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        검색결과 151

        41.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To study the behavior of structures subject to blast loads it is important to calculate the loads due to the explosives accurately, especially in the case of interior explosions. It is known that numerical method based on computational fluid dynamics can estimate relatively accurate blast load due to the interior explosion including reflection effect. However, the numerical method has disadvantages that it is difficult to model the analysis and it takes much time to analyze it. Therefore, in this study, the analytical method which can include the reflection effect of the interior explosion was studied. The target structures were set as the slabs of residential buildings subject to interior explosion that could lead to massive casualties and progressive collapses. First, the numerical method is used to investigate the interior explosion effect and the maximum deflection of the slab which was assumed to be elastic, and compared with the analytical method proposed in this study. In the proposed analytical method, we determine the weighting factor of the reflection effect using the beam theory so that the explosion load calculation method becomes more accurate.
        4,000원
        43.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        치자 껍질의 항산화 활성을 측정하기 위하여 70% methanol, distilled water (DW) 및 ethyl acetate (EA)의 3가지 용매를 사용한 추출물의 용매 별 flavonoid 함량 및 항산화 활성, 금속 chelating 능력 측정을 통하여 치자 껍질의 기능성 식품 재료로서의 가치를 검토한 결과, 치자 껍질의 proanthocyanidin 함량은 48.165±0.811 mg CE/g DW로 나타났으며, 추출 수율은 70% methanol (36.26%), DW (39.87%), EA (2.88%) 로 나타났다. 추출 용매 별 항산화 활성은 농도(0.2, 0.4, 0.6 mg/mL)가 증가할수록 유의적으로 증가하였으며, control로 사용된 ascorbic acid, BHA, EDTA 보다는 낮은 활성이 관찰되었다. Flavonoid 함량(mg QE/g)은 70% methanol (0.416), DW (0.225), EA (0.212) 순으로 확인되었으며 다른 항산화 분석 및 금속 chelating 능력 실험에서도 이와 유사하게 관찰 되어 모든 분석에서 70% methanol 추출물이 가장 활성이 강한 것으로 나타났다. 이상의 결과를 미루어 볼 때 치자 껍질의 용매 별 flavonoid 함량에 따라 항산화능, 금속 chelating 능력이 증가하는 것으로 사 료되며, EA 추출물을 제외한 다른 추출물에서의 수율과 항산화 활성은 높은 수준으로 관찰되었다. 따라 서 치자의 껍질은 proanthocyanidin과 flavonoid 화합물을 다량 함유하고 있으며 그로 인한 높은 항산 화 활성과 생리활성을 가지고 있어 기능성 식품 및 천연항산화제로서의 가치가 매우 기대된다.
        4,000원
        44.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        치자 씨 추출물이 항산화력 및 지질과산화 저해능에 미치는 영향을 알아 보고 치자의 기능성 식품 소재로서의 가치를 검토하기 위하여 실험을 수행한 결과, 치자 씨의 anthocyanin 함량을 측정한 결과 2.201±0.516 mg/100 g DW로 나타났으며, 치자 씨의 용매 별 추출 수율은 chloroform:methanol (CM, 2:1, v/v) 36.39%, 70% ethanol (27.32%), n-butanol (26.23%) 로 확인되었다. 추출 용매 별 항산화 활성은 농도(0.2, 0.4, 0.6 mg/mL)가 증가할수록 유의적으로 증가하였으며 positive control로 사 용된 ascorbic acid, BHA, trolox 보다는 낮은 활성이 관찰되었다. 치자 씨의 total phenol 함량(mg CAE/g)은 CM (32.50), 70% ethanol (30.09), n-butanol (11.07) 추출물 순으로 n-butanol 추출물에 서 가장 적은 함량을 보였으며, Nitric oxide (NO) radical 소거능에서는 CM (76.97~84.24%), 70% ethanol (74.10~79.99%), n-butanol (30.66~37.15%) 추출물 순으로 관찰되었다. Nitrite (NO2) 소거능 은 CM (33.53~43.23%), 70% ethanol (32.40~35.98%), n-butanol (24.72~28.14%) 순으로 관찰되었 다. β-carotene 탈색 저해능은 CM (23.73~44.70%), 70% ethanol (22.03~41.32%), n-butanol (16.00~27.87%) 순으로 확인되었다. Reducing power (optical density)는 70% ethanol (0.073~0.182), CM (0.057~0.154), n-butanol (0.028~0.079) 순으로 관찰되었다. 지질과산화 저해능은 씨 추출물 중 CM (53.26~76.56%), 70% ethanol (52.97~76.56%), n-butanol (38.54~53.33%) 순으로 나타났다. 이 에, 치자씨 추출물은 천연 항산화제로서 기능성 식품의 가치가 높을 것으로 판단된다.
