• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.21-24
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• 2002

One of the factors influences on microstructure of semi-solid product is forging pressure. Generally, the more forging pressure makes the more fine microstructure in semi-solid compression test. The microstructure and mechanical properties were investigated according to the forging pressure. The applied pressure is 110MPa, 140MPa and 170MPa, respectively. Heat treatment conditions also influence to the microstructure and mechanical properties of semi-solid product. T6 heat treatment was performed and the evaluation of microstructure and mechanical properties was investigated according to the aging time in T6 heat treatment.

• Elastomers and Composites
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• 제7권1호
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• pp.45-52
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• 1972

As a series of the studies of EPDM-Polymer blends, the experiments are concentracted to the investigation of the physical properties of the EPDM-NBR blends. The results are shown as follows; 1. As EPDM addition ratio is increased, the physical properties such as resistance to ozone and aging have also improved, on the other hand, elongation and abrasion resistance decreased. 2. Tear strength is less influenced by blending and character after aging exhibited the same result. 3. Tensile strength decreased with increase in EPDM contents, especially the ratio of EPDM/NBR are 50/50 and 75/25.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.199-202
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• 1998

In examining application of polymer as electrical insulators, it is very important to perform accelerated aging test substituted the process which polymer insulator is degraded for long-time by the process of short-time. The purpose of this paper is to examine the properties of water degradation which affect on the efficiency of epoxy insulator. To do this, the surface properties on epoxy insulating material have been investigated after long-time accelerated degradation in boiling water condition. The experimental results showed the contact angle and surface resistivity after treatment to decrease the sample of water treatment. In dielectric properties, dielectric constant was increased by the aging development with water treatments.

• Elastomers and Composites
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• 제7권2호
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• pp.175-182
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• 1972

As a series of the studies of EPDM-Polymer blonds, the experiments are concentrated to the investigation of the physical properties of the EPDM-CR blends. The results are shown as follows: 1. In blending, tensile strength decreased with increase in EPDM contents and decreasing value was good results than various EPDM blending. 2. As EPDM Addition ratio is increased physical properties such as elongation have also improved, on the other hand, hardness and abrasion resistance decreased. 3. Aging resistance is less influenced by blending. 4. Tear strength is less influenced by blending and character after aging exhibited the same result. 5. Ozone resistance was much improved after blending. It was effective more than the ratio of EPDM/CR is 25/75.

• Transactions on Electrical and Electronic Materials
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• 제7권4호
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• pp.189-195
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• 2006

The microstructure, electrical and dielectric properties, and stability against DC accelerated aging stress of the varistors, which are composed of quaternary system $ZnO-Pr_6O_{11}CoO-Cr_2O_3-based$ ceramics, were investigated for different $La_2O_3$ contents. The increase of $La_2O_3$ content led to more densified ceramics, whereas abruptly decreased the nonlinear properties by incorporating beyond 1.0mol%. The highest nonlinearity was obtained from 0.5mol% $La_2O_3$, with the nonlinear coefficient of 81.6 and the leakage current of $0.1{\mu}A$. The varistors doped with 0.5mol% $La_2O_3$ exhibited high stability, in which the variation rates of breakdown voltage, nonlinear coefficient, leakage current, dielectric constant, and dissipation factor were -1.1%, -3.7%, +100%, +1.4%, and +8.2%, respectively, for stressing state of $0.95V_{1mA}/150^{\circ}C/24h$.

• 대한화장품학회지
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• 제45권2호
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• pp.185-198
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• 2019

