• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2004년도 학술대회지
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• pp.47-84
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• 2004

Principal Component Analysis나 Partial Least Squares와 같은 다변량 통계 기법은 변수간의 correlation structure로부터 공정의 variance를 설명할 수 있는 latent variable를 얻고 이를 이용하여 공정을 효과적으로 modeling할 수 있는 방법으로 최근 들어 많은 관심을 얻고 있다. 하지만 PLS는 공정이 stationary state에 있다고 가정하기 때문에, 생물학적 공정의 non-stationary and time-varying behavior를 설명하기에 부적절하다. 본 논문에서는 PLS 알고리즘의 혐기성 폐수처리 공정에의 적용에 있어, 이와 같은 문제를 해결하기 위해서 adaptive PLS 알고리즘을 사용함으로써 변화하는 공정의 특성에 대응하여 모델을 update하는 방법을 이용하였다. 하지만 실시간 데이터로부터 adaptive PLS 방법을 적용하는 데에는 많은 어려움이 존재하며, 특히 outlier나 abnormal disturbance에 모델이 부적절하게 adaptation하는 문제가 발생할 수 있다. 따라서 이의 해결을 위해 adaptive PLS를 적용하는데 있어 robustness를 향상시키기 위해 monitoring index를 이용하여 abnormal data에 weight를 주고 안정적인 모델의 update가 가능하게 하는 방법을 제안하였으며, 이를 적용하여 성공적으로 혐기성 폐수처리 공정의 Output을 예측하고 효과적으로 공정을 모니터링할 수 있었다. 만들어진 PLS 모델은 산업폐수를 처리하기 위한 industrial plan에서 측정된 실제 데이터에 적용하여 그 효용성을 입증하였으며, 그 결과는 mechanistic model을 적용하기 힘든 실공정에 비교적 쉽게 implementation할 수 있는 장점이 있다.

• 전자공학회논문지S
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• 제34S권4호
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• pp.1-11
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• 1997

In this paper, modeling of the communication channel occupancy characteristics at the base station in the wide area radio trunking syste has been performed. Using the results, mathematical analysis for the switching capacity at the network switch has also been done. Specificatlly, we propose a G/M/m queueing model for the single service area modeling, and analyze changes in call blockingprobabilities accoridng to changes in the burstness characteristics of group paging calls. As a result, we have observe dthat the channel occupancy variations become larger as the burstness characteristics become more apparent, to make the call blocking probability higher. Next, based on the single service area analysis, we have anayzed mathematically the average switching capacity required to serve mobile subscribers for a wide area radio trunking sytem, where multiple switching port assignments are required when the people in the same group are distributed over several base stations. Accordingly, we have observed that the average and the variance of switching channel occupancy are closely related to the mobility characteristics of subscribers, and that we need a netowrk switch having bigger capacity as subscribers show wider distribution. Especially, with the call dropping probability within 0.2%, a switch having about 5 to 6 times bigger can be required, compared with the one when the mobility of subscribers is mostly restricte dto a single service area.

• Transactions on Electrical and Electronic Materials
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• 제7권2호
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• pp.81-86
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• 2006

In this paper, the response surface modeling of the control of the pretilt angle in the nematic liquid crystal on the homogeneous polyimide surface with different surface treatment is investigated. The pretilt angle is one of the main factors to determine the alignment of the liquid crystal display. The pretilt angle is measured to analyze the variation of the characteristics on the various process conditions. The rubbing strength and the hard baking temperature are considered as input factors. After the design of experiments is performed, the process model is then explored using the response surface methodology. The analysis of variance is used to analyze the statistical significance and the effect plots are also investigated to examine the relationship between the process parameters and the response.

• 보건행정학회지
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• 제16권4호
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• pp.1-23
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• 2006

There is general consensus in the research literature that market orientation is related to organizational performance. The study examines this relationship in the Korean hospital industry. One feature of this study is to examine the differences between large and small hospitals in terms of their market orientation, performance and the relationship between these constructs. The other feature is that both market orientation and performance are conceptualized as being multi-dimensional constructs. Hence a structural equations modeling (SEM) technique is used to examine the dimensionality of market orientation and performance and to examine the nature of this relationship. Data for this study are collected using a questionnaire that is mailed to the top marketing-related managers of 1,048 hospitals. Usable responses are obtained from 230 hospitals for a response rate of 21.9%. The SEM results confirm the multi-dimensional nature of both market orientation and performance, and the strong relationships between the constructs. Interestingly, this relationship is found to be much stronger for smaller hospitals than for larger hospitals. For smaller hospitals, this study shows that market orientation has a tremendous influence on performance, with almost 73.9% of the variance in performance being attributed to market orientation.

