• Title/Summary/Keyword: Side walls

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An Experimental Study on Compressive Loading Capacity of PCT System (PCT System의 압축내하력에 관한 실험적 연구)

  • Han, Man-Yup;Kim, Jae-Hong;Kang, Sang-Hun;Jin, Kyung-Seok;Jeon, Yong-Sik;Cho, Byung-Ku
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.41-44
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    • 2008
  • The PCT that supports the walls of long span temporary shoring facility is previously manufactured in the way of prestressing, and it which is composed of concrete is improved precast structure to satisfy enough stiffness. The components of PCT are manufactured as a fixed form, and they are close to the inner side of the wall of temporary shoring facility by fixed means in PCT. PCT system as support structure is that the ends of concrete filled segment members are united by the means of connection and also they have connection hole. In this study, PCT has enough bearing power for the long span temporary shoring facility, and also make the term of work reduce due to that the time of curing reduce through the method of precast.

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Numerical Analysis on Effects of Radius Ratio in a Concentric Annulus with a Rotating Inner Cylinder (내부회전실린더를 가진 동심환형관에서 반경비의 영향에 관한 수치해석적 연구)

  • Bae, Kang-Youl;Kim, Hyoung-Bum;Lee, Sang-Hyuk
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.327-330
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    • 2006
  • This paper represents the numerical analysis on effects of radius ratio in a concentric annulus with a rotating inner cylinder. The numerical model consisted of two cylinder which inner cylinder is rotating and outer cylinder is fix, and the axial direction is used the cyclic condition because of the length for axial direction is assumed infinite. The diameter of inner cylinder is assumed 86.8mm, the numerical parameters are angular velocity and radius ratio. Also, the whole walls of numerical model have no-slip and the working fluid is used water at $20^{\circ}C$. The numerical analysis is assumed the transient state to observe the flow variations by time and the 3-D cylindrical coordinate system. The calculation grid adopted a non-constant grid for dense arrangement near the wall side of cylinder, the standard $k-{\omega}$ high Reynolds number model to consider the effect of turbulence flow and wall, the fully implicit method for time term and the quick scheme for momentum equation. The numerical method is compared with the experimental results by Wereley and Lueptow, and the results are very good agreement. As the results, TVF isn't appeared when Re is small because of the initial flow instability is disappear by effect of the centrifugal force and viscosity. The vortex size is from 0.8 to 1.1 for TVF at various $\eta$, and the traveling distance for wavy vortex have the critical traveling distance for each case.

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Integrative Modeling of Wireless RF Links for Train-to-Wayside Communication in Railway Tunnel

  • Pu, Shi;Hao, Jian-Hong
    • Journal of Korea Society of Industrial Information Systems
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    • v.17 no.2
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    • pp.19-27
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    • 2012
  • In railway tunnel environment, the reliability of a high-data-rate and real-time train-to-wayside communication should be maintained especially when high-speed train moves along the track. In China and Europe, the communication frequency around 900 MHz is widely used for railway applications. At this carrier frequency band, both of the solutions based on continuously laid leaky coaxial cable (LCX) and discretely installed base-station antennas (BSAs), are applied in tunnel radio coverage. Many available works have concentrated on the radio-wave propagation in tunnels by different kinds of prediction models. Most of them solve this problem as natural propagation in a relatively large hollow waveguide, by neglecting the transmitting/receiving (Tx/Rx) components. However, within such confined areas like railway tunnels especially loaded with train, the complex communication environment becomes an important factor that would affect the quality of the signal transmission. This paper will apply a full-wave numerical method to this case, for considering the BSA or LCX, train antennas and their interacted environments, such as the locomotive body, overhead line for power supply, locomotive pantograph, steel rails, ballastless track, tunnel walls, etc.. Involving finite-difference time-domain (FDTD) method and uni-axial anisotropic perfectly matched layer (UPML) technique, the entire wireless RF downlinks of BSA and LCX to tunnel space to train antenna are precisely modeled (so-called integrative modeling technique, IMT). When exciting the BSA and LCX separately, the field distributions of some cross-sections in a rectangular tunnel are presented. It can be found that the influence of the locomotive body and other tunnel environments is very significant. The field coverage on the locomotive roof plane where the train antennas mounted, seems more homogenous when the side-laying position of the BSA or LCX is much higher. Also, much smoother field coverage solution is achieved by choosing LCX for its characteristic of more homogenous electromagnetic wave radiation.

