• 품질경영학회지
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• 제33권1호
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• pp.88-98
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• 2005

This paper considers a six sigma project for improving the TIP life time in a spot welding process. The project follows a disciplined process of five phases: define, measure, analyze, improve, and control. A process map is used to identify process input and output variables. Nine key process input variables are selected by using C&E matrix and FMEA, and finally four vital few input variables are selected from analyze phase. The optimum process conditions of the vital few input variables are jointly obtained by maximizing TIP life time using DOE and alternative selection method.

• 산업경영시스템학회지
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• 제29권1호
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• pp.9-17
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• 2006

This paper considers a six sigma project for improving productivity of the brace complement center pillar. The project follows a disciplined process of fife phases: define, measure, analyze, improve, and control. A process map is used to identify process input and output variables. Eleven key process input variables are selected by using X&Y matrix and FMEA, and finally eight vital few input variables are selected from analyze phase. The optimum process conditions of the vital few input variables are jointly obtained by maximizing productivity of the brace complement center pillar using DOE and alternative selection method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.2108-2115
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• 2008

Using transportations like railway, aviations and roads has been increasing continuously. Traffic accidents have been increasing as well. To prevent or lessen these accidents become a big issue to solve. Therefore, more enforced safety levels are being required to meet. In railway field, continuous efforts of railway safety are being executed to prevent traffic accidents. In present, a railway accident has been decreasing since subway accident happened in Daegu Subway in 2003. However, safety levels in railway field have not yet achieved as much as in advanced countries. Basic concept for enforced safety level in railway system is to prevent or minimize accidents by managing systems like related facilities, management method, organization, education. This is the same concept to minimize error rate in six sigma theory. In this paper, we are to apply six sigma techniques used in manufacturing industry to railway safety and go through ways to make more efficient railway safety system.

• 품질경영학회지
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• 제40권2호
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• pp.166-175
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• 2012

Enterprises are continuously trying management innovation activities for survival. Among representative management innovation activities in domestic manufacture enterprise, which are TPS, 6 sigma, Lean 6 sigma etc. Many enterprises through these reform activity have gotten good result. However, these techniques have merits and demerits according to circumstance of enterprise. Specially, there are a lot of difficulties in medium and small size enterprises. In this research, We introduce Lean-SMAIS Method for medium and small size enterprises that is consists of the merit of lean 6 sigma and software(which is called ProEye). We prove Lean-SMAIS method is useful by applying medium and small size enterprise A company.

• 대한안전경영과학회지
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• 제16권1호
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• pp.169-176
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• 2014

This research discusses the characteristics and the implementation strategies for two types of quality metrics to analyze innovation effects in six sigma projects: fixed specification type and moving specification type. $Z_{st}$, $P_{pk}$ are quality metrics of fixed specification type that are influenced by predetermined specification. In contrast, the quality metrics of moving specification type such as Strictly Standardized Mean Difference(SSMD), Z-Score, F-Statistic and t-Statistic are independent from predetermined specification. $Z_{st}$ sigma level obtains defective rates of Parts Per Million(PPM) and Defects Per Million Opportunities(DPMO). However, the defective rates between different industrial sectors are incomparable due to their own technological inherence. In order to explore relative method to compare defective rates between different industrial sectors, the ratio of specification and natural tolerance called, $P_{pk}$, is used. The drawback of this $P_{pk}$ metric is that it is highly dependent on the specification. The metrics of F-Statistic and t-Statistic identify innovation effect by comparing before-and-after of accuracy and precision. These statistics are not affected by specification, but affected by type of statistical distribution models and sample size. Hence, statistical significance determined by above two statistics cannot give a same conclusion as practical significance. In conclusion, SSMD and Z-Score are the best quality metrics that are uninfluenced by fixed specification, theoretical distribution model and arbitrary sample size. Those metrics also identify the innovation effects for before-and-after of accuracy and precision. It is beneficial to use SSMD and Z-Score methods along with popular methods of $Z_{st}$ sigma level and $P_{pk}$ that are commonly employed in six sigma projects. The case studies from national six sigma contest from 2011 to 2012 are proposed and analyzed to provide the guidelines for the usage of quality metrics for quality practitioners.

