To precisely assemble the fuel test rod, an orbital TIG welding system was designed and developed to accurately conduct orbital TIG welding for the nuclear fuel test rod. Using this system, a welding process needs to confirm the welding properties for orbital TIG welding. Therefore, preliminary weld tests were performed on the cladding tubes under various conditions, and the results show that the width and depth of HAZ of the cladding specimen welded using identical power during an orbital TIG welding cycle was continuously increased from a welded start-point to a welded end-point because of heat accumulation. The performance tests were conducted under the welding conditions considered through preliminary welding tests, and the properties of the specimens were conformed through surface and microstructure analyses.

To conduct a nuclear fuel irradiation test, the inside of the nuclear fuel rod must be assembled along with the test fuel, several different parts, and sensors, and then filled with high-pressure and high-purityhelium gas. Therefore, it is necessary to develop helium gas filling techniques that can achieve exact TIG (Tungsten Inert Gas) spot welding at a pin-hole of the nuclear fuel rod to fill helium gas into the nuclear fuel test rod. However, previous apparatuses do not have repeatability for TIG spot welding as they lack an electrode position control jig to exactly fix a TIG electrode in a high-pressure chamber, and they consume a large amount of helium gas. Therefore, a TIG spot welding apparatus was developed to easily and accurately conduct TIG spot welding and significantly reduce the gas consumption. In addition, the optimum welding conditions of this welding apparatus were established through various weld tests.

Fiber laser welding has been developed for precise welding of small and complicate components assembled on the nuclear fuel irradiation test rig. In this research, laser welding characteristics of STS316L, the main material of nuclear fuel test rig, have been studied. Several welding experiments were carried out in lap welding of the tube and the end cap made of STS316L. Process variables such as non-focal length, shield gas, laser frequency and power are optimized and compared with the results of Zircaloy-4.

To evaluate antimicrobial activities of chongkukjang slime fermented by different strains, growth characteristics were compared using various standard microorganisms with addition of chongkukjang slime. Chongkukgang slime was prepared by fermenting cooked soybean after inoculating with Bacillus circulars K-1, Bacillus spp N-1 and Bacillus subtilis CH-1, respectively. Significant antimicrobial activity was observed by chongkukjang slime on gram positive bacteria (Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Micrococcus luteus), gram negative bacteria(Escherichia coli O157:H7, Salmonella Typhimurium, Pseudomonas fluorescens), and yeast (Pichia membranaefaciens, Saccharomyces cerevisiae, Candida albicans). In case of B. cereus growth inhibition of 80% was achieved by the addition of chongkukjang slime; on the contrary, to Escherichia coli O157:H7 only 20% inhibition was observed. Slime from Bacillus subtilis CH-1, in parkicular, inhibition of 40% toward bacteria and yeast, whereas slime from Bacillus circulars K-1, Bacillus spp N-1 showed only 20% inhibition.

This research was carried out to improve the utilization of agar by evaluating the effect of agarooligosaccharides on the intestinal microflora. Medium containing 0.2% agarooligosaccharides remarkably enhanced the growth of Bifidobacterium infantis; however, agarooligosaccharides did not influence the growth of Clostridium perJlingens. Agarooligosaccharides affected intestinal microflora to different extent by various pH and NaCl concentration. The growth of B. infantis enhancad over pH 4.5. Within 1 % NaCl concentration, addition of agarooligosaccharides enhanced the growth of B. infantis. In contract, NaCl did not affect the growth of Cl. perflingens at all concentrations tested. Therefore, agarooligosacchariedes improved the benevolent intestinal microflora and depressed to the level of bacteria causing putrefaction and food poisoning.

Agar, one of the most abundant marine products has not been utilized extensively because of low level of processing technology in Korea. This research was carried out to improve the utilization of agar and consequent increase in profit. Antibacterial activity of agarooligosaccharides were evaluated against bacteria causing putrefaction and food poisoning. Addition of 0.4% agarooligosaccharides showed antibacterial activity toward Staphylococcus aureus and Escherichia coli O157:H7; furthermore, autoclave treatment of agarooligosaccharides solution enhanced the antibacterial activity. Agarooligosaccharides showed high stability against the pH change. Addition of amino acid(alanine, lysine, glycine, phenylalanine) in agarooligosaccharides solution enhanced antibacterial activity in E. coli O157:H7, Streptococcus mutans and Staphylococcus aureus.

식품의 항균물질 분리에 있어 여러 가지 방법이 있지만 오차와 손실이 많아 실용화 하기에는 많은 문제점이 있다. 현재 일반적인 분리법으로 유기용매분획법, 크로마토그래피 등이 있으나, 많은 시간과 노력을 필요로 하며 시료에 따라 항균활성이 소실되는 경우가 많다. 본 연구는 전편의 '부추의 미생물학적 항균활성 특성과 가공식품에의 응용'에 이어 부추의 항균활성 물질을 효과적으로 분리하기 위한 방법을 정립하고 항균활성 물질을 확인하였다. 부추의 항균활성 물질 분리를 위하여 ultrafiltration, liquid-liquid extraction, TLC, HPLC 순으로 정제하였다. Ultrafiltration 결과 항균물질은 분자량 5,000 dalton 이하의 저분자 물질이었고, TLC로 분리된 8개의 spot중 대조군에 비하여 높은 항균활성을 나타내는 1개의 spot을 추출하여, HPLC로 유효 peak 2개를 얻었고 각 peak성분을 GC/MS로 확인한 결과 cis-propenyl methyl disulfide, 5-methyl methylthiosulphonate, dimethyl disulfide등의 황화합물로 구성된 복합물질로 확인되었다.

Antimicrobial activity of Korean leek was effective on Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, E. coli O157:H7, Pseudomonas fluorescens, Pichia membranaefaciens. Extract from raw Korean leek and that from frozen one showed antimicrobial activity; in contrast, extract stored frozen condition or extract from blanched one lost antimicrobial activity. Filtration, centrifugation, and vacuum concentration did not affect antimicrobial activity of the leek, nor did the changes in storage pHs. Addition of ground leek to soy milk, soy curd, and broth for cold noodle resulted in the prolonged shelf life by significantly reducing the number of viable cells.

풋고추의 저장성 향상을 위한 저장전 열처리 조건을 구명하기 위하여 풋고추를 50, 55, 60, 의 온수에 각각 10초 침지하여 열처리를 하였다 에서 10초 열처리한 경우는 열처리 직후 과육표면에 가열장해 현상이 나타났다. 온수에서 침지한 풋고추를 1의 저장고에서 4주 동안 저장하면서 관능적 품질, 화학적 품질과 미생물학적 품질을 측정하였다. 표면 색도 중 L 값은 저장 중 조금씩 감소하는 경향을 보였으며, a 값과 b 값은 저장 3주까지는 거의