• 대한기계학회논문집
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• 제16권10호
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• pp.1900-1907
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• 1992

본 연구에서는 원형평판의 경계조건을 일부분은 고정단으로 일부분은 자유단 으로 구성하여 자유단각 .alpha.(Fig.4 참조)를 0˚, 30˚, 60˚, 90˚, 120˚, 150˚, 180˚로 변화시킴에 따른 진동모드를 시간평균 홀로그래픽 간섭계(time-average holographic interferometry)를 이용해 분석하고 자유단의 변화에 따른 고유진동수의 비를 비교하였고, 레이저 도플러 유속계(LDV)를 변형한 레이저 도플러 진동계(laser doppler vibrometer)로 원형평판의 진동변위와 시간평균 홀로그래픽 간섭계로 구한 진 동변위를 비교하였다.

• 한국정보과학회논문지:데이타베이스
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• 제28권3호
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• pp.384-394
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• 2001

본 논문에서는 시간지원 데이터를 과거 세그먼트, 현재 세그먼트, 그리고 미래 세그먼트로 분리한 저장 구조를 기반으로 하는 AST-AET(Average valid Start Time-Average valid End Time) 데이터 이동 방법을 제안한다. 제안한 AST-AET를 계산하는 방법과 이동 대상 이 되는 개체 버전을 정의한다. AST와 AET를 계산하는 방법과 이동 대상이 되는 개체 버 전을 검색하고 이동하는 과정을 보인다. 도한, 제안하는 AST-AET 데이터 이동방법과 기존 의 LST-GET(Least valid Start Time-Greatest valid End Time) 데이터 이동 방법의 사용 자 질의에 대한 평균 응답시간을 비교한다. 실험 결과에 의하면, LLT(Long Lived Tuples)가 없윽 때는 현재 세그먼트의 크기가 비슷 하기 때문에 두 이동 방법의 평균 응답 시간이 비슷하였다. 그러나 LLT가 있을 때에는 LST-GET 데이터 이동방법의 현재 세그먼트 크기가 커지기 때문에, AST-AET 데이터 이 동 방법의 평균 응답 시간이 LST-GET 데이터 이동 방법보다 작았다. 또한, 시간지원 질의 의 평균 응답 시간이 LST-GET 데이터 이동 방법보다 전반적으로 작았다.

• 한국학교보건학회지
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• 제30권3호
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• pp.317-324
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• 2017

Purpose: Breakfast is the most important meal to provide energy for the day. Breakfast is especially important to give enough nutritional support to children and adolescents for their physical growth and sexual development. Sleep-related factors like average sleep duration and wake up time would mostly be associated with regular breakfast. This study aimed to investigate the effect of sleep on regular breakfast consumption in Korean adolescents. Methods: The study used the data from the 12th Korea Youth Risk Behavior Web-based Survey (KYRBS-XII) conducted in 2016 by the Korea Centers for Disease Control and Prevention. The data of 62,820 subjects (middle/high school students) were included in the final analysis. The study examined the factors related to regular breakfast, focusing on weekday average sleep duration and wake up time of middle school students and high school students, respectively. Results: Regular breakfast consumption was shown to have a statistically significant association with high economic status, nutritional education, weekday average sleep duration, wake up time, and subjective sleep satisfaction in the multivariate logistic regression. Regardless of the school level, regular breakfast consumption was significantly associated with early wake up time. As to the effect of weekday average sleep duration on regular breakfast consumption, it showed some different results depending on the school level. Conclusion: Regular breakfast consumption of Korean adolescents was related to weekday average sleep duration and wake up time. Having breakfast regularly was affected by both adequate weekday average sleep duration and early wake up time.

• Journal of Advanced Marine Engineering and Technology
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• 제22권3호
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• pp.353-361
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• 1998

The study on the vibration characteristics of annular sector plates is important for structural engineers. In this study the vibration modes and their natural frequencies of annular sector plates clamped along the inner circumferential edge are obtained by the time average holographic interferometer according to the varying sector angle. The experimental results agree well with those obtained by the numerical analysis. The vibration characteristics of annular sector plates shows great dependence on the sector angle. The radial nodal lines converge to the center of annular sector plate.

