• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1296-1308
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• 2014

This paper presents a new zero voltage switching (ZVS) converter for medium power and high input voltage applications. Three three-level pulse-width modulation (PWM) circuits with the same power switches are adopted to clamp the voltage stress of MOSFETs at $V_{in}/2$ and to achieve load current sharing. Thus, the current stresses and power ratings of transformers and power semiconductors at the secondary side are reduced. The resonant inductance and resonant capacitance are resonant at the transition interval such that active switches are turned on at ZVS within a wide range of input voltage and load condition. The series-connected transformers are adopted in each three-level circuit. Each transformer can work as an inductor to smooth the output current or a transformer to achieve the electric isolation and power transfer. Thus, no output inductor is needed at the secondary side. Three center-tapped rectifiers connected in parallel are used at the secondary side to achieve load current sharing. Compared with the conventional parallel three-level converters, the proposed converter has less switch counts. Finally, experiments based on a 1.44kW prototype are provided to verify the operation principle of proposed converter.

• 대한의용생체공학회:의공학회지
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• 제37권2호
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• pp.90-103
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• 2016

본 연구는 유한 요소 법을 이용한 노화되어 강성/강도가 저하되는 요추 체의 얇은 피질과 해면 골의 하중 분담 비율 분석과 사용된 탄성계수들의 평가가 목적이다. 해면 골의 나은 해석을 위하여, 20년마다 압축 시험에서 얻은 탄성계수를 체적 공극 비율로 나눈 유효 탄성계수를 사용하였다. 이와 상응하는 피질 쉘도 공극 비율을 포함한 빔 이론의 수식들로부터 유효 탄성계수를 구한 후에 적용하였다. 또한 p-요소를 사용하여 수치 오차를 최소화하였다. 보고된 논문들을 참고하여 후관절 부분이 제거된 매개 변수적인 퇴행된 L3 척추 형상을 만들어 유한 요소 모델링 하였다. 일정 변위의 압축 조건을 가한 후에 여덟 조각의 부피 별로 각 뼈에서 탄성 변형률 에너지와 수직 하중의 비율을 사용하여 하중 분담 비율을 계산하였다. 결과로는 1) 20대에서 80대까지 해면 골의 하중 비율은 55%에서 49%로 감소하였다; 2) 피질 쉘은 중간 면에서 최고 비율을, 해면 골은 종판에서 최고 비율을 나타냈다; 3) 다공성 얇은 피질과 해면 골을 위한 유효 탄성계수의 사용은 적절하였다; 4) 두 방법을 이용하여 얻은 하중 분담 비율의 차이는, 전체 비율은 1% 미만 내에서 같지만 각 위치에서의 비율 값들은 약간 달랐다.

• 생명과학회지
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• 제20권2호
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• pp.208-212
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• 2010

작물의 수량과 품질은 저온 및 고온 스트레스에 영향을 받는 것으로 알려져 있다. 본 연구에서는 배추에서의 스트레스 저항성과 연관된 분자마커를 개발하기 위하여 저온에서의 스트레스 저항성에 영향을 미치는 것으로 알려져 있는 alternative oxidase (AOX) 합성 유전자 관련 분자 마커를 개발하였다. 총 15개의 AOX 합성 유전자와 관련된 Brassica rapa ESTs를 arabidopsis AOX 합성 유전자 염기서열을 이용하여 찾을 수 있었다. 이를 이용하여 고온에서 상대적으로 약한 '지부'품종과 상대적으로 강한 '권심' 사이에서 DNA 염기서열을 조사하여 4개의 ESTs에서 insertion 또는 deletion을 찾았고 PCR로 확인 가능한 4개의 공동우성 마커를 개발하였다. 본 연구에서 개발된 분자마커는 배추 작물에서 환경스트레스 저항성과 유전적 연관성을 확인하는데 유용하게 사용될 수 있다고 기대된다.

• 대한의용생체공학회:의공학회지
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• 제34권1호
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• pp.14-23
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• 2013

In this study, biomechanical stability of the newly developed revision total knee arthroplasty (rTKA) was evaluated through strain and stress distribution analysis within the implanted proximal tibia using a three-dimensional finite element (FE) analysis. 2000N of compressive load (about 3 times body weight) was applied to the condyle surface on spacer, sharing by the medial (60%) and lateral (40%) condyles simulating a stance phase before toe-off. The results showed that PVMS within the revision total knee arthroplasty and the proximal tibia were less than yield strength considering safe factor 4.0 (rTKA: less than 10%, Cortical bone: less than 70%, Cancellous bone: less than 70%). The materials composed of them and the strain and stress distributions within the proximal tibia were generally well matched with those of a traditional revision total knee arthoplasty (Scorpio TS revision system, Stryker Corp., Michigan, USA) without the critical damage strain and stress, which may reduce the capacity for bone remodeling, leading to bone degeneration. This study may be useful to design parameter improvement of the revision total knee arthoplasty in biomechanical stability point of view beyond structural stability of revision total knee arthoplasty itself.

