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        검색결과 612

        104.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cross model correlates the dynamic complex viscosity of polymer systems to zero complex viscosity, relaxation time and power-law index. However, this model disregards the growth of complex viscosity in nanocomposites containing filler networks, especially at low frequencies. The current paper develops the Cross model for complex viscosity of nanocomposites by yield stress as a function of the strength and density of networks. The predictions of the developed model are compared to the experimental results of fabricated samples containing poly(lactic acid), poly(ethylene oxide) and carbon nanotubes. The model’s parameters are calculated for the prepared samples, and their variations are explained. Additionally, the significances of all parameters on the complex viscosity are justified to approve the developed model. The developed model successfully estimates the complex viscosity, and the model’s parameters reasonably change for the samples. The stress at transition region between Newtonian and power-law behavior and the power-law index directly affects the complex viscosity. Moreover, the strength and density of networks positively control the yield stress and the complex viscosity of nanocomposites. The developed model can help to optimize the parameters controlling the complex viscosity in polymer nanocomposites.
        4,200원
        105.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : As road pavement design in an apartment complex varies from one site to another, it is practically difficult to calculate and estimate the traffic volume of construction vehicles. Therefore, this study introduces a methodology to estimate the number of construction vehicles and use it as an indicator to evaluate the conditions of road pavement in an apartment complex. METHODS: Through a literature review and site survey, the operational status of the construction vehicles passing through the site was identified, and the factors affecting the number of construction vehicles were analyzed. The methodologies used to estimate the number of construction vehicles were verified by calculating the Cumulative Load Prediction Index (CLPI), which is a predictive index of the cumulative load on each path. By using this index, the traffic volume of construction vehicles can be estimated based on the number of households in an apartment complex. To prove this definition, we examined the surface and core conditions, and compared the results against the predicted values. RESULTS : By comparing the Cumulative Load Prediction Index with the crack rate on the pavement surface, we obtained a correlation coefficient of 0.92. Furthermore, the analysis indicated that the core condition rate would decrease as the Cumulative Load Prediction Index increased. This correlation between the Cumulative Load Prediction Index, and the pavement surface and core status demonstrates that the traffic volume can be estimated by considering the number of households. CONCLUSIONS: The Cumulative Load Prediction Index presented in this study is a suitable indicator for estimating the conditions of the road pavement in an apartment complex by considering the number of households in the complex, even if the construction processes and characteristics vary.
        4,200원
        106.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        More than 80,000 prisoners in state, federal, and private prisons work for private and for-profit industries in the United States, which is a relatively small, but rapidly growing, portion of the total number of incarcerated individuals. The main purpose of this article is to use critical concepts from Foucauldian theory to explore the relationship between incarceration and labor exploitation in the U.S. prison system. To do this, this article reviews the core Foucauldian concepts and assumptions that are relevant to explaining prison labor; applies those concepts and assumptions to the prison labor issue; and discusses a possible way for conducting an empirical study. Additionally, three implications for social work, policy intervention, and the Korean society in reference to the theory are discussed. This article suggests that understanding Foucault should be a priority to tackle forced control, unequal power, and the immobility of social and economic status embedded in the most marginalized and vulnerable populations.
        5,100원
        107.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aims to evaluate the concentration of biomarkers for heavy metals and volatile organic compounds (VOCs) for the residents living in the Gwangyang industrial complex to compare with residents in the residential area as a control. A total of 810 healthy adults participated in this study, and their urinary and blood samples were analyzed for metals, including As, Pb, Cd, or Hg, and VOC compounds. All study participants also completed questionnaire surveys to collect more detailed information on personal lifestyles, dietary and drinking habits, residential housings types, and their health conditions. The geometric means of urinary levels of Cd were 1.06 g/g creatinine for those living in the vicinity of Gwangyang industrial complex and 1.41 g/g creatinine for those in residential areas (p<0.05). Furthermore, urinary mean levels of Hg were 1.39 μg/g creatinine in the industrial area and 1.23 μg/g creatinine in the control area, respectively. The concentrations of individual VOCs in blood were significantly different between the two population groups. Therefore, urinary levels of Cd and Hg were significantly higher in the local residents compared to the Gwangyang industrial areas. A further study is needed to identify adverse health effects due to environmental exposures to heavy metals, VOCs, and other pollutants in the Gwangyang industrial complex areas in the future.
