• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2006년도 전력전자학술대회 논문집
• /
• pp.146-148
• /
• 2006

The aim of the paper is to design the PLS(Plasma Lighting System) driving inverter circuit with optimal efficiency. In general, it is known that the PLS driven by a pulse has a higher light-conversion efficiency. There are the Class-E type resonant inverter and the semi-bridge inverter as a circuit which can make a pulse with low duty ratio. In this paper, we analyze the losses of the above two circuits. To verify the loss analysis, the inverter circuit with 220V 380W input consumption is manufactured and tested. Throughout the experimental results, the high efficiency PLS system has confirmed.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.560-560
• /
• 2012

We report a one-step fabrication method of Poly(9,9-dioctylfluorene) (PFO) nanowire array with pronounced ${\beta}$-Phase. We use liquid-bridge-mediated nanotransfer molding (LB-nTM) which is a new direct nano-patterning method based on the direct transfer of various materials from a mold to a substrate via liquid layer. The formation of the ${\beta}$-phase morphology in the resulting PFO nanowire array was evidenced by the presence of an absorption peak at 435nm. With the collection polarizer oriented parallel to the wire long axis, the PL emission was most intense and an emission dichroic ratio, DRE, of 3.7 was determined. The nanowire array have been investigated by scanning electron microscopy (SEM). Also, we simply fabricated structure of device of ITO/PFO nanowire arrays/Al and the electroluminescence spectra were recorded at various applied voltage.

• 대한전기학회논문지
• /
• 제36권1호
• /
• pp.3-8
• /
• 1987

The conventional autosequentially commutated current-fed inverter (ASCI) is widely employed with the induction motor drives for speed control. Howener, this inverter has a limit of high power and high frequency indution motor drives. One of the limitations is to be found in the commutation capacitors in the main circuit of this inverter. A new current-fed gate turn-off thyristor (GTO) inverter is developed. This inverter is composed of the main GTO bridge configuration and the improved energy rebound circuit (ERC)without the commutation capacitor. This inverter works stable at high frequency from light load to heavy one. The improved ERC is used not only to rebound the load reactive power to the dc link, but also to return the power in the load to the ac source. The new GTO inverter circuit and the characteristics of the inverter induction motor drives are explained and analyzed.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2011년도 정기 학술대회
• /
• pp.619-622
• /
• 2011

케이블 정착구 검토를 위해서 사장교 전 체계를 모델링하는 것은 전체모델링 해석시 많은 노력과 시간이 요구되고 해석결과의 분석 또한 어려움이 많다. 따라서 문제가 예상되는 부분만을 국부 상세해석하여 구조적 거동을 정확히 파악하는 것이 필요하다. 케이블 정착부에는 여러 보강재들로 구성되어 있어 국부해석에 어려움이 있다. 따라서 실제와 가능한 한 근접하도록 모델링을 하고 전체 구조물의 거동을 국부 상세모델에 적적히 반영할 수 있도록 경계조건을 설정하는 것이다. 본 논문에서는 부산 지하철 4호선의 아치형 사장교를 국내 범용 구조해석 프로그램인 MIDAS/CIVIL을 이용하여 아치리브와 거더정착구 모델링을 실시하였다. 해석 후 해석의 타당성을 검토하고 정착부의 안전성을 확보할 수 있는지 검토 분석 하고자 한다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.539-544
• /
• 2007

Glass fiber reinforced composite decks have high-strength, light-weight and high durability. The composite decks having vertical snap-fit connections are designed for pedestrian bridges and their structural behaviour are studied. The existing connection method of the composite decks in horizontal direction is replaced by the developed snap-fit connection method in vertical direction. The section shape of the composite decks having the vertical snap-fit connection is designed. The safety of the vertical snap-fit connection is verified by finite element analysis.

