• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1319-1327
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• 2015

As wind power farm (WPF) installations continue to grow, monitoring and controlling large-scale WPFs presents new challenges. In this paper, a hierarchical network architecture is proposed in order to provide remote monitoring and control of large-scale WPFs. The network architecture consists of three levels, including the WPF comprised of wind turbines and meteorological towers, local control center (LCC) responsible for remote monitoring and control of wind turbines, and a central control center (CCC) that offers data collection and aggregation of many WPFs. Different scenarios are considered in order to evaluate the performance of the WPF communications network with its hierarchical architecture. The communications network within the WPF is regarded as the local area network (LAN) while the communication among the LCCs and the CCC happens through a wide area network (WAN). We develop a communications network model based on an OPNET modeler, and the network performance is evaluated with respect to the link bandwidth and the end-to-end delay measured for various applications. As a result, this work contributes to the design of communications networks for large-scale WPFs.

• 한국기계가공학회지
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• 제19권1호
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• pp.43-48
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• 2020

At present, 24 nuclear power plants are in operation nationwide as the main power source responsible for about 27% of Korea's electricity, and five nuclear power plants are currently under construction. Issues of nuclear safety and reliability have always existed, but after the Fukushima accident, ensuring reliability has become an even more important issue for safety. Compared to other kinds of accidents, the initial response after a nuclear accident is more important than any other accident. Prior to accidents, it is important to be able to predict and judge the accident in advance for the sake of prevention. In this research, non-destructive inspection methods for existing pipe welds include radiographic, ultrasonic, magnetic particle practice, and liquid penetration testing. For this experiment, carbon steel pipes like that of the material used in nuclear pipes were adopted, and specimen welded to the flange (Flange) were manufactured. After testing, the weld specimen were not damaged through the infrared thermography (IRT) experiment. This study attempted to improve the safety of carbon steel pipes through a comparative analysis of finite element analysis.

• 한국재료학회지
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• 제9권5호
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• pp.533-537
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• 1999

ATO(Sb doped $SnO_2$) thin films whose thicknesses were 600, 1100 and $2100\AA$ were prepared by DC magnetron sputtering method. They showed the lowest resistivity at DC sputtering power 0.24kW and had lower resistivity with increasing thickness. The power dependence of resistivity among ATO thin films was also different with thickness. The increase of carrier concentration in ATO thin films was responsible for the decrease of resistivity with thickness increase. ATO thin films which were prepared at 30sccm oxygen flow rate showed a great change of sheet resistance under 1M HCl solution. The investigation of SAM(Scanning Auger Microprobe) revealed that oxygen atomic percentage on the surface of ATO thin films was changed. The decrease of sheet resistance also occurred when ATO thin films, prepared at 30sccm oxygen flow rate, were exposed to air for a long period of time. For this reason, it was considered that the desorption of oxygen on ATO surface was accelerated by HCl.

• 대한인간공학회지
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• 제25권3호
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• pp.77-83
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• 2006

The purpose of this study is to assess the organizational types and the job stress factors that affect the procedure-based job performances in nuclear power plants(NPPs). We derived 24 organizational factors affecting to the job stress in NPPs from the job stress analysis models of NIOSH(1989), Cooper(1990), and Karasek(1990). onsidering the safety characteristic in operating tasks of NPPs, we individuate among the tasks in NPPs through the division of duty and the analysis of cost activity. Through the questionnaire survey, a structured interview with the responsible employees, and expert panels, we assess 70 tasks among 777 tasks managed officially under the procedures. They are the representative tasks to the duties of each division and are directly related to the safety. We utilize the OPTI(organizational personality type indicators) to characterize the personality type of each organization in NPPs.

• 문화기술의 융합
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• 제8권4호
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• pp.61-65
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• 2022

기업의 규모가 증대하면서 기업은 사회에 대해 매우 광범위한 영향력을 행사하고 있으나, 반면 자신의 영향력에 상용하는 책임있는 기업행동을 하지 못함에 따라 거대기업은 커다란 사회문제를 야기시키는 무책임한 사회조직으로 비난받기도 한다. 본 연구에서는 기업활동과 관련된 사회적 문제가 발생하게 되는 근본적인 배경으로서 ESG와 기업권력과의 문제를 검토해 보고, 기업과 사회 분야에서 전통적으로 논의되어 온 기업의 사회적 책임문제에 대해 연구한다.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.207-219
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• 2022

The suppression of high-intensity blob structures in the scrape-off layer (SOL) by ion-cyclotron range of frequencies (ICRF) power, leading to a decrease in the turbulent fluctuation level, is observed first in the Experimental Advanced Superconducting Tokamak (EAST) experiment. This suppression effect from ICRF power injection is global in the whole SOL at EAST, i.e. blob structures both in the regions that are magnetically connected to the active ICRF launcher and in the regions that are not connected to the active ICRF launcher could be suppressed by ICRF power. However, more ICRF power is required to reach the full blob structure suppression effect in the regions that are magnetically unconnected to the active launcher than in the regions that are magnetically connected to the active launcher. Studies show that a possible reason for the blob suppression could be the enhanced E_r × B shear flow in the SOL, which is supported by the shaper radial gradient in the floating potential profiles sensed by the divertor probe arrays with increasing ICRF power. The local RF wave power unabsorbed by the core plasma is responsible for the modification of potential profiles in the SOL regions.

