• 방송공학회논문지
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• 제23권2호
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• pp.302-315
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• 2018

지각 양자기 광전 변환 함수의 생략 Taylor 급수를 이용한 선형 근사는 휘도 조절 기법의 하드웨어 구현에 적합한 폐쇄형 솔루션을 제공할 수 있지만, 600~3,900 cd/m2 구간의 선형 영역 광 신호에 대해 상대적으로 큰 근사 오차를 유발한다. 이러한 비-선형 광전 변환 함수의 근사 오차 개선을 위해, 본 논문에서는 새로운 선형 모델을 제안한다. 제안된 선형 근사 모델은 그 근사 범위를 고려한 직선의 위치 교정 및 기울기 산출을 수행한다. 제안 모델의 성능 검증을 위해, 다양한 고-휘도 실험 시퀀스를 대상으로 모의실험을 수행하였고, 이를 통해 채도가 높은 색상을 포함하는 시퀀스에 대해서는, Taylor 급수를 기반으로 한 기존의 선형 모델에 비해, 휘도 신호의 t-PSNR을 4.65dB 만큼 개선할 수 있는 높은 성능 향상을 확인하였다.

• 가족자원경영과 정책
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• 제17권2호
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• pp.121-145
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• 2013

The purpose of this study is to understand married female immigrants' life adjustment process in Korea by explaining the resources to which they have access and how they use them. The data were collected through in-depth interviews with ten female participants who have more than one child, have participated in programs of the multicultural family support center, have work experience, can communicate with Koreans, and live in Daegu. The major findings are as follows. The participants' personal resources differed. English language skills were very useful resources for making money and for earning the respect of family members and others. However, the participants without English language skills had sincerely and actively tried to learn the Korean language and gain bilingual competence. The participants obtained diverse family resources from their husbands and parents-in-law after adapting themselves to perform their gender role. Further, the participants used the social resources offered by public support systems as a starting point for learning the Korean language in their early adaptation process, and formed personal networks with staff members at the multicultural family support center. The results show that the participants used many kinds of resources for acculturation by interacting positively with their environment. Moreover, the resources from diverse levels of their environments affected their acculturation process.

• 한국경제지리학회지
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• 제12권4호
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• pp.665-680
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• 2009

본 연구의 목적은 위험조정모형을 활용하여 미국 REITs의 부동산 유형별 성과 특성을 분석하는 것이다. 특히, REITs의 성과가 성장기, 정체기, 금융위기기에 각각 어떻게 차별적인 지를 살펴본다. 분석결과를 요약하면 다음과 같다. 첫째로, 초과 종합수익률의 관점에서 REITs 부동산 유형별 성과를 보면, 1기와 2기에는 정(+)의 초과 성과가 발생한 반면, 3기에는 부(-)의 초과 성과가 나타난다. 금융위기 시기인 3기의 경우, 부(-)의 수익률이 발생한 뿐만 아니라 수익률의 변동성도 큰 것으로 나타난다. 둘째로, 자본자산가격결정모형에 의해 추정한 베타값을 보면, <분석모형 (1)>의 결과에서 평균적인 REITs에 비해 호텔, 지역몰, 상업모기지는 고위험-고수익 특성을, 자유입지, 아파트, 조립식주택, 특수목적 부동산은 저위험-저수익 특성을 가진 것으로 나타난다. <분석모형 (2)>의 결과를 보면, 금융위기 하에서 투자상품으로서의 REITs의 성격이 저위험-저수익에서 고위험-고수익으로 변화하고 있다. 마지막으로, 위험조정모형 추정결과를 보면, <분석모형 (1)>과 <분석모형 (2)> 모두 체계적 위험은 요구수익률에 정(+)의 영향을 미치는 반면, 비체계적위험은 요구수익률에 부(-)의 영향을 미치는 것으로 나타난다. 위험조정모형을 통해 도출된 요구수익률을 실제수익률과 비교한 결과, 헬쓰케어 부문이 가장 높은 정(+)의 성과를 보이고 있다.

• 한국항만경제학회지
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• 제20권2호
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• pp.187-216
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• 2004

Northeast Asia logistics hub strategy was undertaken by Korean Government to gain a national competitive advantage in Northeast Asia. Current Government has Northeast Asian Economic Hub Strategy including construction of SOC in Northeast Asia for promoting peace, promotion of formation of Northeast Asia Community, logistics hub, Financial hub and national innovation for R&D Cluster. To realize Northeast Asian logistics hub, the Northeast Asia logistics hub road map has undertaken as follows: expansion of logistics infra in Incheon Airport, Busan Port and Gwangyang Port, systematic improvements such as adjustment of investment distribution, special logistics companies, transparent customs in logistics transactions, logistics manpower, improvement of system supporting global logistics and attraction of international logistics companies to the logistics center, construction of seamless and paperless logistics information network, Northeast Asia railway infra. The purpose of this paper is to study investment priority and improvements in the Northeast Asia Logistics Hub Road Map and to contribute to gain the national competitive advantage as logistics hub in Northeast Asia

• Journal of Advanced Marine Engineering and Technology
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• 제25권5호
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• pp.1086-1090
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• 2001

In this paper, a method deciding the permissible gains of the P and PT controllers for a retarded process under stable condition is proposed. For analysis, the controlled process is assumed to be first-order system with time delay. At first, the adjustable parameter sets causing stability limit are obtained based on the frequency domain condition which makes the roots of the characteristic equation locate on the imaginary axis. And the cut-in frequency ${\omega}_p$ to bring the parameter set to P control from PI control is derived is derived in terms of L and $T_m$ then ${\omega}_p$ is used to compute the maximum gain with stable condition. The results indicate that the permissible controller gains can be described by a unique if parameters L and $T_m$ are know.