        4,000원
        108.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Heavy metals in stream water and sediments around industrial complex were studied in order to assess the contamination and to identify the potential source of metals. High variability has been observed for both dissolved and particulate phases in stream water with coefficient of variation (CV) ranging from 1.3 to 2.8. The highest metal concentrations in both phases were observed in Gunja for Ni and Cu, in Jungwang for Zn and Pb and in Shiheung for Cd, respectively. These results indicate that the different metal sources could be existing. The concentrations of the heavy metals in sediments decreased in the order of Cu>Zn>Pb>Cr>Ni>As>Cd>Hg, with mean of 2,549, 1,742, 808, 539, 163, 17.1, 5.8, 0.07 mg kg-1, respectively. Mean of metal concentrations (except for As) in sediments showed the highest values at Shiheung stream comparing with other streams. In sediments, the percent exceedance of class II grade that metal may potentially harmful impact on benthic organism for Cr, Ni, Cu, Zn, Cd, Pb was about 57%, 62%, 84%, 60%, 68%, 81% for all stream sediments, respectively. Sediments were classified as heavily to extremely polluted for Cu and Cd, heavily polluted for Zn and Pb, based on the calculation of Igeo value. About 59% and 35% of sediments were in the categories of “poor” and “very poor” pollution status for heavy metals. Given the high metal concentrations, industrial wastes and effluents, having high concentrations of most metals originated from the manufacture and use of metal products in this region, might be discharged into the stream through sewer outlet. The streams receive significant amounts of industrial waste from the industrial facilities which is characterized by light industrial complexes of approximately 17,000 facilities. Thus, the transport of metal loads through streams is an important pathway for metal pollution in Shihwa Lake.
        4,500원
        109.
        2019.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A lead-free bulk ceramic having a chemical formula Ba0.8Ca0.2(Ti0.8Zr0.1Ce0.1)O3 (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.
        4,000원
        110.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근 디지털 콘텐츠 중 E-Book과 웹 소설이 증가하고 있다. 삽화는 텍스트 콘텐츠에서 독자의 이해를 도울 수 있다. 따라서 텍스트 콘텐츠를 분석하여 자동으로 삽화를 생성하는 여러 접근방법이 등장했다. 먼저 규칙 기반 접근방법은 문장을 분석하는 규칙과 분석된 문장 구조를 삽화로 변환하는 규칙을 모두 활용하여 삽화를 생성한다. 그러나 정해진 규칙에서 벗어나면 삽화를 생성하지 못 할 수도 있다는 단점이 있다. 다음으로 통계 기반 접근방법은 통계를 기반으로 후보 중 가장 가능성이 높은 삽화를 생성한다. 그러나 통계 기반 접근방법은 사람이 추출한 정보에 강하게 의존한다는 단점이 있다. 본 연구는 사람이 아닌 시스템이 자동으로 정보를 추출하는 딥러닝을 활용한 삽화 생성 시스템을 제안한다. 제안하는 시스템은 형태소 분석기, 개체명 인식기, 의존 구문 구조 분석기로 이루어져있다. 동화 "빨간모자"를 통해 평가하였고, 총 99문장 중 삽화 생성이 가능한 문장이 28문장, 삽화 생성이 불가능한 문장이 71문장이었다. 삽화 생성이 불가능한 문장의 경우 대사가 41문장, 불명확한 주어가 2문장, 그리고 표현이 불가능한 서술어가 28문장이었다. 제안하는 시스템이 올바른 삽화를 생성한 문장은 23문장, 부적절한 삽화를 생성한 문장은 2문장, 삽화를 생성하지 않은 문장은 74문장으로 나타났다.
        4,000원
        111.
