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.

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.

Differences in Breeding Bird Communities Between Deciduous Forests of Gwangneung and Mt. Namsan Areas

Rhim, Shin-Jae,Kim, Min-Jin,Lee, Ju-Young,Kang, Jeong-Hoon Korean Society of Forest Science 2007 한국산림과학회지 Vol.96 No.5

This study was conducted to clarify the differences in breeding bird communities between deciduous forests of Gwangneung and Mt. Namsan areas from April to August 2006. Two 10ha area were selected for territory mapping of breeding bird community in both study area. The DBH distribution of trees and average foliage profiles were significantly different between study areas. Also, breeding bird communities were different. Number of breeding species and pairs, breeding density, and bird species diversity were higher in Gwangneung area than in Mt. Namsan area. When examining relationship between forest habitat structure and bird community, Number of bird species and breeding pairs belonged to hole and canopy guild were increase as the increase of coverstory coverage and number of large trees. Therefore, it is necessary to make vertical structure more various to plant bushes, and to make DBH distribution more diverse for enhancing bird species diversity in the degraded ecosystem.

PVA/PAA막을 이용한 물-이소프로필알코올 혼합물의 투과증발 분리

Rhim JiWon,Kim SunWoo,Lee KewHo 한국막학회 1996 멤브레인 Vol.6 No.4

본 연구는 가교된 PVA/PAA 막을 이용하여 5와 12wt%를 포함하는 물-이소프로필알코올 계에 대한 투과증발 실험을 60, 70 및 80℃의 조업온도에서 수행하였다. PVA/PAA=75/25 막을 사용했을 경우 공급액의 조성이 물 12wt%에서 투과도 및 선택도가 온도 80℃에서 63g/m2h과 1520을 각각 나타내었으며, 물 5wt%에서는 같은 온도에서 투과도는 56g/m2h을 그리고 선택도는 1563을 얻었다. The crosslinked PVA/PAA membranes developed in our laboratory have been characterized for water-isopropyl alcohol mixture in terms of permeabilities and separation factor. When the feed mixture was 12wt% water, the permeability and the separation factor for PVA/PAA=75/25 membrane show 63g/m2h and 1520 at 80℃, respectively. In case of 5wt% water in feed mixture, the permeability for PVA/PAA=75/25 membrane is 56g/m2h at 80℃ while the separation factor is 1563.

Characteristics of Pressure Confined Concrete under Monotonic Compression

Rhim, Hong-Chul,Buyukozturk, Oral,Soon, K. A,Kim, Gwang-Ho Korea Concrete Institute 2001 KCI concrete journal Vol.13 No.1

Tests of cylindrical concrete specimens under lateral confining pressure of up to 5,000 psi were conducted for two different axial loading cases: monotonic compression and monotonic tension. The purpose of this experimental investigation is to provide stress-strain characteristics of plain concrete in triaxial stress conditions. Lateral confining pressure levels, loading rates, and strength of concrete specimens are varied as parameters. The loading rates are $34.75$\times$10^{-5}$ in/in/sec for fast, $\times$$6.95x10^{-5}$ in/in/sec for normal. and $0.579$\times$10^{-5}$ in/in/sec for slow loading cases. The concrete specimens used in the experiment have compressive strength of 3,500 psi and 6,500 psi, respectively. Findings of this experiment include dependency of the stress-strain behavior of concrete on the above parameters under two different types of loading conditions. The parametric study includes a series of 106 triaxial tests.

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.

폴리에틸렌-n-헥산-벤젠계에 대한 투과속도와 용해도 파라메타 사이의 관계

Rhim Ji Won 한국막학회 1993 멤브레인 Vol.3 No.3

It is well known that the membrane permeation in pervaporation is governed by both the chemical nature of the membrane material and the physical structure of the membrane and also the separation can be achieved by differences in either solubility, size or shape. The solubility of the penerrant in the polymeric membrane can be described qualitively by applying the Hildebrand relation [1] which relates the energy of mixing of the penerrant and the polymer material. Froehling et al. have tried to predict the swelling behavior of polymers for the systems of polyvinylchloride(PVC)-toluene-methanol, PVC-trichloroethylene-nitromethane and PVC-n-butylacetate-nitromethane[2]. The former two systems which do not show the donor/acceptor interactions upon mixing showed the successful results[2]. In addition to this technique, there are several other possible approaches to predict the swelling behaviors of polymers, such as the surface thermodynamic approach[3, 4], the comparison of the membrane polarity with the solvent polarity in terms of Dimroth's solvent polarity value[5].

Strain-induced giant second-harmonic generation in monolayered 2H-MoX2 (X = S, Se, Te)

Rhim, S. H.,Kim, Yong Soo,Freeman, A. J. American Institute of Physics 2015 APPLIED PHYSICS LETTERS Vol.107 No.24

Pharmacological Evidence that Cromakalim Inhibits $Ca^{2+}$ Release from Intracellular Stores in Porcine Coronary Artery

Rhim, Byung-Yong,Hong, Sun-Hwa,Kim, Chi-Dae,Lee, Won-Suk,Hong, Ki-Whan The Korean Society of Pharmacology 1997 The Korean Journal of Physiology & Pharmacology Vol.1 No.1

In the present study, it was aimed to further indentify the intracellular action mechansm of cromakalim and levcromakalim in the porcine coronary artery. In intact porcine coronary arterial strips loaded with fura-2/AM, acetylcholine caused an increase in intracellular free $Ca^{2+}$ $([Ca^{2+}]_i)$ in association with a contraction in a concentration-dependent manner. Cromakalim (1 ${\mu}M$) caused a reduction in acetylcholine-induced increased $[Ca^{2+}]_i$ not only in the mormal physiological salt solution (PSS) but also in $Ca^{2+}$-free PSS (containing 1 mM EGTA). In the skinned strips prepared by exposure of tissue to 20 .${\mu}M$ B-escin, inositol 1,4,5-trisphosphate ($IP_3$) evoked an increase in $[Ca^{2+}]_i$, but it was without effect on the intact strips. The $IP_3$-induced increase in $[Ca^{2+}]_i$ was inhibited by cromakalim by 78% and levcromakalim by 59% (1 .${\mu}M$, each). Pretreatment with glibenclamide (a blocker of ATP-sensitive $K^+$ channels, 10 .${\mu}M$) and apamin (a blocker of small conductance $Ca^{2+}$-activated $K^+$ channels, 1 .${\mu}M$) strongly blocked the effect of cromakalim and levcromakalim. However, charybdotoxin (a blocker of large conductance $Ca^{2+}$-activated $K^+$ channels, 1 .${\mu}M$) was without effect. In addition, cromakalim inhibited the $GTP{\gamma}S$ (100 .${\mu}M$, non-hydrolysable analogue of GTP)-induced increase in $[Ca^{2+}]_i$. Based on these results, it is suggested that cromakalim and levcromakalim exert a potent vasorelaxation, in part, by acting on the $K^+$ channels of the intracellular sites (e.g., sarcoplasmic reticulum membrane), thereby, resulting in decrease in release of $Ca^{2+}$ from the intracellular storage site.

Preparation and Characterization of Agar/Clay Nanocomposite Films: The Effect of Clay Type

Rhim, Jong-Whan,Lee, Soo-Bin,Hong, Seok-In Wiley Blackwell (Blackwell Publishing) 2011 Journal of food science Vol.76 No.3