• Proceeding of KASS Symposium
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• 2006.05a
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• pp.49-57
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• 2006

Performance based seismic design is a very efficient method in evaluating the seismic capacity of building. In this study, the method estimating the performance point of the spatial structures based on capacity spectrum method(CSM) is proposed. And for efficient evaluation for the performance point of the spatial structures, the algorithm to convert spatial structural system to ESDOF system is proposed. Its efficiency is confirmed by comparing with time history analysis of full model. And dynamic behaviors of spatial structures are examined by using this method. At last, evaluation of structural performance according to variation of stiffness after plastic deformation is carried out.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.26-33
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• 2004

In this study, a boundary-layer bleeding and a two-staged fuel injection were applied to a scramjet engine for suppressing unstart transition and improving the thrust performance under Mach 6 flight conditions. With the boundary-layer bleeding, the engine could operate without unstart transition around at the fuel equivalence ratio of unity ($\Phi$ = 1). The thrust increment from the no fuel condition (dF) increased to 2460 N, which was about 1.4 times as large as that of the case without the bleeding and maximum in our Mach 6 tests. It was confirmed that the boundary-layer bleeding suppressed the separation during the engine operation. The two-staged fuel injection was less effective for improving the thrust performance com-pared with the single-staged one with the bleeding at Mach 6.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.39-42
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• 2004

Ceramic membranes have attracted a great attention because they have excellent resistance to most organic solvents and can be used over a wide temperature range. Especially, titania (titanium oxide, TiO$_2$) shows excellent chemical resistance and can be used both acidic and alkali solutions, and therefore, titania is one of the most promising materials for the preparation of porous membranes; titania membranes having pore sizes in the range of nanofiltration (NF) to ultrafiltration (UF) membrane have been prepared by the sol-gel process (Tsuru 2001).(omitted)

• Proceedings of the KIEE Conference
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• summer
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• pp.1199-1201
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• 2004

When The temperature of the joining of SCR rises major changes of characteristics are increase of leakage current, decrease of break-down voltage, and increase of turn off time. Because these changes promote the inferiority of SCR it(SCR) will get out of control and its life time will be shortened and finally it will be destroyed. In this paper, we will measure the changes of the characteristics in accordance with a rise in temperature. On the basis of the result we will find out the appropriate time to change SCR and we will use the result for the maintenance of SCR and increase of reliability of SCR.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1482-1488
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• 2014

The reliability evaluation of the electrical distribution networks (EDN) requires sufficient consideration of the effects of planned outages. The planned outages of the EDN can be divided, by outage models and their effects on the reliability into two major categories: by equipment and by feeder. After studying the characteristics of different categories of planned outages, this paper expands the classification of load points by outage time from 4 types to 7 types and defines corresponding reliability parameters for the different types. By using the section algorithm, this paper proposes a reliability evaluation technique of EDN considering equipment random failures and two categories of planned outages. The proposed technique has been applied to the RBTS-BUS6 test system and some practical EDNs in China. The study results demonstrate that the proposed technique is of higher practical value and can be used for evaluating the reliability performance of EDN more efficiently considering the planned outages.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.683-686
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• 2014

오늘날 기업들의 경쟁력 강화를 위해 활발하게 IT 프로젝트가 수행되고 있다. 특히 복잡한 업무 환경의 금융권에서는 차세대금융시스템구축 프로젝트가 진행되고 있다. 하지만 차세대금융 PMO에서 선행연구자들이 정의한 PMO 의 주요기능이 얼마나 수행 되고 있는지 현 차세대 금융 PMO 상황에 대해서는 연구되지 않았다. 이에 본 논문에서는 프로젝트, 프로젝트관리, PMO 의 정의와 주요기능에 대해 살펴보고, 3 사의 차세대 금융 PMO 사례를 통해 일반 PMO 의 주요기능과 차세대금융 PMO 의 기능을 비교해보고, 그 결과 중점적으로 준수되고 있는 기능과 준수되고 있지 않은 기능을 판별해 차세대 금융 PMO 이 보완되어야 할 점을 제시 할 수 있었다. 향후 연구에서는 다양한 차세대 금융 PMO 사례의 기능비교를 통해 차세대금융 PMO 의 성공적인 운영방안을 제시 해 볼 수 있을 것이다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.520-521
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• 2014

본 논문에서는 3-Level NPC 인버터에서의 새로운 PWM 기법에 대해서 제안하였다. 3-Level NPC 인버터에서 각 상하의 스위치는 데드타임으로 인해 전압과 전류의 왜곡과 직류링크단의 전압 불균형의 원인이 된다. 제안하는 기법은 지령전압과 전류의 위상에 따라 출력전압과 전류의 왜곡성분을 감소시키며 상보동작을 하지 않는 PWM 기법을 이론적으로 검증하였고, 시뮬레이션을 통해 증명하였다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.59-60
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• 2015

본 논문에서는 3-Level NPC(Neutral Point Clamped) 인버터에서 ZDPWM(Zero Dead Time Pulse Width Modulation) 기법에 대해서 제안한다. 3-Level NPC 인버터에서 기존 PWM 기법은 각 스위치는 서로 상보적인 동작을 수행하고, 반도체 스위칭 소자 특성상 Rise Time과 Fall Time의 시간차이로 인하여 단락사고를 방지하기 위해 스위칭 신호의 Rising Edge에 데드타임을 인가하여 단락을 방지한다. 그러나 이러한 데드타임은 지령 스위칭 신호와 실제 스위칭 신호의 오차로 인하여 출력 전압 및 전류에 왜곡이 발생하고, 이러한 왜곡으로 인하여 시스템의 오작동 및 직류링크단 전압의 불평형의 원인이 된다. 제안하는 PWM기법은 지령전압과 출력전류의 위상에 따라 영역을 나눈 후 전류의 방향에 따라 옵셋 전압을 생성하여 새로운 지령전압을 만들어 각 스위치에 스위칭 신호를 인가한다. 제안한 기법에 타당성을 증명하기 위해 시뮬레이션을 통해 검증하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.275-282
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• 2008

This paper presents numerical investigation of multi-phase flow in solid rocket motor nozzle and effect of multi-phases on the performance prediction of the Solid Rocket Motor. Aluminized propellants are frequently used in solid rocket motors to increase specific impulse. An Eulerian-Lagrangian description has been used to analyze the motion of the micrometer sized and discrete phase that consist of the larger particulates present in the Solid Rocket Motor. Uniform particles diameters and Rosin-Rammler diameter distribution method has been used for the simulation of different burning of aluminum droplets generating aluminum oxide smokes. Roe-FDS scheme has been used to simulate the effects of the multi-phase flow. The results obtained show the sensitivity of this distribution to the nozzle flow dynamics, primarily at the nozzle inlet and exit. The analysis also provides effect of two phases on performance prediction of Solid Rocket Motor.

• Communications for Statistical Applications and Methods
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• v.28 no.6
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• pp.673-679
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• 2021

The moment calculation in a truncated multivariate normal distribution is a long-standing problem in statistical computation. Recently, Kan and Robotti (2017) developed an algorithm able to calculate all orders of moment under different types of truncation. This result was implemented in an R package MomTrunc by Galarza et al. (2021); however, it is difficult to use the package in practical statistical problems because the computational burden increases exponentially as the order of the moment or the dimension of the random vector increases. Meanwhile, Lee (2021) presented an efficient numerical method in both accuracy and computational burden using Gauss-Hermit quadrature. This article introduces trunmnt implementation of Lee's work as an R package. The Package is believed to be useful for moment calculations in most practical statistical problems.