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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

Increase in neurokinin-1 receptor-mediated colonic motor response in a rat model of irritable bowel syndrome

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World Journal of Gastroenterology 2005年第2期11卷 237-241页

作者： Jun-Ho La tae-wan kim tae-Sik Sung Hyn-Ju kim Jeom-Yong kim Il-Suk Yang Department of Physiology College of Veterinary MedicineSeoul National UniversityRepublic of Korea Department of Physiology College of Veterinary MedicineKyungpuk National UniversityRepublic of Korea Institute of Bioscience and Biotechnology Daewoong Pharm Co.Ltd.Republic of Korea

AIM: Irritable bowel syndrome (IBS) is a functional bowel disorder. Its major symptom is bowel dysmotility, yet the mechanism of the symptom is poorly understood. Since the neurokinin-1 receptor (NK1R)-mediated signaling in the gut is important in the control of normal bowel motor function,we aimed to investigate whether the NK1R-mediated bowel motor function was altered in IBS, using a rat IBS model that was previously reported to show colonic dysmotility in response to restraint ***: IBS symptoms were produced in male SpragueDawley rats by inducing colitis with acetic acid. Rats were left to recover from colitis for 6 d, and used for experiments 7 d post-induction of colitis. Motor activities of distal colon were recorded in ***: The contractile sensitivity of isolated colon to a NK1R agonist [Sar9, Met(O2)11]-substance P (1-30 nmol/L)was higher in IBS rats than that in normal rats. After the enteric neurotransmission was blocked by tetrodotoxin (TTX, 1 μmol/L), the contractile sensitivity to the NK1R agonist was increased in normal colon but not in IBS rat colon. The NK1R agonist-induced contraction was not different between the two groups when the agonist was challenged to the TTX-treated colon or the isolated colonic myocytes. A nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 100 μmol/L) augmented the NK1R agonist-induced contraction only in normal rat ***: These results suggest that the NK1R-meidated colonic motor response is increased in IBS rats, due to the decrease in the nitrergic inhibitory neural component.

关键词： Irritable bowel syndrome Neurokinin-1 receptor

Advanced heterolytic H_(2) adsorption of K-added Ru/MgO catalysts for accelerating hydrogen storage into aromatic benzyltoluenes

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Journal of Energy Chemistry 2022年第8期31卷 333-343,I0009页

作者： tae wan kim Hwiram Jeong Yeongin Jo Dongun kim Ji Hoon Park Seok Ki kim Young-Woong Suh Department of Chemical Engineering Hanyang UniversitySeoul 04763Republic of Korea Environmental&Sustainable Resources Research Center Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea Department of Chemical Engineering Ajou UniversitySuwon 16499Republic of Korea

Herein,we report a highly active K-added Ru/MgO catalyst for hydrogen storage into aromatic benzyltoluenes at low temperatures to advance liquid organic hydrogen carrier *** hydrogenation activity of Ru/K/MgO catalysts exhibits a volcano-shaped dependence on the K content at the maximum with 0.02 wt%.This is in good agreement with the strength and capacity of H_(2) adsorption derived from basicity,despite a gradual decrease in the textural property and the corresponding increase in the Ru particle size with increasing the K *** functional theory calculations show that heterolytic hydrogen adsorption properties(strength and polarization)are facilitated up to a specific density of K on the Ru–MgO interface and excessive K suppresses heterolytic H_(2) adsorption by direct interaction between K and hydrogen,assuring the hydrogenation activity and H_(2) adsorption capability of Ru/K/MgO ***,the Ru/K/MgO catalyst,when K is added in an optimal amount,is highly effective to accelerate hydrogen storage kinetics at low temperatures owing to the enhanced heterolytic H_(2) adsorption.

关键词： Chemical hydrogen storage Supported Ru catalysts Ru–MgO interface Heterolytic H_(2)adsorption Charge transfer Potassium promotion

Peripheral corticotropin releasing hormone mediates post-inflammatory visceral hypersensitivity in rats

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World Journal of Gastroenterology 2008年第5期14卷 731-736页

作者： Jun-Ho La tae-Sik Sung Hyun-Ju kim tae-wan kim Tong Mook Kang Il-Suk Yang Department of Physiology College of Veterinary Medicine SeoulNational University Seoul 151-742 Republic of Korea Department of Physiology College of VeterinaryMedicine Kyungpuk National University Daegu 702-701Republic of Korea Department of Physiology SungkyunkwanUniversity School of Medicine Suwon 440-746 Republic ofKorea

