• 한국전기전자재료학회논문지
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• 제23권9호
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• pp.667-670
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• 2010

In this paper, a high voltage current sensing circuit for boost converter is designed and verified by Cadence SPECTRE simulations. The current mirror pair, power and sensing metal-oxide semiconductor field effect transistors (MOSFETs) with size ratio of K, is used in our on-chip current sensing circuit. Very low drain voltages of the current mirror pair should be matched to give accurate current sensing, so a folded-cascode opamp with a PMOS input pair is used in our design. A high voltage high side lateral-diffused MOS transistor (LDMOST) switch is used between the current sensing circuit and power MOSFET to protect the current sensing circuit from the high output voltage. Simulation results using 0.35 ${\mu}m$ BCD process show that current sensing is accurate and the pulse frequency modulation (PFM) boost converter using the proposed current sensing circuit satisfies with the specifications.

• 수산해양기술연구
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• 제22권4호
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• pp.32-40
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• 1986

A model experiment of purse seine by the circulating water tank was carried out on the changes of net shape and the tension of purseline under operation in two layer current. In the circular tank, the two layer current was made by cutting off the current of upper layer and producing the bottom current by the equipment shown in Fig. 1. The model experiment of purse sein was made on a reduced scale 1 :400, and the experiment was carried out according to the Tauti's model law. When the bottom current of O. 5 knot flows to lower part of three-eighths of net, following results are derived. The depth of sinkerline reached only about 80% of that of no current set. The horizontal shift of sinker line caused by the bottom current is maximized in tight set. The enclosed area by the floatIine immediately after the completion of set net is 61. 5% in tight set, 50. 0 % in loose set and 54. 1 % in lateral set of those in the case of no current. In the first half period of pursing, the tension of the purseline is enhenced by the bottom current and the pattern of increasing is irregular in the tension curves.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제29권4호
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• pp.340-352
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• 2007

In this systematic review on bone reduction procedures for the correction of the prominent mandibular angle, we collected and sorted the methods. The strength and weakness, indication, complication, and final esthetic result of each method were evaluated. After searching and filtering the literatures on the base of inclusion criteria, 9 eligible case series studies were included in this study. There were 3 types of curved ostectomies and 4 types of lateral cortical ostectomies. Surgical procedures for curved ostectomies were divided into 2 types. One was single curved ostectomy and the other was multistaged curved ostectomy. Lateral cortical ostectomies reported were all similar to sagittal split ramus osteotomy. The complications reported in the included studies were scarce, but curved ostectomies may be able to induce many complications. The prominent mandibular angle must be analyzed in the lateral dimension and frontal dimension, and curved ostectomy can reduce the mandibular angle laterally while lateral cortical ostectomy can reduce the bigonial distance frontally. Because curved ostectomies can induce complications and unnaturally large mandibular angle while can not reduce bigonial distance efficiently, the current trend for the angle reduction procedure is lateral cortical ostectomies.

• 한국지반공학회논문집
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• 제16권4호
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• pp.43-50
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• 2000

본 논문에서는 도심지 깊은 굴축현장에서 수집한 계측자료를 토대로 분석한 흙막이벽체의 거동에 관한 내용을 다루었다. 총 57개 현장에 시공된 H-pile+흙막이판 벽체와 현장타설 주열식 말뚝 벽체, 그리고 지하연속벽체 등 다양한 종류의 흙막이 벽체를 고려하였으며, 굴착으로 인한 벽체의 거동 및 겉보기토압을 집중적으로 분석하였다. 수집된 계측자료를 토대로 벽체 및 지지구조의 형식 등 흙막이벽체의 다양한 구성요소가 벽체의 거동 및 겉보기 토압에 미치는 영향을 분석.고찰하였으며, 그 결과를 현재 적용하고 있는 설계/해석법과 비교하는 한편 다양한 차트의 형식으로 제시하였다. 또한 계측자료를 토대로 흙막이벽체의 최대수평변위를 평가하는 경험식을 제안하였다.

• 한국지진공학회논문집
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• 제13권3호
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• pp.51-65
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• 2009

콘크리트 교량의 합리적인 내진설계는 지진이 발생할 때 연성파괴메커니즘이 유도될 수 있도록 적절하게 교각 연성도를 확보하는 것이다. 현행 기준에서는 이를 위해 휨모멘트의 설계지진력을 산정할 때 응답수정계수를 도입하고 있으며, 연성도 확보를 위한 횡방향철근량을 규정하고 있다. 그러나, 이러한 내진규정은 일반적으로 단면이 크게 설계되는 우리나라에서는 횡방향철근이 과다하게 산정되는 비합리적이었다. 이를 개선하기 위해 소요연성도에 기반한 새로운 내진설계법이 제안되었으나 거동특성과 횡방향철근의 유효구속력이 다른 중공단면에 적용하기 위해서는 향후 많은 검증과 보완이 필요하다. 이에 본 연구에서는 축방향철근의 겹침이음과 횡방향철근량을 변수로 한 중공단면기둥을 제작하여 준정적 재하실험을 수행하였으며 다양하게 내진거동특성을 분석하고 내진성능을 확인하였다. 본 연구 결과는 향후 중공단면교각의 연성도(성능)기반 내진설계를 위한 기초자료로 제공될 수 있다.

