• 소성∙가공
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• 제14권6호
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• pp.559-564
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• 2005

INCONEL 718, nickel based superalloy, has good formability, high strength, excellent corrosion resistance and mechanical properties at high temperature. Owing to theses attractive properties, it is utilized in applications such as combustion system, turbine engines and nuclear reactors. In such applications, components are typically required to be tolerant of high stress impact loading. This may cause material degradation and lead to catastrophic failure during service operation. Accurate understanding of material's mechanical properties with various strain rates is required in order to guarantee the reliability of structural parts made of INCONEL 718. This paper is concerned with the dynamic material properties of the INCONEL 718 at various strain rates. The dynamic response of the INCONEL 718 at the intermediate strain rate is obtained from the high speed tensile test and at the high strain rate is from the split Hopkinson pressure bar test. The effect of the strain rate on dynamic flow stress, work hardening characteristics, strain rate sensitivity and elongation to the failure is evaluated with the experimental results. Experimental results from both the quasi-static and the high strain rate up to 5000/sec are interpolated in order to construct the Johnson-Cook model as the constitutive relation that should be applied to simulate and design the structural parts made of rNCONEL 718.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.478-478
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• 2012

Recently, there are many researches in order to increase the deposition rate (D/R) and improve film uniformity and quality in the deposition of microcrystalline silicon thin film. These two factors are the most important issues in the fabrication of the thin film solar cell, and for the purpose of that, several process conditions, including the large area electrode (more than 1.1 X 1.3 (m2)), higher pressure (1 ~ 10 (Torr)), and very high frequency regime (VHF, 40 ~ 100 (MHz)), have been needed. But, in the case of large-area capacitively coupled discharges (CCP) driven at frequencies higher than the usual RF (13.56 (MHz)) frequency, the standing wave and skin effects should be the critical problems for obtaining the good plasma uniformity, and the ion damage on the thin film layer due to the high voltage between the substrate and the bulk plasma might cause the defects which degrade the film quality. In this study, we will propose the new concept of the large-area multi-electrode (a new multi-electrode concept for the large-area plasma source), which consists of a series of electrodes and grounds arranged by turns. The experimental results with this new electrode showed the processing performances of high D/R (1 ~ 2 (nm/sec)), controllable crystallinity (~70% and controllable), and good uniformity (less than 10%) at the conditions of the relatively high frequency of 40 MHz in the large-area electrode of 280 X 540 mm2. And, we also observed the SEM images of the deposited thin film at the conditions of peeling, normal microcrystalline, and powder formation, and discussed the mechanisms of the crystal formation and voids generation in the film in order to try the enhancement of the film quality compared to the cases of normal VHF capacitive discharges. Also, we will discuss the relation between the processing parameters (including gap length between electrode and substrate, operating pressure) and the processing results (D/R and crystallinity) with the process condition map for ${\mu}c$-Si:H formation at a fixed input power and gas flow rate. Finally, we will discuss the potential of the multi-electrode of the 3.5G-class large-area plasma processing (650 X 550 (mm2) to the possibility of the expansion of the new electrode concept to 8G class large-area plasma processing and the additional issues in order to improve the process efficiency.

• 식품기술
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• 제15권2호
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• pp.93-99
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• 2002

고압처리로 멸균된(high-pressure- sterilized) 저산성 식품은 아직 본격적으로 시장에 나오지는 않고 있다. 그러나 고압처리로 살균시켜(high-pressure-pasteurized) 제품의 부가가치를 높인 상품들은 일부 시판되고 있다. 미국시장에는 구아카몰(guacamole),굴 등이 있고, 일본과 유럽에는 잼, 젤리, 생선제품, 육제품, 슬라이스 햄, 샐러드 드레싱, 쌀떡, 주스, 요구르트 등이 판매되고 있다. 기술이 발전되어 처리비용이 떨어짐에따라 우유나 오렌지 주스 같은 저부가가치의 제품(high-volume commodity products)에도 고압처리 기술이 적용되는 예를 보게 될 것이다.미국 FDA의 "열처리된 저산성식품은 용접밀봉된 용기(캔, hermetically sealed container)에 포장되어야 한다." 는 규정(Title 21, Part 113 of the Code Federal Regulations)은 고압처리 식품을 염두에 두고 만들어진 규정은 아니지만, 저산성식품의 고압처리 공정(high-pressure processing)은 강력한 살균력을 제공하고 있다. 따라서 위의 FDA 규정(21 CFR 113)의 모든 조항은 고압처리 저산성 식품이 상업적인 생산에 들어가기 전에 시행되어야만 하는 것이다. 그 규정의 주요 조항중의 하나는 고압처리 공정에 대한 전문적인 지식을 가진 전문가나 위원회 등에 의하여 세부적인 고압처리공정 절차를 확립하는 것이다. 공정의 전문가들은 안전성을 증명하기 위해서 적합한 과학적인 방법을 사용하여 고압처리 공정을 확립해야만 한다. 저산성 식품에 대한 고압처리 공정은 주의깊게 설정된 공정조건하에서 재현성 있게 안전한 식품을 생산할 수 있어야 한다. 살균에 대한 안전성과 재현성이 입증되면 고압에 의한 살균처리공정 설계는 일반적인 대량생산 공정으로 활용될 수 있게 된다. PP(고압처리공정)의 유효성이 보다 확실하게 입증되고 널리 활용되려면, 공정의 살균력과 일관성(uniformity)을 증명하는 미생물적, 물리적, 화학적, 공학적인 여러 분야가 통합된 검증방법이 필요하다. 전통적인 열처리 공정은 스팀열의 가열시간으로 설명이 충분하다. 물론 HPP살균에서도 시간과 온도는 주요 변수이지만, 압력에 의한 미생물살균도 고려되어야만 한다. 또한 점도, 밀도, 구성성분, pH, 수분활성도 같은 해당제품의 특성도 제품의 고압처리 살균공정, 특히 미생물의 사멸에 영향을 미칠 수도 있다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.221-225
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• 2009

