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        검색결과 277

        1.
        2025.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, we examine the relationships between the National Oceanic and Atmospheric Administration (NOAA) space weather scale frequencies and the maximum monthly sunspot number in each solar cycle: 1975 to 2020 for radio blackouts (R scales) and solar radiation storms (S scales), 1932 to 2020 for geomagnetic storms (G scales). Our main results are as follows. First, we find that NOAA space weather scale frequencies have strong solar cycle dependencies. Second, we propose new linear relationships between the frequency of certain scales (R1 to R4, and G1 to G4) and the maximum monthly sunspot number. T-test results show that R1 to R3 and G1 to G4 relationships are statistically meaningful, but marginal for R4. Third, our results significantly reduce the root-mean-square error (RMSE) between observed and suggested frequencies compared to the NOAA’s current frequencies. For example, in the case of solar cycle 24, our new prediction (74) for R3 scale is much more consistent with the observational frequency (74) than the NOAA prediction (175), and our prediction (85) for G3 scale is much closer to the observation (40) than the NOAA prediction (200). Our work may provide a useful guideline for advancing the space weather scales.
        4,000원
        2.
        2024.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        미선나무는 한국특산의 낙엽관목이며 위기종(Endangered; EN)으로 평가된다. 먼저 전국적인 분포현황을 세부적으로 평가하였다. 관찰된 분포 유형에 따라 개체군구조를 평가하였다, 또한 서로 다른 개체군 구조에 미치는 식생, 토양기질을 평가하였다. 미선나무는 총 13개의 아개체군이 조사되었다. 가장 안정적인 개체군은 충청북도 진천군에 위치하였다. 주로 낙엽활엽수림의 하부에 분포하였고 침엽수, 활엽수 혼효림에 분포지가 위치하기도 하였다. 어린개체로만 구성된 경우, 큰 개체로만 구성된 경우 및 소수의 큰 개체와 크기가 작은 개체로 구성된 경우가 조사되었다. 분포지는 돌서렁 (Scree) 및 하안의 급경사지에 위치하였다. 토양기질에는 서로 다른 크기의 자갈이 약 50% 포함되어 있었고 경사도는 높았다. 분포지에서 관찰된 서로 다른 크기의 개체군 구조는 토양기질, 유기물함량, 식생구조 등이 복합적으로 작용하였 다. 이와 더불어 서로 다른 정착시기에 따라 서로 다른 개체군 구조를 나타내었다. 지역적색목록평가 항목과 기준을 적용하여 재평가하였다. 점유면적 및 개체수가 변동되었지만 분포지에서 관찰되는 생육지의 질적 저하와 아개체군내에 서의 집단간 파편화 증가에 따라 위기종(EN; B2ab(iii))이 유지되었다. 각각의 아개체군별로 종의 특성을 고려한 보전관 리계획의 수립과 시행이 필요함을 제안하였다.
        5,500원
        3.
        2024.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        급성 뇌경색 진단에는 환자에 따라 관류강조영상과 조영증강 자기공명혈관영상이 동시에 촬영되는 경우가 있으며, 이 과정에서 MRI 조영제인 가돌리늄의 T1 단축 효과가 발생하여 동맥과 정맥의 신호 겹침이 빈번히 발생한다. 특 히, 3D T1 경사에코 기법을 사용한 CE-MRA에서 첫 번째 조영제 주입(PWI) 후 연속적으로 발생하는 T1 감소 효과로 인해 혈관의 정확한 묘사에 한계가 있었다. 본 연구에서는 이러한 문제를 해결하기 위해 마스크 영상의 획득 시점을 조정하여 새로운 방법(B)을 제안하였다. 기존 방법(A)에서는 관류강조영상 이전에 마스크 영상을 획득했지 만, 새로운 방법(B)에서는 관류강조영상 이후 마스크 영상을 획득하여 동맥과 정맥 신호 겹침을 효과적으로 줄였다. 연구 결과, S상 정맥동과 내경정맥에서 새로운 방법이 기존 방법보다 유의미하게 낮은 대조대잡음비를 보였으며, 신호 겹침이 줄어들어 정맥 신호의 억제 효과가 극대화되었다(p<0.05). 본 연구의 새로운 방법은 기술적으로 추가적 인 복잡성 없이 효율적으로 정맥 신호를 제거하여 CE-MRA 영상의 진단적 정확성을 향상하는 유용한 기법으로 평 가된다. 향후 연구에서는 더 다양한 환자군을 대상으로 본 방법의 유용성을 검증하고, 최적의 방안 모색을 할 필요가 있다.
