• 상하수도학회지
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• 제21권5호
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• pp.609-619
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• 2007

The objective of this paper is to evaluate the feasibility of conjunctive Operation between Multi-regional water supply networks from multiple source as a effective way to meet two conditions: to minimize the electric cost for providing water demanded and meet the water flow rate for satisfying customers. EPAnet Model is used to calculate a hydraulic water distribution condition based on an integrated operation of water supply systems located in short distance. The modeling was conducted on several simulation cases including the individual operation by existing inter-regional water supply networks within short distance, the conjunctive operation of more than two existing networks with valve fully closed and full open constraint. As a study distribution system, water supplying systems of the Geojae-city in the Geongsang Namdo Province was selected and investigated. It was found that a well-allocated water supply scheme based on a conjunctive operation promises to save the electric cost and satisfy all operational goals such as stability and revenues during the period. The result such as unit district costs, pareto optimum pump combination sets will be applied to the optimization for a conjunctive operation of existing inter-regional water supply networks within short distance.

• 한국전기전자재료학회논문지
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• 제22권12호
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• pp.1073-1077
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• 2009

The iron core, which comprises the superconducting fault current limiter (SFCL) using magnetic coupling of coils, can be operated in the saturation region, especially at the initial fault period. This operation of the iron core in the saturation region deteriorates the fault current limiting operation of the SFCL. To solve the saturation problem of the SFCL using magnetic coupling of coils, the iron core with two magnetic paths, which has an air-gap in one of them, was adopted. In this paper, the hysteresis characteristics of SFCL using magnetic coupling of coils, which were wound in the iron core with two magnetic paths, were analyzed. Through comparative analysis on the hysteresis characteristics of the iron core comprising SFCL, the hysteresis characteristics of the iron core with two magnetic paths were confirmed to be kept in the non-saturation region during the fault period and thus, the effective fault current limiting operation of the SFCL using the magnetic coupling of coils could be performed.

• 한국압력기기공학회 논문집
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• 제10권1호
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• pp.37-43
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• 2014

Nuclear power plants(NPPs) are consisted of power production functions and safety functions preventing leakage of radiation. Operators working in NPPs shall maintain these functions during an operation period through various activities such as improvement & modification, corrective maintenance, preventive maintenance and surveillance test. According to the performance of these work activities, there are configuration changes in NPPs systems. Its changes cause the increase of safety risks(CDF) and plant trip risks. Recently, the importance of risk management is increasing gradually in the operation process of NPPs. Therefore, this paper presents the work management methods using the various risk monitoring systems during power operation and overhaul period. Also this paper suggests the optimum application ways of risk systems for work management.

• Architectural research
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• 제14권1호
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• pp.35-44
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• 2012

Build-Transfer-Lease (BTL) was introduced to the domestic construction market in 2005. Now, seven years later, the BTL model is most active for educational facilities. In 2011, 93 educational facility projects entered the maintenance stage. Considering the characteristics of today's BTL projects for educational facilities, the main issues are the initial performance and maintenance of educational facilities and the service-providing status for the 20-year operational management period, in relation to providing safety and convenience to students, the facility users. Seeking a solution, local education offices and departments in charge of BTL under the Ministry of Education, Science, and Technology have been exploring various methods of evaluating operational maintenance performance from various perspectives. For educational facility BTL projects, however, the appropriateness of initial operation performance evaluation, rather than considering the 20-year operational management period, is controversial in regards to sustainability. On this account, performance evaluation items in four areas-operational maintenance evaluation, facility performance status evaluation, maintenance subject evaluation, and sustainable change response evaluation-should be extracted. An indicator of facility performance evaluation is presented in this study through an AHP survey targeting experts, as part of establishing an operation performance evaluation system for educational facility BTL projects.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1727-1730
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• 2003

A windshield wiper system plays a key part in assurance of driver's safety at rainfall. However, because quantity of rain and snow vary irregularly according to time and velocity of automotive, a driver changes speed and operation period of a wiper from time to time in order to secure enough visual field in the traditional windshield wiper system. Because a manual operation of windshield wiper distracts driver's sensitivity and causes inadvertent driving, this is becoming direct cause of traffic accident. Therefore, this paper presents the basic architecture of vision-based smart windshield wiper system and the rain sensing algorithm that regulate speed and operation period of windshield wiper automatically according to quantity of rain or snow. Also, this paper introduces the fuzzy wiper control algorithm based on human's expertise, and evaluates performance of suggested algorithm in simulator model. In especial, the vision sensor can measure wide area relatively than the optical rain sensor. hence, this grasp rainfall state more exactly in case disturbance occurs.

