• Title/Summary/Keyword: 전기침투

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The Physical Properties Variation of Grout Materials and Improvement of Grouting Effects on Application of High Performance Injection Equipment (고성능 주입장비의 적용에 따른 주입재의 물성변화 및 주입효과 증진에 관한 연구)

  • 천병식;김진춘;김백영
    • Journal of the Korean Geotechnical Society
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    • v.19 no.4
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    • pp.179-190
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    • 2003
  • The grout based on solution type makes it difficult to get the improvement of ground strength and the effefct of water curtain because it has lower strength and durability than suspension type. Nowadays, the technology of particle acceleration, that enhance the material permeability, such as grout based on solution type, and inexpensive grout, is being required. For these reasons, in this study, using wet milling system, we evaluated physical properties of manufactured factors such as water-cement ratio of particles before being milled, optimum milling capacity by controlling milling time and rpm, viscosity of materials, permeation coefficient, and unconfined compressive strength. Also, using micro wet milling apparatus which could manufacture ordinary Portland cement and high speed shear mix which could forcefully separate conglomerate particles in situ, we performed electrical resistivity investigation and falling head permeability tests to analyze differences of grouting effects. From these results, we found that the permeability of the applied equipment was much superior, and in the case of using high speed shear mixer, particles of grout material were well separated.

Hydrogen Embrittlement of TRIP Steel Charged with Hydrogen Under Two Type Electrolytes (2종 전해질 분위기하 수소주입된 TRIP 강의 수소취성)

  • Choi, Jong-Un;Lee, Sang-Wook;Lee, Kyung-Min;Kang, Kae-Myung
    • Journal of the Korean Institute of Gas
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    • v.19 no.1
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    • pp.57-63
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    • 2015
  • The hydrogen was charged TRIP steel by electrochemical method under 0.5M $H_2SO_4$ electrolyte and 0.5M NaOH electrolyte with hydrogen charging conditions respectively. The degree of hydrogen embrittlement of TRIP steel was evaluated by using micro Vickers hardness tests. These results showed that the degree of hydrogen embrittlement in acidic electrolyte with hydrogen penetration and hydrogen diffusion through the depth of specimen was more sensitive than its alkaine electrolyte between two type electrolytes. However, it was investigated that micro Vickers hardnesses of surface in acidic electrolyte under two electrolyte were higher than those of alkaine electrolyte. It was thought that in case of hydrogen embrittlement in acid-ice electrolyte, hydrogen charging time was more effective than current density, in case of alkaine electrolyte, hydrogen current density was more effective than charaging time.

Effect of Compressive Loading on the Chloride Penetration of Concrete Mixed with Granulated Blast Furnace Slag (고로슬래그미분말을 혼입한 콘크리트의 염분침투성에 미치는 압축하중의 영향)

  • Kim, Dong-Hun;Lim, Nam-Gi;Horiguchi, Takashi
    • Journal of the Korea Institute of Building Construction
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    • v.9 no.6
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    • pp.71-78
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    • 2009
  • The analysis of the effect of loading on chloride penetration into concrete is very important. In this study, we confirmed that the chloride penetration rates for plain and BFS concrete were increased by 47% and 89% under compressive stress, respectively. The diffusion coefficient of BFS concrete was lower than for conventional concrete with no BFS, no loads, and under stressed states. Therefore, BFS substitution plays an important role in the repression of chloride penetration even under compressive stress. Under compressive stress,the diffusion coefficient for BFS concrete was higher with increasing stress, and this was also the case for plain concrete. However, BFS concrete was strongly influenced by compressive stress in comparison to plain concrete. We investigated the effect of the difference of specific surfaces on the diffusion coefficient. As a result, the larger specific surface of BFS exhibited a lower diffusion coefficient. This tendency was most pronounced under the high stress conditions.

The Diffusion Property of Chloride Ion into Concrete by Electrically Accelerated Method (전기적인 촉진시험에 의한 콘크리트의 염화물이온 확산특성)

  • Bae, Ju-Seong;Park, Gook-Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.3
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    • pp.138-143
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    • 2010
  • Recently, as many big marine concrete structures increase, it is necessary that chloride ion diffusion coefficient of concrete shall be evaluated but it will take a long time to evaluate chloride ion diffusion coefficient of concrete. Accordingly, many test methods are suggested to evaluate chloride ion diffusion coefficient in a short period time by the promotion in electro chemical ways but the systematic study for this is insufficient. Therefore, this study evaluates chloride ion penetration and diffusion features by three representative electric promotion tests targeting for three different cements whose ingredients are different and analyzes the correlationship between them. As a result, diffusion features of chloride ion varied according to the cement ingredients and three ingredients cement in which blast furnace slag powder and fly ash are mixed in constant ratio, which shows the most excellent cement diffusion properties. For diffusion properties of chloride ion, the correlationship between test methods are good.