        4,000원
        4.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: In healthy dentin conditions, odontoblasts have an important role such as protection from invasion of pathogens. In mammalian teeth, progenitors such as mesenchymal stem cells (MSCs) can migrate and differentiate into odontoblast-like cells, leading to the formation of reparative dentin. For differentiation using stem cells, it is crucial to provide conditions similar to the complex and intricate in vivo environment. The purpose of this study was to evaluate the potential of differentiation into odonto/ osteoblasts, and compare co-culture with/without epithelial cells. Methods: MSCs and epithelial cells were successfully isolated from dental tissues. We investigated the influences of epithelial cells on the differentiation process of dental pulp stem cells into odonto/osteoblasts using co-culture systems. The differentiation potential with/without epithelial cells was analyzed for the expression of specific markers and calcium contents. Results: Differentiated odonto/osteoblast derived from dental pulp tissue-derived mesenchymal stem cells with/without epithelial cells were evaluated by qRT-PCR, immunostaining, calcium content, and ALP staining. The expression of odonto/ osteoblast-specific markers, calcium content, and ALP staining intensity were significantly increased in differentiated cells. Moreover, the odonto/osteogenic differentiation capacity with epithelial cells co-culture was significantly higher than without epithelial cells co-culture. Conclusions: These results suggest that odonto/osteogenic differentiation co-cultured with epithelial cells has a more efficient application.
        4,000원
        5.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The increase in the use of artificial intelligence (AI) in the workplace has introduced changes to traditional working environments. However, these are changes not only to employee productivity but also to how employees feel and think about their work. Based on prior research that has suggested connections between employees’ perceptions of AI and their emotions and thoughts at work, the present study tested a moderated mediation model in which the perception of AI opportunity is indirectly related to job insecurity via employee hope, with tenure as a moderator. Data obtained from 290 Korean full-time employees illustrated that the perception of AI opportunity was negatively related to job insecurity through hope acting as a mediator. In addition, this indirect relationship was found to be dependent on the moderating role of tenure. Specifically, at lower levels of tenure, the aforementioned indirect relationship was statistically significant, but at higher levels of tenure, this indirect relationship was no longer found to be statistically significant. The implications, limitations, and future research directions of this study are discussed.
        4,600원
        6.
        2024.04 구독 인증기관·개인회원 무료
        Pollination is an important ecosystem service mostly provided by diversity of pollinating insects and other animals. As in the anthropocene biodiversity crisis with the climate change, pollination systems are experiencing strongly challenged such as pollinator diversity and abundance decline, pollinator health weakness, pollinator-plant network instability as well as the crop-pollinator habitat fragmentation and insuitability. Here we present some research progress conducted from our group in the last decade. As the pollination dependence of Korean agriculture increases, pollination contribute ap. one forth of national agricultural production, and is responsible substantial portion of vitamin and mineral provisioning. Pollinator diversity is declining in various crop systems and network connectivity is decreasing. Still in agricultural landscape, honeybee (Apis spp) is the main pollinator, accounting ap. 70% of bees, and showed the possible resource partitioning between the native, A. cerana and the introduced, A. mellifera. Simulation of crop-pollinating insect distribution suitability showed up and down directional responses, but more on the negative Further research area for better understanding and stabilizing the plant-pollinator system was proposed.
