• KSBB Journal
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• 제16권5호
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• pp.442-445
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• 2001

녹차는 최근 많은 건강 식품으로 많은 관심을 받고 있는 물질이며 함암 및 항산화 효과, 면역체계 강화, 항혈전 효과, 피부암 예방, 심장병 예방 콜레스테롤 예방과 같은 효능을 지닌 카테킨 화합물을 포함하고 있다. 본 연구에서는 녹차로부터 카테킨 화합물을 회수하기 위하여 용매 추출과 분배 방법을 사용하였으며 추출 시 용매, 시간과 온도에 따른 회수율을 비교하여 최적 추출 조건을 조사하였다. 실험 결과로부터 얻은 최적추출 조건은 물 8$0^{\circ}C$에서 40분 동안 추출한후 카페인을 제거하기 위하여 클로로포름으로 분배를 실시하고 다시 에틸아세테리트로 분배를 실시하는것이다. 에틸아세테이트 층에는 EGC, EC EGCG, ECG와 같은 카테린 화합물이 분배되어 있다. 더 나아가서는 제조용 액체 크로마토그패를 이용하여 항암 및 항산화 효과가 가장 좋은 EGCG를 얻을 수 있다.

• 한국식품과학회지
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• 제5권1호
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• pp.55-64
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• 1973

마늘은 옛부터 정력강장제(精力强壯劑) 및 항균(抗菌) 작용에 효력있는 향신식품으로 구전되어 왔다. 마늘이 정력제의 효력을 나타내는 성분은 미지인바 이를 부분적이라도 밝히고저 하였다. 마늘의 독특한 냄새는 allicin 이외 Se 의 휘발성 냄새에 기인됨을 알았다. Se 는 비타민 E 와 밀접한 관련성이 있으므로 마늘 중에 Se 및 유황 아미노산의 함량을 산지 및 품종별로 분석하였다. 특히 단양, 의성산의 좋은 마늘은 다른 산지의 것 보다 Se의 함량이 훨씬 많았다. 마늘 냄새와 Se의 함량은 비례하며 한국산은 외국산보다 Se 의 함량이 월등히 많았다. 또 마늘을 요리하는 방법에 따라 Se 손실량이 크게 차이가 있었다. Se 분석은 $^{77m}Se$ 을 이용한 비파괴 방사화 분석법을 이용하였고 함유황 아미노산은 Label 된 Sulfur 을 써서 TLC Paper-chromatography 로 확인 정량하였다.

• Archives of Pharmacal Research
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• 제29권9호
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• pp.757-761
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• 2006

Six protoberberine alkaloids were isolated from the chloroform layer of the rhizome of Coptis japonica Makino (Ranunculaceae). The structures of the isolated compounds were determined to be 6-([1,3]dioxolo[4,5-g]isoquinoline-5-carbonyl)-2,3-dimethoxy-benzoic acid methyl ester (1), oxyberberine (2), 8-oxo-epiberberine (3), 8-oxocoptisine (4), berberine (5) and palmatine (6) by physicochemical and spectroscopic methods. The compound 3 (8-oxo-epiberberine) was first isolated from natural sources. The compounds were tested for cytotoxicity against five tumor cell lines in vitro by SRB method, and also tested for the MDR reversal activities. Compound 4 was of significant P-gp MDR inhibition activity with ED50 value $0.018\;{\mu}g/mL$ in MES-SA/DX5 cell and $0.0005\;{\mu}g/mL$ in HCT15 cell, respectively.

• 공업화학
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• 제5권6호
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• pp.1056-1061
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• 1994

$80^{\circ}C$에서 열처리하거나, $80^{\circ}C$와 상대습도 85%인 습도 조건에서 처리한 황동이 피복된 강선 코드의 표면 상태와 고무와 접착 성질을 조사하였다. 열처리로 황동의 산화가 진행되었으며, 습윤처리 후에는 더 심하게 산화되었다. 처리기간이 길어질수록 전처리한 코드의 접착 성질이 나빠졌으며, 고무부착 정도가 심하게 저하되었다. 황동 피복층의 산화로 인한 코드의 접착 성질 저하를 산화아연층의 과도한 성장과 연계지어 설명하였다.

• Progress in Superconductivity
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• 제7권2호
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• pp.179-183
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• 2006

As a material for SFCL(Superconducting Fault Current Limiter), BSCCO tube with metal stabilizer is a promising candidate, assuring the stability and large power capacity, For the application, the proper soldering technique, which overcome the difficulties of the joining between BSCCO and metal stabilizer, is required. In this study, after soldering In-Bi solder and In-Sn solder with BSCCO superconductor, welding properties between BSCCO and solders were investigated. Because ceramic materials is difficult to weld, Ag electro-plating on BSCCO 2212 is used for intermetallic layer. To find out the best welding condition for superconductor, soldering is tested in the maximum temperature from $155^{\circ}C\;to\;165^{\circ}C$ in the reflow oven. By investigating the composition and thickness of IMC (lntermetallic Compound) created in the reaction of Ag with solder, we analyzed the welding properties of High-Tc superconductor from a micro point of view.

