• 한국재료학회지
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• 제9권4호
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• pp.335-340
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• 1999

The hot cracking phenomena and phase behaviors during hot working process of Cu-Ni bearing hot rolled steels were investigated by a $90^{\circ}$bending tests, BSE image analysis and EDS analysis. For aNi-free 1.2% Cu bearing steel, the surface hot cracking occurred about $1100^{\circ}C$ due to a liquid state Cu-enriched phase formed continuously at the interface between oxide scale and matrix. The liquid Cu-enriched phase penetrated into austenite grain boundaries and caused surface cracking during the hot working. In case of 0.6% Ni containing 1.2% Cu-Ni bearing steel, solid state Cu-Ni-riched phase existed at the scale/matrix interface as a discontinuous type. But the higher addition of 1.2% Ni, solid state Ni-Cu-riched phase was formed dominantly in the oxide scale. It was found that the addition of Ni suppressed the surface cracking of 1.2% Cu bearing steel by eliminating the liquid state Cu-enriched phase.

• 한국지반공학회논문집
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• 제15권6호
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• pp.57-69
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• 1999

오염된 연약지반에 편재하중이 작용하는 경우에 있어서 지반의 소성화에 따른 지지력 결정을 위하여 기존의 이론적인 배경을 고찰하고, 이러한 오염된 연약지반에서 편재하중에 의한 지반의 지지력과 변형에 대한 거동을 연구하기 위하여 모형실험을 통한 실측치를 이용하여 서로 비교.분석하였다. 모형실험은 모형 재하장치인 토조와 재하틀 및 재하판을 제작하여 토조안에 함수비를 일정하게 유지한 상태에서 자연지반의 시료와 오염물질을 점진적으로 증가시킨 지반시료에 일정한 시간간격으로 편재하중을 증가시키면서 침하량과 측방변위량 및 융기량 등을 관찰하였다. 그 결과 한계하중은 실험값이 $Tschebotarioff(q_{cr}=3.0_{Cu)$의 제안값과 $Meyerhof(q_{cr}=(B/2H+\pi/2_{Cu})$의 제안값에 근접하여 $q_{cr}=2.78_{Cu$값을 나타냈고, 극한하중은 Prandtl의 제안값에 근접하여 $q_{ult}=4.84_{Cu}$의 값을 나타냈다

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.194-202
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• 2008

In this study, we investigated the tribology behaviour of two different bearing materials. One of these alloys content is Cu(90)-Sn(10) alloy and is widely used in the automotive industry.The other is Al alloy. This bearing content is Al-Sn-Si-Cu. Therefore, it is required to study on the lublicating characteristics of bearing according to different materials. In this study, compressor bearings made by respectively "PTFE solid lubricant" and "AI alloy with superior load carrying capacity, rubbing and impact endurance", have gone through journal bearing test. Lubrication and abrasion characteristics are evaluated by analyzing the material characteristics of a scroll compressor bearing bush. The AI alloy bearing showed the most excellent lubrication and abrasion characteristics than Cu-Sn alloy under high load condition.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1781-1786
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• 2007

Two copper(II) complexes, [CuL3](ClO4)2 bearing one N-CH2CH2CONH2 group as well as one N-CH2CH2CN group and [CuL4](ClO4)2 bearing two N-CH2CH2CONH2 groups, have been prepared by the selective hydrolysis of [CuL2](ClO4)2 (L2 = C-meso-1,8-bis(cyanoethyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). The complex [CuL5](ClO4)2 bearing one N-CH2CH2C(=NH)OCH3 and one N-CH2CH2CN groups has been prepared as the major product from the reaction of [CuL2](ClO4)2 with methanol in the presence of triethylamine. In acidic aqueous solution, the N-CH2CH2C(=NH)OCH3 group of [CuL5](ClO4)2 undergoes hydrolysis to yield [CuL6](ClO4)2 bearing both N-CH2CH2COOCH3 and N-CH2CH2CN groups. The crystal structure of [CuL5](ClO4)2 shows that the complex has a slightly distorted square-pyramidal coordination polyhedron with an apical Cu-N (N-CH2CH2C(=NH)OCH3 group) bond. The apical Cu-N bond distance (2.269(3) A) is ca. 0.06 A longer than the apical Cu-O (N-CH2CH2CONH2 group) bond of [CuL4](ClO4)2. The pendant amide group of [CuL3](ClO4)2 is involved in coordination. The carboxylic ester group of [CuL6](ClO4)2 is also coordinated to the metal ion in various solvents but is removed from the coordination sphere in the solid state.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1994년도 특별강연 및 춘계학술발표 개요집
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• pp.44-47
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• 1994

