• 한국철도학회논문집
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• 제3권1호
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• pp.1-11
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• 2000

In this paper, the IGBT VVVF inverter for 1C4M propulsion system of railway traction is studied. The inverter is consisted of IGBT stacks, a DB unit, and a control unit. The test results of the combined system is given, which shows an excellent performance of the overall system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.580-584
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• 2002

This paper proposes an experimental study on the traction system of rubber tired AGT (Automated Guideway Transit). IGBT VVVF inverter is developed for 1C2M propulsion system of AGT, and it consists of inverter stack, gate control unit, control unit, and interface unit. The combination test was carried out to prove the performance of inverter, and test results show that the developed inverter is excellent.

• Communications for Statistical Applications and Methods
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• 제17권2호
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• pp.223-229
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• 2010

We consider the asymptotic results of the variance ratio statistic when the underlying processes have moving average(MA) unit roots. This degenerate situation of zero spectral density near the origin cause the limit of the variance ratio to become zero. Its asymptotic behaviors are different from non-degenerating case, where the convergence rate of the variance ratio statistic is formally derived.

• 대한한의정보학회지
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• 제22권1호
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• pp.27-36
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• 2016

Purpose: The purpose of this study was to compare the level of job stress, burn-out and job satisfaction between intensive care unit nurses and general unit nurses. Methods: The subjects of this study were 100 intensive care unit nurses and 100 general unit nurses in university's hospitals. The data were collected using self-report questionnaires. The data were analyzed by descriptive statistics, -test, ANCOVA, t-test, ANOVA, and Pearson correlation coefficient by using the SPSS WIN 20.0 program. Results: There were significantly negative correlation in the score of job stress and job satisfaction in both groups of nurses. Job stress of intensive care unit nurses was significantly differences according to department satisfaction. Burn-out of intensive care unit nurses was significantly differences according to position, department satisfaction. Job satisfaction of intensive care nurses unit was significantly differences according to department satisfaction. Job stress of general unit nurses unit was significantly differences according to department satisfaction. Burn-out of general unit nurses was significantly differences according to clinical experience, position, department satisfaction. Job satisfaction of general unit nurses was significantly differences according to clinical experience, department satisfaction. Conclusions: The appropriate rewards for intensive care nurses and general unit nurses to decrease their job stress will be needed in hospital settings. In addition, a plan for systemic nurse training program is needed to provide high quality nursing education for each unit nurses effectively.

• 한국콘텐츠학회논문지
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• 제16권3호
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• pp.1-10
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• 2016

본 연구는 심장내과 중환자실 환자들에게 아로마 흡입요법을 적용하여 환자들의 스트레스, 불안 및 우울에 미치는 효과를 규명하기 위함이다. 비동등성 대조군 전후시차 설계를 이용한 유사 실험 연구로 연구 대상자는 심장내과 중환자실에 입원한 환자로 실험군 30명, 대조군 33명이었다. 연구도구로는 시각적 상사척도(VAS), Spielberger(1972)가 개발한 도구, Beck Depression Inventory-II(BDI-II)를 사용하였다. 자료 수집 기간은 2015년 2월 25일부터 5월 8일까지였다. 수집된 자료는 실수, 백분율, $x^2$-test와 t-test, paired t-test로 분석하였다. 연구결과 아로마 흡입요법이 심장내과 중환자실 환자에게 스트레스, 불안 및 우울을 감소시키는 효과가 실험군, 대조군의 두 집단 간 통계적으로 유의한 차이가 나타나지 않았다. 따라서 심장내과 중환자실 환자들의 스트레스 및 불안, 우울 감소와 관련하여 아로마 흡입요법을 다양하게 시도하는 후속연구가 필요하다.

• 유공압시스템학회논문집
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• 제2권2호
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• pp.1-7
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• 2005

For the reliability evaluation of the track drive unit(TDU), firstly, we analyzed the major failure modes through FMEA(failure mode & effects analysis), FTA(failure tree analysis), and 2-stage QFD(quality function deployment), and then quantitatively determined the priority order of test items. The Minitab analysis was also performed for prediction of life distribution and parameters of TDU by use of field failure data collected from 430 excavators for two years. In addition, we converted the fluctuation load in field conditions into the equivalent load, and for evaluation of the accelerated lift by the cumulative fatigues, the equivalent load is again divided into the fluctuation load by reference of test time. And then, by use of the test method in this paper, the acceleration factor(AF) of needle bearing inside planetary gear which is the most weakly designed part of TDU is achieved as 5.3. This paper presents the quantitative selection method of test items for reliability evaluation, the determination method of the accelerated life test time, and the method of non-failure test time based on a few of samples. And, we proved the propriety of the proposed methods by experiments using a TDU for a 30 ton excavator.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.137.2-137
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• 2001

• 전기학회논문지
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• 제57권2호
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• pp.208-213
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• 2008

In order to assess the reliability of the electronics control unit for vehicles, accelerated life test model and procedure are developed. By using this method, failure mechanism and life distribution are analyzed. The main results are as follows : i) the main failure mechanism is degradation failure that is, junction destruction of a semiconductor resin by high temperature. ii) the life distribution of the electronics control unit for vehicles is fitted well to Weibull life distribution and the accelerated life model of that is fitted well to Arrhenius model. iii) at the result of the life distribution, accelerated life test method is developed, and test time for life assessment will be shortened by 5,000 hours by this test method.

• Communications for Statistical Applications and Methods
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• 제2권2호
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• pp.101-114
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• 1995

In this paper we consider the multiple unit root tests both for the regular and seasonal unit roots based on the Lagrange Multiplier(LM) principle. Unlike Li(1991)'s method, by plugging the restricted maximum likelihood estimates of the nuisance parameters in the model, we propose a Lagrange multiplier test which does not depend on the existence of the nuisance parameters. The asymptotic distribution of the proposed statistic is derived and empirical percentiles of the test statistic for selected seasonal periods are provided. The power and size of the test statistic for examined for finite samples through a Monte Carlo simularion.

• 한국정밀공학회지
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• 제25권4호
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• pp.86-92
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• 2008

This paper is to investigate the behavior of linear static structure stress, the fatigue and experimental shock fracture far engine base in the Auxiliary Power Unit to resolve its restricted electrical power problem. The shock fracture test was experimentally made under MIL standard criteria. The numerical results by finite element method had a good agreement with those from the shock test. The design data of predicting the fracture at the initial crack and the damage behavior of structure with shock and vibration load in the battle field can be obtained from shock test. In the functional shock test, the crack at the side parts of the engine base was found at peak acceleration of 40g.