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        검색결과 320

        181.
        1995.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Al-Mg-Cu-Mn계 합금을 가공열처리하고 초소성 특성을 조사한 후 광학 및 전자 현미경을 이용하여 초소성에 영향을 미치는 주요한 인자들을 조사하였다. 균질화 과정에서 제거되지 않은 조대한 2차상들은 그 후의 가공열처리 과정에서도 계속 잔류하여 초소성 변형 중 기공을 유발함으로써ㅓ 초소성 신율을 저하시켰다. 반면에 가공열처리 과정에서 생성된 미세한 석출물은 결정립 성장을 억제하여 조직을 안정화함으로써 초소성 특성을 향상시켰다. 균질화처리 조건은 2차상의 크기과 분포에 큰 영향을 주어 2단계 균질화-공냉처리는 1단계 균질화-노냉처리보다 조대한 2차상의 제거와 미세석출물의 생성에 효과적이었다.
        4,000원
        182.
        1994.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        PAN계 탄소섬유 roving 및 fabric을 2170˚C에서 열처리 하였다. 열처리를 행하지 않은 탄소섬유 fabric과 행한 것을 사용하고, Autoclave를 이용하여, CFRP와 CFRP의 성형체를 제조하였다. 열처리를 행한 탄소섬유 roving과 행하지 않은것 및 두종류의 성형체의 분석을 통하여, 열처리에 따른 탄소섬유 및 탄소복합재의 물리적. 기계적 특성변화를 연구하였다. 열처리 후 성유의 단면을 주사전자현미경으로 관찰한 결과 탄소섬유의 직경이 6.8μ m에서 6.4μ m으로 감소하였으며, 열중량분석을 행한 결과 내산화성이 증진되었음을 알았다. 단섬유인장실험 결과 인장강도는 탄소섬유의 (3.11± 0.32)× 103 MPa 에서 열처리 섬유의 (1.87± 0.26)× 103MPa으로 감소되었으나, 탄성율은 탄소섬유의 (1.94± 0.06)× 105 MPa에서 열처리 섬유의 (2.02± 0.11)× 105MPa으로 증가하였다. 층간전단강도 측정 실험을 한 결과 그 값이 CFRP(148.8±1.6Mpa)가 CFRP(82.2±1.1Mpa)에 비하여 높음을 알 수 있었고, torch test 결과 CFRP는 층간분리 없이 매끄러운 삭마가 일어나나, GFRP는 층간분리가 발생함을 알 수 있었다.
        4,000원
        183.
        1994.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        All the activities and physical properties including surface tension' foaming power, foam stability, emulsifying power, dispersion effect of 3-(N, N-dimethyl N-alkylammonio)-2-hydroxyY-1-propane sulfonate (HSB)류와 3-CN-alkylamidopropyl-N,N-dimethylamm-onjo)-2-hydroxy-1-propane sulfonate (APSB) aquous solution were measured and critical micelle concentration was evaluated. Their cmc of hydroxy sulfobetaine derivatives evaluated by the surface tension method was 1.0×10-3~1.0×10-4 mol/l, and surface tension of the aquous solution was decreased to 27~38dyne/cm. The experimental results for foaming power, foam stability, emulsifying power in liquid paraffin showed a good surface active properties, especially, dispersion effect in ferric oxide exhibited some efficient surface active properties, and then it would be expected to application as detergent and dispersion agent.
        4,000원
        184.
        1994.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to review industrial application of amphoteric surfactants, new types of hydroxy sulfobetaine, 3-(N, N-dimethyl N-dimethyl-N-alkylammonio)-2-hydroxy-1-propane sulfonate and 3-(N, N-dimethyl N-acylammonio)-2-hydroxy-1-propane sulfonate were prepared by the reaction of quaternized sodium 1-chloro-2-hydroxy-3-propane sulfonate with N, N-dimethyl-N-alkylamine and N, N-dimethyl N-acylamido propylamine that have a straight chain radical of 12, 18 carbon atoms respectively in the presence of alkali catalyst. All the reaction products could be separated by means of column and thin layer chromatography, and the yields of all products ranged in 85~90%, the structure of them could be confirmed from IR and 1H-NMR spectra.
        4,000원
        185.
