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.

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.

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).

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.

자연순환 온수 난방장치에서 열부하에 미치는 코일관 보일러의 형상인자들에 대한 연구

김철주,송기환 成均館大學校 科學技術硏究所 1992 論文集 Vol.42 No.2

So called "Saemaul-Boiler"is a domestic heating system composing a closed loop of tube, through which is circulating a hot water mobilized by natural convection effect in boiler. This heating system was simplified to a single phase closed thermo-loop, having an element of helically coiled tube heated externally by electric resistance wire. The investigation was put on some parameters of coil tube such as helix angle, curvature ratio and tube diameter in order to understand their effects on mass flow rate of working fluid in the loop system. From the results of the experiment it was shown that : 1) The heilx angle and diameter of coil tube might have a considerable importance on improuvement of thermal load by increasing mass flux of working fluid. 2) But the curvature ratio had relatively negligible effect.

地價公示制度의 改善方案에 관한 硏究

서철수,최창환 동아대학교 공과대학 부설 한국자원개발연구소 1993 硏究報告 Vol.17 No.1

The Current Exhibition System of the prices in Korea is similar to that of Japan. Because two countries have difficulties on land policy and land price system, partial improvement in policy to come true the aim is so difficult. The deep study on the land policy should be needed to keep a land price's stability and efficient utility of land.

HPLC에 의한 혈청 Haloperidol 분석에 관한 연구

楊秉煥,延炳吉,韓圭熙,感喆珪,金光日 漢陽大學校 精神健康硏究 1985 精神健康硏究 Vol.3 No.-

교육기관에서의 해킹 기법과 학내망 보안 방안에 관한 연구

이철환,한선관 인천교육대학교 과학교육연구소 2001 과학교육논총 Vol.13 No.-

본 연구는 교육기관에서의 학교망인 네트워크를 해킹하는 사례 및 이에 대한 보안 방법에 관한 연구이다. 이를 위해 보안의 중요성에 대해 논하고 최근 많이 발생하는 해킹 사고를 유형별로 분석하였다. 또한 이러한 해킹 사고가 학내망에 어떠한 위협을 주고 있으며 기술적으로 어떻게 발전하고 있는지 최근 해킹 동향 을 조사 분석하며 이를 방지하기 위한 보안 방법에 대해 논하였다. 마지막으로 바이러스의 위험과 그 예방에 대해 살펴봄으로써 실제 교육기관에서 적용할 수 있는 방향을 제시하였다. Security of network system is very important factor in the school information system. Almost all existing security systems are developed and implemented in very weak manner. And almost all computer is connected by security system at recently. Therefore, a majority of school network systems could be attacked by various hacking methods. The study investigate the methods of hacking technique and suggested a sound solution of school network security system. The importance of security, types of hacking/tracking accident, and the trends of hacking/ tracking method are reviewed. Finally the study summarized danger of virus, preventing method of virus, and implementation method in school system.

구강악안면영역에서 발생한 편평상피세포암종세포주에서 상피성장인자수용체의 발현 및 돌연변이에 관한 연구

김철환,김경욱 大韓顎顔面成形再建外科學會 2003 Maxillofacial Plastic Reconstructive Surgery Vol.25 No.2

Carcinogenesis has been considered as multiple stage process of denaturation of gene which control regulation of cell growth. The growth and differentiation of oral mucosal cell is controlled by growth factors which regulate development and differentiation of cell and apoptosis. It is well known that cell growth is not prevented, and secretion or reaction of growth factors is disturded in head and neck carcinoma including oral carcinoma. The epidermal growth factor is a polypeptide with potent mitogenic activitly of 6,045 daltons which has been shown to involve nuclear differentiation by trigger a cascade of intracellular ionic change and morphological transformation that it bind with epidermal growth factor receptor in surface of cells and delivering signal to inside of cells. The epidermal growth factor receptor is 170-kDa transmembrance phosphoglycoprotein. The extracelloular domain is binding site of epidermal growth factor, and intracellular domain possesses intrinsic tyrosine kinase astivity,which the stimulation can lead to autophosphylation of epidermal growth factor receptor and sequences lead to phosphylation of target protein in case of epidermal growth factor bind with target cell surface recrptor. Inrecently, eapression of epidermal growth factor receptor has been detected in oral squamous cell carcinoma, and overexpression of it is proved, and possibility of early markers of carcinogenesis in head and neck is presented. The many studies for the expression of epidermal growth factor receptor and relationship between it and prognosis of malignancy in carcinoma of breast or stomach have documented. But, in oral squamous cell carcinoma, the study for difference of amplication and mutation of epidermal growth factor receptor gene between primary carcinoma and merastastic carcinoma is rare. For study on mRNA expression of epidermal growth factor receptor,normal human oral keratinocyte, and cell lines of primary and metastastic oral squamous cell carcinomas were cultured, and then, electrophresis and RT-PCR(Reverse Transcriotion-polymerase Chain Reaction)were oerformed. The results were obstained as follows: The mutation of mRNA of EGF receptor were not detected in all oral squamous carcinoma cell lines. The expression of EGF receptor in oral squamous cell lines expressed 3-7 times higher than that of normal human oral keratinocyte of cytoplasmic domain. and 2-3times higher in extracellular domain. the expression of EGF receptor of cytoplasmic domain more expressed than that of extracellular domain in primary squamous cell line. The expression of EGF receptor in metastastic carcinoma cell lines is similis\ar or underexpressed than that of normal human oral keratinocyte cell lines. the expression of EGF receptor in the primary carcinoma cell lines expressed 2-5 times higher than that of metastastic carcinoma cell lines. From the results obtained in this study, the mutation have not mRNA of EGF receptor in carcinoma cell lines, and EGF receptor was overexpresses in early stage of carcinogemesis, and cytoplasmic domain of EGF receptor have relation with carcinogenesis, and EGF receptor have no relation with metastasis.

