• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.105-110
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• 2011

Recently, a deep mixture method as a soil improvement method of marine soft ground, which causes less noise and vibration than other methods, are widely used. In this study, for DCM(Deep Cement Mixing) method, one of the deep mixture method, optimum mixing ratio of clay-cement was suggested using uniaxial compression tests on specimens with various mixing ratio of claycement. In addition, the stability of a caisson on tangent circle-type and wall-type DCM treated ground was evaluated using centrifuge tests. As a result, optimum mixing ratio of clay-cement was 28.5% and the stability of the caisson on DCM treated ground was confirmed. However, the lateral displacement of the caisson on the wall-type DCM treated ground was 7% less and the settlement of that was 39% less than the case of the tangent-circle-type DCM method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.430-435
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• 2007

소음특성이 서로 다른 군용 항공기 소음과 민간 항공기 소음을 환경부에서 고시한 소음 진동공정시험방법에 의거하여 소음을 측정하고 평가하는데는 개선되어야 할 문제점이 뒤따른다. 따라서 본 연구에서는 민간 항공기와 군용 항공기의 소음특성으로 조사하고 소음 측정 및 평가방법에 대한 문제점들을 고찰하였다. 연구결과로 부터, 민간 항공기나 군용 항공기의 정확한 소음측정을 위해서는 동특성을 빠름(Fast)으로 설정하여 측정하는 것이 바람직한 것으로 확인되었다. 또한 등가 소음도를 측정하여 항공기 소음을 평가하는 방식은 민간 항공기 소음평가시에는 적절하지만, 이를 군용 항공기 소음에 적용하여 평가할 때에는 상당한 오차를 포함하는 것으로 조사되었다. 그리고 군용 항공기 이 착륙지점에서의 소음 지속시간이 대부분 30초를 초과하는 것으로 조사되었기 때문에, 군용 항공기 소음평가시에는 지속시간에 대한 보정이 반드시 반영되어야 할 것으로 사료된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.205-209
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• 1997

본 고에서 소개될 내용은 기존에 계측기로 구성되는 시스템의 하드웨어 구성과 PC로 구성할 때의 사양 비교를 알아보며, 응용 프로그램에 있어 상용화된 프로그램 tool을 활용하여 응용 프로그램을 개발하는 기술과 지원 방안을 제시하고자 하며 엘텍에서는 이러한 하드웨어와 user 응용 프로그램의 완벽한 개발로 실사용자들이 보다 나은 시스템 환경에서 완벽한 시험/측정/분석의 업무를 수행할 수 있도록 지원한다. 또한 외국의 많은 업체가 이 프로그램을 이용하여 자체 시스템을 구축하여 국내에 소개되는 시스템이 많은 실정이다. 엘텍에서는 이미 NDT, AE, THD/전원 분석을 위한 시스템 및 프로그램 개발을 완료했으며 국내에 이미 소개된 시스템도 있다. 그러므로, 소음.진동 분야에도 완벽한 시스템 구축을 추진하고자 한다.

• Journal of the Korean GEO-environmental Society
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• v.3 no.2
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• pp.61-70
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• 2002

This paper presents the engineering property of light weight soil made of soil mixed with recycled Styrofoam and stabilizer. Recycled Styrofoam is widely used for lightweight fill material because it has important geotechnical characteristics which are light, adiabatic, and effective for vibration interception. It is very easy to get the disposal styrofoam. For this study, dynamic compaction test, static compaction test and pH and leaching tests were performed. Based on the test results, it is concluded that the static compaction method is recommened to prevent from crushing materials and pH values of embankment materials are satisfied with these of domestic and RCRA configuration.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.43-50
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• 2000

This paper presents the engineering property of light weight soil made of soil mixed with recycled stylofoam and stabilizer. Recycled stylofoam beads is able to use by lightweight fill materials because it is light, adiabatic, and effective for vibration interception. Especially, recycled stylofoam beads is easy to supply because stylofoam have been recycle item in 1996. In this study, physical and geotechnical properties of the light weight mixed soil(weathered granite soil mixed with Stylofoam Beads) were analyzed by laboratory experiments to examine its suitability for backfill materials. Laboratory tests were performed to evaluated strength, bearing capacity, weight, permeability, microphotograph analysis with variation of mixing ratio. Based on the results, it is concluded that the use of recycled stylofoam beads is acceptable lightweight fill.

