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        검색결과 408

        41.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The purpose of this study was to investigate directions for future smart city transportation policies and service development by evaluating road service satisfaction levels and predicting future service demand. METHODS : A nationwide survey was conducted in Korea to develop a transportation service evaluation system based on the functions and objects of transportation. The satisfaction level of road service was evaluated using an analytic hierarchy process (AHP), promising service sectors were identified using the revised importance-performance analysis (IPA) technique, and detailed service demands by sector were suggested. RESULTS : The most valuable service value felt by the people was "safety" (weight 0.4), and the overall satisfaction level was 68.9 points, slightly exceeding "normal." As a result of analyzing the promising service sectors by dividing them into urban and rural areas, "handicapped, elderly, and pedestrians" were important in both areas, and "road facility maintenance" was classified as an additional promising sector for rural areas. CONCLUSIONS : People demand that future smart city transportation policies and services should be "people" and "safety" centered. In addition, it is necessary to pay attention not only to the development of new services but also to the improvement of problems with existing services and policies.
        4,000원
        42.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The collapse of reinforced concrete (RC) frame buildings is mainly caused by the failure of columns. To prevent brittle failure of RC column, numerous studies have been conducted on the seismic performance of strengthened RC columns. Concrete jacketing method, which is one of the retrofitting method of RC members, can enhance strength and stiffness of original RC column with enlarged section and provide uniformly distributed lateral load capacity throughout the structure. The experimental studies have been conducted by many researchers to analyze seismic performance of seismic strengthened RC column. However, structures which have plan and vertical irregularities shows torsional behavior, and therefore it causes large deformation on RC column when subjected to seismic load. Thus, test results from concentric cyclic loading can be overestimated comparing to eccentric cyclic test results, In this paper, two kinds of eccentric loading pattern was suggested to analyze structural performance of RC columns, which are strengthened by concrete jacketing method with new details in jacketed section. Based on the results, it is concluded that specimens strengthened with new concrete jacketing method increased 830% of maximum load, 150% of maximum displacement and changed the failure modes of non-strengthened RC columns.
        4,000원
        43.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study evaluates the long-term performance of the asphalt overlay designed by the Seoul pavement design method which determines overlay thickness by considering existing pavement conditions, traffic volume, and bearing capacity of the pavement. METHODS : A total of 76 sections including 17 control sections and 59 design sections were constructed under various traffic conditions, overlay thicknesses and asphalt mixtures. The performance of the pavements has been monitored up to 60 months in terms of surface distresses, rutting, and longitudinal roughness. The service life of the pavements was estimated to be the period when the Seoul pavement condition index (SPI) becomes 6.0, i.e., a rehabilitation level. RESULTS : Overall, the service life of the pavements was 72 months in the control and 120 months for the design sections. For relatively thinner overlay sections than designed, the service life reduced significantly; 36 months for 15cm thick overlay and 120 months for 25cm thick overlay. The service life of the pavement in the bus-only lane was 78 months, which is 30 months shorter than that in mixed-traffic lanes. Out of the bus-only lanes, 56% of the pavement along bus stop was deteriorated early to be a poor condition while only 2% of the pavement in a driving lane was degraded to be poor. The overlay with Stone Mastic Asphalt (SMA) in the wearing surface had 38% longer life than that with conventional dense graded mixtures. CONCLUSIONS : Most of the overlays sections designed by the Seoul pavement design method were expected to survive 10 years, except for bus-only lanes. The control sections having 5 to 10 cm thick overlays showed significant lower performance than the design sections. Thus proper thickness and materials considering the characteristics of existing pavement and traffic volumes should be applied to secure the service life of overlays.
        4,000원
        44.
