• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.109-120
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• 2006

SPT-Uphole test is a seismic field test using receivers on ground surface and a SPT (Standard penetration test) source in depth. Even though this method is simple and economic, it makes hesitate to apply in real field that it is difficult to obtain reliable travel time information of shear wave because of the characteristics of SPT impact source. To overcome this shortcoming, in this paper, modified SPT-Uphole method using two component surface geophones was suggested. Numerical analysis was performed using finite element method for understanding the characteristics of surface motion induced by in-depth vertical source, and comparison study of the various methods which determine the travel time information in SPT-Uphole method was performed. In result, it is thought that the most reasonable method is using the first local maximum point of the root mean square value signals of vertical and horizontal component in time domain. Finally, modified SPT-Uphole method using two component surface geophones was performed at the site, and the applicability in field was verified by comparing wave velocity profiles determined by the SPT-Uphole method with the profiles determined by SASW method and SPT-N values.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.1-10
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• 2008

Shear wave velocity($V_S$), which can be obtained using various seismic tests, has been emphasized as representative geotechnical dynamic characteristic mainly for seismic design and seismic performance evaluation in the engineering field. For the application of conventional geotechnical site investigation techniques to geotechnical earthquake engineering, standard penetration tests(SPT) and piezocone penetration tests(CPTu) together with a variety of borehole seismic tests were performed at many sites in Korea. Through statistical modeling of the in-situ testing data, in this study, the correlations between $V_S$ and geotechnical in-situ penetrating data such as blow counts(N value) from SPT and piezocone penetrating data such as tip resistance ($q_t$), sleevefriction($f_s$), and pore pressure ratio($B_q$) were deduced and were suggested as an empirical method to determine $V_S$. Despite the incompatible strain levels of the conventional geotechnical penetration tests and the borehole seismic tests, it is shown that the suggested correlations in this study are applicable to the preliminary estimation of $V_S$ for Korean soil layers.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.09a
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• pp.264-279
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• 1995

오늘날 기업 경영 환경은 더욱 복잡해지고, 국가간.지역간 통합 경제 체제 형태로 변화하고 있다. 정보 기술과 텔리커뮤니케이션의 결합에 따른 급속한 발전은 국가간.지역간 경계를 넘어 다국적 기업, 더 나아가서는 범세계적 기 업으로 글로벌(global) 기업을 출현시켰다. 경영 환경의 빠른 변화의 추세 속 에서 경쟁 우위를 지키기 위해서는 이러한 변화를 적절히 수용하고 적응할 수 있는 조직이 필요하였다. 기존의 MIS 관점으로는 환경 변화에 적응 할 수 있는 혁신적인 조직으로 변화시키는 데는 한계가 있었고, 이에 따라 BPR 이 대두되었다. BPR실행에 있어 성공뿐만 아니라 많은 실패도 겪었다. BPR 실행에는 많은 자금과 인력, 시간이 투자되기 때문에 실패의 손실은 기업에 게 큰 타격을 가져다 줄 수 있다. 대부분의 BPR의 실패 원인은 사회적 측면 을 고려하지 못한 데 있다. 정보 기술을 이용하여 프로세스를 급진적으로 재 설계 하였지만, 운영 주체인 구성원의 저항감이나 조직의 문화에 대한 고려 를 하지 못하였다. 그러므로 BPR을 수행함에 있어 사회적 측면과 기술적 측 면을 동시에 고려하여 적용한다면 오류나 실패 요인을 감소시킬 수 있다. 따 라서 요즈음 새로이 부상하고 있는 사회.기술적 시스템 접근법은 성공적인 BPR 실행을 위한 대안이 될 수 있다.

• Convergence Security Journal
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• v.18 no.5_2
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• pp.35-41
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• 2018

The Army has developed the concept of terrestrial warfare in conjunction with the Joint Concept and has introduced TICN as the base communication system to support it. TICN has been used to improve the transmission speed and to increase the coverage distance. Through this, TICN is making efforts to create network-centered operation environment so that information can be distributed in real time or near real time from the monitoring system to the hitting system. However, TICN is not enough to overcome the network limitations that may arise from various contingencies in battlefield situations. Therefore, in this paper, we investigated the limitations of communication according to the situations that can occur in the battlefield situation and studied the considerations to overcome them.

