• Proceedings of the KWS Conference
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• 2006.10a
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• pp.199-201
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• 2006

The wetting balance test was carried out to compare the wettability of Sn-Xwt%Cu($0{\sim}3$wt%) solders. And, IMCs which were formed at interface between solders and substrates were investigated by using XRD(x-ray diffractometer), SEM(scanning electron microscope) and EDS(energy dispersive spectroscope). The value of ${\gamma}_[fl}$ and(${\gamma}_{fs}-{\gamma}_{ls}$) had a tendency to increase with increasing wetting temperature. The activation energy that was calculated between the bare Cu substrate and flux was increased in the following order Sn-0.7wt%Cu(68.42 kJ/mol);Sn-3.0wt%Cu(72.66 kJ/mol);100wt%Sn solder(94.53 kJ/mol).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.429-433
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• 2006

High Temperature deformation behavior of newly developed beta-gamma TiAl alloy was investigated in this study. The optimum processing condition was investigated with the aid of Dynamic Materials Model (DMM). Processing maps representing the efficiency of power dissipation for microstructural evolution and instability were constructed utilizing the results of hot compression test at temperatures ranging from $1000^{\circ}C$ to $1200^{\circ}C$ and strain rate ranging from $10^{-4}/s$ to $10^2/s$. The Artificial Neural Network (ANN) simulation was adopted to consider the deformation heating. With the help of processing map and microstructural analysis, the optimum processing condition was presented and the role of $\beta$ phase was also discussed in this study.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1092-1098
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• 1999

Gamma irradiation was applied to pork for improving its hygienic quality and evaluating its possible genotoxicity. The effective dose of irradiation was 3 kGy in pork for the sterilization of all contaminated microorganisms tested. After 8 weeks of storage at 5oC, no growth of microorganisms except for psychrophile and total aerobic bacteria was observed in the more than 3 kGy irradiated pork. The genotoxicity of high dose irradiated pork(30 kGy) was evaluated by Salmonella typhimurium reversion assay, chromosomal aberration test and in vivo micronucleus assay. The results were negative in the bacterial reversion assay with S. typhimurium TA98, TA100, TA1535, TA1537. In chromosomal aberration tests with CHL cells and in vivo mouse micronucleus assay, no significant difference in the incidences of chromosomal aberration and micronuclei was seen between nonirradiated and 30 kGy irradiated porks. These results indicate that 30 kGy irradiated pork did not show any genotoxic effects under these experimental conditions.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1570-1574
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• 2008

Various mechanical test were conducted on conventional and crosslinked ultra-high molecular weight polyethylene(UHMWPE) all prepared from the same lot of medical grade GUR 1050 for artificial joint. The conventional materials were not irradiated and treated by heating. The cosslinked materials were irradiated with $25kGy{\sim}200kGy$ by gamma-ray andthen annealed or remelted. Gamma-ray irradiation and heat treatment process were found to significantly impact the crystallinity, and hence the mechanical behavior, of the highly crosslinked UHMWPE. The radiation dose and heating conditions were key predictors of the uniaxial yielding, plastic flow, and failure properties of conventional and highly crosslinked UHMWPE. The correlation model from experiments would be the basic information to enhance the were resistance of artificial joint liner.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.202-202
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• 2000

AC-PDP(Plasma Display Paner)는 기체 방전을 이용한 디스플레이로서 기체에 직접 노출되는 MgO 보호막의 2차전자 방출계수(${\gamma}$는 AC-PDP의 방전특성을 결정짓는 중요한 요소이다. MgO 보호막의 이차전자 방출계수는 AC-PDP에 주입하는 기체의 종류, 결정 방향성과 표면오염상태 등에 영향을 받는다. 본 연구에서는 유리 기판위에 Al 전극을 증착, 에칭후 screen printing으로 유전체를 도포, 소성 한 21inch 규격의 test panel에 MgO 보호막을 E-Beam으로 5000$\AA$ 증착한 후 MgO 보호막을 대기에 노출되는 시간간격을 변수로 하여 대기 열처리 한 MgO보호막의 2차 전자방출계수를 ${\gamma}$-FIB(Focused Ion Beam) 장치를 이용하여 측정하였다. 그리고 대기 노출 간격은 1분, 5분, 20분으로 하여 2차 전자방출계수를 측정하였고, 2차전자방출계수 측정 시 가속전압은 50V에서 200V까지 변화를 주었으며, Ne+을 사용하여 1.2$\times$10-4Torr의 진공도를 유지하며 측정하였다. 또한 각각의 MgO막의 에너지 갭을 광학적 방법을 이용하여 구하였다.

