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        검색결과 59

        1.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The emergence of ferrous-medium entropy alloys (FeMEAs) with excellent tensile properties represents a potential direction for designing alloys based on metastable engineering. In this study, an FeMEA is successfully fabricated using laser powder bed fusion (LPBF), a metal additive manufacturing technology. Tensile tests are conducted on the LPBF-processed FeMEA at room temperature and cryogenic temperatures (77 K). At 77 K, the LPBF-processed FeMEA exhibits high yield strength and excellent ultimate tensile strength through active deformation-induced martensitic transformation. Furthermore, due to the low stability of the face-centered cubic (FCC) phase of the LPBFprocessed FeMEA based on nano-scale solute heterogeneity, stress-induced martensitic transformation occurs, accompanied by the appearance of a yield point phenomenon during cryogenic tensile deformation. This study elucidates the origin of the yield point phenomenon and deformation behavior of the FeMEA at 77 K.
        4,000원
        2.
        2023.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to determine the appropriate seeding dates by verifying the difference in winter survival and productivity of alfalfa according to fall sowing dates in the central area of South Korea. The experiment was conducted for 2 years (2020 and 2021) at the field in the Department of Animal Resources Development, NIAS located in Cheonan. Sowing dates started from September 18 to November 8 with 10 days of intervals during 2020 and 2021; SO1 (September 18), SO2 (September 28), SO3 (October 8), SO4 (October 18), SO5 (October 28), and SO6 (November 8). After sowing, the winter survival rate was measured in the spring of the following year, and the dry matter yield was measured by harvesting at 10% flowering and harvesting five times a year. SO6 failed to winter survival, and SO5 also had a lower winter survival rate than SO1~4 (p<0.05). The average annual dry matter yield of alfalfa linearly decreased with delaying sowing dates (p<0.05). The feed value did not differ in the same year by delaying the sowing date in the same year. These results suggest that sowing date should be started before October 18 to increase winter survival and productivity of alfalfa in the central area of South Korea.
        4,000원
        3.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Repetitive or excessive exposure to ultraviolet (UV) radiation causes oxidative stress-mediated skin photoaging through the overproduction of reactive oxygen species. Actinidia polygama is known as a medical plant used in oriental medicine for treating several diseases such as abdominal pain, stroke and rheumatoid arthritis. Recently, it was reported that A. polygama extract had anti-wrinkle and skin hydrating properties in ultraviolet B (UVB)-exposed hairless mice. However, the molecular biological mechanism of this extract on alleviating skin photoaging is still unknown. Therefore, we investigated the anti-photoaging effects of PB203, which is the powder of A. polygama extract, in the in vivo and in vitro photoaging models. First, PB203 showed 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities due to the presence of anti-oxidant components including flavonoids and polyphenols. In UVB-irradiated hairless mice, oral administration of PB203 (100 mg/ kg) significantly improved wrinkle formation, skin dehydration, elasticity and skin barrier function by decreasing the levels of matrix metalloproteinases (MMPs) and increasing those of collagen I, filaggrin, involucrin and loricrin. Especially, the reduced production of p-p38, p-c-Jun and p-c-Fos by PB203 reversed the elevated levels of MMPs mediated by UVB exposure, resulting in the upregulation of collagen I expression. Consistent with these animal data, PB203 remarkably enhanced the mRNA expression of collagen I, filaggrin, involucrin and loricrin, while suppressed that of MMPs in UVB-irradiated HaCaT cells. And PB203 increased the wound recovery rate of cells by promoting their proliferation and migration. Moreover, PB203 significantly recovered the activity of superoxide dismutase inhibited by UVB in both mice and cells. In conclusion, PB203, which protects skin from UVB-induced photodamage by exerting antioxidant properties, can be considered to have sufficient potential as a functional ingredient or therapeutic agent improving skin photoaging and related skin symptoms.