• Journal of electromagnetic engineering and science
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• 제8권2호
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• pp.64-69
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• 2008

In this paper, we have proposed the pattern adjustable base station antenna for WCDMA applications. The proposed antenna consists of an omni-antenna(sleeve monopole) and two movable reflectors. The two reflectors can be controlled by mechanically and used to adjust the horizontal pattern of the base station antenna. The antenna was designed, fabricated, and measured. The antenna covers the entire WCDMA band for VSWR<1.4. The measured antenna gain is more than 15 dBi over the operating frequency range. By changing the angle (a) and the distance (d) of the antenna, the pattern adjustment of the proposed base station antenna is found to be possible.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.607-612
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• 1998

In this paper, a controller using fuzzy-genetic algorithms is proposed for pat-tracking of WMR. A fuzzy controller is implemented so as to adjust appropriate crossover rate and mutation rate. A genetic algorithms is also implemented to have adaptive adjustment of control gain during optimizing process. To check effectiveness of this algorithms, computer simulation is applied.

• 한국정밀공학회지
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• 제16권1호통권94호
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• pp.265-271
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• 1999

In the feed drive systems or the spindle systems of machine tools that consist of many mechanical components, a torsional vibration is often generated because of its elastic elements in torque transmission-Generally, the accuracy of motion control system is strongly influenced by the dynamic behavior of coupled transmission components Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So, it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed m1d spindle system. In this paper, based on the DC motor model, a model of electro-drive system with motor has been developed and an optimal criterion for tuning the gain of speed controller is discussed. The frequency bandwidth of the system and the damping ratio in time domain are optimal design specifications for the gain adjustment speed controller. The gains of PI speed controller are then derived from the bandwidth and damping ratio, and those relationships have been classified.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권3호
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• pp.891-910
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• 2021

Previous QoS-aware service composition methods mainly focus on how to generate composite service with the optimal QoS efficiently for a single request. However, in the real application scenarios, there are multiple service requests and multiple service providers. It is more important to compose services with suboptimal QoS and maintain the load balance between services. To solve this problem, in this paper, we propose a service composition method, named as dynamically change and balancing composition method (DCBC). It assumes that the QoS of service is not static, and the services can adjust the value of QoS to gain more opportunities to be selected for composition. The method mainly includes two steps, which are the preprocessing step and the service selection step. In the preprocessing step, a backward global best QoS calculation is performed which regarding the static and dynamic QoS respectively; then guided by the global QoS, the feasible services can be selected efficiently in the service selection step. The experiments show that the DCBC method can not only improve the overall quality of composite services but also guarantee the fulfill ratio of requests and the load balance of services.

• 정보처리학회논문지D
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• 제15D권4호
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• pp.451-462
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• 2008

최근 들어, 이동 객체의 위치 정보를 이용한 응용의 등장으로 시공간 데이터베이스를 위한 인덱스 기법의 중요성이 점차 커지고 있다. $TPR^*$-트리는 미래 시간 질의의 효율적인 처리를 위하여 가장 널리 사용되는 인덱스 구조이다. $TPR^*$-트리는 CBR(conservative bounding rectangle)의 개념을 이용하여 이동 객체들의 미래 위치의 범위를 추정하는 방식을 사용한다. 그러나 CBR은 시간이 지남에 따라 지나치게 확대 됨으로써 질의 처리 성능을 크게 저하시키는 문제를 야기시킨다. 본 논문에서는 능동적인 CBR 재조정을 통하여 이러한 CBR의 지나친 확대를 방지하고, 이 결과 $TPR^*$-트리의 질의 처리 성능을 개선할 수 있는 효과적인 기법을 제안한다. 제안한 기법은 질의 처리를 위하여 $TPR^*$-트리의 단말 노드를 액세스한 시점에 CBR 재조정의 필요여부를 점검하도록 함으로써 이러한 점검을 위한 추가적인 디스크 액세스 비용을 요구하지 않는다. 또한, CBR의 재조정이 필요한가의 여부를 판정하기 위하여 재조정을 위한 추가 비용과 향후의 질의 비용을 모두 고려하는 새로운 비용 모델을 정립한다. 제안된 기법을 통하여 갱신이 자주 발생하지 않는 경우에도 CBR의 비정상적인 확대를 방지할 수 있다. 제안된 기법의 성능 개선 효과를 정량적으로 검증하기 위하여 다양한 실험을 수행한다. 실험 결과에 의하면, 제안된 기법은 질의 처리 시 기존 기법과 비교하여 최대 40%이상의 성능 개선 효과를 보인다.