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        검색결과 3,759

        501.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 다공성 보와 논로컬 매개변수 사이의 관계에 대한 유한요소해석을 수행한다. 논로컬 매개변수는 다공성 보의 결함을 표현하는 변수들로 정의하여, 하중조건 및 경계조건에 대한 수치모사를 통해 계산한다. 다공성 보와는 반대 개념의 결함을 가지는 보에 대한 해석도 수행하였다. 이러한 보들의 거동은 논로컬 매개변수의 항으로 표현하였으며, 이 매개변수는 구멍의 지름의 제곱 그리고 원기둥 지름의 세제곱에 비례하는 것을 확인하였다. 특히 작은 원기둥을 가지는 보에 축하중을 가하는 경우, 예상과는 다르게 3 차원 유한요소 해석 결과와 2차원 평면응력 해석 결과는 다름을 알 수 있었다.
        4,000원
        502.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 지리산국립공원 세석평전 일대 설치류에 의한 수목피해실태를 조사하고, 피해목 주변에서 확인된 설치류 배설물 분석을 통하여 가해 의심종을 확인하고자 하였다. 피해목 조사는 대상지 내 탐방로를 중심으로 접근과 육안관찰이 가능한 지역에 한해 수종에 관계없이 실시하였으며, 가해 의심종 확인을 위해 피해목 주변 설치류 배설물에 대한 미토콘드리아 DNA Cyt-b의 염기서열 분석을 수행하였다. 설치류에 의한 피해목은 총 52개체로 모두 구상나무로 확인되었으며, 구상나무가 높은 밀도로 군락을 형성하고 있는 곳에서 집중되어 있었다. 수고 1.5m 이상 구상나무가 40개체가 조사되었으며, 이중 39개체는 피해 입은 가지부만 고사한 것으로 나타나 수목 전체에 영향을 미치지 않았다. 수고 1.5m 미만 구상나무는 12개체가 조사되었으며, 이중 7개체는 완전히 고사한 것으로 나타나, 상대적으로 어린 구상나무가 피해를 입을 경우 고사 가능성이 높은 것으로 나타났다. 배설물의 유전자 염기서열 분석결과 구상나무를 가해한 종은 대륙밭쥐로 확인되었다.
        4,000원
        503.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 북한의 지리적 표시제 인식과 관련법 및 현황을 분석하 였다. 북한은 이미 세계지적재산권기구(WIPO)에 개성고려인삼, 백두산 가시오갈피, 고려신덕산샘물, 강서약수, 백두산들쭉술 그리고 평양랭면 이상의 6개 GI 상품을 등록하였다. 향후 북한의 시장 개방 시, 전통상품 및 농업의 보호를 위해 GI의 제도 정비와 관련 상품의 등록 확대가 필요 하다. 개혁·개방 초기 북한의 1차 산업 중 농업분야에 대한 지원이 집중 될 시기 생산성과 효율성, 농업경쟁력을 제고할 수 있는 중요한 제도가 GI라 할 수 있으며, 동 제도의 활성화를 통해 전통적 노하우와 농업생산 품 생산과정의 질적 보호가 유지될 수 있다.
        6,400원
        504.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2016년에 쌍별귀뚜라미는 식품의약품안전처 식품공전에 등록된 식품원료로 가장 큰 장점은 월동 없이 연중 대량 사육이 가능하다는 것과 60% 이상의 단백질 함량이다. 본 연구에서는 사육공간, 인건비 등의 문제로 인하여 귀뚜라미 사육이 불가능할 때를 대비하여 저장조건을 설정하 였으며, 산란율이 높은 산란처 선발과 알의 동종포식률을 조사하였다. 산란은 상토 산란처에서 가장 선호도가 높았으며(p < 0.05), 알의 동종포식 률을 보았을 때 10 L 당 종령 약충 62마리 이하, 1일 동안 산란을 받는 것이 가장 적합한 것으로 판단되었다(p < 0.05). 알의 저온 저장을 하였을 때는 28℃에서 10일간 보관 후 16℃에서 10일간 저온 저장했을 때 부화율이 가장 높았고, 저장을 하지 않았을 때와 비교하였을 때 12~14일 부 화를 연장할 수 있었다(p < 0.05). 쌍별귀뚜라미의 산란처, 산란 방법 및 알 저장조건을 설정함으로써 효율적인 생산방법을 제시하였다.