• 인간식물환경학회지
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• 제22권3호
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• pp.269-277
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• 2019

This study aims to see what changes flower arrangement programs bring to the stress index of elderly people with chronic diseases and its correlation with cognition. Furthermore, seniors from a day care center and a nursing home were compared for the purpose of identifying the effectiveness of flower arrangement activities as a supplementary remedy designed to relieve the symptoms and improve the quality of life of patients with chronic diseases. In this study, 24 seniors with chronic diseases were divided into two groups: Group A consists of 15 seniors from a day care center and Group B consists of nine seniors from a nursing home. Both groups participated in simple flower arrangement activities in 10 sessions. In each session, red and green cut flowers that were preferred by the elderly were provided to elicit and develop their thoughts and behaviors. The results showed that the overall average stress index was significantly reduced from 58.0±11.6 before the program to 50.6±17.1 after the program (p = .037). This study examined that the program was more effective for Group A (p = .021) than for Group B (p = .678). Results of the correlation analysis showed that there was no correlation between cognitive function and stress index (p = .569), but that the activity was more effective for Group A. This study shows that arranging flowers effectively lowers the stress index of elderly people with chronic diseases. Also, sharing the outcomes of such activities with others or continuously caring for the flowers even after the activity can maximize the effectiveness of the therapy and rehabilitation. Thus, the study concluded that the program needs to be applied continuously, not in the short-term, in order to relieve or treat the symptoms of elderly patients with chronic diseases.

• 산경연구논집
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• 제11권6호
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• pp.29-39
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• 2020

Purpose: The purpose of this study is, in the situation where rapid response to the rapidly changing environment is required due to the development of the fourth industrial revolution such as artificial intelligence, virtual reality, and the internet of things, robotics, big data, additive manufacturing, bio-health, sharing economy and in the organizational culture aspiring toward the innovation of a major company, small business and a public institution, to analyze what influence a job-engagement and stress make, and what influence individual's self-efficacy as a moderator mediator makes, and to offer basic data for improving job-engagement and lowering job-stress. Research design, data, and methodology: For doing this, the literature and the empirical studies were combined. Deriving innovation-oriented organizational culture as factors affecting the job engagement and job stress through the literature, and have established hypotheses to verify them. We have collected data of 281 from ex,ecutives and staff-members working in areas including major company, small business and officials (the central government, a local public service, the prosecution, the police, and school). And these data were analyzed by SPSS 23 version. Results: Based on these data, the results of analysis were as follows; First, the innovation-oriented organizational culture which was recognized by organizational members had effect on job-stress. Second, the innovation-oriented organizational culture which was recognized by organizational members influenced job-stress. Third, in the relationship between the innovation-oriented organizational culture and job-engagement, self-efficacy did not influenced job-engagement. Finally, in the relationship between the innovation-oriented organizational culture and job-stress, self-efficacy influenced job-stress. Conclusions: Innovation-oriented organizational culture places importance on the organization's adaptability and flexibility in the external environment, so companies need to establish an innovation-oriented organizational culture favorable to achieving survival and successful innovation, and to develop and disseminate programs of positive and continuous organizations to improve task enthusiasm, reduce task stress, and enhance organizational performance. In the future, it will be necessary to verify the effectiveness of various organizational culture types through comparative analysis with companies that actively maintain an innovation-oriented organizational culture (Google, Kakao, etc.) and companies that prefer hierarchy-oriented organizational culture, relationship-oriented organizational culture, and market-oriented organizational culture.

• 한국생활과학회지
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• 제12권4호
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• pp.433-447
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• 2003

Since self-efficacy was suggested by Bandura(1977) as the most important factor that affects human behavior, preceding studies about self-efficacy are frequently related with children, and it is a main stream that only personal factors are chosen as related factors of these studies. Considering we don't have enough studies about family factors that reflect qualitative and relational factors of adolescents' home background, this study was aimed to seize the actual condition of self-efficacy meaning perceived and emotional faith about their own ability. These are our major concerns: 1. What kind of tendency does self-efficacy and appearance stress of adolescents, family functioning show? 2. How strong are relative influences of variables on self-efficacy of adolescents? This study was operated on July and August, 2002, aimed 378 middle school and high school students in Jeon-Nam, Mokpo area. 378 question sheets were used for analysis. Followings are results of this study. First, aimed students' average mark of self-efficacy was 2.09, which meant a normal level. And in low-ranked part, self-control-efficacy was the highest, and confidence task difficulty preference was following. Furthermore, whole self-efficacy showed a little difference from the demographic factor of adolescents. In low-ranked part, however, confidence and self-efficacy showed a somewhat difference. As students grew up, confidence decreased, and male students showed higher self-control-efficacy than female ones. Second, appearance stress and family functioning degree had a strong relation with self-efficacy. Family functioning, had important interrelation not only with whole self-efficacy but also with low-ranked part of self-efficacy. In low-ranked part, self-control-efficacy and task difficulty preference were proportional to the family functioning degree. From these results, we can find that the appearance stress was an actual factor that affected the self-efficacy of adolescents, and their self-efficacy was strongly related with family functioning degree. Accordingly, affirmative emotion in family, harmonic communication among family members and sharing housekeeping works had an immediate influence on elevation of self-efficacy.

