• 한국재료학회지
• /
• 제32권3호
• /
• pp.139-145
• /
• 2022

Reheat treatment process of mold is necessary when partial machining of the mold is required, such as shape correction for an existing mold. If defects such as cracks or significant deterioration of mechanical properties of the mold occur during reheat treatment, it is impossible to reuse the mold. In this study, reheat treatment was performed up to two times for STD11 tool steel, and microstructure and mechanical properties according to the reheat treatment were evaluated. Carbide fraction and grain size of prior austenite were almost unchanged after the reheat treatment. Hardness and impact toughness increased significantly after QT treatment, and these properties were maintained without significant change even after the reheat treatment. It is concluded that up to two iterations of reheat treatment does not cause deterioration of properties of STD11 tool steel. Based on these results, a mold for a face-lifted front bumper was manufactured through machining and reheat-treating of an existing mold.

• 한국표면공학회지
• /
• 제43권2호
• /
• pp.111-120
• /
• 2010

In this study, the effects of multi-complex agents addition on characteristics of electroless Ni plating solution are investigated. The species and the concentration of complexing agents are major factors to control the deposition rate, P concentration, and surface morphology of plating films. Adipic acid increases the deposition rate in regardless of single- or mutli-complex agent addition. However, lactic acid effectively increases the deposition rate in case of multi-addition as the complex agents with adipic or sodium succinate acid. In addition, sodium citric acid and malic acid show good stabilizing effects of plating solution and lowering the deposition rate, because they have high complexibility. Therefore, it is suggested that the development of Ni-P plating solution suitable for diverse usages can be carried out systematically using the database from this study.

• Journal of Power Electronics
• /
• 제11권4호
• /
• pp.612-619
• /
• 2011

This paper presents a water treatment system for leachate from sewage-filled ground that uses a pulsed-power modulator developed based on semiconductor switches in order to realize a long life, a high repetition rate, and a fast rising time. The specifications of the developed pulsed-power modulator are the pulsed output voltage, the output current, the pulse repetition rate (PRR), the pulse width, and an average output power of $60\;kV_{max}$, $300\;A_{max}$, 3000, $50\;{\mu}s$, and 15 kW, respectively. The pulsed-power water treatment system was introduced and analyzed using an equivalent electrical circuit model to optimize the output voltage waveform. The experimental results verify that the proposed water treatment system can be effectively used for industrial applications.

• 열처리공학회지
• /
• 제36권1호
• /
• pp.40-46
• /
• 2023

Controlled nitriding is a technology that controls the nitriding potential based on the gas partial pressure received through an IOT-based sensor. Controlled nitriding is characterized by easy control of the phase of the nitride compound and excellent reproducibility of quality. In particular, it is possible to form a compound layer of excellent quality with fewer pores on the surface. However, despite these advantages, the application of controlled nitriding still needs to be improved in Korea. This paper explains the characteristics of controlled nitriding and describes the future direction and the problems of controlled nitriding in Korea.

• 한국축산식품학회지
• /
• 제33권5호
• /
• pp.581-586
• /
• 2013

The objective of this study was to investigate the effects of supercritical carbon dioxide (SC-$CO_2$) treatment on meat quality and sensory evaluation of marinated pork. Meat marinated in two traditional Korean marinades, soy sauce and hot-pepper paste, and raw marinated meat were then treated with 7.4, 12.2, or 15.2 MPa $CO_2$ at $31.1^{\circ}C$for 10 min. The SC-$CO_2$ treatments had no effect on the meat pH (p>0.05) or Warner-Bratzler shear force (p>0.05). There was no significant difference (p>0.05) in the total loss (sum of treatment loss and cooking loss) between the control and SC-$CO_2$ treated samples at 15.2 MPa (soy sauce marinated pork: 21.78 vs. 18.97%; hot-pepper marinated pork: 21.61 vs. 18.01%). After the SC-$CO_2$ treatment, lighter surface colors were observed in the treatment samples compared to those of the control samples (p< 0.001). However, tasting panelists were unable to distinguish a difference in color or in overall acceptability of the control and treatment (p>0.05). In the case of soy sauce marinated pork, when SC-$CO_2$ applied at 15.2 MPa and $31.1^{\circ}C$for 10 min, treatment samples showed a tenderer meat than the control samples. Therefore, the SC-$CO_2$ treatment conditions had no adverse effects on the sensory quality characteristics of the marinated meat products.

• 한국결정성장학회지
• /
• 제28권6호
• /
• pp.250-255
• /
• 2018

본 연구에서는 3D-프린팅 적층 공정으로 제조한 인공관절용 CoCrMo 합금 소재의 HIP 처리를 포함한 복합열처리 후 소재의 인장특성, 내마모 특성 등의 기계적 특성과 결정구조 및 미세조직 등의 재료특성 변화를 고찰하였다. 내부마이크로 기공을 제거하기 위한 HIP 열처리와 금속탄화물 생성을 위한 상압열처리 및 금속탄화물의 균질화를 위한 용체화 열처리를 거치는 복합열처리 공정을 실시하여 인공관절 소재로서의 특성을 부여하고자 하였다. 3D-프린팅 적층 공정으로 제조한 인공관절용 CoCrMo 합금 소재의 복합열처리 효과는 HIP 공정중의 치밀화 과정, 상압열처리 중의 금속탄화물 생성 및 용체화 열처리 과정중의 금속탄화물의 균질화 효과임을 XRD, FE-SEM, EDS 분석으로 확인하였다.

• Journal of the Korean Wood Science and Technology
• /
• 제50권6호
• /
• pp.392-403
• /
• 2022

Currently, composite board manufacturing using natural fibers has the potential to expand owing to environmental awareness. To produce a composite board, treatment is required to improve the mechanical and physical properties of the natural fibers. In this study, sodium chloride (NaCl) was used for the chemical treatment. However, studies on chemical treatments using NaCl are limited. This study aimed to investigate the characteristics of kenaf fibers after NaCl treatment. The NaCl treatment concentrations were 1, 3, and 5 wt.% at room temperature, with soaking durations of 1, 2, and 3 h. The tensile strength, strain, and Young's modulus were measured to evaluate the mechanical properties of the fibers. The fiber bundle diameter, weight change owing to treatment, and contact angle were determined to analyze the effect of NaCl treatment. The kenaf fiber bundle treated with 5 wt.% NaCl for 3 h exhibited the highest tensile strength, Young's modulus, reduction in fiber bundle diameter, weight change, and decrease in contact angle compared to those of untreated fiber bundles. The tensile properties of the fiber bundle exhibited a tendency to decrease with increasing fiber bundle diameter. Increasing the soaking duration from 1 to 2 h did not result in a significant decrease in the fiber bundle diameter or an increase in tensile strength. However, a further increase in the soaking duration from 2 to 3 h resulted in a considerable decrease in the fiber bundle diameter and an increase in the tensile strength.

• 열처리공학회지
• /
• 제6권2호
• /
• pp.107-116
• /
• 1993

• 열처리공학회지
• /
• 제20권5호
• /
• pp.273-285
• /
• 2007

• 열처리공학회지
• /
• 제16권4호
• /
• pp.224-231
• /
• 2003