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        검색결과 45

        21.
        2003.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        샌드위치 판은 질량에 비해 높은 강성과 강도를 갖고 있으므로 매우 효율적인 구조재로서 폭넓게 쓰이고 있다. 알루미늄 압출 샌드위치 판의 적절한 설계를 위하여는 역학적 거동 해석이 선행되어야 하나, 아직 이에 대한 연구는 미비한 상태이다. 코어가 채워져 있지 않은 중공 단면(hollow section)인 샌드위치 판의 역학적 거동 해석에는 일반적으로 상세 유한 요소 해석을 하게되나, 이는 모델링과 해석에 많은 시간이 소요된다. 본 논문에서는 트러스(truss) 형상의 심재를 갖는 샌드위치 구조 압출재를 이방성의 판으로 치환하여 해석하는 방법을 제시하였다 적절한 이방성 후판으로의 치환을 위해 등가의 강성을 평가하는 방법을 제안하였으며, 이 등가의 강성을 판 이론에 적용하여 균일 분포 하중을 받는 사변 단순지지 조건의 알루미늄 압출재에 대한 처짐과 응력에 대해 간이 해석식을 개발하였다. 아울러 상용 유한 요소 프로그램을 이용하여 계산한 결과와 비교한 결과 제시한 간이식의 높은 정도와 효율성이 입증되었다.
        4,000원
        22.
        2003.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        현수교의 지진응답 산정 시 몇 가지 해석법 간에 발생될 수 있는 차이를 파악하고자 하나의 예제 현수교에 대해 비교 연구를 수행하였다. 주된 검토항목은 선형과 비선형 응답응답스펙트럼법과 동적해석법, 그리고 감쇠율과 감쇠고려 방안이다. 검토 결과 대상 물리량이나 가진 방향에 따라 약간의 차이는 있지만 전체적으로 감쇠율과 감쇠 고려방안 등 감쇠와 관련된 변수가 지진응답에 큰 영향을 미치고 있음을 확인하였다. 반면 응답스펙트럼과 동적해석법, 선형 및 비선형해석법 등 구조해석법에 관련된 변수는 상대적으로 지진응답에 미치는 영향이 적은 것으로 확인되었다. 대상 현수교의 경우에도 응답스펙트럼법이 안전측의 결과를 줄 수 있을 것으로 기대되지만 이 경우 도로교설계기준에 제시된 설계응답스펙트럼을 감쇠율에 따라 적절히 보정하는 사전 작업이 필요랄 것으로 판단되었다.
        4,000원
        23.
        1997.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        지진하중을 받는 현수교의 기하비선형 거동특성을 분석하기 위하여 비선형 지진응답해석 알고리즘을 정립하고 그에 따른 전산프로그램을 개발하였다. 해석이론을 최근 시도되고 있는 자정식 현수교나 mono-duo 형식의 주케이블 형상을 갖는 독특한 현수교에 대해서는 적용가능하도록 유한요소법을 사용하였다. 입력지진은 장지간 교량의 다중지지효과를 고려하기 위하여 한 지점에서 다른쪽 지점으로 형상변화 없이 이동한다고 가정하였다. 하나의 mono-duo 자정식 현수교에 대하여 비선형 지진해석을 수생한 결과 예제의 교량이 비교적 단지간이어서 비선형 거동특성과 다중지지 효과가 두드러지게 나타나지는 않음을 확인할 수 있었다.
        4,600원
        24.
        2014.04 KCI 등재 서비스 종료(열람 제한)
        The Ponciri fructus immaturus (Poncirus trifoliata Rafinesque) has been used in oriental medicine for uterinecontraction, stomachache, abdominal distension and cardiovascular diseases. Two main compounds, poncirin and naringinwere successfully analyzed by high performance liquid chromatography (HPLC) and carried out method validation accordingto ICH guideline. A successful resolution and retention times were obtained with a C18 reversed phase column, at an 1㎖min−¹ flow rate, with a gradient elution of a mixture of methanol, water and acetonitrile. Poncirin and naringin showed goodlinearity (R²>0.999) in relatively wide concentration ranged. The recovery of each compound was 95.81~101.48% withR.S.D. values less than 1.0%. The application of ultrasound-assisted extraction was shown to be more efficient in extractingponcirin and naringin from Ponciri fructus immaturus. The predicted optimal poncirin and naringin yield were poncirin2.15%, naringin 1.65% under an extraction temperature of 40℃, an extraction time of 10 min in a solvent of 70% methanol.