• 대한간호학회지
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• 제40권4호
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• pp.533-541
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• 2010

Purpose: This study was designed to test structural equation modeling of the quality of life of stroke survivors in order to provide guidelines for development of interventions and strategies to improve their quality of life. Methods: The participants in the study were patients who visited the neurology outpatient department of a tertiary hospital in Seoul between June 25 and October 15, 2009. Data collection was carried out through one-on-one interviews. Demographic factors, functional independence, social support, nutritional status, post-stroke biobehavioral changes and quality of life were investigated. Results: The final analysis included 215 patients. Fitness of the hypothetical model was appropriate (${\chi}^2$=111.5, p=.000, GFI=.926, AGFI=.880, RMSA=.068, NFI=.911, CFI=.953). Functional dependency, social support and post-stroke biobehavioral changes were found to be significant explaining variance in quality of life. Post-stroke biobehavioral changes had the strongest direct influence on quality of life. Nutritional status had an indirect effect on the quality of life. Conclusion: To improve the quality of life of stroke survivors, comprehensive interventions are necessary to manage post-stroke biobehavioral changes, and strengthening social support networks that can contribute to enhancing the quality of life of stroke survivors.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 춘계학술대회 논문집
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• pp.24-29
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• 1996

The seniconductor, which is precision product, requires many inspection processes. The surface conditions of the semiconductor chip effect on the functions of the semiconductors. The defects of the chip surface is crack or void. Because general inspection method requires many inspection processes, the inspection system which searches immediately and preciselythe defects of the semiconductor chip surface. We propose the inspection method by using the computer vision system. This study presents an image processing algorithm for inspecting the surface defects(crack, void)of the semiconductor test samples. The proposed image processing algorithm aims to reduce inspection time, and to analyze those experienced operator. This paper regards the chip surface as random texture, and deals with the image modeling of randon texture image for searching the surface defects. For texture modeling, we consider the relation of a pixel and neighborhood pixels as noncasul model and extract the statistical characteristics from the radom texture field by using the 2D AR model(Aut oregressive). This paper regards on image as the output of linear system, and considers the fidelity or intelligibility criteria for measuring the quality of an image or the performance of the processing techinque. This study utilizes the variance of prediction error which is computed by substituting the gary level of pixel of another texture field into the two dimensional AR(autoregressive model)model fitted to the texture field, estimate the parameter us-ing the PAA(parameter adaptation algorithm) and design the defect detection filter. Later, we next try to study the defect detection search algorithm.

• Safety and Health at Work
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• 제6권4호
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• pp.279-288
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• 2015

Background: In this study, the measurement of job stress of electric overhead traveling crane operators and quantification of the effects of operator and workplace characteristics on job stress were assessed. Methods: Job stress was measured on five subscales: employee empowerment, role overload, role ambiguity, rule violation, and job hazard. The characteristics of the operators that were studied were age, experience, body weight, and body height. The workplace characteristics considered were hours of exposure, cabin type, cabin feature, and crane height. The proposed methodology included administration of a questionnaire survey to 76 electric overhead traveling crane operators followed by analysis using analysis of variance and a classification and regression tree. Results: The key findings were: (1) the five subscales can be used to measure job stress; (2) employee empowerment was the most significant factor followed by the role overload; (3) workplace characteristics contributed more towards job stress than operator's characteristics; and (4) of the workplace characteristics, crane height was the major contributor. Conclusion: The issues related to crane height and cabin feature can be fixed by providing engineering or foolproof solutions than relying on interventions related to the demographic factors.

• 한국언론정보학보
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• 제61권
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• pp.28-51
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• 2013

