HID 램프용 디지털제어 전자식 안정기에 관한 연구

김영동,강원찬,김남오,김형곤,김병철 조선대학교 에너지.자원신기술연구소 2004 에너지·자원신기술연구소 논문지 Vol.26 No.1

In this paper, digitally controlled electronic ballast for the HID lamps driven by proposed frequency conversion method is described. This electronic ballast consists of a buck converter, a low frequency square wave full bridge inverter, a high voltage pulse generator for the lamp ignition, an over current protection circuit and an 8-bit microcontroller. The fuzzy logic digital control operation is carried out by the 8-bit microcontroller. In spite of the limited control bandwidth caused by low operation speed of the 8-bit microcontroller, the good control performance for the constant lamp current in the warm-up period is obtained using the proposed frequency conversion driving method. The HID lamp is controlled in a constant current mode during the lighting warm up process and is controlled in a constant power mode during lighting steady state. A controlled variable power mode is used to extend the lamp lifetime.

목형의 엔드 밀링시 절삭조건에 따른 가공 특성에 관한 연구

김성일,김종택,김민호,신형곤,김태영 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

The cutting tests of wood patterns are carried out using CNC milling machine. The cutting forces and surface characteristics of machined surface are investigated at various cutting conditions such as spindle speed, feed speed, cutting direction of wood pattern and wood material. In the CNC end-milling, the surface roughness increases as feed speed increases and decreases as spindle speed increases. However, the cutting force and surface roughness are different along the cutting direction and material of wood pattern.

부산지역 대학신문들의 편집디자인에 대한 분석

김형곤 동명정보대학교 1999 東明情報大學校論文集 Vol.2 No.-

The purpose of this study is to analyze the design of university newspapers which are publishing in Pusan. For several years, recently, domestic newspapers have been changing their features in a whole. It is rapidly progressing to be changed with horizontal writing system from vertical writing system. To this reason, it is main purpose for this thesis to pursue an improvement for the outward appearance of Korean newspaper, especially university newspaper in Pusan, and to compare the newspapers each other. As the result of this study, visual component factors of university newspaper in Pusan, on the whole, are not appropriate to the general principle of newspaper design. And I cannot find out that there is specific difference among the newspapers for the visual component factors.

사진의 사회적 기능에 대한 일고찰

김형곤 동명정보대학교 2002 저널 언론정보 Vol.1 No.-

기니픽에서 Magnesium의 혈관 이완과 혈압 하강 효과

김정곤,강형섭,김진상 한국수의공중보건학회 2003 예방수의학회지 Vol.27 No.2

The present study evaluated the effects of various agents on magnesium sulfate (Mg^(2+))-induced relaxation in aorta and blood pressure lowering in anesthetized guinea pigs. Mg^(2+) inhibited phenylephrine (PE)- or 40 mM KC1-induced sustained contraction of endothelium-intact (+E) guinea pig aortic rings in concentration-dependent manner. In preparations preconstricted with PE or KC1, Mg^(2+)-induced concentration-dependent relaxations. In preparations preconstricted with PE or KCl, Mg^(2+)-induced relaxations were not affected by the removal of endothelium (-E) and by the pretreatment of aortic rings with NO synthase (NOS) inhibitors (L-NAME and LNNA), guanylate cyclase inhibitors (methylene blue and ODQ, adenylate cyclase inhibitor (MDL), K^(+) channel blockers (glibenclamide and tetrabutylammonium), nifedipine or ryanodine. However, Mg^(2+)-induced relaxations were inhibited by Na^(+)-Mg^(2+) exchange inhibitor (imipramine) or removal (or attenuation) of extracellular Ca^(2+) in +E aortic rings. PE-induced contraction was not inhibited by nifedipine. In addition, Mg^(2+)-induced relaxations were inhibited by phospholipase C inhibitor (NCDC) or inositol monophosphatase inhibitor (lithium), but not by protein kinase C inhibitor (staurosporine). In vi패 infusion of Mg^(2+), directly into the femoral veins of guinea pigs, elicited sustained decrease in arterial blood pressure. The Mg^(2+)-lowered blood pressure was attenuated by intravenous administration of imipramine or lithium, but not by methylene blue, indomethacin, tetrabutylammonium nifedipine, LNNA, L-NAME or saponin (as an endothelium removal agent). These results suggest that endothelium independent vasorelaxant effect of Mg^(2+) on aortic ring appear to play important roles on the antihypertensive action in guinea pig, most likely via the inhibitory action of Mg^(2+) on the intracellular C^(2+) involve in PLC-IP pathway and influx (through the Na^(+)-Mg^(2+) exchanger) into the cell in guinea pig aorta.

