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원형 미소 채널 내 드라이 플러그류의 유동 영역 한계와 압력 강하에 관한 실험적 연구
이치영(Chi Young Lee),이상용(Sang Yong Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In the present experimental study, the regime limit and pressure drop of dry-plug flow (dry wall condition at the gas portions of plug flow) in round mini-channels has been investigated. The air-water mixture was flowed through the round mini-channels made of Teflon, where the tube diameters ranged from 1.26 to 2.06 ㎜. For the present experimental range, with decreasing of the tube diameter, the transition between the plug and slug flows (wet and dry) happened at the higher gas superficial velocity region, which were in good agreement with the previous flow pattern maps tested. On the other hand, the transition between the wet- and dry-plug flows was little affected by the change of the tube diameter. In the pressure drop of dry-plug flows, among the correlations tested, the Lee and Lee’s (2008) correlation best fitted the measured pressure drop data within the mean deviation of 10 % for the present experimental range.
Y-자형 합류지점에서 공기-물 플러그 생성에 관한 사전 연구
이치영(Chi Young Lee),권화길(Hwa-Kil Kwon),이상용(Sang Yong Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In the present study, the formation of air-water plugs at a merging Y-junction was investigated. The generation rates and lengths of gas and liquid plugs were checked for various gas and liquid superficial velocities. For the present experimental range, the generation rates of plugs were increased with increasing gas or liquid superficial velocity, and the effect of the liquid superficial velocity was predominant compared to the gas superficial velocity. The length of gas plugs became longer either by decreasing liquid superficial velocity or by increasing gas superficial velocity. On the other hand, the length of liquid plugs became slightly longer with increasing liquid superficial velocity in the low gas superficial velocity region, and independent of the liquid superficial velocity in the higher gas superficial velocity region. Through the comparison with the previous results of plug formation, the physical interpretations on the present results were provided.
Y-자형 합류 지점에서 기체 및 액체 플러그 생성에 관한 연구
이치영(Chi Young Lee),이상용(Sang Yong Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
In the present study, effect of channel diameter and liquid viscosity on formation of gas and liquid plugs at a merging Y-junction was experimentally investigated. Two Y-junctions were tested, having 1.58 and 2.41 ㎜ inner diameters, respectively. Air was used as the gas phase whereas pure water and aqueous solution of glycerol were used as the liquid phases. As the channel diameter of Y-junction was increased, the generation rates of gas and liquid plugs formed at merging Y-junction were decreased. However, the liquid viscosity has little influence on the plug generation rate for the present experimental condition.
봉다발 유동 내 비틀림 혼합날개 지지격자의 대류열전달 성능 평가
이치영(Chi Young Lee) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.3
봉다발 유동에서 비틀림 혼합날개 지지격자의 대류열전달 성능을 실험적으로 평가하였다. 시험부는 4×4 정사각 배열의 봉다발로 제작하였고, 모의 봉다발에서 봉 중심 간 거리와 봉 외경의 비는 ~1.35이다. 대류열전달 성능 평가를 위해 혼합날개 지지격자 하류에서 봉 벽면 온도의 원주방향 및 축방향 분포를 측정하였다. 원주방향의 경우, 지지격자 하류에서 비틀림 혼합날개 끝이 향하는 벽면의 온도가 가장 낮게 나타났는데 이는 비틀림 혼합날개에 의해 왜곡된 유동 때문으로 판단된다. 반면, 축방향의 경우, 혼합날개 지지격자 근처에서 벽면의 온도가 크게 낮아졌는데, 이는 비틀림 혼합날개에 의해 대류열 전달이 향상됨을 의미한다. 비틀림 혼합날개 지지격자에 의해 대류열전달 성능은 지지격자 상류에 비해 지지격자 근처 하류에서 ~35 % 향상되었고, 실험데이터를 기반으로 비틀림 혼합날개 지지격자에 대한 열전달 성능 예측 상관식을 제안하였다. The performance of convective heat transfer in rod bundle flow was experimentally evaluated using a twistvane spacer grid. A 4×4 square-arrayed rod bundle was prepared as the test section, with a pitch-to-diameter ratio(P/D) of ~1.35. To check the convective heat transfer performance, the circumferential and longitudinal variations in rod-wall temperatures were measured downstream of the twist-vane spacer grid. In the circumferential measurements, the rodwall temperature toward the twist-vane tip showed the lowest value, which might be due to the deflected water flow caused by the twist-vane. On the other hand, the wall temperature of the longitudinal measurements near the twist-vane spacer grid decreased dramatically, which implies that the convective heat transfer performance was enhanced. A heat transfer enhancement of ~35 % was achieved near downstream of the twist-vane spacer grid, as compared with the upstream value. Based on the present experimental data, a correlation for predicting the heat transfer performance of a twist-vane spacer grid was proposed.
