• 공학기술논문지
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• 제11권4호
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• pp.253-257
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• 2018

Exhaust gas from the combustion of automobiles adversely affects the human body and even pollutes the atmosphere. This study investigated the influence of exhaust gas change on intake manifold using the nozzle. First, the flow analysis was performed using the 3D flow analysis program. When the nozzle inlet air velocity increased, the average air velocity in the nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$ increased 37.3% and 31.9% respectively at the intake manifold outlet. As the nozzle inlet air velocity increased, the maximum flow rate of air increased to 42.2% and 32.6%, respectively at nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$. In order to verify the analysis results, experiments on the exhaust gas were performed in the engine simulation system. As the nozzle inlet velocity increased, HC values decreased by 42.4% and 31.4% at nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$, respectively. And CO values decreased by 40.7% and 31.1% at nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$.

• 설비공학논문집
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• 제21권8호
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• pp.448-455
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• 2009

A performance analysis of the regenerative gas turbine system with afterfogging is carried out. Because of the high temperature at the outlet of air compressor, afterfogging has a potential of improved recuperation of exhaust heat than inlet fogging. Thermodynamic analysis model of the gas turbine system is developed by using an ideal gas assumption. Using the model, the effects of pressure ratio, water injection ratio, and ambient temperature are investigated parametrically on thermal efficiency and specific power of the cycle. The dependency of pressure ratio giving peak thermal efficiency is also investigated. The results of numerical computation for the typical cases show that the regenerative gas turbine system with afterfogging can make a notable enhancement of thermal efficiency and specific power. In addition, the peak thermal efficiency is shown to decrease almost linearly with ambient temperature.

• Advances in environmental research
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• 제2권1호
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• pp.1-8
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• 2013

There is a significant demand to make various dissolved gases in water. However, the conventional aeration method shows low gas mass transfer rate and gas utilization efficiency. In this study, a novel rotating wheel entraining gas method was developed for making high dissolved $O_2$ and $O_3$ in water. It produced higher concentration and higher transfer rate of dissolved $O_2$ and $O_3$ than conventional bubble aeration method, especially almost 100% of gas transfer efficiency was achieved for $O_3$ in enclosed reactor. For application of rotating wheel entraining gas method, aerobic bio-reactor and membrane bio-reactor (MBR) were successfully used for treatment of domestic and pharmaceutical wastewater, respectively; and vacuum ultraviolet $(VUV)/UV+O_3/O_2$ reactors were well used for sterilization in air/water, removal of dust particles and toxic gases in air, and degradation of pesticide residue and sterilization on fruits and vegetables.

• 한국대기환경학회지
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• 제21권3호
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• pp.285-293
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• 2005

This study was aimed at estimation of gas-particle partitioning of polychlorinated biphenyls (PCBs) in ambient air. The samples were collected at urban site in Japan from March 2002 to January 2003. The concentration of total PCBs (from 4 CB to 10 CB) and TEQ (Toxic equivalent) ranged from 62 to $247\;pg/m^3$ and from 2 to $14\;fgTEQ/m^3 $, respectively. The average contribution $(\%)$ of gas phase to total PCBs concentration was above $80\%$, which suggests that in the atmosphere PCBs predominantly existed in the gas phase. The weak correlations between total PCBs concentration and temperature was found. However this result was due to a typhoon during summer and raining during sampling period. The gas-particle partition coefficient (Kp) was obtained as a function of temperature. The partition ratio of gaseous and particulate phase PCBs can be estimated for an arbitrary temperature. The plot of gas/particle partition coefficient (log Kp) vs. sub-cooled liquid vapor pressure $(log\;P_L)$ had reasonable correlations for individual samples but the slope varied among the samples (coefficients of determination for log Kp versus log $P_L$ plot were> 0.76 $(p<0.0001)$, except for 3 samples). As a result, the variations in the slope among the sampling period may be due to change of temperature, raining during sampling period and wind in this study.

• 한국산업융합학회 논문집
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• 제21권6호
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• pp.429-437
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• 2018

The process gas piping of the offshore plant can cause a massive explosion if the gas leakage occurs during operation. For the purpose of precaution of gas leakage accident, an air pressure test is performed on the process equipment tests using a test pump as much as the power to the piping inner side, mix 99% nitrogen gas and 1% helium gas. The purpose of the air pressure test is to check the work conformity process by handling and regulation for initial piping process, assembly, installation of module, welding, center alignment of the pipes assembling flange gasket in an unrestrained free state. In this paper, the regulation of the problematic air pressure test was analyzed and the solution criteria were established. And leakage tests of existing equipment were performed applying these solution methods. As a result, it was confirmed that there was no problem.