        1993.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 탄소/탄소복합재료의 마모특성에 대한 탄소섬유 길이의 영향을 고찰하였다. 매트릭스 precursor로 레졸형의 페놀수지와 강화재로 표면처리를 하지않은 PAN계 단섬유형 탄소섬유를 사용하여 액상함침법으로 1회의 고온열처리 공정과 4회의 탄화공정을 통하여 탄소/탄소복합재료를 제조하였다. Disk-on-disk형의 마모시험기를 통하여 상대 마찰재로 AISI 304 stainliss steel을 사용하여 0.6MPa(61 ×103Kg/m2)의 압력과 0.71m/sec의 미끄러짐 속도하에서 측정된 탄소/탄소복합재료의 마찰계수는 0.2-0.3이었다. 마찰계수에 대한 섬유의 길이의 영향은 크게 나타나지 않았지만, 마모 속도는 섬유의 길이가 증가함에 따라 증가하는 경향이 나타났다. 본 실헙 결과를 섬유 강화 플라스틱의 마모 모델을 적용하여 고찰하여 본 결과, 섬유의 길이가 증가함에 따라 탄소/탄소복합재료의 마모 속도가 증가되는 경향은 생성된느 마모조각의 크기가 커기기 때문에 나타난 현상으로 판단되었다.
        4,000원
        186.
        1991.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        8,000원
        187.
        1991.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        수분 장애시 목초 발아 특성을 검토하기 위하여, 삼투압 0, -5 bar 두 수준에서 tall fescue, orchardgrass, Kentucky bluegrass 및 alfalfa의 총 발아율, 발아속도계수를 구하였으며, 누적 발아율의 경시적인 변화를 logistic 및 Weibull 함수를 이용하여 비선형회귀 잔차에 의하여 함수간 비교를 하였고, 각 함수로부터 추정된 계수를 조사 하였던바 다음과 같은 결과를 얻었다. 1. 삼투압 수준 -5 bar
        4,000원
        188.
        1989.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        김치의 숙성과정 중의 물리적 특성을 측정하기 위하여 원료배추의 엽두께, 절임시의 두께 및 pH, total acidity, 염도 등의 변화를 연구하였다. 원료배추의 엽두께는 최외엽보다 내엽의 두께가 50% 감소되었고 절임의 경우에서는 외엽이 내엽보다 감소율이 낮았다. 배추조직의 절단력 측정에서는 절임으로 인하여 상대적인 절단력이 높았고 김치숙성이 되면서 증가하며 7일을 기준으로 감소하였다. Stress에서도 상대적 절단력과 같은 경향이나 숙성 후의 감소되는 점이 잘 나타나지 않았다. pH의 변화에 대한 상관식은 Y=0.23X+6.13이었고 젖산함량의 관계식은 Y=0.09X-0.01로서 매우 완만한 기울기이었으며 김치로서의 적정수준은 pH4.2, 젖산함량은 0.63의 수준이었고 기간은 7일이었다.
        4,000원
        189.
        1988.12 구독 인증기관 무료, 개인회원 유료
        고추의 16개(個) 도입계통(導入系統)에 대(對)해서 내건성(耐乾性)을 알기 위(爲)하여 발식(鉢植)한 고추를 단수처리(斷水處理)하고 일정기간후(一定期間後)에 엽(葉)의 WSD치(値)를 측정(測定)해서 내건성(耐乾性)을 평가(評價)하였으며 성숙엽(成熟葉)의 기공밀도(氣孔密度)를 조사(調査)하여 WSD치(値)와의 상관(相關)을 구(求)하였다. WSD치(値)로부터 내건성(耐乾性)이 강한 계통(系統)의 순위(順位)는 No.3446, C. chaconce, Gogoshari, 팔방(八房)이였다. 성숙엽(成熟葉)의 기공밀도(氣孔密度)와 WSD치(値)와의 상관(相關)(r=0.581)이 인정(認定)되었다.
        4,000원
        190.
        2019.03 KCI 등재 서비스 종료(열람 제한)
        Morphosyntactic and prosodic information is accessed by native speakers of North Gyeongsang Korean when interrogatives are interpreted. The present study investigates the interface between these structures. To do so, the study analyzes the syntactic and prosodic structures of the dialect’s yes/no and wh-questions, and then examines the rate of comprehension and acceptance of the two types of the interrogatives in a perception test. The prosodic structures in the test are modified by transplantation, the results of which allow us to find out the following. First, presented with the interrogatives whose syntactic and prosodic structures did not match, the native subjects of Gyeongsang Korean relied more on the prosodic structures than on the syntactic ones. Second, changes in prosodic structures had a strong influence on simple sentences, but relatively less so on complex sentences. These results lead to the conclusion that prosodic structures are the decisive factor in syntactic interpretations, and, accordingly, are intricately intertwined with the syntactic structures during the processing of interrogatives.
