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        검색결과 1,315

        1.
        2024.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated the microstructure and piezoelectric properties of 0.96(K0.456Na0.536)Nb0.95Sb0.05-0.04 Bi0.5(Na0.82K0.18)0.5ZrO3 (KNNS-BNKZ) ceramics based on one-step and two-step sintering processes. One-step sintering led to significant abnormal grain (AG) growth at temperatures above 1,085 °C. With increasing sintering temperature, piezoelectric and dielectric properties were enhanced, resulting in a high d33 = 506 pC/N for one-step specimen sintered at 1,100 °C (one-step 1,100 °C specimen). However, for one-step 1,115 °C specimen, a slight decrease in d33 was observed, emphasizing the importance of a high tetragonal (T) phase fraction for superior piezoelectric properties. Achieving a relative density above 84 % for samples sintered by the one-step sintering process was challenging. Conversely, two-step sintering significantly improved the relative density of KNNS-BNKZ ceramics up to 96 %, attributed to the control of AG nucleation in the first step and grain growth rate control in the second step. The quantity of AG nucleation was affected by the duration of the first step, determining the final microstructure. Despite having a lower T phase fraction than that of the one-step 1,100 °C specimen, the two-step specimen exhibited higher piezoelectric coefficients (d33 = 574 pC/N and kp = 0.5) than those of the one-step 1,100 °C specimen due to its higher relative density. Performance evaluation of magnetoelectric composite devices composed of one-step and twostep specimens showed that despite having a higher g33, the magnetoelectric composite with the one-step 1,100 °C specimen exhibited the lowest magnetoelectric voltage coefficient, due to its lowest kp. This study highlights the essential role of phase fraction and relative density in enhancing the performance of piezoelectric materials and devices, showcasing the effectiveness of the two-step sintering process for controlling the microstructure of ceramic materials containing volatile elements.
        4,000원
        2.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research aimed to examine the effects of grapefruit seed extract (GSE) at various concentrations on the microbial safety and physicochemical characteristics of onion puree (0.01~0.1%). The onion puree was kept at 4℃ for 14 days. The results of the study indicated that the addition of GSE did not cause any significant changes in the sample’s brix degree and viscosity in onion puree (p<0.05). However, as the concentration of GSE increased, the pH level decreased. On the other hand, as GSE was added, the lightness of the onion puree increased, while the redness and yellowness decreased. Compared to pure onion puree, the GSE-incorporated onion puree had higher levels of total flavonoid and total polyphenol content, indicating that it helps to maintain antioxidant activities. Based on the microbial safety test, aerobic bacteria, yeast, and mold were absent until day 14 of storage. In conclusion, the study suggests that the addition of GSE to onion puree increases its antioxidant activity and shelf-life.
        4,200원
        3.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated quality characteristics and functionality of rose sparkling wine that were manufactured by secondary fermentation after inoculation of yeast strains. The pH of the samples ranged from 3.96 to 4.05 and total acidity ranged from 0.23 to 0.32%. The alcohol contents of wines ranged from 6.4 to 6.6% and the CO2 pressure ranged from 2.0 to 2.6 bar. The brightness of rose wines ranged from 84.72 to 87.36, the redness from 9.28 to 14.15, and the yellowness from 9.50 to 19.20. The hue value of wines ranged from 1.137 to 1.513 and color intensity ranged from 0.724 to 0.882. Aroma analysis identified 14 alcohols, 22 esters, 4 ketones, 4 acids, and 17 miscellaneous compounds. The total tannin contents and total polyphenol contents of wines were 11.28~12.43 mg% and 24.79~28.20 mg%, respectively. The DPPH radical scavenging activity of wines ranged 63.33 to 67.89% and the ABTS radical scavenging activity of wines 82.16~86.06%. The results of this study provide a basis for establishing the brewing process of rose sparkling wines yeast strains.
        4,200원
        4.
