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        검색결과 146

        81.
        2009.06 구독 인증기관 무료, 개인회원 유료
        Periodontal ligament (PDL) tissue is a connective tissue that is interposed between the roots of the teeth and the inner wall of the alveolar bone socket. PDL is always exposed to physiologic mechanical force such as masticatory force and PDL cells play important roles during orthodontic tooth movement by synthesizing and secreting different mediators involved in bone remodeling. The Wnt/β-catenin signaling pathway was recently shown to play a significant role in the control of bone formation. In the present study, we applied cyclic tensile stress of 20% elongation to cultured human PDL cells and assessed its impact after six days upon components of the Wnt/β-catenin signaling pathway. RTPCR analysis showed that Wnt1a, Wnt3a, Wnt10b and the Wnt receptor LRP5 were down-regulated, whereas the Wnt inhibitor DKK1 was up-regulated in response to these stress conditions. In contrast, little change was detected in the mRNA expression of Wnt5a, Wnt7b, Fz1, and LRP6. By western blotting we found decreased expression of the β-catenin and p-GSK-3β proteins. Our results thus show that mechanical stress suppresses the canonical Wnt/β-catenin signaling pathway in PDL cells.
        4,000원
        84.
        2008.09 구독 인증기관 무료, 개인회원 유료
        수평 배향 액정 모드는 양의 유전율 이방성과 음의 유전융 이방성 액정을 사용한 프린지 필드 스위칭과 양의 유전율 이방성 액정을 사용한 인플래인 스위칭 모드가 대표적이다 . 이 대표적인 세 구동 방식의 화질 특성을 비교하기 위하여 각각의 최척화된 위상지연 값 조건하에서 밝기, 명암대비율과 색 특성을 조사하였다. 그 결과 양액정과 음액정을 사용한 프린지 필드 스위칭 모드가 밝기와 명암대비율 면에 있어서 인플래인 스위칭 모드보다 우수한 특성을 보인다. 또한 양액정을 사용한 프린지 필드 스위 칭 모드는 시야각 방향에서 적은 색 변이 특성을 보인다.
        4,000원
        85.
        2008.06 구독 인증기관 무료, 개인회원 유료
        Color is one of the most important attributes determining the purchase of food products by consumers. Therefore, the purpose of this study was to identify consumer color preferences for songpyun, a traditional Korean rice cake, by a consumer acceptance test and using coated Pantone color chips. Color evaluation tools for the study were developed accordingly. From the results, the songpyun sample designated as product E was given the highest color acceptability score, and was ‘slightly liked’ (p<0.05). The color of product E was ‘very pale red-purple’. All the evaluated pink-color songpyun products were based on this red-purple hue, however, they had differences in tone. The consumer panel favored a pale tone over a bright tone. The color concept for traditional songpyun within the pink color category was identified as ‘very pale red-purple’, using coated Pantone color chips. This result for the conceptual color preference was consistent with that of the consumer color acceptance test. Thus, color chips could be an effective tool when applied for color standardization in traditional foods production. From the overall results, it seems consumers are perceiving color trends and are willing to adapt to such changes in food applications.
        4,000원
        87.
        2007.12 구독 인증기관 무료, 개인회원 유료
        Field sequential 액정 디스플레이(FSLCD)는 컬러필터를 사용하지 않아 높은 투과율 특성을 보이고 광 원으로 LED를 사용함으로써 색재현성이 매우 우수하다. 하지만 FSLCD(60Hz 구동)를 실현하기 위해서는 액정의 응답속도가 5ms이하로 고속응답 특성을 보여야 한다. 따라서 본 논문에서는 고속응답 ECB(electrically controlled birefringence) 셀의 최적 구조를 연구하여 5ms 이하의 응답시간을 얻었다. 그리고 ECB 모드에서 높은 구동전압과 시야각을 개선하기 위해 필름 보상을 연구하였다. 판상형 액정필름(discotic film)과 TAC(triacetyl cellulose) 필름의 위상차 값을 최적화함으로써 구동전압을 5V로 낮추고 상하좌우에서 160° 이상(CR>10:1)의 시야각을 실현하였다.
        4,000원
        92.
        2005.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 논문에서 사고로 누출된 삼중수소에 의한 농작물 오염평가 모델을 제시한다. 본 논문에서 제시된 모델은 동적격실모델로써 작물의 성장 방정식을 도입한 것이 특징이며, 이로부터 삼중수소 피폭시 작물의 성장단계에 따른 오염 정도를 예측할 수 있다. 시스템은 크게 대기, 토양, 작물격실로 구성되며, 격실의 삼중수소 농도 변화는 비선형 상미분방정식으로 표현되므로 시간에 따른 각 격실의 삼중수소 농도가 계산된다. 모델의 검증을 위해 배추 및 무에 대한 삼중수소 피폭 실험을 수행하였다. 생육단계별 오염 효과를 조사하기 위해 각기 다른 생육단계에 있는 배추와 무를 독립적으로 HTO 증기에 노출시켰으며, 피폭 후 오염된 작물의 tissue free water tritium(TFWT) 및 organically bound tritium(OBT) 농도를 측정하였다. 측정된 작물 부위별 삼중수소 농도 데이터와 모델 예측 값은 대체로 잘 일치하였다.