AIM:To investigate whether peripheral corticotropin releasing hormone (CRH), which is up-regulated in intestinal inflammation, mediates the post-inflammatory visceral hypersensitivity in a rat model of colitis. METHODS:We measured mucosal myeloperoxidase (MPO) activity as a marker of inflammation, plasma CRH level, and abdominal withdrawal reflex (AWR) to colorectal distension as a visceral nociceptive response at 2, 7 and 14 d after the induction of colitis with 4% acetic acid. RESULTS:Colonic inflammation, quantified by MPO activity, significantly increased on d 2 and subsided thereafter, which indicated a resolution of inflammation within 7 d. On the contrary, plasma CRH level and AWR score were increased on d 2, remained high on d 7, and returned to control level on d 14. Intraperitoneal injection of a CRH antagonist, astressin (30 μg/kg), significantly attenuated the post-inflammatory visceral hypersensitivity on d 7. Furthermore, intraperitoneal administration of CRH (3 and 10 μg/kg) mimicked the post-inflammatory visceral hypersensitivity in naive rats. CONCLUSION:These results suggest that increased peripheral CRH mediates the enhanced visceral nociception in rats recovered from experimental colitis.

关键词： Corticotropin releasing hormone Visceral hypersensitivity Colitis

Visceral hypersensitivity and altered colonic motility after subsidence of inflammation in a rat model of colitis

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World Journal of Gastroenterology 2003年第12期9卷 2791-2795页

作者： Jun-Ho La tae-wan kim tae-Sik Sung Jeoung-Woo Kang Hyun-Ju kim ⅠI-Suk Yang Department of Physiology College of Veterinary MedicineSeoul National UniversitySeoulRepublic of Korea

AIM:Irritable bowel syndrome(IBS)is a functional bowel disorder characterized by visceral hypersensitivity and altered bowel *** is increasing evidence suggesting the role of inflammation in the pathogenesis of IBS,which addresses the possibility that formerly established rat model of colitis could be used as an IBS model after the inflammation subsided. METHODS:Colitis was induced by intracolonic instillation of 4% acetic acid in male Sprague-Dawley *** extent of inflammation was assessed by histological examination and myeloperoxidase(MPO)activity *** subsidence of colitis,the rats were subjected to rectal distension and restraint stress,then the abdominal withdrawal reflex and the number of stress-induced fecal output were measured, respectively. RESULTS:At 2 days post-induction of colitis,the colon showed characteristic inflammatory changes in histology and 8-fold increase in MPO *** 7 days post-induction of colitis,the histological features and MPO activity returned to *** rats at 7 days post-induction of colitis showed hypersensitive response to rectal distension without an accompaning change in rectal compliance,and defecated more stools than control animals when under ***: These results concur largely with the characteristic features of IBS, visceral hypersensitivity and altered defecation pattern in the absence of detectable disease, suggesting that this animal model is a methodologically convenient and useful model for studying a subset of IBS.

关键词： Acetic Acid Animals Biological Markers Colitis Disease Models, Animal Inflammation Irritable Bowel Syndrome Male Pain Peroxidase Rats Rats, Sprague-Dawley Research Support, Non-U.S. Gov't

Selective recovery of Sn from copper alloy dross and its heat-treatment for synthesis of SnO_2

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Transactions of Nonferrous Metals Society of China 2014年第S1期24卷 157-161页

作者： Jung-Il LEE Jong Bum PARK tae wan kim Man-Sik KONG Jeong Ho RYU Department of Materials Science and Engineering Korea National University of Transportation Functional Materials Research Team Advanced Materials & Processing Center Institute for Advanced Engineering Yongin Gyunggi 449-863 Korea

Preliminary study on concentration and separation of tin(Sn) from copper alloy dross by selective dissolution method was conducted. The tin in the copper alloy dross did not dissolve in an aqueous nitric acid solution which could allow separation of tin from the copper alloy dross. The tin as H2SnO3(metastannic acid) phase was precipitated in the solution with centrifuging process and transformed to tin dioxide(SnO2) after drying process. The dried sample was heat-treated at low temperature and its phase characteristics, surface morphology and chemical composition were investigated.

关键词： recovery of Sn copper alloy dross selective dissolution SnO2

Design of Korean Standard Modular Buoy Body Using Polyethylene Polymer Material for Ship Safety

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Journal of Materials Science and Chemical Engineering 2016年第1期4卷 65-73页

作者： Young Whan Park tae wan kim Jae Sub Kwak In Kwan kim Ji Eon Park Kyong Ho Ha Department of Mechanical Engineering Pukyong National University Busan Korea Department of R & D Newmarine Engineering co. Ltd. Busan Korea Department of Electric Energy Dongwon Science and Technology University Busan Korea

