• 제목/요약/키워드: Won Bang

검색결과 1,169건 처리시간 0.026초

무선 환경에서 802.11 MAC의 MIB 정보를 이용한 TCP 성능 개선 (TCP Performance Improvement using 802.11 MAC MIB for Wireless Network)

  • 김기원;신광식;윤완오;최상방
    • 대한전자공학회:학술대회논문집
    • /
    • 대한전자공학회 2006년도 하계종합학술대회
    • /
    • pp.59-60
    • /
    • 2006
  • TCP applied to the wireless-wired integrated network is the one that was applied to the existing wired network. In the wireless-wired integrated network, both wireless and congestion loss can occur. When wireless packet losses occur, the congestion control of TCP causes performance degradation by reducing its transmission rate. In this paper, we propose the algorithm to distinguish the wireless packet loss from congestion packet loss using MIB of the 802.11 MAC which has been generally used recently in wireless links.

  • PDF

Identifying and quantitating defects on chemical vapor deposition grown graphene layers by selected electrochemical deposition of Au nanoparticles

  • So, Hye-Mi;Mun, Jeong-Hun;Bang, Gyeong-Sook;Kim, Taek-Yong;Cho, Byung-Jin;Ahn, Chi-Won
    • Carbon letters
    • /
    • 제13권1호
    • /
    • pp.56-59
    • /
    • 2012
  • The defect sites on chemical vapor deposition grown graphene are investigated through the selective electrochemical deposition (SED) of Au nanoparticles. For SED of Au nanoparticles, an engineered potential pulse is applied to the working electrode versus the reference electrode, thereby highlighting the defect sites, which are more reactive relative to the pristine surface. Most defect sites decorated by Au nanoparticles are situated along the Cu grain boundaries, implying that the origin of the defects lies in the synthesis of uneven graphene layers on the rough Cu surface.

철도구조물 적용을 위한 보강토옹벽 벽체시스템과 단계시공의 효과에 관한 연구 (A Study on the Effect of Facing System and Staged Construction Procedures in GRS Walls for Application in Railroad Structures)

  • 원명수;권오현;김영신;방윤경
    • 한국지반공학회:학술대회논문집
    • /
    • 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
    • /
    • pp.359-366
    • /
    • 2009
  • The present paper analyzes and discusses the effect of facing system and staged construction in GRS (geosynethetic reinforced soil) walls for railway structures throughout various case analyses. The result shows that postconstruction facing system by staged construction procedures is more advantageous for railway structure construction than preconstruction and simultaneous construction facing system with reinforced soil.

  • PDF

WAP 환경에서 푸쉬 메시지를 이용한 주관식 채점시스템 (A Grading System for Subjective Tests using Push Messages in WAP Environments)

  • 방훈;원대희;이재영
    • 한국정보처리학회:학술대회논문집
    • /
    • 한국정보처리학회 2002년도 추계학술발표논문집 (중)
    • /
    • pp.1463-1466
    • /
    • 2002
  • 본 논문은 인터넷과 이동전화 사용자가 늘어감으로써 무선인터넷의 필요성이 대두고 있는 가운데 WAP 환경에서 주관식 채점시스템을 접목시킨 시스템을 구현하고자 한다. 근거리통신, 무선인터넷 등의 통신을 이용하여 학습자가 주제별 주관식문제에 응시한 후 해당 답안 정보는 출제자 무선단말기에 푸쉬(Push) 메시지 형태로 즉시 보내지고, 출제자는 학습자의 답안정보를 받아 무선단말기를 이용하여 학습자가 작성한 답안의 배점을 결정하고 채점결과를 서버에 보낸 후 서버는 이 배점으로 채점결과를 학습자에게 신속하게 알려주는 시스템으로 학습자는 신속한 채점결과를 확인하여 학습능력을 향상시킬 수 있는데 목적이 있다.