        4,000원
        94.
        1994.12 구독 인증기관·개인회원 무료
        95.
        2019.12 KCI 등재 서비스 종료(열람 제한)
        This study investigated a suitable method that could be applied for Asian chain fern [Woodwardia japonica (L. f.) Sm.] to propagate gametophytes and promote sporophyte formation. The gametophytes used in all experiments were obtained from germinated spores in vitro and were subcultured at 8-week intervals. The most appropriate media for gametophyte propagation was identified by culturing 300 ㎎ of gametophyte in Murashige and Skoog (MS) basal medium (1/8, 1/4, 1/2, 1, 2), and Knop medium for 8 weeks. As a result, fresh weight of the gametophyte was increased by 56.7-fold on MS medium. Moreover, antheridium formation as well as gametophyte growth was improved on MS medium, especially. To improve the sporophyte formation ex vitro, 1.0 g of gametophyte was ground with distilled water and spread on eight combinations onto four different culture mediums, such as bed soil, peat moss, perlite and decomposed granite. Then generation and growth of sporophytes were investigated after cultivation for 10 weeks. As a result of this experiment, peat moss had a promotive effect of sporophyte formation at single-use and mixed culture soils. In particular, a mixture of bed soil, peat moss and perlite in a 1:1:1 ratio (v/v/v) led to the accelerated formation (782.5 ea/pot) and the frond growth of sporophytes. This included increases in length and width of fronds. However, promotive effect of gametophyte growth and sporophyte formation was not found at single-use and treatment with high ratio of bed soil.
        96.
        2018.10 KCI 등재 서비스 종료(열람 제한)
        Fruit trees are a key part of agriculture in rural areas and have recently been a part of ecotourism or agrotourism. This study analyzes user segmentation based on user motivation to determine characteristics of potential customers in fruit tree farms, and thereby develop fruit tree experience and educational programs. We conducted a survey of 253 potential customers of fruit tree experience programs in September 2017. Data were evaluated using factor and cluster analyses. The results of the cluster analysis identified four distinct segments based on potential customers' motivations, that is, activity-oriented, learning-oriented, leisure-oriented, and purchase-oriented. These clusters showed that significant differences in the preference of potential customers exist. Different markets were segmented based on the benefits sought by users. The segments’ characteristics were identified and activities relevant to each segment were proposed for rural tourism. Lastly, this study suggests directions for development of fruit tree farm experience and educational programs.
        97.
        2016.12 KCI 등재 서비스 종료(열람 제한)
        The purpose of this study was to investigate the improvement of growth in Israeli carp (Cyprinus carpio), and the cross experiment was carried out with two strains of Israeli carp. Four combinations of Israeli carp from Jeonbuk fisheries farm and Songpu mirror carp from Heilong Jiang, China (KK; Jeonbuk ♀ × Jeonbuk ♂, KC; Jeonbuk ♀ × China ♂, CC; China ♀ × China ♂ and CK; China ♀ × Jeonbuk ♂) were developed and reared. Body length, body weight and condition factor were determined at 20, 40, 60 and 170 days post-hatch (DPH). The results showed that there were differences in growth rate of the four groups. Body length of four groups were CK > CC > KC > KK and body weight were CC > CK > KC > KK at 170 DPH. The growth perfomance of four groups were statistically significant difference (P<0.05). During the rearing, CC group had longer length and higher weight at 170 DPH compared to other three groups and also condition factor was highest in the CC group, but there was no significant difference in a survival rate. These results indicated that the growth performance mainly depended upon brooder combination but survival rate could not significantly affect brooder.
        98.
