• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.102-102
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• 2010

수 Tera Watt급의 가속기 및 펄스파워 시스템은 다수의 스위치를 사용하고 있으며, 이와 같은 가속기 및 시스템의 성능은 기체방전 스위치의 성능에 직접적으로 관련되어 있다. 일반적으로 이와 같은 기체방전, 액체방전 고출력 스위치는 다목적으로 많은 연구와 개발에 응용되고 있다. 예를 들어 천둥 펄스전자빔 발생장치는 12개의 Marx gap 및 3개의 100 kV 펄스충전 전기트리거 gap을 가지고 있다. 기체 방전 또는 액체 방전 펄스 충전 갭 스위치의 음극에 펄스 고전압이 인가되면 이로 인하여 음극에서 전자빔이 발생한다. 내부에는 전자빔이 양극과 충돌하는 순간 양극표면에 플라스마가 형성된다. 이와 같은 플라스마 sheath는 축 방향 이극관 안에서 양극충전 에서 음극으로 팽창하면서 전파하며, 또한 거의 동시에 음극표면에도 플라스마가 형성되어 음극에서 양극으로도 팽창하여 전파하게 된다. 이와 같은 펄스충전 고출력 갭 스위치 안에서 발생되는 방전 플라스마의 특성에 관한 갭 breakdown 과정에 대한 특성연구를 한다. 고출력스위치의 특성 조건으로는 방전전압, 방전시간, jitter 등이 있다. 본 연구에서는 최대전압 600 KV, 최대전류 88 KA, 펄스 폭 60 ns의 특성을 가지는 고전압펄스 시스템 '천둥'을 이용하여 방전 챔버에 고전압 펄스를 인가하고 N2와 SF6 혼합기체 종류와 압력에 따른 방전 현상을 연구하였다. 전극은 구리텅스텐 합금재질의 표준전극을 사용하였고, 전극 간격은 20 mm로 고정하였다. 방전 챔버 압력을 100 torr에서 4 기압까지 변화시켜가며 실험을 진행하였고, N2에 대한 SF6의 혼합비율을 0%~100%까지 변화시키며 실험을 진행하였다. 방전 챔버에는 C-dot probe와 B-dot probe를 설치하여 전압과 전류를 측정하였고, C-dot probe 와 B-dot probe는 각각 Northstar사의 10000:1 고전압 probe와 rogowiski coil을 이용하여 시준 하였다. 실험결과 방전전압은 압력이 증가함에 따라 증가하다가 2 기압 이상에서는 완만히 증가하는 경향을 보였고, SF6 혼합비율은 0~10%까지 급격히 증가하고, 그 이상의 혼합비율에서는 완만히 증가하였다. 방전개시시간은 혼합기체 압력에 따라 증가하며 1기압 이상에서는 급격히 증가 하였다. SF6 혼합비율에 따라서는 1 기압 조건까지는 큰 차이가 없었으나 2 기압부터는 급격히 증가하였다. 안정성을 나타내는 jitter는 SF6 100%일 때 가장 컸으나 혼합기체의 변화에 따른 큰 차이는 없었다.

• Clinical and Molecular Hepatology
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• v.24 no.4
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• pp.384-391
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• 2018

Backgrounds/Aims: The objective of our study was to determine the epidemiological, laboratory, and serological characteristics of patients with chronic hepatitis B virus (HBV) infection and normal transaminases. The study also aimed to evaluate liver damage by measuring the liver fibrosis (LF) grade and to identify possible factors associated with the presence of fibrosis. Methods: A retrospective observational study was conducted in patients with chronic HBV infection and classified as inactive carriers or immune-tolerant. Epidemiological variables of age, sex, immigrant, alcohol consumption, and body mass index (BMI), as well as virological variables (HBV DNA) and transaminase level were collected throughout the follow-up. The LF grade was evaluated by transient elastography. The cutoff value for significant fibrosis (SF) was liver stiffness ${\geq}7.9kPa$. Results: A total of 214 patients were included in the analysis, and 62% of them had a BMI ${\geq}25kg/m^2$. During follow-up, 4% of patients showed transaminase elevation (<1.5 times normal). Most patients had a viral DNA level <2,000 IU/mL (83%). Data on LF were available in 160 patients; of these, 14% had SF, 9% F3, and 6% F4. The variables associated with the presence of SF were transaminase alteration during follow-up, as 23% of patients with SF had elevated transaminases versus 3% of patients without SF (P<0.005), and BMI, as the vast majority of patients with SF (88%) had a BMI ${\geq}25kg/m^2$ versus 56% of patients without SF (P<0.05). Conclusions: In patients with chronic HBV infection and normal transaminases, liver damage does not seem to be related to DNA levels, alcohol consumption, or immigrant status. SF seems to be associated with transaminase alteration during follow-up and elevated BMI. It is therefore recommended to measure LF grade with validated non-invasive methods in such patients.

