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        검색결과 19

        1.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study investigated the effects of exposure frequency, depth of processing, and activity repetition types on vocabulary learning. In total, 78 South Korean fifth-grade students were divided into four conditions. Students in each condition were asked to read a passage with four of the eight target words (exposure: four times) and the other four words (exposure: once) for three days, and to perform the vocabulary activities assigned to each condition. According to the results, exposure frequency and activity repetition type had significant effects on vocabulary learning. Activity repetition type also had a significant interaction effect with exposure frequency and depth of processing. Notably, presenting a word 12 times (4x3) in reading intervals had a more positive impact on vocabulary learning than presenting it three times (1x3), particularly when different vocabulary activities were repeated. Meanwhile, when the same activity was repeated, an activity with a higher depth of processing was more effective for vocabulary learning.
        7,000원
        2.
        2023.11 구독 인증기관·개인회원 무료
        The compacted bentonite buffer is a key component of the engineered barrier system in deep geological repositories for high-level radioactive waste disposal. Groundwater infiltration into the deep geological repository leads to the saturation of the bentonite buffer. Bentonite saturation results in bentonite swelling, gelation and intrusion into the nearby rock discontinuities within the excavation damaged zone of the adjacent rock mass. Groundwater flow can result in the erosion and transport of bentonite colloids, resulting in bentonite mass loss which can negatively impact the long-term integrity and safety of the overall engineered barrier system. The hydro -mechanicalchemical interactions between the buffer, surrounding host rock and groundwater influence the erosion characteristics of the bentonite buffer. Hence, assessing the critical hydro-mechanicalchemical factors that negatively affect bentonite erosion is crucial for the safety design of the deep geological repository. In this study, the effects of initial bentonite density, aperture, discontinuity angle and groundwater chemistry on the erosion characteristics of Bentonil WRK are investigated via bentonite extrusion and artificial fracture experiments. Both experiments examine bentonite swelling and intrusion into simulated rock discontinuities; cylindrical holes for bentonite extrusion experiments and plane surfaces for artificial fracture experiments. Compacted bentonite blocks and bentonite pellets are manufactured using a compaction press and granulation compactor respectively and installed in the transparent extrusion cells and artificial fracture cells. The reference test condition is set to be 1.6 g/cm3 dry density and saturation using distilled water. After distilled water or solution injection, the axial and radial expansion of the bentonite specimens into the simulated rock discontinuities are monitored for one month under free swelling conditions with no groundwater flow. Subsequent flow tests are conducted using the artificial fracture cell to determine the critical flow rate for bentonite erosion. The intrusion and erosion characteristics are modelled using a modified hydro-mechanicalchemical coupled dynamic bentonite diffusion model and a fluid-based hydro-mechanical penetration model.
        4.
        2022.10 구독 인증기관·개인회원 무료
        Compacted bentonite buffer materials are a key component of the engineered barrier system for high-level radioactive waste disposal. The bentonite buffer is saturated via groundwater flow through the excavation damaged zone in the adjacent rock mass. Bentonite saturation results in bentonite swelling, gelation and intrusion into the nearby rock discontinuities. Groundwater flow can cause bentonite erosion and transportation of bentonite colloids. This bentonite mass loss can negatively impact the long-term integrity of the engineered barrier system. Hence, it is necessary to understand the effects of erosion on the properties of the bentonite buffer. In this study, a series of artificial fracture erosion experiments are conducted to investigate the erosion characteristics of compacted Ca-bentonite buffer materials for different initial dry density conditions. Compacted bentonite blocks and bentonite pellets were manufactured using the cold isostatic pressing technique and granulation compactor respectively. The specimens were placed in a custommade transparent artificial fracture cell and the bentonite intrusion characteristics were monitored for two months under free swelling conditions with no groundwater flow. The radial expansion of the bentonite specimens within the artificial fracture was measured using a digital camera. In addition, the swelling pressure, displacement, and saturation were determined using a load cell-piston system, LVDT, and electrical resistivity electrodes respectively. A hydro-mechanical-chemical coupled dynamic bentonite diffusion model was applied to model the bentonite erosion characteristics using COMSOL Multiphysics.
