• Industrial Engineering and Management Systems
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• 제10권3호
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• pp.209-220
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• 2011

Self-tapping screws have some operational peculiarities. In spite of their economical advantage that requires no prior tapping operation, a weakness of self-tapping screw-tightening operations is that screws can easily be tightened at a non-right angle, thus resulting in an improper tightening strength. Increases in outsourced workers have reduced labor costs, but the accompanying high worker fluidity means that new workers are more frequently introduced into factories. It is necessary to train new workers for self-tapping screw-tightening operations, which occupies a considerable portion of ordinary assembly works. The purpose of this study is to develop and implement a skill transfer system for the operation. This study (1) proposes a set of characteristic values for evaluating the quality of the operation and develops a device that can measure these values; (2) proposes criteria for evaluating the resultant quality of the tightening; and (3) develops a skill training system for better work performance. Firstly, sets of characteristic values for evaluating the quality of the operation, namely, torque, vertical pressure forces and horizontal vibration forces, are proposed. A device that can measure these values is developed. Secondly, criteria for evaluating the resultant quality of the tightening are identified, involving tightening torque, maximum vertical pressure and timing, vibration area during the processing and tightening period, and work angle. By using such parameters, workers with the proper aptitude can be identified. Thirdly, a skill training system for the operation is developed. It consists of screwdriver operation training and screw-tightening training with feedback information about the results of the operation. Finally, the validity of the training system is experimentally verified using new operators and actual workers.

• Water Engineering Research
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• 제3권1호
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• pp.57-62
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• 2002

This research is intended to integrate long-term operation rules and real time operation policy for conservation & flood control in a reservoir. The familiar Yield model has been modified and used to provide long-term rule curves. The model employs linear programming technique under given physical conditions, i.e., total capacity, dead storage, spillways, outlet capacity and their respective elevations to find required and desired minimum storage fur different demands. To investigate the system behavior resulting from the above-mentioned operating policy, i.e., the rule curves, the simulation model was used. Results of the simulation model show that the results of the optimization model are indeed valid. After confirmation of the above mentioned rule curves by the simulation models, gate operation procedure was merged with the long term operation rules to determine the optimum reservoir operating policy. In the gate operation procedure, operating policy in downstream flood plain, i.e., determination of damaging and non-damaging discharges in flood plain, peak floods, which could be routed by reservoir, are determined. Also outflow hydrograph and variations of water surface levels for two known hydrographs are determined. To examine efficiency of the above-mentioned models and their ability in determining the optimum operation policy, Esteghlal reservoir in Iran was analyzed as a case study. A numerical model fur the solution of two-dimensional dam break problems using fractional step method is developed on unstructured grid. The model is based on second-order Weighted Averaged Flux(WAF) scheme with HLLC approximate Riemann solver. To control the nonphysical oscillations associated with second-order accuracy, TVD scheme with SUPERBEE limiter is used. The developed model is verified by comparing the computational solutions with analytic solutions in idealized test cases. Very good agreements have been achieved in the verifications.

• 한국수자원학회논문집
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• 제31권1호
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• pp.105-113
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• 1998

홍수기 중 저수지 운영은 이수와 치수를 고려한 전반적인 홍수기 저수지 운영확 홍수예측시 임의의 저수지 수위에서의 홍수시 저수지 운영으로 구분할 수 있다. 본 연구는 홍수시 저수지운영에 관한 것으로 전반적인 홍수시 저수지 운영방안에 관해 논의하고자 한다. 현행의 홍수시 저수지 운영을 위해서는 확보된 홍수조절용량을 토대로 각종 수문모형의 불확실성과 기술적인 한계, 제약조건 등을 고려한 양적인 홍수조절 방안이 마련되어야 한다. '저수지 홍수변환법'은 이러한 양적인 홍수조절 방안중의 하나로 무피해방류량 이상의 홍수유입량에 대해 댐의 안전을 고려하여 적절한 방류량을 결정하는 일련의 절차이다. 본 연구에서는 기 발표된 '저수지 홍수변환법'에 대한 보충설명과 함께 전반적인 홍수시 저수지 운영방안을 논의하였다.

