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Acta Oceanologica Sinica 2013年第1期32卷 59-67页

作者： YANG chan-Su park Seong-Min OH Yisok OUCHI Kazuo Korea Ocean Satellite Center Korea Institute of Ocean Science & Technology (KIOST) Marine Environmental System Science University of Science and Technology ISR R&D Laboratory LIG Nex1 Company Department of Electronics Information and Communication Engineering Hongik University Department of Computer Science School of Electrical and Computer Engineering National Defense Academy

An analysis of the radar backscattering from the ocean surface covered by oil spill is presented using a mi- crowave scattering model and Monte-Carlo simulation. In the analysis, a one-dimensional rough sea sur- face is numerically generated with an ocean waveheight spectrum for a given wind velocity. A two-layered medium is then generated by adding a thin oil layer on the simulated rough sea surface. The electric fields backscattered from the sea surface with two-layered medium are computed with the method of moments （MoM）, and the backscattering coefficients are statistically obtained with N independent samples for each oil-spilled surface using the Monte-Carlo technique for various conditions of surface roughness, oil-layer thickness, frequency, polarization and incidence angle. The numerical simulation results are compared with theoretical models for clean sea surfaces and SAR images of an off-spilled sea surface caused by the Hebei （Hebei province, China） Spirit oil tanker in 2007. Further, conditions for better oil spill extraction are sought by the numerical simulation on the effects of wind speed and oil-layer thickness at different inci- dence angles on the backscattering coefficients.

关键词： method of moments Monte-Carlo technique oil spills backscattering coefficient

Charge-carrier photogeneration and extraction dynamics of polymer solar cells probed by a transient photocurrent nearby the regime of the space charge-limited current

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Frontiers of Chemical Science and Engineering 2021年第1期15卷 164-179页

作者： Boa Jin Hyunmin park Yang Liu Leijing Liu Jongdeok An Wenjing Tian chan Im Department of Chemistry Konkuk UniversitySeoul 05029Republic of Korea State Key Laboratory of Supramolecular Structure and Materials College of ChemistryJilin UniversityChangchun 130012China

To understand the complex behaviors of photogenerated charge carriers within polymer-based bulk-heterojunction-type solar cells,the charge-carrier photogeneration and extraction dynamics are simultaneously estimated using a transient photocurrent technique under various external-bias voltages,and a wide range of excitation intensities are *** this purpose,conventional devices with 80 nm thick active layers consisting of a blend of representative P3HT and PTB7 electron-donating polymers and proper electron-accepting fullerene derivatives were *** the correction for the saturation behavior at a high excitation-intensity range nearby the regime of the space charge-limited current,the incident-photon-density-dependent maximum photocurrent densities at the initial peaks are discussed as the proportional measures of the charge-carrier-photogeneration *** comparing the total number of the extracted charge carriers to the total number of the incident photons and the number of the initially photogenerated charge carriers,the external quantum efficiencies as well as the extraction quantum efficiencies of the charge-carrier collection during a laser-pulse-induced transient photocurrent process were ***,the charge-carrier concentration-dependent mobility values were obtained,and they are discussed in consideration of the additional influences of the charge-carrier losses from the device during the charge-carrier extraction that also affects the photocurrent-trace shape.

关键词： charge-carrier photogeneration transient photocurrent polymer solar cells charge-carrier extraction space charge-limited current

Tailoring uniform γ-MnO2 nanosheets on highly conductive three-dimensional current collectors for high-performance supercapacitor electrodes

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Nano Research 2015年第3期8卷 990-1004页

作者： Sangbaek park Hyun-Woo Shim chan Woo Lee Hee Jo Song Ik Jae park Jae-chan Kim Kug Sun Hong Dong-Wan Kim Department of Materials Science and Engineering Seoul National University Seou1151-744 R. O. Korea School of Civil Environmental and Architectural Engineering Korea University Seou1136-713 R. O. Korea

Recent efforts have focused on the fabrication and application of three- dimensional （3-D） nanoarchitecture electrodes, which can exhibit excellent electrochemical performance. Herein, a novel strategy towards the design and synthesis of size- and thickness-tunable two-dimensional （2-D） MnO2 nanosheets on highly conductive one-dimensional （l-D） backbone arrays has been developed via a facile, one-step enhanced chemical bath deposition （ECBD） method at a low temperature （-50 ℃）. Inclusion of an oxidizing agent, BrO3-, in the solution was crucial in controlling the heterogeneous nucleation and growth of the nanosheets, and in inducing the formation of the tailored and uniformly arranged nanosheet arrays. We fabricated supercapacitor devices based on 3-D MnO2 nanosheets with conductive Sb-doped SnO2 nanobelts as the backbone. They achieved a specific capacitance of 162 F·g-1 at an extremely high current density of 20 A·g% and good cycling stability that shows a capacitance retention of -92% of its initial value, along with a coulombic efficiency of almost 100% after 5,000 cycles in an aqueous solution of I M Na2SO4. The results were attributed to the unique hierarchical structures, which provided a short diffusion path of electrolyte ions by means of the 2-D sheets and direct electrical connections to the current collector by 1-D arrays as well as the prevention of aggregation by virtue of the well-aligned 3-D structure.

