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.

Radionuclide-labeled nanostructures for In Vivo imaging of cancer

Rhim Won-Kyu,Kim Minho,HARTMANKEVIN LAURENCE,강건욱,남좌민 나노기술연구협의회 2015 Nano Convergence Vol.2 No.10

Molecular imaging plays an important role in the non-invasive diagnosis and the guiding or monitoring of disease treatment. Different imaging modalities have been developed, and each method possesses unique strengths. While a variety of molecules have been used previously in nuclear imaging, the exceptional properties of nanostructures in recent research enable the deployment of accurate and efficient diagnostic agents using radionuclide-nanostructures. This review focuses on the radionuclide labeling strategies of various nanostructures and their applications for multimodality tumor imaging.

Activation of Wound Healing in Aged Rats by Altering the Cellular Mitogenic Potential

Rhim, J. H.,Jang, I. S.,Kwon, S. T.,Song, K. Y.,Yeo, E. J.,Park, S. C. GERONTOLOGICAL SOCIETY OF AMERICA 2010 Journals of Gerontology. Series A Vol.65 No.7

Detection of Debonding in Concrete Members Retrofitted with FRP Using Electromagnetic and Ultrasonic Methods

Rhim, Hong C.,Woo, Sang Kyun,Song, Young Chul Trans Tech Publications, Ltd. 2006 Key Engineering Materials Vol.321 No.-

<P>Microwave and ultrasonic methods have been used for the detection of debonding between concrete and fiber-reinforced plastic (FRP). To determine the capability of the microwave method in detecting thin delamination between two materials of concrete and FRP, concrete specimens are made with the dimensions of 600 mm (length) x 600 mm (width) x 50 mm (depth). Specimens have artificial delamination of 5 and 10 mm thick Styrofoam, which represent debonding in structures. Then, the specimens are partially covered with 1.5 mm thick FRP on the top of 3 mm thick epoxy. A horn antenna with a center frequency of 15 GHz and a frequency bandwidth of 10 GHz is used for the measurements. By transmitting and receiving microwave signals from the horn antenna, differences have been detected for the different types of the targets. Also, measurements using ultrasonic method at 5 kHz have been made on the same series of specimens. This work is directed toward a development of an effective and practical microwave based non-destructive evaluation methodology for the detection and quantification of damages in FRP-covered reinforced concrete members in bridges and buildings.</P>

Cellular Pathways in Agonist-induced Gallbladder Muscle Contraction in the Cat

Rhim, Byung-Yong,Kim, Chi-Dae,Kim, Dong-Heon,Biancani, Piero,Behar, Jose The Korean Society of Pharmacology 1996 대한약리학잡지 Vol.32 No.1

고양이 담낭근에서 효소학적으로 분리한 평활근 세포는 cholecystokinin octapeptide (CCK-8), acetylcholine (ACh) 및 KCl에 의하여 용량에 의존하여 수축하였다. 이들 효현제 (CCK-5, ACh 및 KCl)에 의한 평활근 세포의 최대수축은 각각$10^{-9}M$, $10^{-5}M$ 및 20mM 농도에서 야기되었다. CCK-8에 의하여 야기되는 이들 평활근 세포의 수축은 HEPES 완충액에 $Ca^{2+}$을 제거시킴에 의하여 영향을 받지 아니하였으나, $Ca^{2+}$ 대신에 strontium을 첨가시켰을때 수축반응이 완전하게 억제되었다 (p<0.001). 이와는 반대로 KCl에 의한 수축반응은 strontium 치환에 의하여 영향을 받지 아니하고 HEPES 완충액에 $Ca^{2+}$을 제거시킴에 의하여 억제되었다 (p<0.01). ACh에 의하여 야기되는 수축반응은 세포 외액의 $Ca^{2+}$을 제거시킴에 의하여 중등도의 억제반응이 야기되었으나 (p<0.05) strontium에 의하여 영향을 받지 아니하였다. Saponin으로 세포 투과성 변동을 야기시킨 근세포에서 inositol 1,4,5-trisphosphate $(IP_3)$와 CCK-8은 수축반응을 일으켰고, 이러한 수축반응은 calmodulin 길항제인 CGS 9343B에 의하여 차단되었으며 (p<0.001), heparin은 CCK-8 및 $IP_3$의 작용을 완전하게 봉쇄하였다 (p<0.001). 그러나 이러한 수축반응에 있어서 protein kinase C 길항제인 H7은 아무런 작용을 나타내지 못하였다. 이러한 결과로 볼 때 CCK-8에 의하여 야기된 고양이 담낭근 세포의 수축반응은 $IP_3$에 의하여 세포내 저장소로부터 유리된 $Ca^{2+}$과 calmodulin에 의존적인 과정에 의하여 매개되어 지는 것으로 생각된다. 또한 ACh는 세포외액의 $Ca^{2+}$ 뿐만 아니라 세포내 저장소의 $Ca^{2+}$ 모두를 이용하며, KCl은 전적으로 세포외액의 $Ca^{2+}$에 의존적인 형태로 calmodulin과는 무관하게 고양이 담낭근 세포의 수축반응을 야기시키는 것으로 사료된다. Cholecystokinin octapeptide (CCK-8), acetylcholine (ACh) and KCl caused a dose dependent contraction in muscle cells enzymatically digested from cat gallbladder. Maximal contraction was obtained at concentration of $10^{-9}M$ for CCK-8, $10^{-5}M$ for ACh and 20mM for KCl. CCK-8 induced contraction was unaffected in calcium free physiological salt solution (PSS) and was completely blocked by strontium substitution for calcium (p<0.001). In contrast, KCl evoked contraction was blocked in calcium free PSS (p<0.01) but was unaffected by strontium replacement of calcium. The contraction elicited by ACh was only slightly reduced in calcium free PSS (p<0.05) and was unaltered by strontium. Muscle cells permeabilized with saponin contracted in response to inositol 1,4.5-trisphosphate $(IP_3)$ and CCK-8. The contraction was blocked by the calmodulin antagonist CGS 9343B (p<0.001), whereas heparin completely blocked the effect of $IP_3$ (p<0.001). The protein kinase C (PKC) antagonist H7 had no effect on either agonist. We conclude that CCK-8 induced gallbladder muscle contraction is mediated by $IP_3$ dependent intracellular calcium release from intracellular stores and a calmodulin dependent pathway; ACh may utilize both extracellular and intracellular calcium. KCl causes muscle contracrion through influx of extracellular calcium and a calmodulin independent machanism.

