• 동력기계공학회지
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• 제21권6호
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• pp.13-20
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• 2017

Ni-base superalloy Haynes 282 was developed as a gas turbine material for use in the ultra-super-critical stage (USC) of next-generation coal-fired power plants. Temperatures in the USC stage exceed $700^{\circ}C$ during operation. In spite of its important role Haynes 282 in increasing the performance of high-pressure turbines, as a result of its high-temperature capability, there is little information on the microstructure, deformation mechanism, or mechanical properties of the cast condition of this alloy. The aim of present study is to examine the creep properties of cast alloy and compare with wrought alloy. The ${\gamma}^{\prime}-precipitates$ were coarsen with the increase of aging time ranging from 8 to 48 hrs. A creep test performed at $750^{\circ}C$ showed faster minimum creep rate and shorter rupture lifetime with the aging time. A creep test performed showed only a slight difference in the rupture life between cast and wrought products. Based on the creep test results, the deformation mechanism is discussed using fractographs.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.1-8
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• 2024

In this study, the influence of thermal aging on structural integrity is investigated for Gr. 91 steel. A commercial grade Gr. 91 steel is used for the virgin material, and service-exposed Gr. 91 steel is sampled from a steam pipe of a super critical plant. Time versus creep strain curves are obtained through creep tests with various stress levels at 600 ℃ for the virgin and service-exposed Gr. 91 steels, respectively. Based on the creep test results, the improved Omega model is characterized for describing the total creep strain curve for both Gr. 91 steels. The proposed parameters for creep deformation model are used for predicting the steady-state creep strain rate, creep rupture curve, and stress relaxation. Creep-fatigue damage is evaluated for the intermediate heat exchanger (IHX) in a large-scale sodium test facility of STELLA-2 by using creep deformation model with proposed creep parameters and creep rupture curve for both Gr. 91 steels. Based on the comparison results of creep fatigue damage for the virgin and service-exposed Gr. 91 steels, the thermal aging effect has been shown to be significant.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.266-267
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• 2014

In order to develop concrete generating compressive strength of 10MPa~15MPa aging for 6hours in the room temperature curing, Hardening accelerator containing Ca²⁺ mixed with rapid hardening portland cement containing C₃S in quantity. The result was that the more addictive contents of Hardening accelerator is, the more greatly early compressive strength was improved. That's because the composition of Ca(OH)₂ was mass-produced at early-ages.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.20-25
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• 2000

lh deleterious Cr, Mo rich -$\sigma$phase is a hard embrittling precipitate, which forms between MU)-900 $^{\circ}C$, often associated with a reduction in both impact properties and corrosion reshame. On this study, After aging at MU) "C, fatigue crack propagation induced by a phase precipitation was evaluated and time-frequency analysis of acoustic emission was conducted It was possible to find fracture mechanism by a phase precipitation due to time-frequency anulysis of acoustic emission signals.nals.

• 한국자기학회지
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• 제19권3호
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• pp.100-105
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• 2009

차세대 발전소재로 주목 받고 있는 초초임계압 페라이트기 강의 고온 등온열화손상을 평가하였다. 고온 등온열화에 따른 가역 투자율을 측정하여 미세조직 변화와의 상관성과 그 영향에 관하여 연구하였다. 고온 등온열화는 미세한 템퍼링 석출물($Cr_{23}C_6$)을 성장시키고, 새로운 금속간 화합물($Fe_2W$)을 생성시켰으며 급격한 조대화를 보였다. 또한, 래스 내부의 전위밀도를 크게 감소시켰다. 가역투자율로부터 측정한 동적 보자력은 등온열화 초기 약 500시간 이내에 급격하게 감소하고 이후 서서히 감소하였다. 이는 자벽에 대한 고착점의 개수감소와 밀접한 관련이 있으며, 미세한 석출물, 전위 및 마르텐사이트 래스와 관련된다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2015년도 춘계 종합학술대회 논문집
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• pp.125-126
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• 2015

According to the provisions of the United Nations, the proportion was 65 years of age or older population is 7% more than in the total population aged society. Due to the rapid decrease fertility and medical technologies and the improvement of living standards, the average life expectancy has emerged as an aging society. In the case of our country, and in 2011 the proportion of the population aged 65 and over 11.4%, the future is even faster aging rate is expected to launch in 2026, the super aged society. The days went by relying on caring for personal piety. Nursing crime is often due to the patriarchal family culture and afford. To care for patients with severe human or plant in the home, not to assume that society. Expanding the scope of long-term care insurance service person and the family burden reduced through measures to apply for health insurance, nursing care can prevent crime.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2002년도 춘계학술발표회 초록집
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• pp.36-36
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• 2002

