• 제목/요약/키워드: Half Drop

검색결과 87건 처리시간 0.022초

이중 Gate를 갖는 Trench Emitter IGBT의 특성 (The Characteristics of a Dual gate Trench Emitter IGBT)

  • 강영수;정상구
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제49권9호
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    • pp.523-526
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    • 2000
  • A dual gate trench emitter IGBT structure is proposed and studied numerically using the device simulator MEDICI. The on-state forward voltage drop latch-up current density turn-off time and breakdown voltage of the proposed structure are compared with those of the conventional DMOS-IGBT and trench gate IGBT structures. The proposed structure forms an additional channel and increases collector current level resulting in reduction of on -state forward voltage drop. In addition the trench emitter increases latch-up current density by 148% in comparison with that for the conventional DMOS-IGBT and by 83% compared with that for the trench gate IGBT without degradation in breakdown voltage when the half trench gate width(Tgw) and trench emitter depth(Ted) are fixed at $1.5\mum\; and\; 2\mum$, respectively

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하이브리드 제어기법을 이용한 Asymmetrical 하프 브리지 컨버터의 다이오드 스트레스 저감기법 (Diode Stresses Reduction Of Asymmetrical Half-Bridge Converter Using Hybrid Control Scheme)

  • 조창규;이동윤;김경환;현동석
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.221-223
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    • 2003
  • This paper presents a new hybrid control method of asymmetrical/symmetrical half-bridge converter (AHBC/SHBC) with low voltage stress of the diodes. The proposed new control scheme is executed by using feedback of the input voltage and then can decide operation of the converter is divided into two ranges, which are asymmetrical control and symmetrical control, So the proposed control scheme has many advantages such as a low rated voltage of the secondary diodes, and low conduction loss according to the low voltage drop. The proposed control scheme is verified by simulated results.

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낮은 다이오드 스트레스를 갖는 비대칭 하프 브리지 컨버터의 하이브리드 제어기법 (A Hybrid Control Scheme of Asymmetrical Half Bridge Converter with Low Stresses of the Diodes)

  • 조창규;이동윤;박남주;김경환;현동석
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제53권1호
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    • pp.55-62
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    • 2004
  • This paper presents a new hybrid control method of asymmetrical half-bridge converter (AHBC) with low voltage stresses of the diodes. The proposed new control scheme can observe variation of secondary diode voltage stresses by using feedback of the input voltage and then decide the control portions, which are symmetrical control and asymmetrical control. Therefore, the proposed control scheme has many advantages such as a low rated voltage of the secondary diodes and low conduction loss according to the low voltage drop. The principle of the proposed control scheme is explained in detail and its validity is verifiedthrough simulated and experimental results

Asymmetrical 반브리지 컨버터의 이차측 다이오드 전압스트레스저감을 위한 새로운 하이브리드 제어기법 (A new hybrid control scheme for reduction of secondary diode voltage stresses Based on interleaved PFC Asymmetrical Half Bridge Topology)

  • 박남주;이동윤;현동석
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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    • pp.1416-1418
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    • 2005
  • This paper presents a new hybrid control method of asymmetrical half-bridge converter(AHBC) with low voltage stresses of the diodes and interleaved PFC(power factor correction). The proposed new control scheme can observe variation of secondary diodes voltage stresses by variation of duty ratio and then decide the control portions which are asymmetrical control and PFM(Pulse Frequency Modulation). Therefore, the proposed control scheme has many advantages such as a low rated voltage of the secondary diodes, low conduction loss according to the low voltage drop and wide zvs range by load variation. Through simulation results, the validity of the proposed control scheme is demonstrated.

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Modified Trench MOS Barrier Schottky (TMBS) Rectifier

  • Moon Jin-Woo;Choi Yearn-Ik;Chung Sang-Koo
    • KIEE International Transactions on Electrophysics and Applications
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    • 제5C권2호
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    • pp.58-62
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    • 2005
  • A trench MOS barrier Schottky (TMBS) rectifier is proposed which utilizes the upper half of the trench sidewall as an active area. The proposed structure improves the forward voltage drop by 20$\%$ in comparison with the conventional one without degradation in breakdown voltage. An analytical model for the field distribution is given and compared with two-dimensional numerical simulations.

Intracranial Pressure and Experimental Model of Diffuse Brain Injury in Rats

  • Blaha, Martin;Schwab, Juraj;Vajnerova, Olga;Bednar, Michal;Vajner, Ludek;Michal, Tichy
    • Journal of Korean Neurosurgical Society
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    • 제47권1호
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    • pp.7-10
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    • 2010
  • Objective: In this study, we present a simple closed head injury model as a two-stage experiment. The height of the weight drop enables gradation of head trauma severity. Methods: The head injury device consists of three parts and there are three adjustable parameters-weight (100-600 g). height of fall (5-100 cm) and elasticity of the springs. Thirty male Wistar rats underwent monitoring of intracranial pressure with and without induction of the head injury. Results: The weight drop from 45 to 100 cm led to immediate seizure activity and early death of the experimental animals. Severe head injury was induced from 40 cm weight drop. There was 50% mortality and all surviving rats had behavioral deterioration. Intracranial pressure was 9.3${\pm}$3.76 mmHg. Moderate head injury was induced from 35 cm, mortality decreased to 20-40%, only half of the animals showed behavioral pathology and intracranial pressure was 7.6${\pm}$3.54 mmHg. Weight drop from 30 cm caused mild head injury without mortality and neurological deterioration. Intracranial pressure was slightly higher compared to sham group- 5.5${\pm}$0.74 mmHg and 2.9${\pm}$0.81 mmHg respectively. Conclusion: This model is an eligible tool to create graded brain injury with stepwise intracranial pressure elevation.