        5.
        2022.05 구독 인증기관·개인회원 무료
        Low to intermediate radioactive waste disposal concrete structures are subjected to coupled hydromechanical conditions and the identification of structural damage is crucial to ensure safe long-term disposal. Different damage models for concrete and the surrounding rock can affect the damage characteristics of radioactive waste disposal structures. In this study, the effects of different rock damage models are applied to the hydro-mechanical-damage coupled structural analysis of the Wolseong Low and Intermediate Level Radioactive Waste Disposal Center silo. A two-dimensional model of the disposal silo was modeled using the finite element analysis software COMSOL and the Mazars’ damage model was applied to the silo concrete. The Mazars’ model parameters were obtained from uniaxial compression and tensile tests on cylindrical concrete specimens after 28 days of water curing and further 32 days of wet curing at 75°C). The COMSOL embedded Richards equation module was used to simulate hydraulic analysis. Structural loading due to waste disposal was applied at the bottom of the silo structure and the damage evolution characteristics were investigated. The non-linear mechanical rock behavior obtained from laboratory tests (Hoek-Brown criterion, resonant column test, Mazar’s damage model) and field tests (Goodman Jack) were input to assess the effects of different rock damage models. The results highlight the importance of structural damage consideration when assessing the long-term stability and safety of underground radioactive waste disposal structures under coupled hydro-mechanical conditions.
        10.
        2015.06 구독 인증기관 무료, 개인회원 유료
        Curcumin (diferuloylmethane), a constituent of turmeric powder derived from the rhizome of Curcuma longa, has been shown to inhibit the growth of various types of cancer cells by regulating cell proliferation and apoptosis. However, a need exists to design more effective analogs because of curcumin's poor intestinal absorption. EF-24 (diphenyl difluoroketone), the monoketone analog of curcumin, has shown good efficacy in anticancer screens. However, the effects of curcumin and EF-24 on salivary gland epidermoid carcinoma cells are not clearly established. The main goal of this study was to investigate the effects of curcumin and EF-24 on cell growth and induction of apoptosis in human salivary gland epidermoid carcinoma cells. Our studies showed that curcumin and EF-24 inhibited the growth of HTB-41 cells in a dose- and time-dependent manner, and the potency of EF-24 was > 34-fold that of curcumin. Treatment with curcumin or EF-24 resulted in nuclear condensation and fragmentation in HTB-41 cells, whereas the control HTB-41 cell nuclei retained their normal regular and oval shape. Curcumin and EF-24 promoted proteolytic cleavages of procaspase-3/-7/-9, resulting in an increase in the amount of cleaved caspase-3/-7/-9 in the HTB-41 cells. Caspase-3 and -7 activities were detected in viable HTB-41 cells treated with curcumin or EF-24. These results suggest that the curcumin and EF-24 inhibit cell proliferation and induce apoptosis in HTB-41 human salivary gland epidermoid carcinoma cells, and that they may have potential properties as an anti-cancer drug therapy.
        4,000원
        11.
