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Journal of Wuhan University of Technology(Materials Science) 2018年第3期33卷 525-532页

作者： Kyung Do joo Do Hoon Kim Gui Yung Chung Department of Chemical Engineering Hong Ik University

Effects of operating parameters in the thermal gradient chemical vapor infiltration of propane such as thermal gradient, diffusion, infiltrations time, and concentration of propane were studied by focusing on the visualizations of the intrinsic effects of these parameters. A uniform deposition in the preform was obtained with a gradually increasing temperature along the gas flow. The uniformity of deposition through the preform got improved with increasing deposition time. Results of numerical modeling estimated the experimental data very well when the pre-exponential factor of the overall rate of carbon deposition from propane reported by Vaidyaraman[1] was multiplied by 4. The average density of a preform increased by about 3 times from 0.38 to 1.15 g/cm3 after 60 hr deposition with a thermal gradient under the conditions of 3% propane in nitrogen and 840 to 900 ℃.

关键词： TG-CVI propane C/C composites uniform deposition mathematical modeling

SYNTHESIS AND CHARACTERIZATION OF HYDROPHOBIC-HYDROPHILIC MULTIBLOCK COPOLYMERS FOR BIOMEDICAL APPLICATIONS

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Chinese Journal of Polymer Science 1999年第2期17卷 113-122页

作者： Yong Kiel Sung Yong joo Kim Sung Wan Kim Department of Chemistry College of Natural Science Dongguk University 3Ga 26 PhildongJunggu Seoul 100-715 KoreaReliability Technology Division NITQ 2 Chungangdong Kwachoncity Kyunggido 427-010 KoreaCenter for Controlled Chemical Delivery University of Utah Salt Lake City Utah 84112 U. S. A.

The synthesis and characterization of amphiphilic copolymers of poly（dimethyl siloxane）(PDMS),poly（ethylene oxide）(PEO), and heparin（Hep） were investigated. These multiblock copolymers wereidentified using;H-NMR, FTIR, end group analysis, and sulfur elemental analysis. The multiblockcopolymers were characterized by using DSC and X-ray diffractometry. The glass transition temperature,crystalline melting characteristics, annealing effect, and cold crystallization of the block copolymers weredetermined by DSC. The crystallinity of the block copolymers was also determined by X-ray diffractionmethod.

关键词： Heparinized block copolymer Biomedical polymer Synthesis Characterization

Effects of an Urban Park and Residential Area on the Atmospheric CO_2 Concentration and Flux in Seoul,Korea

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Advances in Atmospheric Sciences 2013年第2期30卷 503-514页

作者： Moon-Soo PARK Seung Jin joo Chang Seok LEE Center for Atmospheric and Environmental Modeling Seoul 151 919Korea Life and Environmental Engineering Seoul Women's UniversitySeoul 139 774Korea

The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 2011）, and the late-growing season （22-24 September 2011） were analyzed. The CO2 concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season （early spring） and a minimum value during the growing season （summer）. The CO2 flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO2 flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600-1000 LST and 1800-2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.

关键词： C02 concentration C02 flux Seoul urban forest urban residential region

Sigmoid-sigmoid colon fistula caused by diverticulitis

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Chinese Medical Journal 2022年第4期135卷 491-492页

作者： Jeonghun Lee Young joo Lee Youngsun Kim Department of Internal Medicine Ye HospitalAnyangRepublic of Korea Department of Obstetrics and Gynecology Kyung Hee University HospitalKyung Hee University College of MedicineSeoulRepublic of Korea

To the Editor:Diverticular disease is common worldwide and the incidence of this disease increases with *** diverticulitis is serious and includes abscess,fistula,obstruction,and ***,surgical treatment is recommended to the patients with symptomatic *** these,colocolic fistula caused by diverticulitis is rare findings and especially,sigmoid-sigmoid fistula is an extremely rare *** present report describes a case of sigmoid-sigmoid colon fistula caused by *** results of this case may help physicians to recognize that multidisciplinary management and surgery are needed for the treatment of complicated diverticulitis with fistula.

关键词： fistula colon obstruction

Mathematical Modeling of Flow Field in CeramicCandle Filter

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Journal of Thermal Science 1998年第2期7卷 85-88页

作者： TaewonSeo joo－HongChoi 等 SchoolofMechanicalEng. AndongNationalUniv.388Songchun－DongAndongKorea Depart.ofChemicalEng. Gyeong

Integrated gasification combined cycle (IGCC) is one of the candidates to achieve stringent environmental regulation among the clean coal technologies. Advancing the technology of the hot gas cleanupsystems is the most critical component in the development of the IGCC. Thus the aim of this study isto understand the flow field in the ceramic filter and the influence of ceramic filter in removal of theparticles contained in the hot gas flow. The numerical model based on the Reynolds stress turbulencemodel with the Darcy’s law in the porous region is adopted. It is found that the effect of the porosityin the flowfield is negligibly small while the effect of the filter length is significant. It is also found asthe permeability decreases, the reattachment point due to the flow separation moves upstream. Thisis because the fluid is sucked into the filter region due to the pressure drop before the flow separationoccurs. The particle follows well with the fluid stream and the particle is directly sucked into the filterdue to the pressure drop even in the flow separation region.

