• 대한기계학회논문집
• /
• 제18권2호
• /
• pp.359-371
• /
• 1994

A drop weight type impact test system is designed and set up to experimentally investigate impact responses of composite laminates subjected to the low-velocity impact. Using the test system, the impact velocity and the rebound velocity of the impactor as well as the impact force history are measured. An error of the measured data due to a difference in measuring position of the sensor is corrected and, for the estimation of real contact force history, a method of correcting an error due to friction forces is developed. Experimental methods to fix the boundary edgy of laminate specimens in impact testing are investigated and the impact tests on the specimens fixed by those methods are performed. Impact force histories and dynamic strains measured from the tests are compared with numerical results from the finite element analysis using the contact law. Consequently, the nonlinear numerical results considering the large deflection effects are agreed with the experimental results better than the linear ones.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1419-1424
• /
• 2003

Impact analysis of TFT-LCD module is very complicated because the structure is assisted with thin, small and non-uniform geometry. Especially, finite element modeling is more difficult and need time-consuming efforts. In this study, we developed LCD Impact Analysis System (LIAS) for the purpose of reducing the analysis time without accuracy reduction. This system contains pre-meshing data, material database, shock condition, auto-reporting etc. PATRAN and DYNA3D is used for meshing and solving. Previously, we performed impact test and reviewed the accuracy of analysis results. Simply we can control design parameters, the procedure such as meshing, running and reporting which are partially auto-prepared. By adopting proposed system, it is expected to achieve efficient impact analysis of LCD module.

• 전력전자학회논문지
• /
• 제16권1호
• /
• pp.58-63
• /
• 2011

본 논문에서는 기존의 사격통제장비를 대신하여, 명중탄과 피탄의 충격파형과 충격량을 검출하여 제어기 내부에 저장된 명중탄의 데이터와 상호 비교하여 표적기의 충격에 대한 명중 여부를 자체적으로 구분하는 알고리즘과 무선통신을 이용한 신형 사격통제장비의 개발내용을 기술하였다. 본 논문에서 적용한 명중탄 및 피탄의 구분은 타겟을 통과하는 명중된 관통탄과 그렇지 않은 경우의 타겟이 가해지는 충격량의 차이 및 변화로부터 명중탄의 범위를 산정하고, 이를 통하여 사격후의 결과를 판단하는 방식이다. 또한, 기존의 사격장비에서 적용하고 있는 유선통신으로 인한 배선 및 시설 노후화에 대한 문제를 Zigbee 무선 통신을 활용하여 시스템에 적용함으로써, 보다 간단한 사격통제장비의 개발이 가능하였다. 제안된 시스템은 실제 사격시험을 통하여 그 성능을 검증하였다.

• KIEAE Journal
• /
• 제12권1호
• /
• pp.73-81
• /
• 2012

Floor impact sound has been most annoying for years among the noises which are produced in apartment. This study aims to analyze the improvement of floor impact sound by comparing the results of the test which was carried out for the wall slab type apartment and moment frame apartment, and also for the effect of advanced vibration isolation layer. Moment frame structure that main structure consists of column and slab has shown better performance for the heavyweight impact sound comparing with wall slab type structure which is general type in Korea. Stiffness of floor system was raised by reinforcing the stiffness of vibration isolation layer, and it was analyzed how much the floor impact sound performance was improved. The result showed that the reinforced floor had better performance than the existing floor system that uses lightweight porous concrete as vibration isolation material. In addition, a system used wire mesh in mortar showed improvement of floor impact sound than a system without wire mesh, and better performance for the frequency bands lower than 160 Hz which causes floor impact problem in wall slab type apartment.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 추계학술대회논문집
• /
• pp.361-364
• /
• 2003

The safe operation and reliable maintenance of nuclear power plants is one of the most fundamental and important tasks. It is known that a loose part such as a disengaged and drifting metal inside of reactor coolant systems might lead to a serious damage because of their impact on the components of the coolant system. In order to estimate the impact position of a loose par, three accelerometers attached to the wall of the coolant system have been used. These accelerometers measure the vibration of the coolant system induced by loose part impact. In the conventional analysis system, the low pass filtered version of the vibration data was used for the estimation of the position of a loose part. It is often difficult to identify the initial point of the impact signal by using just a low passed time signal because the impact wave is dispersed during propagation into the sensor. In this paper, the impact signal is analysed by use of various time frequency methods including the short time Fourier transform(STFT), the wavelet transform, and the Wigner-Vill distribution for finding a convenient way to identify the starting point of a impact signal and their advantages and limits are discussed.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
• /
• pp.103-106
• /
• 2004

Impact location monitoring is one of the major concerns of the smart health monitoring. For this application, multipoint ultrasonic sensors are to be employed. In this study, a multiplexed FBG sensor system with wide dynamic range was proposed and stabilization controlling system was also developed for the maintenance of maximum sensitivity of sensors. For the intensity demodulation system of FBG sensors, Fabry-Perot tunable filter(FP-TF) with 23.8nm FSR(free spectral range) was used, which behaves as two separate filters between $1530 \~ 1560$ nm range. Two FBG sensors were attached on the bottom side of the graphite/epoxy composite beam specimen, and low velocity impact tests were performed to detect the one-dimensional impact locations. Impact locations were calculated by the arrival time differences of the impact longitudinal waves acquired by the two FBGs. As a result, multiplexed in-line FBG sensors could detect the moment of impact precisely and found the impact locations with the average error of 1.32mm.

