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Structural optimization for ball valve made of CF8M stainless steel

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中国有色金属学会会刊：英文版 2009年第B9期19卷 258-261页

作者： seung-Gyu kim Seok-Heum BAEK Young-Chul PARK Department of Mechanical Engineering Dong-A University

The mechanical and chemical properties of CF8M were studied through experiments. An application of CF8M in valve body was analyzed by using finite element method(FEM) to evaluate the structural safety. An optimization containing several variables based on the response surface method(RSM) was conducted to find the optimum dimension of the valve. The results show that using this process can save valve mass as well as the computational expense effectively.

关键词：结构优化球阀不锈钢化学性能有限元法结构安全最佳尺寸 FEM

Exploring anharmonic lattice dynamics and dielectric relations in niobate perovskites from first-principles self-consistent phonon calculations

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npj Computational Materials 2023年第1期9卷 757-766页

作者： Kwangrae kim Woohyun Hwang seung-Hyun Victor Oh Aloysius Soon Department of Materials Science&Engineering Yonsei UniversitySeoul 03722Republic of Korea

Group I niobates(KNbO_(3) and NaNbO_(3))are promising lead-free alternatives for high-performance energy storage *** their potential,their complex phase transitions arising from temperature-dependent phonon softening and anharmonic effects on dielectric properties remain poorly *** this study,we employ density-functional theory(DFT)and self-consistent phonon(SCP)calculations to investigate finite-temperature phonons in cubic niobate *** include explicit anharmonic vibrational effects,SCP frequencies are shifted by the bubble self-energy correction within the quasiparticle(QP)approximation,providing precise descriptions of phonon softening in these strongly anharmonic *** further calculate the static dielectric constant of KNbO_(3) and NaNbO_(3) as a function of temperature using the Lyddane-Sachs-Teller(LST)relation and QP-corrected phonon *** theoretical results align with experimental data,offering reliable temperature-dependent phonon dispersions while considering anharmonic self-energies and thermal expansion effects,enhancing our understanding of the complex relations between lattice vibrations and phase transitions in these anharmonic oxides.

关键词： harmonic phonon dielectric

Estimation of marine winds in and around typhoons using multi-platform satellite observations: Application to Typhoon Soulik (2018)

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Frontiers of Earth Science 2022年第1期16卷 175-189页

作者： seung-Woo LEE Sung Hyun NAM Duk-Jin kim School of Earth and Environmental Sciences College of Natural SciencesSeoul National UniversitySeoul 08826Republic of Korea Research Institution of Oceanography College of Natural SciencesSeoul National UniversitySeoul 08826Republic of Korea

Estimating horizontal winds in and around typhoons is important for improved monitoring and prediction of typhoons and mitigating their ***,we present a new algorithm for estimating typhoon winds using multiple satellite observations and its application to Typhoon Soulik(2018).Four kinds of satellite remote sensing data,along with their relationship to typhoon intensity,derived statistically from hundreds of historical typhoon cases,were merged into the final product of typhoon wind(MT wind):(1)geostationarysatellite-based infrared images(IR wind),(2)passive microwave sounder(MW wind),(3)feature-tracked atmospheric motion vectors,and (4)scatterometer-based sea surface winds(SSWs).The algorithm was applied to two cases(A and B)of Typhoon Soulik and validated against SSWs independently retrieved from active microwave synthetic aperture radar(SAR)and microwave radiometer(AMSR2)images,and vertical profiles of wind speed derived from reanalyzed data and dropsonde *** Case A(open ocean),the algorithm estimated the realistic maximum wind,radius of maximum wind,and radius of 15 m/s,which could not be estimated using the reanalysis data,demonstrating reasonable and practical ***,for Case B(when the typhoon rapidly weakened just before making landfall in the Korean Peninsula),the algorithm significantly overestimated the parameters,primarily due to the overestimation of typhoon *** study highlights that realistic typhoon winds can be monitored continuously in real-time using multiple satellite observations,particularly when typhoon intensity is reasonably well predicted,providing timely analysis results and products of operational importance.

关键词： sea surface wind multi-platform satellites Typhoon Soulik(2018)

Minimizing liver uptake of cationic ^(99m)Tc radiotracers with ether and crown ether functional groups

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World Journal of Hepatology 2010年第1期2卷 21-31页

作者： Young-seung kim School of Health Sciences Purdue University550 Stadium Mall DriveWest LafayetteIN47907United States

Ischemia-related diseases,particularly coronary artery disease(CAD),account for the majority of deaths *** ischemia is a serious condition and the delay in reperfusion of ischemic tissues can be *** is particular true in the aged *** and accurate early detection of myocardial ischemia is highly desirable so that various therapeutic regiments can be given before irreversible myocardial damage *** perfusion imaging with radiotracers is an integral component in evaluations of patients with known or suspected CAD. 99m Tc-Sestamibi and 99m Tc-Tetrofosmin are commercial radiopharmaceuticals currently available for myocardial perfusion *** their widespread clinical applications,both 99m Tc-Sestamibi and 99m Tc-Tetrofosmin do not meet the requirements of an ideal perfusion imaging agent,largely due to their high liver *** intense liver uptake makes it difficultto interpret the heart activity in the inferior and left ventricular *** scattering from the high liver radioactivity accumulation remains a significant challenge for diagnosis of heart *** review will summarize the most recent research efforts to minimize the liver uptake of cationic 99m Tc radiotracers by using ether and crown ether-containing chelators. Fast liver clearance will shorten the duration of imaging protocols(<30 min post-injection) ,and allow for early acquisition of heart images with high quality. Improvement of heart/liver ratio may permit better detection of the presence and extent of coronary artery *** of such a new radiotracer that allows for the improved noninvasive assessment of myocardial perfusion would be of considerable benefit in treatment of patients with suspected CAD.

