• Journal of the Korean Geosynthetics Society
• /
• v.22 no.1
• /
• pp.39-51
• /
• 2023

The bearing capacity of the prebored pile has been studied by many researchers. However, The bearing capacity of the prebored pile has been studied by many researchers. However, comparative studies between design data and pile load test data on the load sharing ratio and the settlement were insignificant. Therefore, the design data and the static load test results were compared for the prebored open-end steel piles. In the compressive static pile load test, the load sharing ratios of the base resistance and the shaft resistance were 13%~40% and 60%~87%, respectively and the settlements were measured 2.2mm~4.7mm. In the current bearing capacity calculation formula, the base resistance was shared between 54% and 75%, and the shaft resistance was shared between 25% and 46% and the settlements were calculated about 19.8mm~23.6mm. The settlement in the current bearing capacity calculation formula was 321% to 776% (average : 445%) larger than the settlement in the result of load test. When the settlement were calculated using the load sharing ratio in the pile load tests, it was 137% to 525% larger than the test settlement, and it was as large as 204% on average. It was confirmed that an appropriate evaluation of the load sharing ratio had an important effect on the calculation of pile settlement.

• Journal of Power Electronics
• /
• v.11 no.5
• /
• pp.639-654
• /
• 2011

This paper presents a Current Distribution Control design for Paralleled Positive Output Elementary Super Lift Luo Converters (PPOESLLCs) operated in Continuous Conduction Mode using a Sliding Mode Controller (SMC). Manipulating the higher current requirement of the load through the paralleling of POESLLCs, results in a current inequality. This is mainly due to dissimilarities in the power semiconductor switches and circuit components used in POESLLCs, which may lead to converter failures. In order to balance the proper load current sharing and the load voltage regulation of PPOESLLCs, a SMC is developed. The SMC is designed for the inherently variable-structured of POESLLCs by using the state-space average based model. The static and dynamic performance of the developed controller with PPOESLLCs is validated for its robustness to perform over a wide range of operating conditions through both a laboratory prototype and MatLab/Simulink models, which are compared with a Proportional-Integral (PI) controller. Theoretical analysis, simulation and experimental results are presented to demonstrate the feasibility of the developed SMC along with the complete design procedure.

• Progress in Superconductivity and Cryogenics
• /
• v.24 no.2
• /
• pp.7-18
• /
• 2022

European efforts to design superconducting conductors for a future tokamak have involved Nb₃Sn cable-in-conduit conductor (CICC). Nb₃Sn coils which undergo heat treatment to activate the Nb₃Sn material are mostly produced through the wind-then-react route. However, some Nb₃Sn coils have been proposed with CICCs of the react-then-wind route. The latter CICCs are physically constrained due to handling limitations which if not adhered to will result in irrecoverable damage to the Nb₃Sn cable inside, nullifying any performance advantage. A group at the Swiss Plasma Center has proposed such CICC designs, constructing samples and testing them for performance. The characteristics and performance of these react & wind (R&W) CICCs are compared with the more common wind & react (W&R) CICCs, and it is found that the R&W designs show more extreme characteristics than typical W&R Nb₃Sn CICCs for some parameters that are known to influence CICC performance. Where the R&W CICCs extend the range of those parameters, they also continue trends formed by the W&R CICCs with the parameters. The main observation, however, is that although the current sharing temperature performances of the R&W samples are above the average of the W&R samples they were compared to, they are not the highest. A similar observation applies to a cost comparison of the superconducting material where the R&W CICCs are found to be relatively cheap but not the cheapest. Given these results, clear practical advantages to the R&W CICC design is not evident.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.1129-1132
• /
• 1992

This paper proposes a high frequency resonant inverter consisting of equivalent half bridge model using MOSFET. In this paper time-sharing control method is applied. as a result the output frequency is two times as high as switching frequency of device, and average current of device is incresed because of decreasing switching loss.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.10
• /
• pp.2790-2796
• /
• 1999

In video-on-demand systems, the I.O bandwidth of video servers is the critical resource which contributes to increase in latency. Several approaches: bridging, piggybacking are used to reduce the I/O demand on the video server through sharing. Batching delays the requests for the different videos for a batching window so that more requests for the same video arriving during the current batching window may be served using the same stream. In this paper, we propose an adaptive reservation-based batching policy which dynamically reserves video server capacity for popoular videos according to video server loads. The performance of the proposed policy is evaluated through a simulation, and is compared with simple batching and static reservation-based batching policies. As the result, we know that the adaptive reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching polices.

