Strain Distributions of Plane-Strained and Simple-Sheared Al–Mg Alloy

Hyeon‑Woo Son,Jae‑Cheol Lee,Hyun Soon Park,Soong‑Keun Hyun 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

Strain distribution in plane-strained (rolling) and simple-sheared (torsion) Al–Mg alloy has been estimated using both X-rayline profile analysis and electron backscatter technique. The strain analyses under unified texture distribution by orientationrotation showed that torsion has relatively homogeneous strain distribution regardless of texture component in contrast toinhomogeneous strain in rolling. In addition, annealing texture of torsion has more random texture than inhomogeneousrolling texture. Lower texture difference index in annealed torsion specimens suggest homogeneous strain distribution insimple shear has a higher resistance to strain-induced boundary migration, which has been known to be main reason forstrong development of ND||⟨100⟩ component during annealing of rolled Al sheet.

고객만족모형의 기대 딜레마 : 확산과 기대불일치의 통합모형 A Unified Model of Expectancy Disconfirmation and Diffusion

박상준,김현철 한국경영과학회 2003 한국경영과학회지 Vol.28 No.2

Many forms try to enhance the customer satisfaction, because they believe that higher customer satisfaction leads to superior returns. According to expectancy disconfirmation model, consumers judge the satisfaction in comparison with their expectations about the product performance. If the performance is above the expectations, increase in satisfaction is expected. If the performance is below the expectation, decrease in satisfaction is expected. This explanation contradicts out beliefs that higher expectation leads to consumer's choices. To address the contradiction, this paper present a unified model which combines the expectancy disconfirmation model with the well-known diffusion model. The unified model shows that the expectation can increase the choice even if the expectation decreases the satisfaction.

METRx™ 기구를 이용한 후방 경추부 추궁추간공 제거술의 예비 결과

박형천,윤승환,박종운,하윤,현동근,김은영,박현선,임대철 대한척추신경외과학회 2004 Neurospine Vol.1 No.1

Objectives: Posterior cervical microscopic laminoforaminotomy has been a preferred procedure for a posterolateral cervical disc or foraminal stenosis. However, neckpain from wide skin incision and muscle injury are some of disadvantages. The authors performed cervical microscopic laminoforaminotomy with METRx™ tubular dilator system and were compared the results with classical cervical microscopic foraminotomy. Methods: Six patients underwent posterior cervical microscopic laminoforaminotomy using the METRx™ during 6 months. We have selected 10 patients from our institution as a comparison group. Preoperative and postoperative pain score composed of the radicular and neck component was examined and disability score also recorded. Diameters and lengths of laminoforaminotomy on the postoperative CT also were compared with two methods Results: Postoperative pain scores to the radiculopathies were not different but postoperative pain scores to the neckpain on the follow up periods were significantly different. The average vertical and transverse diameters of the laminoforaminotomy defect on the postoperative CT scans were not different between two groups. Average hospital stay of the classical methods was 8.8±7.5 days comparison with 4.5±0.54days of new procedure. Conclusions: Posterior cervical microscopic laminoforaminotomy with METRx™ systems seems to provide similar decompression and clinical results as classical methods compared to classical methods and shows superior results for postoperative neckpain and hospital stays.

充塡複極槽에 의한 黃酸구리및窒酸카드뮴 廢液의 電解處理 (Ⅰ)

朴勝祚,崔鍾楨,張哲鉉 동아대학교 환경문제연구소 1986 硏究報告 Vol.9 No.1

The objective of this study is to review charateristics of mono and bipolar electrolytic cell in various packing materials, applied valtages and material size. In this paper, we were investigated in the case of the electrolysis of CuSO₄ and Cd(NO₃)₂ solution under different conditions. When the electrolysis was carried out in the cell packed activated carbon from coconut shell, the reaction rate and particile size were increased, the reaction rate increased and metal deposited on packed material. The electrolytic treatment efficiency was over 98% when electrolysis were carried out at 20 voltages during 3 hours.

Inhibition of oxidative stress induced‑cytotoxicity by coptisine in V79‑4 Chinese hamster lung fibroblasts through the induction of Nrf‑2 mediated HO‑1 expression

Hyeon‑Gyun Jo,Cheol Park,이혜숙,Gi‑Young Kim,Young‑Sam Keum,Jin Won Hyun,Taeg Kyu Kwon,Yung Hyun Choi,Su Hyun Hong 한국유전학회 2021 Genes & Genomics Vol.43 No.1

Background Coptisine is a natural alkaloid compound and is known to have multiple benefcial efects including antioxidant activity. However, whether it can protect lung fbroblasts from oxidative damage has not been studied yet. Objectives To investigate the potential inhibitory efect of coptisine against oxidative stress in V79-4 lung fbroblast cells. Methods V79-4 cells were treated with H2O2 (1 mM) in the presence or absence of coptisine (50 µg/ml), N-acetyl cysteine (NAC, 10 mM) or zinc protoporphyrin IX (ZnPP, 10 µM) for the indicated times. The alleviating efects of coptisine on cytotoxicity, cell cycle arrest, apoptosis, reactive oxygen species (ROS) production, DNA damage, mitochondrial dynamics, and inhibition of ATP production against H2O2 were investigated. Western blot analysis was used to analyze the expression levels of specifc proteins. Results Coptisine inhibited H2O2-induced cytotoxicity and DNA damage by blocking abnormal ROS generation. H2O2 treatment caused cell cycle arrest at the G2/M phase accompanied by increased expression of cyclin-dependent kinase (Cdk) inhibitor p21WAF1/CIP1 and decreased expression of cyclin B1 and cyclin A. However, these efects were attenuated in the presence of coptisine or NAC. Coptisine also prevented apoptosis by decreasing the rate of Bax/Bcl-2 expression in H2O2-stimulated cells and suppressing the loss of mitochondrial membrane potential and the cytosolic release of cytochrome c. In addition, the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was markedly promoted by coptisine in the presence of H2O2. However, zinc protoporphyrin IX, a potent inhibitor of HO-1, attenuated the ROS scavenging and anti-apoptotic efects of coptisine. Conclusions Based on current data, we suggest that coptisine can be used as a potential treatment for oxidative stress-related lung disease.