        2023.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To develop a functional probiotic that inhibits gingipain, a major virulence factor of Porphyromonas gingivlais (P. gingivalis), we screened over 30 probiotic strains for their ability to inhibit gingipian activity. We investigated the inhibition of expression of gingipain genes kgp, rgpA, and rgpB as well as gingipain activity, using freeze dried cell-free supernatants of Weisiella cibaria SPM402 (WC402) and Lactobacillus paracasei SMP412 (LP412), both of which demonstrated antibacterial activity against P. gingivalis. Thus, it was verified that kgp expression was reduced by approximately 0.71±0.02 folds and rgpB expression was reduced by approximately 0.71±0.14 folds at a concentration of WC402 10 mg/mL. Meanwhile, at the same concentration of 10 mg/mL of LP412, kgp expression was reduced by approximately 0.19±0.08 folds, rgpA expression was reduced by approximately 0.09±0.02 folds, and rgpB expression was reduced by approximately 0.24±0.03 folds. At a concentration of 10 mg/mL, Kgp activity was inhibited by approximately 78.65±3.58% (cell associated gingipain, CAG), 82.45±1.22% (cell-free gingipain, CFG) by WC402 and 80.71±2.11% (CAG), and 85.81±0.05% (CFG) by LP412 respectively. Rgp activity was also effectively inhibited by approximately 78.6±1.01% (CAG), 86.78±0.47% (CFG) and 82.93±1.26% (CAG), 88.81±0.36% (CFG) by WC402 and LP412 respectively. Based on these results, W. cibaria SPM402 and L. paracasei SPM412 can be regarded as functional probiotics with the ability to inhibit gingipain activity and exhibit antibacterial effects against P. gingivalis.
        4,000원
        11.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hesperetin은 Hesperidin에서 유도되는 강한 항산화 기능의 플라보노이드 비당체이다. 본 연구 에서는 Hesperetin과 이의 Cyclodextrin 포접 복합체에 대하여 항산화, 항염증 및 항균 활성을 비교하였다. Hesperetin은 Hesperidin에 효소처리하여 제조되었으며, Hesperetin/Cyclodextrin 포접체는 용매 증류법에 의해 β-Cyclodextrin 및 Hydroxypropyl-β-Cyclodextrin을 사용하여 제조되었다. Hesperetin에 비해 Hesperetin/Hydroxypropyl-β-Cyclodextrin 포접체의 용해도는 93.5배 증가하였고, Hesperetin/β -Cyclodextrin 포접체의 용해도는 22.5배 증가하였다. 항산화 분석에서 Hydroxypropyl-β-Cyclodextrin 포접체는 Hesperetin과 유사한 라디칼 소거 활성능을 보인 반면, β-Cyclodextrin 포접체는 Hesperetin 보 다 약간 낮은 활성을 나타내었다. RAW 264.7 세포에 대한 세포독성은 Hydroxypropyl-β-Cyclodextrin 포접체, β-Cyclodextrin 포접체, Hesperetin의 순으로 세포독성이 낮았다. Hesperetin과 Cyclodextrin 포 접체는 모두 세포내 산화질소(NO), 종양괴사인자-α(TNF-α) 및 인터루킨-6(IL-6)과 같은 염증 매개체 를 감소시켰다. Hesperetin 및 Hydroxypropyl-β-Cyclodextrin 포접체는 상대적으로 β-Cyclodextrin 포접체 보다 더 효과적이었다. 피부 유해성 세균인 황색 포도상구균과 녹농균에 대해 억제 효과를 시험한 결과, 황색 포도상구균에 대해서는 Hesperetin = Hydroxypropyl-β-Cyclodextrin 포접체 > β -Cyclodextrin 포접체의 순서로 항균 효과를 나타내었으나, 녹농균에 대해서는 뚜렷한 억제효과를 나타내 지 않았다. 결론적으로, Hesperidin의 비당체 형태인 Hesperetin과 이의 Cyclodextrin 포접체는 다양한 생 물학적 활성을 보여주었으며, 용해도가 높은 Hydroxypropyl-β-Cyclodextrin 포접체가 β-Cyclodextrin 포접체에 비해 상대적으로 더 높은 활성을 나타내었다.