        2022.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study evaluated the Protaetia brevitarsis larvae powder’s characteristic changes using hot air drying (60±2.5oC, 12 h) with different pre-treatment methods, including two sacrifice methods, two storage temperatures, and two defatting processes. Appearance, yield, moisture contents, pH, color, proximate analysis, volatile basic nitrogen level, DPPH radical scavenging activity, and total phenol content were assessed. Results revealed that a combination of blanching, defatting, and -20oC storage temperature resulted in higher total phenol contents, lower water contents, and lower volatile basic nitrogen levels than other methods. Defatted treatment resulted in a higher L-value than the non-defatted treatment. Taken together, these results indicate that a combination of -20oC storage, blanching, and defatting is the optimal pre-treatment method for obtaining P. brevitarsis larvae powder with high total phenol content, low water content, and low volatile basic nitrogen, taking into account cost efficiency considerations.
        4,000원
        45.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The acrosome cap allows sperm to penetrate the egg membrane and produce male pronuclei within female chicken eggs, facilitating successful fertilization. Given this, it is important to establish practical methods for evaluating the integrity of the acrosome cap and thus the quality of the rooster’s sperm. There are several established methods for evaluating the acrosomes of mammalian sperm, but none of these methods are suitable for evaluating the acrosome status of rooster spermatozoa. Therefore, a simplified method for evaluating the rooster acrosome is needed. Here we evaluated the usefulness of CBB (coomassie brilliant blue) staining of the acrosome at concentrations of 0.04%, 0.08%, and 0.3% CBB solutions. Our data revealed a clear staining pattern for intact acrosome caps at 0.04% and 0.08% CBB but not at 0.3% CBB. This protocol revealed differences in acrosome integrity between fresh and frozen rooster sperm smears suggesting that CBB staining may facilitate easier semen evaluation in roosters. This protocol allows for the accurate differential staining of acrosome cap in rooster spermatozoa.
        4,000원
        46.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the case of columns in buildings with soft story, the concentration of stress due to the difference in stiffness can damage the columns. The irregularity of buildings including soft story requires retrofit because combined load of compression, bending, shear, and torsion acts on the structure. Concrete jacketing is advantageous in securing the strength and stiffness of existing members. However, the brittleness of concrete make it difficult to secure ductility to resist the large deformation, and the complicated construction process for integrity between the existing member and extended section reduces the constructability. In this study, two types of Steel Grid Reinforcement (SGR), which are Steel Wire Mesh (SWM) for integrity and Steel Fiber Non-Shrinkage Mortar (SFNM) for crack resistance are proposed. One reinforced concrete (RC) column with non-seismic details and two columns retrofitted with each different types of proposed method were manufactured. Seismic performance was analyzed for cyclic loading test in which a combined load of compression, bending, shear, and torsion was applied. As a result of the experiment, specimens retrofitted with proposed concrete jacketing method showed 862% of maximum load, 188% of maximum displacement and 1,324% of stiffness compared to non-retrofitted specimen.
        4,000원
        47.
        2022.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Copper nanoparticles (CuNPs) are considered of great importance due to their high catalytic and antimicrobial activities. This study focuses on the preparation and characterization of CuNPs, and on their antibacterial/antifungal activities. A copper salt (copper sulfate pentahydrate) as precursor, starch as stabilizing agent, and ascorbic acid as reducing agent were used to fabricate CuNPs. The resulting product was characterized via different techniques such as X-ray diffractrometry (XRD), Fourier Transform Infrared (FTIR) spectroscopy, and Scanning electron microscopy (SEM) to confirm its characteristic properties. Employing the Scherrer formula, the mean crystallite sizes of copper (Cu) and cuprous oxide (Cu2O) nanocrystals were found to be 29.21 and 25.33 nm, respectively, as measured from the main X-ray diffraction peaks. The functional groups present in the resulting CuNPs were confirmed by FTIR. In addition, the engineered CuNPs showed antibacterial and antifungal activity against tested pathogenic bacterial and fungal strains.
        4,000원
        48.
