• Nuclear Engineering and Technology
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• 제43권6호
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• pp.567-572
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• 2011

A sensitivity analysis of the methods used to evaluate the transport properties of a CdZnTe detector was performed using two different radiations (${\alpha}$ particle and gamma-ray) emitted from an $^{241}Am$ source. The mobility-lifetime products of the electron-hole pair in a planar CZT detector ($5{\times}5{\times}2\;mm^3$) were determined by fitting the peak position as a function of biased voltage data to the Hecht equation. To verify the accuracy of these products derived from ${\alpha}$ particles and low-energy gamma-rays, an energy spectrum considering the transport property of the CZT detector was simulated through a combination of the deposited energy and the charge collection efficiency at a specific position. It was found that the shaping time of the amplifier module significantly affects the determination of the (${\mu}{\tau}$) products; the ${\alpha}$ particle method was stabilized with an increase in the shaping time and was less sensitive to this change compared to when the gamma-ray method was used. In the case of the simulated energy spectrum with transport properties evaluated by the ${\alpha}$ particle method, the peak position and tail were slightly different from the measured result, whereas the energy spectrum derived from the low-energy gamma-ray was in good agreement with the experimental results. From these results, it was confirmed that low-energy gamma-rays are more useful when seeking to obtain the transport properties of carriers than ${\alpha}$ particles because the methods that use gamma-rays are less influenced by the surface condition of the CZT detector. Furthermore, the analysis system employed in this study, which was configured by a combination of Monte Carlo simulation and the Hecht model, is expected to be highly applicable to the study of the characteristics of CZT detectors.

• 한국위성정보통신학회논문지
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• 제11권3호
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• pp.119-122
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• 2016

특징 검출 기법은 원하는 신호에 대한 부분적인 정보가 수신단에 알려진 상황에서 정확도 높은 검출이 가능한 기법으로 알려져 있다. 이러한 방식의 검출 기법은 잡음이 강한 환경을 위해 제안되었다. 사이클로스테이셔너리 검출은 인지 무선 시스템에서 스펙트럼 검출 기법의 하나의 예이다. 그러나 이 기법은 원하는 신호에 대한 많은 양의 정보와 처리 시간을 요구한다. 반면, 에너지 검출 기반의 스펙트럼 검출은 단순한 기법으로 널리 알려져 있다. 그러나 에너지 검출은 잡음의 영향을 많이 받으며 이로 인한 검출 오류가 많이 발생하게 된다. 본 논문에서는 에너지와 사이클로스테이셔너리 기반의 기법을 결합하여 검출의 정확도를 높이는 한편 계산량과 처리 시간을 감소시키는 기법을 제안한다. 2단계의 문턱값을 이용하여 사이클로스테이셔너리 기법의 복잡도와 처리시간을 단축하여 시스템의 전송 효율을 증가시킨다. 시뮬레이션 결과 에너지 기반 사이클로스테이셔너리 검출 기법은 신호 검출에 소요되는 시간을 상당히 감소시키는 반면 시스템의 성능을 향상시킴을 보여준다.

• 대한조선학회논문집
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• 제52권1호
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• pp.88-95
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• 2015

For the frequency-domain spectral fatigue analysis, the probability density function of stress range needs to be estimated based on the stress spectrum only, which is a frequency domain representation of the response. The probability distribution of the stress range of the narrow-band spectrum is known to follow the Rayleigh distribution, however the PDF of wide-band spectrum is difficult to define with clarity due to the complicated fluctuation pattern of spectrum. In this paper, efforts have been made to figure out the links between the probability density function of stress range to the structural response of wide-band Gaussian random process. An artificial neural network scheme, known as one of the most powerful system identification methods, was used to identify the multivariate functional relationship between the idealized wide-band spectrums and resulting probability density functions. To achieve this, the spectrums were idealized as a superposition of two triangles with arbitrary location, height and width, targeting to comprise wide-band spectrum, and the probability density functions were represented by the linear combination of equally spaced Gaussian basis functions. To train the network under supervision, varieties of different wide-band spectrums were assumed and the converged probability density function of the stress range was derived using the rainflow counting method and all these data sets were fed into the three layer perceptron model. This nonlinear least square problem was solved using Levenberg-Marquardt algorithm with regularization term included. It was proven that the network trained using the given data set could reproduce the probability density function of arbitrary wide-band spectrum of two triangles with great success.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.567-572
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• 2008

This paper's purpose is to improve determining of the critical response of curved bridge to multi-component seismic motion. There are several methods to combine responses by multi-component excitation response, 30%, 40% rules and square-root-of-sum (SRSS). These combination rules determine same value of critical response in straight bridges. However, each method has critical response value of different magnitude in curved bridges. Thus a study about critical response of curved bridges is required. This paper presents comparison critical responses value as each combination rule, 30%, 40% rules and SRSS on curved bridges with the different radiuses of curvature. This study was carried out by response spectrum analysis of OO IC steel box girder bridge using SAP2000. It is concluded as follows: 1) In curved bridges, 30% and 40% rules tend to underestimate the critical response relatively to SRSS. 2) When bridges have smaller radiuses than 100m, difference between SRSS and 30% or 40% rules let run errors up as radiuses of curvature decreased.