• 한국시스템다이내믹스연구
• /
• 제14권1호
• /
• pp.31-53
• /
• 2013

The purpose of this study is to explain the impact of hosting mega event using the system dynamics and to establish the model for analysis of the impact of hosting mega event. The results are as follows. First, the growth of inbound tourists have influenced long term effect. Second, the export has increased for a limited period only after the hosting mega event, but the increase in export returned to the previous state in terms of economic impact of mega event. Third, nation brand has been improved for a limited period only such as the economical impact in terms of socio-cultural impact of mega event. Last, citizenship consciousness has been improved after hosting mega event. Further researches have to be carried out to modify and reinforce the model.

• 환경영향평가
• /
• 제14권4호
• /
• pp.179-193
• /
• 2005

As the world's attention turns to sustainability and the considerations of cumulative effects, the concept of Strategic Environmental Assessment(SEA) has become more significant and urgent and increasing number of countries and international organizations now undertake some forms of SEA. The term SEA, however, is variously defined and understood; generally it means a formal process of systematic analysis of the environmental effects on development policies, plans, programmes and other proposed strategic actions. This process extends the aims and principles of EIA upstream in the decision-making process, beyond the project level in which major alternatives are still open. There is a shift toward more integrative approaches and greater use of Environmental Impact Assessment (EIA) and Strategic Environmental Assessment (SEA) as sustainability tools in cooperation with Environmental Management System (EMS). Currently, Korea has EIA system and Prior Environmental Review System (PERS) which is different type of SEA as Environment Assessment (EA) system. APEMI IA MODEL integrated following three pillar(refer to attached figure.1) ; First pillar symbolized decision making cycle with planning process. Second pillar symbolized integrated assessment which tying SEA and EIA with specific impacts assessment(eg: social impact assessment, economic impact assessment, health impact assessment etc) in cooperation with EMS. Third pillar symbolized EA best practical procedure of International Association for Impact Assessment(IAIA). Considering the above, we applied new conceptual model(APEMI IA MODEL) into Impact Assessment for better integrated decision-making in KOREA as an alternative IA system(IS IA MODEL A and B refer to attached figure 4, 5).

• 한국지능시스템학회논문지
• /
• 제22권4호
• /
• pp.521-526
• /
• 2012

제조공정을 통해 생산된 화살의 성능은 화살의 이동궤적(궁사의 패러독스)과 탄착점의 집적도에 따라 좌우된다. 특히 동일한 환경에서 반복적으로 화살의 슈팅실험을 수행할 경우, 반복실험에서 얻어진 화살의 탄착점 집적도는 화살 성능 평가에서 중요한 객관적 지표가 된다. 그러나 화살의 탄착점에 대한 분석은 현재 상용화된 기술이 부족하며, 기존의 연구들은 화살의 성능에 영향을 미치는 제조공정 변수(화살깃, 화살촉, 화살의 곧기, 중량, 외경, 스파인)만을 최적화하려는 방향으로 기술력이 집중되어 있다. 본 논문에서는 화살의 주요성능지표인 화살의 탄착점 측정 자동화를 위해, Mamdani 퍼지 추론 시스템(Mamdani Fuzzy Inference System)과 도형의 닮음(Similarity of Polygon)을 이용한 화살의 탄착점 측정 시스템을 제안한다. 라인레이저(Line Laser)와 포토다이오드어레이(Photo Diode Array)를 이용하여 고속(약 275km/h)으로 이동하는 화살의 탄착점 데이터를 계측하고, 계측된 데이터를 퍼지 추론과 도형의 닮음을 이용하여 화살의 탄착점으로 사상(Mapping) 시킨다.

• 환경영향평가
• /
• 제20권3호
• /
• pp.337-348
• /
• 2011

Urban environmental problem became one of major issues during its urbanization processes. Environmental impacts are assessed during recent urban planning and development. Though the environmental impact assessment considers meteorological impact as a minor component, changes in wind environment during development can largely affect the distribution pattern of air temperature, humidity, and pollutants. Impact assessment of local wind is, therefore, a major element for impact assessment prior to any other meteorological impact assessment. Computational Fluid Dynamics (CFD) models are utilized in various fields such as in wind field assessment during a construction of a new building and in post analysis of a fire event over a mountain. CFD models require specially formatted input data and produce specific output files, which can be analyzed using special programs. CFD's huge requirement in computing power is another hurdle in practical use. In this study, a CFD model and related software processors were automated and integrated as a microscale wind environmental impact assessment system. A supercomputer system was used to reduce the running hours of the model. Input data processor ingests development plans in CAD or GIS formatted files and produces input data files for the CFD model. Output data processor produces various analytical graphs upon user requests. The system was used in assessing the impacts of a new building near an observatory on wind fields and showed the changes by the construction visually and quantitatively. The microscale wind assessment system will evolve, of course, incorporating new improvement of the models and processors. Nevertheless the framework suggested here can be utilized as a basic system for the assessment.