휘발성유기화합물(VOCs)의 변이원성 검정

박종천,이용탁,송현철,이우범 國立麗水大學校 環境問題硏究所 2004 環境硏究論文集 Vol.6 No.-

The mutagenicity of six kinds of VOCs(benzene, m.p-xylene, chloroform, toluene, methylethylketone, 1,2-dichloroethane) detected in high concentration and frequency in Kwangyang Bay was investigated. VOCs are water-insoluble and volatile. Therefore, when they are tested by the classical Ames test in the assay of mutagenicity, there may be experimental errors. To overcome this limitation, modified Ames test was used to assay mutagenicity of VOCs. By this modified Ames test, we could obtain much more satisfactory results. Even at extremely low concentration(0.0001㎍/㎖). bezene, m,p-xylene, and methylethylketone showed a weak mutagenicity. When S-9 mixture is added in the assay system, all tested VOCs except methylethylketone showed mutagenicity. When Salmonclla typhimurium TA 98 and Salmonella typhimurium TA 100 are exposed to VOCs of high concentration(100㎍/㎖). the number of colony decreased irrespective of the S-9 mixture treatment. It seem to be that the decrement results from the toxic effect of high concentration of VOCs.

3차원 전극(Bipolar Packed Bed Electrode)을 이용한 호소수 처리(II)

장철현,박상우,최창수 한국환경과학회 2002 한국환경과학회지 Vol.11 No.4

This study was to analyze the right or wrong of gray-water treatment by applying BPBE electrode cell to the effluence water in the terminal disposal plant of sewage. The results were as follows : The best result was obtained with applied voltage 40V and detention time 6 minutes for the BPBE electrode cell which has the graphite-plate in main electro-de, packing coconut activated carbon. The elimination rate of COD of Al-plate was higher than that of graphite-plate in main electrode. The result of electrolysis for 3 hour in parallel circuit showed the using possibility of gray-water according to each elimination rate : COD 59%, T-N 69 %, T-P 69%. The BPBE electrode cell with the Al-plate in main electrode made the best effect for the elimination of algae in lake water and algae were not occurred in electrolytic water.

Cryptococcal 뇌막염이 병발된 수막 암종증 1예

안병철,고지영,이현옥,최진영,권오상,박용욱 중앙대부설한국의과학연구소 1990 한국의과학 Vol.22 No.1

당근의 고체배양에서 체세포발생중 세포내 생화학적 변화

차현철,박희승 단국대학교 1996 論文集 Vol.30 No.-

Some important macromolecules in The cells of embryogenic(E-) and non-embryogenic(NE-) calli of car-rot(Daucus carata cv. Daepooong-ochon) were quantitatively measured periodically during culture of 5 weeks on solid medium. The transfer of the callus from the MS medium with phytohormones to phytohormone-free medium induced embyroid formation at 10 days culture. And the condents of some solutes were changed dramatically at embryoid forming time. In other words, free amino acid and soluble protein contents were reached to maximum at 8th day after culture in E-callus cells. On the contrarily reducing suger content was decreased at early time leading to minimum value at 8th day on both calli imspite of the double value in E-callus comparing with Ne-callus at that time. The higher con-tents of sugars in E-callus may contributed by energy budgets needed to initiate embryoid formation. The activity of peroxidase and its specific activity was higher in E-callus than NE-callus at embryoid forming time and DNA content was steadly increased during that time. RNA content also was increased to reach peak at 16th day in NE-callus, at 24th day in E-callus. After that, the content was decreased to the original levels. In conclusion, the metabolism in the parenchyma cells may be changed dramatically in order to initiate the embryoid formation.

폴라로그래피법에 따른 各種 金屬의 電解還元 反應機構의 解析

張哲鉉,朴勝祚 大田工業大學 1992 한밭대학교 논문집 Vol.9 No.1

Using the current-potential equation of the following two cases of E-E mechanism based on an expanding electrode model, were studied the reduction mechanisms of various metals. ◁그림 삽입▷ (원문을 참조하세요) And the logarithmic analysis of the average current-potential curves are carried out in the case of single wave being obtained. The results of this study showed that Lead(Ⅱ) is the case of both charge transfer steps being reversible(R-R CASE), Cadmium(Ⅱ) and Manganese(Ⅱ) are the case of first charge charge trasfer step being reversible while the second step being irrevers- ible(R-I CASE) and Hickel(Ⅱ) rlnd Cobalt(Ⅱ) are case of the first charge transfer step being irreversible and the second charge transfer step being reversible(I-R CASE ).