• 조명전기설비학회논문지
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• 제14권2호
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• pp.68-74
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• 2000

본 논문에샤는 동축형 전극구조 변화시의 중첨방전에 의해 발생되는 오존의 농도 효율 및 발생량 특생에 대해서 논했다. 오존생정올 향상시키기 위해 오존방전환의 새로운 형태를 제안하였으며 연면방전과 무성방전이 동시에 분리된 방전공간내에서 발생하도록 하였다. 전극구조에 대한 오존발생 의존성을 조사하지 워해 구조가 다른 형태(2전극-1캡,3전극-2캡 및 3전극-3캡형)인 방전관올 설계.제작하였고 실험은 오존발생특성을 살펴보지 위하여 60[Hz] 전원을 사용하여 무성방전과 연면반전을 같은 갭내에 중첩시켜 측정한 결과 무성방전을 이용한 전극구조보다 중첩방전올 이용한 전극에서 오존의 농도, 효율 및 발생량이 향상됨율 확인할 수 있었다.

• Journal of Power Electronics
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• 제16권6호
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• pp.2243-2257
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• 2016

This paper presents a two stage three-phase proton exchange membrane fuel cell (PEMFC) generation system. When the system is connected to a three-phase load, it is very sensitive to the characteristics and type of the load. Especially unbalanced three-phase loads, which result in a pulsating power that is twice the output frequency at the inverter output, and cause the dc-link to generate low frequency ripples. This penetrates to the fuel cell side through the front-end dc-dc converter, which makes the fuel cell work in an unsafe condition and degrades its lifespan. In this paper, the generation and propagation mechanism of low frequency ripple is analyzed and its impact on fuel cells is presented based on the PEMFC output characteristics model. Then a novel method to evaluate low frequency current ripple control capability is investigated. Moreover, a control scheme with bandpass filter inserted into the current feed-forward path, and ripple duty ratio compensation based on current mode control with notch filter is also proposed to achieve low frequency ripple suppression and dynamic characteristics improvement during load transients. Finally, different control methods are verified and compared by simulation and experimental results.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 창립 20주년기념 특별학술발표회
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• pp.189-190
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• 2009

• 한국초등과학교육학회지:초등과학교육
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• 제25권3호
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• pp.257-270
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• 2006

The purpose of this study was to develop elementary students' ability to generate hypothesis knowledge through knowledge generation learning in science. The learning program consisted of a series of 28 activities to generate hypotheses in science. Eighty 6th grade students participated in the study and were divided into experimental and control groups. The experimental group was administered a program geared towards hypothesis generation learning and the control group was administered a program aimed at hypothesis expository learning in elementary science. After using the respective programs, subjects in both groups were tested in terms of their abilities in abductive knowledge generation and administered a descriptive self-report regarding their generation of hypotheses. Two of the 28 activity program worksheets in the experimental group were analyzed in terms of the quality and process of students' hypothesis generation. The results were as follows: 1) The experimental group showed significantly higher scores in terms of scientific knowledge generation (i.e. abductive knowledge generation) than the control group. 2) The degree of hypothesis explanation in the experimental group was significantly higher than in the control group in terms of the quality of the generated hypotheses. In addition, students in the experimental group generated more varied and valid knowledge than the control group in terms of sub-knowledge of hypothesis generation. Therefore, it can be argued that this program for hypothesis knowledge generation in elementary science students was effective in the generation of hypothesis knowledge.

• 상하수도학회지
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• 제10권3호
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• pp.83-91
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• 1996

The pulverized wastes originated from kitchen garbage grinder cause an additional load in sewage treatment plant and water environment. Therefore, several problems occur in sewer, such as microbial corrosion, odor, psychoda and fly interrupting flow of sewage etc. by their precipitation with earth and sand. This study was conducted on two experiments: hydrogen sulfide gas generation from sediments in sewer and anaerobic batch test. In anaerobic batch test, gas generation was increased when organic compounds were increased in concentration. Sulfide was decreased upon decreasing in sulfate concentration. In $H_2S$ gas generation test along the depth of sediments there were two different sampling sites which are apart from about 50 cm each other in a menhole. The one has the thickness of 55 cm from the surface, the other, of 60 cm. The hydrogen sulfide gas production rates were measured based on ranges from 0 to 10 cm, 10 to 20 cm, 20 to 30 cm for two samples. The results obtained were 1.08, between 0 to 10 cm in depth for the sample thickness of 55 cm and 3.07, 5.36, $5.42{\mu}g/g-VS{\cdot}hr$ in order of depth for the sample thickness of 60 cm, respectively.

