• Title/Summary/Keyword: improved ground

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Behavioral Characteristics of Improved Ground by Fully Penetrated and Partially Penetrated SCP according to Construction Stage (관통SCP와 미관통SCP로 개량된 지반의 시공단계별 거동 특성)

  • Park, Jongseo;Ahn, Kwangkuk
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.12
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    • pp.51-57
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    • 2012
  • In this study, numerical analysis was carried out for both partially penetrated SCP(sand compaction pile) and fully penetrated SCP constructed into the ground. Midas GTS was used as a FEM analysis program, which is widely used in geotechnical engineering. For the analysis, ground displacement, effective stress and pore water pressure at the time both just after embankment on the ground and 365days later were compared and analyzed. As the results, the effect regarding partially penetrated SCP was similar to the effect regarding fully penetrated SCP under the bottom of the center of embankment when considering the safety towards shear failure.

Evaluation of the grouting in the sandy ground using bio injection material

  • Kim, Daehyeon;Park, Kyungho
    • Geomechanics and Engineering
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    • v.12 no.5
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    • pp.739-752
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    • 2017
  • This study was intended to evaluate the improved strength of the ground by applying the bio grouting method to a loose sandy ground. The injection material was prepared in the form of cement-like powder, with the bio injection material produced by microbial reactions. The grouting test was conducted under the conditions similar to the field where the bio injection material can be applied. In addition, the injection materials (cement and sodium silicate No. 3) used for Labile Waterglass (LW) method and the conventional grouting methodwere prepared through a two-solution one-step process. The injection into the specimens was done at a pressure of 150 kPa and then, with a bender element, their moduliof elasticity were measured on the 7th, 14th, 21st and 28th curingdays to analyze their strengths according to the duration of curing. It was confirmed that in all injection materials the moduli of elasticity increased over time. In particular, when 30% of the bio injection material was added to 100% cement, the modulus of elasticity tended to increase by about 15%. This confirmed that the applicability became higher when the bio injection material was used in place of the conventional sodium silicate.

Numerical Analysis on Offshore Wind Power System Foundation (해상풍력단지 기초에 관한 수치해석적 연구)

  • Kim, Dong-Ho;Jang, Won-Yil;Kim, Seong-Yun;Shin, Sung-Ryul;Lim, Jong-Se;Yoon, Ji-Ho
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.2
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    • pp.355-361
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    • 2009
  • Onshore wind farms having several problems, difficult to secure a building site and incur the enmity of the people. Therefore, offshore wind farms are increasingly expected, because there are huge resource and large site in offshore. If huge wind turbines are constructed, the offshore wind power base is concerned about subsidence. In order to confirm the ground stability, estimation of subsidence is necessary. In this paper, the subsidence is predicted by continuity model when the gravity and the mono-pile base are constructed on soft ground. The FLAC 3D, three dimensional FDM program, was adopted to analysis subsidence. Input factors are yielded by geological information at the yeompo quay in ulsan and the results of laboratory experiments. It has been compared that the original ground with improved ground under the gravity base, and constructed mono-pile under the mono-pile base.

Gait Training Strategy Focusing on Perceptual Learning for Improved Gait Capacity in Stroke Survivors

  • Jung, Jee Woon
    • The Journal of Korean Physical Therapy
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    • v.32 no.5
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    • pp.283-289
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    • 2020
  • Objective: The purpose of this study was to determine the force of lower extremities, the change in walking ability on the ground by applying a walking training program based on perceptual learning to improve gait capacity of chronic stroke patients. Method: This study included Twenty-four patients with chronic stroke. Using a perceptual-based gait training, the experimental group trained twice a day for 30 minutes each time, 5 times a week, for a total of 8 weeks. The control group underwent ground gait training that excluded the element of a perceptual training for 30 minutes, 5 times a week for 8 weeks. Results: In the two groups, the maximum forefoot pressure after intervention was significantly different in both the LEPGT and GGT (p<0.05). The maximum midfoot pressure was significantly different in LEPGT (p<0.05). There was a significant difference in the maximum heel pressure after intervention between the two groups (p<0.05). As a result of comparing the change in step length and stride length after intervention in the two groups, there was a significant difference between the two groups (p<0.05). Conclusion: Both gait training programs was found that gait training based on perceptual learning and ground gait training were the training for improving the functional gait of stroke patient. Perceptual learning gait training utilizing intensive perceptual awareness was the training for improving gait capacity within the period than ground gait training.

Improved Characteristic of Radiated Emission of a PCB by Using the Via-Hole Position (단일 비아 위치를 이용한 PCB의 복사성 방사 성능 향상)

  • Kim, Li-Jin;Lee, Jae-Hyun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.12
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    • pp.1272-1278
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    • 2009
  • The cancellation method of P/G(power/ground) plane resonances which are generated between the power plane and the ground plane in a 4-layer PCB(Printed Circuit Boards) with a via-hole for the improvement of the RE(Radiated Emission) characteristic is presented. The validity of the proposed method was confirmed from simulation and measurement of performances of signal transmission characteristic, intensities of edge-radiation and radiated emission of PCB with a via-hole.

