진행파를 이용한 디지탈 거리 계전기법의 고장발생각에 따른 고장거리 산출 보정에 관한 연구

정주환,서희석,김철환,신명철 成均館大學校 科學技術硏究所 1992 論文集 Vol.43 No.1

For many years digital protective methods have employed for the calculation of transient phenomena on power system networks caused by faults. This paper presents a travelling wave digital protection scheme to be used as an ultra high speed EHV/UHV transmission line relay. A detection of fault is made by a highly reliable relaying algorithm which makes use of the modal components of the voltage and currents which are caused to be superimposed on the steady state prefault power frequency components following the fault inception. Some of the potential problems and limitations associated with fault angles are achieved using correction factor. Varification of the algoithm is presented through digital computer numerical simulation using electromagnetic transients program(EMTP).

디지탈 계전기법에 의한 전선로 보호의 최적화

신명철,김철환,성낙환 成均館大學校 科學技術硏究所 1990 論文集 Vol.41 No.1

To maintain the high reliability and stability in the large scale electric power system for a stabilized power supplying, it requires an accurate high speed digital distance relaying techniques. For this purpose, when it comes to faults with the power system, the digital distance relaying techniques must be investigated to extract the fundamental frequency component and to predict fault location. In this thesis, it is presented the methodology of DFT(discrete Fourier transform), which accompanied aliasing, picket -fence effect, and leakage in the process of extracting fundamental frequency component and an algorithm of extracting fundamental frequency component, using the Kalman filter theory to improve upon these disadvantages. Also, a two-state and three---state Kalman filter are considered for the symmetrical components estimatin of voltages and currents respectively. It is presented an efficient digital distance relaying techniques for the purpose of extracting fundamental frequency component. Also, to confirm the validity of Kalman filtering techniques, it is shown the experimental results obtained by using the digital simulation of power system. And, it is discussed the extracted results of fundamental frequency components by means of the Fourier transform and Kalman filtering techniques.

영광 원자력발전소 3,4호기의 계통 병입에 따른 전력계통의 안정도 해석

박철원,권명현,김철환,신명철 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2

This paper deals with consideration for transient stability of power system The analysis of transient stability is very important because it detects the possibility of large scale outage by system collapse caused system configuration change and load unbalance. Two units YGN 3&4 will be connected to the YGN 1 & 2 switchyard through two 345KV circuits until 1996 because of the nuclear power plant construction according to power demand increment. Therefore it is necessary to study stability analysis, fault capacity calculation and power flow problem in assumption of two units YGN 3&4 operation interconnected with the power system Finally, considerations of the effect of interconnection and the establishment of preservation methods for reliability of stable opration of the power system are included in this paper.

상호상관 함수를 이용한 지중선로 고장점 추정

朴星完,林泳範,鄭州桓,成洛煥,金喆煥,申明徹 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2

This paper is intended as an investigation of fault location for underground line. Over the past few decades a considerable number of studies have been made on protection of underground line. However, these approaches require the interruption of electric power supply from source for fault location estimation. Therefore, we proposed fault location algorithm for underground line protection without interruption of electric power supply. Cross correlation function is used in this algorithm. Also, EMTP data is used to demonstrate the capability of the proposed fault location algorithm.

슬롯후드 입구 균일류 형성 조건

김환태,김태형,하현철,김은아 경성대학교 환경문제연구소 2000 環境硏報 Vol.10 No.1

Slot hoods are most commonly used to provide uniform exhaust air flow and an adequate capture velocity over finite length of contaminant generation, e.g. an open surface tank or over the face of a large hood such as a side-draft design. The function of the slot is solely to provide uniform air distribution. Industrial Ventilation Manual edited by ACGIH (American Conference of Governmental Industrial Hygienists) recommended the conditions to obtain uniform air distribution . slot velocity higher than 10m/s and take-off angle larger than 45 degree. But, in reality, it might not be an easy task to satisfy the conditions for uniform air distribution. By using CFD (Computational Fluid Dynamics), the 81 cases (3 aspect ratios x 3 mean slot velocities x 3 take-off angles x 3 duct velocities) were thus simulated and the coefficients of variance were computed to compare the uniformity of slot face velocities. Generally speaking, either aspect ratio or duct velocity do not affect the uniformity a lot while both slot velocity and take-off angle play a crucial role in forming uniform air distribution.

