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        검색결과 11

        1.
        2024.03 구독 인증기관·개인회원 무료
        본 연구는 2011년에 개발된 한국형 포장설계법(KPRP)이 국내 도로포장 분야에서 어떻게 활용되고 있는지를 조사하며, 특히 JCP(적층 콘크리트 포장) 설계에 중점을 두고 다양한 해외 포장설계 프로그램과의 비교를 수행하였다. 이를 위해 AASHOTO Ware와 같은 국제적으로 인정받고 빈번히 활용되는 해외 프로그램을 선택하여 두 프로그램 간의 차이점을 파악하고자 했다. 비교 대상으로 선정된 AASHOTO Ware는 미국에서 개발된 프로그램으로, 차량 분류 및 기후데이터 활용과 관련하여 KPRP와는 다른 특징을 보인다. AASHOTO Ware는 차량을 16종으로 분류하는 반면, KPRP는 12종으 로 분류하며, 특히 화물차량에 대한 상세한 분류 기준을 가지고 있다. 또한, AASHOTO Ware는 실시간 기후데이터를 인터넷 기반으로 활용하는 반면, KPRP는 기상대에서 축적한 데이터를 사용한다. 두 프로그램 간의 Input 값은 기후데이 터와 교통량 데이터 중 차량 분류를 중심으로 비교하였다. 향후에는 AASHOTO Ware의 설계로직을 분석하여 더욱 세 밀한 비교를 진행하고, 두 프로그램의 설계 전이함수와 로직을 분석하여 KPRP 프로그램의 발전에 기여하는 것이 이 연 구의 최종 목표이다. AASHOTO Ware의 유연한 최종IRI값 설정과 상세한 차량 분류 기준은 KPRP의 발전 가능성을 탐 구하는 데 중요한 지표로 활용될 것으로 예상된다.
        5.
        2023.01 KCI 등재 서비스 종료(열람 제한)
        The advanced oxidation treatment using persulfate and zero-valent iron (ZVI) has been evaluated as a very effective technology for remediation of soil and groundwater contamination. However, the high rate of the initial reaction of persulfate with ZVI causes over-consumption of an injected persulfate, and the excessively generated active species show a low transfer rate to the target pollutant. In this study, ZVI was modified using selenium with very low reactivity in the water environment with the aim of controlling the persulfate activation rate by controlling the reactivity of ZVI. Selenium-modified ZVI (Se/ZVI) was confirmed to have a selenium coating on the surface through SEM/EDS analysis, and low reductive reactivity to trichlroethylene (TCE) was observed. As a result of inducing the persulfate activation using the synthesized Se/ZVI, the persulfated consumption rate was greatly reduced, and the decomposition rate of the model contaminant, anisole, was also reduced in proportion. However, the final decomposition efficiency was rather increased, which seems to be the result of preventing persulfate over-consumption. This is because the transfer efficiency of the active species (SO4-∙) of persulfate to the target contaminant has been improved. Selenium on the surface of Se/ZVI was not significantly dissolved even under oxidation conditions by persulfate, and most of it was present in the form of Se/ZVI. It was confirmed that the persulfate activation rate could be controlled by controlling the reactivity of ZVI, which could greatly contribute to the improvement of the persulfate oxidation efficiency.
        6.
        2022.02 KCI 등재 서비스 종료(열람 제한)
        Heavy metal contaminations were investigated in fishes inhabiting the basins of Andong, Imha and Yeongju dam basins along the upper stream of the Nakdong river. The characteristics of heavy metals contamination in fish were investigated based on sampling sites located in the Andong dam basin. The muscle tissue was analyzed for 267 objects of 26 species from the Andong dam, 50 objects of 17 species from Imha dam, 38 objects of 9 species fromYoungju dam basin.The type and amount of heavy metals concentrated in the body of the fishes was found to be species-dependent. The heavy metal species which contamination increase through the Seokpo smelter are chromium, zinc, cadmium, and lead, and these are very likely the influence of the smelter. The concentration of eight heavy metals in fish from the Andong dam basin was higher than that in fish from the Imha and Youngju dam basins; the values for zinc, arsenic, and cadmium were significantly higher. However, mercury and lead exhibited high values in the Imha and Yeongju dam basins, respectively.
        7.
        2022.01 KCI 등재 서비스 종료(열람 제한)
        Environmental contamination by organic compounds are not only restricted to water, but extends to soil and groundwater as well. However, highly oxidized compounds, such as halogenated organics and nitro-compounds, can be detoxified employing reducing methods. Permeable reactive barrier is one of the representative technologies where zero-valent metals (ZVMs) are employed for groundwater remediation. However, organics contaminates often contaminate the unsaturated zone above the groundwater. Despite the availability of technologies like soil vapor extraction and bioremediation, removing organic compounds from this zone represents several challenges. In this study, the reduction of nitrobenzene to aniline was achieved using zero-valent iron (ZVI) under unsaturated conditions. Results indicated that the water content was an important variable in this reaction. Under dry conditions (water content = 0.2%), the reduction reaction was inhibited; however, when the water content was between 10% and 25% (saturated condition), ZVI can reduce nitrobenzene. Palladized iron (Pd/Fe) can be used to reduce nitrobenzene when the water content is between 2.5% and 10%. The reaction was evaluated over a wide range of temperatures (10 – 40 °C), and the results indicated that increasing the temperature resulted in increased reaction rates under unsaturated conditions.
