• Journal of ILASS-Korea
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• v.17 no.3
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• pp.140-145
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• 2012

Recent common-rail injector of a diesel engine needs more smaller nozzle hole to meet the stringent emission regulation. But, small nozzle hole diameter can cause nozzle coking which is occurred due to the deposits of post-combustion products. Nozzle coking has a negative effect on the performance of fuel injector because it obstructs the fuel flow inside a nozzle hole. In this study DFSS (Design for six sigma) method was applied to find the effect of nozzle design parameter on nozzle coking. Total 9 injector samples were chosen and tested at diesel engine. The results show that nozzle hole diameter and K-factor have more effect on nozzle coking than A-mass and hole length. Large hole diameter and A-mass, small hole length and K-factor give more positive performance on nozzle coking in these experimental conditions. But, a performance about nozzle coking and exhaust gas emission shows the opposite tendency. Further study is needed to find the relation between nozzle coking and emission characteristic for the optimization of injector nozzle design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.280-281
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• 2008

In pursuit of decreasing noise and vibration, the electromagnetic active control mount(ACM) is developed which is corresponding with the tendency of greater fuel efficiency, higher engine power and lower lightweight vehicle. In process of developing the ACM, making patent searches and benchmarking are performed first, and then robust mount design which is reflected on the users' demand through Design For Six Sigma(DFSS) is carried out. The manufactured prototype of ACM is tested in various environmental conditions for the purpose of ensuring the performance quantitatively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.476-477
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• 2014

This paper relates to the automotive silencers reduce noise generated from the actual vehicle for the activity is based on was worth. To do this, the noise from cars to distinguish them by category, characteristics of turbo charger was designed to reduce noise. In order for the design of acoustic modeling using line dynamics, was analyzed using In house & the commercial software programs. Silencers have about several basic elements. Expand, collapse, perforated plate, and the combination are the basic reactive or dissipative elements. Finally, DFSS(design for six sigma) method was designed. and it was verified in vehicle test. The new developed silencers showed good performance vehicle test results. also, the net cost also indicated excellent results compared with other company.

• Journal of Korean Society for Quality Management
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• v.38 no.4
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• pp.531-539
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• 2010

Mega-Y project is very important for a company to gain a competitive advantage in markets or to achieve drastic change in the internal processes. It stems from the company strategy and annual management goals or key performance measures, and is proceeded by the cross-functional team. This paper presents the success factors and implementation process of the Mega-Y projects. The implementation process is presented in 5 steps, including project selection, cross-functional team building, establishment of the master plan, development and execution of sub-projects, and project completion. A case study on the cost reduction project of aircraft development is presented to help for the practitioners to deploy the implementation process introduced in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.357-360
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• 2011

In these days, the passenger vehicles usually have equipped various comfort & security systems to appeal to customers. And then, the importance of emotional quality gives added weight to the noise performance of those system devices. Door inside handle system is one of the most popular devices for passenger. This paper shows developing process about the operating sound of door inside handle. We used DFSS process to develop the door inside handle snap back sound and confirmed the improvement.

• Communications for Statistical Applications and Methods
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• v.16 no.3
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• pp.449-461
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• 2009

Higher sigma quality level is generally perceived by customers as improved performance by assigning a correspondingly higher satisfaction score. The process capability indices and the sigma level $Z_{st}$ ave been widely used in six sigma industries to assess process performance. Most evaluations on process capability indices focus on statistical estimation under normal process which may result in unreliable assessments of process performance. In this paper, we consider statistical estimation for bivariate VPCI(Vector-valued Process Capability Index) $C_{pkl}=(C_{pklx},\;C_{pklx})$ under Marshall and Olkin (1967)'s bivariate exponential process. First, we derive some limiting distribution for statistical inference of bivariate VPCI $C_{pkl}$. And we propose two asymptotic normal confidence regions for bivariate VPCI $C_{pkl}$. The proposed method may be very useful under bivariate exponential process. A numerical result based on our proposed method shows to be more reliable.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.149-156
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• 2011

