• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1081-1089
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• 2005

In order to examine the application feasibility of Orimulsion fuel in a commercial boiler using heavy fuel oil, a numerical and experimental research efforts have been made especially to figure out the fundamental combustion characteristics of this fuel in a small-scale boiler. One of the notable combustion features of Orimulsion fuel is the delayed appearance of flame location with the flame shape of rather broad distribution, which is found experimentally and confirmed by numerical calculation. This kind of flame characteristics is considered due to the high moisture content included inherently in the process of Orimulsion manufacture together with micro-explosion by the existence of fine water droplets. In order to investigate the effect on the combustion characteristics of Orimulsion, a series of parametric investigation have been made in terms of important design and operational variables such as injected amount of fuel, types of atomization fluid, and phonemenological radiation model employed in the calculation, etc. The delayed feature of peak flame can be alleviated by the adjustment of the flow rate of injected fuel and the generating features of CO, $SO_2$ and NO gases are also evaluated in the boiler. When the steam injection as atomizing fluid is used, the combustion process is stabilized with the reduced region of high flame temperature. In general, the calculation results are physically acceptable and consistent but some refinements of phenomenological models are necessary for the better resolution of pollutant formation. From the results of this small-scale Orimulsion boiler, it is believed that a number of useful information are obtained with the working computer program for the near future application of Orimulsion fuel to a conventional boiler.

• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.2
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• pp.154-161
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• 2014

The purpose of this study is to evaluate the antioxidant activity and hair growth effects of a natural herbal ethanol extract, Samhwang-Sasimtang(SS). In case of antioxidant ability of SS, the content of phenolic compounds was 28.44mg/g. The extract showed strong electron donating ability and free radical scavenging activity in a concentration-dependent manner. SOD-like activity also rose through increasing the concentrations of SS. In order to estimate the hair growth effects, the extract was applied to the back of seven-week-old C57BL/6 male mice ($150{\mu}{\ell}$ a day, five days a week, for four weeks) in four groups (C, control, saline; PC, positive control, 3% minoxidil; E1, experimental 1, 1% SS; E2, experimental 2, 2% SS). Ten mice were assigned to each group and five mice in each group were sacrificed at weeks 2 and 4, respectively. There was no a significant difference in body weight change among experimental groups. In macroscopic observation of hair growth at week 4, the scores of hair growth on the backs of mice were 80, 60, 40 and 20% in the PC, E2, E1 and C groups. In terms of histological observation, the ratio and thickness of hair follicles, the enzyme activities of ALP and ${\gamma}$-GT, immunohistological examination of IGF-1 and VEGF which are the hair growth factors, in each group were significantly high in this order: PC, E2, E1 and C group, at week 4. Meanwhile, hair growth inhibition factors, TGF-${\beta}1$ and Caspase-3, were reduced in PC, E1 and E2 groups compared with C group. These results indicate that SS extract may be effective in promoting hair growth, and suggest that it can be used practically as a superior natural agent for hair growth promotion.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.11
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• pp.64-74
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• 1999

A new clock skew optimization for clock routing using link-edge insertion is proposed in this paper. It satisfies the given skew bound and prevent the total wire length from increasing. As the clock skew is the major constraint for high speed synchronous ICs, it must be minimized in order to obtain high performance. But clock skew minimization can increase total wire length, therefore clock routing is performed within the given skew bound which can not induce the malfunction. Clock routing under the specified skew bound can decrease total wire length Not only total wire length and delay time minimization algorithm using merging point relocation method but also clock skew reduction algorithm using link-edge insertion technique between two nodes whose delay difference is large is proposed. The proposed algorithm construct a new clock routing topology which is generalized graph model while previous methods uses only tree-structured routing topology. A new cost function is designed in order to select two nodes which constitute link-edge. Using this cost function, delay difference or clock skew is reduced by connecting two nodes whose delay difference is large and distance difference is short. Furthermore, routing topology construction and wire sizing algorithm is developed to reduce clock delay. The proposed algorithm is implemented in C programming language. From the experimental results, we can get the delay reduction under the given skew bound.

• Asian Journal for Public Opinion Research
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• v.5 no.3
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• pp.228-249
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• 2018

