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        검색결과 1,654

        261.
        2018.04 구독 인증기관·개인회원 무료
        목 적:본 연구에서는 인체 조직밀도와 유사한 실리콘을 이용하여 인체구조상 공기와 맞닿은 굴곡진 경추부위에 적용하여 자화율 인공물을 줄이고자 하였다. 대상 및 방법:인체부위 중 굴곡이 많고 구조가 복잡하여 공기와 접촉하는 면적이 넓은 경추를 대상으로 10명(평 균연령 53.3세)을 대상으로 하였다. 실험방법은 1.5T MRI(Avanto, Siemens medical system), 16 channel head-neck coil로 화학적 이동 선택 기법인 SPIR(Spectral Presaturation with Inversion Recovery)지방소거영상을 실리콘 적용 전과 후에 동일한 조건으로 획득하였다. 정량적 분석방법은 경추 부위 중 vertebra body 와 subcutaneous fat의 신호강도(Signal intensity)와 대조도 잡음비 (Contrast to ratio)를 측정한 후 비교하였으며, 정성적 분석방법은 영상의학과 전문의 3명이 영상의 지 방소거 정도에 따라서 좋음=3, 양호=2, 나쁨=1로 평가하였다. 통계적 방법은 대응표본 T 검정을 이용하 여 통계적으로 유의한 차이가 있는지 분석하였다. 결 과:기존에 실리콘 적용 전에는 vertebra body와 subcutaneous fat의 신호강도는 386.15±65.31, 681.57±103.28로 적용 후 177.83±37.62, 332.72±75.29로 적용 전보다 상대적으로 36.13% 낮았 으며, 대조도 잡음비는 19.56±4.13, 14.82±3.64로 적용 후 35.88±9.62, 33.28±8.17로 적용 전 보다 적용 후에 높게 측정되었다, 정성적 평가는 적용 전 1.30±0.33 적용 후 3.00±0.00으로 측정되었 다. 두 기법은 모두 통계적으로 유의한 차이가 있었다.(p<0.05) 위와 같은 분석결과는 지방소거가 효과적 으로 제거가 되면 주변 조직보다 신호가 더 낮게 되므로, 신호강도는 낮게 대조도 잡음비는 높게 나타났 다. 이로 인하여 실리콘 적용 후에 지방소거가 높은 효과가 있음을 알 수 있다. 결 론:본 연구는 체적소에 영향을 주지 않으면서 근본적인 문제인 공기와 인체의 자화율 차이를 보상하는 방법 이다. 또한 추가 소프트웨어나 검사시간의 증가 등의 복잡한 과정 없이 적용할 수 있는 근본적인 개선방 안이다.
        262.
        2018.04 구독 인증기관·개인회원 무료
        목 적:일반적으로 DWI 검사의 Echo Planner Image(EPI)기법은 공기, 지방, 물 등 자화율 차이가 큰 물질에 서 종종 왜곡된 영상이 발생되는 특성이 있다. 또한 B0 field 영역의 불균일에 따라 발생 되어지는 왜곡 현상도 1.5T보다 3.0T에서 더 크다. 이러한 문제점을 해결하고 보완하기 위하여 본 연구에서는 정상인을 대상으로 3D shim Whole body DWI와 SIEMENS의 Integrated-shim (i-shim) Whole body DWI의 영상품질을 비교 평가해 보았다. 대상 및 방법:본 연구는 2017년 12월부터 2018년 1월까지 정상인 10명(평균 나이 28.7±3.62세, 체질량지수 26.3±2.74)을 대상으로 하였다. 연구에 사용된 장비는 3.0T MRI 장비(Skyra 3.0T Elfs, SIEMENS, Germany)를 사용하였으며, 20 채널 head&neck coil, 30 채널 body coil 2개, 18채널 spine coil을 사용하였다. 방법으로는 3D shim WB DWI와 i–shim WB DWI을 연속적으로 검사하였다. step당 TR/TE = 8500/ 56 msec, fOV450x450, matrix 134/134, Nex(b-value 0 =3nex, 900= 4nex), 50slice, Slice Thickness 5mm로 하였다. 영상획득시간은 pre scan을 포함하여 step당 3D shim DWI = 183sec, i-shim DWI = 227sec였다. 평가 방법으로는 재구성 된 B900 영상의 시상면 영상을 가지고 정성적 분석과 Image J의 Plot profile기능을 활용한 정량적 분석을 하였다. 결 과:시상면 영상에서 척추와 뇌척수(spinal cord) 주변부의 신호소실, 틀어짐, 영상 품질, 3가지 항목을 정성 적으로 평가한 결과 I shim DWI가 3D shim DWI보다 신호소실 평가에서 0.9점(18%)더 높게 받았으며, 틀어짐에서 1.1점(22%), 총 영상 품질에서 1.1점(22%) 높았다. 