• Proceedings of the KIEE Conference
• /
• 2002.11d
• /
• pp.218-220
• /
• 2002

본 연구에서는 정상상태에서 고조파 전류와 순시전압 강하에 대한 보상성능이 우수한 3상 전압 Sag 및 고조파 전류 보상 시스템을 제안하고 있다. 제안된 시스템의 보상 알고리즘으로는 구현하기 쉽고 간단한 직접 필터링 알고리즘이 사용되고 있으며 하이브리드 직렬형 능동전력필터에 적용하였다. 제안된 알고리즘은 전원전압이 순간적으로 왜형과 sag가 발생되더라도 비선형 부하에 인가되는 전압은 일정한 정현파로 제어 가능하며 동시에 전원전류의 고조파와 기본파 무효전류도 보상 가능하다. 정상상태와 과도상태에서 전력전자전용 시뮬레이터인 PSIM에 의해 제안된 이론의 타당성을 입증하였다.

• Proceedings of the KIEE Conference
• /
• 2002.04a
• /
• pp.190-197
• /
• 2002

The goal of this paper is to propose a virtual instrumentation system based on three dimensional current coordinates for monitoring power quality. A developed system with various experimental graphic screens and numerical results is made up 586-PC and DSP(digital signal processor) board, power quality analyzing and evaluating software for windows. Power parameters are analyzed using correlation signal processing techniques based on the correlation between voltage and current waveforms. Analysis results are visualized by 3-D current coordinates, and it is compared and evaluated with conventional time/frequency domain. To verify the validity of the proposed system, power and harmonic parameters of single phase induction motor drive system is analyzed and verified.

• Journal of KSNVE
• /
• v.9 no.5
• /
• pp.891-898
• /
• 1999

The purpose of Superconducting Magnetic Bearing Flywheel Energy Storage System (SMB-FESS) is to store unused nighttime electricity until it is needed during daytime. An analytical model of the SMB-FESS is necessary to identify the system behavior. At first, we have to model the superconducting magnetic bearing. Modeling the SMB is same as estimating the bearing parameter. The theoretical modal parameter is calculated through the equation of motion and the experimental modal parameter is estimated through the impact testing (modal testing). The bearing parameter is searched by using the non-linear least square method until the theoretical result corresponds to the experimental result. The suggested modeling method is verified by comparing experimental and analytical frequency response function.

• Journal of the Korean Society for Library and Information Science
• /
• v.31 no.1
• /
• pp.125-151
• /
• 1997

The writers have explored developmental strategies for Library and Information Science in Korea which would flexibly cope with changes in the social environment. They have identified two fronts in the struggle to improve the conditions in the present developmental stage of their academic discipline, i.e., self-reliance and 'movement' orientation.

• Journal of Korea Foundry Society
• /
• v.9 no.4
• /
• pp.320-326
• /
• 1989

Titanium-Boron-Aluminium master alloys are used extensively to grain-refine a wide range of aluminium alloys. This experiment was performed by various amounts of AlTi5B1 addition to the technical aluminium alloys, and also by changing cast temperature and hold time of the melts. The macrostructures were shown that with increasing the addition of AlTi5B1 to the melts, the grain became finer. In the case of cast temperature high enough over $900^{\circ}C$, the grain became coarser, but hold time change not affected on the grain refinement. Particles of $TiAl_3$, and $TiB_2$ were found in the grains and grainboundaries. The important role of grain refinement in this experiment were mainly $TiAl_3$, and also $TiB_2$ those have been confirmed in TEM, SEM, EDS, WDX and X-ray diffraction.

