Mathematical Modeling of Feature Conversion
International Journal of Engineering Materials and Manufacture (2017) 2(1) 1-10
https://doi.org/10.26776/ijemm.02.01.2017.01
H. Ullah and A. Asiyah
Mechanical Engineering Programme
Faculty of Engineering, Universiti Teknologi Brunei
Jalan Tungku Link, Brunei Darussalam
E-mail: hamid.ullah@utb.edu.bn
Reference: Ullah, H. and Asiyah, A. (2017). Design and Development of Mobile Phone using Quality Function Deployment.
International Journal of Engineering Materials and Manufacture, 2(1), 1-10.
Design and Development of Mobile Phone using Quality Function
Deployment
Hamid Ullah and Asiyah Ali
Received: 22 November 2016
Accepted: 17 February 2017
Published: 31 March 2017
Publisher: Deer Hill Publications
© 2017 The Author(s)
Creative Commons: CC BY 4.0
ABSTRACT
This paper presents design and development of mobile phone where quality function deployment approach is used
to convert customer needs into design specifications. Customer needs and their relative importance are identified
through the analysis of customer survey. Technical requirements that could fulfill the customer needs are established
and a relationship matrix is developed between the customer needs and the technical requirements. The
relationship matrix is then converted into the house of quality matrix. Using output from the house of quality,
concepts of a mobile phone are generated. Concept generation is followed by concept selection where finally an
improved model of a new mobile phone is presented.
Keywords: Customer needs, Technical requirements, House of Quality (HOQ), Quality Function Deployment
(QFD), Concept generation, Concept selection.
1. INTRODUCTION
Yoji Akao is considered as the father of QFD who introduced the concept of QFD in Japan in 1966. The Japanese
phrase “hinshitsu kino tenkai” matches to “Quality Function Deployment”, where “function” corresponds to the
analysis of the business process to enhance the quality of products in the development process (Akao and Mazur,
2003). The first use of QFD was made in 1972 by Professor Mizuno to Mitsubishi’s Kobe shipyard site in the design
of super tankers (Martins and Aspinwall 2001).
Company’s success lies in knowing the customer needs and foreseeing the modifications required in the already
available products (Soota et al. 2008). Innovation-based companies may push a technology into the market by
those who design the product to those who produce it and to those who distribute it in the market (D.R. Kiran,
2017). Therefore, it is very essential for any firm to develop the quality of its product (or service) by bridging the
gap between product quality and customer satisfaction (Lin 2007). QFD is the best tool to convert the customer
preferences into quality attributes. It is a powerful development tool for achieving product development,
improving product quality, reducing time to market, and decreasing the cost of production. It is a famous design
tool that considers systematically the customer needs and preferences in product planning and therefore has good
applications in manufacturing and service organizations (Dijkstra and Bij, 2002). QFD is a method for developing a
quality design by incorporating the consumer demands into design specifications (Akao 1990). Basically, it is aimed
to fulfill customer preferences of the product (Kasim et al., 2009). It is a customer driven technique (Guinta and
Praizler, 1993). It is broadly spreading in business organizations because of its wonderful usefulness.
QFD is a planning tool that guides the design, manufacturing, and marketing of products (Chan and Wu, 2003).
It uses planning matrices that connect customer requirements, design and target specifications, and competitive
performance into one graph. It is a helpful tool that facilitates planning, decision-making, and communication in
the product development phase. At its heart is the ‘Voice of Customer’, which gives it the unified stage throughout
the product planning and development process. It takes the ‘Voice of Customer’ throughout the product
development process out into the market place. The resulting new product will delight the customers and outshine
the competition provided the QFD is done thoroughly (Pun et al., 2000).
mailto:hamid.ullah@utb.edu.bn
Design and Development of Mobile Phone using Quality Function Deployment
2
QFD reduces the gap between organization and its customers. To achieve the objective, it is necessary to know the
customer needs so that, these could be considered from the early stages of the planning process. It involves
implementing technological solutions, by experts, to determine the customer requirements. QFD provides
significant advantages, for example: to reduce design and development time, to spotlight the satisfaction of
customers, and to increase communication at all levels of an organization (Kasim et al., 2009). It speeds up changes
during the various phases of product development. It can assist product designers to identify important design
attributes and also provide suggestions for possible improvements in these attributes (Liu, H-T and Cheng, H-S.,
2016). Because of these advantages, it has become an accepted support to the product planning and development
process (Akao and Mazur, 2003; Chan and Wu, 2002; Chan and Wu, 2003; Day, 1993). It is a historically proven
means of guiding process development by using technical performance measures for a systematic organization of all
independent variables and their interrelationships. It is cited as a key facilitating method in simultaneous
engineering (Menon et al., 1994), and is the most extensive implementation of Total Quality Management (Sage,
1992).