        25.
        2013.12 KCI 등재 서비스 종료(열람 제한)
        Collected germplasms of five representative species belonging to Curcuma genus (C. longa, C. aromatica, C.zedoaria, C. phaeocaulis and C. kwangsiensis) were 52 samples from different farmhouse in Korea and China. To elucidatethe genetic diversity among the species, 52 samples were analyzed by genomic fingerprinting method using amplified frag-ment length polymorphism (AFLP). AFLP results of 6 primer combinations were revealed 643 total DNA fragments and349 polymorphic bands with the 54.3% ratio of polymorphism. In the analysis of coefficient similarity using unweight pairgroup method with arithmetic averages (UPGMA), 52 Curcuma germplasm lines were ranged from 0.60 to 0.99 and clus-tered distinct five groups according to the species and collected geographical levels. However, the result of principal coordi-nate analysis (PCA) by multi-variate analysis was shown significantly greater differences among species than geographicalorigins based on AFLP profiling data of these samples.
        26.
        2013.08 KCI 등재 서비스 종료(열람 제한)
        Collected germplasms of five representative dandelion species (Taraxacum ohwianum, T. platycarpum, T. platypecidum, T. officinale, and T. coreanum) were 104 lines from different habitates in Korea and China. Their genetic diversity was analyzed by genomic fingerprinting method using amplified fragment length polymorphism (AFLP). AFLP results of 6 primer combinations were revealed 1,176 total DNA fragments and 523 polymorphic bands with a 44.4% ratio of polymorphism. On the basis of similarity coefficient analysis by unweight pair group method with arithmetic averages (UPGMA), 104 dandelion germplasm lines were ranged from 0.64 to 0.99 and clustered distinct five group depending on the species. Furthermore, a principal coordinate analysis (PCA) by the application of multi-variate analysis indicated significantly greater differences among species than geographical origins.
        27.
        2013.06 KCI 등재 서비스 종료(열람 제한)
        The fruits of Schisandra chinensis have been used as an edible ingredient and traditional medicine in Korea. Due to morphological similarities of dried mature fruits, the correct identification of S. chinensis from other closely related Schisandrae species is very difficult. Therefore, molecular biological tools based on genetic analysis are required to identify authentic Schisandrae Fructus. Random amplifed polymorphic DNA (RAPD) and Sequence Characterized Amplified Region (SCAR) were used to develop an easy, reliable and reproducible method for the authentication of these four species. In this paper, we developed several RAPD-derived species specific SCAR markers and established a multiplex-PCR condition suitable to discriminate each species. These genetic markers will be useful to distinguish and authenticate Schisandrae Fructus and four medicinal plants, S. chinensis, S. sphenanthera, S. repanda and K. japonica, in species level.
        28.
        2013.04 KCI 등재 서비스 종료(열람 제한)
        This study was conducted to investigate the residual contents of sulfur dioxide (SO2) in commercial medicinal herbs in Korea in 2012. Among a total of 136 samples of 16 different kinds of herbs, 86 samples (15 Kinds) were domestic, and 50 samples (14 Kinds) were imported. Sulfur dioxide in the samples was measured by a modified Monier-Williams method. Of the 136 samples, 17 samples (12.5%, 6 Kinds) failed to meet the regulations for sulfur dioxide residues of KFDA in medicinal herbs. Among 17 unsuitable samples, 7 samples (8.1%, 3 Kinds) were domestic, and 10 samples (20.0%, 6 Kinds) were imported. The highest amount of sulfur dioxide residues was 3,167.94 mg/kg (Lycii Fructus) in the domestic samples. The detection frequency of sulfur dioxide by medicinal herb parts used, Rhizoma 25.7%, Flos 20.0%. Cortex 12.5%, Radix 15.3%, Fructus 7.6%, p-value 0.011. This results will be used as a basic data for the future legislation on the quality estimation and safety of medicinal herbs.
