한정된 자원과 환경보호에 대한 중요성이 점차 증가됨에 따라 제품을 회수하여 재사용하는 회수물류가 기업업체의 관심을 끌기 시작하였다. 이러한 문제점을 인식하여 회수가능하며 회수 시 부피를 줄여서 회수비용을 절감할 수 있는 회수용 접이식 플라스틱 박스의 개발이 본격화 되고 있다. 본 논문에서는 회수용 접이식 플라스틱 박스의 재사용 네트워크의 모델을 제안하고, 수치실험을 통해 제안한 모델의 최적을 구하여 이 모델의 적합성과 실용성을 검증하고 이에 근거하여 최적의 운영책을 제시하였다.

The particle size of MgO was examined as a function of the Na content in Mg(OH)2 powders and the calcination temperature. Mg(OH)2 suspension was obtained by dropwise precipitation of Mg(NO3)2·6H2O and NaOH solutions. The suspension was diluted by varying the dilution volume ratio of distilled water to Mg(OH)2 suspension to change the Na salt concentration in the suspension. Mg(OH)2 slurry was filtered and dried at 60˚C under vacuum, and then its Mg(OH)2 powder was calcined to produce MgO with different amount of Na content at 500~900˚C under air. Investigation of the physical and chemical properties of the various MgO powders with dilution ratio and calcination temperature variation was done by X-ray diffraction, transmission electron microscopy, BET specific surface area and thermal gravimetric analysis. It was observed that MgO particle size could depend on the condition of calcination temperature and dilution ratio of the Mg(OH)2 suspension. The particle size of the MgO depends on the Na content remaining in the Mg(OH)2 powder, which powder was prepared by changing the dilution ratio of the Mg(OH)2 suspension. This change increased as the calcination temperature increased and decreased as the dilution ratio increased. The growth of MgO particle size according to the increase of temperature was more effective when there was a relatively high content of Na. The increase of Na content lowered the temperature at which decomposition of Mg(OH)2 to MgO took place, thereby promoting the crystal growth of MgO.

연구는 표고 760 m 지역인 강원도 평창군 대관령면에 위치한 국립축산과학원 한우시험장에서 2009년부터 2010년까지 2년간 기후조건과 사일리지용 옥수수의 생육특성과 생산량의 관계를 검토하였다. 파종에서 수확기까지의 평균 최저기온은 2009년에 , 2010년에는 였고 평균최고기온은 2009년 , 2010년 였다. 평균기온은 2009년 , 2010년 였다. 일조시간은 2009년도 711.3시간, 2010년 663.8시간이었고 강수량은 2009년 893.

Magnesium hydroxide-melamine core-shell particles were prepared through the coating of melamine monomer on the surface of magnesium hydroxide in the presence of phosphoric acid. The melamine monomer was dissolved in hot water but recrystallized on the surface of magnesium hydroxide by quenching to room temperature in the presence of phosphoric acid. The core-shell particle was applied to low-density polyethylene/ ethylene vinyl acetate (LDPE/EVA) resin by melt-compounding at 180˚C as flame retardant. The effect of magnesium hydroxide and melamine content has been studied on the flame retardancy of the core-shell particles in LDPE/EVA resin according to the preparation process and purity of magnesium hydroxide. Magnesium hydroxide prepared with sodium hydroxide rather than with ammonia solution revealed higher flame retardancy in core-shell particles with LDPE/EVA resin. At 50 wt% loading of flame retardant, core-shell particles revealed higher flame retardancy compared to that of the exclusive magnesium hydroxide in LDPE/EVA composite, and it was possible to satisfy the V0 grade in the UL-94 vertical test. The synergistic flame retardant effect of magnesium hydroxide and melamine core-shell particles was explained as being due to the endothermic decomposition of magnesium hydroxide and melamine, which was followed by the evolution of water from the magnesium hydroxide and porous char formation due to reactive nitrogen compounds, and carbon dioxide generated from melamine.

Inorganic oxide colloids dispersed in alcohol were applied to a stainless steel substrate to produce oxide coatings for the purpose of minimizing emissive thermal transfer. The microstructure, roughness, infrared emissive energy, and surface heat loss of the coated substrate were observed with a variation of the nano oxide sol and coating method. It was found that the indium tin oxide, antimony tin oxide, magnesium oxide, silica, titania sol coatings may reduce surface heat loss of the stainless steel at 300˚C. It was possible to suppress thermal oxidation of the substrate with the oxide sol coatings during an accelerated thermal durability test at 600˚C. The silica sol coating was most effective to suppress thermal oxidation at 600˚C, so that it is useful to prevent the increase of radiative surface heat loss as a heating element. Therefore, the inorganic oxide sol coatings may be applied to improve energy efficiency of the substrate as the heating element.

To deterrnine the effects of insulin-like growth factor system in the aging process of the rat submandibular gland, expression pattems of 19f-1, 19f-2 and 19f-1 receptor were investigated by immunohistochem엽따. 1n addition, age-related changes of 19f-1 and 19f-2 concentrations in serum were deterrnined by radioimmunoassay 19f-1, 19f-2 and 19f-1 receptor were principally expressed 띠 the duct cells. 19f-1 receptors were strongly expre잃ed in 2-week-old group but were gradually decreased with advancing age. 19f-1 expressions were the strongest in the excretory and striated ducts of 7-month-old and 17-month-old groups. 19f-1 expressions, however, were weakiy expressed in the cells of granular convoluted tubules of 7-month잉ld ， 17-month-old and 27-month-old groups. 19f-2 expressions were found in some cells around duαs of 2-week-old group but were persisted relatively weak. The concentrations of 19f-1 and 1향2 in serum were the highest in 2-week-old group but were decreased and maintained at low level with advancing age. These results show that all components of 19f system were expressed in the rat submandibular giand in an age-related manner. Serum concentrations of all components of 19f system were not dosely related with the intra-밍and비ar expresslon patterns 까lerefore ， 1양 systerns may play important roles in the aging process of the rat submandibular gland in an autocrine/paracrine manner