• Journal of Advanced Marine Engineering and Technology
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• 제23권4호
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• pp.543-551
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• 1999

Diesel engine is a major source of the air pollution. In general the concentrations of these pollu-tants in diesel engine exhaust differ from values calculated assuming chemical equibrium. Thus the detailed chemical mechanisms by which these pollutions form and the kinetic of these process-es are important in determining emission levels. In this study the computer program has been developed to calculate the required thermodynam-ic properties of combustion products(10 spacies) for both equilibrium and non-equilibrium in cylin-der for diesel engines. Nitric oxide emissions are calculated by using the extended Zeldovich Kinet-ic mechanism with a steady state assumption for the N concentration and equilibrium values used for H, O, $O_2$ and OH concentrations. By the results it is confirmed that developed simulations program with the NO prediction model is validated against residual mass fraction combustion index of Wiebe's functions pre-mixed com-bustion ration fuel injection timing.

• 식물조직배양학회지
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• 제26권4호
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• pp.259-264
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• 1999

애기장대 (Arabidopsis thaliana)생태종 'Columbia'의 잎절편 배양시 부정근, 모용 및 캘러스 형성에 미치는 에틸렌의 역할을 알아보고자 ACC, ethephon, CoCl$_2$및 AgNO$_3$의 영향을 조사하였다. 애기장대 잎 절편을 부정근 (0.1 mg/L NAA), 모용 (2.0mg/L NAA) 및 캘러스 (10.0mg/L - NAA)를 형성하는 MS 배지 각각에 ACC와 ethephon을 1-100mg/L 처리한 결과 부정근 형성구에서는 부정근이 감소 한 반면 모용이 유기되었고 모용 형성구에서는 모용이 감소한 반면 캘러스가 유기되었다. 또한 CoCl$_2$와 AgNO$_3$를 1-100mg/L 처리한 결과 부정근 형성구에서는 모용 형성 없이 부정근이 증가하였으며, 모용 형성구에서는 모용은 감소한 반면 부정근이 유기되었다. 그리고 캘러스 형성구에서는 ACC, ethephon, CoCl$_2$및 AgNO$_3$처리구 모두에서 캘러스 형성이 억제되면서 모용이 형성되었다.

• 대한기계학회논문집B
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• 제36권2호
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• pp.225-232
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• 2012

희박 예혼합 가스터빈 연소기에서 배출되는 NOx, CO 와 같은 오염물질을 예측하기 위해서 화학반응기 네트워크 모델을 개발했다. 본 연구에서는 CHEMKIN 코드와 4 가지 NO 생성 메커니즘을 포함한 GRI 3.0 메탄-공기 연소 메커니즘을 이용해서 가스터빈의 부하조건을 변화시키며 NOx 및 CO 배출의 예측을 수행하였다. 모델의 검증을 위해서 계산된 결과를 모사연소기의 실험 데이터와 비교하였다. 여러부하조건에 따른 4 가지 NO 경로의 기여도를 조사하였다. 또한 인젝터의 질량유동 및 당량비의 불균일성이 NOx 배출이 끼치는 영향을 고찰하고 10ppm 이하의 저 NOx 연소기 개발을 위한 저감 방법을 제안했다.

• 한국자원식물학회지
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• 제32권4호
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• pp.264-269
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• 2019

쉽싸리(L. lucidus)가 가지는 효능의 하나로 알려진 항염증효과의 활성물질을 파악하기 위하여 본 연구를 수행하였다. 항염효과는 LPS로 활성화한 macrophage 264.7이 생산하는 NO의 감소효과를 측정함으로써 평가하였다. 쉽싸리 추출물에서 얻은 비극성 분획물인 $CHCl_3$ 분획물은 농도의존적으로 현저히 NO 생산을 감소시켰다. 이에 비해 극성 분획물인 BuOH 분획물은 그 효과가 약하였다. Silica gel column chromatography에 의해 이 $CHCl_3$ 분획물로부터 주요 화합물인 ursolic acid를 분리하고 분광학적 방법으로 동정할 수 있었다. 효과가 약하였던 BuOH 분획물로부터 diaion HP-20 column chromatography와 sephadex LH-20 column chromatography로 이 분획의 주요 화합물인 rosmarinic acid를 분리하고 역시 분광학적 방법으로 동정하였다. Ursolic acid는 농도의존적으로 NO 생산을 억제하였으나 rosmarinic acid는 그 효과가 상대적으로 약하였다. 이러한 사실로부터 쉽싸리의 항염효과는 주로 ursolic acid의 존재 때문임을 알 수 있었다.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.46-52
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• 2009

In this study the predictions of NOx in methane-air lean premixed combustion in PSR were carried out with GRI 3.0 methane-air combustion mechanism and Zeldovich, nitrous oxide, prompt, and NNH NO formation mechanism by using CHEMKIN code. The results are compared to the JSR experimental data of Rutar for the validation of the model. This study concerns about the importance of the chemical pathways. The chemical pathway most likely to form the NO in methane-air lean-premixed combustion was investigated. The results obtained with the 4 different NO mechanisms for residence time(0.5-1.6ms) and pressure(3, 4.7, 6.5 atm) are compared and discussed.