        29.
        2012.12 KCI 등재 서비스 종료(열람 제한)
        This study was conducted to determine the contents of heavy metal in commercial herbal medicines. The monitoring of lead, arsenic, cadmium and mercury was carried out on 100 samples with 10 kinds of herbal medicines. The contents of heavy metal were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) and mercury analyzer. The mean values of heavy metal contents for herbal medicines were Pb 1.87 mg/kg, As 0.39 mg/kg, Cd 0.26 mg/kg and Hg 0.021 mg/kg. Of the total samples, 19 samples (19%, 4 types) were violated the KFDA regulatory guidance of heavy metal in herbal medicines (9 samples on Pb, 10 samples on Cd). Among these 19 unsuitable samples, 16 samples were domestic and 3 samples were imported. Therefore, we need continuously monitoring to ensure confidence and safety for these herbal medicines.
        30.
        2011.06 KCI 등재 서비스 종료(열람 제한)
        The rhizomes and herbal medicines originating from Acorus gramineus, A. calamus, A. tatarinowii, and A. gramineus var. pusilus, show significant similarity, and the correct identification of species is very difficult. Random Amplified Polymorphic DNA (RAPD) and Sequence Characterized Amplified Region (SCAR) were used to develop a reliable method for identification of these four species. Several distinct SCAR markers were developed from species-specific RAPD amplicons for each species. Furthermore, a useful molecular marker was established for multiplex-PCR, in order to the four species could be distinguished concurrently. These markers allow efficient and rapid identification of closely-related Acorus species and will be useful for standardization of herbal medicines.
        31.
        2010.12 KCI 등재 서비스 종료(열람 제한)
        Adenophora racemosa is recently reported as a new Korean endemic plant species. However, the phylogenetic relationship of this genus has been controversial due to the morphological similarity and frequent morphological change of aerial parts. To verify the phylogenetic position of Adenophora racemosa and phylogenetic relationship of genus Adenophora, we analyzed the internal transcribed spacer (ITS) sequence of nuclear ribosomal DNA (nrDNA) and random amplified polymorphic DNA (RAPD) using 21 individual of 6 Adenophora species, A. verticillata, A. divaricata, A. racemosa, A. remotiflora, A. stricata and A. tetraphylla. In comparative analysis of the nrDNA-ITS sequences, we could not found not only any species specific nucleotide sequence but also could not estimated their inter or intra species. In the phylogenic analysis based on the RAPD derived DNA polymorphism, Adenophora species were classified into four groups by clustering analysis of the UPGMA. These results suggest that the DNA fingerprinting based on RAPD is more suitable than nrDNA-ITS sequence for the phylogenetic analysis of Adenophora species.
        32.
        2010.06 KCI 등재 서비스 종료(열람 제한)
        Obesity has become one of the main public health problems. Saussurea lappa (Asteraceae), syn Aucklandia lappa and Saussurea costus, is a well-known herbal medicine that has been used for treating various ailments, such as inflammatory and gastrointestinal diseases. The present study examined the anti-obesity effect of S. lappa extract (SLE) in 3T3-L1 adipocytes and high fat diet (HFD)-induced obese mouse model. SLE significantly inhibited the differentiation from preadipocytes to adipocytes of cultured 3T3-L1 in dose-dependent manner. In addition, SLE significantly decreased the body weight gain and the food efficiency ratio of mice fed HFD during 9 weeks. Further study must be performed for the pharmacological mechanism and safety of SLE as well as the identification of active compound in SLE. Our results revealed that S. lappa suppresses the adipogenesis in cultured cells and the obesity in rodent models. Therefore, S. lappa may be useful toward the development of new potent anti-obesity drugs.
        33.
