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        검색결과 280

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Highly safe lithium-ion batteries (LIBs) are required for large-scale applications such as electrical vehicles and energy storage systems. A highly stable cathode is essential for the development of safe LIBs. LiFePO4 is one of the most stable cathodes because of its stable structure and strong bonding between P and O. However, it has a lower energy density than lithium transition metal oxides. To investigate the high energy density of phosphate materials, vanadium phosphates were investigated. Vanadium enables multiple redox reactions as well as high redox potentials. LiVPO4O has two redox reactions (V5+/V4+/V3+) but low electrochemical activity. In this study, LiVPO4O is doped with fluorine to improve its electrochemical activity and increase its operational redox potential. With increasing fluorine content in LiVPO4O1-xFx, the local vanadium structure changed as the vanadium oxidation state changed. In addition, the operating potential increased with increasing fluorine content. Thus, it was confirmed that fluorine doping leads to a strong inductive effect and high operating voltage, which helps improve the energy density of the cathode materials.
        4,000원
        4.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 허벅다리걸기 시 유도 선수들의 무릎 관절 부상 경험이 운동학적 요인과 압력 중심 요인들에 미치는 영향을 분석하는데 있었다. 본 연구에는 허벅다리걸기를 특기로 하는 오른손잡이 남 자 대학 유도 선수 중 최근 2년 이내 무릎 관절 부상 경험이 있었던 13명(연령, 20.69.1±0.75 세; 신장, 172.85±4.81 cm; 체중, 74.92±5.51 kg; 경력, 8.92±0.95 세)과 상해 경험이 없었던 13명(연령, 21.08.1±0.76 세; 신장, 172.54±6.32 cm; 체중, 76.62±9.09 kg; 경력, 9.46±0.94 세)이 두 그룹으로 나 뉘어 피험자로 참여하였다. 두 그룹의 발목, 무릎, 힙 관절각도 변인과 압력 중심 가동범위와 속도 요인들 의 차이를 분석하였다. 그 결과, 부상 경험 그룹은 부상 경험이 없었던 그룹에 비해 허벅다리걸기 기술 발 휘 시 한발 지지 구간 중 E3에서의 무릎 관절 굴곡 각도와 E4에서의 힙 관절 신전 각도에서 작은 수치를 나타내었다. 더불어 부상 경험 그룹은 부상 경험이 없었던 그룹에 비해 한발 지지 구간에서 압력 중심 가동 범위와 전방 이동 속도 요인에서도 낮은 수치를 나타내었다.
        4,000원
        5.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Paddy fields provide important habitats for biodiversity conservation within the agricultural ecosystem. Their importance is gradually increasing as their ecological value is better understood. Benthic macroinvertebrates dominate paddy fields. They play an essential role in maintaining the biodiversity of paddy ecosystems. This study aimed to analyze characteristics of benthic macroinvertebrate communities and main environmental factors affecting the distribution of golden apple snails (Pomacea canaliculata). Results showed that the diversity index (H ′) of the benthic macroinvertebrate community was the highest at the Sangju site (St. 12) but the lowest at the Sancheong site (St. 18). Total Dissolved Solids (TDS), salinity, and Electrical Conductivity (EC) values were the highest in Gimhae and Yeongam based on Canonical Correspondence Analysis (CCA). Numbers of P. canaliculata (m-2) were relatively low in Gunsan and Iksan where water temperatures were high. Therefore, changes in geographical characteristics and environmental factors might affect the distribution of P. canaliculata and characteristics of benthic macroinvertebrate communities. Results of this study can be used as primary data for biodiversity conservation and ecosystem service evaluation in agroecosystems.
        4,300원
        7.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper investigates the effects of aspect ratio and volume fraction of hooked-end normal-strength steel fibers on the compressive and flexural properties of high-strength concrete with specified compressive strength of 60 MPa. Three types of hooked-end steel fibers with aspect ratios of 64, 67 and 80 were considered and three volume fractions of 0.25%, 0.50% and 0.75% for each steel fiber were respectively added into each high-strength concrete mixture. The test results indicated that the addition of normal-strength steel fibers is effective to improve compressive and flexural properties of high-strength concrete but fiber aspect ratio had little effect on the modulus of elasticity and compressive strength. As steel fiber content and aspect ratio increased, flexural beahvior of notched high-strength concrete beams was effectively improved.