        2019.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061 three-layer clad sheet. Two AA6061 and one AA5052 sheets of 2 mm thickness, 40 mm width, and 300 mm length are stacked, with the AA5052 sheet located in the center. After surface treatment such as degreasing and wire brushing, sample is reduced to a thickness of 1.5 mm by multi-pass cold rolling. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at rolling speed of 6.0 m/sec. The roll bonded AA6061/AA5052/AA6061 complex sheet is then hardened by natural aging(T4) and artificial aging(T6) treatments. The microstructures of the as-roll bonded and age-hardened Al complex sheets are revealed by optical microscopy; the mechanical properties are investigated by tensile testing and hardness testing. After rolling, the roll-bonded AA6061/AA5052/AA6061 sheets show a typical deformation structure in which grains are elongated in the rolling direction. However, after T4 and T6 aging treatment, there is a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 sheets. The as roll-bonded specimen shows a sandwich structure in which an AA5052 sheet is inserted into two AA6061 sheets with higher hardness. However, after T4 and T6 aging treatment, there is a different sandwich structure in which the hardness of the upper and lower layers of the AA6061 sheets is higher than that of the center of the AA5052 sheet. The strength values of the T4 and T6 age-treated specimens are found to increase by 1.3 and 1.4 times, respectively, compared to that value of the starting material.
        4,000원
        112.
        2019.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The antioxidant activity, total phenol content, and inhibitory effect of xanthine oxidase (XOase) for six different medicinal plant complexes such as Achyranthes japonica, Acanthopanax sessiliflorus, Carthamus tinctorius, Eucommia ulmides, Viscum album, and Caragana koreana were investigated in this study. The free radical scavenging activity values using DPPH(2,2'-diphenyl-1-picrylhydrazyl) and ABTS[2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation] analyses were found to be 532.03±86.60 μg/mL and 1376.50±35.01 μg/mL, respectively, in 95% of ethanol extracts among six medicinal plant mixed compositions (6MPMC). The total phenolic content in 70% ethanol extract of 6MPMC was 125.19±1.34 mg GAE/g. The inhibitory activity against XOase was highest at 33.20±0.17% in the 70% ethanol extract of 6MPMC. In the antimicrobial activity test of 6MPMC, the minimum inhibitory concentration (MIC) value showed activities against V. litoralis and E. coli in 70% and 95% ethanol extracts, and these two microorganisms were created in clear zones by method of paper disc diffusion. These results suggest that the 6MPMC, composed of Achyranthes japonica, Acanthopanax sessiliflorus, Carthamus tinctorius, Eucommia ulmides, Viscum album, and Caragana koreana, have both antioxidant and antimicrobial activities and, therefore, may serve as a functional health food product.
        4,000원
        115.
        2019.04 구독 인증기관·개인회원 무료
        Three species, Luciola unmunsana and L. papariensis, endemic to Korea and L. tsushimana, endemic to Japan, have been taxonomically controversial whether they are independent or a single species for a long time. Therefore, we examined genetic diversity and evolutionary history of these species as well as including the related congeners using COI gene sequences (DNA barcoding region). Interestingly, we found seven paraphyletic groups from three species: two paraphyletic groups from L. papariensis, three paraphyletic groups from L. unmunsana and two paraphyletic groups from L. tsushimana. Among them, the group III of L. unmunsana collected from Jeolla-do province has never been recognized in the previous studies. A molecular clock analysis indicated that the origin of the major lineages of L. unmunsana, L. papariensis and L. tsushimana occurred between ~5.62 to 3.16 Ma. The origin of the major lineages of the group II and III of L. unmunsana, the group II of L. papariensis and the three groups of L. tsushimana occurred in 3.49 Ma (4.45–2.51 Ma, 95% HPD), which is consistent with the final disconnection of Japan from Korean Peninsula. The subsequent divergences of these paraphyletic groups clearly showed they have undergone allopatric speciation associated with geologic events in Korea and the sea level changes between Korea and Japan.
        116.
        2019.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        중증 급성 괴사성 췌장염은 높은 합병증 발생률과 사망률을 보인다. 급성 괴사성 고임이 4주가 지나면서 구역성 췌장 괴사로 발전하는데 합병증을 동반한 구역성 췌장 괴사는 치료를 필요로 한다. 최근에는 수술보다는 경피적 혹은 내시경을 통한 배액술과 괴사조직 제거술을 시행하고 있으며 특히 내시경초음파를 이용한 배액술의 발전으로 덜 침습적인 방법으로 보다 효과적인 치료가 가능해 졌다.