关键词： IGCC ceramic candle filter permeability porosity Reynolds stress model

Development of 3D bicontinuous metal-intermetallic composites through subsequent alloying process after liquid metal dealloying

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Journal of Magnesium and Alloys 2023年第11期11卷 4274-4281页

作者： Jee Eun Jang Jihye Seong Soo-Hyun joo Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Materials Science and Engineering Dankook UniversityCheonan 31116Republic of Korea

This study presents a novel process for the fabrication of metal-intermetallic composites with a 3D bicontinuous structure, achieved through a combination of liquid metal dealloying(LMD) and subsequent alloying. Initially, porous Ti structures are produced using the LMD process, followed by immersion in a molten Mg-3Al(wt%) metal. Due to the higher thermodynamic miscibility of Al with Ti compared to Mg, the concentration of Al in the Ti matrix increases as the immersion time increases. This results in a sequential phase transition within the Ti matrix: α-Ti → Ti_(3)Al → Ti Al. The phase transition considerably affects the hardness and strength of the composite material,with the Mg-Ti_(3)Al-Ti Al composite exhibiting a maximum hardness nearly twice as high as that of the conventional Mg-Ti composite. This innovative process holds potential for the development of various bicontinuous metal-intermetallic composites.

关键词： Liquid metal dealloying Subsequent alloying Metal–intermetallic composite 3D bicontinuous structure Hardness

Carbon Dioxide Concentration and Flux in an Urban Residential Area in Seoul,Korea

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Advances in Atmospheric Sciences 2014年第5期31卷 1101-1112页

作者： Moon-Soo PARK Seung Jin joo Soon-Ung PARK Weather Information Service Engine Center for Atmospheric Science & Earthquake ResearchSeoul 121-835 Korea Center for Atmospheric and Environmental Modeling Seoul 152-775 Korea

The carbon dioxide （CO2） concentrations and fluxes measured at a height of 17.5 m above the ground by a sonic anemometer and an open-path gas analyzer at an urban residential site in Seoul, Korea from February 2011 to January 2012 were analyzed. The annual mean CO2 concentration was found to be 750 mg m-3, with a maximum monthly mean concentration of 827 mg m-3 in January and a minimum value of 679 mg m-3 in August. Meanwhile, the annual mean CO2 flux was found to be 0.45 mg m-2 s-1, with a maximum monthly mean flux of 0.91 mg m-2 s-1 in January and a minimum value of 0.19 mg m-2 s-1 in June. The hourly mean CO2 concentration was found to show a significant diurnal variation; a maximum at 0700-0900 LST and a minimum at 1400-1600 LST, with a large diurnal range in winter and a small one in summer, mainly caused by diurnal changes in mixing height, CO2 flux, and surface complexity. The hourly mean CO2 flux was also found to show a significant diurnal variation, but it showed two maxima at 0700-0900 LST and 2100-2400 LST, and two minima at 1100-1500 LST and 0300-0500 LST, mainly caused by a diurnal pattern in CO2 emissions and sinks from road traffic, domestic heating and cooking by liquefied natural gas use, and the different horizontal distribution of CO2 sources and sinks near the site. Differential advection with respect to wind direction was also found to be a cause of diurnal variations in both the CO2 concentration and flux.

关键词： CO2 concentration CO2 flux liquefied natural gas (LNG) Seoul urban residential area

Highly Stable Silicon–Carbon–Nitrogen Composite Anodes from Silsesquiazane for Rechargeable Lithium-Ion Battery

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Journal of Materials Science & Technology 2016年第3期32卷 195-199页

作者： Yong Seok Kim Yong L.joo Young-Je Kwark School of Chemical & Biomolecular Engineering Cornell University Department of Organic Materials and Fiber Engineering Soongsil University

Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.

关键词： Polymer-derived ceramics Silsesquiazane Lithium ion battery Lithium ion conductivity

Evaluation of lubrication performance of crank pin bearing in a marine diesel engine

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Friction 2018年第4期6卷 464-471页

作者： Suk Man MOON Yong joo CHO Tae Wan KIM School of Mechanical Engineering Pusan National University Department of Mechanical Engineering Pukyong National University

In this study, the lubrication performance of the crank pin bearing in a marine two–stroke diesel engine is evaluated to investigate the adhesional failure on the crank pin bearing. A numerical algorithm for the lubrication analysis considering motion analysis of the crank pin system is developed. The film pressure and thickness for three clearances and three lubricant temperatures are calculated. The results show that the lubricant temperature has a higher effect on film thickness than clearance. In terms of the film parameter, the operating condition that can result in solid–solid contact is investigated. We also suggest the desirable operating conditions of clearance and lubricant temperature to prevent the solid–solid contact.

关键词： crank pin bearing film thickness lubricant film parameter diesel engine

Direct dynamic-simulation approach to trajectory optimization

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Chinese Journal of Aeronautics 2021年第10期34卷 6-19页

作者： Sung Wook HUR Seong Han LEE Yong Hyeon NAM Chang-joo KIM Department of Aerospace Information Engineering Konkuk UniversitySeoul 05029Republic of Korea

This paper proposes a new direct method for an efficient trajectory optimization using the point that the dynamics of a deterministic system are uniquely determined by initial states and controls imposed over the time horizon of *** effectively implement this concept,the Hermite spline is adopted to interpolate the continuous controls and the system dynamics are integrated with corresponding control parameters in *** a result,the optimal control problem can be transcribed into a nonlinear programming problem which has no dynamic equality constraints and no intermediate states in its design *** addition,the paper proposes an efficient recursive Jacobian estimation technique and introduces a Jacobian transformation matrix to straightforwardly handle the general state *** properties of the present method are thoroughly investigated through its applications to the trajectory optimization for a soft lunar landing from a parking orbit,including the detailed analyses for the de-orbiting *** computed results are compared with those using the pseudo-spectral method to demonstrate an extreme outperformance of the proposed method in the aerospace applications over the traditional direct method.

关键词： Trajectory optimization Direct method Hermite spline interpolation Pseudo-spectral integrator Soft lunar landing