TAMPERE UNIVERSITY OF TECHNOLOGY

Tampere School of Business and Technology

ONUR TAMUR

ACHIEVING COST OPTIMIZATION VIA IT INTEGRATION: Case Sel Hoses

Tamur, O.

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ABSTRACT

IT-enabled manufacturing systems are highly valued in current business world

because of the benefits they provide in process optimization and cost reduction and

these systems are increasing their dominance in the industrial markets thanks to the

continuous technological improvements in IT sector. Even though automation

systems require high amount of capital investment, they usually pay back in a short

period of time depending on the values enabled to their users. Thus, major firms

are eager to adopt automated systems in their manufacturing facilities to able to

benefit from these opportunities and guarantee steady growth.

This study is started by the case study of Sel Hoses in collaboration with Tampere

University of Technology. Sel Hoses is a Turkish hose manufacturer that is one of

the biggest suppliers of industrial hoses to European markets and recognized as a

high quality and low cost manufacturer. The industry is eager to adopt automated

cutting process in their manufacturing plants to lower labour costs and optimize the

cutting process by lowering the waste of hoses and Sel Hoses will play a key role

in this implementation if they launch the barcode system on their hose reels. Thus,

the objective of this research is understand the waste reduction opportunities in

hose cutting process by using PC controlled systems and how this project can be

undertaken by following a hand-on approach within the value network to increase

the overall value generated by the major project stakeholders.

The paper gives an insight into different theories that are applied to understand the

cost dynamics of the industry and evaluate the investment decision in terms of the

beneficial return. The above mentioned theories combined with extensive

brainstorming with industry leaders provide managers a helpful tool to evaluate the

long term growth potential of the industry and follow a collaborative strategy to

bring value to the whole business network. Hence, this research attempts to identify

the waste reduction possibilities in hose cutting process by using automated

systems which will lead to lower material costs and process optimization.

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PREFACE

This paper is structured on the case study of Sel Hoses in collaboration with

Tampere University of Technology. The objective of the project was to investigate

the waste reduction possibilities in hose cutting process which is expected to lead

to an increase in the overall value of the business network. Throughout the research

steps, I had chance to understand the dynamics of B2B markets and value

generation in business networks. Personally, it was interesting to use my IT

background in business perspective which provided me an invaluable opportunity

to analyse the technological capabilities with a business mind-set.

I would be glad to thank to the project -

guidance and support throughout the study process, as well as taking part in the

meetings with his meaningful contribution to the discussions. I also appreciate the

collaboration with Sel Hoses, who supported the project from the start and shared

their views and valuable experiences throughout the process. Furthermore, I am

really thankful to my family and friends who supported me during my studies and

motivated to do my best in everything I accomplish.

Tampere, June 2012

Onur Tamur

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TABLE OF CONTENTS

ABSTRACT ______________________________________________________ ii

PREFACE _______________________________________________________ iii

1 INTRODUCTION ____________________________________________ 1

1.1 What is IT Integration? _________________________________________ 1

1.2 Introduction to Sel Hoses _______________________________________ 1

1.3 Objective of the Paper __________________________________________ 2

2 RESEARCH METHODS AND PROCESS ________________________ 3

2.1 Research Method ______________________________________________ 3

2.2 Project Stakeholders ___________________________________________ 4

2.3 Research Process ______________________________________________ 4

3 THEORETICAL BACKGROUND ______________________________ 6

3.1 Return on Investment Analysis __________________________________ 6

3.2 Return on Investment from a Cost Point of View ____________________ 7

3.3 Costing Methods ______________________________________________ 8

4 CASE STUDY – WASTE REDUCTION IN HOSE CUTTING

PROCESS________________________________________________________ 9

4.1 The Problem __________________________________________________ 9

4.2 The Solution _________________________________________________ 10

4.3 The Cost Impact of the Solution _________________________________ 12

5 CONCLUSION ______________________________________________ 15

REFERENCES __________________________________________________ 16

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1 INTRODUCTION

1.1 WHAT IS IT INTEGRATION?

Integration is defined as making applications operate together that were not

intended to work together by passing information through some form of interface to

pursue operational efficiency (Gulledge, 2006). Information management systems

used by global corporations are the biggest example of this trend. By using these

systems companies enable global information sharing and resource management

which increases the productivity in a global perspective. Moreover, IT systems are

widely used in manufacturing, logistics and communication in most of industries.