        191.
        2018.12 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 하수오를 이용하여 50% 에탄올 추출물과 에틸아세테이트 분획물을 제조하고, 추출물 및 분획물의 항산화, 세포 보호 및 항균 효능을 평가하여 기능성 소재로서의 가능성을 확인하였다. 또한, 하수오에 주요하게 존재하는 성분의 활성도 검증하였다. HPLC-DAD, LC-EIS-MS를 통해 분석한 결과, 하수오의 주성분은 2, 3, 5, 4'-tetrahydroxystilbene 2-O-β-D-glucoside (THSG)이었다. 페놀류 및 THSG 함량은 에틸아세테이트 분획물이 에탄올 추출물 보다 각각 11.1 및 3.0배 높게 나타났다. DPPH 자유 라디칼 및 Fe3+-EDTA/H2O2 시스템에서 생성된 ROS에 대한 소거 활성 평가에서, 에틸 아세테이트 분획물은 에탄올 추출물 보다 뛰어난 소거 활성을 나타냈다. 특히 ROS 소거 활성 평가에서 에틸 아세테이트 분획물과 THSG은 L-ascorbic acid와 동등한 소거 활성을 나타냈다. 이러한 결과를 바탕으로 수행된 광증감 반응으로 유도된 적혈구의 산화적 손상에 대한 세포 보호 활성은 에틸아세테이트 분획물, 에탄올 추출물, THSG 순서로 나타났으며, 모든 실험군이 양성 대조군으로 사용한 (+)-α-tocopherol보다 우수한 활성을 나타냄을 확인하였다. 항균 활성 평가는 S. aureus, E. coli, P. aeruginosa, C. albicans 균주를 대상으로, disc diffusion assay와 broth microdilution assay를 이용하여 수행하였다. 그 결과 추출물, 분획물 및 THSG 모두 모든 균주에 대해 항균 활성을 나타냈으며, 특히 그람 양성균인 S. aureus에 대해 methyl paraben보다 우수한 항균력을 나타냄을 확인하였다. 본 연구의 결과는 하수오가 항산화, 세포 보호 및 항균력에 관한 천연 소재로의 활용될 수 있는 가능성을 시사한다.
        192.
        2018.12 KCI 등재 서비스 종료(열람 제한)
        Drought is one of the natural disasters that slowly begin to accumulate over a long period. Although there are many kinds of drought indices, one single universally accepted definition does not currently exist, which makes it difficult to evaluate drought severity comprehensively and objectively. This paper describes the comparisons of satellite-based drought indices such as SPI (Standardized Precipitation Index), NDDI (Normalized Difference Drought Index), NMDI (Normalized Multi-band Drought Index), VHI (Vegetation Health Index) and SDCI (Scaled Drought Condition Index) to analyze agricultural drought in Korea. Through an experiment using the five drought indices, we found that VHI and the SPI2 calculated from 2-month accumulated precipitation were highly correlated and appropriate to express agricultural drought in South and North Korea. Also, the SPI2 and VHI showed close relationships with hydro-meteorological factors and vegetation production variables. For future work, it is necessary to develop a comprehensive drought index which can cover various aspects of drought including precipitation, evapotranspiration, soil moisture, and vegetation state.
        193.
        2018.10 서비스 종료(열람 제한)
        Background : Ribes fasciculatum var. chinense Maxim. has been traditionally used as febrifuge, diuretic and antidote against urushiol in Korea. This study described a metabolomics approach used to discriminate the genus Ribes from different sources. Methods and Results : Four different types of Ribes from Korea were analyzed by ultra-high-resolution mass spectrometry (UHPLC-HR-MS/MS) based metabolomics. Multivariate statistical method such as principal component analysis (PCA) were used to compare the derived patterns among the samples. The data set was subsequently applied to various metabolite selection methods for sophisticated classification with the optimal number of metabolites. The results showed variations in accuracy among the classification methods for the samples of different origins, especially for cultivation region. Conclusion : This proposed analytical method coupled with multivariate analysis is fast, accurate, and reliable for discriminating the origin of the genus Ribes samples and is a potential tool to standardize quality control in the genus Ribes related products.
