• 전력전자학회논문지
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• 제24권1호
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• pp.56-61
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• 2019

In this study, a reduction method of leakage current in a three-level photovoltaic power-conditioning system (PCS) is proposed and verified by simulation and experiment. Leakage current generation is analyzed through an equivalent model of the common mode voltage considering a significant parasitic capacitance existing between the photovoltaic array and ground. A leakage current reduction method using pulse-width modulation (PWM) method is also proposed, and a 10-kW three-level photovoltaic PCS simulation and experiment is performed with a $1{\mu}F$ parasitic capacitor based on 100 nF/kW. The proposed method using the PWM method is verified to reduce the leakage current by 73% compared with the conventional PWM method.

• 대한치과의사협회지
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• 제54권1호
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• pp.27-38
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• 2016

Objectives: This study evaluated the outcomes of continuing professional education in implant dentistry using Kirkpatrick's four-level evaluation model. Material and methods: The study was carried out through a questionnaire distributed to dentists who attended a continuing professional education in implant dentistry, 2008~2012. They were asked to fill out questionnaires at least 6 months after its completion. Results: Mean ages of total 23 dentist was $44.8^{\circ}{\ae}8.2$. Mean period after completion of education was $2.7^{\circ}{\ae}1.2$. Knowledge (level 2) (r=0.71, p<0.01) and behavior (level 3) (r=0.68, p<0.01) was positively correlated with topic and methods of education in reaction (level 1). Behavior was positively correlated with knowledge (r=0.79, p<0.01). Result (level 4) was positively correlated with knowledge (r=0.64, p<0.01) and behavior (r=0.86, p<0.01). Conclusion: Reaction affects on knowledge, behavior and result in order.

• 대한임상독성학회지
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• 제13권2호
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• pp.55-61
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• 2015

Purpose: Many studies have examined the mechanisms of impaired glucose homeostasis after organophosphate (OP) exposure, however no study has evaluated the clinical utility of blood glucose measurements in patients with OP poisoning. The current study was conducted to evaluate the initial glucose level at presentation and the glycemic variables during the first 3 days after admission as a predictor of mortality. Methods: This retrospective observational case series included 228 patients with a history of OP poisoning. Among other clinical data, information on the initial glucose level at presentation and mean glucose level, delta glucose level, and the presence of a hypoglycemic event during the first 3 days of admission, was collected. Results: Survivors had lower initial glucose levels at presentation and glucose variability during the first 3 days of admission compared to non-survivors. The frequency of hypoglycemic events was higher in non-survivors. In multivariate analysis, the initial glucose level (> 233 mg/dl) was an independent predictor of mortality, along with age. Conclusion: The initial glucose level at presentation can be helpful in prediction of mortality in cases of OP intoxication at bedside. The physician should pay attention to patients with a glucose level >233 mg/dl at presentation after ingestion of OP.

• 한국초전도ㆍ저온공학회논문지
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• 제23권4호
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• pp.56-60
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• 2021

The microwave Radar used for special purposes in the past is being applied in various areas due to the technological advancement and cost reduction, and is particularly applied to autonomous driving in the automobile field. The FMCW (Frequency Modulated Continuous Wave) Radar can acquire level information of liquid in vessel based on the beat frequency obtained by continuously transmitting and receiving signals by modulating the frequency over time. However, for cryogenic fluids with small impedance differences between liquid medium and gas medium, such as liquid nitrogen and liquid hydrogen, it is difficult to apply a typical Radar-based level meter. In this study, we develop an 80 GHz FMCW Radar for level measurement of cryogenic fluids with small impedance differences between media and analyze its characteristics. Here, because of the low intrinsic impedance difference, most of the transmitted signal passes through the liquid nitrogen interface and is reflected at the bottom of the vessel. To solve this problem, a radar measurement algorithm was designed to detect multiple targets and separate the distance signal to the bottom of the vessel in order to estimate the precise position on the liquid nitrogen interface. Thereafter, performance verification experiments were performed according to the liquid nitrogen level using the developed radar level meter.

