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        검색결과 9,927

        481.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문은 회분식 반응기에서 습식 산화법으로 합성한 칼륨 페레이트(VI)에 의한 난분해성 아조 염료Reactive Black 5의 분해 과정을 연구하는 것을 목적으로 한다. 수용액에서 RB5의 분해는 pH, Ferrate (VI) 투입량, 초기 농도, 수용액 온도 등 다양한 변수의 조건에서 연구되었다. RB5 경우에는 최대 분해 효율은 pH 7.0에서 63.2%가 달성되었으며, 이 실험 조건에서 얻은 kapp 값은 190.49 M-1s-1 으로 나타났다. 온도 또한 가장 중요한 매개 변수 중 하나로 연구되었으며, 그 결과로부터 온도(45°C까지)를 증가시키면 페레이트(VI)에 의한 아조 화합물 염료의 분해 효율이 증가하고, 온도가 45°C를 초과하면 분해 효율이 저하되는 것으로 나타났다.
        4,200원
        482.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examines the rise of the Body Positive Movement on TikTok and its role as a form of online content activism influencing the fashion design and industry. Through a combination of literature review and case study methodology, the study explores the expression techniques and thematic types of Body Positive Movement on TikTok. Reviews of literature, previous studies, online articles, fashion journals, and relevant search terms on TikTok informed a definition of Body Positive Movement and an analysis of its formation and rise. The research findings confirm the impact TikTok content on Body Positive Movement has on the fashion industry in addressing external factors (i.e., ‘Appearance’, ‘Race’, ‘Aging’, ‘Physical Disability’) and intrinsic factors (i.e., ‘Acceptance of Diversity’, ‘Self-Esteem’, ‘Rejection of Stereotypes’, ‘Appropriate Representation’, ‘Information Provision’). The key external factor , ‘Appearance’, includes subcategories such as ‘Body Shape’, ‘Body Hair’, ‘Skin’, and ‘Facial Features’. TikTok content creators on fashion creatively combine music, emojis, and visual storytelling to exhibit positive self-perception concerning these factors. A significant finding of the study is that short clips predominantly manifesting external factors differentiate into informative or enlightening videos associated with intrinsic factors. The study underscores Body Positive Movement's important influence on the fashion industry from design to presentation.
        5,700원
        483.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study explores the profound impact of varying oxygen content on microstructural and mechanical properties in specimens HO and LO. The higher oxygen concentration in specimen HO is found to significantly influence alpha lath sizes, resulting in a size of 0.5-1 μm, contrasting with the 1-1.5 μm size observed in specimen LO. Pore fraction, governed by oxygen concentration, is high in specimen HO, registering a value of 0.11%, whereas specimen LO exhibits a lower pore fraction (0.02%). Varied pore types in each specimen further underscore the role of oxygen concentration in shaping microstructural morphology. Despite these microstructural variations, the average hardness remains consistent at ~370 HV. This study emphasizes the pivotal role of oxygen content in influencing microstructural features, contributing to a comprehensive understanding of the intricate interplay between elemental composition and material properties.
        4,000원
        484.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In the merger-driven galaxy evolution scenario, dust-obscured quasars are considered to be an intermediate population between merger-driven star-forming galaxies and unobscured quasars; however, this scenario is still controversial. To verify this, it is necessary to investigate whether dust-obscured quasars have higher Eddington ratio (λEdd) values than those of unobscured quasars, as expected in the merger-driven galaxy evolution scenario. In this study, we derive black hole (BH) masses of 10 dust-obscured quasars at z ∼ 2, during the peak period of star-formation and BH growth in the Universe, using a newly derived mid-infrared (MIR) continuum luminosity (LMIR)-based estimator that is highly resistant to dust extinction. Then, we compare the λEdd values of these dust-obscured quasars to those of unobscured type-1 quasars at similar redshifts. We find that the measured log (λEdd) values of the dust-obscured quasars, −0.06 ± 0.10, are significantly higher than those of the unobscured quasars, −0.86 ± 0.01. This result remains consistent across the redshift range from 1.5 to 2.5. Our results show that the dust-obscured quasars are at their maximal growth, consistent with the expectation from the merger-driven galaxy evolution scenario at the epoch quasar activities were most prominent in the cosmic history.
