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Rare Metals 2020年第7期39卷 767-783页

作者： Inhee Choi Hyeon Kyeong lee gyoung woo lee Jiyull Kim Ji Bong Joo Department of Life Science University of SeoulSeoul 02504Republic of Korea Division of Chemical Engineering Konkuk UniversitySeoul 05029Republic of Korea

In this article,we review the recent progress and our research activity on the synthesis of inorganic shell nanostructures to enhance the catalytic performance and stability of metal nanoparticles in catalytic ***,we introduce general synthetic strategies for the fabrication of inorganic nanoscale shell layers,including template-assisted sol-gel coating,hydrothermal(or solvothermal)synthesis and the self-templating *** also discuss recent examples of metal nanoparticles(NPs)with nanoscale shell layers,namely core-shell,yolk-shell and multiple NPs-embedded nanoscale *** then discuss the performance and stability of metal particles in practical catalytic ***,we conclude with a summary and perspective on the further progress of inorganic nanostructure with nanoscale shell layers for catalytic applications.

关键词： Nanostructures Inorganic shell Metal nanoparticle Stabilization Performance enhancement Catalyst

Intermediate-scale Analysis of Landscape Characteristics Affecting Edge Formation in Burned Forests in Samcheok,Korea

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Journal of Mountain Science 2014年第2期11卷 384-397页

作者： Sang-woo lee Myoung-Soo WON Joo-Mee lee Hai-gyoung KIM Department of Design Konkuk University Kwangjin-Gu Hwayang-DongSeoul 143-701 South Korea Division of Forest Disaster and Fire prevention Korea Forest Research Institute Graduate Program Department of Landscape Architecture & Urban Planning Texas A&M University College Station Yirakjae Landscape Studio Songdong-Gu Hongik-Dong 210Seoul 133-880 South Korea

Compared to burn interiors, edges exhibit distinct biotic and abiotic conditions that include microclimate, wind speed, sunlight levels, soil composition, moisture content, nutrient availability, population density, and species diversity. This study characterized the landscapes in which burned forest edges formed in Samcheok, Korea. Over the study area, 500-m2 grid cells were generated to capture landscape characteristics. Grid cells intersecting burn boundary lines were designated as edge, while cells without these lines were classified as the interior of burned areas. Topographic variables including slope, elevation, topographic wetness index, solar radiation index, and proportions of fuel and land use types within grid cells were computed in a geographical information system(GIS). Correlation analysis with modified t-test and regression tree analysis were performed to explore the influences of landscape variables on edge formation with avoiding spatial autocorrelation problems. The results indicated that edges formed at low elevations with mild slopes, high topographic wetness, and low solar radiation. Edges were unlikely to form in areas dominated by Japanese red pines at low elevations. Moreover, heterogeneous land use/cover types contributed significantly to edge formation. Different forest management strategies for different landscape conditions can be more effective for enhancing resilience of forests to fire. Reducing susceptible fuel types might be effective at low elevations, while enhancing forest heterogeneity might be more effective at high elevations.

关键词： Forest fire Modified t-test, Edge formation Fuel type Topographic characteristics

Crystal Facet Engineering of TiO_(2) Nanostructures for Enhancing Photoelectrochemical Water Splitting with BiVO_(4) Nanodots

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Nano-Micro Letters 2022年第3期14卷 201-215页

作者： Mi gyoung lee Jin wook Yang Hoonkee Park Cheon woo Moon Dinsefa M.Andoshe Jongseong Park Chang‑Ki Moon Tae Hyung lee Kyoung Soon Choi woo Seok Cheon Jang‑Joo Kim Ho Won Jang Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Republic of Korea Department of Chemistry and Nanoscience Ewha Womans UniversitySeoul 03693Republic of Korea National Research Facilities and Equipment Center Korea Basic Science InstituteDaejeon 34133Republic of Korea Advanced Institute of Convergence Technology Seoul National UniversitySuwon 16229Republic of Korea

Although bismuth vanadate(BiVO4)has been promising as photoanode material for photoelectrochemical water splitting,its charge recombination issue by short charge diffusion length has led to various studies about heterostructure *** a hole blocking layer of BiVO4,titanium dioxide(TiO_(2)) has been considered unsuitable because of its relatively positive valence band edge and low electrical ***,a crystal facet engineering of TiO_(2) nanostructures is proposed to control band structures for the hole blocking layer of BiVO4 *** design two types of TiO_(2) nanostructures,which are nanorods(NRs)and nanoflowers(NFs)with different(001)and(110)crystal facets,respectively,and fabricate BiVO4/TiO_(2) heterostructure *** BiVO4/TiO_(2) NFs showed 4.8 times higher photocurrent density than the BiVO4/TiO_(2) *** decay time analysis and time-resolved photoluminescence reveal the enhancement is attributed to the reduced charge recombination,which is originated from the formation of type II band alignment between BiVO4 nanodots and TiO_(2) *** work provides not only new insights into the interplay between crystal facets and band structures but also important steps for the design of highly efficient photoelectrodes.

