• Proceedings of the KWS Conference
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• 2004.05a
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• pp.311-313
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• 2004

WC-12-17%Co powders with nano- and micro-structures were deposited by cold spray process using nitrogen and helium gases. The results show that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition as expected. It is also observed that nano-sized WC in the feedstock powder is maintained in the cold spray deposition. It is demonstrated that it is possible to fabricate the nano-structured WC-Co coating with low porosity and very high hardness (-2050 HV) by cold spray deposition with reasonable powder preheating.

• The Korean Journal of Food And Nutrition
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• v.5 no.2
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• pp.163-169
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• 1992

The changes in the various chemical compositions and textural properties of salted vegetables during salting and fermentation were reviewed with 25 papers published from 1981 to 1991 The changes in the texture of vegetables were largely affected by the properties of pectic substances, and additional factors such as salt type, salt concentration, salting time, temperature, preheating treatment, enzyme, salt mixtures, salt-fermented fish and garlic contents, were concerned complexly.

• Solar Energy
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• v.7 no.2
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• pp.54-64
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• 1987

Experiments on honeycomb structure collectors (HSC with/without cover) were performed and the experimental results showed good agreement with the preceding analytical results. The tendency of the efficiency of HSC was same with that of conventional air-type solar collector, even though there were some seasonal differences. Therefore, HSC, which can be itself utilized as a part of building structure, is applicable to space heating as well as preheating of industrial process and drying.

• Journal of the East Asian Society of Dietary Life
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• v.5 no.3
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• pp.359-370
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• 1995

Kimchi is a traditional fermented vegetable in Korea. It has unique taste and flavor due to the variability of raw vegetable, subingredient and their ratio of combination. Fermentation method have very critical effect on these charicteristics. Overall taste of Kimchi is also influenced by texture. In this paper, the changes in texture of Kimchis were reviewed related to pectic substance, enzymatic activities and other chemical changes during the fermentation of Kimchi. Moreover, treatments to prevent softening of Kimchi texture such as preheating, CaCl$_2$ addition, their combination effect and chitosan addition were summarized from the literatures.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.309-315
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• 2012

Metal foam has many excellent properties, such as light weight, incombustibility, good thermal insulation, sound absorption, energy absorption, and environmental friendliness. It has two types of macrostructure, a closed-cell foam with sealed pores and an open-cell foam with open pores. The open-cell foam has a complex macrostructure consisting of an interconnected network. It can be exploited as a degradable biomaterial and a heat exchanger material. In this paper, open cell Mg alloy foams have been produced by infiltrating molten Mg alloy into porous pre-forms, where granules facilitate porous material. The granules have suitable strength and excellent thermal stability. They are also inexpensive and easily move out from open-cell foamed Mg-Al alloy materials. When the melt casting process used an inert gas, the molten magnesium igniting is resolved easily. The effects of the preheating temperature of the filler particle mould, negative pressure, and granule size on the fluidity of the open cell Mg alloy foam were investigated. With the increased infiltration pressure, preheat temperature and granule sizes during casting process, the molten AZ31 alloy was high fluidity. The optimum casting temperature, preheating temperature of the filler particle mould, and negative pressure were $750^{\circ}C$, $400-500^{\circ}C$, and 5000-6000 Pa, respectively, At these conditions the AZ31 alloy had good fluidity and castability with the longest infiltration length, fewer defects, and a uniform pore structure.

• Journal of Welding and Joining
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• v.28 no.6
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• pp.70-75
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• 2010

This study intends to investigate the weldability and mechanical characteristics of butt weld joints by LAFSW for dissimilar materials (Al6061-T6 and SS400). At optimum welding conditions, the tensile strength of dissimilar materials joints made by FSW is found to be lower than that of LAFSW. Due to the increase in plastic flow and formation of finer recrystallized grains at the TMAZ and SZ by laser preheating in LAFSW, the hardness in LAFSW appeared to be higher than that of FSW. Compared with FSW, finer grain size is observed and elongated grains in parent metal are deformed in the same direction around the nugget zone in TMAZ of Al6061-T6 by LAFSW. Whereas, at weld nugget zone, coarse grain size is appeared in LAFSW compared to FSW, which is owing to more plastic flow due to laser preheating effect. In dissimilar materials joints by LAFSW, ductile mode of fracture is found to occur at Al6061 side with fewer brittle particles. Mixed mode of cleavage area and ductile fracture is observed at SS400 side.

