• 한국전자파학회논문지
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• 제15권8호
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• pp.752-758
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• 2004

본 논문에서는 MBE로 성장한 AlGaN/InGaN/GaN 에피층으로 제작된 GaN HEMTs의 특성을 분석하였다. 게이트 전극 길이가 0.5 $\mu$m로 제작된 소자는 비교적 평탄한 전류 전달 특성을 나타내었으며 최대 전류 880 mA/mm, 최대 전달정수 156 mS/mm, 그리고 $f_{r}$와 $f_{MAX}$는 각각 17.3 GHz와 28.7 GHz가 측정되었다. 또한 표면 처리되지 않은 AlGaN/InGaN/HEMT의 경우 기존의 AlGaN/GaN HEMT와는 달리 펄스 전류 동작 상태에서 전류 와해 현상(current collapse)이 발생하지 않음이 확인되었다. 이 연구 결과는 InGaN를 채널층으로 사용할 경우 표면에 존재하는 트랩에 의한 전류 와해 현상이 발생하지 않는 고성능, 고출력의 GaN HEMT를 제작할 수 있음을 보여준다....

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.63-70
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• 2010

Novel influenza A (H1N1) is a newly emerged flu virus that was first detected in April 2009. Unlike the avian influenza (H5N1), this virus has been known to be able to spread from human to human directly. Although it is uncertain how severe this novel H1N1 virus will be in terms of human illness, the illness may be more widespread because most people will not have immunity to it. In this study, we compared the codon usage bias between the novel H1N1 influenza A viruses and other viruses such as H1N1 and H5N1 subtypes to investigate the genomic patterns of novel influenza A (H1N1). Totally, 1,675 nucleotide sequences of the hemagglutinin (HA) and neuraminidase (NA) genes of influenza A virus, including H1N1 and H5N1 subtypes occurring from 2004 to 2009, were used. As a result, we found that the novel H1N1 influenza A viruses showed the most close correlations with the swine-origin H1N1 subtypes than other H1N1 viruses, in the result from not only the analysis of nucleotide compositions, but also the phylogenetic analysis. Although the genetic sequences of novel H1N1 subtypes were not exactly the same as the other H1N1 subtypes, the HA and NA genes of novel H1N1s showed very similar codon usage patterns with other H1N1 subtypes, especially with the swine-origin H1N1 influenza A viruses. Our findings strongly suggested that those novel H1N1 viruses seemed to be originated from the swine-host H1N1 viruses in terms of the codon usage patterns.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.218-226
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• 2018

Nanometric Lactobacillus plantarum nF1 (nLp-nF1) is a biogenics consisting of dead L. plantarum cells pretreated with heat and a nanodispersion process. In this study, we investigated the immune-enhancing effects of nLp-nF1 in vivo and in vitro. To evaluate the immunostimulatory effects of nLp-nF1, mice immunosuppressed by cyclophosphamide (CPP) treatment were administered with nLp-nF1. As expected, CPP restricted the immune response of mice, whereas oral administration of nLp-nF1 significantly increased the total IgG in the serum, and cytokine production (interleukin-12 (IL-12) and tumor necrosis factor alpha (TNF-${\alpha}$)) in bone marrow cells. Furthermore, nLp-nF1 enhanced the production of splenic cytokines such as IL-12, TNF-${\alpha}$, and interferon gamma (IFN-${\gamma}$). In vitro, nLp-nF1 stimulated the immune response by enhancing the production of cytokines such as IL-12, TNF-${\alpha}$, and IFN-${\gamma}$. Moreover, nLp-nF1 given a food additive enhanced the immune responses when combined with various food materials in vitro. These results suggest that nLp-nF1 could be used to strengthen the immune system and recover normal immunity in people with a weak immune system, such as children, the elderly, and patients.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1290-1302
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• 2016

Microalgae are being researched for their potential as attractive biofuel feedstock, particularly for their lipid production. For maximizing biofuel production, it is necessary to explore the effects of environmental factors on algal lipid-producing potential. In this study, the effects of nitrogen (N) sources (NO₂-N, NO₃-N, urea-N, NH₄-N, and N-deficiency) and carbon-to-nitrogen ratios (C/N= 0, 1.0, 3.0, and 5.0) on algal lipid-producing potential of Chlorella sp. HQ were investigated. The results showed that for Chlorella growth and lipid accumulation potential, NO₂-N was the best amongst the nitrogen sources, and NO₃-N and urea-N also contributed to algal growth and lipid accumulation potential, but NH₄-N and N-deficiency instead caused inhibitory effects. Moreover, the results indicated that algal lipid-producing potential was related to C/N ratios. With NO₂-N treatment and carbon addition (C/N = 1.0, 3.0, and 5.0), total lipid yield was enhanced by 12.96-20.37%, but triacylglycerol (TAG) yields decreased by 25.52-94.31%. As for NO₃-N treatment, carbon addition led to a 17.82-57.43%/25.86-82.67% reduction of total lipid/TAG yields. When NH₄-N was used as the nitrogen source, total lipid/TAG yields were increased by 46.67-113.33%/28.99-74.76% with carbon addition. The total lipid/TAG yields of urea-N treatment varied with C/N ratios. Overall, the highest TAG yield (TAG yield: 38.75 ± 5.21 mg/l; TAG content: 44.16 ± 4.35%) was achieved under NO₂-N treatment without carbon addition (C/N = 0), the condition that had merit for biofuel production.