Evaluation of Structural Integrity and Performance Using Nondestructive Testing and Monitoring Techniques

Rhim Hong Chul 한국지진공학회 1998 한국지진공학회논문집 Vol.2 No.3

In this paper, the necessity of developing effective nondestructive testing and monitoring techniques for the evaluation of structural integrity and performance is described. The evaluation of structural integrity and performance is especially important when the structures and subject to abrupt external forces such as earthquake. A prompt and extensive inspection is required over a large area of earthquake-damaged zone. This evaluation process is regarded as a part of performance-based design. In the paper, nondestructive testing and monitoring techniques particularly for concrete structures are presented as methods for the evaluation of structural integrity and performance. The concept of performance-based design is first defined in the paper followed by the role of evaluation of structures in the context of overall performance=based design concept. Among possible techniques for the evaluation, nondestructive testing methods for concrete structures using radar and a concept of using fiber sensor for continuous monitoring of structures are presented.

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.

Determination of Kinetic Parameters Using the Equivalent Point Method

Rhim, Jong Whan 木浦大學校 工業技術硏究所 1991 工業技術硏究誌 Vol.1 No.-

임의의 열처리 방법에 대해 equivalent time과 equivalent temperature를 결정할 수 있음을 직교좌표법과 회귀분석법을 이용하여 예시하였으며, 이들 equivalent time과 equivalent temperature를 활용하여 kinetic parameters를 결정하는 새로운 방법을 제안하였다. 이 방법을 2% 설탕용액의 산 가수분해(0.0005N HCl) 반응에 대해 적용해 본 결과 활성화 에너지 104.74±1.87kJ/mol 및 frequency factor 5.62×10^14hr^-1를 얻었으며, 이들 값은 보고된 결과와 잘 일치하였다. 또한 이 방법으로 구한 kinetic parameters값들이 기존의 방법들에 비해 보다 정확하고 사용이 간편함이 입증되었다. The uniqueness of the equivalent time and the equivalent temperature for any thermal treatment was demonstrated by both the line intersection method and the linear regression method. The equivalent time and the equivalent temperature determined by both method were consistent. And the equivalent time and the equivalent temperature were used for estimating the kinetic parameters for sucrose hydrolysis by acid. The activation energy and the frequency factor determined by the method were 104.74±1.87kJ/mol and 5.62×10^14hr^-1 respectively and the results agreed well with those obtained by a different method of kinetic data generation, i.e., the linearly increasing temperature method. The method was proved to be more accurate and move convenient than the conventional kinetic method.

Investigation of the Incorporation Efficiency of $\beta$-Carotene into Liposomes

Rhim, Chae-Hwan,Lee, Kyong-Eun,Yuk, Hyun-Gyun,Lee, Sang-Chun,Lee, Seung-Cheol The Korean Society of Food Science and Nutrition 2000 Preventive Nutrition and Food Science Vol.5 No.3

Chemical and photochemical precesses during food storage an preparation rapidly degrade $\beta$-carotene, the most active form of carotenoids. We investigated the possibility of liposomes as tool to preserve $\beta$-carotene. Liposomes with $\beta$-carotene were prepared as multilamellar vesicles by using soybean phosphatidylcholine, in terms of the ratio of $\beta$-carotene to phospholipid and pH. Incorporated efficiency was 99.7% at 1:0.05 of phospholipid : $\beta$-carotene and at pH 9.0. As the concentration of $\beta$-carotene increased, the incorporated efficiency increased progressively. pH did not affect the incorporation efficiency greatly.