• 한국결정성장학회지
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• 제18권5호
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• pp.200-204
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• 2008

기계화학공정(MCP; Mechano Chemical Process)은 원료 분말이 기계적인 에너지로 인해 상 형성이 활성화되기 때문에 기존의 볼밀링을 이용한 고상반응에서 필수적인 높은 온도에서의 하소 공정이 필요하지 않다. 본 연구에서는 고 에너지 MCP 방법을 이용하여 perovskite 구조를 가지는 PLT 나노 분말을 제조하였다. 특히, 일반적으로 출발물질로 염을 이용하는 것과 달리 산화물을 원료 분말로 사용하여 어떠한 열처리 공정 없이 PLT 나노 분말을 합성하였다. 또한 건식으로 밀링을 하여 분말 건조 공정이 필요 없어서 공정이 간단하다. MCP 밀링은 시간 별로 12시간까지 진행하였으며, 제조된 분말의 상 분석과 결정면 분석 결과 3시간 이후에는 perovskite 구조의 순수한 PLT 상을 형성하였다. 또한 마이크로 크기의 원료 분말이 밀링 3시간이 지나자 약 20 nm 크기의 균일한 나노 입자가 생성되었다.

• 한국패류학회지
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• 제30권4호
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• pp.353-361
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• 2014

동합금이 사육 생물에게 미치는 생리적 영향을 조사하기 위해 화학적 조성이 다른 5종류의 금속판을 넣은 수조에서 사육한 북방전복을 대상으로 성패와 치패의 생존율, 호흡 및 배설률 그리고 기관별 중금속 축적률을 조사하였다. 생존율은 치패와 성패가 각각 27-60%와 63-83%로 성패가 더 높게 나타났다. 합금 조성에 따른 생존율의 뚜렷한 차이는 나타나지 않으나 중금속 축적률 그리고 영양적인 스트레스 등을 고려하면 동합금망은 전복 양성을 위한 가두리로서는 적합하지 못할 것으로 사료된다.

• Journal of Ginseng Research
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• 제39권3호
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• pp.221-229
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• 2015

Background: Minor ginsenosides, those having low content in ginseng, have higher pharmacological activities. To obtain minor ginsenosides, the biotransformation of American ginseng protopanaxadiol (PPD)-ginsenoside was studied using special ginsenosidase type-I from Aspergillus niger g.848. Methods: DEAE (diethylaminoethyl)-cellulose and polyacrylamide gel electrophoresis were used in enzyme purification, thin-layer chromatography and high performance liquid chromatography (HPLC) were used in enzyme hydrolysis and kinetics; crude enzyme was used in minor ginsenoside preparation from PPD-ginsenoside; the products were separated with silica-gel-column, and recognized by HPLC and NMR (Nuclear Magnetic Resonance). Results: The enzyme molecular weight was 75 kDa; the enzyme firstly hydrolyzed the C-20 position 20-O-${\beta}$-D-Glc of ginsenoside Rb1, then the C-3 position 3-O-${\beta}$-D-Glc with the pathway $Rb1{\rightarrow}Rd{\rightarrow}F2{\rightarrow}C-K$. However, the enzyme firstly hydrolyzed C-3 position 3-O-${\beta}$-D-Glc of ginsenoside Rb2 and Rc, finally hydrolyzed 20-O-L-Ara with the pathway $Rb2{\rightarrow}C-O{\rightarrow}C-Y{\rightarrow}C-K$, and $Rc{\rightarrow}C-Mc1{\rightarrow}C-Mc{\rightarrow}C-K$. According to enzyme kinetics, $K_m$ and $V_{max}$ of Michaelis-Menten equation, the enzyme reaction velocities on ginsenosides were Rb1 > Rb2 > Rc > Rd. However, the pure enzyme yield was only 3.1%, so crude enzyme was used for minor ginsenoside preparation. When the crude enzyme was reacted in 3% American ginseng PPD-ginsenoside (containing Rb1, Rb2, Rc, and Rd) at $45^{\circ}C$ and pH 5.0 for 18 h, the main products were minor ginsenosides C-Mc, C-Y, F2, and C-K; average molar yields were 43.7% for C-Mc from Rc, 42.4% for C-Y from Rb2, and 69.5% for F2 and C-K from Rb1 and Rd. Conclusion: Four monomer minor ginsenosides were successfully produced (at low-cost) from the PPD-ginsenosides using crude enzyme.

