• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.397-407
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• 2017

In this study, a SCR system is employed to selectively reduce $NO_X$, which is a major cause of environmental pollution and issues in diesel engines. In particular, this paper focuses on the combination of feedforward injection strategies, depending on the NO/$NO_X$ ratio, and feedback injection control, using $NH_3$ coverage ratio, based on a SCR model. A 2.2 L passenger diesel engine, which is equipped with a diesel oxidation catalyst (DOC) and a diesel particle filter (DPF), was used in the experiments. The developed control algorithm is implemented on a real-time computer with injection control algorithm. By analyzing the $NO_X$ emission measurement, the performance of the proposed injection control algorithm is verified.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.699-707
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• 2007

This study was carried out to investigate the reaction characteristics of corona/catalyst hybrid $DeNO_x$ process. The experiments were performed by using the multi-staged pin-to-hole type corona reactor which is enable to control the pin-to-hole gap and to insert the catalyst. Also, used for this study, were catalysts which commercially used Pt, Pd and $TiO_2$, and oxygen and hydrocarbon ($C_2H_4$) as reagents. In the syn-gas test, at high temperatures in the range of $100{\sim}200^{\circ}C$, the corona-only $DeNO_x$ process did not reduce the $NO_x$ concentration effectively. However in the presence of ethylene and oxygen as reagents, the $NO_x$ removal efficiency was better at these high temperatures than corona-only $DeNO_x$ process. In addition, coronal catalyst hybrid process with $TiO_2$ showed more efficiency of $NO_x$ removal than Pt and Pd catalyst, because the $TiO_2$ catalyst was more active than Pt and Pd catalyst to converse the $NO_2$ to $HNO_3$. Furthermore, at the condition of real diesel exhaust gas, the $DeNO_x$ efficiency of corona/catalyst hybrid process was not good at higher reaction temperature and plasma density.

• Proceedings of the KSME Conference
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• 2001.06d
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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.

• Journal of Hydrogen and New Energy
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• v.11 no.1
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• pp.1-9
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• 2000

The goals of this research are to understand the $NO_x$ emission in direct injected diesel engine with premixed hydrogen fuel. Hydrogen fuel was supplied into the test engine through the intake pipe. Amount of hydrogen-supplemented fuel was 70 percent basis heating value of the total fuel. The effects of exhaust gas recirculation(EGR) on $NO_x$ emission were studied. The exhaust gas was recirculated to the intake manifold and the amount of exhaust gas was controlled by the valve. The major conclusions of this work include: (i) the tested engine was run without backfire under 70 percent hydrogen fuel supplemented; (ii) the peak cylinder pressure was decreased with increase of EGR ratio due to the decrease of oxygen concentration in an intake pipe; and (iii) $NO_x$ emission was decreased by 77% with 30% EGR ratio. Therefore, it may be concluded that EGR is effective method to lower $NO_x$ emission in hydrogen fueled diesel engine.

• Clean Technology
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• v.21 no.3
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• pp.184-190
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• 2015

Most of LNT catalysts use noble metals such as Pt for low temperature NO_x oxidation but there is an economic weakness. For the purpose of overcoming this, this study is to develop DeNO_x catalyst for LNT excluding PGM (platinum group metal) such as Pt, Pd, Rh, etc. To do so, Al/Co/Ni catalyst selected as a preliminary test is used to study fundamental property and NO_x’s conversion according to calcined temperature. Ultimately, that is, Al/Co/Ni mixed metal oxide which does not use PGM is selected and physicochemical characterization is performed by way of XRD, EDS, SEM, BET and ramp test and NO_x conversion is also analyzed. This study shows that all samples consist of mixed oxides of spinel structure of Co₂AlO₄ and NiAl₂O₄ and have enough pore volume and size for redox. But as a result of NH₃-TPD test, it is desired that calcined temperature needs to be maintained at 700 ℃ or lower. Also only samples which are processed under 500 ℃ satisfied NO and NO_x conversion simultaneously through ramp test. Based on this study’s results, optimum calcined temperature for Al/Co/Ni=1.0/2.5/0.3 mixed metal oxide catalyst is 500 ℃.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.203-206
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• 2000