        2010.02 KCI 등재 서비스 종료(열람 제한)
        Glycyrrhiza uralensis (Leguminosae) is a well-known herbal medicine that has long been valued as a demulcent to relieve inflammatory disorders. To compare the influence of different solvents on the anti-inflammatory efficacy of G. uralensis, we measured the inhibition of pro-inflammatory mediators such as NO, TNF-α, and PGE2 in lipopolysaccharide (LPS)-stimulated mouse macrophage RAW 264.7 cells by extracts produced using different solvents (water, methanol, ethanol, or n-hexane). The results showed that methanol was the most effective solvent for the inhibition of both NO and PGE2 production in RAW 264.7 cells. However, there was no difference among the extracts for inhibition of TNF-α. Further study must be performed for the analysis of correlation between the anti-inflammatory activity of extracts produced using different solvents and the content of major bioactive compounds in G. uralensis, such as glycyrrhizin and liquiritin. The present study suggests that methanol may be a more appropriate solvent of G. uralensis than other solvents (water, ethanol, and n-hexane) to yield the greatest anti-inflammatory activity for food additives and medicine.
        34.
        2009.10 KCI 등재 서비스 종료(열람 제한)
        In this paper, changes in the intensity (e.g., central pressure and maximum sustained wind speed) of Tropical Cyclone (TC) in summer in the regions located at 30 oN in East Asia from 1988 to 1991 were found. The intensity of TC from 1991 to 2007 was much higher than that of TC from 1965 to 1988. The reason for this was that the frequency of TCs passing China from 1991 to 2007 was much lower than that of TCs from 1965-1988 because a northeasterly wind caused by high-pressure circulation in East Asia got severer along the East Asian coast. Instead, TCs moved from the eastern region of the Tropical West Pacific to Korea and Japan mainly after passing the East China Sea due to the low-pressure circulation strengthened in the subtropical waters of East Asia. In addition, low Vertical Wind Shear (VWS) was created along the mid-latitude regions of East Asia and the main path of TCs from 1991 to 2007. Most of the regions in the Northwestern Pacific showed higher Sea Surface Temperature (SST) from 1991 to 2007, and had a good environment where TCs were able to maintain a higher intensity on the mid-latitude. In particular, a low sensible heat flux occurred due to high snow depth in East Asia in the spring of 1991 to 2007. Accordingly, the lower layer of East Asia showed high-pressure circulation, and the sea surrounding East Asia showed low-pressure circulation. Thus, the typical west-high, east-low pattern of winter atmospheric pressure was shown. The possibility of snowfall in East Asia in spring to be used as a factor for predicting the summer intensity of TC in the mid-latitude regions of East Asia was insinuated. The characteristics of TC in a low-latitude region were the same in Korea. The latest intensity of TCs got higher, and the landing location of TCs gradually changed from the west coast to the south coast.
        35.
        2009.05 KCI 등재 서비스 종료(열람 제한)
        This study found that tropical cyclones (TCs) formed for fall in 2007 over the western North Pacific were distributed in high-latitudes comparing to 56-year (1951-2006) climatological mean. The frequency and latitude of TC genesis became higher than 56-year climatological mean from September onward in 2007 and all the TCs that formed to the north of 20°N was also distributed after September in 2007. These characteristics of TC genesis for fall in 2007 could be confirmed through analyzing various variables, such as a large-scale atmospheric circulation, outgoing longwave radiation (OLR), vertical zonal wind shear, and sea surface temperature (SST). On the other hand, a frequency of the TC that occurred to the north of 20°N showed a clear interdecadal variation and its decreasing trend was distinctive in recent years. Its intensity was also weaker that TCs that did to the south of 20°N. However, a latitude of TC genesis showed an increasing trend until recent years, whose variation was consistent with trend that through a SST analysis, warm SST went north in recent years.
        36.
        2009.04 KCI 등재 서비스 종료(열람 제한)
        This study was carried out to investigate the distribution of native Asparagus cochinchinensis and ecological characteristic in South Korea. Natural vegetative areas were investigated at 5 areas; Taean, Buan, Geoje, Namhae and Jindo. In this study, the 5m×5m quadrat was established for recording coverage and appearance species by phytosociological method. The flora of the studied area in native habitats were listed as 130 species. The native habitats was classified into Pinus thunbergii community and typical community. Two communities were located in a coastal cliff and have been destroyed. Therefore Asparagus cochinchinensis native habitats must be protected by regulation. In the studied sites, soil pH, organic matter, nitrogen, available phosphorus, exchangeable K, exchangeable Ca, exchangeable Mg and cation exchange capacity were ranged from 5.1~5.7%, 1.77~3.59%, 0.19~0.54%, 5.4~18.7 (mg/kg), 0.24~0.48 (cmol+/kg) 0.76~2.83 (cmol+/kg), 3.11~6.22 (cmol+/kg) and 8.7~24.5(cmol+/kg), respectively.
