• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.82-84
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• 2003

In case contact between point of contacts is not achieved well, contact resistance is grown, and by current concentration at current conducting contacts can weld. In order to decrease contact resistance between contacts in case of busbar, installing spring between fixed contact and moving contact. and then force on faying surface of contacts increase and contact resistance decrease. But, in case increase force of spring to widen contact area, operating force moving contact can grow, on the contrary force of spring is small, contact resistance becomes low. Therefore, need to optimize force and number of spring. position, and also need to examine force change on contact surface at point of contact moving. In this paper, dynamic kinetics analysis for force on faying surface of contacts is performed at unsteady state. It is showed to not uniform force on surface between contacts, and we can got more uniform force by means of change spring position.

• 한국자동차공학회논문집
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• 제18권3호
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• pp.43-52
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• 2010

In this study, the shapes of the wheel and rail are represented by using 3-dimensional surface functions with surface parameters and a 3-dimensional wheel-rail contact analysis is presented. A whole numerical solution of wheel-rail contact at tread and flange including 2-point contacts can be achieved with the proposed numerical algorithm. Kinematic characteristics such as variances of vertical displacement and roll angle, and variance of wheel radius difference for arbitrary yaw and lateral displacement of wheelset, are determined for the KTX wheel-rail pair as an example. The condition of yaw and lateral displacement occurring 2-point contacts to analyze derailment are compared between standard and worn wheels. Differences of contact characteristics between curved and straight rails are also analyzed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.593-596
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• 2001

It is necessary for calculation of repulsion forces acting on the closed electric contacts flowing over-current, e.g. inrush current and overload currents, to do optimum design of switching devices. In this paper, the farces and flux densities generated by currents at the contact point when circuit breakers are in closed state are obtained by using 3D finite element methode. To be convinced of the results, we measure electrogmanetic repulsion forces on contacts by measuring voltage between opened contacts in MCCB.

• 전기학회논문지
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• 제57권1호
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• pp.46-51
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• 2008

Extra-high voltage(EHV) disconnecting switch(DS) consists of the electrical contacts and mechanical parts which actuate the contacts. When the short-circuit condition occurs, a large amount of current flows through the electrical contact in disconnecting switches and this causes considerable temperature rise due to Joule heating. If the temperature rise is higher than the melting point of contact material, the DS contact becomes melting and cannot be usable anymore. For this reason, the analysis for capability of carrying short-circuit current in DS contacts must be performed at a design stage. Here, we proposed a numerical technique for evaluating the capability of carrying short-circuit current at electrical contacts in EHV DS. In this numerical approach, the mechanical and thermal analyses were simulated to check the capability of carrying short-circuit current. First, the applied pressure at contact parts was analyzed considering the mechanical properties, and then contact resistance was calculated by an empirical equation. Finally, thermal analysis was performed with resistance variation at electrical contacts. To verify these numerical results, the distributions of temperature in DS were experimentally measured and compared with each other. The results from experiments were agreed well with those from the proposed numerical simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1424-1429
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• 2004

In this paper a mathematical framework for deriving acceleration bounds from given joint torque limits of multiple cooperating robots are described. Especially when the different frictional contacts for every contact are assumed and the torque limits are given in 2-norm sense, we show that the resultant geometrical configuration for the acceleration is composed of corresponding parts of ellipsoids. Since the frictional forces at the contacts are proportional to the normal squeezing forces, the key points of the work includes how to determine internal forces exerted by each robot in order not to cause slip at the contacts while the object is carried by external forces. A set of examples composed of two robot systems are shown with point-contact-with-friction model and insufficient or proper degree of freedom robots.

• Structural Engineering and Mechanics
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• 제36권1호
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• pp.95-110
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• 2010

Two-dimensional elastic contact problems, including normal, tangential, and rolling contacts, are treated with the finite element method in this study. Stress boundary conditions and kinematic conditions are transformed into multiple point constraints for nodal displacements in the finite element method. Upon imposing these constraints into the finite element system equations, the calculated nodal stresses and nodal displacements satisfy stress and displacement contact conditions exactly. Frictional and frictionless contacts between elastically identical as well as elastically dissimilar materials are treated in this study. The contact lengths, sizes of slip and stick regions, the normal and the shear stresses can be found.

