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Influence of moisture content on main mechanical properties of expansive soil and deformation of non-equal-length double-row piles: A case study

  • Wei, Meng;Liao, Fengfan;Zhou, Kerui;Yan, Shichun;Liu, Jianguo;Wang, Peng
    • Geomechanics and Engineering
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    • v.30 no.2
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    • pp.139-151
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    • 2022
  • The mechanical properties of expansive soil are very unstable, highly sensitive to water, and thus easy to cause major engineering accidents. In this paper, the expansive soil foundation pit project of the East Huada Square in the eastern suburb of Chengdu was studied, the moisture content of the expansive soil was considered as an important factor that affecting the mechanics properties of expansive soil and the stability of the non-equal-length double-row piles in the foundation pit support. Three groups of direct shear tests were carried out and the quantitative relationships between the moisture content and shear strength τ, cohesion c, internal friction angle φ were obtained. The effect of cohesion and internal friction angle on the maximum displacement and the maximum bending moment of piles were analyzed by the finite element software MIDAS/GTS (Geotechnical and Tunnel Analysis System). Results show that the higher the moisture content, the smaller the matrix suction, and the smaller the shear strength; the cohesion and the internal friction angle are exponentially related to the moisture content, and both are negatively correlated. The maximum displacement and the maximum bending moment of the non-equal length double-row piles decrease with the increase of the cohesion and the internal friction angle. When the cohesion is greater than 33 kPa or the internal friction angle is greater than 25.5°, the maximum displacement and maximum bending moment of the piles are relatively small, however, once crossing the points (the corresponding moisture content value is 24.4%), the maximum displacement and the maximum bending moment will increase significantly. Therefore, in order to ensure the stability and safety of the foundation pit support structure of the East Huada Square, the moisture content of the expansive soil should not exceed 24.4%.

Assessment of Potential Radiation Dose Rates to Marine Organisms Around the Korean Peninsula

  • Lee, Dong-Myung;Lee, Jun-ho
    • Journal of Radiation Protection and Research
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    • v.41 no.1
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    • pp.1-6
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    • 2016
  • Background: It is very difficult to set a regulatory guidance or criteria for the protection of non-human species from the ionizing radiation, because there are no generally or internationally accepted methods for demonstrating the compliance with such criteria. It is needed that Korea develop the primary dose rate standards for the protection of both aquatic and terrestrial biota in the near future. Materials and Methods: The potential dose rates due to both external and internal radiation exposures to marine organisms such as plaice/flounder, gray mullet, and brown seaweed collected within territorial seas around the Korean Peninsula were estimated. Results and Discussion: The total dose rates to plaice/flounder, gray mullet and brown seaweed due to $^{40}K$, a primordial radionuclide in marine environment, were found to be 0.2%, 0.08% and 0.3% of approximately the values of the Derived Consideration Reference Levels (DCRLs, i.e. $1-10mGy{\cdot}d^{-1}$), respectively, as suggested by the International Commission on Radiological Protection (ICRP) publication 124. The total dose rates to marine fishes and brown seaweed due to anthropogenic radionuclides such as $^{90}Sr$, $^{137}Cs$ and $^{239+240}Pu$ were considered to be negligible compared to the total dose rate due to $^{40}K$. The external exposure to benthic fish due to all radionuclides was much higher than that of pelagic fish. Conclusion: From this study, it is recommended that the further study is required to develop a national regulatory guidance for the evaluation of doses to non-human species.

Study on the Ground Fault Protection in 6.6KV Ungrounded Power System SGR Malfunction or Non-Tripping (선택지락보호계전기 오.부동작에 관한 연구)

  • Kim, Byung-Tae;Lee, Dal-Woo;Jeon, Myung-Soo
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.3
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    • pp.296-301
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    • 2008
  • This paper presents a study on the ground fault protection in 6.6KV ungrounded power system relay(SGR) malfunction or non-tripping. Ground test had made on 6.6KV HV(high voltage) system, Some of domestic and oversea's SGR products are different from their own specific characteristics. This study on the ground protection relay 6.6KV power supply system is focused to protect human.

