• 열처리공학회지
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• 제17권1호
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• pp.29-35
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• 2004

The effect of low tempering in a temperature range of $150{\sim}400^{\circ}C$ on corrosion resistance in 420J2 stainless steel austenitized at $1000^{\circ}C$ was investigated by the application of salt spray test, electrochemical pitting test in 3.5% NaCl solution and DL-EPR test for intergranular corrosion in 0.5M $H_2SO_4$+0.01M KSCN solution. In salt spray test, good corrosion resistance was obtained in a tempering temperature range of $150{\sim}250^{\circ}C$. Pitting potential was increased to the tempering temperature of $250^{\circ}C$, but decreased with the increase of temperature up to $400^{\circ}C$ And it was thought that the degradation of pitting corrosion resistance showed at the tempering temperature of around $400^{\circ}C$ was due to the precipitation of $Cr_7C_3$ of $M_7C_3$ type. The degree of sensitization showed increasing tendency with the increase of tempering temperature, and also Cr depletion phenomena were observed in the vicinity of grain boundary.

• 한국표면공학회지
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• 제51권4호
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• pp.249-255
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• 2018

High temperature and low temperature gaseous nitriding was performed in order to study of the surface hardening and wear properties of the nitrided AISI 410 Martensitic stainless steels. High temperature gaseous nitiridng (HTGN) was carried out using partial pressure $N_2$ gas at $1,100^{\circ}C$ for 10 hour, and Low temperature gaseous nitiridng (LTGN) was conducted in a gas mixture of NH3 and N2 at $470^{\circ}C$ for 10 hour. The nitrided samples were characterized by microhardness measurements, optical microscopy and scanning electron microscopy. The phases were identified by X-ray diffraction and nitrogen concentration was analyzed by GD-OES. The HTGN specimen had a surface hardness of about $700HV_{0.1}$, $350{\mu}m$ of case depth. A ${\sim}50{\mu}m$ thick, $1,250HV_{0.1}$ hard nitrided case formed at the surface of the AISI 410 steel by LTGN, composed nitrogen supersaturated expanded martensite and ${\varepsilon}-Fe_{24}N_{10}$ iron nitrides. Additionally, the results of the wear tests, carried out LTGN specimen was low friction coefficient and high worn mass loss of ball. The increase in wear resistance can be mainly attributed to the increase in hardness and to the lattice distortion caused by higher nitrogen concentration.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.159-159
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• 2007

In order to reduce a signal delay in ULSI, low resistive metal and intermetal dielectric material of low dielectric constant are required. Ordered mesoporous silica film is proper to intermetal dielectric due to its low dielectric constant and superior mechanical properties. In this study, ordered mesoporous silica films was synthesized using TEOS (tetraethoxysilane) / MTES (methyltriethoxysilane) mixed silica precursor and Brij-$76^{(R)}$ surfactant. These films had the porosity of 40% and dielectric constant of 2.5. To lower dielectric constant, the ordered mesoporous silica films were surface-modified by HMDS (hexamethyldisilazane) treatment. HMDS substituted -OH groups on the surface of silica wall for -Si$(CH_3)_3$ groups. After the HMDS treatment, ordered mesoporous silica films were calcined at various calcination temperatures. Through the investigation, it was concluded that the proper calcination temperature is necessary as aspects of structural, electrical, and mechanical properties.

• 한국작물학회지
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• 제39권6호
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• pp.571-576
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• 1994

본실험은 대맥의 미숙배 배양을 통한 육종기간을 단축하기 위하여 미숙배 배양시 식물체 유도, 생육 및 출수에 영향을 미치는 생장조절물질, 배의 성숙정도 및 저온처리효과를 구명하고자 실시하였으며 그 결과는 다음과 같다. 1. 미숙배 배양으로부터 줄기의 유도에는 생장조절물질이 첨가된 기본배지도 효과적이었으며, Kinetin 0.5mg/1와 $GA_3$ 5mg/l를 처리한 것 이 좋았으나 Kinetin농도가 높을 때에는 shoot 유도가 감소되었다. 2. 지베렐린을 1mg/l와 5mg/l 처리한 배지에서 초장, root길이, root수 등이 좋았으나 Kinetin이 처리된배지에서는 생육이 억제되었으며, 특히 뿌리의 생육을 억제하였다. 3. 유도된 식물체의 토양생존율은 Kinetin 5mg/l 처리시에 생존율이 가장 낮았고 무처리에서 가장 높았다. 4. 파성정도가 IV인 올보리의 20일배를 4주저온처리 하였을 때에 출수율이 높았고 출수하는데 소요되는 기간도 짧았다. 5. 저온처리후 Kinetin 5mg/l 처리한 것은 초장, root수, shoot수가 적은 반면 $GA_3$ 5mg/l 처리한 것은 생육이 좋았다. 6. 올보리는 생장조절물질과 저온처리에 따라 출수율에 차이를 보였으며 $GA_3$를 1mg/l처리하고 28일 저온처리하였을때 출수율이 좋았으며, 출수에 소요되는 기간이 짧았다.