Unbalanced Characteristics of the Superconducting Fault Current Limiters with a Single Line-to-ground Fault (1선 지락사고에 대한 초전도한류기의 불평형 특성)

  • Choi, Hyo-Sang;Lee, Na-Young;Lee, Sang-Il
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.9
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    • pp.851-855
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    • 2005
  • We investigated the unbalanced characteristics of the superconducting fault current limiters (SFCLs) based on YBCO thin films with a single line-to-ground fault. When a single line-to-ground fault occurred, the short circuit current of a fault phase increased about 6 times of transport currents after the fault onset but was effectively limited to the designed current level within 2 ms by the resistance development of the SFCL. The fault currents of the sound phases almost did not change because of their direct grounding system. The unbalanced rates of a fault phase were distributed from 6.4 to 1.4. It was found that the unbalanced rates of currents were noticeably improved within one cycle after the fault onset. We calculated the zero phase currents for a single line-to-ground fault using the balanced component analysis. The positive sequence resistance was reduced remarkably right after the fault onset but eventually approached the balanced positive resistance component prior to the system fault. This means that the system reaches almost the three-phase balanced state in about 60 ms after the fault onset at the three-phase system.

Reduction of short channel Effects in Ground Plane SOI MOSFET′s (Growld Plane SOI MOSFET의 단채널 현상 개선)

  • ;;;;Jean-Pierre Colinge
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.4
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    • pp.9-14
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    • 2004
  • This paper reports the measurement and analysis of the short channel effects and the punchthrough voltage of SOI-MOSFET with a self-aligned ground plane electrode in the silicon mechanical substrate underneath the buried oxide. When the channel length is reduced below 0.2${\mu}{\textrm}{m}$ it is observed that the threshold voltage roll-off and the subthreshold swing with channel length are reduced and DIBL is improved more significantly in GP-SOI devices than FD-SOI devices. It is also observed from the dependence of threshold voltage with substrate biases that the body factor is a higher in GP-SOI devices than FD-SOI devices. From the measurement results of punchthrough voltage, GP-SOI devices show the higher punchthrough voltages than FD-SOI devices

Visual Precise Measurement of Pile Rebound and Penetration Movement Using a High-Speed Line-Scan Camera

  • Lim, Mee-Seub;You, Bum-Jae;Oh, Sang-Rok;Han, Song-Soo;Lee, Sang-Hun
    • Transactions on Control, Automation and Systems Engineering
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    • v.4 no.4
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    • pp.341-346
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    • 2002
  • When a construction company builds a high structure. many piles should be driven into the ground by a hammer whose weight is 7,000 kg in order to make the ground under the structure safe and strong. So. it is essential to determine whether a pile is penetrated into the ground enough to support the weight of the structure since ground characteristics at different locations are different each other. This paper proposes a visual measurement system for pile rebound and penetration movement including vibration using a high-speed line-scan camera and a specially designed mark to recognize two-dimensional motion parameters of the mark using only a line-scan camera. A mark stacking white and black right-angled triangles is used for the measurement, and movement information for vertical distance, horizontal distance and rotational angle is determined simultaneously. Especially- by adopting a line-scan CCD camera whose line rate is 20 ㎑. the measurement performance of dynamic characteristics of the pile at impact instant is improved dramatically.

Effects of Calcium Powder Mixtures and Binding Ingredients as Substitutes for Synthetic Phosphate on the Quality Properties of Ground Pork Products

  • Cho, Min Guk;Jeong, Jong Youn
    • Food Science of Animal Resources
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    • v.38 no.6
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    • pp.1179-1188
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    • 2018
  • This study aimed to investigate the combined effect of using natural calcium mixtures and various binding ingredients as replacers for synthetic phosphate in ground pork products. We performed seven treatments: control (0.3% phosphate blend), treatment 1 (0.5% natural calcium mixtures [NCM, which comprised 0.2% oyster shell calcium and 0.3% egg shell calcium powder] and 0.25% egg white powder), treatment 2 (0.5% NCM and 0.25% whey protein concentrate), treatment 3 (0.5% NCM and 0.25% concentrated soybean protein), treatment 4 (0.5% NCM and 0.25% isolated soybean protein), treatment 5 (0.5% NCM and 0.25% carrageenan), and treatment 6 (0.5% NCM and 0.25% collagen powder). All the treatment mixtures had higher pH and lower cooking loss than the control, which was treated with phosphate. We found that NCM and binding ingredients had no negative effects on the moisture content, lightness, and yellowness of the cooked ground pork products. Treatments 3 and 4 showed significantly lower CIE $a^*$ values than the control. Treatments 2 and 6 improved the textural properties of the products. In conclusion, the combination of NCM with whey protein concentrate or collagen powder could be suitable for producing phosphate-free meat products.

Hazard-Consistent Ground Displacement Estimation for Seismic Input of Underground Utility Tunnels in Korea (국내 재해도에 상응하는 공동구의 지반변위 산정)

  • Kim, Dae-Hwan;Lim, Youngwoo;Chung, Yon-Ha;Lee, Hyerin
    • Journal of the Korean Geotechnical Society
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    • v.37 no.12
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    • pp.7-23
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    • 2021
  • Underground utility tunnels, which contribute to supply of electricity, communication, water and heat, are critical lifelines of an urban area. In case service is discontinued or functional disruption happens, there will be a huge socio-economic impact. For the improved seismic design and evaluation of underground structures, this study proposes a ground displacement measure when the site is subjected to a scenario earthquake based on hazard-consistent source spectra and site amplification/attenuation. This measure provides a rational estimation of ground displacement and can be an alternative to existing response displacement methods.