0.65-7 GHz Inverse Conical Antenna for Reverberation Chamber (전자파 잔향실용 0.65-7 GHz 광대역 역원뿔 안테나 설계)

  • Jeong, Jin-Young;Chung, Jae-Young
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.3
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    • pp.10-14
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    • 2017
  • A reverberation chamber is widely used in mobile handset measurements due to its faster and simpler measurement process compared to traditional anechoic chambers. We propose an ultra-wideband inverse conical antenna design suitable as a reference antenna in a reverberation chamber. Traditionally, multiple discone antennas are needed to cover more than 10:1 operation bandwidth of a reverberation chamber. The proposed inverse conical antenna offers wideband impedance matching bandwidth by virtue of the linear impedance transition along its oblique side. The antenna is feasible to mount on the conductive walls which can be utilized as a ground to improve the matching bandwidth, antenna gain and radiation patterns. The antenna geometry is optimized using a 3D electromagnetic simulation tool and fabricated using a 3D printer. The measured results show that the antenna reflection coefficient lower than -10dB and radiation efficiency more than 70% at the frequency range of 0.65~7 GHz.

Design and Implementation of Frontal-View Algorithm for Smartphone Gyroscopes (스마트폰 자이로센서를 이용한 Frontal-View 변환 알고리즘 설계 및 구현)

  • Cho, Dae-Kyun;Park, Seok-Cheon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.6
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    • pp.199-206
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    • 2012
  • Attempt to use as a marker of natural objects directly in the real world, but there is a way to use the accelerometer of the smartphone, to convert the Frontal-View virtual, because it asks only the pitch of the camera, from the side there is a drawback that can not be converted to images. The proposed algorithm, to obtain the rotation matrix of axis 3 pitch, roll, yaw, we set the reference point of the yaw of the target image. Then, to compensate for the rotation matrix to determine Myon'inji any floor, wall, the ceiling of the target image. Finally, to obtain the homography matrix for obtaining the Frontal-View to account for the difference between the gyro sensor coordinate system and image coordinate system, so we can get the Frontal-View from the captured images through the projection transformation was designed. Was tested to convert Frontal-View the picture was taken in an environment smartphone environment surrounding floor, walls and ceiling in order to evaluate the conversion program Frontal-View has been implemented, in this paper, design and The conversion algorithm implementation, it was confirmed that to convert a regular basis Frontal-View footage taken from multiple angles.

Centrifugal Modelling on the Displacement Mode of Unpropped Diaphragm Wall with Surcharge (과재하중이 있는 Unpropped Diaphragm Wall의 변위양상에 관한 원심모델링)

  • 허열;이처근;안광국
    • Journal of the Korean Geotechnical Society
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    • v.20 no.8
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    • pp.135-145
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    • 2004
  • In this study, the behavior of unpropped diaphragm walls on decomposed granite soil was investigated through centrifugal and numerical modelling. Centrifuge model tests were performed by changing the interval distance of surcharge. Excavation was simulated during the centrifuge tests by operating a solenoid valve that allowed the zinc chloride solution to drain from the excavation. In these tests, ground deformation, wall displacement and bending moment induced by excavation were measured. FLAC program which can be able to apply far most geotechnical problems was used in the numerical analysis. In numerical simulation, Mohr-Coulomb model fur the ground model, an elastic model for diaphragm wall were used for two dimensional plane strain condition. From the results of model tests, failure surface was straight line type, the ground of retained side inside failure line had downward displacement to the direction of the wall, and finally the failure was made by the rotation of the wall. The angle of failure line was about 67 ∼ 74$^{\circ}$, greater than calculated value. The locations of the maximum ground settlement obtained from model tests and analysis results are in good agreements. The displacement of wall and the change of the embedment depth is likely to have linear relationship.

Analytical study on hydrodynamic motions and structural behaviors of hybrid floating structure

  • Jeong, Youn-Ju;Lee, Du-Ho;Park, Min-Su;You, Young-Jun
    • Ocean Systems Engineering
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    • v.3 no.1
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    • pp.35-53
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    • 2013
  • In this study, a hybrid floating structure with cylinder was introduced to reduce the hydrodynamic motions of the pontoon type. The hybrid floating structure is composed of cylinders and semi-opened side sections to penetrate the wave impact energy. In order to exactly investigate the hydrodynamic motions and structural behavior of the hybrid floating structure under the wave loadings, integrated analysis of hydrodynamic and structural behavior were carried out on the hybrid floating structure. Firstly, the hydrodynamic analyses were performed on the hybrid and pontoon models. Then, the wave-induced hydrodynamic pressures resulting from hydrodynamic analysis were directly mapped to the structural analysis model. And, finally, the structural analyses were carried out on the hybrid and pontoon models. As a result of this study, it was learned that the hybrid model of this study was showed to have more favorable hydrodynamic motions than the pontoon model. The surge motion was indicated even smaller motion at all over wave periods from 4.0 to 10.0 sec, and the heave and pitch motions indicated smaller motions beyond its wave period of 6.5 sec. However, the hybrid model was shown more unfavorable structural behavior than the pontoon model. High concentrated stress occurred at the bottom slab of the bow and stern part where the cylinder wall was connected to the bottom slab. Also, the hybrid model behaved with the elastic body motion due to weak stiffness of floating body and caused a large stress variation at the pure slab section between the cylinder walls. Hence, in order to overcome these problems, some alternatives which could be easily obtained from the simple modification of structural details were proposed.