关键词： Crystal facet control Bismuth vanadate Titanium dioxide Heterojunction Water splitting

Diamond machining of sinusoidal grid surface using fast tool servo system for fabrication of hydrophobic surface

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中国有色金属学会会刊：英文版 2012年第S3期22卷 787-792页

作者： Hong LU Deug-woo lee Sang-Min lee Jeong-woo PARK Department of Nano Fusion Technology Pusan National University Department of Nano Mechatronics Engineering Pusan National University Department of Mechanical Design Engineering Chosun University

Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in *** results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining *** properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.

关键词： fast tool servo system diamond turning sinusoidal grid surface UV-moulding contact angle

Tailored BiVO_(4)/In_(2)O_(3)nanostructures with boosted charge separation ability toward unassisted water splitting

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Carbon Energy 2023年第6期5卷 45-59页

作者： Mi gyoung lee Jin wook Yang Ik Jae Park Tae Hyung lee Hoonkee Park woo Seok Cheon Sol Alee Hyungsoo lee Su Geun Ji Jun Min Suh Jooho Moon Jin Young Kim Ho Won Jang Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoulRepublic of Korea Country Department of Applied Physics Sookmyung Women's UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Yonsei UniversitySeoulRepublic of Korea Advanced Institute of Convergence Technology Seoul National UniversitySuwonRepublic of Korea

The development of new heterostructures with high photoactivity is a breakthrough for the limitation of solar-driven water ***,we first introduce indium oxide(In_(2)O_(3))nanorods(NRs)as a novel electron transport layer for bismuth vanadate(BiVO_(4))with a short charge diffusion ***_(2)O_(3)NRs reinforce the electron transport and hole blocking of BiVO_(4),surpassing the state-of-the-art photoelectrochemical performances of BiVO_(4)-based ***,a tannin-nickel-iron complex(TANF)is used as an oxygen evolution catalyst to speed up the reaction *** final TANF/BiVO_(4)/In_(2)O_(3)NR photoanode generates photocurrent densities of 7.1 mAcm^(−2) in sulfite oxidation and 4.2 mA cm^(−2) in water oxidation at 1.23 V versus the reversible hydrogen ***,the“artificial leaf,”which is a tandem cell with a perovskite/silicon solar cell,shows a solar-to-hydrogen conversion efficiency of 6.2%for unbiased solar water *** reveal significant advances in the photoactivity of TANF/BiVO_(4)/In_(2)O_(3)NRs from the tailored nanostructure and band structure for charge dynamics.

关键词： bismuth vanadate heterojunction indium oxide nanostructure photoelectrochemical water splitting

Dynamic Behavior and Deformation Analysis of the Fish Cage System Using Mass-Spring Model

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China Ocean Engineering 2015年第3期29卷 311-324页

作者： Chun woo lee Jihoon lee Subong PARK Division of Marine Production System Management Pukyong National University Division of Marine Technology Chonnam National University Department of Fisheries Physics Pukyong National University

Fish cage systems are influenced by various oceanic conditions, and the movements and deformation of the system by the external forces can affect the safety of the system itself, as well as the species of fish being cultivated. Structural durability of the system against environmental factors has been major concern for the marine aquaculture system. In this research, a mathematical model and a simulation method were presented for analyzing the performance of the large-scale fish cage system influenced by current and waves. The cage system consisted of netting, mooring ropes, floats, sinkers and floating collar. All the elements were modeled by use of the mass-spring model. The structures were divided into finite elements and mass points were placed at the mid-point of each element, and mass points were connected by springs without mass. Each mass point was applied to external and internal forces, and total force was calculated in every integration step. The computation method was applied to the dynamic simulation of the actual fish cage systems rigged with synthetic fiber and copper wire simultaneously influenced by current and waves. Here, we also tried to find a relevant ratio between buoyancy and sinking force of the fish cages. The simulation results provide improved understanding of the behavior of the structure and valuable information concerning optimum ratio of the buoyancy to sinking force according to current speeds.

关键词： fish cage mathematical model aquaculture computer simulation mass-spring model

Efficient multi-response adaptive sampling algorithm for construction of variable-fidelity aerodynamic tables

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Chinese Journal of Aeronautics 2019年第3期32卷 547-558页

作者： Maxim TYAN Jae-woo lee Department of Aerospace Information Engineering Konkuk University

Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-response adaptive sampling algorithm for simultaneous construction of multiple surrogate models in a time-efficient and accurate manner. The new algorithm uses the Jackknife cross-validation variance and a minimum distance metric to construct a sampling criterion function. A weighted sum of the function is used to consider the characteristics of multiple surrogate models. The proposed algorithm demonstrates good performance on total 22 numerical problems in comparison with three existing adaptive sampling algorithms. The numerical problems include several two-dimensional and six-dimensional functions which are combined into singleresponse and multi-response systems. Application of the proposed algorithm for construction of aerodynamic tables for 2 D airfoil is demonstrated. Scaling-based variable-fidelity modeling is implemented to enhance the accuracy of surrogate modeling. The algorithm succeeds in constructing a system of three highly nonlinear aerodynamic response surfaces within a reasonable amount of time while preserving high accuracy of approximation.