Since the 1970s, manufacturing firms have increasingly adopted IT-based

production management and resource planning systems (David et al., 2011). After

this impact, IT systems have started to be used intensively in manufacturing

processes. Manufacturing machinery is controlled by embedded systems that are

used to optimize the manufacturing process and increase productivity. They also

have a role to minimize the ambiguity and uncertainty in the manufacturing

process. Differentiated customer needs, high product varieties and increased inter-

dependency across the supply network increase the significance of IT integrated

systems in the market and usage rate is increasing drastically (David et al., 2011).

1.2 INTRODUCTION TO SEL HOSES

Sel Hoses was founded in 1957. Following a rapid growth period, Sel Hoses

dominated the hose industry in Turkey and was recognized as the top provider of

hoses in the market. Sel Hoses is among the top 300 firms in Turkey and top 200

firms in export. Sel Hoses produces all types of hoses in two factories. Rubber

hoses are d c d Ç k zkö ac t , PVC and Thermoplastic copolymer

d ct a ma act d A cı a ac t

The strategy of Sel Hoses is to provide high-quality hoses to its business network at

a low cost. The company operates globally and supplies hoses to plenty of diverse

needs in different industries which enables them to pursue economies of scale. By

having manufacturing plants in Turkey, they are also considered as a low cost

manufacturer which forms strong competitive advantage for Sel Hoses in European

markets against European manufacturers.

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1.3 OBJECTIVE OF THE PAPER

Industrial machinery manufacturers are increasing their significance in the

marketplace which raises the need for hoses. The industry is looking for options to

lower their costs and one of the options to lower the costs is to minimize the waste

in the process. The waste reduction in hoses will be also beneficial for the

environment since it is proven that the material that a hose is made from is not

environment friendly. Therefore, the objective of this paper is to…

…investigate the waste reduction possibilities in hose cutting process by using

IT integrated systems and maximize cost saving to create value for the business

network via the collaboration between supplier and customer.

The structure of the paper is as following. First, the paper gives an insight into the

research method and research process that is followed. Second, the paper discusses

theories on costing methods and return on investment analysis to give an overall

approach for further discussions. Finally, based on these theories and concepts, the

case will be analysed starting with problem identification, possible solutions to the

identified problems and cost saving analysis. These analyses lead the paper to its

key findings and conclusion by unveiling the dilemma in the realization phase.

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2 RESEARCH METHODS AND PROCESS

2.1 RESEARCH METHOD

Research is a widely used term in academic environment and case study research is

a one common area in the field of research. The application of the case study

research is very common in many areas and disciplines such as sociology, law,

medicine, government and management (Zairal, 2007). It is widely accepted

method by professional and it is commonly used by researchers to analyse a

situation or solve a specific problem in business field. The general reason of

conducting management case study research is to better understand complex

business situations such as change in processes (Gummesson, 1993).

A case study research follows well-defined steps in its implementation and it can

be applied by using quantitative and qualitative methods. Quantitative research

methods focus on data generation and relation identification. On the other hand,

qualitative research methods include the researcher, his knowledge and his

experience in the scientific process in order to generate data for higher quality

analysis. Their aim is to cover an in-depth awareness of human behaviour and

the reasons behind the behavioural concepts. According to Gummesson (1993), this

analysis enables the researcher to explore hidden phenomena that do not easily

come up to the surface. There are several categories of case study as well which

are:

Explanatory cases

Exploratory cases

Descriptive cases

First, explanatory cases have the purpose to explain and a w “ w” a d “w ”

questions. They examine the data closely both at a surface and deep level in order

to explain the phenomena in the data (Zainal, 2007). Second, exploratory cases aim

to explore and area that is little known. It is a pilot study or foreplay to a more

rigorous quantitative research. Third, descriptive cases usually just describe a

process or an event without analysis or value judgments. The goal set by the

researcher is to describe the data as they occur (Zainal, 2007). These are the three

most common seen case types and there are plenty of other case types that are

derived from them or a combination of them.

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2.2 PROJECT STAKEHOLDERS

To be able to understand the case study in hand, project stakeholders and their roles

in the business network should be analysed and identified clearly (Chaoji, 2011).

