• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.838-846
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• 2015

This paper deals with the modified modeling of PV system based on the PSCAD/EMTDC and optimal control method of customer voltages in real distribution system interconnected with the photovoltaic (PV) systems. In order to analyze voltage variation characteristics, the specific modeling of PV system which contains the theory of d-q transformation, current-control algorithm and sinusoidal PWM method is being required. However, the conventional modeling of PV system can only perform the modeling of small-scale active power of less than 60 [kW]. Therefore, this paper presents a modified modeling that can perform the large-scale active power of more than 1 [MW]. And also, this paper proposes the optimal operation method of step voltage regulator (SVR) in order to solve the voltage variation problem when the PV systems are interconnected with the distribution feeders. From the simulation results, it is confirmed that this paper is effective tool for voltage analysis in distribution system with PV systems.

• Journal of East Asia Management
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• 제5권1호
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• pp.75-90
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• 2024

About 100 years after the start of mass production by American car maker Ford in 1913, the automobile industry has come to a major transformation in 100 years. In this transformation period, automakers are facing the biggest challenge of converting power sources, the basis of automobiles, from existing internal combustion engines to electric vehicles. Hybrid vehicles have been released in Japan since the late 1990s, and changes in automobile power sources have occurred early. In order to gain global leadership in hybrid vehicles, Japanese automakers and the Japanese government joined forces to promote the growth of the domestic hybrid vehicle market. The government has implemented a policy to substantially subsidize the high price of hybrid cars compared to internal combustion engine cars by providing purchase subsidies and tax benefits to buyers. Toyota has increased its line-up of hybrid cars around the Prius and has further strengthened communication with customers for the sale of hybrid vehicles. As a result of continuing these efforts for about 20 years, the percentage of Japan's hybrid vehicle market in 2022 reached 51% for passenger cars. Recently, each country has been setting and promoting aggressive goals for electric vehicles that require a wider range of physical and institutional infrastructure than hybrid vehicles. This study aims to assess the growth of electric vehicles by looking at the trend of hybrid vehicles and how they've been distributed in the Japanese market.

• Korean Chemical Engineering Research
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• 제51권1호
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• pp.1-9
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• 2013

제올라이트 촉매를 이용한 알킬 방향족 화합물의 전환은 현대 석유화학 산업에서 큰 비중을 차지한다. 본 총설에서는 제올라이트의 구조적 물리화학적 특성에 따른 알킬 방향족 화합물 전환 반응의 기구에 대해 고찰하였다. 제올라이트의 형상선택성은 알킬 방향족 화합물 전환에 있어서 반응중간체의 생성을 조절함으로써 반응 기구 및 생성물 분포에 직접적인 영향을 미친다. 다양한 알킬 방향족 화합물의 전환 반응에 대하여 반응 중간체의 구조 및 역할에 대한 고찰을 통해 지금까지 알려진 반응기구들을 정리하였다. 아울러 제올라이트 촉매를 기초로 하는 향후 석유화학 공정 개발에 대한 전망을 기술하였다.

• Asian Journal of Innovation and Policy
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• 제6권2호
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• pp.152-169
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• 2017

In this paper, we analyze the basic research system in South Korea. We propose a national basic research system consisting of value, openness, input, transformation, and output. Based on this framework, we set up interview questionnaires, and 15 key informants have been interviewed. According to our results, first, in terms of value, basic research is recognized as an activity for creating knowledge in the understanding of nature. Second, as for openness, scientists and policy experts agree that active interaction with the global community is an important value for the national research system. Third, in terms of sustainable research resources, scientists are strongly required to effectively allocate research funding, maximizing the creativity of researchers and the efficient sharing of research equipment. Fourth, in transformation, basic researchers maintain that the Korean research system has is extremly dependent on the government's external control, and its self-regulative system has been weak for over half century onw. Fifth, for global competitiveness, the interviewees agreed that the quality of basic research in Korea is approaching that of its global competitors. Finally, we put forward some policy implications on the basis of these findings.

• 한국가금학회지
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• 제34권1호
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• pp.57-76
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• 2007

Marek's disease (MD) is caused by a ubiquitous, lymphotropic alphaherpesvirus, MD virus (MDV). MD has been a major concern in the poultry industry due to the emergence of increasingly virulent strains over the last few decades that were isolated in the face of comprehensive vaccination. MD is characterized by a variety of clinical signs, amongst them neurological symptoms, chronic wasting, and most notably the development of multiple lymphomas that manifest as solid tumors in the viscera and musculature. Much work has been devoted to study MD-induced oncogenesis and genes involved in this process. Among the many genes encoded by MDV, a number have recently been shown to affect the development of tumors in chickens, one protein directly causing transformation of cells (Meq) and another being involved in maintaining transformed cells (vTR). Other MDV gene products modulate and are involved in early lytic in vivo replication, thereby increasing the chance of transformation occurring. In this review, specific genes encoded by MDV that are involved in the initiation and/or maintenance of transformation were briefly summarized, and limits of current vaccination and new control strategies against MD, particularly how modem molecular biological methods may be used to improve strategies to combat the disease in the future, were discussed.

