• 한국공간구조학회논문집
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• 제14권4호
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• pp.47-54
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• 2014

This paper presents the structural model development and verification processes of wind turbine blade. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine which the wind tunnel and structural test data has publicly available is used for the study. The wind turbine assembled by blades, rotor, nacelle and tower. The wind blade connected to rotor. To make the whole turbine structural model, the mass and stiffness properties of all parts should be clear and given. However the wind blade, hub, nacelle, rotor and power generating machinery parts have difficulties to define the material properties because of the composite and assembling nature of that. Nowadays to increase the power generating coefficient and cost efficiency, the highly accurate aerodynamic loading evaluating technique should be developed. The Fluid-Structure Interaction (FSI) is the emerging new way to evaluate the aerodynamic force on the rotating wind blade. To perform the FSI analysis, the fluid and structural model which are sharing the associated interface topology have to be provided. In this paper, the structural model of blade development and verifying processes have been explained for Part1. In following Part2 paper, the processes of whole turbine system will be discussing.

• 전기학회논문지
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• 제57권11호
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• pp.1954-1961
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• 2008

Microgrid usually consists of a cluster of distributed generators(DGs), energy storage systems and loads, and can operate in the grid-connected mode and the islanded mode. This paper presents detailed descriptions of two different options for controlling the active power of DGs in the microgrid. One is regulating the power injected by the unit to a desired amount(Unit output power control) and the other is to regulate the flow of active power in the feeder where the unit is installed to a constant(Feeder flow control). Frequency-droop characteristics are used to achieve good active power sharing when the microgrid operates in the islanded mode. The change in the frequency and the active power output of DGs are investigated according to the control mode and the configuration of DGs when the microgrid is disconnected from the main grid. From the analysis, this paper proposes a method to determine the droop constant of DGs operating in the feeder flow control mode. Simulation results using the PSCAD/EMTDC are presented to validate the approach, which shows good performance as opposed to the conventional one.

• 유통과학연구
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• 제18권5호
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• pp.71-81
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• 2020

Purpose: This case study illustrates the successful entry of Saudi Aramco in the Korean market and how it grows to become one of the world's largest integrated energy enterprises. Research design, data and methodology: This case investigates diverse secondary sources to examine the entry strategy of Aramco in Korea, such as several interviews including public and anonymous dialogues, periodicals, dispatches (i.e. news articles and magazines), annual reports, industrial reports, and others. Results: The main concern for the international strategic approaching of Saudi Aramco is to enter into Korean market by joint venture with SsangYong Oil (today's S-Oil Corporation) in 1991 and finally, ending by Acquisition of S-Oil in 2015. This acquisition of local No.3 company, S-Oil, in Korea is the successful case in Asian Markets overcoming liability of foreignness. Moreover, Saudi Aramco's global distribution strategy through localization in the Korean market is appropriate given the market conditions, timing, effectiveness, and efficiency by sharing their resources and collaborating. Conclusions: It would be valuable, unique, and real story to analyze global leading company's entry and globalization strategy in overseas market. In addition, this study provides decision-makers with a significant and more strategic implication for the overseas expansion of businesses.

• Nuclear Engineering and Technology
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• 제41권8호
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• pp.1005-1014
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• 2009

The Dual Unit Optimizer 2000 MWe (DUO2000) is put forward as a new design concept for large power nuclear plants to cope with economic and safety challenges facing the $21^{st}$ century green and sustainable energy industry. DUO2000 is home to two nuclear steam supply systems (NSSSs) of the Optimized Power Reactor 1000 MWe (OPR1000)-like pressurized water reactor (PWR) in single containment so as to double the capacity of the plant. The idea behind DUO may as well be extended to combining any number of NSSSs of PWRs or pressurized heavy water reactors (PHWRs), or even boiling water reactors (BWRs). Once proven in water reactors, the technology may even be expanded to gas cooled, liquid metal cooled, and molten salt cooled reactors. With its in-vessel retention external reactor vessel cooling (IVR-ERVC) as severe accident management strategy, DUO can not only put the single most querulous PWR safety issue to an end, but also pave the way to very promising large power capacity while dispensing with the huge redesigning cost for Generation III+ nuclear systems. Five prototypes are presented for the DUO2000, and their respective advantages and drawbacks are considered. The strengths include, but are not necessarily limited to, reducing the cost of construction by decreasing the number of containment buildings from two to one, minimizing the cost of NSSS and control systems by sharing between the dual units, and lessening the maintenance cost by uniting the NSSS, just to name the few. The latent threats are discussed as well.

