• Journal of the Korean Data and Information Science Society
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• v.23 no.6
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• pp.1117-1125
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• 2012

The occurrence of food poisoning is usually modeled by meteorological variables like the temperature and the humidity. In this paper, we investigate the relationship between food poisoning occurrence and climate variables in Korea and compare Poisson regression and autoregressive moving average model to select the forecast model. We confirm that lagged climate variables affect the food poisoning occurrences. However, it turns out that, from the viewpoint of the prediction, the number of previous occurrences is more influential to the current occurrence than meteorological variables and Poisson regression model is less reliable.

• Review of KIISC
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• v.2 no.3
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• pp.41-49
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• 1992

레이다 시스템, ranging 시스템, 확산 대역 통신 (spread spectrum communication) 시스템, 그리고 요즈음 각광받고 있는 코드분할방식 다중통신 (CDMA com-munication) 시스템에서는 주지하다시피 상관성(correlation) 이 좋은 수열(sequence)들위 사용이 필수 불가결하다. 수열의 상관성은 그 수열 자신의 상관성이냐 다른 수열간의 상관성이냐에 따라 자기상관관계(crosscorrelation)로 나누어 생각할 수 있고 수열의 주기성의 유무에 따라 주기적 상관관계(Periodic correlation)와 비주기적 상관관계(aperiodic correla-tion)로 나누어 볼 수 있다. 여기서 수열의 상관성이 좋다는 말은 정규화된 수열의 자기상관계수(autocorrelation coefficient)와 수열 간의 교차상관 계수(crosscorrelation coefficient)의 최대 크기가 수열의 길이에 비해 상대적으로 작은 값을 갖는다는 것을 의미한다. 본 논문에서는 주기성을 갖는 이진수열군의 하나인 bent수열과 이 bent수열을 구성하는데 기본이 되는 bent함수를 중심으로 주기적 상관성이 우수한 여러 수열군에 대해 알아보고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.167-167
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• 2004

반도체 공정 등에서 10-6_10-8 TOW의 고진공 환경을 제공하기 위하여 사용되는 고진공 터보분자펌프(Turbomolecular Pump, TMP)는 다층의 회전깃을 갖는 로터를 회전시켜 분자를 배출시키는 방식을 사용하는 진공펌프이다. 이러한 고진공을 실현하기 위해서는 가장 효과적인 방법으로는 회전블레이드의 선속도를 높이는 것으로, 이는 회전로터의 직경을 크게 하거나, 회전속도를 높임으로써 얻어질 수 있다. 따라서 최근의 고진공 터보분자펌프는 대부분 25,000∼40,000RPM의 고속회전을 요구하는 것이 일반적이며 회전속도는 주로 로터 재료의 허용한도까지 적용되고 있다.(중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.1
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• pp.40-47
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• 1986

In this paper, the principles of cascade realization of 3-3CLC(3input-3out put Conservative Logic Circuit)using magnetic bubble are exlpored and the problem of realizing arbitary 3-3lofic circuit with minimal number of logic elements is handled. The five primitives classes 5, 15, 21, 24 and 29 are selected to realize all of the 3 equivatlent class by cascading only two of them. The crossoreres of lines are permitted in this realization and the upper bound of crossorers is three. The composition results are computed in MV 4000 minicomputer.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.259-264
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• 1997

널리 쓰이는 진화 알고리즘은 크게 두가지가 있다. 유전 알고리즘과 진화 기법이 그것이다. 이들 알고리즘은 실행 전에 사용자가 정해주어야 하는 변수들을 가지고 있다. 본 논문에서는 이 두 알고리즘을 일반화시키고 집단의 크기, 교차변이 연산자 적용 확률 그리고 돌연변이 연산자 적용 확률과 같은 변수들을 알고리즘이 수행되는 동안 스스로 정하는 일반화된 자기 형성 진화 알고리즘을 제안한다. 제안된 알고리즘의 타당성과 효용성은 시스템 동정화와 다개체 시스템 제어의 두가지 복잡한 제어 문제에 대한 적용을 통해 보여진다.