• International Journal of Quality Innovation
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• 제10권1호
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• pp.1-23
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• 2009

Face the process yield rate improvements of motherboard, although general enterprises finish deployment goal of each functions by overall quality managements, through quality improvement methods, industry engineering methods, plan-do-check-act (PDCA) methods and other improvement solutions, but it is only can be improved partially and unable to enhance the yield rate of product to the target. It only can takes one step ahead to enhance the process yield rate of motherboard with six sigma ($6{\sigma}$) overall DMAIC process and tactics. This research aimed to use six sigma quality improvement tactics by DMAIC systematic procedure and tactics, and find the key factors that effect to the process yield rate of surface mount technology. It also identified the keys input and process and output index to satisfy customer requirements and internal process index. The results showed that the major effective factors by fishbone and process failure modes and effects analysis (PFMEA). If the index of input and output that can be quantified, the optimum parameter can be found through design of experiment to ensure that the process is stable. If the factor of input and output that cannot be quantified, we found out the effective countermeasure by Mind_Mapping, make sure whole processes can be controlled stably, to reach the high product quality and enhance the customer satisfaction.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.399-400
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• 2010

• 응용통계연구
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• 제28권6호
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• pp.1257-1273
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• 2015

모바일 제품에서 임베디드 소프트웨어(Embedded Software)의 역할이 중요해짐에 따라 소프트웨어(SW) 개발 프로세스에 대한 관심이 높아지고 있다. 또한 모바일 제품 시장에서 기업 간의 경쟁이 치열해 지고 적용되는 SW의 규모가 커짐에 따라 SW 개별 모듈의 결함 관리보다는 고객 사용 환경과 시장 품질의 관점에서 SW 개발 프로세스를 개선할 수 있는 새로운 방법이 요구되고 있다. 이 논문에서는 모바일 폰 분야에서 실행된 103개의 SW 개선 프로젝트를 검토하여 프로세스 개선 방법으로 자리 잡고 있는 식스 시그마 방법의 SW 분야 적용 가능성과 통계적 도구와 방법의 유용성을 확인해 보고자 한다.

• 한국기계가공학회지
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• 제16권6호
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• pp.117-124
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• 2017

In this study, we investigated the optimization of process conditions by using the Six Sigma process, design of experiment (DOE) method and response surface method (RSM) to resolve dimensional deviation and appearance problems arising from the shortened process time of the mobile phone rear cover. The analysis of the trivial many was performed by 2-sample T-test and cooling time, and mold temperature and packing pressure were selected as the vital fews affecting the overall width of the product. The optimal conditions of the process were then studied using the DOE and the RSM. We analyzed the improvement effects by applying the selected optimal conditions to the production process and the results showed that the difference between the mean value and target value of the overall width stood at 0.01 mm, an improvement of 88.89% compared to current process that fell within the range of standard dimension. The short-term process capability stood at $4.77{\sigma}$, which implied an excellent technology level despite a decrease by $0.22{\sigma}$ compared to the current process. The difference in process capability decreased by $2.44{\sigma}$ to $0.41{\sigma}$, showing a significant improvement in management capability. Ultimately, the process time of the product was shortened from 18.3 seconds in the current process to 13.65 seconds, resulting in a 34.07% improvement in production yield.

• 융합보안논문지
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• 제7권2호
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• pp.27-37
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• 2007

기업 경영환경의 급격한 변화로 과거 공급자 중심의 경영패러다임은 고객 및 프로세스 중심의 경영패러다임으로 변화하고 있으며 이러한 변화에 민첩하고 유연하게 대응하며 지속적으로 변화하는 기업만이 시장에서 생존할 수 있는 시대가 되었다. 기업은 통합 생산성을 고려하여 프로세스를 재설계하고 내부업무를 통합하는 등 비즈니스 프로세스를 통합하여 경영의 효율성을 극대화하기 위해 많은 투자를 한다. 이러한 노력은 기업운영차원에서 반드시 필요하지만 오늘날 빠르게 변화하는 시장과 고객의 요구에 대처하면서 기업의 전략과 연계하여 운영차원으로 적용하지는 못하고 있다. 효율적인 경영을 통해 얻을 수 있는 이점에는 한계가 있으며 기업내부경영의 효율화가 극대화되어도 치열한 경영환경 하에서 경쟁우위를 차지할 수 있는 요소가 되지는 못한다. 따라서 기업은 시장에서 살아남고 경쟁우위를 유지하기 위해 새로운 가치를 창출할 수 있는 전략을 도출하여 빠르게 프로세스에 적용하고 지속적으로 관리해야 한다.