모집 및 채용과정에서의 장애인 고용차별실태에 관한 연구

박철현,나운환 대구대학교 국제재활과학연구소 2004 再活科學硏究 Vol.22 No.1

본 연구의 목적은 고용차별 개념과 기준을 토대로 우리나라 장애인 모집 및 채용과정에서의 차별실태를 진단하기 위함이며 그 결과는 다음과 같다. 첫째, 400개 회사 중 91.3%가 응시자격의 직접적인 차별기준이 없는 것으로 나타났으며, 간접적인 차별의 경우 모집회사의 91.3%가 학력, 연령제한 등으로 간접차별을 명시하고 있었다. 둘째, 채용절차에 있어서는 채용전 신체검사요구를 하는 직접적인 차별을 하는 구인회사가 67.8%로 나타났고 간접차별은 시험이나 면접시 적절한 배려와 인터넷 서류접수시 시각장애인 배려규정이 없는 회사(99.5%), 지원서에 신체조건을 표기하도록 하는 회사(82.5%)로 분석되었다. 그리고 직접적 채용절차 차별의 경우 기능종사자나 조립, 단순노무직과 300인 이상 규모가 입법 등, 전문가, 기술공, 사무직, 서비스직과 300인 이하 규모가 차별이 심한 것으로 나타났으며 신체조건표기의 경우는 전문가, 기술공, 사무직, 서비스직 등이 모두 차별이 심한 것으로 분석되었다. 셋째, 응시자격과 간접적 차별내용에 있어 학력제한과 연령제한은 종업원규모와 직종별로 차이가 있는 것으로 나타났다. 즉, 300인 이상 업체와 직종별로는 전문가, 기술공, 사무직, 서비스직이 300인 이하 업체와 조립, 기능직, 단순노무직보다 학력제한을 하고 있는 것으로 분석되었으며, 연령제한의 경우는 300인 이하 업체와 단순노무, 조립, 기능원, 서비스직이 연령제한을 하고 있는 것으로 분석되었다. The main purpose of this experiment was to find the difficult and unequal situations that individuals with disabilities meet when it comes to recruiting and employment process for jobs. The result from this experiment is that first of all, out of 4 hundred companies, 365 companies which is 91.3% show it in their application that they do not discriminate the individuals with disabilities. Secondly, out of companies that are looking for employees, 67.8% (271 companies) of them said that they had certain elements that need to be agreed with the employee. Most of the time, these companies require the employees to have a physical check from the doctor. And 99.8% (398 companies) of the companies show an indirect discrimination against the individuals with disabilities. For example, 99.5% (398 companies) of them don't show any reasonable accommodation during the interview nor through out the registration paper online for the blinds, and 82.5% (330 companies) requires them to fill out the physical condition of the employees. Lastly, it is proven that the employees with disabilities have discrimination on their scholastic ability and age limits depending on what job they apply to. In a condition where employees have discrimination on their scholastic ability, it's usually when they apply for jobs such as office worker, professional work in certain areas. When they have age limit, that's when they apply for works such as constructing, organizing, works that need skill and etc. Considering the result from this experiment, conclusion is that one, there shouldn't be any direct or indirect discrimination items against the individuals with disabilities when one applies for a job and there should be a set of laws to it. Two, in the process of employing, to prevent any indirect discrimination from happening, there should be a special management responsible to it. At last, in the process of employment a disability discrimination law should be enacted.