충격자의 형상 및 재질변화에 따른 펄스형성에 관한 연구 (A study on the impact pulse analysis with various shapes and materials of impactor)

  • 이영신;김동진;강근희;오종수
    • 대한기계학회논문집A
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    • 제22권1호
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    • pp.52-63
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    • 1998
  • The impact programmer for impact test was designed and the impact analysis was conducted. The effects of the material and geometric parameters on the impact force and pulse shape were investigated. The impact characteristics were examined by experimental and finite element method. The impact test was conducted with free drop impact tester. The ABAQUS/Explicit 5.5 version was used for finite element analysis. The geometric parameters of the conical and dome type impact programmer were analyzed. The polyurethane impact programmers were fabricated and tested. The effects of the hardness and thickness of the impact programmer were studied. The peak acceleration and time duration of impact programmer have close correlation with the hardness, impact energy and thickness of the impactor. The experiment was good agreement with analytical predictions. The impact pulse shape generated with polyurethane impact programmer was half sine shape. The maximum impact force was proportional to impact energy. The impact acceleration was decreased with thickness of impact programmer. The maximum impact time duration level was about 2 msec.

입자 및 필터 대전상태에 따른 입자부하조건에서 공기정화 필터의 여과특성 (Influence of Particle and Filter Charge on Filtration Property of Air Filter under Particle Loading)

  • 지성미;손종렬;박현설
    • 한국대기환경학회지
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    • 제28권6호
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    • pp.644-655
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    • 2012
  • As soon as a new air filter is applied to an air purification process, the filter gets loaded with dust particles. Thus, the study on the particle loading characteristics of air filter is very essential in order to understand the real filtration phenomena during filter use. In this study, we investigated the effect of particle and filter charge on the particle loading property of air filter. Charged filter and uncharged filter prepared by discharging the charged filter by isopropyl alcohol were used as test samples, and three types of particle having different charge states were supplied to filters tested. For neutralized particles there was a big difference in areal mass loading rates between charged and uncharged filters due to the very small amount of particle charge, on the other hand the difference was diminished for atomized particle and finally almost vanished for corona charged particles. The pressure drop of filter loaded with corona charged particles was only half of those for neutralized and atomized particles at the same areal mass loading because of the porous structure of particle deposit formed on filter fibers, caused by the space charge effect between particles.

Alternatives to Enhance Flat Slab Ductility

  • Husain, Mohamed;Eisa, Ahmed S.;Roshdy, Ramy
    • International Journal of Concrete Structures and Materials
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    • 제11권1호
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    • pp.161-169
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    • 2017
  • Flat slab systems are vastly used in multi-story buildings because of their savings in story height and construction time, as well as for their flexibility in architectural remodeling. However, they frequently suffer brittle punching-shear failure around columns, especially when subjected to lateral loads. Therefore, seismic codes labeled flat slabs as non-ductile systems. This research goal is investigating some construction alternatives to enhance flat slab ductility and deformability. The alternatives are: adding different types of punching-shear reinforcement, using discreet fibers in concrete mixes, and increasing thickness of slab around columns. The experimental study included preparation and testing of seven half-scale interior slab-column connections up to failure. The first specimen is considered a reference, the second two specimens made of concrete mixes with different volumetric ratios of polymer fibers. Another three specimens reinforced with different types of punching-shear reinforcement, and the last specimen constructed with drop panel of inverted pyramidal shape. It is found that using the inverted pyramid-shape drop panel of specimen, increases the punching-shear capacity, and the initial and the post-cracking stiffnesses. The initial elastic stiffnesses are different for all specimens especially for the slab with closed stirrups where it is experienced the highest initial stiffness compared to the reference slab.

Choked Surge in a Cavitating Turbopump Inducer

  • Watanabe, Toshifumi;Kang, Dong-Hyuk;Cervone, Angelo;Kawata, Yutaka;Tsujimoto, Yoshinobu
    • International Journal of Fluid Machinery and Systems
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    • 제1권1호
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    • pp.64-75
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    • 2008
  • During an experimental investigation on a 3-bladed and a 4-bladed axial inducer, a severe surge instability was observed in a range of cavitation number where the blade passage is choked and the inducer head is decreased from noncavitating value. The surge was stronger for the 4-bladed inducer as compared with a 3-bladed inducer with the same inlet and outlet blade angles. For the 4-bladed inducer, the head decreases suddenly as the cavitation number is decreased. The surge was observed after the sudden drop of head. This head drop was found to be associated with a rapid extension of tip cavity into the blade passage. The cause of surge is attributed to the decrease of the negative slope of the head-flow rate performance curve due to choke. Assuming that the difference between the 3 and 4-bladed inducers is caused by the difference of the blockage effects of the blade, a test was carried out by thickening the blades of the 3-bladed inducer. However, opposite to the expectations, the head drop became smoother and the instability disappeared on the thickened blade inducer. Examination of the pressure distribution on both inducers could not explain the difference. It was pointed out that two-dimensional cavitating flow analyses predict smaller breakdown cavitation number at higher flow rates, if the incidence angle is smaller than half of the blade angle. This causes the positive slope of the performance curve and suggests that the choked surge as observed in the present study might occur in more general cases.