        4,500원
        12.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate optimal conditions for cutting propagation of the strawberry cultivar “Sulhyang” through the collection methods of cuttings (runners tips), leaf number of cuttings, and cutting time. Cuttings were collected from the mother plant in the nursery bed (MP) and plants after fruit harvest (HP); the leaf number of cuttings was 0, 1, and 2, and the cutting time was at one-week intervals from June 4 to July 9. The survival rates for MP and HP cuttings were notably high, reaching 99.5% and 98.7%, respectively, but no significant difference was found. The number of roots were higher in MP cuttings, and there was no significant difference in crown and leaf growth. The fruit yields were 419.2 and 428.4 g, for MP and HP cuttings, respectively. The survival rates according to leaf number of cuttings were 98.1% and 98.3% for 1 and 2 remaining leaves, respectively, and remarkably lower at 25.3% for no remaining leaves. The root numbers were 26.0 and 26.3 for 1 and 2 remaining leaves, respectively, compared with 23.5 for no remaining leaves, with no significant differences in crown and leaf growth. The fruit yields were 424.4 and 421.5 g for 1 and 2 remaining leaves, respectively, and 396.7 g for no remaining leaves. The survival rates according to cutting time was over 97.2% in all cutting time without any difference in each treatment. The root, shoot, and crown of the nursery plant before planting showed the best growth in the cuttings on June 4 and 11, resulting in the highest fruit yields of 433.3 and 426.4 g, respectively, with the lowest yields at 384.5 g for cutting time on July 9. Both MP and HP materials proved suitable for strawberry cuttings. The optimal leaf number for cuttings was at least 1, and the optimal cutting time in Gyeongnam area was evaluated as around June 4-11.
        4,200원
        13.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examines the characteristics of berries from secondary bearing shoots of ‘Scintilla’ southern highbush blueberry, grown hydroponically in the Jinju, Gimhae, and Uiryeong regions of Gyeongnam Province. Typically, ‘Scintilla’ forms flower buds at the tips of regular bearing shoots during the previous season, yielding berries in the current season. However, under heated cultivation, we observed a proliferation of secondary bearing shoots that produce berries in the same growing season. Flowering and harvesting on secondary bearing shoots were delayed by 52 and 36 days, respectively, compared to regular bearing shoots. However, these shoots exhibited a 54% increase in diameter and a 10% increase in length. We found no significant difference in berry size and soluble solid content between the two types of shoots. Notably, berries from the secondary bearing shoots had higher potassium and lower calcium and magnesium concentrations. We conclude that berries from secondary bearing shoots could be marketable, provided the bushes are healthy. These findings provide valuable insights for optimizing cultural practices to improve the yield and quality of blueberries under specific environmental conditions.
        4,000원
        14.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        강황 분말의 첨가가 마요네즈의 품질특성, 항산화활성 및 산화안정성에 미치는 영향에 대해 평가하였다. 들기름으로 제조된 마요네즈에 강황 분말을 0.5%, 1%, 2%, 3% 농도로 첨가하여 4°C에서 12주 동안 저장하였으며, 강황 분말 무첨가구와 비교하였다. 강황 분말 첨가량이 많아짐에 따라 들기름 마요네즈의 L* (명도) 값은 유의적으로 감소하였고, a* (적색도)는 모든 실험구에서 negative (-)값이었으며, b* (황색도)값은 유의적으로 증가되는 경향이었다(p<0.05). 강황 분말 첨가량이 많아짐에 따라 총 페놀 함량 및 항산화 활성이 유의적으로 증가하였다(p<0.05). 마요네즈를 저장하는 동안 과산화물가는 유의적으로 증가하였으나, 강황 분말 첨가 시료에서는 유의적으로 낮았다(p<0.05). 마요네즈의 유화안정성은 저장 초기에 비해 저장 기간이 길어질수록 감소되는 경향이었으나, 0.5%의 강황 분말 첨가구는 무첨가구에 비해 유의적으로 높은 유화안정성을 보였으며, 1%의 강황 분말 첨가구는 무첨가구와 유의차를 보이지 않았다. 점도는 저장 기간이 경과됨에 따라 감소되었으나, 무첨가구에 비해 1% 이상의 강황 분말 첨가구에서 유의적으로 높았다. 들기름 마요네즈에 강황 분말 첨가 시 항산화 활성 증대 및 과산화물의 생성 억제에 효과적이었으며, 특히 0.5~1% 첨가시 마요네즈의 유화안정성 및 점도 개선에 도움이 될 것으로 판단된다.
