• The Korean Journal of Applied Statistics
• /
• v.9 no.1
• /
• pp.53-73
• /
• 1996

This paper compares two accelerated life for Weibull distribution. One is the optimum constant stress accelerated life test which minimizes the asymptotic variance of maximum likelihood estimator of a specified quantile at design stress, and the other is corresponding simple step stress test. The models and optimum designs of constant stress and step stress tests are reviewed. Behaviors of asymptotic variances, effects of design parameters to optimum tests, and expected numbers of failures and expected test times of the two tests are investigated. The efficiency of step stress test relative to constant stress test is studied in terms of variance ratio, and robustness to preestimates of design parameters are investigated.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.1301-1307
• /
• 2008

The Seoul-Metro is the first city railroad corporation to operate RIMS(Rolling-stock Information Maintenance System). The development of "RIMS Project" and trial running task were started from Mar 29, 2001. Finally, this project was completed successfully on Dec 31, 2005, as integrated systems including light or heavy maintenance works in Ji-Chuk and Chang-Dong Rolling-stock Offices. After that, from 2006 to Dec 31, 2007, we promoted a this new program to other four rolling-stock offices (Su-Seo, Gun-Ja, Sin-Jeong) and the headquarter. For the duration of trial running, we developed and applied new complementary program having made up for the weak points or defects. The series of new program which were newly developed and applied are comprised of an operation management, trouble management, wheel management, heavy maintenance table automatic creation programs and ordering prediction programs to purchase goods smoothly. The Seoul-Metro have registered these programs(RIMS) to Computer Program Protection Committee. We'd like to introduce a composition of program for enhancement of a city railroad Information Systems.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.184-190
• /
• 2009

Recently, the concern for the reliability of railway is increasing, also the study about reliability is being processed at a good pace. However, in case of an existing railway operating it is true that the railway system is being operated without a clear RAM standard. There is not a clear RAM standard about product menual of a city railroad, and there are only basic provisions concerning traction motor which can be called a main equipment. In this paper, we calculated the availability and reliability of subway having MKBSF, MKBF, MTBF, MTTR analyzing accumulated maintenance data about a main equipment of a VVVF direct subway being operated in line #4. By watching the reliability grade of a VVVF subway being operated and manufactured within the country and being applied with the development of a city railway reflected by RAM menual when the new subway is manufactured, and with the basic data of RCM, we'd like to grope the methods which can be improved by operation stability of a city railway.

• Proceedings of the KIEE Conference
• /
• 1997.07a
• /
• pp.291-293
• /
• 1997

The external magnetic field which is applied to the superconducting wire generates coupling loss. Analytical method has been used for the calculation of the coupling loss. This paper calculates the coupling loss that is generated in the matrix by the external magnetic field. Two-dimensional Finite Element Method has been used for the calculation.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2002.05a
• /
• pp.767-771
• /
• 2002

This paper proposes a multivariate $T^2$ variable interval control chart with sampling at fixed times, where samples are taken at specified equally spared fixed time points, and additional samples are allowed between these fixed times when indicated by the preceding $T^2$ statistics. At fixed sampling tunes, the $T^2$ statistics are composed of all quality characteristics, and a part of qualify characteristics are selected to obtain $T^2$ statistics at additional sampling times. A Markov chain approach is used to evaluate the performance of the proposed chart.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2002.05a
• /
• pp.762-766
• /
• 2002

This paper proposes a method or estimating lifetime distribution for products under two-dimensional warranty in which age and usage are used simultaneously to determine the eligibility of a warranty claim. For such a case, existing methods reduce the two-dimensional time stale to a single stale assuming that the two variables have a functional relationship. This assumption is, however, not appropriate since the functional relationship is unknown in practice. In this paper, the field age and usage data are modeled with a bivariate lifetime distribution. Method of obtaining maximum likelihood estimators is outlined, their asymptotic properties are studied and specific formulas for a bivariate Weibull distribution are obtained. The proposed model is compared with the existing one which assumes a lineal relationship between the two variables Simulation studios are performed to investigate the effect of the degree of dependency between the two variables.

