• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.570-576
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• 2010

This paper presents the use of the Petri Net Method for modeling railway tracks. The Petri Net is defined as having the characteristics of a parallel, asynchronous, distributed, inconclusive, statistical, etc. information handling system and is a graphical mathematical modeling tool to study the specifics of active movement. It's proven use can be seen at the Korean type Light Rail testing tracks where they modelled the Petri Net method using the train track encasing the segment, track, turnout, and platform as a singular factor and even though two trains either travelling in the same or opposite directions on a single test track equipped with a sidetrack can travel with the guarantee that the two will not collide.

• Journal of Embryo Transfer
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• v.20 no.3
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• pp.297-302
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• 2005

Artificial insemination (AI) technology has widely applied in domestic animals including cattle for production and preservation of valuable animals. However, AI in goat was poorly studied. We here compared two different estrus synchronization methods, CIDR (controlled intravaginal drug release)+$PGF_2a$ and CIDR+PMSG, in Korean native goats. After treatment of CIDR+$PGF_2a$ or CIDR+PMSG for estrus synchronization, AI was applied to 38 recipients. Of 18 recipients treated with CIDR+$PGF_2a$, 4 recipients produced offsprings. However, no pregnancy was obtained in 20 recipients treated with CIDR+PMSG. Especially, after treatment of CIDR+$PGF_2a$, AI with fresh or frozen sperm showed markedly higher parturition rates than that of CIDR+PMSG. From these results, we suggest that combination of CIDR and $PGF_2a$ could be used as good method for estrus synchronization in Korean native goats.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.43-51
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• 2016

Preventing the forgery and alteration of test reports is important, in order to maintain the reliability of military supplies. Based on a survey of reports on testing institutions and a case study of established electronic document systems in the public sector, we propose a system architecture, which helps prevent the forgery and alteration of test reports with legal force. The proposed architecture takes advantage of both the time stamp that records the time a document is received and a server synchronized with the testing institution. Using the proposed system architecture, the user is able to request a test and receive reports from the testing institution without delay. Also, a defense agency is able to conveniently prove the authenticity of the test reports and utilize the statistical data collected by the architecture. Therefore, we expect that the proposed system architecture will help defense agencies to prevent the forgery and alteration of test reports and ensure their reliability and quality.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.153-160
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• 2019

Electro-mechanical actuator system for aircraft has advantages in compactness and its lightweight, compared to the hydraulic actuator system. Hinge line actuator has low air resistance and is suitable for special purpose such as stealth. This paper describes design contents of 10,000 lbf-in class dual redundant hinge line electro-mechanical actuator system for performance test. The control structure was designed to minimize impact of torque fighting. A mathematical model is proposed to analyze and validate the performances of actuator by comparison with experiment results.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.491-499
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• 1999

This paper is on the high perfonnance propulsion IGBT VVVF inverter adopted new technique for railways. To prove the high performance and stabilit~r of traction, running tests are carried out under the simulated condition alike real field. The tests are perfonned on not only a steady states but also a transient states such a as input voltage variation using inertia load equivalent to 160tons train. The vector control technique is a adopted to improve traction for 4 motors. The low switching synchronous PW1\l method based on a space v voltage vector modulation is pro\XlSed as the optimal method for propulsion system railway. The output voltage l is controlled continuously to six step by prolxlsed ovennodu]ation technique without sudden torque variation.

• Journal of The Korean Association For Science Education
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• v.25 no.5
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• pp.547-554
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• 2005

A developed Web-aided laboratory program visualized invisible gas. In the Web-aided laboratory temperature and pressure were controlled and the resultant findings were presented as types of graphs, disclosed in the form of an analyzed report. A Web-aided laboratory experiment and traditional experiment group(2 classes) were assembled from a farming village co-educational high school and taught the motion of molecule lesson for 2 class hours. Before actual class instruction, to survey learner motivation characteristics, the short-version GALT, the test of attitudes toward science instruction, was administered. After instruction, student learning achievement, TOSRA, and IMMS, were administered to the two groups. To analyze data ANCOVA was administrated. Result found that attitudes towards science instruction did not significantly differ, but learning motivation and achievement were significantly altered.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.620-627
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• 2004

As h-bridge multilevel inverter is connected with series of single phase power cell, so it obtain high voltage using low voltage power semi-conductor and output voltage similar to sine wave. In this topology, the number of power cell increases in proportion to the output voltage level. Therefore, there are drawbacks that are responsibility against operating ability of main controller and signal wire increase. However, we can overcome this problems by the substitution of serial communication for the PWM signal in power cell control. Additionally, it has merits of reliability and maintenance. This paper deals with the synchronization and phase-shift method of power cell PWM using CAN(Controller Area Network) communication interrupt in H-bridge multilevel inverter. The advantages of proposed method are signal-line simplification using serial communication between main controller and cell controller, burden reduction in main controller, modularization of power cell, easy protection of each power cell, expandability improvement and reliability increase of control signal and power cell. This paper establishes propriety and reliability of proposed method through experiment of 13-level H-bridge multilevel inverter.