The crucial step in QFD is to derive the prioritization of design specifications from customer needs for a product
(Yan and Ma 2015). The successful implementation of QFD lies in the accurate capturing and prioritization of the
customer requirements (Kamvysi et al. 2014). While the new customer needs have a major effect on the product
successfully, the traditional requirements may not be forgotten by the product’s designers (Ashtiany, M.S, and
Alipour, A., 2016). The identification and prioritization of customer needs could also be achieved through
integration of Kano's model, Analytical Hierarchy Process (AHP) technique and QFD matrix (Hosna Pakizehkar et
al., 2016). QFD therefore has been broadly spreading in the industrial and business organizations because of its
wide and diverse usefulness. The key planning part of QFD is the House of Quality (HOQ). The customer needs
are called ‘WHATS’ while the technical specifications are called ‘HOWS’ in the HOQ matrix. The paper is
organized as follows: section 2 describes methodology. Section 3 mentions mission statement of the product. It is
followed by identifying customer needs and establishing their relative importance in section 4. Defining Technical
requirements is presented in section 5. Building House of Quality for mobile phone is discussed in section 6. Section
7 describes ranking of technical requirements which is followed by concept generation and concept selection
presented in sections 8 and 9 respectively. At the end, discussion and conclusion are presented.
2. METHODOLOGY
Survey questionnaire is designed to get feedback from the end users’ of mobile phone in Brunei Darussalam with
respect to their preferences from a new mobile phone. The survey questionnaire consists of twenty (20) questions:
eleven (11) multiple choice questions, one (1) ranking question and 8 open ended questions. The questionnaire is
distributed online to the customers. The web link of the questionnaire is shared through email, social media such as
Facebook and WhatsApp messages. Out of 100 mobile phone end users, response is received from 85 respondents.
Data collected is interpreted in terms of customer needs. Relative importance is assigned to the customer needs on
a scale of 1 to 5 (where 1 indicates the least important need and 5 indicates the most important need). The
customer needs, their relative importance, and technical requirements are used in building HOQ for the mobile
phone. The input from the HOQ is used in concept generation phase of mobile phone. Concept generation is
followed by concept selection of mobile phone. CAD model of the improved mobile phone is presented.
3. MISSION STATEMENT
A mission statement provides a basic functional description of the product, identifies its target market, and also
specifies its business goals. The mission statement for the mobile phone is provided in Table 1.
4. IDENTIFYING CUSTOMER NEEDS AND ESTABLISHING THEIR RELATIVE IMPORTANCE
Aim of this phase is to identify the customer needs and requirements and to effectively communicate to the product
design and development team. The idea behind the technique is to create high-quality information guide that runs
directly between the developers of the product and the customers in the target market. This idea is made on the
principle that those responsible for the direct control of the details of the product must interact with customers and
also experience the use environment of the product. From the survey questionnaire distributed among the end
users, the data collected is compiled into the Voice of Customer (VOC). The VOC is converted into customer
needs. There are different terminologies used for customer needs. These include customer wants, customer
preferences, customer choices, customer wishes, customer expectations, and customer requirements. The customer
needs are called ‘WHATS’ in the HOQ matrix and acts as a first building block in building the HOQ and is the most
important phase of QFD. Once the customer needs have been identified, their relative importance is determined.
The value of relative importance of the customer need is necessary to obtain the value of the weighted average for
the relationship matrix in the HOQ. The customer needs and their relative importance are shown in Table 2. The
average value of relative importance shown in Table 2 is assigned on the basis of customer feedback. The features
are rated on a scale of 1 to 5.
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Ullah and Asiyah (2016): International Journal of Engineering Materials and Manufacture, 2(1), 1-10
3
Table 1: Mission statement for the mobile phone.
Product Description Mobile phone with basic and advanced features
Key main objectives
Product introduced in 1th Q of 2017
50% gross margin
10% share of mobile phone market by 2020
Primary market
Executives
Youngsters
Students
Secondary market
Middle Class
Casual users
Assumptions
Water proof
Solar chargeable
Touch screen
Dual Sim
Light weight
Stakeholders
Users
Design department
Manufacturing / production department
Sale force and service center
Legal department
5. DEFINING TECHNICAL REQUIREMENTS
The next step in the QFD technique is to identify a list of suitable technical requirements that could meet the
customer needs. These requirements translate the customer needs into quantifiable terms. These requirements
define how to respond to the customer needs. The technical requirements need to be measureable so that it could
be determined that the customer needs are satisfied. At least one technical requirement is identified for each
customer need. Other terminologies used for technical requirements are: engineering characteristics, quality
attributes, design requirements, and voice of company. The technical requirements are called ‘HOWS’ in the HOQ
matrix. Technical requirements that could meet the customer needs are provided in Table 2.
Table 2: Customer needs (their relative importance) and technical requirements.
