• Journal of Power Electronics
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• 제12권2호
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• pp.276-284
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• 2012

AC/AC power conversion is widely used to feed AC loads with a variable voltage and/or a variable frequency from a constant voltage constant frequency power grid or to connect critical loads to an unreliable power supply while delivering a very balanced and accurate sinusoidal voltage system of constant amplitude and frequency. The load specifications will clearly impose the requirements for the inverter stage of the power converter, while wider ranges of choices are available for the rectifier. This paper investigates the utilization of a buck-type current source rectifier as the active front-end stage of an AC/AC converter for applications that require an adjustable DC-link voltage as well as elimination of the low-frequency common mode voltage. The proposed solution is to utilize a combination of two or more zero current vectors in the Space Vector Modulation (SVM) technique for Current Sources Rectifiers (CSR).

• 센서학회지
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• 제24권5호
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• pp.299-305
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• 2015

Since the natural disasters such as floods, droughts, heat wave and cold wave are increasing, the need for risk management is necessary to minimize the damage with utilizing IT technology. Also, the monitoring services of disaster response type have been developed and applied. Recently, the open source hardware based on the signal of the sensor, or the monitoring studies have been carried. In this paper, by analyzing a low-cost open source hardware platform such as Beagle board, we examine the utilization of the hardware-based module for sensor monitoring.

• 한국수학교육학회지시리즈A:수학교육
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• 제53권4호
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• pp.449-462
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• 2014

In this study, mathematics teachers' awareness of the need for motivation and its utilization in the actual classes were analyzed through a survey. As a result, the mathematics teachers answered positive on the need for motivation but the attempts for motivation in actual classes were rather low. In addition, they answered that teacher training for motivation were helpful in actual classes. Among Keller's ARCS, the strategies mathematics teachers recognized necessary and those used frequently in actual classes often showed generally consistent, and the need for motivation and the degree of utilization got highest score in motivation sector. On the other hand, mathematics teachers need to acknowledge specific utilization strategies of ARCS but showed incompetent in utilizing them in actual classes. Thus, in order to efficiently utilize the strategies for motivation in mathematics classes, mathematics teachers needed practical teacher training, specific instruction methods, researches on practical instructional methods and in-service, and administrative supports for the activations of teacher's study group and mentor system.

• 한국병원경영학회지
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• 제17권2호
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• pp.21-33
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• 2012

Purpose : This study aims to suggest application of patients DB to hospital marketing by performing market segmentation and selecting target market. Consequently help to establish suited strategy of marketing. Method : 14,072 patients hospitalized in a University Medical Center were recruited into this study. In order to classify the customer groups, cluster analysis was used with RFM(Recency, Frequency, Monetary) model, and 1-way ANOVA verified the differences among groups. And then, sociodemographical status, healthcare utilization and diagnosis(ICD-10) of each group were compared to draw a marketing strategy. Results : Four groups were classified through clustering analysis, and'high use and high profit' and'low use and high profit' groups were selected as a target market. The features of target market were as follows, the female proportion was high; used a private room; hospitalized through the emergency room; had operation; length of stay was long; had many comorbidity and cooperative treatment. There was difference in each feature of target market: as for the'high use and high profit' group, many patients were diagnosed with 'certain infectious and parasitic diseases'; and as for the'low use and high profit'group, the proportion of patients who purchased'industrial accident compensation insurance'and'auto insurance'was relatively high; many patients were diagnosed with'Injury, poisoning and certain other consequences of external causes'. Conclusion : It is needed to establish'positioning' strategy by monitoring and communicating with'high use and high profit' group. And for the case of'low use and high profit' group, it is necessary to make a follow-up management and lead them to have a medical check-up.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2711-2719
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• 2013

Hydrogen bonding interaction between alcohols and water molecules is an important characteristic in the aqueous solutions of alcohols. In this paper, a series of molecular dynamics simulations have been performed to investigate the aqueous solutions of low molecular weight alcohols (methanol, ethylene glycol and glycerol) at the concentrations covering a broad range from 1 to 90 mol %. The work focuses on studying the effect of the alcohols molecules on the hydrogen bonding of water molecules in binary mixtures. By analyzing the hydrogen bonding ability of the hydroxyl (-OH) groups for the three alcohols, it is found that the hydroxyl group of methanol prefers to form more hydrogen bonds than that of ethylene glycol and glycerol due to the intra-and intermolecular effects. It is also shown that concentration has significant effect on the ability of alcohol molecule to hydrogen bond water molecules. Understanding the hydrogen bonding characteristics of the aqueous solutions is helpful to reveal the cryoprotective mechanisms of methanol, ethylene glycol and glycerol in aqueous solutions.

• 한국물환경학회지
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• 제20권3호
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• pp.197-205
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• 2004

Batch test methods have developed for a long time to measure kinetic and stoichiometric parameters which are required to perform steady state design and mathematical modelling of activated sludge processes. However, at various So/Xo ratios, abnormal behaviors of ordinary heterotrophic organism in batch tests have been reported in many researches. Thus, in this research, abnormal behaviors of heterotrophs in batch tests were investigated at various So/Xo conditions by measuring and interpreting oxygen utilization rate. As So/Xo ratio increased, the calculated values of maximum specific growth rates, ${\mu}_{H,max}$ and $K_{MP,max}$, increased. However, at a certain point of So/Xo (around 10mgCOD/mgMLAVSS), ${\mu}_{H,max}$ and $K_{MP,max}$ values started to decrease. According to this observation, three prominent behaviours of heterotrophs were identified at various So/Xo conditions. (1) At low So/Xo region (below 5 mgCOD/mgMLAVSS), the oxygen utilization rate of heterotrophs in batch tests were almost stable and consequently yielded lower maximum specific growth rate. (2) At high So/Xo region (up to 5~10 mgCOD/mgMLAVSS), oxygen utilization rate incresed sharply with time and indicated more upward curvature than the predicted OUR with conventional activated sludge model, which consists of single hetetrotrophs group. Thus, in this region, competition model of two organisms, fast-grower and slow-grower, seemed to be appropriate. (3) At extremely high So/Xo region (over 10mgCOD/mgMLAVSS), significant oxygen utilization rate was still observed even after depletion of readily biodegradable COD. This might be caused by retarded utilization of intermediates which were generated by self inhibition mechanism in the process of RBCOD uptake.