        4,000원
        485.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) will provide all-sky spectral survey data covering optical to mid-infrared wavelengths with a spatial resolution of 6.′′2, which can be widely used to study galaxy formation and evolution. We investigate the galaxy-galaxy blending in SPHEREx datasets using the mock galaxy catalogs generated from cosmological simulations and observational data. Only ∼0.7% of the galaxies will be blended with other galaxies in all-sky survey data with a limiting magnitude of 19 AB mag. However, the fraction of blended galaxies dramatically increases to ∼7–9% in the deep survey area around the ecliptic poles, where the depth reaches ∼22 AB mag. We examine the impact of the blending in the number count and luminosity function analyses using the SPHEREx data. We find that the number count can be overestimated by up to 10–20% in the deep regions due to the flux boosting, suggesting that the impact of galaxy-galaxy blending on the number count is moderate. However, galaxy-galaxy blending can marginally change the luminosity function by up to 50% over a wide range of redshifts. As we only employ the magnitude limit at Ks-band for the source detection, the blending fractions determined in this study should be regarded as lower limits.
        4,000원
        486.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A force-free field (FFF) is determined solely by the normal components of magnetic field and current density on the entire boundary of the domain. Methods employing three components of magnetic field suffer from overspecification of boundary conditions and/or a nonzero divergence-B problem. A vector potential formulation eliminates the latter issue, but introduces difficulties in imposing the normal component of current density at the boundary. This paper proposes four different boundary treatment methods within the vector potential formulation. We conduct a comparative analysis of the vector potential FFF solvers that we have developed incorporating these methods against other FFF codes in different magnetic field representations. Although the vector potential solvers with the new boundary treatments do not outperform our poloidal-toroidal formulation code, they demonstrate comparable or superior performance compared to the optimization code in SolarSoftWare. The methods developed here are expected to be readily applied not only to force-free field computations but also to time-dependent data-driven simulations.
        4,300원
        487.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In recent years, the energy storage sector has experienced a notable transition toward the use of organic electrodes. This shift is largely attributed to their superior energy density, cost-effectiveness, and eco-friendliness. However, there is a main drawback that the organic molecules oftentimes suffer shuttle phenomenon across the separator due to their high solubility in the organic electrolyte. In addition, the low electrical conductivity of organic materials is also detrimental, thereby requiring a large amount of carbon additives (up to 40 wt. %) in the electrode. In this perspective, addition of carbon additives with the desirable amount, which can prevent organic molecules from being dissolved into the liquid phase as well as provide the electrical conductivity. While N,Nʹ-dimethylphenazine (DMPZ) was investigated as a model material, we compared two carbon additives with different surface areas and functional groups. We carefully scrutinized the structural effect of carbon additives on the cycle-life performance of the organic electrode.
        4,000원
        488.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Traditional piles used for deep foundation, such as steel, concrete, and timber, are susceptible to corrosion and a reduction in structural capacity over time. This has led to the development of new materials like concrete-filled FRP piles (CFFP). CFFP is a composite pile filled with concrete and covered with a fiber-reinforced plastic (FRP) shell, providing non-corrosive reinforcement and protection to the concrete. As a result, CFFP is a highly promising candidate for implementation in various fields due to its structural advantages and necessity. Compared to traditional concrete piles, CFFP can be installed with less damage and a lower blow range due to its elastic modulus, damping ratio, and specific weight. The bearing capacity of a pile is influenced by various factors, including its stiffness, residual stress, and axial load resistance. Due to competitive pricing, glass fiber has been widely utilized, and there is a growing interest regarding carbon-fiber-reinforced concrete piles due to the excellent mechanical properties of carbon fiber. The remarkable stiffness and strength attributes of carbon fibers are evident in CFRP-confined piles, which present a notably wide range of load-bearing capacities, boasting an ultimate axial load capacity ranging from 500 to 4000 kN. Furthermore, CFFPs have been confirmed to have superior lateral load resistance compared to conventional piles, attributed to the reinforcement provided by FRP materials. Conventional piles face a challenge in that their structural characteristics deteriorate in the corrosive marine environment, with a projected lifespan of less than 20 years. In contrast, the service life of CFFPs is estimated to range from 50 to 75 years.