• Reproductive and Developmental Biology
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• v.30 no.3
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• pp.225-228
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• 2006

This study was undertaken to investigate the effect of ovulation-synchronization(OVSYNCH) method on conception rate after insemination of dairy cattle. The proportion of conception of normal fertility cows(65%) was higher than that in infertility cows(50%) in dairy cows with OVSYNCH treatment. However, there was no significant difference between experimental groups. In another experiment, when the OVSYNCH method was adapted in multiparous dairy cows, the conception rate of experimental group of $30{\sim}35kg/day$ in milk yield was significantly higher than those in groups of $20{\sim}25kg/day$ in milk yield(p<0.05). In conception rates by OVSYNCH method in experimental groups with different parity, the group of 1st parity was significantly higher than in 3rd parity group(p<0.05). The results suggest that conception rate by OVSYNCH method was affected by various reproductive conditions in dairy cattle, and OVSYNCH method could be used to increase the conception rate for infertility cows with hormone disorder.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.35-35
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• 2001

본 연구는 수정란이식기법에 의해 우량 한우 송아지를 대량 생산할 수 있는 기반조성을 위한 한우 수정란이식 최적모델을 개발하기 위해 실시되었다. 본 시험에 공시된 수정란은 우량한 한우의 체내수정란 및 체외수정란을 생산하여 좋은 배반포 수정란을 신선 혹은 동결란 상태로 이식에 공시하였다. 수란우는 정상 발정주기를 가진 경산우로 CIDR을 이용하여 발정을 동기화 하였고 이식시 직장검사로 황체의 크기를 검사하고 초음파진단기로 황체의 구조를 조사하여 정상인 개체에 수정란을 이식하였다. 수란우의 최적 선정조건을 구명하고자 혈중 호르몬 및 대사물질을 분석하였으며 얻어진 결과는 다음과 같다. 1. 총 397두의 수란우에 수정란을 이식하여 121두가 임신하여 평균 30.5%의 수태율을 얻었다. 2. 수란우의 황체의 크기 및 황체내 강 형성 유무와 수태율간에는 차이가 없었으나 혈중 progesterone 수준을 분석해 본 결과, progesterone 수준이 2.0 ng/$m\ell$ 이상일 경우 수태율이 46.6%로 높게 나타났다. 3. 수란우의 혈중 Total cholesterol은 90~110mg/㎗, BUN은 14~16 mg/㎗, Glucose 수준은 70~80 mg/㎗에서 가장 높은 수태율을 나타내어 이들 혈중 대사물질이 수태율에 영향을 미치는 것으로 나타났다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.667-668
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• 2008

현대 산업사회의 특징은 대용량화와 고속화에 있다. 전력부분에 있어서도 예외는 아니어서 초고층빌딩, 대단지 아파트, 공장, 위락시설, 병원 등 대용량 전력부하가 급격한 속도로 증가하고 있다. 특히 전력부분에 있어서는 대용량화와 동시에 경량 및 부피감소의 요구가 증대되면서도 신뢰성 높은 전력 품질 또한 요구되고 있다. 전기안전의 측면에 있어서 발전소의 안전불량은 전력수용가의 수급 차질로 인한 데이터 전산망, 생산설비의 막대한 재산 피해 뿐 아니라 병원 등에서의 인명피해도 발생시킬 수 있으므로 이에 대한 대책이 꼭 강구되어야 한다. 본 논문은 소용량 2극 동기발전기의 공극자속 파형 특성연구를 통하여 발전기 회전자 권선의 단락고장진단을 위한 예측진단기술을 개발하는 과정의 일환으로 진행되었으며 우선 정상상태의 공극자속을 컴퓨터 시뮬레이션 방법으로 계산하고 이를 시험치와 비교하여 해석 결과의 신뢰성을 평가하였다. 본 연구의 결과를 바탕으로 발전기의 모의 고장으로 발생하는 공극 자속의 특성을 연구하여 발전설비의 안전 확대에 기여할 것이다.