• 한국안전학회지
• /
• 제14권1호
• /
• pp.55-65
• /
• 1999

Fuzzy logic fuzzy set theory is recently getting increasing emphasis in process control applications. This paper describes application of fuzzy logic in a speed control system that uses a phase controlled bridge converter and a separately excited dc motor. The fuzzy control is used to linearize the transfer characteristics of the converter in discontinuous conduction mod occurring at light load and high speed. The fuzzy control is then extended to the current and speed control loops replacing the conventional PI control method. The control algorithms have been developed in detail and verified by simulation of a DC motor(DM) drive system. The simulation result indicates the superiority of fuzzy control over the conventional control methods. Fuzzy logic seems to have a lot of promise in the applications of power electronics.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 1995년도 추계학술발표회논문집
• /
• pp.47-52
• /
• 1995

This paper presents a new approach in the design of an electronic ballast for fluorescent lamps in the range of 10∼20W. The central point of the design lies in the equivalent concepts for a lamp and for the inverter part of an electronic ballast. The ballast, which adopts half-bridge inverter topology, is designed to adjust ifself to a predefined range of lamp power output by frequency control using MCU. At first, the circuit parameters were estimated using PSpice simulatio, and then were made varied according to the selection of an optimal frequency for each lamp. A series of experiments using fluorescent lamps of 11W, 15W, and 20W were carried out to verify the proposed design. As a result of the experiments, all the three lamps of different kind were run normally with the same ballast under consideration, And the characteristics on lamp starting and light output were satisfactory compared to existen single-output electronic ballasts.

• Computers and Concrete
• /
• 제11권6호
• /
• pp.493-513
• /
• 2013

Direct displacement-based design (DDBD) represents an innovative philosophy for seismic design of structures. When structural considerations are more critical, DDBD design should be carried on the basis of limiting material strains since structural damage is always strain related. In this case, the outcome of DDBD is strongly influenced by the displacement demand of the structural element for the target limit strains. Experimental studies have shown that anchorage slip may contribute significantly to the total displacement capacity of R/C column elements. However, in the previous studies, anchorage slip effect is either ignored or lumped into flexural deformations by applying the equivalent strain penetration length. In the light of the above, an attempt is made in this paper to include explicitly anchorage slip effect in DDBD of R/C column elements. For this purpose, a new computer program named RCCOLA-DBD is developed for the DDBD of single R/C elements for limiting material strains. By applying this program, more than 300 parametric designs are conducted to investigate the influence of anchorage slip effect as well as of numerous other parameters on the seismic design of R/C members according to this methodology.

• Bulletin of the Korean Chemical Society
• /
• 제24권5호
• /
• pp.569-572
• /
• 2003

The majority of dyes belong to the chromophoric class known as donor-acceptor systems. The essential structural feature of such systems is the presence of one or more electron donating groups conjugated to one or more electron withdrawing groups via an unsaturated bridge. The pyrazolin-5-one system is an effective electron acceptor residue, and can also act as a weak electron donor. In our experiments, the various symmetrical and unsymmetrical H-chromophores were synthesized in the indoxyl, imidazo[1,2-a]pyridin-2-one, pyrazolin-5-one, and pyridin-2,6-dione residues, resulting in cross-conjugated donor-acceptor systems. And the visible light absorption was then associated with the migration of electron density from the donor region of the molecule to the acceptor region. Also, it was useful to prepare related non-cross-conjugated donor acceptor chromophores by combining these residues with other electron donor or acceptor moieties. For convenience such chromophores are referred to as merocyanines.

• Structural Engineering and Mechanics
• /
• 제35권5호
• /
• pp.539-554
• /
• 2010

Light weight superstructure is beneficial for bridges in remote areas and in emergency erection. In such weight sensitive applications, combination of fibre reinforced plastics (FRP) as material and box-girders as a structural system have great scope. This combination offers various options to tailor structure and its elements but this flexibility poses greater challenge in optimum design. In this paper a procedure is derived for a generalised optimum design of FRP box-girder bridges, using genetic algorithms (GA). The formulation of the optimum design problem in the form of objective function and constraints is presented. Size, configuration and topology optimization are done simultaneously. A few optimum design studies are carried out to check the performance of the developed procedure and to get trends in the optimum design which will be helpful to the new designers.