        4,000원
        117.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cryopreservation is mainly used for preservation of boar sperm. However, this method stresses the sperm by reactive oxygen species (ROS), and the conception rate and the litter size are not more efficient than the liquid preservation of spermatozoa. Therefore, we use chitosan which is a natural product derived antioxidant compound. We used GnHA (chitosan+hyaluronic acid) and GnHG (chitosan hydrogel) as chitosan complexes to cryopreserve boar sperm for improve sperm metabolism and function. Sperm parameter (sperm motility, progressive motility, path velocity, straight-line velocity, curvilinear velocity) is measured by computer-assisted sperm analysis (CASA) using frozen sperm with GnHA or GnHG (0, 0.25, 0.5, 1 mg/mL), respectively. Also, lipid peroxidation analysis using malondialdehyde (MDA) is performed to confirm the antioxidative effect of chitosan in frozen spermatozoa. CASA analysis showed GnHA and GnHG are effective against cryopreserved boar sperm. And antioxidant effect is measured by lipid peroxidation analysis. GnHA and GnHG, which is chitosan complex are effective for boar sperm cryopreservation by antioxidant effect.
        4,000원
        118.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        수용성 비이온고분자인 Polyvinylalcohol (PVA), Polyvinylpyrrolidone (PVP), Hydroxypropyl cellusoe (HPC)와 iodine과의 착물 형성에 대한 계면활성제의 영향을 알아보기 위해 Sodiumdodecylsulfate을 포함하는 수용액에서 이들 사이의 반응을 수행하였다. PVP와 HPC에서 tri-iodide band의 적색 이동에 의하여 착물이 만들어졌다는 것을 알게되었고, PVA-iodine 착물에서는 500 nm 부근에서 고유의 특색있는 띠를 나타내었다. SDS 계면활성제의 존재는 PVA-iodine 착물의 파괴를 가져왔고, 고유의 푸른색도 사라지게 만들었다. 그러나 SDS 단량체는 PVP, HPC와 iodine의 착물 형성을 도와주는 경향을 나타내었다. 고분자 용액에서 겔이 만들어지는 것을 방해하는 n-propanol은 고 분자-iodine 착물이 형성되는 것을 도와주었다. SDS가 있을 때와 없을 경우의 영향을 알아보기 위해 순 수한 HPC와 HPC-iodine 착물을 만들고 이들의 성질을 조사하였다.
        4,000원
        119.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        우리는 오리온 분자운 복합체의 북부 필라멘트(이하 NF)에 대하여 12CO (J=1-0) 분자선의 자료를 이용하여 은하 평면이 분자의 운동과 운동학에 미치는 영향을 연구하였다. 6 m 서울대학교 전파망원경(Seoul Radio Astronomy Observatory, SRAO)을 이용하여 2arcmin 공간분해능으로 은하면으로부터 먼 순서로 NF1, NF2, NF3 세 곳을 총 270시간 동안 관측된 자료를 사용하였다. 은하면과 OMC NF는 12CO (J=2-1) 경우 3% 밀도에서, 티끌의 경우 9% 밝기 수준에서 자기장을 따라 서로 연결되어 있었다. 12CO (J=1-0), 12CO (J=2-1), 성간 티끌 관측결과를 비교해본 결과, 세 경우 모두 NF3에서는 고루 분포했지만, NF1과 NF2에서는 비교적 밀도가 높은 특정 영역에서만 함께 나타났다. NF는 단일 구조를 보였으며, NF1에서는 부분 수축 운동을, NF2에서는 하단에서 회전 운동이 나타났고, NF3에서는 유일하게 명확히 자기장에 연관된 나선형 회전이 보였다. 위치-속도 분석 결과, 12CO (J=1-0)를 비롯한 물질들은 NF2와 NF3을 따라 은하면을 향하여 흐를 가능성이 있음을 확인할 수 있었다. 은하면을 향하여 물질이 흐르는 명백한 원인을 이번 연구결과에서 볼 수 없었지만 추후의 더 정교한 관측결과가 NF1과 NF2 상단부의 회전 운동을 확인 할 수 있겠다.
        4,600원