Even though this case study is analysed from the perspective of Sel Hoses, it

directly affects the whole value chain in the industry. Sel Hoses and Intertraco are

the hose and fitting suppliers of PMC Polarteknik respectively. PMC Polarteknik

handles the hose cutting and assembly process by using the machines provided by

Marken which is a leader in cutting technologies and Techhmaflex that specialized

in crimping products. After the assembly process is over, PMC Polarteknik delivers

the hoses to the OEMs to be used in the machinery they manufacture. A more

detailed illustration of the project stakeholders is illustrated in Figure 1 below.

Figure 1. Project Stakeholders.

As seen in the figure above, the value network of industrial hoses used in

machinery equipment is inter-dependent to different stakeholders and supplied

from a wide range of manufacturers with different kind of roles in the process.

Since, Sel Hoses is the hose supplier which is a key part in the hose assembly value

network, the strategy that will be followed by Sel Hoses in the implementation of

the project is vital in to be able to launch the automated cutting process with full

efficiency.

2.3 RESEARCH PROCESS

The starting point of this research derived from the necessity to investigate the

potential waste reduction options in the automated hose cutting process. The

stakeholders have realized that the waste in hose cutting process is quite high and it

provides non- recyclable waste to the environment which is also an extra cost for

the companies. Thus, the resources provide plenty of valuable empirical study

opportunities to be analysed within the value network and then be merged and

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aligned with the theoretical aspects by taking previous researches in the issue into

consideration.

The research was based on existing literature and utilized both existing material

and action science method. Initially, data was mined from the existing publications

and the main means of data gathering were internet, books, academic papers and

meetings with the project stakeholders. By exhaustive analysis of the collected

data, the big picture about the value generation dynamics in the hose assembly

value network has been acquired. Moreover, close connection and communication

with project stakeholders throughout the project enabled the researcher to grasp the

requirements of each party and conduct the research according to their specific

needs. Project timeline is illustrated in more details in Figure 2 below.

Figure 2. Research process timeline.

The research study started officially in the beginning of August 2011. After several

meetings with the supervisors, there has been a visit to tak d ’ facilities to

increase the general understanding of the waste reduction concept and discuss the

implementation strategies with managers. The next step was to negotiate the initial

findings with Sel Hoses and communicate the benefits that would be provided to

them if they implement the barcode system in their hose coils. The research process

continued with fruitful discussions, improvement suggestions and combining the

ideas with theoretical concepts. Finally, the collected data has been analysed and

the writing has been finalized according to the key findings.

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3 THEORETICAL BACKGROUND

3.1 RETURN ON INVESTMENT ANALYSIS

The impact of globalization and reduced technology cycles creates a volatile

business environment. Thus, strategic investment decisions play a key role in

pursuing success for a company (Krychowski & Quelin, 2010). In B2B world,

companies purchase assets or services to obtain further benefits which can either be

financial or non-financial. The return on investment analysis directly affects their

success because it is vital to know that the benefits they will receive from their

investment are greater than the value they invested. Hence, investment decisions

can also be identified as current sacrifice for future benefits (Butt et al., 2011). The

investment decisions and their outcome are illustrated in more details in Figure 3.

Figure 3. Investment decision.

Investment decisions are usually evaluated by using discounted cash flow based

methods, such as the internal rate of return (IRR) or net present value (NPV) to be

able to compare the benefits by considering the current value of money

(Krychowski & Quelin, 2010). However, there has been a drastic change in the

understanding of the benefits in the current business environment recently.

Companies realized that non-financial returns are also as important as the financial

ones and directly affects the performance of the firm and its brand value. The

increased amount of investments made in corporate social responsibility projects

can be considered as an example for this trend.

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3.2 RETURN ON INVESTMENT FROM A COST POINT OF VIEW

As it was mentioned in the previous section, benefits of an investment decision can

be either financial or non-financial. Even though non-financial aspects are

increasing its significance in the current business market, companies still take

investment decisions mainly for financial returns. Financial benefits provided by an

investment can be analysed by using the profitability analysis framework. The

financial benefit provided by an investment will eventually increase profit and the

possible ways to increase profit can either be done by increasing price, increasing

sales volume or decreasing costs. The profitability analysis framework used for

assessing the benefits of an investment is illustrated in the Figure 4 below.