关键词： Myocardial perfusion imaging Cationic 99mTc radiotracers Single photon emission computed tomography

Risk factors affecting pancreatic fistulas after pancreaticoduodenectomy

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World Journal of Gastroenterology 2008年第45期14卷 6970-6974页

作者： Yun-Mee Choe Keon-Young Lee Cheong-Ah Oh Joung-Bum Lee Sun Keun Choi Yoon-Seok Hur Sei-Joong kim Young up Cho seung-Ik Ahn Kee-Chun Hong Seok-Hwan Shin Kyung-Rae kim Department of Surgery Inha University Hospital

AIM: To analyze the risk factors of pancreatic leakage after ***: We retrospectively reviewed 172 consecutive patients who had undergone pancreatico-duodenectomy at Inha University Hospital between April 1996 and March 2006. We analyzed the pancreatic fistula rate according to the clinical characteristics, the pathologic and laboratory findings, and the anastomotic ***: The incidence of developing pancreatic fistulas in patients older than 60 years of age was 21.7% (25/115), while the incidence was 8.8% (5/57) for younger patients; the difference was significant (P = 0.03). Patients with a dilated pancreatic duct had a lower rate of post-operative pancreatic fistulas than patients with a non-dilated duct (P = 0.001). Other factors, including clinical features, anastomotic methods, and pathologic diagnosis, did not show any statistical difference. CONCLUSION: Our study demonstrated that pancreatic fistulas are related to age and a dilated pancreatic duct. The surgeon must take these risk factors into consideration when performing a pancre-aticoduodenectomy.

关键词： Pancreaticoduodenectomy Pancreatic fistula Pancreatic leakage

Avoiding heating interference and guided thermal conduction in stretchable devices using thermal conductive composite islands

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Nano Research 2021年第9期14卷 3253-3259页

作者： seung Ji Kang Haeleen Hong Chanho Jeong Ju seung Lee Hyewon Ryu Jae-hun Yang Jong Uk kim Yiel Jae Shin Tae-il kim School of Chemical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Department of Biomedical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Biomedical Institute for Convergence(BICS) Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea

The miniaturization and high integration of devices demand significant thermal management *** technologies for the thermal management of electronics show some limitations in the case of multiple chip arrays.A device in multiple chip array is affected by heat from adjacent devices,along with thermal conductive *** address this problem,we present a nano composite of aligned boron nitride(BN)nanosheet islands with porous polydimethylsiloxane(PDMS)foam to have mechanical stability and non-thermal *** islands of tetrahedrally-structured BN in the composite have a high thermal conductivity of 1.219 W·m^(-1)·K^(-1) in the through-plane direction(11.234W·m^(-1)·K^(-1)in the in-plane direction)with 16 wt.%loading of *** the other hand,porous PDMS foam has a low thermal conductivity of 0.0328W·m^(-1)·K^(-1) in the through-plane direction at 70%*** pathways are then formed only in the structured BN islands of the *** porous PDMS foam can be applied as a thermal barrier between structured BN islands to inhibit thermal interference in multiple device ***,this composite can maintain selective thermal dissipation performance with 70%tensile *** beauty of the work is that it could have guided heat dissipation by assembling of multiple layers which have high vertical thermal conductive islands,while inhibiting thermal *** selective heat dissipating composite can be applied as a heatsink for multiple chip arrays electronics.

关键词： selective thermal conduction non-thermal interference thermal conductive composite island stretchable electronics structured boron nitride nanosheet(s-BN) porous polydimethylsiloxane(p-PDMS)

Clinical application of liver stiffness measurement using transient elastography in chronic liver disease from longitudinal perspectives

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World Journal of Gastroenterology 2013年第12期19卷 1890-1900页

作者： Beom Kyung kim James Fung Man-Fung Yuen seung up.kim Department of Internal Medicine Institute of Gastroenterology Yonsei University College of Medicine Liver Cirrhosis Clinical Research Center Department of Medicine State Key Laboratory for Liver Research the University of Hong Kong

