• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.914-919
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• 1998

A Capacitor Commutated Converter (CCC) has less difficulty of commutation failure in comparison to the conventional line commutated converter. This paper proposes the Ar1R control of the CCC in the inverter operation, which deserves as the Ar1R of the conventional converter. The CCC can be operated in high power factor area by using the proposing Ar1R control. The voltage stability at an AC bus connected the CCC inverter is investigated and estimated its ability of preventing the AC voltage collapse. To estimate the voltage stability, this paper developed the simplified converter mathematical model and led the VSF index. The results shows that the AC voltage stability is guaranteed and enables the interconnection to an weak AC system, when compensation factor of the compensation capacitor is higher than 200%.

• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.141-145
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• 2004

FACTS devices, such as the Thyristor Controlled Series Compensator (TCSC) and Static Var Compensators (SVC), can help increase system load margin to improve static voltage stability. In power systems, because of the high cost and the effect value, the optimal placement for FACTS devices must be determined. This paper investigates the use of the series device (SVC) and the parallel device (TCSC) from the point of load margin to increase voltage stability. It considers the sensitivity of load margin to the line reactance and eigenvector of the collapse. The study has been carried out on the IEEE 14 Bus Test System to verify the validity and efficiency of the method. It reveals that incorporation of FACTS devices significantly enhance load margin as well as system stability.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.50-57
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• 1995

Cylindrical space frame which have a mechanic property, a functional property, a aesthetic prioerty and so on, occupies one part of sin structures and after this, the using parts will be extended. But because this structure is made of network by combination of line elements there are many nodes the structural the structural behavior is very complicated and there can be a overall collapse of structure by buckling phenomenon if the external force reaches a limitation. In design for this structure, we must determinate layer by considering above mentioned property first of all. Therefore this study aimed at the comparison and the investigation of mechanical characteristics of single-layer and double-layer cylindrical space frame on views of behavior and buckling by use of rise ratio.

• Journal of the Korea Safety Management & Science
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• v.9 no.1
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• pp.51-63
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• 2007

It is noted that the disaster such as fire, explosion, collapse has been rapidly increased caused by strength deterioration of steel structures at petrochemical plant during fire. In this regard, it is stressed out that the legal requirement for fire proofing for steel structures at petrochemical plant should be carefully reviewed since the current legal requirement such as Industrial Safety & Health Law, Architectural Law has a conflict and different way of approach. In addition, it is our point of view that the present law should be revised to consolidate into single law including engineering design criteria to reflect unreasonable legal requirement. It is further our point of view that the performance certificate for fire proofing like UL-1709, basis of maintenance should be appropriately and reasonably provided in line with global practice.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.1
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• pp.1-14
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• 1999

선형탄성이론을 기초로 한 구조해석의 경우 사용하중상태에서의 변형과 응력은 만족할 만한 결과를 나타내지만, 항복후의 처짐과 파괴시의 극한하중 산정의 정확한 해석이 불가능하다. 평판의 극한해석시, 상한계 이론을 바탕으로 한 항복선 이론이 널리 사용되고 있으나 이론적으로 평판의 강도를 과대평가하게 된다. 그러므로, 임의의 하중조건과 경계조건에 대한 비선형 거동과 극한내하력을 산정할 수 있는 해석기법이 필요하다. 평판의 정확한 극한하중을 위해 p-Version 유한요소법을 제안하며, p-Version의 해석치를 범용 구조해석 프로그램인 ADINA의 결과와 문헌의 이론치와 비교하였다.

• Journal of Korean Association for Spatial Structures
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• v.9 no.1
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• pp.47-52
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• 2009

In this study, it is demonstrated by a pseudo dynamic earthquake response tests that combination of semi-rigid partial-strength using the high performance-high strength bolts and inter-story hysteretic damper system creates a fairly good structural system that satisfies not only the serviceability requirement under moderate earthquakes but unexpected failure of damper system.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.145-148
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• 2015

Young Galactic supernova remnants (SNRs) are where we can observe closely supernova (SN) ejecta and their interaction with the circumstellar/interstellar medium. They also provide an opportunity to explore the explosion and the final stage of the evolution of massive stars. Near-infrared (NIR) emission lines in SNRs mostly originate from shocked dense material. In shocked SN ejecta, forbidden lines from heavy ions are prominent, while in shocked circumstellar/interstellar medium, [Fe II] and $H_2$ lines are prominent. [Fe II] lines are strong in both media, and therefore [Fe II] line images provide a good starting point for the NIR study of SNRs. There are about twenty SNRs detected in [Fe II] lines, some of which have been studied in NIR spectroscopy. We will review the NIR [Fe II] observations of SNRs and introduce our recent NIR spectroscopic study of the young core-collapse SNR Cas A where we detected strong [P II] lines.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.77-79
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• 1996

This paper presents an integrated stability analysis by the direct energy function method based on Equivalent Mechanical Model(EMM) which reflects the system behavior related to both angle and voltage stabilities. Actually, angle and voltage stability are intimately related in power system, so complete decoupling of these stability analysis is not possible in general, particularly in stressed power systems. In this paper, it is shown that a identical energy function can be used for angle and voltage stability analysis. The proposed energy function reflects the line resistances and reactive powers under the constraints of the same R/X ratio. The energy margin between UEP and SEP presents a good collapse proximity index in both types of stability analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.366-373
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• 2006

In order to reduce the secondary earthquake disaster resulting from the damage of gas facilities it is indispensable to establish an early response system on the basis of damage prediction. In this study the procedure of damage prediction for gas facilities is proposed and applied to the gas supply model area. Model area is divided into several little blocks. The soil condition and the characteristics of facilities were investigated at each block. Using fragility curves of facilities the damage level was analyzed under various seismicities. It is confirmed that the exposure gas pipe line in several blocks is damaged seriously by the collapse of building structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.1
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• pp.15-23
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• 2009

Masonry structures that are very strong in compression fail due to the instability of structural shape of geometry rather than the material stress limit. Considering such structural behavior, the use of the limit theorem that focuses on structural collapse mechanisms is more appropriate for the evaluation of the structural safety of stone voussoir arch bridges. This paper is to investigate structural performance of the stone arch bridges constructed using dry construction method in Korea based on the limit theorem and to exploit the result to develop a system for an structural safety margin. It is expected that this study will help us understand structural behavior of stone voussoir arch bridges in Korea. Also, it will provide a guideline to make engineering decision from the viewpoint of the maintenance of cultural heritages.