Effect of Variation of Heated Bottom Wall Area on Natural Convection in Square Enclosure with Inner Circular Cylinder (원형 실린더가 존재하는 사각 밀폐계 바닥면의 고온 영역 변화가 자연대류 현상에 미치는 영향)

  • Jo, Hyun Woo;Yoon, Hyun Sik;Lee, Hyo Jeong;Kim, Minsung;Ha, Man Yeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.11
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    • pp.991-998
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    • 2013
  • A numerical study is carried out for natural convection in an enclosure with an inner hot cylinder at the center. The top wall is cold, the bottom and both side walls of the enclosure are adiabatic, and the cylinder is heated. The bottom wall is heated locally at the middle. The ratio (w) is defined by as the width of the bottom wall to that of the heated local area. The immersed boundary method (IBM) is used to model an inner circular cylinder based on the finite volume method (FVM). This study investigates the effect of w on natural convection in an enclosure with an inner heated cylinder for Rayleigh numbers of $10^6$. At $6Ra=10^6$, thermal and flow fields show time-dependent characteristics after their full development.

Palaeomagnetism of Tertiary Basins in Southern Korea: 2. Basaltic Rocks in the Central Part of Pohang Basin (남한 제3기 분지지역에 대한 고자기 연구 : 2. 포항분지 중부의 현무암질암)

  • Son, Moon;Kim, In-Soo
    • Economic and Environmental Geology
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    • v.29 no.3
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    • pp.369-380
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    • 1996
  • In order to determine the emplacement time and stratigraphic position of basaltic rocks in the central part of Pohang basin, palaeomagnetic investigations were conducted on 111 samples collected from 6 sites. Formation mean built from site-mean ChRM directions is $d=340.7^{\circ}$, $i=52.2^{\circ}$ (${\alpha}_{95}=6.0^{\circ}$, k=91) in the geographic coordinates. If "tilt" correction is applied regarding the plane perpendicular to the side walls of columnar joint as palaeohorizon, the formation mean becomes $d=328.7^{\circ}$, $i=43.8^{\circ}$ (${\alpha}_{95}=17.1^{\circ}$, k=13). It is to be noticed that the formation mean is deflected significantly (about $20{\sim}30^{\circ}$) counterclockwise from the Tertiary reference geomagnetic field of Eurasia, independent of "tilt" correction. This situation is very different from that of clockwise rotation of ChRM directions which has been ubiquitously observed in other Tertiary basins of south Korea, and indicates sinistral regional simple-shearing during the emplacement times of the basaltic rocks. Considering previous palaeomagnetic and AMS (anisotropy of magnetic susceptibility) data from other Tertiary regions of south Korea, the time of this sinistral shearing should be 15 Ma or directly thereafter, and this time point represents inversion from extensional to compressional tectonic regime. Magnetic foliation data obtained in this study indicate WNW-ESN compression during or directly after emplacement of the basaltic rocks, while it has known from regional tectonic study that the time of the WNW-ESN compression is about 15 Ma, when SW Honshu was rotated and the Korean strait was narrowed.

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A Study on the Distribution of the Peak Wind Pressure for Rooftop Signboards (건물 옥상에 설치되는 옥상 간판의 피크풍압 분포에 대한 연구)

  • Nam, Byung-Hee;You, Jang-Youl;Lee, Nam-Hun;You, Ki-Pyo
    • Journal of Korean Association for Spatial Structures
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    • v.18 no.2
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    • pp.79-86
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    • 2018
  • Unlike other types of outdoor advertisements, rooftop signboards are installed on the roofs of buildings, rather than on their outer walls. This means that the area of a rooftop signboard is commonly larger than that of a general outdoor signboard. Moreover, as such signboards are greatly influenced by the wind, they can suffer a lot of damage from typhoons and strong winds every year. However, there is no wind load specification for rooftop signboards. In this study, wind pressure experiments were conducted to investigate the peak wind pressure on each side of rooftop signboards installed on the roofs of 5-15 story buildings in a city center. The minimum peak wind pressure coefficient was -3.0 at the bottom edges of the front and back of the rooftop signboards and -2.0 along the entire length of the sides. As the height of the rooftop signboard increased with the increasing height of the buildings, the peak value was found to be larger than the absolute peak value for the minimum peak wind pressure coefficient. The maximum and minimum peak wind pressure distributions of the rooftop outdoor signboards were influenced by the position of the signboard and the wind angle.