Figure 4. Beneficial return from financial perspective.

Reducing costs and optimizing the business process are the biggest challenge for

companies nowadays. Most of the B2B companies tend to form long term relations

with their customers to guarantee the sales of their manufacturing output which

limits the growth potential in saturated industries. Thus, cost reduction is the key

target for companies to increase their profit margin and achieve operational

efficiency. As seen in the figure above, cost related benefits that an investment

provides can be related to either fixed or variable costs. Fixed costs are mainly

linked to rent, machinery and salaries and they can be reduced by making some of

these assets obsolete. Variable costs are dependent on the volume output and they

can be reduced by decreasing the raw material need, lean manufacturing or

manufacturing process improvements. Cost reduction gives a long term vision for

companies to see the further development possibilities internally. Hence, it is quite

common that companies make investments to reduce costs in their manufacturing

process.

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3.3 COSTING METHODS

In the fast changing business landscape, organizational learning and knowledge

management are key steps to success and they are vital to leapfrog the competition

in the market (Huber 1998). Thus, management accounting tools are important

service functions for companies to gather the financial information they need to be

used in decision making (Lyly- t a 2010) C t g a k c c t

management accounting and it is extensively used in pricing by adding a profit

margin to the total cost of a product. Even though it is not an appreciated pricing

method anymore, knowing how much a product costs is critical to know the

bottom-line for prices to guarantee profitability. It is also an important concept for

product developers to understand the cost implications of their actions (Lyly-

t a 2010) Costing methods are analysed according to their cover of

cost areas in Figure 5 below.

Figure 5. Costing methods

Contribution costing is a costing method that focuses on the variable costs of a

product and neglects the fixed costs. Despite its simplicity, contribution costing is

widely accepted in retail business and many industrial companies (Lyly-

et al. 2010). Full costing enables companies cost their products by taking all the

expenditures (fixed and variable) of a company into consideration (Lyly-

t a 2010). It is considered as an advanced method compared to

contribution costing because it takes the overhead costs into account. Activity-

based costing is a costing model used for identifying the activities of a company

and assigning each of them to products or services. Activity-based costing has been

developed to assign more indirect costs to direct costs to increase accuracy and it

mainly focuses on taking fixed costs into account while making costing analysis.

The above mentioned models are widely used and accepted in the industry.

However, there are many companies that develop their own cost model according

to their own needs or use hybrid models derived from the above mentioned costing

methods.

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4 CASE STUDY – WASTE REDUCTION IN HOSE CUTTING

PROCESS

4.1 THE PROBLEM

Industrial hoses are widely used in automotive, machinery or similar industries to

complete the functionality of a machine to execute its tasks. Thus, hoses are

considered as a complementary part of the products and used almost in every

product to transmit oil, water or air. Like all industries, hose industry has also

industry specific dynamics that evolve by time depending on the arising needs and

technological improvements.

Hoses that are rolled in the coil are not one piece of hose. Hose coils usually

contain 3-4 industrial hoses that are tied to each other in the connection points and

rolled to the reels. There is a pack list on the hose coil that shows the total length of

the hoses in the reel but it does not specify the order of the hoses because it has no

significance for the buyers. Total length of the hose coil is used for price

calculations. Hose coils and their contents are illustrated in Figure 6 below.

Figure 6. Different hose coils and their content.

As seen in the figure above, the hose coils contain different lengths of hoses. The

pack list attached to the coil does not show the order of hoses in the coil because in

the manual cutting process it does not create any value for the buyers in terms of

increasing their cutting speed or optimizing the cutting process. Recently,

automation is increasing its dominance in many industries and companies are eager

to make investment in automated systems to lower their labour costs and optimize

their manufacturing process. This trend is also seen in hose industry and industry

leaders started to realize that there is important improvement potential in process

optimization and cost saving that can be enabled by using automated cutting

systems.

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Marken is one of the leading companies in producing automated systems in cutting

technologies and specializes in standard and custom cutting machines for hose,

wire, and cable industries. The Marken cutting machine works with a cut list and

starts processing the cutting in order to the list entered in the system. The

unordered pack list provided on the hose coil creates an obstacle for the automated

cutting process. The machine starts cutting the hose and marks the hose with a

unique stamp that contains the length of the cut part in the beginning of the process

but if the remaining hose is not long enough for the hose in the list, the cut part

goes to waste because it is already printed for a different length. The problem in the

cutting process is illustrated in details in Figure 7.

