• 조명전기설비학회논문지
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• 제19권3호
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• pp.35-43
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• 2005

종래의 컨버터-인버터 전력변환 시스템에서 do-link를 제거하여 보다 효과적인 인버터를 만들기 위하여 매트릭스 컨버터에 관하여 연구를 하고자 한다. 따라서 매트릭스 컨버터는 에너지를 저장하는 능동소자를 갖지 않는 장점이 있으나 전원이 스위치를 통하여 직접 부하에 연결되므로 전원의 리플과 노이즈가 그대로 부하에 전달되는 결점을 갖는다. 매트릭스 컨버터는 전원을 부하에 대하여 정현적으로 스위칭해야 되며, 한편 이러한 노이즈를 제거 및 보상하는 특성과 함께 역율문제도 함께 해결해야 한다. 본 연구에서는 종래의 제시된 방법에 비하여 제어어시간을 단축시킨 제어함수를 제시한다. 제시된 제어함수는 전원에 포함된 리플과 노이즈를 스위칭하는 과정에서 자동으로 보상하며 역율 1이되게 스위칭한다. 시뮬레이션 결과와 실험결과를 함께 제시한다.

• Tuberculosis and Respiratory Diseases
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• 제85권2호
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• pp.165-174
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• 2022

Background: One goal of the End tuberculosis (TB) Strategy is to see no TB-affected households experiencing catastrophic costs. Therefore, it is crucial for TB-elimination programs to identify catastrophic costs and their main drivers in order to establish appropriate health and social measures. This study aimed to measure the percent of catastrophic costs experienced by Egyptian TB patients and to identify its determinants. Methods: We conducted a prospective cohort study with 151 Egyptian TB patients recruited from two chest dispensaries from the Cairo governate from May 2019 to May 2020. We used a validated World Health Organization TB patient-cost tool to collect data on patients' demographic information, household income, and direct and indirect expense of seeking TB treatment. We considered catastrophic TB costs to be total costs exceeding 20% of the household's annual income. Results: Of the patients, 33% experienced catastrophic costs. The highest proportion of the total came in the pre-treatment stage. Being the main breadwinner, experiencing job loss, selling property, and the occurrence of early coronavirus disease 2019 lockdown were independent determinants of the incidence of catastrophic costs. Borrowing money and selling property were the most-often reported coping strategies adopted. Conclusion: Despite the availability of free TB care under the Egyptian National TB Program, nearly a third of the TB patients incurred catastrophic costs. Job loss and being the main breadwinner were among the significant predictors of catastrophic costs. Social protection mechanisms, including cash assistance and insurance coverage, are necessary to achieve the goal of the End TB Strategy.

• 한국학교ㆍ지역보건교육학회지
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• 제23권2호
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• pp.51-64
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• 2022

Objectives: This study aims to examine diabetic patients' quality of life by using the data of the 8th Korea National Health and Nutrition Examination Survey (1st year, 2019), identify the factors related to this, and utilize the results as basic data for intervention that can improve diabetic patients' quality of life. Methods: For the research subjects, this study extracted 624 patients who were diagnosed with Diabetes by a doctor from the total sample of 8,110 participants of the 8th Korea National Health and Nutrition Examination Survey. The SPSS(version25.0) program was used for the analysis of the collected data. Then, this study used a backward elimination multiple regression analysis method that applied complex sample, to examine the factors related with the finally estimated quality of life. Results: The results of this study revealed that diabetic patients' quality of life was related with gender, age, occupation, restriction of activity, subjected health status. The final model explained 35.7% of the variance (Wald F=28.210, p<.001). Conclusions: In order to improve the quality of life of diabetic patients, it would be desirable to provide differentiated management by developing a customized intervention strategy that takes into account gender, age, and occupation. When managing diabetic patients, the state, local governments, and hospitals should include content that prevents and copes with restrictions on activities that may occur due to disease. In addition, it is required to prepare a strategy to induce positive perception of the subject's own health status.

• 한국과학교육학회지
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• 제26권4호
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• pp.546-558
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• 2006

본 연구의 목적은 지구환경적 문제를 해결하는 과정 중에 귀추법이 어떻게 활용되는가를 발견법적으로 확인하기 위한 것이었다. 현직 지구과학 교사, 사범대학의 예비 과학 교사, 그리고 고등학교 학생 등 서로 다른 배경을 지닌 참여자들이 총 32개 조를 이루어 끝이 열린 형태의 지구환경적 문제를 해결하였고, 그 과정에서 자신들의 추론 과정이 기록된 텍스트를 산출하였다. 이 텍스트에 포함된 추론 과정을 귀추법의 삼단논법적 형식에 따라 정리하고 귀추적 추론에서 사용된 사고 전략들을 반복적으로 분석하였다. 그 결과, 추론자들이 지구환경적 문제 해결 상황에서 귀추법을 사용하였으며, 그들은 다양한 사고 전략들을 활용하여 귀추적 결론을 낳게 하는 규칙을 추리해 내었음을 알 수 있었다. 이 전략들은 자료의 재구성, 연쇄적 귀추, 특이 정보의 채택, 모델 구성 및 조작, 인과적 결합, 제거, 사례 기반의 유추, 그리고 존재에 관한 전략 등이었다. 결론적으로, 학생들의 사고 능력을 증진시키고 지구과학과 지구환경적 문제 해결 과정의 특징에 대한 학생들의 이해를 함양하기 위하여 귀추적 추론 과제가 이용될 수 있다는 것을 시사 받을 수 있었다.