결과적으로 i-shim DWI가 3D shim DWI보다 높은 점수를 보였으며, Total image quality를 합산하여 평가한 결과 i-shim DWI가 1.03점 (20.6%)이상으로 더 좋은 점수를 받았다. 정성적 평가에서 영상의 품질이 가장 좋지 않았던 목 부위를 정량적으로 분석해 본 결과, 3D shim WB DWI의 Area signal Plot profile 은 242.74(6.67)이었고, i-shim WB DWI의 Area signal Plot profile은 250.21(5.65)로 I-shim WB DWI에서 목 부위 Area 신호 면적이 더 넓어 신호소실이 더 적은 것으로 확인됬다. 또한 영상의 background 값을 normalize하여 signal intensity를 비교한 결과 3D shim DWI이 455.80(299.81), i-shim DWI이 718.80 (376.40)으로 약 1.57배 더 신호강도가 좋았다. 결 론:i-shim DWI은 기존의 3D shim DWI보다 자화율과 두께 차이가 심한 목 부분에서 자화 불균일에 의한 인공물을 효과적으로 교정할 수 있었으며, 결과적으로 B0 fileld 불균일에 따라 발생되어지는 인공물을 줄이는데 탁월한 것으로 확인됬다. 또한 step이 인접한 각 table의 위치에서 왜곡에 따른 신호소실을 줄이고 움직임에 대한 보상이 탁월한 것으로 판단되었다.
        267.
        2018.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Nitrogen (N)-doped protein-based carbon as platinum (Pt) catalyst supports from tofu for oxygen reduction reactions are synthesized using a carbonization and reduction method. We successfully prepare 5 wt% Pt@N-doped protein-based carbon, 10 wt% Pt@N-doped protein-based carbon, and 20 wt% Pt@N-doped protein-based carbon. The morphology and structure of the samples are characterized by field emission scanning electron microscopy and transmission electron micro scopy, and crystllinities and chemical bonding are identified using X-ray diffraction and X-ray photoelectron spectroscopy. The oxygen reduction reaction are measured using a linear sweep voltammogram and cyclic voltammetry. Among the samples, 10 wt% Pt@N-doped protein-based carbon exhibits exellent electrochemical performance with a high onset potential of 0.62 V, a high E1/2 of 0.55 V, and a low ΔE1/2= 0.32 mV. Specifically, as compared to the commercial Pt/C, the 10 wt% Pt@N-doped proteinbased carbon had a similar oxygen reduction reaction perfomance and improved electrochemical stability.
        4,000원
        268.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 순수와 유사한 밀도의 세척형 구형 입자를 제작하고 순수 수조 내에서 산기량 및 입자 농도에 따른 입자의 유동 속도를 측정하였다. 세척형 구형 입자 1~3%를 MLSS 8,000 mg/L인 활성슬러지 용액에 주입하고 20 LMH 및 산기량 500 mL/min 조건에서 FR 및 SFCO 모드로 동시에 투과 실험하였다. 사용한 분리막은 유효 막면적이 90 cm2, 공칭 세공크기가 0.4 μm인 평막이다. 입자 농도가 증가할수록 TMP가 감소하였으며 FR 모드, 입자 농도 2%일 때 가장 효과적 인 것으로 확인되었다.
