• 조명전기설비학회논문지
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• 제27권7호
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• pp.37-44
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• 2013

Phase to ground faults are possibly one of the maximum number of faults in power distribution system. During a ground fault the maximum fault current and neutral to ground voltage will appear at the pole nearest to the fault. Distribution lines are consisted of three phase conductors, an overhead ground wire and a multigrounded neutral line. In this paper phase to neutral faults were staged at the specified concrete pole along the distribution line and measured the ground fault current distribution in the ground fault current, three poles nearest to the fault point, overhead ground wire and neutral line. A simplified equivalent circuit model for the distribution system under case study calculated by using MATLAB gives results very close to the ground fault current distribution yielded by field tests.

• 컴퓨터교육학회논문지
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• 제21권1호
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• pp.51-58
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• 2018

인공 신경망은 최근 다양한 분야에서 뛰어난 성능을 보여주고 있다. 하지만 인공 신경망이 학습한 지식이 정확히 어떤 내용인지를 사람이 파악하기 어렵다는 문제점이 존재하는데, 이를 해결하기 위한 방법 중 하나로 학습된 인공 신경망에서 규칙을 추출하는 방법들이 연구되고 있다. 본 연구에서는 학습된 인공 신경망으로부터 규칙을 추출하는 방법 중 하나인 ordered-attribute search(OAS) 알고리즘을 사용하여 인공 신경망으로부터 규칙을 추출해보고, 추출된 규칙을 개선하기 위해 규칙들을 분석하였다. 그 결과로 은닉 층의 출력값 분포가 OAS 알고리즘을 이용해 추출된 규칙의 정확도에 영향을 주는 것을 파악하였고, 은닉 유닛 명확화 기법을 통해 은닉 층 출력값을 이진화하여 효율적인 규칙을 추출할 수 있음을 제시하였다.

• 한국환경보건학회지
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• 제33권4호
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• pp.299-305
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• 2007

Distribution of fecal pollution indicator bacteria and environmental parameter were investigated of urban artificial lakes. An average concentration of temperature, pH, SS, DO, $COD_{Mn}$, T-P, T-N, Turbidity, Chl-a were $21.5^{\circ}C$, 8.07, 116.70 mg/l, 8.66 mg/l, 2.24 mg/1, 0.52 mg/l, 1.71mg/l, 80.54 NTU, and 52.12 mg/l respectively. From the results of bivariate correlation analysis, fecal contamination indicator bacteria were found to be mutually correlated. And turbidity and suspended solid were correlated. From the results of principal component analysis, four factors were extracted. And four factors of variance explained up to 81.5 percentage. Factor 1 was pollution pattern by fecal contamination, factor 2 was physical pollution pattern by pollution source, factor 3 was natural pollution by precipitation, and factor 4 was artificial pollution pattern by organism.

• 한국수산과학회지
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• 제40권1호
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• pp.31-38
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• 2007

This study investigated the fluid force acting on an artificial reef and the scour pattern at the bottom of the artificial reef in a steady-flow field using the finite difference method (Flow-3D). The structure was tetragonal in shape, like similar objects found in nature. The numerical analysis showed that the hydrodynamic characteristics and incipient scouring pattern matched natural phenomena. The velocity distribution around the tetragon was symmetric and wake occurred inside the tetragon and behind the bottom of the tetragon. The length of the recirculation flow behind the tetragon for each velocity was about 4-5 cm and the magnitude of the recirculation flow inside the tetragon generally increased with the Reynolds' number, although it decreased slightly for Reynolds' numbers from 11,000 to 12,000. In addition, the total fluid force acting on the tetragon increased with the inflow velocity, although the increment was smaller when the velocity exceed 18 cm/sec. The incipient pattern for the scouring of sediment matched the natural phenomenon.

• 조명전기설비학회논문지
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• 제21권1호
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• pp.1-9
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• 2007

본 연구는 실내로 유입되는 주광을 조광제어시스템의 적용에 효율적으로 활용하여 초과한 인공조명의 광량을 줄임으로써 에너지 절약의 효과를 높이고자 함이다. 광센서는 탐지된 광속량을 신호로 보내고 그에 알맞은 제어신호를 받아 조광율을 결정하는데, 일반적으로 사무공간에서 인공조명의 개수나 행수만큼 광센서가 설치가 되어 조명기구의 각 구역마다 다른 조광율로 조광제어를 하는 것이 인공조명 제어측면에서는 효율적이나, 시스템 설치비용측면에서는 비효율적이다. 그러므로 실험과 시뮬레이션을 통하여 미리 유입되는 주광 분포를 파악하고 조광율을 분석한다면, 하나의 광센서 설치로써 인공조명 구역간의 각기 다른 조광율로 제어가능하다.

