• Structural Engineering and Mechanics
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• 제62권4호
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• pp.455-464
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• 2017

Rayleigh damping model is recommended in the recently developed Performance-Based Earthquake Engineering (PBEE) methodology, but this methodology does not provide sufficient information due to the complexity of the damping mechanism. Furthermore, each Rayleigh-type damping model may have its individual limitations. In this study, Rayleigh-type damping models that are used widely in engineering practice are discussed. The seismic performance of a large-span single-layer latticed dome subjected to earthquake ground motions is investigated using different Rayleigh damping models. Herein a simulation technique is developed considering low cycle fatigue (LCF) in steel material. In the simulation technique, Ramberg-Osgood steel material model with the low cycle fatigue effect is used to simulate the non-uniformly distributed material damping and low cycle fatigue damage in the structure. Subsequently, the damping forces of the structure generated by different damping models are compared and discussed; the effects of the damping ratio and roof load on the damping forces are evaluated. Finally, the low cycle fatigue damage values in sections of members are given using these damping models. Through a comparative analysis, an appropriate Rayleigh-type damping model used for a large span single-layer latticed dome subjected to earthquake ground motions is determined in terms of the existing damping models.

• 한국사회복지학
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• 제42권
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• pp.107-138
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• 2000

Today, the public assistance program in Korea is provided mainly for the livelihood protection beneficiary in urban area. The fact that the urban community-centered program is also applied to the livelihood protection beneficiary in rural area brings about some problems in fitness and effectiveness of resource distribution. The purpose of my study is to present my opinion that the public assistance program for the rural community should be put in practice after being fully distinguished from the urban program for the effective distribution of limited social welfare resources to insure the minimum standard of living and seek the self-support contribution which is the purpose of the public assistance program. The subject for this study were livelihood protection beneficiaries living in both rural and urban area. And the study was carried out in this parts: first, the way of life in them, second, the contents of 6 main public assistance programs being carried out. Total number of the livelihood protection beneficiaries are 279 case: 143 case from 15 Dong in 5 cities, and 136 case from 15 Myun in 5 counties. And the social worker who are performing the public assistance programare consisted of 50 case: 25 case from 5 Dong in 5 cities, and 25 case from 5 Myun in 5 counties. This research reach the result that the differentiate performance of the public assistance program in rural community would be an effective device for self-support to be freed from the vicious circle of poverty.

• 한국위성정보통신학회논문지
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• 제7권2호
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• pp.18-24
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• 2012

본 논문에서는 ESD 방지를 위한 최적 방법론에 목표하여 확장된 드레인을 갖는 EDNMOS 소자의 더블 스냅백 현상 및 백그라운 도핑 농도 (BDC)의 영향을 조사하였다. 고전류 영역에서 낮은 BDC를 가진 EDNMOS 소자는 강한 스냅백으로 인해 취약한 ESD 성능과 높은 래치업 위험을 가지게 되나, 높은 BDC를 가진 EDNMOS 소자는 스냅백을 효과적으로 방지할 수 있음을 알 수 있었다. 따라서 BDC 제어로 안정적인 ESD 방지 성능과 래치업 면역을 구현할 수 있음을 밝혔다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.220-223
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• 2007

Acoustic test of the payload fairing of Korea satellite launch vehicle was conducted to verify the performance of acoustic protection system installed inside the payload fairing. This paper briefly introduces the acoustic test procedures and its results. Overall 148 dB acoustic loads were exerted on the payload fairing structures which mated with the upper stage structure of the launch vehicle. In order to verify the increase of insertion loss by the acoustic protection system, two kinds of test were performed. One is conducted with acoustic protection system and the other without acoustic protection system. Internal acoustic loads as well as external ones were measured and the measured insertion losses were compared with the requirement. The results showed that the acoustic protection system increases the insertion loss by more than 6 dB above 125 Hz. They also indicated that some design modification of Helmholtz resonator array is required to increase the insertion loss at a cavity resonant frequency.

