• Explosives and Blasting
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• v.37 no.3
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• pp.25-33
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• 2019

Controlling the blast-induced damage zone(BDZ) in mining excavation is a significant issue for the safety of employees and the maintenance of facilities. Numerous studies have been conducted to accurately predict the BDZ in underground mining. This study employed the dynamic fracture process analysis (DFPA) to estimate the BDZ from a single hole blasting. The estimated BDZ were compared with the results obtained by Swedish empirical equation. The DFPA was also used to investigate the control mechanism of BDZ and fracture plane formation around perimeter holes for underground mining blasting.

• Journal of Korea Multimedia Society
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• v.2 no.2
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• pp.195-199
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• 1999

While object-oriented models are effective in achieving sharing and code reusability, they unfortunately lack a mechanism for giving scope to objects. We propose an object-oriented model in which each object can be given a scope, i.e., an object becomes available only when it is needed. Thus, the set of currently available objects is dynamically changing and only the needed set of objects is maintained in this model. We illustrate the usefulness of this model through some examples.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.61-64
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• 2001

본 논문에서는 실시간 MMDBMS 를 위한 효율적인 색인 기법을 제안한다. 기존의 주기억장치 트리 기반 색인 구조는 범위 검색을 효과적으로 지원할 수 있지만 한 노드에 대한 접근시간과 평균 접근시간의 차이가 클 수 있기 때문에 실시간 특성을 보장하지 못하는 단점이 있다. 또한 해시 기반 색인 구조는 간단한 검색에서 접근 시간이 매우 빠르고 일정하지만 범위 검색을 지원하지 못하는 단점이 있다. 이러한 두 색인 구조의 단점을 해결하기 위해 본 논문에서는 동적 확장이 가능하며 검색 시간이 빠르고 실시간 특성을 지원할 수 있는 ECBH(Extendible Chained Bucket Hashing)와 범위 검색에 더욱 효과적인 $T^{\ast}$-트리를 상호보완적으로 결합하여 Hyper-TH(Hyper Tree-Hash)라는 실시간 MMDBMS 에 적합한 새로운 색인 기법을 제안하고 구현한다. 그리고 성능 평가를 통해 제안하는 색인 기법의 우수성을 증명한다.

• Journal of the Korean Geosynthetics Society
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• v.11 no.1
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• pp.35-45
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• 2012

Dynamic characteristics of decomposed granite soil mixed with stone sludge and bentonite were investigated to figure out adequate applications of stone sludge, A total of 16 specimens with different stone sludge contents of 0%, 5%, 10%, 15% and bentonite with 0%, 5%, 10%, 15% were prepared. Resonant column tests were carried out on each specimen at different confining pressure. The results showed that the optimum mixing ratio which can satisfy the maximum shear modulus and the minimum damping ratio of the decomposed granite soils ranges from 5% to 10% respectively.

• Geotechnical Engineering
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• v.10 no.2
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• pp.85-96
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• 1994

Resonant column test huts been widely used as a primary laboratory testing technique in investigating dynamic soil properties expressed in therms of shear and Young's moduli and material damping. In thin Paper, dynamic Properties of typical Korean subgrade boils are investigated at shearing strains between 10-4% and 10-1% using Stokoe-type resonant column teat. The elastic threshold strains(yte) above which shear modulus and damping ratio are affected by strain amplitude, are defined at strain amplitude of about 10-3%. Below yte", small-strain shear modulus (Gmn) increases with confining pressure (Qc) as proportional to (Qe)0.61, and small-strain damping ratio(Dmin) ranges between 1% and 5.7%. Above yte, normalized shear modulus reduction curve(G/Gma. versus log strain) can be quite well expressed with Ramberg Osgood stress -strain equation and match well the curve suggested for sand by Seed and Idriss.riss.

• Journal of Korea Water Resources Association
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• v.43 no.3
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• pp.283-294
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• 2010

The objective of this study is to develop an accurate and stable dynamic water quality model which is capable of reflecting various flows and irregular cross sections and handling numerical oscillations under the low flow conditions. In order to solve the oscillation problem under the low flow conditions, diffusive wave method was applied to the low flow condition in developing a hydraulic model, DyHYD. DyQUAL is also developed as a water quality model to calculate up to 12 water quality variables including autochthonous BOD, water temperature, DO, TN and TP. The developed model is applied to both hypothetical river channels and actual Nakdong river watershed. Additionally, the applicability and reliability of the models are verified by comparing simulation results with observed values. Nash-Sutcliffe coefficients are estimated by comparison between simulation results and observed values. In the calibration and verification process, the coefficients varies from 0.391 to 0.591 and 0.704 to 0.902 for discharge, BOD, TN and TP, respectively.

• Journal of the Korean Geotechnical Society
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• v.35 no.2
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• pp.5-17
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• 2019

Dynamic centrifuge model test was conducted to evaluate the dynamic stability of the pile-supported slab track method during dynamic railway loading and earthquake loading. The centrifuge tests were carried out for various condition of embankment height and soft ground depth. Based on test results, we found that the bending moment was increased with embankment height and decreased with soft ground depth. In addition, it was confirmed that the pile-supported slab track system could have dynamic stability for short-period seismic loading. However, in case of long-period seismic loading, such as Hachinohe earthquake, the observed maximum bending moment reached to pile cracking moment at the return period of 2,400 year earthquake. The criterion of ratio between embankment height and soft ground depth was suggested for dynamic stability of pile-supported slab track system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.892-897
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• 2017

As the weapon system SW development and management manual of the DAPA, which is the regulation for the overall weapon system SW development, is revised, the level and scope of SW reliability test are upgraded to improve the reliability and quality of SW. It is a big burden for SW developers. In particular, the dynamic test requires a schedule and manpower required to implement the weapon system SW, and should be performed every time the source code changes, not just one time. In this paper, we propose a regression test automation program(VectorCast Environment Manager) that performs a dynamic test using VectorCast, a dynamic test tool, and then performs a regression test automatically by minimizing human intervention in the regression test of dynamic test due to the change of the source code.

• Journal of Korean Society of Steel Construction
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• v.20 no.4
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• pp.455-467
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• 2008

The dynamic vehicle running tests were performed to analyze dynamic behavioral characteristics such as displacement, strain history loop and vibration acceleration in arch bridges. Also, the validity of the modeling was verified by comparing the results of the tests and those of the structural analysis modeling. With the resonance revision of verified modeling, when the ratio of excited frequencies to natural frequencies exceeds ${1{\pm}0.04}$, the stability of the bridge is obtained. Also, in the event of resonance by speed parameter, the second mode shape is dominant to the dynamic behaviors of arch bridges. It is found that manipulating the parameters involving arch ribs can increase the second mode natural frequency. It makes critical velocity greater than operational velocities to guarantee the stability of arch bridges.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.2
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• pp.100-109
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• 2022

Large-scale urban concentration of population and vehicles due to economic growth in Korea has been causing serious urban transport problems. Although the collection of congestion pricing has been evaluated as the most effective transportation policy to alleviate traffic demand, its effectiveness is very limited as it was just executed around congested points or along main arterial roads. This study derived dynamic congestion zones with the average travel speed of 206 traffic analysis zones in Busan Metropolitan City to propose a dynamic congestion pricing collection system by employing Space-Time Cube Analysis and Emerging Hot Spot Analysis. As a result, dynamic hot spots were formed from 7h to 24h and particularly, traffic congestion was severely deteriorated from 18h to 20h around Seomyeon and Gwangbok-dong. Therefore, it is expected that the effect of dynamic congestion pricing will be maximized in managing traffic demand in the city center.