关键词： nanosheets manganese oxide chemical bath deposition SnO2 nanobelts supercapacitor

Carbon-Coated Three-Dimensional MXene/Iron Selenide Ball with Core–Shell Structure for High-Performance Potassium-Ion Batteries

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Nano-Micro Letters 2022年第1期14卷 278-294页

作者： Su Hyun Yang Yun Jae Lee Heemin Kang Seung-Keun park Yun chan Kang Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul 136-713Republic of Korea Department of Advanced Materials Engineering Chung-Ang University4726 Seodong-daeroDaedeok-myeonAnseong-siGyeonggi-do 17546Republic of Korea

Two-dimensional(2D)MXenes are promising as electrode materials for energy storage,owing to their high electronic conductivity and low diffusion ***,similar to most 2D materials,MXene nanosheets easily restack during the electrode preparation,which degrades the electrochemical performance of MXene-based materials.A novel synthetic strategy is proposed for converting MXene into restacking-inhibited three-dimensional(3D)balls coated with iron selenides and *** strategy involves the preparation of Fe_(2)O_(3)@carbon/MXene microspheres via a facile ultrasonic spray pyrolysis and subsequent selenization *** 3D structuring effectively prevents interlayer restacking,increases the surface area,and accelerates ion transport,while maintaining the attractive properties of ***,combining iron selenides and carbon with 3D MXene balls offers many more sites for ion storage and enhances the structural robustness of the composite *** resultant 3D structured microspheres exhibit a high reversible capacity of 410 mAh g^(−1) after 200 cycles at 0.1 A g^(−1) in potassium-ion batteries,corresponding to the capacity retention of 97% as calculated based on 100 *** at a high current density of 5.0 A g^(−1),the composite exhibits a discharge capacity of 169 mAh g^(−1).

关键词： MXene Spray pyrolysis Iron selenide Potassium-ion batteries 3D structures

Electrically focus-tuneable ultrathin lens for high-resolution square subpixels

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Light(Science & Applications) 2020年第1期9卷 1066-1078页

作者： Sehong park Gilho Lee Byeongho park Youngho Seo Chae bin park Young Tea Chun Chulmin Joo Junsuk Rho Jong Min Kim James Hone Seong chan Jun School of Mechanical Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Electrical Engineering Division Engineering DepartmentUniversity of Cambridge9 JJ Thomson AvenueCambridge CB3 OFAUK Department of Electronic Material Engineering Korea Maritime and Ocean UniversityBusan 49112Republic of Korea Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)77 Cheongam-roNam-guPohang 37673Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)77 Cheongam-roNam-guPohang 37673Republic of Korea Institute for Convergence Research and Education in Advanced Technology Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Department of Mechanical Engineering Columbia University500 West 120th StreetMudd 220New YorkNY 10027USA

Owing to the tremendous demands for high-resolution pixel-scale thin lenses in displays,we developed a graphenebased ultrathin square subpixel lens(USSL)capable of electrically tuneable focusing(ETF)with a performance competitive with that of a typical mechanical refractive *** fringe field due to a voltage bias in the graphene proves that our ETF-USSL can focus light onto a single point regardless of the wavelength of the visible light—by controlling the carriers at the Dirac point using radially patterned graphene layers,the focal length of the planar structure can be adjusted without changing the curvature or position of the lens.A high focusing efficiency of over 60% at a visible wavelength of 405 nm was achieved with a lens thickness of change of 19.42% in the focal length with a 9% increase in transmission was exhibited under a driving *** design is first presented as an ETF-USSL that can be controlled in pixel units of flat panel displays for visible *** can be easily applied as an add-on to high resolution,slim displays and provides a new direction for the application of multifunctional autostereoscopic displays.

