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Feasibility Study of R134a/R404a Cascade Heat Pump Cycle in Heat Pump Dryers with Electrical Heaters at Low Temperatures

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Journal of Thermal Science 2015年第5期24卷 463-467页

作者： Ji woo Jeong Young lim Lee Dept. of Mechanical Engineering Kongju National University Dept. of Mechanical and Automotive Engineering Kongju National University

Heat pump cycles have been widely applied to dryers for their high efficiency. However, low–efficiency electrical heaters are often used during early drying stage for frozen foods or winter since a standard heat pump cycle cannot operate at low temperature. This study introduced cascade heat pumps replacing electrical heaters to improve dryer performance at low temperatures. Experiments were performed to examine changes in performance of the cascade heat pump dryers in relation to ambient temperature, low-stage cycle mass flow rate, and high-stage cycle mass flow rate. The results showed a significant improvement in low-temperature dryer performance with the introduction of cascade heat pump cycles.

关键词： Cascade cycle R134a/R404a Heat pump dryer COP Energy efficiency

CaCO_3 film synthesis from ladle furnace slag: morphological change, new material properties, and Ca extraction efficiency

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International Journal of Minerals,Metallurgy and Materials 2018年第12期25卷 1447-1456页

作者： Seung-woo Lee Yong-Jae Kim Jun-Hwan Bang Soochun chae Center for carbon mineralization Korea Institute of Geosciences and Mineral Resources Frontier in extreme physics Korea Research Institute of Standards and Science

A rapidly air-cooled ladle furnace slag(RA-LFS), which is a type of steelmaking slag discharged from a steel mill, was used to synthesize CaCO_3 film. The CaCO_3 film with 35 cm^2 of surface area was synthesized under atmospheric conditions, and the surface morphology of the CaCO_3 films was changed by using additives(CaCl_2 and ethylene glycol). Especially, the addition of CaCl_2 changed the surface morphology of CaCO_3 film with pore and induced new material properties, such as water adsorption. The(012) face of CaCO_3 film(calcite) was rapidly decreased by the addition of CaCl_2. The major components of RA-LFS were calcium(type of CaO, 53.9 wt%) and aluminum(type of Al_2 O_3, 37.9 wt%), and the major crystal phases of RA-LFS were C_3 S, C_(12) A_7, and C_3 A. The calcium extraction efficiency of RA-LFS was significantly increased after the CaCO_3 film synthesis. The material properties(hardness and elastic modulus) and the thermal characteristics of the CaCO_3 films were analyzed by nano-indentation and thermogravimetry–differential thermal analysis. The synthesized CaCO_3 films from RA-LFS and Ca(OH)_2(reagent) showed similarities in terms of their material properties and the decomposition temperature.

关键词： carbon dioxide ladle furnace slag carbonation calcium carbonate film calcium efficiency

Total Particulate Matter and Wound Healing: An in vivo Study with Histological Insights

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Biomedical and Environmental Sciences 2009年第4期22卷 278-287页

作者： SOHAIL EJAZ MUHAMMAD ASHRAF MUHAMMAD NAWAZ chae wooNG lim Department of Clinical Neurosciences Neurology Unit Addenbrookes Hospital University of Cambridge Angiogenesis and Toxicology Research Laboratory Department of Toxicology and Pharmacology University of Veterinary and Animal Sciences Biosafety Research Institute and College of Veterinary Medicine Chonbuk National University

Objectives Wound healing in the skin is a multifarious orchestration of cellular processes and cigarette smoking may be a cause for delayed wound healing. The aim of this study was to investigate the plausible association between exposures of cigarette total particulate matter （TPM） and wound healing. Methods An in vivo wound healing model of mice was established for determination of assorted events of wound healing, dermal matrix regeneration, re-epithelialization, and neovascularization. A total of 72 adult mice, separated in eight groups, were exposed to TPM for 12 days. Results A highly considerable diminution in wound closure （P〈0.001） was pragmatic among all TPM-treated mice from day 6 to day 8 post-wounding. Histological investigations unveiled a noteworthy impede in the outcome of re-epithelialization, dermal matrix regeneration and maturation of collagen bundles among all TPM-exposed wounds. Delayed commencement of neovascularization was pragmatic among all TPM-treated mice, on day 12 post wounding. Abbot curve, angular spectrum, and other different parameters of 3D surface behavior of wounds revealed a very highly significant reduction （P〈0.001） in angiogenesis on days 6 and 8 post-wounding, which points that application of TPM instigates extensive delay in trigging the progression of angiogenesis, resulting in delayed onset of wound healing. Conclusion Our annotations validate the damaging effects of TPM on wound healing and excessive use of TPM may lead to the production of chronic wounds and oral ulcers.

