• Geomechanics and Engineering
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• 제34권4호
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• pp.381-396
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• 2023

The present paper evaluates seismic bearing capacity of rock masses subjected to loads of strip footings using the upper bound method. A general formula was proposed to evaluate the seismic bearing capacity considering both the horizontal and vertical accelerations of the earthquake and the effects of footing embedment depth simultaneously. Modified Hoek-Brown failure criterion was employed for the rock mass. Some comparisons were made with the available solutions and the finite element numerical models to show the accuracy of the developed upper bound formulations. The obtained results show significant improvement compared to the other available solutions. By increasing the horizontal earthquake acceleration from 0.1 to 0.3, the bearing capacity was reduced by up to 39%, while the effect of the vertical earthquake acceleration depends on its direction. An upward acceleration in the range of zero to 0.2 results in an increase in the bearing capacity by up to 24%, while the downward earthquake acceleration has an adverse effect. Also, by increasing the embedment depth of the footing from zero to 5 times the footing width, the value of seismic bearing capacity was raised about 86%. The obtained results were presented as design tables for use in practical applications.

• Journal of Communications and Networks
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• 제8권1호
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• pp.13-20
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• 2006

In cellular mobile communications, how to achieve optimum system capacity with limited frequency spectrum is one of the main research issues. Many dynamic channel assignment (DCA) schemes have been proposed and studied to allocate the channels more efficiently, thus, the capacity of cellular systems is improved. Reuse partitioning (RP) is another technique to achieve higher capacity by reducing the overall reuse distance. In this paper, we present a network-based DCA scheme with the implementation of RP technique, namely dynamic reuse partitioning with interference information (DRP-WI). The scheme aims to minimize the effect of assigned channels on the availability of channels for use in the interfering cells and to reduce their overall reuse distances. The performance of DRP-WI is measured in terms of blocking probability and system capacity. Simulation results have confirmed the effectiveness of DRP-WI scheme. Under both uniform and non-uniform traffic distributions, DRP-WI exhibits outstanding performance in improving the system capacity. It can provide about 100% capacity improvement as compared to conventional fixed channel assignment scheme with 70 system channels.

• 산업공학
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• 제16권spc호
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• pp.111-115
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• 2003

Railroad system is consisted of resources of rail track, signal system, and vehicles. Railway operation must use these limited resources and maximize resource utilization. Line capacity(number of trains throughput/day) is determined by such as parameters, line utilization rate($\alpha$), dummy rate for the break-through hour($\beta$), and dummy rate for the number of rail track intervals($\delta$). Line capacity simulation(LCS) determined the line capacity through simulation given $\alpha$, $\beta$, and $\delta$. This paper deals with the development of parameter evaluation simulation(PES). PES presents the decision maker with the relationship of line capacity and measurement of robustness for various scenarios in different parameters and then the decision maker can determine the appropriate parameters.

• 한국지열·수열에너지학회논문집
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• 제10권3호
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• pp.17-23
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• 2014

One major breakthrough in the field of heating, ventilation and air conditioning has been the development of heat pumps. Heat pump systems offer economic alternatives for recovering heat from different sources for use in various industrial, commercial and residential applications. In recent years, the heat pump has been tipped to have a very good potential for hot water production. This paper investigated the performance of a vapor injection heat pump with the variation of sub-cooler capacity at heating mode. The heating capacity of the vapor injection heat pump slightly increased with an increment of sub-cooler capacity, while COP didn't increase continuously. The 20% capacity of sub-cooler comparing with system capacity could be used as a standard to select sub-cooler capacity.

