• 한국염색가공학회지
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• 제21권3호
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• pp.1-9
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• 2009

Polycarboxylics acids are used as crosslinking agents for cotton cellulose to produce durable finished press cotton fabric. It has been observed that the strength of the cotton fabric treated with polycarboxylic acids showed significant reduction as a result of the crosslinking process. The effect of acid-catalyzed depolymerization on the tear strength of cotton fabric is investigated by evaluating the cotton fabric treated by succinic acid, which does not crosslink cotton cellulose and form little ester on the cotton fabric. We find that the tear strength of cotton fabric treated with succinic acid decreases at elevated temperature due to acid-catalyzed depolymerization of cellulose. The magnitude of fabric strength reduction increases as the acid concentration increases. At a constant acid concentration, it increases as the curing temperature and time increases. It decreases as the pH of the acid solution increases. We also find that the dissociation constant of an acid also has a significant effect on the fabric strength reduction. The magnitude of fabric tear strength reduction increases as the acid dissociation constant decreases.

• International Journal of Automotive Technology
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• 제7권7호
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• pp.763-768
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• 2006

Emission reduction in the cold start period of SI engines is crucial to meet stringent emission regulations such as SULEV Emissoin reduction is the starting point of the study in the which the variable valve timing (VVT) technology may be one promising method to minimize cold start emissions while maintaining engine performance. This is because it is possible to change valve overlap and residual gas fraction during cold start and idle operations. Our previous study showed that spark timing is another important factor for reducing cold-start emissions since it affects warm-up time of close-coupled catalysts (CCC) by changing exhaust gas temperature. However, even though these factors may be favorable for reduction of emissions, they may deteriorate combustion stability in these operating conditions. This means that the two variables should be optimized for best exhaust emissions and engine stability. This study investigated the effects of valve and spark timings in idle performance such as combustion stability and exhaust emissions. Experiments showed that valve timings significantly affected engine stability and exhaust emissions, especially CO and $NO_x$, due to change in residual gas fraction within the combustion chamber. Spark timing also affects HC emissions and exhaust gas temperature. Yet it has no significant effects on combustion stability. A control strategy of proper valve timing and spark timing is suggested in order to achieve a reduction in exhaust emissions and a stable operation of the engine in a cold start and idle operation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.776-779
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• 2003

To reduce the storage space of spent fuel used at the atomic power plants in the over the world, the uranium elements contained in the spent fuel is being extracted and effectively stored. For this, the spent fuel are oxidized and deoxidized. In this study, it is produced the heat-resisting methods about the spent fuel management technology research and test facility for the spent fuel waste for spent fuel minimized. The first considered processes in the facility are the electrolytic metal reduction reactor process. Since the electrolytic metal reduction reactor is operated at the high temperature range, we have to consider the heat-resisting methods for the devices. For the heat-resisting methods, we have searched and analyzed technical reference for the heat-resisting methods. We have calculated thermal stress and strain of each devices by the commercial analysis software, ANSYS. D.S. It is experimented for inspecting confidence rate of analysis results. By using the results, we have analyzed the problems of parts and determined the heat-resisting material, commercial parts, and the size of parts and O-ring. Based on these results, it is produced the heat-resisting methods of magnesia filter, cathode, and reactor for the electrolytic metal reduction reactor.

• 한국정밀공학회지
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• 제30권7호
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• pp.667-672
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• 2013

This paper presents the development of a condition monitoring system that monitors the operating conditions of a reduction unit, such as the bearing temperature, gearbox vibration, and gear oil deterioration, and notifies the operator of potential problems or abnormal conditions. A series of field tests on high-speed rail and conventional lines was performed to identify the characteristics of temperature rise and vibration levels on the reduction unit during operation. The monitoring system was designed based on the proper sensor selection, measurement method, and signal analysis to optimize the interface with the operating system of high-speed trains. Application of this monitoring system to high-speed trains will play an important role in their proper maintenance and safe operation.

• 한국콘텐츠학회논문지
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• 제11권8호
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• pp.468-474
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• 2011

연료전지에 사용되는 백금촉매 제조 공정상의 변수로서 환원제를 사용 하였다. 환원조절 횟수, 환원온도, 환원제의 양 그리고 공정시간의 네 가지의 제어인자에 변화를 주어 입자의 크기와 ICP 수율 등의 촉매 구조에 관한 최적화의 평가를 위해 six sigma 의 design of experiment 기법을 사용하여 각각의 변수간의 최적점을 확인해 보았다. 부분요인배치를 통해 입자크기 2.2nm 이하와 ICP수율 75% 이상의 촉매제조를 위하여 도출된 결과로서 주된 제어인자는 환원 시간과 환원 온도로서 밝혀졌고 각 변수의 최적 조건으로서는 환원조절횟수 1회, 환원온도 $67-88^{\circ}C$, 환원제의 양 0.5ml 그리고 10분의 공정시간에서 최적화가 이루어졌다.

