• Geomechanics and Engineering
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• 제21권1호
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• pp.35-51
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• 2020

In this study, the seismic response analysis of embankment dams was investigated through numerical modeling. The seismic behavior of dams under main earthquake records and wavelet-based records were studied. Earthquake records were decomposed using de-noising method (DNM) and down-sampling method (DSM) up to five levels. In decomposition process, low and high frequencies of the main earthquake record were separated into two signals. Acceleration response, spectral acceleration, and Fourier amplitude spectrum at the crest of embankment dams under different decomposition levels were evaluated. The seismic behavior under main and decomposed earthquake records was compared. The results indicate an acceptable agreement between the seismic responses of embankment dams under wavelet-based decomposed records and main earthquake motions. Dynamic analyses show that the DNM-based decomposed earthquake records have a better performance compared to DSM-based records. DNM-based records up to level 4 and DSM-based records up to level 2 have a high accuracy in assessment of seismic behavior of embankment dams. The periods corresponding to the maximum values of acceleration spectra and the frequencies corresponding to the maximum values of Fourier amplitude spectra of embankment dam crest under main and decomposed records are in good agreement. The results demonstrate that the main earthquake records can be replaced by wavelet-based decomposed records in seismic analysis of embankment dams.

• 환경영향평가
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• 제4권2호
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• pp.123-130
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• 1995

The equipment composed of many complicated electronic stuffs undergoes diverse stresses caused by mechanical vibrations during its service. Thus, to ensure its proper operation in the field a simulated vibration test has to be carried out in the laboratory with the Vibration Qualification Level, the test specification, which can include the real environment. In this paper we intent to deal with method and procedure for determining the Vibration Qualification Level so as to estimate the vibration-endurance for the equipment precisely.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.123-126
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• 2002

Acoustic vibration analysis has been performed using random vibration analysis module of MSC/NASTRAN to evaluate the safety of the composite satellite antenna structure under the acoustic pressure from the launch vehicle. It was found that maximum $3\sigma$ stress by acoustic excitation was less than allowable stress.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 봄 학술발표회 논문집
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• pp.26-29
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• 1992

Modern tall buildings are subject to wind induced oscillations. Those oscillations can cause discomfort to the occupants. To control these motions, tuned mass dampers have been used. In this paper, component node synthesis, based on Lagrange multipliers formulation. is applied to the along-wind motion of tall buildings with multiple tuned mass dampers. Spectral densities of accelerations of top floor are compared by changing the numbers and locations of tuned mass dampers. It is found that multiple tuned mass dampers can be more effective than single tuned mass damper in reducing the acceleration response.

• 전자공학회논문지B
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• 제32B권12호
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• pp.1552-1564
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• 1995

A fault detecting method of ternary logic is proposed by using the spectral coefficients of the Chrestenson function. Fault detecting conditions are derived for a stuck-at fault in case of single input, multiple inputs and internal lines in the ternary logic. The detecting conditions for min/max bridging faults are also considered. When using this fault analysis method, it is possible to detect faults without the test vector and minimize high volume memory for storing the vector and response data. Thus, the computational complexity for the test vector can be decreased.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.41-48
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• 1999

Small earthquake records with magnitude 2.7-4.8 recorded in Kyungsang Basin during 1995-1997 were analysed. Total of 87 records consisted of 16 events instrumented at 11 stations,. Mean dominant period at each station mean zero period acceleration of each component and the acceleration response spectra were analysed. Spectral value increases as magnitude increases and the predominant frequency band expands to low frequency zone as magnitude increases.

• 대한원격탐사학회지
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• 제28권5호
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• pp.531-548
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• 2012

