• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.320-330
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• 2012

In this paper, we investigate the power integrity of grid structures for power and ground distribution on printed circuit board (PCB). We propose the 2D transmission line method (TLM)-based model for efficient frequency-dependent impedance characterization and PCB-package-integrated circuit (IC) co-simulation. The model includes an equivalent circuit model of fringing capacitance and probing ports. The accuracy of the proposed grid model is verified with test structure measurements and 3D electromagnetic (EM) simulations. If the grid structures replace the plane structures in PCBs, they should provide effective shielding of the electromagnetic interference in mobile systems. An analytical model to predict the shielding effectiveness (SE) of the grid structures is proposed and verified with EM simulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1135-1142
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• 2007

STSAT-2 has an on-board satellite retroreflector array for precise orbit determination. Satellite retroreflector array reflects photon emitted from laser and uses to determine precisely the distance from ground station to satellite by the round-trip travel time of photon. The retroreflector array of protoflight model has been developed and verified through environmental tests. This paper describes the protoflight model of retroreflector array and reports environmental test results. The environmental tests of protoflight model retroreflector array were performed successfully without damage of corner cube prism occurred in engineering model development.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.101-114
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• 2008

Pressurized grouting is a common technique in geotechnical engineering applications to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressurized grouting has been applied to a soil-nailing system which is widely used to improve slope stability. Because interaction between pressurized grouting paste and adjacent ground mass is complicated and difficult to analyze, the soil-nailing design has been empirically performed in most geotechnical applications. The purpose of this study is to analyze the ground behavior induced by pressurized grouting paste with the aid of laboratory model tests. The laboratory tests are carried out for four kinds of granitic residual soils. When injecting pressure is applied to grout, the pressure measured in the adjacent ground initially increases for a while, which behaves in the way of the membrane model. With the lapse of time, the pressure in the adjacent ground decreases down to a value of residual stress because a portion of water in the grouting paste seeps into the adjacent ground. The seepage can be indicated by the fact that the ratio of water/cement in the grouting paste has decreased from a initial value of 50% to around 30% during the test. The reduction of the W/C ratio should cause to harden the grouting paste and increase the stiffness of it, which restricts the rebound of out-moved ground into the original position, and thus increase the in-situ stress by approximately 20% of the injecting pressures. The measured radial deformation of the ground under pressure is in good agreement with the expansion of a cylindrical cavity estimated by the cavity expansion theory. In-situ test revealed that the pullout resistance of a soil nailing with pressurized grouting is about 36% larger than that with regular grouting, caused by grout radius increase, residual stress effect, and/or roughness increase.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.979-990
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• 2010

Although a centrifuge model test is performed with scaled models, it has a lot of advantages compared with usual scale model tests, for the reproduction of stress levels equal to a full scale test is possible. At the beginning of the Daewoo Institute of Construction Technology, a servo-motor-driven single axis actuator was introduced and has been in use with a geo-centrifuge. However, for variety of experiments and construction stage simulation, various apparatuses have been developed, such as a vacuum generator, a lateral actuator for tidal power simulation, a gravel hopper and a sand drainer for filled-up ground, and a water level controller. The apparatuses have been manufactured with enough strength and durability to be operated under specific g levels. This paper presents the properties of the apparatuses and the results of the tests performed with those.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.481-489
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• 2006

Two dimensional diffusion model test was conducted to investigate the sedimentation properties and consolidation process of reclaimed ground using dredging coarse soil which is composed of passing amount 20 percentage and 45 percentage of #200 sieve size respectively. The passing amount of #200 sieve size affected on sedimentation properties. The coarse soil which is passing amount of 20 percent showed that the sedimentation structure was layered type and passing amount of 45 percentage was wall-partition type according diffusion distance. Furthermore, the water content of surface and section, and distribution of fine soil were changed according to diffusion distance. and the change amount of pore water pressure and strength property when soil is diffused, segregated and accumulated can be applied efficiently in design of dredging and reclamation.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.12-19
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• 2011

