• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.24-31
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• 2008

Power converters are becoming an essential block in modem mobile multimedia application. This paper presents a high performance DC-DC buck converter for mobile applications. Controller of DC-DC buck converter is designed by current-mode control method. An current-mode DC-DC converter is implemented in a standard $0.18{\mu}m$ CMOS process, and the overall die size was $1.2mm^2$. The peak efficiency was 86 % with a switching frequency of $1\sim1.5MHz$ and a maximum load current of 400mA.

• Journal of the Korean Society of Costume
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• v.61 no.4
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• pp.92-102
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• 2011

This study researches the current status of shrouds and analyzes the current status of the Hanji shrouds and sets its goal on suggesting the direction for a futuristic shroud design, suitable for the changing funeral culture. For this, the characteristics of traditional shrouds were studied, standard shrouds' and Hanji shrouds' current statuses were researched and analyzed to suggest the development diretion for design of Hanji shrouds. The results of the research showed that the Hanji shrouds are superior in cremation and burial, and the design expressions were more effective. Also the previously established shrouds were shown to have an increase in value through use of different materials, changing designs through various patterns, or through the added symbolic value. Thus the direction of shroud development designs based on the advantages of Hanji have been drawn out to as follows: First, traditional shrouds used the ceremonial dresses, such as official uniforms or wedding dresses, from the Tang dynasty which made it multicolored. Afterwards colors were limited with the use of hemp clothes shrouds but with the appearance of Hanji shrouds, the possibility for mulitcolors and patterns became larger. Second, Hanji is superior in its expression of colors and patterns, making designs with symbolic sides such as religion possible, to meet the demands of the customers. Third, Hanji shrouds are more environmentaly friendly than the standard shrouds in cremation and burial, and it presents a much better image of shrouds for the future society. Such development of Hanji shrouds design developments satisfies the distinct and gentrified demands of the customers and it looks to be able to suggest an opportunity for environmentaly friendly actions while preparing itself for the chaning market demands and values.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.409-416
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• 2016

The contact force characteristic between the pantograph and the catenary wire represents the current collection quality of trains; it should be precisely controlled under international standard. Recently, a noise reduction cover has been installed around the pantograph of high speed trains. However, little study on the contact force by the pantograph cover has been conducted. In this study, the impact on the current collection performance of the pantograph cover was analyzed by dynamic contact force measurement using a next generation high speed train (HEMU-430X). As a result, it was confirmed that the attachment of a pantograph cover could lower the mean contact force by approximately 50N at 300km/h. In addition, the pure difference of the average contact force by the presence of pantograph cover, except for the static pressure, was measured and found to be up to 110N at 300km/h. It was also found that the standard deviation of the contact force of 3~5N could be changed by use of a pantograph cover.

• Biomolecules & Therapeutics
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• v.30 no.6
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• pp.603-615
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• 2022

Assessing the health of international migrants is crucial in the Republic of Korea, Asia, and even worldwide. We compared the risk factors for non-communicable diseases among Asian migrants in Korea and the Korean population. This cross-sectional (2015) and longitudinal (2009-2015) observational study comprised a population-wide analysis spanning 2009 to 2015. Asian migrants (n=987,214) in Korea and Korean nationals (n=1,693,281) aged ≥20 were included. The Asian migrants were classified as Chinese, Japanese, Filipino, Vietnamese, and other. The prevalence of risk factors for non-communicable diseases (current smoking, obesity, diabetes mellitus, and hypertension) were analyzed. Regarding the age-adjusted prevalence, direct age standardization was conducted separately by sex using 10-year age bands; the World Standard Population was used as the standard population. Among the participants aged ≥20, the age-adjusted prevalence of current smoking was higher among Chinese and other Asian migrant men than among Korean men and women (p<0.001 and p<0.001, respectively). The age-adjusted prevalence of obesity was higher among Chinese, Filipino, and other Asian migrant women than in Korean women (p<0.001, p=0.002, and p<0.001, respectively). Among the participants aged 20-49, the age-adjusted prevalence of diabetes mellitus and hypertension was higher in Filipino migrant women than in Korean women (p=0.009 and p<0.001, respectively). Current rates of smoking and obesity were worse among Asian migrants of specific nationalities than among native Koreans. The health inequalities among Filipino migrant women in Korea, especially those aged 20-49, should be addressed.

• Journal of Advanced Navigation Technology
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• v.20 no.6
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• pp.580-587
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• 2016

In the purpose of suggesting the necessity and proper method of providing the standard reference material for acquiring the aircraft pilot license, this study provides the FAA and ROKAF case study, and positively analyzes the materials of 178 pilots and student pilots who acquired the aircraft pilot license. The result of case study shows that compared to the case of Korea which the restriction on the standard reference material providing exists, the FAA(Federal Aviation Administration) and ROKAF are currently providing the standard reference material. Additionally, the result of positive analysis indicates the fact that the necessity of standard reference material providing is well recognized and its importance also found to be remarkably high. These results represent that the standard reference material providing is necessary for training competent aircraft pilots. Also, this will mitigate the current shortage of aircraft pilots due to the rapid growth of air transportation industry, and this will play an important role in preventing diverse aircraft-related accidents.

