• Journal of Powder Materials
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• v.17 no.4
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• pp.312-318
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• 2010

High speed steels (HSS) were used as cutting tools and wear parts, because of high strength, wear resistance, and hardness together with an appreciable toughness and fatigue resistance. Conventional manufacturing process for production of components with HSS was used by casting. The powder metallurgy techniques were currently developed due to second phase segregation of conventional process. The powder injection molding method (PIM) was received attention owing to shape without additional processes. The experimental specimens were manufactured with T42 HSS powders (59 vol%) and polymer (41 vol%). The metal powders were prealloyed water-atomised T42 HSS. The green parts were solvent debinded in normal n-Hexane at $60^{\circ}C$ for 24 hours and thermal debinded at $N_2-H_2$ mixed gas atmosphere for 14 hours. Specimens were sintered in $N_2$, $H_2$ gas atmosphere and vacuum condition between 1200 and $1320^{\circ}C$. In result, polymer degradation temperatures about optimum conditions were found at $250^{\circ}C$ and $480^{\circ}C$. After sintering at $N_2$ gas atmosphere, maximum hardness of 310Hv was observed at $1280^{\circ}C$. Fine and well dispersed carbide were observed at this condition. But relative density was under 90%. When sintering at $H_2$ gas atmosphere, relative density was observed to 94.5% at $1200^{\circ}C$. However, the low hardness was obtained due to decarbonization by hydrogen. In case of sintering at the vacuum of $10^{-5}$ torr at temperature of $1240^{\circ}C$, full density and 550Hv hardness were obtained without precipitation of MC and $M_6C$ in grain boundary.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.132-139
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• 2005

The major obstacle in the popularization of Chungkookjang is the short shelf-life of $2{\sim}3$ months and some problems concerning storage including the growth of molds even in the products even within shelf-life. To solve these problems we conducted a research to improve its storage by using the vacuumed packaging and sanitary method through seed culture, innoculation and sterilization. For the optimization of storage time, temperature and sterilization temperature, we measured viable cell numbers of bacteria and fungi, amount of gas outbreak and contents of amino type nitrogen and monitored these experimental results by response surface methodology of SAS program, so that we could observe the quality changes of Chungkookjang during shelf-life. Especially fungi, which are the biggest troublemaker in Chungkookjang shelf-life, couldn't be detected from the generally and vacuum-packed samples; also, viable cell numbers were highly influenced by sterilization temperature and in vacuum-packed samples. In the case of vacuum-packed samples, amount of gas outbreak was highly influenced by sterilization temperature of its storage conditions and it was higher in generally packed samples as compared to vacuum-packed samples even at any storage conditions. The changes of pH in generally and vacuum-packed samples were highly influenced by the storage temperature. As the temperatures of storage and sterilization were higher and the storage time was longer, so the amount of gas outbreak was accordingly lower. These results showed that amino type nitrogen contents in generally and vacuum-packed samples were systematically influenced by the temperature, storage time and sterilization temperature. Also the result showed that the change of amino type nitrogen contents during storage was less in vacuum-packed samples than in general ones. Based on the above results, we can produce Chungkookjang products with extended shelf-life of as far as 6 months without any quality change using sanitary manufacturing method, vacuumed packaging condition, sterilization in $70^{\circ}C$ for 60 minutes and storage under $10^{\circ}C$ during shelf-life. According to this research, we have the possibility to greatly increase the goods value of Chungkookjang by developing the manufacture processing and packaging.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.99-101
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• 2008

At 21st century, material development concepts were changed to fulfill the environmental friendly demands. This study is to study the effect of pressurized nitrogen gas and manganese in high nitrogen austenitic stainless steel(HNS) in which N and Mn elements substitute the nickel element. 100kg HNS ingots were made by Pressurized Vacuum Induction Melting(P-VIM) and were forged according to free forging process. As forged HNS were hot and cold rolled by pilot scale rolling machine. Depending on the rolling condition, the mechanical properties of HNS were changed. The roll thrust and sheet folding showed asymmetry condition between work and drive side during cold and hot rolling. The purpose of this study are to improve workability the hot and cold rolling machine and to set the conditions for establishing the rolling process.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.174-179
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• 2003

Thin copper films were grown by electrodeposition on copper seed layers which were grown by sputtering of an ultra-pure copper target on tantalum nitride-coated silicon wafers and subsequently, cleaned in ECR plasma. The copper films were then subjected to ⅰ) vacuum annealing, ⅱ) rapid thermal annealing (RTA) and ⅲ) rapid thermal nitriding (RTN) at various temperatures over different periods of time. XRD, SEM, AFM and resistivity measurements were done to ascertain the optimum heat treatment condition for obtaining film with minimum resistivity, predominantly (111)-oriented and smoother surface morphology. The as-deposited film has a resistivity of ∼6.3 $\mu$$\Omega$-cm and a relatively small intensity ratio of (111) and (200) peaks. With heat treatment, the resistivity decreases and the (111) peak becomes dominant, along with improved smoothness of the copper film. The optimum condition (with a resistivity of 1.98 $\mu$$\Omega$-cm) is suggested as the rapid thermal nitriding at 400oC for 120 sec.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.106-112
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• 2012

