• Food Science and Preservation
• /
• v.17 no.6
• /
• pp.835-846
• /
• 2010

The manufacture of beverages prepared using hot-water extracts of Polygonatum odoratum var. pluriflorum, Houttuynia cordata, and Lycium chinensis was statistically optimized using response surface methodology. The total polyphenol content, electron donation activity, and reducing power of optimized beverages were measured to evaluate antioxidant properties. The coefficients of determination, the $R_2$ values, were 0.9887~0.9957 for color, taste and overall acceptability. Analysis of variance showed that the model fit was a statistically significant (p<0.05). The optimized compositions of processed beverages were: Polygonatum odoratum var. pluriflorum extract, 2.15%; Houttuynia cordata extract, 1.74%; and Lycium chinensis extract, 0.19% (all w/w). Total polyphenol content, electron donation activity, and reducing power of beverages of optimized composition were 3.61 mg/L, 23.78%, and 0.26, respectively.

• Land and Housing Review
• /
• v.12 no.4
• /
• pp.127-137
• /
• 2021

Grouting has been widely used to enhance the strength of the ground and prevent waterflow into the underground space in the geotechnical engineering field. Cement with bentonite can be considered a helpful grouting material because the bentonite has a swelling ability with water. Therefore, it is essential to evaluate the characteristics of grouting materials according to the mixing ratio for a successful grouting process. In this regard, the study investigated the viscosity and bleeding characteristics of grouting materials according to the mixing ratio (i.e., water/cement ratio and bentonite/cement ratio). In the experimental result, the viscosity increases with decreasing water/cement ratio and rising proportion of bentonite by weight of cement. However, the results of the bleeding ratio show the tendency is inversely proportional to the viscosity results. Bentonite was explored in terms of the viscosity and bleeding criterion. This result is expected to be meaningful to determine the optimized mixing ratio of bentonite-cement in the grouting field.

• Journal of Korean Society of Forest Science
• /
• v.81 no.2
• /
• pp.139-145
• /
• 1992

A planning method of optimum forest road was tested in the compartment II of Kangweon National University Forests by using a digital terrain model under four evaluation factors, i. e., minimum road length, average skidding distance, exploitative index, and ratio of inaccessible points. The results of the study were as follows : 1. Optimum forest road design based on the minimum road length was shown as 6035.6m, 12.73m/ha, 279.9m, 1.43, and 15.7% for total road length, forest road density, average skidding distance, exploitative index, and ratio of inaccessible points, respectively. 2. Optimum forest road design based on the average skidding distance was shown as 7828.5m, 16.52m/ha, 198.4m, 1.31, and 4.0% for total road length, forest road density, average skidding distance, exploitative index, and ratio of inaccessible points, respectively. 3. Optimum forest road design based on the exploitative index was shown as 7410.6m, 15.64m/ha, 210.9m, 1.26, and 5.0% for total road length, forest road density, average skidding distance, exploitative index, and ratio of inaccessible points, respectively. 4. Optimum forest road design based on the ratio of inaccessible points was shown as 8307.1m, 17.53 m/ha, 184.9m, 1.29, and 2.5% for total road length, forest road density, average skidding distance, exploitative index, and ratio of inaccessible points, respectively.

• Journal of the Korean Institute of Gas
• /
• v.21 no.2
• /
• pp.1-9
• /
• 2017

Enhanced coalbed methane recovery (ECBM), as injecting $CO_2$ or $N_2$ into the coalbed methane (CBM) reservoir for increasing methane recovery, takes center stage in these days. ECBM makes a better recovery than the conventional production method, it called dewatering process. However the characteristics of injection gas affect to methane recovery, thus analysis on the mixed ratio of injection gas should be required. In this study, CBM reservoir model was built to estimate the methane recovery of ECBM method by different mixed ratio of injection gas. Additionally, to consider the characteristics of injection gas such as carbon captured storage, nitrogen re-injection, etc. economic analysis was performed. The results showed that ECBM cases produced methane almost twice as much as dewatering case and $CO_2$ 10% and $N_2$ 90% case resulted in the highest methane recovery among the mixed gas cases. On the other hand, the results of economic analysis showed that $CO_2$ 20% and $N_2$ 80% case made the highest total production profit. Therefore, both the recovery of methane and economical efficiency should be considered to apply ECBM process.

