• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.305-305
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• 2014

양자점(Quantum dots)은 3차원적 운반자 구속과 낮은 전류와 높은 온도에서 작동하는 나노 크기의 전기적, 광학적 소자로 응용이 적합하기 때문에 그 특성을 이용한 단전자 트랜지스터, 적외선 검출기, 레이저, LED, 태양전지 등 반도체 소자로의 응용연구가 활발히 진행되고 있다. 특히 양자점의 낮은 임계전류밀도와 높은 차동 이득(differential gain), 그리고 고온에서 작동이 용이하여 양자점 레이저로 활용되고 있다. 이러한 분야에 양자점을 응용하기 위해서는 양자점의 운반자 동역학을 이해하고 양자점의 모양, 크기, 크기 분포와 같은 특성 조절이 필요하다. 또한 기존의 연구들은 III-V족 화합물 반도체 양자점에 대한 연구가 대부분이며, II-VI족으로 구성된 연구가 미흡한 상황이기 때문에 II-VI족 화합물 반도체 양자점에 대한 많은 연구가 필요한 상황이다. II-VI 족 화합물 반도체 양자점은 기존의 III-V 족 양자점보다 더 큰 엑시톤 결합에너지(exciton binding energy)를 가지고 있으며, 이러한 특성을 가지는 II-VI 족 화합물 반도체 양자점 중에서도 CdTe 양자점은 높은 엑시톤 결합에너지와 녹색 스펙트럼 영역을 필요로 하는 광학적 장치들에 응용 가능성이 높기 때문에 더욱 주목받고 있다. 본 연구에서는 분자 선속 에피 성장법(Molecular Beam Epitaxy; MBE)과 원자 층 교대 성장법(Atomic Layer Epitaxy; ALE)으로 CdTe/ZnTe 나노구조에서 ZnTe 완충층의 두께에 따른 운반자 동역학 및 광학적 특성을 연구 하였다. 저온 광루미네센스 측정(Photoluminescence; PL) 을 통하여 ZnTe 완충층 두께가 증가할수록 양자점의 광루미네센스 피크가 낮은 에너지로 이동함을 알 수 있었는데, 이는 ZnTe 완충층의 두께가 증가할수록 ZnTe 완충층과 CdTe 양자점의 격자 불일치(lattice mismatch)로 인한 구조 변형력이 감소하고 이에 따라 CdTe 양자점으로 가해지는 변형(Strain)이 감소하여 CdTe 양자점의 크기가 증가했기 때문이다. 그리고 ZnTe 완충층의 두께가 증가할수록 PL 세기가 증가함을 알 수 있었는데, 이는 ZnTe 완충층의 두께가 증가할수록 양자 구속 효과로부터 electronic state와 conduction band edge 사이의 에너지 차이의 증가 때문이다. 또한 시분해 광루미네센스 측정 결과 ZnTe의 두께가 증가할수록 양자점의 소멸 시간이 더 길게 측정되었는데, 이는 더 큰 양자점 일수록 엑시톤 오실레이터 강도가 감소하기 때문에 더 긴 소멸 시간을 나타내는 것을 확인할 수 있었다. 결과적으로 본 연구는 ZnTe 두께 변화를 통해 양자점의 에너지 밴드를 제어할 수 있으며, 양자점의 효율 향상을 할 수 있는 좋은 방법임을 제시하고 있다.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.140-147
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• 2009

In this study, anaerobic enrichment cultivation was performed with the sediments from the Gimpo and Inchon areas. Lactate as an electron donor and PCE as an electron acceptor was injected into the serum bottle with an anaerobic medium. After the incubation of 8 weeks, the reductive dechlorination of PCE was observed in 7 sites among 16 sites (43%). Three enrichment cultures showed completely dechlorination of PCE to ethene, while four enrichment culture showed transformation of PCE to cis-DCE. The bacterial community structure was analyzed by PCR-DGGE. Dechlorinating bacteria were detected by species-specific primers. The dominant species in seven anaerobic enrichments were found to belong to the genus of Dehalococcoides sp. and Geobacter sp., and Dehalobacter sp.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.15-22
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• 1998