        4,000원
        269.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 비료를 이용한 정삼투식 해수담수화에서 가장 적합한 유도용액을 찾기 위한 연구이다. 이를 위하여 삼 투압, 용해도 및 pH를 고려하여 20종의 혼합 비료를 선정하고, 수투과선속과 질소, 인 및 칼륨의 역용질선속과 비역용질선속 을 측정하여 각 혼합비료 유도용액의 성능을 평가하였다. KCl을 함유한 혼합비료의 수투과선속이 다른 혼합비료에 비해 높게 나타났다. NO3 -를 함유한 혼합비료 유도용액의 질소 역용질선속과 비역용질선속은 NO3 -를 함유하지 않은 혼합비료 용액에 비해 상대적으로 높게 나타났다. 또한 NH4H2PO4 및 KNO3를 각각 함유한 혼합비료 유도용액의 인 및 칼륨에 대한 역용질 선속과 비역용질선속은 NH4H2PO4 및 KNO3를 함유하지 않은 혼합비료 용액에 비해 상대적으로 높게 나타났다. (NH4)2HPO4 와 KCl의 혼합비료 유도용액은 비료의 필수성분인 질소, 인 및 칼륨을 모두 포함하고 있고, 수투과선속이 클 뿐만 아니라 질소, 인 및 칼륨에 대한 역용질선속이 작아 정삼투식 해수담수화용 유도용액의 유도물질로서 가장 적합하다고 판단된다.
        4,000원
        270.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the differences of holding power according to the shape and weight distribution of concrete weight used in shellfish shell fishery were investigated through the experiments. To investigate the differences in shape, five bar-shaped concrete weights with the same length and different cross-sectional shapes were produced. The sectional shape of each weight was square, triangle, circle, small cross, and large cross (SQ, TR, CI, CR-S, CR-L). Ten rectangular parallelepiped weights with different bottom area and cross-sectional area were produced. To investigate the differences by the weight distribution, the holding power on the square model (SQ) with six 50 g weights at different positions was investigated. All the holding power was obtained by measuring the tensile force generated when the concrete weight was pulled at a constant speed on the sand. As a result, there were no differences in holding power between the ten rectangular weights. However, the experiment on weights with different cross-sectional shapes showed differences in holding power. The holding power was higher in the order of CR-L > CR-S > CI > TR > SQ. In the weight distribution test, the holding power was higher as the front side of the weight was heavier. Generally, the frictional force is the same even if the shape is different, when two objects have the same value in the weight and the roughness. On the other hand, it seems to have a large impact when the shape of the bottom is deformed in the course of pulling the object. Particularly, the larger the degree of protrusion like cruciform weights, the more the holding power increased while deeply digging the bottom. It is also likely that the holding power increases as the front weight increases.
        4,000원
        271.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the quality characteristics and the antioxidant efficacy of roasted maize tea according to different moisture contents (9% to 14%) using the puffing system (PS) and the roasting system (RS). Compared with the RS, the PS caused higher turbidity (0.017 vs. 0.003 in PS-14% vs. RS-14%), brown color intensity (0.170 vs. 0.059 in PS-14% vs. RS-14%), a-values (0.20 vs. -0.44 in PS-14% vs. RS-14%), b-values (7.90 vs. 5.57 in PS-14% vs. RS-14%), and a lower L-value (19.67 vs. 21.03 in PS-14% vs. RS-14%). Total polyphenol and flavonoid contents of roasted maize tea were increased along with the moisture content and they were higher with the PS (polyphenol; 5.95 mg GAE/g, flavonoids; 1.27 CE/g in PS-14%) than with the RS (polyphenol; 5.39 mg GAE/g, flavonoids; 1.12 mg CE/g in RS-14%). The DPPH and ABTS radical scavenging effects of roasted maize tea were also increased along with the moisture content, and the scavenging efficacy was significantly higher with the PS (DPPH; 160 mg TE/100g, ABTS; 507 mg TE/100g in PS-14%) compared with the RS (DPPH; 120 mg TE/100g, ABTS; 362 mg TE/100g in RS-14%). The polyphenol levels were significantly correlated with turbidity, brown color intensity, and L, a, and b-values of the roasted maize tea. In addition, an increase of the total polyphenol content in roasted maize tea induced antioxidant activities. As a result, an increase in polyphenols during the roasting process induced antioxidant activities which could prevent damage from free radicals.