• 대한핵의학회지
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• 제25권2호
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• pp.286-293
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• 1991

$^{123}I$, which is applied for the thyroid and other in vivo kinetic study, has a special role in life sciences. The 159 KeV $\gamma-ray$ from $^{123}I$ is almost ideally appropriate for the current imaging instrumentation. Its decay mode (electron capture) and short half-life (13.3 hr) reduced the burden of radiation dose to the patients, and its chemical property makes it easy to synthesize the labelling compounds. In this experiment, the production of $^{123}I$ via the nuclear reaction $^{124}Te(p,2n)^{123}I$ with 28 MeV protons was sutdied. $TeO_2$ is used as a target material, because it has good physical properties. The target was prepared with $TeO_2$ powder and was molten into a ellipsoidal cavity (a=14 mm, b=10 mm, $270.8mg/cm^2$ thick) of pure platinum. The irradiation was carried out in the external proton beam with incident energies range from 28 MeV to 22 MeV, and current was $30{\mu}A$. The loss of $TeO_2$ target was significantly reduced by using $4\pi-cooling$ system in irradiation. The dry distillation method was adopted for the separation of $^{123}I$ from irradiated target, and when it was kept 5 minutes at $780^{\circ}C$, its result was quantitative. The loss of the target material $(TeO_2)$ was below 0.2% for each production run and $^{123}I$ from the dry distillation apparatus was captured with 0.01 N NaOH in $Na^{123}I$ form, then the pH of the solution was adjusted to $7.5\sim9.0$ with HC1/NaOH. The $Na^{123}I$ solution was passed through $0.2{\mu}m$ membrane filter, and sterilized under high pressure and temperature for 30 minutes. The production of $^{123}I$ is acceptable for clinical application based on the quality of USP XXI.

• 대한치과보철학회지
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• 제35권1호
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• pp.43-66
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• 1997

Dental implant may be immediately placed in postextraction socket which has alveolar bone defect. The purpose of this study was to compare the bone regeneration and bone quality around defects adjacent to implants that were placed into extraction sockets according to EFEB, GTAM barrier and GTAM barrier with DFDB. Mandibular P2, P3 and P4 were extracted bilaterally in dogs, and buccal defects were created about 4mm in depth and 3.3mm in width. Screwed pure titanium implants, 3.8mm in diameter and 10mm in length, were placed into the extraction sockets. The experimental groups were divided into four groups : the G group was covered with a GTAM barrier on the defective area, the D+G group was filled with DFEB and covered with a GTAM barrier, the D group was filled with DFDB only and the control group was sutured without any special treatment on the defective area. The experimental animals were killed after 12 weeks and specimens were prepared for light microscopic evaluation and fluorescent dyes were administered daily for 2 weeks after implantation, and injected on the 4th and 11th week for fluorescent microscopic examination to observe new bone formation and bone remodeling. The new Bone height of the buccal defect was measured and compared with the another for bone gain and the removal torque for the implant was measured for the comparison of bone density and bone-implant osseointegration. Results obtained were as follows : 1. Experimental groups showed bone regeneration in oder from D+G, G, D group and control. D+G and G group was significantly from D group and control(P<0.01). 2. In the defective area of control the regenerated alveolar bone showed poorly developed lamellated structure and fibrous tissue intervention into the bone-implant interface but the others showed well developed lamellated structure and osseointegration. 3. All implant groups showed no significaant difference in the removal torque for implant(P>0.05) These results suggest that immediate implants placed in defective sockets were successfully osseointegrated and utilizing placed in defective sockets were successfully osseointegrated and utilizing not only the combination of GTAM and DFDB but also only the GTAM was favorable for the predictable regeneration of the defective area.

• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.92-100
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• 2017

Acetoin (AC) is a volatile platform compound with various potential industrial applications. AC contains two stereoisomeric forms: (3S)-AC and (3R)-AC. Optically pure AC is an important potential intermediate and widely used as a precursor to synthesize novel optically active materials. In this study, chiral (3R)-AC production from meso-2,3-butanediol (meso-2,3-BD) was obtained using recombinant Escherichia coli cells co-expressing meso-2,3-butanediol dehydrogenase (meso-2,3-BDH), NADH oxidase (NOX), and hemoglobin protein (VHB) from Serratia sp. T241, Lactobacillus brevis, and Vitreoscilla, respectively. The new biocatalyst of E. coli/pET-mbdh-nox-vgb was developed and the bioconversion conditions were optimized. Under the optimal conditions, 86.74 g/l of (3R)-AC with the productivity of 3.61 g/l/h and the stereoisomeric purity of 97.89% was achieved from 93.73 g/l meso-2,3-BD using the whole-cell biocatalyst. The yield and productivity were new records for (3R)-AC production. The results exhibit the industrial potential for (3R)-AC production via whole-cell biocatalysis.

• Nutrition Research and Practice
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• 제11권1호
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• pp.43-50
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• 2017

BACKGROUND/OBJECTIVES: The present study investigated the hypothesis that a highly pure linear ${\beta}$-1,3-glucan produced by Agrobacterium sp. R259 enhances human natural killer (NK) cell activity and suppresses pro-inflammatory cytokines. SUBJECTS/METHODS: In an eight-week, double-blind, randomized, placebo-controlled clinical trial, 83 healthy adults with white blood cell counts of $4,000-8,000cells/{\mu}L$ were participated and randomly assigned to take two capsules per day containing either 350 mg ${\beta}$-1,3-glucan or placebo. Six participants withdrew their study consent or were excluded due to NK cell activity levels outside the normal range. NK cell activity and serum levels of immunoglobulin G (IgG) and cytokines, such as interferon (IFN)-${\gamma}$, interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12 and tumor necrosis factor (TNF)-${\alpha}$ were measured. RESULTS: NK cell activity and the serum levels of IL-10 were significantly higher from baseline to week 8 in the ${\beta}$-glucan group compared with the placebo group (P = 0.048, P = 0.029). Consumption of ${\beta}$-1,3-glucan also significantly increased NK cell activity compared with placebo after adjusting for smoking and stress status (P = 0.009). In particular, the effect of ${\beta}$-1,3-glucan on NK cell activity was greater in participants with severe stress than in those experiencing mild stress. However, the administration ${\beta}$-1,3-glucan did not significantly modulate the levels of IFN-${\gamma}$, IL-2, IL-4, IL-6, IL-12, TNF-${\alpha}$ and IgG compared with the placebo. CONCLUSION: The results showed that supplementation with bacterial ${\beta}$-1,3-glucan significantly increased NK cell activity without causing any adverse effects. Additionally, the beneficial effect of ${\beta}$-1,3-glucan on NK cell activity was greater in participants experiencing severe stress.

• 한국정보과학회논문지:소프트웨어및응용
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• 제34권9호
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• pp.828-847
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• 2007

본 논문에서는 패싯 분류에 기반하여 다차원 사용자 관점의 도메인 시소러스를 체계적으로 구축하고, 각 관점에 따라 시각화된 환경에서 시소러스를 브라우징, 항해 그리고 검색할 수 있는 다차원 관점객체기반 패싯 시소러스 시스템을 제안한다. 기존의 패싯 시소러스 시스템들과 달리, 본 시스템은 개념들간의 다각적인 상관 관계를 객체 지향 패러다임에 따라 자동으로 설정 구축할 수 있고, 브라우징과 항해를 통해 다차원 시소러스의 복잡한 개념 구조를 적절히 시각화할 수 있기 때문에, 시소러스의 유지 보수 관리가 용이하다. 다차원 브라우징 및 항해는 계층화된 패싯 용어들간의 조합으로 이루어진 패싯화된 시소러스를 필요시 동적으로 생성함으로써 이루어진다. 패싯화된 시소러스는 일종의 다차원 가상 시소러스 계층들로 볼 수 있다. 제안하는 방식에 의한 시소러스 자동 구축은 패싯들의 조합으로 새로운 차원의 시소러스를 용이하게 추가할 수 있기 때문에, 융통성 있는 시소러스 확장이 가능하고 대량의 시소러스 인스턴스들을 관점에 따라 적절한 해석을 부여하는 방식으로 구조화하기 때문에 개별적 사용자 관점에 부합되는 인스턴스들을 참조 질의에 의해 효율적으로 검색할 수 있다. 본 논문에서는 먼저 제안 시스템을 체계화하기 위한 모델을 정형화하고 이를 바탕으로 모델의 실용성을 입증하기 위해 그 프로토타입을 구현하였다.

