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Thermal-environment characteristics and comfort of combined radiant-floor (Korean heating system ondol) and convective cooling system

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Journal of Central South University 2013年第12期20卷 3589-3603页

作者： LEE kang-guk HONG Won-Hwa School of Architecture Kyungpook National University

The thermal-environment characteristics of the existing forced-convection cooling system were compared with those of the convective cooling system, which combined the radiant-floor cooling system using floor-heating panel typically applied to apartments in South Korea with the forced-convection cooling system using improved fan coil unit. The subjective warm/cool-feeling responses to the combined radiant-floor and convective cooling system in the questionnaire survey conducted among the test subjects were analyzed to establish the basic data for the combined cooling system. The results show that in the thermal-equilibrium condition, the vertical air temperature difference in the model living room is larger in the forced-convection-cooling condition. Most of the subjects feel a proper warm/cool feeling on their entire body, but they feel colder on the foot and lower body in the combined-cooling condition.

关键词： convection cooling temperature ondol thermal comfort fan coil unit combined cooling system

Characteristics of bifurcation and buckling load of space truss in consideration of initial imperfection and load mode

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第3期14卷 206-218页

作者： Su-deok SHON Seung-jae LEE kang-guk LEE School of Architectural Engineering Korea University of Technology and Education1800 ChungjeolroCheonan ChungnamRepublic of Korea Research Center for Urban Affair Kyungil UniversityGyeongsan-city GyeongbukRepublic of Korea

This study investigated characteristics of bifurcation and critical buckling load by shape imperfection of space truss,which were sensitive to initial *** critical point and buckling load were computed by the analysis of the eigenvalues and determinants of the tangential stiffness *** two-free-nodes example and star dome were selected for the case study in order to examine the nodal buckling and global buckling by the sensitivity to the eigen buckling mode and the analyses of the influence,and characteristics of the parameters as defined by the load ratio of the center node and surrounding node,as well as rise-span ratio were *** sensitivity to the imperfection of the initial shape of the two-free-nodes example,which occurs due to snapping at the critical point,resulted in bifurcation before the limit point due to the buckling mode,and the buckling load was reduced by the increase in the amount of *** two sensitive buckling patterns of the numerical model are established by investigating the displaced position of the free nodes,and the asymmetric eigenmode greatly influenced the behavior of the imperfection shape whether it was at limit point or ***,the sensitive mode of the two-free-nodes example was similar to the in-extensional basis mechanism of a simplified *** star dome,which was used to examine the influence among several nodes,indicated that the influence of nodal buckling was greater than that of global buckling as the rise-span ratio was ***,global buckling is occurred with reaching bifurcation point as the value of load ratio was higher,and the buckling load level was about 50%-70% of load level at limit point.

关键词： Space truss Geometric nonlinearity Initial imperfection Snap-through Bifurcation Global buckling

Sensitivity to electricity consumption in urban business and commercial area buildings according to climatic change

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Journal of Central South University 2012年第3期19卷 770-776页

作者： LEE kang-guk KIM Sung-bum HONG Won-hwa Research Center for Urban Affair Kyungil University School of Architecture Kyungpook National University

Recently, urban high temperature phenomenon has become a problem which results from human activities, the increase in energy consumption, and land-cover change in urban areas. As extremely hot weather caused by urban high temperature continues, demand for power is increased and results in the degradation of electricity reserves. The current trend in climate change, regardless of the summer and winter power demand, is likely to have much effect on the power demand. Thus, sensitivity to electricity consumption in urban areas due to climate change was researched. The results show that, 1） the basic unit of the sensitivity to electricity consumption in the target areas is 1.25-1.58W/（m2.℃）; 2） The maximum sensitivity is recorded at around 8：00 pm in the area crowded with commercial and business area. And in the business area, electricity consumption load is even from 9：00 am to 6：00 pm.

关键词： electricity consumption electricity load electricity reserves energy

Analyses on performances of heat and multilayer reflection insulators

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Journal of Central South University 2012年第6期19卷 1645-1656页

作者： LEE Moo-jin LEE kang-guk SEO Won-duck School of Architecture Kyungil UniversityGyeongsan 702701Korea Research Center for Urban Affair Kyungil UniversityGyeongsan 702701Korea Department of Architectural Design Joongbu UniversityGeumsan-gun 701140Korea

