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      • KCI등재SCIESCOPUS

        Probe Beam Current Enhancement in a Microcolumn using Bias Potential

        Dae-Wook,Kim,Young,Chul,Kim,Dae-Yong,Kim,Ho-Seob,Kim,Myeong-Heon,Seol,Sang-Kook,Choi,Seungjoon,Ahn 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2

        For the practical application of a microcolumn as a next generation lithography system with high throughput capability, a high probe beam current is required. Microcolumn operation with a negatively biased accelerator has been tried to achieve a high probe beam current, and the results will be discussed. When a negative bias voltage is applied to the accelerator, the beam divergence is reduced until beam crossover occurs, and the measured probe beam current is enhanced by around 1 order of magnitude at a specic bias voltage. Also, the magnitude of the bias voltage at which the highest probe beam current is observed varies linearly with the electron beam energy. The operation of a microcolumn with a bias voltage has been studied in detail and will be discussed

      • Clinicopathologic and Prognostic Significance of Multiple Hormone Expression in Pancreatic Neuroendocrine Tumors

        Kim,,Joo,Young,Kim,,Min-Sun,Kim,,Ki-Suk,Song,,Ki-Byung,Lee,,Seung,Hun,Hwang,,Dae,Wook,Kim,,Kyu-pyo,Kim,,Hyoung,Jung,Yu,,Eunsil,Kim,,Song,Cheol,Jang,,Hyeung-Jin,Hong,,Seung-Mo Wolters Kluwer Health, Inc. All rights reserved. 2015 The American journal of surgical pathology Vol.39 No.5

        Pancreatic neuroendocrine tumors (PanNETs) produce variable peptide hormones. The expression status of some hormones has been linked to the biological and clinical behaviors of PanNETs. A total of 226 surgically resected PanNETs were selected. Immunolabeling for peptide hormones was compared with various clinicopathologic factors, including patient survival. Expression of insulin, glucagon-like peptide 1, glucagon, gastrin, somatostatin, and serotonin were observed in 56 (24.8%), 41 (18.1%), 25 (11.1%), 5 (2.2%), 5 (2.2%), and 4 (1.8%) cases, respectively. Expression of 1, 2, and 3 hormones was noted in 70 (31.0%), 28 (12.4%), and 3 (1.3%) cases, respectively; 125 cases (55.3%) were negative for all hormones. PanNETs with insulin and glucagon-like peptide 1 expression were associated with a lower grade, smaller size, lower pT and pN classifications, absence of lymphovascular invasion, and lymph node metastasis and had better survival by univariate analysis, whereas PanNETs with gastrin expression were associated with a higher grade, larger size, higher pT and pN classifications, presence of lymphovascular invasion, and lymph node metastasis and had worse survival. Gastrin expression, increased age, and tumor grade were negative prognostic factors in multivariate analysis. As the number of hormones expressed increased, the survival rate of PanNET patients increased. In summary, PanNET patients showing insulin or glucagon-like peptide 1 expression and increased numbers of expressed hormones had a better survival outcome by univariate analysis, whereas gastrin expression was a negative prognostic indicator in surgically resected PanNET patients.

      • KCI등재

        Loss of Progesterone Receptor Expression Is an Early Tumorigenesis Event Associated with Tumor Progression and Shorter Survival in Pancreatic Neuroendocrine Tumor Patients

        Kim,,Sung,Joo,An,,Soyeon,Lee,,Jae,Hoon,Kim,,Joo,Young,Song,,Ki-Byung,Hwang,,Dae,Wook,Kim,,Song,Cheol,Yu,,Eunsil,Hong,,Seung-Mo 대한병리학회 2017 Journal of Pathology and Translational Medicine Vol.51 No.4

