• Journal of Power Electronics
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• 제18권1호
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• pp.212-224
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• 2018

For maintaining a reliable and secure power system, this paper describes the design and implement of a single-phase grid-connected inverter with an enhanced phase-locked loop (PLL) and excellent power control performance. For designing the enhanced PLL and power regulator, a full-bridge voltage-controlled inverter (VCI) is investigated. When the grid frequency deviates from its reference values, the output frequency of the VCI is unstable with an oscillation of 2 doubling harmonics. The reason for this oscillation is analyzed mathematically. This oscillation leads to an injection of harmonics into the grid and even causes an output active power oscillation of the VCI. For eliminating the oscillation caused by a PLL, an oscillation compensation method is proposed. With the proposed method, the VCI maintains the original PLL control characteristics and improves the PLL robustness under grid frequency deviations. On the basis of the above analysis, a power regulator with the primary frequency and voltage modulation characteristics is analyzed and designed. Meanwhile, a small-signal model of the power loops is established to determine the control parameters. The VCI can accurately output target power and has primary frequency and voltage modulation characteristics that can provide active and reactive power compensation to the grid. Finally, simulation and experimental results are given to verify the idea.

• 한국정보통신학회논문지
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• 제19권2호
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• pp.386-392
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• 2015

영상압축코덱은 데이터를 일정한 블록크기로 나누어 처리하며 블록크기로 나누어진 데이터는 필요에 따라 처리 순서가 바뀌게 되므로 블록단위의 순서 재배열을 위해서는 블록의 크기에 해당하는 데이터를 메모리에 저장한 후 새로운 순서로 읽는다. 처리 속도를 유지하기 위해서는 두 개의 메모리를 이용하여 입력 데이터를 저장하는 동시에 이전에 저장된 데이터를 읽는 방법을 사용한다. 본 논문에서는 단일 메모리를 적용한 불규칙한 입출력 순서 변환의 경우에도 주소의 변화가 유한한 갱신 횟수 안에 반복되는 예측 가능한 규칙성을 가짐을 보이고 하드웨어 구현을 위한 효율적인 방법을 제안한다. 제시한 방법은 HDL로 설계하여 TSMC 0.18 CMOS 공정 라이브러리를 이용하여 합성하였고 다양한 입출력 순서변환 스캔블록에 대해 40%이상의 면적 절감효과가 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제50권3호
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• pp.396-410
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• 2018

To assist operators to properly assess the current situation of the plant, accurate fault diagnosis methodology should be available and used. A reliable fault diagnosis method is beneficial for the safety of nuclear power plants. The major idea proposed in this work is integrating the merits of different fault diagnosis methodologies to offset their obvious disadvantages and enhance the accuracy and credibility of on-line fault diagnosis. This methodology uses the principle component analysis-based model and multi-flow model to diagnose fault type. To ensure the accuracy of results from the multi-flow model, a mechanical simulation model is implemented to do the quantitative calculation. More significantly, mechanism simulation is implemented to provide training data with fault signatures. Furthermore, one of the distance formulas in similarity measurement-Mahalanobis distance-is applied for on-line failure degree evaluation. The performance of this methodology was evaluated by applying it to the reactor coolant system of a pressurized water reactor. The results of simulation analysis show the effectiveness and accuracy of this methodology, leading to better confidence of it being integrated as a part of the computerized operator support system to assist operators in decision-making.

• 패션비즈니스
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• 제19권3호
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• pp.43-58
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• 2015

Compulsive hoarding becomes a problem when the spaces hoarded items are stored in become unusable due to clutter, health, or safety issues. Our research purpose was to document relationships between two non-normative consumer behaviors (compulsive hoarding, compulsive buying tendency) and two shopping-related variables: hedonic shopping motives and emotional attachment to possessions with everyday consumers. As hedonic shopping motives have been related to compulsive buying, we predicted these motives (e.g., adventure, gratification, role, value, social, and idea) are related to compulsive buying. We also examined the relationship between compulsive buying and compulsive hoarding tendency and whether emotional attachment to possessions moderated this relationship. Participants were 280 undergraduate and graduate students attending a Midwestern university in the U.S. Regression analysis revealed the enhancing emotion motive (a combined motive of adventure and gratification) positively influenced compulsive buying whereas the value motive negatively influenced compulsive buying. All other hedonic shopping motives were non-significant. Participants who tended to buy compulsively were likely to hoard compulsively. This relationship, however, was moderated by participants' emotional attachment to possessions. Participants with high emotional attachment to possessions showed a higher level of hoarding behavior than those with low emotional attachment to possessions. However, the increase in hoarding tendency among participants with low emotional attachment to possessions was larger between those who were low in compulsive buying and those who were high in compulsive buying than the increase between these two groups among participants with high emotional attachment to possessions.

