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        검색결과 3,332

        142.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 CFRP sheet의 RC 보에 대한 부착 보강 시 충분한 정착길이를 확보하고 조기파괴를 방지하기 위한 보 강 방법을 제안하였다. 제안된 방법의 보강 성능을 실험적으로 측정하기 위해 총 3개의 RC 보 실험체를 제작하였으며, 실험 변 수로 무보강(ORB), 하단 보강(FRB), 그리고 사선 보강 방법(XRB)이 있다. 실험은 4 점 재하로 설계하였다. 실험 결과는 휨에 의 한 파괴 양상 및 최종 파괴형태, 항복점 및 최대점, 강성, 그리고 처짐 등으로 분석하였다. 분석 결과 FRB는 단부파괴박리가 발 생하였으나, XRB는 정착 효과로 인해 인장파괴형태를 나타내었다. 휨 강도 및 항복강도 모두 XRB가 가장 크게 나타났다. 휨에 의한 강성 증가와 처짐에 대한 구속 효과 또한 XRB이 가장 크게 나타남을 실험을 통해 확인하였다.
        4,000원
        149.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study analyzes the effectiveness of different types of children's safety devices in a school zone. The analysis targets are yellow carpet type A (installed up to the floor and wall) and yellow carpet type B (installed only on the floor). METHODS : Based on field data collected at a school zone in Seoul, statistical tests were conducted to compare three different pairs of data: (1) none vs. yellow carpet type A, (2) none vs. yellow carpet type B, and (3) yellow carpet types A and B. The test employed two different measures: (1) the level of drivers’ eye attention and (2) the level of the vehicle deceleration rate. The study utilized software named "Visual Attention Software" to quantify the level of drivers’ eye attention at the location where children pedestrians were waiting for a green signal. It also utilized the Vegas (pro 17) image processing software to reduce the cruising speed data frame-by-frame from the video streaming data. The image data used in this study were collected with (1) camcorders attached to a test vehicle and (2) a drone aerial imaging technique. RESULTS : It was found that the level of the drivers’ eye attention level improved in the daytime when either of yellow carpet types A and B was placed; moreover, the safety enhancement effects were statistically identical. However, in nighttime, the measures only improved when the yellow carpet type A was placed. It was learned that yellow carpet type A provides significant safety effects according to both measures, i.e., the level of drivers’ eye attention and cruising speed. CONCLUSIONS : The test results suggest that the yellow carpet type A should be installed in school zones to maximize the safety effects of yellow carpets.
        4,200원
        150.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study proposes brief guidelines for traffic engineers in the field to refer to when operating tram priority signals based on the "early green" and "green extension" methods. METHODS : A set of VISSIM simulation analyses was conducted considering various traffic and control conditions in a hypothetical corridor consisting of two signalized intersections. The traffic conditions were varied at five different levels. The control conditions were varied at twenty-five levels by changing the tram priority traffic signal control parameters, i.e., the early green unit time and green extension unit time. A total of 125 simulation runs were from these combinations. A set of optimal signal timings for ordinary non-tram vehicles was prepared with TRANSYT-7F and implemented for the simulation. A tram priority signal control module based on VISVAP was exclusively developed for this study. RESULTS : As expected, no specific trend was found in the relationship between the two tram priority control parameters (early green time and green extension time). However, a trend was observed when assuming that the early green and green extension operations were mutually exclusive. Specifically, an inverse trend appeared between the tram priority control parameter values and level of congestion according to the performance measure (average network delay). CONCLUSIONS : For the early green control parameters, it is better to provide six seconds when undersaturated and four seconds when near-saturated. For the green extension control parameter, four seconds is suitable.