        5,500원
        4.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 외계 행성에서 주어진 임무를 모두 수행하여 클리어하는 탑 뷰 슈팅 게임을 제안한다. 제안 하는 게임을 진행한 플레이어 45명의 로그 기록과 설문 조사 결과를 분석하여, 몰입감, 플레이 패턴의 다양 성, 접근성을 중심으로 제안하는 게임의 특징을 살펴보고자 한다. 첫째, 제안한 게임은 더 높은 몰입감을 위 해 스토리 애니메이션과 오디오를 제공한다. 실험 결과 시각, 청각적 방면으로 몰입감을 효과적으로 제공하 고 있어 대다수의 플레이어가 스토리 애니메이션을 건너뛰지 않고 끝까지 시청했다. 둘째, 제안하는 게임은 더 다양한 플레이 패턴으로 즐길 수 있다. 실험 결과 수많은 경우의 수가 존재하는 무기와 스킬을 선택할 수 있게 하였기 때문에 대부분의 플레이어가 선택하는 스킬들이 서로 겹치지 않고 다양한 방식으로 게임을 플레이할 수 있다. 플레이 패턴이 다양한 만큼 더 게임을 오랫동안, 더 재미있게 즐길 수 있다. 셋째, 제안한 게임은 맵을 비교적 단순하게 구성하였다. 그런데, 호기심 많은 일부 플레이어들이 미션과 직접 관련이 없는 경로를 찾아서 길을 헤매는 경우가 나타났다. 이로 인해, 플레이어들이 게임을 다시 한번 진행하고자 하는 경향이 나타났다.
        4,000원
        8.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study identified single nucleotide polymorphisms (SNPs) that affect the body weight of chickens. Analysis of body weight showed that the Cornish breed had the highest body weight, and the Korean native chicken (Gray Brown) had the lowest body weight. TSH is composed of an α-subunit and a β-subunit, and the TSH-β gene encoding the β-subunit has been reported to be associated with obesity. In chickens, it is located on chromosome 26 and is reported to be associated with growth. The calcium-sensing receptor gene (CaSR) plays a role in the regulation of extracellular calcium homeostasis and is responsible for calcium absorption in the urinary tract, which affects the eggshell quality in poultry. It was shown that TSH-β was strongly correlated with weight in Cornish and Korean native (Gray Brown) chickens, particularly in those with the CC trait. However, CaSR showed no association with body weight in poultry; it was associated with calcium and the eggshell. Thus, selection for TSH-β can be used to produce individuals with more favorable traits in terms of body weight.
        4,000원
        9.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Using data from flies collected with pitfall traps in 365 forests on a nationwide scale in Korea, the abundance and distribution changes of two families (Phoridae and Lauxaniidae) in Korean forests were predicted at the genus level according to two climate change scenarios: RCP 4.5 and RCP 8.5. The most suitable temperature for the 17 major genera was estimated using a weighted average regression model. Stichillus and Anevrina displayed the lowest optimum temperature with 7.6℃ and 8.5℃ in annual mean temperature, respectively, whereas Chonocephalus had the highest optimum temperature with 12.1℃. Among thirty genera, seven genera (four from Phoridae and three from Lauxaniidae), which showed their abundance in a bell-type or linear pattern along the temperature gradient, were used for predicting the distribution changes according to the future climate change scenarios. All the taxa of this study are expected to decrease in abundance and distribution as a function of temperature increase. Moreover, cold-adapted taxa were found to be more affected than warmadapted taxa.
        4,000원
        16.
        2019.04 구독 인증기관·개인회원 무료
        본 조사지인 돌리네 습지보호지역은 경북 문경시 산북면 굴봉산 정상부에 위치하였으며, 물이 고이기 힘든 돌리네(doline) 지형에 형성된 희귀 습지이다. 뿐만 아니라 멸종위기종과 법적보호종이 분포하는 등 생물다양성 또한 매우 풍부한 것으로 평가되고 있다. 그러나 습지보호지역 주변으로 과수원 등 경작지가 형성되어 있어, 관리 및 보전을 위한 조사 및 대책이 필요하다. 따라서 본 조사에서는 습지보호지역의 체계적인 관리를 위하여 돌리네 습지의 곤충상을 조사하였다. 조사 방법에는 곤충의 다양한 습성과 서식환경을 고려하여, Searching, Sweeping, Pitfall trap, Bucket trap으로 총 4가지의 채집방법으로 조사를 실시하였다. 그 결과 총 11목 82과 188속 237종이 확인되었으며, 이중 딱정벌레목이 가장 많이 출현하였다. 특이사항으로 환경부지정종 51종(중복포함)이 조사되었으며, 그중 멸종위 기종 1종이 확인되었다. 본 연구를 통해 돌리네 습지보호지역의 곤충상을 파악하고 관리 및 보전에 대한 기초자료를 제공하고자 한다.