남해안에서 발생한 Cochlodinium polykrikoides 적조를 적조인 경우와 아닌 경우(satellite high chlorophyll water)로 부터 분류하기 위해서, 본 연구는 Son et al.(2011)의 spectral classification 방법을 세계 최초 해색위성인 GOCI 파장에 맞도록 개선했다. C. polykrikoides 적조인 경우와 아닌 경우는 네 가지 단계를 거쳐서 분리했다. 첫 번째 단계는 적조 발생 가능지역으로 555nm와 680nm (fluorescence peak)에서 피크를 보이는 지역을 선택했다. 두 번째 단계는 적조 발생 가능 지역 중에서 용존유기물/부유물질 함량이 높은 지역과 낮은 지역을 구분했다. 세 번째와 네 번째 단계는 blue-to-green 밴드비를 이용하여 적조 발생 지역과 아닌 지역을 구분했다. 네 가지 단계를 적용한 결과 적조의 스펙트럼은 증가된 식물성 플랑크톤과 용존유기물(부유물질)의 흡광 때문에 짧은 파장에서는 낮은 기울기를 보이고, 증가된 부유물질 때문에 긴 파장에서는 상대적으로 증가된 기울기를 나타냈다. GOCI를 위해 개선된 spectral classification 방법은 C. polykrikoides 적조인 경우와 적조가 아닌 경우에 대해서 높은 user accuracy를 보이고, 다양한 해양환경에서 신뢰성 있는 적조 탐지 가능성을 보이고 클로로필 농도를 이용한 방법이나 기존의 다른 적조 탐지 방법보다 좋은 결과를 보였다. 남해안 C. polykrikoides 적조는 2012년 7월 말에서 8월 초까지 나로도와 통영 부근 해상에서 탐지 되었고, 2012년 8월 중순에는 완도에서 거제도까지 남해안 전체에 걸쳐 발생했다.

• 자원환경지질
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• 제52권2호
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• pp.129-139
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• 2019

본 연구는 적상추(Lactuca sativa var crispa L.)가 아연을 축적함에 따라 발생하는 분광학적 반응특성을 고찰하기 위해, 대조군(T0)과 1 mM(ZnT1), 5 mM(ZnT2), 10 mM(ZnT3), 50 mM(ZnT4), 100 mM(ZnT5)로 처리된 실험군을 제작하여 분실험을 실시하였다. 대조군의 아연함량은 134-181 mg/kg의 범위로 오염되지 않은 농작물이 갖는 정상수준의 아연함량을 보였다. 그러나 아연용액의 주입농도가 증가하고 시간이 경과함에 따라 실험군 내 아연함량은 증가하였다. 적상추의 분광반사도는 적색밴드에서 안토시아닌에 의한 높은 피크, 적외선 대역에서 세포구조의 산란효과로 인한 높은 반사도, 그리고 물에 기인한 흡광특성이 관찰되었다. 적상추 내 아연이 고농도로 축적됨에 따라 녹색과 적색밴드에서는 반사도가 증가하고 적외선 대역에서는 반사도가 감소하였다. 아연함량과 분광반사도 사이의 상관관계 분석결과는 700-1300 nm의 파장대역이 아연함량과 유의한 음의 상관관계를 가짐을 보여주었다. 해당 파장대역은 잎 중의 세포구조와 밀접한 관계가 있는 파장대역으로 아연함량이 증가함에 따라 잎 중의 세포구조가 파괴됨을 지시한다. 특히 적외선 대역 중 700-800 nm은 아연함량과 가장 강한 상관관계를 보여주었다. 본 연구는 적상추의 중금속 오염을 분광학적으로 인지하여 광업 및 농업지역 주변 토양 내 중금속 오염을 조사하는데 활용 가능할 것으로 판단된다.

• Structural Engineering and Mechanics
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• 제33권2호
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• pp.179-191
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• 2009

This paper is aimed at combining wavelet multiresolution analysis and nonstationary Kanai-Tajimi model for the simulation of earthquake accelerograms. The proposed approach decomposes earthquake accelerograms using wavelet multiresolution analysis for the simulation of earthquake accelerograms. This study is on the basis of some Iranian earthquake records, namely Naghan 1977, Tabas 1978, Manjil 1990 and Bam 2003. The obtained results indicate that the simulated records preserve the significant properties of the actual accelerograms. In order to investigate the efficiency of the model, the spectral response curves obtained from the simulated accelerograms have been compared with those from the actual records. The results revealed that there is a good agreement between the response spectra of simulated and actual records.

• ETRI Journal
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• 제42권4호
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• pp.585-595
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• 2020

Integration of multiple communication technologies in a smart grid (SG) enables employing cognitive radio (CR) technology for improving reliability and security with low latency by adaptively and effectively allocating spectral resources. The versatile features of the CR enable the smart meter to select either the unlicensed or the licensed band for transmitting data to the utility company, thus reducing communication outage. Demand response management is regarded as the control unit of the SG that balances the load by regulating the real-time price that benefits both the utility company and consumers. In this study, joint allocation of the transmission power to the smart meter and consumer's demand is formulated as a two stage multi-armed bandit game in which the players select their optimal strategies noncooperatively without having any prior information about the media. Furthermore, based on historical rewards of the player, a real-time pricing adaptation method is proposed. The latter is validated through numerical results.