        4,000원
        505.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        한반도 풍력자원의 연간 변동성을 파악하기 위하여 한국 기상청의 아시아권 및 한반도권 지역예보모델 해석자료를 초기 기 상장으로 연계한 UM-WRF 수치기상예측 모델로 2010년부터 2018년까지의 풍력자원지도를 생산하였다. 풍력자원지도의 풍력발전량 예측정확도를 확인하기 위해 가동 중인 모든 풍력터빈의 발전량을 예측하고 전력거래소의 월간 발전량 기록과 비교검증하였으며, R2=0.83의 높은 일치도를 확인하였다. 한반도 육상 및 해상의 연간 풍속 변동성은 각각 COV = 11.4%와 4.3%로 파악되었으며, 특히 풍력자원이 우수한 고산지대의 변동성이 큰 것으로 나타났다. 풍력보급의 증가에 따라서 전력계통에 미치는 변동성의 우려가 커지고 있기 때문에 지속적으로 장기간의 고해상도 풍력자원지도를 생산하고 발전량 검증을 거쳐 발전량 변동성을 정밀하고도 정량적으로 파 악할 필요가 있다.
        4,000원
        506.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Purpose: This is a group pretest-posttest design study that aim to examine the effect of smart problem-based learning (PBL) teaching method using flipped learning to meta-cognition, academic self-efficacy, and satisfaction level of nursing students. Method: The subjects were 76 students who took basic nursing practice, which is a major subject, from August 29 to December 13, 2018. A questionnaire was used to measure meta-cognition in web-based self-directed learning. The self-efficacy measurement used a scale consisting of self-regulating efficacy, task difficulty preference, and confidence. The measurement of practical satisfaction is a 5-point Likert scale that employs a questionnaire. Flipped learning uploaded a 10-minute lecture video, and the subjects learned through PC or smartphone. PBL teaching was developed in two modules: gavage and indwelling urinary tract. Results: Result showed a significant improvement of meta-cognition after education than before education (t=3.21, p=.043). Academic self-efficacy was not significantly changed before and after education. Practice satisfaction was significantly improved after training than before training (t=-2.19, p=.032). Conclusion: The smart PBL teaching method using flipped learning is an effective teaching and learning strategy for nursing majors. Nursing students with high meta-cognition will be able to perform well in their learning outcomes; therefore, this positive performance experience will enhance self-efficacy.
        4,200원
        507.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research focuses on the life and works of architect Yi Hunwoo, who was active in early 20th century. Yi has been previously mentioned in a few research documents, but not as a main subject of interest. Thanks to digitalized historic databases, the authors of this research were able to access more information about Yi. It was discovered that he was born in Korea in the late 19th century and then attended the Nagoya Higher Technical School in Japan. After repatriation, he participated in a few public projects in Korea as an in-house architect at the Governor-General’s office, then started his own practice and produced his individual projects. He also contributed articles on innovations in residential design to newspapers. Chronologically, his activities as an architect preceeded those of Park Gilyong, who has been conventionally regarded as the first Korean modern architect so far. This research would like to establish Yi Hunwoo as a historic figure whose professional career spanned the earlier stage of the Korean modern architecture, based on the records of his life and professional activities. The authors do not wish to present the architectural analysis nor evaluation of his works, which will be subject to future researches.
        4,600원
        508.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study deals with a pressure relief joint, which is one of primary preventive methods of blow-up in concrete pavement. The purpose of the study is to estimate the joint sealant protrusion of pressure relief joint filler types according to horizontal displacement of concrete pavement by applying a variety of joint sealants and joint fillers. And test method for resistance of concrete to chloride ion penetration and test method for resistance of concrete to rapid freezing and thawing were conducted to analyze the improvement of concrete durability according to the primer types on concrete surface of stress relief joint. METHODS : Joint fillers of pressure relief joint were categorized into four different types, which are was styrofoam+backer+sealant(type 1), styrofoam+sealant(type 2), foaming styrofoam+sealant(type 3), and preformed joint+sealant(type 4). By varying the depth (10, 20, 30, 50 mm) from the top of the test specimens to the sealant’s surface, the test factors were evaluated for a total of 16 variables. When the specimen’s joint spacing decreased from 70mm to 10mm, the load was stopped. And the displacement of the center of the joint protrusion was measured. The test was terminated when the specimen joint spacing was reduced to 60 mm. The horizontal displacement at the time when the joint protrudes over the specimen surface is recorded and analyzed as the critical threshold displacement. RESULTS : According to the test results according to the type of joint filling material, it was found that there was a difference in the protrusion of the horizontal compression displacement according to the joint filling type. Under the current installation standard of 20mm, the preformed seal joint member showed the best crimping characteristics by securing the safety against protrusion until the horizontal displacement of 50mm occurred. CONCLUSIONS : The most common failures in pressure relief joints are those related to joint sealants, which can be minimized by changing the current joint type, installation depth, etc. to suppress them.