아동기 가정 내 스트레스가 공동의존성에 미치는 영향 및 공동의존성과 정신병리와의 관련성

곽운환,손지욱,한규희,박철수,김장락,김붕년,김봉조,강여화,하형래 대한생물치료정신의학회 2003 생물치료정신의학 Vol.9 No.1

연구목적: 본 연구는 공동의존성에 영향을 미치는 아동기 가정내 스트레스 요인과 공동의존성과 다른 병리와의 연관성을 규명하고자 하였다. 더불어 특정한 질환에서의 공동의존성의 평가가 가지는 의의를 탐색해 보고자 하였다. 방 법: 연구 대상은 정상 일반인 남성집단 88명과 알코올리즘 남성 집단 76명으로 구성되어 있다. 평가도구는 본 저자가 직접 작성한 '아동기 가정내 스트레스 요인 측정용 설문'과 공동의존 척도(RPS), 간이증상 진단검사(SCL-90-R)를 사용하였다. 통계적 분석은 Mann-Whitmey test, Kruskall- Wallis test, Multiple linear regression analysis, Spearman correlation analysis를 이용하였다. 결 과: 1) 정상 일반인 군과 알코올리즘 군의 공동의존성 평균값은 각각 49.12점(표준편차=15.41)과 88.31점(표준편차=17.48)이었다. 2) 정상 일반인 군에서는 '아동기 부모 사별'(p<0.01) '부모의 알코올리즘'(p<0.01) '부모의 상습적 구타'(p<0.01)의 3가지 요인에서, 알코올리즘 군에서는 '어린시절 부모 사별'(p<0.01) '부모의 알코올리즘'(p<0.01) '부모의 상습적 구타'(p<0.01) '부도의 도박'(p<0.01) '사회 병질자 부모의 존재'(p<0.05)의 5가지 요인에서 스트레스 유무에 따라 공동의존성에 유의한 차이를 보였다. 3) 두 집단 동시에 SCR-90-R의 8개 소척도 중 '대인관계 예민성'이 공동의존성과 가장 높은 연관성(rs>0.06, p<0.01)을 보였다. 이외에도 '우울증' '불안증'등이 두 집단 모두에서 통계적으로 유의한 연관성을 보였다. 결 론: 본 연구는 부모의 알코올리즘뿐만 아니라 여러 가정 내 스트레스 요인이 공동의존성의 발생에 영향을 미칠 수 있음과 공동의존성이 높은 집단이 다른 정신과 질환을 동반할 가능성이 높음을 증명한다고 할 수 있다. Objectives : The aim of this study was to examine the relationships of codependency with family stressors in childhood and psychopathology. Methods : Subjects were a group of 88 normal adult males and a group of 76 alcoholic males. The degree of codependency was assessed with the Korean version of Recovery Potential Survey(RPS). All subjects filled out questionnaires regarding demographic information and family stressors. The psychopathology was measured by self-administred questionnaires using Symptom Check List-90-Revision(SCL-90-R). Results : 1) There were no significant differences in codependency levels by sociodemographic characteristics in two groups, but obvious difference in mean of codependency scores(normal group : 49.12±15.41, alcoholism group : 88.31±17.48). 2) There were significant differences in codependency levels between the presence and absence of parental physical abuse, parental death, and parental alcoholism(p<0.01) in both groups. 3) Among family stressors, parental physical abuse had the largest contribution to codependency level in multiple linear regression. 4) There were significant correlations between the codependency levels and the scores of SCL-90-R's subscales of interpersonal sensitivity, depression, and anxiety in both groups. Conclusion : The codependency levels were related to some family stressors such as parental physical abuse, parental death, and parental alcoholism and the high-level codependency was correlated with higher level of psychopathology in both normal and alcoholism group. These results suggested that various family stressors, as well as parental alcoholism may be predictors of codependency, and codependency also may be a predictor of other psychiatric disorders.