        4,800원
        489.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Disposable masks manufactured in response to the COVID-19 pandemic have caused environmental problems due to improper disposal methods such as landfilling or incineration. To mitigate environmental pollution, we suggest a new process for recycling these disposable masks for ultimate application as a conductive material in lithium-ion batteries (LIBs). In our work, the masks were chemically processed via amine functionalization and sulfonation, followed by carbonization in a tube furnace in the Ar atmosphere. The residual weight percentages, as evaluated by thermogravimetric analysis (TGA), of the chemically modified masks were 30.6% (600 °C, C-600), 24.5% (750 °C, C-750), and 24.1% (900 °C, C-900), respectively, thereby demonstrating the possibility of using our proposed method to recycle masks intended for disposal. The electrochemical performance of the fabricated carbonized materials was assessed by fabricating silicon/graphite (20:80) anodes incorporating these materials as additives for use in LIBs. Using a coin-type half-cell system, cells with the aforementioned carbonized materials exhibited initial capacities of 553 mAh/g, 607 mAh/g, and 571 mAh/g, respectively, which are comparable to those of commercial Super P (591 mAh/g). Cell cycled at the rate of 0.33 C with C-600, C-750, and C-900 as additives demonstrated capacity retention of 53.2%, 47.4%, and 51.1%, respectively, compared with that of Super P (48.3%). In addition, when cycled at rates from 0.2 to 5 C, the cells with anodes containing the respective additives exhibited rate capabilities similar to those of Super P. These results might be attributable to the unique surface properties and morphologies of the carbonized materials derived from the new recycling procedure, such as the size and number of heteroatoms on the surface.
        4,200원
        490.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Synthesis of extremely competent materials is of great interest in addressing the energy storage concerns. Manganese oxide nanowires ( MnO2 NWs) are prepared in situ with multiwall carbon nanotubes (MWCNT) and graphene oxide (GO) using a simple and effective hydrothermal method. Powder XRD, Raman and XPS analysis are utilized to examine the structural characteristics and chemical state of composites. The initial specific discharge capacity of pure MnO2 NWs, MnO2 NWs/ MWCNT and MnO2 NWs/rGO composites are 1225, 1589 and 1685 mAh/g, respectively. The MnO2 NWs/MWCNT and MnO2 NWs/rGO composites showed stable behavior with a specific capacity of 957 and 1108 mAh/g, respectively, after 60 cycles. Moreover, MnO2 NWs/rGO composite sustained a specific capacity of 784 mAh/g, even after 250 cycles at a current density of 1 A/g showing outstanding cycling stability.
        4,200원
        491.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Cerebral palsy presents significant challenges in motor function for affected children. While conventional bottom-up approaches are common in physical therapy, there is increasing interest in the efficacy of the top-down approach. Objectives: To investigated the impact of applying the top-down approach in physical therapy for a child diagnosed with cerebral palsy, focusing on functional improvement and quality of life. Design: A single-case study. Methods: The patient was a 15-year-old boy with spastic diplegic cerebral palsy who was entering middle school. Cerebral palsy treatment approach of the top-down method (jumping rope) was used to guide and direct physical therapy. Results: The child improved in muscle strength of lower extremity, gross motor function, participation and self-esteem, but the pattern of his gait seemed to be more severe on tiptoe. When the child participated in a jumping rope class, he was able to do more than 10 jumps. Conclusion: The effectiveness of the top-down approach in enhancing functional outcomes and quality of life in children with cerebral palsy. It highlights the potential of this approach in pediatric physical therapy, warranting further research validation.
        4,000원
        492.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Most studies targeting stroke patients have confirmed improvements in balance and walking using immersive and non-immersive virtual reality training programs. However, to date, there are not many studies targeting brain activation enhancement for the two training programs. Objectives: The purpose of this study is to investigate the effect of a virtual reality training program on the EEG of stroke patients according to differences in immersion. Design: A randomized controlled trial. Methods: A total of 20 stroke patients, with 10 in an immersive virtual reality training programs group (IVRG) and 10 in a non-virtual reality training programs group (NVRG) were randomly assigned to exercise three times a week for 6 weeks. EEG was measured for 2 minutes using DSI-24. Results: The intra-group difference in relative alpha waves of brain waves was not significant for both groups, and the between-group difference was not significant. Differences in EEG relative beta waves in the experiment group were significant in the Fp1, Fp2, Cz, C3, C4, P3, and O2 in the experiment group, and significant in the Cz and O2 in the control group. As a result of comparing the differences between each group before and after, there was a significant difference in the Fp1 area. Conclusion: Virtual reality training programs based on differences in immersion were found to have a positive effect on EEG. Therefore, it is believed that a virtual reality training program based on differences in immersion can be provided as a clinical intervention method for EEG.
