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      • KCI등재

        Effect of Intermediate Metal on the Methanol Gas Sensitivity of ITO Thin Films

        이학민,허성보,공영민,김대일 한국진공학회 2011 Applied Science and Convergence Technology Vol.20 No.3

        ITO thin films and gold (Au), copper (Cu) and nickel (Ni) intermediate ITO multilayer (ITO/Au/ITO, ITO/Cu/ITO, ITO/Ni/ITO) films were deposited on glass substrates with a reactive radio frequency and direct current magnetron sputtering system and then the effect of intermediate metal layer and annealing temperature on the methanol gas sensitivity of ITO films were investigated. Although both ITO and ITO/metal/ITO (IMI) film sensors have the same total thickness of 100 nm, IMI sensors have a sandwich structure of ITO 50 nm/metal 10 nm/ITO 40 nm. The change in the gas sensitivity of the film sensors caused by methanol gas ranging from 100 to 1000 ppm was measured at room temperature. The IAI film sensors showed the higher sensitivity than the other sensors. Finally, it is concluded that the ITO 50/Au 10/ITO 40 nm film sensors hasthe potential to be used as improved methanol gas sensor.

      • KCI등재

        Epidemiology of Lower Urinary Tract Symptoms: Emphasis on the Status in Korea

        이학민,정성진 대한비뇨의학회 2014 Investigative and Clinical Urology Vol.55 No.5

        A comprehensive and correct understanding of epidemiologic finding about lower urinary tract symptoms (LUTS) is important for several reasons. First, LUTS are highly prevalent in both genders all around the world and are expected to be a major concern to physicians in the near future because of the rapid rise in the elderly population. Second, it is crucial to observe trends in prevalence when national health care policy is established. By using a Medline search with various terms related to LUTS and prevalence, a review of epidemiologic studies was undertaken with an emphasis on the status in Korea. Despite the suggestions made by the International Continence Society, the lack of uniform definitions and the lack of a unified threshold of symptoms are the biggest obstacles in epidemiologic study with regard to LUTS. Most Korean epidemiologic studies on LUTS have been reported since 2000 and reveal that the prevalences of specific clinical conditions, such as LUTS, benign prostatic hyperplasia, overactive bladder, and detrusor underactivity, are in line with prevalences in Western counties. However, the prevalence of nocturia is somewhat different from that in Western countries. Many epidemiologic studies of LUTS have provided us with valuable information and a better understanding of the clinical conditions. Given that the impact of these clinical conditions on quality of life and health care cost will be emphasized more in the near future, more studies on optimal management approaches to LUTS are needed on the basis of this knowledge.

      • KCI등재

        Changes in Bladder Wall Thickness and Detrusor Wall Thickness After Surgical Treatment of Benign Prostatic Enlargement in Patients With Lower Urinary Tract Symptoms: A Preliminary Report

        이학민,추민수,김명,조성용,이승배,정현,손환철 대한비뇨의학회 2014 Investigative and Clinical Urology Vol.55 No.1

        Purpose: The purpose of the present study was to evaluate the perioperative changesin bladder wall thickness and detrusor wall thickness after transurethralprostatectomy. Materials and Methods: Fifty-one men who were treated for benign prostatic hyperplasia/lower urinary tract symptoms with transurethral prostatectomy were prospectivelyanalyzed from May 2012 to July 2013. Prostate size, detrusor wall thickness,and bladder wall thickness were assessed by transrectal and transabdominal ultrasonographyperioperatively. All postoperative evaluations were performed 1 month afterthe surgery. Results: The patients’ mean age was 69.0 years, the mean prostate-specific antigen concentrationwas 8.1 ng/mL, and the mean prostate volume was 63.2 mL. The mean bladderwall thickness was 5.1 mm (standard deviation [SD], ±1.6), 5.1 mm (SD, ±1.6), and5.0 mm (SD, ±1.4) preoperatively and 4.5 mm (SD, ±1.5), 4.5 mm (SD, ±1.3), and 4.6mm (SD, ±1.2) postoperatively in the anterior wall, dome, and trigone, respectively(p=0.178, p=0.086, and p=0.339, respectively). The mean detrusor wall thickness was0.9 mm (SD, ±0.4) preoperatively and 0.7 mm (SD, ±0.3) postoperatively (p=0.001). Asubgroup analysis stratifying patients into a large prostate group (weight, ≥45 g) anda high Abrams-Griffiths number group (>30) showed a significant decrease in detrusorwall thickness (p=0.002, p=0.018). Conclusions: There was a decrease in detrusor wall thickness after transurethralprostatectomy. The large prostate group and the high Abrams-Griffiths number groupshowed a significant decrease in detrusor wall thickness after surgery.

      • KCI등재

        Elevated Ki-67 (MIB-1) Expression as an Independent Predictor for Poor Prognosis After Radical Cystectomy for Bladder Cancer

        이학민,이동환,정연수,응우엔 하,오종진,이상철,이상은,홍성규,변석수 대한비뇨기종양학회 2017 대한비뇨기종양학회지 Vol.15 No.3

        Purpose: We tried to investigate the clinical impact of Ki-67 (MIB-1) expression on the oncological and survival outcomes in patients with bladder cancer (BCa) after the radical cystectomy. Materials and Methods: We retrospectively analyzed the data of 230 patients who were treated by radical cystectomy for BCa. Multivariate Cox-proportional hazards models and logistic regression tests were performed to evaluate the prognostic value of each variable. Results: The patients with positive Ki-67 expression showed significant worse clinical characteristics and pathologic outcomes than negative Ki-67 group. Furthermore, the patients with Ki-67 expression showed significant worse recurrence (p=0.018) and cancer-specific mortality free survival (p=0.019) than negative Ki-67 group. The overall survival was also revealed to be inferior in Ki-67 positive group than Ki-67 negative group but the statistical significance was marginal (p=0.062). Subsequent multivariate Cox analyses showed that Ki-67 was independent predictor for disease recurrence after surgery (hazard ratio, 3.142; 95% CI, 1.287–7.671; p=0.012). Conclusions: In our study, high Ki-67 expression was significantly related with worse clinical outcomes after radical cystectomy in the patients with BCa. Further prospective and basic researches are needed to validate the true prognostic value of Ki-67.

