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        검색결과 9,912

        2541.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The fuel used in this study, DMM is an oxygen additive containing 42.5% oxygen by weight and dissolved in diesel fuel, also known as methyl alcohol or Dimethoxymethane (CH3-O-CH2-O-CH3). DMM, which is a colorless liquid, shows chemical characteristics of gas-liquid and is also used as a diesel fuel component. In this study, five mixtures were added to the common diesel fuel at DMM addition rates of 2.5, 5, 7.5, 10 and 12.5% by volume. A single cylinder, four strokes, DI diesel engine was used as the test engine. Experimental data were also collected at 24 engine speed-load conditions operating in steady state. The purpose of this experiment was to study the effect of the addition ratio of oxidized fuel mixed in diesel fuel on engine power and exhaust performance. When compared with the common diesel fuel, the exhaust of Smoke was substantially reduced in all DMM mixing ratios. These results indicate that DMM can be an effective blend of diesel fuel and is an environmentally friendly alternative fuel. This study also shows that smoke and NOx emissions can be reduced at the same time through the application of oxygen fuel and EGR.
        4,000원
        2542.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The spray characteristics of two working fluids operating with a bi-fuel injector were investigated. A bi-fuel injector simultaneously sprays two working fluids, both of which possess different properties. An effervescent atomizer containing two separated aerator tubes was employed as the bi-fuel injector. Vegetable oil and kerosene were the working fluids. The mixing ratio and ALR were the experimental parameters. The mixing ratio is the mass fraction of vegetable oil in the total amount of working fluids. The ALR represents the ratio of the atomizing gas to the working fluid mass flow ratio. In order to examine spray characteristics, the spray angle, droplet size distribution, cumulative volume fraction, Sauter Mean Diameter and span factor were measured using a high resolution video camera and a Laser Diffraction Particle Analyzer. From the experimental results, spray angle is decreased with as the ratio of kerosene to vegetable oil in working fluid is increased. Regardless of ALR, SMD was the smallest when the only working fluid was kerosene and uniformity was the most stable when the only working fluid was vegetable oil.
        4,000원
        2543.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study conducted finite element analysis in advance to understand the natural frequency, con-ducted static structural analysis and analyzed stress behavior occurring on the boundary of wheel and rail when passing the straight line and curve line. According to the FEA, the wheel had natural frequency of 1st mode 238.4Hz to 10th mode 1,320Hz, and the rail had natural frequency of 457.4Hz to 619.7Hz. When looking at the correlated frequency range, the natural frequency of 4th~6th mode of wheel and 3rd~9th mode of rail track were correlated. As for the result of stress behavior translation occurring on the boundary of wheel and track, it was 53.4MPa when passing the curve line, which was 16MPa higher than when passing the straight line.
        4,000원
        2544.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 폴 멀둔의 시에 나타난 유희적인 비가풍 회상을 두 가지 방식, 즉 어두운 유머와 연상기법을 중심으로 고찰하는 것이다. 멀둔은 어두운 유머를 통해 당대의 존재론적, 역사적, 정치적 위기상황을 보여준다. 그는 심각한 멜랑 콜리 정서만을 유지하지는 않는데, 전통적인 비가에서처럼 화자가 주변 환경과 정서적인 거리를 좁히지 않을 뿐만 아니라, 근대 비가에서처럼 멜랑콜리의 심연에 무력하게 빠지지도 않는다. 멀둔이 보여주는 멜랑콜리와 유머의 특이한 결합은 그가 선택한 미묘한 단어, 암호말, 기표 유희 등의 연상기법을 통해 이뤄지고, 이는 대상과 상황 사이에 긴장을 일으켜 의미화 작용의 한계에 이른다. 멀둔은 20세기 후반 격동기를 애 도하면서 추적 가능한 애도의 감정들이 기표의 유희 속으로 급속히 표류하게 하여 충격적인 역사로부터 유머러스한 거리를 유지한다.
        6,400원
        2545.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to offer basic data on cosmetics by investigating college women’s purchasing and use behaviors regarding cosmetics according to their experience with side effects. A questionnaire was administered to 351 college women in the Seoul and Kyoung-in areas. The data were analyzed with SPSS Statistics V22.0 using frequency, χ2-test, and t-test. The results are as follows. First, 72.6% of surveyed women reported experiencing side effects from cosmetics. The largest side effects were acne and boils, and the primary ways of coping with these side effects were discontinuing use and using other products. Second, the group that experienced cosmetics’ side effects used brands that were more expensive and eco-friendly than the group without side effects. Third, the group that experienced side effects continued to use the product more than the group without side effects. The primary reason for continued use was efficacy, and the reasons for discontinued use were efficacy and curiosity. Fourth, the side-effects group proactively identified cosmetics ingredients more than the non-side-effects group. Specifically, they checked the major components, the function, and for any hazardous ingredients. Fifth and finally, 98.3% of survey respondents purchased and used functional cosmetics. The group that had experience with side effects used more functional cosmetics than the group without side effects.
        4,300원
        2546.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Eurytoma maslovskii conduces the unexpected plum dropping. It stayed overwinter inside the pits of the dropped plums and able to oviposit on plum surface when the diameter of the plums are over 16 mm prior to endocarp hardening. To control this harmful pests is too much essential to plum orchard. Therefore, the plum seed crusher (PSC) was designed and developed according to the purpose of perishing the pests through destroying the dropped plums. The rocks and the weeds were removed from the plum orchard prior to the test. Manually operated plum seed crusher picked-up the dropped plums from the ground and crushed them. The performance of PSC was evaluated by applying 2.5 and 3.0 km/h travelling speeds, and controlling the gaps; 18, and 28 mm intervals between plum pick-up discs. The test result showed the plum pick-up rate was 98±2.0%, and 92±5.3% with the machine travelling speed of 3.0 km/h in laboratory. Further, it changed to 95±8.7%, and 93±5.8% when the travelling speed was used 2.5 km/h. In both cases of test plum pick-up discs were maintained 18 mm, and 28 mm gap intervals, respectively. Furthermore, in field conditions, pursuing to similar gap intervals, the plum pick-up rate was 94±4.0%, and 92±2.0% with the speed of 3.0 km/h albeit it showed 92±4.0%, and 90±3.5% when the speed was decreased to 2.5 km/h. The maximum plum pick-up rate was found at 18 mm disc intervals with 3.0 km/h travelling speeds. The crushing teeth were selected 8 mm in height by repeated test to destroy the plum seeds. The result showed 100% crushing efficiency was facilitated to entire tests at 280 RPM crushing speeds regardless of plum sizes and shapes. This machine is preferred for the farmers to control the damage of plums by preventing the propagation of the identified pests.
        4,000원
        2547.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Low cost and scalable manufacturing of highly doped cellulose for enhanced multifunctional applications is still an issue. In this work, eco-friendly nanocomposites were fabricated by incorporating regenerated cellulose (RC) of 10, 30, and 50 wt% into an exfoliated graphene nanoplatelets (GNPs), resulting in the intercalation of GnPs. The thermal and electrical properties of hybrid nanocomposites were investigated. The structural property was conducted through scanning electron microscope and X-ray diffraction analyses. Strong frequency-dependent dielectric response was found due to the change of the permittivity and the loss tangent of nanocomposites by different content of RC, which is associated with the polarizations behavior. Non-elastic relaxation at the GNPs–RC chains interfacial areas in an alternating field was identified as the main cause of polarization losses among others. Detailed ferroelectric measurements provided the evidence of the ideal resistive behavior of the nanocomposites, which are confirmed by the resistivity measurements along the out-of-plane direction of the nanocomposite sheets.
        4,000원