• 한국정보전자통신기술학회논문지
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• 제9권2호
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• pp.243-247
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• 2016

본 논문은 급가속, 급 감속, 급제동, 급출발, 그리고 과속 등과 같은 여러 운행 이벤트 데이터는 운전자의 운행습관과 운전자의 사고위험성을 예측 또는 분석하는데 중요한 정보를 제공한다. 일반적인 자료의 분포는 정규분포, 로그정규분포, 감마분포 등을 이용하지만 운전자 운행습관을 나타내는 자료에서 사고위험성을 추정 할 수 있는 극단적인 부분에서는 언급한 분포로 적합하지 않은 경우가 발생한다. 특히 왜도가 발생하여 정규분포에 적합하지 않은 영역이 생겨난다. 본 논문에서는 이 영역에서 적합한 분포 함수와 사고를 유발하는 위험군을 분리 할 수 있고 운전자 운행 시 사전경고로 사고율을 줄 일수 있는 임계점을 분포함수의 quantile값과 군집분석 결과와 비교하여 제시하였다.

• 유통과학연구
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• 제8권1호
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• pp.21-33
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• 2010

인터넷과 모바일기술의 발전은 화훼유통서비스를 급격히 진화시켰을 뿐만 아니라, 화훼 도소매점간 경쟁방식과 유통경로에도 많은 변화를 가져왔다. 인터넷과 정보기술의 발전은 화훼 유통경로에 있는 중개상들의 힘(영향력)이 축소되거나 일부 소멸할 것으로 예상했다. 그러나 오히려 중개기능의 강화되었고 정보시스템을 통해 유통서비스의 지역적 한계가 없어지고 매출증가로 점포규모가 커지고 협회와 같은 중개자가 재출현하게 되었다. 본 연구는 화훼중도매인이 도소매점의 활동을 원활하게 지원하기 위해 지금까지 어떤 노력들이 있었고 정보시스템 도입 실패원인에 대해 살펴보았다. 그리고 유통경로에서 힘(영향력)의 우위를 확보하기 위해 유통 중간상이 어떻게 변화하고 있는지를 (주)플로마켓 사례를 통해 살펴보았다. 연구결과 화훼도매점들이 정보시스템을 활용한 유통경로 혁신을 시도하였지만 매출채권 및 상품재고 관리를 위한 기능을 정보시스템에 미반영, 거래 및 업무 프로세스 확립 없이 자동화 개념으로 도입, 정보시스템 가동이후 노력을 고려한 정보시스템 구축전략 미비, 화훼소매점과 유통 및 제품정보 공유 없이 주문처리 중심의 정보시스템 구축 등 4가지 이유로 구축에 실패한 것으로 파악되었다. 파악된 실패요인들을 고려하여 (주)플로마켓은 정보시스템을 통해 화훼공판장과 화훼도소매시장으로 구분되어 있는 도매유통시장을 통합하여 고품질의 상품을 확보할 수 있도록 유통경로 개선을 하고자 했다. 시스템구축 후 운영되면서 (주)플로마켓은 상품재고 최소화와 다품종 대량구매를 실현 할 수 있었고 사전주문 프로세스와 사후 재정산을 통하여 실시간 시세를 반영한 상품공급으로 고객의 신뢰를 확보할 수 있었다. 단계별 비즈니스에 맞는 정보시스템 구축전략으로 급변하는 비즈니스 환경에 대처할 수 있도록 정보시스템을 구축하였다. (주)플로마켓의 성공여부는 화훼도매시장에서 화훼소매점과 도매점들이 얼마나 참여하느냐에 달려있기 때문에 시간을 가지고 지켜봐야 하지만 (주)플로마켓 주문처리 시스템의 등장은 거래자간 정보흐름이 끊김 없이 실시간으로 유통정보 및 상품정보 교환이 되고, 제품 표준화와 거래 프로세스가 명확해지고, 정보시스템을 통해 화훼도매점은 유통정보, 거래정보, 상품정보 등 마케팅 정보 수집이 가능해서 전략적 의사결정을 내릴 수 있을 것이다. 따라서 그 동안 정보화 수준이 낮은 화훼유통시장에서 거래의 효율성을 높인 유통경로개선 사례로 본 논문의 의의가 있다고 할 것이다.

• 전기학회논문지
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• 제65권5호
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• pp.753-759
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• 2016

Power automation system to operate power distribution systems can be distinguished by distribution SCADA with remote monitoring and control; and distribution automation system with basic functions such as service restoration to the distribution SCADA; and distribution management system which is operated by various applications in order to enhance distribution system operation performance based on the distribution automation system. In the technological change, a technical boundary of information technology (IT) and operation technology (OT) is being blurred by that new concepts such as interoperability. In addtion, IT/OT convergence has been proposed by the improvement of ICT and power system technology. At the viewpoint, advanced distribution management system (ADMS) to have the new concepts and to increase distribution system operation efficiency through global information and functions from the other systems has been proposed. In order to implement the ADMS, IT and OT have to be employed together on the ADMS; and the concept-based IT/OT convergence concept has been presented. Therefore, this paper introduces ADMS and IT/OT convergence and proposes a design of IT/OT convergence based ADMS system design with configurations and functions.