• 융합보안논문지
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• 제22권2호
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• pp.27-42
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• 2022

4차 산업혁명 시대에는 산업혁신이라는 목표를 달성하기 위해 기존 산업의 생산성을 높일 수 있는 디지털 전환이 더욱 중요해지고 있다. 디지털 전환에는 디지털 뉴딜과 스마트 국방 등이 있으며, 이들은 인공지능과 빅데이터 분석기술, 사물인터넷을 이용한다. 이러한 변화는 사이버공간을 지속해서 확장함으로써 국가의 국방, 사회, 보건 등의 산업화 영역을 더 지능적인 새로운 서비스들로 혁신하고 있다. 하지만 이로 인해 업무 생산성, 효율성, 편리성, 산업 안전성 등은 강화되겠지만, 디지털 전환영역의 확대로 사이버공격에 따른 위험성 또한 지속해서 증가할 것이다. 본 고의 목표는 이러한 위협에 선제적으로 대응하기 위해 미래의 변화로 나타날 수 있는 위협시나리오를 고찰하고, 이를 해결할 근본적인 대안 중의 하나인 미래의 복합안보 상황에서 요구되는 4차 산업혁명 시대의 선제적 위협 대응 모델을 제안한다. 본고는 향후 미래 사회에서 사이버 위협에 능동적으로 대응할 사이버안보 전략과 기술 개발의 선행 연구로 활용할 수 있을 것이다.

• 한국정밀공학회지
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• 제33권7호
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• pp.551-558
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• 2016

Reduction of welding residual stress is very important in the railway industry, but calculating its distribution in structures is difficult because welding residual stress formation is influenced by various parameters. In this study, we developed a finite element model for simulating the repair welding process to recover a surface damaged rail, and conducted a series of parametric studies while varying the cooling rate and the duration of post weld heat treatment (PWHT) to find the best conditions for reducing welding residual stress level. This paper presents a three-dimensional model of the repair welding process considering the phase transformation effect implemented by the ABAQUS user subroutine, and the results of parametric studies with various cooling rates and PWHT durations. We found that heat treatment significantly reduced the residual stress on the upper rail by about 170 MPa.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.479-489
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• 2020

The purpose of this paper is to uncover whether and how contextual factors (information exchange, participation, trust in management, and training), relate to resistance to change. It also explores the mediating effect of perceived impact of change on the relations between contextual factors and resistance to change. This study is conducted in several manufacturing plants in food processing industry in Vietnam, which is implementing a top-down large-scale change - Lean transformation, adopting Total Productive Maintenance (TPM) program, to be specific. The findings suggest that all four contextual factors are negatively associated with resistance to change, in which training had the strongest impact. Also, the perceived change impact partially mediates the relationships between the four contextual factors and resistance to change. The practical implications of this paper are that employees who receive adequate, timely and useful information relating to change are less likely to show opposing behaviors towards change. Fostering trust in management among employees, and employee involvement in decision-making, also have a significant influence when addressing employee resistance to change. Employees who are well-trained, well-equipped with tools and knowledge about the change, are less likely to resist as they view the benefits of changes more significant than the risks.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1217-1224
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• 2018

Seaweeds produce antioxidants to counteract environmental stresses, and these antioxidant genes are regarded as important defense strategies for marine algae. In this study, the expression of Pyropia yezoensis (Bangiales, Rhodophyta) ascorbate peroxidase (PyAPX) and manganese-superoxide dismutase (PyMnSOD) was examined by qRT-PCR in P. yezoensis blades under abiotic stress conditions. Furthermore, the functional relevance of these genes was explored by overexpressing them in Chlamydomonas. A comparison of the different expression levels of PyAPX and PyMnSOD after exposure to each stress revealed that both genes were induced by high salt and UVB exposure, being increased approximately 3-fold after 12 h. The expression of the PyAPX and PyMnSOD genes also increased following exposure to $H_2O_2$. When these two genes were overexpressed in Chlamydomonas, the cells had a higher growth rate than control cells under conditions of hydrogen peroxide-induced oxidative stress, increased salinity, and UV exposure. These data suggest that Chlamydomonas is a suitable model for studying the function of stress genes, and that PyAPX and PyMnSOD genes are involved in the adaptation and defense against stresses that alter metabolism.

• 한국분말재료학회지
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• 제23권6호
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• pp.458-465
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• 2016

A $TiO_2$/CNT nanohybrid photocatalyst is synthesized via sol-gel route, with titanium (IV) isopropoxide and multi-walled carbon nanotubes (MWCNTs) as the starting materials. The microstructures and phase constitution of the nanohybrid $TiO_2$/CNT (0.005wt%) samples after calcination at $450^{\circ}C$, $550^{\circ}C$ and $650^{\circ}C$ in air are compared with those of pure $TiO_2$ using field-emission scanning electron microscopy and X-ray diffraction, respectively. In addition, the photocatalytic activity of the nanohybrid is compared with that of pure $TiO_2$ with regard to the degradation of methyl orange under visible light irradiation. The $TiO_2$/CNT composite exhibits a fast grain growth and phase transformation during calcination. The nanocomposite shows enhanced photocatalytic activity under visible light irradiation in comparison to pure $TiO_2$ owing to not only better adsorption capability of CNT but also effective electron transfer between $TiO_2$ and CNTs. However, the high calcination temperature of $650^{\circ}C$, regardless of addition of CNT, causes a decrease in photocatalytic activity because of grain growth and phase transformation to rutile. These results such as fast phase transformation to rutile and effective electron transfer are related to carbon doping into $TiO_2$.