Figure 7. Problem in hose cutting process

The above mentioned problem is the biggest challenge in automated hose cutting

process and it needs to be solved by the contribution of all stakeholders in the

process. The decreased amount of waste will be appreciated by external

stakeholders because the automated process will enable companies to save costs

and optimize their hose cutting process by increasing the efficiency which will

increase the overall value of the business network.

4.2 THE SOLUTION

The barcode system that will be implemented on the hose coil plays the most

critical role in the project which will be provided by the hose manufacturer Sel

Hoses. By reading the barcode on the hose coil using a barcode reader integrated to

Marken machines, the system will acquire the pack list information in order. This

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feature will enable Marken machines to reorder the cut list according to the pack

list in hand to be able to minimize the waste and optimize the cutting process.

Scanning process has been illustrated in details in Figure 8 below.

Figure 8. Scanning a hose reel

Sel Hoses need financial resources and time to be able to implement this

technology in their facilities but when they are able to provide this offering, they

will improve their significance as the low cost supplier in the market. The current

agreements of Sel Hoses with its customers state that the cost of the hose wasted in

t c t m ’ ac t during the cutting process is covered by Sel Hoses. Thus,

the implemented solution will significantly decrease the spending on wasted hoses

which will lead to an increase in profitability with minimum effort.

To minimize the hose waste in the cutting process, an algorithm will be

implemented on the Marken cutting machines. The barcode on the hose reels will

be read by the barcode reader which is connected to the Marken cutting machine

that will reorder the cut list according to the pack list information by using a PC-

controller in order to minimize the waste in the cutting process. After the cut list is

re-ordered, cutting process will start in an optimized way and marking the hoses

with their lengths before the cutting process will not lead to any waste of hoses or

slow down the process. Optimized hose cutting process is illustrated in details in

Figure 9 below.

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Figure 9. Optimized hose cutting process.

The proposed solution will significantly increase the profitability of Sel Hoses. As

they will not be paying for the hose waste of their customers anymore, they will be

able to get the return on their investment in a short period. Moreover, the customers

will be able to achieve operational efficiency because they will not be creating and

storing hose waste anymore in their facilities. By the IT enabled solution provided,

customers will be able to process more hoses in the same amount of time because

they do not need to spend time on activities related to hose waste anymore which

will lead to advanced business process in the production of the machinery.

4.3 THE COST IMPACT OF THE SOLUTION

It is important for companies to understand the financial benefits provided to them

via optimized hose cutting process to be evaluate the financial impact of their

investment in the new Marken cutting machine. To be able to calculate the cost

savings provided by the optimized cutting system, different types of hoses with a

total length of 1,000,000 meters are used as the basis of analysis which is given in

Table 1 below.

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Table 1. Hose types

Hose Type Total Length (meters) Price per meter (€) Average Length (meters)

1/4” 500 000 1.00 70

1/2” 250 000 2.00 66

3/4” 150 000 4.00 55

1” 75 000 8.00 45

3/2” 25 000 15.00 40

As seen in the table above, Sandvik Mining Company uses different variety of

hoses in the machinery manufactured. The most commonly used hose type is the

1/4” hose which is also the cheapest one and the price increases relatively to the

radius of the hose. The cost saving analysis depending on the hose information in

hand is in Table 2 below.

Table 2. Cost saving analysis

Hose Type Price (€) Number of Hoses Costs (€) (1,5 meters waste) Costs (€) (0,1 meters waste)

1/4” 1.00 7 143 10 714 714

1/2” 2.00 3 788 11 364 758

3/4” 4.00 2 727 16 364 1 091

1” 8.00 1 667 20 000 1 333

3/2” 15.00 625 14 063 938

TOTAL 72 504 4 834

The hose coils are formed by connecting hoses in different lengths and average

length of hose varies in each type. Number of hoses in each hose segment is

calculated by dividing the total length to the average length. Depending on the data

provided, it is known that the average cut length is 3 meters and the average waste

is 1.5 meters per hose. Cutting optimization software that is planned to be

implemented in Marken machines targets to eliminate the waste in the cutting

process. However there is still possibility that some waste can occur in

extraordinary occasions so 0.1 meter waste per hose is used in the calculations.

