• 전기학회논문지
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• 제58권10호
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• pp.1911-1915
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• 2009

The problem of determining the proper capacity of electric vehicle charging station is studied in the presented paper. Based on the expected arrival rate and the expected charging time, we calculate the proper capacity that guarantees electric vehicles get service better than a given lower bound which is termed the loss of charging probability. The problem is studied by using certain queueing models. We first formulate the problem as a queueless model of type M/M/n/n, known as the Erlang loss system. And then the M/M/n/K type queueing model is formulated to consider the parking space constraint. Results of the study may be used for designing the electric vehicle charging station.

• 대한기계학회논문집B
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• 제27권6호
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• pp.677-684
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• 2003

A new unipolar aerosol charger was developed by using an indirect photoelectric charging. The charger consists of two coaxial tubes, the inner UV lamp wrapped with stainless mesh and the outer Al cylinder. In this study, the effects of flow rate, particle size, and electric field were examined to search the optimal charging conditions with experimental and numerical methods. Monodisperse NaCl particles were fed into an annular space and the particles were charged by negative ions generated from Al plate exposed to the UV light. According to experimental results, the average number of elementary charge on particles increases from 2.5 to 5.5 as particle size increases from 50nm to 130nm at 2.5 L/min and 100V. The average number of elementary charge on particles was maximized at 25V as the electric potential between the stainless mesh and Al plate was varied from 0V to 400V.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.123-126
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• 2005

In this study, the Thermally Stimulated Current(TSC) of corona charged PTFE is studied and the simulation of corona charging process is also calculated by Finite Element Method. The electrets which were formed by applying high voltages (DC ${\pm}5{\sim}{\pm}8$ [kV]) to PTFE, are used to measure TSC in the temperature range of $-100{\sim}+200$ [$^{\circ}C$] and then the Finite Element Method is performed to examine corona charging process using a obtained physical constants. As a result. it is confirmed that the charging negative corona is profitable as the applications are manufactured, because the time constant of negative corona is much larger than it of positive corona. And it is attempted to estimate the corona charging process in space using simulation.

• 한국의료질향상학회지
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• 제4권1호
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• pp.116-124
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• 1997

Background : As parking problem caused by increasing owner-driver and patients concentrating to a general hospital is becoming one of the dissatisfactions in medical care. It is time that a general hospital should solve the parking problem in a desirable way. The purpose of this survey is to let the clients understand the basic motivation of the pay parking and develop the better parking system. Methods : Clients of a tertiary care hospital in Chon-ju were surveyed by means of a questionnaire. All in all, 193 subjects answered the questionnaire. Results : In relation to previous experiences, 39.6% of the subjects experienced inconvenience with confused parking lot and the shortage of parking space. Under the current parking system, the subjects who felt the available parking space was enough were more than those who didn't 62.7% of the subjects answered that they could find the parking lot easily. 33.2% of the subjects mentioned that it was not easy to drive in the parking area ; The reasons were pointed out the shortage of space, disordered parking, and insufficient guide. 12.8% of the subjects satisfied with the current administering system of parking lot. The outpatients were more affirmative than the admitted patients about the charging system. As for the parking fee, 64% of the subjects answered that it is expensive, and 89.5% of the subjects thought imposing of parking fee is irrational. Conclusion : To say as a whole, the basic purpose of the charging system are more or less accepted. However, the management details like parking facilities and payment method are dissatisfactory, so it is necessary to improve the management system. It is also noted that the inpatients showed more negative attitude than the outpatients with the charging system. To secure a more convenient parking, the parking system should be considered in relation to the information service, kind guidance, improve facilities, personnel cooperation, fix outpatient scheduling system, etc.

• 교육시설
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• 제15권5호
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• pp.21-32
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• 2008

The major issues that higher education has recently faced are the shortage of students of school age, the changing environment of higher education and the evolving technology. These challenges have urged the university facilities and space to be managing more efficient and more effective. This study assures that the strong strategy is to operate more like business while retaining unique higher education values and a sound facilities management system and appropriate budget help to ensure that university facilities are good for student and teacher's demand. With such faith, this study explores the facilities/space maintaining status and the facility management system of national universities and collages. It finds that there are some problems to adapt new managing methodologies in national universities and that there are also some gaps and perceived constraints to effective space management. This study proposes the alternatives for the facilities managing system that involves the improvement of manpower structure, the expansion of budget scale and the establishment of appropriate facility management system. Finally it provides the practical tools for the effective space and facilities management such as space charging, space standards, central timetabling, space utilisation survey and facilities performance indication.