• Journal of Communications and Networks
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• 제7권4호
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• pp.438-449
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• 2005

In this paper, we describes the information-theoretic approaches to sensor selection and sensor placement in sensor net­works for target localization and tracking. We have developed a sensor selection heuristic to activate the most informative candidate sensor for collaborative target localization and tracking. The fusion of the observation by the selected sensor with the prior target location distribution yields nearly the greatest reduction of the entropy of the expected posterior target location distribution. Our sensor selection heuristic is computationally less complex and thus more suitable to sensor networks with moderate computing power than the mutual information sensor selection criteria. We have also developed a method to compute the posterior target location distribution with the minimum entropy that could be achieved by the fusion of observations of the sensor network with a given deployment geometry. We have found that the covariance matrix of the posterior target location distribution with the minimum entropy is consistent with the Cramer-Rao lower bound (CRB) of the target location estimate. Using the minimum entropy of the posterior target location distribution, we have characterized the effect of the sensor placement geometry on the localization accuracy.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.102-108
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• 2015

This paper proposes a new fault isolation methodology for a smart protective device which plays an agent role on the smart grid distribution system with the distributed generation. It, by itself, determines accurately whether its protection zone is fault or not, identifies the fault zone and separates the fault zone through the exchange of fault information such as the current information and the voltage information with other protective devices using bi-directional communication capabilities on the smart grid distribution system. The heuristic rules are obtained from the structure and electrical characteristics determined according to the location of the fault and DG (Distributed Generation) when faults such as single-phase ground fault, phase-to-phase short fault and three-phase short fault occur on the smart grid distribution system with DG.

• 한국컴퓨터정보학회논문지
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• 제21권10호
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• pp.77-83
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• 2016

To verify the trustworthiness of messages, public key certificates and certificate revocation list(CRL) has been standardized for vehicular networks. However, timely distribution of large CRLs to vehicles should be more elaborated with low bandwidth utilization from a practical point of view. To address this concern, we propose a CRL distribution scheme using long term evolution(LTE) point-to-multicast transmission, namely the enhanced multimedia broadcast multicast service(eMBMS). The schem is much more resource efficient than the existing unicast CRL distribution schemes for vehicular networks and it allows realizing the regional CRL distribution schemes efficiently in LTE network. By means of ns-3 simulation, we analyze the performance, latency, and execution time of the scheme in terms of varying coverage of the multimedia broadcast multicast service over single frequency network (MBFSN).

• Journal of information and communication convergence engineering
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• 제12권2호
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• pp.75-82
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• 2014

Dispersion management (DM), optical phase conjugation (OPC), and the combination of DM and OPC are promising techniques to compensate for optical signal distortion due to group velocity dispersion and nonlinear Kerr effects. The system performance improvement in DM links combined with OPC has been reported; however, the fixed residual dispersion per span (RDPS) usually used in these links restricts the flexibility of link configuration. Thus, in this paper, a flexible optical link configuration with artificially distributed single-mode fiber (SMF) lengths and RDPS in the combination of DM and OPC is proposed. Simulation results show that the best artificial distribution pattern is the gradually descending distribution of SMF lengths and the gradually ascending distribution of RDPS, as the number of fiber spans is increased, regardless of the average RDPS, the optimal net residual dispersion, and the dispersion coefficient of the dispersion compensating fiber.

• 한국신뢰성학회지:신뢰성응용연구
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• 제2권2호
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• pp.63-83
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• 2002

Degradation data can provide more reliability information than traditional failure-time data, especially products with few or no failures. This paper is concerned with a method of estimating lifetime distribution from field data with supplementary information on degradation data and covariates. When a distribution of degradation rate obtained by follow-up study for a portion of products that survive after-warranty follows a reciprocal-Weibull or lognormal distribution. A time-to-failure distribution of the product follows Weibull or lognormal distribution, respectively. A method of estimating lifetime parameters for this kind of data and their asymptotic properties are studied. Effects of after-warranty report probability, follow-up rate, and proportion of degradation data on pseudo maximum likelihood estimators of these parameters are investigated.

• 산업공학
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• 제21권2호
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• pp.151-160
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• 2008

Defect size distribution is a probability density function for the defects that occur on wafers or glasses during semiconductor/LCD fabrication. It is one of the most important information to estimate manufacturing yield using well-known statistical estimation methods. The defects are detected by automatic optical inspection (AOI) facilities. However, the data that is provided from AOI is not accurate due to resolution of AOI and its defect detection mechanism. It causes distortion of defect size distribution and results in wrong estimation of the manufacturing yield. In this paper, I suggest a size conversion method and a maximum likelihood estimator to overcome the vague defect size information of AOI. The methods are verified by the Monte Carlo simulation that is constructed as similar as real situation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.371-373
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• 2001

In this paper, we present 2-step load cycle for daily load curve of up to and including 100kVA distribution transformer in domestic. Daily load patterns are classified by two methods dependent upon possession information. In case we possess daily load profiles make use of K-mean algorithm and in case we have not daily load profiles, make use of customer information of KEPCO. As the parameters of the load pattern classification, we use are daily load profiles and customer information of each distribution transformers. Data management system is used for NT oracle. We can present peak load magnitude, initial load magnitude and peak load duration for daily load patterns by 2-step load cycle for daily load curve of up to and including 100kVA distribution transformer in domestic. We think that this paper contributes to enhancing the distribution transformer overload criterion.