• Korean Journal of Food Science and Technology
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• v.3 no.3
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• pp.178-184
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• 1971

Samples of refined soybean oil were irradiated with lights from a 20-watt incandescent tungsten lamp, a 20-watt fluorescent daylight type lamp, a 20-watt low-pressure mercury vapor germicidal lamp, and direct sunlight for an experimental period of 147 days. Some samples were stored in a dark room throughout the period as a control. The peroxide values of all samples were measured every week. The induction period of the samples was arbitrarily taken as the time required for the samples to reach a peroxide value of 15. The induction period of the control was estimated at 198 days. Those of the samples irradiated with the incandescent light, the fluorescent light, the ultraviolet light, and the sunlight were estimated at 196, 119, 52 and 6 days, respectively. The sunlight showed by far the strongest prooxidant activity whereas the incandescent light showed the weakest but distinct prooxidant activity. The small temperature differences observed among the various samples throughout the experimental period did not seem to affect the oxidation rates of the irradiated samples in any significant way.

• Korean Journal of Medicinal Crop Science
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• v.1 no.2
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• pp.137-157
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• 1993

This study was carried out to investigate the optimal condition for multiple propagation through leaf tissue culture and to apply anther culture techniques to Pulsatilla koreana Nakai breeding. Leaf and anther of Pulsatilla koreana Nakai were cultured on MS, MT, LS and $B_5$ media supplemented with several growth regulators and nitrogen sources under various conditions. For callus induction and differentiation from the Pulsatilla koreana leaf segments were more effective in the combination of zeatin and auxin than auxin alone. The color of the callus was green when treated with IBA alone. Shoot differentiation was more effective when treated with zeatin than auxin alone, especially the best hormoal combination for shoot differentiation was zeatin 1.0mg/l +NAA 0.1mg/l, while 2,4-D inhibited shoot differentiation. The appeared rate of S pollen was 35% in vivo, while that of S pollen by low temperature$(4^{\circ}C)$ pretreatment for 4 days was increased by 53% and the optimum culture time for callus induction from anther was uni-nucleate stage. $B_5$ basal medium supplemented with NAA 0.5mg/l and zeatin 1 mg/l was the most effective on callus formation and the best results of plant regeneration were obtained from combination of NAA 0.5mg/l and zeatin 0.5mg/l in anther culture. $NH_{4}NO_3$ as more effectives as the nitrogen source than $KNO_3$ and the combination with zeatin 2.0mg /L was the best effective. The best combination for plant regeneration in callus induced from anther was $NH_{4}NO_3$ 1650mg/l + $KNO_3$ 3800mg/l + zeatin 2.0mg/l. Ploidy level of anther-derived plants appeared 28% haploid, 47% diploid and the others were triploid, tetraploid and mixploid. In compare with E.S.T, M.D.H and P.X banding patterns were distinguished among callus, haploid and diploid plants in electrophoresis.

• Journal of Life Science
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• v.21 no.1
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• pp.119-126
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• 2011

There is a growing recognition of the significance of $H_2S$ as a biological signaling molecule involved in vascular and nervous system functions. In mammals, two enzymes in the transsulfuration pathway, cystathionine ${\beta}$-synthase (CBS) and cystathionine ${\gamma}$-lyase (CGL), are believed to be chiefly responsible for $H_2S$ biogenesis. Genetic inborn error of CGL leads to human genetic disease, cystathioninuria, by accumulating cystathionine in the body. This disease is secondarily associated with a wide range of diseases including diabetes insipidus and Down's syndrome. Although the human CGL (hCGL) overexpression is essential for the investigation of its function, structure, reaction specificity, substrate specificity, and protein-protein interactions, there is no clear report concerning optimum overexpression conditions. In this study, we report a detailed analysis of the overexpression conditions of the hCGL using a bacterial system. Maximum overexpression was obtained in conditions of low culture temperature after inducer addition, performing low aeration during overexpression, and using a low concentration inducer (0.1 mM, IPTG) for induction. Expressed hCGL was purified by His-tag affinity column chromatography and confirmed by Western blot using hCGL antibody and enzyme activity analysis. We also report that the His tag with TEV site attached protein exhibits 76% activity for ${\alpha}-{\gamma}$ elimination reaction with L-cystathionine and 88% for ${\alpha}-{\beta}$ elimination reaction with L-cysteine compared to those of wild type hCGL, respectively. His tag with TEV site attached protein also exhibits a 420 nm absorption maximum, which is attributed to the binding cofactor, pyridoxal 5'-phosphate (PLP).