        4,000원
        272.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Importance of climate change and its impact on agriculture and environment has increased with the rise in the levels of Green House Gases (GHGs) in the atmosphere. To slow down the speed of climate change, numerous efforts have been applied in industrial sectors to reduce GHGs emission and to enhance carbon storage. In the agricultural sector, several types of research have been performed with emphasis on GHGs emission reduction; however, only a few work has been done in understanding the role of carbon sink on reduction in GHGs emission. In this study, we investigated ecosystem carbon balance and soil carbon storage in an agricultural paddy field. The results obtained were as follows: 1) Evaluation of soil C sequestration in paddy field was average 3.88 Mg CO2 ha-1 following NPK+rice straw compost treatment, average 3.22 Mg C ha-1 following NPK+hairy vetch treatment, and average 1.97 Mg CO2 ha-1 following NPK treatment; and 2) Net ecosystem production (NEP) during the paddy growing season was average 14.01 Mg C ha-1 following NPK+hairy vetch treatment, average 12.60 Mg CO2 ha-1 following NPK+rice straw compost treatment, and average 11.31 Mg CO2 ha-1 following NPK treatment. Therefore, it is proposed that organic matter treatment can lead to an increase in soil organic carbon accumulation and carbon sock of crop ecosystem in fields compared to chemical fertilizers.
        4,200원
        273.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Korean aquaculture industry was generally began in the 1970s and has gradually increased. Now, the number of households is about 7,068 and the scale of an aquaculture farm is about 248,014 ha; the value of all production in the industry is estimated to be about 1602.2 billion won. The aquaculture industry is very valuable and important for future food resources. However, the aquaculture industry was damaged by several marine ecological disturbance causing organisms. The Ascdiella aspersa colonized on the shell of scallop and then scallops were detached from rope. The patterns of damage in the aquacultures were observed in Tongyeong (oyster), Geojedo (oyster), and Gangneung (sea squirt) in June, 2017, as well as in Tongyeong (oyster) in November, 2017 by SCUBA divers. The species Halichondria bowerbanki, Bugula neritina, Mytilus galloprovincialis, Balanus amphitrite, Ascidiella aspersa, Ciona intestinalis, Didemnum sp, Styela plicata in Tongyeong, M. galloprovincialis, A. aspersa, C. intestinalis, D. vexillum, S. plicata in Geojedo, and M. galloprovincialis in Gangneung were all usually found in their farms. The marine ecological disturbance causing organisms gave rise to a reduced number of aquaculture products.
        4,000원
        274.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nannophya pygmaea (commonly known as the scarlet dwarf dragonfly) was designated as an endangered species, level II, by the Ministry of Environment of Korea in 1994; it has been used as a flagship species for the protection and preservation of wetlands. Over 25 sites in Korea have been identified as the habitat of Nannophya pygmaea. However, most of these habitats have proven to be unstable, and there have been subsequent changes in the assemblage structure and organization. Most habitats changed to become grasslands or plain ground, and now only five habitats remain. Although efforts have been made to protect the Nannophya pygmaea as an endangered species, their habitat loss has increased, caused by natural succession and drought. Therefore, we need to make stronger protections in the preservation manual of level II endangered species, particularly Nannophya pygmaea, and its native habitats in Korea.
