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.

지지격자가 있는 봉다발 구조에서 압력 손실에 대한 실험적 연구

이치영(Chi Young Lee),신창환(Chang Hwan Shin),박주용(Ju Yong Park),오동석(Dong Seok Oh),인왕기(Wang Kee In) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

In the present experimental study, OFEL (Omni Flow Experimental Loop) was built up, and then the friction factor in rod bundle and the pressure loss coefficient of spacer grid were investigated in range of Re=40,000?200,000. As a test section, 25 smooth rods of 9.48 mm in diameter and 2 m in length was prepared, and installed in 5×5 square array in a square channel. In this case, P/D (Pitch-to-Diameter ratio) was 1.35. In this work, three kinds of spacer grids were tested: SG0MV (Spacer Grid without Mixing Vane), SG1MV (Spacer Grid with 1-pair Mixing Vane) and SG2MV (Spacer Grid with 2-pair Mixing Vane). In the bare rod bundle (i.e., no spacer grid), the measured friction factors were in good agreement with the previous correlations proposed by Blasius and McAdams. Among the spacer grids tested in this study, the SG2MV appeared the largest friction factor in rod bundle and pressure loss coefficient, which were approximately 0.019 and 0.94 at Re=200,000, respectively.

물 소화약제에서 스타이렌 위험물을 포함한 합성수지에 의한 금속 이온들의 흡착

이치영 ( Chi Young Lee ),김준태 ( Joon Tae Kim ) 한국공업화학회 2010 공업화학 Vol.21 No.2

신체적 특성을 고려한 장애인용 Mouse Piece Controller에 관한 연구

이치영(Lee Chi-Young) 한국디자인학회 2007 한국디자인학회 학술발표대회 논문집 Vol.- No.-

이중냉각 환형핵연료 집합체를 위한 비틀림 혼합날개 지지격자의 강제대류열전달 성능 검토

이치영(Chi Young Lee) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.1

이중냉각 환형핵연료 집합체를 위한 비틀림 혼합날개 지지격자의 강제대류열전달 성능을 실험적으로 평가하였다. 비틀림 혼합날개 지지격자는 부수로 간 혼합뿐 아니라 부수로 내 혼합을 동시에 증대시킬 수 있도록 설계되었다. 실험을 위한 이중냉각 환형핵연료 모의 집합체로, 봉 중심 간 거리와 봉 외경의 비가 1.08인 봉 간격이 좁은 4×4 정사각 배열의 봉다발을 준비하였다. 실험은 봉다발 유동의 축방향 평균속도가 1.5 m/s, 열유속은 26 kW/m<SUP>2</SUP>인 조건에서 수행하였다. 원주방향 온도 분포의 경우, 지지격자 상류에서는 부수로 중심 벽면에서, 하류에서는 비틀림 혼합날개 끝이 향하는 벽면에서 온도가 가장 낮게 나타났다. 축방향 온도 분포의 경우, 지지격자 하류 근처에서 온도가 급격하게 감소하는 것으로 측정되었고, 비틀림 혼합날개에 의해 누셀트 수는 최대 56 % 증대되는 것으로 나타났다. 본 실험결과를 토대로 봉 간격이 좁은 이중냉각 환형핵연료 집합체에서 비틀림 혼합날개 지지격자에 의해 강제대류열 전달 성능이 효과적으로 증대될 수 있음을 확인하였다. The forced convection heat transfer performance of a twist-vane spacer grid for a dual-cooled annular fuel assembly was examined experimentally. The twist-vane spacer grid was uniquely designed to enhance mixing inside subchannels and mixing between adjacent subchannels. For testing, a 4 × 4 square-arrayed rod bundle with narrow gaps between rods was prepared as the dual-cooled annular fuel assembly to be simulated. The pitch-to-rod diameter ratio of simulated dual-cooled annular fuel assembly was 1.08. The experiments were performed under the following conditions: axial bulk velocity, 1.5 m/s and heat flux, 26 kW/m<SUP>2</SUP>. With regard to the circumferential temperature distribution, the lowest rod-wall temperatures upstream and downstream were measured at the subchannel center and the position toward the tip of twist-vane, respectively. With regard to the axial temperature distribution, behind the twist-vane spacer grid, the rod-wall temperature decreased drastically, and the Nusselt number was enhanced by up to 56 %. The present measured data indicate that the twist-vane spacer grid can effectively improve the forced convection heat transfer in the dual-cooled annular fuel assembly with narrow gaps.

봉다발 유동에서 혼합날개 지지격자에 의한 단상 대류열전달 향상에 대한 연구

이치영(Chi Young Lee),인왕기(Wang Kee In) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.4

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.

대기오염물질의 건성침적에 관한 연구

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/>

Cryptand 합성수지에 의한 금속 이온들의 흡착

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.

계면활성제 수용액 내 고온 수직 금속봉의 최소막비등점에 대한 연구

이치영(Chi Young Lee),김재한(Jae Han Kim) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.9

다양한 온도 조건의 계면활성제 수용액 내에서 급속 냉각되는 고온 수직 금속봉의 최소막비등점에 대한 실험을 수행하였다. 액체로는 Triton X-100 수용액(100 wppm)과 순수(pure water)를 이용하였고, 액체의 온도는 77 °C~100 °C 영역이었다. 고체 시편으로는 시편 중심의 초기 온도가 500 °C인 스테인레스 스틸(stainless steel) 수직봉을 이용하였다. Triton X-100 수용액과 순수에서, 액체의 온도가 감소함에 따라 최소막비등점의 도달시간은 감소하였고, 온도 및 열유속은 증가하였다. 한편, 본 실험 온도 영역에서, Triton X-100 수용액의 경우가 순수의 경우보다 최소막비등점의 도달시간은 길었고, 온도 및 열유속은 감소하는 경향을 나타냈다. 본 실험데이터를 토대로 고온 수직 금속봉에 대해서 Triton X-100 수용액과 순수에서의 최소막비등 온도에 대한 실험식을 제안하였다. In this study, experiments were conducted on the MFB(minimum film boiling) point of highly heated vertical metal rod quenched in aqueous surfactant solution at various temperature conditions. The aqueous Triton X-100 solution(100 wppm) and pure water were used as the liquid pool. Their temperatures ranged from 77 °C to 100 °C. A stainless steel vertical rod of initial center temperature of 500 °C was used as a test specimen. In both liquid pools, as the liquid temperature decreased, the time to reach the MFB point decreased with a parallel increase in the temperature and heat flux of the MFB point. However, over the whole present temperature range, in the aqueous Triton X-100 solution, the time to reach the MFB point was longer, while the temperature and heat flux of the MFB point were reduced when compared with pure water. Based on the present experimental data, this study proposed the empirical correlations to predict the MFB temperature of a high temperature vertical metal rod in pure water and in aqueous Triton X-100 solution.