• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.38-40
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• 2002

In the case of conventional high frequency inverter, with damage of switch by surge voltage when switch gets into compulsion extinction by load accident and so on because reactor is connected by series to switch, or there was problem of conduction loss by reactor's resistivity component, Also, it has controversial point of that can not ignore conduction loss of switch in complete work kind action of soft switching. In this paper, as high frequency induction heating power supply, we propose half bridge type multi resonance soft switching high frequency inverter topology that can realize high amplitude operation of load current with controlling switch current by multiplex resonance, mitigating surge voltage when switch gets into compulsion extinction and to be complete operation of zero current switching by opposit parallel connected reactor to inverter switch. and do circuit analysis for choice of most suitable circuit parameter of circuit

• Journal of the Korea Institute of Building Construction
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• v.9 no.3
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• pp.59-64
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• 2009

This study is to analyse the causes of accident in small and medium-sized construction sites and to provide prevention strategies and system improvement guidance. Although occupational safety and health act regulates the standards and installations of temporary structures, about an half of construction accidents were caused by poor temporary structures such as guardrails, scaffolds, work platforms, etc. It investigated 51 construction sites which is located in metropolitan area by asking a series of questions including their knowledge about regulations and opinions about prevention strategies. The result shows that many of the respondents do not have sufficient understandings about the regulations, and it implies that education and training must be reinforced in order to enhance the safety-awareness and to develop the comprehension of regulations.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.55-61
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• 1999

The torsional and axial vibrations of shaft system have been calculated independently because of both the limitation of computing time and the complexity of crankshaft model. In actual system, however, the torsional and axial vibrations are coupled. Therefore, in recent, many works in the coupled vibration analysis have been done to find out the more exact dynamic behavior of shaft system. The crankshaft model is very important in the vibration analysis of shaft system because most of excitation forces act on the crankshaft. It is, however, difficult to establish an exact model of crankshaft since its shape is very complex. In this work, an efficient method is proposed to construct the stiffness matrix of crankshaft using a finite element model of half crankthrow. The proposed and existing methods are compared by applying to both a simple thick beam with circular cross section and an actual crankshaft.

• Korean Medical Education Review
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• v.15 no.1
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• pp.54-58
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• 2013

There has been an increase in the number of female doctors worldwide. Women now represent half of all medical students, with almost the same numbers of men and women becoming physicians. There is a pool of talented women in our midst, and it is our responsibility as leaders to find those individuals and groom them for progress. However, residency training and academic education still resemble the historical model when there were few women in medicine. Gender differences in medical specialty choices can cause a maldistribution of doctors by specialty and geographical area, which could cause significant problems at the national health care system level. Major challenges facing female physicians include gender discrimination and sexual harassment, and work/family conflicts. Women are largely under-represented in academic medicine and experience discrimination in the academic environments. Recent issues about related to the "feminization of medicine" raise important questions forabout how academic medicine deals with gender issues. To better accommodate the needs of female doctors and ensure that they will have successful careers, structural and cultural changes to medical educations are needed.

• Bulletin of the Korean Chemical Society
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• v.21 no.7
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• pp.697-700
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• 2000

A method of calculating the excess Helmholtz free energy from the average of the bent effective acceptance ratio for two-center-Lennard-Jones liquids has been presented. The bent effective acceptance ratio has been newly composed from the acceptan ce ratio for the potential energy difference between a configuration in the Metropolis Monte Carlo procedure and random virtual configuration generated by the separate parallel Monte Carlo procedure and the Boltzmann factor for half the potential energy difference. The excess Helmholtz free energy was calculated directly from the average of the bent effective acceptance ratio through a single Metropolis Monte Carlo run. Because the separate parallel Monte Carlo procedure was used, this method can be applied to molecular dynamics simulations. For two-center-Lennard-Jones liquids, the average of the bent effective acceptance ratio gave better results than use of the modified effective acceptance ratio in the previous work.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.172-180
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• 1999