In this experiment, an attempt to use pellets($BaTiO_3$, $TiO_2$, ${\gamma}-Al_2O_3$, sludge) for $NO_x$ removal was conducted The effect of pellets on NO removal from simulated flue gas was experimentally investigated for packed-bed reactor of plate-plate geometry. An experimental investigation has been conducted for NO concentration of 50ppm balanced by air, and gas flow rate of $5{\ell}/min$. Ceramic pellets were used for surface discharge and the sludge pellets was added on $BaTiO_3$ and $TiO_2$ to increase $NO_x$ removal rate. In the result, $NO_x$ removal rate using $TiO_2$ was better than other pellets. $NO_2$ segnificatly generated by using $BaTiO_3$ pellets and sludge pellets used with $BaTiO_3$ decreased $NO_2$ generation.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.372-376
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• 2015

The experiment was performed using the cleaning precipitator To investigate the absorption efficiency of the $SO_X/NO_X$ of the aqueous ammonia solution. Concentration of the cleaning liquid is 0.1, 0.5, and 1.0% with increasing absorption efficiency has improved. However, the reaction shown only a difference in time. Absorption efficiency has improved in accordance with the gas residence time. When the direction of the same gas and the cleaning liquid is determined that there is the effect of increasing the residence time. The relative impact of $SO_X$ and $NO_X$ is this likely to react slower than $SO_X/NO_X$. The yield is determined to require adjustment of the cleaning dust collector according to the concentration of the next gas.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.487-495
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• 2010

The purpose of this study was conducted to make a comparative biomechanical analysis of X-factor and X-factor stretch during driver and iron swing. The subjects were composed of 10 professional golfers with more than 10 years career. The result was as follows: First, the analysis of the back swing with driver and iron swing showed no differences statistically between both the timing in horizontal rotating of shoulder and hip, the time required for X-factor stretch also showed no differences statistically. Second, the back swing with a driver swing showed more maximum horizontal rotation of shoulder and hip joint than the back swing with an iron swing, but the twist of shoulder and hip that was X-factor stretch angle showed no difference. Third, the GRF of the max value for the left and right foot during shoulder and hip horizontal rotation of back swing showed no differences statistically in the movement of driver and iron swing during the back swing, and the GRF of X-factor stretch for the left and right foot showed no differences statistically in driver and iron swing. Therefore the result of this research showed that the operation of torso(X-factor stretch) and weight shifting were similar although the horizontal rotation of body was different during the driver and iron swing.

• Journal of Sensor Science and Technology
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• v.18 no.4
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• pp.263-268
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• 2009

With the increasing number of automobiles, the problem of air pollution from the exhaust gases of automobiles has become a critical issue. The principal gases that cause air pollution are nitrogen oxide or NO$_x$(NO and NO$_2$), and CO. Because NO$_x$ gases cause acid rain and global warming and produce ozone(O$_3$) that leads to serious metropolitan smog from photochemical reaction, they must be detected and reduced. Mixtures of WO$_3$ and $In_2O_3$(WO$_3$:$In_2O_3$=10:0, 7:3, 5:5, 3:7, and 0:10 in wt.%), which are NO$_x$ gas-sensing materials, were prepared, and thick-film gas sensors that included a heater and a temperature sensor were fabricated. Their sensitivity to NO$_x$ was measured at 250$\sim$400$^{\circ}C$ for NO$_x$ concentrations of 1$\sim$5 ppm. The $In_2O_3$ thick-film sensor showed excellent sensitivity($R_{gas}/R_{air}$=10.22) at 300$^{\circ}C$ to 5-ppm NO. The response time for 70 % saturated sensitivity was about 3 seconds, and the sensors exhibited very fast reactivity to NO$_x$.

• Clean Technology
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• v.22 no.3
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• pp.141-153
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• 2016

Numerous stationary NO_x emission sources have employed a suitable deNO_x technology that is typically selective catalytic reduction (SCR) of NO_x by NH₃ over V₂O₅/TiO₂-based catalysts with on-demand monolithic structures. These structured catalysts undergo a time-on-deterioration of deNO_xing activity on site. Thus, we need more efficient, more deactivation-tolerant, more economic deNO_x systems and for which, their performance management is essential. This review has covered details of strategies to successfully manage the performance of SCR catalysts and timely replace them to new or rejuvenated ones. Key considerations to maintain the catalyst activity will be reviewed. Details of the sequential addition of new catalysts and the replacement of life-end catalysts and their regeneration will be discussed with general guidances to determine the time for such a replacement. Finally, a better way to get more economic approaches to deNO_x system management will be proposed here.