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.37-49
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• 1998

The specimens used were Ag-25 Pd-15 Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age- hardening characteristics of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing. X-ray diffraction and electron microscope observations, electrical resistance, ergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, i.e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the $L1_0$ type face-centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affected by the Cu concentration. In stage II, decomposition of the ${\alpha}$ solid solution to a PdCu ordered phase($L1_0$ type) and an Ag-rich ${\alpha}2$ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was conclued that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipetation procedure was ${\alpha}{\to}{\alpha}+{\alpha}_2+PdCu {\to}{\alpha}_1+{\alpha}_2+PdCu$ at Pd/Cu = 1.7 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.21-35
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• 1997

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy is cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-20Pd-20Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electic furace and centrifugal casting machine in Ar atmoshpere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age-hardening characteristics of the small Au-containing Ag-pPd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, emergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, I. e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the Llo type face centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affedted by the Cu concentration. In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase(L1o type) and an Agrich ${\alpha}2$ phase occurred and a discontiunous precipitation occurred at the grain boundary. Form the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}\to{\alpha}+{\alpha}2+PdCu\to{\alpha}1+{\alpha}2+PdCu$ at Pd/Cu = 1 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.191-204
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• 1994

Due to its topographic complexities and various climatical condition, Korea exhibits diverse forest types. Dominant tree species in this zone are Quercus spp., Betula spp., Zelkova spp., Fraxinus spp., Pinus densiflora, Pinus koraiensis, and Pinus thunbergii ete. Genetic conservation in forest species in Korea there are three ways ; one is in situ, other is ex situ and third is in-facility conservation. In situ conservation include that are the present status of conservation of rare and endangered flora and ecosystem, the reserved forest, the national and provincial park, and the gene pool of natural forests. Ex situ conservation means to be established the new forest from in situ forest stands, progeny and provenance test populations, seed orchard and clone banks, and gene conservation in-facility. As a tool for low temperature storage, several aspects on in vitro system were studied ; (1) establishment of in vitro cultures from juvenile and/or rejuvenated tissues, (2) induction of multiple shoots from the individual micropropagules, (3) elongation of the proliferated shoots. Studies on cold storage for short-and long-term maintenance of in vitro cultures under $4^{\circ}C$ in the refrigerator were conducted. For the cryopreservation at $-196^{\circ}C$, various factors affecting survivability of the plant materials are being examined. The necessity of gene conservation of forest trees is enlarged not only to increase the adaptability for various environments but also to gain the breeding materials in the future. For effective gene conservation of forest trees, I would like to suggest followings ; 1. Forest stands reserved for other than the gene conservation purposes such as national parks should be investigated by botanical and gene-ecological studies for selecting bio-diversity and gene conservation stands. 2. Reserved forest for gene pool should be extented both economically important tree spp. and non-economical species. 3. Reserved forest for progeny test and clone bank should be systematically investigated for the use of Ex situ forest gene conservation. 4. We have to find out a new methodology of genetic analysis determining the proper and effective size of subpopulation for in situ gene conservation. 5. We should develop a new tree breeding systems for successful gene conservation and utilization of the genetic resources. 6. New method of in-facility gene conservation using advanced genetic engineering should be developed to save time and economic resources. 7. For the conservation of species with short-life span of seed or shortage of knowledge of seed physiology, tissue culture techniques will be played a great role for gene conservation of those species. 8. It is are very useful conservation not only of genes but of genotypes which were selected already by breeding program. 9. Institutional and administrative arrangements including legistlation must be necessarily taken for gene conservation of forest trees. 10. It is national problems for conservation of forest resources which have been rapidly destroyed because of degenerating environmental condition and of inexperienced management system of bio-diversity and gene conservation. 11. In order to international cooperation for exchanging data of bio-diversity and gene conservation, we should connect to international net works as soon as possible.