• 스마트미디어저널
• /
• 제9권3호
• /
• pp.80-89
• /
• 2020

Out - of - distribution (OOD) samples are frequently encountered when deploying a classification model in plenty of real-world machine learning-based applications. Those samples are normally sampling far away from the training distribution, but many classifiers still assign them high reliability to belong to one of the training categories. In this study, we address the problem of removing OOD examples by estimating marginal density estimation using variational autoencoder (VAE). We also investigate other proper methods, such as temperature scaling, Gaussian discrimination analysis, and label smoothing. We use Chonnam National University (CNU) weeds dataset as the in - distribution dataset and CIFAR-10, CalTeach as the OOD datasets. Quantitative results show that the proposed framework can reject the OOD test samples with a suitable threshold.

• 조명전기설비학회논문지
• /
• 제29권11호
• /
• pp.66-73
• /
• 2015

AC-based power systems, having the advantages that voltage transformation and long distance transmission are easy, have been constructed since the last 19th century. However, DC-based power system is paid attention these days because of the development of power electronic devices as well as the increase of digital loads and distributed generation. For instance, the transmission systems using High Voltage DC (HVDC) are commercially operated in the world and the researches on distribution system using Low Voltage DC (LVDC) are gradually increased. This paper analyzes voltage sag, resulted from faults, in LVDC distribution system according to the number of poles. Modeling and simulation with various conditions are conducted by using ElectroMagnetic Transients Program (EMTP). Moreover, some countermeasures to reduce voltage sag in LVDC distribution system are suggested briefly.

• 한국산학기술학회논문지
• /
• 제8권5호
• /
• pp.1034-1041
• /
• 2007

본 논문은 저압 감시 기능을 포함하는 개선된 배전자동화시스템 개발에 관한 연구 결과를 소개한 것으로서 연구배경, 시스템 구성, 설계, 시제품 제작, 시험 및 실계통 시범운영 등 전반적인 사항을 설명한다. 개발 시스템은 배전현장에서 별도로 수행 중인 변압기 부하감시, 전압감시 및 정전감시 및 품질감시 업무를 배전자동화시스템에 통합하여 운영함으로써 보다 경제적이고 효율적인 배전망의 운영을 위하여 개발되었다. 시스템 통합을 위한 통신망은 간선망과 지선망을 갖도록 계층적으로 구성하고, 변압기 부하 측의 저압 감시를 위한 단말장치를 새로 개발하였다. 또한, 기존 배전자동화시스템에 저압 감시 기능을 추가하기 위하여 주장치 소프트웨어를 개선하였다. 개발 시스템은 실계통 시범운영을 통하여 설계 및 성능이 검증되었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
• /
• pp.1687-1689
• /
• 2005

In this paper, novel concept of a photovoltaic(PV) power generation system adding the function of active filter(AF) is proposed. Even PV power generation system can be treated to a harmonics source for the power distribution system, it is necessary that the function of AF system in grid connected PV power generation system. Active Filters intended for harmonic solutions are expending their functions from harmonic compensation of nonlinear loads into harmonic isolation between utilities and consumer, and harmonic damping throughout power distribution system. So, the PV system combined the function of AF system can be usefully applied in power distribution system. Here, the control strategy of PV-AF system is introduced.

• 유통과학연구
• /
• 제8권1호
• /
• pp.21-33
• /
• 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.

• 유통과학연구
• /
• 제19권1호
• /
• pp.61-73
• /
• 2021

Purpose: The transition from a traditional to a modern food distribution system induces several adjustments on the supply side since supermarkets must collect food on a larger scale and with higher quality standards. This situation becomes a real challenge for small scale farmers to access supply in a modern distribution channel. This gives rise to an original solution: supplying supermarkets through farmer associations or cooperatives. Based on this context of Vietnam linking to the case of distribution science, the paper proposes an industrial organization model of the food processing system in developing countries. The model presents the competitive relationship between two competing distribution systems: a traditional and a modern one. The former is composed of several retailers that sell their products on the traditional market while the latter is based on cooperatives that collect food and negotiate with supermarkets. The current study is to discuss the conditions under which the evolution of the food distribution system occurs by using the proposed model. Research design, data, and methodology: Based on the proposed model, the study explored the quantity flow from small producers to consumers through a Nash equilibrium and address the question of farmer repartition by a free-entry equilibrium. Results: The result shows that there is a unique positive equilibrium in the food market with participation of cooperative associations; Since farmers serve cooperative associations, they not only receive quantity incentive prices but also share profits within their organization. Conclusions: This study shows a unique distribution equilibrium where the profits of farmers working for middlemen and cooperatives are maximized. Further insights were discussed.

• Journal of Electrical Engineering and Technology
• /
• 제7권4호
• /
• pp.486-492
• /
• 2012

This paper presents a novel objective function for distribution system reconfiguration for reliability enhancement. When islanding operations of distributed generators is prohibited, faults in the feeder interrupt the operation of distributed generators. For this reason, we include the customer interruption cost as well as the distributed generator interruption cost in the objective function in the network reconfiguration algorithm. The network reconfiguration in which genetic algorithms are used is implemented by MATLAB. The effect of the proposed objective function in the network reconfiguration is analyzed and compared with existing objective functions through case studies. The network reconfiguration considering the proposed objective function is suitable for a distribution system that has a high penetration of distributed generators.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -1
• /
• pp.433-436
• /
• 2002

Most of electric distribution utilities have their reliability performance measured by reliability indices such as SAIFI and SAIDI to evaluate customer satisfaction. Adding protective devices in electrical distribution system can increase the system reliability by protecting public customers from local faults. In large-scale distribution system, it is difficult to determine the positions of these protective devices, which can efficiently protect customers within utilities' investment. In this paper, we propose an optimization technique to identify types and positions of protective devices to minimize SAIFI and SAIDI indices according to system requirement constraints.

• 한국자동차공학회논문집
• /
• 제11권6호
• /
• pp.134-140
• /
• 2003

The film sensor is used for measuring pressure distribution at planar area, especially at a small space or gap. The present paper deals with the development of film type sensors and system for pressure distribution measuring. The developed system is consist of (1)film sensor with 40/sup */40 array, (2)PCI interface card with maximum sampling rate of 100㎐, and (3)software for data processing and real-time display. The contact pressure test of wiper blade and front glass of vehicle was performed with wiper blade by 40cm. Generally spring force of wiper arm is designed at 0.7∼1kN. Test results of total force was 9.4N and 7.1N in each driver and passenger toward. The paper suggested possibility for base definition in wiper design. A windshield wiper blade experiment revealed that the system successfully measured the contact force distribution during static state, showing the usefulness of the developed system.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2002년도 학술대회논문집
• /
• pp.139-145
• /
• 2002

Recently, power-electronics equipments or machine that microprocessor is included and computers have been installed continuously in industrial process or region of electronics customer. So concern for power quality, especially sags has been increased. Because those equipments are very sensitive to sags. The sag is phenomenon that magnitude of load voltage temporarily decreases because of power system fault. If a certain equipment in industrial process have any trouble result from sag, it can cause utility to be charged for enormous economics loss. Therefore it need to analyze the characteristic of sag and then mitigation method for sags in distribution system in odor to increase reliability. This paper gives an overview of sags characteristic due to short circuit fault in distribution system and after a general discussion of the various forms mitigation, gives a sags mitigation method with concentrating on changing the distribution system like spot network, on-site generation.