• 한국산학기술학회논문지
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• 제1권2호
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• pp.41-48
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• 2000

최근 산업현장의 모든 부분에서 자동화의 요구가 급격하게 증가되고 있다. 지금까지의 사격장 시스템은 정적인 환경을 중심으로 설계되어져 왔다. 그러나, 실제의 사격상황은 목표물이 동적이므로 다른 사격 환경 변화가 요구된다. 본 연구에서는 동적인 사격환경을 구현하기 위해 1개 사로에 4대의 타겟을 설치하여 사격순서를 순차 및 비순차로 구분하고 사격시간을 가변적으로 조정할 수 있게 하였다. 그리고. 자동차 및 빌딩 자동화에 많이 응용되고 있는 CAN(Controller Area Network)을 이용함으로써 효율적인 통신을 가능하게 하였다. CAN은 높은 데이터 전송률과 안정성을 제공할 수 있어 다수의 ECU(Electric Control Unit)를 상호 연결하여 분산된 실시간 제어를 효율적으로 지원할 수 있다.

• 조명전기설비학회논문지
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• 제25권10호
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• pp.59-66
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• 2011

In electric power system, the circuit breaker is not operated when the higher voltage then the rated TRV(transient Recovery Voltage) appeared in the circuit breaking, The TRV of a circuit breaker means the characteristics of reignition by the arc between two poles. and is decided by the value of connecting Impedance. In this paper we of carried out many kinds of experiments varying the types of bus, the types of installation, the length of installation between 22.9 [kV] level circuit breaker and MTR in general 154/22.9[kV] system, We also simulated the characteristics of TRV using EMTP-RV program. The suitability of TRV in assessed by Uc, RRRV(Rate of Rise of Recovery Voltage) which are defined by the international guide, IEC62271-100. The values of RRRV gained from the cable-made bus are 590[%] lesser than those from the NSPB-made bus respectively. So the triangled type is more rational in the aspect of TRV.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.79-82
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• 2002

The addition of switches to a distribution feeder does, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder. To cover its service area so that feeder-level delivery reaches sufficiently close to all customers, feeders typically split their routes many times, in what is often called a lateral feeder. It is interesting to note, however, that the effectiveness of a switch is very much dependent on the types of lateral feeder. The types of lateral are classified into two types. The first is loop lateral feeder that can connect its load to an adjacent feeder through a tie line in case that a fault occurs in its feeder and it is laid out so that every feeder has complete fault backup through re-switching of its loads to other sources like a main feeder. The second is the radial lateral feeder cannot connect its load to an adjacent line, no provision is made for contingency backup of feeders. There are no other circuits in the radial lateral feeder form which to restore power. In this study, we evaluate the effectiveness of a switch installation between on the radial and loop lateral feeders to increase reliability by decreasing the duration of the outage. These results can help power utility to design the switch layouts on the radial and loop lateral feeder system.

• The Korean Journal of Ecology
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• 제20권4호
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• pp.265-274
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• 1997

All landscapes are mosaics of habitat patches of different types. Therefore, there are always edged between habitat patches in a landscape. Forest animal has an important role in vegetation development and maintenance by seed dispersal around forest. Movement of animals depends on the spatially heterogeneous structure and pattern of vegetation landscapes because each animal has special habitats in a landscape. Especially, forast edge with high permeability and prey density is one of the important habitats to the animals. Therefore, understanding the ecological characteristics of the forest edges as a corridor connecting mosaic vegetation patches is necessa교 새 establish the strategies for the nature conservation and sustainable vegetation management. Under this idea, we examined the animal influenced on pine seeds as one of the method of monitoring the animal activity in mosaic vegetation. Man-made mosaic vegetations including open, edge and inner forests were carefully selected in the rural landscape. We carried out predation test on pine seeds during one year. A result was that damages on seed was more significant at forest edge than inner and open forest. Pine seed on seedbeds was mainly attacked by squirrels and mice than birds. Pine seed was damaged by squirrels in different types of vegetation by seasons. Rate of seed predation at forest edge was, in special, higher than that of other sites. According to this results, it is suggested that the relationship between animal behavior and spatial vegetation structure relating to human impact such as the distance from settlement to vegetation appeares to be in the rural vegetation landscape.