Effects of pulse-plating on the wear and corrosion resistance of chrome-carbon layers were studied. The plating were carried out at $06A/\textrm{cm}^2$ in modified Sargent bath containing formic acid at $53^{\circ}C$. The chrome layer were super-saturated with carbon up to 2.0wt. %, which precipitated as chrome carbide such as $Cr_{23}C_6$ after vacuum aging above $200^{\circ}C$ for 1 hour. This resulted in improvement of hardness and wear resistance of the chrome layer. Considering the reduction of corrosion resistance due to the thermal effect, optimum vacuum aging condition of the chrome layer in this study was I-hour at $200^{\circ}C$.

• Asian Journal of Innovation and Policy
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• 제8권2호
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• pp.208-237
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• 2019

Serious social problems related to the elderly have appeared in the Gangwon Province because the population in this area is rapidly aging. Gangwon has the highest suicide rate and the highest percentage of single households. In the process of preparing for the super-aging society, Time Bank (TB) System has been actively used in 34 countries, especially in the United States, the United Kingdom, and Japan. In Korea, the Gumi Senior Club has joined this system since 2004. TB is a multilateral exchanged system based on the philosophy that everyone's time is valued equally. Time credits are given to the person who provides social services, such as citizen participation and elderly care. People receive the desired services using time credits or donating them. If this system were applied to the Gangwon Province in accordance with its characteristics, it would help to reduce the elderly's prejudices and manage their diverse health problems. A virtual local currency using IT technologies is needed to boost the regional economy. The elderly's participation in TB is strongly needed. Future research about the effectiveness of health management is then discussed.

• 한국콘텐츠학회논문지
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• 제19권10호
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• pp.560-567
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• 2019

고령사회에 접어든 우리나라는 앞으로 다가올 2025년 초고령사회 진입을 앞두고 있다. 고령 인구의 증가와 함께 고령운전자의 교통안전 사고는 사회적 문제로 자리 잡았다. 본 연구는 초고령사회를 앞두고 고령자가 운전 중 발생하는 교통사고를 방재디자인을 통해 예방하기 위한 연구를 진행하였다. 이론적 연구를 위해 방재디자인의 개념 및 필요성, 고령사회 현황 및 고령운전자 신체적 인지적 특성, 고령자가 보는 교통신호등 형태 및 관련 정책 등을 살펴보았다. 또한, 디자인 제안을 위해 국제 표준화 기구의 교통안전 형태 및 색상을 조사 분석하고, 이를 바탕으로 교통신호등의 점진적 개선을 위해 1차, 2차 교통신호등 디자인 형태를 제안하였다. 1차 개선 형태는 기존의 신호등 두 렌즈 안에 삼각형, 넓은 면적의 화살표, 사각형을 표시하는 안이며, 2차 디자인 개선 형태는 새로운 신호등 두를 도입하여 크기가 커진 삼각형, 넓은 면적의 화살표, 사각형의 렌즈로 신호등을 구성하는 안이다. 이는 시각적으로 현재 교통신호등보다 명확한 형태 띠고 있어 노화로 인해 신체적 인지적 특성을 갖는 고령운전자가 더 나은 가시성과 시인성을 확보할 수 있으며, 운전 환경의 변화(우천, 폭설 등)에서도 현재보다 나은 반사적 반응을 할 수 있을 것으로 기대된다. 또한, 초고령사회를 대비해 교통신호등 이외의 교통안전표지에 대한 표준지침을 마련하기 위한 선행연구가 될 수 있을 것으로 기대된다.

• 대한금속재료학회지
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• 제48권1호
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• pp.19-27
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• 2010

This paper investigates the influence of aging time on creep properties via a small punch creep test and evaluates the microstructural change of P122 steel at $600^{\circ}C$. The area fraction of precipitates was quantitatively analyzed to identify the relationship between the creep rupture life and precipitates was coarsening behavior of precipitates along the grain boundaries was also investigated for various aging times. It is found that this coarsening behavior led to a loss of solution hardening and rewulte in a hardness drop and a reduction of creep life.