• 한국해양환경ㆍ에너지학회지
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• 제4권2호
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• pp.25-34
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• 2001

마산만에서 Ra 동위원소의 농도를 결정하는 요인을 살펴보기 위해 1개 고정정점에서 1999년 5월에서 8월까지 총 4회에 걸쳐 해수 중의 /sup 226/Ra과 /sup 228/Ra을 수심별로 측정하였다. /sup 226/Ra과 /sup 228/Ra의 농도는 강수량이 많은 하계 (8월 1일)에 비교적 높으나, 그 외의 조사시기에는 비교적 낮다. 마산만 표층수의 /sup 226/Ra의 시계열 변화는 염분과 높은 부의 상관관계를 보여 표층수의 /sup 226/Ra 농도는 저염분의 높은 /sup 226/Ra 내만수와 고염분의 낮은 /sup 226/Ra의 외양수의 혼합에 지배적인 것으로 사료된다. /sup 228/Ra//sup 226/Ra의 방사능비는 표층수 보다 저층수에서 낮고, 이는 저층수에 과량의 /sup 226/Ra 공급원이 존재한다는 것을 의미한다. 그러나 해수의 Ra 동위원소의 주요 공급원인 퇴적물 및 간극수는 /sup 226/Ra에 비해 상대적으로 풍부한 /sup 228/Ra을 함유하기 때문에 저층수의 낮은 /sup 228/Ra/sup 226/Ra 비는 /sup 226/Ra이 풍부한 해저지하수의 누출 가능성을 의미한다. 따라서 마산만에서 해저지하수 누출은 /sup 226/Ra의 농도분포를 결정하는 또다른 중요한 기작으로 사료되며, 이에 대한 집중적인 연구가 요망된다.

• 한국수산과학회지
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• 제17권3호
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• pp.170-176
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• 1984

전보에 이어서 우리나라 주요 담수어의 정미성분을 밝힐 목적으로 붕어 배육중의 유리아미노산, 핵산관련물질, 유기염기, 당류, 유기산 및 무기질을 분석하였고 이 분석치를 기초로 하여 표준 시약으로 합성엑스분을 조제해서 천연엑스분과 맛을 비교하였으며 omission test를 통하여 각 성분들이 맛에 미치는 영향을 실험 검토하였다. 유리아미노산 중 histidine 함량이 월등히 많아 전체 유리아미노산의 $46\%$를 차지하였으며 다음으로 glycine, lysine, alanine, taurine 등이 많았다. 핵산관련물질 중에는 IMP 함량이 166.lmg/100g으로서 가장 많았으며 그 외 성분은 함량이 적었다. 유기염기로서는 총 creatinine 이 320.5 mg/100 g으로 가장 함량이 많았고 betaine은 21.6mg/100g이었으며 TMA 및 TMAO는 1mg/100g미만으로 극미량이었다. 유기산의 경우는 숙신산, 프로피온산, 보티르산, 발레르산등이 함량이 많았고 옥살산, 푸마르산, 말레산, 타르타르산 및 시트르산은 흔적량에 불과하였다. 당류의 함량으로는 포도당이 2.4mg/100g이었고 ribose, arabinose, fructose 및 inositol은 1 mg/100g미만이었다. 무기염류 중에는 $K^+$ 및 $PO_4^{3-}$이 각각 220.0mg/100g, 288.7mg/100g으로서 월등히 많았고 다른 무기염류는 32 mg/100g 이하이었다. omission test에 의한 관능검사 결과에 의하면, 붕어의 주된 정미성분은 serine, glutamic acid, IMP, $Na^+,\;K^+$ 및 $PO_4^{3-}$이었으며 lysine, arginine, tyrosine 및 phenylalanine에 의해서 더욱 맛이 조화를 이루고 있었다.