• Parasites, Hosts and Diseases
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• 제54권3호
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• pp.253-259
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• 2016

In the era of (pre) elimination setting, the prevalence of malaria has been decreasing in most of the previously endemic areas. Therefore, effective cost- and time-saving validated pooling strategy is needed for detection of malaria in low transmission settings. In this study, optimal pooling numbers and lowest detection limit were assessed using known density samples prepared systematically, followed by genomic DNA extraction and nested PCR. Pooling strategy that composed of 10 samples in 1 pool, $20{\mu}l$ in 1 sample, was optimal, and the parasite density as low as $2p/{\mu}l$ for both falciparum and vivax infection was enough for detection of malaria. This pooling method showed effectiveness for handling of a huge number of samples in low transmission settings (<9% positive rate). The results indicated that pooling of the blood samples before DNA extraction followed by usual nested PCR is useful and effective for detection of malaria in screening of hidden cases in low-transmission settings.

• 농촌지도와개발
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• 제25권2호
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• pp.71-83
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• 2018

This study aims to analyze the competitiveness of agricultural products in Korea, China and Japan and the effect of increasing imports from Korea and China. and then we discussed how to cooperate in the agricultural trade field between the three countries. The results are summarized as follows. First, The intra-industry trade of agricultural products was the most active in Korea and China, followed by the intra-industry trade index between Korea and Japan. The intra-industry trade between China and Japan were the lowest. Second, The mutual complementarity of agricultural products trade between Korea, China and Japan is mostly high. Among them, Korea and Japan are the highest, while Japan and China have the lowest complementarity. Third, it was found that in tariff elimination, imports of rice and meat products increased the most, while the import growth rate of green tea, meat products and ginseng increased the most. Finally, the three countries in Korea, China, and Japan can consider the way to increase the trade of agricultural products in the region by internalizing the trade of complementary items while maintaining a constant level of production of mutually competitive products.

• 산업공학
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• 제20권3호
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• pp.235-244
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• 2007

The Toyota Production System (TPS) developed by Toyota Motor Corporation is a management principle and production method to improve values added thorough elimination of waste. Since the oil shock in 1970s, the TPS has drawn the worldwide attentions as a main factor of competitiveness of Japanese manufacturing system and has been studied and implemented in many countries regardless of size and types of industry. While the principles of the TPS system are known widely, the framework and the implementation methodology are rarely discussed, especially in the domestic companies. In this paper, the framework of the TPS system are developed as a view of the domestic practitioners and researchers, with which the introduction strategy can be developed as a guideline.

• 한국정밀공학회지
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• 제15권5호
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• pp.65-71
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• 1998

This paper presents in-process compensation methodology to eliminate cutter runout and improve machined surface quality. The cutter runout compensation system consists of the micro-positioning mechanism with the PZT (piezo-electric translator) which is embeded in the sliding table to manipulate the radial depth of cut in real time. For the implementation of cutter runout compensation methodology. cutting force adaptive control was proposed in the angle domain based upon PI (proportional-integral) control strategy to eliminate chip-load change in end milling process. Micro-positioning control due to adaptive acuation force response improves the machined surface quality by compensation or elimination of cutter runout induced cutting force variation. This results will provide lots of information to build-up the precision machining technology.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.675-682
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• 2016

Sudden voltage drops and outages frequently disturb the operation of sensitive loads for domestic, commercial, and industrial use. In some cases, these events may even impair the functioning of relevant equipment. To maintain power under such conditions, a UPS system is usually installed. Once a disturbance happens at the grid side, the line-interactive UPS system takes over the load to prevent an interruption. But, due to magnetic saturation of the transformer, a significant inrush current may occur for the transformer-coupled loads during this transition. The generation of such transient currents may in turn decrease the line voltage and activates over-current protecting devices of the system. In this work, a cost-effective, line-interactive UPS system is proposed that eliminates the inrush current phenomenon associated with transformer-coupled loads. The strategy was implemented by connecting a standard current-regulated voltage source inverter (CRVSI) to the secondary winding of the load transformer. During any transient condition at the grid side, the load current is monitored and regulated to achieve either seamless compensation of the load current or complete transferal of load from grid to the inverter. Experimental results were obtained for a prototype under all possible operating conditions so as to validate the performance of the proposed topology.

• 전력전자학회논문지
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• 제9권4호
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• pp.334-340
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• 2004

본 논문에서는 캐스케이드 변압기를 이용하는 멀티레벨 인버터의 변압기 크기를 동일화시키기 위한 효과적인 스위칭 패턴을 제안한다. 제안된 스위칭 방식은 기존의 SHEPWM 스위칭 방식을 기초로 하여 각 변압기에 인가되는 최대 자속을 동일하게 함으로서 캐스케이드 변압기의 위치에 상관없이 동일한 설계가 가능하다. 따라서 동일한 풀-브리지 모듈의 이용이 가능하고, 모듈화 특성을 개선시키며, 제작의 용이성을 쾌할 수 있다. 제안된 스위칭 기법의 기본 아이디어를 이론적으로 분석하며, 타당성을 실험을 통하여 입증한다.