        4,000원
        45.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The acai berry (Euterpe oleracea Mart.) contains vitamin B complex, vitamin C, anthocyanin and so on. Especially acai berry was seen as nutritionally comparable to blueberry and related berries. The acai berry has significant aging-reducing properties. Compounds have been found to have anti-aging and antioxidant components. Acai berry was extracted with 70% methanol, 70% ethanol and CM (chloroform:methanol=2:1, v/v). After sample and reagents of each experiment was reacted, DPPH radical scavenging activity and ABTS radical scavenging activity, ferric reducing antioxidant power, reducing power were measured to determine the antioxidant capacity, and as results of comparing each extract. Ethanol (70%) extraction was measured highest. Anthocyanin, total phenol, flavonoid also appeared similar to the results. In addition, the antioxidant activities of the extraction solvents were increased significantly with increasing concentrations, but showed lower antioxidant activity than the positive control (ascorbic acid). As a result, antioxidant activities of sample supposed to affect by the anthocyanin, phenol and flavonoid contents.
        4,000원
        46.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The black raspberry (Rubus coreanus Miquel) contains anthocyanin, tannins, gallotannin, gallic acid, ferulic acid and phenolics. It brightens the eyes and protects the liver and kidneys. It was effective for anti-aging. Thus, the purpose of this study was to inform the excellence of black raspberry and to screen antioxidant activity to ensure the possibility as a functional material. In this study, bioactive compounds in black raspberry were determined. Additionally, black raspberry was extracted by CM (chloroform:methanol, 2:1, v/v), 70% methanol and 70% ethanol, and were investigated and compared in vitro methods. Total phenol and flavonoid contents were measured to compare each different solvents. In addition, DPPH radical scavenging activity and ABTS radical scavenging activity, ferric reducing antioxidant power, reducing power were determined to measure the antioxidant activity. The results were the highest in 70% ethanol extracts, and the higher the concentration showed a significantly higher antioxidant capacity. When observed the relationship between the study, antioxidant activity of black raspberry was supposed to affect by the anthocyanin, phenol and flavonoid contents.
        4,000원
        47.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근에 요소망의 재구성이 불필요하고 균열의 가시화에 강점을 가지는 확장유한요소법(XFEM)을 이용한 균열 해석이 많이 연구되고 있지만 주로 단일재료로 이루어진 부재의 해석에 집중되어 있다. 본 논문에서는 복합재료 부재인 철근콘크리트보의 다중균열 해석에 확장유한요소법을 적용하며 그 적용성과 타당성을 살펴보았다. 확장유한요소해석 기능이 탑재된 상용해석프로그램인 ABAQUS를 사용하여 균열해석을 수행하였으며 그 결과를 실험결과와 비교하였다. 확장유한요소법에서 인접요소에 동시에 균열이 발생할 경우 균열의 불연속성이 나타나지 않은 부가자유도 잠김 현상을 발견하였고 이에 대한 원인과 그 해결방안을 제시하였다. 또한 실험결과와 유사한 다중균열 발생을 위한 모델링 기법도 제시하였다. 확장유한요소법을 이용한 해석결과는 실험결과와 유사한 균열 양상 및 균열 간격을 보여 주었으며 하중-변위 관계에 있어서도 실험에 근접한 결과를 보여 주었다.
        4,000원
        48.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 부분 보강된 CFT 기둥의 폭발저항성능을 일반 CFT 기둥과 비교하여 강판 보강의 효과를 확인하였다. 폭발하중을 받는 CFT 기둥의 구조해석에는 폭발과 충돌 해석을 위한 특수한 하이드로코드인 Autodyn을 사용하여 수치해석을 수행하였다. 콘크리트와 이를 둘러싸고 있는 강판 사이의 상호작용을 모델링하는 여러 방법이 있다. 본 연구에서는 기둥의 실제 파괴를 표현하기 위해 마찰 옵션 및 조인 옵션으로 모델링하였다. 해석에 따르면, 부분 보강된 CFT 기둥은 일반 CFT 기둥에 비해 더 나은 폭발저항효과를 나타내었다. 보강 CFT기둥의 폭발저항성능은 콘크리트를 둘러싸고 있는 부분 보강된 강판의 높이가 높을수록 향상되었으며 CFT 기둥의 단면 크기 이상으로 보강할 것을 추천한다.
