冷間加工의 磨耗에 對한 影響

李任烈 단국대학교 1986 論文集 Vol.20 No.-

The wear experiment was conducted on couples consisting of iron, nickel, Fe-36% Ni and 3% silicon steel pins sliding against a tool steel disc. It has been found that the wear rate in air at room temperature lis independent to me hardness. The experimental observations are well related to the oxidation characteristics. However, the rate of oxidative wear is much higher than that for static oxidation due to the difference in the activation energy for oxidative wear. The lower energy for oxidational wear indicates that the rubbing surfaces are mechanically activated and high diffusivity path for diffusion of matrix elements and oxygen are produced during the sliding motion. The higher wear rate for cold-worked samples than for the annealed ones are associated with the higher oxidation rate for the cold-worked specimen.

산소와 구리의 공정반응에 의한 구리와 알루미나의 직접접합

이임렬,유환성 단국대학교 신소재기술연구소 1991 신소재 Vol.1 No.-

본 연구에서는 구리표면의 구리-산소간의 공정반응에 의하여 형성된 Cu-Cu_2O 공용액상 피막으로 고체 Cu금속과 Al_2O_3세라믹을 압력없이 직접접합시키는 방법을 조사하였으며 접합조건에 따른 접합특성, 파면 및 계면분석을 SEM, EDS, XRD 및 peeling 시험을 통하여 분석하였다. 1.5×10^-1 torr 진공하에서 1015℃의 온도에서 산화시킨 구리시편은 미세한 산화물 Cu_2O가 표면에 잘 형성되었다. 그후 공정온도 1065℃ 이상의 접합온도 1075℃에서 5분간 10^-3 torr의 진공하에서 직접접합시킨 시편은 접합력이 우수한 Cu/Al_2O_3 접합이 되었으며 접합후 구리기니 내에는 Cu2O가 석출된 공융조직을 갖고 있었다. 3분 산화조건에서 충분한 액상이 형성되어 29kg의 최대 접합강도를 보였으며 산회시간이 이보다 짧거나 불충분한 액상의 형성이나 산화물내의 균열 등으로 결합력이 저하하였다. 파단후 Al_2O_3 표면에는 Cu_2O nodule이 존재하였고 Cu족에는 nodule이 빠진홈을 관찰할 수 있었는바 cu2O/Al_2O_3계면 접착력은 Cu.Cu_2O계면보다 강함을 알 수 있었다. 또한 파단면에는 반응 생성물 CuAlO_2가 접합중 형성되었으나 이 반응층 두께는 SEM분해능 이하인 매우 얇은 것으로 생각된다. The direct bonding between Cu and Al_2O_3, utilizing Cu-Cu_2O skin melt formed on Cu surface by eutectic reation of Cu-O, is investigated in this study. The bond strength, fracture surface and interface structure with bonding conditions have been studied using SEM, EDS, XRD and peeling test. A fine Cu_2O is formed on the surface of Cu with oxidation at 1015℃ under 1.5×10^-1torr vacuum. After oxidation, the bonded specimen conducted at 1075℃ in 10^-3torr vacuum for 5minutes, higher temperature than its eutectic temperature of 1065℃, has a good strength having a Cu_2O precipitated structure in Cu matrix upon cooling. It has been found that the maximum bonding force of 29kg is obtatined for 3 minutes of oxidation. However, the adhesion forces are decreased with shorter or longer oxidation than this due to the formation of insufficient liquid skin or crack within oxide. After peeling test, Al_2O_3 surface is covered with Cu_2O nodules which are pulled out of Cu surface indication that Cu_2O/Al_2O_3 adhesion force is stronger than that of Cu/Cu_2O. Moreover a reaction phase of CuAlO_2, thought to be very thin layer below the resolution of SEM, is also formed during the bonding process.

Targeted delivery of growth factors in ischemic stroke animal models

Rhim, Taiyoun,Lee, Minhyung Informa UK (Ashley Publications) 2016 Expert opinion on drug delivery Vol.13 No.5

Etiological and pathophysiological enigmas of severe coronavirus disease 2019, multisystem inflammatory syndrome in children, and Kawasaki disease

Rhim Jung-Woo,Kang Jin-Han,Lee Kyung-Yil 대한소아청소년과학회 2022 Clinical and Experimental Pediatrics (CEP) Vol.65 No.4

During the coronavirus disease 2019 (COVID-19) pandemic, a novel multisystem inflammatory syndrome in children (MIS-C) has been reported worldwide since the first cases were reported in Europe in April 2020. MIS-C is temporally associated with severe acute respiratory syndrome coronavirus 2 infection and shows Kawasaki disease (KD)-like features. The epidemiological and clinical characteristics in COVID-19, KD, and MIS-C differ, but severe cases of each disease share similar clinical and laboratory findings such as a protracted clinical course, multiorgan involvement, and similar activated biomarkers. These findings suggest that a common control system of the host may act against severe disease insult. To solve the enigmas, we proposed the protein-homeostasis-system hypothesis in that every disease involves etiological substances and the host’s immune system controls them by their size and biochemical properties. Also, it is proposed that the etiological agents of KD and MIS-C might be certain strains in the microbiota of human species and etiological substances in severe COVID-19, KD, and MIS-C originate from pathogen-infected cells. Since disease severity depends on the amounts of inflammation-inducing substances and corresponding immune activation in the early stage of the disease, an early proper dose of corticosteroids and/or intravenous immunoglobulin (IVIG) may help reduce morbidity and possibly mortality among patients with these diseases. Corticosteroids are low cost and an analogue of host-origin cortisol among immune modulators. This study’s findings will help clinicians treating severe COVID-19, KD, and MIS-C, especially in developing countries, where IVIG and biologics supplies are insufficient.