• 한국정밀공학회지
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• 제25권11호
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• pp.83-89
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• 2008

The Effect of Space Velocity(SV) on NOx conversion rate was performed to develop NOx reduction after-treatment system. SV is calculated from engine exhaust gas volume and SCR catalyst volume. Found the Urea injection duty of maximum efficiency for NOx conversion if increase SV, NOx Conversion rate is down. Especially, when SV is more than $110,000h^{-1}$, NOx conversion rate decrease suddenly. Same case, if SV is lower than $40,000h^{-1}$, NOx conversion rate is down. Also, the characterization of Urea-SCR system was performed. Three candidate injectors for injecting Urea were tested in terms of 속 injection rate and NOx reduction rate. The performances of SCR catalytic converter on temperature were investigated. The performance of Urea-SCR system was estimated in the NEDC test cycle with and without EGR. It was found that nozzle type injector had high NOx conversion rate. SCR catalytic converter had the highest efficiency at the temperature of $350^{\circ}C$. EGR+Urea-SCR system achieved NOx reduction efficiency of 73% through the NEDC test cycle.

• 한국염색가공학회지
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• 제21권6호
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• pp.12-21
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• 2009

The dyeing property of direct-spinning type and seaisland type 0.2D micro polyester nonwoven fabrics was characterized by three disperse dyes (Dorosperse Red KFFB, Blue KGBR, Yellow KRL) at $120^{\circ}C$ and $130^{\circ}C$. Before and after reduction cleaning, dyeing fastness was evaluated and the thermomigaration after heat setting at $180^{\circ}C$ for 60 min were also evaluated. Direct-spinning type fabric showed better dyeing property, wash fastness, and light fastness, but worse rub fastness than seaisland type fabric. The dyeing property and fastness of direct-spinning type fabric increased at higher dyeing temperature, whereas seaisland type fabric exhibited lower dyeing fastness and the increase of thermomigration at higher dyeing temperature. Non-fixed dye in fiber surface was removed by reduction cleaning process, then dyeing fastness was improved and thermomigration decreased. The higher dye uptake of direct-spinning type non-woven fabric caused the increase of dye molecule migration from fiber internal to fiber surface, so this fabric showed larger thermomigration than seaisland type non-woven fabric.

• 한국자동차공학회논문집
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• 제8권5호
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• pp.47-53
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• 2000

To overcome the shortage of conventional TWC that is activated at high temperature, higher than 25$0^{\circ}C$, photocatalyst is considered as an new technology. Because the photocatalytic reaction of photocatalyst is not a thermo mechanical reaction, it is necessary to heat the system to start the reaction. It can be activated just by ultra violet light that includes wavelengths shorter than 400 nanometers even at ambient temperature. In this study photocatalytic reduction of hydrocarbon was investigated with a model gas test. To understand the effects of co-existence gases on the hydrocarbon reduction by photoreaction, CO and NO, $O_2, H_2O$ gases those are components of exhaust gases of gasoline engine are supplied with C3H8/N2 to a photoreactor. The photoreactor contains $TiO_2$ photocatalyst powders and a UV bulb. The results show that oxygen is the most important factor to reduce HC emission with photocatalyst. Photocatalyst seems to have a good probability for automotive application to reduce cold start HC emissions.

• 대한기계학회논문집B
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• 제30권8호
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• pp.788-795
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• 2006

From the view of the environmental protection against the use of fossil fuels, the great of efforts have been exerted to find an effective method which is not only pollutant reduction but also high thermal efficiency. Reburning is a useful technology in reducing nitric oxide through injection of a secondary hydrocarbon fuel. In this paper, an experimental study has been conducted to evaluate the hybrid effects of reburning and selective non-catalytic reaction (SNCR) on $NO_x/CO$ reduction from oxygen-enriched LPG flame. Experiments were performed in flames stabilized by a co-flow swirl burner, which was mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The paper reported data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. Overall temperature in the furnace, heat fluxes to the wall and $NO_x$ generation were observed to increase by oxygen-enriched combustion, but due to its hybrid effects of reburning and SNCR, $NOx/CO$ concentration in the downstream has considerably decreased.

• 한국표면공학회지
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• 제50권2호
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• pp.114-118
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• 2017

Bismuth telluride ($Bi_2Te_3$) and its alloys are well-known thermoelectric materials for ambient temperature applications. In this study, the dissolved Bi-Te precursor solution was used to synthesis metallic $Bi_2Te_3$ powder via ultrasonic spray pyrolysis and reduction process. The droplets of the Bi-Te precursor solution were decomposed to Bi-Te oxide powders by ultrasonic spray pyrolysis. The spherical $Bi_2Te_3$ powders were synthesized by reduction reaction in atmosphere of hydrogen gas at the temperature above $375^{\circ}C$ for 6h. The reduced $Bi_2Te_3$ powders have a mean particle size of $1.5{\mu}m$. The crystal structure of the powder was evaluated by X-Ray diffraction(XRD), and the microstructure with size and shape powders was observed by fieldemission scanning electron microscope(FE-SEM) and transmission electron microscope(TEM).