• 설비공학논문집
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• 제13권4호
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• pp.289-294
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• 2001

A well defined electro-spraying and electro-static precipitator(ESP) experiment is carried out to investigate the charging characteristics of the submicron particles and the monodisperse particles. The basic idea is that the highly charged electro-sprayed droplets will be produced into the gas when the Coulombic repulsive force on the surface is higher than the surface tension of the spraying liquid. During this process many highly charged smaller droplets or ions, if the droplets are completely dried out, will be produced in the space. These charged species will be attached ion the particles and then eventually charge the particles. These charged particles will be easily collected with ESP. The experimental results show that the atomizer generated particles with geometric mean diameter (GMD) of 62nm are charged more than 90% even at the mean face velocity of 2.5m/s at the charging zone.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
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• pp.94-98
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• 1994

In this study, the thermally stimulated current(TSC) of corona charged PTFE film was studied and the simulation of corona charging process was also calculated by finite element method. The electrets which were formed by appling high voltages(DC-5∼-8[kV]) to PTFE film were experimented to measure TSC in the temperature range of -100∼+200 [$^{\circ}C$] and then the finite element method was accomplished to examine corona charging process using a obtained physical constants. It is confirmed that the charging negative corona is profitable as the applications are manufactured because the time constant of negative corona is much larger than it of positive corona. And it is attempted to estimate the corona charging process in space using simulation.

• 한국항공우주학회지
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• 제46권6호
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• pp.513-518
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• 2018

KUH-1에 적용되는 질소충전트레일러는 항공기의 주/전륜 완충기, 테일범퍼완충기, 브레이크 축압기, 타이어 등에 질소를 충전하는 장비이다. 명칭에서 알 수 있는 것과 같이 질소충전트레일러는 질소 충전과 더불어 이동성을 가지고 있는 장비이다. 기존 미국의 Tronair사에서 독점 공급하여 국내에서는 수입에 의존하던 품목이며, 본 국산화 개발품은 도입품의 성능을 만족할 뿐만 아니라 운용 시 도입품보다 용이하도록 설계를 추진하였다. 제15-4차 민관공동투자사업으로 선정되어 개발이 진행되었으며, 민관투자기업인 한국항공우주산업과 국방기술품질원의 개발관리 지원하에 개발요구도 분석 및 시험평가가 수행되었으며, 2017년 5월 군사용 적합 판정 결과 승인을 받았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.169-171
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• 1993

In order to estimate space charging process in the corona charging apparatus which has been used to make polymer electret cell, the electrical properties of 30[${\mu}m$] thick polypropylene film were obtained from TSC measurement after corona charging between copper knife electrode and aluminum cylinder electrode with the voltage of -8, -7, -6, -5 (kV). And, the electrostatic contour and the electric field vector were calculated using Finite Element Method with the electrical properties obtained from TSC spectra analysis. The edge effect around the edge of knife electrode affects electrostatic contour on the surface of specimen and the electric field concentration inside the polymer. As a result the uneven charging state in the electret cell due to the mistake of design was calculated, and the optimal design of corona charging apparatus opprobriate to various specimen was come to be practicable.

• 항공우주기술
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• 제8권2호
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• pp.122-126
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• 2009

KSLV-I은 100kg급 소형 인공위성을 지구 저궤도에 진입시키는 임무를 수행하여야 하며, 이를 위해 상단의 3축 자세제어를 위한 자세제어 시스템이 요구된다. 추력기 노즐을 통해 질소가스를 방출함으로써 발생하는 작용 반작용 모멘트를 제어모멘트로 사용하는 냉가스 추력기 자세제어 시스템을 KSLV-I 상단의 3축 자세제어 시스템으로 선정하였다. 충전 시스템의 유량 검증 및 충전 시나리오 작성을 위해 지상 충전 시스템 개발 전단계로 충전모사 시스템의 개발이 필요하다. 본 논문에서는 KSLV-I 충전 모사 시스템의 오리피스 설계, 시스템 개발, 충전 시험에 관한 것이다.