• Journal of Acupuncture Research
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• v.15 no.2
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• pp.173-182
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• 1998

In order to evaluate calorie rate of moxa-combustion(direct moxibustion=DM, indirect moxibustion with stainless steel tube=IMS, indirect moxibustion with ginger slice=IMG), calorie rate(%) in the preheating period, heating period, retaining period, and cooling period was calculated respectively to the total combustion calories in all the periods. The result are as follow: 1. Indirect moxibustion with stainless steel tube had the highest rate with the statistical significance than other groups during the preheating period, represented statistical differences between IMS group and IMG group, and also between DM group and IMS group. 2. Indirect moxibustion with ginger slice group showed the highest rate with the statistical significance and followed by DM group and IMG group during the heating period, represented statistical difference among DM, IMS, and IMG group. 3. Direct moxibustion group had the highest rate with the statistical significance than other group during the retaining period, represented statistical difference between DM group and IMG group, and also between DM group and IMS group. 4. Indirect moxibustion with stainless steel tube had the highest rate with the statistical significance than other groups during the cooling period, represented statistical differences between IMS group and IMG group, and also between IMS group and DM group.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.9-14
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• 2011

The expansion work that is wasted through the irreversible expansion through the PC valve of decompression process of the natural gas governor station can be recovered by replacing the process by an isentropic expansion. The energy and exergy analyses for the two decompression process models of power producing and current decompression process model are presented. Analysis results showed that the exergy by gas supply is 56.29%, the exergy by producing power is 32.12 % in case of preheating system and 22.52% in case of non-preheating system. The dead exergy at the PCV is generated much more network. As these results, the usefulness of exergy analysis is verified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.2
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• pp.104-110
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• 2001

Structural, optical and electrical properties of Cd$_{1-x}$ Zn$_{x}$S films deposited by chemical bath deposition(CBD), which is a very attractive method for low-cost and large-area solar cells, are presented. Especially, in order to control more effectively the zinc component of the films, zinc acetate, which was used as the zinc source, was added in the reaction solution after preheating the reaction solution and the pH of the reaction solution decreased with increasing the concentration of zinc acetate. The films prepared after preheating and pH control had larger zinc component and higher optical band gap. The crystal structures of Cd$_{1-x}$ Zn$_{x}$S films was a wurtzite type with a preferential orientation of the (002) plane and the lattice constants of the films changed from the value for CdS to those for ZnS with increasing the mole ratio of the zinc acetate. The minimum lattice mismatch between Cd$_{1-x}$ Zn$_{x}$S and CdTe were 2.7% at the mole ratio of (ZnAc$_2$)/(CdAc$_2$+ZnAc$_2$)=0.4. As the more zinc substituted for Cd in the films, the optical transmittance improved, while the absorption edge shifted toward a shorterwavelength. the photoconductivity of the films was higher than the dark conductivity, while the ratio of those increased with increasing the mole ratio of zinc acetate. acetate.

• Journal of Energy Engineering
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• v.5 no.1
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• pp.50-55
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• 1996

A numerical simulation on a primary calcinator of porcelain was performed with using Fluent to calculate the heat efficiency by studying velocity vector and temperature profile according to variables such as the location of outlet and porcelain. Control-Volume based Finite Difference Method and Up-wind scheme are used for discretization of differential equation. SIMPLEC Algorithm and standard k-$\varepsilon$ turbulent model are selected to resolve the pressure-velocity coupling and the turbulent. The result of simulation showed that the whole velocity vector field in a calcinator was varied greatly according to the location of outlet. But the whole temperature profile at each zone was still high regardless of the location of outlet because of the radiation. But the temperature of a case with a outlet at sidepart of preheating or cooling zone was little high compared to the case with a outlet on the top of preheating zone. The velocity vector field and temperature profile in a calcinator were almost not affected by the location of porcelain, but the temperature inside a porcelain was much affected according to the place where it was located. The heat efficiency in a calcinator was 44.6% and the gas temperature in the outlet was about 1000 K.