• Title/Summary/Keyword: Gyu-Dong Choi

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An Effective Mapping for a Mobile Robot using Error Backpropagation based Sensor Fusion (오류 역전파 신경망 기반의 센서융합을 이용한 이동로봇의 효율적인 지도 작성)

  • Kim, Kyoung-Dong;Qu, Xiao-Chuan;Choi, Kyung-Sik;Lee, Suk-Gyu
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.9
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    • pp.1040-1047
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    • 2011
  • This paper proposes a novel method based on error back propagation neural networks to fuse laser sensor data and ultrasonic sensor data for enhancing the accuracy of mapping. For navigation of single robot, the robot has to know its initial position and accurate environment information around it. However, due to the inherent properties of sensors, each sensor has its own advantages and drawbacks. In our system, the robot equipped with seven ultrasonic sensors and a laser sensor navigates to map two different corridor environments. The experimental results show the effectiveness of the heterogeneous sensor fusion using an error backpropagation algorithm for mapping.

A Study on the Design on Iron-Core Shape for Superconducting Hybrid Electro-Magnet System (초전도 하이브리드 자기부상 마그넷 시스템의 코어 형상 설계 연구)

  • Hwang, Young-Jin;Choi, Suk-Jin;Jang, Jae-Young;Ko, Tae-Kuk;Lee, Chang-Young;Yang, Dong-Gyu;Lee, Hai-Gun
    • Progress in Superconductivity and Cryogenics
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    • v.13 no.1
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    • pp.36-40
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    • 2011
  • This paper deals with the design on iron-core shape for superconducting hybrid electromagnet (SH-EM). A proto-type SH-EM was developed by Yonsei University. It is the first step study on the fundamental technology for advanced railroad system development. We proposed the method that reduce the number of cooling systems in order to improve operating efficiency of the SH-EM. The results was obtained by changing of iron-core shape were verified by the FEM analysis. This paper can be expected to suggest useful data for an advanced SH-EM.

Design of a Bidirectional Adaptive Coupler for Spread Spectrum Power Line Communications (대역 확산 전력선 통신을 위한 양방향 적응 결합기 설계)

  • Yu, Young-Gyu;Woo, Dae-Ho;Choi, Seok-Woo;Kim, Dong-Yong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.3
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    • pp.623-628
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    • 2007
  • This paper presents the new power line coupler which is applicable to spread spectrum power line communications. The proposed coupler maintains the adequate value of a capacitor between the transmitter mode and the receiver mode using a switch. In the transmit mode, the relatively high value of the capacitor is chosen to minimize the attenuation of transmitted signals. In the receiver mode, the value of the capacitor is chosen to be small enough so that the coupler attenuates power line noises. This coupler reduced the magnitude distortion due to having a high Q value and the power consumption caused by the AC current flowing into the capacitor. The simulation and measurement results show the improved performance in the transmitter and receiver mode, respectively.

Anticonvulsant Effect of Uncariae Ramulus et Uncus. I. -Anticonvulsant Effect of Ethyl Acetate Fraction- (조구등(釣鉤藤) 성분의 항경련 효과 I. -에틸아세테이트 분획의 항경련 효과-)

  • Kim, Dong-Young;Kim, Hoe-Young;Park, Min-Soo;Lee, chung-Gyu;Choi, Jong-Won
    • Korean Journal of Pharmacognosy
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    • v.27 no.1
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    • pp.53-57
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    • 1996
  • To elucidate the activities of Uncaria Ramulus et Uncus, which has been used as anticonvulsant and antihypertensive in oriental region, the methanolic extract and its fractions were applied to inhibition of convulsion onset. The ethyl acetate fraction showed dose-dependent inhibitory activity against pentylenetetrazole-induced seizure.

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Effect of Skin Burn on the Skin and Liver (피부화상이 피부 및 간에 미치는 영향)

  • Nam, Chul-Hyun;Seo, Hyun-Gyu;Hwang, Tae-Yeun;Choi, Hyun-Lim;Lee, Dong-Ho
    • Journal of Korean Physical Therapy Science
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    • v.8 no.2
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    • pp.1091-1097
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    • 2001
  • The main experiments was investigated the skin tissue damage changing for the skin bum having influence on the skin and the liver and also observed the radical liver weight, ALT in the serum, the fluctuating of AST for the skin bum causing to the liver damage. Anatomically the edema formation of skin after thermal injury was showed, and skin bum increased liver weight (% of body weight, p<0.05) and the activity of serum aniline aminotrasferase (p<0.05), and also histologically induced wes of epidermal layer, protein degeneration of connective tissue, local hemorrhage and degeneration of glandular epithelium in the skin tissue. Liver tissue showed the evidences of postbum damage, they were sinusoidal dilatation, cell swelling, infiltration of inflammatory cells.

