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Effects of gamma-ray irradiation on free volume in polymers by positron annihilation lifetime spectroscopy

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Nuclear Science and Techniques 2014年第A01期25卷 31-35页

作者： Yongmin KIM Jungki SHIN Junhyun kwon Department of Radiologieal Science Catholic University of Daegu Gyeongbuk 712-702 Republic of Korea Korea Research Institute of Standards and Science Daejeon 305-430 Republic of Korea Korea Atomic Energy Research Institute Daejeon 305-353 Republic of Korea

The positron annihilation lifetime (PAL) technique has been applied to study the effects of gamma-ray irradiation on polymer materials, such as ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR), and chloroprene rubber (CR), used in various industries. PAL measurements were performed with a conventional fast-fast coincidence system. Polymer materials were irradiated with 25 Gy/h in three conditions (50, 100, 500 Gy) and 5 kGy/h in six conditions (5, 50, 200, spo, 800, and 1 000 kGy) at room temperature with a (60)co gamma-ray source. Afterwards, the irradiated samples were measured by PAL spectroscopy. The delayed lifetime spectra of irradiated and unirradiated samples were decomposed into three lifetime components. The lifetime parameters indicate the free-volume size and concentration. The longest lifetime component represents the free volume size in polymer. Free volume and intensity were multiplied as a measure of relative fraction of free-volume hole. Cross-linking and degradation could occur when a polymer is irradiated. The free volumes of polymers were decreased accordingly. These results were verified through PAL measurement. From the Tao-Eldrup model, the mean radius and free volume fraction of CR, EPDM, and NBR were calculated. We certified the decrease of the fractional free volume. From these results, this study verified the feasibility of PA application on polymers.

关键词：正电子湮没寿命谱自由体积聚合物射线辐照 γ-射线照射高分子材料丁二烯橡胶伽玛

Clinical characteristics of incidental or unsuspected gallbladder cancers diagnosed during or after cholecystectomy: A systematic review and meta-analysis

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World Journal of Gastroenterology 2015年第4期21卷 1315-1323页

作者： Kui Sun Choi sae Byeol Choi Pyoungjae Park Wan Bae Kim Sang Yong Choi Department of Surgery Korea University College of MedicineSeoul 152-703South Korea

AIM: To perform a systematic review of incidental or unsuspected gallbladder(GB) cancer diagnosed during or after cholecystectomy. METHODS: Data in Pub Med, EMBASE, and CochraneLibrary were reviewed and 26 publications were included in the meta-analysis. The inclusion criterion for incidental GB cancer was GB cancer diagnosed during or after cholecystectomy that was not suspected at a preoperative stage. Pooled proportions of the incidence, distribution of T stage, and revisional surgery of incidental GB cancer were ***: The final pooled population comprised 2145 patients with incidental GB cancers. Incidental GB cancers were found in 0.7% of cholecystectomies p e r f o r m e d f o r b e n i g n g a l l b l a d d e r d i s e a s e s o n preoperative diagnosis(95%CI: 0.004-0.012). Nearly 50% of the incidental GB cancers were stage T2 with a pooled proportion of 47.0%(95%CI: 0.421-0.519). T1 and T3 GB cancers were found at a similar frequency, with pooled proportions of 23.0%(95%CI: 0.178-0.291) and 25.1%(95%CI: 0.195-0.317), respectively. The pooled proportion that completed revisional surgery for curative intent was 40.9%(95%CI: 0.329-0.494). The proportion of patients with unresectable disease upon revisional surgery was 23.0%(95%CI: 0.177-0.294). CONCLUSION: A large proportion of incidental GB cancers were T2 and T3 lesions. Revisional surgery for radical cholecystectomy is warranted in T2 and more advanced cancers.

