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Effect of In Composition on Two-Dimensional Electron Gas in Wurtzite AlGaN/InGaN Heterostructures

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Chinese Physics Letters 2010年第11期27卷 188-190页

作者： KIM Bong-hwan park seoung-hwan LEE Jung-Hee MOON Yong-Tae Department of Electronics Engineering Catholic University of Daegu Hayang Kyeongsan Kyeongbuk 712-702 R. Korea School of Electrical Engineering and Computer Science Kyungpook National University Daegu 702-701 R. Korea LG Corporate Institute of Technology 16 Woomyeon-dong Seocho-gu Seoul 137-14-0 R. Korea

The effect of In composition on two-dimensional electron gas in wurtzite AlGaN/InGaN heterostructures is theoretically investigated. The sheet carrier density is shown to increase nearly linearly with In mole fraction x, due to the increase in the polarization charge at the AlGaN/InGaN interface. The electron sheet density is enhanced with the doping in the AlGaN layer. The sheet carrier density is as high as 3.7×1013 cm^-2 at the donor density of 10×1018 cm^-3 for the HEMT structure with x=0.3. The contribution of additional donor density on the electron sheet density is nearly independent of the In mole fraction.

关键词： Condensed matter: electrical magnetic and optical Electronics and devices Semiconductors Surfaces interfaces and thin films Condensed matter: structural mechanical & thermal Nanoscale science and low-D systems

A review of understanding electrocatalytic reactions in energy conversion and energy storage systems via scanning electrochemical microscopy

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Journal of Energy Chemistry 2024年第4期91卷 155-177页

作者： Jihye park Jong hwan Lim Jin-Hyuk Kang Jiheon Lim Ho Won Jang Hosun Shin Sun Hwa park Interdisciplinary Materials Measurement Institute Korea Research Institute of Standards and ScienceDaejeon 34113Republic of Korea Department of Material Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Applied Measurement Science University of Science and TechnologyDaejeon 34113Republic of Korea

To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for *** optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis *** electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical *** possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface *** review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage *** with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM.

关键词： Scanning electrochemical microscopy Electrocatalyst Electrocatalysis Water splitting Fuel cell Metal-oxygen battery

Validity of fatty liver prediction scores for diagnosis of fatty liver by Fibroscan

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Hepatobiliary & Pancreatic Diseases International 2024年第4期23卷 353-360页

作者： Seogsong Jeong Sun Jae park Seong Kyun Na Sang Min park Byung-Cheol Song Yun hwan Oh Department of Biomedical Sciences Seoul National University Graduate SchoolSeoul 03080Korea Department of Biomedical Informatics CHA University School of MedicineCHA UniversitySeongnam 13488Korea Department of Internal Medicine Inje University College of MedicineSeoul 50834Korea Department of Family Medicine Seoul National University HospitalSeoul National University College of MedicineSeoul 03080Korea Department of Internal Medicine Jeju National University HospitalJeju National University College of MedicineJeju 63241Korea Department of Family Medicine Jeju National University HospitalJeju National University College of MedicineJeju 63241Korea Department of Family Medicine Chung-Ang University Gwangmyeong HospitalChung-Ang University College of MedicineGwangmyeong 14353Korea

Background:The Korea National Health and Nutrition Examination Survey nonalcoholic fatty liver disease(K-NAFLD)score was recently developed with the intent to operationally define nonalcoholic fatty liver disease(NAFLD).However,there remained an external validation that confirmed its diagnostic performance,especially in patients with alcohol consumption or hepatitis virus ***:Diagnostic accuracy of the K-NAFLD score was evaluated in a hospital-based cohort consisting of 1388 participants who received Fibroscan®.Multivariate-adjusted logistic regression models and the contrast estimation of receiver operating characteristic curves were used for validation of the K-NAFLD score,fatty liver index(FLI),and hepatic steatosis index(HSI).Results:K-NAFLD-moderate[adjusted odds ratio(aOR)=2.53,95%confidence interval(CI):1.13-5.65]and K-NAFLD-high(aOR=4.14,95%CI:1.69-10.13)groups showed higher risks of fatty liver compared to the K-NAFLD-low group after adjustments for demographic and clinical characteristics,and FLI-moderate and FLI-high groups revealed aORs of 2.05(95%CI:1.22-3.43)and 1.51(95%CI:0.78-2.90),*** addition,the HSI was less predictive for Fibroscan®-defined fatty *** K-NAFLD and FLI also demonstrated high accuracy in the prediction of fatty liver in patients with alcohol consumption and chronic hepatitis virus infection,and the adjusted area under curve values were comparable between K-NAFLD and ***:Externally validation of the K-NAFLD and FLI showed that these scores may be a useful,noninvasive,and non-imaging modality for the identification of fatty *** addition,these scores also predicted fatty liver in patients with alcohol consumption and chronic hepatitis virus infection.

