• Computers and Concrete
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• v.20 no.6
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• pp.655-661
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• 2017

Fiber reinforced concretes exhibit higher tensile strength depending on the percent and type of the fiber used. These concretes are used to reduce cracks and improve concrete behavior. The use of these fibers increases the production costs and reduces the compressive strength to a certain extent. Therefore, the use of fiber reinforced concrete in regions where higher tensile strength is required can cut costs and improve the overall structural strength. The behavior of fiber reinforced concrete and normal concrete adjacent to each other was investigated in the present study. The concrete used was self-compacting and did not require vibration. The samples had 0, 1, 2 and 4 wt% polypropylene fibers. 15 cm sample cubes were subjected to uniaxial loads to investigate their compressive strength. Fiber Self-Compacting Concrete was poured in the mold up to 0, 30, 50, 70 and 100 percent of the mold height, and then Self-Compacting Concrete without fiber was added to the empty section of that mold. In order to investigate concrete behavior under bending moment, concrete beam samples with similar conditions were prepared and subjected to the three-point bending flexural test. The results revealed that normal Self-Compacting Concrete and Fiber Self-Compacting Concrete may be used in adjacent to each other in structures and structural members. Moreover, no separation was observed at the interface of Fiber Self-Compacting Concrete and Self-Compacting Concrete, either in the cubic samples under compression or in the concrete beams under bending moment.

• Asia-Pacific Journal of Business
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• v.10 no.4
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• pp.137-151
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• 2019

Using Korean Labor and Income Panel Study data, this paper estimates nominal wage rigidity in Korea by industry from 2005 to 2017 and evaluates the level of inefficiency of Korean labor market. And, after estimating employment volatility by industry using the Labor Force Survey at Establishments data for Korea, we combine the nominal wage rigidity and the employment volatility estimates and analyze the effect of nominal wage rigidity on employment volatility in Korea from 2011 to 2017. If the level of wage rigidity is high, it may be hard for the labor market to be in the equilibrium, and therefore, the market may have inefficiency. We find that the inefficiency of the labor market in Korea have increased from 2005 to 2017 and the industry of accommodation and food service activities has the highest level of inefficiency over the period. We also find that one-percent-point increase in wage rigidity increases employment volatility by 2.3-2.9 percent and the positive effect is bigger for workers with part-time and temporary jobs. The result implies that firms may adjust their labor costs by changing the number of casual workers, rather than permanent workers, when the labor market suffers from a high level of wage rigidity.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.3
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• pp.467-476
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• 2022

The Bank of Korea raised the benchmark interest rate by a quarter percentage point to 1.75 percent per year, and analysts predict that South Korea's policy rate will reach 2.00 percent by the end of calendar year 2022. Furthermore, because market volatility has been significantly increased by a variety of factors, including rising rates, inflation, and market volatility, many investors have struggled to meet their financial objectives or deliver returns. Banks and financial institutions are attempting to provide Robo-Advisors to manage client portfolios without human intervention in this situation. In this regard, determining the best hyper-parameter combination is becoming increasingly important. This study compares some activation functions of the Deep Deterministic Policy Gradient(DDPG) and Twin-delayed Deep Deterministic Policy Gradient (TD3) Algorithms to choose a sequence of actions that maximizes long-term reward. The DDPG and TD3 outperformed its benchmark index, according to the results. One reason for this is that we need to understand the action probabilities in order to choose an action and receive a reward, which we then compare to the state value to determine an advantage. As interest in machine learning has grown and research into deep reinforcement learning has become more active, finding an optimal hyper-parameter combination for DDPG and TD3 has become increasingly important.