In 2015, the population of elderly people in Thailand was 16% of the total population and is predicted to be over 20% by 2021 and nearly 28% by 2031. The increase of the elderly population in Thailand has also increased the proportion of dependent elderly people, and caring for them poses many challenges for both families and the government. This descriptive method research aimed to survey the health status of dependent older people in the rural community of Lampang province in northern Thailand. The participants consisted of 62 older people and 62 primary family caregivers from Hong Ha Health Promoting Hospital, Lampang, Thailand (totaling 124 people). The researchers assessed the health status of older people and their activities of daily living (ADL). In addition, researchers assessed the health status and stress of caregivers. All the participants were interviewed about their experiences with caregiving. The results showed that most of the older respondents were female with an average age of 78.15 years. Based on the ADL assessment, 50 of the 62 older persons were homebound while the rest were bedridden. The majority of older people had chronic or long-term conditions that required hospitalization from time to time. Their frequent health problems included oral disorders such as tooth decay or caries/gum disease/no teeth, reduced sight, psychological disorders, knee pain and risk of falling, low BMI, risk of malnutrition, and urinary leakage and incontinence (58.06%, 66.13%, 62.90%, 70.97%, 38.71%, 66.13%, and 37.10%, respectively). Usual care provided by the family members included personal hygiene care, food preparation and feeding, medication management, housekeeping and organizing necessary equipment, supply of needed equipment, prevention of falls, helping with travel for medical checkups and treatment, and providing companionship. Families experienced shortages of medical supplies, daily use equipment, lack of employment, inadequate income, and difficulty accessing health care services due to lack of transportation. Some caregivers experienced caregiving stress related to a lack of social interactions as well as routine caregiving activities. Families need different types of support in order to promote the well-being of older people and caregivers. This highlights the need for a community participation model for the care of older people in order to reflect sustainable long-term outcomes.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1999.04a
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• pp.426-426
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• 1999

;There are many sources of uncertainty in a typical production and inventory system. There is uncertainty as to how many items customers will demand during the next day, week, month, or year. There is uncertainty about delivery times of the product. Uncertainty exacts a toll from management in a variety of ways. A spurt in a demand or a delay in production may lead to stockouts, with the potential for lost revenue and customer dissatisfaction. Firms typically hold inventory to provide protection against uncertainty. A cushion of inventory on hand allows management to face unexpected demands or delays in delivery with a reduced chance of incurring a stockout. The proposed strategies are used for the design of a probabilistic inventory system. In the traditional approach to the design of an inventory system, the goal is to find the best setting of various inventory control policy parameters such as the re-order level, review period, order quantity, etc. which would minimize the total inventory cost. The goals of the analysis need to be defined, so that robustness becomes an important design criterion. Moreover, one has to conceptualize and identify appropriate noise variables. There are two main goals for the inventory policy design. One is to minimize the average inventory cost and the stockouts. The other is to the variability for the average inventory cost and the stockouts The total average inventory cost is the sum of three components: the ordering cost, the holding cost, and the shortage costs. The shortage costs include the cost of the lost sales, cost of loss of goodwill, cost of customer dissatisfaction, etc. The noise factors for this design problem are identified to be: the mean demand rate and the mean lead time. Both the demand and the lead time are assumed to be normal random variables. Thus robustness for this inventory system is interpreted as insensitivity of the average inventory cost and the stockout to uncontrollable fluctuations in the mean demand rate and mean lead time. To make this inventory system for robustness, the concept of utility theory will be used. Utility theory is an analytical method for making a decision concerning an action to take, given a set of multiple criteria upon which the decision is to be based. Utility theory is appropriate for design having different scale such as demand rate and lead time since utility theory represents different scale across decision making attributes with zero to one ranks, higher preference modeled with a higher rank. Using utility theory, three design strategies, such as distance strategy, response strategy, and priority-based strategy. for the robust inventory system will be developed.loped.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.502-507
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• 2016

The transition from a carbon economy based on fossil fuels to a hydrogen economy is necessary to ensure energy security and to combat climate change. In order to pursue the transition to a hydrogen economy while achieving sustainable economic growth, a preliminary study into the establishment of the necessary infrastructure for the future hydrogen economy needs to be carried out. This study addresses the economic and environmental interactions in a dynamic computable general equilibrium (CGE) model focusing on the economic effects of the introduction of renewable energy into the Korean energy system. Firstly, the introduction of hydrogen results in an increase in the investment in hydrogen production and the reduction of the production cost, ultimately leading to GDP growth. Secondly, the mandatory introduction of renewable energy and associated government subsidies bring about a reduction in total demand. Additionally, the mandatory introduction of hydrogen energy into the power sector helps to reduce CO2 emissions through the transition from a carbon economy-based on fossil energy to a hydrogen economy. This means that hydrogen energy needs to come from non-fossil fuel sources in order for greenhouse gases to be effectively reduced. Therefore, it seems necessary for policy support to be strengthened substantially and for additional studies to be conducted into the production of hydrogen energy from renewable sources.

