• 한국도로학회논문집
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• 제18권6호
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• pp.41-50
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• 2016

OBJECTIVES : In this study, microstructural components of crumb rubber modified asphalt (CRMA) binder were investigated using environmental scanning electron microscope (ESEM). To clearly understand the elemental composition of the CRMA binder, energy dispersive X-ray spectroscopy (EDX) was employed on the ESEM samples. METHODS : CRMA binders were produced using open blade mixers at $177^{\circ}C$ for 30 min. The binders were artificially aged through a series of accelerated aging processes. Sample preparation was done by making a mold shape on the glass slide. Thereafter, the morphology of the CRMA binder was observed using the ESEM coupled with the EDX. RESULTS : The images captured from the ESEM indicate that the unaged CRMA binder appears to have a single-phase continuous nonuniform structure after the addition of crumb rubber particles, whereas the artificially aged CRMA binder was observed to have two different phases. ESEM coupled with EDX shows detailed internal structure of the modified binders compared to other technologies (i.e., optical microscopy, atomic force microscopy, and conventional scanning electron microscope). CONCLUSIONS : The captured images resemble the internal structures such as the viscous properties of the unaged CRMA binder and the interaction between the rubber particles and the base binder at aged condition. ESEM is a powerful instrument and with the introduction of EDX, it provided more details of the network microstructure of the asphalt binder. ESEM coupled with EDX is recommended for use in future investigation of microstructure of asphalt binders.

• 한국농촌건축학회논문집
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• 제21권4호
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• pp.17-24
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• 2019

It has been long time since the local small-and-medium cities had lost their vitality due to the progress of aging, economic decline in urban areas, the lack of new growth engines, and the declining population in korea. In addition, since the implementation of the local self-governing system, the creation of new urban areas and the transfer of the administrative institutions to the outskirts of a city have accelerated the decline of old downtown. Rather, local small-and-medium cities would have a problem to make urban regeneration impossible. Under the recognition of such problems, individual self-governing entities have come up with numerous policies and implemented various policies for the revitalization of local small-and-medium cities, but it is a condition that the effect of their efforts falls shorts of expectations, such as the space of the similar style, which has been widespread in developed countries, simple restoration, and a few structural changes. In this regard, the part to be realized anew is to enhance the attractiveness of small-and-medium cities. However, is not possible to raise the overall attractiveness in a short time in reality. To select local assets to be utilized in urban regeneration, it is judged that gathering opinions of local residents is more important than any other thing. Accordingly, this study intends to present positive outcome for the purpose of the revitalization of local small-and-medium cities by finding the factors which can remind us of the collective memory of Jinju city and selection the critical factors to determine a detailed project plan from the perspective of urban regeneration.

• Tribology and Lubricants
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• 제35권4호
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• pp.222-228
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• 2019

As rubber products such as O-rings, which are also known as packings or toric joints, come in regular, long term contact with liquid fuel, they can eventually swell, become mechanically weakened, and occasionally crack; this diminishes both their usefulness and intrinsic lifetime and could cause leaks during the steady-state flow condition of the fuel. In this study, we evaluate the lifetime of such products through compression set tests of FKM, a family of fluorocarbon elastomer materials defined by the ASTM international standard D141; these materials have great compression, sunlight, and ozone resistance as well as a low gas absorption rate. In this process, O-rings are immersed in the liquid fuel of airtight containers that can be expressed as a compression set, and the liquid fuel leakage in a flow rig tester at variable temperatures over 12 months is investigated. Using the Power Law model, our study determined a theoretical O-ring lifetime of 2,647 years, i.e. a semi-permanent lifespan, by confirming the absence of liquid fuel leakage around the O-ring assembled fittings. These results indicate that the FKM O-rings are significantly compatible for fuel tests to evaluate long-term sealing conditions.

• 한국구조물진단유지관리공학회 논문집
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• 제23권1호
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• pp.122-129
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• 2019

콘크리트에서 염소 이온과 같은 열화물질의 이동은 응력상태 및 재령의 증가에 기인한 공극구조에 따라 변화한다. 본 연구에서는 재령 28일, 91일, 그리고 365일 양생된 OPC 콘크리트의 압축 및 인장 하중조건을 고려하여 촉진탄산화 실험을 실시하였으며, 탄산화 거동을 평가하였다. KS F 2584에 의거하여 탄산화 속도계수를 도출하였는데, 하중을 고려하지 않을 경우 탄산화 속도계수는 재령 28일 대비 재령 91일은 50.0 % 수준으로, 재령 365일에서는 44.8 % 수준으로 감소하였다. 28일 재령 시, 하중의 영향으로 인해 인장재하영역에서는 103.9 ~ 108.8 % 수준으로 압축재하영역에서는 91.9 ~ 104.6 % 수준으로 변화하였다. 재령이 증가함에 따라 탄산화 속도는 크게 감소하였는데, 30 % 인장재하영역에서는 탄산화 속도계수가 1년 경과시 47.3 % 수준으로, 60 % 인장재하영역에서는 52.5 % 수준으로 감소하였으며 30 % 압축재하영역에서는 45.8 %로, 60 % 압축재하영역에서는 44.9 % 수준으로 감소하였다. 압축재하영역 30 %에서는 공극압밀로 인해 탄산화 속도계수가 감소하였으나 하중의 증가에 따라 압축재하영역 60 %에서는 미세균열의 영향으로 탄산화 속도계수가 증가하였다. 또한 인장재하영역은 압축부와는 다르게 탄산화 속도계수가 선형적으로 증가하는 경향을 나타내었다.

