• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.53-56
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• 2008

In this paper, we propose the battery charging device for electric bicycle using photovoltaic power. DC voltage from the solar cells is low, it needs to be step-up by the power conversion device. The power conversion device applied to this paper is phase-shift full-bridge converter. This converter steps-up from 12${\sim}$22[Vdc] to 36[Vdc] for charging the battery of electric bicycle. Phase-shift full-bridge converter(PSFB) can obtain twice as much DC voltage compared with half-bridge converter, thus it has lower current stress less than half-bridge converter. It is simulated and tested the battery charging device using photovoltaic power.

• Communications of the Korean Mathematical Society
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• v.14 no.4
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• pp.815-832
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• 1999

High-order weighted difference schemes with uniform meshes are considered for the convection-diffusion problem depending on Reynolds numbers. For small Reynolds numbers, a weighed cen-tral difference scheme is suggested since there is no boundary layer. For large Reynolds numbers, we propose a modified up wind method with an artificial diffusion in order to overcome nonphysical oscilla-tion of central schemes and obtain good accuracy in the boundary later. Existence and corresponding error estimates of the solution for the difference scheme have been shown. Numerical experiments are provided to back up the analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1409-1417
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• 2003

In the 21st century, the concept of remote design and manufacture is strongly required in manufacturing processes to reduce cost and time-to-market. The objective of this paper is the development of an internet-based dimensional verification system for reverse engineering. An inspection client can register measurement data at the developed web server. Collaborators related to the development of a new product can confirm geometrical form from measurement data, check dimensional information and mark up the important parts, as well as make a statement of their views through the Internet. The developed system is realized through the ActiveX-Server architecture. Functions of the dimensional verification module are constructed as ActiveX by using the visual C＋＋ and OpenGL. The usefulness of the developed system is confirmed through a case study.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.199-200
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• 2015

본 논문에서는 Online UPS system에 계통 연계가 가능하며, 피크 전력을 저감 할 수 있는 기능을 추가한 UPS를 제안한다. 제안한 UPS는 계통 연계와 피크 전력 저감을 위하여 AC/DC PWM 컨버터와 배터리 단에 양방향 Buck-Boost 컨버터를 적용하였으며 역률 0.98 이상과 THD를 3%이하의 조건을 만족하고 IGBT의 신뢰성 확보를 위한 발열 및 방열을 검토한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.28-34
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• 1987

As a means of improving the reliability of a process control system, a FTCS(Fault Tolerant Control System) is designed and applied to the boiler controller of a thermal power plant. The proposed FTCS has capabilities of fault detection and diagnosis as well as back-up control and bumpless switching. A prototype of FTCS is implemented on an IBM PC as an add-on system and it is experimentally verified by using a boiler process simulator together with simplified analog controllers and a switching unit that an one-fold fault is detected in real time and back-up controller takes over the role of the original controller, controlling the faulty loop.

• Lingua Humanitatis
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• v.7
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• pp.205-226
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• 2005

Up to January 2003, the amount of English translated works of Korean Literature are 399, among which 170 are translated abroad, 189, in Korea, and 40, abroad as well as in Korea at the same time. Like other language speaking countries, the 1980s and the 1990s are peak not only for the translation of Korean Literature but also for its scholarly attention. The statistic analysis of information, accumulated in various databases such as The Harvard Korean Studies Bibliography, Hawaii Korean Studies Bibliography, and MLA International Bibliography, shows that up to February 2004, 33 books, 16 dissertations and one thesis, 200 articles, and 84 reviews are wholly devoted to the study of Korean Literature in English speaking countries. However, why certain works of poets like Kim Sowol, Han Youngun, So Chungju, and novelists like Hwang Sunwon, Han Moosook, Kim Dongri are mostly translated in English speaking countries remain to be analysed in their socio-political details in breadth and depth. Likewise, why the works of So Chungju, Yi Kwangsoo, Kim Manjoong, Han Youngun, Kim Sowol, Chung Jiyoung are mostly taught and studied in English speaking countries are open to further scholarly discussion and debate.

• Korean Journal of Head & Neck Oncology
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• v.16 no.1
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• pp.26-32
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• 2000

Background and Objectives: Various flaps are using for reconstruction of hypopharyngeal and esophageal defect. However, complication and indication of each flap are not fully analyzed. Patient and Methods: Records of 52 hypopharyngeal cancer patients who had surgical treatment and 13 other head and neck cancer patients who underwent hypopharyngeal and/or esophageal reconstruction with flap were retrospectively analyzed. Eighty three percent(54 cases) of patients needed reconstruction other than primary pharyngeal closure. Five split thickness skin graft, 1 pectoralis major myocutaneous flap, 20 forearm free flap, 13 jejunal free flap, 15 gastric pull up were used. Result: Flap failure was noted in 2 cases who had subsequent gastric transposition. Wound dehiscence and fistula were most common problem of forearm free flap. Most fistulas were developed in patients with conduit type reconstruction of forearm flap while there wasn't any fistula in patient with patch type reconstruction. Stenosis of lower anastomosis was the frequent problem of jejunal transfer. Gastric pull-up has frequent com-plication of stomal stenosis. All but three patients had reached oral feeding postoperatively. Conclusion: Based on this study, forearm flap is effective in partial hypopharyngeal defect while jejunum is the choice for circumferential defect. Gastric pull-up is for combined esophageal defect.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.4
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• pp.31-40
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• 2007

Recently, the scale in the field of reinforced soil retaining wall has been grown up like tiered reinforced soil retaining wall. However, there have been increasing number of collapse accidents and large scale of collapse. The design manual adopted in the construction fields have been inconsistent in tiered reinforced soil retaining wall. Therefore, this study performed finite element analysis on 90 cases and analyzed characteristic behavior of lower wall which was one of the effect factors on the stability of tiered reinforced soil retaining wall. The facing displacement of each walls and the behavior of the whole ground were interpreted by the numerical analysis depending on the lower offset distance by the upper wall as well as the upper offset distance by the surcharge load. The results showed that the behavior of tiered reinforced soil retaining wall was differed by condition of surcharge load and each offset distance was found to be important factor.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.640-644
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• 2004

Since the existing quadtree image segmentation methods decide the presence of image information using the maximum and minimum pixel value within an image block, they are very sensitive to noise. Although many image segmentation methods have been researched up to date, they can not execute the optimum image segmentation if noise is included in an image because there is no accurate parameters which can distinguish noise. For that reason, all application using the existing quadtree segmentation has potential of decreasing in performance due to noise. This paper proposed a quadtree image segmentation based on SDT (Standard Deviation Threshold) that can effectively extract image information parameters from a noise image. This method has the advantage of distinguishing the presence of image information even if the image has noises caused by communication. Furthermore, this paper verified through test comparison that the proposed quadtree segmentation could estimate more accurate image information parameters than the existing ones even in noise-added environment.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1925_1926
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• 2009

This paper describes a novel power management circuitry for reducing the sleeping mode power dissipation. Based on the proposed power management circuitry, the sensor module can be activated by RF wake-up signal, perform designated process and deactivate itself. There is absolutely no power dissipation at the sleeping mode which takes almost time of the operation. The temperature sensor module using solar cell as energy source has been fabricated and tested. Experimental results show that the sensor module with 3300 ${\mu}$F for storage capacitor can transmits RF temperature data to a receiver at a distance of 20 m every 15 second in a normal indoor light condition and keep the capacitor voltage over 9 V. And the sensor module can operate 100 times with a single charging, that means it is possible for the sensor module to transmit every 5 minute for 8 hours without light or any other power input during the night time.