• Journal of the Korean Wood Science and Technology
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• 제38권4호
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• pp.298-305
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• 2010

본 연구에서는 목분 첨가된 폴리프로필렌 복합재의 수분흡수 특성에 목재수종, 화학조성분, 충진제 함량, 입자크기 및 상용화제의 첨가가 미치는 영향에 관해서 알아보았다. 500, 1,000, 1,500, 2,000, 2,500 및 3,000 시간 동안 물에 침지시킨 후, 상수리나무(Quercus accutisima Carr.)와 다릅나무(Maackia amuresis Rupr. et Maxim)는 낙엽송(Larix kaempferi Lamb.)에 비하여 훨씬 낮은 물흡수도를 보였다. 모든 수종에서 목분의 함량이 10 wt%로부터 50 wt%까지 증가할수록, 주어진 시간동안 물에 침지시켰을 때 복합재의 수분흡수율이 증가하 였다. 목분의 입자크기는 복합재의 수분흡수율에 큰 영향을 주는 것으로 나타났다. 상용화제의 첨가는 복합재의 수분흡수율을 낮추는데 아주 효과적이다. 가장 낮은 수분흡수율은 다릅나무 목분을 이용하고, 목분의 함량이 낮을수록, 목분의 입자크기가 작을수록, 그리고 상용화제를 첨가했을 때 얻을 수 있다. 복합재의 두께팽창은 수분흡수율과 아주 높은 상관관계를 가지고 있다.

• Journal of Pharmaceutical Investigation
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• 제35권1호
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• pp.33-38
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• 2005

Recently increasing attention has been focused on solid lipid nanoparticles (SLN) as a parenteral drug carrier due to its numerous advantages that can come from both polymeric particle and fat emulsions, together with the possibility of controlled release and increasing drug stability. Lipophilic drugs such as paclitaxel, cyclosporin A, and all-trans retinoic acid have been successfully entrapped in SLN but the incorporation of hydrophilic drugs in SLN is very limited because of their very low affinity to the lipid. Therefore, as a new approach to improve the loading of hydrophilic drugs, a w/o/w emulsion technique has been developed. The primary objective of the current study was to improve the loading efficiency of a model hydrophilic drug, glycine (Log P = -3.44) into SLN. The proposed preparation process is as follows: A heated aqueous phase consisting of 0.1 ml of glycine solution in water (100 mg/ml), and poloxamer 188 (5 mg) were then added to a molten oil phase containing precirol (100 mg) and lecithin (5 mg). This mixture was dispersed by sonicator, leading to a w/o emulsion. A double emulsion (w/o/w) was formed after the addition of 2% poloxamer solution to the above dispersed system. After cooling the double emulsion, solid lipid nanosuspensions were successfully formed. The lipid nanoparticles had the mean particle size of 441.25 nm, and the average zeta potential of -20.98 mV. The drug loading efficiency was measured to be 8.54% and the drug loading amount was measured to be 0.92%. The w/o/w emulsion method showed an increased loading efficiency compared to conventional o/w emulsion method.

• 산업기술연구
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• 제24권B호
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• pp.89-94
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• 2004

This Study is results of experimental works to investigate the characteristics of vibro-compaction of crushed stones having coarse grain sizes. For testing material, crushed stone, sieved within very narrow ranges of grain size distribution, was used. Cyclic loading apparatus was used to apply cyclic loading to the specimen prepared in the mold. Tests were performed by changing the ratio of the maximum to the minimum stress, frequency and the magnitude of the maximum and the minimum stresses. Settlement of specimen due to cyclic loading was measured to analyze the compaction efficiency and sieve analysis test after cyclic loading test was also carried out to find the crushing rate of the specimen. As results of cyclic loading test, normalized settlement in terms of specimen height tends to be converged around loading cycle number of 1500. The magnitude of normalized settlement is in the range of 3.11 ~ 8.57%. The crushing rate is in the range of 4.46 ~ 8.78%. Normalize settlement and the crushing rate tend to increase with decreasing the ratio of the maximum to the minimum stresses and they tend to increase with increasing the frequency and the magnitude of the maximum and the minimum stresses for the given ratio. In conclusions, compaction rate of crushed stone is controlled by the dynamic stress (difference between the maximum and the minimum stresses) and the crushing rate is dominated by applied energy to the specimen.

• 한국초전도ㆍ저온공학회논문지
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• 제17권3호
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• pp.13-17
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• 2015

In superconducting coil applications particularly in wet wound coils, coated conductor (CC) tapes are subjected to different type of stresses. These include hoop stress acting along the length of the CC tape and the Lorentz force acting perpendicular to the CC tape's surface. Since the latter is commonly associated with delamination problem of multi-layered CC tapes, more understanding and attention on the delamination phenomena induced in the case of coil applications are needed. Difference on the coefficient of thermal expansion (CTE) of each constituent layer of the CC tape, the bobbin, and the impregnating materials is the main causes of delamination in CC tapes when subjected to thermal cycling. The CC tape might also experience cyclic loading due to the energizing scheme (on - off) during operation. In the design of degradation-free superconducting coils, therefore, characterization of the delamination behaviors including mechanism and strength in REBCO CC tapes becomes critical. In this study, transverse tensile tests were conducted under different loading conditions using different size of upper anvils on the GdBCO CC tapes. The mechanical and electromechanical delamination strength behaviors of the CC tapes under transverse tensile loading were examined and a two-parameter Weibull distribution analysis was conducted in statistical aspects. As a result, the CC tape showed similar range of mechanical delamination strength regardless of cross-head speed adopted. On the other hand, cyclic loading might have affected the CC tape in both upper anvil sizes adopted.

• 유통과학연구
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• 제12권8호
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• pp.55-69
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• 2014

Purpose - Despite the importance of price, many companies do not implement pricing policies smoothly, because typical price management strategies insufficiently consider logistics efficiency and an increase in logistics costs due to logistics waste. This study attempts to examine the effect of product line pricing, which corresponds to product mix pricing, on logistics efficiency in the case of manufacturer A, and analyzes how logistics performance changes in response to these variables. Research design, data, and methodology - This study, based on the case of manufacturer A, involved research through understanding the current status, analyses, and then proposing improvement measures. Among all the products of manufacturer A, product group B was selected as the research object, and its distribution channel and line pricing were examined. As a result of simulation, for products with low loading efficiency, improvement measures such as changing the number of bags in the box were suggested, and a quantitative analysis was conducted on how these measures influence logistics costs. The TOPS program was used for the Pallet loading efficiency simulation tool in this study. To prevent products from protruding out of the pallet, the maximum measurement was set as 0.0mm, and loading efficiency was based on the pallet area, and not volume. In other words, its size (length x width) was focused upon, following the purpose of this study and, then, the results were obtained. Results - As a result of the loading efficiency simulation, when the number of bags in the box was changed for 36 products with low average loading efficiency of 73.7%, as shown in