The ageing behavior of Cu-bearing HSLA steels was studied by using Differential scanning calorimetry(DSC), Transmission electron microscopy and hardness tester. Two heat evolution peaks were observed during DSC scans over the temperature range of 25～590$^{\circ}C$ at a heating rate of 5$^{\circ}C$/min. The peaks appeared in low (241∼319$^{\circ}C$ : HSLA-A, 224∼310$^{\circ}C$ : HSLA-B) and high temperature (514∼590$^{\circ}C$ : HSLA-A, 451∼558$^{\circ}C$ : HSLA-B) are attributed to the formation of coherent Cu-clusters and noncoherent $\varepsilon$-Cu phase, respectively. It was confirmed that as ageing proceeds, the coherent bcc Cu-clusters transform to noncoherent fcc $\varepsilon$-Cu phase. In the case of the ageing to peak hardness at 300$^{\circ}C$ and 400$^{\circ}C$, the coherent Cu-clusters contributed to the hardening. As ageing time and temperature increase over peak hardness, noncoherent $\varepsilon$-Cu are formed and hardness decreases.

• 한국재료학회지
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• 제8권3호
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• pp.274-279
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• 1998

0.05wt%C-Cu첨가열연강판에서 590MPa급을 가지며 10% pre-strain을 가한 후 780MPa급 이상을 가지는 Cu첨가형 열연강판의 최적 Cu 및 Mn첨가량 규명을 위해 경도 및 인장시험과 투과 전자현미경으로 조사하였다. Cu 첨가형 열연강판에서 고용강화와 시효경화를 고려한 적정 Cu 첨가량은 1.2wt% 전후였으며, Mn첨가량은 0.75-0.85wt%범위였다. 0.05%C-1.2%Cu-0.75%Mn-0.04%Nb첨가 강판에서 과시효조건에서 관찰되는 조대한 석출물은 면심입방정 구조인 $\varepsilon$-Cu인 것으로 확인되었으며, 열연상태에서는 590MPa급을 가지며, 10% pre-strain을 부여한 후 $550^{\circ}C$에서 30분 열처리할 경우 780MPa급의 인장강도를 가지는 Cu첨가형 열연강판의 제조가 가능하였다.

• 자원환경지질
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• 제27권6호
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• pp.549-556
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• 1994

Geochemical studies on gold-bearing quartz veins and wallrocks from the Okgye mine were carried out in order to investigate the primary dispersion patterns of gold and associated elements and to quantify the dispersion width of elements with distance from the gold-bearing quartz veins. Gold-bearing quartz veins occur in basaltic trachyandesite of unknown age. Enrichment of $k_2O$, MnO, Au, As, Rb, Sb, Pb, Zn, Cu, Ag and Cd, and depletion of $Na_2O$ and Sr are found in altered wallrocks. The ratio of $k_2O(k_2O+Na_2O)$, alteration index for trace elements, and Rb/Sr in altered wallrocks are increased, whereas Sr/CaO ratio is decreased with approach to the gold-bearing quartz veins. The widths of primary dispersion range from 17 cm to 155 cm. The relative dispersion width increases in order Au=Cu=Zn=Ag=Cd$k_2O$=Rb and Ba< $Na_2O$ $Na_2O$, As, Sb, Sr, Pb, Au, Cu, Zn, Ag and Cd, and a quadratic function for $k_2O$, MnO, Rb and Ba.