• Trans-
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• v.10
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• pp.15-29
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• 2021

After the coronavirus pandemic, quarantine or social distancing was required for public health and almost all international exchanges were restricted. Those changes affected huge peoples lifestyle including a way of behaving, purchase and even old habits seemed unable to change. The art market also faced many changes. Art fairs are the primary sectors in the art market but restrictions on gathering and exchanges between countries have primarily affected the size and the type of event. Online platforms are rising, art fairs opened online viewing rooms on the internet instead of booths in the convention center. Even galleries opened their own viewing rooms or renewed online pages to promote artworks and communicate with customers. In this paper, we will examine the effects of Corona on the art market and will seek a way to react to those changes and challenges.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.117-119
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• 2010

미래 전쟁은 과거의 재래식 전쟁과는 판이하게 변화된 환경 속에서 새로운 전투 형태와 방법으로 전개될 것이다. 특히, 첨단 기술의 급속한 발전은 전장에서 싸우는 방법을 변화시키는 주요 요인이라고 할 수 있다. 전장에서 적을 먼저 발견하고 타격하기 위해서는 실시간 표적 획득 및 첩보 수집과 정확한 상황판단 및 적시적인 지휘가 요구되기 때문에 정보 수집 자산이 부족한 사 여단급 부대를 대상으로 감시 정찰 센서 네트워크 시스템을 구축하는 것이 필요하다. 그러나 평시 체계와 전시 체계의 운용 개념이 부족한 상태에서 실 세계에 적용하는 것은 유지비용의 증가, 감지 오류, 야전 환경과의 부적합 등을 야기한다. 따라서, 이러한 문제점의 해결 대안으로 이 논문에서는 지상군 작전에서 적의 조기 발견과 전장 가시화에 필요한 전장감시 센서 네트워크 시스템을 위한 상황 인식 프레임 워크를 제안하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.9-16
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• 2014

In recent years, the structural shock response to UNDEX (UNDerwater EXplosion) has been studied as much, or more, through numerical simulations than through testing for several reasons. Very high costs and sensitive environmental concerns have kept destructive underwater explosion testing to a minimum. Increase of simulation capabilities and sophisticated simulation tools has made numerical simulations more efficient analysis methods as well as more reliable testing aids. In this study, the main issue is the fluid-structure interaction. Here, appropriate relations between the acoustic pressure on the fluid surface and displacements on the structure surface are formed internally. The analysis was carried out using ABAQUS/Explicit and the results have been visualized in ABAQUS CAE. The shock loading history, acoustic pressure, stress of stand-off point, the velocity and strain energy time histories were presented.

• International Journal of Highway Engineering
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• v.9 no.2 s.32
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• pp.89-99
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• 2007

The stiffness of the asphalt concrete is represented by the complex modulus $E^*$, which is very important properties in the mechanistic design of flexible pavement system. The moduli of asphalt concrete were generally determined by dynamic modulus test. However, the dynamic modulus testing method is too complex, expensive, and time consuming to be applicable on a production basis. The IR(Impact Resonance) method has been shown to be a truly simple nondestructive testing method which produces very repetitive, consistent results. The major object of this study was to estimate of the effects on IR tests for determining modulus of asphalt concrete including impact position, specimen support condition, impact steel ball size and sampling rate. The variations of IR test results with various testing conditions are within ${\pm}2.7%$.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.95-100
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• 2006

To reveal subsurface structures of the Ulsan fault, seismic data were recorded along a 750-m long line near Nongso-Eup in Ulsan. P and S waves were generated simultaneously by impacting a 5 kg sledgehammer on a tilted plate. The data were received by 16 10-Hz 3-component geophones at 3 m intervals. Refracted P waves were inverted using the tomography method. Dip moveout and migration were applied to reflection data processed following a general sequence. Four layers were identified based on P-wave velocities and P- and S-wave stacked image. From top to bottom, the P-wave velocity of each layer ranges in $300{\sim}1100\;m/s$, $1100{\sim}1700\;m/s$, $1700{\sim}2700\;m/s$, and greater than 2700 m/s. The corresponding thickness of the top three layers averages 3.9 m, 5.9 m, 4.4 m, respectively. The S-wave stack section is effective to define subsurface structures shallower than 10 m.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.219-224
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• 2020

The purpose of this study is to develop a device to replace the pre-boring method, which is generally constructed, to prevent pile damage caused by tension cracks that reason from tension waves generated during PHC pile construction on soft ground. Tension cracks are caused by tension waves from the hammer striking during the PHC pile hitting on the soft ground, which in turn leads to faulty construction. In order to prevent the occurrence of tension waves generated during driving, apply separate driving force increasing device to prevent the generation of tension waves, and pile damage as well. Also, it is an eco-friendly construction method that reduces smoke and noise by improving construction speed, reducing construction costs, and able to small equipment when developing equipment. This development equipment is a piece of effective equipment that can pioneer the Saemangeum reclamation area, the South-east Asian construction market, where the Deep soft ground is distributed.