Drawing on its extensive experience with natural disasters, Japan has been dispatching Japan Disaster Relief (JDR) team to disaster-stricken countries to provide specialist assistance in rescue and medical operations. The JDR team has assisted in the wake of disasters including the 2004 Indian Ocean Earthquake and the 2008 Sichuan Earthquake in China. Information about the affected area is essential for a rapid disaster response. However, it can be difficult to gather information on damages in the immediate post-disaster period. To help overcome this problem, we have built on an Earthquake Damage Estimation System. This system makes it possible to produce distributions of the earthquake's seismic intensity and structural damage based on pre-calculated data such as landform and site amplification factors for Peak Ground Velocity, which are estimated from a Digital Elevation Model, as well as population distribution. The estimation result can be shared with the JDR team and with other international organizations through communications satellite or the Internet, enabling more effective rapid relief operations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1219-1227
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• 1994

For Determination of the ultimate uplift capacity, the failure mechanism of the foundation by uplift should be correctly known. However, studies on the variation of the failure mechanism with the embedment ratio of anchor plate among those factors governing the uplift resistance are scarce. In this study. in an attempt to observe more clearly the variation of the failure mechanism with embedment ratio and to check applicability of existing formulae for the ultimate uplift capacity. a model test was performed with ground made of carbon rods, simulating a plane strain conditions. As a result, failure characteristics of shallow and deep anchor conditions were clearly classified. It was found that the analysis of a shallow anchor should be made prior to determination of the ultimate uplift capacity of a deep anchor.

• Geomechanics and Engineering
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• v.8 no.5
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• pp.707-726
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• 2015

This paper investigates the time dependent behaviour of Haarajoki test embankment on soft structured clay deposit. Half of the embankment is constructed on an area improved with prefabricated vertical drains, while the other half is constructed on the natural deposit without any ground improvement. To analyse the PVD-improved subsoil, axisymmetric vertical drains were converted into equivalent plane strain conditions using three different approaches. The construction and consolidation of the embankment are analysed with the finite element method using a recently developed anisotropic model for time-dependent behaviour of soft clays. The constitutive model, namely ACM-S accounts for combined effects of plastic anisotropy, interparticle bonding and degradation of bonds and creep. For comparison, the problem is also analysed with isotropic Soft Soil Creep and Modified Cam Clay models. The results of the numerical analyses are compared with the field measurements. The results show that neglecting effects of anisotropy, destructuration and creep may lead to inaccurate predictions of soft clay response. Additionally, the numerical results show that the matching methods accurately predict the consolidation behaviour of the embankment on PVD improved soft clays and provide a useful tool for engineering practice.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.4
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• pp.11-20
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• 1997

The aseismic capacity of a traditional three-bay-straw-roof wooden house for rock site condition is quantitatively estimated. One 1/4 scale model was tested for the Nahanni Earthquake with peak ground accelerations from 0.1g to 0.6g. The natural frequency of the wooden house in elastic range is 1.66 Hz and 2.15 Hz in longitudinal and transversal direction, respectively. Damping ratio of the house in elastic range is 7%. The horizontal acceleration response of the house is significantly reduced compared with the input motion due to the nonlinear inelastic characteristics of the Sagae-machum joint of the frame. The traditional wooden house has high aseismic capacity in the rock site condition where high frequency contents of motion are predominant.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.598-602
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• 2017

Korea Aerospace Research Institute has been developing 3-stage launcher KSLV-II, which can inject 1.5-ton satellite into sun synchronous orbit (SSO). For development process, Test Launch Vehicle(TLV) adopting the $2^{nd}$ and $3^{rd}$ stage of KSLV-II will be scheduled to launch in 2018. The propulsion system of TLV is composed of $2^{nd}$ stage engine system (ground type) and propellant supply system including LOX, Kerosene tanks. Until now, system integration of engineering model of TLV and delivery of qualification model have been done. In this paper, the product assurance activities for propulsion system KSLV-II will be illustrated.