A Study on the Development of a Transient Voltage Blocking Device for Info-communication Facilities (정보통신기기용 과도전압 차단장치의 개발에 관한 연구)

  • 한주순
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.2
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    • pp.159-167
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    • 1999
  • This paper presents a new transient voltage blocking device(TOBD)which low power and high frequency bandwidth to protect info-communication facilities from transient voltages. Conventional protection devices have some problems such as low frequency bandwidth low ener-gy capacity and high remnant voltage. in order to improve these limitations a hybrid type TOBD which consists of a gas tube avalanche diodes and junction type field effect transistor (JFETs) is developed. The TOBD differs from the conventional protection devices in configuration and JFETs are used as an active non-linear element and a high speed switching diode with low capacitance limited high current. Therefore the avalanche diode with low energy capacity are protected from the high current and the TOBD has a very small input capacitance. From the performance test using combination surge generator which can produce $1.2/50{\mu}m$ 4.2 kV/max, $8/20{\mu}m$ 2.1 kAmax it is confirmed that the proposed TOBD has an excellent protection per-formance in tight clamping voltage and limiting current characteristics.

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Present State and Strategies on Environmental Pollution by Animal Wastes (축산분뇨에 의한 환경오염현황과 대책)

  • 이명규;이재일
    • Journal of Animal Environmental Science
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    • v.2 no.1
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    • pp.63-78
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    • 1996
  • The main purpose of this research project is to monitor the present state of agricultural environment and to develope the countermeasures for the protection of the environment from the pollution by animal wastes. The results of this research were described largely 3 parts, 1) Monitoring of present state of environmental pollution by animal wastes, 2) Monitoring of animal wastes treatment technology, 3) Strategies for the protection of environmental pollution from animal wastes in future. The current most important problems from animal wastes are water pollution and air pollution commonly regardless of domestic or foreign country. Especially, intensive livestocks breeding pattern in restricted area is actually a real reason of eutrophication, soil acidification, ground water contamination, irrigation water pollution. As a result from this research project, authors recommend the 3 type of strategies for the protection of environmental pollution by animal wastes, 1 . Development of non-discharge type of wastes treatment technology 2. Manufacturing local structure for animal waste recycling system 3. Development of new international environmental program for transfer bioresource and soil environment prevention.

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The Effect of Goomcheongsim-won(구미청심원) Extracts on E20 Corticells and P7 Cerebellar Cells Exposed to Hypoxia (구미청심원이 저산소증 유발 배양신경세포에 미치는 영향)

  • 한기선;정승현;신길조;문일수;이원철
    • The Journal of Korean Medicine
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    • v.23 no.1
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    • pp.120-132
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    • 2002
  • Objectives : The purpose of this investigation was to evaluate the effect of Goomicheongsim-won Extracts on E20 corticells and P7 cerebellar cells exposed to hypoxia, and the effect on neuronal protection by elimination of Rhinoceros unicornis L. and/or Orpiment $As_2S_3$. Methods : P7 cerebellar cells were grown in various concentrations of KM-A, KM-B, KM- C and KM-D. On 7 DIV (day in vitro), cells were exposed to hypoxia (98% $N_2/5%{;}CO_2,{\;}3{\;}hr,{\;}37^{\circ}C$) and normoxia, and then further incubated for 3 days. Neuronal viabilities were expressed as percentages of control. E20 cortical cells were grown in various concentrations of KM-A, KM-B, KM-C, and KM-D. On 7 DIV, cells were exposed to hypoxia and normoxia, and then further incubated for 3 and 7 days. Results : I. The effect of KM-A on neuronal protection was significantly increased P7 cerebellar granule cells and E20 cortical cells on normoxia and hypoxia. 2. The effect of KM-B on neuronal protection was increased P7 cerebellar granule cells on normoxia, but was significantly decreased P7 cerebellar granule cells on hypoxia. The effect of KM-B on neuronal protection was non-significantly increased E20 cortical cells on normoxia and hypoxia. 3. The effect of KM-C on neuronal protection was non-significantly increased P7 cerebellar granule cells on normoxia and hypoxia and was decreased (p=0.058) on hyperconcentration of the extracts in normoxia. The effect of KM-C on neuronal protection was significantly increased P7 cerebellar granule cells and E20 cortical cells on normoxia and hypoxia (10 DIV), and the effect was E20 cortical cells on normoxia (14 DIV), non-significantly increased E20 cortical cells on hypoxia (14DIV). 4. The effect of KM-D on neuronal protection was increased P7 cerebellar granule cells on normoxia but was not on hyperconcentration of the extracts, was significantly decreased on hyperconcentration of the extracts in hypoxia. The effect of KM-D on neuronal protection was significantly increased E20 cortical cells on normoxia and was significantly increased E20 cortical cells increased on hypoxia (10 DIV). Conclusions : Goomicheongsim-won extracts had applicable effect on E20 corticells and P7 cerebellar cells exposed to hypoxia. The effect on neuronal protection by elimination of Rhinoceros unicornis L. and/or Orpiment $As_2S_3$ was changed.