• 한국잡초학회지
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• 제2권2호
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• pp.129-140
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• 1982

식물(植物) 생태학(生態學)에서 식생분석(植生分析)에 이용(利用)되는 two-dimensional ordination 분석법(分析法)을 사용(使用)하여 잡초군락형살초(雜草群落型殺草) spectrum을 분류(分類)하여 효과적(效果的)인 제초제선발(除草制選拔), 체계처리(體系處理) 및 약제가격절감(藥劑價格節減)을 위(爲)한 기초자료(基礎資料)를 얻고자 2개년(個年)(1980, 1981)에 걸쳐 포장시험(圃場試驗) 및 pot시험(試驗)으로 실시(實施)하였던 결과(結果)를 요약(要約)하면 다음과 같다. 1. 26종(種)의 수도용(水稻用) 제초제(除草劑)를 pot 시험(試驗)으로 처리(處理)하여 제초제군(除草劑群)을 분류(分類)한 결과(結果) 마디꽃 (48%) - 올챙고랭이 (35%) - 알방동산이 (8%) 잡초군락형(雜草群落型)에서는 6개군(個群), 마디꽃 (45%) - 물달개비 (35%) - 바람하늘직이 (9%) 잡초군락형(雜草群落型)에서는 10 개군(個群)으로 분류(分類)되었다. 2. 포장(圃場) 시험결과(試驗結果)에 있어 18종(種)의 제초제(除草劑)를 너도방동산이 (37%) - 올챙고랭이 (19%) - 물달개비 (14%) - 피 (7%) - 사마귀풀 (6%) 잡초군락형((雜草群落型)에서 처리(處理)하였던 결과(結果) 7개(個) 제초제군(除草劑郡)으로 분류(分類)되었고, 물달개비 (40%) - 여뀌바늘 (27%) - 너도 방동산이 (17%) - 올챙고랭이 (12%) 잡초군락형(雜草群落型에)에서 19종(種)의 제초제(除草劑)를 처리(處理)하였던 결과(結果)는 14개(個) 제초제군(除草劑群)으로 분류(分類)되었다. 3. two-dimensional ordination 분석법(分析法)은 제초제살초(除草劑殺草) spectrum 분류(分類)뿐만 아니라 제초제처리방법(除草劑處理方法)에 따른 문제잡초(問題雜草)를 구명(究明)하는데도 이용(利用)이 가능(可能)하였다. 4. 본(本) 시험결과(試驗結果)를 미루어 보아 효과적(效果的)인 제초제사용(除草劑使用)을 위(爲)해서는 단순(單純)히 제초제(除草劑) 상호간(相互間)의 유사성계수(類似性係數)(Similarity coefficient)를 이용(利用)하는 것 보다 two-dimensional ordination 분석법(分析法)을 이용(利用)하므로서 효과적(效果的)인 제초제선발(除草劑選拔), 살초(殺草) spectrum 증대(增大)를 위(爲)한 혼합처리(混合處理) 또는 체계처리(體系處理) 및 약제가격(藥劑價格)을 절감(節減)하기 위(爲)한 혼합처리(混合處理) 등(等)에 관(關)한 정보(情報)를 비교적(比較的) 쉽게 얻을 수 있었다.

• 한국산학기술학회논문지
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• 제14권3호
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• pp.1191-1196
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• 2013

임상검체에서 분리되는 그람음성 막대균의 제 3세대 cephalosporin에 대한 내성율의 증가는 임상적으로 심각한 문제가 되고 있다. 3세대 cephalosporin 및 monobactam계 항균제에 대한 내성은 주로 Extended-Spectrum ${\beta}$-Lactamase(ESBL)의 생성에 기인한다. 따라서 ESBL 유전자의 정확한 검출은 병원내의 감염경로 파악을 위한 감시 및 역학조사를 위해 필수적이다. 본 연구는 2012년 2월부터 8월까지 대전, 충남, 충북지역의 대학병원으로부터 ESBL 생성 Klebsiella penumoniae 46균주를 분리하여 Clinical and Laboratory Standards Institute (CLSI)에 따라 ceftazidime (CAZ)과 CAZ/clavulanate (CLA)를 이용한 combination disk test (CDT) 방법에 의해 표현형을 조사하고, 유전형 특이 프라이머를 이용한 multiplex PCR을 수행하여 유전형을 검출하였다. CDT 결과 42균주가 ESBL생성균주로 확인되었다. PCR 결과, 46균주 모두 TEM형이었으며, 37균주는 SHV형, 14균주는 CTX-M형으로 나타났으며 10균주가 TEM, SHV, CTX-M 유전자를 모두 가지고 있었다. Multiplex PCR에 의한 유전형 검출 방법은 임상에서 분리한 ESBL생성 K. penumoniae균주의 감별과 검출에 유용한 방법으로 사료된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1301-1318
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• 2017