• The Journal of Korean Physical Therapy
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• 제31권4호
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• pp.248-253
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• 2019

Purpose: To improve pulmonary function and decrease in balance ability with increasing forward head position and vertebral curvature, we applied Figure-8 brace to confirm the immediate effect on vital capacity and balance and to see if it is applicable. Methods: A total of 34 elderly women aged 65 or older and young women in their 20s with FHP were screened to measure vital capacity, measuring the forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC), and measuring the foot pressure to see the change in balance. For statistical analysis, the difference between pre and post values was compared using pared t-test. Results: As a result of vital capacity measurements, there was no significant difference between FEV1 and FVC for women over 65 years old (p>0.05). Young women in their 20s had no significant difference in FEV1 (p>0.05), and FVC had significant differences (p<0.05). In measuring foot pressure to measure balance, both women aged 65 and above and young women in their 20s had a significant decrease in anterior foot pressure, and a significant increase in posterior foot pressure (p<0.05). Conclusion: The results of this study did not positively affect the vital capacity of elderly women with FHP. However, the significant increase in vital capacity of young women in their 20s suggests that contraction of the abdominal muscle is necessary during forced expiration. Therefore, it is believed that proper application and therapeutic interventions should be combined when applying Figure-8 brace.

• 해양환경안전학회지
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• 제16권1호
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• pp.21-29
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• 2010

지금까지 연안 양식장의 지속적인 생산 및 체계적인 관리를 위해 어장환경용량 산정 및 활용에 관하여 많은 연구가 선행되어 왔다. 그러나, 생태학적 부하를 고려한 지속적 적정 생산을 위해서는 4가지 계층구조(물리적 수용능력, 생산 수용능력, 생태학적 수용능력 및 사회적 수용능력)에 의한 어장환경용량 산정 개념을 활용할 수 있다. 생태학적 수용 능력 산정의 경우, 환경과 패류 양식의 상호작용에 관한 좀 더 전체적인 접근이 필요하여 아직까지 모델 개발은 초기 단계에 있으므로, 이에 대한 대안접근으로 패류양식장이 해양생태계의 가능을 어떻게 변화시킬 수 있는지 패류양식장의 생태적 효율을 평가할 수 있는 생태지표의 필요성이 대두되었다. 현재 거제한산만 굴양식장의 정화율 생태지표는 0.331, 여과압 생태지표는 0.203으로 계산되었으며, 이는 연안 생태계에 부하를 주지 않는 생태학적 수용 능력인 0.05를 초과하고 있음을 나타내었다. 본 연구에서는 생태학적 수용 능력의 개념에 근거한 생태지표를 거제한산만에 적용하여, 현재의 굴 양식장의 개발 수준이 어느 정도인지를 평가하여 지속적인 생산과 효과적인 양식어장 관리 지침으로 활용하는 방안을 마련하고자 하였다.

• 한국산업보건학회지
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• 제24권2호
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• pp.193-200
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• 2014

Objectives: To develop domestic charcoal tubes with good adsorption capacity, breakthrough experiments were performed on four types of activated charcoal. Materials: The adsorption capacity and the adsorption rate were determined using a modified Wheeler equation after the breakthrough experiment. For four types of charcoal (J, K, S and SKC Inc. 226-01), 100 mg were used in the breakthrough experiment. The test was done on benzene, toluene, n-hexane, and acetone in a dynamic chamber. Results: K charcoal had the greatest surface area and the highest micropore volume. J charcoal had a similar surface area and micropore volume to SKC charcoal. S charcoal had the lowest surface area and micropore volume. J charcoal had the highest adsorption capacity at 101, 252 and 609 ppm of benzene. The gap in benzene adsorption capacity among the types of charcoal was the least at 609 ppm and the greatest at 101 ppm. J charcoal showed the highest adsorption capacity at 54, 106, 228 and 508 ppm of toluene. J charcoal and SKC charcoal had a similar adsorption capacity for acetone. J charcoal had the highest adsorption capacity for n-hexane. In the experiment featuring 10% breakthrough volume, 10% breakthrough occurred at 18 liters at $2065.9mg/m^3$ for J charcoal and at 20 liters at $1771.2mg/m^3$ for K charcoal. It was difficult to judge adsorption capacity by surface area and micropore volume of charcoal. J charcoal, which was similar to SKC charcoal in surface area and micropore volume, showed good adsorption capacity at common workplace concentrations. Conclusions: The adsorption capacity of J and K charcoal was superior compared with SKC charcoal. J and K charcoal can be considered appropriate for use as sampling media based on this result.