The dnrF gene, responsible for conversion of aklavinone to $\varepsilon$-rhodomycinone via C-11 hydroxylation, was mapped in the daunorubicin gene cluster of Streptomyces peucetius subsp. caesius ATCC 27952, close to drrAB, one of the anthracycline resistance genes. To characterize the enzymatic properties of the aklavinone 11-hydroxylase, the dnrF gene was overexpressed in Escherchia coli. The pET-22(+) plasmid which has the T7 promoter under the control of lacUV5 gene was used for the overexpression of the dnrF gene, and the recombinant plasmid pET213 that contains the dnrF gene linked to the T7 promoter of pET-22b(+) was introduced into the E. coli BL2l. When the expression of the dnrF gene was induced by IPTG at the final concentration of 1 mM, the induced protein could be detected in SDS-PAGE only in insoluble precipitate. The insoluble protein was electroeluted from the gel and used for the preparation of antiserum in mice. Various culture conditions were tested to maximize the expression of the aklavinone 11-hydroxylase in soluble form. The enzymatic activity was checked by the bioconversion experiment, and the protein was confirmed by the SDS-PAGE and the Western blot analysis. From the analysis of the data, it was concluded that the culture induced with IPTG at the final concentration of 0.02 mM at 37$^{\circ}C$ yielded the best productivity of active form of enzyme.

• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.419-422
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• 2009

We performed the PARR (PCR to detect antigen receptor rearrangements) test on DNA isolated from twelve archival canine cytological slides including nine lymphoma, two reactive lymphocytes and one sample from Ehrlichia canis infected dog. As a result, our PCR control gene, $C{\mu}$, was successfully amplified from all of the DNA samples. Six out of nine lymphoma samples showed a clonal rearrangement of immunoglobulin gene whereas three samples did a clonal rearrangement of T cell receptor gamma ($TCR{\gamma}$) gene. However, we observed no visible or clear bands from PCR conducted using our antigen receptor rearrangement primers on DNA from a reactive lymphoid cell proliferation used as a negative control. False-positive amplification in $TCR{\gamma}$ gene was observed only in one sample from E. canis infection. The use of archival cytological specimens demonstrated in this study offers potential advantages for cost-effective specimen acquisition and efficient high-fidelity DNA analysis.

• Research in Plant Disease
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• v.15 no.3
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• pp.254-258
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• 2009

An isolate of Cucumber mosaic virus (CMV), called as Lag-CMV, was identified from Lagenaria leucantha var. gourda showing mosaic symptom, and its properties was compared to Fny-CMV (subgroup IA) and As-CMV (subgroup IB) by host reaction in several indicator plants, dsRNA analysis, RT-PCR analysis, restriction enzyme profile of the PCR products and nucleotide sequence of coat protein gene. Lag-CMV was similar to As-CMV used as a control CMV by the induced chlorotic spot on inoculated leaves and mosaic symptoms on upper leaves of N. tabacum. cv. Xanthi nc. In the cucumber and zucchini squash, Lag-CMV and As-CMV induced a mild mosaic symptoms than that of Fny-CMV. Size and shapes of local lesions on Chenophodium amaranticolor and Vigna unguiculata induced by Lag-CMV was similar those by Fny-CMV or As-CMV. In experiments of dsRNA profiles and RT-PCR analysis of coat protein gene, Lag-CMV was come within subgroup I CMV. Moreover, restriction enzyme analysis using EcoRI, SalI, MspI, XhoI, and HindIII of the RTPCR products and nucleotide sequence analysis of the coat protein gene showed that Lag-CMV belong to a member of CMV subgroup IB of the same to As-CMV.