• 한국구조물진단유지관리공학회 논문집
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• 제26권6호
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• pp.93-101
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• 2022

국내 RC 슬래브교의 경우 공용연수가 20년 이상인 교량이 전체의 70% 이상을 차지하며, 노후화된 구조물의 수가 증가함에 따라 구조물의 안전 진단 및 유지관리의 중요성이 증가하는 실정이다. 고속도로 교량의 경우 바닥판 균열은 열화현상의 우선적인 원인이 되며, 교량 내구성 및 사용수명 저하에 밀접한 관계가 있다. 또한 신축이음과 교량받침 등의 부재 손상으로 인한 손상 발생 비율이 약 73%로 주부재보다 높다. 따라서 본 연구에서 교량 부재 손상과 바닥판 열화가 결합된 손상 시나리오를 정의하였다. 설계하중으로는 일교차를 고려한 온도 증감과 차랑햐중을 고려하여 개별 단일 손상 및 이종손상 시나리오 발생 시 바닥판 응력 분포와 최대 응력 발생 지점을 비교 분석하였다. 또한 바닥판 열화의 주요한 원인이 되는 균열의 점검 및 진단이력데이터 기반으로 공용연수 별 손상 시나리오에 대한 손상확산 분석 및 상태등급 예측을 수행하였다. 교량부재 손상이 동반되어 발생하는 이종손상의 경우 단일손상 대비 균열 면적율과 손상확산율이 증가되며, 상태등급 C에 도달하는 시기도 매우 빠를 것으로 예측된다. 따라서 교량부재 손상이 발생하였을 때, 신속한 보수 및 교체가 이루어지지 않으면 바닥판의 손상 발생과 손상 확산으로 인한 2차 피해를 유발하는 원인이 될 수 있다. 따라서 바닥판 응답에 대한 지속적인 관찰과 대응이 필요할 것으로 판단된다.

• 한국농촌건축학회논문집
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• 제24권1호
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• pp.27-36
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• 2022

Currently the population of rural areas in Korea continue to decline due to low birth rate, aging population, and migration. This phenomenon is accelerated over time. And as a result, there are some declining phenomenon in rural society. And it is same in the residential and basic living conditions of rural villages. The increase ratio of empty houses exacerbates the rural landscape, acts as a cause of crime and bring out various social and economic problems such as worsening settlement conditions and local slums. The study is carried out to prevent this phenomenon by investigating the architectural contents of empty houses in the village, surveyed residents and owners and finally analyzed and synthesized to make a plan to utilize empty houses in the village. This study was conducted from June to December 2021. The conclusions are followings: 1. The empty houses in Korea were 1,511 million in 2020, 8.2% of the total number of houses, whereas those in Jeollabuk-do were 95,412, 12.9% of those of houses, and those in Gimje-city, the subject of this study, were 5,944. It is up to 15.8%. In particular, empty houses in Hacheon village, the site of this study, accounted for the highest ratio, with 25% of the total number of houses. 2. To understand the utilization and improvement of empty houses, surveys and interviews were conducted to residents and owners of Hacheon village in Gimje, and most of the residents submit proposals that empty houses were not desirable in terms of village landscape and safety. The owners don't have intentions of selling or leasing them. They want to remodel them and rent for a specific period. 3. As the physical condition of the empty houses(9empty houses) 6 empty houses of them are good. 4 of them are in poor condition. 4. By synthesizing these contents, nine empty houses in Hacheon village will be remodeled as the space for those of rural start-up young people, smart farm area, community space and rental housings for rural returnees.

