• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.23-26
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• 2007

A preliminary， study of low temperature condition was performed to simulate high altitude condition. The mixed air temperature were investigated at various condition by experiments using cryogenic air by heat exchanger and normal temperature air. An experimental setup was constructed to simulate low temperature condition with liquid nitrogen. To control mass flow rate, orifice and pressure regulators were used. The experimental results show that the mixed air temperature increases linearly with mass flow rate of normal temperature air. Therefore it can be help to simulate a low temperature condition of high altitude.

• The Korean Journal of Food And Nutrition
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• v.17 no.2
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• pp.206-211
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• 2004

It is very important to minimize the acid value of oil in the oil and fat industry, because acid value of oil products are a indicator quality. This study was performed to investigate change of moisture content, acid value and free fatty acid content by drying condition such as drying method, temperature and drying time on steamed duck egg york. Also, change of fatty acid composition by acid value. The acid values, moisture contents and free fatty acid contents were showed comparatively lower value by spray drying and freeze drying than by steam drying. but difference that keep in mind between each drying method was not looked. Whereas moisture content, acid value and free fatty acid content of effect of drying temperature reaches in lowest value. also, did not show change until dry 12hours reaching to lowest value by 3.1, 3.0％ and 0.98％ after dry 9hours both moisture content, acid value and free fatty acid content. Also, acid value increase, free fatty acid was increased, where unsaturated fatty acid showed that decrease rapidly.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.529-552
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• 2004

We made a robust catalogue of reliable records of meteor showers and storms recorded in Korean, Japanese, and Chinese chronicles. In our new catalogue, there are 35 Korean records, 29 Japanese records, and 93 Chinese records. The temporal frequency distribution of records shows two broad peaks around the 10th and the 16th centuries. We observed that the peak in the 10th century is mainly contributed by the Perseids, while the peak in the 16th century was mainly contributed by the Leonids. We found that the ${\eta}-Aquarids$, the Perseids, the Orionids, and the Leonids have been active during the last two millennia. The oldest record of the ${\eta}-Aquarids$ is that of BC 687 in China, and the oldest record of the Perseids is that of 36 AD. Contrary to previous investigations, there has been no nodal shift of the ${\eta}-Aquarids$ and the Orionids, whose mother comet is the Halley's comet. The oldest record of the Leonids is probably that of 288 AD, instead of 902 AD. We also find some evidence on the existence of a possible shower a-Draconids. We note that our catalogue will be useful to investigate meteor showers.

• Journal of Energy Engineering
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• v.13 no.1
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• pp.34-39
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• 2004

The process of energy separation in a low pressure vortex tube with compressed air as a working medium is studied in detail. Experimental data of the temperature of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the inner surface of a vortex tube and the temperature distribution in a vortex tube provide useful information about the location of the stagnation point of the flow field at the axis of the vortex tube Analysis of the results enabled to find the optimum ratio of nozzle area and the optimum shape of an orifice. From this optimum geometric setup of a low pressure and big vortex tube the effectiveness of energy separation was better than a high pressure and small vortex tube.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.133-136
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• 2008

The present study presents experimental results of combustion tests of a fuel-rich gas generator associated with a turbopump. Five combustion tests had been successfully executed. Static pressures of the gas generator promptly reacted to propellant supply variations from the turbopump. A closed-loop test for driving the turbopump revealed no flaw. Exit gas temperature results are very similar to previous ones. An orifice was effective on the suppression of pressure fluctuations although tests conducted below 45 bar showed the same dynamic behaviour as that of component-only tests.

• Journal of Korean Society of Forest Science
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• v.39 no.1
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• pp.57-63
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• 1978

Enzymatic hydrolysis of the substrate from Alnus hirsuta (Spach) Rupr (8-14years) was investigated using cellulase preparations of Trichoderma viride Pers. ex. Fr. SANK 16374 and conduced on the optimum reaction conditions of the cellulase on saccharification. The crude cellulase was produced by the submerged culture process and produced in the culture fluid was salted out quantitatively by the use of ammonium sulfate. The method of delignification from wood(Saw dust) was treated by the peracetic acid (PA) method. Reducing sugar was determined by the dinitrosalicylic acid (DNS) method. The results were summerized as follows; 1. The optimum pH of cellulase was 5.0 and the range of stability with respect to pH was generally from 4.0 to 6.0 2. The optimum temperature of cellulase was generally $40^{\circ}C$, but reducing sugar formation did not show significent differences at 5% levels in the reaction temperature from $40^{\circ}C$ to $50^{\circ}C$. 3. The redusing sugar were increased with increase of cellulase concentration. 4. The reducing sugar were decreased with increase of substrate concentration. 5. Fructose was a very good inhibitor of the enzyme from Trichoderma viride, but glucose inhibition was generally weak.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.839-854
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• 2018