• Child Health Nursing Research
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• v.17 no.4
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• pp.238-246
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• 2011

Purpose: The purpose of this study was to identify pediatric nurses' attitudes to, and compliance with, standard precautions in the prevention of hospital infections by enhancing their practice of standard precautions. Methods: The participants were 206 nurses who worked in pediatric nursing departments of a general medical institution in Seoul. The questionnaire was a modification of Kim (2008) and consisted of 18 questions about hand washing, personal protective equipment, sharps, linen and patient care equipment. Collected data were processed using SPSS 15.0 WIN. Results: Mean scores for attitudes to standard precautions and for compliance with standard precautions were 4.43 (${\pm}0.83$) and 4.22 (${\pm}0.44$) respectively. This difference was statistically significant (t=3.368, p=.001). The nurses' compliance with standard precautions differed significantly according to the general characteristics of age (F=8.705, p<.001), total clinical experience (F=9.426, p<.001), current department experience (F=6.555, p<.001), and education experience (t=0.616, p<.043). There was a positive correlation between attitudes to, and compliance with, standard precautions (r=.156, p=.025). Conclusion: The results of this study indicate that educational programs and policy on infection control and standard precautions for pediatric nurses are needed. Also these results should contribute to baseline data for establishing appropriate clinical policy on infection control.

• Journal of the Ergonomics Society of Korea
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• v.32 no.3
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• pp.279-291
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• 2013

Objective: The aim of this study was to compare old standard EN 954-1 and new standard EN ISO 13849-1 through case study and provide necessity of adaptation of EN ISO 13849-1 in Korea. Background: International and EU harmonized standard EN ISO 13849 "safety of machinery - Safety-related parts of control system" is classified into Part 1: General principles for design and Part 2: Validation. EN ISO 13849-1 standard was introduced in Official Journal of the European Union on September 8, 2009 as harmonized standard, and old standard EN 954-1 was withdrawn on December 31, 2011. So, EU decided to use of EN ISO 13849-1 standard forcibly from January 1, 2012 for safety of machinery. New machines need to be CE marked if they are to be placed on the market in the European Economic Area(EEA), Switzerland or Turkey, and Korean machine builder should apply EN ISO 3849-1 standard for safety of machinery accordingly. However, current Korean Safety Certification system(KCs mark) for dangerous machinery is not referred to EN ISO 13849-1 standard as safety standard. There is a need of research for adaptation of EN ISO 13849-1 standard in Korea as safety standards for new design of safety-related control system which use mostly electronic components. Method: Five case studies of representative designs for safety-related control system in accordance with EN 954-1were selected according to safety category from B to 4. And these five representative designs were tried to change new design in accordance with EN ISO 13849-1 standard. The results of comparison were analyzed in aspect of economy and technical complexity. Results: The results showed that EN ISO 13849-1 provided quantitative method of application and it enabled designers to create safety-related control systems that require fewer components and less wiring, with many of the components being to a lower specification and, therefore, less costly. Conclusion: EN ISO 13849-1 standard is good for electronic safety-related control systems compare to EN 954-1. By considering the importance of application of EN ISO 13849-1 and benefits, the application of EN ISO 13849-1 as safety standard for safety of machinery is urgent in Korea. Application: The results of comparing EN 954-1 and EN ISO 13849-1 standard might help to determine the adaptation of EN ISO 13849-1 standard for safety of industrial machinery in Korea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.103-109
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• 2006

This research is contents about output characteristic of optic current sensor that use faraday effect. optic current sensor used in an experiment is consisted of three parts.(1) Source of light used laser diode of 1310[nm].(2) Sensor section manufactured circularly according to gas insulated switchgear. And $9/125[{\mu}m]$ standard single mode optical fiber for communication was installed winding 20 [turn] on sensor section core surroundings of diameter 31 [cm].(3) Electrical signal of PD(Photo detector) is collected using NI company's 16bit DAQ board via terminal block. Collected data analyzed by different three signal processing methods. NI company's $Labview^{TM}$ was used to signal processing software. As a result, In signal processing of optic current sensor, we could know that noise greatly more influences the error generation than fluctuation of light intensity. also, 1 class CT(current transformer) manufacture that have error rate less than 1[%] was available by removing these

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1409-1413
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• 2013

This paper analyzed the change of subthreshold current for channel doping concentration of double gate(DG) MOSFET. Poisson's equation had been used to analyze the potential distribution in channel, and Gaussian function had been used as carrier distribution. The potential distribution was obtained as the analytical function of channel dimension, using the boundary condition. The subthreshold current had been analyzed for channel doping concentration, and projected range and standard projected deviation of Gaussian function. Since this analytical potential model was verified in the previous papers, we used this model to analyze the subthreshold current. As a result, we know the subthreshold current was influenced on parameters of Gaussian function and channel doping concentration for DGMOSFET.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.4
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• pp.263-276
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• 1992

The transmission current in a power cable is determined under the condition of separate pipe cooling. To this end, the thermal analysis is conducted with the standard condition of separate pipe cooling system, which constitutes one of the underground power transmission system. The changes of transmission current in a power cable with respect to the variation of temperatures and flow rates of inlet cooling water as well as the cooling spans are also determined. As a consequnce, the corresponding transmission current is shown to vary within allowable limit, resulting in the linear variation of the current for most of the cable routes. The abrupt changes of current, however, for the given flow rate of inlet cooling water in some cooling span lead to the adverse effects on the smooth current transmission within the underground power transmission system. In practice, it is expected that the desinging of the separate pipe cooling system in conjunction with the evaluation of system capacity should take into account the effects of design condition on the inlet cooling flow rate.