        4,000원
        49.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to improve the ammonia (NH3) emission inventory estimation in the domestic CAPSS (Clean Air Policy Support System). Currently, the ammonia emissions rate is obtained by multiplying the activity (number of livestock) by emission factors. The amount of movement and treatment are not considered in the estimation of ammonia emission rates. However, livestock manure is currently moved and treated in accordance with the energy recycling policy. In this study, the new emission estimation method were suggested considering the moving and treatment characteristics of livestock manure. A new ammonia emissions was calculated for Bcity and Y-gun at Chungcheongnam-do province. It was shown that the moving and treatment ratio of ammonia emissions were 4.3% and 8.4%, respectively. Furthermore, this ratio would be increased rapidly with the continuous establishment of large-scale manure treatment facilities.
        4,000원
        50.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was performed to produce WBM (wheat and barley mixture) bread containing molokhia powder with quality characteristics and antioxidant activities. Analysis of the chromaticity of WBM prepared with molokhia powder showed that; the lightness and redness were decreased, but yellowness was increased. In mechanical properties, hardness, gumminess, and chewiness were significantly increased as the amount of molokhia powder was increased. However, cohesiveness was significantly decreased. In sensory evaluation, WBM bread containing 1.5% of molokhia powder (MB1.5) showed an overall high preference level. The total polyphenol content of molokhia powder EtOH extract and MB1.5 were 29.19 and 58.18 mg TAE/g, respectively. The total flavonoid contents of molokhia powder EtOH extract and MB1.5 were 20.62 mg and 33.25 mg RE/g, respectively. The radical scavenging ability (IC50) of DPPH (IC50) for molokhia powder EtOH extract and MB1.5 was 31.04 and 58.18 μg/mL, respectively while that of ABTS was 33.25 and 54.15 μg/mL, respectively. The α -glucosidase inhibitory effects of molokhia powder EtOH extract and MB1.5 were 494.88 and 814.88 μg/mL, respectively. MB bread containing 1.5% molokhia powder showed antioxidative effects and α-glucosidase inhibitory activity, meaning that not only molokhia but also MB1.5 bread has the potential to prevent chronic degenerative diseases such as diabetes.
        4,000원
        51.
        2015.02 구독 인증기관 무료, 개인회원 유료
        The contents of this paper is to develop a passive sampler for H2S measurement. When the H2S gas exists in the air, AgNO3 solution coated filter of white used phenomenon which is exchanged with black. If the H2S gas concentration increased, the color of AgNO3 solution coated filter is discolored more black. H2S passive sampler measures the H2S gas concentration by changed color of AgNO3 solution coated filter. The reproducibility of the H2S passive sampler is very stable to within an error 5%RSD. The black color of AgNO3 solution coated filter showed a linear relationship with the H2S gas concentrations. In addition, correlation of the developed CDM and CR-10(Minolta, Japan) showed a high correlation to 0.99. Manufactured H2S passive sampler must be kept refrigerated, stability and reactivity was observed for up to 20 days
        4,000원
        52.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research determined the threshold value of 10 specified offensive odor substances based on the 3 point comparison sensory method. The panelist's thresholds were calculated by taking the arithmetic, geometric mean, and 50th percentile. Three methods of calculating the odor thresholds from the same data are compared. For 10 odor substances, the panelist's thresholds revealed a logarithmically normal distribution. The 50th percentile was the best method among the three methods of calculating the odor threshold from the 270 thresholds of 18 panels. As a result, the threshold values of individual odor substances, including i-valeric acid, n-valeric acid, n-butyric acid, and butyl acetate ranged between 0.0001~0.006 ppm, while the values of methyl ethyl ketone and toluene were relatively higher than that of other substances at 0.7107 ppm and 1.2139 ppm, respectively. The threshold values of the 10 specified odor substances were compared in Korea and overseas, which showed that the characteristics of sensory response varied by substance and nation.
        4,500원
        53.