        4,000원
        8.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        나노복합재료는 다기능성과 고성능을 가지는 혁신적인 복합재료이다. 나노 스케일 필러의 혼입함으로써 복합재료의 전기적, 역학 적 및 열적 특성이 크게 향상될 수 있기 때문에 나노 스케일 필러를 이용한 나노복합재료의 특성화에 관한 다양한 연구가 광범위하게 수행되어 왔다. 특히, 탄소계 나노 필러(탄소나노튜브, 카본블랙, 그래핀 나노판 등)를 활용하여 전기/역학적 특성을 향상시킨 나노복 합소재 개발에 관한 연구들이 복합재료 분야에서 큰 관심을 받고있다. 본 논문은 실제 응용에 필수적인 나노복합재료의 전기/역학적 특성을 문헌조사를 통해 고찰하는 것을 목표로 한다. 또한, 나노복합재료의 전기/역학적 특성 예측을 위한 최신 멀티스케일 모델링 연 구들에 대해서 검토하고, 멀티스케일 모델링에 대한 과제와 향후 발전 가능성에 대해서 논의한다.
        4,000원
        10.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sarcoma is rare malignant tumors that develop from mesenchymal cells. Metastasis to the oral cavity is a rare occurrence. Undifferentiated Pleomorphic sarcoma(UPS), formerly known as Malignant fibrous histiocytoma(MFH), is rare spindle cell neoplasm that can have poorly prognosis with metastasis and local recurrence. This report describes a case of a 77-year-old man who was diagnosed with Undifferentiated Pleomorphic Sarcoma of the chest wall and underwent adjuvant radiation therapy after surgical resection. Although there was success of wide excision, two years later, he presented with metastasis to the several organs including tongue. We retrospectively analyzed results of Next Generation Sequencing(NGS), and we figured out RB1 gene mutation. Until now targeted therapy of RB1 gene mutation is not established. Surgeon needs to consider metastatic tumors through identifying patients’ chief complaints and past medical & dental history. We need to research through NGS, and take a step closer to find targeted therapy for tumors.
        4,000원
        11.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ecological occupation in irrigation ponds is a well-acknowledged fact that is essential for biodiversity conservation in agricultural ecosystems. However, there are few studies on the ecological functions and relationship between a paddy field and irrigation using macroinvertebrates in an environmentally friendly paddy field. The objective of this study is to identify the community and distribution characteristics of macroinvertebrates in an agricultural paddy field and irrigation pond ecosystems, and to provide basic data on the ecological function of an environmentally friendly paddy field. Macroinvertebrate sampling was conducted from May to September in an agricultural paddy field and irrigation pond in an environment-friendly paddy field in Boryeong city. We conducted a study to identify the distribution characteristics using macroinvertebrate species analysis, such as Functional Feeding Groups (FFGs), Habitat Oriented Groups (HOGs), rarefaction curve, and a two-way dendrogram. A total of 37 species of macroinvertebrates in 28 families, 13 orders were collected study during the period of the investigation. Dominant taxa of macroinvertebrates included Coleoptera, Hemiptera, and Odonata. In terms of FFGs, predators and gathering collectors accounted for approximately 70%, in relation to HOGs, and climbers and swimmers occupied more than 50% from both the paddy field and irrigation pond. With respect to the rarefaction curve, the irrigation pond (July) was high as E (S, 141)=18 species, while the paddy field (May) was comparatively low as E (S, 141)=9 species. In conclusion, our results revealed that macroinvertebrates, such as Notonecta triguttata, Peltodytes intermedius, Appasus major, Laccotrephes japonensis, Appasus japonicus, Sigara substriata, Enochrus simulans, and Sternolophus rufipes, were used as a habitat and spawning ground in both paddy field and irrigation pond. The irrigation pond appears to be a very important spawning ground for macroinvertebrates.
        4,000원
        12.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        콘크리트 경화 시 발생하는 수분증발로 인한 건조수축은 콘크리트의 균열을 발생시킨다. 콘크리트에 발생하는 균열 은 콘크리트의 내구성을 저하하여 안정성과 사용성에 문제를 발생시킨다. 이러한 문제점을 보안하기 위해 콘크리트에 강섬유를 혼입하여 건조수축으로 인한 균열을 방지하는 강섬유 보강 콘크리트 (SFRC)에 관한 연구가 진행되고 있다. 강섬유는 콘크리트 의 균열단면에서 가교역할, 부착작용을 통해 건조수축으로 인한 균열발생을 억제하고 균열 폭을 감소시키는 효과가 있다. 본 논 문에서는 강섬유의 인장강도에 따른 강섬유 보강 콘크리트의 건조수축 제어성능을 평가하였다. 자유건조수축 실험과 구속건조 수축 실험을 진행하였으며 실험 결과를 콘크리트의 인장응력으로 변환하여 콘크리트 직접인장실험 결과와 비교하였다. 강섬유 의 자유건조수축 저감 효과는 미미하지만 강섬유의 인장강도가 증가할수록 구속건조수축으로 인한 균열제어에 효과적임을 확인 하였다. 또한 강섬유의 인장강도가 증가할수록 콘크리트의 인장응력이 증가함을 확인하였다.