关键词： Cigarette Total particulate matter Wound healing Re-epithelialization Angiogenesis

MAINTENANCE OF MULTI-STATE PRODUCTION SYSTEMS DETERIORATED BY RANDOM SHOCKS AND PRODUCTION

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Journal of Systems Science and Systems Engineering 2011年第1期20卷 110-118页

作者： Won Seok YANG Dae E.lim Kyung C.chae Department of Business Administration Hannam University Department of Industrial and Systems Engineering

We consider the preventive maintenance of a production system that is deteriorated by random shocks and the production process itself. The degree of deterioration is modeled by discrete and finite states. Shocks arrive according to a Poisson process and deteriorate the system by random amounts. The system may deteriorate whenever it produces an item. The system is continuously monitored and repaired if the system state is at or above a predetermined level for maintenance. We analyze the lifetime, product quantity, average cost, and average profit considering revenue from the product and cost due to setup, operation, and repair. Assuming a structure of system parameters and costs, using numerical examples, we investigate the impact of production and shock arrivals on the average profit and the optimal maintenance level that maximizes the average profit. The proposed model is applicable to manufacturing tasks in which machines wear due to production, for example, press processes, milling, turning, punching, and drilling.

关键词： Multi-state deterioration random shock maintenance cost-benefit analysis

Mechanical joint performances of friction self-piercing riveted carbon fiber reinforced polymer and AZ31B Mg alloy

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Journal of Magnesium and Alloys 2022年第12期10卷 3367-3379页

作者： Yuan Li Yong chae lim Jian Chen Jiheon Jun Zhili Feng Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA

Carbon fiber reinforced polymer(CFRP) and AZ31B Mg alloy were joined by the friction self-piercing riveting(F-SPR) with different steel rivet shank sizes. With the increase of rivet shank size, lap shear fracture load and mechanical interlock distance increased. Ultrafine grains were formed at the joint in AZ31B as a result of dynamic recrystallization, which contributed to the higher hardness. Fatigue life of the CFRP-AZ31B joint was studied at various peak loads of 0.5, 1, 2, and 3 kN and compared with the resistance spot welded AZ31B-AZ31B from the open literature. The fatigue performance was better at higher peak load(>2 kN) and comparable to that of resistance spot welding of AZ31B to AZ31B at lower peak loads(<1 kN). From fractography, the crack initiation for lower peak load(<1 kN) case was observed at the fretting positions on the top and bottom surfaces of AZ31B sheet. When peak load was increased, fretting between the rivet and the top of AZ31B became more dominant to initiate a crack during fatigue testing.

关键词： Friction self-piercing riveting Magnesium alloy Carbon fiber reinforced polymer Dynamic recrystallization Fatigue life Crack initiation

Vascular and Morphogenetic Abnormalities Associated with Exposure of Cigarette Smoke Condensate during Chicken and Murine Embryogenesis

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Biomedical and Environmental Sciences 2010年第4期23卷 305-311页

作者： SOHAIL EJAZ AHMED EJAZ AMARA SOHAIL chae wooNG lim Department of Clinical Neurosciences Neurology Unit Addenbrookes Hospital University of Cambridge District Headquarter Hospital Government Social Security Hospital Gujranwala Pakistan Biosafety Research Institute and College of Veterinary Medicine Chonbuk National University

Objective Embryonic movements （EM） and angiogenesis pathways are evolutionarily conserved mechanisms which are essential for proper embryonic development. Deviations in these processes by exposure to cigarette smoke condensate （CSC） may cause vascular and morphogenetic disorders. Methods Using chicken and mouse embryos, we have demonstrated the in vivo effects of CSC on EM, vascular development, and organogenesis. Results Examination of the CSC exposed chicken embryos revealed a significant reduction in EM, stunted growth, deviated pattern of blood vessels, hemorrhages, and localized necrosis. Likewise, mouse embryos that were exposed to CSC at E8.5 and E9.5 died between E11.5 and E12.5, respectively. These mouse embryos showed defects in morphogenesis and remodeling of the embryonic vasculature, while littermate controls showed normal development. Conclusion Cigarette smoking during pregnancy is fatal for growing embryos. CSC may induce the remodeling of embryonic vasculature, leading to various pathologies.