• Wind and Structures
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• 제20권2호
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• pp.169-189
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• 2015

To investigate the effects of "sudden change" of wind fluctuations on vehicle running performance, which is caused by the artificial discrete simulation of wind field, a three-dimensional vehicle model is set up with multi-body dynamics theory and the vehicle dynamic responses in crosswind conditions are obtained in time domain. Based on Hilbert Huang Transform, the effects of simulation separations on time-frequency characteristics of wind field are discussed. In addition, the probability density distribution of "sudden change" of wind fluctuations is displayed, addressing the effects of simulation separation, mean wind speed and vehicle speed on the "sudden change" of wind fluctuations. The "sudden change" of vehicle dynamic responses, which is due to the discontinuity of wind fluctuations on moving vehicle, is also analyzed. With Principal Component Analysis, the comprehensive evaluation of vehicle running performance in crosswind conditions at different simulation separations of wind field is investigated. The results demonstrate that the artificial discrete simulation of wind field often causes "sudden change" in the wind fluctuations and the corresponding vehicle dynamic responses are noticeably affected. It provides a theoretical foundation for the choice of a suitable simulation separation of wind field in engineering application.

• International Journal of Industrial Entomology and Biomaterials
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• 제21권2호
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• pp.189-191
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• 2010

The black soldier fly, Hermetia illucens, has a worldwide distribution in the tropics and warm temperate regions and is active in the Korea from May through October. This species colonize a wide variety of decomposing vegetable and animal matter and oviposits in a variety of decomposing materials. In this study, how the black soldier fly pupation, adult emergence and mating rate changed with season at the artificial rearing system was investigated. The black soldier fly larvae and pupae were reared under laboratory condition ($27^{\circ}C$, 60% R.H.). In this study, under the laboratory condition, pupation and adult emergence were not influenced by season, but the data shows definitely different mating numbers throughout whole year. The time of the day is changed with seasons and it influence to mating on artificial rearing. To culture the black soldier fly throughout the year in Korea needs a more deep study under the artificial rearing system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.2948-2963
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• 2015

In the field of computer vision, visual surveillance systems have recently become an important research topic. Growth in this area is being driven by both the increase in the availability of inexpensive computing devices and image sensors as well as the general inefficiency of manual surveillance and monitoring. In particular, the ultimate goal for many visual surveillance systems is to provide automatic activity recognition for events at a given site. A higher level of understanding of these activities requires certain lower-level computer vision tasks to be performed. So in this paper, we propose an intelligent activity recognition model that uses a structure learning method and a classification method. The structure learning method is provided as a K2-learning algorithm that generates Bayesian networks of causal relationships between sensors for a given activity. The statistical characteristics of the sensor values and the topological characteristics of the generated graphs are learned for each activity, and then a neural network is designed to classify the current activity according to the features extracted from the multiple sensor values that have been collected. Finally, the proposed method is implemented and tested by using PETS2013 benchmark data.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.964-966
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• 2015

분산 제어 (DM; dispersion management)와 광 위상 공액기 (OPC; optical phase conjugator)가 적용된 광전송 링크에서 송신단부터 OPC까지 중계 구간이 증가할수록 단일 모드 광섬유 (SMF; single mode fiber)의 길이와 중계 구간 당 잉여 분산 (RDPS; residual dispersion per span)은 감소하고, OPC부터 수신단까지는 중계 구간이 증가할수록 SMF 길이와 RDPS가 증가하는 분포에서 인접 중계 구간과의 SMF 길이와 RDPS 편차가 WDM 신호의 보상에 미치는 영향을 살펴보았다.

• 로봇학회논문지
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• 제14권2호
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• pp.94-103
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• 2019

The optimal grasping point of the object varies depending on the shape of the object, such as the weight, the material, the grasping contact with the robot hand, and the grasping force. In order to derive the optimal grasping points for each object by a three fingered robot hand, optimal point and posture have been derived based on the geometry of the object and the hand using the artificial neural network. The optimal grasping cost function has been derived by constructing the cost function based on the probability density function of the normal distribution. Considering the characteristics of the object and the robot hand, the optimum height and width have been set to grasp the object by the robot hand. The resultant force between the contact area of the robot finger and the object has been estimated from the grasping force of the robot finger and the gravitational force of the object. In addition to these, the geometrical and gravitational center points of the object have been considered in obtaining the optimum grasping position of the robot finger and the object using the artificial neural network. To show the effectiveness of the proposed algorithm, the friction cone for the stable grasping operation has been modeled through the grasping experiments.