This study was carried out to investigate the effect of bonding temperature and holding time on microstructure and mechanical properties in brazing joints of Ni-base superalloy using MBF-30 (Ni-4.5Si-3.2B [wt.%]). The heating rate was $20^{\circ}C$/min to the bonding temperatures $1050^{\circ}C$, $1070^{\circ}C$, $1090^{\circ}C$ under high vacuum condition. The holding times were 100s, 400s, 900s and 1600s. $Ni_3B$ phases and proeutectic Ni were observed in the interlayer of Ni-201. Then, Ni3B and Ni3Si were found in the middle region of brazing joint. Cr-boride phase appeared in the interlayer of Inconel-625. Tensile strength and elongation were decreased at $1050^{\circ}C$-1600s, $1070^{\circ}C$-900s and $1090^{\circ}C$-400s. After observation the fracture specimens, There was Ni3B which is very brittle phase in the grain boundary of Ni201.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.35-38
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• 1995

Indium Tin Oxide(ITO) thin film is transparent to visible ray and conductive in electricity. It is seen that the samples made by the sputtering process have high transmission rate to visible ray and high adhesion , but the planar type magnetron sputtering process with is very well known in industrial region have a defect of partial erosion on the surface of target and a high loss of target and also since the substrate is positioned in plasma, the damage on thin film surface is caused by the reaction with plasma. In cylindrical magnetron sputtering system. it is known that the loss of target is little , the damage of thin film is very little and the adhesion of thin film with substrate is strong. In this study, we have made ITO thin film in the cylindrical DC magnetron system with the variable of substrate temperature , magnetic field, vacuum condution and the applied voltage. The general temperature for formation on ITO is asked at 350 $^{\circ}C$~400$^{\circ}C$ but we have made ITO is low temperature(80-150$^{\circ}C$) By studing electrical and optical properties of ITO thin fims made by varing several condition, we have searched the optimal condition for formation in the best ITO in low temperature.

• Journal of the Korean Home Economics Association
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• v.41 no.2
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• pp.107-121
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• 2003

This study was discussed the dyeing of wool and nylon fabrics with Chinese Scholar Tree extract. The extracts of Chinese Scholar Tree was prepared in the condition of heating at $95{\pm}5C$, for 1 hour and cooling to 40C. And then the extracts of color matter treate with vacuum concentration at $60{\pm}2^{\circ}C$, 30mmHg and dried with spray dryer. The dyeing of wool and nylon fabric in this experiment was also employed the mordant dyeing method such as pre-mordant, post-mordant and simultaneous mordant method. The mordanting agents used in this study were as followings ; aluminium potassium sulfate, copper(II) acetate monohydrate, chromium potassium sulfate$.$$7H_2O$, Tin(II) chloride dihydrate, iron(II)sulfate $7H_2O$. For an evaluation of the dyeing property of the mordanting agents, the pre-mordant method, the repeat dyeing and the fastness of the light, dry cleaning, washing and rubbing measured respectively. From the results of the dye absorption, the optimum dyeing condition of the wool and nylon fabrics with Chinese Scholar Tree extract is at 80C dyeing temperature for 60 minutes. The optimum concentration of mordanting agent is Al, Cr, Sn 1%, Fe, Cu 2% solution. In general, the fastness property of the dyed wool and nylon fabrics had a comparatively high grade.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.149-155
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• 2011

We investigated tribological characteristics of diamond-like carbon (DLC) in a condition with carbon nanotube (CNT) content of 1wt% in aqueous solution. Si-DLC films were deposited by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process on Al6061 aluminum alloy. In this study, the deposition of DLC films was carried out in vacuum with a chamber pressure of 10-5 to 10-3 Torr achieved by mechanical pump followed by turbo molecular pump. The surface adsorbed oxygen on the Aluminum substrates was removed by passing Ar gas for 10 minutes. The RF power was maintained at 500W throughout the experiment. A buffer layer of HMDSO was deposited on the substrate to improve the adhesion of DLC coating. At this point CH4 gas was introduced in the chamber using gas flow controller and DLC coating was deposited on the buffer layer along with HMDSO for 50 min. The thickness of 1 ${\mu}m$ was obtained for DLC films on aluminum substrates The tribological properties of as synthesized DLC films were analyzed by wear test in the presence of dry air, water and lubricant such as CNT ink.

• Journal of Technologic Dentistry
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• v.23 no.2
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• pp.203-210
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• 2002

This test is to conduct applied research the reaction area of the Ti-cast metal body which is made use of Dental Phosphate-silica alumina bonded investment material selling at a market, and the cooling method is how to effect on the acicular. The experimentation is as followings, 1. Experimental specimens After invest with Dental Phosphate-silica alumina bonded investment material, the $10{\times}10{\times}1.0mm^3$ wax pattern was casted by Dental high vacuum argon centrifugal casting machine. 2. Test We can analyze SEM/EDS, XRD utilize the fractography(an optical microscope). 3. Conclusion The pure cast metal body constituted of reaction products layer, stability layer and contamination layer. This pure cast have no connection with the cooling condition. The pure Titanium shows difference in a component distribution according to the cooling condition. Through this experimentation we can establish that acicular in the pure Ti-cast metal is consist of Hexagonal structure a=2.9505$\AA$, c=4.6826$\AA$.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.754-758
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• 2002

In order to reach the high quality of organic thin films such as high mobility for device applications, it is strongly desirable to study the growth properties of pentacene film as a function of evaporation condition. Here, we report the structure and morphology of thermal evaporated pentacene thin film by AFM, SEM, and XRD as a function of the evaporation rate and substrate temperature. These results play a key role in determining the electric performance of organic thin film transistor devices.