The purpose of this study is to optimize the extraction conditions (time, pH, and temperature) for water-soluble dietary fiber (SDF) and solids from Opuntia ficus-indica (OFI) stems and to evaluate the functionality of the optimized extract. The maximum extraction yield was obtained when 100% distilled water was used, indicating that ethanol hampered the extraction. The extraction yields were lower at higher temperatures and lower pHs. The maximum extraction of SDF (27.92%) and solids (5.6 g) was achieved with a 7-h extraction at 50oC and pH 7.0, with desirability being 0.958. The stem extract obtained under the optimum extraction conditions had an antioxidant capacity of 118.10 mg vitamin C equivalents (VCE) using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. In a medium containing 30% extract, the growth of E. coli was reduced by 34%, while that of B. cereus was reduced by 23%. These results suggest that OFI stems can be used as a functional resource.

The goal of this study was to identify how well learners express themselves when an online conversation environment is provided in a SW education curriculum. In order to achieve this goal, this study took place during the first semester of 2018, with the subjects being 115 students belonging to two classes from 5th grade and two from the 2nd year of middle school in schools that were conducting the SW leadership school project. The results of creating an online conversation environment and collecting the students’ opinions about it showed that the higher the age of the students, the better they adapted to the online environment and, furthermore, female students especially proved to be more active at online expressions compared to male students.

본 연구는 중국 상장기업을 표본으로 기업의 소유 및 지배구조가 기업의 현금보유에 미치는 영향을 실증적으로 분석하고 또한 소유 및 지배구조에 따라 현금자산이 어떻게 다르게 사용되는지를 분석한다. 더 나아가 기업의 경영성과에 어떤 영향을 미치는지를 실증적으로 분석한다. 주요 분석 결과는 다음과 같다. 먼저 중국기업의 소유 및 지배구조는 기업의 현금보유 경향에 영향을 미치는 것으로 나타났다. 대주주 지분율이 높고 이사회규모가 작은 기업의 현금보유가 많은 것으로 나타난 반면, 소유권이 분산되어 효과적인 감시주체가 적고 이사회 규모가 커서의사결정의 효율성이 떨어지는 기업은 현금자산이 적었다. 이는 이들 기업은 현금자산을 주로 비합리적인 자본 지출이나 연구개발에 빨리 소진하였기 때문인 것으로 볼 수 있다. 이러한 현금사용 방식의 차이는 기업성과에도 영향을 미쳐 대주주 지분율이 낮고 이사회 규모가 큰 기업에서 현금을 많이 보유할 때 영업이익률이 낮은 것으로 나타난 반면, 대주주 지분율이 높고 이사회 규모가 작은 기업의 경영성과는 더 좋은 것으로 나타났다. 중국기업의 소유 및 지배구조는 배당정책에도 영향을 미쳤는데 대주주 지분율이 높은 기업에서는 기업내부의 현금이 증가함에 따라 배당을 많이 하는 반면에, 대주주 지분율이 낮은 기업에서는 배당이 감소하여 기업내부의 현금 을 주주에게로 이전하지 않는 것으로 나타났다. 이러한 결과는 중국기업의 소유구조상 대주주 지분율이 낮고 소유권이 분산된 기업에서는, 지배 주주가 존재하고 소유권이 집중된 기업보다 주주와 경영자 사이의 대리인 문제가 더 심각함을 보여 준다. 이에 따라 소유권이 분산된 중국기업에서 향후 주주의 권한 강화와 함께 경영진에 대한 감독이 강화될 필요가 있음을 시사한다. 또한 이사회 규모와 관련해서 이사회 규모가 작은 기업의 이사회가 더 효율적이며, 사외이사는 기업의 현금보유 경향에 영향을 미치지 않고 그 역할을 제대로 수 행하지 못하며 사외이사의 독립성이 떨어짐을 의미한다. 따라서 향후 중국기업에서 이사회 효율성을 강화하고 사외이사 제도를 적극 보완하는 등 이사회 기능을 개선해야 함을 시사한다.

대형 유조선에서 유류의 선적이나 하역에 사용되는 장치인 COPT (Cargo Oil Pump Turbine) 가 매우 큰 형태이므로 이 터빈을 회전시키는 장치가 Rotor disc로서, 내부에 stator ring이 장착되어 있고 이 ring에는 많은 turbine blade가 riveting 방법에 의해 체결되어 있다. riveting 은 재래식 가공 방법으로서 정밀도와 작업자의 근 골격계 직업병 등 많은 문제점을 포함하고 있다. 이러한 문제를 해결하기 위해 riveting 체결방법을 조립방법으로 전환하여 링의 조립정밀 도를 향상하고 stator의 수명을 연장시킬 수 있다. 많은 turbine blade가 링의 중심점을 기준으로 원주상에 배열되어 있는 형태로서 조립을 위한 구조개선을 필요로 한다. 이런 목적을 달성 하기 위해서는 ring 구조를 결구 방식으로 변경하고 조립 후 COPT에 적용하였을 때 안전성이 보장되어야 한다. Stator 링의 모델링과 구조안전성에 대한 검증은 상용 software를 이용하여 결과를 도출한다.

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.

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.

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.

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.

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.

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.

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.