  • PDF

다양한 펄스 반복률에서의 NPN BJT (Bipolar Junction Transistor)의 파괴 특성에 관한 연구 (A Study on Destruction Characteristics of BJT (Bipolar Junction Transistor) at Different Pulse Repetition Rate)

  • 방정주;허창수;이종원
    • 한국전기전자재료학회논문지
    • /
    • 제27권3호
    • /
    • pp.167-171
    • /
    • 2014
  • This paper examines the destruction behavior of NPN BJT (bipolar junction transistor) by repetition pulse. The injected pulse has a rise time of 1 ns and the maximum peak voltage of 2 kV. Pulse was injected into the base of transistor. Transistor was destroyed, current flows even when the base power is turned off. Cause the destruction of the transistor is damaged by heat. Breakdown voltage of the transistor is 975 V at single pulse, and repetition pulse is 525~575 V. Pulse repetition rate increases, the DT (destruction threshold) is reduced. Pulse Repetition rate is high, level of transistor destruction is more serious.

적응형 소속함수를 가지는 퍼지 제어기 (Fuzzy Controller with Adaptive Membership Function)

  • 김봉재;방근태;박현태;유상욱;이현우;정원용;이수흠
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 1995년도 하계학술대회 논문집 B
    • /
    • pp.813-816
    • /
    • 1995
  • The shape and width of fuzzy membership function has an effect on performance of fuzzy controller. In this paper, neuro-fuzzy controller is proposed to improve the control performance of fuzzy controller. It has membership function, that is adapt to plant constant by using trained neural network. This neural network has been trained with back propagation algorithm. To show the effectiveness of proposed neuro-fuzzy controller with adaptive membership function, it is applied to plant (dead time + 1st order) with various plant constant.

  • PDF

Determination of the Optical Functions of Various Liquids by Rotating Compensator Multichannel Spectroscopic Ellipsometry

  • Bang, Kyung-Yoon;Lee, Seung-Hyun;Oh, Hye-Keun;An, Il-Sin;Lee, Hai-Won
    • Bulletin of the Korean Chemical Society
    • /
    • 제26권6호
    • /
    • pp.947-951
    • /
    • 2005
  • Rotating compensator multichannel spectroscopic ellipsometry has been employed to determine the optical functions of various liquids used in chemistry. We attempted three different measurement configurations: (1) air-liquid interface, (2) prism-liquid interface, and (3) liquid-sample interface. In prism-liquid interface, we found that the prism surface had roughness and it should be considered in analysis for accurate results. In liquidsample interface, we had much higher reflection, better sensitivity, and less limitation compared to the other two configurations when crystalline silicon was used as reference sample. We discuss the merit of each configuration and present the optical functions of various liquids. Also we demonstrate Bruggeman effective medium theory to determine the optical properties of mixed liquid.

Human Visual System에 적응적인 영상 화질 향상 기법 (Human Visual System Adaptive Image Enhancement)

  • 방성배;김원하
    • 한국방송∙미디어공학회:학술대회논문집
    • /
    • 한국방송∙미디어공학회 2016년도 추계학술대회
    • /
    • pp.114-116
    • /
    • 2016
  • 본 논문은 human visual system(HVS)에 따른 주파수 민감도와 공간에서 다양한 특성들을 구현하기 위한 신호처리 방법을 개발하였다. 인간의 눈은 주파수 성분에 따라 민감도가 다르며 초점에서 멀수록 인지 가능한 해상도가 떨어진다. 주파수 민감도를 구현하기 위해서 본 논문은 영상 신호의 에너지 스펙트럼 모양이 contrast sensitivity function(CSF)의 모양이 되도록하여 영상 신호의 에너지를 증가시켰으며 신호 방향에 적응적인 multiband energy scaling 방법을 개발하였다. 기존의 시스템에서 능률만을 향상시키는 기존의 분석 모델과 비교하면 개발한 방법은 HVS에 좀 더 적절하고 선호되게 영상 신호를 처리 할 수 있다.

  • PDF