• Journal of Power Electronics
• /
• v.7 no.3
• /
• pp.265-270
• /
• 2007

Equal rating DC-DC converter modules can be connected in series at the input for circuits requiring higher input voltages and in parallel at the output for circuits requiring higher output currents. Since the converter modules may not be practically identical, closed loop control has to ensure that each module equally shares the total input voltage and the load current. A control scheme consisting of a common output voltage loop, individual inner current loops and individual input voltage loops have been designed in this work to achieve input voltage and load current sharing as well as load voltage regulation under supply and load disturbances. The output voltage loop provides the basic reference for the inner current loops, which are also modified by the respective input voltage loops. The average of the converter input voltages, which is dynamically varying, is chosen as the reference for input voltage loops. This choice of reference eliminates interaction among different control loops. Type II compensators and Fuzzy Logic Controllers (FLCs) are designed and compared through MATLAB based simulation and FLC is found to be satisfactory. Hence TMS320F2407A DSP based FLC is implemented and the results are presented which prove the superiority of the FLC developed for this research.

• Water for future
• /
• v.52 no.8
• /
• pp.56-66
• /
• 2019

Nepal is bestowed with abundant water. With more than 1500 mm average annual rainfall in the country, a vast quantity of underutilized groundwater in the Terai belt, and the water stored in snowcaps in the Himalayas, aquifers in the mountains and glacial lakes, Nepal is potentially in an advantageous position in terms of per capita availability. However, low emphasis in management aspect of water and high emphasis in infrastructural developments related to water resources management has resulted in conversion of water in Nepal from a resource to a burden. The global climate change, reduction in number of rainy days, increase in intensity of rainfall during wet monsoon season, encroachment of river banks for settlement, inadequate release of environmental flows from hydropower plants, and attempt to tame the mighty and high velocity rivers of Nepal have resulted in increasing number of water induced disasters (flood and landslide), rise in conflict between local residents and hydropower developers, higher number of devastating landslides, and in some extreme cases mass migration of residents resulting in climate refugees. There is a ray of hope; the awareness level of the people regarding sustainable use of water resources is increasing, the benefit sharing mechanism is gradually being implemented, the role of interdisciplinary and integrated water resources management is appreciated at a higher level and the level of preparedness against flood and landslides is at a higher degree compared to a couple of decades ago. With the use of renewable energy sources, the possibilities for sustainable and productive use of water are on the rise in Nepal.

• Journal of Digital Contents Society
• /
• v.18 no.2
• /
• pp.411-422
• /
• 2017

Current policies for sharing bandwidth increase average throughput and improve utilization of the bandwidth in the local network. However, with these policies, a central administer, which is responsible for allocating bandwidth to each network flow, cannot allocate resources based on user characteristics. Thus, it leads to unfair bandwidth allocation because it does not guarantee services based on user characteristics. Therefore, we propose a novel negotiation method to share the bandwidth in a limited bandwidth network, in which, a user negotiates with other users to gain more resource. Ideally, we use a fuzzy system to infer and determine whether a device will request bandwidth or not based on the current usage of the given device. We conduct two experiments consisting of a video streaming simulation in OPNET and a real-time video streaming in WebRTC. The results of the experiment indicate that the proposed method can flexibly share the bandwidth utilization based on user's requirement in the network.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.54-56
• /
• 2018

본 논문은 평균 전류 분담 기법을 적용한 UPS(Uninterruptible Power Supply) 시스템의 병렬 운전 기법을 제안한다. 각각의 UPS는 전류 정보를 공유하기 위하여 CAN 통신을 사용하며, 이중 루프 방식의 전압, 전류제어기로 구성되어 있다. UPS의 전류 분담 성능을 내부 전류 제어기의 피드백 전류인 인덕터 전류, 커패시터 전류 그리고 통신 시지연에 따라 영향을 분석하고 3상 30kVA급 UPS에 적용하여 그 유효성을 검증하였다.

• Health Policy and Management
• /
• v.29 no.3
• /
• pp.374-378
• /
• 2019

After the announcement of Moon Jae-in Government's plan (Moon's Care) for Benefit Expansion in National Health Insurance in August 2017, it is necessary to monitor the effects of the policy, especially household out-of-pocket payments (OOP). This paper aims to observe the current status and trend of OOP in Korea. Current health expenditure (CHE) was 144.4 trillion won in 2018, which accounts for 8.1% of gross domestic product (GDP) increased 9.7% from the previous year. Although GDP's share of CHE has been close to the average of the Organization for Economic Cooperation and Development (OECD) countries, the public fund's share was 59.8% of the total in 2018, which was lower than the OECD average of 73.5%. OOP's share was 32.9% in 2018, which decreased from 37.4% in 2008. The share of OOP of non-covered services was 20.0% in 2018, which decreased from 22.9% in 2008. The share of cost-sharing with third-party payers was 12.9% in 2018, which decreased from 14.5% in 2008. The OOP of non-covered services was significantly decreased in hospital and inpatient curative care, but the OOP of non-covered services was significantly increased in the medical clinic. The effect of Moon's Care was not showed in OOP through the results of 2017 and 2018, but further monitoring is needed because the Moon's Care is progressing and the observational period is short.