• 화약ㆍ발파
• /
• 제24권2호
• /
• pp.83-91
• /
• 2006

종래의 발파진동 분석은 주로 대상 지장물에 대한 피해한계를 정립시키고자 하는 관점에서 발파공에서 비교적 원거리의 진동특성을 이해하기 위해 수행되어져 왔으나, 최근의 추이는 발파공 주변 암반의 손상의 정도를 평가하고자 하는 관점에서 그 분석영역의 범위가 근거리 진동특성 연구분야로 확대되고 있는 실정이다. 암반손상의 평가를 위한 손상권 예측방법에는 여러 가지가 있으나 그 중에서 대부분이 발파진동속도에 근거하고 있으며, 평가를 위한 진동의 예측은 기존에는 원거리 진동특성을 이용하여 근거리 진동을 예측하는 방법으로 그 손상의 정도를 평가하였으나, 최근의 추세는 계측기의 발달로 수m 이내의 진동특성의 계측이 가능하게 되었다. 이와 관련하여 국외에서는 수차례의 실험결과가 여러 문헌에서 보고되고 있으나, 실험장비의 선택 및 측정방법의 어려움 등의 연유로 국내에서는 아직까지 실시되지 못하고 있는 상황이다. 따라서, 본 연구에서는 실제 발파공 근접진동 계측을 실시하고 그 결과를 분석하여 추후 지속적인 근거리 진동측정 방법 및 평가방법에 대한 기초자료를 제공하고자 하였으며, 무엇보다도 어떻게 계측할 것인가 하는 계측방법 및 그 계측결과의 분석방법에 대해 문제점 파악 및 향후 보완점에 대해 비중을 두어 수행하였다.

• Computers and Concrete
• /
• 제20권6호
• /
• pp.711-718
• /
• 2017

Nanotechnology is a new filed in concrete structures which can improve the mechanical properties of them in confronting to impact and blast. However, in this paper, a mathematical model is introduced for the concrete models subjected to impact load for wave propagation analysis. The structure is simulated by the sinusoidal shear deformation theory (SSDT) and the governing equations of the concrete model are derived by energy method and Hamilton's principle. The silicon dioxide ($SiO_2$) nanoparticles are used as reinforcement for the concrete model where the characteristics of the equivalent composite are determined using Mori-Tanaka approach. An exact solution is applied for obtaining the maximum velocity of the model. In order to validate the theoretical results, three square models with different impact point and Geophone situations are tested experimentally. The effect of different parameters such as $SiO_2$ nanoparticles volume percent, situation of the impact, length, width and thickness of the model as well as velocity, diameter and height of impactor are shown on the maximum velocity of the model. Results indicate that the theoretical and experimental dates are in a close agreement with each other. In addition, using from $SiO_2$ nanoparticles leads to increase in the stiffness and consequently maximum velocity of the model.

• 한국지반공학회지:지반
• /
• 제13권1호
• /
• pp.5-18
• /
• 1997

일반적으로 포화지반의 동적거동을 정확히 예편하기 위해서는 다공성(multi-phase) 재료모델과 그 모델을 이용하는 수치해석 프로그램의 개발이 필요하다. 본 논문에서는 높은 동하중을 받는 다공질 재료의 이론적인 거동해석 연구결과와 함께 기존 MPDAP(multi-phase dynamic analysis program)에 JWL(Jones-Withins-Lee) 모델을 삽입시켜 개발한 MPDAP에 대해 다루었다. JWL모델은 기존 모델과는 달리 폭약의 종류 및 특성 등을 고려할 수 있는 모델이다. 또한 본 논문에서는 개발된 프로그램의 적합성을 조사하기 위하여 몇몇 예제에 대한 검증해석을 수행하였다. 검증결과, 단일매체 (single-phase medium)에서의 탄성구형파의 전파특성 해석의 경우 해석결과와 이론해는 거의 일치하는 결과를 나타내었고, 일차원 선형 압밀해석의 경우과잉 간극수압은 Terzaghi의 이론해와 해석된 결과가 비교적 일치하는 경향성을 보여 주었다. 또한 포화지반에서의 평면 압축파 해석의 경우도 해석결과와 이미 검증된 프로그램 또는 완전해의 해석결과는 거의 유사하게 나타나는 것을 알 수 있었다.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
• /
• pp.49-54
• /
• 2000

