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이중 무선 인터페이스 결합 시스템을 위한 적응적 인터페이스 활성화 기법의 성능 분석
윤지훈,Yun, Ji-Hoon 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.8
스마트폰을 비롯한 최신의 사용자 단말은 대체로 복수 개의 무선 인터페이스를 갖는다. 이러한 복수 개의 무선 인터페이스를 결합하여 동시에 사용함으로써 데이터 전송 속도를 향상시킬 수 있다. 하지만, 이 경우 각 인터페이스가 전력을 소모하므로 단말의 총 소비 전력은 매우 클 수 있다. 본 논문에서는 이중 무선 인터페이스를 결합하여 사용 시 단말의 버퍼 상태에 따라 무선 인터페이스를 적응적으로 활성화시키는 기법의 성능 모델을 마코브체인을 이용해 도출한다. 도출된 성능 모델은 패킷 발생률, 딜레이 성능 요구 조건, 결합으로 인한 성능 손실 등 다양한 동작 환경 및 설정에 대해 전송 딜레이 성능과 전력 소모를 예측할 수 있게 한다. 모델을 통해 적응적 활성화 기법이 일정 이하의 낮은 트래픽 발생 상황에서 기존 대비 절반 정도의 전력 소모를 하는 것을 보인다. Today's smartphones and user devices are equipped with multiple radio interfaces increasingly. Aggregating theses multiple radio interfaces and using them concurrently will increase a user's communication speed immediately, but at the expense of increased power consumption. In this paper, we develop a mathematical performance model of an adaptive radio activation scheme by which a radio interface is activated only when needed for performance increase and deactivated otherwise. The developed model shows that the adaptive scheme reduces delay significantly and almost halves power consumption below a certain level of traffic input.
ATmega16 마이크로컨트롤러를 이용한 전력선통신용 가시광 무선통신 시스템 구현 및 수신 특성 분석
윤지훈(Ji-Hun Yun),홍근빈(Geun-Bin Hong),김용갑(Yong-Kab Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.11
This study is to solve problems of depletion of RF bandwidth frequency, confusion possibility, security that current wireless communications system have and is to confirm possibility of applying next generation network. To solve problems of current wireless communications system, visible light communications system for power line communications using ATmega16 Microcontroller is was realized and receiver property was analyzed. PLC exclusive chip APLC-485MA, Microcontroller ATmega16, 5pi bulb type LED and high flux LED, visible light receiving sensor LLS08-A1 were used for transmitter and receiver. Performance was analyzed by designed program and an oscilloscope. It was showed average 20% improved receiver rate rather than bulb type LED in the case of high flux LED through voltage change rate on communication distance and LED type of distance between 10 to 50 cm. The blue LED showed the best performance among measured LED types with above 10% of voltage decreasing rate. But As it gradually becomes more distant, the precise date was difficult to obtain due to weak light. To overcome these sort of problems, specific values such as changing conditions and efficiency value relevant to light emitting parts and visible light receiving sensor should be calculated and continuous study and improvements should also be accomplished for the better communications condition.
진공관형 집열기 히트파이프 접촉방식에 따른 집열성능 비교
윤지훈(Ji hun Yun),정인국(In guk Jeong),이중섭(Chung seob Yi),정경택(Kyeong teak Jeong),서정세(Jeong se Suh) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
In this study, it was compared collecting performance according to contact types between heatpipe and manifold of vacuum tube type solar collector. Between two types, direct contact type is better in collecting performance. On the other hand, Indirect type have advantage in maintenance. In the result of numerical analysis, As the temperature of heatpipe and flow rate of working fluid increased, difference of outlet mean temperature of two types became large. Also, it could be confirmed, as contact resistance between heatpipe and copper wall in indirect type increased, the difference increased too. Useful data in selection and design in vacuum tube type solar collector were proposed by the results of numerical analysis.
진공관형 집열기 히트파이프 접촉방식에 따른 집열성능 비교
윤지훈(Ji-Hun Yun),정인국(In-Guk Jeong),이중섭(Chung-Seob Yi),정경택(Kyung-Teak Chung),서정세(Jeong-Se Suh) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.6
In this study, it was compared collecting performance according to contact types between heatpipe and manifold of vacuum tube type solar collector. Between two types, direct contact type is better in collecting performance. On the other hand, Indirect type have advantage in maintenance. In the result of numerical analysis, As the temperature of heatpipe and flow rate of working fluid increased, difference of outlet mean temperature of two types became large. Also, it could be confirmed, as contact resistance between heatpipe and copper tube in indirect type increased, the difference increased too. Useful data in selection and design in vacuum tube type solar collector were proposed by the results of numerical analysis.
산업용 Turbo형 송풍기의 Cutoff 각도에 따른 유동특성
윤지훈(Ji-Hun Yun),정인국(In-Guk Jeong),이중섭(Chung-Seob Yi),서정세(Jeong-Se Suh) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.5
This study aims to analyze the flow characteristics of turbo-fan which is applied to the industrial field. Numerical analysis has been carried out to investigate the pulsation behavior of exhaust air flown out turbo fan by rotating impeller with constant speed. Moving mesh technique is proved as time-accurate solution for the flow inside impeller. As numerical results come within the error range of 1% by comparing with theoretical results, the numerical analysis can be verified. Cutoff angle has large influence on the amplitude of pulsation and the least pulsation of flow can be generated by the cutoff angle of 20°.
윤지훈(Ji-Hun Yun),이중섭(Chung-Soeb Yi),서정세(Jeong-Se Suh),송철기(Chul-Ki Song) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.2
In this study, numerical analysis was conducted to understand the flow characteristics of lubrication system in a manual transmission installed in a commercial vehicle. Also, the analysis was conducted with the purpose of improving the heat and lubricative condition of the transmission. Discharging flow rates on each oil hole outlet according to various engine rotating speed and the length of oil hole branch was calculated. In conclusion, as engine rotating speed is high and the length of oil hole branch is long, the discharging flow rate is high by virtue of the centrifugal force. In addition, this study proposed data for optimal design of lubrication system in manual transmission for a commercial vehicle.
전방향성 특성을 갖는 RFID Tag 용 다이폴 안테나
윤지훈(Yun Jihun),손태호(Son Taeho),한경환(Han Dave K.) 한국산학기술학회 2005 한국산학기술학회 학술대회 Vol.- No.-
본 논문에서는 900MHz대역에서 전방향성 특성을 갖는 RFID tag용 다이폴 안테나를 설계하였다. 전방향성 특성을 얻기 위해 두 개의 다이폴 안테나를 대각으로 위치하고 의 위상차를 주어 급전하였다. 시뮬레이션 툴을 이용한 결과 안테나의 이득은 1.78dB이었으며, E-plane 과 H-plane 모두 전방향성 특성을 보였다.