• Asian-Australasian Journal of Animal Sciences
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• 제4권3호
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• pp.211-218
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• 1991

The effects of dietary fiber on true digestibility of amino acids by growing pigs were studied, using semi-purified diets formulated from alfalfa meal, cassava leaf meal, rubber seed meal and leucacna meal at 20% level. A protein-free diet including 5% cellulose was formulated for correcting the endogenous amino acid loss. Across all the diets, arginine was the most digestible while the least at ileal level was threonine; methionine and/or histidine at fecal level respectively. The true digestibility value of amino acids at ileal level were higher than at fecal level except control diet (cellulose). The true digestibility values at ileal level were similar for all diets but differed at fecal level in different magnitude. These results indicate that undigestible compound in individual feedstuff might confound. True digestibility should be studied together for accurate diet formulation as apparent digestibility decreased when their amino acid concentration in the diet was reduced.

• 한국환경과학회지
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• 제23권5호
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• pp.801-806
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• 2014

Long-term change in sea level along the eastern coast of Korea was illustrated using four tide-gauge station (Pohang, Mukho, Sokcho, Ulleung) data, water temperature and salinity. Seasonal variation in the sea level change was dominant. The sea level change by steric height derived from water temperature and salinity was relatively lower than that measured from the tide-gauge stations. Sea level rising rate per year by steric height increased with latitude. The effect of salinity(water temperature) on the sea level change is greater in winter(in summer).

• Communications for Statistical Applications and Methods
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• 제8권2호
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• pp.383-394
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• 2001

This paper is a generalization of single and two-level skip-lot sampling plans to n-level. On every skipping inspection of the n-level skip-lot sampling plan, not only the number of consecutive lots to be accepted but also the fraction of lots to be inspected can be freely choosed. The general formulas of the operating characteristic function, average fraction inspected, average sample number and average outgoing quality in n-level skip-lot sampling plan are derived. The operating characteristic curves, average sample number and average outgoing quality of a reference plan, two-level and five-level skip-lot sampling plans are compared.

• 기술혁신학회지
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• 제2권3호
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• pp.61-75
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• 1999

This study is focused on acquiring through understanding of the S&T level of Korea to serve as an important basis for the government policy-making and to make available basic information for promoting the National R&D Program effectively. the survey of S&T level is a comparison of the highest level in the world to that of korea in 3 digit of the technology tree table. And survey of technological gaps is determined by year which Korea is able to reach the current level of the advanced countries. The results of the surveys should be applied to strategic technology planning for solving or nar-rowing the technology gap and the major criteria for resources allocation in national R&D Pro-grams. The results of he surveys should be the fundamental information for establishing strategic S&T policy in government.

• Journal of Power Electronics
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• 제12권2호
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• pp.285-293
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• 2012

Multilevel inverters have gained attention in high-power applications due to their numerous advantages in comparison with conventional two-level inverters. In this paper a simplified Space-Vector Modulation (SVM) algorithm for a three-level Neutral-Point Clamped (NPC) inverter is implemented on a Freescale$^{(R)}$ DSP56F8037. The algorithm is based on a simplification of the space-vector diagram for a three-level inverter so that it can be used with a two-level inverter. Once the simplification has been achieved, calculation of the dwell times and the switching sequences are carried out in the same way as for the two-level SVM method. Details of the hardware design are included. Experimental results are analyzed to validate the performance of the simplified algorithm.

• 대한가정학회지
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• 제36권8호
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• pp.63-76
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• 1998

The purposes of this research were to find out general trends of the efficiency of the interspouse communication and the level of stress recognition, to estimate the differences of the efficiency of communication and the level of stress recognition according to socio-demographic, communication variables, and to analyze correlations between stress recognition and communication efficiency. The subjects of this study were 220 couples in Kwang-ju. The major results were as follow; 1) The level of wives' stress recognition was higher than husbands' and the level of interspouse communication efficiency was median. 2) Communication efficiency showed significant differences according to number of children, the duration of marriage in wives. The level of stress recognition showed significant differences according to the hours they spend in daily communication, the typeds of communication, the satisfaction of communication in both groups of husbands and wives. 3) Marital communication efficiency was negatively correlated with the level of stress recognition in couples.