http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
초격자 고경도 나노 다층막 소재의 복합경도 해석을 통한 계면 강화 효과 분석
김성훈,이윤희,박종극,백영준,권동일 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.12
Multilayer coatings consisting of very thin layers of nitride materials deposited by magnetron sputtering (sometimes called superlattices) exhibit hardnesses over 50 GPa, much higher than that of single layers. Several explanations for this hardness increase have been proposed, including dislocation blocking by layer interfaces, Hall- Petch strengthening, strain effects at layer interfaces, and the supermodulus effect. Among these, dislocation blocking has been generally accepted as a dominant factor in large hardness enhancement. However, the interface between two materials consisting of multilayers is broadened due to interdiffusion. The magnitude of hardness enhancement by the interface has not yet been quantified for real systems. In this study, the concept of composite hardness is introduced to quantify the interface-related hardness enhancement. We suggest a composite hardness equation and quantifythe magnitude of hardness increase by using an equation based on the interface hardness and the interface thickness derived by comparing results derived from this equation and those determined in nanoindentation tests. Three multilayer systems, such as TiN/VN, TiN/NbN and CrN/NbN were used in the equation.
잡초성벼의 superoxide dismutase cDNA cloning과 재배벼로의 형질전환
박상규,박종석,이승인,서석철,김병극,조윤래,서학수 한국환경농학회 2002 한국환경농학회지 Vol.21 No.2
냉해나 한발등의 환경스트레스에 대해 저항성을 유발하는 유전자를 환경스트레스에 강한 잡초성벼로부터 선발하고 이들 유전자를 재배벼에 도입하여 도입유전자 산물의 과량 발현을 통해 냉해나 한발 등에 대한 저항성이 향상된 벼를 선발하고자 하였다. 잡초성벼인 Bhutan 14Ad로부터 냉해 및 한발 저항성 유전자로 알려진 superoxide dismutase (SOD) cDNA를 분리하고자 mRNA를 분리하고 이 분리된 mRNA를 이용해 reverse transcriptase PCR방법으로 SOD cDNA를 cloning 하였다. 그 결과 2종의 SOD cDNA가 cloning되어 SOD-A, SOD-B로 명명하였다. 이들 cDNA의 염기서열을 결정한 결과 이들은 아미노산 서열 상동성이 88.4%를 나타내었으며, SOD-A는 oryza sativa 계열의 Cu/Zn SOD유전자인 GenBank accession No. L36320와 99.3%로 동일하였으며, SOD-B는 accession No. D01000과 100% 동일하였다. 이들 SOD-A와 SOD-B cDNA를 재배벼인 낙동벼에 형질전환하여 형질전환체 벼를 선발하였으며, 이들 형질전환체 벼의 냉해저항성 및 한발저항성 검정을 통해 저항성이 향상된 형질전환체 벼를 선발하고 있다. Two different cDNA clones for superoxide dismutase (SOD) were isolated from an weedy rice variety (Oryza sativa, cv. Bhutanl4Ad) and were introduced into a cultivated rice variety (Oryza sativa, cv. Nakdong) in order to develop the environmental stress-resistant rice plants. Sequence analysis of the cloned cDNAs indicated that the deduced amino acid sequence of SOD-A is 88.4% identical to that of SOD-B. Furthermore, the nucleotide sequence of SOD-A is 99.3% identical to that of a Cu/Zn SOD gene of Oryza sativa (GenBank accession No. L36320). The nucleotide sequence of SOD-B was identical to that of the previously published SOD gene (Accession No. D01000). A cultivated rice variety, Nakdong-byeo, was transformed with chimenc SOD genes containing a actin promoter of rice and pin2 terminator using a particle bombardment technique. Transformed calli were selected on an selection medium containing phosphinothricin (PPT). Transgenic rice plants were regenerated from the PPT-resistant calli. PCR analysis with genomic DNAs from transgenic plants revealed that transgenes are introduced into rice genome.
Lee, Hae-In,Kim, Jae-Jung,Park, Tae-Sung,Kim, Kyung-A,Lee, Jong-Eun,Cho, Yoon-Shin,Lee, Jong-Young,Han, Bok-Ghee,Lee, Jong-Keuk Korea Genome Organization 2011 Genomics & informatics Vol.9 No.2
Obesity provokes many serious human diseases, including various cardiovascular diseases and diabetes. Body mass index (BMI) is a highly heritable trait that is broadly used to diagnose obesity. To identify genetic loci associated with obesity in Asians, we conducted a genome-wide association study (GWAS) of a population of Korean adults (n=6,742, age 40~60 years) and detected six BMI risk loci (TNR, FAM124B, RGS12, NFE2L3, MC4R and FTO) having p< $1{\times}10^{-5}$. However, in the replication study, only melanocortin 4 receptor gene (MC4R) (rs9946888, p=$4.58{\times}10^{-7}$) was replicated with marginal significance (p<0.05) in the second cohort (n=5,102, age 40~60 years). This study indicates that each locus associated with BMI has very weak genetic effect.
