• Journal of Navigation and Port Research
• /
• v.36 no.3
• /
• pp.181-187
• /
• 2012

Highly plastic clays in their normally consolidated states are not always linear but are concave downwards. Thus their compression index deceases with the increase of consolidation pressure. The $e-{\log}{\sigma}_{\upsilon}{\prime}$ curves of plastic or non-plastic silty clays are not linear but are convex upwards. In this paper, consolidation tests were conducted with several undisturbed field soils of Korea south coast and their $e-{\log}{\sigma}_{\upsilon}{\prime}$ plots are not always linear. In case of using Butterfield's method(liquid limit 50~100%), ${\ln}{\upsilon}-{\ln}{\sigma}_{\upsilon}{\prime}$ plots are linear. But some undisturbed samples which have void ratio over 2.24, liquid limit over 100% and plasticity index over 60% are not linear. In results of consolidation tests with remolded samples which contain silt(fly ash) contents of 90% has compression index increasing with the increase in consolidation pressure.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.3
• /
• pp.69-80
• /
• 2015

This paper is writing about developing magnet power supply. It is very important for power supply to obtain output current in high precision and high stability. As a switching noise and a power noise are the cause of disrupting the stability of output current, to remove these at the front end, low pass filter with 300Hz cutoff frequency is designed and placed. And also to minimize switching noise of the current into magnet and to stop abrupt fluctuations, output filter should be designed, when doing this, we design it by considering load has high value inductance. As power supply demands the stability of less than 5ppm, high precision 24bit(300nV/bit) analog digital converter is needed. As resolving power of 24bit(300nV/bit) analog digital converter is high, it is also very important to design the input stage of analog digital converter. To remove input noise, 4th order low pass filter is composed. Due to the limitation of clock, to minimize quantization error between 15bit DPWM and output of ADC having 24bit resolving power, ${\Sigma}-{\Delta}$ modulation is used and bit contracted DPWM is constituted. And before implementing, to maximize efficiency, simulink is used.

• Proceedings of the Korean Society for Quality Management Conference
• /
• 2007.04a
• /
• pp.3-8
• /
• 2007

본 논문에서는 사무 간접부서의 효율성 문제를 해결하고자 한다. 먼저 도요다 경쟁력의 원천인 유연생산 시스템의 아이디어를 응용하고자 하였다. 도요타의 유연생산시스템을 살펴보고, 프로세스 분석을 위해서 SIPOC 분석 기법을 살펴보았다. 도요타의 유연생산 방식을 사무 부서에 적용을 시도하였다. 실제 현장에 적용하여 효과를 보았다. 본 개선 기법은 인적 물적 제약이 많은 중소기업 및 공공부문의 경영혁신 방안으로 효과가 있을 것으로 제안한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.3
• /
• pp.235-241
• /
• 2010

Engine Mount plays an important role which supports engine, isolates vibration from engine and blocks the vibration from road. Development of engine mount for NVH costs great a deal. So, the cost of development being reduced, the way developed effectively engine mount using DFSS technique is proposed in this paper. CTQ(critical to quality) is vibration and parameter is dynamic stiffness of mounts. The core parameters are selected with TPA(transfer path analysis) technique. It uses design of experiments(DOE) or Taguchi Methods to optimize parameter values and reduce variation. And then, this paper shows the result of improvement for vibration in the developing vehicle.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.3
• /
• pp.673-681
• /
• 2007

The integration of Quality Circles and Six-Sigma has gained attentions for the attainment of enhanced customer satisfaction, costs reduction, and improved business performance. The purpose of this paper is to verify the benefit from the integration of Quality Circles and Six-Sigma by applying the integrated process for an alcohol manufacturing line. In the integrated process, we used the first three steps of Six-Sigma of Define, Measure, and Analyze(D-M-A) and then applied the concept of Quality Circle, which has good performance in the Improvement and Control(I-C) process. For the selection of the theme of quality circles, Analytic Hierarch Process(AHP) is used, and we also employed the experimental design, which is designed to find an optimal operating condition. Furthermore, the results of the economic analysis confirm that the integration process would be successful in reducing the incidence of defects and the quality cost.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.8
• /
• pp.27-35
• /
• 2005