• 한국가스학회지
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• 제21권3호
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• pp.53-60
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• 2017

연소로에서 질소산화물을 저감하기 위하여 여러 가지 방법으로 연구가 진행되어 오고 있는데 그 중에 배기가스를 재순환하여 저감하는 방법이 있다. 본 연구는 배기가스를 재순환하는 방법으로 연소로 외부에 코안다 노즐을 이용하여 배기가스를 재순환 유입하는 방법을 사용하였다. 코안다 노즐을 이용하여 배기가스를 재순환하고 혼합가스는 연소로 접선 방향으로 투입하여 선회유동을 유발하는 특징을 가지는 배기가스 재순환 버너이다. 이러한 버너에서 연소로 내의 선회 유동 특성을 살펴보고 온도와 반응속도 분포를 살펴봄으로써 코안다 노즐을 이용한 재순환 버너의 연소 유동 특성을 규명하였다. 과잉공기계수와 코안다 노즐 간격을 변화하여 배기가스 재순환 유입량 특성을 살펴보았으며 과잉공기계수를 증가하면 재순환 유입량비가 증가하였고 코안다 노즐 간격을 증가하면 코안다 노즐 공기 출구에서 속도가 낮아져서 재순환 유입량이 감소한다는 특성을 알았다. 배기가스 출구에서 평균온도는 코안다 노즐 간격 변화에 거의 무관하며 과잉공기계수 증가에 따라 감소하는 것을 알았다. 이러한 특성으로 배기가스 출구에서 NOx 농도는 과잉공기계수 증가에 따라 현저히 감소하고 코안다 노즐 간격에는 상대적으로 영향이 적은 것으로 나타났다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
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• pp.51-56
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• 2001

An experiment using preheated air in the coaxial diffusion flame burner was carried out in order to decrease NOx emission and improve the thermal efficiency. Preheated air combustion generally produces high NOx emissions but it was known very well to reduce NOx emission by diluting the combustion air with inert gas in preheated air combustion. In our study, $N_2$ gas was used for diluent and propane was utilized for fuel. We set the combustion air temperature on 300K, 500K, 700K, 900K and dilution level from 21% to 10% in terms of oxygen concentration. NOx emission increased along increment of combustion air temperature and decreased along increment of dilution level(lowering of oxygen concentration in combustion air). Flame-off limit with dilution level enhanced, flame length became longer and the location of maximum flame temperature became lower with increasing of combustion air temperature.

• 항공우주기술
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• 제9권2호
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• pp.98-104
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• 2010

대기 중의 수증기는 가스터빈엔진의 주요성능에 많은 영향을 끼친다. 습공기의 영향은 기온 및 기압이 높은 여름철 해면 고도, 높은 비행 마하수 그리고 낮은 엔진 회전수에서 이 더욱 두드러진다. 이러한 습공기 유입에 따른 가스터빈 엔진의 성능변화의 정도를 살펴보고자 가스터빈 시뮬레이션 프로그램(GSP)과 200lbf 급 초소형 터보제트 엔진의 고공환경 성능시험을 통해 습도가 엔진성능에 미치는 영향에 대하여 알아보았다. 고공환경 엔진시험을 통해, 건공기 유입에 비해 습공기 유입 시 순추력에서 2.826% 낮게, 비연료소모율에서 1.325% 높게 측정되었다.

• 대한기계학회논문집B
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• 제24권10호
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• pp.1294-1299
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• 2000

The combustion characteristics have been investigated to develop the 50 kW-class gas turbine combustor. The combustor design program was developed and applied to design this combustor. The combustion air which has the temperature of 45, 200, $300^{\circ}C$ were supplied to combustor for elucidating the effect of inlet air temperature on CO, NOx emissions and flame temperature. The exit temperature and NO were increased and CO was decreased with increasing inlet air temperature. Also, the effect of equivalence ratio was considered to verify the combustor performance. The emissions of CO and NO with inlet air temperature can be analyzed qualitatively by measuring the temperature inside the combustor. The combustion performance with fuel schedule was evaluated to get the informations of the starting and part loading process of gas turbine. The combustion was stable above the equivalence ratio of 0.18. The pattern factor which is the important parameter of combustor performance was satisfied with the design criterion. Consequently the combustor was proved to meet the performance goal required for the target gas turbine system.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.149-157
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• 2004

In the present paper we studied experimentally fundamental optimization of oxygen enriched pyrolysis melting incinerator, Characteristics of this system was confirmed dealing with the gas flow and combustion properties for the inside secondary air injection. The experiment setup has a disposal rate of 30kg/hr which was measured by the inside temperature and gas. Along with above experiments, the three-dimensional computation was employed to analyse the combustion fluid dynamics and gas residence time. Equations for turbulence and heat - transmission as well as chemical reactions were solved by using common codes. The experimental combustion chamber was composed of staged combustion types structure for reducing NOx. Finally, it was verified that the control of the secondary air and air ratio of thermo stack were important. In the computational analysis, it showed reasonable agreement with the experimental results regarding the temperature and discharged gas concentration.