Lee, Jong Keuk,Hong, Soon Jik,Lee, Min Ku,Rhee, Chang Kyu Trans Tech Publications, Ltd. 2006 Diffusion and defect data. SSP. [Pt. B], Solid sta Vol.118 No.-
<P>In this study the nanostructured α-Al2O3 ceramics has been fabricated by the combined application of magnetic pulsed compaction (MPC) and spark plasma sintering (SPS), and their density and hardness properties were investigated. The α-Al2O3 prepared by the combined processes showed an increase of 8.4 % in density, approaching a value close to the theoretical density, a enhancement by 210∼400 Hv in hardness, compared to those for the ones by the MPC or static compaction method followed by a sintering treatment. Its grain size was almost equivalent to or slightly higher than the size of the starting Al2O3 powder, suggesting that the grain growth was remarkably reduced during the MPC and SPS processes.</P>
INFERENCING THE NUMBER OF CLUSTERS WITH BAYESIAN INFORMATION CRITERION
Jong-Keuk Lee,Gyeongyong Heo,Soowhan Han,Young Woon Woo 한국멀티미디어학회 2007 한국멀티미디어학회 국제학술대회 Vol.2007 No.-
K-means is one of the simplest unsupervised learning algorithms that solve the clustering problem. However K-means suffers the basic shortcoming: the number of clusters k has to be known in advance. In this paper, we propose an extension of X-means, which is parameter-free and can estimate the number of clusters using Bayesian Information Criterion (BIC). X-means, however, suffers severe over-fitting when the data does not follow a spherical Gaussian distribution due to the diagonal covariance matrix assumption. We introduce two different versions of algorithm; Modified X-means (MX-means) and Generalized X-means (GX-means), which employ one full covariance matrix for one cluster and can estimate the number of clusters efficiently without severe over-fitting and any additional parameters. The algorithms start with one cluster and try to split one cluster iteratively to maximize the BIC score. The former uses the traditional K-means algorithm to find a set of optimal clusters with current k, the number of clusters, which makes it faster than the latter. However it generates incorrectly estimated centers when the clusters are overlapped. The latter uses EM algorithm to estimate the parameters instead of K-means and generates more stable clusters even when the clusters are overlapped. Experiment with synthetic data shows that the proposed methods can provide a robust estimate of the number of clusters and cluster parameters compared to other top-down algorithms.
Lee, Shin-Hwa,Chang, Hun Soo,Jang, An-Soo,Park, Sung-Woo,Park, Jong Sook,Uh, Soo-Taek,Kim, Yong Hoon,Oh, Bermseok,Lee, Jong-Keuk,Park, Byung-Lae,Shin, Hyung Doo,Park, Choon-Sik,Kimm, Kuchan Published for the Galton Laboratory by Cambridge U 2011 Annals of human genetics Vol.75 No.3
<P>Asthma manifests as TH2-dominant airway inflammation regulated by inducible T-cell kinase (ITK). To investigate associations between genetic variants of the ITK gene and asthma, 31 single-nucleotide polymorphisms (SNPs) were genotyped in 303 normal controls and 498 asthmatics and the two groups were compared using logistic regression models. The functional effects of the ITK promoter SNP were assessed using pGL3 luciferase reporter systems and gel-shift assays. The minor allele-196C>T in the promoter region of the ITK gene was significantly more frequent in asthmatics than in controls. The luciferase activity of the PGL3-ITK-196T allele construct was higher than that of the -196C allele. In the gel-shift assay, -196T double-stranded oligonucleotides bound more strongly to Jurkat cell nuclear protein compared to the -196C double-stranded oligonucleotides. People with the -rare allele 196C>T may be more susceptible to asthma via transcriptional regulation of the ITK gene.</P>
Homogeneous dispersion of TiC nano particles in a cast carbon steel matrix.
Lee, Sang-Hoon,Hong, Sung-Mo,Han, Byoung-Sun,Park, Jin-Ju,Lee, Jong-Keuk,Lee, Jung-Gu,Lee, Min-Ku,Rhee, Chang-Kyu American Scientific Publishers 2010 Journal of nanoscience and nanotechnology Vol.10 No.1
<P>Metal matrix nano-composites (MMNCs) (metal matrix with nano-sized ceramic particles) can be of great significance because of their high performance and thus it would be advantageous to produce as-cast bulk MMNCs. However, it is so difficult to disperse nano-sized ceramic particles uniformly in molten metal. In this study, carbon steel matrix composites with a homogeneous dispersion of TiC nano particles were fabricated by conventional liquid metal casting method. In order to get highly wettable nano-sized TiC ceramic particles, the micro-sized (approximately 10 m) TiC particles were first mechanically milled (MMed) by Cu in a high-energy ball mill machine (MMed TiC/Cu), and then mixed with Sn powders to obtain better wettability, as this lowered the surface tension of the carbon steel melt. According to OM images, an addition of MMed TiC/Cu-Sn mixed powders favorably disperses the TiC nano particles in the carbon steel matrix. SEM and EDS images revealed that spherical particles with several hundreds of nanometers were distributed uniformly in the carbon steel matrix. It was also found that the grain size refinement of the cast matrix is achieved remarkably when TiC nano particles were added due to the fact that TiC nano particles act as nucleation sites during the solidification process.</P>