        194.
        2018.10 서비스 종료(열람 제한)
        Background : Stevia rebaudiana (Asteraceae), a perennial plant, has been used as a low caloric sweetener and therapeutic agent for diabetes, hypertension, myocardial, and antimicrobial infections. It has been commonly used leaves and stems because of their high anti-oxidative potential. The present research was carried out to explore anti-oxidative and anti-melanogenic effects of aqueous extract of Stevia rebaudiana Bertoni flos in B16F10 cells. Methods and Results : Anti-oxidant activity of Stevia flos extract (SFE) was determined by using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assay, nitric oxide (NO) radical scavenging method, and reducing power method. The results showed that the total phenolic content of SFE was 63.154 ± 0.0002 ㎍·QE/100㎎ and the total flavonoid was 8.64 1 ± 0.002 ㎍·GAE/100㎎. SFE exhibited a big significant effect on NO radical scavenging activity (IC50: 179.6 ㎍/㎖) comparing with standard ascorbic acid (IC50: 368.6 ㎍/㎖), and showed concentration dependent DPPH radical scavenging activity (IC50: 131.8 ㎍/㎖). Anti-melanogenic effect of SFE was also examined with B16F10 melanocytes. The amount of melanin synthesis followed by α-melanocyte stimulating hormone on B16F10 cells were significantly reduced in the presence of SFE treatment (p < 0.05). SFE also suppressed the tyrosinase activity (p < 0.05) and α-glucosidase activity (p < 0.05). Conclusion : These results provide evidence Stevia rebaudiana flos has an antioxidant potency and can be used as an anti-melanogenic agent.
        195.
        2018.06 KCI 등재 서비스 종료(열람 제한)
        Background: Atractylodes japonica Koidz. and Atractylodes macrocephala Koidz. belong to the family (Asteraceae). Their rhizomes, called white Atractylodes rhizomes, are used in traditional medicine. To address some issues with their cultivation, we recently developed eight hybrid cultivars by interspecific hybridization of A. japonica and A. macrocephala. This study was conducted to screen the hybrid cultivars that have high amounts of active ingredients and yield ability. Methods and Results: Experiments were conducted using the eight hybrid cultivars and A. macrocephala (control cultivar) in the experimental field of the department of Herbal Crop Research located in Eumseong, South Korea. We investigated the growth characteristics of the aerial and underground parts. Among the cultivars, ‘Sanwon’ had the highest rhizome dry weight (53.8 g/plant), followed by ‘Dachul’ (50.0 g/plant). In addition, the content of atractylenolide I, II, III and total active ingredients were investigated using high-performance liquid chromatography. Compared with A. macrocephala, most of the inter-specific hybrid cultivars had a higher content of active ingredients and yield ability. Conclusions: Through study, we established the superior quality of Atractylodes inter-specific hybrid cultivars. In particularly, it was found that ‘Dachul’ may be grown as a superior cultivar, with high amount of active ingredients as well as yield ability.
        196.
        2018.05 서비스 종료(열람 제한)
        Background : Atractylodes japonica koidz (AJ) is a perennial herb that belongs to Atractylodes genus. The dried rhizome of AJ is known as ‘Baek-chul’. The ‘Baek-chul’ is used as important traditional medicine in north-east Asia. It is considered to be effective for the treatment of stomach disorder, virus, diuresis, inflammation, arthritis. AJ is heavily depend on import from china and only few studies have been carried out. In this study, we develop SSR marker to build a foundation of breeding, to analyze genetic diversity and to construct core collection. Methods and Results : AJ resources was collected from each different place. To find simple sequence repeat (SSR) marker, we sequenced genomic DNA of AJ resources using Illumina HiSeq 2000 System. As a result of next generation sequencing (NGS), we obtained putative SSR loci. From these SSR primers, 553 SSR primer sets were designed successfully and confirmed polymorphism by in silico analysis. Nucleotide motifs ranged from tri- to penta-. Among these, 48 primer were tested in 4 individuals by capillary electrophoresis. Finally, selected 28 SSR marker were showed clear band and polymorphism by Electrophoresis. Conclusion : In this study, we developed 28 polymorphic SSR marker using NGS, and it could be used for analyzing genetic diversity of A. japonica. These marker would be useful for breeding of new cultivar in the future.
        197.