In order to utilize the licensed channel of cognitive radio (CR) when the primary user (PU) is detected busy, a benefit-exchange access mode based on cooperative communication is proposed to allow secondary user (SU) to access the busy channel through giving assistance to PU's communication in exchange for some transmission bandwidth. A holistic joint optimization problem is formulated to maximize the total throughput of CR system through jointly optimizing the parameters of cooperative spectrum sensing (CSS), including the local sensing time, the pre-configured sensing decision threshold, the forward power of cooperative communication, and the bandwidth and transmission power allocated to SUs in benefit-exchange access mode and traditional access mode, respectively. To solve this complex problem, a combination of bi-level optimization, interior-point optimization and exhaustive optimization is proposed. Simulation results show that, compared with the tradition throughput maximizing model (TTMM), the proposed holistic joint optimization model (HJOM) can make use of the channel effectively even if PU is busy, and the total throughput of CR obtains a considerable improvement by HJOM.

• Structural Engineering and Mechanics
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• 제36권3호
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• pp.321-341
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• 2010

The seismic-induced failure of a dam could have catastrophic consequences associated with the sudden release of the impounded reservoir. Depending on the severity of the seismic hazard, the characteristics and size of the dam-reservoir system, preventing such a failure scenario could be a problem of critical importance. In many cases, the release of water is controlled through a reinforced-concrete intake tower. This paper describes the application of a static nonlinear procedure known as the Capacity Spectrum Method (CSM) to evaluate the structural integrity of intake towers subject to seismic ground motion. Three variants of the CSM are considered: a multimodal pushover scheme, which uses the idea proposed by Chopra and Goel (2002); an adaptive pushover variant, in which the change in the stiffness of the structure is considered; and a combination of both approaches. The effects caused by the water surrounding the intake tower, as well as any water contained inside the hollow structure, are accounted for by added hydrodynamic masses. A typical structure is used as a case study, and the accuracy of the CSM analyses is assessed with time history analyses performed using commercial and structural analysis programs developed in Matlab.

• 대한토목학회논문집
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• 제10권3호
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• pp.1-6
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• 1990

다지점지진하중(多支點地震荷重)을 받는 사경문(四徑問) 연속철도교양(連續鐵道橋梁)의 동적거동(動的擧動)을 응답(應答)스펙트럼법(法)에 의하여 조사(調査)하였다. 소진복(小振福)의 진동(振動)과 재료(材料)의 선형(線形)-탄성거동(彈性擧動)을 가정(假定)하였으며, 지반(地盤)-구조물(構造物) 상호작용(相互作用) 효과(效果)는 무시(無視)하였고, 교량(橋梁)의 횡방향(橫方向) 등답(應答)만을 고려(考慮)하였다. 응답(應答)스펙트럼해석(解析)의 결과(結果)는 시간이력해석결과(時間履歷解析結果)와 비교(比較)되었으며 모우드 최대치(最大値)와 지지점운동(支持點運動)의 중량(重量)은 여러가지 조합법칙(組合法則) 즉(卽), Square-Root-Of-Sum-Squares, Double Sum, 그리고 P-Norm Rule을 적용(適用)하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2014년도 춘계학술발표대회
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• pp.206-209
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• 2014

Control message exchange is major job for cognitive radio to exist and use spectrum opportunistically. For this control message exchange they need a common control channel (CCC). Once this channel is affected by a primary user, communication stops until new CCC is setup. This takes substantial time and if they could not get free channel, this halt continues for long time. To prevent such cease of communication, we propose a combination of two networks, namely WLAN and UWB, to let the communication continue. In our proposed idea if the CCC of a certain CR in WLAN is affected, the CR changes its network from WLAN to UWB and keeps the communication because UWB cannot be affected by PU. In the proposed idea every cognitive radio has two transceivers; one for the overlay network (WLAN) and another UWB network. If a primary user is detected in the spectrum of a cognitive radio, it continues exchanging control messages under the UWB network and in parallel negotiates for a new CCC using the WLAN network. This idea solves the communication interruption until new CCC is setup.