본 연구는 소비자 기반 브랜드 자산 모형에 기반한 기존의 미디어 브랜드 확장 모형을 응용하여 이러한 브랜드 확장이 모 브랜드(Parent Brand)에 미치는 영향을 분석하고자 하였다. 선행연구들을 바탕으로 확장 전 모 브랜드 평가, 브랜드 포트폴리오 품질 변량, 지각된 브랜드 확장 수, 모 브랜드와 확장된 브랜드 간 지각된 적합성, 브랜드 확장상품 평가 등이 확장 후 모 브랜드 평가에 영향을 미치는 것으로 연구모형을 구성한 뒤 구조방정식모형을 이용하여 검증하였다. 분석결과, 확장 후 모 브랜드 평가에 확장 전 모 브랜드 평가, 브랜드 포트폴리오 품질 변량, 적합성, 브랜드 확장상품 평가가 유의미한 영향을 미친 반면 지각된 브랜드 확장 수의 영향력은 유의미하지 않았다. 본 연구를 통해, 첫째, 수직적 브랜드 확장에서 적합성은 확장상품 평가에는 정적인 영향을 주지만, 확장 후 모 브랜드 평가에는 부적인 영향을 미친다는 것을 확인하였다. 둘째, 브랜드 포트폴리오 품질 변량은 적합성과 확장상품 평가, 확장 후 모 브랜드 평가에 부적인 영향을 준다는 것을 새롭게 알아내었으며, 모 브랜드 평가가 브랜드 포트폴리오 품질 변량에 부정적인 영향을 미친다는 것을 확인하였다. 셋째, 모 브랜드 미디어에 대한 평가가 적합성에 부적인 영향을 미친다는 것을 발견하였다.

• 한국응급구조학회지
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• 제5권1호
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• pp.147-164
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• 2001

The purpose of this study was to examine the hypothetical model designed to explain the post-traumatic stress and burnout in firefighters. Six exogenous variables such as career, control, impact mobilization frequency, life event, work burden, social support, and four endogenous variables, eg., mobilization impact, coping, post-traumatic stress, burnout were considered for the study. The target population for the distribution of the questionnaire was 428 firefighters in Daejeon, Chungnam Province, Seoul and Kyonggi Province. The data was collected about five weeks, July 12-August 25, 1999. The survey instrument was 8 control items by Seo(1995), 10 life event items by Brugha and Cragg(1990), 20 work burden items by Choi(2000), 12 social support items by Park(1985), post-traumatic stress of 17 items by Foa et al.(1998) and 45 items by Kang(1997). The reliability of the survey instrument and the cronbach's alpha was .62 - .93 level. SAS PC Program and LISREL 8.12a program were used for descriptive statistics and linear structural relationship(LISREL) modeling. Based on the data collected, the following results were obtained. 1. The overall fit of the hypothetical model to the data was good (${\chi}^2=54.65$ [df=17, p=0.000007], RMSEA=0.07, standardized RMR=0.03, GFI=0.98, AGFI=0.91, NFI=0.90, NNFI=0.75). 2. After considering statistical significance and theoretical meaningfulness of paths of the model, a modified model was sought. Compared to the hypothetical model, the modified model has become parsimonious and had a better fit to the data(${\chi}^2=55.90$ [df=20, p=0.0003], RMSEA=0.06, standardized RMR=0.03, GFI=0.98, AGFI=0.93, NFI=0.90, NNFI=0.80). 3. The results of statistical testing of hypotheses were as follows: (1) Work burden, career had a significantly direct effect on mobilization impact. These variables explained 9% of the total variance of mobilization impact. (2) Control, social support, work burden, mobilization impact had a significantly direct effect on coping. These variables explained 15% of the total variance of coping. (3) Control, work burden, social support, coping had a significantly direct effect on post-traumatic stress. These variables explained 49% of the total variance of post-traumatic stress. (4) Coping, post-traumatic stress had a significantly direct effect on burnout. These variables explained 60% of the total variance of burnout.

• 한국정보통신학회논문지
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• 제17권9호
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• pp.2227-2232
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• 2013

유도제어 시스템 체계개발의 초기단계에는 운용 효과도 도출 및 요구사항 적합성 검토를 통한 체계 개략사양도출을 위해 효과도 분석을 수행한다. 본 논문의 목표는 M&S (Modeling & Simulation)를 활용한 운용 효과도 분석을 통해 고속 무인 수중운동체의 목표점 도달 임무를 위한 체계 요구사항 도출이다. 운용 효과도는 대상 수중운동체의 목표점 도달 정확도로 정의한다. 도달 정확도에 가장 큰 영향을 미칠 것으로 예상되는 변수는 항법센서 성능이다. 본 논문에서는 관성항법센서(Inertial Navigation Sensor, INS)와 도플러 속도 측정 장치(Doppler Velocity Log, DVL)를 이용한 복합항법을 고려하였다. 몬테카를로 수치 시뮬레이션을 통해 항법센서 성능에 대한 효과도 분석을 수행한다. 몬테카를로 수치 시뮬레이션 결과는 CEP(Circular Error Probability)와 분산을 이용한 확률분석을 통해 분석한다. 상용 항법센서 가격을 고려하여 최적의 가격대 성능비를 갖는 항법센서 성능을 제시한다.