• Journal of the Korean Society for Heat Treatment
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• v.15 no.1
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• pp.21-24
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• 2002

The electrode materials for welding machine in automobile industry such as Cu-Cr, Cu-Zr and Cu-$Al_2O_3$ require the high electrical conductivity and the proper hardness. Therefore the effects of solution heat treatment and aging treatment on the electrical conductivity and hardness of Cu-0.8wt%Cr and Cu-1.2wt%Cr alloys have been investigated. Cu-0.8wt%Cr alloy showed the higher electrical conductivity and hardness than Cu-1.2wt%Cr alloy and both alloys showed the better electrical conductivity at $930^{\circ}C$ among 930, 980 and $1030^{\circ}C$ solution heat treatment temperatures. The electrical conductivity and hardness in both alloys were not affected by aging treatment but remarkably affected by solution heat treatment temperature. The final drawing process reduced electrical conductivity and increased hardness more in Cu-1.2wt%Cr alloy.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.281-286
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• 2001

Titanium alloy conducted in this experimental study has superior corrosive resistant and is mainly used in aerospace, automotive and petro-chemical industries. It is also treated with important materials of domestic goods due to improvement of the standard of living. In this study specimens were processed in the wire EDM after annealing, solution treatment and aging. Results were obtained through repeated experments of main rough process and finish process with the change of process parameters. Processing characteristics such as surface hardness, surfaces roughness, shape of processed surface and components were measured. The results confirmed that the above mentioned elements were improved in accordance with the number of process. Therefore, the optimal wire EDM condition in accord with processing characteristics is proposed in this experiment.

• Journal of Korea Foundry Society
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• v.12 no.5
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• pp.397-402
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• 1992

The effect of the solution & aging treatment on the tensile strength, yield strength, elongation, reduction of area, hardness was studied in the 17-4 PH stainless steel. SEM pictures were also taken in order to examine the fracture surfaces and precipitated particles. X-ray diffraction patterns for the heat treated samples were also observed. Mechanical properties of the heat treated samples were superior to those of as cast samples. Tensile strength, yield strength, hardeness decreased with the increase of aging temperature. On the other hand, elongation and reduction of area increased as the aging temperature increased.

• Journal of IKEEE
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• v.5 no.1 s.8
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• pp.24-34
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• 2001

IP address lookup is a major bottleneck of IP packet processing in high speed router. Existing IP lookup methods are focused only on lookup throughput without considering lookup table update. So their slow update can lead to lookup blocking or wrong routing decision based on obsolete routes. Especially existing IP lookup methods based on CAM(content addressable memory) have slow update of O(n) cycles in spite of their high throughput and low area complexity In this paper we proposes a new IP address lookup method based on pipelined CAM architecture(PICAM) with fast update of O(1) cycle of lookup table and high throughput and low area complexity.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.524-534
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• 1994

The effects of transformation temperature and mechanical properties by thermal cycle of CuZnAl shape memory alloy with a small of misch metal and Zr contents were investigated. The addition of misch metal and Zr was very effective for reducing the grain size. After solution treatment, the specimens were post-quench aged or step quenched at $100^{\circ}C$ to $350^{\circ}C$ for variation of Rockwell hardness value. It was found that the Rockwell hareness value was very increased at $200^{\circ}C$ and $250^{\circ}C$. The fracture strength and ductility have been significantly increased with the increase of misch metal conten when tensile tested below $M_f$ temperature. Also, the fracture strength has been more increased in the case of post quench aging treatment than that of the as-quenching treatment. Aging of the $\beta$-phase decreases the $M_s$ temperature, but that of the martensite phase increases the $A_s$ temperature. The change in $A_s$ temperature with post-quench aging can be attributed to recovery of order in the $\beta$phase. The hystersis of transformation temperature ($A_s-M_s$) has an increasing tendency by thermal cycles.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.2
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• pp.193-197
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• 2013

In this study, ultrasonic nonlinear characteristics in the heat-treated aluminum alloy have been evaluated. The nonlinearity of ultrasonic wave has been measured as the acoustic nonlinear parameter ${\beta}$, depending upon the amplitude ratio of the second-order harmonic and the fundamental frequency component of ultrasonic wave propagating through the materials. The parameter ${\beta}$ measurement has been carried out with the reflected signals from the back-wall of specimens at the same plane using the contact-type transducers. The heat-treatment, aging, has been achieved at $300^{\circ}C$ for various durations in the range of 1 to 50 hours. The tensile strength and elongation are obtained by the tensile test and then compared with the parameter ${\beta}$. There is a peak of the acoustic nonlinear parameter ${\beta}$ on 5 hours aging and the ${\beta}$ decreases thereafter, exhibiting closed relations with tensile strength and elongation. Also, the heat-treatment time showing peak in the parameter ${\beta}$ was identical to that showing severe change in the ${\sigma}-{\varepsilon}$ curve. These results suggest that the acoustic nonlinear parameter ${\beta}$ can be used for monitoring the strength variations with aging of aluminum alloys.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.327-327
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• 2011

