• 한국작물학회지
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• 제38권4호
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• pp.366-370
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• 1993

본 연구는 기내에서 두릅의 잎조직배양을 통한 효율적인 종묘대량증식체계를 확립하기 위한 기초연구로서 엽내으로부터 캘루스 유기 및 식물체 재분화를 시도한 결과이다. 1. 유연조직으로부터 캘루스 유기는 1.0mg/1 Thidiazuron 첨가배지에서 70%의 유기율을 보였다. 2. 0.1～0.2mg/1 Dicamba 및 1.0mg/1 Picloram 첨가가 캘루스의 증식에 효과가 있었다. 3. 호르몬 첨가배지에서는 식물체 재분화가 이루어지지 않은 반면 Hormon-free 배지에서 shoot 및 root의 분화가 이루어져 완전한 식물체를 얻었다.

• 대한기계학회논문집A
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• 제24권4호
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• pp.1001-1006
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• 2000

To verify the existing theory, non-propagating crack(NPC) does not exist in Ti which fulfills the good conditions for being of NPC, NPC detection in Ti was tried out. Also, the conception of fatigue limit in Ti and a main cause for NPC being were inquired. NPC was detected in both sharp notch root ( $\rho$=0.02mm) and micro pit (diameter = 0.25mm) which held fast to the end under stressing of fatigue limit. Therefore, the existing theory was identified as mistake. But, NPC can not be detected in smooth specimen. This fact would be due to the presumption that NPC is very small or crack does not initiate in smooth specimen. Anyway, the fatigue limit of Ti does not correspond to critical stress of crack initiation but correspond to critical stress of NPC growth. Measurement on the COD of NPC in Ti showed that the crack tip was closed even under the peak stress level at fatigue limit. But, after stress relieving annealing crack tip was opened. Consequently, compressive residual stress which is induced around the crack tip is considered to be the factor causing the NPC being.

• 한국작물학회지
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• 제47권5호
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• pp.352-355
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• 2002

Mature embryos of five oat genotypes were cultured to develop an efficient method of callus induction and plant regeneration. Murashige and Skoog(MS) and N6 media supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin were used for callus induction. Percentage of callus induction showed significant among the combinations of plant growth regulators. Callus induction showed high efficiency in medium containing 3 mg/$\ell$ of 2,4-D. The high frequency of callus induction was obtained in Gwiri37. For plant regeneration, calli induced from mature embryos were transferred onto MS and N6 media supplemented with combinations of 6-benzyladenine (BA) and naphthaleneacetic acid (NAA) for 5 weeks. Percentage of plant regeneration showed high in MS medium containing 0.2 mg/$\ell$ of NAA and 1 mg/$\ell$ of BA. The callus initiation medium affected the subsequent plant regeneration. Treatment with 3 mg/$\ell$ of 2,4-D, and 3 mg/$\ell$ of 2,4-D and 3 mg/$\ell$ of kinetin in callus induction media showed high frequency for plant regeneration. Plant regeneration frequency among the genotypes showed significant. Especially, Gwiri37 showed high regeneration frequency. Regenerated shoots were treated with 200, 350 and 500 mg/$\ell$ of indole-3-butyric acid (IBA) transferred onto half-strength MS medium without plant growth regulators. Treatment of shoots with IBA induced root formation rapidly.

• 대한조선학회논문집
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• 제43권4호
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• pp.494-503
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• 2006

Inherent damage zone model is presented to explain the fatigue properties near the fatigue limit and the crack growth threshold consistently Inherent damage zone model assumes that the stress at a point which is located at a small distance, $r_0$, an inherent length of the material that represents the size of effective damage zone, from the crack initiation position governs the fatigue characteristics regardless of the geometric configuration of the specimen; smooth specimen, notched specimen or cracked specimens with short and long crack length. A special feature of the paper is using the exact stress distributions of notched and cracked specimens at the strength evaluations. Analytical elastic solutions by Neuber and Westergaard are employed for this purpose Relationship between fatigue limit of smooth specimen and threshold stress of cracked specimen, occurrence condition of non-propagating crack at the root of elliptic notch and circular hole and relationship between stress concentration factor and fatigue notch factor are discussed quantitatively based on the proposed model.

• Journal of Plant Biotechnology
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• 제5권4호
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• pp.239-244
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• 2003

A protocol has been developed for rapid large scale clonal propagation of an aromatic endangered medicinal plant, Hemidesmus indicus R. Br. with the elimination of the problems such as premature leaf fall and callus formation during caulogenesis and rhizogenesis. Multiple shoots were induced from shoot tip and nodal explants on Murashige and Skoog (MS) medium supplemented with 1 mg/L Benzylaminopurine (BAP) and 0.5 mg/L Napthaleneaceticacid (NAA). Addition of 15 mg/L adenine sulphate to the above medium checked leaf abscission completely, reduced the time required for caulogenesis and restored morphogenetic potential after several subcultures. The in vitro grown propagules were rooted in 1/2 MS medium supplemented with 2 mg/L Indolebutyric acid (IBA) +1 mg/L NAA and sucrose 0.7% (w/v). Addition of charcoal at 100 mg/L to the rooting medium quickened root initiation with a complete check on callus formation. The effect of sucrose concentration on both caulogenesis and rhizogenesis was also studied. The resultant plantlets were acclimatized and grown in fields where ninety eight percent of the rooted shoots survived and grew normally. The estimation of the secondary metabolite content in the shoots of the regenerated plant and the mother plant indicated that the concentration of the three secondary metabolites lupeol, vanillin and rutin was similar.