• Journal of radiological science and technology
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• v.37 no.2
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• pp.109-116
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• 2014

Many studies have suggested that in the era of Drug-Eluting Stents(DES) are one of the causes of In-Stent Restenosis(ISR) of Stent Fracture(SF). The present study sought to evaluate clinical characteristics of patients with stent fracture after successful DES implantation. The 4,701 patients were selected for analysis who underwent a follow-up coronary angiography irrespective of ischemic symptoms. The overall incidence of SF was 32 patients(male:female=19:13, Av. age $62.44{\pm}9.8$year, 0.68%). Fractures of Sirolimus-Eluting Stents(SES), Paclitaxel-Eluting Stents(PES), Biolimus A9-Eluting Stents(BES), Everolimus-Eluting Etents(EES), Endothelial Progenitor Cell Capture Stent(EPC) and Zotarolimus-Eluting Stents(ZES) are accounted for 19(59.4%), 9(28.1%), 2(6.3%), 1(3.1%), 1(3.1%) and 0(0%) respectively. SF developed in the left Anterior Dscending(LAD) artery in 16 patients(50%) and in complex(type B2, C) lesions in 25 patients(69.4%). Ten patients were treated with heterogenous DES, the rest being treated with either homogenous DES(3 patients), plain old balloon angioplasty(3 patients), or conservative medical treatment(17 patients). None of the patients with SF suffered from cardiac death during a follow-up period of $32.9{\pm}12.4$ months. The overall rate of DES fracture over up to 3.7 years of follow-up was 0.68% with higher incidence in SES than in PES. SF frequently occurred in the LAD artery and in complex lesions. Of the patients with SF, coronary intervention was performed only when the binary restenosis lesion was significant. During the follow-up, patients with SF have continued on combination antiplatelet therapy. There is a very low rate of major adverse cardiac events(post-detection of SF), especially cardiac death associated with SF.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.272-279
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• 2021

Two genes encoding probable α-ʟ-arabinofuranosidase (E.C. 3.2.1.55) isozymes (ABFs) with 92.3% amino acid sequence identity, ABF51A and ABF51B, were found from chromosomes 3 and 5 of Saccharomycopsis fibuligera KJJ81, an amylolytic yeast isolated from Korean wheat-based nuruk, respectively. Each open reading frame consists of 1,551 nucleotides and encodes a protein of 517 amino acids with the molecular mass of approximately 59 kDa. These isozymes share approximately 49% amino acid sequence identity with eukaryotic ABFs from filamentous fungi. The corresponding genes were cloned, functionally expressed, and purified from Escherichia coli. SfABF51A and SfABF51B showed the highest activities on p-nitrophenyl arabinofuranoside at 40~45℃ and pH 7.0 in sodium phosphate buffer and at 50℃ and pH 6.0 in sodium acetate buffer, respectively. These exoacting enzymes belonging to the glycoside hydrolase (GH) family 51 could hydrolyze arabinoxylo-oligosaccharides (AXOS) and arabino-oligosaccharides (AOS) to produce only ʟ-arabinose, whereas they could hardly degrade any polymeric substrates including arabinans and arabinoxylans. The detailed product analyses revealed that both SfABF51 isozymes can catalyze the versatile hydrolysis of α-(1,2)- and α-(1,3)-ʟ-arabinofuranosidic linkages of AXOS, and α-(1,2)-, α-(1,3)-, and α-(1,5)-linkages of linear and branched AOS. On the contrary, they have much lower activity against the α-(1,2)- and α-(1,3)-double-substituted substrates than the single-substituted ones. These hydrolases could potentially play important roles in the degradation and utilization of hemicellulosic biomass by S. fibuligera.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.3
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• pp.61-74
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• 2010