Korea Institute of Geology Mining and Materials(KIGAM) has been operating Korean Earthquake Monitoring System(KEMS) to archive the real-time data stream and to determine event parameters (epicenter origin time and magnitude)by the automatic processing and analyst review. To do this KEMS uses the Vindel Hue's velocity model which was derived from Wonju KSRS data. Because KIGAM now receives the real-time data from many stations including Wonju KSRS Cholwon seismo-acoustic array Uljin Wolsung Youngkwang Taejon Seoul Kimcheon Taegu etc. the proper velocity model should be established around the Korean peninsula, In this study P were velocity structures was derived from VELEST program using 69 events among the 835 events determined by KEMS in 1999 which were recorded by at least 5 stations. General trend of velocity structure was similar to Sang Jo Kim's model but velocity value was low in crust and high in upper mantle. Due to the sensitivity of inversion results to the initial input model the artificial short and blast data might be added.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.922-925
• /
• 2011

Smoothed Particle Hydrodynamics (SPH) is a Lagrangian method widely used for the modeling fluid flows. Simulations of explosions require, besides the hydrodynamic equations, a realistic equation of state, an energy source term, and a set of chemical kinetic equations to follow the composition changes of the gas during the explosion. The performance of the hydrodynamic equations is investigated in the framework of the Sedov-Taylor blast-wave. The implementation of chemical kinetic equations and equation of state is studied with 1D detonation of TNT slab. Our results are compared to those from analytical and experimental studies.

• 한국자동차공학회논문집
• /
• 제4권4호
• /
• pp.179-189
• /
• 1996

An unstructured grid finite-volume method has been applied to predict the linear and nonlinear attenuation characteristics of the expansion chamber silencer system. In order to achieve a grid flexibility and a solution adaptation for geometrically silencer system. In order to achieve a grid flexibility and a solution adaptation for geometrically complex flow regions associated with the actual silencers, the unstructured mesh algorithm in context with the node-centered finite volume method has been employed. The present numerical model has been validated by comparison with the analytical solutions and the experimental data for the acoustic field of the concentric expansion chamber with and without pulsating flows, as well as the axisymmetric blast flowfield with open end. Effects of the chamber geometry on the nonlinear wave attenuation characteristics is discussed in detail.

• 천문학회지
• /
• 제37권2호
• /
• pp.61-77
• /
• 2004

We have searched for HI 21 cm line emission from shocked atomic gas associated with southern supernova remnants (SNRs) using data from the Southern Galactic Plane Survey. Among the 97 sources studied, we have detected 10 SNRs with high-velocity HI emission confined to the SNR. The large velocity and the spatial confinement suggest that the emission is likely from the gas accelerated by the SN blast wave. We also detected 22 SNRs which show HI emission significantly brighter than the surrounding regions over a wide ($>10 km\;s^{-1}$) velocity interval. The association with these SNRs is less certain. We present the parameters and maps of the excess emission in these SNRs. We discuss in some detail the ten individual SNRs with associated high-velocity HI emission.

• 천문학회보
• /
• 제37권2호
• /
• pp.64-64
• /
• 2012

Supernova remnants (SNRs) are beautiful and diverse. Individual SNRs have their own distinctive features. The morphology and physical characteristics of young SNRs result from the interaction of supernova (SN) ejecta with circumstellar medium, while those of old SNRs result from the interaction of SN blast wave with the interstellar medium. The diversity of SNRs reflects different types of SN and the broad physical conditions in their environments, which are ultimately related to the formation and evolutionary history of progenitor stars. The importance of SNe and SNRs as the sources of heavy elements, cosmic rays, dusts, hot coronal gases, and interstellar turbulences depends on their types and environments. In this talk, I discuss the connections among SNRs, SNe, and their progenitors, and the consequences on the characteristics and astrophysical roles of SNRs.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
• /
• pp.57-61
• /
• 2004

레이저 추진의 개념을 이용한 공기 흡입 레이저 스파이크 엔진은 대기권 내의 비행체에 사용될 수 있다. 레이저 스파이크 엔진은 연소 과정 대신 레이저 에너지에 의해 유도된 폭풍파에 의해서 추력을 얻는다. 그리고 이 엔진은 공기를 추진제로 사용하기 때문에 추진제를 따로 탑재할 필요가 없다. 실험에서는 초음속 풍동과 스파크 발생기를 사용하였다. 2차원 레이저 스파이크 엔진 모형을 사용하여 유동을 가시화 하였으며, 동일한 형태에 대한 수치 해석을 시행하였다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 1999년도 추계학술대회 논문집
• /
• pp.146-154
• /
• 1999

The test facility of the 1/60-scale models for the train-tunnel interactions was recently developed to investigate the effects of entry portal shapes, flood shapes and air-shafts for reducing the micro-pressure waves radiating to the surroundings of the tunnel exits by KRRI in Korea. The launching system of train model was chosen as air-gun type. In present test rig, after train model is launched, the blast wave by the driver did not enter to inside of the tunnel model. The train model is guided on the one-wire system from air-gun driver to the brake parts of test facility end. Some cases of the experiments were compared with numerical simulations to prove the test facility.