        4,500원
        493.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: The Nordic hamstring exercise is effective as a representative exercise for strengthening eccentric contraction that can activate the hamstring at high levels, improve eccentric contraction strength and ability, and significantly reduce injury rates. Objectives: To investigated a comparison with the lunge exercise to determine the effect of the Nordic hamstring exercise on muscle activity and balance ability in a sample of adult amateurs and football players. Design: Randomized controlled trials. Methods: The subjects of the study were stratified samples of 28 professional and amateur football players and two groups (Nordic hamstring group and lunge group) of 14 people each were studied. Surface electromyography using, was performed to measure the hamstring muscle activity, and the good morning exercise was selected as the measurement exercise. For balance ability, the surface area ellipse and length were measured with BioRescue, while for static balance, the posture of closing the eyes and single-limb standing was measured, and for dynamic balance the one-legged squat was measured. Results: The %MVIC of the semitendinosus and the biceps femoris improved in the Nordic hamstring exercise group and showed statistically significant increase (P<.05). The static and dynamic balance improved in the Nordic hamstring exercise group and showed statistically significant decrease (P<.05). Conclusion: The Nordic hamstring exercise can be useful as an exercise to improve the hamstring muscle activity and balance ability of professional and amateur football players.
        4,200원
        494.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        해사영어는 선박 운항, 해양 안전, 선내 의사소통 및 선외 교신을 위해 설계된 특수한 영어 언어체계이다. 국제해사기구 STCW(선원의 훈련, 자격증명 및 당직근무의 기준에 관한 국제협약)에 따르면 국제항해에 종사하는 항해사가 되기 위해서는 SMCP를 포함한 해사영어 대한 충분한 이해가 수반되어야 한다. 본 연구는 음성인식, 번역, 단어 기입 등 유형의 해사영어시험을 통하여 학생들 의 해사영어 활용 능력을 측정하고 플랫폼 사용에 따른 시험 점수 향상 정도, 나아가 초임항해사로 나가기 위하여 요구되는 해사영어 시험 플랫폼 활용 시간 등을 조사하고자 하였다. 실험은 먼저 초기 시험을 통해 학생들의 일반영어능력과 SMCP 활용 능력에 대한 연 관성을 조사한 후, 중간 시험 및 최종 시험을 통해 플랫폼 활용에 대한 점수 향상 정도, 응시시간 변화 등 요인을 측정하였다. 초기 시 험을 통해 개인 요인(예: 토익 점수, 본인 스스로에 대한 영어능력 평가)에 따른 그룹 간 해사영어시험 점수에 유의한 차이가 있음을 확인하였으며, 중간시험 및 최종시험을 통해 플랫폼 활용이 유의한 시험점수 향상으로 이어졌음을 확인하였다. 해당 연구는 해사 교육 분야에 다양하게 적용할 수 있는 학습 플랫폼 활용 효능을 조사하였으며 향후 해사영어 교육 외 그 범위를 넓혀 활용될 수 있을 것으 로 사료된다.
        4,000원
        495.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to analyze the formative characteristics of women’s costumes among the Regency era’s elite in the television drama Bridgerton (2020). Its methodology investigates the socio-cultural background and literature on clothing in the Regency era. It also analyzes the formative elements of Daphne’s costumes (of the Bridgerton family) and Penelope’s costumes (of the Featherington family) representing the upper class. The study reveals that women’s costumes had a tubular silhouette consisting of a low neckline, high waistline, and short puffed sleeves. The series expressed well the Regency-era costumes, which were influenced by Neoclassicism and characterized by silk materials, shawls, gloves, belts, a reticule, and hairstyles. Among the formative elements, the Bridgerton and Featherington families’ costumes showed distinct differences in color, materials, patterns, accessories, and hairstyles. Daphne’s costumes were intelligent and elegant in pastel-toned blues and had small patterns. She carried small accessories and had a natural curled hairstyle. In contrast, Penelope wore decorative and splendid styles in intense colors and large patterns. Her accessories were large and colorful, and she had a strong curled hairstyle. These costumes express the Bridgerton family as aristocratic and the Petringer family as flashy, thereby distinguishing the two families. These research results will be presented as basic data for producing drama costumes in the 19th century to help complete the drama.
        4,500원
        496.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Along with other heavy metals, arsenic (As) is one among the substances most harmful to living organisms including humans. Owing to its morphological similarity to phosphorus, the uptake of As is influenced by photosynthesis and the phosphorus uptake pathway. In this study, we varied arsenic exposure and light intensity during nutrient solution cultivation of lettuce (Lactuca sativa L.) to determine the effect of these two factors on arsenic uptake, lettuce growth, and electron transfer in photosystem II. In the treatment exposed to 30 μmol L-1 of arsenic, the shoot arsenic concentration increased from 4.73 mg kg-1 to 18.97 mg kg-1 as the light intensity increased from 22 to 122 μmol m-2 s-1. The water content and ET2o/RC of the shoots were not affected by arsenic at low light intensity; however, at optimal light intensity, they decreased progressively with arsenic exposure. Increased light intensity stimulated the growth of plant roots and shoots; contrarily, the difference in growth decreased as the concentration of As exposure increased. The results of this study suggest that the effect of As on plant growth is dependent on light intensity; in particular, an increase in light intensity can increase the uptake of As, thereby affecting plant growth and As toxicity.