        17.
        2018.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hierarchically porous, chemically activated carbon materials are readily derived from biomass using hydrothermal carbonization (HTC) and chemical activation processes. In this study, empty fruit bunches (EFB) were chosen as the carbon source due to their sustainability, high lignin-content, abundance, and low cost. The lignin content in the EFB was condensed and carbonized into a bulk non-porous solid via the HTC process, and then transformed into a hierarchical porous structure consisting of macro- and micropores by chemical activation. As confirmed by various characterization results, the optimum activation temperature for supercapacitor applications was determined to be 700°C. The enhanced capacitive performance is attributed to the textural property of the extremely high specific surface area of 2861.4 m2 g–1. The prepared material exhibited hierarchical porosity and surface features with oxygen functionalities, such as carboxyl and hydroxyl groups, suitable for pseudocapacitance. Finally, the as-optimized nanoporous carbons exhibited remarkable capacitive performance, with a specific capacitance of 402.3 F g–1 at 0.5 A g–1, a good rate capability of 79.8% at current densities from 0.5 A g–1 to 10 A g–1, and excellent life cycle behavior of 10,000 cycles with 96.5% capacitance retention at 20 A g–1.
        4,000원
        18.
        2017.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The electronic and optical characteristics of molybdenum disulphide (MoS2) film significantly vary with its thickness, and thus a rapid and accurate estimation of the number of MoS2 layers is critical in practical applications as well as in basic researches. Various existing methods are currently available for the thickness measurement, but each has drawbacks. Transmission electron microscopy allows actual counting of the MoS2 layers, but is very complicated and requires destructive processing of the sample to the point where it will no longer be useable after characterization. Atomic force microscopy, particularly when operated in the tapping mode, is likewise time-consuming and suffers from certain anomalies caused by an improperly chosen set point, that is, free amplitude in air for the cantilever. Raman spectroscopy is a quick characterization method for identifying one to a few layers, but the laser irradiation causes structural degradation of the MoS2. Optical microscopy works only when MoS2 is on a silicon substrate covered with SiO2 of 100~300 nm thickness. The last two optical methods are commonly limited in resolution to the micrometer range due to the diffraction limits of light. We report here a method of measuring the distribution of the number of MoS2 layers using a low voltage field emission electron microscope with acceleration voltages no greater than 1 kV. We found a linear relationship between the FESEM contrast and the number of MoS2 layers. This method can be used to characterize MoS2 samples at nanometer-level spatial resolution, which is below the limits of other methods.
        4,000원
        19.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Alginate lyase from Streptomyces violaceoruber was purified by DEAE sephacel chromatography and SP sepharose chromatography. The specific activity of the purified enzyme was 14.6 units/mg protein, representing a 40.6-fold purification of the crude extract. The final preparation thus obtained showed a single band on Tricine-SDS polyacrylamide gel electrophoresis whose molecular weight was determined to be 23.3 kDa. The polyMG block of sodium alginate was hydrolyzed by the purified alginate lyase and then separated by activated carbon column chromatography and bio gel P-2 gel filtration. The main hydrolysates were composed of hetero type M/G-oligosaccharides with the degrees of polymerization (D.P.) being 6 and 8. To investigate the effects of hetero type M/Goligosaccharides from the sodium alginate on the growth of some intestinal bacteria, cells were cultivated individually on the modified-MRS medium containing D.P. 6 and 8 M/G-oligosaccharides. B. longumgrew 4.25-fold and 6.44-fold more effectively by the treatment of D.P. 6 and 8 M/G-oligosaccharides compared with those of standard MRS medium. In addition, B. bifidumgrew 3.3-fold and 5.4-fold more effectively by the treatment of D.P. 6 and 8 M/G-oligosaccharides. In conclusion, D.P. 8 was more effective than D.P. 6 hetero M/G-oligosaccharides as regards the growth of Bifidobacteriumspp. and Lactobacillus spp
        4,000원
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