• Clinics in Shoulder and Elbow
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• 제9권1호
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• pp.60-67
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• 2006

Purpose: The purpose of this study was to compare the method of using coraco-clavicular (C-C) sling with modified Phemister operation by postoperative clinical results, radiologic analysis and complications. Materials and Methods: 33 patients of acromioclavicular joint dislocation were included in this study. Thirteen patients were treated with simple C-C sling method and twenty patients were treated with modified Phemister operation. The assesment of clinical and radiological evaluation were performed and the final results were examined by using the Weitzman's classification. Results: In the final result of C-C sling method group, forward elevation $161^{\circ}$, external rotation $70^{\circ}$, internal rotation T8 level, Visual Analogue Scale (VAS) 83.3 points were checked. In modified Phemister operation group, forward elevation $155^{\circ}$, external rotation $67^{\circ}$, internal rotation T6 level, VAS 83.8 points were checked. In coracoclavicular distance of C-C sling method group, pre-operation 12.82 mm and last follow up 8.37 mm were checked. In modified Phemister operation group, pre-operation 12.8 mm and last follow up 7.7 mm were checked. In functional evaluation by the Weitzman criteria, C-C sling group had excellent 8, good 1, fair 1 and modified Phemister group had excellent 13, good 4, fair 3. Conclusion: C-C sling method would be the better than the Modified Phemister operation because of short operation time and smaller skin incision.

• 한국임상수의학회지
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• 제25권1호
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• pp.9-14
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• 2008

This purpose of this study was to describe and compare the radiographic and computed tomographic(CT) appearance of the experimentally induced Legg-Calve-Perthes Disease(LCPD) in dogs. LCPD was experimentally induced at the left femoral head in 7 litters of a dog. The lesions were evaluated with radiography, CT, and contrast CT every week from day 7 to day 70 after operation. Histopathologic examination was performed on 92th day after operation. Every images were evaluated according to the staging system of the osteonecrosis published by Association Research of Circulation Osseous in 1997 and the scoring(0-4). On CT scan, diffuse porotic lesion and focal sclerotic lesion were detected on day 14 and on day 21 after operation, respectively. Subchondral fracture, articular collapse and crescent sign with decreased attenuation were shown on day 28 after operation for the first time and no change of the sign were detected from operation day 9 to day 70 after operation. Focal porotic lesion and irregular radiopacity of femoral head were detected on day $41{\pm}7.48$ and on day $51{\pm}5.29$ after operation respectively on radiographs. In scoring evaluation, 2.00 was scored on day 14 after operation on CT scan, on day 56 after operation on radiographs, respectively This study has shown that CT is more suitable for early diagnosis of LCPB and has superior sensitivity than radiography. Also, CT has been expected to be important for staging and treatment of LCPD.

• 교육시설 논문지
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• 제25권4호
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• pp.19-30
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• 2018

The school classroom is a common living place where students spend 7 to 14 hours a day to prepare for their careers. Therefore, if the ventilation of the classroom is not properly performed, it may lead to the deterioration of learning ability due to the unclear air. The concentration of carbon dioxide in the classroom is reported to be high, and the increase in carbon dioxide concentration has a negative effect on the learner's academic performance. In this context, the purpose of this study is to propose a methodology for intelligent and responsive window opening-closing operation process that can reduce the concentration of $CO_2$ in the classroom in order to build a support space that can create an effective teaching-learning environment for adolescents. The specific objectives are as follows. First of all, we define the concept of window opening-closing operation. Secondly, twe develop the operation process of window opening-closing. Thirdly, we develop an algorithm for real-time window opening and closing (process) (Window Opening-Closing Operation Process). Finally, we verify the intelligent responsive window opening-closing operation process through developing examples of window opening-closing operation process using the parametric design program. This study is a preliminary study to develop algorithms necessary for window opening-closing operation. Based on the first-order algorithm, We simulated window opening-closing operations according to a hypothetical scenario. As a result, This study can show that the window is open and close depending on the $CO_2$ concentration, but the $CO_2$ concentration in the room is higher than outdoors. Consequentially, we suggest that it is necessary to develop an algorithm to supplement these results because window is often not working when the temperature difference between indoor and outdoor in winter is large.