This research was conducted to study the performances of the heat and multilayer reflection insulators used for buildings in South Korea to realize eco-friendly, low-energy-consumption, green construction, and to contribute to energy consumption reduction in buildings and to the nation＇s greenhouse gas emission reduction policy （targeting 30% reduction compared to BAUCousiness as usual） by 2020）. The heat insulation performance test is about the temperatures on surfaces of test piece. The high air temperature and the low air temperature were measured to determine the overall heat transfer coefficient and thermal conductivity. The conclusions are drawn that the heat transmission coefficients for each type of existing reflection insulator are： A-1 （0.045 W/（m-K））, A-2 （0.031 W/（m.K））, A-3 （0.042 W/（m.K））, A-4 （0.078 W/（m.K））, and the average heat conductivity is 0.049 W/（m-K）; The heat conductivity for each type of Styrofoam insulator are 0.030 W/（m.K） for B-l, 0.032 W/（m-K） for B-2, 0.037 W/（m＇K） for B-3, 0.037 W/（m.K） for B-4, and the average heat conductivity is 0.035 W/（m＇K） regardless of the thickness of the insulator; The heat conductivity values of the multilayer reflection insulators are converted based on the thickness and type C-1 （0.020 W/（m.K））, C-2 （0.018 W/（m.K））, C-3 （0.016 W/（m.K））, and C-4 （0.012 W/（m.K））; The multilayer reflection insulator keeps the indoor-side surface temperature high （during winter） or low （in summer）, enhances the comfort of the building occupants, and conducts heating and moisture resistance to prevent dew condensation on the glass-outer-wall surface.

关键词： heat reflection insulator multilayer reflection insulator overall heat transfer coefficient thermal conductivity nonflammability vapor permeability eco-friendly construction

Smooth cutting pattern generation technique for membrane structures using geodesic line on subplane and spline interpolation

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Journal of Central South University 2013年第11期20卷 3131-3141页

作者： SHON Su-deok LEE Seung-jae LEE kang-guk School of Architectural Engineering Korea University of Technology and Education Research Center for Building safety Kyungpook National University

Practical techniques for smooth geodesic patterning of membrane structures were *** the geodesic search,adjustment of the subplane of the extracted elements series was proposed,and various spline approximation methods were used to flatten the strip for the generation of a smooth *** search approach is very simple,and the geodesic line could be easily attained by the proposed method without the need for a difficult computation *** cutting patterning can also be generated by spline approximation without the noise in discrete nodal ***,the geodesic cutting pattern saved about 21%of the required area for the catenary model due to the reduction of the curvature of the planar pattern seam line.

关键词： membrane structures cutting pattern generation geodesic line spline interpolation triangular mesh sub-plane

Stable operation of highly loaded pure Si-Fe anode under ambient pressure via carboxy silane-directed robust solid electrolyte interphase

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Journal of Energy Chemistry 2024年第7期94卷 568-576页

作者： Guntae Lim Dong guk kang Hyeon Gyu Lee Yen Hai Thi Tran Kihun An Junghyun Choi Kwang Chul Roh Do Youb Kim Seung-Wan Song Department of Chemical Engineering&Applied Chemistry Chungnam National University Daejeon 34134Republic of Korea Energy Storage Materials Center Korea Institute of Ceramic Engineering&TechnologyJinju 52851Republic of Korea Advanced Energy Materials Research Center Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea

Incorporation of higher content Si anode material beyond 5 wt% to Li-ion batteries(LIBs)is challenging,owing to large volume change,swelling,and solid electrolyte interphase(SEI)instability ***,a strategy of diacetoxydimethylsilane(DAMS)additive-directed SEI stabilization is proposed for a stable operation of Si-0.33FeSi_(2)(named as Si-Fe)anode without graphite,which provides siloxane inorganics and organics enrichment that compensate insufficient passivation of fluoroethylene carbonate(FEC)additive and reduce a dependence on *** stable cycling performance of highly loaded(3.5 mA h cm^(-2))pure Si-Fe anode is achieved with 2 wt%DAMS combined with 9 wt%FEC additives under ambient pressure,yielding high capacity 1270 mA h g^(-1)at 0.5 C and significantly improved capacity retention of 81% after 100 cycles,whereas short circuit and rapid capacity fade occur with FEC only ***-directed robust SEI layer dramatically suppresses swelling and particles crossover through separator,and therefore prevents short circuit,demonstrating a possible operation of pure Si or Sidominant anodes in the next-generation high-energy-density and safe LIBs.

关键词： High-energy Li-ion battery Pure Si-Fe anode without graphite Silane additive SEI layer Suppressed swelling

Gastric intestinal metaplasia development in African American predominant United States population

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World Journal of Gastrointestinal Endoscopy 2022年第10期14卷 597-607页

作者： Akram I Ahmad Arielle Lee Claire Caplan Colin Wikholm Ioannis Pothoulakis Zaynab Almothafer NishthaRaval Samantha Marshall Ankit Mishra Nicole Hodgins in guk kang Raymond K Chang Zachary Dailey Arvin Daneshmand Anjani Kapadia Jae Hak Oh Brittney Rodriguez Abhinav Sehgal Matthew Sweeney Christopher B Swisher Daniel F Childers Corinne O'Connor Lynette M Sequeira Won Cho Department of Internal Medicine MedStar Washington Hospital CenterWashingtonDC 20010United States Department of Internal Medicine Georgetown University School of MedicineWashingtonDC 20007United States Department of Gastroenterology and Hepatology INOVA Medical SystemLeesburgVA 20176United States