        8.
        2021.12 KCI 등재 서비스 종료(열람 제한)
        Organic contaminants can be released into water environments due to chemical accidents and exist as dissolved and non-aqueous phase liquids (NAPL). Fenton oxidation was tested for bisphenol A and nitrobenzene as model organic contaminants in dissolved and NAPL states. Fenton oxidation was successfully applied for both of the dissolved and NAPL states of the two pollutants and the results indicated that a quick treatment was needed to reduce the risk from a chemical accidents instead of carrying out oxidation after the contaminants dissolve in water. A set of Fenton reactions were tested under seawater conditions because chemical accidents often occurs in the ocean. Chloride ions act as radical scavengers and inhibit Fenton oxidation. The reaction rate is inversely proportional to salt contents and the reduced reaction rate can be compensated by increasing the quantity of the oxidizing agents. The current study showes that Fenton oxidation could be applied as a quick treatments for organic contaminant in dissolved and NAPL state organic contaminants released as a result of leaks or chemical accidents.
        9.
        2020.12 KCI 등재 서비스 종료(열람 제한)
        In this study, the applicability of reduction-oxidation-linked treatment was evaluated for nitrobenzene and a by-product by analyzing the reaction kinetics. Nitrobenzene showed very low reactivity to persulfate that was activated using various methods. Nitrobenzene effectively reacted through the reduction process using Zero-Valent Iron (ZVI). However, aniline, a toxic substance, was produced as a by-product. Reduction-oxidation-linked treatment is a method that can allow the oxidative degradation of aniline after reducing nitrobenzene to aniline. The experimental results show improved reactivity and complete decomposition of the by-product. Improved reactivity and decomposition of the by-product were observed even under conditions in which the reduction-oxidation reaction was induced simultaneously. No activator was injected for persulfate activation in the process of reducing oxidant linkage, and the activation reaction was induced by ferrous iron eluted from the ZVI. This indicates that this method can be implemented relatively simply.
        10.
        2020.01 KCI 등재 서비스 종료(열람 제한)
        Oxidative degradation of phenol, three monochlorophenols (2-chlorophenol, 2-CP; 3-chlorophenol, 3-CP; 4-chlorophenol, 4-CP), four dichlorophenols (2,3-dichlorophenol, 2,3-DCP; 2,4-dichlorophenol, 2,4-DCP; 2,5-dichlorophenol, 2,5-DCP; 2,6-dichlorophenol, 2,6-DCP), and two trichlorophenols (2,4,5-trichlorophenol, 2,4,5-TCP; 2,4,6-trichlorophenol, 2,4,6-TCP) was conducted with heat activated persulfate. As the number of chlorinations increased, the reaction rate also increased. The reaction rate was relatively well fitted to the zero-order kinetic model, rather than the pseudo-first order kinetic model for the reactions at 60℃, which can be explained by insufficient activation of the persulfate at 60℃, and the oxidation reaction of 2,4,6-TCP at 70℃ was relatively well fitted to the pseudo-first order kinetic model. The oxidation reaction rate generally increased with increase of persulfate concentration in the solution. 2,6-dichloro-2,5-cyclohexadiene-1,4-dione was found as a degradation product in a GC/MS analysis. This compound is a non-aromatic compound, and one chlorine was removed. This result is similar to the result of previous studies. The current study proved that heat activated persulfate activation could be an alternative remediation technology for phenol and chlorophenols in soil and groundwater.
        11.
        2017.11 KCI 등재 서비스 종료(열람 제한)
        Oxidative degradation of chlorinated ethenes was carried out using heat-activated persulfate. The activation rate of persulfate was dependent on the temperature and the activation reaction rate could be explained based on the Arrhenius equation. The activation energy of persulfate was 19.3 kcal/mol under the assumption that the reaction between the sulfate radical and tricholoroethene (TCE) is very fast. Activation could be achieved at a moderate temperature, so that the adverse effects due to high temperature in the soil environment were mitigated. The reaction rate of TCE was directly proportional to the concentration of persulfate, indicating that the remediation rate can be controlled by the concentration of the injected persulfate. The solution was acidized after the oxidation, and this was dependent on the oxidation temperature. The consumption rate of persulfate was high in the presence of the target organic, but the self-decomposition rate became very low as the target was completely removed.