        4,000원
        151.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the vertical distribution and vascular plants in the Gakho mountain. Form the results of three field surveys from May 2022 to September 2022, a total of 478 total taxa, representing 426 species, 11 subspecies, 35 varieties, four forms, and two hybrids were identified, which were categorized in 282 genera and 94 families. We identified the elevational distribution ranges of 398 taxa of vascular plants. Among them, 19 taxa were endemic to Korea, one taxon was identified as a rare plant. The floristic target plants amounted to 72 taxa, specifically two taxa of grade V, two taxa of grade IV, 16 taxa of grade III, 27 taxa of grade II, and 25 taxa of grade I. Further, 71 taxa were identified as northern lineage plants. A total of 19 taxa of alien plants were identified, with a Naturalized Index of 4.0%, an Urbanization Index of 6.6%, and three plants that disturbed the ecosystem. The result of analyzing the pattern of species richness showed a reversed hump shape with minimum richness at midhigh elevation. A cluster analysis showed a high degree of similarity between adjacent elevation sections that are geographically adjacent with similar habitat environments. Warmth index in the Gakho mountain ranged from 57.2°C · month to 84.2°C · month. Our results provide basic data on vascular plants and valuable information on elevational distribution ranges of current plant species in the Gakho mountain, which could serve as a baseline for comparison of the shifts in elevation under future climate change.
        6,900원
        152.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To investigate the effect of thinning intensity on environmental factors and ectomycorrhizal mushroom fruiting in forest ecosystems, we studied canopy closure, throughfall, soil temperature, soil moisture, light response of understory vegetation, and ectomycorrhizal mushroom fruiting in a 10-year-old pine forest after 34%, 45%, and 60% thinning. Canopy closure was significantly higher in the 34% treatment and control plots, ranging from 80–85% in April. However, in November, all thinning treatment plots showed a decrease of approximately 5–10% compared with the control plot. The 60% treatment plot had over 200 mm of additional throughfall compared with the control plot, and monthly throughfall was significantly higher by more than 100 mm in October. The soil temperature in each treatment plot increased significantly by up to 1°C or more compared with the control plot as the thinning rate increased. The soil moisture increased by more than 5% in the thinning treatment plots during rainfall, particularly in the 34% treatment plot, where the rate of moisture decrease was slower. The photosynthetic rate of major tree species (excluding Pinus densiflora)was highest in Quercus mongolica, with a rate of 7 μmolCO2·m-2·s-1. At a lightintensity of 800 μmol·m-2·s-1, Q. mongolica showed the highest photosynthetic level of 6 ± 0.3 μmolCO2·m-2·s-1 in the 45% treatment. The photosynthetic rate of Fraxinus sieboldiana and Styrax japonicus increased as the thinning intensity increased. The Shannon– Wiener index of mycorrhizal mushrooms did not significantly differ among treatments, but the fresh weight of mushrooms was approximately 360–840 g higher in the 34% and 45% treatments than in the control. Additionally, the fresh weight of fungi in the 60% treatment was 860 g less than that in the control. There were more individuals of Amanita citrina in the control than in the thinning treatment, while Suillus bovinus numbers increased by more than 10 times in the 34% thinning treatment compared with the control.
        4,200원
        157.
        2023.02 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        목적: 본 논문의 목적은 연구 문헌 중 요통 환자에게 보행운동을 적용한 무작위 대조군 실험설계를 메타 분석을 하여 통증과 장애지수에 대한 효과를 알아보고자 하였다. 방법: 본 논문은 다음 데이터베이스에서 검색하였다: Google scholar, PubMed, Sciencedirect, KISS, RISS, NDSL. 지난 10년간 영어나 한국어로 된 논문 중, 요통이 있는 환자들이 보행운동을 하였을 때, 통증과 장애지 수를 연구한 논문들을 검색하였다. 이 논문에는 (1) 요통이 있는 환자, (2) 중재에는 보행운동이 포함되며, (3) 평가 지표에는 통증과 장애지수가 포함되었다. 최종 결과로 35개의 논문을 확인하였고, 그중 15개의 논문이 충족되었다. 결과: 본 논문은 요통 환자를 대상으로 보행운동을 중재로 주었을 경우의 논문 15편을 최종적으로 선정하 였고 분석하였다. 통증과 장애지수와 관련되어 각각 12개의 논문을 분석하였다. 통증과 관련된 12개의 논문의 효과 크기는 중간의 효과 크기나 나타났고, 장애지수와 관련된 12개의 논문의 작은 효과 크기가 있었다. 결론: 보행운동은 요통 환자들의 통증을 감소시키고 장애지수를 줄이는데 유의미한 효과가 있다. 따라서 보 행운동은 요통을 지닌 사람들에게 긍정적인 영향을 미칠 것으로 사료된다.