Objectives : The purpose of this study is to find out the effects of flexion-distraction technique on low back pain. Methods : The 40 patients were divided into 2 groups: group a was treated except flexion-distraction technique and group B was treated with flexion-distraction technique. Both groups were treated with acupuncture treatment, physical therapy and manipulation. Patients were evaluated by McGill pain questionnaire-short form(SF-MPQ), visual analogue scale(VAS), Oswestry disability index(ODI) and pain disability index(PDI). Results : 1. Both Groups were significantly decreased in VAS and ODI after 3 weeks of treatment. 2. Group B compared with Group A was significantly decreased in SF-MPQ, VAS, ODI and PDI after 3 weeks of treatment. Conclusions : We found out that flexion-distraction technique is considered to be effective and useful on low back pain.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.2
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• pp.36-46
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• 1995

In this paper, fatigue crack propagation behaviors were investigated experimentally for the materials, carbon steel forgings (SF45A, SF50A, SF60A) which are used in the marine propeller shaft. The results obtained are as follows: The number of cycles required to grow crack length 1.30mm from microcrack initiation was about 60% of the total fatigue life. Fatigue crack propagation rate was expressed by the equation d(2a)/dN_B 2a/$N_f$ and the result was agreed well with the experimented data. And the equation d(2a)/dN=$C{\sigma}_a^m(2a)^n$ was evaluated also. Obtained material property m and n are 3~5 and 1-1.5 respectably, and the result was reasonably agreed to the data obtained from experiments.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.2
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• pp.69-80
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• 1975

Relationships between yield and various nitrogen efficiencies, between efficiencies and between efficiency and nitrogen uptake amount of rice plant were proposed and tested using data from N.P.K simple trials about 30 to 50 locations, for three years. Established relationships are well in accordance with experimental results by showing highly significant correlations between them. The overall indications are that high yielding capacity of fields with fertilizer application, depends primarily on high fertilizer nitrogen uptake by increasing fertilizer use efficiency (Eu), secondly the efficiency (Ef) of absorbed fertilizer nitrogen (Nf) and fertilization efficiency (Fe) and also depends much on nitrogen efficiency for grain yield (E) to great extend and that the efficiency (Es) of soil nitrogen (Ns) contributes to E more than Ef does. All nitrogen efficiencies are negatively correlated with the uptake amount of corresponding nitrogen and counterpart efficiency. Es and Ef could be determined firstly by difference method and secondly E versus Cs (Cs=Ns/Ns+Nf) plotting and thirdly E-Cs plotting with labelled fertilizermethod using the equation E=Es Cs+B where B=Ef Cf but a constant under the given condition and at last Y-Ns plotting with labelled fertilizer using Eq Y=$Es{\cdot}Ns+B$ where B=$Ef{\cdot}Nf$. Es which seems not much variable from field to field is mostly greater (about 80% of tested fields) than Ef which is much variable and depends much on fertilizer form. The relationships tested and well agreed are as follows: 1. Y=$Es{\cdot}Ns+Ef{\cdot}Nf$ (Y is yield) 2. E=$Es{\cdot}Cs+Ef{\cdot}Cf$ where Cf=Nf/Nf+Ns 3. E=b-aN where E=E, Es or Ef and N=N, Ns or Nf respectively, (E=Y/N, N=Nf+Ns), b is theoretical maximum under the given system and a is tangent at N=O of the curve, Y=EN. 4. Fe=Ef Eu and Se=$Es{\cdot}Eu$ where Se is efficiency of soil available nitrogen. 5. E=$(Se{\cdot}Cs+Fe{\cdot}Cf)/Eu$ 6. Y=$Es{\cdot}Eu{\cdot}Sf+Ef{\cdot}Eu{\cdot}Fn$or Y=$Es{\cdot}Eu{\cdot}Ea{\cdot}Sn+Ef{\cdot}Eu{\cdot}Fn $where Sf=$Ea{\cdot}Sn$, Ea is soil available nitrogen equivalent to fertilizer(Sf) divided by total soil nitrogen (Sn).

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.4
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• pp.1034-1038
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• 2007