The performance measurement of construction firms is considered as a competitive advantage to develop and improve their performance to have place in the market and stay able to face the continuous challenge. Egyptian construction firms (ECF) started recently to adopt quality management system (QMS) as a way to develop and improve their performance as previous studies showed. However, measuring that performance to include all the firm's aspects in a competitive way is a crucial process for the ECF's culture. The research is trying to indicate the role of the QMS implementation in measuring performance (MP) through developing a model for measuring performance on the organization level, and explore its impact on the organization that adopt quality management system. This model is based on specific elements and their related indicators which have been derived from national approaches and models of measuring performance (benchmarking, quality awards and six sigma).Elements determination and the status of their real practice has been investigated through a questionnaire to a representative sample of ECF. This model determines the performance level (PL) of the organization that measured by a mean of a point system. Weights of the elements in the point system considered both the elements' importance in the international models and its real practice in the Egyptian construction firms. So, the final outcome of the model reveals the level of firm performance that helps the firm to identify the weak points against the strong ones, Confirm the priorities and identify new opportunities for developing, and Check the position of the company in the market among the others. Another questionnaire has been developed to be distributed on a group of Experts on measuring performance for the purpose of model validation. The majority of surveyed experts agreed that the proposed model can be applied effectively.

• Journal of Information Technology Services
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• v.10 no.3
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• pp.113-126
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• 2011

The smelting and the continuous casting of steel are important processes that determine the quality of steel products. Especially most of quality defects occur during solidification of the steel continuous casting process. Although quality control techniques such as six sigma, SQC, and TQM can be applied to the continuous casting process for improving quality of steel products, these techniques don't provide real-time analysis to identify the causes of defect occurrence. To solve problems, we have developed a detection model using decision tree which identified abnormal transactions to have a coarse grain structure. And we have compared the proposed model with models using neural network and logistic regression. Experiments on steel data showed that the performance of the proposed model was higher than those of neural network model and logistic regression model. Thus, we expect that the suggested model will be helpful to control the quality of steel products in real-time in the continuous casting process.

• Tribology and Lubricants
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• v.24 no.4
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• pp.179-185
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• 2008

Microporous polymer lubricants(MPLs) are solid polymer materials containing micropores which are filled with liquid lubricants, and which are molded or formed to suit rolling bearings or other machine parts requiring lubrication. MPLs can be effectively applied to provide long-term, maintenance-free lubrication of a variety of machine elements without fully replacing of oils and greases. The application of rolling bearings packed fully with an MPL could reduce or eliminate the problems such as grease deterioration, leakage, under-lubrication caused by insertion of water or foreign matters under severe operation conditions. This paper discuss the application of MPLs for lubrication of rolling ball bearings. Two different MPLs were synthesized and the features of MPLs were tested. Characteristics of the bearings which are packed fully with synthesized MPLs were investigated using SEM, TG/DSC, extents of oil leakage, OIT, and life time test. After these preliminary tests twelve MPLs were synthesized and evaluated by measuring extents of oil leakage and OIT values. Then synthesis conditions for the optimum MPL were selected by SSRED(Six Sigma Robust Engineering Design) pro gram using extents of oil leakage and OIT values respectively. The optimum MPL by means of OIT value showed higher performance such as long life time and application at higher temperature of $140^{\circ}C$ than previous temperature of $100^{\circ}C$.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.212-219
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• 2012

This study focus on what methods of MOT are needed and utilized to solve a technical problem in the MOT leading company. We first classified the MOT methods by project life cycle and R&D job quality based on the several discussion with working group. In order to study, the survey was carried out by 168 experts working on MOT practices. Our main research findings are as follows. The level of utilized MOT methods was above average because MOT sector was beginning to represent an increasing share of total R&D business. But the satisfaction level on the MOT majors was below average. The more utilized MOT methods in practices were 'environment analysis and opportunity research,' 'business feasibility,' 'roadmapping,' 'portfolio,' 'technology tree,' 'scheduling,' 'risk management,' 'six sigma,' 'design of experiment,' 'quality control,' 'cost analysis' etc. And the subjects of product realization process were also needed to MOT practice such as 'design for reliability,' 'design for cost,' 'design for performance,' 'design for safety' deeply involved to product quality. Finally, the capability requested to University students were 'problem define and solving,' 'technology planning and strategy,' 'creative thinking.'