마이크로-매크로 셀룰라 시스템을 위한 계층선정 기법분석

김장섭,이상헌,정우곤,최형진 成均館大學校 科學技術硏究所 1998 論文集 Vol.49 No.1

A control scheme to select the appropriate layer between macro- and microcell hierarchical structure is considered. With the assumption that the each mobile speed is known to the system. the algorithm determines the optimal velocity threshold by which the cell section performed. The optimal criterion is to minimize the Grade of Service(GOS), a service criterion in cellular telephone systems. Mobile station with faster speed relative to the determined optimal speed threshold are assigned to a macrocell, while slower moving terminals are assigned to the smaller cells, i,e.. microcells. For the evaluation purpose for the proposed scheme, two different evaluation perspectives are compared and the algorithm proves to work

伽耶式木槨墓의 一考察 : 昌原 道溪洞의 例

金亨坤 동의대학교 인문과학연구소 2000 인간과 문화 연구 Vol.5 No.-

2차원 해석을 이용한 지하복합구조물 설계의 문제점 : 지하철 정거장을 중심으로

김형곤,조현영,정진환 釜山大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.52 No.-

본 연구에서는, 3차원 지하구조물이 2차원 뼈대조구조해석에 의해서 설계될 때의 문제점 들, 즉 갑작스런 단면의 변화, 개구부, 길이방향으로의 지반상태의 변화들이 검토 되어진다. 구조물들 3차원 해석에서 실제구조물과 가능한한 가장 근사하게 FEM에 의해 이상화되어진다. 본 연구로부터, 다음과 같은 두가지 결론을 내릴수 있다. 첫째, 개구부가 존재하는 곳에서는 보다 정확한 휨 모멘트분포를 얻기 위해 3차원이나 판이론에 의한 세부적인 해석이 수행되어져야 한다. 둘째, 건조수축, 수화열 그리고 힘의 분배에 대한 길이방향 보강을 결정하기 위해서는 더 세심한 검토가 필요하다. In this study, the problems when 3-D underground structures were designed by using 2-D plane frame structure analyses, such as sudden changes of sections, openings, and the variations of the ground conditions in the longitudinal directions, were investigated. The structures were idealized by FEM as close as possible to the real structures in 3-D. From this study, the authors conclude following two results. First, 3-D or detailed analysis with plate theory where openings exist must be carried out to obtain more accurate bending moment distribution. Second, a more refined investigation is needed to determine the longitudinal reinforcement due to shrinkage, the heat of hydration and the distribution of forces.

미국 '적색공포'에 대한 일사례 연구 : 시애틀 총파업(1919.2)을 중심으로

金亨坤 中央大學校 史學硏究會 1995 중앙사론 Vol.8 No.-

메탈핼라이드 램프용 저주파 구형파 구동의 퍼지제어 전자식 안정기

金柄哲,金亨坤,全仁柱,宋燦日 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.2

A low frequency square wave driven electronic ballast for metal halide (MH) lamps is developed. The lamp current/wattage is controlled by fuzzy logic controller based on the low cost 8-bit microcontroller. This electronic ballast consists of a buck converter, a low frequency square wave full bridge inverter, a high voltage burst pulse generator using IGBT for the MH lamp ignition, an over-current protection circuit and an 8-bit microcontroller circuit. The ballast system is operated on the constant current mode during the MH lamp start-up process and the system is operated on the constant power mode during steady state. Experimental results show that the fuzzy logic control operation is carried .out successfully by the 8-bit microcontroller PIC16F877. In this electronic ballast system, in spite of the limited control bandwidth caused by low operating speed of the %bit microcontroller, the good performance in the constant lamp current characteristic is obtained. Acoustic resonance of the MH lamps can be effectively avoided because the instantaneous lamp power is fully constant due to the low frequency square wave drive.