        2016.10 서비스 종료(열람 제한)
        Background : Agrimonia pilosa (A. pilosa) Ledebour has been registered in The Korean Herbal Pharmacopeia (KHP). In the recent study, A. Coreana showed antioxidant and anti-inflammatory effect. However, Studies of components in Agrimonia coreana (A. Coreana) Nakai was not much. So, we compared A. pilosa and A. coreana by High performance liquid chromatography (HPLC). we perfomed Thin layer chlromatography (TLC) including the anatomical characteristics by using microscope. Methods and Results : The anatomical characteristics of A. pilosa were similar to them of A. coreana. But, fascicular fivers of A. Coreana was broader than it of A. pilosa. TLC were performed to identify the Rutin and Apigenin-7-glucuronide compound. In the extract of Agrimoniae Herba, they were identified on the spot of Rf 0.2, 0.4 in Ethyl acetate - Formic acid – Water (8 : 1 : 1). The Rutin and Apigenin-7-glucuronide were analysed by HPLC/UV with Thermo Column (5 μm, 4.6 × 250 mm, C18), the column temperature at 40 ℃ and a diode-array detector (DAD) seted at 255 nm and 338 nm. The mobile phase was composed of water and acetonitrile containing 0.1% formic acid with the flow rate 1 mL/min. All compounds showed good linearity (R2>0.999) within test ranges. Agrimoniae herba was extrated by four kinds of extraction methods: MeOH, 50% MeOH, EtOH and water. The highest extraction rate occurred, when it was treated with 50% Methanol for refluxing extraction (60min). Content of Rutin was found to be 0.07±0.00 mg/g in A. pilosa and 0.02±0.00 mg/g in A. coreana. Content of Apigenin-7-glucuronide was found to be 0.12±0.00 mg/g in A. pilosa and 0.11±0.00 mg/g in A. coreana. Conclusion : The anatomical characteristics of A. pilosa were similar to them of A. coreana. Contents of Rutin and Apigenin-7-glucuronide in A. pilosa was higher than them in A. coreana slightly. But there were observed the similar patterns of Agrimonia pilosa Ledebour and Agrimonia coreana Nakai on the finger print anelysis.
        99.
        2016.10 서비스 종료(열람 제한)
        Background : ROS produced by oxidative stress damaged endothelial cells, and cause a variety of vascular complications. In diabetic hyperglycemia state, ROS increase. The polyol pathway occur in diabetic complications, the excess glucose is absorbed into the polyol pathway when aldose reductase increased, NADPH changes it to sorbitol. Glutathione (GSH) removes ROS. GSH level is reduced by glutathione reductase, using NADPH as an electron donor. Activation of the polyol pathway decrease NADPH, and GSH also reduced. As a result, ROS is increased. In diabetic hyperglycemia state, Glycolysis increases. Effects of increased glycolysis, protein kinase C (PKC) is increased. NAD(P)H oxidase, stimulated by PKC-dependent pathway, increases ROS in the cell. In this study, we measured the ROS scavenging activity of 5 natural products (Lycii fructus, Astragalus membranaceus, Cassia Tora, Polygonatum odoratum, Rubus Coreanus), to confirm the efficacy as diabetic antioxidants. Methods and Results : We extracted 5 natural product by distilled water and ethanol. DPPH radical scavenging activity was significantly higher in Lycii fructus, Rubus coreanus. ABTS radical scavenging activity was better Rubus coreanus, Lycii fructus, Cassia Tora. In addition to, Rubus coreanus, Cassia Tora, Lycii fructus was comparatively higher reducing power activity than other natural products. And total phenolic and flavonoid contents were much higher in Rubus coreanus compared with other extracts. Conclusion : These results suggest that Lycii fructus, Rubus coreanus can be applied as diabetic antioxidant that prevent vascular complications caused by ROS.
        100.
        2016.06 KCI 등재 서비스 종료(열람 제한)
        This study was carried out to develop an effective seed propagation method for Thalictrum rochebrunianum var. grandisepalum (H. Lev.) Nakai by analyzing seed dormancy types and germination characteristics. Seeds were collected between September to October at Gangwon province, and well-selected seeds were used while being dry-stored at 4±1℃. The seed size ranged 4.52 × 1.58 ㎜ and the weight of thousand seeds were 1,603.5 ± 0.02 ㎎. The moisture content was 7.2%. Seeds were achene type, and morphology characters showed an elliptical shape and rough texture, and light brown in color. Moist-chilling treatment was conducted for dormancy breaking because the seeds had an undeveloped embryo of liner type. The embryo had developed during a moist-chilling period, constantly, and fully developed in 10 weeks. Consequently, it seemed to be non-deep complex or intermediate complex type of morphophysiological dormancy, and embryo dormancy was broken by wet-chilling for 10 weeks. After 10 weeks of wet-chilling treatment, seed germination began. Germination percentage was higher in dark condition raher than light condition and recorded the maximum at 25℃ in the dark (16.3%). A pre-soaking treatment with a combined plant growth hormones promoted germination and shortened T50. Specifically, seed germination of 84.5% was achieved by pre-soaking of seeds with a combined solution of 500 ㎎/L GA3 and 10 ㎎/L kinetin for 24 h after a wet-chilling treatment for 10 weeks. Thus the effect of plant growth hormones coupled with chilling temperature on seed breaking dormancy provide asubsequent growth of seedlings for successful plantation.
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