• 한국세라믹학회지
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• 제49권3호
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• pp.236-240
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• 2012

The reticulated carbon foam have been used for their excellent properties in terms of thermal management which is getting important in industrial field currently. In this study, we measure the mechanical properties of the reticulated carbon foam which is heat-treated at various temperature from the prepared low-density phenol foam. Simultaneously, we observe microstructures with high resolution transmission microscope and measure the residual oxygen content of carbon foams to figure out the relationship between the apparent change of properties such as weight loss and linear shrinkage during heat treatment. In conclusion, the carbon foam heat-treated at $1400^{\circ}C$ shows the highest strength, and the mechanical behavior is believed to be strongly related to the creation of nano-size graphite crystals from the amorphous carbon during heat treatment. On the other hand, it is turned out that the weight loss occurred at the temperature under $1400^{\circ}C$ comes from the elimination of oxygen in the form of $CO_2$ or CO, but no evidence is found on weight loss mechanism at the temperature above $1400^{\circ}C$.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권3호
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• pp.10-16
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• 2011

The experimental studies for remediation of diesel contaminated soils were performed using subcritical water in laboratory scale. Contaminated soils from industrial area and artificially contaminated soils were utilized for soil remediation. Experimental system was composed for subcritical water to flow upward through the soil packed column for extracting contaminants. 10 g of contaminated soil was packed into the column and water flow rate was 2 mL/min. To evaluate the effects of temperature, pressure and treatment time on the removal efficiency, temperature was changed from 100$^{\circ}C$ to 350$^{\circ}C$, pressure from 50 bar to 220 bar and treatment time at the predetermined temperature from 0 min to 120 min. The purification efficiency increased as temperature increased. However, the effect of pressure and treatment time was low. Temperature 250$^{\circ}C$, pressure 50 bar and treatment time 30 min were selected for optimal operating condition for this study.

• 열처리공학회지
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• 제19권4호
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• pp.219-224
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• 2006

Silver paste with low sintered temperature has been developed in order to apply electronic parts, such as bus electrode, address electrode in PDP (Plasma Display Panel) with large screen area. In this study, nano-sized silver particles with 10-30 nm were synthesized from silver nitrate ($AgNO_3$) solution by chemical reduction method and silver paste with low sintered temperature was prepared by mixing silver nanoparticles, conventional silver powder with the particle size 1.6 um and Pb-free frit. Conductive thick film from silver paste was fabricated by screen printing on alumina substrate. After firing at $540^{\circ}C$, the cross section and surface morphology of the thick films were analyzed by FE-SEM. Also, the sheet resistivity of the fired thick films was measured using the four-point technique.

• 한국염색가공학회지
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• 제24권2호
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• pp.131-137
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• 2012

para-Aramid fibers were treated by low-temperature plasma to improve the adhesion. The surface of para-aramid fibers were treated with gaseous plasma of several discharge power and treatment time in oxygen gas at 1Torr pressure. The treated fibers at low-temperature plasma were taken oxygen-containing functional groups and micro-crator on the surface. The modified fibers were measured by dynamic contact angle analyzer and XPS(X-ray photoelectron spectroscopy). The Interfacial adhesion properties of aramid fabric and polyurethane resin were determined by T-peel test. The surface of aramid fibers were observed by FE-SEM photographs. It was found that surface modification and chemical component ratio of the aramid fibers were improved wettability and adhesion characterization.

• Membrane and Water Treatment
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• 제15권1호
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• pp.1-9
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• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• 한국축산식품학회지
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• 제34권1호
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• pp.115-121
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• 2014

This study explored the effects of water or brine (2% NaCl, w/v) immersion thawing combined with ultrasound treatment (40 kHz, 150 W) on the quality characteristics of pork. Ultrasound treatment of pork was conducted in two cold media (at $4^{\circ}C$), water and 2% (w/v) brine, respectively. Because the ultrasound treatment caused temperature increase in the media from $4^{\circ}C$ to $16^{\circ}C$, the qualities of pork thawed by ultrasound were compared with those thawed by immersion either in water or brine where the temperature was being maintained at either $4^{\circ}C$ (low temperature control) or $17^{\circ}C$ (high temperature control). The ultrasound treatment resulted in rapid thawing of pork where the thawing rate was similar to those thawed in the $17^{\circ}C$ media. For quality characteristics, ultrasound-treated pork in brine had an advantage of less cooking losses when comparing to the control. In particular, ultrasound treatment in brine exhibited the lowest shear force (or highest tenderness) among the freezing/thawing treatments. Although the ultrasound processing in brine caused discoloration of the pork, this thawing technique had potential to be applied as a commercial thawing technology for frozen foods.