        7.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        압축센스(Compressed SENSE) 기법은 검사 시간을 획기적으로 단축할 수 있으나, 시간 단축을 위한 기법적용 시 가속계수를 증가시키면 인공물의 발생이 영상에서 증가하는 문제점이 있다. 이에 인공물이 발생하지 않으면서 검사 시간을 최대한 단축할 수 있는 최적의 압축센스 가속계수를 제시하고자 하였다. 연구 방법은 인공물이 발생하지 않는 가속계수 1.0을 기준으로 0.5 간격씩 5.0까지 무릎관절 자기공명영상의 팬텀 실험과 임상실험 영상을 획득한 후, 방사선사 10명이 5점 척도로 영상을 평가하여 유의한 차이가 있는지 판단하였다. 연구 결과 T1 강조영상과 T2 강조 영상 모두 팬텀 실험은 가속계수 2.0 이하로 하였을 때 임상실험은 3.0 이하로 하였을 때 기준이 되는 1.0 영상과 차이가 없었다. 결론적으로 무릎관절 자기공명영상 검사 시 인공물이 발생하지 않으며 검사 시간을 최대로 단축할 수 있는 최적의 압축센스 가속계수는 팬텀 실험의 경우 2.0, 임상실험의 경우 3.0이 적정하리라 판단된다.
        4,200원
        8.
        2023.10 구독 인증기관·개인회원 무료
        2015년부터 2022년도까지 6개목(딱정벌레목, 노린재목, 나비목, 벌목, 파리목, 총채벌레목)에 대해서 식물검 역현장 검출실적과 국내 미기록종을 분석 하였다. 총 45,078건이 검역현장에서 검출되었으며, 545종이 새롭게 국내에 보고되었다. 이중 9종은 검역현장에서도 검출된 것으로 확인되었다. 검역현장에서는 딱정벌레목, 총채 벌레목, 노린재목이 높은 검출률을 보였으며, 국내 미기록종 중에서는 벌목이 176종으로 가장 많이 보고되었다. 본 연구는 검출실적과 미기록종과의 관계를 살펴볼 때, 동시간대의 침입압력으로는 설명이 어렵다는 것을 보여 주고 있으며, 이는 지속적인 식물검역시스템 개선이 필요성을 제시한다.
        9.
        2023.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigated an emerging magnetic loop dynamically formed on the Sun, which has the effective footpoint heating source that may play a key role in heating a solar atmosphere with free magnetic energy in it. It is suggested that the heating source could be related to local compression of a plasma in the emerging loop by means of Lorentz force, which converts the magnetic energy to the internal energy of the plasma that is used to reaccelerate a decelerated downflow along the loop, eventually generating the source when the kinetic energy of the downflow is thermalized. By analyzing very high-cadense data obtained from a magnetohydrodynamic simulation, we demonstrate how the local compression is activated to trigger the generation of the heating source. This reveals a characteristic of the emerging loop that experiences a dynamic loop-loop interaction, which causes the local compression and makes the plasma gain the internal energy converted from the magnetic energy in the atmosphere. What determines the characteristic that could distinguish an illuminated emerging loop from a nonilluminated one is discussed.
        4,000원
        10.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This case report describes the pathological features of pulmonary alveolar proteinosis(PAP) in mouse. Grossly, multiple irregular yellow-grey patches were observed on the lung surface of a C57BL/6 mouse. Histopathologically, the alveolar walls were thickened by type II cell hyperplasia and cellular infiltrates, and the bronchioles and alveolar lumens were filled with amorphous eosinophilic lipoproteinaceous material. This material was positive for Periodic acid-Schiff stain. Gomori methenamine silver staining was negative. Immunohistochemical staining showed that cells in the alveolar wall and lumen were positive for surfactant protein B, chitinase-like protein-3, and CD68. As a result, PAP was diagnosed. This is a rare case of spontaneous PAP in mice, and we report the histopathological characteristics along with the literature.
        3,000원
        14.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The plant-specific NAC transcription factors control various biological processes, including plant development and stress responses. We have isolated an ANAC032 gene, one of the NAC transcription factor family, which was highly activated by multi-abiotic stresses, including high salt and drought in Arabidopsis. Here, we generated transgenic plants constitutively expressing ANAC032 and its knockout to identify the functional roles of ANAC032 in Arabidopsis under abiotic stress responses. The ANAC032-overexpressing plants showed enhanced tolerance to salinity and drought stresses. The anac032 knockout mutants were observed no significant changes under the high salt and drought conditions. We also monitored the expression of high salt and drought stress-responsive genes in the ANAC032 transgenic plants and anac032 mutant. The ANAC032 overexpression upregulated the expression of stress-responsive genes, RD29A and ERD10, under the stresses. Thus, our data identify that transcription factor ANAC032 plays as an enhancer for salinity and drought tolerance through the upregulation of stress-responsive genes and provides useful genetic traits for generating multi-abiotic stress-tolerant forage crops.