Hybrid Fabrication of Screen-printed Pb(Zr,Ti)O3 Thick Films Using a Sol-infiltration and Photosensitive Direct-patterning Technique (졸-침투와 감광성 직접-패턴 기술을 이용하여 스크린인쇄된 Pb(Zr,Ti)O3 후막의 하이브리드 제작)

  • Lee, J.-H.;Kim, T.S.;Park, H.-H.
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.4
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    • pp.83-89
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    • 2015
  • In this paper, we propose a fabrication technique for enhanced electrical properties of piezoelectric thick films with excellent patterning property using sol-infiltration and a direct-patterning process. To achieve the needs of high-density and direct-patterning at a low sintering temperature (< $850^{\circ}C$), a photosensitive lead zirconate titanate (PZT) solution was infiltrated into a screen-printed thick film. The direct-patterned PZT films were clearly formed on a locally screen-printed thick film, using a photomask and UV light. Because UV light is scattered in the screen-printed thick film of a porous powder-based structure, there are needs to optimize the photosensitive PZT sol infiltration process for obtaining the enhanced properties of PZT thick film. By optimizing the concentration of the photosensitive PZT sol, UV irradiation time, and solvent developing time, the hybrid films prepared with 0.35 M of PZT sol, 4 min of UV irradiation and 15 sec solvent developing time, showed a very dense with a large grain size at a low sintering temperature of $800^{\circ}C$. It also illustrated enhanced electrical properties (remnant polarization, $P_r$, and coercive field, $E_c$). The $P_r$ value was over four times higher than those of the screen-printed films. These films integrated on silicon wafer substrate could give a potential of applications in micro-sensors and -actuators.

Chloride Penetration of Concrete Mixed with High Volume Fly Ash and Blast Furnace Slag (FA 및 BFS를 다량 혼입한 콘크리트의 염분침투성)

  • Park, Ki-Cheul;Lim, Nam-Gi
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.1
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    • pp.90-99
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    • 2015
  • This study examined dynamic and characteristics and chloride penetration of concrete mixed with large amount of FA and BFS, which are considered for positive application to construction fields with purpose of long-tern durability of concrete structures. As a result of strength test on FA and BFS, FA concrete showed higher increase of strength compared to OPC, when FA4000 and FA5000 were mixed 30%, respectively. For BFS concrete, those mixed with 30% and 50% of BFS8000, respectively, showed higher or equivalent strength compare to OPC. As a result of test of chloride penetration on FA and BFS, diffusion coefficients of concrete mixed with 30% FA4000 and FA5000, respectively, showed to restrain average 6.5% of diffusion coefficient compared to OPC. And in case of BFS concrete, those mixed with BFS6000 and BFS8000, restrained diffusion of chloride ions 253% and 336%, respectively, compared to OPC. Therefore, Mixing 50% of BFS was most efficient in order to maximize restraint of chloride penetration according to metathesis of large amount. For relation between compression strength and diffusion coefficient of FA and BFS concrete, as strength increased, diffusion coefficient decreased. In this study, when mixing FA and BFS to concrete for long-run durability and restraint against chloride penetration, for FA, mixing it to concrete with less or equivalent 30% of replacement rate was most efficient. And for BFS, as fineness was higher and mixing it to concrete with less or equivalent 50% of replacement rate, there were results of higher strength compared to OPC and more efficient restraint of chloride ions.

The Development of Multi-channel Electrical Conductivity Monitoring System and its Application in the Coastal Aquifer (다채널 전기전도도 모니터링 시스템의 개발과 연안지역 공내수 모니터링에 대한 적용 사례)

  • Shin, Je-Hyun;Hwang, Se-Ho;Park, Kwon-Gyu;Park, Yun-Seong;Byun, Joong-Moo
    • Geophysics and Geophysical Exploration
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    • v.8 no.2
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    • pp.156-162
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    • 2005
  • Particularly in research related to seawater intrusion the change of fluid electrical conductivity is one of major concerns, and effective monitoring can help to optimize a water pumping performance in coastal areas. Special considerations should be given to the mounting of sensors at proper depth during the monitoring design since the vertical distribution of fluid electrical conductivity is sensitive to the characteristics of seawater intrusion zone. This tells us the multi-channel electrical conductivity monitoring is of paramount consequence. It, however, is a rare event when this approach becomes routinely available in that commonly used commercial stand-alone type sensors are very expensive and inadequate for a long term monitoring of electrical conductivity or water level due to their restricted storage and difficulty of real-time control. For this reason, we have developed a real-time monitoring system that could meet these requirements. This system is user friendly, cost-effective, and easy to control measurement parameters - sampling interval, acquisition range, and others. And this devised system has been utilized for the electrical conductivity monitoring in boreholes, Yeonggwang-gun, Korea. Monitoring has been consecutively executed for 24 hours, and the responses of electrical conductivity at some channels have been regularly increased or decreased while pumping up water. It, with well logging data implemented before/after pumping water, verifies that electrical conductivity changes in the specified depths originate from fluid movements through sand layer or permeable fractured rock. Eventually, the multi-channel electrical conductivity monitoring system makes an effective key to secure groundwater resources in coastal areas.