• Journal of Korean Neurosurgical Society
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• 제60권4호
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• pp.471-474
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• 2017

Objective : The thromboembolic events during neuroendovascular therapy (NET) are the major complications of concern that can be occasionally fatal. The thrombotic occlusion of the guide catheter for NET is thought to be the risk of the thromboembolic events. We have developed an idea for inventing the monitoring system of the continuous irrigation through the guide catheter. We herein present a unique invention of the guide catheter irrigation monitoring device. Methods : We have developed ideas for preventing the thrombotic occlusion of the guide catheter. In order to design a convenient device working in the practical use, we have consulted and shared the ideas with the electrical engineers about putting the invention. Results : The guide catheter irrigation monitoring device (GCIMD) consisted of three parts of optical sensor, main body and electric adapter. In brief, the basic principles of working of the GCIMD are as follows. The optical sensor is attached to the dripping chamber of the line to irrigation solution. The main body had the small light and speaker to make an alarm sounds. The sensor monitors the dripping of flush solution. If the dripping stops more than three seconds, a warning alarm has been activated. So, the operating physicians can concentrate and check the guide catheter irrigation. After the use of the GCIMD, there was no major thromboembolic complication in conjunction with the thrombotic occlusion of the guide catheter in our institute. Conclusion : We have developed a brilliant invention of the GCIMD for NET.

• 한국정보통신학회논문지
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• 제11권5호
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• pp.889-896
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• 2007

센서기술 및 무선통신 기술의 발달로 센서네트워크에 대한 연구가 가속화되고 있다. 센서노드는 크기 및 용량의 제한 때문에 간단하면서 에너지를 효율적으로 사용할 수 있는 프로토콜을 설계하는 것이 매우 중요하다. 기존 센서네트워크용 라우팅 프로토콜로 널리 알려져 있는 directed diffusion 프로토콜은 간단하다는 장점을 갖지만 Interest/Exploratory data 메시지를 Flooding 기법에 따라 전송하게 됨에 따라 에너지 소모가 크다는 단점을 가지고 있다. 따라서 본 논문에서는 directed diffusion 기법이 가진 단점을 보완하면서 각 센서노드가 에너지를 균형 있게 소비할 수 있는 설계된 센서 네트워크 용 라우팅 기법을 제안하고 시뮬레이션을 통해 성능평가를 수행하였다. 성능평가 결과에 따르면 본 연구에서 제안한 라우팅 프로토콜이 기존 directed diffusion 기법에 비해 에너지를 훨씬 효율적으로 사용하면서 센서노드간 에너지 소비 불균형 문제를 해결하고 있음을 수치계산 결과를 통해 확인할 수 있었다.

• Coupled systems mechanics
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• 제4권4호
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• pp.279-295
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• 2015

The article presents a theoretical-experimental approach developed for modeling the coefficient of sliding friction in the dynamic system tool-workpiece in slide diamond burnishing of low-alloy unhardened steels. The experimental setup, implemented on conventional lathe, includes a specially designed device, with a straight cantilever beam as body. The beam is simultaneously loaded by bending (from transverse slide friction force) and compression (from longitudinal burnishing force), which is a reason for geometrical nonlinearity. A method, based on the idea of separation of the variables (time and metric) before establishing the differential equation of motion, has been applied for dynamic modeling of the beam elastic curve. Between the longitudinal (burnishing force) and transverse (slide friction force) forces exists a correlation defined by Coulomb's law of sliding friction. On this basis, an analytical relationship between the beam deflection and the sought friction coefficient has been obtained. In order to measure the deflection of the beam, strain gauges connected in a "full bridge" type of circuit are used. A flexible adhesive is selected, which provides an opportunity for dynamic measurements through the constructed measuring system. The signal is proportional to the beam deflection and is fed to the analog input of USB DAQ board, from where the signal enters in a purposely created virtual instrument which is developed by means of Labview. The basic characteristic of the virtual instrument is the ability to record and visualize in a real time the measured deflection. The signal sampling frequency is chosen in accordance with Nyquist-Shannon sampling theorem. In order to obtain a regression model of the friction coefficient with the participation of the diamond burnishing process parameters, an experimental design with 55 experimental points is synthesized. A regression analysis and analysis of variance have been carried out. The influence of the factors on the friction coefficient is established using sections of the hyper-surface of the friction coefficient model with the hyper-planes.