        4,000원
        511.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, deep learning that is the most popular and effective class of machine learning algorithms is widely applied to various industrial areas. A number of research on various topics about structural engineering was performed by using artificial neural networks, such as structural design optimization, vibration control and system identification etc. When nonlinear semi-active structural control devices are applied to building structure, a lot of computational effort is required to predict dynamic structural responses of finite element method (FEM) model for development of control algorithm. To solve this problem, an artificial neural network model was developed in this study. Among various deep learning algorithms, a recurrent neural network (RNN) was used to make the time history response prediction model. An RNN can retain state from one iteration to the next by using its own output as input for the next step. An eleven-story building structure with semi-active tuned mass damper (TMD) was used as an example structure. The semi-active TMD was composed of magnetorheological damper. Five historical earthquakes and five artificial ground motions were used as ground excitations for training of an RNN model. Another artificial ground motion that was not used for training was used for verification of the developed RNN model. Parametric studies on various hyper-parameters including number of hidden layers, sequence length, number of LSTM cells, etc. After appropriate training iteration of the RNN model with proper hyper-parameters, the RNN model for prediction of seismic responses of the building structure with semi-active TMD was developed. The developed RNN model can effectively provide very accurate seismic responses compared to the FEM model.
        4,000원
        512.
        2020.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Cerium oxide (ceria, CeO2) is one of the most wide-spread oxide supporting materials for the precious metal nanoparticle class of heterogeneous catalysts. Because ceria can store and release oxygen ions, it is an essential catalytic component for various oxidation reactions such as CO oxidation (2CO + O2 2CO2). Moreover, reduced ceria is known to be reactive for water activation, which is a critical step for activation of water-gas shift reaction (CO + H2O → H2 + CO2). Here, we apply van der Waals-corrected density functional theory (DFT) calculations combined with U correction to study the mechanism of water chemisorption on CeO2(111) surfaces. A stoichiometric CeO2(111) and a defected CeO2(111) surface showed different water adsorption chemistry, suggesting that defected CeO2 surfaces with oxygen vacancies are responsible for water binding and activation. An appropriate level of water-ceria chemisorption energy is deduced by vdW-corrected non-local correlation coupled with the optB86b exchange functional, whereas the conventional PBE functional describes weaker water-ceria interactions, which are insufficient to stabilize (chemisorb) water on the ceria surfaces.
        4,000원
        515.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study is to investigate the cause of the malfunction of the ground tracked combat vehicle rotating roller and set future direction of improvement. The integrity of the initially used plate and rotating roller was evaluated. As evaluation methods, mechanical property test, radiographic test and size checking test were performed. PA66, PA12, PET, and POM were selected among polymer materials and tested for water absorption rates. Through mechanical property test and radiographic test, the materials used initially were identified to be sound. In the evaluation of the selected four polymer materials, it was confirmed that the PET was excellent in the mechanical properties and the water absorption rate. PET is excellent in mechanical properties and water absorption.
        4,000원
        516.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An underwater cable guide device which is using the caterpillar movement to move smoothly along the slippery and curved surface of the cast iron pipe was developed. We performed structural analysis with maximum stress and structural safety for the designed guide device. As a result of the structural analysis, the maximum stress occurred between the connecting link and the pin, and it was confirmed that it was structurally safe by satisfying the safety factor of 2.5 or more. In addition, we performed modal analysis to find out the possibility of resonance between the guide device and motor for driving the Caterpillar. The natural frequency of guide device was calculated to be higher than the frequency of motor ,so no resonance was found. We tested performance of the developed guide device, the target performance was satisfied in the watertight test, salt spray test, vibration test, and durability test.
        4,000원
        517.
