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        검색결과 7

        1.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Benzene, toluene, ethylbenzene, and xylenes are commonly known as (BTEX) and include volatile organic compounds (VOCs) in ambient air. Exposure to some BTEX has been associated with health risks. This study aimed to reduce BTEX on the environment and human health dramatically. This research targeted decreasing the BTEX in an air environment by producing high surface area activated carbon (KA-AC) under optimized synthesis conditions from Ricinus communis as lignocellulosic waste using ZnCl2 solution, respectively. The influence of several activation parameters was investigated on the surface area, such as impregnation ratio, carbonization time, and carbonization temperature. The KA5-AC prepared under optimized conditions showed BET surface area and total pore volume of 1225 m2/ g, and 0.72 cm3/ g, respectively. The optimized synthesis conditions were as follows: 0.1, 0.5, 1, 2, and 5 M impregnation ratio, 450–950 °C carbonization temperature, and 100 min carbonization time. The characteristics of the optimized KA-AC were analyzed using nitrogen adsorption–desorption isotherm, scanning electron microscopy, and pore structural analysis. The results confirmed that the VOCs adsorption on KA-AC followed a monolayer adsorption isotherm over a homogeneous adsorbent surface. It showed the removal efficiency of benzene, toluene, ethylbenzene, and m, p-xylene (R2 = from 0.991 to 0.997). Moreover, the KA-AC exhibited good performance without considerable loss of efficacy throughout the experiments. Accordingly, it is concluded that developing low-cost activated carbon to use BTEX vapor adsorption research could be practical and developments to overcome for utilization in air pollution control.
        4,000원
        2.
        2022.05 구독 인증기관·개인회원 무료
        The International Atomic Energy Agency recommends the deep geological disposal system as one of the disposal methods for high-level radioactive waste (HLW), such as spent nuclear fuel. The deep geological disposal system disposes of HLW in a deep and stable geological formation to isolate the HLW from the human biosphere and restrict the inflow of radionuclides into the ecosystem. It mainly consists of an engineered barrier and a natural barrier. Safety evaluation using a numerical model has been performed primarily to evaluate the buffer’s long-term stability. However, although the gas generation rate input for long-term stability evaluation is the critical factor that has the most significant influence on the long-term hydraulic-mechanical behavior of the buffer, in-depth research and experimental data are lacking. In this study, the gas generation rate on the interface between the disposal canister and the buffer material, a component of the engineered barrier, was mainly studied. Gas can be generated between the disposal canister and the buffer material due to various causes such as anaerobic corrosion of the disposal canister metal, organic matter decomposition, radiation decomposition, and steam generation due to high temperature. The generation of gas in such a disposal environment increases the pore gas pressure in the buffer and causes internal cracks. The occurred cracks increase the intrinsic permeability of the buffer, which leads to a decrease in the primary performance of the buffer. For this reason, it is essential to apply the appropriate gas generation rate according to the disposal condition and buffer material for accurate long-term stability analysis. Therefore, the theoretical models regarding the estimation of gas generation were summarized through a literature study. The amount of gas generated was estimated according to the disposal environment and material of the disposal canister. It is expected that estimated values might be used to estimate the long-term stability analysis of buffer performance according to the disposal condition.
        4.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present 12CO (2-1) data for four spiral galaxies (NGC 4330, NGC 4402, NGC 4522, NGC 4569) in the Virgo cluster that are undergoing different ram pressure stages. The goal is to probe the detailed molecular gas properties under strong intra-cluster medium (ICM) pressure using high-resolution millime- ter data taken with the Submillimeter Array (SMA). Combining this with Institut de RadioAstronomie Millimetrique (IRAM) data, we also study spatially resolved temperature and density distributions of the molecular gas. Comparing with multi-wavelength data (optical, Hi, UV , Hα), we discuss how molecular gas properties and star formation activity change when a galaxy experiences Hi stripping. This study suggests that ICM pressure can modify the physical and chemical properties of the molecular gas sig- nificantly even if stripping does not take place. We discuss how this affects the star formation rate and galaxy evolution in the cluster environment.
        3,000원
        5.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recognition of the role of radio galaxies in the universe has been increasing in recent years. Their colossal energy output over huge volumes is now widely believed to play a key role not only in the formation of galaxies and their supermassive black holes, but also in the evolution of clusters of galaxies and, possibly, the cosmic web itself. In this regard, we need to understand the in ation of radio bubbles in the hot gas atmospheres of clusters and the importance of the role that radio galaxies play in the overall energy budget of the intracluster medium. Here, we present results from X-ray and radio band observations of the hot gas atmospheres of powerful, nearby radio galaxies in poor clusters.
        4,000원
        7.
        2015.04 KCI 등재 서비스 종료(열람 제한)
        This study was conducted to determine the effects of mixed Korean red ginseng marc with aluminum sulfate on gas concentration and volatile fatty acid (VFA) in poultry litter during 4 weeks in terms of livestock and environment managements. A total of 240 broiler chicks were randomly allocated to four treatments in four replications and 15 birds per replicate. The four treatments was mixed to rice hull under each pen at 0, 10 g or 20 g red ginseng marc + 90g aluminum sulfate, and 100g aluminum sulfate per kg poultry litter (rice hulls). Carbon dioxide, methane, acetic acid, and propionic acids were measured weekly. The results that could be available include: First, during the experimental period, carbon dioxide emissions were not remarkably different among treatments. Second, no differences were observed among treatments in methane emissions at 2 weeks through 4 weeks, but at 1 week, the reduction in methane emissions was in following order: 100 g aluminum sulfate > 20 g red ginseng marc + 90 g aluminum sulfate > 10 g red ginseng marc + 90 g aluminum sulfate > control. Third, in spite of statistically differences, treatment with 10 g or 20 g red ginseng marc + 90g aluminum sulfate, and 100g aluminum sulfate reduced acetic acid and propionic acid as a function of time, except acetic acid in aluminum sulfate treatment at 2 and 4 weeks. In conclusion, the results indicated that like aluminum sulfate, using 10 g or 20 g red ginseng marc with aluminum sulfate was effective in decreasing methane and propionic acid released from poultry litter.