        4,000원
        16.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Physicochemical properties and storage stability of plant-based alternative meat prepared with low-fat soybean powder (LPAM) treated by supercritical-CO2 and those of full-fat soybean powder (FPAM) were compared. Ash and crude protein contents were higher in LPAM than in FRAM. Water absorption capacity and oil absorption capacity were significantly higher in LPAM than in FPAM. Water binding capacity was higher in LPAM than in FPAM during a 20 days storage period at 5℃ and pH was significantly lower in LPAM than in FPAM after a 5~10 days storage period. Hardness, gumminess and chewiness significantly increased with the increase in the storage period, and the three were significantly higher in LPAM than in FPAM after 10 days and 20 days of storage. The acid value showed no remarkable difference according to the storage period in LPAM; however, it was significantly higher in FPAM than in LPAM after 20 days of storage. The peroxide value and TBA value were significantly increased according to the storage period, and were significantly lower iin LPAM than in FPAM during all the storage periods. Therefore, the use of low-fat soybean powder may be effective in improving oxidative stability during storage in the production of plant-based alternative meat.
        4,000원
        17.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study would analyze a survey conducted with 609 workers to use the results as materials for the settlement of safety culture for the characteristics of the establishment by assessing the status of the workers’ exposure to harmful risks and the impact on safety culture to present the following conclusions. This study has significance in that it found that exposure to harmful/dangerous factors in the establishment and the workers’ experiences of occupational accidents affect their perception of safety culture and that in particular, ‘worker safety priority’ of the safety cultural factors was an important factor, and it is judged that continuous studies are necessary so that the perceptions of safety culture will spread in the establishment.
        4,000원
        18.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we aimed to compare the mycelial growth of Pleurotus ostreatus after medium supplementation with various amino acids at different concentrations to select the optimal medium nutrient composition for mycelial growth. The mycelial growth of P. ostreatus was investigated after adding four amino acids (tryptophan, threonine, methionine, and lysine) at 0.5% or 1% to the medium.The rate of P. ostreatus mycelial growthwas faster in the potato dextrose agar (PDA) medium supplemented with threonine at 0.5% or 1% than that of the control, whereas it was inhibited by tryptophan treatment. Supplementation of sawdust mediumwith all amino acids, except tryptophan, at 0.5% did not alter the mycelial growth, compared to the controls. However, addition of any amino acid to sawdust medium at a higher concentration (1%) inhibited the mycelial growth. The laccase acitivity of P. ostreatus mycelium cultured in PDA medium was the highest when threonine was added, and the lowest when tryptophane was added, consistent with the results of the mycelial growth. Therefore, the addition of threonine, methionine, or lysine to PDA medium at a concentration of 0.5-1%was effective for increasing the mycelial growth of P. ostreatus; however, it inhibited mycelial growth insawdust medium, suggesting that the effects of amino acids dependedon the medium nutrient composition.
        4,000원
        19.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        콘크리트 구조물은 시간이 경과함에 따라 Steel Re-bar 부식 등이 원인이 되어 주요 구조부재의 내력이 저하된다. 이 를 방지하기 위해 아연도금, 에폭시 코팅, 피복두께 증가 등의 방법이 사용되지만 근본적인 문제가 해결되지 않는다. 최근 들어 Steel Re-bar를 대체할 복합섬유에 대한 연구가 활발히 수행된다. CFRP Re-bar는 경량이며 고강도이고 내식성이 우수하다. Steel Re-bar의 임계온도는 538℃인 반면 CFRP Re-bar의 임계온도는 250℃로 화재에 취약하다. 따라서 건설현장에 적용하기 위한 내 화피복 방안이 필요하다. 본 연구에서는 콘크리트 피복두께(40, 60, 80mm), SFRM(0, 15, 30mm)두께를 변수로 CFRP Re-bar가 배 근된 표준화재 3시간 노출된 콘크리트 기둥 단면의 온도분포를 확인하고, 온도상승에 따른 소재 강도 감소를 고려하여 P-M상관 도를 도출하였다. 이를 통해 건설현장에 CFRP Re-bar를 사용하기 위한 내화피복 두께를 제안하고자 한다. 1시간 내화성능을 만 족하기 위해 콘크리트 피복두께가 60mm 필요하며, 2시간은 80mm가 필요하다. SFRM 15mm를 도포하면 400×400 단면의 경우 2 시간, 600×600과 800×800 단면의 경우 3시간 내화성능을 만족한다.
        4,300원
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