关键词： visible driving competitive

Effect of esterification reaction of citric acid and ethylene glycol on the formation of multi-shelled cobalt oxide powders with superior electrochemical properties

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Nano Research 2014年第12期7卷 1738-1748页

作者： Gi Dae park Jong-Heun Lee Jung-Kul Lee Yun chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea Department of Chemical Engineering Konkuk University 1 Hwayang-dong Gwangjin-gu Seou1143-701 Republic of Korea

In this study, for the first time, polymeric precursors have been used in the preparation of yolk-shell powders using a large-scale spray drying process. An esterification reaction between the carboxyl group of citric acid and the hydroxyl group of ethylene glycol inside the droplet produced organic polymers during the drying process of the droplet. During the spray drying process, the polymeric precursors enabled the formation of multi-shell cobalt oxide yolk- shell powders with superior electrochemical properties. The maximum number of shells of the particles in the yolk-shell powders post-treated at 300, 400, and 500 ℃ were six, five, and four, respectively. The initial discharge capacities of the cobalt oxide yolk-shell powders post-treated at 300, 400, and 500 ℃ were 1,188, 1,331, and 1,110 mAh·g^-1, and their initial charge capacities were 868, 1,005, and 798 mAh·g^-1, respectively. The discharge capacities of the powders post- treated at 300, 400, and 500 ℃ after 100 cycles were 815, 958, and 670 mAh·g^-1, respectively and their corresponding capacity retentions measured after the first cycles were 92%, 93%, and 82%, respectively. The pure phase Co3O4 yolk-shell powders post-treated at 400 ℃ had low charge transfer resistance and high lithium-ion diffusion rate.

关键词： yolk-shell energy storage synthesis design lithium battery spray drying

Increased incidence of indeterminate pancreatic cysts and changes of management pattern: Evidence from nationwide data

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Hepatobiliary & Pancreatic Diseases International 2023年第3期22卷 294-301页

作者： Jaewoo park Jinkyeong park Yoon Suk Lee Kwangrok Jung In Ho Jung Jong-chan Lee Jin-Hyeok Hwang Jaihwan Kim Department of Internal Medicine Seoul National University Bundang HospitalSeoul National University College of MedicineSeongnamKorea Department of Internal Medicine Kyung Hee University Hospital at GangdongSeoulKorea Department of Internal Medicine Inje University College of MedicineIlsan Paik HospitalGoyangKorea

Background:Pancreatic cysts are ***,most studies are based on data collected from individual *** present study aimed to evaluate the changes of management patterns for pancreatic cystic lesions(PCLs)by analyzing large epidemiologic ***:Between January 2007 and December 2018,information regarding pancreatic cystic lesions was acquired from the nationwide Health Insurance Review and Assessment Service database in ***:The final number of patients with pancreatic cysts was 165277 among the total claims for reimbursement of 855983 associated with PCLs over 12 *** total number of claims were increased from 19453 in 2007 to 155842 in 2018 and the prevalence increased from 0.04%to 0.23%.For 12 years,2874(1.7%)had pancreatic cancer and 8212(5.0%)underwent surgery,and 36 had surgery for twice(total 8248 pancreatectomy).After ruling out claims from the first 3 years of washout period,the incidence increased from 9891 to 24651 and the crude incidence rate of PCLs expanded from 19.96 per 100000 to 47.77 per *** to specific neoplasm codes(D136 or D377),the use of pancreatic cyst code(K862)has been remarkably increased and the most common since *** annual number of pancreatectomies increased from 518 to 861 between 2007 and 2012,and decreased to 596 until *** percentage of pancreatic cancer in patients who received pancreatectomy increased from 5.6%in 2007 to 11.7%in ***:The incidence of PCLs is rapidly *** PCLs,indeterminate cyst is increasing outstandingly.A trend of decreasing in the number of resections and increasing cancer rates among resected cysts may be attributed to the updated international guidelines.

关键词： Pancreatic cyst Incidence Prevalence Pancreatectomy Big data

Improving ionic conductivity of von-Alpen-type NASICON ceramic electrolytes via magnesium doping

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Journal of Advanced Ceramics 2023年第5期12卷 1058-1066页

作者： Il-Seop Jang Wooseok Go Bo-Ye Song Hayoung park Yun chan Kang Jinyoung Chun Emerging Materials R&D Division Korea Institute of Ceramic Engineering and Technology(KICET)Jinju 52851Republic of Korea Department of Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea Energy Storage and Distribution Resources Division Lawrence Berkeley National LaboratoryBerkeley 94720USA

NASICON (sodium (Na) superionic conductor) compounds have attracted considerable attention as promising solid electrolyte materials for advanced Na-based batteries. In this study, we investigated the improvement in ionic conductivities of von-Alpen-type NASICON (vA-NASICON) ceramic electrolytes by introducing a magnesium ion (Mg^(2+)) as a heterogeneous element. The optimal Mg-doped vA-NASICON exhibited a high ionic conductivity of 3.64×10^(−3) S·cm^(−1), which was almost 80% higher than that of un-doped vA-NASICON. The changes in physicochemical properties of the vA-NASICONs through the Mg introduction were systematically analyzed, and their effects on the ionic conductivities of the vA-NASICON were studied in detail. When the optimal ratio of Mg^(2+) was used in a synthetic process, the relative density (96.6%) and grain boundary ionic conductivity (σgb) were maximized, which improved the total ionic conductivity (σt) of the vA-NASICON. However, when Mg^(2+) was introduced in excess, the ionic conductivity decreased because of the formation of an undesired sodium magnesium phosphate (NaxMgyPO_(4)) secondary phase. The results of this study are expected to be effectively applied in the development of advanced sodium-based solid electrolytes with high ionic conductivities.

