• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 춘계학술대회 논문집
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• pp.123-124
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• 2003

Fishman and Larson (1987) derived tropical tropospheric column ozone by subtracting stratospheric column ozone measured by the Stratospheric Aerosol and Gas Experiment (SAGE) from total column ozone obtained by the Total Ozone Mapping Spectrometer (TOMS). Later, the Convective Cloud Differential (CCD) method (Ziemke et al., 1998) indicated stratospheric ozone is invariant with longitude and concluded the zonal variation of total ozone determines the zonal variation of tropospheric ozone. (omitted)

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2002년도 춘계학술대회 논문집
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• pp.241-242
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• 2002

최근 들어 지표면 오존농도의 증가에 기여하는 오존전구물질에 대한 관심이 증대되면서 오존전구물질에 대한 분석방법의 확립에 많은 노력을 기울이고 있는 실정이다. 지금까지는 비극성 column을 이용하여 저온 농축과정을 거쳐 분석을 수행하거나 극성 및 비극성 column을 병렬로 연결하여 환경대기 중의 오존전구물질을 측정한 연구사례가 대부분인 것으로 보고되고 있으나 이러한 저온농축과정 및 다수의 column을 사용할 경우 소요되는 장비 및 시간에 대한 비경제적인 측면을 고려하지 않을 수 없다. (중략)

• 자원리싸이클링
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• 제12권3호
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• pp.31-37
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• 2003

수용액중의 암모니아를 리싸이클링하여 황산암모늄을 제조하기 위한 1단계 공정으로 air stripping에 의한 암모니아 탈기특성을 조사하였다. 수용액중 암모니아 탈기실험을 위하여 내경 40mm의 아크릴관을 탈기 column으로 사용하고 하단에 미세한 기체방울을 생성시키기 위하여 air sparger를 설치하는 한편 탈기가스로는 공기를 사용하였다. 탈기실험 결과 수용액 pH가 증가할수록 암모니아 탈기효율이 향상되었으며, 적정 pH범위는 10∼12 인 것으로 나타났다. 공기유량변화가 암모니아 탈기에 미치는 영향에 있어서는 공기유량이 증가함에 따라 탈기량이 비례하여 증가하지는 않았다. 또한, 수주 높이 20 cm 이상에서 절대 탈기량은 수주 높이에 관계없이 일정하게 나타났다. 탈기 온도를 높일수록 암모니아 탈기속도는 크게 증가하여 pH 12.8, 탈기 온도 $60^{\circ}C$에서 14시간 탈기시 초기 암모니아의 90% 정도를 탈기시킬 수 있었으며, 탈기 온도는 수용액 pH와 함께 암모니아 탈기공정의 가장 중요한 변수임을 확인할 수 있었다.

• 한국환경과학회지
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• 제13권12호
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• pp.1059-1065
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• 2004

Bio sparging experiments were conducted in a laboratory column to investigate the potential removal of diesel contaminated groundwater. The objectives in this study were (a) to determine the extent of diesel degradation in laboratory columns under supplement of nutrient; (b) to determine the effect of variation of air flow in the removal of diesel and (c) to evaluate the potential enhancement of diesel degradation as a function of temperature. Our results showed that the nutrient supplement and higher air flow greatly enhanced diesel degradation. However, the variation of water temperature examined slightly increased degradation rate of diesel fuel.

• 설비공학논문집
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• 제18권5호
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• pp.402-409
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• 2006

For the design of a liquid direct contact cooling system, thermal and hydraulic analysis has been carried out. Well-known Zukauskas correlations are used to estimate the Nusselt number between the liquid refrigerant columns and the inlet airflow. The inlet air velocity is set at a typical value used in an actual showcase. For a constant column number, the best nozzle arrangement is determined for the maximum heat transfer. Heat transfer increases as the transverse pitch of the refrigerant column decreases. Among all the cases dealt with in the present study, the staggered arrangement with 140-columns of $14{\times}10$ shows the best thermal peformance and the expected temperature drop is $27.8^{\circ}C$. The effect of downstream refrigerant columns on the overall thermal performance is investigated as well.

• 한국대기환경학회지
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• 제26권5호
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• pp.475-489
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• 2010

