• Tribology and Lubricants
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• 제5권2호
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• pp.42-47
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• 1989

The thermal behaviour of layerd solids, typified in practice by surface coated materials, is evaluated for the specific case of a fast moving heat source. This is intended to represent the particular instance of solids in sliding contact and the consequences of friction. The finite difference method has been utilised to establish the temperature distributions at the surface and also the sub-surface region for coating materials which are either less conductive or more conductive than the substrate to which they are attached. The effects of variation in layer thickness, and also the load, speed and friction coefficient, are evaluated.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.46.3-46
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• 2002

Most of the process control algorithms in practice are based on the finite dimensional control theory. However, many chemical processes are described by partial differential equations (PDE's) and are infinite dimensional in nature due to spatial variation. Especially when the convection is dominant and thus diffusion can be ignored, chemical processes that are described by a system of first order hyperbolic PDE's. Such processes include tubular reactors, fixed bed reactors and pressure swinging adsorption. Conventionally such infinite dimensional systems described by PDE's are controlled by finite dimensional controllers that are designed through finite dimensional reduction of the process m...

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.700-705
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• 2005

This study presents a fatigue line with a plastic rotational angle to a great extent of plastic strain of Low-Cycle-fatigue period, such as earthquake, etc. This fatigue line with a plastic rotational angle is measured and analysed more simply in practice rather than Woehler's fatigue line which is developed in stress variation of the structure. It shows that the slope of fatigue line with a plastic rotational angle is equal to that with plastic strain through the experiments by proving the correlation that the plastic strain ratio is directly proportional to the plastic rotational angle in plastic hinge.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.353-360
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• 1998

Dynamic measurements are used rather sparingly to determine the elastic moduli of rock cores and modulus values are not much utilized in design practice. The reason seems to result from the general perception that values obtained by dynamic measurement are much higher (about 10 times) than those determined statically. This paper presents results from dynamic and static tests on rock cores. The findings are : 1) elastic moduli can be consistently determined by laboratory seismic testing. 2) nonlear deformation characteristic of rock cores was tentatively proposed with variation in elastic modulus with strain.

• 연구논문집
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• 통권24호
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• pp.13-26
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• 1994

The choice of design parameters for a robot arm depends on the desired workspace, load lifting capacity, application requirements, and the performance of the robot. The inverse process, which is the determination of a single robot's workspace for a given specification is also a common practice and is as important to the designers as it is to the users. Based on the geometric influence coefficients, the workspace areas on the vertical Y-Z plane are investigated and calculated. Using these areas, the effects of link parameters, link length ratios and joint rotation angles, are investigated.

• 한국자동차공학회논문집
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• 제16권4호
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• pp.143-150
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• 2008

EGR(exhaust gas recirculation) is an attractive means of improving the fuel economy of spark ignition engines, as it offers the benefits of charge dilution (lower pumping and cooling losses) while allowing stoichiometric fuelling to be retained for applications using the three-way catalysts. However, the occurrence of excessive cyclic variation with high EGR normally prevents substantial fuel economy improvements from being achieved in practice. Therefore, the optimum EGR rate in Gasoline-Hybrid engine should be carefully determined in order to achieve low fuel consumption and low exhaust emission. In this study, 2 liters gasoline engine with E-EGR system was used to investigate the effects of EGR on fuel economy, combustion stability, engine performance and exhaust emissions. EGR tolerance with load variation was found to be more sensitive than with rpm variation. With optimal EGR rates, the fuel consumption was improved by 5.5% while a combustion stability was guaranteed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1194-1199
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• 2010

Systematic finite element analyses on consolidation were performed with various drainage conditions. Numerical analyses were performed using SAGE CRISP2D, a commercial numerical analysis program for the conventional geotechnical engineering practice. For the input properties of the numerical analyses, incremental loading oedometer tests were performed on reconstituted kaolinite samples. Numerical analyses were performed with various drainage conditions such as vertical, radially inward and outward drainage conditions. For the case of radially inward drainage conditions, a series of numerical analyses were performed with varying the diameter of vertical drains. As a result, the lateral deformation and void ratio variation occurred during consolidation for the radially inward or outward drainage conditions. And the variations of the lateral deformation and void ratio did not fully disappear even after the completion of the consolidation and induced the spatial variations of the soil properties. Keywords : finite element analysis of consolidation, various drainage conditions, lateral deformation, spatial variation of soil properties.