• 대한약침학회지
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• 제20권1호
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• pp.5-9
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• 2017

Objectives: Gan Mai Da Zao (GMDZ) decoction is widely used for the treatment of various diseases of the internal organ and of the central nervous system. The aim of this study is to investigate the effects of GMDZ decoction on neuropsychiatric disorders in an animal model. Methods: We searched seven databases for randomized animal studies published until April 2015: Pubmed, four Korean databases (DBpia, Oriental Medicine Advanced Searching Integrated System, Korean Studies Information Service System, and Research Information Sharing Service), and one Chinese database (China National Knowledge Infrastructure). The randomized animal studies were included if the effects of GMDZ decoction were tested on neuropsychiatric disorders. All articles were read in full and extracted predefined criteria by two independent reviewers. Results: From a total of 258 hits, six randomized controlled animal studies were included. Five studies used a Sprague Dawley rat model for acute psychological stress, post-traumatic stress disorders, and unpredictable mild stress depression whereas one study used a Kunming mouse model for prenatal depression. The results of the studies showed that GMDZ decoction improved the related outcomes. Conclusion: Regardless of the dose and concentration used, GMDZ decoction significantly improved neuropsychiatric disease-related outcomes in animal models. However, additional systematic and extensive studies should be conducted to establish a strong conclusion.

• 한국지반공학회논문집
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• 제30권4호
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• pp.5-19
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• 2014

본 논문에서는 천층블록/심층말뚝 혼합식 시멘트혼합처리 공법을 구조체적 관점에서 해석하였고, 각 방법별 특징 및 관련 거동을 분석하였다. 연속보 해석법의 경우 침하량을 매우 작게 예측하였고, 천층블록의 전단력과 휨응력은 다소 크게 예측하였다. Frame 해석법의 경우 천층블록의 부재력과 장주의 부재력은 수치해석법과 가장 근접한 거동을 예측하였지만, 장주의 침하는 작게 예측하여, 장주 반력을 이용한 별도 침하계산을 실시해야하는 것으로 나타났다. 지반아칭법과 말뚝지지전면기초해석법의 경우 장주의 하중분담율이 타방법에 비해 매우 커서 장주의 축력이 과대 예측되었다. 천층블록/심층말뚝 혼합식 시멘트혼합처리공법을 적용하면, 천층블록의 침하 및 지반반력은 중앙에서 가장 크고, 외곽에서 가장 작았다. 또한, 개량체와 지반간의 상호작용을 고려할 수 있는 해석법에서 장주 개량체가 분담하는 하중은 약 20~45% 범위를 보였고, 응력분담비는 일반적인 말뚝식 DCM 공법보다 작은 약 2.0~5.0정도의 범위를 나타내었다. 장주 두부 경계조건에 따라 최대 부재력에서는 유사하지만, 두부 구속조건에서는 장주의 위치에 따라 축력 및 연직변위는 서로 다르게 나타났다.

• 대한한의진단학회지
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• 제22권1호
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• pp.11-18
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• 2018

Objectives The incidence of degenerative diseases is increasing as society ages, and this increased the economic burden on society. Oxidative stress was also under suspicion as one of the causes. Recent studies have found that Curcuma longa Rhizoma had antioxidant, anti-inflammatory, antimutagenic, and anticancer effects. Through this study, we figure out trends in Curcuma longa Rhizoma research and evaluate the therapeutic potential of Curcuma longa Rhizoma for dementia. Methods The search was made using domestic and international internet search sites. "Naver academic," "Google scholar," "Korea institute of oriental medicine (KIOM OASIS)," "Korean traditional knowledge portal (KTKP)," "Library of Congress," "Research information sharing service (RISS)," "National Digital Science Links (NDSL)," and "Pub med" are used to search. The searched for words were "turmeric," "Curcuma longa Rhizoma," "antioxidant," and "nerve regeneration." Results It could be seen that a lot of research done on Curcuma longa recently. In previous studies, the most common research disease was cancer. In previous studies, the most common effects of Curcuma longa was antioxidant and anticancer. Curcumin, Vitamin B1, and various essential oils were the functional components of Curcuma longa Rhizoma. Curcuma longa Rhizoma performs DPPH radical scavenging activity and ABTS radical cation decolorization activity; it inhibits NO and iNOS. Conclusion The destruction of nerve cells due to oxidative stress is a cause of dementia. Curcuma longa Rhizoma have antioxidant effects. Therefore, we believed that it is an effective treatment for dementia. Various studies will be made on Curcuma longa Rhizoma.