In order to verify the enhancement of ozone and carbon monoxide (CO) during springtime in East Asia, we investigated weather conditions and data from remote sensors, air quality models, and air quality monitors. These include the geopotential height archived from the final (FNL) meteorological field, the potential vorticity and the wind velocity simulated by the Meteorological Mesoscale Model 5 (MM5), the back trajectory estimated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the total column amount of ozone and the aerosol index retrieved from the Total Ozone Mapping Spectrometer (TOMS), the total column density of CO retrieved from the Measurement of Pollution in the Troposphere (MOPITT), and the concentration of ozone and CO simulated by the Model for Ozone and Related Chemical Tracers (MOZART). In particular, the total column density of CO, which mightoriginate from the combustion of fossil fuels and the burning of biomass in China, increased in East Asia during spring 2000. In addition, the enhancement of total column amounts of ozone and CO appeared to be associated with both the upper cut-off low near 500 hPa and the frontogenesis of a surface cyclone during a weak Asian dust event. At the same time, high concentrations of ozone and CO on the Earth's surface were shown at the Seoul air quality monitoring site, located at the surface frontogenesis in Korea. It was clear that the ozone was invaded by the downward stretched vortex anomalies, which included the ozone-rich airflow, during movement and development of the cut-off low, and then there was the catalytic photochemical reaction of ozone precursors on the Earth's surface during the day. In addition, air pollutants such as CO and aerosol were tracked along both the cyclone vortex and the strong westerly as shown at the back trajectory in Seoul and Busan, respectively. Consequently, the maxima of ozone and CO between the two areas showed up differently because of the time lag between those gases, including their catalytic photochemical reactions together with the invasion from the upper troposphere, as well as the path of their transport from China during the weak Asian dust event.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.87-92
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• 2008

The breakup processes and spray plume characteristics of liquid jets injected in subsonic air cross-flows were experimentally studied. The behaviors of column, penetration, breakup of plain liquid jet and droplet sizes, velocities have been studied in non-swirling cross-flow of air. Nozzle has a 1.0 mm diameter and Lid ratio=5. Experimental results indicate that the breakup point is delayed by increasing air momentum, the penetration decreases by increasing Weber number and the split angle is increased by increasing air velocity or decreasing injection velocity. SMD increases according as increasing height or decreases in accordance with increasing air velocity. This phenomenon is related to the momentum exchange between column waves and cross-flow stream. Droplet vector velocities were varied from 11.5 to 33 m/s. A higher-velocity region can be identified in down edge region at Z/d=40, 70 and 100. Lower-velocity region were observed on bottom position of the spray plume.

• 한국해양공학회지
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• 제24권2호
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• pp.1-9
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• 2010

Oscillating Water Column is one of the most widely used converting systems all over the world. The operating performance is influenced by the efficiencies of the two converting stages in the OWC chamber-turbine integrated system. In order to study the effects of the pressure drop induced by the air turbine, the experiments using the impulse turbine and the orifice device are carried out in the wave simulator test rig. The numerical simulation utilizing the orifice and porous media modules is calculated and validated by the corresponding experimental data. The numerical wave tank based on the two-phase VOF model embedded with the above modules is employed to investigate the wave elevation, pressure variation inside the chamber and the air flow velocity in the duct. The effects of the air turbine on the integrated system and interaction among the wave elevation, pressure and air flow velocities variations are investigated, which demonstrates that the present numerical model are more accurate to be employed.

• 환경위생공학
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• 제17권2호
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• pp.79-84
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• 2002

This study investigated possibility of the nitrification and denitrification in one counter-current column with the growth of biofilm attached to its media. This experiment was performed through use of the lab scale reactor composed of the column and settler. The column used was packed with the small size of plastic rings called PALL($1.5{\times}1.5{\;}cm$) with a cylindrical shape. Synthetic wastewater was used in the experiment. The loading rates of carbon (C) and total nitrogen (TN) furnished to the reactor were 0.23 to 1.0 kg COD/m3.d and 0.023 to 1.0 kg N/m3.d, respectively. Major factors controlling the removal efficiencies of COD and TN were the different air flux and volumetric loading rates of COD and TN. The experimental results obtained from this study demonstrated that the removal efficiencies of COD ranged from 90 to 95% and those of TN were from 80 to 83% under the N loading rate of 0.035 and $0.058{\;}kg{\;}N/m^3{\cdot}d$, respectively. The patterns of TN removed were distinctively different on the limit of 50cm of column in depth. This indicated that the nitrification and denitrification occurred near the surface zone of and inside the biofilm respectively, upto the 50cm of the column in depth.

• 분석과학
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• 제8권4호
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• pp.829-834
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• 1995

Whole column coldtrapping(WCC) on a fused silica capillary (FSCC)combined with GC/MS analysis was evaluated for use in the investigation of volatile organic compounds(VOCs) in indoor air. Research had indicated that a temperature of $-80^{\circ}C$ is optimal for WCC. Samples were analyzed on a $50m{\times}0.2mm$ cross-linked 5% phenylmethylsilicone fused silica column. Liquid nitrogen was used as the coolant for the peak resolution significantly. The analysis can be performed quickly and conveniently. More than 112 of VOCs were determined in the samples from three typical indoor environment including: (1) a room which had just been decorated involving building materials and paints; (2)a kitchen used for Chinese cooking, and (3) a room had tobacco smoke. The method is could be readily applied to rapid sample screening for VOCs contamination surveys or initial investigations with its valid and simple sampling and analytical technique.