반복측정의 다가 반응자료에 대한 일반화된 주변 로짓모형

최재성,Choi, Jae-Sung 한국통계학회 2008 응용통계연구 Vol.21 No.4

This paper discusses how to construct a generalized marginal logit model for analyzing repeated polytomous response data when some factors are applied to larger experimental units as treatments and time to a smaller experimental unit as a repeated measures factor. So, two different experimental sizes are considered. Weighted least squares(WLS) methods are used for estimating fixed effects in the suggested model.

물 분사 시스템에 의한 소형 디젤엔진의 NOx 및 그 외 배출물의 특성에 관한 연구

최재성,남정길,Choi Jae-Sung,Nam Jeong-Gil 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.6

In this paper. the effects of a WI(Water Injection) in the intake pipe for a 4-cylinder Dl(Direct Injection) diesel engine are investigated experimentally, The WI system was controlled by the duty cycle from the intake manifold's temperature and MAF(Manifold Air Flow) First. effect of EGR on NOx reduction was investigated. Then WI system was applied to reduce NOx As the results. we can make the NOx map and visualize the NOx results by variation of engine speed and engine load It was known that effect of WI system on NOx reduction without the EGR was better than the with EGR base engine except of low load and speed condition.

저속박용디젤기관의 순간회전속도 변동에 관한 연구

최재성,이진욱,이상득,조권회,Choi, Jae-Sung,Lee, Jin-Uk,Lee, Sang-Dug,Cho, Kwon-Hae 한국마린엔지니어링학회 2007 한국마린엔지니어링학회지 Vol.31 No.2

The variation of the crankshaft speed in a multi-cylinder engine is determined by the resultant gas pressure torque and the torsional deformation of the crankshaft. Under steady state operation, the crankshaft speed has a quasi-periodic variation. For the diagnosis the engine instantaneous speed versus crankshaft angle is utilized. This paper describes a simple measurement method of the engine instantaneous speed versus crankshaft angle using the teeth on the flywheel of the crankshaft. Two non-contacting magnetic pickup combinations detect the crank angle and TDC position for the data acquisition. The results from experiments on a 6 cylinder marine diesel engine demonstrate that the crankshaft speed variation are detected with good resolution. And the crankshaft speed variation is investigated according to the operation conditions. Also, it is confirmed that the engine output measured by EMS can be evaluated larger than the actual value due to TDC position error caused by instantaneous speed variation.

사영에 의한 제1종 분석

최재성,Choi, Jae-Sung 한국통계학회 2011 응용통계연구 Vol.24 No.2

본 논문은 실험자료에 대한 분석모형으로 이원 분산분석모형을 가정한다. 고정효과 모형의 가정하에 요인별 변동량을 구하기 위한 방법으로 제1종 분석을 다루고 있다. 모형의 순차적 적합에 따라 얻어지는 요인별 제곱합의 계산방법으로 대수적 방법이 아닌 사영에 의한 분석방법을 제공한다. 관측자료를 다차원상의 공간벡터로 간주할 때, 최소 제곱법에 의한 요인별 변동량은 계획행렬로 생성되는 모수추정 공간에서 요인별 부분공간으로의 사영에 이르는 거리 제곱으로 구해질 수 있음을 논의하고 있다. 또한 사영행렬로 부터의 고유벡터와 고유근을 이용하여 요인별 변동량을 구하는 방법을 제공하고 있다. 균형자료나 불균형자료에서 모형의 순차적 적합에 따른 제1종 분석이 행해질 때 요인별 변동량의 합은 처리제곱합과 일치하나 제2종 분석의 경우 불균형자료에서 이러한 성질이 만족되지 않음을 논의하고 있다.