关键词： Nonalcoholic fatty liver disease Fatty liver index Hepatic steatosis index

Biochar-based materials as remediation strategy in petroleum hydrocarbon-contaminated soil and water:Performances,mechanisms,and environmental impact

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Journal of Environmental Sciences 2024年第4期138卷 350-372页

作者： Zhuo Wei YiWei Yang Liu Shuai Niu Yaxi Xu Jong-hwan park Jim J.Wang Faculty of Environmental Science&Engineering Kunming University of Science&TechnologyKunming 650500China School of Plant Environment&Soil SciencesLouisiana State University AgCenter.Baton RougeLA 70803USA Department of Life Resources Industry Dong-A University37Nakdong-daero 550 beon-gilSaha-guBusan 49315South Korea

Petroleum contamination is considered as a major risk to the health of humans and *** as low-cost and eco-friendly carbon materials,have been widely used for the removal of petroleum hydrocarbon in the *** purpose of this paper is to review the performance,mechanisms,and potential environmental toxicity of biochar,modified biochar and its integration use with other materials in petroleum contaminated soil and ***,the use of biochar in oil-contaminated water and soil as well as the factors that could influence the removal ability of biochar were systematically *** addition,the modification and integrated use of biochar for improving the removal efficiency were summarized from the aspects of sorption,biodegradation,chemical degradation,and ***,the functional impacts and associated ecotoxicity of pristine and modified biochars in various environments were ***,some shortcoming of current approaches,and future research needs were provided for the future direction and challenges of modified biochar ***,this paper gain insight into biochar application in petroleum remediation from the perspectives of performance enhancement and environmental sustainability.

关键词： Petroleum contamination Adsorbent Bioremediation Biochar modification Ecotoxicity

Endoscopic ultrasound-guided tissue sampling induced pancreatic duct leak resolved by the placement of a pancreatic stent:A case report

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World Journal of Clinical Cases 2024年第9期12卷 1677-1684页

作者： Ki-Hyun Kim Chang hwan park Eunae Cho Yohan Lee Department of Internal Medicine Chonnam National University HospitalGwangju 61469South Korea Department of Gastroenterology Chonnam National University HospitalGwangju 61469South Korea

BACKGROUND Pancreatic ductal leaks complicated by endoscopic ultrasonography-guided tissue sampling(EUS-TS)can manifest as acute *** SUMMARY A 63-year-old man presented with persistent abdominal pain and weight ***:Laboratory findings revealed elevated carbohydrate antigen 19-9(5920 U/mL)and carcinoembryonic antigen(23.7 ng/mL)*** resonance imaging of the pancreas revealed an approximately 3 cm ill-defined space-occupying lesion in the inferior aspect of the head,with severe encasement of the superior mesenteric *** ductal adenocarcinoma was confirmed after pathological examination of specimens obtained by EUS-TS using the fanning *** and outcomes:The following day,the patient experienced severe abdominal pain with high amylase(265 U/L)and lipase(1173 U/L)*** tomography of the abdomen revealed edematous wall thickening of the second portion of the duodenum with adjacent fluid collections and a suspicious leak from either the distal common bile duct or the main pancreatic duct in the *** retrograde cholangiopancreatography revealed dye leakage in the head of the main pancreatic ***,a 5F 7 cm linear plastic stent was deployed into the pancreatic duct to divert the pancreatic *** patient’s abdominal pain improved immediately after pancreatic stent insertion,and amylase and lipase levels normalized within a *** chemotherapy was then *** Using the fanning method in EUS-TS can inadvertently cause damage to the pancreatic duct and may lead to clinically significant *** a pancreatic stent may immediately resolve acute pancreatitis and shorten the waiting time for curative *** using the fanning method during EUSTS,ductal structures should be excluded to prevent pancreatic ductal leakage.