With the above mentioned data in hand, it is now possible to calculate the cost that

can be saved by comparing the two options available which are highlighted in the

last columns in Table 2. Accumulated value and the cost saving percentage are

available in Table 3 below.

Table 3. Cost saved by the automated system

Cost Saving (€) 67 670

T ta W t t Batc (€) 2 575 000

Percentage 2.63%

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As seen in the table above, it is possible to save 67,670 Euros per year by using the

optimized cutting process which is 2.63% of the total worth of the batch. This

result clearly states that the payback period will be considerably short by

considering that the amount of hose that is used by Sandvik Mining Company in a

certain period and their growing position in the market.

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5 CONCLUSION

The most important target of every firm is to make profit which can first ensure

survival and then growth. The cost reduction possibilities provided by minimizing

the waste in the manufacturing process have direct effect on profitability of a

company as well as the brand value by lowering the waste of environmentally

harmful raw materials. The current business environment and the mind-set of the

customers are forcing companies to do business in an environment friendly way

and this approach increases the overall worth of the whole industry if applied

successfully.

The objective of this study was to understand and evaluate the waste reduction

opportunities in hose cutting process by maximizing the collaborative efforts

within the value network which will lead to an overall value expansion. Sel Hoses

will invest in the automated IT solution which will be implemented on cutting

mac t c t m ’ ac t The new system target to eliminate the hose

waste in the cutting process that will create value for both suppliers and customers

in terms of cost and time saved. To achieve the objective, the work first introduced

costing methods, return investment analysis and investment decision made for

achieving cost reduction. Then, it focused on analysing the case study on

automation in hose cutting process from the perspective of Sel Hoses by

highlighting their role in the project and how cost saving will increase the overall

value of the business network.

To sum up, the outcome of the case study is that implementation of automated hose

cutting process in the industry will uncover plenty of opportunities for Sel Hoses to

utilize. Sel Hoses w ’t d t c t cost of their c t m ’ waste

anymore so they will increase their profitability drastically by lowering their

variable costs. The amount saved on variable cost will payback their investment in

a short period of time. This investment will create great opportunity for Sel Hoses

for further growth and it will highlight their position as the low cost provider in the

market significantly. Moreover, the solution will impact the overall value of the

business network because their customers will advance their operational efficiency

by eliminating the time spend on hose waste related activities. Thus, it is vital for

Sel Hoses to evaluate the case thoroughly by conducting win-loss analysis and take

part in the paradigm shift to guarantee long-term success in the market.

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REFERENCES

Butt, M., Saddar R., Shafi, H., Rehman K., Rehman R., Shoaib, H., (2011),

I t ’ mma: F dam ta B a I tment Decision,

Journal of Economics and Behavioural Studies Vol. 3, No. 2, pp. 122-127

Chaoji, P. (2011). Understanding and Communicating Customer Value in Business

Markets. Selected Graduate Papers, Lyly- , , Ma t , M ,

Nokelainen, S., Tampere University of Technology

David Xiaosong Peng, Gensheng (Jason) Liu, Gregory R. Heim, (2011),"Impacts

of information technology on mass customization capability of

manufacturing plants", International Journal of Operations & Production

Management, Vol. 31 Iss: 10 pp. 1022 - 1047

Gummesson, E. (1993). Case study research in management. Method for

generating qualitative data. Stockholm University. pp. 4, 6

H b , G g “S g b tw ga zat a a g a d creativity

innovation”, C at t a d I novation Management, Vol. 7, No. 1,

(1998): 3-8;

Krychowski, C., Quelin, B. (2010), Real Options and Strategic Investment

Decisions: Can They Be of Use to Scholars? Academy of Management

Perspectives

Lyly- , (2010) C b k “Ma ag g O rative Sales and

S c g G ba B2B Ma k t ” Tam U t T c g

Thomas Gulledge, (2006),"What is integration?", Industrial Management & Data

Systems, Vol. 106 Iss: 1 pp. 5 – 20

Yin, R. (1984). Case study research: Design and methods (1st ed.). Beverly Hills,

CA: Sage Publishing.

Zainal, Z. (2007). Case study as a research method. Jurnal Kemanusiaan bil.9