• 대한전자공학회논문지SD
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• 제41권11호
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• pp.29-34
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• 2004

본 논문에서는 molecular beam epitaxy (MBE)로 성장한 AlGaN/InGaN/GaN high electron-mobility transistors (HEMTs)의 선형성과 RF dispersion 특성을 조사하였다. 전극 길이가 0.5 ㎛인 AlGaN/InGaN HEMT는 최대 전류 밀도가 730mA/mm, 최대 전달정수가 156 mS/mm인 비교적 우수한 DC 특성과 함께, 기존의 AlGaN/GaN HEMT와는 달리 높은 게이트 전압에도 완만한 전류 전달 특성을 보여 선형성이 우수함을 나타내었다. 또한 여러 다른 온도에서 측정한 펄스 전류 특성에서 소자 표면에 존재하는 트랩에 의한 전류 와해 (current collapse) 현상이 발생되지 않음을 확인하였다. 이 연구 결과는 InGaN를 채널층으로 하는 GaN HEMT의 경우 선형성이 우수하고, 고전압 RF 동작조건에서 출력저하가 발생하지 않는 고출력 소자를 제작할 수 있음을 보여준다.

• 대한수학회논문집
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• 제25권4호
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• pp.557-569
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• 2010

Suppose that n is a positive integer. For any real number $\alpha$($\beta$ resp.) with $\alpha$ < 1 ($\beta$ > 1 resp.), let $K^{(n)}(\alpha)$ ($K^{(n)}(\beta)$ resp.) be the class of analytic functions in the unit disk $\mathbb{D}$ with f(0) = f'(0) = $\cdots$ = $f^{(n-1)}(0)$ = $f^{(n)}(0)-1\;=\;0$, Re($\frac{zf^{n+1}(z)}{f^{(n)}(z)}+1$) > $\alpha$ (Re($\frac{zf^{n+1}(z)}{f^{(n)}(z)}+1$) < $\beta$ resp.) in $\mathbb{D}$, and for any ${\lambda}\;{\in}\;\bar{\mathbb{D}}$, let $K^{(n)}({\alpha},\;{\lambda})$ $K^{(n)}({\beta},\;{\lambda})$ resp.) denote a subclass of $K^{(n)}(\alpha)$ ($K^{(n)}(\beta)$ resp.) whose elements satisfy some condition about derivatives. For any fixed $z_0\;{\in}\;\mathbb{D}$, we shall determine the two regions of variability $V^{(n)}(z_0,\;{\alpha})$, ($V^{(n)}(z_0,\;{\beta})$ resp.) and $V^{(n)}(z_0,\;{\alpha},\;{\lambda})$ ($V^{(n)}(z_0,\;{\beta},\;{\lambda})$ resp.). Also we shall determine the extreme points of the families of analytic functions which satisfy $f(\mathbb{D})\;{\subset}\;V^{(n)}(z_0,\;{\alpha})$ ($f(\mathbb{D})\;{\subset}\;V^{(n)}(z_0,\;{\beta})$ resp.) when f ranges over the classes $K^{(n)}(\alpha)$ ($K^{(n)(\beta)$ resp.) and $K^{(n)}({\alpha},\;{\lambda})$ ($K^{(n)}({\beta},\;{\lambda})$ resp.), respectively.