        <P><B>Background</B></P><P>Pancreatic neuroendocrine tumors (PanNETs) are the second most common pancreatic neoplasms and there is no well-elucidated biomarker to stratify their detection and prognosis. Previous studies have reported that progesterone receptor (PR) expression status was associated with poorer survival in PanNET patients.</P><P><B>Methods</B></P><P>To validate previous studies, PR protein expression was assessed in 21 neuroendocrine microadenomas and 277 PanNETs and compared with clinicopathologic factors including patient survival.</P><P><B>Results</B></P><P>PR expression was gradually decreased from normal islets (49/49 cases, 100%) to neuroendocrine microadenoma (14/21, 66.6%) to PanNETs (60/277, 21.3%; p < .001). PanNETs with loss of PR expression were associated with increased tumor size (p < .001), World Health Organization grade (p = .001), pT classification (p < .001), perineural invasion (p = .028), lymph node metastasis (p = .004), activation of alternative lengthening of telomeres (p = .005), other peptide hormonal expression (p < .001) and ATRX/DAXX expression (p = .015). PanNET patients with loss of PR expression (5-year survival rate, 64.1%) had significantly poorer recurrence-free survival outcomes than those with intact PR expression (90%) by univariate (p = .012) but not multivariate analyses. Similarly, PanNET patients with PR expression loss (5-year survival rate, 76%) had significantly poorer overall survival by univariate (p = .015) but not multivariate analyses.</P><P><B>Conclusions</B></P><P>Loss of PR expression was noted in neuroendocrine microadenomas and was observed in the majority of PanNETs. This was associated with increased grade, tumor size, and advanced pT and pN classification; and was correlated with decreased patient survival time by univariate but not multivariate analyses. Loss of PR expression can provide additional information on shorter disease-free survival in PanNET patients.</P>

      • S-127 : The Role of Chitosan Nanoparticles in Delivery of Photosensitizer to Cholangiocarcinoma Cells

        ( Dae Hwan Kang ), ( Hyung Wook Kim ), ( Dae Gon Ryu ), ( Tae Sung Kim ) 대한내과학회 2015 대한내과학회 추계학술대회 Vol.2015 No.1

        Purpose: Chitosan is a natural, biocompatible, and biodegradable polymer with immuno-positive features and anticancer activities. Due to its cationic properties, Chitosan is used to incorporate anionic drugs e.g. Ce6 via transmucosal or oral delivery. In the study, Ce6-incorporated nanoparticles were created using water-soluble chitosan and its physicochemical properties and photodynamic potentials were studied against cholangiocarcinoma cells in vitro and in vivo settings. Methods: Water-soluble chitosan were obtained from Kittolife Co. Korea and Ce6 from Frontier Sci. Co. Ltd. USA. Ce6-incorporated nanoparticles using chitosan was prepared by thawing 100 mg of chitosan in 10 mL of deionized water. After the sonication of chitosan solution using bar-type ultrasonicator, 5-20 mg of Ce6 in 0.5 mL DMSO was added.The solution was dialyzed against water to remove any organic solvents and free drugs. Results: The higher Ce6 contents in the nanoparticles induced increased particle size and decreased zetapotential. When Ce6-incorporated nanoparticles were treated in HuCC-T1 cholangiocarcinoma cells with irradiation, it enhanced delivery of Ce6 to HuCC-T1 cells and raised ROS levels in tumor cells compared to Ce6 alone. Moreover, Photo-induced toxicity against cholangiocarcinoma cells were increased compared to Ce6 alone as well. In the in and ex vivo studies using cholangiocarcinoma-bearing mice and porcine bile duct slice, significantly better delivery was demonstrated with Ce6 comprising nanoparticles. Conclusions: ChitoCe6 nanoparticles can enhance cellular uptake of Ce6, phototoxicity, and ROS generation in HuCC-T1 cholangiocarcinoma cells compared to Ce6 alone. It has also shown improved delivery performance in both in and ex vivo settings

      • KCI등재

        초소형 전자 렌즈의 전자 광학적 분석

        김호섭,김대욱,김영철,최상국,김대용 한국광학회 2003 한국광학회지 Vol.14 No.2

        FCM(Fast moving least square reproducing kernel point collocation method) 방식의 simulatien tool을 이용하여 전기장으로 구동되는 초소형 전자 렌즈의 구동 특성을 조사·분석하였다. Einzel 렌즈의 retarding mode와 accelerating mode구동에서 포텐셜 분포는 유사하지만, electric field strength는 서로 다른 방향을 갖게 되어 서로 다른 형태의 전자 궤적을 보인다 동일한 working distance에서 accelerating mode로 구동되는 전자렌즈는 retarding mode로 구동되는 경우보다 매우 높은 focusing 전압을 필요로 한다. The analysis of operation characteristics of a miniaturized electrostatic electron lens system called an Einzel lens was performed using a simulation tool of FCM method, The potential distributions of Einzel lenses operated both in retarding and accelerating modes show similar features. But the electric fields determined from the potential distributions show opposite directions, which results in different features in the electron beam trajectory in each mode of operation. For the same working distance, focusing voltage in the accelerating mode is higher than that in the retarding mode.