• 한국주거학회논문집
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• 제24권6호
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• pp.189-197
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• 2013

The purpose of the study was to analyze the improvement elements depended on housing quality measurement tool related to mental health. The data for the analysis was collected through questionnaire survey method from November 1, 2012 to January 17, 2013, and the sample consisted of 720 respondents living in single detached houses, multi-families detached houses, apartments, and town houses in 4 cities, Seoul, Busan, Daejeon, and Kwangju. The data were analyzed using descriptive statistics. The results of improvement elements are as follows: 1) Pedestrian-threaten street from cars in physical safety 2) A secluded or dark spot and fear of walking at night in social security, 3) Indoor noise, outdoor noise, and evidence of abandoned trash heap/bottle in neighborhood in health & sanitation, 4) Illegal parking and heating control system in facility convenience, 5) Extra kitchen, number of bathrooms, and community spaces in space convenience, 6) Openness and spaciousness of indoor room, and satisfaction of house and neighborhood in comfort, 7) Management common/sharing space in maintenance, 8) Energy saving facility and environment friendly materials use in sustainability, 9) Burden on housing cost, asset value on house, and school district in economic value, 10) Reflection of residents style, surrounding building's number of layers, and neighborhood appearance of preference in housing environment image.

• World Technopolis Review
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• 제6권1호
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• pp.2.1-2.9
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• 2017

Humanity is experiencing a very fast-paced technological evolution. As technological systems evolve exponentially, societies are becoming more global and are starting to have impacts beyond their geographic demarcations. This implies that, the actions of a person who is across the ocean from where we live could have significant impacts on our everyday lives. This article explores the complexity of globalization, identifies a number of global issues, and looks at the University and the Science and Technology Parks as potential sources of human capital to tackle current and forthcoming global challenges, ranging from new energy sources to potable water distributions. The article focuses on current efforts that are taking place across universities and science and technology parks around the world. We propose a new methodology whereby interdisciplinary work can inform the development of multidisciplinary approaches to solve some of the most complex global issues such as cyber security and educating the next generations of global leaders, providing them them with the necessary skills to be successful in a globally distributed workforce.

• 한국ITS학회 논문지
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• 제8권1호
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• pp.65-75
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• 2009

차량 애드 혹 네트웍 (VANET)은 모바일 애드혹 네트워크의 일종으로써 차량 간의 임시적인 통신을 가능케 한다. VANET의 모바일 노드는 네트웍의 일원으로 참여하면서 에너지와 자원을 사용한다. 몇몇의 노드는 다른 노드와 협력하는 대신에 자신의 이득만을 취하려고 하는 이기성을 가지고 있다. 이러한 이기성을 가진 노드들로 인해 데이터 접근성과 네트웍의 효율성이 감소하게 된다. 이 논문에서는 새로운 기법인 VANET 그룹에서 이기성을 갖고있는 노드를 제거하는 Friendship-VaR을 제안한다. Friendship-VaR은 이기성을 갖고있는 노드를 제거하고 믿을 수 있는 노드들간에 데이터 공유를 가능케 한다. Friendship-VaR는 간단한 데이터 교환을 통해 노드의 이기성 여부를 결정한다. 실험 결과는 제안한 기법이 기존의 기법에 비해 데이터 접근성이 좋아짐을 보여준다.

• 한국통신학회논문지
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• 제35권11A호
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• pp.1085-1090
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• 2010

Ultra wideband (UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geolocation, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional mobile wireless systems sharing the frequency bands such as Cellular CDMA and Korean PCS. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a direct-sequence spread-spectrum UWB source and an impulse radio UWB source, to a Cellular CDMA and K-PCS digital transmission system. The average frame error rate degradation of each system arc presented. From these experimental results, we show that in all practical cases UWB system can coexist with Cellular CDMA and K-PCS terminal without causing any dangerous interference.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.40.2-40.2
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• 2011

A Counter-rotating wind turbine is one of the new concepts that are proposed to increase the performance of a wind turbine. It has two rotors rotating in the same axis, and it is known that its power coefficient can reach to 0.64 in the ideal case. While the BEMT is widely used to analyze the aerodynamic performance of wind turbines, the analysis of the counter-rotating wind turbine by using it is limited due to the aerodynamic interaction between the two rotors. In this study, the vortex lattice method is used to consider the effect of the front rotor on the rear rotor of the counter-rotating wind turbine and calculate the aerodynamic performance of it. The power and thrust sharing in the two rotors of the counter-rotating wind turbine are predicted and the total power and thrust are compared with that of a single rotor. Moreover, the wake convection and expansion rate is also compared with that of a single rotor.

• 국제초고층학회논문집
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• 제6권4호
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• pp.297-300
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• 2017

Employers are realizing that workplaces have an immense impact on productivity. And, because people typically represent about 90% of a company's costs, even a slight improvement in productivity hits the bottom-line in a very big way. The focus is shifting away from saving money by reducing space needs or cutting energy requirements, and moving toward making the workplace friendlier and healthier. What is a healthy workplace, exactly? The answer should be clear by now. Mountains of research have expounded on this very topic, and then news outlets cover the latest discoveres ad infinitum. The problem is, research is rather dense, while the news isn't comprehensive. Office managers trying to improve workplace wellness want neither a 55-page report nor a half dozen articles to convince their landlord that their space can do better. Recognizing this gap, Harvard researchers have released a concise-yet-complete list of healthy building features. Here, we're sharing these nine features with a few insights of our own on the value of being healthy and productive. Find out: ${\bullet}$ What makes a healthy building and why is it so important ${\bullet}$ How to improve the health of your own office ${\bullet}$ What happens for your people and your bottom line when you make health a priority.