        4,000원
        15.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper aims to investigate Korean EFL learners’ pragmatic performance in request speech acts in comparison with native speakers of English. Written discourse completion tasks (WDCT) are used to examine how native and non-native speakers request in terms of request strategies, internal modifications, and external modifications. The results show that first, Korean learners had a higher frequency of inappropriate strategies than native speakers. Second, they lacked the quantity and variety of internal modifications both lexically and syntactically. However, regarding external modifications, their use of supportive moves was similar to that of natives in frequency and order. In addition, this study identified newly emergent supportive moves that are Korean-specific and detrimental to communication goals. The findings shed light on pragmatic instruction in the Korean EFL situation by providing research-informed data. Several pedagogical implications are suggested for application in teaching.
        8,000원
        16.
        2022.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        To seek an atmospheric heating mechanism operating on the Sun we investigated a heating source generated by a downflow, both of which may arise in a magnetic loop dynamically formed on the Sun via flux emergence. Since an observation shows that the illumination of evolving magnetic loops under the dynamic formation occurs sporadically and intermittently, we performed a magnetohydrodynamic simulation of flux emergence to obtain a high-cadence simulated data, where temperature enhancement was identified at the footpoint of an evolving magnetic loop. Unlike a rigid magnetic loop with a confined flow in it, the evolving loop in a low plasma β atmosphere is subjected to local compression by the magnetic field surrounding the loop, which drives a strong supersonic downflow generating an effective footpoint heating source in it. This may introduce an energy conversion system to the magnetized atmosphere of the Sun, in which the free magnetic energy causing the compression via Lorentz force is converted to the flow energy, and eventually reduced to the thermal energy. Dynamic and thermodynamic states involved in the system are explained.
        4,000원
        17.
        2022.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This research investigated the effect of Si addition on the microstructure, mechanical properties, electric and thermal conductivity of as-extruded Al 6013 alloys. As the content of Si increased, the area fraction of the second phase increased. As the Si content increased, the average grain size decreased remarkably, from 182 (no Si addition) to 142 (1.5Si), 78 (3.0Si) and 77 μm (4.5Si) due to dynamic recrystallization by the dispersed second particles in the aluminum matrix during the hot extrusion. As the Si content increased, the yield strength and ultimate tensile strength increased. The maximum values of yield strength and ultimate tensile strength were 224 MPa and 103 MPa for the 6013-4.5Si alloy. As the amount of Si added increased, the electrical and thermal conductivity decreased. The electrical and thermal conductivity of the Al6013-4.5Si alloy were 44.0% IACS and 165.0 W/mK, respectively. The addition of Si to Al 6013 alloy had a significant effect on its thermal conductivity and mechanical properties.
        4,000원
        18.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Kale (Brassica oleracea var. acephala) is one of the most frequently consumed leafy vegetables globally, as it contains numerous nutrients; essential amino acids, phenolics, vitamins, and minerals, and is particularly rich in glucosinolates. However, the differences in the biosynthesis of glucosinolates and related gene expression among kale cultivars has been poorly reported. In this study, we investigated glucosinolates profile and content in three different kale cultivars, including green (‘Man-Choo’ and ‘Mat-Jjang’) and red kale (‘Red-Curled’) cultivars grown in a vertical farm, using transcriptomic and metabolomic analyses. The growth and development of the green kale cultivars were higher than those of the red kale cultivar at 6 weeks after cultivation. High-performance liquid chromatography (HPLC) analysis revealed five glucosinolates in the ‘Man-Choo’ cultivar, and four glucosinolates in the ‘Mat-Jjang’ and ‘Red-Curled’ cultivars. Glucobrassicin was the most predominant glucosinolate followed by gluconastrutiin in all the cultivars. In contrast, other glucosinolates were highly dependent to the genotypes. The highest total glucosinolates was found in the ‘Red-Curled’ cultivar, which followed by ‘Man-Choo’ and ‘Mat-Jjang’. Based on transcriptome analysis, eight genes were involved in glucosinolate biosynthesis. The overall results suggest that the glucosinolate content and accumulation patterns differ according to the kale cultivar and differential expression of glucosinolate biosynthetic genes.
        4,200원
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