• Korean Journal of Food Science and Technology
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• v.48 no.6
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• pp.590-596
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• 2016

This study was designed to investigate the antioxidant activities of the ethanol extracts (GBE) of grape branches (Campbell Early). The total polyphenol and flavonoid content of GBE was $201.42{\pm}4.16$ and $11.85{\pm}0.44mg\;GAE/g$, respectively. The antioxidant activity of GBE was measured using the ABTS and DPPH assays, and the $IC_{50}$ values were $45.60{\pm}0.09$ and $299.13{\pm}0.22$, respectively. GBE inhibited the production of pro-inflammatory mediators (NO, iNOS, $PGE_2$, COX-2, $IL-1{\beta}$, and IL-6) in lipopolysaccharide-stimulated RAW 264.7 macrophages in a dose-dependent manner. Moreover, GBE treatment significantly suppressed the production of $TNF-{\alpha}$ and IL-6 cytokines in phorbol 12-myristate 13-acetate plus calcium ionophore A23187-stimulated HMC-1 human mast cells. Furthermore, the administration of GBE markedly inhibited the scratching behavior induced by the compound 48/80 in ICR mice. These results suggested that GBE has potential as a therapeutic agent against inflammation and itch-related skin diseases.

• Journal of Life Science
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• v.29 no.12
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• pp.1314-1320
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• 2019

This study aimed to identify single nucleotide polymorphisms in exon 8 region of the calmin (CLMN) gene and to evaluate their associations with meat yield and quality traits in Hanwoo (Korean cattle). We compared gene expression pattern of CLMN between high and low marbling score groups with extremely different intramuscular fat content of the longissimus lumborum muscles in Hanwoo. The CLMN gene was highly expressed in the high marbling score group. Total of nine SNPs were identified in the exon 8 region of CLMN gene, genotyping of the SNPs was carried out using direct-sequencing analysis in Hanwoo population (n=300) to evaluate their association with meat yield and quality traits. As a result, g.23249G>C in exon 8 was significantly associated with marbling score. Animals with the CC and GC genotypes had higher marbling score than those with the GG genotype. We constructed haplotypes of CLMN gene by linkage disequilibrium analysis and analyzed association between haplotypes and meat yield and quality traits. Haplotype of CLMN gene was associated with marbling score. As a result, animals with the CC-CC haplotype (g.23249G>C and g.23465T>C SNPs) had higher marbling score than those with CT and GT haplotypes. These findings suggest that the SNPs of bovine CLMN gene may be a useful molecular marker for selection of meat quality traits in Hanwoo.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.288-291
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• 2012

Korean oak wilt disease caused by Raffaelea quercus-mongolicae is vectored by the ambrosia beetle Platypus koryoensis. To prevent the spread of the disease, the beetle infested oak tree had been cut into logs, covered with plastic vinyl, fumigated with a pesticide, and stored for three years on the site where the tree was cut. This study was carried out to get information on the fungi colonizing the fumigated oak wood. Wood disk samples collected from the fumigated oak logs at two locations in the Taejo Mountain, Cheonan city, were used for fungal isolation. A total of 99 filamentous fungal isolates were obtained from the wood disk samples. Hypocrea spp., Trichoderma spp. and Penicillium spp. were identified based on morphological characteristics and nucleotide sequence analysis of translation elongation factor 1-alpha gene and ITS rDNA region. Trichoderma was the major fungal group. R. quercus-mongolicae, and P. koryoensis were not detected from the fumigated oak wood. Our work provided evidence that after three years of storage, the fumigated oak wilt-diseased logs should be no longer harmful source of oak wilt disease transmission.