• 한국콘텐츠학회논문지
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• 제3권4호
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• pp.63-68
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• 2003

본 논문은 통신 네트워크 운용관련 민감도 측정에 관한 연구를 위해 네트워크 운용 적정비용 산출 및 효율화 방안을 제안하였다. 통신 네트워크 운용효율화를 위해 네트워크 운용 효율성 측정을 위한 모형을 개발하였다. 전반적/포괄적 관점에서 산출된 네트워크 운용의 적정비용에 대해 품질수준 개선을 위한 요소, 고객만족도 관련 요소 등과의 연계성을 중심으로 재평가하고 개선하는 것이 본 논문의 가장 핵심적인 연구이다. 이러한 과정은 네트워크 운용의 가장 큰 부분을 차지하는 것이 품질관련 활동이고 품질관련 활동은 결국 고객만족도로 나타나게 되는 것이기 때문에, 각 요소별 개별적인 변화가 상호간에 미치는 영향을 중심으로 상관관계를 정립하여 민감도 측정을 바탕으로 네트워크운용비용을 산출하는 것이 진정한 의미의 적정수준 분석이라 할 수 있다. 따라서, 본 논문에서는 네트워크 운용에 대한 체계적인 모형의 구축 및 효율성 측정을 위한 다양한 시나리오에 따른 민감도 측정을 위한 시스템을 개발하였다.

• 한국수자원학회논문집
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• 제32권6호
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• pp.685-695
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• 1999

홍수예경보란 홍수예측시 적기에 홍수예경보를 발령하여 홍수피해를 경감시키고자 하는 방재활동의 일환으로 이는 홍수조절과정을 전제로 한다. 유역내에서 홍수조절을 직접 수행할 수 있는 곳은 홍수조절용량을 갖추고 있는 다목적 댐으로 홍수시 다목적 댐의 역할은 매우 중요하다고 할 수 있다. 홍수예경보시스템에서 이러한 다목적 댐의 저수지 운영과 관련된 부분의 바로 저수지 운영모듈이다. 본 연구에서는 한강홍수통제소에 구축된 저수지 운영모듈의 현황과 문제점을 고찰하여 한정된 범위내에서 개선작업을 수행하였고 결과적으로 Technical ROM과 ARD ROM을 추가적인 저수지 운영모듈로 구축하였다. 새로이 구축된 저수지 운영모듈을 이용하여 홍수시 한강 홍수통제소는 Technical ROM과 같은 확정론적인 모의방법을 통해 우선 홍수통제에 관한 1차적인 계획을 수립하고, 이후 승인된 방류량에 따라 ARD ROM을 이용하여 최종적인 홍수통제 및 예측 업무를 수행할 수 있을 것이다.

• 한국건설관리학회논문집
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• 제20권5호
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• pp.42-51
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• 2019

철도운영기관은 수송수요예측과 열차차량의 수송능력을 토대로 수송계획을 세우고 이에 따른 열차운행계획을 수립한다. 열차운행계획을 통해 열차 운행간격이 조정되어 열차운행시간표(열차다이아)가 작성되고, 열차운행에 사용되는 열차의 차량운영계획이 수립된다. 열차운영기관에서는 열차 운영관리의 효율성을 높이기 위해 다이아에 편성되어진 열차들의 승무인원을 판단하고 배치하는 승무일정계획을 수립해야 한다. 본 연구에서는 승무일정계획 문제인 승무다이아 작성단계에 제약조건을 만족하는 이웃해 탐색기법을 적용하여 승무 계획의 효율적 관리가 가능하도록 하는 방법론을 제시한다. 연구에서 제시한 방법론에 의해 생성된 승무 다이아는 실제 운영하는 열차시간표를 대상으로 기존 승무다이아와 결과 값을 비교하여 제시된 방법론의 효율성을 검증하였다.

• 융합정보논문지
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• 제11권4호
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• pp.203-210
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• 2021

본 연구는 의료기관의 설립운영 관리주체에 따라 운영자금 조달방법별 조달비율과 이들이 경영성과에 미치는 영향을 살펴보고자 의료기관 회계정보 공시시스템에 등록된 재무정보를 이용하여 분석하였다. 분석방법은 설립운영 관리주체별 차이비교를 위하여 분산분석을 실시하였으며, 운영자금 조달방법별 조달비율이 경영성과에 미치는 영향은 로지스틱 회귀분석과 회귀분석을 실시하였다. 연구결과, 운영자금 대비 총수익 비율은 설립운영 관리주체에 따라 유의한 차이가 있었다. 그리고 운영자금 조달방법별 조달비율은 경영결과(적자, 흑자)와 유의하게 인과관계가 있는 것으로 확인되었으며, 운영자금 조달방법 조달비율이 경영성과에 미치는 영향은 설립운영 관리주체에 따라 차이가 있었다. 이상의 결과 의료기관의 운전자금 관리는 운영자금에 대한 수익의 비율을 고려한 비용관리를 우선적으로 적용하고 그 다음으로 내부운영자금을 활용하는 방안의 적용이 적절할 것으로 사료된다.