• 전자공학회논문지C
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• 제35C권12호
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• pp.77-84
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• 1998

0.8㎛ single poly CMOS 공정을 이용하여 집적화 된 전압제어형 카오스 발생회로를 설계, 제작하였다. 제작된 카오스 집적회로는 비선형함수 발생회로와 op-amp, 2상 클럭발생회로, 2개의 샘플&홀드 회로 등으로 이루어진다. 측정결과 ±2.5V 전원, 20kHz의 클럭 인가시 입력제어전압에 따라 주기상태, 준주기 상태, 카오스 상태 등 다양한 형태의 분기현상 및 시계열 파형을 관측할 수 있었다. 또한 이 회로의 직렬, 병렬 연결에 의한 2차원 카오스 패턴도 관측하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.989-996
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• 2008

Recently, a few types of fish-cage in open sea are researched. This fish-cage has to operate monitoring system for keeping an optimum living condition for fish. The most efficient monitoring system is WVMS(Wireless Vision Monitoring System) for fish-cage in open sea. WVMS should be able to transmit video signal and communicate with each controller. So. it needs to be based on WLAN(Wireless LAN) which has characteristic of higher transfer-rate, In this paper, we propose a structure of WVMS using WLAN equipments for maritime environment and prove its effectiveness. We present the propagation loss model of WVMS's communication channel. measured by field test, and discuss its validity compared with the predictive value based on the Friss propagation model and Plane earth reflection model. We present the number of frames that is received from WLAN modem connecting with underwater-camera in field test spots. As a result, we confirmed that proposed WVMS is suitable for maritime environment and it is possible to be applied to fish-cage in open sea on 'seogwipo'.

• 한국식품영양학회지
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• 제22권1호
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• pp.57-62
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• 2009

The current exploratory study attempted to investigate the levels of expected and perceived service quality of in-flight meals. A questionnaire was developed following extensive literature review and in-depth interviews. The survey was conducted on board a flight by international passengers and also by passengers in the trans lounge waiting for connecting flights between October 21, 2005 through October 30, 2005. Out of the 450 questionnaires administered, a total of 319 completed questionnaires were returned, yielding a response rate of 89.6%. The 20 items representing the service quality factor of in-flight meals were analyzed, resulting in four distinct dimensions-food quality, employee service, cleanliness and reliability. In all dimensions, customer expectation was higher than the perceived level of service and the service quality of Korean based airlines was higher than that compared to foreign based airlines. There were differences in the perceived service quality of in-flight meals according to the demographics of the respondents. The results of this study can be beneficial from a theoretical and practical point of view by providing empirical data that measures the service quality of in-flight meals.

• 대한전기학회논문지:전력기술부문A
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• 제51권6호
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• pp.290-295
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• 2002

The present assignment in installing the number of switches for distribution line was made on the basis of a normal feeder capacity 7,000kVA in KEPCO(Korea Electric Power Corporation), Korea. But the normal capacity is revised to 10000kVA in 1998. Even increasing limit of the operating capacity of the distribution lines enables us to give some benefit for the operation flexibility and investment cost of the distribution system. It is disadvantageous in the viewpoint of supply reliability. In distribution systems, switches are equipped to improve the reliability of distribution systems by minimizing the outage section due to fault and maintenance. Utility generally improves the reliability by minimizing the length of outage section, which is caused by fault and maintenance, through switch equipment on distribution system. In order to cope with the changes such as operation capacity, it is necessary to study whether the present criteria is reasonable or not, also to confirm whether the present criteria of installing switches in line is improved or not. In this study, we proposes the number of switch per feeder on the basis of present operation capacity in distribution system.

• 한국생산제조학회지
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• 제24권6호
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• pp.599-604
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• 2015

Currently, the coolant system in industrial sites is an efficient process to keep clean cutting oils. However, the damage to a pump occurs due to a chip and debris when inhaled into the pump, and thus problems such as the reduction of both efficiency and lifespan might arise. In this study, a new type of filter was developed in order to primarily prevent the damage from the pump impeller and make it unnecessary to have the replacement and cleaning at the same time. This study found the problem reducing the suction volumetric efficiency and cavitation when inhaled, and conducted a method to solve the problem compared to the result of fluid analysis according to two velocity conditions. As a result, this study achieved the effect of lowering the pressure and meeting the suction flow rate by connecting the four filters.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권9호
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• pp.3377-3395
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• 2015

Recently, several approaches to share road conditions and/or digital contents through VANETs have been proposed, and such approaches have generally considered the radial distance from the information source as well as the TTL to provision an ephemeral, geographically-limited information sharing service. However, they implement general MANETs and have not been tailored to the constrained movement of vehicles on roads that are mostly linear. In this paper, we propose a novel application-level mechanism that can be used to share road conditions, including accidents, detours and congestion, through a VANET. We assign probabilities to roads around each of the intersections in the neighborhood road network. We then use the graph representation of the road network to build a spanning tree of roads with the information source as the root node. Nodes below the root represent junctions, and the edges represent inter-connecting road segments. Messages propagate along the branches of the tree, and as the information propagates down the branches, the probability of replication decreases. The information is replicated until a threshold probability has been reached, and our method also ensures that messages are not delivered to irrelevant vehicles, independently of their proximity to the source. We evaluated the success rate and performance of this approach using NS-3 simulations, and we used IDM car following and MOBIL lane change models to provide realistic modeling of the vehicle mobility.