      • KCI등재

        CRTC2 as a novel prognostic biomarker for worse pathologic outcomes and biochemical recurrence after radical prostatectomy in patients with prostate cancer

        이학민,이민승,홍성규 대한비뇨의학회 2019 Investigative and Clinical Urology Vol.60 No.2

        Purpose: To identify the association between tumor metabolism and prostate cancer (PCa), we investigated the relationship between expression of metabolism-related genes and clinicopathologic outcomes in patients with localized PCa. Materials and Methods: We prospectively collected periprostatic adipose tissue from 40 PCa patients and extracted the RNA of each sample. After cDNA was synthesized from the extracted RNA, we analyzed the expression of 18 metabolism-related genes using real-time polymerase chain reaction. We divided the subjects according to the pathologic Gleason score (pGS) and compared the expression of each gene. Subsequently, the clinicopathologic outcomes were also compared according to the expression of each gene. Results: When we compared the expression of 18 metabolism-related genes between the high (≥4+3) and low pGS groups (3+4), there were significant differences in the expression of six genes (SREBP, SCD, FASN, ACLY, ECHS, and CRTC2; p<0.05). Among them, the subjects with low expression for CRTC2 showed significantly worse pathologic outcomes in terms of high pGS (≥4+3) (p=0.020) and higher rates of seminal vesicle invasion (p=0.017). The low CRTC2 group also showed significantly inferior biochemical recurrence-free survival than the high CRTC2 group (p=0.048). Conclusions: We found that high pGS patients showed significant differences in expression of several metabolism-related genes compared with low pGS patients. Among those genes, CRTC2 showed the strongest association with pathologic outcome, as well as postoperative survival.

      • KCI등재

        Numerical Simulation of Horizontal Axis Wind Turbines with Vortex Generators

        이학민,권오준 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.2

        In the present study, a simulation about the effects of vortex generators on horizontal axis wind turbine rotor blade was numerically conducted using a static coupled CFD–CSD method. A Navier–Stokes CFD flow solver based on unstructured meshes was used to obtain the blade aerodynamic loads. A FEM-based CSD solver employing a nonlinear coupled flap-lagtorsion beam theory was utilized to calculate the blade elastic deformation. The coupling of the CFD and CSD solvers was accomplished in a loosely coupled manner by exchanging the information between the two solvers at infrequent intervals. The static coupled CFD–CSD method was applied to the NREL 5 MW reference wind turbine rotor under steady axial flow conditions. Triangular counter-rotating vortex generators were adopted to control flow separation and radial flow in the inboard section of the NREL 5 MW reference rotor blades. They were installed on the inboard part of the blade from 0.2 to 0.4 R. As a result of the flow analysis considering the counter-rotating vortex generators, strong vortices were generated by counter-rotating vortex generators. It can be seen that the regions where flow separation and radial flow occur in the inboard sections were reduced compared to the baseline wind turbine. For this reason, the maximum power improvement due to counter-rotating vortex generators was 1.04% at the rated wind speed.

      • KCI등재

        Effect of Intermediate Metal on the Methanol Gas Sensitivity of ITO Thin Films

        이학민,허성보,공영민,김대일,Lee, H.M.,Heo, S.B.,Kong, Y.M.,Kim, Dae-Il The Korean Vacuum Society 2011 Applied Science and Convergence Technology Vol.20 No.3

        RF 마그네트론 스퍼터와 DC 마그네트론 스퍼터를 병행하여 ITO/Au/ITO, ITO/Cu/ITO, 그리고 ITO/Ni/ITO 박막을 유리기판 위에 증착하였다. 증착 후 진공열처리를 통하여 층간 금속 층이 ITO박막의 메탄올 검출 민감도에 미치는 영향을 분석하였다. 모든 박막센서의 두께는 100 nm로 동일하게 ITO 50 nm/metal 10 nm/ITO 40 nm로 제작되었고 메탄올 농도는 100에서 1,000 ppm까지 달리하였다. ITO/Au/ITO 박막센서가 가장 높은 민감도를 보임으로써 ITO/Au/ITO 다층박막이 기존의 ITO메탄올 센서를 대체할 수 있는 센서임을 확인하였다. ITO thin films and gold (Au), copper (Cu) and nickel (Ni) intermediate ITO multilayer (ITO/Au/ITO, ITO/Cu/ITO, ITO/Ni/ITO) films were deposited on glass substrates with a reactive radio frequency and direct current magnetron sputtering system and then the effect of intermediate metal layer and annealing temperature on the methanol gas sensitivity of ITO films were investigated. Although both ITO and ITO/metal/ITO (IMI) film sensors have the same total thickness of 100 nm, IMI sensors have a sandwich structure of ITO 50 nm/metal 10 nm/ITO 40 nm. The change in the gas sensitivity of the film sensors caused by methanol gas ranging from 100 to 1000 ppm was measured at room temperature. The IAI film sensors showed the higher sensitivity than the other sensors. Finally, it is concluded that the ITO 50/Au 10/ITO 40 nm film sensors hasthe potential to be used as improved methanol gas sensor.

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