关键词： NASICON solid electrolyte von-Alpen-type magnesium(Mg)doping ionic conductivity

Dipole-assisted carrier transport in bis(trifluoromethane) sulfonamide-treated O-ReS_(2) field-effect transistor

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Nano Research 2021年第7期14卷 2207-2214页

作者： Jae Young park SangHyuk Yoo Byeongho park Taekyeong Kim Young Tea Chun Jong Min Kim Keonwook Kang Soo Hyun Lee Seong chan Jun Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Center for Biomicrosystem Brain Science InstituteKorea Institute of Science and TechnologySeoul 02792Republic of Korea Sensor System Research Center Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of Physics Hankuk University of Foreign StudiesYongin 17035Republic of Korea Division of Electronics and Electrical Information Engineering Korea Maritime and Ocean UniversityBusan 49112Republic of Korea Electrical Engineering Division Engineering Department University of CambridgeCambridgeCB3 OFAUK

We demonstrate the dipole-assisted carrier transport properties of bis(trifluoromethane)sulfonamide(TFSI)-treated O-ReS_(2) field-effect *** ReS_(2) was compared with defect-mediated ReS_(2) to confirm whether the presence of defects on the interface enhances the interaction between O-ReS_(2) and TFSI *** to the experiment,density functional theory(DFT)calculation was performed,and the result indicated that the charge transfer between TFSI and O-ReS_(2) is more sensitive to external electric fields than that between TFSI and pristine ReS_(2).After TFSI treatment,the drain current of O-ReS_(2) FET was significantly increased up to 1,113.4 times except in the range of−0.32–0.76 V owing to Schottky barrier modulation from dipole polarization of TFSI molecules,contrary to a significant degradation in device performance in pristine ReS_(2) ***,in the treated O-ReS_(2) device,the dipole direction was highly influenced by the voltage sweep direction,generating a significant area of hysteresis in I–V and transfer characteristics,which was further verified by the surface potential ***,the dipole state was enhanced according to the wavelength of the light source and *** results indicate that TFSI-treated ReS_(2) FET has large potential for use as next-generation memristor,memory,and photodetector.

关键词： Two-dimensional material ReS_(2) field-effect transistor TFSI superacid dipole

Synergic effect of sex pheromone(7R,8S)-cis-7,8-epoxy-2-methyloctadec-17-ene on(+)-disparlure of the Asian gypsy moth,Lymantria dispar, in Korea

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Journal of Forestry Research 2019年第3期30卷 1119-1122页

作者： Il-Kwon park Hyo-Rim Lee chan-Sik Jung Sang-Hyun Koh Department of Forest Sciences Seoul National University Seoul 08826Republic of Korea Research Institute of Agriculture and Life Science College of Agriculture and Life SciencesSeoul National University Seoul 08826Republic of Korea Division of Forest Insect Pests and Diseases National Institute of Forest ScienceSeoul 02455Republic of Korea

field attraction test of (7R,8S)-cis-7,8-epoxy-2- methyloctadec-17-ene (= 7R,8S-epo-2me-17ene-18Hy), a trace component of the sex pheromone gland of the Asian gypsy moth,(Lymantria dispar), traps that were baited with the trace component attracted more L. dispar than traps baited with (7S,8R)-cis-7,8-epoxy-2-methyloctadec-17-ene (= 7S,8R-epo-2me-17ene-18Hy) and unbaited traps. However, traps baited with 7R,8S-epo-2me-17ene-18Hy were less attractive than traps baited with (+)-disparlure [=(7R,8S)-cis-7,8-epoxy-2-methyloctadecane], the sex pheromone of L. dispar. Combination tests with (?)-disparlure, 7R,8S-epo-2me-17ene-18Hy, and 7S,8R-epo-2me- 17ene-18Hy revealed that 7R,8S-epo-2me-17ene-18Hy acted synergistically with (?)-disparlure.

关键词： Asian gypsy moth Lymantria dispar Sex pheromone (+)-disparlure (7R,8S)-cis-7,8-epoxy-2methyloctadec-17ene