        3,000원
        275.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sexual dimorphism of the mouthpart, antenna and mandible of the Cyllorhynchites ursulus in South Korea was studied with linear measurements. The mouthpart and antenna measurements were conducted with a stereoscopic microscope using 122 specimens (72 males and 50 females). Microscopic observation of the mandible were conducted with a Field Emission Scanning Electron Microscope (FE-SEM) using 103 specimens (73 males and 30 females). Results showed that the size difference between males and females was significant in the size of the mouthpart and antenna. On the other hand, we could not detect sexual size dimorphism in the microstructure of the mandible. The bivariate plots made by the result of Principal Component Analysis (PCA) and Discriminant Analysis (DA) showed a size dimorphism in the size of the mouthpart and the antenna between males and females. Based on our study, sexual dimorphism in the mouthpart and antenna exists in C. ursulus from the South Korean population, and this difference seems to be related to the behavioral differences between males and females.
        4,000원
        276.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Climate change may result in increases in air temperature and shifts in precipitation patterns as the result of increases in atmospheric CO2. Outdoor, naturally sunlit, plant growth chambers referred to as SPAR (Soil Plant Atmosphere Research) chambers are one of the important research facilities under controlled conditions. SPAR provide precise control of the major environmental variables influencing crop growth including temperature, humidity and atmospheric CO2 concentration. Especially the SPAR system is considered as the most realistic approach for studying crop canopy gas exchange including photosynthesis, respiration, transpiration. Indeed, many reports have confirmed that gas exchange values in SPAR is highly associated with dry matter and yield. So SPAR data can be used to develop quantitative relationships and functions, which are then tested against field data. In ARS, the SPAR system is widely used for research on: (1)Response and adaptation of crops and weeds to elevated CO2 and global warming, (2)Developing analytical and management strategies to improve crop utilization and to reduce losses due to the environment, (3)Mechanistic process-level crop simulation models for assessment of agricultural systems.
        4,000원
        277.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Waterlogging strongly affects maize (Zea mays L.) growth. It is necessary to find the screening method of waterlogging tolerant maize lines. This study was to investigate the growth characters at V3 stage of maize, when is very sensitive to waterlogging. Six Korean maize inbred lines were subjected to waterlogging at V3 stage for 30 days. The 30 days waterlogging treatment significantly reduced plant height, number of expanded leaves, and SPAD value, compared with the control plants. SPAD values were significantly different among the six inbred lines, KS140 was the highest. The dry matter accumulation of aerial and root part were significantly decreased by 30 days waterlogging. KS140 was the weightiest among inbred lines. The dry matter of adventitious root showed same trend. Waterlogging treatment significantly reduced to ear length and thickness, grains filling length, grain number per ear, and maize grain. Plant height, SPAD value, and number of fully-expanded leave showed high correlation with maize grain yield, but number of senescent leaves, dry matter of adventitious root and TR ratio did not, suggesting that the former three traits may be good indicator for evaluating 30-day waterlogging tolerance of maize inbred lines. KS164 was the highest yield by increasing of grains filling length and grain number per ear of among waterlogging inbred lines. According to the results, evaluation of maize waterlogging should be consider both early growth characteristics and resilience in the later growth stages.
        4,000원
        278.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Solar energy has been known as a successful alternative energy source, however it requires a large area to build power generation facilities compared to other energy sources such as nuclear power. Weather factors such as rainy weather or night time impact on solar power generation because of lack of insolation and sunshine. In addition, solar power generation is vulnerable to external elements such as changes in temperature and fine dust. There are four seasons in the Republic of Korea hereby variations of temperature, insolation and sunshine are broad. Currently factors that cause find dust are continuously flowing in to Korea from abroad. In order to build a solar power plant, a large area is required for a limited domestic land hereby selecting the optimal location for the plant that maximizes the efficiency of power generation is necessary. Therefore, this research analyze the optimal site for solar power generation plant by implementing analytic hierarchy process based on weather factors such as fine dust. In order to extract weather factors that impact on solar power generation, this work conducts a case study which includes a correlation analysis between weather information and power generation.
        4,200원
        279.
        2017.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
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