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        검색결과 50

        1.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research has been conducted to design upright parts of hand-made vehicles with the purpose of reducing material and machining cost while ensuring structural safety. Aluminum knuckles were modelled with three parts in order to enhance design flexibility as well as to reduce CNC machining cost. A vehicle model was constructed in CAD program and simulated in ADAMS View in order to estimate joint forces developing during 20 degree step steering condition at 60km/h. The joint forces obtained in the vehicle dynamics simulation were used for the structural analysis in ANSYS and dimensions of knuckle parts were adjusted until the lowest safety factor reached 2.0. The weight of knuckle decreased by 50% compared to the previous version that was designed without the structural analysis. The overall manufacturing cost decreased by 33% due to the reduction in the material as well as the CNC machining effort.
        4,000원
        16.
        2013.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An experiment was conducted to study effects of abomasal infusions of casein, glucose or starch on milk production and blood metabolites in dairy cows. Four lactating cows (559±41.9kg) fitted with 100 mm ruminal cannulas were used in a 4 × 4 Latin square experiment. The cows were given access ad libitum to grass silage and received 6.2 kg dry matter (DM) of a mixture of rapeseed meal (5.3kg/d DM) and barley grain (0.9kg/d DM) as a basal diet (CON), the basal diet plus intra-abomasal infusions of 270 g sodium caseinate (CAS), 300 g of glucose (GLU) or 243 g of starch (STA) starting at 09:00 h each day. Abomasal infusion of different nutrients did not affect (p>0.05) grass silage intake and rumen fermentation parameters (rumen pH, ammonia N and volatile fatty acids). As unexpected, milk yield and composition data did not differ between CON and the treated groups (p>0.05). Most of plasma amino acids were not significantly (p>0.05) affected by the abomasal infusions of CAS, GLU or STA except for histidine, tryptophan and glycine. Although histidine, known as the first limiting amino acid in dairy cows fed grass silage based diets, was significantly (p=0.003) increased by CAS, we failed to result in a clear increase in milk yield and protein yield. This discrepancy between plasma AA profiles and milk production could be presumably explained by relatively high concentration of total amino acids in the present study (2,039μmol/l).
        4,000원
        17.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, national attention on the regulations for carbon dioxide emission has risen. Thus, diverse attempts are being actively carried out to reduce the resistance of ships and to develop a new propelling system that reduces the emission of carbon dioxide. This study presents to induce a way to utilize the generated wind power for the electrical energy source of a ship’s lighting, air conditioning and heating by installing a compact wind power facility on the experiment target; a small size high-speed vessel. The vessel targeted for application is a 30ft high-speed leisure boat made of aluminum alloy. The wind power facility installed on the hull and the batteries that will be charged by the electric energy generated by the wind power system were considered at the designing stage of the boat. A new presumption equation for air resistance of wind turbines and efficient measures for management are suggested based on a model test that verifies the basic performance of the wind-powered leisure boat.
        4,000원
        18.
        2012.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The demand of energy is increasing around the world due to the high dependency of our society on energy. So the worldwide recognition of the limited supply of fuels has led to a large scale effort in search of alternative energy sources. Biodiesel has been considered as an alternative fuel to the petroleum diesel in compression ignition engines and is receiving more and more attention. Biodiesel can be obtained by the transesterification of methanol with triglycerides, with glycerin as by- product. This paper introduces the transesterification reaction of lard oil with methanol in the presence of hexane as solvent and potassium hydroxides as catalyst. Different from other researches, a new method to analyze the reaction process in this research was developed by starting with the by-product, crude glycerin. This new method was verified and the effects of various parameters such as solvent, molar ratio of methanol to oil (3:1-12:1), catalyst concentration (0.5-4 wt%) on the traneseterification process were investigated. Molar ratio of methanol to oil was optimized and identified to be 8:1, catalyst concentration of 2 wt% with hexane as solvent and at a temperature of 57℃ were found to be optimum for the reactions. Under this condition for 4 hours, the production yield can be 96.95%.
        4,000원
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