• 한국산학기술학회논문지
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• 제22권6호
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• pp.27-35
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• 2021

일반적으로, 태양광모듈은 20년 이상의 장기간 동안 사용할 수 있다고 알려져 있지만, 설치된 주변 환경요인(염분, 온도, 습도, 자외선, 음영 등)에 따라 다양한 열화현상이 발생하여, 전기적 성능과 수명이 크게 감소할 수 있어 태양광 모듈에 대한 정확한 열화특성 분석이 요구되고 있다. 그러나, 태양광모듈의 출력을 STC조건으로 보정하여 초기 사양과 비교분석하는 기존의 열화특성 분석방법은 데이터 보정 시 필연적으로 발생하는 데이터 오류로 인하여 객관성이 결여될 수 있다. 따라서, 본 논문에서는 태양광전원 모듈부와 모니터링부로 구성된 열화진단 시험장치를 구축하여 모듈별 출력 데이터를 측정 및 수집하고, 태양광모듈의 출력 변동성과 통신 에러 및 지연에 따른 영향을 최소화하기 위하여, MATLAB을 이용한 열화특성 분석 모델링을 통하여 실측 데이터를 평활화한다. 또한, 이를 바탕으로 태양광모듈의 열화 상태를 계절별 실측 출력특성에 따라 분석한 결과, 전체 구형모듈의 평균 열화율은 총 25.73%이고, 연평균 1.55%씩 열화됨을 진단할 수 있어, 본 논문에서 구축한 열화진단 시험장치의 유용성을 확인하였다.

• 한국기계가공학회지
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• 제18권1호
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• pp.31-37
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• 2019

This study investigates the effects of long-term artificial-aging on hardness variation in the dissimilar metal weldments for nuclear power plant facilities. These dissimilar welds are inevitably required to join the components in nozzle parts of pressurized vessels, such as austenitic stainless steels and ferritic steels. A artificial thermal aging was conducted in an electrical furnace to simulate material degradation at high temperatures. The test materials were held at the temperature of $600^{\circ}C$ for 10000 hours and interrupted at various levels of degraded specimens. The degradation of hardness is a well-known phenomenon resulting from long-term aging or high-temperature degradation of structural materials. In this study, the variation of hardness at each position was different, and complicated in relation to microstructures such as twins, grains, precipitates, phase transformations, and residual stresses in dissimilar weldments. We discussed the variation of hardness in terms of microstructural changes during long-term aging.

• 한국조리학회지
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• 제5권2호
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• pp.165-190
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• 1999

There are no reliable data about the effect on the baking industry in Korea yet. The damage caused by the product's aging is so much in the confectionary and baking industries. Therefore, the aging of bread is an economical problem which determines its commercial lifespan. In order to solve out this aging problem, this article dealt with the factors which give rise to the effect of starch on the aging and its inhibitory methods. 1. Control of the moisture content : Because the aging of starch occurs at 30~60% of moisture most frequently, controlling the moisture content above or below the above percentage can help restrain the aging to a certain degree. 2. Addition of sugars : The sugars become hydrated through hydrogenation with the moisture in the food. Thus, the sugars suppress the phenomenon of crumbling inside the food acting as a kind of dehydrator. 3. Use of an emulsifying agent : The emulsifying agent increases the stability of starch colloid liquid and suppresses the precipitation of starch molecules and the formation of crystallized range to prevent aging. 4. Method by freezing : The aging of starch does hardly occur reaching -2$0^{\circ}C$~-3$0^{\circ}C$ below zero. 5. Maintenance of warm condition : The freshness of bread is maintained at the 80% of humidity at 5$0^{\circ}C$.

• 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.

• 한국의류학회지
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• 제44권6호
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• pp.1070-1086
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• 2020

This study analyzed the size of women in their 60s, 70s and 80s in the 2014 Human Body Dimension Survey data among Size Korea's 7th Human Dimension Survey Data in 2015. This study examined the characteristics of changes in female body shape according to aging and the age range. The height item gradually decreased from the 60s and then rapidly decreased to the 80s. In the case of the circumference item, a sharp change occurred in the section from 69 to 70 years old. The reduction in hip height, waist height, and navel level waist height was not significant compared to the decrease in stature. Both width, thickness, and circumference gradually decreased with age. It can be seen that the back bends forward and the legs become thinner than the body due to the aging phenomenon with increasing age. Even for older women, the characteristics of aging differ in their 60s, 70s and 80s, so age segmentation of silver clothing should be considered.

• 한국실내디자인학회논문집
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• 제19권1호
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• pp.100-111
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• 2010

All of us have no time to predict and prepare for a rapidly-approaching future change in the 21st century, thereby being reality that we feel uneasy about future society. Accordingly, there is necessity for re-consolidating environment and daily culture in preparation for future society, namely, aging society. Given well preparing for super-aging society that will approach in the future, by which this effort becomes what bad luck often brings good luck, our country's role is thought to get probably bigger even in the globally silver industrial market in near future. We need to synthetically recognize a human being's aging psychological and physical conditions through the aging experience exhibition available for publicizing properly this historical phenomenon, and to pay more attention to importance of interaction between a human being and product environment. The experience exhibition is a concept for the exhibition form and the spatial composition, which emphasized interaction, with having escaped from the simply exhibition space. Given trying to communicate information more scientifically with escaping from the conventional exhibition of seeing and listening, it is also important to research Into the basis for exhibition as the experience space based on interaction. After all, a human being's aging is the unavoidably future phenomenon. And, importance of environment, which influences a human being, is very mutual as well. Our country is desired to develop a research on interaction of the exhibition experience space available for broadening recognition of senior-friendly and for properly experiencing this, thereby being an opportunity that the business entity, which plans silver industry, and the academic circles, which research and develop this, do mutually cooperate and can make silver industry grow further.