• 한국노년학
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• 제31권1호
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• pp.171-188
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• 2011

본 연구는 Andersen의 의료서비스 이용에 관한 행동모형을 근거로 2008년 장애인실태조사 자료를 분석하여 만 65세 이상 장애노인의 외래 및 입원이용에 영향을 미치는 요인을 파악하고자 하였다. 연구방법은 two-part 모델을 활용하여 장애노인의 외래 및 입원 이용 여부에 대해서는 로지스틱 회귀분석을, 의료 이용량 및 의료비 지출에 대해서는 다중 회귀분석을 실시하였다. 분석결과 외래와 입원의 이용에 공통적으로 만성질환과 주관적 건강상태 등의 질병요인의 영향이 유의하였고, 의료비 지출에는 의료보장 유형이 결정적 역할을 하고 있었다. 외래에서는 신장장애를 가졌을 때 이용량과 지출이 높았고, 입원에서는 일상생활의 수행에 도움이 필요할 때 입원일수가 증가하였으며, 심장장애와 호흡기장애를 가진 경우 입원료 지출이 유의하게 높았다. 이상의 결과는 장애노인들에게 만성질환 이환이나 일상생활 활동의 전적인 의존을 예방하는 보건의료 서비스의 제공, 의료이용이 높은 내부 장애를 가진 노인에 대한 지속적 보건관리체계의 구축, 그리고 저소득층 장애노인의 보건 의료 접근성 향상을 위한 경제적 지원의 필요성을 시사한다.

• 한국산학기술학회논문지
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• 제11권9호
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• pp.3495-3501
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• 2010

최근 화상회의, 인터넷방송, 온라인 게임등 대규모의 데이터를 여러사용자에게 동시에 전송하는 애플리케이션이 증가함으로 인해 그룹 통신의 중요성 및 활용도가 높아지게 됨에 따라 그에 대한 보안이 중요한 문제로 인식되게 되었다. 멀티캐스트 환경에서 보안성을 제공하기 위해 기존의 하나의 그룹 관리 서버를 통해 키 트리 기반의 프로토콜을 이용한 연구가 많지만, 제안하는 논문에서는 상대적으로 오버헤드가 적은 안전한 그룹키 관리 기법을 제안하고자 한다. 따라서 제안하는 논문에서는 기존의 그룹키 관리기법과의 차별성 및 효율성을 비교하여 우수성을 입증한다.

• Journal of Nutrition and Health
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• 제26권2호
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• pp.145-155
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• 1993

A factorial experiment was conducted to determine the influence of phytate(0 or 10g/kg diet) and calcium (Ca)(3 or 10g/kg diet) intakes on Ca, P and Zn metabolism by growing female rats. Food intake and weight were similar for the all groups, however, phytate ingestion for six weeks depressed femur growth. The low Ca plus phytate group showed the lowest Ca content of total femur and this was related to a significant decrease of Ca retention. Phytate intake depressed zinc(Zn) absorption in the first metabolic collection. This inhibitory effect of phytate on Zn absorption was improved in the low Ca plus phytate group after several weeks. Impared Zn absorption however remained in the high Ca plus phytate group which was reflected in the lowest Zn content of femur, phytate intake with high Ca also depressed phosphorous(P) absorption and serum and urinary P. These adverse effects of phytate on Zn and P absorption when the dietary Ca was high could explain reduced femur weight despite the highest concentration of femur Ca(mg/g ash) in this group. Results suggest that phytate can adversely affect not only Ca metabolism but Zn and P utilization. Thus, for the normal bone growth when phytate intake is high, the ingesion of Ca, P, Zn and other minerals should be enhanced.

• 복식문화연구
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• 제19권5호
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• pp.889-902
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• 2011

The purposes of this study were to identify point makeup purchasing and using behavior according to the personal color awareness. Most women considered their favorite color first when purchasing lipsticks and skin color when purchasing cheek powder or foundation. They considered makeup concept first when applying lipsticks, eye shadows, and cheek powder but skin color applying foundations and manicures. Factors of personal color awareness were preferences & utilization awareness, other's advice, and direct awareness, and were segmented into PC intermediate group, high PC group, and PC retard group. PC intermediate group were in the late 20's and the early 30's, average incomes with high education, and patronized discount stores for point makeups, used fashion color as a criterion when selecting lipsticks, foundations, and manicures, apparel color when applying eye shadows, skin color when applying cheek creams, and preferred imported lipsticks and manicures. High PC group were among unmarried women in the early 20's, university students, high income households with medium level of pocket money, spent more for point makeup, and patronized department stores and internet shopping mall, used skin color or fashion color as criteria when selecting point makeup, referenced makeup concept when applying point makeup, preferred imported point makeup. PC retard group were among married women in the late 30's with low education and low income, spent less for point makeup and pocket money, and selected domestic point makeup, used their favorite color as a criterion when selecting point makeups and apparel color when applying lipsticks and cheek creams.