• Explosives and Blasting
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• v.42 no.1
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• pp.1-11
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• 2024

Through existing research and construction cases during tunnel blasting, the electronic blasting method is reported to be more effective in reducing blast vibration than the normal blasting method. However, due to the high price of electronic detonators, they are only used in some blasting sites where security objects are located nearby. Accordingly, this study performed tunnel blasting tests by adjusting the ratio of electronic and non-electronic detonators. And through the research results, the reduction effect of blasting vibration according to the detonator ratio was evaluated. The research results showed that the reduction effect of blast vibration was greatest when 100% electronic detonator was applied. In addition, when more than 52% of the electronic detonator was applied, it was found that the reduction effect was similar to the reduction effect when 100% of the detonator was used.

• Explosives and Blasting
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• v.22 no.1
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• pp.23-32
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• 2004

터널 발파를 원활히 수행하기 위해서는 암반조건에 적합한 합리적인 설계와 정밀한 천공, 정확한 기폭초시가 기본요소로서 이는 현재 국내 터널 설계.시공 기술 및 기자재의 발달로 만족할 만한 성과를 얻을 수 있다. 특히. 터널발파에서 정확한 기폭초시 부여는 굴진율 및 버럭 파쇄율, 굴착예정선 미려도, 잔여 암반 손상도 등의 시공성에서 뿐만 아니라 소음 및 진동 발생율을 좌우하는 환경적인 측면에서 매우 중요한 요소이다. 기폭요소는 최초 도화선을 활용한 공업뇌관에서 전기뇌관, 비전기식뇌관의 순으로 기폭안전성과 정밀성 면에서 눈부신 성장을 이룩하여 왔으며 특히, 90년대 초에 개발되어 전 세계적으로 최근까지 지속적으로 사용량이 급증하고 있는 전자뇌관은 기폭방식에 일대혁신을 이루었다. 전자기폭 시스템은 기존뇌관의 초시를 결정하는 화약성분의 지연요소 대신에 IC board(전자회로)에 의한 Digital timer로 신호를 발생하여 초시를 결정하는 방식이다. 본 논문에서는 국내 최초로 전자기폭시스템을 활용하여 2003년 9원 23일에서 동년 11월 2일까지 강원도 양구 지역의 $\bigcirc\bigcirc$터널에 전자뇌관을 이용한 시험발파를 실시하였고, 발파에 의한 진동 등을 조사하여 그 효율성을 검토하였다. 이를 위해 전자뇌관의 특성과 장점을 최대한 샅리기 위하여 각공을 발파하는 방식, 즉 1지발에 1공을 발파하는 방식을 채택하고 일반 뇌관과 전자뇌관으로 설계를 하여 각각의 발파효율을 비교하여 보았다. 그 결과 발파진동의 경우 기존뇌관을 이용하여 1공씩을 1지발로 발파를 한 경우에는 18~56%의 진동저감 효과가 있었고. 본선 설계에 의해 진행된 발파에 비하여는 최대 70% 이상의 진동저감 효과가 있는 것으로 나타났다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.87-92
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• 2005

This paper presents a design concept of smart UAV console system and the analysis of its dynamic response to shock and vibration. The console system design is determined by two main elements; the shape design and the mechanical design. The shape design refers to the human engineering aspects according to the military standards for ship borne equipment. The goal of the mechanical design is to provide the required shock and vibration endurance. The endurance of the system is numerically verified by means of Finite Element Method. The results of verification show that six resilient mounts installed on the console allow to sufficiently decrease the influence of the input impact wave on endurance of the system.

• Explosives and Blasting
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• v.33 no.2
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• pp.25-39
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• 2015

The common underwater rock removal methods involve underwater blasting and crane's chisel dropping impact method. From an environmental point of view, these methods cause ground vibrations and underwater noise. At the site for this study, a method of dropping heavyweight chisel is selected to remove the underwater bedrock near the ferry rack in the course of improving the cargo handling ability of the loading dock. A prediction formula for the vibration was obtained based on the measurement and evaluation of the vibrations caused by the chisel dropping impacts during the test droppings. The prediction formula was successfully applied to the main construction for securing the stability of the structure.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.6
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• pp.596-605
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• 2022

In this study, analysis of dynamic characteristics and flight vibration was performed to unmanned aerial vehicles. The analysis model was supplemented by performing a dynamic characteristic test and a random vibration test using manufactured dummy aerial vehicle. For the dynamic characteristic test, a bungee cable was used to implement the free end boundary condition. Prior to the flight vibration test using a multiple electric shaker, a random vibration test was performed to predict the excitation force during the actual flight vibration test. It was judged that the actual test could be predicted more accurately by supplementing the analysis model from the test results. In addition, it was possible to determine the feasibility of the test by predicting the excitation force of the flight vibration test.