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A Study on the Protection Functionality of Supermodern Fashion (슈퍼모던 패션의 보호기능에 관한 연구)

  • Kim, Wan-Joo;Lee, Keum-Hee
    • Journal of the Korean Society of Clothing and Textiles
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    • v.32 no.8
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    • pp.1264-1273
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    • 2008
  • The purpose of this study is to analyze protection functionality of supermodern fashion which is shown by responding to supermodern environment, where non-spaces increases in the 21st modern city. The theoretical background is drawn for supermodern environment theory. For the study, he researcher used existing study and specialized book and analyzed photograph materials by selecting them in specialized fashion book, internet site and designer's collection. The works from 1995 S/S collection to 2008 S/S collection are analyzed. The result of this study is as follow. First, supermodern design is adopting the shape of high-functional element, electronic device, protective device to protect wearer in non-space. Second, in order to mentally protect individual anonymous leadership of interaction is granted by adopting hood, veil or mask. Third, supermodern design is creating independent and user-based space by shape transformation in change of urban environment. Fourth, in order to protect wearer through camouflage or concealment, camouflage pattern or neutral color are used.

Development of Wave Breaking Construction Method for Shore Protection using New Type of Precast Preforated Concrete Block (프리캐스트 유공식 호안블록을 이용한 소파감쇄 신공법개발)

  • 이주호;박광순;박경래;염종윤;배한욱
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.10a
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    • pp.743-748
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    • 1997
  • In this paper, a new type of precast perforated concrete block is presented to be used in the construction of a step seawall. The overtopping rate of the perforated step seawall is lower than that of the traditional non-perforated step seawall. In construction stage, the cost of total construction of the perforated block is cheaper than that of traditional block. The new type of perforated block may be used as an alternative for shore protection facility.

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Partitioning Interwell Tracer Test for NAPL Source Characterization: A General Overview

  • Lee, Tony R.;A. Lynn Wood;Jeong, Seung-Woo
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2002.04a
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    • pp.159-162
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    • 2002
  • Innovative and nondestructive characterization techniques have been developed to locate and quantify nonaqueous phase liquids (NAPLs) in the vadose and saturated zones in the subsurface environment. One such technique is the partitioning interwell tracer test (PITT). The PITT is a simultaneous displacement of partitioning and non-partitioning tracers through a subsurface formation. Partitioning tracers will partition into the NAPL during their transport through NAPL-contaminated formations. Mean travel times of partitioning and non-partitioning tracers are used to estimate the quantity of NAPL encountered by the displaced tracer pulse. Travel times are directly proportional to the partitioning coefficient and the volume of NAPL contacted in the subsurface environment. This paper discusses the conceptual background, design and implementation of PITTs. (This document has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency, and no official endorsement should be inferred.)

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Protection for a Wind Turbine Generator in a Large Wind Farm

  • Zheng, Tai-Ying;Kim, Yeon-Hee;Kang, Yong-Cheol
    • Journal of Electrical Engineering and Technology
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    • v.6 no.4
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    • pp.466-473
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    • 2011
  • This paper proposes a protection algorithm for a wind turbine generator (WTG) in a large wind farm. To minimize the outage section, a protection relay for a WTG should operate instantaneously for an internal fault or a connected feeder fault, whereas the relay should not operate for an internal fault of another WTG connected to the same feeder or an adjacent feeder fault. In addition, the relay should operate with a delay for an inter-tie fault or a grid fault. An internal fault of another WTG connected to the same feeder or an adjacent feeder fault, where the relay should not operate, is determined based on the magnitude of the positive sequence current. To differentiate an internal fault or a connected feeder fault from an inter-tie fault or a grid fault, the phase angle of the negative sequence current is used to distinguish a fault type. The magnitude of the positive sequence current is then used to decide either instantaneous operation or delayed operation. The performance of the proposed algorithm is verified under various fault conditions with EMTP-RV generated data. The results indicate that the algorithm can successfully distinguish instantaneous operation, delayed operation, or non-operation depending on fault positions and types.