No. Customer needs
Relative importance of
customer needs
Technical requirements
1 High camera resolution 4.88
High MP camera resolution
LED flash
Autofocus
2 External memory card slot 4.77
Micro SD (secure digital) card slot
Pin ejection button
3 High internal memory 5.12
Built in storage
High RAM
4 Battery is removable 4.5
Non built in battery
High battery capacity
Fast charging battery
5 Wireless charger 4.38
Fast Wireless charging pad
Travel adapter
Micro USB adapter
6 Long lasting battery life 5.31
Non built in battery
High battery capacity
Fast charging battery
7 Fast operating system 5.23
Latest OS
High RAM
8 Durable screen 4.36
Corning Gorilla Glass 4
IP 68 material (dust and water
resistant)
Tempered glass screen protector
Design and Development of Mobile Phone using Quality Function Deployment
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9 Large screen 4.12
Screen to body ratio
10 Waterproof 4.96
IP 68 material
Plastic coated speaker
Rubber protection USB port
11 Dual SIM card slot 3.48
Single nano SIM card slot
Dual SIM card ( MMC slot)
Pin ejection button
12 Speaker on the front 4.04
Plastic coated speaker
Equalizer software
13 Stylus pen 3.9 Stylus pen
14 Fingerprint lock 3.72
Fingerprint sensor
Home button
15 Stand at the back of phone 3.94
Ring holder/stand on back cover
16 Holder on the phone 2.7 Ring holder/stand on back cover
17 Radio 3.04
Frequency network software
Plastic coated speaker
18 Different colors of back cover 3.11 IP68 material
19 Projector 3.06
Built-in Digital Light Processing (DLP)
projector
6. BUILDING HOUSE OF QUALITY FOR MOBILE PHONE
Using the above data (customer needs, their relative importance and technical requirements) a HOQ is built. HOQ
is an important element of QFD. It gives a central part to how well the technical requirements address the customer
needs. The HOQ is shown in Figure 1. The customer needs (WHATS) are shown in the 2
nd
leftmost column of the
HOQ matrix while the technical requirements (HOWS) are shown in the topmost row in HOQ. The customer
needs are followed by their relative importance presented in the 3
rd
leftmost column of the matrix. The cells after
the column for the relative importance show the interrelationship between the customer needs and the technical
requirements. There may be ‘no relationship’, ‘weak relationship’, ‘medium relationship’, or ‘strong relationship’
between the customer needs and the technical requirements. The weights assigned to these relationships are 0, 1, 5,
and 10 respectively. The values of 1, 5 and 10 are shown in the HOQ matrix by the symbols shown in Table 3. A
blank cell in the matrix shows ‘no relationship’ between the customer needs and the technical requirements.
Purpose of the interrelationship is to translate the customer needs into the technical requirements. This
interrelationship matrix is a two-dimensional matrix containing cells that relate to the combinations of individual
customer need and technical requirement.
After all calculations have been made, the top five rankings appears to be IP68 casing, micro SD card slot, non-
built-in battery, high battery capacity, and plastic coated speaker respectively. The roof of the HOQ shows the
correlation among the technical requirements. The plus (+) sign in a cell of the roof shows that improving a
particular technical requirement causes improvement in the technical requirements of the corresponding cells. A
minus (-) sign could be used in a cell if improving a technical requirement causes deterioration in the technical
requirements of the corresponding cells. The symbols used for the interrelationship between the customer needs
and the technical requirements are shown in Table 3. The correlation among the technical requirements obtained
from the roof of HOQ is shown in Table 4.
7. RANKING OF TECHNICAL REQUIREMENTS
It is the final element of the HOQ. It is achieved from the weighted average of the technical requirements in the
interrelationship matrix of the HOQ. It provides a summary of the conclusions drawn from the information
contained in the entire matrix of the HOQ. It presents a priority score and ranks all the technical requirements in
the HOQ matrix. The ranking of the technical requirements is shown in the HOQ matrix.
Table 3: Legend of symbols for House of Quality.
Strong Relationship 10
⃝ Medium Relationship 5
Δ Weak Relationship 1
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Figure 1: House of Quality
Design and Development of Mobile Phone using Quality Function Deployment
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Table 4: Correlation among technical requirements.
High camera resolution
Built in storage
High RAM
High battery capacity
LED flash
Built in storage
Micro SD external slot
Pin ejection
High RAM
Frequency network
Built in projector
High battery capacity
Fast charging battery
Fast wireless charging pad
Travel adaptor
Micro USB adapter
Corning gorilla glass 4
IP 68
Screen ratio
IP 68
Tempered glass screen protector
Plastic coated speaker
Rubber protection USB port
Plastic coated speaker
Equalizer software
Fingerprint lock
Home button
8. CONCEPT GENERATION
Mobile phone concepts are generated using the input from the HOQ. Three concepts of the improved mobile
phone are generated. All the three concepts are designed in rectangular shape. Based on the input from end users
of mobile phone, features such as front and back camera, speaker, switch button, ring holder are included in the
concepts. Concept 1 shown in Figure 2 has the features of home button, screen and front camera. On the right side,
there are volume and switch button. On the back side of the mobile phone, the back camera is circular in shape
and there is a dual flash and ring holder attached to the back cover. The battery is removable and there is external
memory card and SIM card slots covered by the back cover of mobile phone. The speaker is designed on the
bottom side of the mobile phone together with the USB charging port. On the top side of the mobile phone, there
is a hole for earphone plug.