A solar thermal collector is a solar collector specifically intended to collect heat: that is, to absorb sunlight to provide heat. A flat plate is the most common type of solar thermal collector, and is usually used as a solar hot water panel to generate solar hot water. A flat plate collector consists basically of an insulated metal box with a glass or a plastic cover and a dark-colored copper absorber plate. Solar radiation is absorbed by the copper absorber plate and transferred to water that circulates through the collector in copper tubes. Ultrasonic welding is an industrial technique whereby high-frequency ultrasonic acoustic vibrations are locally applied to work pieces being held together under pressure to create a solid-state weld. In this study, we developed solar collector ultrasonic welding machine with digital controlled power supply and tested various welding conditions such as welding pressure, welding amplitude, welding speed. Welding speed was considered in 2~12m/min. The width of ultrasonic welds was increased with welding amplitude by 2.2~2.5mm. The fracture load of ultrasonic welds showed 20% higher than domestic products.

• 한국분말재료학회지
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• 제2권2호
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• pp.158-164
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• 1995

Synthesis of the NiTi shape memory alloy using the thermal explosion mode of the self-propagating high-temperature synthesis has been investigated. The significant fractions of intermetallics phases were found to form at the Ti/Ni powder interface during the heating to the ignition temperature and seemed to influence the relative fraction of phases in the final products. As the heating rate to the ignition temperature was increased, the combustion temperature and the fraction of NiTi in the final reaction products were increased. The synthesis reaction under 70 MPa compressive pressure yielded a reaction product with 98% theoretical density.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3252-3258
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• 2010

In this study, the effects of the various parameters of spinning and drawing processes on the properties of polyester full drawn yarn (FDY) prepared by steam processing during high-speed spinning were investigated using several techniques. The wet shrinkage ratio of the FDY was able to be manipulated by controlling the temperature and draw ratio. The FDY made using the steam high speed spinning technique exhibited identical properties (such as tenacity, elongation, and wet shrinkage ratio) to that of regular FDY, made using the spin-draw process. FDY prepared using the steam process during high-speed spinning showed excellent dyeability. The dye pick-up of the polyester yarn spun at high-speed spinning was found to be improved when dyed under an atmospheric pressure of $100^{\circ}C$. This result was the same as regular FDY dyed under a high pressure of $130^{\circ}C$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.334-337
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• 2003

장마포기에는 적도에서 동지나 지역은 주로 대류에 의한 강수가 우세했으며, 대다수의 수증기는 인도 몬순지역에서 이류되어 온 수증기임을 안 수 있었다. 장마기에는 한반도 지역은 convection에 의한 강수는 미소하나 microphysics에 의한 강수가 지배적이었다. 이 때 수증기의 근원(강수량)은 인도 몬순지역에서 이류되어 온 수증기이다. 비장마기에 우리나라 및 대다수의 지역은 microphysics에 의한 강수가 지배적이었다. 또한 태풍의 북상으로 인한 대량의 수증기의 이류이다. 수증기의 대부분은 Rossby wave의 복동방향 전파에 기인한다.

• 소성∙가공
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• 제17권7호
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• pp.528-533
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• 2008

Cavity in the mold is exposed to high pressure during injection molding operation. Injection molded articles with deep depth are often demanded as design variety increases. Subsequently mold becomes weak and deformation increases as the mold depth increases. Thus the injection molds for deep depth articles should be designed to hold out high pressure or stress concentration and large deformation. Through this study, equation for mold design was examined and suggested novel method to determine equation for mold design with deep depth. Novel equation developed in this study was modified from beam theory considering cantilever and two points bending situation while previous equation was modified from just cantilever bending situation. The validity of novel equation was verified through computer simulations for various mold side and wall thickness.

• International Journal of Industrial Entomology and Biomaterials
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• 제31권2호
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• pp.127-131
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• 2015

Oak silkworm, Antheraea yamamai (A. yamamai), has been used for clothing and surgical suture and considered as biomaterial due to RGD tripeptide. This paper reported the degumming conditions of A. yamamai using sodium oleate, high pressure and temperature, and sodium carbonate. Degumming ratio of A. yamamai cocoon using sodium oleate was less than 10%. High pressure and temperature treatment induced 30% weight loss of A. yamamai cocoon. The concentration, treatment temperature and time using sodium carbonate was examined and revealed the following conditions for degumming; 5% owf, 60 min at 100℃. The degummed solution was confirmed using UV and FT-IR spectrometer. Our results can be used to handle A. yamamai silkworm cocoon for further application including material processing.