• 한국초지조사료학회지
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• 제15권3호
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• pp.164-168
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• 1995

A field experiment was carried out to determine the effects of nitrogen (N) fertilization levels after first harvest (0, 30, 60, 90 and 120 kglha) during spring season on the gms growth, dry matter (DM) yield, nutritive value, and efficiency of DM production per N kg applied in orchardgrass meadow. Additional N was applicated at early spring (70 kg), after second harvest (50 kg), and after fourth harvest (30 kg/ha) in all treatments, 1990. Growth and DM yield of orchardgrass at second harvest were significantly increased with increasing level of N after first harvest (P<0.05), but no yield differences were observed between application of N 60, N 90, and N 120 kg. The efficiency of DM increment per N kg applied was rapidly decreased with increasing level of N; that was 14.8, 12.0, 10.7 and 4.7 DM kg/N kgha in the plot of N 30, N 60, N 90 and N 120 kg, respectively. The content and yield of crude protein of orchardgrass at second harvest were significantly increased with increasing of N (P<0.05), ranged h r n 11.0% (N 0 kg) to 16.8% (N 120 kg), and from 195.0 kg (N 0 kg) to 508.2 kglha (N 120 kg), respectively. However, the content of neutral detergent fiber was not affected by N level after first harvest. From the above results, it is suggested that application of N fertilizer after first harvest was very effective for regrowth and nutritive value of orchardgrass during spring season, and the proper amount of N after first harvest was 60-90 kglha in this experiment.

• 약학회지
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• 제28권4호
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• pp.197-206
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• 1984

The derivatives of N-(alkylcarbamoyl) amino acid methyl ester, N-(2-chloroethylcarbamoyl)-glycine methyl ester (7a), -valine methyl ester (8a), -phenylalanine methyl ester (9a), N-(N'-methylcarbamoyl)-glycine methyl ester (7b), -valine methyl ester (8b), and-phenylalanine methyl ester (9b), were prepared by reacting the corresponding free amino acid methyl ester (glycine-, valine-, phenylalanine-methyl ester) with isocyanate (R-N=C=O${\cdot};R=Cl-CH_2-CH_2-or\; CH_3-)$. The prepared N-(alkylcarbamoyl) amino acid methyl esters (7,8,9) were treated with $NaNO_2$/98% HCOOH in order to obtain their nitrosoated products, N-(alkyl-N'-nitrosocarbmoyl)amino acid methyl ester. The compound (7,8,9) gave N-(2-chloroethyl-N'-nitrosocarbamoyl)-valine methyl ester (14a),-phenylalanine methyl ester (15a), N-(N'-alkyl-N'-nitrosocarbamoyl)-glycine methyl ester (13b),-valine methyl ester. (14b), and-phenylalanine methyl ester (15b) respectively under the nitrosoation. On the other hand, N-(2-chloroethylcarbamoyl) glycine methyl ester produced N-(2-chloroethylcarbamoyl)-N-nitrosoglycine methyl ester (13a). The inhibitory activity of the prepared N-(alkylcarbamoyl) amino acid methyl ester (7,8,9) and N-(alkyl-N'-nitrosocarbamoyl) amino acid methyl ester (13,14,15) towards the growth of L1210 murine leukemia cells were examined. Among them the compound (14a) and (15a) exhibit excellent activity having $ED_{50}\; to\;be\;1.5{\mu}g/ml\;and\;3.0{\mu}g/ml respectively.

• 한국결정성장학회지
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• 제32권3호
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• pp.83-88
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• 2022

이종 기판과 GaN의 물성 차이로 인해 발생하는 결함을 제어하기 위한 다양한 방법 중 동종 물질을 완충층으로 사용하는 LT-GaN 방법을 사용하여 완충층과 성장 온도의 상관성을 자체 제작한 성장 장비를 통해 확인하고자 하였다. 성장 온도에 따라 표면에 형성된 LT-GaN 결정성에 변화가 있었으며, annealing 후 LT-GaN가 나타내는 결정성에 따라 epiGaN의 응력 완화 효과에 차이점이 있었다. 반면 LT-GaN의 높은 결정성은 다결정을 형성하는 원인으로 작용하여 그 위에 성장하는 epi-GaN의 결정질을 저해하는 결과를 유발하였다.

• 한국정보전자통신기술학회논문지
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• 제16권4호
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• pp.180-186
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• 2023

본 논문은 4세대 VNAND 공정으로 만들어진 고전압 SiO2 절연층 nMOSFET의 n⁺ 및 p⁺ poly-Si 게이트에서의 positive bias temperature instability(PBTI) 열화에 대해 비교하고 각각의 메커니즘에 대해 분석한다. 게이트 전극 물질의 차이로 인한 절연층의 전계 차이 때문에 n⁺/nMOSFET의 열화가 p⁺/nMOSFET의 열화보다 더 클 것이라는 예상과 다르게 오히려 p⁺/nMOSFET의 열화가 더 크게 측정되었다. 원인을 분석하기 위해 각각의 경우에 대해 interface state와 oxide charge를 각각 추출하였고, 캐리어 분리 기법으로 전하의 주입과 포획 메커니즘을 분석하였다. 그 결과, p⁺ poly-Si 게이트에 의한 정공 주입 및 포획이 p⁺/nMOSFET의 열화를 가속시킴을 확인하였다.