• 한국강구조학회 논문집
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• 제18권2호
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• pp.191-201
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• 2006

본 연구에서는 비지지길이 양단에 계단식 단면 변화를 가지는 보에 대해 횡-비틀림 좌굴강도를 합리적으로 산정하기 위 한 새로운 모멘트 구배 수정계수를 개발, 제안하였다. 제안된 식은 건물과 교량에 사용된 보의 양단에 개별 지지만 존재하는 경우와, 슬래브 등이 타설되어 상부플랜지에 연속적인 횡방향 지지가 존재하는 경우로 구분되어 연구되었다. 새로운 모멘트 구배 수정계수식을 개발하기 위하여 유한요소해석 프로그램이 활용되었으며, 제안식은 기존에 발표된 식들과 비교 분석되었다. 구조물에 발생가능한 대부분의 하중조건이 본 연구에 고려되었으나, 본 논문에서는 하나의 집중하중과 등분포하중이 작용하는 경우를 중점으로 기술되었다. 본 연구에서는 비지지길이와 보작용시 적용 가능하도록 식이 개발 제안되었다. 본 논문을 통해 제안된 새로운 모멘트 구배 수정계수식들은 건물과 교량의 설계 및 유지관리 기술자들이 간편하고 경제적인 설계를 유도하는 데 크게 기여할 것이다.

• Steel and Composite Structures
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• 제30권5호
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• pp.483-492
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• 2019

In the current study, the influence of the initial lateral (sweep) shape and the cross-sectional twist imperfection on the lateral torsional buckling (LTB) response of doubly-symmetric steel I-beams was investigated. The material imperfection (residual stress) was not considered. For this objective, standard European IPN 300 beam with different unbraced span was numerically analyzed for three imperfection cases: (i) no sweep and no twist (perfect); (ii) three different shapes of global sweep (half-sine, full-sine and full-parabola between the end supports); and (iii) the combination of three different sweeps with initial sinusoidal twist along the beam. The first comparison was done between the results of numerical analyses (FEM) and both a theoretical solution and the code lateral torsional buckling formulations (EC3 and AISC-LRFD). These results with no imperfection effects were then separately compared with three different shapes of global sweep and the presence of initial twist in these sweep shapes. Besides, the effects of the shapes of initial global sweep and the inclusion of sinusoidal twist on the critical buckling load of the beams were investigated to unveil which parameter was considerably effective on LTB response. The most compatible outcomes for the perfect beams was obtained from the AISC-LRFD formulation; however, the EC-3 formulation estimated the $P_{cr}$ load conservatively. The high difference from the EC-3 formulation was predicted to directly originate from the initial imperfection reduction factor and high safety factor in its formulation. Due to no consideration of geometric imperfection in the AISC-LFRD code solution and the theoretical formulation, the need to develop a practical imperfection reduction factor for AISC-LRFD and theoretical formulation was underlined. Initial imperfections were obtained to be more influential on the buckling load, as the unbraced length of a beam approached to the elastic limit unbraced length ($L_r$). Mode-compatible initial imperfection shapes should be taken into account in the design and analysis stages of the I-beam to properly estimate the geometric imperfection influence on the $P_{cr}$ load. Sweep and sweep-twist imperfections led to 10% and 15% decrease in the $P_{cr}$ load, respectively, thus; well-estimated sweep and twist imperfections should considered in the LTB of doubly-symmetric steel I-beams.

• 전기전자학회논문지
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• 제15권1호
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• pp.37-42
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• 2011

본 논문에서는 0.35 um BCD 공정을 통한 고내압 BCD 소자와 새로운 구조의 BCD 소자를 제작하여 전기적 특성을 분석하였다. 20 V급 BJT 소자, 30/60 V급 HV-CMOS, 40/60 V급 LDMOS 소자의 전기적 특성을 분석하고, 동일 공정을 통해 높은 전류 이득을 갖는 수직/수평형 NPN BJT와 고내압 특성의 LIGBT 소자를 제안하였다. 제안된 수직/수평형 NPN BJT의 항복전압은 15 V, 전류이득은 100으로 측정되었으며, 고내압 특성의 LIGBT의 항복전압은 195 V, 문턱전압은 1.5 V, Vce,sat은 1.65 V로 측정 되었다.

• 센서학회지
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• 제9권3호
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• pp.182-189
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• 2000

미소 공간 내의 진공도를 측정하기 위하여 마이크로 진공 센서를 제작하였다. 동작 원리로서 전계 방출 전류가 진공도에 의존한다는 점을 이용하였고, 이를 위해 측면형 실리콘 전계 방출 소자를 제작하였다. 음극과 게이트, 그리고 양극을 분리하기 위하여 표면 미세가공을 이용하였으며, 제작된 소자는 $10^{-5}{\sim}10^{-8}\;Torr$ 범위의 진공도에서 $1.20{\sim}2.42\;{\mu}A$ 범위의 방출 전류 변화를 보였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.267-270
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• 2001

A new small scaling Lateral Trench Insulated Gate Bipolar Transistor (SSLTIGBT) was proposed to improve the characteristics of the device. The entire electrode of the LTIGBT was replaced with a trench-type electrode. The LTIGBT was designed so that the width of device was no more than 10$\mu\textrm{m}$. The latch-up current densities were improved by 4.5 and 7.6 times, respectively, compared to those of the same sifted conventional LTIGBT and the conventional LTIGBT which has the width of 17$\mu\textrm{m}$. The enhanced latch-up capability of the SSLTIGBT was obtained due to the fact that the hole current in the device reaches the cathode via the p+ cathode layer underneath the n+ cathode layer, directly. The forward blocking voltage of the SSLTIGBT was 125 V. At the same size, those of the conventional LTIGBT and the conventional LTIGBT with the width of 17$\mu\textrm{m}$ were 65 V and 105 V, respectively. Because the proposed device was constructed of trench-type electrodes, the electric field in the device were crowded to trench oxide. Thus, the punch through breakdown of LTEIGBT occurred late.