• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1695-1696
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• 2006

In this paper, we designed high performance, high quality and high density switch mode power supply for precision electronics, and communication equipments. For this, we used two parallel DC-DC converters, which have opposite phases, to support proper high performance and high quality power. To reduce switching losses and make high switching frequency, active-clamp and ZVS technique were employed in each converter.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.09a
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• pp.231-234
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• 1994

Concentrated stresses due to the tunnel excavation easily cause failure around opening in the soft rock mass layer. Thus, while excavatng tunnel in the soft rock mass layerm it is very important to predict the possibility of failure or yielding zones around tunnel boundary. There are two typical methods to predict these; 1) the analysis of field monioring data and 2) numerical analysis. In this study, it was attempted to describe the time-dependent or progressive rock mass manner due to the continuous failure and fracturing caused by surrounding underground openings using the second method. In order to apply the effects of progressive failure underground, an iterative technique was used with the Hoek and Brown rock mass failure theory. By developing and simulating, three different shapes of twin tunnels, this research simulated and estimated the proper size of critical pillar width between tunnels, distributed stresses on the tunnel sides, and convergences of tunnel crowns. Moreover, results out progressive failure technique based on the Hoek and Brown theory were compared with the results out of Mohr-Coulomb theory.

• English Language & Literature Teaching
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• v.12 no.1
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• pp.103-129
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• 2006

This paper presents a case study of the effectiveness of debate class in promoting speaking skills of advanced learners. The researcher adopted English debate techniques in an English speaking class during four-week teacher training program and investigated how teachers responded to the new technique. Forty-five middle and high school teachers participated in the study and classroom observation, pre-survey, post-survey, and focus group interviews were used as the major research methods. The teacher pre-survey results presented that teachers prefer a conversation class where they can directly acquire proper sentence patterns and speaking strategies rather than spend time in performing communicative events. The results of the focus group interview and post-survey confirmed that a debate class can meet this specific teachers' needs. Most teachers responded positively to the debate classes since: 1) debate techniques are relatively new ideas to Korean teachers; 2) debate techniques require speed and accuracy in speech; thus teachers could learn to present their ideas logically and efficiently in a limited time through repeated argument exercises. The study result implies that debate technique can be an effective vehicle in an EFL context to promote advanced learners' logical thinking skills and logical English sentence structures.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.2
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• pp.111-119
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• 1995

In this paper, we propose an efficient SA(simulated annealing) algorithm for the synthesis of binary phase computer generated hologram. SA algorithm is a method to find the optimal solution through iterative technique. It is important that selecting cost function and parameters within this algorithm. The aplications of converentional SA algorithm to synthesize parameters within this algorithm. The applications of conventional SA algorithm to synthesize binary hologram have many problems because of inappropriate paramters and cost function. So, we propose a new cost function and a calculation technique of proper parameters required to achieve the optimal solution. Computer simulation results show that the proposed method is better than conventional method in terms of diffraction efficiency and reconstruction error. Also, we show the reconstructed images by the proposed method through optical esperiment.

• Korean Journal of Computational Design and Engineering
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• v.12 no.1
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• pp.58-73
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• 2007

This paper described a method for the construction of a surface through a set of nonuniform scattered points. When the shift vectors of some points as constraints on the original surface are given, those of the other points should be computed to make the new surface. To keep up the look-see and smoothness with the original surfaces, the proper relationship should be formulated between the shifts of the constraint points and those of the other points. Vector fields for 3 dimensional shift of a point on the surface are made based in the constraint shifts. Vector fields for 3 dimensional shift of a point on the surface are made based on the constraint shifts. Multilevel B-spline approximation technique was used to construct the vector field. The technique uses coarse-to-fine hierarchy of control lattices. The developed method was applied to shoe sole design system especially for grading. Using this system, a shoe sole can be modified effectively.

• Journal of Yeungnam Medical Science
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• v.33 no.2
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• pp.138-141
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• 2016

Coronary stent dislodgement during percutaneous coronary intervention, which occurs when the stent is passed through tortuous and calcified lesions, is not a rare complication. Without proper treatment, such as fixing with another stent in the coronary artery or removing the undeployed stent from the coronary artery or systemic artery system, this complication can cause serious problems. We experienced the unusual situation of a dismounted and dislodged coronary stent, in which retrograde retrieval to the radial artery was impossible during transradial coronary intervention. We report on use of a rendezvous and snare technique at the brachial artery level via femoral puncture, which resulted in resolution without surgery.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.5
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• pp.230-237
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• 2003

Current mode control has been used for DC to DC converters for over twenty years. There are many different control schemes which use the inductor current signal in one way or another to control the DC to DC converter. In this paper, the state space averaging technique is applied for the analysis of flyback type current mode control circuit. We made real converter for the guarantee of stable output characteristic and proper design of feedback circuit. The validity of proposed method is verified from test result. The improvement of stability is confirmed by sinusoidal signal injection method with isolated transformer. It is known that phase margin is sufficient and gain crossover frequency fc is early 1/5 of switching frequency, fs, from the experimental result with frequency response analyzer.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.943-947
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• 2005

This study was intended to interpose an objection about the analysis of rainfall spatial distribution without a proper standard, and offer the improved approach using 1,he geostatistical analysis method to analyze it. For this, spatially distributed daily rainfall data sets were collected for 41 weather stations in study area, and variogram and correlation analysis were conducted. In the results of correlation analysis, it was found that the longer distance between the stations reduces the correlation of the rainfall data, and maltes the characteristics of the rainfall spatial distribution. The variogram analysis shows that correlation range was less than 50 km for the 17 daily rainfall data sets of total 91 sets. It says that it involves some rike, to determine the application method for rainfall spatial distribution without some qualifications, hence the Application standards of the Rainfall Spatial Distribution Analysis Technique, were essential and that was contingent on characteristics of rainfall and landscape.

• MALSORI
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• no.56
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• pp.185-194
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• 2005

In this paper, we present POSSDM (POSTECH Situation-Based Dialogue Manager) for a spoken dialogue system using a new example and situation-based dialogue management technique for effective generation of appropriate system responses. Spoken dialogue system should generate cooperative responses to smoothly control dialogue flow with the users. We introduce a new dialogue management technique incorporating dialogue examples and situation-based rules for EPG (Electronic Program Guide) domain. For the system response inference, we automatically construct and index a dialogue example database from dialogue corpus, and the best dialogue example is retrieved for a proper system response with the query from a dialogue situation including a current user utterance, dialogue act, and discourse history. When dialogue corpus is not enough to cover the domain, we also apply manually constructed situation-based rules mainly for meta-level dialogue management.

• Journal of Conservation Science
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• v.5 no.2 s.6
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• pp.57-64
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• 1996

Korean Paintings have been drawn on in the main two types of support material - paper and silk. In these things, silk designates picture silk, that of a specially weaved textile for painting since CHO-SUN dynasty, different such as hemp, ramie have been started to use for support material In addition to picture silk. However the structure of hemp and ramie are so close and progue, They are not proper to express the technique of pigments on the back of the paintings. On the other hand, picture silk is efficacious in pigments on the back of the painting with its interval between the strands and translucent textile. As the result, paintings on the silk has many - sided techniques as compared with painting on the papers therfore various devices in conservation have to be considered to deal with the techniques. In this report the focus is on classifying the method of removing the Lining paper according to the several types of expression technique of paintings on the silk.