• Tribology and Lubricants
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• 제11권5호
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• pp.162-171
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• 1995

The application of reciprocating engine crankshaft bearings is of particular importance and interest among the plain bearing, not only because the sheer volume of intemal combustion engines now produced, but because the severe operating conditions they are subjected to. Demands for better performances of crankshaft bearings have provide an important impetus in the development of bearings and bearing materials. As engine design progresses toward higher outpt and higher efficiency, crankshaft bearings must perform under more seveve operating conditions. Higher load, temperature, and speed as well as lower viscosity oil are applied to the bearing sysem, resulting in a smaller minimum oil film thickness. This means more solid-solid contact between the shaft and bearing, and the bearing is exposed to more danger of seizure. Some engines may experience bearing seizure problems. However, understanding about the seizure behavior and mechanism is far from being enough. Seizure resistance of a bearing-shaft system will be affected by the properties of the shaft and bearing, especially their materials and surface texture. Commonly used engine bearing materials include Al-Pb-Si, Al-Sn-Si, Al-Sn, and Cu-Pb with Pb-Sn-Cu overlay. These materials have very different properties. They showed different behaviors dering seizure tests and seizure may occur with different mechanism for different bearing material. Shaft materials also affect the seizure resistance of the system. Surface texture of the bearing and shaft have apparent effects on the lubrication and solid-solid contact pattern, and therefore will affect the seizure behavior of the system. Bearings and shafts which are made of different materials and have different surface textures have been tested and analyzed. Their effects on seizure resistance are discussed and possible seizure mechanisms for different beatings are presented in this paper.

• 자원리싸이클링
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• 제1권1호
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• pp.51-57
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• 1992

동전해 과정중 비소를 제거하는 과정에서 생성된 함비소 동슬라임으로부터 비소의 희수와 고순도 비소의 제조를 위한 기초적인 자료를 얻기 위하여 함비소 슬라임의 염산침출실험을 행하였다. 함비소 슬라임은 Cu와 As의 금속간화합물인 $\beta-Cu_3As$가 주이며, 그밖에 미량의 $CU_2O$dhkCusAs가 혼재되어 있었다. 함비소 슬라임의 최적 염산침출조건은 슬라임입도 -140 mesh, 반응온도 $60^{\circ}C$ 염산과 슬라임의 비 3:1, 산소유량 1.25l/min, 침출반응시간 150분이었으며, 위의 침출실험조건에서 비소의 최대 침출들은 98%이었다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1712-1716
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• 2004

Copper-bearing montmorillonite (Cu-MMT) was produced by $Cu^{2+}$ cation exchange reaction. X-ray diffraction analysis showed that that the (001) basal spacing of the MMT crystal lattice increased from 1.544 to 1.588 nm after $Cu^{2+}$ exchange. This indicated that $Cu^{2+}$ entered into interlayer position of MMT as a hydrated cation or composite cation. In vitro results indicated that Cu-MMT had antibacterial activity on Escherichia coli $K_{88}$. Cu-MMT had unbalanced positive charge after cation exchange. Its antibacterial activity resulted from two aspects, one was electrostatic attraction which made E. coli $K_{88}$ being adhered on the montmorillonite surface, the other was the $Cu^{2+}$ slowly released, which could kill bacteria. In an in vivo study, four replicates of eight weanling pigs were assigned to each of two dietary treatments to study the effects of Cu-MMT on diarrhea, E. coli in the lumen of the jejunum and morphology of jejunal mucosa. As compared to the control, supplementation of the diet with 0.2% Cu-MMT improved average daily gain by 12.50% (p<0.05) and decreased F/G by 9.42% (p<0.05). The mean diarrhrea incidence was decreased by 71.80% (p<0.05). The viable counts of Escherichia coli in jejunal contents were significantly reduced (p<0.05). Villus height and the villus height to crypt depth ratio at the jejunal mucosa were increased by 19.09% (p<0.05) and 37.10% (p<0.05), respectively.