关键词： Adaptive sampling Aerodynamic database Multi-response system Surrogate modeling Variable fidelity modeling

Characteristics of machined surface controlled by cutting tools and conditions in machining of brittle material

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中国有色金属学会会刊：英文版 2009年第B9期19卷 194-201页

作者： Yong-woo KIM Soo-Chang CHOI Jeung-woo PARK Deug-woo lee Department of Nano Fusion Technology Pusan National University Department of Mechanical Design Engineering Chosun University Department of Nanosystem and Nanoprocess Engineering Pusan National University

One of the ultra-precision machining methods was adapted for brittle material as well as soft material by using multi-arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because the particles of grinding tools are irregular size and material can be fragile. Therefore, we were able to design tool paths and machine controlled pattern on surface by multi-arrayed diamond tips with uniform size made in MEMS fabrication and high speed spindle, and the maximum speed was about 3×105 r/min. We defined several parameters that can affect the machining surface. Those were multi-array of diamond tips (n×n), speed of air spindle and feeding rate. The surface roughness and surface texture can be controlled by those parameters for micro machining.

关键词：加工表面脆性材料条件控制刀具路径表面粗糙度特征高速主轴加工方法

Improvement in Background Error Covariances Using Ensemble Forecasts for Assimilation of High-Resolution Satellite Data

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Advances in Atmospheric Sciences 2011年第4期28卷 758-774页

作者： Seung-woo lee Dong-Kyou lee School of Earth and Environmental Sciences Seoul National University

Satellite data obtained over synoptic data-sparse regions such as an ocean contribute toward improving the quality of the initial state of limited-area models. Background error covariances are crucial to the proper distribution of satellite-observed information in variational data assimilation. In the NMC （National Meteorological Center） method, background error covariances are underestimated over data-sparse regions such as an ocean because of small differences between different forecast times. Thus, it is necessary to reconstruct and tune the background error covariances so as to maximize the usefulness of the satellite data for the initial state of limited-area models, especially over an ocean where there is a lack of conventional data. In this study, we attempted to estimate background error covariances so as to provide adequate error statistics for data-sparse regions by using ensemble forecasts of optimal perturbations using bred vectors. The background error covariances estimated by the ensemble method reduced the overestimation of error amplitude obtained by the NMC method. By employing an appropriate horizontal length scale to exclude spurious correlations, the ensemble method produced better results than the NMC method in the assimilation of retrieved satellite data. Because the ensemble method distributes observed information over a limited local area, it would be more useful in the analysis of high-resolution satellite data. Accordingly, the performance of forecast models can be improved over the area where the satellite data are assimilated.

关键词： 3DVAR background error covariances retrieved satellite data assimilation ensemble forecasts.

Estimation of genetic parameters on growth characteristics of a 35-year-old Pinus koraiensis progeny trial in South Korea

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Journal of Forestry Research 2021年第5期32卷 2227-2236页

作者： Kyungmi lee In Sik Kim Seok woo lee Division of Forest Tree Improvement Department of Forest BioresourcesNational Institute of Forest ScienceSuwonRepublic of Korea

The effects of genetic and environmental factors on Pinus koraiensis growth were studied based on a35 year-old progeny trial composed of open-pollinated offspring of twenty-one plus ***,DBH and volume of the offspring was analyzed using restricted maximum likelihood/best linear unbiased prediction in mixed model *** site and family effects on the three traits were *** distinct growth of offspring by site with disparate climates corroborated the importance of planting species in suitable *** differences by family was significant,emphasizing the importance of identifying families with either superior or inferior *** parental ranking was assigned in the sites,inferring the breeding value of each plus *** estimates of individual heritability(h_(i)^(2))of height,DBH and volume growth were 0.169-0.645,0.108-0.331 and 0.129-0.343 respectively,with higher h_(i)^(2) of the height than DBH on each *** of variance of genetic effect was higher with DBH in some cases,indicating the scope for selection is larger for this trait despite the lower heritability compared to *** the variation between families in terms of the performance stability across sites,consideration of the genotype by environment interaction is required in selecting materials to be used in reforestation with Korean pine.A few families with either superior or inferior performance retained their parental ranking for at least a *** families with increased growth on a particular site were identified,indicating their high breeding value and low *** in the genetic performance of the families by site requires delineation of the breeding region of the species.

关键词： Pinus koraiensis Genetic parameters Genotype by environment interaction Tree improvement Progeny trial