• Journal of the Korean Operations Research and Management Science Society
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• v.12 no.1
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• pp.19-26
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• 1987

In analyzing time series, estimating the level or the current mean of the process plays an important role in understanding its structure and in being able to make forecasts. The studies the class of time series models where the level of the process is assumed to follow a random walk and the deviation from the level follow an ARMA process. The estimation and forecasting problem in a Bayesian framework and uses the Kalman filter to obtain forecasts based on estimates of level. In the analysis of time series, we usually make the assumption that the time series is generated by one model. However, in many situations the time series undergoes a structural change at one point in time. For example there may be a change in the distribution of random variables or in parameter values. Another example occurs when the level of the process changes abruptly at one period. In order to study such problems, the assumption that level follows a random walk process is relaxed to include a major level change at a particular point in time. The major level change is detected by examining the likelihood raio under a null hypothesis of no change and an alternative hypothesis of a major level change. The author proposes a method for estimation the size of the level change by adding one state variable to the state space model of the original Kalman filter. Detailed theoretical and numerical results are obtained for th first order autoregressive process wirth level changes.

• Journal of Distribution Science
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• v.14 no.12
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• pp.61-69
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• 2016

Purpose - This study investigates the determinants that affect the number of IT Incident tickets of an IT Service Provider ("ITSP") to logistics industry in order to improve its management process by reducing the incident tickets. Research design, data, and Methodology - This study uses weekly data of IT incident tickets from September 2012 to June 2015. Correlation and regression analyses are conducted. Six identified determinants i.e., IT Change, User Errors, Shipment Volume, Network, Hardware and Software Issues are used as the explanatory variables. Results - Our findings show as following. First, our analysis indicates that IT Change is not a significant determinant as opposed to what commonly believed by many as the most important factor. Second, Software issue is the highest contributor to the Major IT incident tickets, followed by User Error, Network and Hardware issues. Third, it seems there is lead-lag relationship between IT Change and Major IT Incidents tickets as indicated by earlier studies. Fourth, the relationship between IT Change and Major IT tickets is also affected by shipment volume. Conclusions - As policy recommendation, all identified determinants should be treated according to priority. In addition, improving the way IT Changes are implemented will definitely reduce the IT incident tickets.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.87-99
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• 2013

For analysis of climate change effects on agriculture, precise agricultural meteorological data are needed to target period and site. In this study, agricultural meteorological data under new climate change scenario (RCP 8.5) are constructed from 2011 to 2099 in 111 agriculture major station suggested by Rural Development Administration (RDA). For verifying constructed data, comparison with field survey data in Suwon shows same trend in maximum temperature, minimum temperature, average temperature, and precipitation in 2011. Also comparison with normals of daily data in 2025, 2055, and 2085 shows reliability of constructed data. In analysis of constructed data, we can calculate sum of days over temperature and under temperature. Results effectively show the change of average temperature in each region and odd days of precipitation which means flood and dry days in target region.

• Korea journal of population studies
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• v.9 no.2
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• pp.53-66
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• 1986

This study was carried out to determine the mortality level and it's related demographic factors in Korea since 1942. In order to clarify the changes in structure of mortality and the causes of death, the indices such as Crude Death Rate(CDR) or Life Expectancy at Birth were used. The author examined the mortality levels and major causes of death and performed the relevant demographic analysis. The followings are the summary of this study: 1. The CDR declined rapidly till 1960's. Such improvement slowed down from 1960's to mid 1970's and stabilized afterwards. It was due to the change of age composition, namely, the increase of aging population. 2. The Life Expectancy at Birth increased rapidly till mid 1960's. But elongation of the Life Expectancy slowed down after then. Especially in female, it slowed down more. 3. Changing patterns of major causes of death summarize that, till 1960's infectious diseases were major causes of death, but recently non-infectious diseases like chronic degenerative diseases became more prevalent. 4. The elongation of Life Expectancy at Birth till mid 1960's was mainly resulted by $_4{q}_1$. But the major contributing factor of the improvement in Life Expectancy at Birth in female is he reduction of $_$\infty${q}_{50}$ recently. In male, the improvement in Life Expectancy at Birth is due to the reduction of $_1{q}_0$. recently. 5. The age-sex-specific mortality rates revealed that $_n{q}_x$ declined in common throughout the period, even though there exists some variability of their ranges as age changes. Consequently, this study seems to suggest that the demographic transition in Korea occurred between late 1960's and early 1970's. In other words, the rapid change before late 1960's was eased in early 1970's. The slow change in this period caused a stabilizing pattern. Therefore, the population change is expected to be stabilized continuously.

