• Title/Summary/Keyword: Cut-off wall

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A Study on the Lateral Earthpressure at Behind Structure for Backfill by Sand (구조물 배면에 사질토 되메움시 유발되는 수평토압에 관한연구)

  • Lee, Sang-Duk;Kang, Se-Gu
    • Journal of the Korean Geosynthetics Society
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    • v.10 no.4
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    • pp.11-18
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    • 2011
  • In this study, the reinforcing effect of geogrids in the narrow backfill by sand was experimentally studied. In the model tests, the size of space and the slope of the cut off slope were varied out. The resultant and the distribution of lateral earth pressure were measured. Width of backfill space varied 10 cm, 20 cm, 30 cm at the lower wall level and angle of the cut off slope varied $90^{\circ}$, $75^{\circ}$, $60^{\circ}$. Geogrids were installed in the backfill. Measured results showed that the distribution of the lateral earth pressure due to the narrow backfill developed in a arching shape. And the earth pressure was reduced due to the reinforcement of the backfill by geogrid. geogrid helps reduction of lateral earth pressure.

The Fluid Loss and Sealing Mechanisms in Slurry Trench Condition (I) : A Large Scale Test and Design Procedure (Slurry wall 공법에서 안정액의 역할 (I) : 대형모형실험과 설계절차)

  • Kim, Hak-Moon
    • Journal of the Korean Geotechnical Society
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    • v.18 no.4
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    • pp.239-248
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    • 2002
  • Bentonite slurries in a slurry wall construction must fulfill a stabilizing function by forming impermeable membrane (surface cake and penetrated cake) on the excavated soil faces. Thus problems are occurring in practice for the construction of diaphram walls and cut-off walls with a low permeability for wastes disposal areas in some deep excavations or different grounds. In this paper, the fundamental mechanics of fluid loss and filter cake formation in various soil beds are investigated using large scale laboratory apparatus. The sealing efficiency of filter cake from the large scale tests and the significance of fluid loss in a slurry trench are utilized for practical situation as a recommended design procedure.

PIV Measurement of Flow Inside of HVAC Blower Unit (자동차 HVAC용 Blower Unit 내부 유동장의 PIV 계측)

  • Ji, Ho-Seong;Kim, Bo-Ram;Lee, Sang-Joon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.5
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    • pp.165-173
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    • 2007
  • Flow characteristics inside a blower unit of an automotive HVAC module were investigated experimentally using a high-resolution PIV technique. The PIV system consists of a 2-head Nd:YAG laser, a high-resolution CCD camera, optics and a synchronizer. The prototype siroco-fan with forward-curved blades was operated under the same condition of real car. The scroll casing was made transparently for capturing clear flow images. The time-averaged velocity fields were measured in three cross sections. Flow is accelerated with going toward the outer wall of scroll due to centrifugal force and large pressure gradient formed in the region between the fan and the outer casing wall. The presence of the cut-off region and diffusing duct of fan outlet influences largely the flow structure inside the blower unit.

The Change of Hagdong Shingle Beach and its Causes -By Monitoring the Change of Beach Profiles- (거제도 학동 자갈해빈의 변화와 그 원인에 관한 연구 -해빈 단면의 모니터링을 통해-)

  • Son, Ill;Park, Kyeong
    • Journal of the Korean association of regional geographers
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    • v.10 no.1
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    • pp.177-191
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    • 2004
  • Monitoring has been done for the shingle beach in Hagdong Beach in Geojesi, City during the seven month period. The shingle beach has been found to go through the cyclic change according to the tidal schedule. The typhoon Rusa in year 2002 affected whole beach face. Sea wall, constructed to protect the village along the beach, aggravates the situation, since it cut off the supply of shingle from the marine terrace, upon which village was built. Concrete walls along the streams also diminish the supply of shingles from the mountains. To protect the shingle beach and encourage the sustainable eco-tourism long-term monitoring on sediment budget is necessary.

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Containing Heavy Metal Contaminants Using Soil-Cement Column Barrier (심층혼합기둥체 차수벽을 이용한 중금속 오염물질의 이동 제어)

  • 정문경;천찬란;이주형;김강석
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.821-826
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    • 2003
  • Laboratory experiments were peformed to understand physical properties of soil-cement column under the influence of acidic flow including metal contaminants and its retaining capacity against metal migration. The contaminant used in this study was nitric acid with Cu and Cd. The Permeability of soil-cement column decreased when pH of the column began to drop below 12. Decreases in pH led to significant reduction of compressive strength of clayey soil-cement specimen, while relatively marginal reduction for sandy soil-cement specimen. The metal contaminants did not leachate from soil-cement column until pH of soil-cement dropped below 7∼8 for Cu and 9∼10 for Cd. Metal contaminants were precipitated and trapped inside the soil-cement column at pHs higher than those mentioned as verified with metal analysis and visual inspection. This indicated that soil-cement column not only performs well as a cut-off wall, but also helps alleviating the level of contamination of the surrounding environment.