Accurate determination of the presence and degree of fibrosis in liver is of great importance, because the prognosis and management strategies for chronic liver disease depend mainly on these factors. To date, liver biopsy (LB) remains the "gold standard" for assessing the severity of liver fibrosis; however, LB is often limited by its invasiveness, sampling error, and intra/ inter-observer variability in histological interpretation. Furthermore, repeated LB examinations within a short time interval are indeed ineligible in a real clinical practice. Thus, due to the pressing need for non-invasive surrogates for liver fibrosis, transient elastography (TE),as a novel ultrasound based technology, has allowed a noninvasive measurement of liver stiffness and has gained in popularity over recent years. In the past few years, additional roles for transient TE beyond the initial purpose of a non-invasive surrogate for LB have included the prediction of the most two critical consequences of fibrosis progression: the development of portal hypertension-related complications and hepatocellular carcinoma. This indicates that the role of transient TE is not merely limited to reducing the need for LB, but transient TE can enable the establishment of tailored management strategies by providing more detailed prognostic information. In particular, under the concept in which the clinical course of liver fibrosis is dynamic and bidirectional, especially when appropriate intervention is commenced, transient TE can be used to track the dynamic changes in fibrotic burden during antiviral or antifibrotic treatment. This review discussed extended applications of transient TE in prediction of the development of real clinical endpoints from a longitudinal perspective.

关键词： Liver stiffness Transient elastography Fibroscan Fibrosis Longitudinal Outcome

Right hepatectomy in living donors with previous abdominal surgery

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Hepatobiliary & Pancreatic Diseases International 2017年第1期16卷 33-38页

作者： Seong Hoon kim seung Duk Lee Young Kyu kim Sang-Jae Park Center for Liver Cancer National Cancer Center 111 Jungbalsan-ro Ilsandong-gu Goyang-si Gyeonggi-do 410-769 Korea

BACKGROUND： Few studies have evaluated the impact of previous abdominal surgery （PAS） on living donor right hepatectomy （LDRH）. The aim of this study was to investigate the outcomes of liver transplantation using right lobe grafts of living donors with PAS. METHODS： Data were reviewed from LDRH patients at the authors＇ institution between March 2008 and November 2014. LDRH patients with PAS were divided into two groups according to upper PAS （group 1） or lower PAS （group 2）, and they were compared to those without PAS （group 3） who were matched 1：1 based on age, gender, and body mass index. Periop- erative data, complications by the Clavien classification, and the outcomes with more than 14 months follow-up were compared. RESULTS： Twenty-three （4.9%） of a total of 471 LDRH donors had PAS. Eleven donors were assigned to group 1, 12 to group 2, and 23 to group 3. Intraperitoneal adhesions were found in 20 （87.0%） of 23 donors with PAS, of whom 5 （21.7%） had adhesiolysis-related injuries that happened more commonly in group 1 than in group 2 （P=0.025）. LDRH was successfully completed under upper midline laparotomy in all donors. No donors received perioperative blood transfusion. The peak postoperative AST, ALT, INR, and total bilirubin levels made no difference between the three groups. Compared with group 3, groups 1 and 2 had a longer operative time （P=0.012） and a higher grade I complication rate （P=0.047）. All donors recovered fully to their routine activities. The 23 recipients of grafts from donors with PAS showed good liver function with 1-year graft and patient survivals of 100%. CONCLUSION： A history of PAS is not a contraindication to LDRH in the current era of advanced surgical techniques.

关键词： living donor liver transplantation liver surgery liver function

Conversion of twice-daily to once-daily tacrolimus is safe in stable adult living donor liver transplant recipients

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Hepatobiliary & Pancreatic Diseases International 2015年第4期14卷 374-379页

作者： Seong Hoon kim seung Duk Lee Young Kyu kim Sang-Jae Park Center for Liver Cancer National Cancer Center 111 Jungbalsan-ro Ilsandong-gu Goyang-si Gyeonggi-do 410-769 Korea

Once-daily extended-release tacrolimus （Tac-OD） has been introduced as a useful therapeutic option to increase patient adherence to immunosuppressive therapy. This study aimed to evaluate the safety, efficacy and immunosuppressant adherence of conversion from twice-daily tacrolimus （Tac-BID） to Tac-OD in stable adult living donor liver transplant （LDLT） recipients in a single institution. METHODS： Between February and May 2013, Tac-BID was converted to Tac-OD in recipients followed up for at least 12 months after transplantation and without previous rejection episodes. The switching policy was based on a dose ratio of 1：1 with dose adjustment target trough levels at 3-5 ng/mL. Tacro- limus trough levels, laboratory parameters, metabolic disor- ders, and adverse events were assessed. RESULTS： A total of 229 patients were enrolled in the study. The median age at conversion was 53 years （range 31-73）. The median transplant duration was 35.3 months （range 12.0-95.4）. During a median follow-up of 13.5 months after conversion, 9 patients returned to Tac-BID because of adverse events. No acute rejection episodes were observed. Of 214 patients still on Tac-OD at 12 months, 12 （5.6%） received a reduced dose and 95 （44.4%） required an increased dose over baseline. Overall adherence was 82.2% at the end of follow-up. CONCLUSION： The conversion from Tac-BID to Tac-OD with similar target trough levels after conversion is safe and effec- tive for long-term stable LDLT patients.

关键词： liver transplantation living donor immunosuppressive agents tacrolimus