        2018.05 서비스 종료(열람 제한)
        Background : Atractylodes japonica koidz. (AJ) and Atractylodes macrocephala koidz. (AM) belong to Atractylodes genus (Asteraceae) and their rhizomes are used as traditional medicine ‘Baek-chul’. The ‘Baek-chul’ is considered to be effective for the treatment of stomach disorder, virus, diuresis, inflammation, arthritis and Atractylenolide I, Atractylenolide II and Atractylenolide III are the major active ingredients of these. Previously, we developed 8 hybrid cultivars with disease resistance, high yielding ability and high active ingredients by interspecific hybridization between AJ and AM. In this study, growth characteristics of 8 hybrid cultivars were investigated in RDA experimental field. Methods and Results : Growth characteristics of 8 hybrid cultivars were investigated in RDA experimental field. Among these cultivars, ‘Sanwon’ had the highest fresh weight of rhizome (149.5 g/plant), followed by ‘Dachul’ (145.8 g/plant). Most of hybrid cultivars showed higher fresh weight than and AM (108.7 g/plant). In addition, active ingredients (Atractylenolide I, Atractylenolide Ⅱ and Atractylenolide Ⅲ) were investigated using HPLC. As a result, The sum of active ingredients were the highest in ‘Dachul’ (0.40 ㎎/g) that was 2 times higher than AM (0.22 ㎎/g). Conclusion : In this study, hybrid cultivars showed higher agronomic performance than AM. Particularly, ‘Dachul’ could be the superior cultivar with high atractylenolides as well as high yield ability.
        198.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        This research was conducted to evaluate methods of enhancing the waterlogging resistance of soybean plant. Thus, we applied seven types of plant growth regulators (PGRs) to soybean plants and exposed them to waterlogged conditions for a total of 14 days. To evaluate stress resistance, we monitored plant growth characteristics data such as height, chlorophyll content, and chlorophyll fluorescence for 28 days after the initial waterlogging (14 days under waterlogging conditions and 14 days after waterlogging). According to the results, plant height was significantly increased by gibberellin A4 (GA4) treatment compared to the control treatment and waterlogging-only treatment. However, we could not detect plant height owing to plant death when we applied abscisic acid (ABA). Except for GA4 and ABA treatments, plant heights slightly decreased in all treatments compared to the waterlogging-only treatment. The chlorophyll content and chlorophyll fluorescence showed a similar tendency among PGR treatments. The chlorophyll content and chlorophyll fluorescence were significantly increased by ethephon and kinetin treatments 28 days after waterlogging compared to the waterlogging-only treatment. Consequently, kinetin and ethephon treatments induced more resistant phenotypes in soybean plants during or after exposure to waterlogging conditions.
        199.
        2017.09 KCI 등재 서비스 종료(열람 제한)
        Kimchi cabbage (known as Chinese cabbage) is major vegetable in Korea. An inbred line of ‘Wonkyo20038ho’, was developed by the National Institute of Horticultural & Herbal Science, RDA in Republic of Korea. The microspore culture was carried out using ‘Chunhuigohangwang’ which was introduced from China in 2002. Among 3 DH inbred lines, ‘Wonkyo20038ho’ inbred line was finally selected after field exhibition in 2009. The horticultural traits of ‘Wonkyo20038ho’ inbred line; half-open head, white inner leaf colour, and dark green outer leaf colour. The average (for four years) head weight was 2025.3g, and head width and height were 15.8cm and 32.4cm, respectively. Head shape was narrow elliptic and degree of overlapping leaf was medium. Numbers of outer and internal leaves were 14.1 and 49.8, respectively. Harvest maturity was mid-late maturing type and average of seed yield for five years was 926 seeds. In addition, ‘Wonkyo20038ho’ inbred line is suitable for salad in that it possessed few trichome and narrow elliptic head shape.
        200.
        2017.09 서비스 종료(열람 제한)
        Soundless Chemical Demolition Agent (SCDA) has been spotlighted for demolition of concrete structure or rock near or in urban areas and historical places since it does not produce dust or rock fragmentations compared to explosive and gas pressure blasting methods. However, there is no guideline or design code for the demolition of existing structures using SCDA. In this study, numerical analysis using ABAQUS is conducted in order to find a minimum required pressure for the initiation of crack in concrete body with SCDA and obtained results in this study could be a basic data for design of hole spacing for the demolition of the structures using SCDAs.