This study was performed to evaluate the performance of GFRP plate reinforced segments for TBM tunnel support. Recently, the SFRC segment has been applied to prevent local damage such as reduction of the amount of reinforcing bars of the segment, crack control and breakage. However, the steel fiber used in the SFRC segment has a problem of durability deterioration due to fiber corrosion. Compared with the RC segment, the maximum flexural load reduction of the SFRC segment hinders the broad application range of the TBM tunnel segment. Therefore, GFRP plate was considered as a stiffener for the maximum load increase of SFRC segment, and structural synthetic fiber without corrosive concern was used as a substitute for steel fiber. The flexural performance of the segment was evaluated by using the type of reinforcing fiber and GFRP plate thickness as the main parameters. As a result, the maximum load and the flexural toughness were increased by 21.78~23.03% and 0.5~7.96%, respectively, as compared with the segments reinforced with reinforcing fiber and GFRP plate of 3 mm thickness.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.39-46
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• 2020

This study evaluated the nitrogen oxide (NO_x) removal efficiency by air purification concrete blocks with titanium dioxide (TiO₂). The concrete in the mixtures had a 30% water:cement ratio, to which TiO₂ was added at 0%, 5%, and 10% of cement weight. The compressive strength reduction rate and removal efficiency of NO_x were investigated. The result of the compressive strength test in the study indicated that addition rate of TiO₂ did not lead to signifcant effect. In terms of the average removal efficiency of NO_x, mix No. 1 using a TiO₂ mixing ratio of 0% had a removal efficiency of 0.57% on average; thus, the removal effect w as not significant. For the other samples prepared by mixing, the average removal efficiencies for mix No. 2 (5% TiO₂) were 58.86% and 62.05% for normal and washing surface treatments, respectively, and those of sample No. 3 (10% TiO₂) were 59.94% and 67.61%. mixs No. 4 (5%) and No. 5 (10%), in which TiO₂ diluted with distilled water was sprayed onto the block surface, had an average NO_x removal efficiency of 61.72% and 68.48%, respectively. In terms of NOx removal efficiency, Mixs No. 3 and No. 5 with 10% TiO₂ were better than Mixs No. 2 and No. 4 with 5% TiO₂. In addition, analyzing the NO_x removal efficiency results from the fixing method, it was capable to apply mixing (washing) and the diluted spray methods. Therefore, it was found that the diluted spray method applied in this study can be employed in any manufacture of air purification concrete blocks.

• Asia Marketing Journal
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• v.12 no.4
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• pp.113-136
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• 2011

Product harm crises can distort long standing favorable equality perceptions, tarnish a company's reputation, cause major revenue and market-share losses, lead to costly product recalls, and devastate a carefully nurtured brand equity. However, in spite of the devastating impact of product-harm crises, little systematic research exists to asses its marketing consequences. So, this study focuses on the negative publicity about companies and their products. Namely, this study presented how inclusion effect supported the relationship between negative publicity and consumers' response, market performance. According to the results, after negativity publicity was happened, it was appeared that the negativity image spread into other product lines(spillover effect; inclusion effect). Also, when they contact with the negative publicity, respondents negatively evaluated both production evaluation and corporate evaluation. And, in that case of the products with negativity publicity, compared with refutation strategy(defense strategy<study 2>), improving strategy(correction notice) had positive influence on recovery of sales, product evaluation, and corporate evaluation. Finally, as the reaction time toward negativity publicity was faster, the market performance got worse. Especially, according to two-way interaction, when the reaction time was fast, the difference between refutation strategy(defense strategy<study 2>) and improving strategy was not existed in product evaluation and corporate evaluation. However, when the reaction time was late(after a month), improving strategy had more positive evaluation than defense strategy in product evaluation, and corporate evaluation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1062-1070
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• 2016

The heat transfer and flow characteristics of gas turbine blade tip were investigated in this paper by using the conjugate heat transfer analysis. The rotor inlet boundary condition profile which was taken from the first stage nozzle outlet was used to analyse. The profile contained the velocity and temperature information. This study presents the influence of tip clearance about aerodynamic loss, heat transfer coefficient and film cooling effectiveness with the squealer tip designed blade model which tip clearance variation range from 1% to 2.5% of span. Results showed that the aerodynamic loss and the heat transfer coefficient were increased when the tip clearance was increased. Especially when the tip clearance was 2% of the span, the average heat transfer coefficient on the tip region was increased obviously. The film cooling effectiveness of tip region was increasing with decreasing of the tip clearance. There was high film cooling effectiveness at cavity and near tip hole region.