• The Korean Journal of Applied Statistics
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• v.28 no.5
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• pp.871-883
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• 2015

Vector autoregressive (VAR) models in high dimension suffer from noisy estimates, unstable predictions and hard interpretation. Consequently, the sparse vector autoregressive (sVAR) model, which forces many small coefficients in VAR to exactly zero, has been suggested and proven effective for the modeling of high dimensional time series data. This paper studies coupling measures to select non-zero coefficients in sVAR. The basic idea based on the simulation study reveals that removing the effect of other variables greatly improves the performance of coupling measures. sVAR model coefficients are asymmetric; therefore, asymmetric coupling measures such as Granger causality improve computational costs. We propose two asymmetric coupling measures, filtered-cross-correlation and filtered-Granger-causality, based on the filtered residuals series. Our proposed coupling measures are proven adequate for heavy-tailed and high order sVAR models in the simulation study.

• Journal of Digital Convergence
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• v.13 no.8
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• pp.267-279
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• 2015

The study aimed to examine the longitudinal relationship between addictive use of mobile phones and learning activities for elementary school students and to analyze (1)temporal changes of the addictive use of mobile phones and learning activities, (2)temporal relationship between them, and (3)multiple and complex group analysis across gender on the relationship. For the study, 3-year longitudinal data(2010-2012) of the Korean Children and Youth Panel Survey and autoregressive cross-lagged modeling were used. The findings showed that the addictive use of mobile phones and learning activities had a significant positive effect on the future selves of children over time. The addictive use of mobile phones influenced positively subsequent learning activities, but, the learning activities did not affect the addictive use of mobile phones. Further, there were no significant gender differences in the longitudinal relationship. The study provided the useful data to make guidelines on how to protect mobile phone addiction for elementary school students.

• Journal of KIISE
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• v.44 no.9
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• pp.954-965
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• 2017

A stable power supply is very important for the maintenance and operation of the power infrastructure. Accurate power consumption prediction is therefore needed. In particular, a university campus is an institution with one of the highest power consumptions and tends to have a wide variation of electrical load depending on time and environment. For this reason, a model that can accurately predict power consumption is required for the effective operation of the power system. The disadvantage of the existing time series prediction technique is that the prediction performance is greatly degraded because the width of the prediction interval increases as the difference between the learning time and the prediction time increases. In this paper, we first classify power data with similar time series patterns considering the date, day of the week, holiday, and semester. Next, each ARIMA model is constructed based on the classified data set and a daily power consumption forecasting method of the university campus is proposed through the time series cross-validation of the predicted time. In order to evaluate the accuracy of the prediction, we confirmed the validity of the proposed method by applying performance indicators.

• Journal of the Korea Society of Computer and Information
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• v.26 no.4
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• pp.181-188
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• 2021

The purpose of the current study was to investigate the causal relationship between school life adjustment and life satisfaction among adolescents through longitudinal panel data. The current study analyzed the 1st through 7th wave data in the 4th grade panel of elementary school from the Korea Children and Youth Panel Survey (KCYPS). The research model was tested using auto-regressive cross-lagged model. The major results were as follows. First, adolescents' school life adjustment had a positive auto-regressive effect. Second, adolescents' life satisfaction had a positive auto-regressive effect. Third, adolescents' school life adjustment was a causal predictor of life satisfaction, but not vice versa. Finally, implications in terms of enhancing adolescents' school life adjustment and life satisfaction were also discussed.

• The Journal of the Korea Contents Association
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• v.22 no.9
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• pp.473-484
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• 2022

This study aimed to verify the reciprocal casual relationship between self-rated health status and depression in the elderly through longitudinal analysis. An autoregressive cross-lagged model was identified. This study analyzed 3,363 elderly people aged 65 or older using the 5th, 6th, and 7th wave data from Korean Longitudinal Study of Ageing(KLoSA). The results are as follows. First, self-rated health status had a positive(+) autoregressive effect. Second, depression had a positive(+) autoregressive effect. Third, self-rated health status had a negative(-) cross-lagged effect on depression, but depression was not a casual predictor of self-rated health status. Based on these findings, it was suggested that there is a need for systematic policies to improve basic fitness in the early stages of old age, as well as the need to expand health promotion programs and implement integrated depression management programs.