• 디자인학연구
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• 제16권4호
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• pp.313-322
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• 2003

우리나라는 고령인구의 증가추세 속에서 가족에 대한 가치관의 변모로 양로원과 같은 주거복지시설이 지속적으로 증가하고 있으며, 그간의 증가 속도를 감안한다면 앞으로 전체 사회 복지시설 대비 양로원이 차지하는 비율과 수용인원의 수는 가속화될 것으로 예측된다. 한편, 고령자는 약 60%가 장애인 수준에 가까울 정도로 심신의 기능이 저하되어 있어 이들의 독립적 생활을 지원하는 특별한 환경적 배려가 반드시 필요하다고 하겠다. 본 연구는 환경적 요소 가운에 색채가 고령자의 원활한 인식작용과 커뮤니케이션, 심리적 치료효과에 중요한 인자임을 인식하여 고령자 시설이 이들의 요구조건을 수용하기에 적절한지를 파악하는데 연구목적이 있다. 이를 위해 고령자환경에서 색채가 지니는 중요성 및 효과, 고령자의 시각적 특성 및 색채에 대할 반응을 문헌을 통해 조사하였으며, 서울$.$경기도 지역의 10개 양로시설에 대한 현장방문을 통해 실내환경의 색채현황을 조사하였다. 그리고 대상시설의 주요 공간인 로비/라운지, 복도, 식당, 침실, 계단실/경사로 등 5개 영역에 대한 측색 결과를 문과 스펜서의 색채조화론에 기초하여 색의 3속성별 조화정도와 미도를 정량적으로 평가하였고 색채 경향을 분석하여 적정성 여부를 평가하였다.

• 한국작물학회지
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• 제45권5호
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• pp.305-309
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• 2000

Ultra-drying [＜5.0% seed moisture content (SMC)] storage technique is a cost-effective storage method for oily seeds. To decide proper ultra-drying condition for soybean seeds, drying rate was compared three silica gel to seed ratios, two seed sizes with varietal difference, two kinds of container, and three seed amounts per container under :t 23$\pm$1$^{\circ}C$. When the relative humidity (RH) was reduced at the rate of less than 0.1 % a day, silica gel was replaced with dry one by 47 days. Higher silica gel to seed ratios (3:1 and 2:1) dried faster than lower ratio (1:1) until 28 days, but not after 43 days of drying. Also, large seeded variety was dried faster than small seeded variety. Kinds of container and seed amounts per container didn't show differences in drying of soybean seeds. After completion of ultra-drying, percentage germination by standard germination test (SGT) was not different among silica gel to seed ratios, kinds of container, and seed amounts per container, except among seed sizes (varieties). Before SGT, soybean seeds were premoistened using saturated ${CaCl}_2$ for 48 hours and ${NH}_4$Cl for 24 hours in desiccators. To compare germinability between ordinary-dried seeds and ultra-dried seeds, the seeds of seven soybean varieties, which were varying in size from 8.1 to 34.9 g per 100 seeds, were dried using same amount of silica gel under 23$\pm$1$^{\circ}C$. After completion of 76 days of drying, SMCs were reduced to 3.13-3.45% from 7.86-8.82%. SMC after completion of drying was not correlated with 100-seed weight (r=0.556). Before germination tests, soybean seeds were premoistened using saturated salt solutions. Percentage germination was higher with ultra-dried seeds than ordinary-dried seeds in SGT and higher with ordinary-dried seeds than ultra-dried seeds in AAT at the beginning of storage and after 6 months storage, but general trend of percentage germination was not observed among varieties classified by 100-seed weight. From these results, we concluded that further studies are needed to improve ultra-drying storage method for soybean seeds.

• 대한의용생체공학회:의공학회지
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• 제45권1호
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• pp.10-19
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• 2024

The purpose of this study is to conduct a summative evaluation of the usability of a general-purpose ventilator to determine whether it can be used for its intended purpose in the intended environment by the intended user and to find possible errors in use. The importance of ventilators has increased due to the accelerated aging of the population and the impact of the pandemic. In addition, patients who require ventilators are often in critical condition, so even a small error in use can be fatal. Therefore, it is important to ensure that the ventilator has sufficient stability and can be used satisfactorily without inconvenience to the user. In this study, we conducted a usability test with 17 respiratory nurses with more than 3 years of experience using the ventilator. We analyzed the task success rate, satisfaction, and opinions of the intended users while going through a total of 17 scenarios. Satisfaction was captured through an ASQ questionnaire and subjective opinions were captured through a detailed opinion questionnaire. The results showed a high level of satisfaction with an average score of 6.3 for the use scenarios. Evaluators expressed satisfaction with the overall visibility and versatility of the features, but noted that improvements were needed for calibration tasks with low task success rates. As the calibration method is different from other equipment, it was suggested that specific explanations of the calibration method and the picture that appears when calibrating are needed, and that if relevant training is provided, the equipment can be used without problems. If the usability evaluation is not limited to securing efficiency and satisfaction from the intended users, but also continuously receives feedback from users to prepare for use in emergency environments such as pandemic situations, it will be very helpful to seize opportunities such as emergency authorization in future situations, and ultimately contribute to patient safety by reducing use errors.