• Journal of Electrical Engineering and Technology
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• 제4권4호
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• pp.451-456
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• 2009

Through the development of phasor measurement units (PMU), various aspects of power system dynamic behavior could be monitored and diagnosed. Monitoring dynamic voltage stability has become one of the achievements we can obtain from PMUs. It is very important to select the most appropriate method for the Korea Electric Power Corporation (KEPCO) system since there are many voltage stability indices. In this paper, we propose an advanced WAVI (Wide Area Voltage Stability) that is well suited for the purposes of monitoring the dynamic voltage stability of KEPCO's PMU installation plan. The salient features of the proposed index are: i) it uses only PMU measurements without coupling with EMS data; ii) it is computationally unburdened and can be applied to real-time situations. The proposed index is applied to the KEPCO test system and the results show that it successfully predicts voltage instability through comparative studies.

• Asian-Australasian Journal of Animal Sciences
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• 제12권4호
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• pp.515-519
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• 1999

With the purpose of determining the influence of sexual partners on the oestrous behaviour and to evaluate the accuracy of predicting the time from implant withdrawal to sexual receptivity following a treatment with Synchromate B (SMB), 15 adult Brahman cows were used in each of three phases. During phase I and n, random pairs of animals were induced to display oestrus one pair after the other at daily intervals, while in phase III, cows were induced alternately, every other day, one cow on the 1st day, two on the 3rd, one on the 5th, two on the 7th until all cows were treated. Sixty six percent of the cows in phases I and II, and 80% in phase III came into oestrous after treatment. The interval between implant withdrawal and, expected and observed oestrous was statistically different in all phases. Clustering of oestrous was evident. Cows displayed sexual receptivity within a. range of -24 to +96; -24 to +72 and -216 to +192 hours after implant withdrawal for the three phases, respectively, with a tendency for cows treated first (within treatments), to delay their oestrus signs and vice versa. In phase III, four cows showed oestrous behaviour with the implant in place. These in spite of not observing pre-ovulatory follicles. Correlation values of 0.99, 0.93 and 0.90 (P<0.05) were found respectively among treatments, between the number of cows coming into oestrus and the number of mounts observed. These findings suggest that there are social and behavioural factors in a herd that may override exogenous synchronisation treatments.

• 한국ITS학회 논문지
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• 제15권6호
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• pp.90-101
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• 2016

본 연구에서는 V2X 통신환경 하에서 개별 차량 기반 수집 데이터를 활용하여 독립교차로의 실시간 교통상황대응 최적 교통신호 제어 알고리즘을 개발하였다. 매초 간격으로 V2X 통신환경에서 수집되는 정보를 이용하여 주기, 현시, 현시 순서를 결정하는 알고리즘과 이 알고리즘 안에서 감응식 신호를 적용하여 독립신호 교차로의 신호 최적제어를 실시하였다. 최적화된 신호시간과 본 연구에서 개발된 알고리즘을 활용한 신호제어 성능을 비교하면 전제적으로 평균 지체, 평균 정지지체, 정지횟수, 평균속도가 개선되었음을 나타나고 있으며, 개선 폭이 교통량이 많아질수록 커지는 것으로 분석되었다. 또한 시장점유율에 따른 도입 시기 평가 결과, 평균 지체의 경우 교통량이 500대의 경우 시장점유율이 50% 이하로 내려가면 본 연구에서 개발된 알고리즘이 기존 신호알고리즘보다 높은 지체를 보였으나, 교통량이 1,000대일 경우 시장 점유율 25% 이하에서 지체가 높아졌다. 하지만 1,500대일 경우 시장점유율에 25%에 불과해도 기존의 신호제어 알고리즘보다 지체가 낮아지는 것으로 분석되었다.