BACKGROUND Gastric cancer significantly contributes to cancer mortality *** intestinal metaplasia(GIM)is a stage in the Correa cascade and a premalignant lesion of gastric *** natural history of GIM formation and progression over time is not fully ***,there are no clear guidelines on GIM surveillance or management in the United *** To investigate factors associated with GIM development over time in African American-predominant study *** This is a retrospective longitudinal study in a single tertiary hospital in Washington *** retrieved upper esophagogastroduodenoscopies(EGDs)with gastric biopsies from the pathology department database from January 2015 to December *** included in the study had undergone two or more EGDswith gastric *** with no GIM at baseline were followed up until they developed GIM or until the last available *** criteria consisted of patients age<18,pregnancy,previous diagnosis of gastric cancer,and missing data including pathology results or endoscopy *** study population was divided into two groups based on GIM *** and multivariate Cox regression was used to estimate the hazard induced by patient demographics,EGD findings,and Helicobacter pylori(***)status on the GIM *** Of 2375 patients who had at least 1 EGD with gastric biopsy,579 patients were included in the study.138 patients developed GIM during the study follow-up period of 1087 d on average,compared to 857 d in patients without GIM(P=0.247).The average age of GIM group was 64 years compared to 56 years in the non-GIM group(P<0.001).In the GIM group,adding one year to the age increases the risk for GIM formation by 4%(P<0.001).Over time,African Americans,Hispanic,and other ethnicities/races had an increased risk of GIM compared to Caucasians with a hazard ratio(HR)of 2.12(1.16,3.87),2.79(1.09,7.13),and 3.19(1.5,6.76)*** gender difference was obse

关键词： Gastric intestinal metaplasia Gastric cancer Helicobacter pylori Retrospective longitudinal study Esophagogastroduodenoscopy African American population

The influence of thermohaline fronts on chlorophyll a concentrations during spring and summer in the southeastern Yellow Sea

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Acta Oceanologica Sinica 2013年第9期32卷 82-90页

作者： JANG Pung-guk LEE Tong Sup kang Jung-Hoon SHIN Kyoungsoon Korea Institute of Ocean Science and Technology/South Sea Institute Department of Oceanography College of Natural SciencesPusan National University

A spatial and temporal variation in physiochemical parameters in the southeastern Yellow Sea （YS） is in- vestigated in the spring and summer of 2009 to 2011. Nutrient show a strong negative relationship with chlorophyll a （Chl a） concentration in spring, and the subsurface chlorophyll a maxima （SCM） layer was associated with the nitracline in summer. In summer, the SCM was usually found within or above the pyc- nocline and at the depths of shoals from the open sea to the coastal sea due to tidal and/or topographical fronts in the southernmost study area. High Chl a concentrations were found in the central southern YS, where the YS cold water layer expanded under the pycnocline and encountered water masses during spring and summer. After a typhoon in the summer of2011, Chl a concentration increased, especially in the central southern YS, where cold waters occurred below the pycnocline. The results suggest that the development of thermohaline fronts may play an important role in the growth and accumulation of phytoplankton biomass in the upper layer of the southeastern YS during spring and summer.

关键词： Yellow Sea Cold Water nutrient chorophyll a thermohaline front

Aging Behavior of Mg-Y-Zr and Mg-Nd-Zr Cast Alloys

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Journal of Materials Science & Technology 2008年第1期24卷 80-84页

作者： Yang-Do Kim Nam-Hyun kang Il-guk Jo Kyung-Hyun Kim In-Bae Kim School of Materials Science and Engineering Pusan National University 30 Jangjun-dongGeumjeong-guBusan 609-735Korea Deptartment of Materials Engineering Korea Institute of Machinery & Materials 66 Sangnam-dongChangwonGyeongsangnam-do 641-010Korea

Aging behavior of Mg-3.6Y-0.5Zr and ***-0.5Zr alloys was investigated by microhardness measurement and transmission electron *** the case of Mg-Y-Zr alloy,the presence ofβ″phase,a major strength- ener,having base centered orthorhombic structure with its lattice constants of a-（β″）=0.64 nm,b-（β″）=2.22 nm, and c-（β″）=0.52 nm was *** the case of Mg-Nd-Zr alloy aged at 250℃,the presence ofβ″andβ′phases was *** crystal structure ofβ″phase was found to be DO-（19） and its orientation relationships with Mg matrix were [0001]-（β″）//[0001]-（Mg） and [01（？）0]-（β″）//[01（？）0]-（Mg）.Theβ′phase had face centered cubic structure and its orientation relationships with Mg matrix were [011]-（β′）//[0001]-（Mg） and [（？）1（？）]β′//[（？）110]）-（Mg）. The ***-0.5Zr alloy showed higher hardness compared with Mg-3.6Y-0.5Zr alloy.

关键词： Mg-Y-Zr alloy Mg-Nd-Zr alloy Precipitation sequence