• Journal of the Korean Society of Propulsion Engineers
• /
• v.15 no.4
• /
• pp.94-102
• /
• 2011

Sub-system requirements of a pressure-fed hot-firing test facility for performance assessment of a Liquid Rocket Engine(LRE) thrust chamber using Liquid oxygen and kerosene were described. These requirements were based on the experience of construction and operation of the ground hot-firing test facility which was used for the development of the KSR-III and a 30 tonf-class LRE thrust chamber. So it is expected that this paper is used as a basic material and an itemized previous review statement for the design and construction of a large hot-firing test facility.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.63-71
• /
• 2010

Sub-system requirements of a pressure-fed hot-firing test facility for performance assessment of a Liquid Rocket Engine(LRE) thrust chamber using Liquid oxygen and kerosene were described. These requirements were based on the experience of construction and operation of the ground hot-firing test facility which was used for the development of the KSR-III and a 30 $ton_f$-class LRE thrust chamber. So it is expected that this paper is used as a basic material and an itemized previous review statement for the design and construction of a large hot-firing test facility.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.3
• /
• pp.23-30
• /
• 1985

When a digital filter implementation is based on a difference equation, the frequency characteristics cannot be obtained by direct computation, but be obtained by experiment or analogized by Z-transform. In this paper, the method to compute the frequency magnitude response of the function expressed in a difference equation is derived from PARSEVAL's relation. To verify the validity of this new method two types of digital filters are implemented. Both filters' characteristics are measured and their values are compared with the value obtained by a Z-transform and with the value by a difference equation. The result shows that the measured values and the values obtained by the difference equaton are more closer than the values by a Z-transform. And the difference-equaton-based filters' showed sharper roll off characteristics than the Z-transform-based filters. Therefore when a digital filter implementation is based on a difference equation, the characteristics computation by a difference equation predicts better practical results than based on Z-transform.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.2 s.40
• /
• pp.169-175
• /
• 2006

In this paper we propose a method of reconstruction of cylindrical panorama using simplified projective transform from the panning image on the fixed camera. For the practical construction of cylindrical panorama we consider the rotation of the camera on the Y-axis only, even though considering the rotation components on all of the X,Y,Z axis on three-dimensional space for projective transform between general panoramas. The restriction mentioned above simplifies projective transform with existing 8 degrees of freedom into the one with 4 degrees of freedom. In the results, overall computation for projective transform can be decreased to the great extents in quantify, because the number of corresponding points required for inducing the transforming formula is gone down by half. Proposed algorithm from the simulation carried out in this paper shows similar performance and decreased computational quantity compared with existing algorithm. Also, it shows the construction of cylindrical panorama using simplified projective transform.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.348-349
• /
• 2011

전력계통해석 중 전력조류계산과 안정도 해석에서 부하모델이 필요하다. 부하모델을 만드는 방법 중 미시적 방법에 의한 부하모델 방법은 몇 개의 부하군으로 분류하고, 전압, 주파수 변화에 따른 특성 실험에 의해 부하군의 개별부하 모델을 구축하고 각 부하군이 시간별 구성 비율을 이용하면 합성된 부하모델을 얻을 수 있다. 이 ��, 부하구성비 추정이 필요로 하게 된다. 본 논문에서는 스마트그리드 환경에서 구성될 새로운 주택모습과 그 안에 구성될 부하기기를 추론하고, 10년전에 이루어 졌던 부하모델 방법의 부하구성비와 스마트 그리스환경에서 구성될 새로운 주택의 부하구성비를 비교함으로써 부하모델을 10년 주기로 새로 예측해야 할 이유에 대해 서술하도록 한다.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.35 no.2
• /
• pp.216-224
• /
• 2008

The purpose of this study was to evaluate the effectiveness of fissurotomy and double application time of acidic primer of self-etching adhesive system of acid treatment on enamel surfaces for prevention of microleakage of pit and fissure sealants. The microleakage of pit and fissure sealants was evaluated by measuring the penetration depth of methylene blue solution. Specimens were divided by 4 groups according to the method of treatment. Group I: 35% phosphoric acid etching, 20 seconds. Group II: Priming with self-etching primer, 20 seconds. Group III: Priming with self-etching primer, 40 seconds. Group IV: Priming with self-etching primer, 20 seconds, after fissurotomy. The etched pattern produced on enamel was observed using a scanning electron microscope. Obtained data were analysed statistically using Kruscal-Wallis test followed by Mann-Whitney test for comparison of groups. The results are as follows: 1. Microleakage scores of group IV priming with self-etching primer 20 seconds after fissurotomy was the lowest. 2. Microleakage scores between group II and group III were not shown significant difference. 3. Enamel for 20 seconds etching with 35% phosphoric acid was observed the most effective etching pattern. And the etching pattern on the fissure enamel with self-etching adhesive 20 seconds after fissurotomy was more prominent than group II, III only using self-etching primer.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2002.11a
• /
• pp.271-274
• /
• 2002

본 논문에서는 Class E zero-current-switching (ZCS) 인버터를 이용하여 단일 스위치로서 램프를 점등하는 타여자 방식의 전자식 안정기를 제안하였다. 이론을 통해 각 파라미터를 계산하고, PSpice 시뮬레이션을 통하여 안정상태의 램프출력을 예측하였다. 또한, MOSFET의 전압 스트레스를 고려한 스너버 회로를 구성하여 스위칭 서지전압의 발생을 억제하였으며, 실제 전자식 안정기를 제작하여 전기적 특성을 살펴보았다.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.743-745
• /
• 2002

본 논문에서는 최근 개발된 250W 고압나트륨 램프용 전자식 안정기의 구성과 동작특성을 다양한 실험을 통해 기존 자기식 안정기와 비교하였다. 이를 통해 전자식 안정기의 향상된 광효율 특성과 개선된 역률, THD 등과 같은 전기적 특성을 확인할 수 있었다.

• The Optical Journal
• /
• s.140
• /
• pp.34-35
• /
• 2012

대한민국 사진영상장비 대표기업 세기 P&C(주)(이봉훈 대표, www.saeki.co.kr)는 지난 6월 1일 서울 충무로 신사옥 오픈식을 개최했다. 세기P&C(주)는 지난 4월, 기존 종로구 와룡동에서 중구 충무로3가 소재의 신사옥으로 이전한 후, 동양 최대 규모의 멀티 브랜드숍을 표방한 '세기 브랜드숍'을 준비, 매장 구성을 완성하여 신사옥을 오픈했다. 이날 충무로 신사옥 오픈식에선 세기P&C(주) 이봉훈 대표의 자서전 출판기념회도 함께 진행되었다.

• Computational Structural Engineering
• /
• v.11 no.4
• /
• pp.267-274
• /
• 1998

본 연구에서는 기지개와 미시구멍으로 구성된 복합재료에 입자보강 복합재료의 등가 재료상수 예측기법인 평균장 근사이론과 등가원리를 적용하여 위상 최적화에 필요한 등가 재료상수와 설계변수와의 상관관계식을 유도하였다. 또한, 유도된 관계식에 중간값을 갖는 설계변수의 수를 줄이기 위하여 벌칙인자를 도입하였다. 그리고 본 연구의 타당성을 검증하기 위하여 벌칙인자가 도입된 위상 최적화문제를 순차이차계획법인 PLBA 알고리즘을 이용하여 해석하였다.