• Nutrition Research and Practice
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• 제17권4호
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• pp.597-615
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• 2023

Healthy aging can be defined as an extended lifespan and health span. Nutrition has been regarded as an important factor in healthy aging, because nutrients, bioactive food components, and diets have demonstrated beneficial effects on aging hallmarks such as oxidative stress, mitochondrial function, apoptosis and autophagy, genomic stability, and immune function. Nutrition also plays a role in epigenetic regulation of gene expression, and DNA methylation is the most extensively investigated epigenetic phenomenon in aging. Interestingly, age-associated DNA methylation can be modulated by one-carbon metabolism or inhibition of DNA methyltransferases. One-carbon metabolism ultimately controls the balance between the universal methyl donor S-adenosylmethionine and the methyltransferase inhibitor S-adenosylhomocysteine. Water-soluble B-vitamins such as folate, vitamin B6, and vitamin B12 serve as coenzymes for multiple steps in one-carbon metabolism, whereas methionine, choline, betaine, and serine act as methyl donors. Thus, these one-carbon nutrients can modify age-associated DNA methylation and subsequently alter the age-associated physiologic and pathologic processes. We cannot elude aging per se but we may at least change age-associated DNA methylation, which could mitigate age-associated diseases and disorders.

• 인지과학
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• 제24권2호
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• pp.111-132
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• 2013

노화에 따라 언어 기능은 다르게 변화한다. 의미 처리에서는 청년과 노인의 수행이 유사하지만 언어산출에서는 노인이 청년에 비해 기능이 감퇴한다고 보고되어 왔다. 설단현상은 음운 정보 산출에서의 실패를 잘 드러내주는 현상이다. 노인은 청년에 비해 설단현상을 더 빈번하게 보고하는데, 이에 대한 설명으로 차단 가설과 전달손실 가설이 제안되었다. 본 연구는 설단현상을 유도하는 질문을 사용하여 음운 정보 산출에서 노화의 영향을 살펴보았다. 실험에서 두 변인이 조작되었다. 첫 번째 변인은 연령조건으로, 참가자는 청년과 노인 집단으로 구성되었다. 두 번째 변인은 단어범주 조건으로, 자극은 총 5가지의 단어 범주로 구성되었다. 참가자는 표적단어에 대한 설명을 듣고 '안다', '모른다', '설단현상'의 세 가지 상태를 보고하였다. 실험 결과는 다음과 같다. 첫째, 청년에 비해 노인에게서 설단현상이 증가하였다. 둘째, 단어범주에 따른 설단현상의 차이가 있었다. 설단현상은 인물 이름, 장소 이름과 같은 고유명사에서 더 자주 발생하였다. 셋째, 설단현상이 더 자주 발생하는 단어범주에서 연령 차이는 더 크게 나타났다. 넷째, 설단현상을 겪는 동안 대안단어의 보고는 청년에 비해 노인이 적었다. 다섯째, 설단현상을 겪는 동안 표적단어에 대한 부분 정보는 글자 단위로 유지되는 경향을 보였다. 본 결과는 한국어 음운 산출에서 노화의 영향을 확인하고, 그 기제에 대해 전달손실가설의 설명을 지지한다. 또한, 한국어의 음운 및 표기 특성이 설단현상 동안의 정보처리과정에 반영되고 있음을 시사한다.

• 한국재료학회지
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• 제26권5호
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• pp.281-286
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• 2016

In the present study, the tensile properties and dynamic strain aging of an Fe-24.5Mn-4Cr-0.45C alloy were investigated in terms of strain rate. During tensile testing at room temperature, all the stress-strain curves exhibited serrated plastic flows related to dynamic strain aging, regardless of the strain rate. Serration appeared right after yield stress at lower strain rates, while it was hardly observed at high strain rates. On the other hand, strain-rate sensitivity, indicating a general relationship between flow stress and strain rate at constant strain and temperature, changed from positive to negative as the strain increased. The negative strain-rate sensitivity can be explained by the Portevin Le Chatelier effect, which is associated with dynamic strain aging and is dependent on the strain rate because it is very likely that the dynamic strain aging phenomenon in high-manganese steels is involved in the interaction between moving dislocations and point-defect complexes.

• 드라이브 ㆍ 컨트롤
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• 제12권4호
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• pp.28-34
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• 2015

Because heavy-duty construction vehicles such as excavators are required for good engine-room cooling capacity, a hydraulic gear motor is adopted in the cooling fan drive mechanism to actively control the output speed, instead of adopting the conventional ON/OFF type belt drive. While gear motors are normally limited to 140bars of operating pressure, those for the cooling fan are capable of operating at continuous pressures of up to 220bars. After assembly, all gear motors for high pressure must pass an aging test which is a kind of the wearing process between the gear teeth and motor housing. During the aging process with gradual pressure increments, gear sticking sometimes occurs due to abnormal wear, resulting in defects. This paper focuses on a gear-sticking free aging test controller that is designed together with the knowledge of an experienced operator and the analysis results of experimental data of the gear jamming phenomenon. From the aging experiment, it is demonstrated that the developed controller that can alter the setting pressure of the load pump is effective for stabilizing the abrupt increase in the motor input pressure, thus preventing the hydraulic motor from stopping. This is expected to be helpful for the reduction of defects and increase in productivity.