• 대한기계학회논문집B
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• 제25권2호
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• pp.147-155
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• 2001

Experimental investigations were conducted for two hydrogen-nitrogen coaxial jet diffusion flames. A flame was a conventional coaxial jet diffusion flame and the other was a coaxial jet diffusion flame of which ambient air-jet turbulence was intensified. In this study, firstly two kinds of NOx measuring system were campared by using different convertors, secondly the NOx formation characteristics were investigated in order to examine the effect of turbulence intensity. In this study it is known that stainless convertor has some problem in the converting process from NO$_2$to NO in fuel rich region but molybdenum convertor can detect the amount of NOx correctly. The increase of turbulence intensity reduces the thermal NOx less than a half in our experiment and this effect is conspicuous near the nozzle. The conversion rate from NO to NO$_2$and the portion of NO$_2$among NOx are increased with turbulence intensity. These NOx measurements will help to understand the influences of turbulence intensity on NOx formation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.339-342
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• 2014

Rotary kiln produces lime from limestone through thermal decomposition. Ring formation in kiln internal wall is known issue that decreases productivity. The cause of ring formation is temperature imbalance as flame leans toward upper wall. Therefore, burner nozzle geometry was changed to improve air-fuel mixing state which leads to prevention of ring formation. CFD simulation and experimental test were performed in this study to investigate the effect of air-fuel mixing on flame structure, temperature and $NO_X$ concentration. It is shown that combustion efficiency has been enhanced and $NO_X$ concentration has been decreased by using swirl flow for secondary combustion air. It's also shown that flame has been straightened by using straight flow for secondary combustion air.

• 한국세라믹학회지
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• 제42권11호
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• pp.770-776
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• 2005

Hardening and hydroxyapatite(HAp) formation behavior of the bioactive cements in the system of $CaO-SiO_{2}-P_{2}O_{5}$ glasses and the corresponding glass-ceramics were studied. DCPD (Dicalcium Phosphate Dihydrate: $CaHPO_4{\cdot}2H_2O$) and DCPA (Dicalcium Phosphate Anhydrous: $CaHPO_4$) were developed when the prepared glass and glass-ceramic powders were mixed with three different solutions. The DCPD and DCPA transformed to HAp when the cement was soaked in Simulated Body Fluid (SBF), and this HAp formation strongly depended on the releasing capacity of $Ca^{2+}$ ions from the cements. The glass-ceramic containing apatite showed fast setting, but no HAp formation was observed because no $Ca^{2+}$ ions were released from this glass-ceramics. The compressive strength of the cements increased with reaction time in SBF until all DCPD and DCPA transformed to HAp.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.31-41
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• 2008

This paper deals with the energy saving problem of the follower aircraft in the loose leader-follower formation geometry in which the lateral separation between formation members is more than a wingspan of the leader aircraft. This formation geometry offers no drag benefit, but has a strategic advantage. In the case of loose formation flight, the follower aircraft usually consumes more energy than the leader aircraft because the follower aircraft should use more thrust to maintain given formation geometry, especially during the turning phase from the outside of the leader"s flight path or join-up phase. A formation control scheme based on the energy maneuverability is proposed in this paper. To design the proposed control law, the velocity command is designed using feedback linearization for the horizontal formation geometry and then coverts it to the altitude command using the energy equation. Numerical simulation is performed to verify the effectiveness of the proposed controller.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.115-120
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• 2001

The present study examined the possibility of $NO_{x}$ reduction in the high temperature industrial furnaces. duct burner of gas turbine cogeneration and two-stage gas turbine combustor. The experimental study was carried out for the diffusion flame of second stage combustor with the variations of oxygen concentration and supplying rate of hot exhaust gas from first stage combustor. It also examined the flammability range and $NO_{x}$ formation of the second stage combustor in which the fuel is supplying into the mixture of oxygen hot exhaust gas from first stage combustor. The results show that the enrichment of oxygen and increase of exhaust gas lead to increase the $NO_{x}$ up to 50 ppm with 23% $O_{2}$ condition.