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Study on Experimental Fabrication of a New MOS Transistor for High Speed Device (새로운 고주파용 MOS 트랜지스터의 시작에 관한 연구)

  • 성영권;민남기;성만영
    • 전기의세계
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    • v.27 no.4
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    • pp.45-51
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    • 1978
  • A new method of realizing the field effect transistor with a sub-.mu. channel width is described. The sub-.mu. channel width is made possible by etching grooves into n$^{+}$ pn$^{[-10]}$ n$^{[-10]}$ structure and using p region at the wall for the channel region of the Metal-Oxide-Semiconductor transistor (MOST), or by diffusing two different types of impurities through the same diffusion mask and using p region at the surface for the channel region of MOST. When the drain voltage is increased at the pn$^{[-10]}$ drainjunction the depletion layer extends into the n$^{[-10]}$ region instead of into p region; this is also the secret of success to realize the sub-.mu. channel width. As the result of the experimental fabrication, a microwave MOST was obtained. The cut-off frequency was calculated to be 15.4 GHz by Linvill's power equation using the measured capacitances and transconductance.

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A Study for Tubing Pipe Flaw Sizing by Using Guided Ultrasonic Wave (유도초음파기법을 이용한 튜빙 결함측정에 관한 연구)

  • Joo, Kyung Mun;Cheon, Keun Young;Lee, Jeong Seok
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.5 no.1
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    • pp.20-24
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    • 2009
  • There is extensive tubing pipe in the nuclear power plant under high temperature and pressure. Erosion and corrosion defects are expected on this tubing pipe due to environmental and mechanical factors. In this study, Guided Ultrasonic Wave technique was applied to detect defects. The technique explores the advantages of the Guided Ultrasonic Wave method that inspects along the wall of the pipe and can travel long distances, providing rapid collection of data. This paper presents a case study of the Guided Ultrasonic Wave testing of 3/8" tubing pipe. This study offers to understand detected signals through correlation between amplitude and depth of defects.

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Fabrication and its characteristics of $WN_x$ self-align gate GaAs LDD MESFET ($WN_x$ Self-Align Gate GaAs LDD MESFET의 제작 및 특성)

  • 문재경;김해천;곽명현;강성원;임종원;이재진
    • Journal of the Korean Vacuum Society
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    • v.8 no.4B
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    • pp.536-540
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    • 1999
  • We have developed a refractory WNx self-aligned gate GaAs metal-semiconductor field-effect transistor(MESFET) using $SiO_2$ side-wall process. The MESFET hasa fully ion-implanted, planar, symmetric self-alignment structure, and it is quite suitable for integration. The uniform trans-conductance of 354nS/mm up to Vgs=+0.6V and the saturation current of 171mA/mm were obtained. As high as 43GHz of cut-off frequency hs been realized without any de-embedding of parasitic effects. The refractory WNx self-aligned gate GaAs MESFET technology is one of the most promising candidates for realizing linear power amplifier ICs and multifunction monolithic ICs for use in the digital mobile communication systems such as hand-held phone(HHP), personal communication system (PCS) and wireless local loop(WLL).

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A Study on Aerodynamic and Noise Characteristics of a Sirocco Fan for Residential Ventilation (주거환기용 시로코홴의 공력 및 소음 특성 연구)

  • Kim, Jin-Hyuk;Song, Woo-Seog;Lee, Seung-Bae;Kim, Kwang-Yong
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.2
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    • pp.18-23
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    • 2010
  • This paper presents a procedure for the aerodynamic and aeroacoustic characteristics of a sirocco fan. For the aerodynamic and aeroacoustic analyses of the sirocco fan, three-dimensional steady and unsteady Reynolds-averaged Navier-Stokes equations are solved with a shear stress transport turbulence model for turbulence closure. The flow analyses were performed on a hexahedral grid using a finite-volume solver. The validation of the numerical results is performed by comparing with experimental data for the pressure, efficiency and power. The internal flow analyses of the sirocco fan are performed to understand the unstable flow phenomenon on the casing for the wall pressure and internal flow characteristics at each position. It was found that fluctuation of pressure and locally concentrated noise source are observed near the cut-off and expansion regions of the casing.

Characteristics of the Cell Wall Lytic Enzyme of Anabaena cylindrica from Penicillium oxalicum(HCLF-34) (Penicillium oxalicum(HCLF-34)으로부터 분비되는 Anabaena cylindrica 세포벽 분해효소의 특성)

  • 현성희;최영길
    • Korean Journal of Microbiology
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    • v.35 no.3
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    • pp.231-236
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    • 1999
  • The fuugus(Penicil1ium oralicum; HCLF-34) secreted the cyanobacteria lytic enzyme which had a molecular weight of about 22 kDa, a optimum temperature of $20^{\circ}C$, a optimum pH of 3.5, and a temperature-stable up to $50^{\circ}C$. The chemical ions such as sodium, potassium, barium, magnesium. and mangan ions appeared positive activity. but calcium, iron, copper ions, EDTA, and PMSF displayed negative activity: this results were the same as the characterilics of other cell wall lytic enzymes. This extracellular enzyme showed lytic aclivily against SDS-insoluble peptidoglycan of Anabaenrr cylinrlrica. The cell wall lylic enzyme of Penicilliurn oxalicum(HCLF-34) seemed to be glycosidase-like enzyme in the fact that ihe concentration of rcducing sugar was increased when the peptidoglycan of Anabaena qlinrlricn md Micrococcus luteus reacted with this enzyme

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