• 한국식품영양과학회지
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• 제32권1호
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• pp.22-28
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• 2003

단삼을 건조시켜 분쇄한 후 methanol로 추출하여 여러 용매로 분획하여 식품부패미생물의 증식억제 효과를 검색하고 그 항균성 물질을 분리하였다. 단삼의 chloroform 분획 추출물은 B subtilis, S. aureus, L. monocytogenes. E. coli 및 V, parahaemolyticus에 대해서 가장 낮은 농도인 250 $\mu\textrm{g}$/disc 농도에서 가장 높은 항균활성을 나타내었다. 단삼의 chloroform 추출물을 silica gel coliumn chromatography와 TLC로 monitoring 하여 항균성을 실험하였다. 이 결과 우수한 항균성 을 보인 sub fraction을 재차 분리하여 붉은색 결정의 항균성 물질을 얻었고 이를 GC/MS, $^1$H-NMR, $^{13}$C-NMR 로 구조분석 한 결과 화학식 이 $C_{19}$ H$_{20}$ O$_3$이며 분자량이 296.141 의 cryptotanshinone으로 동정되었다.

• 한국재료학회지
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• 제14권5호
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• pp.322-327
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• 2004

Copper-based leadframe sheets were oxidized in two kinds of hot alkaline solutions to form brown-oxide or black-oxide layer on the surface. The oxide coated leadframe sheets were molded with epoxy molding compound (EMC). After post mold curing, the oxide-coated EMC-leadframe joints were machined to form sandwiched Brazil-nut (SBN) specimens. The SBN specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under mixed-mode (mode I + mode II) loading conditions. Fracture surfaces were analyzed by various equipment to investigate failure path. The results revealed that the failure paths were strongly dependent on the oxide type. In case of brown oxide, hackle-type failure was observed and failure path lay near the EMC/CuO interface with a little inclining to CuO at all case. On the other hand, in case of black oxide, quite different failure path was observed with respect to the distance from the tip of pre-crack and phase angle. Different failures occurred with oxide type is presumed to be due to the difference in microstructure of the oxides.

• 한국균학회지
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• 제26권1호통권84호
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• pp.78-85
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• 1998

전국 각지에서 채집한 사멸곤충에서 분리한 곤충 기생성 진균이 생산하는 살충성 생리활성물질을 탐색한 결과 곰팡이 분리주 CNAB-63 균주가 목화진딧물과 점박이응애 모두에 대해 다른 분리균주들보다 비교적 높은 살충효과를 보인 바, 본 균주가 생산하는 살충성분을 각종 chromatography로 분리 정제하였다. 정제된 활성물질 CNAB는 점박이응애에서 66.59%, 목화진딧물에서 52.96%의 살충효과를 보였으며, 그 외에도 온실가루이에 살충효과를 보였으나 배추좀나방에는 미미한 살충효과를 보였다. 한편 활성물질 CNAB는 $100\;{\mu}g/disk$ 농도에서 곰팡이, 효모, 세균류에 전혀 항균활성을 보이지 않았다.

• 한국주조공학회지
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• 제20권2호
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• pp.116-121
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• 2000

Interfacial reaction and mechanical properties between Sn-Zn-X ternary alloys(X : 3wt.%In, 4wt.%Bi) and Cu-substrate were studied. Cu/solder joints were subjected to aging treatments for up to 50days to see interfacial reaction at $100^{\circ}C$ and then were examined changes of microstructure and interfacial compound by optical microscopy, SEM and EDS. Cu/solder joints were aged to 30days and then loaded to failure at cross head speed of 0.3 mm $min^{-1}$ to measure tensile strength. According to the results of the solderability test, additions of In and Bi in the Sn-9wt.%Zn solder improve the wetting characteristics of the alloy and lower the melting temperature. Through the EDS and XRD analysis of Cu/Sn-9wt.%Zn solder joint, it was concluded that the intermetallic compound was the ${\gamma}-Cu_5Zn_8$ phase. Cu-Zn intermetallics at Cu/solder interfaces played an important role in both the microstructure evolution and failure of solder joints. Cu/solder joint strength was decreased by aging treatment, and those phenomenon was closely related to the thickening of intermetallic layer at Cu/solder joints.

• 치위생과학회지
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• 제23권1호
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• pp.60-67
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• 2023

Background: In our study, a silver diamine fluoride (SDF) compound for the treatment of dental caries was synthesized to characterize its remineralization activity upon direct application to deciduous teeth. This study aimed to use microscopic computed tomography (microCT) and nanoindentation to evaluate whether SDF composite application could effectively arrest dental caries in five exfoliated primary molars. Methods: Carious teeth were extracted and visually examined using quantitative photofluorescence devices (Qraycam and QraypenTM). After performing microCT, the SDF composite was applied to the teeth according to the manufacturer's instructions. The researchers exchanged and precipitated the irritant saliva once daily for 1 week. The teeth were sectioned longitudinally through the centers of the mesial and distal surfaces, embedded, polished, and measured using nanoindentation. Thereafter, microCT was repeated. Statistical analyses were performed using GraphPad Prism software. Results: Following SDF composite application, a remineralized layer was observed on microCT images, and the hardness increased when measured using nanoindentation. We found that demineralized enamel presented with an increased number of irregular crystals in the deep carious lesion group compared with those in the shallow carious lesion group, resulting in a rougher surface. Conclusion: The SDF composite may be used for remineralization of early caries and cessation of advanced caries in primary molars.