Mechanical alloying using high-energy ball mill and subsequent spark plasma sintering (SPS) process was applied to Al-Fe-Cr and Al-Fe-Mo powder mixture to investigate effects of Cr and Mo addition on thermal stability of Al-Fe, and thereby to enhance its thermal stability up to . Various analytical techniques including micro-Vickers hardness test, SEM, TEM, X-ray diffractometry and corrosion test were carried out. It was found that addition of Cr and Mo to Al-Fe system played a role of grain growth inhibitor of matrix Al and some precipitates such as during SPS and subsequent heat treatment. The inhibition of grain growth resulted in increased Vickers hardness and thermal stability up to comparing to those of Al-Fe alloy system.

An aluminum powder compact consolidated by a powder-in sheath rolling (PSR) method was severely deformed by accumulative roll-bonding (ARB) process. The ARB process was performed up to 8 cycles at ambient temperature without lubrication. Optical microscope and transmission electron microscope observations revealed that microstructure of the ARB-processed Al powder compact is inhomogeneous in the thickness direction. The ultra-fine subgrains often reported in the ARB-processed bulky materials were also developed near surface of the Al powder compacts in this study. Tensile strength of the ARB-processed Al powder compact increased at the 1st cycle, but from the 2nd cycle it rather decreased slightly.

Dense -20vol.%SiC composite was synthesized by high-frequency induction-heated combustion synthesis(HFIHCS) method within 2 minutes in one step from elemental powder mixture of W, Si and C. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. Highly dense -20vol.%SiC with relative density of up to 97% was produced under simultaneous application of 60MPa pressure and the induced current. The average grain size of was about 5.2. The hardness and fracture toughness values obtained were 1700kg/ and , respectively.

꼬막, 참굴, 바윗굴 및 가리비 등 폐기되는 몇 종의 패각류를 이용하여 칼슘 보강용 식품 첨가제의 원료로써 사용 할 수 있는 고순도의 탄산칼슘을 제조하고자 하였다. 꼬막 패각을 900℃에서 5시간 회화한 회화분의 칼슘 함량이 64.9%로 가장 높게 나타났으며, 가리비 62.5%, 참굴 62.4%, 바윗굴 61.5% 순이었다. 백색도는 가리비 패각 회화분의 경우 81.6-85.8로서 패각류 중 가장 높았다. 꼬막 패각 회화분(Ca 39.92%)에 ammonium chloride process(ACP)와 ammonium nitrate process(ANP)법을 적용하여 제조한 CaCO₃의 Ca 함량은 40.03-40.04%로 높아졌고, ANP법에 의해 제조한 pH조정 시료의 경우가 40.04%로서 가장 높았으며, 이 방법들에 의해 불순물이 거의 대부분 제거되는 것으로 나타났다. ACP법과 ANP법에 의해 제조한 CaCO₃의 백색도는 101.0-101.5로 매우 우수하였으며, 칼슘보강용 식품첨가제로서 사용될 가능성이 충분하다고 판단된다.

The preparation of CaSO4 nanoparticle by vesicles formed spontaneously in cationic OTAC and anionic ADS mixed surfactant solution whose ratio is 0.3/0.7 is investigated. Added electrolytes for preparing nanoparticles reduce vesicle size about 200-300 nm comparing with that of pure vesicle whose size is 700-800 nm by DLS. The core of vesicles has 200 nm size and acts as nanoreactors which same size of monodisperse CaSO4 nanopaticles are formed. Although CaSO4 particles are formed at the outer of vesicles, they are very large and amorphous. The formed particles are identified with XRD analysis after separation due to coinciding with CaSO4 particles.

Highly crosslinked micron-size monodispersed PMMA/PDVB and PS/PDVB particles were prepared using seeded multi-stage emulsion polymerization. PMMA and PS seed particles were synthesized by seeded multi-stage emulsion polymerization and soap-free emulsion polymerization. Then PMMA/PDVB and PS/PDVB particles were obtained using semi-batch type emulsion polymerized using divinyl benzene as a cross-linkable monomer in the presence of seed particles. PMMA particles with size of ca. 730 nm and polydispersity of 1.03 were successfully prepared in this experiment. PS particles with size of ca. 1.5 μm and polydispersity of 1.01 were prepared in this experiment. Highly crosslinked PS/PDVB particles with size of ca. 1.3 μm and polydispersity of 1.00 were obtained.