• Asian Journal of Business Environment
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• 제11권2호
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• pp.5-13
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• 2021

Purpose: This paper aims to study the fishing capacity of the shrimp trawlers in the Aru and Arafura Sea. Research design, data and Methodology: The abundant shrimp resources call for its sustainable use to advance economic activity. Time-series data of effort and catch from shrimp trawlers from 1980-2015 were utilized. The technical efficiencies of the vessels and the target capacity of the shrimp fishery were estimated using Peak to Peak Method. Results: Arafura's shrimp fishery presents high technical efficiency, which is suggested by the high scores of its fishing capacity utilization. The issuance of a ministerial decree on the prohibition of the use of trawls has impacted the plummeting of Arafura's shrimp trawler production right after the regulation implemented in 2015, which is far below the total production of the Arafura's shrimp trawler in 1980. Today, the Aru and Arafura Sea has different sets of fishing gears that are dominated by Squid Jigging and gillnet vessels. Conclusions: Arafura shrimp fishery performs high technical efficiency, which is indicated by the high utilization value of its catching capacity ranging from 71% to 100% annually from 1980 to 2015 This has shown that the resource-utilization has shifted from shrimps to other economically important species during the post trawl ban such as squid and pelagic. Any future intention to utilize shrimp resources, interaction of gears harvesting shrimp with current gears should be well considered in the policy making process.

• 통합자연과학논문집
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• 제16권4호
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• pp.139-145
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• 2023

Due to changes in the distribution system and increased demand for renewable energy, interest in technology to increase the limit capacity of distributed energy grid connection using grid flexible resources is also increasing. Recently, the distribution system system is changing due to the increase in distributed power from renewable energy, and as a result, problems with the limited capacity of the distribution system, such as waiting for renewable energy to connect and increased overload, are occurring. According to the power generation facility status report provided by the Korea Power Exchange, of the total power generation capacity of 134,020 MW as of 2021, power generation capacity through new and renewable energy facilities is 24,855 MW, accounting for approximately 19%, and among them, power generation through solar power accounts for a total portion of the total. It was analyzed that the proportion of solar power generation facilities was high, accounting for 75%. In the future, the proportion of new and renewable energy power generation facilities is expected to increase, and accordingly, an efficient operation plan for the distribution system is needed. Advanced country-type NWAs that can integrate the operation and management of load characteristics for each line of the distribution system, power distribution, regional characteristics, and economic feasibility of distributed power in order to improve distribution network use efficiency without expanding distribution facilities due to the expansion of renewable energy. An integrated operating system is needed. In this study, in order to improve the efficiency of distribution network use without expanding distribution facilities due to the expansion of renewable energy, we developed a method that can integrate the operation and management of load characteristics for each line of the distribution system, power distribution, regional characteristics, and economic feasibility of distributed power. We want to develop an integrated operation system for NWAs similar to that of advanced countries.

• Computers and Concrete
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• 제28권6호
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• pp.533-547
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• 2021

Calculating the shear capacity of slender reinforced concrete beams without shear reinforcement was the subject of numerous studies, where the eternal problem of developing a single relationship that will be able to predict the expected shear capacity is still present. Using experimental results to extrapolate formulae was so far the main approach for solving this problem, whereas in the last two decades different research studies attempted to use artificial intelligence algorithms and available data sets of experimentally tested beams to develop new models that would demonstrate improved prediction capabilities. Given the limited number of available experimental databases, these studies were numerically restrained, unable to holistically address this problem. In this manuscript, a new approach is proposed where a numerically generated database is used to train machine-learning algorithms and develop an improved model for predicting the shear capacity of slender concrete beams reinforced only with longitudinal rebars. Finally, the proposed predictive model was validated through the use of an available ACI database that was developed by using experimental results on physical reinforced concrete beam specimens without shear and compressive reinforcement. For the first time, a numerically generated database was used to train a model for computing the shear capacity of slender concrete beams without stirrups and was found to have improved predictive abilities compared to the corresponding ACI equations. According to the analysis performed in this research work, it is deemed necessary to further enrich the current numerically generated database with additional data to further improve the dataset used for training and extrapolation. Finally, future research work foresees the study of beams with stirrups and deep beams for the development of improved predictive models.