Buoy is the structure which is floated on sea surface in order to indicate the presenting obstacle such as reef and shallow sea and to show the direction of sea route to ship during sailing. Generally, the conventional material of buoy is steel and it has some problems. Firstly this steel light buoy has safety risk in case of collision between ship and steel buoy. Secondly steel buoy revealed high corrosion environment of salted water and oxide and corrosion of steel can lead to marine pollution. Thirdly it needs too much maintain cost because of its heavy weight. In this study, in order to overcome these problems we changed the buoy material from conventional steel body to polyethylene body. Polymer buoy body was designed with module type part and it can reduce total weight up to 43.12%. To evaluate the strength of that part, the structure analysis simulation was carried out with respect to stress, displacement, and strain. Maximum stress was 1.667 × 107 N/m2 and it was 25% of yielding stress of base material. Maximum displacement and strain were 3.164 mm and 0.00433353 and they are too small value and in safe range with comparing to total length of body. The stability of polymer buoy body was compared with conventional buoy with respect to center of gravity, center of buoyancy, metacenter, oscillation period, and tilt angle by wind, tidal current, and wave. Every value was improved comparing conventional one and we can get more stable buoy. Therefore the new polymer buoy body could prove its safety and stability.

关键词： Polymer Buoy Polyethylene Float Weight Reduction Structure Analysis Stability Evaluation

White luminescence of Ho^(3+)/Tm^(3+)/Yb^(3+)-codoped CaWO_4 synthesized via citrate complex route assisted by microwave irradiation

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Transactions of Nonferrous Metals Society of China 2014年第S1期24卷 134-140页

作者： Hyun CHO Seok Min HwanG Jae Bin LEE Dong Hyun KA tae wan kim Bo Seul LEE Ji Young LEE Jung-Il LEE Jeong Ho RYU Department of Nanomechatronics Engineering Pusan National University50 Cheonghak-ri Miryang Gyeongnam 627-706 Korea Department of Materials Science and Engineering Korea National University of Transportation Chungju Chungbuk 380-702 Korea

The nanocrystalline Ho3+/Tm3+/Yb3+ co-doped CaWO4 upconversion(UC) phosphors were successfully synthesized by a modified citrate complex method using microwave irradiation. The citrate complex precursors were heat-treated at temperature ranging from 300 to 700 °C for 3 h. Crystallization of the Ho3+/Tm3+/Yb3+ co-doped CaWO4 was detected at 400 °C, and entirely completed at 600 °C. The Ho3+/Tm3+/Yb3+ co-doped CaWO4 heat-treated at 600 °C showed primarily spherical and homogeneous morphology. Under the laser excitation of 980 nm, Ho3+/Tm3+/Yb3+ co-doped CaWO4 shows the bright white upconversion(UC) emission visible to the naked eye, which is composed of a blue emission at 475 nm from Tm3+, and green and red emissions at 543 and 651 nm respectively from Ho3+. The coordinates of Ho3+/Tm3+/Yb3+ co-doped CaWO4 in the Commission International De'eclairage(CIE) chromaticity diagram could be controlled from a cool to a warm white color depending on the Tm3+ and Ho3+ concentrations. The UC luminescent properties on Tm3+ and Ho3+ concentrations and related mechanism based on laser pump power were discussed in detail.

关键词： upconversion CaWO4 microwave irradiation white luminescence

Ultra‑Transparent and Multifunctional IZVO Mesh Electrodes for Next‑Generation Flexible Optoelectronics

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Nano-Micro Letters 2025年第1期17卷 293-309页

作者： Kiran A.Nirmal Tukaram D.Dongale Atul C.Khot Chenjie Yao Nahyun kim tae Geun kim School of Electrical Engineering Korea UniversityAnam‑ro 145Seongbuk‑guSeoulRepublic of Korea Computational Electronics and Nanoscience Research Laboratory School of Nanoscience and BiotechnologyShivaji UniversityKolhapur 416004India

Mechanically durable transparent electrodes are essential for achieving long-term stability in flexible optoelectronic ***,they are crucial for applications in the fields of energy,display,healthcare,and soft *** meshes represent a promising alternative to traditional,brittle,metal oxide conductors due to their high electrical conductivity,optical transparency,and enhanced mechanical *** this paper,we present a simple method for fabricating an ultra-transparent conducting metal oxide mesh electrode using selfcracking-assisted *** this method,we produced an electrode with ultra-transparency(97.39%),high conductance(Rs=21.24Ωsq^(−1)),elevated work function(5.16 eV),and good mechanical *** also evaluated the effectiveness of the fabricated electrodes by integrating them into organic photovoltaics,organic light-emitting diodes,and flexible transparent memristor devices for neuromorphic computing,resulting in exceptional device *** addition,the unique porous structure of the vanadium-doped indium zinc oxide mesh electrodes provided excellent flexibility,rendering them a promising option for application in flexible optoelectronics.

关键词： Self-cracking template Vanadium-doped indium zinc oxide mesh Organic solar cells Organic light-emitting diodes Flexible transparent memory