        2005.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to define more precisely the anatomy of the thumb flexor pulley system and to determine the relative contribution of each of the pulleys to the biomechanics of thumb motion at the metacarpophalangeal (MP) and interphalangeal (IP) joints. For this, 22 hands from 11 cadavers were used and randomly assigned to two groups. In the first group, the first annular (A1) pulley was cut first followed by the variable annular (Av) pulley and then the oblique pulley. In the second group, the oblique pulley was cut first followed by the, pulley and then the Av pulley. In 7 of 22 hands, it was a transverse structure parallel to the, pulley with a gap between the A1 and Av pulleys, referred to here as type I. In 9 hands, the A1 and Av pulleys were connected without any gap (type II). In 6 hands, the space between the A1 and Av pulleys were triangular in shape with fibers of the Av pulley converging toward the radial side (type III). In biomechanical study of both first and second experiments, there was no significant difference in MCP joint flexion between the all intact, A1 section, A1/Av section, A2 intact (A1/Av/oblique section), and no pulley configuration (p>.05). In occurring displacements less than 10 mm, there was no significant difference in IP joint flexion (p>.05). However, there was a significant decrease in IP joint flexion occurred in both 15 mm and 20 mm excursion (p<.05), when the oblique pulley was resected additionally after cutting the A1 and Av pulleys in first experiment, and when the A1 pulley was resected additionally after cutting the oblique pulley. According to the results, the injury of only the oblique pulley does not decrease thumb motion significantly. The oblique pulley injury with both the A1 and Av pulleys laceration decreased thumb motion significantly. The additional laceration of the A2 pulley does not decrease thumb motion.
        4,000원
        16.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근 국내에서는 국내 여건을 고려한 설계법을 개발함과 동시에 이미 공용중에 있는 도로 포장의 성능향상을 위한 「한국형 포장 설계법 개발과 성능개선 연구」가 진행되고 있다. 본 연구에서 개발된 「하중변환 알고리듬을 적용한 줄눈콘크리트 포장 해석 프로그램」은 이러한 연구의 세부분야인 콘크리트 포장 설계법 개발분야의 연구 결과로서 기본 프로그램 부분과 하중변환 부분으로 구분되어 구성되며, 기본 프로그램 부분에서는 판/쉘 요소, 스프링 요소 보 요소를 이용하여 줄눈 콘크리트 포장의 콘크리트 슬래브, 하부층, 다웰바를 모사한다. 하중변환 부분에서는 기존의 연속체 요소에 대한 하중변환 알고리듬을 수정/적용하여 요소망에 제약을 받지 않고 다양한 하중 조건을 해석한다. 또한 프로그램은 하중변환 알고리듬을 적용하여 해석을 수행하는 등분포 하중 이외에, 집중하중. 온도하중, 자중 등을 고려할 수 있는 특징이 있다. 개발된 프로그램의 특성을 분석하기 위한 민감도 분석 결과 하중크기 및 위치와 콘크리트 슬래브의 두께가 포장의 거동에 가장 큰 영향을 미치는 인자로 분석되었으며 이는 Westergaard 계산식, ILLISLAB과 유사한 결과이다.
        4,200원
        17.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        국내의 포장 재료와 교통 및 기후조건이 반영되는 포장설계법 개발을 위한 연구가 진행중에 있으며, 이를 위해 실제 교통량 및 기후조건이 반영되고 이에 따른 포장의 거동을 모니터링 할 수 있는 대규모의 현장시험시설로 시험도로를 건설하였다. 시험도로 아스팔트 포장구간은 15개의 다양한 두께 및 재료를 가진 단면들로 구성되어 있다. 이러한 단면들을 평가하기 위해 포장체 내에 다양한 계측기들이 매설되어 있다. 계측기 매설에 있어서 핵심 요소는 매설 위치의 정확성과 장기적인 생존율 및 내구성이다. 외국의 시험사례를 보면, 이런 정확성과 내구성은 매설 방법에 크게 영향을 받는다. 이에 본 연구에서는 2000년도부터 3년여 동안 일반적인 계측기 매설 방법인 마운드, 블록아웃. 트렌치컷에 대해 시험시공을 수행하였으며 시험시공 결과를 분석하여 시험도로에 적용하였다. 위치의 정확성, 생존의 안전성, 시공성, 재료의 균질성 측면에서 시험시공 결과를 평가한 결과 블록아웃이 가장 효율적인 방법으로 나타났다. 그러나, 표층의 경우 블록아웃에 부적절한 층두께 등의 특성을 감안하여 마운드 방법을 사용하는 것으로 결정하였다. 아스팔트 기층과 중간층의 매설에는 블록아웃을, 표층의 매설에는 마운드를 사용하는 것으로 결정했다. 2003년 9월 3일부터 11월 18일까지 2달 여에 걸쳐 총 374개의 아스팔트 포장 변형률계를 시험도로에 매설하였다. 계측값 분석 결과, 마운드의 경우 6.3%, 블록아웃은 2.5%의 계측기가 매설 전후의 계측값 변화가 일반적인 계측기 사양 범위를 초과하는 것으로 나타났다. 생존율의 경우 매설후 손실된 계측기는 2개로 99.5%의 높은 생존율을 나타났다.