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Effects of Injector Shape Variation on Combustion Performance of a Subscale Gas Generator (분사기 형상 변화에 따른 축소형 가스발생기 연소 특성)

  • Kim, Mun-Ki;Lim, Byoung-Jik;Kang, Dong-Hyuk;Ahn, Kyu-Bok;Kim, Jong-Gyu;Choi, Hwan-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.159-162
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    • 2011
  • The hot-firing tests of a subscale gas generator were successfully performed to investigate the effect of injector shape variation on its discharge coefficient. The test results showed that discharge coefficients of fuel and liquid oxygen injectors remained nearly constant irrespective of the mixture ratio or the chamber pressure. In all experimental conditions, the combustion instability was not observed.

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Diseases Management Hybrid App Service for Chronic disease Patients (만성질환 환자들을 위한 질환관리 하이브리드 앱 서비스)

  • Lee, dong-hee;Lee, gyu-jung;Lim, byung-muk;Ahn, da-mi;Choi, eun-suk;Son, Hyun-Jun;Kang, Hoon;Yoo, Kwan-Hee
    • Proceedings of the Korea Contents Association Conference
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    • 2015.05a
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    • pp.441-442
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    • 2015
  • 현대인들의 건강관리의 인식의 변화와 노령화 인구 증가는 현대 사회의 큰 이슈이다. 몸이 불편하지만 거동이 힘든 환자, 보호자가 항상 곁에 없는 환자, 스스로의 질병관리의 방법을 모르는 환자들이 스마트 기기만 있으면 이용 가능한 만성질환관리 하이브리드 앱서비스를 제안한다. 제안한 하이브리드 앱서비스는 웹페이지를 이용하여 운영체제에 상관없는 서비스 이용이 가능하도록 연구하였다.

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Development of Rotational Molds for Continuous Casting of Rotor (Rotor 연속주조를 위한 회전형 주형개발)

  • Lee, Yang-Chang;Bae, Byeong-Gyu;Chang, Hyun-Seok;Lee, Joon-Seong;Choi, Yoon-Jong;Kwon, Dong-Cheol;Song, Byeong-Mok
    • Proceedings of the KAIS Fall Conference
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    • 2011.05b
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    • pp.840-843
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    • 2011
  • 본 논문은 모터의 회전자를 연속적으로 주조하기 위한 주형 개발을 위해 주조 유동해석를 통해 그 결과를 반영하였다. 주형을 제작하고, 성형한 결과로 수평형은 슬리브가 수평구조이고, 고속으로 작동하면서 공기와 기타 가스빼기가 원활하지 않음에 제품 성형률이 매우 떨어짐을 알 수 있었다. 현재 이를 해결하기 작업자들의 경험에 많이 의지하고 있다. 수직형은 슬리브 구조가 수직으로 되어있어 슬리브가 고속으로 작동할 때, 수평형과 달리 용액이 층류형태로 유지되면서 공기나 기타 가스발생이 매우 적어 안정된 주물제품이 성형됨을 알 수 있었다.

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Modeling the Dynamics of Wildbird's Avian Influenza Using the System Dynamics (시스템다이나믹스를 이용한 철새의 AI 전파 모델)

  • Park, Young-wook;Won, Dong-gyu;Choi, Sung-Bae
    • Proceedings of the Korea Contents Association Conference
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    • 2009.05a
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    • pp.1130-1135
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    • 2009
  • Avian Influenza is an infectious desease of birds. The infection can cause a wide spectrum of symptoms in birds, ranging from mild illness to a rapidly fatal diseases which might bring a tremendous economic loss to poultry farms[1]. It can also give fatal diseases to human. Therefore it is important to surveil wildbirds that are primary transportation of avian influenza. This report showed a relationship between avian influenza and a habitat of wildbirds using system dynamics, and concluded with suggestion for surveilance.

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A Study on Negative Bias Temperature Instability in ELA Based Low-Temperature polycrystalline Silicon Thin-Film Transistors

  • Im, Kiju;Choi, Byoung-Deog;Hyang, Park-Hye;Lee, Yun-Gyu;Yang, Hui-won;Kim, Hye-Dong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08b
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    • pp.1075-1078
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    • 2007
  • Negative Bias Temperature Instability (NBTI) in Eximer Laser Annealing (ELA) based Low Temperature polysilicon (LTPS) Thin-Film Transistors (TFT) was investigated. Even though NBTI is generally appeared in devices with thin gate oxide, the TFT with gate oxide thickness of 120 nm, relatively thick, also showed NBTI effect and dynamic NBTI effect is dependent on operational frequency.

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