• Parasites, Hosts and Diseases
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• v.27 no.1
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• pp.9-14
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• 1989

Enzyme-linked immunoelectrotransfer blot (EITB) using crude worm antigen of adult Paragonimus westermani was performed for human patients sera to identify the species-specific components. Crude antigen was obtained by homogenizing and centrifuging 24-week old adult worms at 10,000 rpm for 60 minutes in phosphate buffered saline (PBS, PH 7.2) containing: Phenyl methyl sulfonyl auoride (PMSF). Gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) was performed and blotted electrophoretically onto a sheet of nitrocellulose paper. The sheet was cut into strips and exposed to sera diluted 1 : 200 with PBS. SDS-PAGE showed 26 protein bands ranging 229 to 10 kDa. Of them 229, 91, 60, 50, 35∼31, 27, 25, 21, 17, 11 and 10 kDa components showed positive reaction with serum antibody of patients with p. westermani. Sera of patients infected with Clcnorchis sinensis reacted with 35∼31, 19, and 11 kDa bands. Human sera from cysticercosis and diphyllobothriasis cases showed non-specific cross reactions with 229, 35∼31, 27, 25 and 17kDa bands. Protein bands of 91, 60, 21 and 10kDa showed strong positive reaction without cross reactions with sera from other helminthic infections.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.298-299
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• 2012

현재 반도체 나노구조는 단전자 트랜지스터, 레이저, LED, 적외선 검출기 등과 같은 고효율 광전자 소자에서의 응용을 위해 활발한 연구가 진행 되고 있다. 이러한 응용 분야를 위한 다양한 종류의 나노구조 성장이 광범위하게 시도 되고 있지만 주로 III-V 족 화합물 반도체에 대한 연구가 주를 이룬 반면 II-VI 족 화합물 반도체에 대한 연구는 아직 미흡하다. 하지만 II-VI 족 화합물 반도체는 III-V 족 화합물 반도체와 비교했을 때 더 큰 엑시톤 결합에너지(exciton binding energy)를 가지는 우수한 특성을 보이고 있으며 이러한 성질을 가지는 II-VI 족 화합물 반도체 중에서도 넓은 에너지 갭을 가지는 CdTe 양자점은 녹색 영역대의 광전자 소자로서 활용되고 있다. 본 연구에서는 분자 선속 에피 성장법(molecular beam epitaxy; MBE)과 원자 층 교대 성장법(atomic layer epitaxy; ALE)으로 CdTe 두께에 따른CdTe/ZnTe 나노구조의 광학적 특성을 연구하였다. 광루미네센스(photoluminescence; PL)를 통해 CdTe/ZnTe 나노구조에서 CdTe 두께에 따른 에너지 밴드와 열적 활성화 에너지를 관찰하였다. 또한 시분해 광루미네센스(Time-resolved PL)를 통해 CdTe 두께에 따른 CdTe/ZnTe 나노구조의 운반자 동역학을 조사하였다. 저온 광루미네센스 측정 결과 CdTe 두께가 증가할수록 각 샘플의 피크는 더 낮은 에너지 영역대로 이동하는 것을 관찰할 수 있다. 1.2 에서 2.0 ML로 증가할 때 광 루미네센스의 작은 적색편이를 관찰할 수 있는데, 이는 CdTe 양자우물에서 양자점으로의 구조적인 전이가 일어남에 따라 구속효과가 증가하였기 때문이다. 또한 2.0 에서 3.6 ML까지 CdTe 두께가 증가할 때 측정된 적색편이 현상은 양자점의 사이즈 증가함에 따른 것이다. 마지막으로 3.6 에서 4.4 ML로 CdTe 두께가 증가할 때 큰 적색편이 현상을 볼 수 있는데 이는 CdTe 양자점에서 양자세선으로의 구조적 전이에 따라 구속효과가 증가하였기 때문이다. 온도 의존 광루미네센스(Temperature-dependent PL) 측정 결과 1.2 와 3.0 ML 두께의 CdTe/ZnTe 나노구조에서 구속된 전자의 열적 활성화 에너지가 18 과 35 meV로 관찰되었다. 3.0 ML CdTe/ZnTe 나노구조에서 가장 큰 열적 활성화 에너지를 갖는 것은 양자점의 균일도가 좋아지고 저차원 나노구조로의 구조적 전이가 일어나면서 운반자 구속효과에 다른 쿨롱 상호작용이 증가하였기 때문이다.