        4,600원
        158.
        2023.02 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        Background/Objectives: 본 연구의 목적은 복부 브레이싱 운동과 복부 할로잉 운동을 결 합한 요부 안정화 운동프로그램이 20대 정상성인의 폐기능에 미치는 영향과 흡연자와 비흡 연자를 비교하여 그 차이를 알아보고자 하는 데 있다. Methods/Statistical analysis: 이를 위해 20대 정상성인을 대상으로 흡연집단(n=16)과 비 흡연집단(n=16) 두 그룹으로 모집하여 동일한 중재를 실시하였다. Findings: 흡연집단은 집단 내 기간 지남에 따라 폐기능 요인 중 FVC과 FEV1/FVC를 제 외한 FEV1과 PEF가 운동 전보다 유의하게 증가하였다(p<.05). 비흡연집단에서 기간 지남에 따라 폐기능 요인 중 FVC과 PEF를 제외한 FEV1, FEV1/FVC가 운동 전보다 유의하게 증가하 였다(p<.05). Improvements/Applications: 본 연구 결과, 복부 브레이싱 운동과 복부 할로잉 운동을 결 합한 요부 안정화 운동프로그램은 흡연집단과 비흡연집단 두 그룹의 폐기능 향상에 효과가 나타난 것을 알 수 있었다.
        4,900원
        159.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To improve the safety of tap water, a study was conducted on the introduction of sanitation safety certification system for water treatment plants(WTPs). In order to produce and supply safe tap, the inflow of pollutants should be blocked as much as possible during the tap water production process, and contaminated materials should be removed or inactivated to a safe level in the WTPs. In order to block the inflow of pollutants in WTPs, it is necessary to strengthen the sanitation management such as installation of facilities for preventing inflow and habitat of larvae, and to remove or inactivate pollutants in the tap water production process, strengthening the safety management such as enhanced turbidity management is needed. Sanitation and safety management in the WTPs can be significantly improved by introducing certification system of WTPs. This will induce continuous improvement in water purification plants with insufficient sanitation and safety management, and provide incentives for WTPs with good sanitation and safety management. In addition, when the WTPs sanitation and safety certification system is established, it is desirable to expand the proposed system from WTPs to the entire process of tap water production and supply.
        4,000원
        160.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The initial smoothness of concrete pavement surfaces must be secured to ensure better driving performance and user comfort. The roughness was measured after hardening the concrete pavement in Korea. When the initial roughness is poor, relatively large-scale repair works, such as milling or reconstruction must be performed. Hence, a method to measure the roughness of the concrete pavements in realtime during construction and immediately correct the abnormal roughness was developed in this study. METHODS : The profile of a concrete pavement section was measured at a construction site using sensors that were attached to the tinning equipment of the paver. The measured data included outliers and noise caused by the sensor and vibration of the paving equipment, respectively, which were further calibrated. Consequently, the calibrated data were input into the ProVAL program to calculate the roughness based on the international roughness index (IRI). Additionally, the profile of the section was re-measured using another method to verify the reliability of the calculated IRI. RESULTS : The profile data measured at the concrete pavement construction site were calibrated using methods, such as overlapped boxplot outlier removal and low-pass filtering. The outlier data from the global positioning system (GPS), which was installed to identify the construction distance, was also calibrated. The IRI was calculated using the ProVAL program by matching the measured profile and GPS data, and applying the moving average method. The calculated IRI was compared to that measured using another method, and the difference was within the tolerance. CONCLUSIONS : A method to measure the roughness of the concrete pavements in real time during construction was developed in this study. Hence, the performance of concrete pavements can be improved by enhancing the roughness of the pavement considerably using the aforementioned method.
        4,600원