      • KCI등재

        Restructuring and Efficiency

        Dae-Wook Kim(김대욱), Jongho Kim(김종호), Bongchan Ha(하봉찬) 한국법경제학회 2008 법경제학연구 Vol.5 No.1

        구조개편이 이루어진 전력시장의 시장지배력을 분석한 연구는 그 동안 많이 이루어져 왔다. 그러나 구조개편이 과연 효율성의 증대를 가져왔는지에 관한 실증적인 연구는 상대적으로 미진한 실정이다. 본 연구는 구조개편이 이루어진 한국 전력산업의 패널자료를 사용하여 구조개편이 발전회사의 효율성에 미친 영향을 분석하고자 한다. 투입요소와 발전량 사이의 내생생 문제를 제어하기 위하여 Levinsohn and Petrin(2003)의 기법을 사용하여 분석한 결과에 따르면, 발전자회사 분할 이후에 6.6%의 효율성 증대가 이루어졌으나 남동발전의 매각 이 중단된 이후에는 이러한 효율성 증대효과가 사라진 것으로 나타났다. Despite the prevalent analysis on the exercise of market power in the competitive generation sector, only few studies measuring efficiency gains of restructuring exist. In this paper, we estimate the empirical effects of restructuring on technical efficiency using data on the restructured Korean coal generation plants from 1990 to 2005. The estimation results from the Levinsohn and Petrin (2003), to account for the simultaneous issues between input and output decision, suggest that there exist 6.6% productivity gains associated with restructuring activities in 2001. This implies that the Korean Electric Power Company got rid of inefficiencies only after they divided the generation sector into six subsidiary firms.

      • KCI등재후보SCOPUS

        Effect of fabrication processes on mechanical properties of glass fiber reinforced polymer composites for 49 meter (160 foot) recreational yachts

        Dae-Wook,Kim,Daniel,John,Hennigan,Kevin,Daniel,Beavers 대한조선학회 2010 International Journal of Naval Architecture and Oc Vol.2 No.1

        Polymer composite materials offer high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions that appeal to the marine industry. The advantages of composite construction have led to their incorporation in U.S. yacht hull structures over 46 meters (150 feet) in length. In order to construct even larger hull structures, higher quality composites with lower cost production techniques need to be developed. In this study, the effect of composite hull fabrication processes on mechanical properties of glass fiber reinforced plastic (GFRP) composites is presented. Fabrication techniques investigated during this study are hand lay-up (HL), vacuum infusion (VI)), and hybrid (HL+VI) processes. Mechanical property testing includes: tensile, compressive, and ignition loss sample analysis. Results demonstrate that the vacuum pressure implemented during composite fabrication has an effect on mechanical properties. The VI processed GFRP yields improved mechanical properties in tension/compression strengths and tensile modulus. The hybrid GFRP composites, however, failed in a sequential manor, due to dissimilar failure modes in the HL and VI processed sides. Fractography analysis was conducted to validate the mechanical property testing results.

      • Phenolic phytochemical displaying SARS-CoV papain-like protease inhibition from the seeds of <i>Psoralea corylifolia</i>

        Kim,,Dae,Wook,Seo,,Kyung,Hye,Curtis-Long,,Marcus,J.,Oh,,Kyeong,Yeol,Oh,,Jong-Won,Cho,,Jung,Keun,Lee,,Kon,Ho,Park,,Ki,Hun Informa UK Ltd. 2014 Journal of enzyme inhibition and medicinal chemist Vol.29 No.1

        <P>Severe acute respiratory syndrome coronavirus (SARS-CoV) papain-like protease (PLpro) is a key enzyme that plays an important role in SARS virus replication. The ethanol extract of the seeds of <I>Psoralea corylifolia</I> showed high activity against the SARS-CoV PLpro with an IC<SUB>50</SUB> of value of 15 µg/ml. Due to its potency, subsequent bioactivity-guided fractionation of the ethanol extract led to six aromatic compounds (<B>1-6</B>), which were identified as bavachinin (<B>1</B>), neobavaisoflavone (<B>2</B>), isobavachalcone (<B>3</B>), 4′-O-methylbavachalcone (<B>4</B>), psoralidin (<B>5</B>) and corylifol A (<B>6</B>). All isolated flavonoids (<B>1-6</B>) inhibited PLpro in a dose-dependent manner with IC<SUB>50</SUB> ranging between 4.2 and 38.4 µM. Lineweaver-Burk and Dixon plots and their secondary replots indicated that inhibitors (<B>1-6</B>) were mixed inhibitors of PLpro. The analysis of <I>K</I><SUB>I</SUB> and <I>K</I><SUB>IS</SUB> values proved that the two most promising compounds (<B>3</B> and <B>5</B>) had reversible mixed type I mechanisms.</P>

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