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        검색결과 3,224

        661.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES: The object of this study is to select appropriate inorganic materials, and find the best mixing formula to secure fast curing time and enough initial strength, and then to evaluate the durability of the asphalt mixtures according to the degree of addition of the compound manufactured by the determined blending ratio. METHODS : The breaking time and reactivity between seven kinds of inorganic minerals, and the selected recycled aggregate and emulsified asphalt were compared to determine the best initial curing strength for the mixtures. Then, three inorganic materials were chosen as the materials that provide good breaking time and reactivity, and the best mixing formula for the three materials was determined. The chemical composition of the compound manufactured using the mixing formula was analyzed by energy dispersive x-ray system method. Finally, indirect tensile strength (ITS) test was performed (for two days) at room temperature to determine the proper amount of additives that will provide the best initial strength. RESULTS: From the results of the reactivity test, the best mixing formula (A:C:G = 60:30:10) for the three selected inorganic materials with short braking time and high reactivity was determined. The four types of cold reclaimed asphalt mixtures for ITS testing were manufactured by adding the inorganic material compounds at 0%, 3%, 5%, and 7%, and the ITS values were measured after two curing days. The ITS values at 5% and 7% were 0.308 MPa and 0.415 MPa, respectively. The results of quality control tests (Marshall stability, porosity, flow value, etc.) at 5% and 7% satisfied the specification criterion for the cold recycled asphalt mixtures. CONCLUSIONS : The selected inorganic materials (A, C, and G) and the best mixing formula (A:C:G = 60:30:10) accelerated the reaction with emulsified asphalt and shortened the curing time. Depending on the inorganic material used, the breaking time and reactivity can be directly related or unrelated. This is because of the chemical compositions of recycled aggregates, infiltrated foreign matter, and chemical reactions between the inorganic materials and other materials. Therefore, it is important to select the proper materials and the best mixing formula when evaluating the characteristics of the practically used materials such as recycled aggregates, inorganic materials, and emulsified asphalt.
        4,000원
        662.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The performance of pavements is decreased by reduced bearing capacity, deterioration, and distress due to complex loading conditions such as traffic and environmental loads. Therefore, the proper maintenance of pavements must be performed, and accurate evaluation of pavement conditions is essential. In order to improve the accuracy of the heavy weight deflectometer (HWD), which is a nondestructive evaluation method, the correlation between HWD test results and temperature factors were analyzed in this study. METHODS : The HWD test was conducted five times for one day on airport concrete pavement, and the ambient temperature, surface temperature, and slab internal temperature were collected. Since the slab internal temperature was nonlinear, it was replaced by the equivalent linear temperature difference (ELTD). The correlation between the HWD test results and each temperature factor was analyzed by the coefficient of correlation and coefficient of determination. RESULTSAND: The deflection of the slab center, mid edge, and corner, and impulse stiffness modulus (ISM) showed significantly high correlation with each temperature factor, especially the ELTD. However, the load transfer Efficiency (LTE) had very low correlation with the temperature factors. CONCLUSIONS : It is necessary to analyze the effect of aggregate interlocking on LTE according to the overall temperature changes in slabs by conducting seasonal HWD tests. It is also necessary to confirm the effect of seasonal temperature changes on deflection and ISM.
        4,300원
        663.
        2018.12 구독 인증기관 무료, 개인회원 유료
        본 연구는 수온, 염분, 사육밀도 및 혼합 먹이생물 공급량과 같은 환경요인이 왕우럭 Tresus keenae의 유생사육 시 생존 및 발생에 미치는 영향을 조사하기 위하여 수행하였다. 연구 결과, 왕우럭 유생사육의 최적 조건은 수온 20℃에서 24℃, 염분 30 psu, 사육밀도 1 ml당 5개체 및 먹이생물 I. galbana, C. simplex 및 T. suecica 혼합 공급량 10×104 세포/ml이였다. 본 연구 결과 를 통해 밝혀진 왕우럭 유생 최적의 사육 환경요인은 빠른 성장 및 높은 생존을 통해 생산성 향상에 기여하리라 생각된다.
        4,000원
        664.
        2018.12 구독 인증기관 무료, 개인회원 유료
        수온의 변화는 어류의 거의 모든 생리학적 부분에 영향을 미친다. 기후 변화로 인한 수온의 상 승은 어류에게 물리적 피해를 줄 수 있다. 이 연구는 최적의 수온(15°C)보다 높은 수온(20°C)에 서의 대서양 연어의 건강상태를 평가하기 위해 수행하였다. 간 조직은 열 적응에 중요한 대사 기능을 발휘하기에 본 연구에 간 조직을 사용하였다. 생체지표유전자의 개발을 위한 분석 방법 으로는 NGS RNAseq 방법을 사용하였고, 생체지표유전자의 발현 양상을 관찰하기 위한 분석 방 법으로는 RT-qPCR을 사용하였다. NGS RNAseq 분석을 통해 1,366개의 차별적 발현 유전자를 확인하였으며, 그 중에서 880개의 증가하는 유전자와 486개의 감소하는 유전자를 확인하였다. 생체지표유전자로는 heat shock protein 90 alpha (Hsp90α), heat shock protein 90 beta (Hsp90β) 및 cytochrome P450 1A (CYP1A)을 선정하였는데 이들 유전자는 NGS RNAseq 분석에서 수온의 변화에 민감하게 반응하는 유전자들이었다. 이들 유전자의 RT-qPCR을 통한 발현 양상은 NGS RNAseq 분석과 유사하게 나타났다. 이 연구의 결과는 다른 어종에도 적용할 수 있으며, 산업 적으로도 유용하다고 생각된다.
        4,000원