In concept 2, shown in Figure 3, the back side of the mobile phone is almost the same as that of concept 1. The
camera shape is rectangular. The switch button is on the right of the top side. The speaker is at the front of the
mobile phone. There are dual flash for both front and back cameras. The home button is rectangular in shape
while, it is circular in case of concept 1. The external memory card and SIM card slots are at the left side of the
mobile phone. Concept 3 is shown in Figure 4. There are few similarities between concept 2 and concept 3. The
difference between concept 3 and concept 2 is that the front camera is larger in size and the ring holder is circular
in shape.
9. CONCEPT SELECTION
Final concept is selected based on the criteria shown in Table 5. The evaluation matrix provides concept 2 to be
the final best concept. The selected concept is modeled using Autodesk Inventor Professional 2015. The design
specifications of the final concept are presented in Table 6. The final concept could be considered for subsequent
development activities.
Ullah and Asiyah (2016): International Journal of Engineering Materials and Manufacture, 2(1), 1-10
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Figure 2: Concept 1
Figure 3: Concept 2
Design and Development of Mobile Phone using Quality Function Deployment
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Figure 4: Concept 3
Table 5: Evaluation matrix for concept selection.
Criteria Concepts
1 (Datum) 2 3
Aesthetic + 0
Cost - -
Weight - +
User friendliness + 0
Durability + 0
Easy to manufacture - -
Safety 0 0
Sum "+" 3 1
Sum "-" 3 2
Sum "0" 1 4
Net score 0 -1
Ranking 1 2
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Table 6: Design specifications of the concept selected.
Dimensions 142 mm x 70 mm x 08 mm
Body build
Corning gorilla glass 4: the toughest glass material for mobile phone,
IP 68 material
Screen size 58 mm x 115 mm
Operating system Android OS, Marshmallow: latest updated operating system
CPU Quad-core 2.3 GHZ
Memory card slot Micro SD up to 200 GB
Internal storage 128 GB with 4 GB RAM
Camera
Front camera: 08 MP with dual LED flash
Back camera: 13 MP with autofocus and dual LED flash
Battery Removable battery with a capacity of 3000 mAh
10. DISCUSSION AND CONCLUSIONS
Mobile phone is designed and developed using QFD technique. Customer requirements (Voice of Customer) of a
new mobile phone are identified by conducting a market survey. VOC is converted into customer needs. Customer
needs and their relative importance are identified. HOQ for the mobile phone is built. Final specifications of the
mobile phone are established. In the design specifications, the dimensions of the mobile phone are 142 mm x 70
mm x 08 mm. The screen size is 115 mm x 58 mm which is about 70% of the front side of the mobile phone. The
mobile phone is operated with the latest operating system which in Android Marshmallow version 6.0. Quad core
2.3 GHz is chosen for the fastest processor of the mobile phone.
To be long lasting or durable, Corning Gorilla Glass 4 is specified for body of the mobile phone. IP 68 material
is specified for the mobile phone to make it waterproof. External memory card slot is provided for more efficient
storage. Micro Secure Digital (MSD) card is specified to fit up to 200 GB, the maximum capacity for external
storage. The slot is incorporated with SIM card slot. The mobile phone can hold two SIM cards at the same time
where the memory card slot is used for second SIM card. High camera resolution is included. In order to get good
resolution, both front and back cameras have their own dual LED flash. They have high mega pixel for better
resolution. A removable battery in the mobile phone is located at its back covered by the back cover. It has high
capacity of 3000 mAh so that the mobile phone can function longer. There is a ring holder attached to the back
cover of the mobile phone. It acts as a convenient and safe grip to prevent falling of the mobile phone while in
use. It can also be used as a stand while watching videos by the mobile phone.
In conclusion, QFD is very important method for development of new products according to customer needs.
It helps to improve the existing product by taking into account customer requirements and is therefore a very good
planning tool. It is worth to mention that the survey questionnaire is distributed within various universities in
Brunei Darussalam. Majority of the respondents are students. In future research, diverse users of mobile phone
could be considered for taking their input to develop mobile phone. Also, instead of relying only on survey
questionnaire, other modes of data collection, for example, one-on-one interview, focus groups, and observing the
product in use could be considered.
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