• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.125.2-125.2
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• 2003

Hepatic ischemia and reperfusion predisposes the liver to secondary stresses such as endotoxemia possibly via dysregulation of the hepatic microcirculation secondary to imbalanced regulation of vascular stress gene. In this study, we determined the effect of endotoxin on hepatic vasoregulatory gene expression in response to hepatic ischemia and reperfusion (I/R). Rats were subjected to 90 min of hepatic ischemia and 6 h of reperfusion. Lipopolysaccharide (LPS, 1 mg/kg) was injected intraperitoneally after reperfusion. (omitted)

• 플랜트 저널
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• 제15권4호
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• pp.43-51
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• 2019

배관계를 지지하는 목적으로 자주 사용되는 일체형 용접부착물은 응력집중효과로 인한 국부응력을 유발시켜 종종배관의 파손을 일으키기 때문에 사용에 각별한 주의를 요구하고 있다. 국내 원자력 발전소 배관 곡관부에 부착된 원형관의 국부응력 평가는 EPRI TR-107453에 따라 평가하고 있지만, 이의 적용에는 배관과 부착물의 크기에 관한 특정 매개변수 범위의 제한사항이 있다. 이 논문에서는 유한요소해석을 활용하여 모델들의 치수를 기반으로 한 매개변수 연구를 수행하여 기술적 근거를 확립하고 연구 결과에 대한 회귀분석을 통해 확장된 매개변수 범위를 갖는 곡관부에 부착된 원형관 이음부의 이차응력지수 산출 상관관계식을 도출하였다. 본 연구를 통해 개발된 새로운 상관관계식에 대한 검증을 통해 현재 평가기준의 대체 기준으로써 적용할 것을 제안한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.344-349
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• 2008

Ratcheting behavior of IN 718 was investigated at $649^{\circ}C$ under various proportional and non-proportional loading conditions with stress control. The material response was initially elastic but substantial plastic strain was developed as the material softened cyclically. Ratcheting strain was measured to near fatigue life, and is found to have three stages of development - primary, secondary (steady-state) and tertiary. The secondary stage dominates for most cases. Under the same equivalent stress amplitude and mean stress, it was revealed that circular path loading gives higher ratcheting rates and shorter lives than linear paths and that the more ratcheting occurs when the cyclic load is in the same direction as the mean stress. The ratcheting strain at failure depends not only on its rate but also on fatigue life itself, and it is not a primary life-determining factor.

• 한국해양공학회지
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• 제18권1호
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• pp.22-27
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• 2004

An orthotropic steel deck system is widely adapted form for a long-span bridge. It has many advantages, such as the big reduction of dead weight, the simplicity for erection, and the reduction of the construction period. However, an orthotropic steel deck system requires a lot of welding work, which may result in defects and deformation of connection. Therefore, the research for the general behavior and fatigue strength of the several details in orthotropic steel deck bridge is necessary. The fatigue failure with distortion results from secondary stress by out-of-plane deformation; these kinds of cracks are very difficult to measure, and can not be precisely calculated through finite element analysis. This stress concentration phenomenon generates the fatigue failure around the lower scallop of the transverse rib. This paper presents improved details of the intersection between the longitudinal rib and the transverse rib of an orthotropic steel deck bridge by the third dimensional hit size test, and the finite element method, which can minimize local stress through parametric study.

• International Journal of Knowledge Content Development & Technology
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• 제9권4호
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• pp.7-29
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• 2019

The study was carried out to investigate the influence of demographics and social media use on perceived academic stress of secondary school students in St. Thomas Aquinas College, Akure, Nigeria. This was achieved using five research questions and four null hypotheses. The population of the study consisted of 1,107 students at ISCED level 3, out of which 286 were selected based on the Israel (2003) model for determining sample size. The Ex-Post Facto (EPT) research design of the correlational type was employed to investigate the study while questionnaire was used for data elicitation. Out of the 286 copies distributed, 192 (67% response rate) were retrieved and analyzed using descriptive statistics (frequency, percentage, mean and standard deviation) and inferential statistics (correlation and multiple regression). The findings revealed that there is high frequency of social media use among secondary school students, majorly for meeting new friends and chatting. The perceived academic stress (PAS) of the students was found to be moderate. Of the three demographics considered, only class had significant influence on PAS. Use of social media did not have significantly influence on PAS of the students. When combined, demographics and social media use predicted PAS; and when considered relatively, of the independent variables, only class as an aspect of demographics predicted PAS. Therefore, the authors concluded that PAS of secondary school students is not directly influenced by demographics (except for class) and social media use. Based on the study's conclusion, recommendations were made.