• 한국산업보건학회지
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• 제18권2호
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• pp.141-148
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• 2008

To prevent musculoskeletal disorders(MSD) for dental hygiene students, who will potentially be at high risk of developing MSD while performing oral prophylaxis practice, an MSD prevention education program was designed and was offered to a group of dental hygiene students to find whether the program is effective. Before the program started and three months after the program ended, changes in the students' posture were filmed to observe them. The final subjects for analysis included 30 students in the experimental group and 41 students in the control group. To verify differences between the experimental and the control groups, repeated measures ANOVA was carried out before and after the program. After the education program, the experimental group's RULA scores for neck, left upper arm, right forearm, and wrist, RULA A score on both left and right side, RULA B score on left side, and total RULA score were significantly lowered during the operation on the upper jaw, compared with that of the control group. And, during the operation on the lower jaw, the experimental group's RULA A score, RULA B score, and total RULA score were very significantly lowered. The results of this study suggest the MSD prevention education program is effective in preventing the disorder. Thus, the program can be utilized as an education program for preventing MSDs during dental hygiene students' oral prophylaxis practice and clinical practice.

• 보건행정학회지
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• 제8권1호
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• pp.1-14
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• 1998

Analysis of practice variations has been one of important issues in trying to contain costs as well as to manage quality in health care. This study was conducted to provide statistical model for analysing variations in inpatient costs by type of hospitals. Four K-DRGs including Cesarean section, appendectomy, cataract extraction, and pediatric pneumonia with CC class 0 were selected, and means and dispersions of inpatient procedure and operation costs were simultaneously compared between type of hospitals. The results indicated that joint modelling of means and dispersions by gamma distribution was a very useful analytic tool for identifying factors which might have relationship with variations in inpatient costs. This model can be expanded to test the significance of several independent variables in analysing cost variations. In surgical conditions, means and unit variations of procedure and operation costs showed consistent pattern which was tertiarty hospital, general hospital, and hospital in descending order. Different findings were identified in pediatric pneumonia, from which mean and unit variation of procedure and operation cost was the highest in general hospital. The practical implication of this difference could not be drawn from this study. It will be done by further sophisticated researches. In order to develop health policy for cost containment and quality management in Korea, it is essential to find out manageable factors affecting variations in practice patterns which include characteristics of population, providers, regions, and so on. The statistical model presented in this study will give health services researchers useful insights for future investigations in analysing cost variations.

• 한국콘텐츠학회논문지
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• 제11권9호
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• pp.372-383
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• 2011

본 연구의 목적은 관상동맥중재술 입원 환자의 재원일수의 변이를 규명하기 위해 중증도 보정 모형을 개발하였다. 2004~2006년 퇴원손상환자 조사자료 중 관상동맥중재술 입원 환자 1,011건을 연구대상으로 하였으며, 재원일수의 변이분석은 t검정, 분산분석을 실시하였고, 중증도 보정 재원일수 모형은 데이터마이닝 기법을 이용하였다. 개발된 다중회귀분석 모형을 이용하여 예측 재원일수를 산출하고 이를 실제 재원일수와 비교한 결과 병상규모별, 보험유형과 지역별로 재원일수의 변이가 존재하는 것으로 나타났다. 환자 특성과 중증도를 통제하고 나타난 재원일수의 변이는 공급자 요인으로 설명될 수 있는데, 진료행태나 의료자원에 대한 후속 연구가 필요한 것으로 보인다. 본 연구는 행정 데이터를 이용하여 중증도 모형을 개발하고 변이를 확인하였다는 점에서 활용의 효용성을 높이는 데 기여할 것으로 사료된다.