• Journal of Medicine and Life Science
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• 제17권1호
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• pp.29-32
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• 2020

As respiratory syncytial virus(RSV) is transmitted either via directly contact with an infected case or via indirectly contaminated fomites or skin, the major preventive measures are strict hand hygiene, early detection of transmitted sources, and rapid isolation of RSV patients. Especially early detection of hidden cases is the most critical control measure when an index case was notified in a postpartum center. The Guideline of Korea Centers for Diseases Control and Prevention defines potential contacts in an epidemiologic survey as admitted newborns, parents of index cases, center's workers, and visitors for 10 days before the first diagnosis day of index case. However, it needs to classify potential contacts in more detail in order to conduct a successful survey. Authors conducted to search related literatures and appraise the evidences. Firstly, potential contacts would be classified into RSV-related symptomatic contacts(SxC) and asymptomatic contacts. And then, mother, caring workers, and visitors of the index cases among asymptomatic contacts would be defined as the asymptomatic close contacts(ASCC). Finally, the rest would be defined as the asymptomatic regular contacts(ASRC). The defined test using reverse transcription-PCR is applied to SxC and ASCC, and decision of isolation or regular activities are made according to the results. The rapid antigen detection test kits are applied to ASRC. These suggestions might be helpful to detect hidden cases earlier and prevent a further infection.

• Journal of Preventive Medicine and Public Health
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• 제57권3호
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• pp.223-233
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• 2024

Objectives: The coronavirus disease 2019 pandemic has exacerbated the rate of tuberculosis (TB) infection among close contacts of TB patients in remote regions. However, research on preventive behaviors, guided by the Health Belief Model (HBM), among household contacts of TB cases is scarce. This study aimed to employ the HBM as a framework to predict TB preventive behaviors among household contacts of TB patients in the border areas of Northern Thailand. Methods: A cross-sectional study with multi-stage random sampling was conducted in Chiang Rai Province. The study included 422 TB patients' household contacts aged 18 years or older who had available chest X-ray (CXR) results. A self-administered questionnaire was used to conduct the survey. Results: The participants' mean age was 42.93 years. Pearson correlation analysis showed that TB preventive behavior scores were significantly correlated with TB knowledge (r=0.397), perceived susceptibility (r=0.565), perceived severity (r=0.452), perceived benefits (r=0.581), self-efficacy (r=0.526), and cues to action (r=0.179). Binary logistic regression revealed that the modeled odds of having an abnormal CXR decreased by 30.0% for each 1-point score increase in preventive behavior (odds ratio, 0.70; 95% confidence interval, 0.61 to 0.79). Conclusions: HBM constructs were able to explain preventive behaviors among TB patients' household contacts. The HBM could be used in health promotion programs to improve TB preventive behaviors and avoid negative outcomes.

• 제어로봇시스템학회논문지
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• 제10권10호
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• pp.887-898
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• 2004

In this paper a mathematical framework fur deriving acceleration bounds from given joint torque limits of multiple cooperating robots are described. Especially when the different frictional contacts for every contact are assumed and the torque limits are given in 2-norm sense, we show that the resultant geometrical configuration for the acceleration is composed of corresponding parts of ellipsoids. Since the frictional forces at the contacts are proportional to the normal squeezing forces, the key points of the work includes how to determine internal forces exerted by each robot in order not to cause slip at the contacts while the object is carried by external forces. A set of examples composed of two robot systems are shown with point-contact-with-friction model and insufficient or proper degree of freedom robots.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.593-596
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• 2001

It is necessary for calculation of repulsion forces acting on the closed electric contacts flowing over-current. e.g. inrush current and overload currents, to do optimum design of switching devices. In this paper. the forces and flux densities generated by currents at the contact point when circuit breakers are in closed state are obtained by using 3D finite element methode. To be convinced of the results, we measure electrogmanetic repulsion forces on contacts by measuring voltage between opened contacts in MCCB