关键词： Angiogenesis Embryonic movements Cigarette smoke condensate Vascular remodeling

Sub-2 nm mixed metal oxide for electrochemical reduction of carbon dioxide to carbon monoxide

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能源化学:英文版 2023年第9期84卷 303-310页

作者： Devina Thasia Wijaya Andi Haryanto Hyun woo lim Kyoungsuk Jin Chan woo Lee Department of Chemistry Kookmin UniversitySeoul 02707Republic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Chemistry Korea UniversitySeoul 02841Republic of Korea

Mixed metal oxide(MMO) represents a critical class of materials that can allow for obtaining a dynamic interface between its components:reduced metal and its metal oxide counterpart during an electrocatalytic ***,a synthetic method utilizing a MOF-derived micro/mesoporous carbon as a template to prepare sub-2 nm MMO catalysts for CO_(2) electro reduction is *** from the zeolite imidazolate framework(ZIF-8),the pyrolyzed derivatives were used to synthesize sub-2 nm Pd-Ni MMO with different *** Ni-rich(Pd_(20)-Ni_(80)/ZC) catalyst exhibits unexpectedly superior performance for CO production with an improved Faradaic efficiency(FE) of 95.3% at the current density of 200 mA cm^(-2) at-0.56 V *** hydrogen electrode(RHE) compared to other Pd-Ni compositions.X-ray photoelectron spectroscopy(XPS) analysis confirms the presence of Ni^(2+) and Pd^(2+) in all compositions,demonstrating the presence of *** functional theory(DFT) calculation reveals that the lower CO binding energy on the surface of the Pd_(20)-Ni_(80) cluster eases CO desorption,thus increasing its *** work provides a general synthetic strategy for MMO electrocatalysts and can pave a new way for screening multimetallic catalysts with a dynamic electrochemical interface.

关键词： Carbon dioxide reduction Mixed metal oxide Nanoalloy Carbon monoxide Metal-organic framework

Application of Integrated Database to the Casting Design

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Journal of Materials Science & Technology 2008年第3期24卷 351-355页

作者： In-Sung Cho Seung-Mok Yoo chae-Ho lim Jeong-Kil Choi KITECH 7-47 Songdo-dongYeonsu-gu

Construction of integrated database including casting shapes with their casting design, technical knowledge, and thermophysical properties of the casting alloys were introduced in the present study. Recognition tech- nique for casting design by industrial computer tomography was used for the construction of shape database. Technical knowledge of the casting processes such as ferrous and non-ferrous alloys and their manufacturing process of the castings were accumulated and the search engine for the knowledge was developed. Database of thermophysical properties of the casting alloys were obtained via the experimental study, and the properties were used for the in-house computer simulation of casting process. The databases were linked with intelligent casting expert system developed in center for e-design, KITECH. It is expected that the databases can help non casting experts to devise the casting and its process. Various examples of the application by using the databases were shown in the present study.

关键词： Integrated database Casting design Shape recognition

Crushing behavior of lightmass structural member

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中国有色金属学会会刊：英文版 2009年第B09期19卷 276-279页

作者： Kil-Sung LEE Yong-June YANG woo-chae HWANG In-Young YANG Department of Mechatronics Chosun University of Science and Technology Department of Advanced Part and Materials Engineering Chosun University Department of Mechanical Design Engineering Chosun University

Carbon fiber reinforced plastic (CFRP) of the advanced composite materials is widely used in lightmass structural materials of air planes, ship and automobiles because of high strength and stiffness. In this study, experimental investigation was performed for each specimen. The square section members consist of aluminum, CFRP and hybrid (aluminum/CFRP) member, and hat-shaped section members consist of CFRP and hybrid (aluminum/CFRP) members specimen. Based on the collapse characteristics of aluminum square section member, the collapse characteristics and energy absorption capability of hat-shaped section members were analyzed. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed. In the lightmass design aspect, the collapse characteristics and energy absorption capability of the members were compared.

关键词：碳纤维增强复合材料碳纤维复合材料能量吸收能力行为构件破碎航空飞机 CFRP