The major subject of this paper is to develop the concept fur a Korea high speed train system and recommend to train configuration. High speed train configurations are basically concerned traction power(train configurations with concentrated; CPT or distributed Power system: DPT) and train design(single car as compared with articulated bogies). The result of configuration, a advantages and disadvantaged were necessitated by different train configurations; -distributed underfloor power have an increased length for the seats by 15% as compared with the concentrated power trait - articulated trainsets are characterised by less of number of bogies and reduced values of mass, train resistance, noise and vibration. from the result, the optimized train concept combining high seat capacity per train length with low weight and train resistance is 400m long, single -floor train composed of two symmetrically arranged half trainsets. Therefore, at this work recommended distributed train system However, the final decision of Korea high speed train configuration was concentrated power train and articulated bogie system. The configuration of trainset was 20cars included 2 power cars, 4 motorized cars and 14 trailer cars.

• Journal of Power Electronics
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• v.19 no.1
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• pp.1-10
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• 2019

Current imbalance is the main factor affecting the lifespan of light-emitting diode (LED) lighting systems and is generally solved by active or passive approaches. Given many new lighting applications, independent control is particularly important in achieving different levels of luminance. Existing passive and active approaches have their own limitations in current sharing and independent control, which bring new challenges to the design of LED drivers. In this work, a multichannel resonant converter based on switched-capacitor control (SCC) is proposed for solving this challenge. In the resonant network of the upper and lower half-bridges, SCC is used instead of fixed capacitance. Then, the individual current of the LED array is obtained through regulation of the effective capacitance of the SCC under a fixed switching frequency. In this manner, the complexity of the control unit of the circuit and the precision of the multichannel outputs are further improved. Finally, the superior performance of the proposed LED driver is verified by simulations and a 4-channel experimental prototype with a rated output power of 20 W.

• Progress in Superconductivity and Cryogenics
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• v.23 no.1
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• pp.1-6
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• 2021

Thermoacoustic oscillations (TAOs) could be often observed in liquid helium cryogenic system especially in half-open tubes. These tubes have closed warm end (300K) and open cold end (usually 4.4K). This phenomenon significantly induces additional heat load to cryogenic system and other undesirable effects. This work focuses on using computational fluid dynamics (CFD) method to study TAOs in liquid helium. The calculated physical model, numerical scheme and algorithm, and wall boundary conditions were introduced. The simulation results of onset process of thermoacoustic oscillations were presented and analyzed. In addition, other important characteristics including phase relation and frequency were studied. Moreover, comparisons between experiments and the CFD simulations were made, which demonstrated thevalidity of CFD simulation. CFD simulation can give us a better understanding of onset mechanism of TAOs and nonlinear characteristics in liquid helium cryogenic system.

• Journal of Technologic Dentistry
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• v.42 no.4
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• pp.372-378
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• 2020

Purpose: The aim of this study is to explore professional ethics and awareness of education among dental technicians. Methods: A total of 250 questionnaires were produced and distributed to dental technicians from June 1 to October 30, 2019. Of these questionnaires, 106 were used in the final analysis. Results: More than half of respondents said that the state-run dental company has very strong ethical values. Higher levels of confidence in the professional mission of dental work were correlated with stronger ethical values. Moreover, those who had greater experience of training in the code of ethics for dental technicians exhibited a firmer sense of their professional mission. Conclusion: In the education process for dental technicians, attention should be given to establishing and practicing professional ethics. Guidelines and programs should be revised accordingly to build awareness of ethical practices in the workplace.

• Safety and Health at Work
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• v.12 no.2
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• pp.141-146
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• 2021

Background: Violence against health professionals is an increasing problem in Turkey. This study aims to determine the societal perception of violence, experience of violence, and the intentions to use violence against health professionals. Methods: This descriptive study sample comprised 484 individuals. Data were collected by using the "Descriptive Information Form" and "Intentions to Use Violence against Health Professionals Scale." Results: Of the participants, 8.3% used violence against health professionals. Most of the participants (81.2%) stated that violence was not a solution, and 65.9% believed that health professionals did not deserve violence. Past behavior of the participants was the most influential factor on the intention to use violence (β = .473, p = 0.000). Conclusions: More than half of the participants believed that health professionals did not deserve violence and violence was not a solution. We found that intention to use violence was affected by past experiences.