        37.
        2009.04 KCI 등재 서비스 종료(열람 제한)
        Rhubarb is the well-known and frequently used herbal medicine for the treatment of constipation, inflammation, and cancer. As described in the Korea and Chinese Pharmacopoeia, rhubarb consists of the roots and rhizomes of Rheum palmatum, R. officinale, and R. tanguticum. However, the pharmacological differences among rhubarb have not been scientifically established. In the present study, we investigated and compared the inhibitory effects of 70% ethanolic extracts from R. palmatum (RPE), R. officinale (ROE), R. nobile (RNE), and R. franzenbachii (RFE) on the production of inflammatory mediators, nitric oxide (NO), prostaglandin E2 (PGE2), interlukin-1beta (IL-1β), and tumor necrosis factor-alpha (TNF-α) in RAW 264.7 macrophage cells. ROE, RNE, and RFE significantly inhibited the release of NO, PGE2, IL-1β, and TNF-α. RPE significantly reduced the release of IL-1β, but not NO, PGE2, and TNF-α. Overall, RFE was found to inhibit the release of PGE2 and IL-1β, to a far greater degree than RPE, ROE, and RNE. Our results indicate that RFE possess the strongest anti-inflammatory activity among 4 tested rhubarb.
        38.
        2008.06 KCI 등재 서비스 종료(열람 제한)
        Poncirus trifoliata Rafinesque has been used as the immature fruit of the trifoliate orange tree. This study was carried out to investigate the quality change of Poncirus trifoliata Rafinesque depending on packing materials (vacuum packing, PP (polypropylene) packing, gunny sack packing), storage places and storage periods up to 12 months. The change of loss on drying content, content of poncirin were measured during the 12 months. As a result, the loss on drying content was decreased rapidly in gunny sack packing after storage of 12 months at room temperature. The content of poncirin was decreased generally according to storage conditions and its average loss percent was 38.8%.
        39.
        2008.06 KCI 등재 서비스 종료(열람 제한)
        The root of Angelica tenuissima Nakai (Umbelliferae) has been used in traditional medicines of Korea as a headache, common cold and a fever remedy. A. tenuissima contains ferulic acid and various compounds of essential oil group such as limonene, 3-butylidenephthalide, γ-terpinene, neocnidilide, ligustilide, senkyunolide and neocnidilide. This study carried out to compare the contents of ferulic acid, z-ligustilide and n-butylidenephthalide between native and cultivated species of A. tenuissima by HPLC. The average contents of ferulic acid, z-ligustilide and n-butylidenephthalide indicated that native species (9 samples) were 0.060%, 0.616%, 0.025% and cultivated species (15 samples) were 0.037%, 0.141%, 0.029%, respectively. All samples were collected from different places in Korea.
        40.
        2008.06 KCI 등재 서비스 종료(열람 제한)
        This study was investigated that quality inspection of distributed Scutellariae Radix in Korea. To evaluate the quality of these herbal medicines, we carried out TLC pattern, foreign matter in purity, loss on drying, ash, acid-insoluble ash, oil content, dilute ethanol-soluble, water-soluble, ether-soluble extracts contents, quantitative analyses, residual SO2, individual heavy metals and organochlorine pesticides. To measure contents of baicalin, baicalein and wogonin, we were quantitative analyzed using HPLC. The average contents of baicalin, baicalein and wogonin were detected by 13.28 (±0.43)%, 1.17 (±0.04)% and 0.40 (±0.02)%, respectively. Each average contents As, Cd, Hg and Pb was 0.059 (±0.054) mg · kg-1, 0.019 (±0.010) mg · kg-1, 0.017 (±0.057) ppm and 0.242 (±0.084) mg · kg-1, respectively.
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