        2020.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Amorphous In-Ga-Zn-O (a-IGZO) thin film transistors, because of their relatively low mobility, have limits in attempts to fulfill high-end specifications for display backplanes. In-Zn-O (IZO) is a promising semiconductor material for high mobility device applications with excellent transparency to visible light region and low temperature process capability. In this paper, the effects of working pressure on the physical and electrical properties of IZO films and thin film transistors are investigated. The working pressure is modulated from 2 mTorr to 5 mTorr, whereas the other process conditions are fixed. As the working pressure increases, the extracted optical band gap of IZO films gradually decreases. Absorption coefficient spectra indicate that subgap states increase at high working pressure. Furthermore, IZO film fabricated at low working pressure shows smoother surface morphology. As a result, IZO thin film transistors with optimum conditions exhibit excellent switching characteristics with high mobility (≥ 30cm2/Vs) and large on/off ratio.
        4,000원
        518.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the physicochemical properties of brown rice by cultivar to select cultivar suitable for making brown rice porridge. The moisture content of the brown rice ranged from 8.79~11.78% with the highest varieties being ‘Geonyangmi’. The crude ash and crude lipid content ranged from 1.02~1.65% and 1.65~3.26%, while the rest were similar except for ‘Daebo’. Crude protein also had the lowest ‘Daebo’ and generally glutinous rice showed higher crude protein content than common rice. The hardness showed that ‘Seolgaeng’ and ‘Keunnun’ were the lowest, and ‘Haiami’ was the highest. In the RVA analysis, the setback was in the range -80.61~22.44 and was low in the order of ‘Wolbaek’, ‘Baekjinju'', and ‘Dongjinchal’. As a result of water binding capacity (WBC) measurement, ‘Sindongjin’, ‘Geonyang’ and ‘Samkwang’, were high in common rice, and ‘Dongjinchal’ and ‘Hwaseonchal’ were high in glutinous rice. Generally, solubility and swelling power in common rice was found to be lower than in glutinous rice. As a result, ‘Samkwang’ is considered suitable for brown rice porridge production because of high WBC, breakdown, and low setback.
        4,000원
        519.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To increase the functional material content of soybean, a repetitive steaming and drying process was used. We investigated the changes in the total polyphenol content, the antioxidant activity, and the angiotensin-Ⅰ converting enzyme (ACE) inhibition in soybean following nine rounds of steaming and drying. Soybean was steamed 9 times for 2 h and then dried 9 times from 55℃ to 73℃ for 3 h. The total polyphenol content in the soybean reached a maximum value of 60.47 mg GAE eq./100 g at 73℃ while the total polyphenol content in the raw soybean reached 25.17 mg GAE eq./100 g. In the raw soybean samples, the DPPH radical scavenging activity (5 mg/mL) was 8.04% but it increased by 43.29% after drying 9 times to 73℃. ABTS radical scavenging activity also improved following 9 rounds of steaming and drying. ACE inhibitory activity of the soybean dried 9 times at 73℃ was 58.94% at 10 mg/mL. These results showed that steaming and drying soybean 9 times enhanced the antioxidant activity and the ACE inhibitory activity of soybean. Therefore, more research on the biological and anti-hypertensive activity of soybean using this steaming and drying method is necessary.
        4,000원
        520.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate antioxidant characteristics and anti-adipogenic effects of colored rice and brown rice extracts in 3T3-L1 adipocyte depending on cultivar (Josaengheugchal, Heugjinmi, Hongjinju, Geongganghongmi, Seolgaeng, Milyang 320, Sindongjin, Baegjinju). Colored rice and brown rice was extracted with 100% ethanol, followed by the analysis of polyphenol, flavonoid, anthocyanin, antioxidant, and anti-adipogenic activity. Total polyphenol and flavonoid content ranged from 6.86~314.08 mg GAE/g and 1.47~56.88 mg CE/g the highest total polyphenol and flavonoid content was observed in Heugjinmi cultivar. Anthocyanin composition was analyzed by HPLC, cyanidin-3-gluoside and peonidin-3-glucoside was found in black rice including Josaengheugchal and Heugjinmi. Also, the ABTS and DPPH radical scavenging activity of colored rice cultivars was higher than that of brown rice cultivars, the highest ABTS radical scavenging activity also was observed in Heugjinmi (128.20 mg TE/g). The anti-adipogenic effects of colored rice and brown rice extracts on differentiation of 3T3-L1 preadipocytes evaluated that extracts of Heugjinmi cultivar significantly reduced intracellular lipid accumulation. These results provide valuable information for the use of Korean colored rice cultivar as a functional food materials relative to anti-obesity.
        4,000원