• Knowledge Management Research
• /
• v.22 no.2
• /
• pp.247-268
• /
• 2021

Investors mainly use PER and PBR among financial ratios for valuation and investment decision-making. I conduct an analysis of two basic financial ratios from a statistical perspective. Financial ratios contain key accounting numbers which reflect firm fundamentals and are useful for valuation or risk analysis such as enterprise credit evaluation and default prediction. The distribution of financial data tends to be extremely heavy-tailed, and PER and PBR show exceedingly high level of kurtosis and their extreme cases often contain significant information on financial risk. In this respect, Extreme Value Theory is required to fit its right tail more precisely. I introduce not only GPD but exGPD. GPD is conventionally preferred model in Extreme Value Theory and exGPD is log-transformed distribution of GPD. exGPD has recently proposed as an alternative of GPD(Lee and Kim, 2019). First, I conduct a simulation for comparing performances of the two distributions using the goodness of fit measures and the estimation of 90-99% percentiles. I also conduct an empirical analysis of Information Technology firms in Korea. Finally, exGPD shows better performance especially for PBR, suggesting that exGPD could be an alternative for GPD for the analysis of financial ratios.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.3-4
• /
• 2006

본 논문에서는 계통의 불확실성을 고려한 확률론적인 방법으로 전력계통의 신뢰도를 평가한다. 발전기 3 state modeling 및 부하의 정규분포 곡선으로 확률론 신뢰도 평가 모델을 가정하였다. 그리하여 Adequacy 및 계통의 전압 및 송전선제약 조건 외에도, 소신호 안정도 항목을 추가하여 보다 동적인 측면에서의 신뢰도 평가가 이루어지도록 하였다. 이러한 평가 방법의 결과에 의하여 각 평가 항목간의 비율을 비교하였으며, 이를 통한 PSS의 설치 위치 선정의 근거를 마련하였다. 모의 방법은 Monte Carlo Simulation방법을 사용하였으며, WSCC 3기 9모선과 New England 10기 39모선을 모의계통으로 하였다.

• Communications of Mathematical Education
• /
• v.23 no.3
• /
• pp.923-951
• /
• 2009

In this paper, we have analyzed the term examinations on quadratic equations and functions in middle schools based on the object of evaluations given by the ministry of education, science and technology of Korea.

• Journal of the Korea Institute of Building Construction
• /
• v.21 no.1
• /
• pp.11-19
• /
• 2021

The aim of the research is providing a fundamental data on quality and constructability of direct tile setting method depending on various cement to sand ratio for tiling dry cement mortar. A large number of tile setting failures reported is related with the cement mortar and its construction for tiling. Because of different materials of tiles, the properties of tiling dry cement mortar, an adhesive for tiling, can influence on quality and constructability of tiling differently. Practically, the easiest way of controlling the properties of the tiling dry cement mortar is to control the proportion of cement and sand. Hence, in this research, sand to cement ratio (S/C) was controlled. Since there is no standarized method on evaluating performance of dry cement mortar for tiling, a several sensory evaluation methods were suggested and executed. According to the experiments conducted in this research, the adhesive performance of cement mortar for tiles can be different depending on the sides such as tile and substrate. Additionally, depending on S/C, finishability, initial adhesive performance, and tile shifting resistance can be changed for ceramic tile. Therefore, under the conditions of this research, about 5 of S/C can be recommended for appropriate performace of tiling dry cement mortar.

• Journal of the Korean Society of Food Culture
• /
• v.22 no.4
• /
• pp.468-474
• /
• 2007

Physicochemical and sensory characteristics of cookies with various levels of resistant starch were investigated in this study. Dough pH of 30% substituted sample group had significantly the highest value than that of all(p<0.05). Water contents of Dough were decreased with increased levels of the resistant starch in cookie preparation. The spreadability was increased as the addition levels of the resistant starch were increased. The Hunter L and a values of 30% substituted sample group had the highest values of all(p<0.05). Results of sensory characteristics of 30% substituted sample group showed significantly the lower values in hardness and crack than those in the other groups at p<0.05. Acceptance tests of cookies with 10 and 20% substituted sample groups showed higher values in savory flavor and overall acceptability than those of others.

• Journal of The Korean Association For Science Education
• /
• v.28 no.5
• /
• pp.438-452
• /
• 2008

The purposes of National Assessment of Educational Achievement(NAEA) are to assess Korean students' achievement of the educational goals as well as to diagnose the trends of educational achievement in order to monitor the quality of education at the national level. We analysed average scores in science achievement and trend of achievement level at the National Assessment of Educational Achievement(NAEA) from the year 2003 to 2006 for 6th, 9th and 10th graders. The results are as follows: For grades 6, 9, and 10, the average scores of NAEA did not tend to increase or decrease. About the trend analysis of gender, females outperformed males for grade 6, but males outperformed females for grade 10. For grade 6, the ratio of females in Advanced level was more than that of the males in the same level. For grades 9 and 10, the ratio of male was higher than the females. For grades 6, 9 and 10, the ratio of males in Below-Basic level was more than that of females in the same level. The results of the educational achievement of urbanization shows that students in rural area scored the lowest. And the ratio of Below-basic level students was highest in rural area. It is needed that educational surroundings be improved to lessen the score difference both between genders and regions. An additional study is needed to used the results of NAEA for the improvement of curriculum and educational policy.