• 전기학회논문지
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• 제56권5호
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• pp.854-859
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• 2007

A wind farm consists of many wind generator(WG)s therefore, it is generally a complex power system. A wind farm as a distributed generation(DG) affects utility power system. If a conventional protection schemes are applied, it is difficult to detect faults correctly and the schemes can't provide proper coordination in some cases. This paper presents a protection algorithm for a wind farm which consists of a looped collection circuit. Because the proposed algorithm can distinguish between an internal fault and an external fault in a wind farm, The proposed algorithm can disconnect the faulted section in a wind farm. This algorithm is based on an overcurrent protection technique with the change of the ratio of the output current of a generator to the current of the looped line connected to each generator to collect the each generator's power. In addition, operating time of the algorithm is shortened by using the voltage drop at a generator collection point. The performance of the proposed algorithm was verified under various fault conditions using PSCAD/EMTDC simulations.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.503-507
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• 2000

The corrosion protection methods of reinforcing steel in concrete are the various methods such as increasing thickness of cover concrete, using of reinforcing bars coated with epoxy, dosage of corrosion inhibitor as concrete admixture, cathodic protection method and etc. In this study, the performance of corrosion protection was investigated for the test specimens using corrosion inhibitors and cathodic protection, respectively. For this purpose, the accelerated corrosion tests for reinforcing steel were conducted according to the periodic cycles(140 days) of wetting($65^{\circ}C$, 90% R.H) and drying period($15^{\circ}C$, 65% R.H) for the test specimens. As a result, it can be concluded from the test that the effect of corrosion inhibitor was found to be variable with products, the cathodic protection method was found to be independent of salt concentration in concrete.

• 전기학회논문지
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• 제58권8호
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• pp.1538-1543
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• 2009

The electric ballast for ceramic metal halide lamp needs a protection circuit to prevent from over voltage and over current in the case that the lamp or the electric ballast are in faults. In this paper, cost-effective and high performance protection circuit is proposed for the electric ballast. The proposed protection circuit is adapted to the electric ballast with $LC_SC_P$ resonance type half bridge inverter. The experimental results demonstrate that the proposed circuit can protect effectively under open and short fault conditions.

• Journal of Power Electronics
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• 제2권3호
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• pp.171-180
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• 2002

New 42-volt automotive electrical systems can provide significant improvements in vehicle performance and fuel economy. It is crucial to provide protection against load dump and other overvoltage transients in 42-volt systems. While advanced active control techniques are generally considered capable of providing such protection, the use of passive transient voltage suppression (TVS) devices as a secondary or supplementary protection means can significantly improve design flexibility and reduce system costs. This paper examines the needs and options for passive TVS devices for 42-volt applications. The limitations of the commonly available automotive TVS devices, such as Zener diodes and metal oxide varistors (MOV), are analyzed and reviewed. A new TVS device concept, based on power MOSFET and thin-film polycrystalline silicon back-to-back diode technology, is proposed to provide a better control on the clamp voltage and meet the new 42-volt specification. Both experimental and modeling results are presented. Issues related to the temperature dependence and energy absorbing capability of the new TVS device are discussed in detail. It is concluded that the proposed TVS device provides a cost-effective solution for load dump protection in 42-volt systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.835-837
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• 1997

This paper presents a control system design for the STATCON of FACTS devices by LQR, LQG control scheme to enhance small-signal stability in the power system, the feature of this FACTS controller is coordinated with generator exciter controller(AVR, PSS) to improve the total power system stability and performance.

• Corrosion Science and Technology
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• 제11권4호
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• pp.112-119
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• 2012

This paper presents the results of a study of the effectiveness of cathodic protection with insoluble ICCP anode in reinforced concrete structures. Experimental tests were carried out on reinforced concrete specimens with 3 different commercial anodes for ICCP system in order to compare the effectiveness of cathodic protection. Results have shown that the kinds of anode for ICCP is irrelevant to the effectiveness of cathodic protection, In case of ICCP, the performance of cathodic protection has no relationship to the kinds of anode especially in concrete specimens with sea water condition. It has been found slightly more effective at Ti-Rod anode in fresh water condition and Ti-Mesh anode in atmospheric condition.