        4,000원
        15.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, air scouring cleaning was selected and applied among 5 small blocks (S1~S5) in domestic S cities to analyze the cleaning effect of particles causing discoloration. In order to identify the cleaning effect, 10 locations were selected as water quality investigation point, such as the stagnant or water mains ends. Removal of solids, variation of particle components, weight and concentration were analyzed. And the level of the cleanness of the surface inside water mains using endoscope was investigated. As a result of analysis, the solids discharged after cleaning were mainly sand and gravel, pieces related to pipe materials, and corrosion products. As a result of analyzing the concentrated particles of the filter before and after cleaning, it was found that the change in discoloration on the filter was large. In addition, as a result of comparing the weight and the concentration of the particles, it was found that the particles causing discoloration were significantly removed after cleaning. From the results of the endoscopy, it was confirmed that most of the precipitated and accumulated dark yellow discoloration matters inside water mains were removed through cleaning. Therefore, it seems that the particles causing discoloration in water decreased after cleaning. Therefore, it is expected that, if properly cleaning was applied, matters that cause discoloration can be removed from the water mains, and customer's complaints can also be reduced through water quality improvement.
        4,000원
        17.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 유도 허벅다리걸기 기술 발휘 시 발목 관절의 테이핑 처치가 하지 관절과 압 력중심(COP, center of pressure)에 미치는 영향을 분석하는데 있었다. 대학 유도 선수 20명(연령, 20.9±0.8세; 신장, 168.6±7.4cm; 체중, 73.5±11.6kg; 신체질량지수, 25.7±2.6kg/m2)이 참여하였으며, 발목 관절 테이핑 처치 전과 후의 2가지 조건에서 허벅다리걸기 기술 발휘 시 지지다리 관절의 각도와 압 력중심 요인을 분석하여 다음의 결과를 도출하였다. E2(t=2.411, p=.027) E4(t=2.388, p=.029)시점에서 발목 관절의 각도는 테이핑 처지 전에 비해 처치 후 발목의 각도가 통계적으로 적은 수치를 나타내었고, E2(t=-2.343, p=.032) E3(t=-4.531, p=.000)시점에서 힙 관절의 각도는 통계적으로 크게 나타났다. 그리 고 발목 관절 테이핑 처치 후 좌·우의 COP 이동은 상대를 메치는 P3 국면에서 통계적으로 크게 나타났으 며(t=2.670, p=.016), 전·후의 COP 이동은 상대의 무게 중심을 기울이는 P1 국면에서 통계적으로 적은 수 치를 나타내었다(t=2.846, p=.011). 그러므로 허벅다리걸기를 특기로 사용하는 유도 선수들은 발목 관절 테이핑으로 인해 발생하는 지지관절의 운동 기능과 COP의 이동범위를 고려하여 사용하는 것에 대하여 제 안하고자 한다.
        4,000원
        19.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Proteasome inhibitors can improve the efficiency of cancer treatments by inhibiting nuclear factor κB(NF-κB) activation in cancer cells. Lentils are a type of beans of which consumption of such beans is increasing. The purpose of this study was to investigate the effects of lentils extract (LE) on the proteasomal activities, NF-κB activation, and cell cycle in HepG2 human liver cancer cells. LE treatments inhibited proteasomal activities at concentrations of 10, 50, and 100 μg/mL respectively, and repressed NF-κB activation at concentrations of 1, 10, and 100 μg/mL respectively, in HepG2 cells. LE treatments at concentrations of 1, 10, and 100 μg/mL respectively, increased sub-G1 cell population in HepG2 cells, which may be the result of apoptosis. The results suggest that LE inhibited NF-κB activation partially with its proteasome inhibitory activities, and the increase of sub-G1 cell population was induced partially, by inhibition of NF-κB activation in HepG2 cells.
        4,000원
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