• Korean Journal of Microbiology
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• v.8 no.2
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• pp.65-68
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• 1970

In continuation of the previous work (The New Medical Journal, Vol. 12, No. 3, 111, 1969), the effects on the bactericidal activity against coli form group, on vitamin C content and ascorbate oxidase activity of the purple laver due to the $^{80}Co$ gamma-irradiation were studied. The results obtained are ; 1) After the 0.1m rad./hr. doses treatment of gamma-irradiation for 1 hours to the laver, the coli form group was being remarkably destoryed and after the application for 10 hours the coli form group was completely destroyed. 2) The content of vitamin C was gradually decreased during the gamma-irradiation to the laver. According to the sensory test, no changes in flavor nad color were indicated for 9-10 hours treatment. But, the loss of ascorbic was much than that of dehydroascorbic acid after 10-hour treatment. 3) And also, the ascorbate oxidase activity due to the irradiation waas conspicuously decreased.

• Structural Engineering and Mechanics
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• v.69 no.5
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• pp.527-536
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• 2019

This paper will compare $T3{\gamma}_s$ and MITC3 elements, both these two elements are three-node triangular plate bending elements with three degrees of freedom per node. The formulation of the $T3{\gamma}_s$ and MITC3 elements is rather simple and has already been widely used. This paper will prove that the shear strain formulation of these two elements is identical even though they are obtained from two different methods. A single element is used to test the formulation of shear strain matrices. Numerical tests for circular plate cases compared with the exact solutions and with DKMT element will complete this review to verify the performances and show the convergence of these two elements.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.103-106
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• 2015

The oriental tobacco budworm, Helicoverpa assulta (Lepidoptera: Noctuidae), is classified as a quarantine pest that must be controlled for the exportation of Korean paprika to the USA. We performed a confirmatory test of gamma irradiation against the last-instar larvae and pupae of H. assulta in paprika. Previous, small-scale gamma irradiation at a dose of 100 Gy to the last-instar larvae allowed emergence of adults, though they were abnormal, but 200 Gy prevented adult emergence completely. For pupae, irradiation of 5- to 6-day-old pupae with 300 Gy prevented normal emergence completely. To gather confirmatory data applicable to phytosanitary quarantine regulations, larvae and pupae were placed inside paprika in a box and were irradiated with 200 Gy and 300 Gy, respectively. After irradiation with 200 Gy (measured doses 170-199 Gy) of 2,186 individuals of the last-instar larvae, 10.84% survived, but either formed abnormal pupae (7.57%) or died during the pupal stage (3.27%), resulting in no emergence of normal adults. For pupae, the dose of 300 Gy (measured doses 276-319 Gy) given to 1,200 pupae allowed 10.75% to survive and 9.17% to emerge with deformity. However, 1.58% of irradiated pupae emerged normally, requiring an increased dose for complete prevention of normal emergence. Subsequently, an increased dose of 400 Gy (measured doses 340-402 Gy) to 1,005 pupae allowed 88.35% to emerge, but all emerged with deformity. Thus, irradiation treatment with a minimum dose of 400 Gy will provide quarantine security for all premature H. assulta in exported paprika.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.67-74
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• 2004

A bacterium which grow on phenol as an only carbon and energy source was isolated from the sewage sludge at Nangi municipal wastewater treatment plant in Seoul. This bacterium was found to be a Gram negative rod with high motility, and well grew on 0.05%, 0.1%, and 0.15% of phenol. No matching strain was found from the result of the BBL test. Phylogenetic analysis of the strain by comparison of the 16s-rDNA has revealed that this bacterium has 99% of similarity with Stenotrophomonas maltophilia strain of Xanthomonas group, which belongs t the Gamma (${\gamma}$) subdivision of Proteobacteria. This strain has also shown 98% of similarity with nitrogen fixing bacterium MAGDE3 and Pseudomonas cissicola strain, and 97% of similarity with Stenotrophomonas sp. LMG198 and Xanthomonas cucurbitae.

• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.219-226
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• 1997

Ultralow background gamma-ray measurement system was installed to measure and analyze gamma-rays emitted from environmental and swipe samples. The background reduction techniques applied on this system are the passive shielding to surround the HPGe detector, an active external anticosmic shield to shield cosmic-rays and the nitrogen gas supply to minimize the introduction of ubiquitous radon decay nuclei. The performance test result showed that the system background at energies between 50 keV and 2 MeV is reduced about $10^{-2}$ order and the MDA is so low as to be suitable for the environmental sample analysis. But it is appeared that the neutron produced by cosmic-ray increases the background at low energy region.