        4,300원
        18.
        2018.07 KCI 등재 서비스 종료(열람 제한)
        이 연구는 입학전형별 학업성취도의 차이를 검증하고 취업희망자 특별전형의 전형요소가 학업 성취도에 미치는 영향력을 파악하기 위해 수행되었다. 이에 이 연구에서는 2016~2017학년도 대구 지역 A 특성화고 입학생을 대상으로 입학전형별(취업희망자 특별전형, 일반전형, 기타특별전형) 학업성취도의 차이를 검증하였다. 또한, 취업희망자 특별전형의 전형요소와 학업성취도간의 상관 관계를 비교·분석하고 취업희망자 특별전형의 전형요소가 학업성취도에 미치는 영향력을 분석하였다. 분석된 결과는 차기년도 입학전형에서 취업희망자 특별전형의 전형요소를 보완하거나 새롭게 개발할 때, 필요한 기초자료로 활용될 것이다. 이 연구의 결과는 다음과 같다. 첫째, 입학전형별 학업성취도에 통계적으로 유의미한 차이가 있었다. 사후분석 결과, 취업희망자 특별전형-일반전 형, 취업희망자 특별전형-기타특별전형, 일반전형-기타특별전형에서 모두 유의미한 차이가 나타 났다. 게다가 취업희망자 특별전형으로 선발된 학생들의 학업성취도가 일반전형과 기타특별전형으로 선발된 학생들에 비해 높게 나타났다. 둘째, 취업희망자 특별전형의 전형요소와 학업성취도의 상관관계는 입학년도에 따라 다르게 나타났다. 2016학년도 입학생의 학업성취도는 출결성적과 직업기초능력평가에서 낮은 상관관계를 보였으며, 교과성적과는 다소 높은 상관관계를 나타냈다. 반면, 2017학년도 입학생의 학업성취도는 교과성적과는 낮은 상관관계를 보였으며, 직업기초능력 평가와는 다소 높은 상관관계를 나타냈다. 셋째, 취업희망자 특별전형의 전형요소가 학업성취도에 영향을 미쳤다. 2016~2017학년도 취업희망자 특별전형의 전형요소들은 학업성취도에 대해 각각 26.4%, 22.3%의 설명력을 보였다. 전형요소들이 학업성취도에 미치는 영향력을 비교해 보니, 2016 학년도에는 교과성적(β =.338)이 제일 크고, 그 다음으로 직업기초능력평가(β =.180), 출결성적(β =.154) 순이었다. 2017학년도에는 직업기초능력평가(β =.338)가 교과성적(β =.257) 보다 학업성취도에 미치는 영향력이 크게 나타났다.
        19.
        2016.10 서비스 종료(열람 제한)
        There are bolt contraction torque decision standards in KSB 0101 for high tension bolt( torque calculation method) and in KSB 0140 for general bolts(bolt torque decision general rule), But in using bolt torque decision general rule method, friction coefficients between bolt and to-be-bolted object will rule the calculated yielding contraction axle force and yielding contraction torque, making it hard to determine the contraction torque in the field. So in other to determine the contraction torque for general bolts in field using high tension bolt torque decision method, the torque decision method for general bolt is proposed referencing high tension bolt torque decision method. And the field torque test is planned to verify the adaptability of the proposed method in the field.