Characteristics of mammal abundance relative to habitat variables in temperate forests

Rhim, Shin-Jae,Son, Seung-Hun,Hwang, Hyun-Su,Kang, Jung-Hoon,Sung, Joo-Han,Park, Go Eun,Park, Chan-Ryul Sage Publishing 2015 Forest Science And Technology Vol.11 No.2

Antiviral effect of Wild Oyster mushroom (Pleurorus ostereatus) against respiratory virus

Rhim Ryoo,Hyorim Lee,Mi-Jeong Park,Eunjin Kim,Ki Won Lee 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

Oyster mushroom (Pleurorus ostereatus) is popular as a healthy diet food due to their richness in essential amino acids and low calories. Also, the need for functional research on disease prevention using this mushroom has been increased. Thus, our study tried to evaluate the antiviral activity against viruses that cause human infection by using hot water extract of oyster mushroom. The material used in this study was the fruiting bodies of this mushroom which were collected from Ginko biloba in Yongmunsa, Kapyung in 2018. For the antiviral activity test, the aqueous extract of the mushroom was prepared by incubating 50g of the dried fruiting body powder in 500 ml of distilled water at 100°C for 2 hours. Antiviral activity was performed with the novel swine-origin influenza A (H1N1) virus by modified ASTM E1052-11 method using plaque assay. As a result of measuring the decrements in the virus for 2 hours, this extract showed 99.99% antiviral efficacy against influenza A (H1N1) virus. This result suggest that the boiled oyster mushroom extract has a high application value for the prevention of viral respiratory diseases as a personalized food through drinking material in daily life.

Antiviral activity against Influenza A (H1N1) virus of Oak mushroom (Lentinula edodes) Extract

Rhim Ryoo,Hyorim Lee,Mi-Jeong Park,Eunjin Kim,Ki Won Lee 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

Oak mushroom (Lentinula edodes) have been recognized for helping to improve immunity in various oriental medicine libraries. However, this mushroom is vaguely known only as a healthy forest product without being clear on which pathogens this is effective against. Accordingly, in this study, we tried to evaluate the antiviral activity against viruses that cause human infection by using aqueous extract of oak mushroom. The material used in this study was the cultivar "Sanbaekhyang" developed and cultivated by the National Institute of Forest Science. For the antiviral activity test, the hot water extract of the mushroom was prepared by incubating 50g of the dried fruiting body powder in 500 ml of distilled water at 100°C for 2 hours. Antiviral efficacy evaluation was performed with the novel swine- origin influenza A (H1N1) virus by modified ASTM E1052- 11 method using plaque assay. As a result of measuring the decrement in the virus for 2 hours, this exctract showed 99.997% antiviral efficacy against the virus. This result indicated that the oak mushroom extract is highly valuable for use as a personalized food and pharmaceutical material for the prevention of respiratory pathogens.

Pervaporation Separation of Trace VOCs from Water Through PDMS Membranes

Rhim, Ji-Won,Kwon, Young-Mann The Membrane Society of Korea 1999 Korean Membrane Journal Vol.1 No.1

The removal of trace chlorinated and aromatic hydrocarbons from water by a pervaporation technique has been carried out through poly (dimethylsiloxane) membrane which had been fabricated by the addition crosslinking reaction. This study dealt with the swelling and permeation behaviors of the PDMS membranes with dichloroethane trichloroethane and toluene aqueous solutions. The swelling ratio in the toluene aqueous solution was much higher than those in the chloroethane solutions at all of the operating temperatures and concentrations. The solubility parameter theory was introduced to interpret the affinity between permeates and a membrane material and in all cases this approach seemed to be proper. It was suggested that the existence of water clusters in the membrane due to the hydrophobic characteristics of the membrane made the size of the permeating water larger resulting in suppressing water permeation and increasing enrichment of the organic components. The permeation behaviors at different membrane thicknesses were indirectly interpreted in terms of the effect of concentration polarization.

Unified bulk-boundary correspondence for band insulators

Rhim, Jun-Won,Bardarson, Jens H.,Slager, Robert-Jan American Physical Society 2018 Physical review. B Vol.97 No.11

Nanocrystalline Ferrihydrite-Based Catalysts for Fischer-Tropsch Synthesis: Part II. Effects of Activation Gases on the Catalytic Performance

Rhim, Geun Bae,Hong, Seok Yong,Park, Ji Chan,Jung, Heon,Rhee, Young Woo,Chun, Dong Hyun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.2

<P>Fischer-Tropsch synthesis (FTS) was carried out over nanocrystalline ferrihydrite-based (Fe9O2(OH)(23)) catalysts activated by different reducing agents: syngas (H-2+CO), CO, and H-2. The syngas activation successfully changed the ferrihydrite-based catalysts into an active and stable catalytic structure with chi-carbide (Fe2.5C) and epsilon'-carbide (Fe2.2C). The crystal structure of the catalysts obtained by syngas activation was similar to the structure obtained by CO activation; this similarity was probably due to the peculiar reduction behavior of the ferrihydrite-based catalysts, which exhibit much greater reducibility in CO atmosphere than in H-2 atmosphere. The performance of the catalysts activated by syngas was much higher than the performance of the catalysts activated by H-2 and was comparable to the performance of the catalysts activated by CO. This strongly demonstrates that the ferrihydrite-based catalysts are advantageous for industrial FTS processes because syngas can be commonly used for both activation pre-treatment and subsequent reaction.</P>