DLC 필름은 바이오 적합성, 특히 생체 적합성이 뛰어나기 때문에 바이오 코팅분야에서 널리 이용된다. 많은 연구 결과에 의하면 세포와 장기 등이 바이오 재료 표면에 적절히 접합할 수 있도록, 재료 표면을 산소나 질소를 이용하여 플라즈마 처리로 초친수성 표면으로 개질하고 있다. 하지만, 시간이 지남에 따라서 친수성 표면은 점차 재료의 표면 처리 전의 성질인 소수성을 회복하게 된다. D실제 생체에 적용하기 위해서 이러한 시효 효과에 대한 정확한 평가가 이루어져야 한다. 따라서 산소와 질소 플라즈마 처리 후의 친수성 성질이 소수성 성질로 변해가는 거동을 조사하는게 중요하다. 13.56 MHz의 plasma assisted chemical vapor deposition (PACVD) 법을 이용하여 DLC와 Si-DLC를 500 ${\mu}m$ 두께의 P-type 실리콘(100) 기판에 증착하였다. 박막 증착 과정에 사용한 기체는 벤젠과 희석된 silane이 사용되었다(SiH4/H2=10:90). 박막 증착은 -400 V의 바이어스 전압을 인가하였으며, 이때 증착 압력은 1.33Pa으로 일정하게 유지하여, 두께 $0.55{\pm}0.01{\mu}m$로 증착하였다. X-ray Photoelectron Spectroscopy (XPS) 법을 이용하여 실리콘 함량을 측정하였으며, 증착 된 Si-DLC의 실리콘 함량은 0~4.88 at. %였다. 이후에 질소와 산소 플라즈마를 이용하여 챔버 압력을 1.33 Pa로 유지하여, -400 V의 바이어스 전압을 인가하여 10분간 표면 처리를 하였다. 표면 처리된 DLC와 Si-DLC 표면 위에서의 물방울(water droplet)의 젖음각을 20일간 측정하였다. 플라즈마 표면 처리 된 모든 시편에서 초기 젖음각은 $10{\sim}20^{\circ}$의 친수성 성질을 보였지만, 점차 젖음각이 상승하여 산소 플라즈마 처리 된 Si-DLC를 제외하고는 5일이 지나면서 거의 소수성 표면으로 회복되었다. 산소 플라즈마 처리 된 Si-DLC의 경우, 젖음 각 측정 기간(20일) 동안 $15^{\circ}$ 미만의 친수성 성질을 유지하였다.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.4
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• pp.677-687
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• 1999

This study was performed to evaluate the effect of aging and thermal cycling on the tensile strength of six commercially available glass-ionomer materials: two chemically set glass-ionomer materials(Fuji II, Fuji IX), two resin-modified glass-ionomer materials(Fuji II LC, Vitremer), and two polyacid-modified composite resins(Compoglass, Dyract). Rectangular tension test specimens were fabricated in a teflon mold giving 5mm in gauge length and 2mm in thickness. All samples were divided into 3 groups. Group 1 was immersed in a $37^{\circ}C$ distilled water for 1 hour. Group 2 was immersed in a $37^{\circ}C$ distilled water for 30 days. Group 3 was subjected to 10,000 thermal cycles between $5^{\circ}C$ and $55^{\circ}C$, and the immersion time in each bath was 15 seconds per cycle. Tensile testing was carried out at a cross-head speed of 0.5mm/min and fracture surfaces were examined with scanning electron microscope. The results obtained were summarized as follows; 1. The polyacid-modified composite resins were stronger than the resin-modified glass-ionomer materials, which were much stronger than the conventional glass-ionomer materials. 2. Tensile strengths were slightly increased after aging treatments for 30days. 3. Tensile strengths of conventional glass ionomers were significantly increased after thermal cycling treatment(p<0.01). 4. The highest tensile strength value of 45.4MPa was observed in the Dyract group and the lowest value of 13.3MPa was observed in the Fuji II LC group after the thermal cycling test, and the strengths of polyacid-modified composite groups were significantly higher than those of other groups. 5. The highest characteristic strength value of 48.6MPa was obtained in the Dyract group, however the highest Weibull modulus value of 8.9MPa was obtained in the Compoglass group after thermal cycling test.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.5
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• pp.29-35
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• 1994

The microstructual refinement process of Al-5Cr-2Zr alloys mechanical alloying 30h can be divided in five stages ; initial stage, welding predomminance stage, spherical partical formation stage, convolution welding predominance stage, and steady state. The rate of structural of aluminium splats was roughly logarithmic with processing time ; ${\in}$=k/0.78 ln(1+0.0028t). The age hardening in rapidly solidified Al-5Cr-2Zr alloys is ascribed to the coherency and dispersion hardening. Coherency hardening is occurred by matastable cubic Al3Zr precipitates in Al-Cr-Zr alloys. Dispersion hardening after mechanical alloying is attributed to the finely-dispersed $Al_2O_3$ and $Al_4C_3$ in Al-5Cr-2Zr alloys.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.11-18
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• 2009