• 한국사회복지학
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• 제69권2호
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• pp.219-246
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• 2017

본 연구는 트라우마 센터에 근무한 사회복지사들의 소진과 이차적 외상 스트레스 경험을 이해하기 위한 실체 이론 개발을 목적으로 한다. 근거이론을 통해 자료를 분석한 결과, 초기코딩을 통해서 159개의 의미단위, 47개의 하위범주, 그리고 12개의 범주를 구성하였다. 초점 코딩에서 중심현상을 '상처받은 존재성'으로 보고 '사회복지사로서의 자리 찾기'를 핵심범주로 정하였으며 이를 중심으로 연관된 범주들을 연결하였다. 이론적 코딩 결과 트라우마 센터에서 근무한 사회복지사의 소진과 이차적 외상 스트레스 경험 과정은 사명기, 갈등기, 침체기, 해체기로 나타났다. 이러한 연구 결과를 바탕으로 재난복지실천에 대한 준비, 트라우마 치유 관점에 대한 논의 및 합의, 그리고 소진과 이차적 외상 스트레스 예방과 대처를 위한 프로그램의 필요성을 제시하였다.

• 디지털융복합연구
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• 제15권11호
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• pp.297-305
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• 2017

2차 병원 신규간호사의 직무스트레스와 자아탄력성이 간호업무성과에 미치는 영향을 규명하기 위한 서술적 조사연구이다. 연구대상은 일 지역 6개의 2차 병원에 재직 중인 6개월 이상의 신규간호사 198명으로 편의표집하였고 2016년 2월 10일부터 4월 30일까지 자료수집을 하였다. 연구 결과 대상자의 간호업무성과정도는 높게 나타났고, 직무스트레스 정도와 자아탄력성 정도는 중간 정도로 나타났다. 대상자의 직무스트레스와 간호업무성과는 음의 상관관계가 있는 것으로 나타났고, 대상자의 자아탄력성과 간호업무성과는 양의 상관관계가 있는 것으로 나타났다. 대상자의 간호업무성과 정도에 가장 영향을 미치는 요인은 자아탄력성 정도, 직무스트레스 정도, 간호학을 택한 동기 순이었으며, 전체 설명력은 33.6%이었다. 따라서 2차 병원 신규간호사의 간호업무성과를 향상시키기 위해서는 2차 병원 신규간호사의 직무스트레스를 줄이고 자아탄력성을 증진시키는 프로그램의 개발과 적용이 필요하다고 사료된다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.381-384
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• 2008

The purpose of this study is to evaluate influence factors of secondary traumatic stress, burnout, and physical symptoms which were experienced by fire fighters. The questionnaire research was done for field service fire fighters who work in Korea. I analyzed 358 questionnaires and the questionnaires consisted of stress scale, work force, burden of physical symptoms, and self-control to stress. Through this study I will propose the solution for the posttraumatic stress disorder(PTSD) for the near future.

• Journal of Power Electronics
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• 제13권2호
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• pp.177-185
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• 2013

This paper studies a soft switching DC/DC converter to achieve zero voltage switching (ZVS) for all switches under a wide range of load condition and input voltage. Two three-level PWM circuits with the same power switches are adopted to reduce the voltage stress of MOSFETs at $V_{in}/2$ and achieve load current sharing. Thus, the current stress and power rating of power semiconductors at the secondary side are reduced. The series-connected transformers are adopted in each three-level circuit. Each transformer can be operated as an inductor to smooth the output current or a transformer to achieve the electric isolation and power transfer from the input side to the output side. Therefore, no output inductor is needed at the secondary side. Two center-tapped rectifiers connected in parallel are used at the secondary side to achieve load current sharing. Due to the resonant behavior by the resonant inductance and resonant capacitance at the transition interval, all switches are turned on at ZVS. Experiments based on a 1kW prototype are provided to verify the performance of proposed converter.

• ALGAE
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• 제32권3호
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• pp.245-259
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• 2017

We report on the culture growth and stress-induced secondary carotenogenesis in a biotechnologically promising but largely unexplored chlorophyte Coelastrella rubescens strain Vinatzer/Innsbruck V 195. Changes in the cell morphometry, biomass accumulation, its carotenoid and fatty acid profiles were followed in the cultures supplemented with either inorganic ($CO_2$) or organic (sodium acetate) carbon on the background of low-pH stress. Collectively, the results of the study characterize C. rubescens as a biotechnologically promising, potentially double-purpose organism. It produces several secondary keto-carotenoids with a considerable proportion of astaxanthin and canthaxanthin. At the same time, the cell lipid fatty acid profile of this microalga is suitable for obtaining a high-quality biodiesel complying with the strictest EN14214 European standard.