• Tunnel and Underground Space
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• v.7 no.4
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• pp.267-273
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• 1997

Rock fragmentation with plasma blasting technique has advantageous properties in contrast to the conventional blasting method in controlling of flying rocks and ground vibrations, when residents are complaining or surrounding structures stay in protection from blasting operations. The experiences show in urban construction works that the plasma blasting is the most possible method to prevent damages and minimize adverse environmnetal impacts. The fragmentation energy level is evaluated by numerical simulation using PFC-2D for various drill hole pattern and tested accordingly to get the feasibility. The energy output of plasma blasting system has been improved to a level of 1 MJ, which can break a 2~3 ㎥ granite boulder or 1.5 m height bench face. Measurements are carried out to get the ground vibration level and propagation equation, so that the control of the blasting operations can be performed more precisely and safely.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1143-1145
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• 2003

Some of satellites such as IKONOS don't provide the orbital elements so that we can’ utilize the physical sensor model. Therefore, Rational Function Model(RFM) which is one of mathematical models could be a feasible solution. In order to improve 3D geopositioning accuracy of IKONOS stereo imagery, Rational Polynomial Coefficients(RPCs) of the RFM need to be updated with Ground Control Points(GCPs). In this paper, a method to improve RPCs of RFM using GCPs and 3D cube is proposed. Firstly, the image coordinates of GCPs are observed. And then, using offset values and scale values of RPC provided, the image coordinates and ground coordinates of 3D cube are initially determined and updated RPCs are computed by the iterative least square method. The proposed method was implemented and analyzed in several cases: different numbers of 3D cube layers and GCPs. The experimental results showed that the proposed method improved the accuracy of RPCs in great amount.

• Journal of electromagnetic engineering and science
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• v.18 no.4
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• pp.261-266
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• 2018

This paper reports on the proposed design of a low profile broadband array antenna for home repeater applications. The proposed antenna consists of $1{\times}4$ patch elements and two ground planes, one of which is slitted. By using the gap feeding method, the impedance matching of the antenna is improved by a multi-resonance phenomenon. The proposed antenna provides a wide -10 dB reflection coefficient bandwidth simultaneously covering the Global System for Mobile communications (GSM-1800), Personal Communications Service (PCS), and the Universal Mobile Telecommunication System (UMTS) bands (1.67-2.32 GHz). In order to reduce the mutual coupling between adjacent patch elements, slits are embedded in the ground plane. An isolation level of -20 dB is realized over the entire operating frequency band.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.843-848
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• 2007

Quadruped robot is very useful mechanism for a various area. Recently, home entertainment and military robots adapted quadruped platform and useful function have been introduced. Our goal is the development of quadruped robot locomotion for any type of ground included to sloping one and irregular terrain. This paper, as a first step, deals with design and construction of quadruped robot walking on the flat ground. The most important factor of quadruped robot is stability of locomotion. At first, we introduce the developed quadruped robot based on dynamic simulation and experimental study of general gait algorithm. Finally, propose unique locomotion proper to our mechanism. Future work of this study is the performance test and analysis on the ground of various conditions and proposes the improved mechanism and gait algorithm.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.300-310
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• 2008

A series of numerical simulations on the several types of breakwaters on the foundation systems utilizing buoyancy were carried out in plane-strain conditions using the modified Cam-Clay model and the Biot's consolidation theory. Improved foundation system by the replacement of original ground with light weighted material, expandable poly-styrene (called below EPS) and several foundation systems with buoyant cells were used. From the results of numerical simulations we found that the foundation systems utilizing buoyancy are efficient to reduce the maximum consolidation settlements without reducing lateral safety.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.256-257
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• 2014

Concrete made with ground granulated blast-furnace slag(GGBS) has many advantage, including improved durability, workability and economic benefits. GGBS concrete is that its strength development is considerably slower under standard 20℃ curing conditions than that of portland cement concrete, although the ultimate strength is higher for same water-binder ratio. GGBS is not therefore used in application where high early age strength is required. However, hydration of GGBS is much more sensitive to temperatures, the strength development of GGBS concrete is significantly enhanced.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.4
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• pp.163-170
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• 2005

This paper deals with an improved fault location algorithm with compensation ground capacitance through distributed parameter for a long parallel T/L. For the purpose of fault locating algorithm non-influenced by source impedance and fault resistance, the loop method was used in the system modeling analysis. This algorithm uses a positive and negative sequence of the fault current for high accuracy of fault locating calculation. Power system model of 160km and 300km long parallel T/L was simulated using EMTP software. To evaluate of the proposed algorithm, we used the several different cases 64 sampled data per cycle. The test results show that the proposed algorithm was minimized the error factor and speed of fault location estimation.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.872-879
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• 2010

High rock-fill embankment is relatively flexible, which makes crest of embankment subject to excessive amplification in displacement due to earthquake loading. To overcome problems related with site response in high embankment, it is essential to evaluate shear-wave velocity profile of the embankment with improved accuracy and reliability. In this aspect, an experimental research was performed to answer how to perform surface-wave tests and to analyze measurements at an embankment site with a sloping ground surface. Unlike flat ground surface, sloping ground may hamper and slow down propagation of surface waves due to multiple reflections and refractions in embankment. To figure out this reasoning for the effect of multiple reflections and refractions due to sloping surface, surface wave tests were performed at a reservoir embankment of Chung-Song in North KyeongSang Province. Parameters involved in surface wave tests at non-flat surface, including source directionality, geometry-related constraint and frequency components in source function, were investigated using field measurements.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.45-46
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• 2016

As coal fly ash emissions have increased due to additional constructions of domestic heat power plants, the amount of embedded reject ash (Rj henceforth) is increasing as well. Most Rj is embedded, so if it is used as an alternative admixture instead of cement, embedded quantities will decrease, leading to economic and environmentally positive effects. Therefore this study conducted an experiment to contemplate the usability of Rj ground in the Los Angeles abraser, and what effects ground Rj has on the engineering properties of high compressive strength mortar. The result was that as the number of grinding turns increased, liquidity, air quantity and intensity were improved, proving Rj a possible alternative admixture to cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.96-97
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• 2016

As coal fly ash emissions have increased due to additional constructions of domestic heat power plants, the amount of embedded reject ash (Rj henceforth) is increasing as well. Most Rj is embedded, so if it is used as an alternative admixture instead of cement, embedded quantities will decrease, leading to economic and environmentally positive effects. Therefore this study conducted an experiment to contemplate the usability of Rj ground in the Los Angeles abraser, and what effects ground Rj has on the engineering properties of poor-mix mortar. The result was that as the number of grinding turns increased, liquidity, air quantity and intensity were improved, proving Rj a possible alternative admixture to cement.