• Journal of Engineering Education Research
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• v.18 no.1
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• pp.31-40
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• 2015

This study explored the trend of higher education policy according to the change of productive populations. This study analyzes current problem on higher education policy and suggests direction of higher education policy according to decrease in productive population, focusing on the change in productive populations and related social changes. The major directions of higher education policy are enhancing competitiveness of universities, managing university enrollment quota, and activating education - industry links. This study suggests twelve detailed - policies based on the three major directions of higher education policy.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.214-215
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• 2022

This study analyzed the development stage and change management necessity of the construction IT system through existing research and literature review, and used WordCloud, one of the text mining techniques, to analyze current construction trends and major issues. The necessity of change management is derived by using existing research literature and construction-related social issues as analysis data.

• Physical Therapy Korea
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• v.29 no.2
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• pp.131-139
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• 2022

Background: Shoulder impingement syndrome, a major cause of shoulder pain, involves weakness of the scapular retractor muscles. The major scapular retractor muscles are the middle trapezius and rhomboid major muscles; however, the latter is excluded in most studies. Objects: We aimed to measure the thickness of the middle trapezius and rhomboid major muscles using an ultrasonic diagnostic imaging system while performing four different shoulder retraction exercises and comparing the thicknesses and ratio of the thicknesses of these muscles. Methods: The thickness of the middle trapezius and rhomboid major muscles was measured in 24 healthy adults using ultrasound. Muscle thickness was measured three times in the Reference posture and four times while performing four different exercises that involved scapular retraction. The averages and standard deviations of the measured muscle thicknesses were obtained and compared. The ratio of muscle thickness and rate of changes in muscle thickness between the reference posture and the four exercises were compared. Results: For both, male (n = 10) and female (n = 14), there was a significant difference in the thickness of the middle trapezius muscle between the reference posture and the four exercises (p < 0.05) and in the thickness of the middle trapezius and rhomboid major muscles between male and female (p < 0.05); however, there was no significant difference in the ratio of the thicknesses of these muscles. Although a significant difference in the rate of change in muscle thickness during the four exercises was noted, there was no significant difference in the ratio of change in muscle thickness. Conclusion: This study demonstrates the ratio of the thicknesses of the middle trapezius and rhomboid major muscles and the rate of change in their thickness during exercises involving scapular retraction in healthy people in their 20s-30s.

• Journal of architectural history
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• v.2 no.2 s.4
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• pp.50-65
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• 1993

Most of the studies on Yangban Houses dealt with the existing houses which were constructed, in most part, after the 17th century. Therefore it is important to identify the actual process of change from before the 17th century which is critical in understanding the history of residential architecture of the Chosun Dynasty. This study aims to clarify that the architectural condition after the 17th century is the result of the major change in sound the 16th century, and the prime motivation of that change was initiated by the family ritual which become very important social and idealogical base of the change. To be able to practice the family ritual, the spatial arrangement had to be changed, Man's quarter had to be enlarged, which a stone-floored room was added on one side of the centural wooden floor of the lady's quarter. Also, family shrine was erected on eastern side of the site. Thus, unless the major change in the 16th century, which was caused by the practice of family ritual, is understood, the study of historical background of Yangban houses can never be complete.

• Korean Journal of Health Education and Promotion
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• v.20 no.3
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• pp.255-267
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• 2003

The purpose of this study is to analyze the affecting factors on self-efficacy of walking exercise. The subjects were 413 working men. Whose data and material were collected through an organized questionnaire from October, 1999 to May 2000. The major results of this were as follows； 1. 61.1％ of the subjects' major affecting factor was deep sleep, 65.0％ of the subjects' majo affecting facto was regular physical screening, 51.1％ of the subjects' regular exercise, 18.7％ of the subjects' walking exercise. 2. stages of change related to walking exercise of the subjects were as follows, 15.8％ of the subjects were in the precontemplation stage, 51.1％ of the subjects were in the precontemplation stage. 3. The average self-efficacy concerning walking exercise was 3.16 points. 4. With stepwise multiple regression, the most significant factor on self-efficacy related to walking exercise in stages of change was the preparation stage. According to the results of this study, a concrete practice program is needed to promote self-efficacy related walking exercise.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.51-58
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• 2016

On account of the increase in water demand and climate change, droughts are in great concern for water resources planning and management. In this study, rainfall characteristics with stationary and non-stationary perspectives were analyzed using Weibull distribution model with 40-year records of annual minimum rainfall depth collected in major cities of Korea. As a result, the non-stationary minimum probable rainfall was expected to decrease, compared with the stationary probable rainfall. The reliability of ${\xi}_1$, a variable reflecting the decrease of the minimum rainfall depth due to climate change, in Wonju, Daegu, and Busan was over 90%, indicating the probability that the minimal rainfall depths in those city decrease is high.