关键词： Gallbladder cancer Laparoscopic surgery Cholecyste

Submillimeter wave communication versus millimeter wave communication

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Digital Communications and Networks 2020年第1期6卷 64-74页

作者： Madhuprana Goswami Hyuck M.kwon Department of Electrical Engineering and Computer Science Wichita State University1845 N.FairmountWichitaKS67260USA

This paper studies the performance of a submillimeter wave antenna operating between frequencies 0.1 THz and 10 THz with a 4-cyano-4-pentylbiphenyl[5CB]*** the size and shape of the antenna impact its gain/directivity,resonant frequency,bandwidth,and efficiency,the two antenna types considered in this paper are:(a)Rectangular Patch Antenna(RPA),and(b)Cylindrical Dielectric Resonator Antenna(CDRA).Here a submillimeter wave antenna is compared with a millimeter wave(a few GHz to 100 GHz)*** popular mmwave antennas are chosen for the submillimeter wave antenna in order to understand changes in their performance as the result of changes in their geometrical *** bei Korpern mit beliebiger Oberflache(FEKO)software is used for the design and calculation of the Three-Dimensional(3D)ElectroMagnetic(EM)*** paper also concentrates on the design and analysis of a massive submillimeter wave Multiple-Input Multiple-Output(MIMO)(8 by 8)RPA and CDRA.

关键词： Submillimeter wave antenna Millimeter wave antenna Rectangular micro-strip patch antenna Cylindrical dielectric resonator antenna Massive submillimeter wave MIMO antenna Applications

Randomized clinical trial of a bladder neck plication stitch during robot-assisted radical prostatectomy

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Asian Journal of Andrology 2015年第2期17卷 304-308,I0011页

作者： Seung-kwon Choi Sejun Park Hanjong Ahn Department of Urology University of Ulsan College of Medicine Asan Medical Center Seoul Korea Department of Urology University of Ulsan College of Medicine Ulsan University Hospital Utsan Korea

Urinary incontinence after robot-assisted radical prostatectomy （RARP） is one of the most bothersome complications affecting patients＇ daily lives. The efficacy of the bladder neck plication stitch technique in promoting an earlier return of continence was prospectively evaluated in 158 patients who underwent RARP for clinically localized prostate cancer by a single surgeon at our institute from March 2012 to January 2013. Patients were randomized 1：1 to undergo surgery with （n = 79） or without （n = 79） the bladder neck plication stitch, and their time to recovery from incontinence, defined as being pad free, was compared. Recovery from incontinence at 1, 3, and 6 months were observed in 22 （27.8%）, 42 （53.2%）, and 57 （72.2%） patients, respectively, treated with, and 23 （29.1%）, 47 （59.5%）, and 59 （74.7%） patients, respectively, treated without the bladder neck plication stitch, with no significant difference in time to recovery from incontinence between the two groups. Multivariate analysis showed that age, membranous urethral length and shape of the prostatic apex on magnetic resonance imaging were independent predictors of early recovery from urinary incontinence after RARP. The bladder neck plication stitch had no effect on time to recovery from postoperative urinary incontinence following RARR

关键词： prostatectomy prostatic neoplasms urinary incontinence urologic surgical procedures

Neuroinflammation in neurodegenerative disorders:the roles of microglia and astrocytes

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Translational Neurodegeneration 2020年第4期9卷 535-546页

作者： Hyuk Sung kwon Seong-Ho Koh Department of Neurology Hanyang University College of MedicineSeoulRepublic of Korea Department of Translational Medicine Hanyang University Graduate School of Biomedical Science&EngineeringSeoulRepublic of Korea

Neuroinflammation is associated with neurodegenerative diseases,such as Alzheimer's disease,Parkinson's disease,ancamyotrophic lateral *** and astrocytes are key regulators of inflammatory responses in the central nervous *** activation of microglia and astrocytes is heterogeneous and traditionally categorized as neurotoxi(M1-phenotype microglia and A1-phenotype astrocytes)or neuroprotective(M2-phenotype microglia and A2-phenotype astrocytes).However,this dichotomized classification may not reflect the various phenotypes of microgliaand *** relationship between these activated glial cells is also very complicated,and the phenotypic distribution can change,based on the progression of neurodegenerative diseases.A better understanding of the rolesof microglia and astrocytes in neurodegenerative diseases is essential for developing effective *** this review,we discuss the roles of inflammatory response in neurodegenerative diseases,focusing on the contributions of microglia and astrocytes and their *** addition,we discuss biomarkers to measure neuroinflammation andstudies on therapeutic drugs that can modulate neuroinflammation.