• 한국의류학회지
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• 제21권2호
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• pp.333-345
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• 1997

The purposes of this study were 1) to identify the differences between the sexes in the perception of sexuality in jeans fashion advertising, 2) to find out the differences between the high and low sexy advertisements and the differences between the groups which had different orientation of the characteristics of new young generation in preferences of advertisements and intentions to purchase product in sexy fashion advertising. The data were collected using questionnairs which contained nine advertisements of Guess Jeans, from 441 college students (female= 225, male= 216) living in Seoul, Korea participated in the study and the data were and analyzed by paired 1·test and t-test. The results of this study were as follows: First, there were significant differences between male and female in the perceptions of sexuality in jeans advertisements. Second, by paired t-test, male preferred highly sexy advertisement to low sexy advertisement, and female's intention to purchase product was higher in the advertisement of high sex appeal than that of low sex appeal. Third, there were partially significant diferences between two groups which had different orientation of the characteristics of new young generation in preferences of sexy advitisements. The differences of intentions to purchase product between two groups were significant in highly sexual advertising. But in low sexual advertising, the significant differences between two groups were not found in advertisement preferences and intentions to purchase products.

• 대기
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• 제18권3호
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• pp.207-224
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• 2008

Severe downslope windstorms observed at Gangneung, Korea in the springtime during the last 30 years are studied to understand their generation mechanisms. 92 severe wind cases are selected for which the maximum instantaneous wind speeds exceed two standard deviation of total mean plus ($18.7ms^{-1}$). They are categorized into the three mechanisms (hydraulic jump, partial reflection, and critical-level reflection) proposed in previous studies based on the flow condition, which is calculated using the wind and temperature profile observed at one upstream rawinsonde station, Osan. Among the three, partial reflection is found to be the most frequent mechanism for the last 30 years (1976 - 2005). To understand the role of inversion in generating severe downslope windstorms, horizontal velocity perturbation was calculated analytically for the atmosphere with an inversion layer. It turned out that the intensity of downslope wind was increased by inversion layer of specific heights, which are well matched with the observations. For better understanding the generation mechanisms, two-dimensional numerical simulations are conducted for the 92 severe wind cases using the ARPS model. In most simulations, surface wind speed exceeds the value of the severe-wind criterion, and each simulated case can be explained by its own generation mechanism. However, in most simulations, the simulated surface wind speed is larger than the observed, due to ignoring the flow-splitting effect in the two-dimensional framework.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1283-1286
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• 2005

Multimodal optimization is one of the most interesting topics in evolutionary computational discipline. Simple genetic algorithm, a basic and good-performance genetic algorithm, shows bad performance on multimodal problems, taking long generation time to obtain the optimum, converging on the local extrema in early generation. In this paper, we propose a new genetic algorithm with two new genetic mutational operators, i.e. global and local mutation operators, and no genetic crossover. The proposed algorithm is similar to Simple GA and the two genetic operators are as simple as the conventional mutation. They just mutate the genes from left or right end of a chromosome till the randomly selected gene is replaced. In fact, two operators are identical with each other except for the direction where they are applied. Their roles of shaking the population (global searching) and fine tuning (local searching) make the diversity of the individuals being maintained through the entire generation. The proposed algorithm is, therefore, robust and powerful.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권11호
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• pp.5563-5582
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• 2016

Parametric min-cuts is an object proposal algorithm, which can be used for accurate image segmentation. In parametric min-cuts, foreground seeds generation plays an important role since the number and quality of foreground seeds have great effect on its efficiency and accuracy. To improve the performance of parametric min-cuts, this paper proposes a new framework for foreground seeds generation. First, to increase the odds of finding objects, saliency detection at multiple scales is used to generate a large set of diverse candidate seeds. Second, to further select good-quality seeds, a two-stage cascaded ranking classifier is used to filter and rank the candidates based on their appearance features. Experimental results show that parametric min-cuts using our seeding strategy can obtain a relative small pool of proposals with high accuracy.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.951-957
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• 2010

An optimal path generation method considering the safety of UGV(Unmanned Ground Vehicle) is proposed and demonstrated through examples. Among various functions of UGV, real-time obstacle avoidance is a key issue to realize realistic scenario in FCS(Future Combat Systems). A two-dimensional narrow corridor environment is considered as a test field. For each step of UGV movement, two objectives are considered: One is to minimize the distance to the target and the other to maximize the distance to the nearest point of an obstacle. A weighted objective function is used in the optimization problem. Equality and inequality constraints are taken to secure the UGV's dynamics and safety. The weighting factors are controlled by a fuzzy controller which is constructed by a fuzzy rule set and membership functions. Simulations are performed for two cases. First the weighting factors are considered as constant values to understand the characteristics of the corresponding solutions and then as variables that are adjusted by the fuzzy controller. The results are satisfactory for realistic situations considered. The proposed optimal path generation with the fuzzy control is expected to be well applicable to real environment.