• Journal of Sport and Applied Science
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• 제5권1호
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• pp.17-26
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• 2021

Purpose: The purpose of this study is to suggest the policy and scope of the concept of sports welfare and to present a systematic model enhancing sport welfare of the society. Research design, data, and methodology: In order to induce idea for welfare policy and conceptual sport welfare model, this study reviewed a literature discussing the functions and mechanism of sport in enhancing a sense of life quality and thus rebuilding welfare of community. Results: The study suggests these. First, sports welfare ensures the rights of sports of all citizens and has the main purpose of providing social services, creating environments against inequality, improving the quality of life and happiness for everyone to enjoy, and the range should be continued from the right to live, environments against inequality, to the improvement of life and happiness. Second, since the integrated perspective was first suggested, sports integration development will be researched as well as the direction of the development of policies of the integrated model. Basic research of indicator development will need to be proceeded to execute and evaluate the integrated model. Third, the improvement of treatment of sports welfare instructors is urgent. Namely, compared to sports-related budget and the enhancement of facilities, the poor environment of sports welfare instructors needs to be improved. Instead of only testing physical fitness and prescription, the business needs to be continued by connecting to the participants' continuous participation in sports. Conclusions: Whether sports welfare succeeds depends on the need for an active beneficiary, identification of demand, a beneficiary that can discover potential to join offline and online into one, the establishment of sports policies to promote competency development, and a direct progression is needed.

• Earthquakes and Structures
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• 제15권6호
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• pp.639-654
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• 2018

Rocking motion have been used for achieving the 'resilient buildings' against earthquakes in recent studies. Low-rise buildings, unlike the tall ones, because of their small aspect ratio tend to slide rather than move in rocking mode. However, since rocking is more effective in seismic response reduction than sliding, it is desired to create rocking motion in low-rise buildings too. One way for this purpose is making the building's structure rock on its internal bay(s) by reducing the number of bays at the lower part of the building's skeleton, giving it a mushroom form. In this study 'mushroom skeleton' has been used for creating multi-story rocking regular steel buildings with square plan to rock on its one-by-one bay central lowest story. To show if this idea is effective, a set of mushroom buildings have been considered, and their seismic responses have been compared with those of their conventional counterparts, designed based on a conventional code. Also, a set of similar buildings with skeleton stronger than code requirement, to have immediate occupancy (IO) performance level, have been considered for comparison. Seismic responses, obtained by nonlinear time history analyses, using scaled three-dimensional accelerograms of selected earthquakes, show that by using appropriate 'mushroom skeleton' the seismic performance of buildings is upgraded to mostly IO level, while all of the conventional buildings experience collapse prevention (CP) level or beyond. The strong-skeleton buildings mostly present IO performance level as well, however, their base shear and absolute acceleration responses are much higher than the mushroom buildings.

• 한국융합학회논문지
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• 제10권7호
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• pp.199-211
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• 2019

본 연구는 2010년부터 2018년까지 한국연구재단의 등재학술지에 게재된 학술논문 172편을 대상으로 대학생 창업에 대한 연구동향을 분석하였다. 분석 결과, 대학생 창업 연구는 창업과 창업가로서의 특성과 창업교육 관련 연구영역과 주제에 초점을 두고 있으며, 창업의지나 기업가정신, 창업교육 등 특정 변수에 대한 변수 관계를 탐색하기 위해 통계분석을 활용한 양적연구에 치중하고 있다는 점을 확인하였다. 향후 연구에서는 창업 아이디어 발굴, 창업환경, 창업제도 등 연구영역에 대한 연구의 확장이 필요하다. 또한, 창업의지, 창업교육 및 기업가정신 등 특정 변수에 초점을 둔 것에서 벗어나 창업 관련 다양한 변수 관계를 탐색할 필요가 있다. 그리고 종속변수로서 창업의지에 영향을 미치는 변수들과의 관계에 대한 메타분석이 필요하다. 아울러, 대학생 창업과 기업가정신이 형성되는 과정과 그 과정에 영향을 미치는 요인들에 대한 이론적 구조를 탐색하고 그 구조에 대한 실증적 탐색을 하는 질적연구와 혼합연구가 활성화될 필요가 있다.