• Journal of The Korean Association For Science Education
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• v.22 no.1
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• pp.204-213
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• 2002

In this study, the students' responses on the items of chemistry II in the College Scholastics Ability Test (CSAT) implemented for the past 3 years since 1999 was investigated. The number of applicants and mean score of chemistry II, average percent correct by contents and inquiry process, and the items with high and/or low percent correct are analysed and discussed. The percentage of applicants for natural science track is reduced each year. However, more than 25% of natural science track applied to chemistry II, which ranked second to biology II. The mean score of chemistry II was increased in 2001 along with those of other subjects. There is no difference in average percent correct either by contents or inquiry process. Students performed generally poor at solving test items relating to 'colligative properties of solution' such as 'boiling point elevation' or 'osmotic pressure', and very well at solving test items relating to 'reaction rates'. Educational implications are discussed.

• Korean Journal of Community Nutrition
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• v.3 no.2
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• pp.292-307
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• 1998

This study was conducted to evaluate the eating behavior and to analyze the various factors affecting eating behavior among middle school students. The subjents consisted of 212 middle school students(106 boys and 106 girls between 13-14 years) residing in Seoul. A questionnaire was used as the questionnaire consisted of four parts : the socio-demographic characteristics of the subjects, value toward food and nutrition, diet diversity(the number of food items) and eating behavior. Results showed that fifty three point five percent of males and fifty seven percent of females skipped breakfast. The main reason for skipping breakfast was shortage of time. Fifty five percent of the total number of subjects stated that they had more than two plasant meals a day. The number of food items eaten was significantly higher in males than in females. In only 16.4% of total subjects(18.5% of male and 14.2% of female), the primary pursuit in having meals was not to satisfy hunger but to consider nutrition and health. The eating behavior of the adolescents showed that 65% of the subjects had a 'good' eating behavior score and 17.4% had scores of 'excellent' and 'poor' respectively. The existence of parents, the economic level of the family, and concern of health and nutrition affected the eating behavior score. The less the subject skipped breakfast, the greater they placed a value toward food and nutrition. Value toward food and nutrition had a significant influence on their eating behavior. Those who placed a value toward food and nutrition had a higher eating behavior. Those who placed a value toward food and nutrition had a higher eating eating behavior. As a result of the multiple regression analysis, factors affecting eating behavior were 'pleasant meal' , 'the value toward food and nutrition' and 'the numbers of food items' in order(R2=0.2984).

• Food Science and Preservation
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• v.5 no.3
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• pp.275-280
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• 1998

The effects of Poria cores powder addition on bread making were investigated by evaluation of dough rasing power, rheological properties of dough by farinograph and extensograph color and sensory quality. As increment of Poria cocos powder, dough rasing power and extensibility were decreased but water absorption rate and resistance were increased. Time for dough formation, stability and v/v point of dough were increased when 5 and 10 percent of Poria cocos powder were added. Color of bread wasn't significantly different when Poria cocos powder was added up to 10 percent. Overall acceptance by sensory evaluation was the best when 5 percent of Poria cocos powder was added, tut there are no significant difference among breads which were made with various mixing rates of Poria cocos powder.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.269-272
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• 2008

This paper reports on the cracking mitigation and flexural behavior experimentally observed in concrete prisms layered with strain-hardening cement composites (SHCCs) which is micro-mechanically designed cement composite and exhibits pseudo tensile strain-hardening behavior accompanied by multiple cracking while using a moderate amount of fiber, typically less than 2 percent in term of fiber volume fraction. In this study, SHCC is reinforced with 1.3 percent polyvinyl alcohol (PVA) and 0.20 percent polyethylene (PE) in volume fraction. Tests were conducted using $100{\times}100{\times}400mm$ long prisms supported over a simply supported span of 350mm. The four point load was applied using MTS servo control machine. The thickness patched with SHCC is the main variable for this study. Experimental study shows that when subject to monotonic flexural loading, the SHCC layered repair system showed 2.7 - 4.2 times increased load carrying capacity, and mitigated cracking damage of concrete beams layered with SHCC compared with plain concrete beams.