出力 時間遲延이 있는 離散時間 線型 시스템의 最適出力 饋還器

鄭鐵煥,文光碩,李健一 경북대학교 공과대학 1984 工大硏究誌 Vol.13 No.-

This paper considers the problem of designing optimal output-feedback controller for discrete-time linear time-invariant systems with time delayed output. The new control law is defined by instantaneous output and time delayed output. The output responses were more improved by the new control law than that of the instantaneous output control law. To analyze the systems with time delayed output, the way is presented that transforms output time delayed systems into instantaneous output systems. The algorithm for simulation and a numerical example is presented.

油壓管路의 數學的 Model

吳哲煥 서울 敎育大學校 1985 論文集 Vol.18 No.-

정보사회와 초등정보교육의 방향

이철환 仁川敎育大學校 初等敎育硏究所 2000 교육논총 Vol.17 No.-

The aim of Information Education is to cultivate students' aptitude of obtaining, processing, exchanging and creating information on their own initiative. Students' information quality is a basic viability in new century. We can classify knowledge into five categories; 1) Know What - the fact, 2) Know Why - the scientific principles of the developing rules of the nature and the society, 3) Know How - the engineering and technology, 4) Know Where & Who - obtaining and utilizing information, and 5) Know New - innovation. Information Education has become the urgent problem that should be paid much attention in the course of educational reform in today's Korea. Information Education should include the following points according to the request of information environment in modern society. 1) Teach students to form the initial and scientific realization of information. 2) Teach students to form the correct attitude to life in information society. 3) Teach students the practical ability to utilize information smartly in school study and daily life. The study investigated the direction of the 7th curriculum, the meaning of informatized society, the new paradigm of education, and the trends and issues in information education for elementary school students. The study suggested some sound approaches for the learner centered instruction, self-directed instruction, and education of home-knowledgian. Finally, the study proposed status and directions of information education in elementary school.

북중국 환적화물 추정에 관한 실증연구 : 북미항로를 중심으로 Focusing on Transpacific Route

한철환 한국해운물류학회 2005 해운물류연구 Vol.44 No.-

본 연구의 목적은 우리나라 동북아 중심화전략의 성패가 달려있다 해도 과언이 아닌 북중국 항만들의 발전에 따른 국내항만의 환적화물 유치물량을 추정해 봄으로써 향후 국내 항만의 대응전략을 모색해 보는데 있다. 이를 위해 본 연구는 다리엔, 티안진, 칭다오 세 재 북중국 항만의 북미항로에 있어서 컨테이너 물동량과 모선의 기항선박량을 각각 추정하였고, 이를 토대로 향후 우리나라의 북중국발 환적화물을 시나리오별로 예측해 보았다. 그 결과, 선사들의 서비스별 기항항만수가 감소할 경우 향후 우리나라에서 처리할 것으로 예상되는 북중국발 환적물량은 2005년 7만 TEU, 2010년 IS만 TEU에 그칠 것으로 추정되었다. The main purpose of this paper is to forecast transshipment cargo from the Chinese Northern container ports-Dalian, Tianjin and Qingdao, focusing on Transpacific route. For this purpose, some empirical models for forecasting the container cargo from the three ports in Transpacific route, the fleet of mother vessel to call the those ports, the direct transport container cargo and that of transshipment are constructed. According to the results. the future amount of transshipment cargo, which come from the Chinese Northern ports, will be decreased to 70000TEU in 2005 and 150000TEU in 2010. Therefore, Korean ports are recommended to make its efforts the maximization of inherent cargo volume, increase of global shipping company's participation in port operation and creation of Global Advisory Council.