단치궁 노인의 구강 기능 만족도에 관한 연구

최재성,강우진,정문규,Choi Jae-Sung,Kang Woo-Jin,Chung Moon-Kyu 대한치과보철학회 1992 대한치과보철학회지 Vol.30 No.2

The purpose of the present study is to inspect the satisfied degree of each oral function in geriatric patients with the shortened dental arch and when their prosthetic treatment is on schedule, provide some references to such treatment. For the approach to such study, 521 subjects were reviewed by grouping them according to the number of their remaining teeth, and masticatory function, phonetic function, facial change, and TMJ disorders were inspected and clarified through some questionnaires. Also through the questionnaires, the correlations between the geriatiric patients with the shortened dental arch and dentition and between the geriatiric patients with the Free-end RDP at the shortened dental arch and their oral function were found out with their satisfied degree of oral function. Results or findings from such study are as follows : 1. With regard to their satisfied degree of oral function, there was a significant difference of satisfaction between or among the group having only the anterior teeth and the group having the part of premolars and the group having even the part of molars, however no significant difference of satisfaction appeard between the group having 1st molars and the group having 2nd molars. 2. With regard to their satisfied degree of phonetic function, no significant difference appeared between or among the group having only the anterior part of teeth and the group having even the part of premolars and the group having even the part of molars, and with regard to their satisfied degree of facial change, no significant difference of satisfaction appeared between the group having the part of premolars and the group having even the part of molars. 3. With regard to their satisfied degree of masticatory function, phonetic function, TMJ disorders, and facial change, no significant difference appeared between the group having both the anterior part of teeth and the part of premolars and the group attached with the Free-end RPD on the same conditions of the afore-said group.

InGaAs 위의 NH₃ Plasma Passivation을 이용한 ALD HfAlO유전체 계면전하(Dit) 향상

최재성,Choi, Jae Sung 한국반도체디스플레이기술학회 2018 반도체디스플레이기술학회지 Vol.17 No.4

The effect of $NH_3$ plasma passivation on the chemical and electrical characteristics of ALD HfAlO dielectric on the InGaAs substrate was investigated. The results show that $NH_3$ plasma passivation exhibit better electrical & chemical performance such as much lower leakage current, lower density of interface trap(Dit) level, and low unstable interfacial oxide. $NH_3$ plasma passivation can effectively enhance interfacial characteristics. Therefore $NH_3$ plasma passivation improved the HfAlO dielectric performance on the InGaAs substrate.

지분구조의 반복측정 자료에 대한 혼합모형

최재성,Choi, Jae-Sung 한국통계학회 2009 응용통계연구 Vol.22 No.1

This paper discusses the covariance structures of data collected from an experiment with a nested design structure, where a smaller experimental unit is nested within a larger one. Due to the nonrandomization of repeated measures factors to the nested experimental units, compound symmetry covariance structure is assumed for the analysis of data. Treatments are given as the combinations of the levels of random factors and fixed factors. So, a mixed-effects model is suggested under compound symmetry structure. An example is presented to illustrate the nesting in the experimental units and to show how to get the parameter estimates in the fitted model.

Machine Learning기법을 이용한 Robot 이상 예지 보전

최재성,Choi, Jae Sung 한국반도체디스플레이기술학회 2020 반도체디스플레이기술학회지 Vol.19 No.1

In this paper, a predictive maintenance of the robot trouble using the machine learning method, so called MT(Mahalanobis Taguchi), was studied. Especially, 'MD(Mahalanobis Distance)' was used to compare the robot arm motion difference between before the maintenance(bearing change) and after the maintenance. 6-axies vibration sensor was used to detect the vibration sensing during the motion of the robot arm. The results of the comparison, MD value of the arm motions of the after the maintenance(bearing change) was much lower and stable compared to MD value of the arm motions of the before the maintenance. MD value well distinguished the fine difference of the arm vibration of the robot. The superior performance of the MT method applied to the prediction of the robot trouble was verified by this experiments.

반복측정의 분할구 자료에 대한 혼합모형

최재성,Choi, Jae-Sung 한국데이터정보과학회 2010 한국데이터정보과학회지 Vol.21 No.1

This paper suggests a mixed-effects model for analyzing split-plot data when there is a repeated measures factor that affects on the response variable. Covariance structures are discussed among the observations because of the assumption of a repeated measures factor as one of explanatory variables. As a plausible covariance structure, compound symmetric covariance structure is assumed for analyzing data. The restricted maximum likelihood (REML)method is used for estimating fixed effects in the model.

디젤기관의 신기술 개발동향

최재성,Choi Jae-Sung 한국마린엔지니어링학회 2004 한국마린엔지니어링학회지 Vol.28 No.7