축열공조 시스템의 최근 동향

  • 대한전기협회
    • JOURNAL OF ELECTRICAL WORLD
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    • s.273
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    • pp.60-66
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    • 1999
  • 에너지 공급기반이 취약한 일본에서 에너지의 이용효율 향상과 에너지 절약의 촉진은 중요한 과제의 하나이다. 이를 위하여 일본 정부는 1997년 4월 ''종합에너지대책 추진 각료회의''에서 자에너지의 추진과 전력공급의 안정 및 공급설비의 증대 억제에 의한 전력공급코스트의 저감을 위하여 전력부하 평준화의 추진을 결정하였다. 이것에 이어 ''97년 7월에는 ''전력부하평준화대책검토위원회''가 발족되고 12월에는 중간보고로서, ''전력코스트삭감=축열공조(저온도 포함) 보급확대''가 제안되어 거국적인 축열 보급확대의 필요성이 인식되게 되었다. 빙축열 공조시스템은 주간 전력소비를 억제하고 야간전력을 사용함으로써 탄산가스 배출을 삭감하는 효과도 기대되고 있어, 앞으로 일본 국내 공조시스템의 일익을 담당하며 국가에 의한 지원도 받아 급속한 시장침투가 확대될 것으로 전망되고 있다. 미쓰비시전기에서는 타사에 앞서서 선진적인 빙축열 공조시스템을 제작$\cdot$판매하고 있으며 업계의 선도적 위치를 유지하고 있다.

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A study on the detection method of environment toxic gases by using electrical signal (전기적 신호처리에 의한 환경유해물질 검출연구)

  • Chon, Y.K.;Sun, J.H.;Lee, T.S.
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.1997-2000
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    • 1999
  • 본 연구에서 제시하는 기공세라믹(Porous Ceramic)에 의한 누설전류 측정법은 기공 사이즈가 일정한 Open Pore Cell내에서 도전성 물질 및 이온화된 물질이 기공 사이에 침투되었을 때 외부에서 전계를 가하므로 써 이들 이온화 된 물질이 chain처럼 배열되어 전기적 병렬회로를 구성시켜 미세한 누설전류를 흐르게 한다. 이 누설전류법에 의한 도전성분 검출을 여러 환경 배출가스에 대한 모의실험을 실시한 결과 기공세라믹인 센서 자체의 누설전류는 가스 온도 150 ($^{\circ}C$) 이상에서 급격한 변화를 보이고 200($^{\circ}C$)에서 센서 자체의 전류치와 가스를 주입하였을 때의 전류치와는 상당한 격차를 두고 변화됨을 알 수 있었다. 그리고 공장연돌이나 자동차 배기관에서 방출되는 가스 중 HC, CO, NO, $CO_2$, $SO_2$, $N_2$ 등에 대한 센서 특성이 각각 달리 나타남을 알 수 있었다.

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Nondestructive Characterization of Degradation of EPDM Rubber for Automotive Radiator Hoses (자동차 냉각기 호스용 EPDM고무의 노화에 대한 비파괴 특성평가)

  • Kwak, Seung-Bum;Choi, Nak-Sam;Choi, Youn-Joung;Shin, Sei-Moon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.5
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    • pp.368-376
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    • 2005
  • Coolant rubber hoses for automobile radiators can be degraded and thus failed due to the influence of contacting stresses of air and coolant liquid under thermal and mechanical loadings. In this study, for EPDM(ethylene-propylene diene monomer) rubber conventionally used as a radiator hose material the aging behaviors of the skin part due to thermo-oxidative and electro-chemical stresses were nondestructively evaluated. Through the thermo-oxidative aging test, it was shown that the surface hardness IRHD(International Rubber Hardness Degrees) of the rubber increased with a considerable reduction of failure strain. On account of the penetration of coolant liquid into the skin part the weight of rubber specimens degraded by electro-chemical degradation(ECD) test increased, whereas their. failure strain and IRHD hardness decreased largely. The penetration of coolant liquid seemed to induce some changes in inner structure and micro hardness distribution of the rubbers. Consequently, EPDM rubbers degraded by thermo-oxidative aging and ECD could be characterized nondestructively by micro-hardness and chemical structure analysis methods.