• Journal of Korea Water Resources Association
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• v.40 no.6 s.179
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• pp.485-494
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• 2007

This study was performed to evaluate the environmental qualities of the revetment construction methods and the river-facility materials using Life-Cycle-Assessment(LCA) for the nature-friendly design of close-to-nature river, The investigation results on the environmental qualities of energy and materials used to the close-to-nature river plan showed that the environmental impacts per unit weight increased in the order of gasoline > diesel > cement > wood. The environmental impacts per unit area of revetment construction method exhibited that the environmental loadings increased in the order of gabion > revetment > cribwork. In addition, it was observed that the environmental impact was reduced by improving the materials of zinc-galvanized wire. The model basin investigated in this study was the $0.3km^2$ area of river improvement works in Kyung stream, which is a tributary to the Seomjin river and the second regional stream. The research was conducted based on the 30years by life expectancy of artificial facilities. For the comparisons of revetment techniques with respect to the environmental qualities, the method resulted in the highest environmental loadings. The method using ready-mixed concrete ranked second in the environmental loadings of revetment techniques. The present results of this study are expected to play a beneficial role in the nature-friendly design of close-to-nature river by quantitatively identifying the environmental quality of total procedures (i.e., combination of techniques, selection of river-facility materials, maintenance of river-facility) applied to close-to-nature river plan.

• Journal of Korea Water Resources Association
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• v.52 no.8
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• pp.555-563
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• 2019

Reduced thickness of the water pipes due to corrosion makes it difficult to perform the original functions since corrosion in metallic water pipes can occur over time. In this study, reliability model that can estimate the probability of pipe breakage is developed regarding corrosion depth increment according to service year. Probability of pipe breakage was calculated by FORM(First Order Reliability Method) and unsteady analysis was performed to analyze the statistical properties of water pressure. And KCIP(Korea Cast Iron Pipe) equation was adopted for the reliability function. Furthermore, change of pipe thickness was estimated by Nahal and Khelif equation and Romanoff equation. Therefore, pipe thickness was calculated due to change of corrosion depth and probability of pipe breakage was calculated and compared with 10, 20, 30 service years. From the results, probability of pipe breakage for network A is gradually increased from 6.8% to 8.6% according to service year of 10, 20, 30 when Nahal and Khelif equation is applied. And probability of pipe breakage for network A is also gradually increased from 6.4% to 8.9% according to service year of 10, 20, 30 when Romanoff equation is applied.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.5
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• pp.1-14
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• 2021

Excessive development and urbanization have destroyed animal, plant, habitats and reduced biodiversity. In order to preserve species diversity, habitat prediction studies are have been conducted at home and overseas using various modeling techniques. This study was conducted to suggest optimal habitat modeling research by comparing HSI and MaxEnt, which are widely used among habitat modeling techniques. The study was targeted on the endangered species of Prionailurus bengalensis in nearby areas (5460.35km2) including Cheonan City, and the same data were used for analysis to compare those models. According to the HSI analysis, Prionailurus bengalensis's habitat probability was 74.65% for less than 0.5 and 25.34% for more than 0.5 and the top 30% were forest (99.07%). MaxEnt's analysis showed that 56.22% of those below 0.5 and 43.79% of those above 0.5 were found to have a high explanatory power of 78.3% of AUC. The Paired Wilcoxn test, which evaluated the significance of thoes models, confirmed that the mean difference between the two models was statistically significant (p<0.05). Analysis of the differences in the results of those models using the matrix table shows that score 24.43% HSI and MaxEnt was accordance,12.44% of the 0.0 to 0.2 section, 7.22% of the 0.2 to 0.4 section, 2.73% of the 0.4 to 0.6 section, 1.96% of the 0.6 to 0.8, and 0.08% of the 0.9 to 1.0. To verify where the score difference appears, the result values of those models were reset to values from 1 to 5 and overlaid. Overlapping analysis resulted in 30.26% of the Strongly agree values, 56.77% of the agree values, and 11.92% of the Disagree values. The places where the difference in scores occurs were analyzed in the order of forest (45.23%), agricultural land (34.57%), and urbanization area (7.65%). This confirmed that the analysis of the same target species within the same target site also has differences in forecasts depending on the modelling method. Therefore, a novel analysis method combining the advantages of each modeling in habitat prediction studies should be developed, and future study may be used to select Prionailurus bengalensis and species-protected areas and species protection areas in the future. Further research is judged to require higher accuracy studies through the use of various modeling techniques and on-site verification.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.3
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• pp.148-153
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• 2020

In order to obtain high accuracy with an convolutional neural network(CNN), it is necessary to set the optimal hyperparameters. However, the exact value of the hyperparameter that can make high performance is not known, and the optimal hyperparameter value is different based on the type of the dataset, therefore, it is necessary to find it through various experiments. In addition, since the range of hyperparameter values is wide and the number of combinations is large, it is necessary to find the optimal values of the hyperparameters after the experimental design in order to save time and computational costs. In this paper, we suggest an algorithm that use the design of experiments and grid search algorithm to determine the optimal hyperparameters for a classification problem. This algorithm determines the optima values of the hyperparameters that yields high performance using the factorial design of experiments. It is shown that the amount of computational time can be efficiently reduced and the accuracy can be improved by performing a grid search after reducing the search range of each hyperparameter through the experimental design. Moreover, Based on the experimental results, it was shown that the learning rate is the only hyperparameter that has the greatest effect on the performance of the model.