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.

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

RESPONSE TIME, INCENTIVE SYSTEM, AND LONG-TERM RELATIONSHIP

Rhim, Hosun 한국경영과학회 1998 Management Science and Financial Engineering Vol.4 No.2

This paper presents an incentive system to reduce response time from a supplier. The incentive system is expressed as a contract between an assembler and a supplier who have a long-term relationship. We produce the optimal payment scheme and expected total cost, when the assembler is farsighted. We show that the farsighted assembler obtains higher effort level from the supplier than the myopic assembler. We also show that the expected total cost of the farsighted assembler is smaller in the long run, although it is initially higher than that of the myopic assembler.

Mechanical and barrier properties of biodegradable soy protein isolate-based films coated with polylactic acid

Rhim, Jong-Whan,Lee, Jun Ho,Ng, Perry K.W. Elsevier 2007 FOOD SCIENCE AND TECHNOLOGY -ZURICH- Vol.40 No.2

<P><B>Abstract</B></P><P>Polylactic acid (PLA)-coated soy protein isolate (SPI) films were prepared by dipping SPI film into PLA solution. The effects of coating on improvements in mechanical and water barrier properties of the film were tested by measuring selected film properties such as tensile strength (TS), elongation at break (<I>E</I>), water vapor permeability (WVP), and water solubility (WS). TS of SPI films increased from 2.8±0.3 up to 17.4±2.1MPa, depending on the PLA concentration of the coating solution, without sacrificing the film's extensibility. In contrast, the extensibility of SPI film coated with solution containing more than 2g PLA/100ml solvent, increased. WVP of PLA-coated SPI films decreased from 20 to 60 fold, depending on the concentration of PLA coating solution. Water resistance of SPI films was greatly improved as demonstrated by the dramatic decrease in WS for PLA-coated films. The improvement in water barrier properties was mainly attributed to the hydrophobicity of PLA.</P>

Genetic Algorithms for A Competitive Location Problem

Rhim, Hosun 韓國經營硏究所 1997 經營論集 Vol.31 No.3-4

Interface electronic structure, two-dimensional metallicity, and possible interface superconductivity inCuCl∕Sisuperlattices

Rhim, S. H.,Saniz, R.,Yu, Jaejun,Ye, Lin-Hui,Freeman, A. J. American Physical Society 2007 Physical review. B, Condensed matter and materials Vol.76 No.18

Pinnal dermatitis caused by Arthroderma vanbreuseghemii in a Rex rabbit

Rhim, Haerin,Na, Ki-Jeong,Han, Jae-Ik The Korean Society of Veterinary Service 2017 韓國家畜衛生學會誌 Vol.40 No.1

This report describes a case of pinnal fungal dermatitis caused by Arthroderma vanbreuseghemii in a Rex rabbit diagnosed by clinical signs, macro- and microscopic examination, molecular and phylogenetic analyses. This is the first description of natural A. vanbreuseghemii infection in rabbits in South Korea.

Aneurysm of the Posterior Inferior Cerebellar Artery: Clinical Features and Surgical Results

Rhim, Jong-Kook,Sheen, Seung-Hun,Oh, Sung-Han,Noh, Jae-Sub,Chung, Bong-Sub The Korean Neurosurgical Society 2005 Journal of Korean neurosurgical society Vol.37 No.6

Objective: Aneurysms arising from the posterior inferior cerebellar artery(PICA) are uncommon. We review literature on that and surgical results on aneurysmal treatment by choice of surgical approach. Methods: On the basis of radiologic findings & charts, we review retrospectively the surgical results of 12 cases from Mar 1999 to Dec 2003. Results: The mean age of the 12 patients was 55.8(ranged from 36 to 71) and female was predominant (female:male = 8:4). Locations of PICA aneurysms revealed variously(vertebral artery - PICA junction: 8, lateral medullary segment: 2, PICA - anterior inferior cerebellar artery common trunk: 1, telovelomedullary : 1). Surgical approaches & treatments were attempted in 11 cases and embolization was done in 1 case(Far lateral transcondylar or supracondylar approach & clipping: 9, Far lateral transcondylar or supracondylar approach and trapping: 2, suboccipital approach & clipping: 1). The surgical result were 8 of 12 patients were good outcome, 1 of 12 was severely disabled and 3 of 12 were died. Conclusion: First, we choose surgical approach by the laterality of aneurysms and surgical or interventional treatment is attempted as soon as possible. The PICA aneurysm is regarded as having a relatively good surgical outcome without drilling of the posterior arch of the atlas.

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.