关键词： Neuroinflammation Neurodegenerative diseases Microglia Astrocytes

The Effect of Non-equilibrium Condensation on the Drag Coefficient in a Transonic Airfoil Flow

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Journal of Thermal Science 2012年第6期21卷 518-524页

作者： I.W.Kim M.M.A.Alam S.J.Lee Y.D.kwon S.B.kwon School of Mechanical Engineering Kyungpook Nat.Uni.1370Sankyuk-dongDaegu 702-701Korea Dept.of Advanced & Control Eng.Saga Uni.Japan

In this study, a transonic flow past NACA0012 profile at angle of attack α=0^0 whose aspect ratio AR is 1.0 with non-equilibrium condensation is analyzed by numerical analysis using a TVD scheme and is investigated using an intermittent indraft type supersonic wind tunnel. Transonic flows of 0.78-0.90 in free stream Mach number with the variations of the stagnation relative humidity（φ0） are tested. For the same free stream Mach number, the increase in φ0 causes decrease in the drag coefficient of profile which is composed of the drag components of form, viscous and wave. In the case of the same Moo and To, for more than φ0=30%, despite the irreversibility of process in non-equilibrium condensation, the drag by shock wave decreases considerably with the increase of φ0. On the other hand, it shows that the effect of condensation on the drag coefficients of form and viscous is negligible. As an example, the decreasing rate in the drag coefficient of profile caused by the influence of non-equilibrium condensation for the case of M∞=0.9 and φ0 =50% amounts to 34%. Also, it were turned out that the size of supersonic bubble （that is, the maximum height of supersonic zone） and the deviation of pressure coefficient from the value for M=1 decrease with the increase of φ0 for the same M∞.

关键词： Non-equilibrium condensation Transonic Moist air Drag coefficient Pressure coefficient

High resolution aerosol optical thickness retrieval over the Pearl River Delta region with improved aerosol modelling

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Science China Earth Sciences 2009年第10期52卷 1641-1649页

作者： WONG ManSing NICHOL Janet LEE kwon Ho Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic University Earth System Science Interdisciplinary Center University of Maryland (UMD)

Aerosol retrieval algorithms for the MODerate Resolution Imaging Spectroradiometer (MODIS) have been developed to estimate aerosol and microphysical properties of the atmosphere, which help to address aerosol climatic issues at global scale. However, higher spatial resolution aerosol products for urban areas have not been well researched mainly due to the difficulty of differentiating aerosols from bright surfaces in urban areas. Here, a new aerosol retrieval algorithm using the MODIS 500 m resolution images is described, to retrieve aerosol properties over Hong Kong and the Pearl River Delta region. The rationale of our technique is to first estimate the aerosol reflectance by decomposing the top-of-atmosphere reflectance from surface reflectance and Rayleigh path reflectance. For the determination of surface reflectance, a modified Minimum Reflectance Technique (MRT) is used, and MRT images are computed for different seasons. A strong correlation is shown between the surface reflectance of MRT images and MODIS land surface reflectance products (MOD09), with a value of 0.9. For conversion of aerosol reflectance to Aerosol Optical Thickness (AOT), comprehensive Look Up Tables (LUT) are constructed, in which aerosol properties and sun-viewing geometry in the radiative transfer calculations are taken into account. Four aerosol types, namely mixed urban, polluted urban, dust, and heavy pollution, were derived using cluster analysis on three years of AERONET measurements in Hong Kong. Their aerosol properties were input for LUT calculation. The resulting 500 m AOT images are highly correlated (r = 0.89) with AERONET sunphotometer observations in Hong Kong. This study demonstrates the applicability of aerosol retrieval at fine resolution scale in urban areas, which can assist the study of aerosol loading distribution and the impact of localized and transient pollution on urban air quality. In addition, the MODIS 500 m AOT images can be used to study cross-boundary aeroso