• 한국국방경영분석학회지
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• 제3권1호
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• pp.109-114
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• 1977

There are some factors which cause the profits from the production to be decreased or increased. They are, for example, the rise in efficiency of production facilities resulting from the development of the scientific technique, the changes of purchase price of those, and the drop in efficiency of those owing to there long-term operation. In this connection, an manager can get the highest profit by deciding the proper time of new facilities replacement for those in operation or in being planned, which leads to good management planning of his manufactaring business for a given period or a long time. Main purpose of this is the study of how we decide the optimal time or facilities replacement in order to maximize the total profits for a given period by considering them as continous function as to the time in the case where a machineng is set. The results are following: 1. The definition of profit function is in duced in consideration of the breakdowns caused from continous operation of the machinery. 2. The necessary conditions are obtained for the optimal time of replacement and find out the methods of its solution. 3. Comparing between the 'Short cut' method and method in this paper, we obtained that our method is more realistic.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.131-134
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• 2005

Anaerobic reductive dechlorination of tetrachloroethylene(PCE) to ethylene was investigated by performing laboratory experiments using semi-continuous flow two-in-series soil columns. The columns were packed with soils obtained from TCE-contaminated site in Korea. Site ground water containing lactate(as electron donor and/or carbon source) and PCE was pumped into the soil columns. During the first operation with a period of 50 days, injected mass ratio of lactate and PCE was 620:1 and incomplete reductive dechlorination of PCE to cis-DCE was observed in the columns. However, complete dechlorination of PCE to ethylene was observed when the mass ratio increased to 5,050:1 in the second operation, suggesting that the electron donor might be limited during the first operation period. During the degradation of cis-DCE to ethylene, the concentration of hydrogen was $22{\sim}29mM$. These positive results indicate that the TCE-contaminated groundwater investigated in this study could be remediated through biological anaerobic reductive dechlorination processes.

• 대한수의학회지
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• 제45권3호
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• pp.405-410
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• 2005

To analyze and identify selected risk factors for infectious bronchitis virus (IBV) infection in the growing and laying period of laying-hen flocks, a longitudinal field study was conducted with 27 commercial flocks reared in three provinces of Korea during the period from May 2003 to April 2004. Using monitored data for IBV infection status among study flocks we computed the multivariate odds ratios (ORs) and their corresponding confidence intervals (CIs), and population attributable risks (PARs). Multivariate logistic regression showed significant risk increments for: continuous entry of chick (OR=1.9, 95% CI, 0.7-69.1) and operation years of the layer house greater than or equal to 5 years (OR=3.2, 95%CI, 1.6-389.9). No significant interaction was found between variables. The PAR suggested that continuous entry of chick (PAR=32%) and ${\geq}5years$ of house operation (PAR=84%) had the highest impacts on IB presence in laying-hen flocks under study. Of the two significant factors, however, operation year of the layer house lacks an easy applicability in preventing IB control strategies, and the possibility of confounder cannot be ruled out.

• 물과 미래
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• 제23권4호
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• pp.499-507
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• 1990

홍수기중의 실시간 저수지 운영을 위해서는 매시간 on-line으로 입력된 자료와 예측치로부터 시간별 최적방류량을 구해야 한다. 이를 위해서 댐하류의 홍수피해를 최소화하고 홍수 말기의 용수보존을 고려하는 무의 모형의 기법을 발표한 바 있다. 본 논문에서는 홍수시의 대청댐의 단일저수지 운영을 위해 모형을 적용하고 결과를 검토하며, 과거의 측정된 유입량과 방류량자료도 검토한다. 초기저수위를 달리하여 각 재현 기간별 홍수수문곡선을 다루고, 강우유출 모형으로부터 얻은 예측유입량을 구하여 운영한 뒤에 실제값과 비교하였다. 연구결과에 의하면 예측유입량의 불확실성을 고려하기 위해 위험계수를 적용하면 홍수조절용량을 효율적으로 이용할 수 있다.

• 대한기관식도과학회지
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• 제18권1호
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• pp.19-23
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• 2012

Carcinoma arising in a thyroglossal duct cyst is a not common disease. It is detected in approximately 1% of thyroglossal duct cyst, therefore the clinical manifestation of the patient with carcinoma is undistinguishable from the common cystic lesion. Clinically, it may be confounded with a benign lesion and diagnosed after operation. The mainstream of treatment is the Sistrunk operation, however, there is no definite agreement regarding further treatment in addition to an excision of the cyst. The role of total thyroidectomy and the radioactive iodine therapy have been discussed for adjuvant treatment. We have experienced four cases of papillary carcinoma arising in thyroglossal duct cyst. In the three of the cases, the patients underwent Sistrunk operation, while the other one had additional total thyroidectomy and postoperative radioactive iodine therapy. There was no complication in the perioperative period and no signs of recurrence or metastasis during follow-up period.