Several damages due to large displacement caused by liquefaction have been reported increasingly. Numerical procedures based on effective stress analysis are therefore necessary to predict liquefaction-induced deformation. In this paper, the fully coupled effective stress model called UBCSAND is proposed to simulate pore pressure rise due to earthquake or repeated loadings. The proposed model is a modification of the simple perfect elasto-plactic Mohr-Coulomb model, and can simulate a continuous yielding by mobilizing friction and dilation angles below failure state. Yield function is defined as the ratio of shear stress to mean normal stress. It is radial lines on stress space and has the same shape of Mohr-Columob failure envelope. Plastic hardening is based on an isotropic and kinematic hardening rule. The proposed model always causes plastic deformation during loading and reloading but it predicts elastic unloading. It is verified by capturing direct simple shear tests on loose Fraser River sand.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.5
• /
• pp.1017-1022
• /
• 2011

This paper describes the improvement of the calculation by using $6{\sigma}$ method on steam turbine simulator in a nuclear power plant. The simulator is essential to not only verification and validation of control logic but also making sure of control constants in upgrading the long time used control system into the new one. And the dynamic model is a key point in that simulator. The model used during the retrofit period of the turbine controller in Kori Nuclear Power Plant makes difference in calculating generator output and control valve positions. That is because such operating data as the main steam pressure, the main steam temperature and control valve positions of Yongkwang #3 are different from those of Kori #4. Therefore, the model parameters must be tuned by using actual operating data for the high fidelity of simulator in calculating the dynamic characteristic of the model. This paper describes that the $6{\sigma}$ method is used in improvement of precision of generator output calculation in the steam turbine model of the simulator.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.3
• /
• pp.15-19
• /
• 2003

In This paper, we developed 1.96 GHz air gap type FBAR BPF using ZnO as piezoelectric sputtered by RF magnetron at room temperature. FBAR BPF was fabricated by sputtering bottom electrode (Al), ZnO as piezoelectric and top electrode (Mo) on Si wafer one by one with RF magnetron sputter, then Si was dry etched to make an air hole. XRD test result of fabricated FBAR BPF showed that ZnO crystal was well pre-oriented as (002) and sigma value of XRC was 1.018. IL(Insertion loss) showed excellent result as 1 dB.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.05a
• /
• pp.500-504
• /
• 2004

본 논문에서는 한 중소기업을 상대로 진행된 게이트 도장 품질 개선을 위한 6시그마 프로젝트 과정을 소개한다. 프로젝트는 6시그마 개선활동의 로드맵인 DMAIC 절차를 따라 진행하였다. 먼저 Define 단계에서는 고객요구사항 파악을 위해 VOC 기법을 활용하여 CTQ를 선정하였다. Measure 단계에서는 프로세스 맵, 특성요인도, XY 매트릭스, FMEA등을 이용하여 주요 인자들을 규명하였다. Analyze 단계에서는 상관분석, ANOVA, 그래프 분석 등 각종 통계적 기법을 활용해 핵심입력변수인 'Vital Few's'를 규명한 후, Improve 단계에서 DOE를 통한 최적조건을 도출하였다. 또한 Control 단계에서는 최적조건을 유지하기 위한 관리계획 및 실수방지, 표준화 기법을 도입하였다. 이러한 개선 활동을 통해 개선 전 2.957 시그마 수준의 품질을 3.66 시그마 수준까지 높일 수 있었으며, 6천 3백만원의 비용절감을 할 수 있었다. 또한 본 논문에서는 중소기업에서의 프로젝트 진행의 문제점을 제시하였고, 그 해결방안에 대해서도 논하고자 한다.

• 한국경영정보학회:학술대회논문집
• /
• 2008.06a
• /
• pp.238-244
• /
• 2008

본 연구는 급변하는 경영환경에서 서비스 기업들이 빠르고 창의적인 혁신활동으로 기업의 문제를 해결을 지원하기 위한 문제해결 정보시스템을 설계 하고자 하는 연구이다. 이를 위해 창의적 혁신 기법인 TRIZ 혁신 기법과 고객관점의 최적화 기법인 6시그마 기법을 융합하여 CTQ를 중심으로 하는 3단계 문제해결 Logic과 이를 지원하는 정보 시스템 설계에 대한 Framework 및 속성들을 제시하였다. 또한 서비스 기업의 일반적 사례 적용을 통해 문제해결정보시스템의 활용 가능성을 확인 하였고, 이에 대한 문제해결 시스템 적용을 통해 서비스 기업들의 경영혁신을 고도화하여, 기업의 경쟁력을 향상할 수 있다는 점을 제시해 주고 있다.