        2014.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research is carried out to investigate the odor emission characteristics in a sewage treatment plant. The plantwas divided into four areas (boundary areas, sewage treatment processes, sludge treatment processes and odortreatment plants), and measured around 27 sampling points. Odor characteristics from each areas were evaluatedby air dilution olfactory method and NH₃/SO₂/VOCs passive sampler, mainly in terms of spatial distribution. Themain odor emission sources were found out to be dewatering plant (S-4) of sludge, sludge transshipment place(S-5), and the outlet of odor treatment plant (B-2, B-3). The correlation between dilution number (OU) and ammoniaconcentration of passive sampler appeared to be low; correlation coefficient 0.49, but correlation coefficient for theresults of sulfur dioxide and toluene were very high, 0.95 and 0.93, respectively. These results indicate that odorcompounds form sewage treatment facility are mainly due to sulfur compounds and volatile organic compounds.
        4,000원
        54.
        2014.02 구독 인증기관 무료, 개인회원 유료
        This study evaluated the concentration(OU/m3) of a complex odor being discharged from tire, feedstuff, bakery, paper, casting and painting manufacturing process, correlation between odor concentration(OU/m3) and the odor sensor was investigated. 4 type(A, B, C, D) gas sensors of metal oxide compounds are used in this study. Each odor sample of manufacturing process is diluted with odorless air and diluted odor samples were prepared for five different concentrations. Correlation results(R) of odor sample of tire, feedstuff, bakery, paper manufacturing process ware 0.86~0.99, and odor sample of casting, painting manufacturing process ware more than 0.93. Thus the odor concentration(OU/m3) evaluation by odor sensor was to determine the possible. In particular odor sensor B and D are likely to be effective for evaluation of odor concentration. However, odor samples before evaluation is needed the calibration process depending on the field odor sample to field apply.
        4,000원
        55.
        2012.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the effects of the secondary tasks such as sending text message (STM) and searching navigation (SN) on skin conductance level (SCL) and driving performance of relatively aged and high-experienced drivers. The s
        4,000원
        58.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 50대 택시 운전자를 대상으로 동작 신호인 Jerk-Cost function(JC)와 차간거리의 분산계수(Anterior-Posterior Coefficient of Variation, APCV), 차선이격거리의 분산계수(Medial-Lateral Coefficient of Variation, MLCV)와 같은 차량 통제 데이터를 이용하여 운전 중 문자 메시지 전송 또는 네비게이션 검색과 같은 동시 과제 수행이 운전 수행 능력에 어떠한 영향을 미치는지를 알아보고자 하였다. 남성 14명과 여성 14명을 대상으로 실험을 진행하였다. 피험자는 일정 속도(80km/hr or 100km/hr)로 주행하는 선행 차량과 일정 거리 30m를 유지하며 주행하도록 하였다. 처음 1분간은 운전만을 수행하게 하였으며, 다음 1분 동안은 운전만을 수행하거나 운전과 함께 동시 과제를 수행하도록 하였다. MLCV와 APCV는 80km/hr와 100km/hr 주행 시 Driving only에 비해 Driving + Sending Text Message(STM)와 Driving + Searching Navigation(SN)에서 유의하게 증가하였다. JC 또한 주행 시 Driving only에 비해 Driving + STM과 Driving + SN에서 증가하였다. 본 연구를 통해 운전 경력이 길고 운전 전문가라고 할 수 있는 50대 택시 운전자도 운전만을 수행하는 경우에 비해 운전과 함께 문자 메시지 전송 또는 네비게이션 검색 과제를 수행하게 될 경우 동작 패턴이 거칠어지고 차량 통제가 어려워진다는 사실을 도출할 수 있었다.
        4,000원
        60.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        인간 활동이 생태계의 훼손과 생물다양성의 변화에 미치는 영향을 경관생태학적 측면에서 분석하고 해석하는 연구가 활발히 진행되고 있다. 본 연구는 우리나라의 35개 농촌마을을 대상으로 자연생태계의 교란정도를 알 수 있는 귀화식물분포현황을 조사하였다. 대상지에 대한 토지이용 현황도를 제작하고 이를 바탕으로 경관지수를 이용하여 경관생태학적특성을 정량화하였다. 이를 바탕으로 대상지의 경관지수와 귀화식물 분포특성의 상관관계를 분석하였다. 경관지수는 공간분석 프로그램인 FRAGSTATS를 이용하여 산출하였으며 귀화식물의 분포특성은 Urbanization Index와 Naturalization Index를 이용하였다. 연구 결과 귀화율과 패치밀도, 귀화율과 가장자리밀도, 귀화율과 면적가중평균형태지수 등이 양의 상관관계를 나타냈으며 귀화율과 핵심면적백분율, 귀화율과 평균핵심지역 등이 음의 상관관계가 있는 것으로 분석되었다.
        4,800원
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