모바일 PULSE : 모바일 싱크 노드를 가진 센서 네트워크에서의 경로 복구 시간과 전력 소모량을 고려한 라우팅 프로토콜
이치영(Chi-Young Lee),이신형(Shin-Hyoung Lee),유혁(Chuck Yoo) 한국통신학회 2009 韓國通信學會論文誌 Vol.34 No.2b
PULSE 프로토콜은 센서 노드의 슬립을 통해 소모 전력량을 크게 줄인다. 그러나 이 프로토콜은 싱크 노드의 이동을 고려하지 않는 문제가 있다. 모바일 싱크 노드를 가진 센서 네트워크를 위한 라우팅 프로토콜은 빠른 경로복구와 전력 소모 최소화를 모두 달성해야 한다. 본 논문은 두 목적을 달성하기 위해 모바일 PULSE 프로토콜을 제안한다. 또한, 실험을 통해 제안한 프로토콜의 경로 복구 능력과 전력 소모량을 확인하였다. 이 프로토콜은 기존의 PULSE 프로토콜에 비해 약 40% 정도 경로 복구 시간을 단축하였고, 드롭되는 패킷의 양도 약 1/2 수준으로 줄였다. 전력 소모량 면에서는 최대 0.8%의 증가만이 나타남으로써, 기존의 PULSE 프토토콜의 전력 효율적인 특징을 그대로 유지함을 보였다. 본 논문은 모바일 PULSE 프로토콜의 경로 복구 능력과 전력 소모량을 확인함으로써 모바일 센서 네트워크에 적합한 프로토콜로서의 가능성을 보여준다. The PULSE protocol can greatly reduce power consumption using a node's sleep state. But this protocol does not consider movement of a sink node in a sensor network. In the mobile sensor network, a routing protocol must recover path error by movement of a sink node as quickly as passible. Therefore we have to achieve fast path recovery and power saving to support movement of a sink node in a sensor network. This paper proposes the Mobile PULSE protocol which is a improved routing protocol for a mobile sink node. And we evaluate Mobile PULSE and show that the Mobile PULSE reduces the recovery time about 40% compared with original PULSE protocol. Mobile PULSE increases energy consumption than PULSE as a maximum of 0.8%, which means Mobile PULSE is similar to PULSE in energy consumption. This paper shows mobile PULSE's capability in the mobile sensor network through evaluation of path recovery time and power consumption.
이치영(Chi-Young Lee),강동구(Dong-Ku Kang) 대한환경위생공학회 2003 대한환경위생공학회지 Vol.18 No.3
Measurement of dried deposition for air pollutant was investigated in Gwang-ju Health college area for a year. The average value of air pollutants was investigated three times a month. Measured heavy metals and concentration of mass are not co related. Heavy metals were thrown up air as state of large particles and they were moved by wind. Deposition of heavy metals and deposition velocities were high in the order of Fe > Zn >Cu > Pb > Cr and Pb > Fe > Cr > Zn > Cu, respectively. The patterns of deposition velocity of heavy metals for a year were much the same as each other except that Pb is faster than others.<br/> <br/> <br/> <br/> <br/> <br/> <br/>
이치영(Chi-Young Lee),김준태(Joon-Tae Kim) 대한환경위생공학회 2005 대한환경위생공학회지 Vol.20 No.4
Cryptand resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene(DVB) copolymer with crosslink of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium(UO₂²+) ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium(UO₂²+) > zinc(Zn²+) > samarium(Sm³+) ion. The adsorption was in order of 1% > 2% > 5% > 10% crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.