• Journal of Plant Biotechnology
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• 제30권3호
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• pp.257-261
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• 2003

This experiment was carried out to investigate the effects of plant growth regulators on the organogenesis from the tissue culture of Arabidopsis thaliana stem, and the origin of the callus development. When the stem segments were cultured on medium with 2mg/L IAA or NAA, adventitious roots and trichomes were differentiated after 11 days of culture. Callus vigorously formed on medium with 2/L2,4 after 7 days of culture, but adventitious roots and trichomes were not differentiated from callus after 10 days of culture. This results suggesting that picloram is very effective auxin for the callus formation and organogenesis. Callus weakly formed on 0.05mg/L kinetin, and formed on combination of auxins(2mg/L) with 0.05mg/L kinetin. But the effect of combination of auxins and kinetin the callus formation was less than 2,4-D or picloram alone. A histological examination of callus formed on picloram showed that phloram showed that phloem parenchyma cells were divided and enlarged after 2 days of culture. Cortex parenchyma cells were divided and meristematic nodules were developed from these cells after 4 days of culture. Finally, callus formed on outside of cortex and epidermis by division of meristematic nodules after 7 days of culture.

• 공업화학
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• 제4권2호
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• pp.300-307
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• 1993

$Na_2S_2O_4$ 수용액과 $CCl_4$-toluene 용액의 2상에서 유기상에 용해하는 tricaprylmethylammonium chloride 상이동 촉매를 사용하여 methyl methacrylate의 라디칼 중합속도를 측정하여, 액-액 불균일계 접촉계면을 통한 라디칼 중합반응기구를 해석하였다. MMA의 중합속도는 수용액상에 존재하는 $Q^+$ 이온의 농도와 ${S_2O_4}^{-2}$ 이온의 농도의 제곱근에 정비례하고 $CCl_4$와 MMA의 농도에 각각 정비례하였다.

• Journal of Welding and Joining
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• 제3권2호
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• pp.42-51
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• 1985

The dynamic fracture toughness, fracture characteristics, impact tension and tensile properties of Al-Mg-Si T5 alloy and Al-Zn-Mg T6 alloy respectively welded with filler metal of Alcan 4043 were investigated. The dynamic fracture toughness values were obtained rapidly and simply for the specimen of small size by using instrumented Chirpy impact testing machine. the testing temperatures of the specimen were a range of room temperature and-196.deg. C. The results obtained in this experiment are summarized as follows. With decreasing the testing temperatures, dynamic tensile stress and fracture load were increased, on the other hand the deflection and impact value showed decreasing tendency in order of base metal>HAZ>weld. Changes of total absorbed energy were more influenced by the crack propagation energy than the crack initiation energy. At the low temperatures, the unstable rapid fracture representing the crack propagation appeared for the specimens of Charpy press side notched in Al-Zn-Mg alloy, but it was difficult to obtain the unstable rapid fracture in Al-Mg-Si alloy. Because of the development of plastic zone at the notch root, it was difficult to obtain thevalid $K_{1d}$ value in Al-Mg-Si alloy. Therefore the fatigue cracked specimens were effective in both Al-Mg-Si and Al-Zn-Mg alloys. With decreasing the impact testing temperatures, specimens underwent a transition from dimple-type transgranular fracture to lamella surface-type intergranular fracture because of the precipitate at the grain boundaries, impurities and crystal structure of the precipitates.s.

• Journal of Plant Biotechnology
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• 제37권1호
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• pp.96-101
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• 2010

Leaf explants of the Solanum hainanense plant, grown in vitro, were cultured in basal Murashige and Skoog (MS) media supplemented with 0.5 mg/L kinetin and 1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) for callus initiation. For maintenance and proliferation, the callus was cultured on MS medium supplemented with 1 mg/L 6-benzylaminopurine (BAP) and 0.5 mg/L 2,4-D. The glycoalkaloid content in the callus was at its maximum after ten weeks of culture (188.65 mg/g), whereas that of the one-year-old control was 22.22 mg/g in the root and 5.99 mg/g in the stem. The glycoalkaloid extracted from the callus inhibited the activity of collagenase on collagen gel. High performance liquid chromatography (HPLC) analysis showed that biotransformation occurred when a callus was grown on medium supplemented with various carbon sources. These results suggest that callus of S. hainanense is a good material for production of glycoalkaloid.

• Applied Biological Chemistry
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• 제33권2호
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• pp.129-132
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• 1990

저온에서 식물체중에 축적되는 과산화수소의 생리적 기능을 IAA수준의 조절과 관련하여 연구하였다. 과산화수소는 10mM농도에서 완두의 발근과 귀리 초엽의 신장을 억제하였으며 IAA의 호르몬 효과도 억제하였다. 이 억제효과는 catalase를 첨가하면 해제되었다. 유리의 IAA는 과산화수소와 반응하여 Salkowski시약에 민감하지 않은 어떤 복합체를 형성하여 과산화수소에 의하여 불활성화되는 것처럼 보였다. 그러므로 저온에서 식물체내에 축적된 과산화수소는 IAA를 불활성화하여 세포의 유용한 IAA수준을 하향조절하였을 것으로 여겨졌다.