        2022.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Based on the nonlinear static analysis and the approximate seismic evaluation method adopted in “Guidelines for seismic performance evaluation for existing buildings, two methods to calculate strength demand for retrofitting individual structural walls in unreinforced masonry buildings are proposed.” The displacement coefficient method to determine displacement demand from nonlinear static analysis results is used for the inverse calculation of overall strength demand required to reduce the displacement demand to a target value meeting the performance objective of the unreinforced masonry building to retrofit. A preliminary seismic evaluation method to screen out vulnerable buildings, of which detailed evaluation is necessary, is utilized to calculate overall strength demand without structural analysis based on the difference between the seismic demand and capacity. A system modification factor is introduced to the preliminary seismic evaluation method to reduce the strength demand considering inelastic deformation. The overall strength demand is distributed to the structural walls to retrofit based on the wall stiffness, including the remaining walls or otherwise. Four detached residential houses are modeled and analyzed using the nonlinear static and preliminary evaluation procedures to examine the proposed method.
        4,000원
        49.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 대목용 호박 계통들의 내냉성을 다양한 방법들로 평가 후 상호 비교하고, 수박과 접목 후 포장에서 나타나는 내냉성 양상과 비교하여 수박 재배용 호박 대목개발에 활용 가능한 내냉성 자원선발 방법을 제시하고자 수행하였다. 그 결과 내냉성 평가에 간접적으로 사용하고 있는 발아검정, 유묘 생육 및 피해검정, 단근삽목 검정법은 접목 후 포장에서 검정한 결과와 상관관계를 보이지 않았다. 포장검정 결과와 상관관계를 보인 검정법은 유묘를 1℃로 1일 처리하고 엽록소형광 값을 측정한 방법과 유묘를 1℃로 2일 처리 후 떡잎의 저온피해 정도를 비교한 방법이었고, 그 중 떡잎의 저온피해 정도를 비교한 방법이 포장검정 결과와 더 높은 상관관계(r=0.480, p=0.002)를 보여 내냉성 대목 선발에 더 적합한 것으로 나타났다.
        4,000원
        51.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 논문에서는 박스형 전력구의 지진응답해석에 사용되는 응답진도법의 보수성을 평가하였다. 이를 위해 25가지 전력구 단면과 각 전력구에 대한 2개의 지반조건을 고려한 총 50개 예제를 선정하였다. 응답진도법의 보수성을 평가하기 위해 동적 지반-구조물 상호 작용을 고려한 정밀해석법에 의한 응답과 비교하였다. 비교결과, 정밀해석 응답에 대한 응답진도법에 의한 응답의 비로 정의한 응답 비의 평균이 1.0에 근접하며, 응답비의 표준편차도 5% 이내로 매우 작아서, 응답진도법에 의한 해석이 정밀해석법과 일관됨을 알 수 있었다. 마지막으로 응답진도법에 의한 응답에 하중계수 1.1을 적용하면 전력구의 보수적인 내진설계가 가능할 것으로 나타났다.
        4,000원
        53.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        연층을 가지는 건축물들의 피해사례가 관측됨에 따라 기존 건축물 내진성능평가시 수직비정형의 고려가 중요해졌다. 하지만 기존 방법은 수직비정형을 충분히 반영하기 어렵기 때문에 수직비정형을 가지는 건축물에 대해 내진성능을 과소 혹은 과대평가할 여지가 있다. 본 연구는 강성기반 연층비(Soft Story Ratio, SSR)를 이용해 수직비정형 건축물의 내진성능평가 기법을 개발하는데 목적이 있다. SSR은 변위에 대한 요구량과 능력의 비율을 나타내고, 강성차이에 의한 수직비정형을 고려하여 건축물의 변위집중 비율을 의미하는 파라미터다. 1층 기둥을 변수로 하는 필로티 건축물 네 개를 대상으로 개발한 내진성능평가 기법을 기존의 내진성능평가 기법과 비교하였다. 기존 기법은 수직비정형이 극대화되는 모델에 대해 내진성능을 과대평가하는 경우가 발생하였다. 반면 제안된 기법은 모든 모델에 대해서 상세평가의 결과와 동일했다. 따라서 제안하는 내진성능평가 기법은 수직비정형이 극대화되는 필로티 건축물에서 기존의 방법보다 정밀하게 내진성능평가 결과를 제공할 수 있다고 사료된다.