• Product Safety
• /
• s.198
• /
• pp.38-41
• /
• 2010

'전기 없이도 작동하는 피난유도선', '와이어리스(무선) 피난유도선' 바론 (주)알지비테크롤러지(회장 조성복)사의 제품이다. 발광시트 전문생산업체인 알지비테크놀러지는 그 동안 알지비테크놀러지는 발광시트를 이용하여 기존 비상등 및 축광 표지판등이 가지고 있는 문제점들인 외부충격에 의한 파손, 짙은 연기에서의 시인성(연기속 시각효과)과 유도능력 등을 보완할 수 있는 제품 개발에 힘써왔다. 지난2010. 5.12 ~ 5.14간 이뤄진 '2010 재난대응 안전한국훈련' 중 지하철화재 대응훈련부분에 참가하기 위하여 '와이어리스피난유도선'을 몽촌토성역 설치로 그 첫 선을 보였는 바, 국내외 재난안전관련 업계로부터 최고의 찬사로 주목을 받았고, 이에 제품관련 문의와 상담이 폭주하고 있어 세계적으로 주목받는 기업으로의 성장을 기대하고 있다.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.6
• /
• pp.1172-1179
• /
• 2010

Since HEMP has the very short rising time and propagates widespreadly with several tens of kV/m, it threatens most of systems in its cover range. Therefore, it is important to research coupling mechanism into systems and establish countermeasures for the HEMP to protect systems effectively. This paper analyzed characteristics and trends of currents to be induced at the load of a line which is located over ground with different conditions such as polarization, incidence angle, line length and height etc. We applied double exponential waveform as the HEMP shape and used BLT method to analyze the coupling route into the line. Also, we compared the simulation data of chain matrix modeling to verify reliability of BLT modeling. In the result, two data is almost agreed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2011.06a
• /
• pp.61-62
• /
• 2011

이 연구는 경인아라뱃길 중의 경인항 인천 컨테이너터미널의 부두축조에 있어서 터미널 활용의 경제성을 감안한 대상 선박의 조종성능 및 운동성능을 검토하고, 대상선박의 통항 및 접 이안 안전성 확보에 필요한 적정 수역 및 부두길이를 확정하여 준설토 투기장의 부족문제 해결을 위한 부두전면의 최선의 준설범위를 결정하는 데 그 목적이 있다. 이를 위하여 550 TEU급 컨테이너선을 인천갑문 쪽으로 접안 배치하고, 1,000 TEU급의 컨테이너선을 갑문에서 멀리 떨어진 수역에서 접이안 조종함으로써 최대한의 안전성을 확보할 수 있도록 한다. 이러한 상황을 감안하여 인천항 도선사협회 전문가들과의 협의를 거쳐서, 안전한 선박조종 수역을 포함한 최적의 부두길이 결정을 위한 부두배치안 2개(제1안, 제2안)를 설정하여 선박조종 시뮬레이션을 통하여 2개의 안에 대한 대상 선박의 접이안 안전성을 평가하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2011.06a
• /
• pp.71-73
• /
• 2011

다기능 선박조종시뮬레이터(Full-mission Shiphandling Simulator)는 항해사, 선장 및 도선사의 자질 향상을 위한 교육뿐만 아니라 항만개발을 위한 사전 검토와 해난사고 발생 시, 원인규명을 위한 분석에도 이용되고 있다. 한국해양수산연수원에서는 이러한 목적을 위하여 2011년 2월 28일 Russia Transas 제품의 선박조종시뮬레이터를 설치 완료 하였다. 이 FMSS는 적어도 360도의 수평시각을 가진 대형 구형화면에 여섯(6) 자유도 운동을 하는 본선 및 타선을 실시간으로 표현하는 photo-realistic high resolution computer graphic visual system과 같은 최신기술을 사용하는 가장 현대화된 최고급 해상용 시뮬레이터로 해난 사고 윈인규명을 위한 분석 연구 목적을 위하여 광범위한 출처로부터 모델시험과 자료의 신뢰할만한 공식적 기록들에 근거한 매우 정확한 수력학적 선박 모델링 소프트웨어로 이루어졌다. 여기서는 이 FMSS의 형태와 복잡성을 상세하게 소개한다.