Reaction conditions and catalysts were investigated for direct CF3I synthesis. Optimum reaction temperature was determined by pyrolysis of CF3H and catalytic reactions. Reactions with changing oxygen concentration were performed. As a result, yield of CF3I increased with decreasing oxygen concentration. Catalytic activity was changed with the weight ratio of the used metal salts. This result was stemmed from the change in the pore size of activated carbon by the metal salts. The optimum reaction conditions were: 600℃, space velocity of 45hr-1, and with 7wt% KF/AC catalyst.

본 연구에서는 ionomer와 여러 가지의 유기화물로 처리된 MMT type의 clay를 이용하여 ionomer-clay 하이브리드 막을 용융삽입법으로 제조하였다. Twin extruder를 사용하여 clay를 ionomer에 분산시켰으며, 제조된 ionomer-clay 하이브리드에서 clay의 특성피크가 완전히 박리되거나 이동하는 XRD 결과로부터 clay의 층간거리가 넓어지는 고분자의 clay 층간삽입을 확인하였다. Clay의 종류에 따라서 제조된 ionomer-clay 하이브리드 막의 가스투과도, 기계적 물성 및 열적 성질을 측정하였다. ionomer-clay 하이브리드 막은 clay 자체의 도입과 층간거리의 확대로 기체분자의 tortuosity를 증가시켜서 가스투과도를 저하시키는 것을 확인하였다.

An acid cleaning agent (AACA) for aluminum was prepared by blending of sorbitol, n-octanoic acid, MJU-100A, Tetronix T-701, PPA-23, C8-83 and phosphoric acid. With the prepared AACA, degreasing, foam height, etching and derusting tests were carried out. As a result, AACA-4 and AACA-7 showed better cleaning ability than commercial acid cleaning agents.

The injection mold industry has strong relationship with many other industries. In the injection mold industry, the harmonious collaboration of the order-making companies, the mold-making companies, and the molded-parts making companies, which are distantly located, is very important. In this study, a web-based collaboration system is developed for the purpose. It offers the criterion to select appropriate production companies. It also tries to minimize the production cost of the mold design by distributing and evaluating the design information. The developed system is constructed using various recent web-programming tools.

This research considers the problem of scheduling Jobs on unrelated parallel machines with a common due date The objective is to minimize the total absolute deviation of Job completion times about the common due date. This problem is motivated by the fact

What is the most important in articles of food is hygienic safety. Because food Is the most common thing in our everyday life, however, the importance of its hygienic safety and other many problems caused by food may be easily neglected. What is more, food is can be dangerous as much as it is directly related to human life and accidents from the same cause may have different effects on the victims according to physical and environmental differences of individuals. Thus PL action for food requires more thorough prevention and measure. Korea has been enforcing 'the Product Liability Act' since the 1<SUP>1st</SUP> of July 2002. Product Liability (PL) is liability of the manufacturer or the seller of a product to compensate for the death or injury of consumers or the loss of properties caused by the defect of the product. This study surveyed consumers' response to and the effects of the enforcement of the Product Liability Act, investigated how consumers perceived the importance of food safety and the risk of defective food based on PL standards and their experience in damage by food through a questionnaire survey, and analyzed collected data through empirical analyses (reliability analysis, factorial analysis, regression analysis and ANOVA t-test) using SPSS 10.0. Based on the results of analysis, the researcher proposed strategies for coping with the Product Liability Act in the food industry

Nano sized FeAl intermetallic particles were successfully synthesized by plasma arc discharge pro-cess. The synthesized powders shouted core-shell structures with the particle size of 10-20 nm. The core was metallic FeAl and shell was composed of amorphous Because of the difference of Fe and Al vapor pressure during synthesis, the Al contents in the nanoparticles depended on the Al contents of master alloy.

Fe(C) nanocapsules were prepared by the chemical vapor condensation(CVC) process using the pyrolysis of iron Their characterizations were studied by means of X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The long-chained Fe(C) nanocapsules hav-ing the mean size of under 70 nm could be obtained below in different gas flow rates. The particle size of the powders was increased with increasing decomposition temperature, but it was decreased with increasing CO gas flow rate. The Fe powders produced at consisted of three layers of phases, but it had two phase core-shell structure which consited of phase of core and graphite of shell at