• Korean Journal of Community Nutrition
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• v.5 no.4
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• pp.624-632
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• 2000

Nutrition related factors were investigated in one hundred and two hypertensive patients(Male : 44, female : 58) before they started drug treatment or diet therapy. The mean age of men and women were 49.9 and 53.5, respectively. Among the men, their mean SBP and DBP were 165.8 mmHg/108.4 mmHg. Fifty six point eight percent of men was classified as having in stage 3 hypertension(SBP $\geq$ 180 mmHg, or DBP $\geq$ 110 mmHg) and 45.5% was classified as having low renin hypertension (serum renin < 2.5 ng/ml/h). The proportion of overweight or obesity assessed by BMI($\geq$ 25) or body fat percent( $\geq$ 21%) was 47.7% or 80.9%, respectively. Men showed 19.1% of hypertriglyceridemia(serum TG $\geq$ 200 mg/dl), 42.6% of hypercholesterolemia(serum cholesterol $\geq$ 220 mg/dl), and 17.0% was observed as having serum cholesterol higher than 240 mg/dl. The proportion of men with high risk of cardiovascular disease was 72.3% assessed by atherogenic index( $\geq$3.4). The prevalence of drinking was 86.4% including a daily drinking proportion of 15.8%. Among women, their mean SBP and DBP were 162.6 mmHg/104.3 mmHg. Less women(43.1%) were classified as having stage 3 hypertension and more women were observed in low renin hypertension(55.1%). The prevalence of obesity or overweight assessed by BMI( $\geq$ 25) was 31.0% and 76.3% with body At percent($\geq$28%). Women revealed 24.1% of hypertriglyceridemia and 36.2% of hypercholesterolemia. The proportion of women who showed high risk of cardiovascular disease(atherogenic index $\geq$ 3.4) was 63.8%. The smoking rate was 8.6% and drinking rate was 43.1%.

• Health Policy and Management
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• v.22 no.4
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• pp.538-560
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• 2012

This study tried to find out the level of national health expenditure and associated factors in the OECD countries and then to derive lessons for Korea's health financing based on the cross-national comparison. As a result, Korea's health expenditure in 2010(7.1% of GDP) accounted for 74.7 percent of the OECD average and ranked as countries to spend less on health. At the same time, the socio-economic indicators such as GDP per capita, elderly population ratio and the total tax revenue to GDP also remained between 72 ~ 82 percent of the OECD average. The public share of health financing(58.2%) was relatively lower than those of other countries. However the health expenditure and the public share have grown 1.9 ~ 2.4 times higher than the OECD average over the past decade. According to the quantitative analysis, countries with relatively high income and elderly population turned out to have high health expenditure. Whereas, an inverse relationship was found between the total health expenditure and the public funding. It was estimated that the value of national health expenditure to GDP decreases 0.083 when the rate of public funding increases 1 percent point. Further, the share of public funding was affected positively by the total tax burden. Based on these findings, this study suggests that the sustainable spending on health and alleviating households' direct burden could be ensured by enhancing the share of public funding along with adjusting the tax burden of the people.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.1-9
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• 2019

This study was carried out to compare stand structure and dynamics in Abies koreana forest in Yeongsil area of Mt. Hallasan between 2011 and 2017 by analysing DBH distribution, tree vitality, importance value (IV) and species diversity through the national long-term ecological research project conducted by National Institute of Environmental Research. As a result of DBH distribution, A. koreana decreased in all DBH class except 20-25 cm and the number of individual decreased by 16.3 percent from 780 to 655. As a result of tree vitality of A. koreana, the number of standing alive (AS) decreased by 16.2 percent from 652 to 546, while that of standing dead (DS) increased by 15.8 percent from 106 to 126 and that of fallen dead (DF) increased by 193.7 percent from 16 to 47, respectively. Importance value of A. koreana decreased by 2.4 percent point from 45.9 % to 43.5 %. Species diversity increased by 0.006 from 0.513 to 0.519. The weakening of the A. koreana in the Yeongsil area of Mt. Hallasan could be considerably supported by many aspects such as DBH distribution, tree vitality and importance value. Therefore, Long-term ecological monitoring and continuously research in that area should be conducted to clarify the effects of ecosystem changes.