        4,000원
        57.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The railroad facilities are intended for long-term operation as the initial acquisition costs necessary for infrastructure construction are high. Therefore, regular maintenance of railroad facilities is essential, and furthermore, system reliability through systematic performance evaluation is required. In this study, the signal control system of railroad electrical equipment was selected as the subject of research and the performance evaluation target facility selection study was conducted using AHP. The results of the study can contribute to the reliability of the signal control system as well as to the reliability of the railroad system, which is a higher system.
        4,000원
        58.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        콘크리트는 안전성과 경제성이 우수한 재료로 인식되어 많은 사회기반시설물의 건설재료로 이용되어 왔으나, 최근에는 노후화 현상 등으로 인한 성능저하가 발생하고 있으며 이는 직·간접적으로 경제적·인명적 피해의 원인이 되기 때문에 여러 가지 보강을 실시하고 있다. 본 연구에서는 복합섬유소재를 활용하는 보강공법을 포함한 다양한 보강공법에 대한 성능비교 실험연구를 수행하고 분석하였다.
        4,000원
        59.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적 : 본 연구에서는 다양한 방법들을 이용하여 토릭렌즈 마킹 회전량을 평가할때 일치도를 평가측정하고자 하였다. 방법 : 모형안과 콘택트렌즈 착용이 가능한 57안(평균 24.79±1.29세)을 대상으로 토릭소프트렌즈를 제조사의 가이드라인에 따라 피팅한 후, 사진 촬영, 각도기 어플리케이션, 휴대용 돋보기와 세극등 현미경을 사용하여 회전 평가를 진행했을 때의 서로 다른 검사자 간의 검사 결과값을 비교 분석하였고, 서로 다른 회전평가 방법 간의 일 치도는 블랜드 알트만 분석을 사용하였다. 결과 : 서로 다른 검사자 간 같은 회전평가 방법으로 토릭소프트렌즈의 회전량을 측정하였을 때, 측정값의 평 균 차이가 사진 촬영, 각도기 어플리케이션, 휴대용 돋보기, 세극등 현미경 평가 방법 각각 –0.50, -0.70, -0.30, -0.13°로 유사한 결과를 보였다. 회전평가 방법 간 비교에 대해서는 사진 촬영과 각도기 어플리케이션을 사용했을 때, 허용 오차 범위(5°) 내의 측정값이 각각 74.56%, 75.44%로 비교적 낮은 신뢰도를 보였고 휴대용 돋 보기를 사용한 방법에서는 95.61%로 높은 신뢰도를 보였다. 결론 : 토릭소프트렌즈 처방에서 세극등 현미경을 사용할 수 없어도 사진 촬영, 핸드폰 각도기 어플리케이션, 휴대용 돋보기를 통해 토릭소프트렌즈 회전평가에 대한 임상적으로 유용한 결과를 얻을 수 있다.
        4,200원
        60.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The resilience performance evaluation method of a structure can evaluate the ability to recover after an earthquake disaster, and this study deals with the consideration and introduction of the resilience performance evaluation method. The resilience evaluation method can be expressed as a quantified number by constructing a loss estimation model and a recovery evaluation model. The recovery evaluation model should consider downtime in addition to the repair time, and the loss estimation model should consider not only direct loss to structures and non-structures, but also indirect loss due to functional loss of the building. In addition, to build a loss estimation model, the structure should be simplified to perform an efficient analysis. Therefore, in this study, the equivalent terminal induction system proposed cantilever-type and rahmen-type SDOF, and it is evaluated somewhat conservatively compared to the example structure, and it is judged that there is a need to improve the hysteresis characteristics by applying the stiffness reduction factor of the SDOF model.
        4,000원
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