• Proceedings of the KIEE Conference
• /
• 2001.04a
• /
• pp.259-262
• /
• 2001

본 연구에서는 과도상태와 정상상태에서 고조파 보상특성이 우수한 순시전력이론을 단상에 적합하게 수정한 후 순시전압강하 보상 기능을 갖는 단상하이브리드형 직렬 능동전력필터의 제어에 적용하였다. 제안된 알고리즘은 전원전압이 순간적으로 왜형 및 강하되더라도 비선형 부하에 인가되는 전압은 항상 일정치를 갖는 정현파로 제어 가능하며 동시에 전원전류의 고조파와 기본파 무효전류도 보상 가능하다. 정상상태와 과도상태에서 전력전자전용 시뮬레이터인 PSIM에 의해 제안된 이론의 타당성을 입증하였다.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.84-86
• /
• 2001

본 연구에서는 플랜트의 계측신호로 부터 특징 패턴 파형들을 감지하고 패턴감지 정보로부터 플랜트의 운전상황 및 고장을 알아내도록 하는 새로운 기법을 제시하고, 이러한 기법의 실현에 필요한 신호처리 기초 연구를 수행하였다. 또한 보령화력 1.2호기 500MW급 드럼형 보일러및 제어 시스템을 대상으로 보일러 플랜트의 dynamics 모델링과 운전 시뮬레이션을 통하여 여러 운전 패턴및 고장 상황을 발생시켜 고장감지 앨고리즘들의 개발 및 시험과정에 적용하였다. 본 연구에서 수행한 보일러 및 보일러 제어계통에 대한 모델링 및 시뮬레이션은 실제 수행한 발전소 시험 데이터와 비교할 때 높은 일치도를 보이는 결과를 보였다.

• Proceedings of the KIEE Conference
• /
• 2003.04a
• /
• pp.292-295
• /
• 2003

Conventional methods in time / frequency domain for evaluating the compensation performance of active power filters are not provided easy solutions. So, the authors have previously proposed 3-D current coordinates which is composed into active component, fundamental reactive component and distorted component of nonlinear loads current. This method has excellent performance, but can not evaluate the characteristics of nonlinear load current whether it is inductive or capacitive. Therefore, To overcome problems mentioned previously, this paper deals with the simple Average power theory and the expanded 3-D current coordinates for evaluating the compensation performance of active power filters. To confirm the validity, active power filters simulator is developed using C-language. From the simulation, results are discuss their utility.

• Journal of the Korea Furniture Society
• /
• v.12 no.1
• /
• pp.57-67
• /
• 2001

This paper considers Wedding Furniture(new furniture that brides prepare for marriage) design in Korea. Social survey research methods were applied to study wedding furniture from 1960 to 1990. A questionnaires were delivered to 766 urban housewives. As to the statistical methods of the study, descriptive analysis for frequencies, and $X^2-test$ were selectively performed using SPSS PC+ program. the findings are as follows; During this period, Wedding Furniture became an essential Honsu(혼수: wedding gift) item People choose as Wedding Furnitures that serve basic functions of furniture and are traditionally symbols of wedding. They were increased both quantity and quality. Typical Wedding Furnitures of the Modern time were Jangrong(장농: wardrobe for storing clothes and bed clothes), dressing table, wardrobe chest, cupboard and bed. Wedding Furniture items have become more various in kind. Criteria for selecting Wedding Furniture were functionality, affordability, fashion, and decorativeness, tradition and symbolic of marriage. but, The symbolic importance of Wedding Furniture as Honsu will be weakened with the introduction of a variety of electronic appliances.

• YAKHAK HOEJI
• /
• v.34 no.3
• /
• pp.171-179
• /
• 1990

The recombinant gamma-interferon (LBD-001) which was produced by yeast as host system was investigated on the pharmacological activities. This gamma-interferon exhibited potent inhibitory effect on adjuvant induced arthritis, but no effect on carrageenin induced paw edema in rats. It did not show any sedative, anticonvulsive, analgesic and hypothermic activities in animals. It also had no influences on isolated tracheal muscle and ileum of guinea pig, isolated uterus and fundus strip of rats, and on blood pressure and respiration in situ experiments of rabbits.