To examine the difference of health-related quality of life (QoL) of obese patients between before and after treatment of Korean traditional medicine. This study was assessed in 18 obese-women (age 29.72${\pm}$7.38) treated by acupuncture and herbal medicine using SF-36 quality of life questionnaire between January and July 2006, a 36 item instrument yielding 8 dimensions (Social functioning, Role limitation-Physical, Role limitation-Emotion, Mental health, Vitality, Bodily pain, and General health) and a total score. Their weight was measured by Inbody 3.0 (Biospace co. Korea). QoL and body composition was assessed twice at baseline (B) and 4 weeks after treatment. Auricular acupuncture and electrical needle stimulation to abdomen, thigh, and arm fat was used twice a week and complex herb formula was prescribed according to their constitution and symptoms for 4 weeks. Herb medication was taken 2 times a day. Respective variables were analyzed with Wilcoxon signed ranks test and the level set for statistical significance was p <0.05. The mean of the body weight (P=0.000;B64,68${\pm}$6.86, 4 WKs 60.47${\pm}$5.69), fat percentage (P=0.000;B33.14${\pm}$4.86, 4 WKs 30.16${\pm}$5.34), body mass index (P=0.000;B25.18${\pm}$2.44, 4 WKs 23.46${\pm}$2.09) and fat weight (P=0.000;B21.66${\pm}$5.06, 4 WKs 18.41${\pm}$4.57) of some obese patients decreased significantly between before and after treatment for 4 weeks. Physical functioning (P=0.48;B27.06${\pm}$3.17, 4 WKs 28.00${\pm}$1.71), Mental health (P=0.01 ;B18.83${\pm}$5.25, 4 WKs 22.00${\pm}$3.73), Vitality (P=0.028;B13.89${\pm}$3.03, 4 WKs 15.44${\pm}$2.53), Bodily pain (P=.0014;B8.84${\pm}$1.75, 4 WKs 10.15${\pm}$1.78), and the total scores (P=0.001;B104.99${\pm}$12.60, 4 WKs 114.58${\pm}$11.11) of SF-36 were increased significantly after treatments. These data show some differences in QoL and BMI between before and after treatment on obesity and suggest that the treatment with acupuncture and herbal medicine have a positive impact on several domains of QoL of some obese patients. Further randomized clinical trials (RCTs) including follow-up are needed to examine whether acupuncture and herb medicine have a positive effect on QoL of treatment group compared with control group.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.312-322
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• 2006

The objectives of this study were to evaluate the effect of surface roughness on the surface color and translucency of the composite resins. Two composite resins (Esthet-X, Dentsply, Milford, USA and Charisma, Kulzer, Domagen, Germany) were used to investigate the surface color. Charisma was used to investigate the translucency. 40 disc samples (diameter: 8 mm, thickness: 5 mm) were made by each product to measure the surface color. Polymerized each sample's one side was treated by Sof-Lex finishing and polishing system (Group C, M, F, SF). 40 disc samples (diameter: 6 mm, thickness: 1 mm) were prepared to measure the opacity. 1 mm samples were ground one side with #600, #1000, #1500 and #2000 sandpapers. CIE $L^{*}a^{*}b^{*}$ values of each 5 mm thickness samples, and XYZ values of 1 mm thickness samples on the white and black background were measured with spectrophotometer (Spectrolino, GretagMacbeth, Regensdorf, Switzerland). Mean surface roughness (Ra) of all samples before and after surface treatment was measured using the Surface Roughness Tester SJ-301 (Mytutoyo, Tokyo, Japan). Regardless of type and shade of the composite resin, $L^{*}$ values measured in group C were higher than others (p < 0.05), and $L^{*}$ value decreased as the Ra value decreased except B3 shade of Esthet-X. But there were no significant difference in $a^{*}$ values among groups. In control group and SF, highest $b^{*}$ values were measured (p < 0.05), except B1 shade of Esthet-X. Contrast ratio decreased as the Ra value decreased (p < 0.05). With the above results, difference of surface roughness has influence on surface color and translucency of dental composite resins.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.165-171
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• 2006

ERM proteins transfer the methyl group to $A_{2058}$ in 23S rRNA to confer the resistance to MLS (macrolide-lincosamide-streptogramin B) antibiotics on microorganism ranging from antibiotic producers to pathogens. To define the functional role of peptide segment encompassing amino acid residues 1 to 25 in NTER (N-terminal end region) of ErmSF, one of the ERM proteins, DNA fragment encoding mutant protein deprived of that peptide was cloned and overexpressed in E. coli to obtain a purified soluble form protein to the apparent homogeneity in the yield of 12.65 mg per liter of culture. The in vitro activity of mutant protein was found to be 85% compared to wild type ErmSF, suggesting that this peptide interact with substrate to affect the enzyme activity. This diminished activity of mutant protein caused the delayed expression of antibiotic resistance in vivo, that at fIrst cells expressing mutant protein showed the retarded growth due to the antibiotic action but with time cells inhibited by antibiotic gradually recovered the viability to exert the resistance to the same extent as those with wild type protein.