关键词： Endoscopic ultrasound-guided tissue sampling Pancreatitis Pancreatic duct leak Pancreatic stent Case report

Vertical plane depth-resolved surface potential and carrier separation characteristics in flexible CZTSSe solar cells with over 12% efficiency

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Carbon Energy 2024年第3期6卷 36-52页

作者： Dae-Ho Son Ha Kyung park Dae-hwan Kim Jin-Kyu Kang Shi-Joon Sung Dae-Kue hwang Jaebaek Lee Dong-hwan Jeon Yunae Cho William Jo Taeseon Lee JunHo Kim Sang-Hoon Nam Kee-Jeong Yang Division of Energy Technology DGISTDaeguRepublic of Korea Research Center for Thin Film Solar Cells DGISTDaeguRepublic of Korea Department of Physics Ewha Womans UniversitySeoulRepublic of Korea Department of Physics Incheon National UniversityIncheonRepublic of Korea Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMassachusettsUSA

Cu2ZnSn(S,Se)4(CZTSSe)solar cells have resource distribution and economic *** main cause of their low efficiency is carrier loss resulting from recombination of photo-generated electron and *** overcome this,it is important to understand their electron-hole behavior *** determine the carrier separation characteristics,we measured the surface potential and the local current in terms of the absorber *** elemental variation in the intragrains(IGs)and at the grain boundaries(GBs)caused a band edge shift and bandgap(Eg)*** the absorber surface and subsurface,an upward Ec and Ev band bending structure was observed at the GBs,and the carrier separation was *** the absorber center,both upward Ec and Ev and downward Ec-upward Ev band bending structures were observed at the GBs,and the carrier separation was *** improve the carrier separation and suppress carrier recombination,an upward Ec and Ev band bending structure at the GBs is desirable.

关键词： carrier separation CZTSSe flexible solar cell local current surface potential

Benefit in physical function and quality of life to nonsurgical treatment of varicose veins: Pilot study

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World Journal of Clinical Cases 2024年第3期12卷 517-524页

作者： Gwon-Min Kim BoKun Kim Minwoo Jang Jong-hwan park Miju Bae Chung Won Lee Jong Won Kim Up Huh Medical Research Institute Pusan National University School of MedicineYangsan 50612South Korea Future Convergence Research Institute Changwon National UniversityChangwon 51140South Korea Department of Convergence Medical Science School of MedicinePusan National UniversityYangsan 50612South Korea Health Convergence Medicine Laboratory Biomedical Research InstitutePusan National University HospitalBusan 49241South Korea Department of Thoracic and Cardiovascular Surgery Pusan National University School of MedicineBiomedical Research InstitutePusan National University HospitalBusan 49241South Korea

BACKGROUND Studies on varicose veins have focused its effects on physical function;however,whether nonsurgical treatments alter muscle oxygenation or physical function remains ***,the differences in such functions between individuals with varicose veins and healthy individuals remain *** To investigate changes in physical function and the quality of life(QOL)following nonsurgical treatment of patients with varicose veins and determine the changes in their muscle oxygenation during *** We enrolled 37 participants(those with varicose veins,n=17;healthy individuals,n=20).We performed the following measurements pre-and post-nonsurgical treatment in the varicose vein patients and healthy individuals:Calf muscle oxygenation during the two-minute step test,open eyes one-leg stance,30 s sit-to-stand test,visual analog scale(VAS)for pain,Pittsburgh sleep quality index,physical activity assessment,and QOL *** Varicose veins patients and healthy individuals differ in most variables(physical function,sleep quality,and QOL).Varicose veins patients showed significant differences between pre-and post-nonsurgical treatment—results in the 30 sit-to-stand test[14.41(2.45)to 16.35(4.11),P=0.018],two-minute step test[162.29(25.98)to 170.65(23.80),P=0.037],VAS for pain[5.35(1.90)to 3.88(1.73),P=0.004],and QOL[39.34(19.98)to 26.69(17.02),P=0.005];however,no significant difference was observed for muscle *** Nonsurgical treatment improved lower extremity function and QOL in varicose veins patients,bringing their condition close to that of healthy *** studies should include patients with severe varicose veins requiring surgery to confirm our findings.