• 한국시스템다이내믹스연구
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• 제2권2호
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• pp.25-40
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• 2001

This paper describes the forecast of power plant construction in a competitive korean electricity market. In Korea, KEPCO (Korea Electric Power Corporation, fully controlled by government) was responsible for from the production of the electricity to the sale of electricity to customer. However, the generation part is separated from KEPCO and six generation companies were established for whole sale competition from April 1st, 2001. The generation companies consist of five fossil power companies and one nuclear power company in Korea at present time. Fossil power companies are scheduled to be sold to private companies including foreign investors. Nuclear power company is owned and controlled by government. The competition in generation market will start from 2003. ISO (Independence System Operator will purchase the electricity from the power exchange market. The market price is determined by the SMP(System Marginal Price) which is decided by the balance between demand and supply of electricity in power exchange market. Under this uncertain circumstance, the energy policy planners such as government are interested to the construction of the power plant in the future. These interests are accelerated due to the recent shortage of electricity supply in California. In the competitive market, investors are no longer interested in the investment for the capital intensive, long lead time generating technologies such as nuclear and coal plants. Large unclear and coal plants were no longer the top choices. Instead, investors in the competitive market are interested in smaller, more efficient, cheaper, cleaner technologies such as CCGT(Combined Cycle Gas Turbine). Electricity is treated as commodity in the competitive market. The investors behavior in the commodity market shows that the new investment decision is made when the market price exceeds the sum of capital cost and variable cost of the new facility and the existing facility utilization depends on the marginal cost of the facility. This investors behavior can be applied to the new investments for the power plant. Under these postulations, there is the potential for power plant construction to appear in waves causing alternating periods of over and under supply of electricity like commodity production or real estate production. A computer model was developed to sturdy the possibility that construction will appear in waves of boom and bust in Korean electricity market. This model was constructed using System Dynamics method pioneered by Forrester(MIT, 1961) and explained in recent text by Sternman (Business Dynamics, MIT, 2000) and the recent work by Andrew Ford(Energy Policy, 1999). This model was designed based on the Energy Policy results(Ford, 1999) with parameters for loads and resources in Korea. This Korea Market Model was developed and tested in a small scale project to demonstrate the usefulness of the System Dynamics approach. Korea electricity market is isolated and not allowed to import electricity from outsides. In this model, the base load such as unclear and large coal power plant are assumed to be user specified investment and only CCGT is selected for new investment by investors in the market. This model may be used to learn if government investment in new unclear plants could compensate for the unstable actions of private developers. This model can be used to test the policy focused on the role of unclear investments over time. This model also can be used to test whether the future power plant construction can meet the government targets for the mix of generating resources and to test whether to maintain stable price in the spot market.

• 한국실내디자인학회논문집
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• 제13호
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• pp.60-71
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• 1997

A study was performed for combination active process between the academical theory and practical design process based on creative thinking process in interior desigv. At first, it was investigated the concepts and characteristics of creativity combined with creativite process of thinking, and also scientific and art characteristics on interior design to be educated together with logical and esthetical concepts required for creative thinking process. In reference with above process, it was systematically established stepwise process of interior design with creative thinking system. As a resualt, creativity in interior design could develop a unique design process combined informations about knowledge and experiences with actual acquirements by individual's experiences. So interior design could be approachable and developed with open-mind and consistently scientific methodology. Also creativity power of interior design could be solved by strategic knowledge acquired by practical experiences and problem solving capability in special branches. Like this, all design activities, including interior design, would be accomplished theoretical background and actual design process under the concepts of practical intension and use. So it would be made creative products by means of detail adapation process based on the theoretical atmosphere, therefore it'll be strongly based on the hardnessing of theoretical value and power. Theory for design process referred to environmental concepts, so including interior design, would not be terminated as for theoretical concepts but be responsible for future of well-developed design by accomplishment of various design adaption method for practical purpose and objectives.

• Wind and Structures
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• 제17권2호
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• pp.227-244
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• 2013

Non-stationary extreme winds such as thunderstorm downbursts are responsible for many structural damages. This research presents a time domain approach for estimating along-wind load effects on tall buildings using multiple wind speed time history samples, which are simulated from evolutionary power spectra density (EPSD) functions of non-stationary wind fluctuations using the method developed by the authors' earlier research. The influence of transient wind loads on various responses including time-varying mean, root-mean-square value and peak factor is also studied. Furthermore, a simplified model is proposed to describe the non-stationary wind fluctuation as a uniformly modulated process with a modulation function following the time-varying mean. Finally, the probabilistic extreme response and peak factor are quantified based on the up-crossing theory of non-stationary process. As compared to the time domain response analysis using limited samples of wind record, usually one sample, the analysis using multiple samples presented in this study will provide more statistical information of responses. The time domain simulation also facilitates consideration of nonlinearities of structural and wind load characteristics over previous frequency domain analysis.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.4665-4671
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• 2013

엔진 설치 시스템은 차량의 NVH 성능에 매우 중요한 시스템 이다. 차량의 NVH 성능은 공회전 진동(Idle Vibration), 엔진 쉐이크(Engine Shake) 시동 진동(Key ON/OFF Vibration), 변속 진동(Gear Shift Vibration) 등 다양한 이론이 존재한다. NVH 성능 개선을 위해 이러한 이론들에 대한 실제적 최적화가 필요하며, 특히 최적의 엔진 설치 위치와 강성을 찾아내는 것이 매우 중요하다. 또한 효과적인 NVH 성능 개선을 위하여 차량개발 프로세스 측면에서 제약조건과 한계가 있는 사후 조정보다는 개발 초기에 최적화가 필요하다. 본 논문에서는 엔진 설치 시스템 관련 여러 이론에 대한 최적화 해석과 파워 트레인의 엄격한 모드 분리와 토크롤축(Torque Roll Axis), 탄성롤축(Elastic Roll Axis) 사이의 각도를 최소화 하는 다양한 시뮬레이션 케이스(Simulation Case)와 FE-모드를 개발초기에 수행하여 다중 최적화 분석을 함으로서 최적의 엔진 설치 위치와 강성을 찾아내어 NVH 성능을 개선하였다.