        4,000원
        497.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hypertension is characterized by excessive renin-angiotensin system activity, leading to blood vessel constriction. Several synthetic compounds have been developed to inhibit renin and angiotensin-converting enzyme (ACE). These drugs often have adverse side effects, driving the exploration of plant protein-derived peptides as alternative or supplementary treatments. This study assessed the phenolic compound and amino acid content and the antioxidant and antihypertensive activity of 5 South Korean staple crops. Sorghum had the highest phenolic compound content and exhibited the highest antioxidant activity. Millet grains, particularly finger millet (38.86%), showed higher antihypertensive activity than red beans (14.42%) and sorghum (17.16%). Finger millet was found to contain a large proportion of branched-chain, aromatic, and sulfur-containing amino acids, which are associated with ACE inhibition. In particular, cysteine content was positively correlated with ACE inhibition in the crops tested (r=0.696, p<0.01). This study confirmed that the amino acid composition was more correlated with the antihypertensive activity of grains than the phenolic compound content. Finger millet mainly contained amino acids, which have higher ACE inhibitory activity, resulting in the strongest antihypertensive activity. These findings underscore the antihypertensive potential of select crops as plant-based food ingredients, offering insight into their biological functions.
        4,200원
        498.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This comprehensive study delves into the intricate process of exfoliating and functionalizing boron nitride nanosheets (BNNSs) extracted from hexagonal boron nitride (h-BN), and meticulously explores their potential application within epoxy composites. The extensive research methodology encompasses a sequence of treatments involving hydrothermal and sonication processes aimed at augmenting the dispersion of BNNSs in solvents. Leveraging advanced analytical techniques such as Raman spectroscopy, X-ray diffraction, and FTIR spectroscopy, the study rigorously analyzes a spectrum of changes in the BNNS’s properties, including layer count variations, interlayer interactions, crystal structure modifications, and the introduction of functional groups. The research also rigorously evaluates the impact of integrating BNNSs, specifically glycidyl methacrylate (GMA)-functionalized BNNSs, on the thermal conductivity of epoxy composites. The conclusive findings exhibit notable enhancements in thermal properties, predominantly attributed to the enhanced dispersion of fillers and enhanced interactions within the epoxy matrix. This pioneering work illuminates the wide potential of functionalized BNNSs for significantly enhancing the thermal conductivity of epoxy composites, paving the way for advanced materials engineering and practical applications.
        4,000원
        499.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study describes Philodromus paiki sp. nov., which was previously misidentified as P. fuscomarginatus (De Geer, 1778), P. poecilus (Thorell, 1872), and P. spinitarsis Simon, 1895 in Korea, as a new species with diagnosis, detailed descriptions, and taxonomic photographs. Additionally, P. spinitarsis is also described to correct previous misidentifications of Korean records of the species.
        4,000원
        500.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Abstract Purpose : To investigate the prevalence and risk factors for dry eye syndrome (DES) in university students. Methods : A cross-sectional survey of university students was conducted through a combination of online smartphone surveys using Google Forms and face-to-face questionnaires. The questionnaire consisted of questions about risk factors for dry eye disease and the 5-item Dry Eye Questionnaire (DEQ-5). Results : A total of 288 university students participated in the study. The average age was 22.5±2.1 years, w ith 54.2% female a nd 4 5.8% m ale. The m ean of t he D EQ-5 s core w as 7.37±4.65, and the prevalence of DES by DEQ-5 was 47.2%. Female gender (p=0.012), digital screen use for more than 8 hours per day (p=0.018), digital screen use for more than two hours without a break (p=0.035), contact lens wear (p=0.016), refractive surgery (p=0.020), less than 6 hours of sleep per night (p=0.0169, and allergic conjunctivitis (p=0.016) were relevant associated risk factors for DES. Conclusion : The prevalence of DES in young adults may be underestimated in comparison to middle-aged and older adults. The severity of DES depends on several factors, including genetic and environmental factors, so identifying risk factors would help with proper prevention and early diagnosis. Key words : DEQ-5, Dry eye syndrome, Risk factor
        4,000원