关键词： aerosol retrieval aerosol optical thickness AERONET MODIS satellite image

Probability mass first flush evaluation for combined sewer discharges

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Journal of Environmental Sciences 2010年第6期22卷 915-922页

作者： Inhyeok Park Hongmyeong Kim Soo-kwon Chae Sungryong Ha Department of Urban Engineering Chungbuk National University Ecowiz Corporation Cheongju School of Human & Environmental Sciences Eulji University

The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several serious problems have arisen in the operation and treatment effectiveness of these facilities due to unsuitable design flow volumes and pollution loads. It is difficult to assess the optimal flow volume and pollution mass when considering both monetary and temporal limitations. The objective of this article was to characterize the discharge of storm runoff pollution from urban catchments in Korea and to estimate the probability of mass first flush （MFFn） using the storm water management model and probability density functions. As a result of the review of gauged storms for the representative using probability density function with rainfall volumes during the last two years, all the gauged storms were found to be valid representative precipitation. Both the observed MFFn and probability MFFn in BE-1 denoted similarly large magnitudes of first flush with roughly 40% of the total pollution mass contained in the first 20% of the runoff. In the case of BE-2, however, there were significant difference between the observed MFFn and probability MFFn.

关键词： first flush combined sewer overflows (CSOs) probability mass first flush storm water management model best management practices

Effectiveness and safety of auriculotherapy for breastfeeding: a systematic review

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Journal of Traditional Chinese Medicine 2020年第5期40卷 721-737页

作者： Boram Lee Chan-Young kwon Sun Haeng Lee Department of Clinical Korean Medicine Graduate SchoolKyung Hee UniversitySeoul 02453Republic of Korea Clinical Medicine Division Korea Institute of Oriental MedicineDaejeon 34054Republic of Korea Department of Oriental Neuropsychiatry Dong-eui University College of Korean MedicineBusan 47227Republic of Korea Department of Pediatrics of Korean Medicine Kyung Hee University Korean Medicine HospitalKyung Hee University Medical CenterSeoul 02447Republic of Korea

OBJECTIVE:To summarize and critically evaluate the evidence pertaining to the effectiveness and safety of auriculotherapy for ***:We performed a systematic search of10 databases from their inception dates to May 15,*** controlled trials evaluating the effectiveness and safety of auriculotherapy for breastfeeding were *** of bias was assessed using the Cochrane risk of bias ***:This review included 31 randomized controlled trials with 5389 *** to the obvious clinical or statistical heterogeneity,a Meta-analysis was not ***-nine studies compared auriculotherapy plus routine care with routine care *** consistent adjunctive effect of auriculotherapy was observed in increasing the volume of milk production(9 studies showed significant results in favor of auriculotherapy and 5 did not)and serum prolactin level(7 studies showed significant results in favor of auriculotherapy and 2 did not),and in facilitating the initiation of milk secretion(10 studies showed significant results in favor of auriculotherapy and 7 did not).Two studies compared auriculotherapy with no *** as a monotherapy showed significant effects in increasing serum prolactin level and facilitating the onset of milk secretion;however,it was limited and inconclusive because only two studies were included in this *** subgroup analysis of women who underwent cesarean delivery showed inconsistent results with respect to all *** serious adverse events were reported with the use of *** methodological quality of the included studies was generally ***:Although some studies showed positive results,no definite conclusion about the effectiveness and safety of auriculotherapy for breastfeeding could be drawn,owing to the low methodological quality of the included studies and the heterogeneity among ***-scale,well-designed studies are warranted on this topic.

关键词： Breastfeeding Auriculotherapy Systematic review