• 대한인간공학회지
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• 제4권1호
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• pp.7-10
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• 1985

Eye blinking in case of three visual tasks is studied; wall hard-copy and color monitor. The eye blinking is checked by eye-status detector. The data observed are (1) the average number of eye blinking (2) the average time of eye blinking for three minutes in case of all three visual tasks. The results are as follows: (1) The average times (or numbers) of eye blinking are different among three tasks. (2) The average time (or number) of eye blinking of wall is different from hard-copy and color monitor tasks. (3) But the average time (or number) of eye blinking of hard-copy is not different from that of color monitor.

• Journal of the Korean Statistical Society
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• 제23권2호
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• pp.403-420
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• 1994

An economic design of the $\bar{X}-R$ chart using variable sample size (VSS) scheme is proposed in this paper. In this design the sample size at each sampling time changes according to the values of the previous two sample statistics, sample mean and range. The VSS scheme uses large sample if the sample statistics appear near inside the control limits and smaller sample otherwise. The set of process parameters, such as the sampling interval, control limits and the sample sizes, are chosen to minimize the expected cost per hour. The efficiency of the VSS scheme is compared to the fixed sample size one for cases where there is multiple of assignable causes. Percent reductions of the expected cost in the VSS design are calculated for some given sets of cost parameters. It is shown that the VSS scheme improves the confidence of the procedure and performs statistically better in terms of the number of false alarms and the average time to signal, respectively.

• 한국정밀공학회지
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• 제24권7호
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• pp.69-74
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• 2007

The paper proposes a new sonic resonance test for a elastic modulus measurement which is based on time-average electronic speckle pattern interferometry(TA-ESPI) and Euler-Bernoulli equation. Previous measurement technique of elastic constant has the limitation of application for thin film or polymer material because contact to specimen affects the result. TA-ESPI has been developed as a non-contact optical measurement technique which can visualize resonance vibration mode shapes with whole-field. The maximum vibration amplitude at each vibration mode shape is a clue to find the resonance frequencies. The dynamic elastic constant of test material can be easily estimated from Euler-Bernoulli equation using the measured resonance frequencies. The proposed technique is able to give high accurate elastic modulus of materials through a simple experiment set up and analysis.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.245-249
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• 2004

This paper describes the vibration characteristics of Nd:YAG laser welding plates analyzed time-average Electronic Speckle Pattern Interferometry(ESPI). In laser welding, the travel speed has influence on a mechanical properties, such as elastic modules, response frequencies and so on, which is resulted on a residual stress of the welding zone. the response frequencies related to elastic modules are determined by time-average ESPI and the results, as compared to each condition, are used to estimate optimal condition of travel speed.

• Journal of Information Processing Systems
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• 제10권3호
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• pp.429-442
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• 2014

In this paper, we investigated the use of seasonal autoregressive integrated moving average (SARIMA) time series models for fault detection in semiconductor etch equipment data. The derivative dynamic time warping algorithm was employed for the synchronization of data. The models were generated using a set of data from healthy runs, and the established models were compared with the experimental runs to find the faulty runs. It has been shown that the SARIMA modeling for this data can detect faults in the etch tool data from the semiconductor industry with an accuracy of 80% and 90% using the parameter-wise error computation and the step-wise error computation, respectively. We found that SARIMA is useful to detect incipient faults in semiconductor fabrication.

• 한국정밀공학회지
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• 제16권10호
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• pp.53-58
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• 1999

Even I the Electronic Speckle Pattern Interferometry(ESPI) method that measure the strain of object within wavelength of light is less visibility than Holographic Interferometry(HI) method, the merits of application, convenience and time-save have made the method practical in industry. However, the existing ESPI methods that are based on dual-exposure, real-time and time-average method have difficulties for accurate measurement, due to irregular intensity and shake of phase. Recently, in order to solve this problem, phase shifting method have been proposed. In this method, the path of reference light in interference is shifted to make improvement in distinction and precision. But this method includes too many noise, caused by the problem of relationship between object and phase. Therefore, a method to reduce noise muse be introduced. In this paper, least square fitting method is proposed. As results, the phase-map is influenced by precise phase shifting and current of notes and speckle pattern obtained by phase shifting method is improved on the existing method driven from time-average method.