인체 조직은 노화 현상을 겪으면 산화로 인한 손상이 진행되어 구조적인 변화가 일어나고 물성 저하를 겪는다. 피부가 겪는 노화 과정은 잘 알려져 있고 많은 평가가 수행되고 있지만 상대적으로 모발(머리카락)의 노화에 의한 평가는 잘 진행되어 있지 않아 모발의 노화를 케어하는 연구가 어려운 실정이다. 이에 본 연구는 모발의 노화 현상을 케어할 효능 기작을 적용할 수 있도록 노화된 모발 샘플을 제작하고 물성을 평가하여 안티에이징 효능을 확인하는 것을 목적으로 진행하였다. 먼저 내인성 노화가 진행된 모발의 지질량을 외인성 노화를 진행시킨 시료들과 비교한 결과, 펌 1회 처리 모발이 60대의 모발 지질량과 가장 유사함을 발견하였고, 이 모발을 통해서 원자 현미경으로 나노 스케일의 거칠기와 매크로 스케일의 인장강도를 평가하여 내인성 노화 모발과 유사한 물성 값을 가지고 있음을 확증하였다. 실제로 펌 처리를 통해 외인성으로 노화시킨 모발에 카르보디이미드와 펩타이드 결합을 적용하여 DSC로 구조적 변화와 거칠기 및 인장강도를 확인한 결과, 외인성 요인으로 노화된 모발을 에이징 이전의 상태의 물성 쪽으로 개선시키는 효과를 확인할 수 있었다. 뿐만 아니라 내인성 노화에 의해서 소실 된 내부 구성 성분을 프로폴리스를 이용하여 보강한 경우에도 외인성 노화가 유도된 모발의 물성이 에이징 이전 상태의 물성으로 회복되는 안티 에이징 효능이 발생함을 확인하였다. 본 연구에서 사용한 외인성 노화 유발 모발 시료 및 평가는 모발의 외인성 노화 연구에 유용하게 적용될 수 있음을 최초로 확인하였다.

• 열처리공학회지
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• 제31권3호
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• pp.91-96
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• 2018

Microstructural development of ferritic 11Cr-3.45W heat-resistance steel for ultra-supercritical power plant during creep and thermal aging was investigated using electron microscopy. The test samples were isothermally aged at $700^{\circ}C$ for up to 4000 hours and subjected to creep loading at $700^{\circ}C$ for predetermined periods of lifetime to prepare the damaged materials. In this structural material, a various secondary phases are the primary influence on mechanical properties of ferritic heat-resistance steel. The typical precipitates of $M_{23}C_6$, MX and $M_2X$ secondary phases had been analyzed through qualitative and quantitative manner. Coarsening of precipitates and increase of lath width were observed during creep and thermal aging. This phenomenon was remarkable for creep process compared with isothermal aging process.

• 한국세라믹학회지
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• 제24권5호
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• pp.477-483
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• 1987

Cr2O3 doped Pb(Zr0.525 Ti0.475)O3 piezoelectric ceramics were prepared from reagent grade oxide mixture, PbO, ZrO2, TiO2 and Cr2O3. Piezoelectric and aging properties of specimens were measured for various additions of Cr2O3. Generally, it has been known that aging rate decreased with Cr2O3 addition by stabilizing the domain wall. But hysteresis loops showed that the domain destabilization was occurred at high electric field (larger than 10KV/cm). In smaller additions of Cr2O3 (0-0.2mol%), aging rate increased and microcracks were created with increasing poling filed due to increasing internal stress. In larger additions of Cr2O3(0.4∼0.6mol%), aging rate decreased with increasing poling field.

• 열처리공학회지
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• 제33권5호
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• pp.226-231
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• 2020

The Cu-Co-Si alloy shows high strength by forming precipitates by aging precipitation heat treatment of supersaturated solid solution treated with solution treatment such as Cu-Ni-Si alloy, and the Co₂Si precipitated phase is dispersed in the copper matrix. The effect of aging treatment on the microstructure, mechanical and electrical properties of Cu-Co-Si alloys for electronic devices was investigated. As a results of SEM/EDS analysis, it was found that Co₂Si precipitates of 30~300 nm size were distributed in grains. By performing the double aging treatment, it was possible to improve the strength and electrical conductivity by dispersing the fine precipitate evenly.

• 공업화학
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• 제5권4호
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• pp.630-636
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• 1994

열화처리 후 고무와 황동이 피복된 강선코드의 접박계면 변화를 오제 광전자 분광기와 주사 전자현미경으로 조사하였다. 열열화 후에는 접착층의 부분 산화와 추가 성장이, 습윤열화 후에는 접착층과 황동의 부분 소실이, 동적열화 후에는 접착층의 파괴와 철심의 부식이 관찰되었다. 이러한 접착계면의 변화를 인장시험에서 측정된 접착 성질과 관련지어 고찰하였다.