关键词： Varicose vein Nonsurgical treatment Physical function Quality of life Near infrared spectroscopy

Omni-functional simultaneous interfacial treatment for enhancing stability and outgassing suppression of lithium-ion batteries

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Journal of Energy Chemistry 2024年第7期94卷 677-687页

作者： Youbean Lee Chanjoo park Kyoungmin Min Kwangjin park Department of Mechanical Engineering Gachon UniversityGyeonggi-do 13120Republic of Korea Department of Battery Engineering Gachon UniversityGyeonggi-do 13120Republic of Korea School of Mechanical Engineering Soongsil UniversitySeoul 06978Republic of Korea

Ni-rich layered oxides in lithium-ion batteries have problems with gas generation and electrochemical performance reduction due to residual lithium's reaction on the surface with the *** address this issue,in this study,the Acid solvent evaporation(AsE)method has been proposed as a potential method to remove residual lithium while promoting the formation of a new LiNO_(3)-derived coating layer on the cathode *** reduction of residual lithium using the ASE method and the construction of a LiNO_(3)-derived coating layer suppresses gas evolution caused by the side effects of the electrolyte,improves electrochemical performance,and improves thermal stability by facilitating the smooth movement of lithium ***,the structural stability and resistance change due to the LiNO_(3)-derived coating layer effects is guaranteed through cycling and DCIR of the pouch *** a result,compared to Pristine,the capacity retention of coin cells increased by 8%after 100 cycles,and pouch cells increased by 25%after 160 *** addition,after cycling the pouch cell,CO_(2) gas has significantly reduced by about 30%compared to Pristine using gas *** ASE method effectively forms a robust LiNO_(3)-derived coating layer on the cathode active material,which helps minimize electrolyte reactivity,suppress ,CO_(2) emissions,enhance surface structure stability,improve thermal stability,and improveoverallbatteryperformance.

关键词： Lithium-ion batteries Ni-rich NCM Acid solvent evaporation LiNO_(3)-derived coating Gasevolution

An Investigation on Open-RAN Specifications:Use Cases,Security Threats,Requirements,Discussions

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 13-41页

作者： Heejae park Tri-HaiNguyen Laihyuk park Department of Computer Science and Engineering Seoul National University of Science and TechnologySeoul01811Republic of Korea Faculty of Information Technology School of TechnologyVan Lang UniversityHo Chi Minh City70000Vietnam

The emergence of various technologies such as terahertz communications,Reconfigurable Intelligent Surfaces(RIS),and AI-powered communication services will burden network operators with rising infrastructure ***,the Open Radio Access Network(O-RAN)has been introduced as a solution for growing financial and operational burdens in Beyond 5G(B5G)and 6G networks.O-RAN promotes openness and intelligence to overcome the limitations of traditional *** disaggregating conventional Base Band Units(BBUs)into O-RAN Distributed Units(O-DU)and O-RAN Centralized Units(O-CU),O-RAN offers greater flexibility for upgrades and network ***,this openness introduces new security challenges compared to traditional *** existing studies overlook these security requirements of the O-RAN *** gain deeper insights into the O-RAN system and security,this paper first provides an overview of the general O-RAN architecture and its diverse use cases relevant to B5G and 6G *** then delve into specifications of O-RAN security threats and requirements,aiming to mitigate security vulnerabilities *** providing a comprehensive understanding of O-RAN architecture,use cases,and security considerations,thisworkserves as a valuable resource for future research in O-RAN and its security.

关键词： O-RAN architecture use cases security issues security requirements security discussions