• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2010.04a
• /
• pp.787-790
• /
• 2010

현재 고속도로 상의 노후 교량에 대하여는 재하시험을 통하여 정량적인 내하력 평가를 수행하고, 만족스러운 수준의 내하력이 확보되지 않은 경우에는 보수, 보강 또는 교체를 수행한다. 그러나 교통량이 많은 고속도로사의 교량에 대해서는 재하시험이 매우 어렵고, 센서 케이블 작업으로 인하여 작업성이 떨어지는 경우가 많다. 본 연구에서는 이러한 문제점들을 개선하기 위하여 상시교통하중에 의한 교량 내하력 평가 시스템에 대한 연구를 수행하였다. 내하력 평가 대상 교량에 대하여 상시진동계측을 수행하였으며, 계측된 데이터를 통하여 교량의 동특성을 추정하였다. 추정된 동특성을 바탕으로 초기 해석 모델을 Downhill Simplex 방법을 이용하여 개선하였으며, 개선된 교량 모델을 이용하여 재하시험을 시뮬레이션 함으로써, 처짐 보정 계수를 구하였다.

• 한국해양학회지
• /
• v.30 no.2
• /
• pp.116-124
• /
• 1995

Marine, shallow seismic data have been acquired and processed by newly developed multi-channel(6 channel), PC-based digital recording and processing system. The digital processing system includes pre-processing, swell-compensation filter, frequency filter, gain correction, deconvolution, stacking, migration, and plotting. The quality of processed sections is greatly enhanced in terms of signal-to-noise ratio and vertical/horizontal resolution. The multi-channel, digital recording, acquisition and processing system proved to be and economical, efficient and easy-to-use marine shallow seismic tool.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.4
• /
• pp.1044-1047
• /
• 1998

Non-destructive x-ray inspection system needs image intensifier to obtain the x-ray image. Captured image from image intensifier is distorted because the input plate of image intensifier has a spherical surface. In the research, in order to compensate this image distortion, we created the model of image intensifier and show mathematically that the image distortion was compensated. To show the performance of the proposed method, experiment was performed in real x-ray inspection system.

• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06c
• /
• pp.469-473
• /
• 2010

본 논문에서는 조각 병리 영상을 강체 정합을 통해 하나의 영상으로 자동 스티칭하는 방법을 제안한다. 제안 방법은 영상의 위치 초기화, 위치 보정, 강체 정합의 세 단계로 이루어진다. 첫째, 영상의 위치 초기화 단계에서는 순서 없이 흩어진 부분 영상을 탬플릿 매칭 기법을 사용한 영상 내 문자 인식을 통해 위치를 초기화한다. 둘째, 강체 정합의 정확성을 높이기 위해 코너점을 이용해 부분 영상의 위치를 보정한다. 셋째, 조각 영상 간 거리를 최소화하는 강체 정합을 수행한다. 실험 결과, 부분 영상 간 간격이 최소화되어 하나의 영상으로 스티칭되는 것을 확인하였고, 최적화 반복 횟수와 변환 벡터에 따른 정확성, 견고성 평가를 통해 거리 차의 제곱 합이 최소화되어 수렴됨을 알 수 있었다. 본 논문의 제안 방법은 조각 영상을 하나의 영상으로 스티칭함으로써 병리 조직의 전체적인 구조 파악과 이를 이용한 전립선암 확진에 사용될 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.4
• /
• pp.351-358
• /
• 2013

We propose a correction method of nonlinear frequency sweep in an FMCW(Frequency Modulated Continuous Wave) laser range finder. FMCW laser range finder requires linear frequency sweep for high resolution, and nonlinear frequency sweep makes the system performance degrade. In general, VCO(Voltage Controlled Oscillator) which is a component used for frequency modulation in FMCW method has nonlinear property. To correct the nonlinear frequency sweep, we utilize an auxiliary delay structure for generating trigger signal of ADC(Analog to Digital Converter). Because the trigger signal has same rate of change with the beat signal, the nonlinearity of the beat signal can be corrected. the experimental results show that the proposed method effectively eliminates the nonlinear frequency sweep problem and enhances the system performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.1
• /
• pp.1-11
• /
• 2016

The information about the deformations of high-aspect-ratio wings is needed for the real-time monitoring of structural responses. Wing deformation in flight can be predicted by using relationship between the curvatures and the strains on the wing skin. It is also necessary to consider geometric nonlinearity when the large deformation of wing is occurred. The strain distribution on fixed-end is complex in the chordwise direction because of the geometric shape of fixed-wings on fuselages. Hence, the wing displacement can be diversely predicted by the location of the strain sensing lines in the chordwise direction. We conducted a study about prediction method of displacements regardless of the chordwise strain sensing locations. To correct spanwise strains, the ratio of spanwise strain to chordwise strain, Poisson's ratio, and the ratio of the plate strain to the beam strain were used. The predicted displacements using the strain correction were consistent with those calculated by the FEA and verified through the bending testing.

• Journal of the Korean Society of Radiology
• /
• v.14 no.5
• /
• pp.503-510
• /
• 2020

Concrete is one of the most widely used materials as the shielding structures of a nuclear facilities. It is also the most generated radioactive waste in quantity while dismantling facilities. Since the concrete captures neutrons and generates various radionuclides, radiation measurement and analysis of the sample was fulfilled prior to dismantle facilities. An HPGe detector is used in general for the radiation measurement, and effective correction factors such as geometrical correction factor, self-absorption correction, and absolute detector efficiency have to be applied to the measured data to decide exact radioactivity of the sample. Correction factors are obtained by measuring data using a standard source with the same geometry and chemical states as the sample under the same measurement conditions. However, it is very difficult to prepare standard concrete sources because concrete is limited in pretreatment due to various constituent materials and high density. In addition, the concrete sample obtained by core drill is a volumetric source, which requires geometric correction for sample diameter and self absorption correction for sample density. Therefore in recent years, many researchers are working on the calculation of effective correction factors using Monte carlo simulation instead of measuring them using a standard source. In this study we calculated, using Geant4, one of the Monte carlo codes, the correction factors for the various diameter and density of the concrete core sample at the gamma ray energy emitted from the nuclides ¹⁵²Eu and ⁶⁰Co, which are the most generated in radioactive concrete.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.8
• /
• pp.99-104
• /
• 2005

The major role of a spacecraft structure is to keep and support the spacecraft safely in all the launch environment, on-orbit condition and during ground-transportation and handling. In a satellite development, a structural and thermal model (STM) is developed for two goals ; demonstration of a structural and a thermal stability. In the structure point of view, STM is used to verify the static/dynamic characteristics of structure in the initial stage of development. In this paper, the structure design/analysis of high resolution LEO earth observation satellite STM is described. Also, a low level sine vibration test is performed and compared to the results of finite element analysis.

• Journal of the KSME
• /
• v.44 no.12
• /
• pp.51-55
• /
• 2004

이 글에서는 AFM을 이용한 미소 구조물의 기계적 물성 측정 방법 중 기계적 물성 측정을 위한 대칭형 AFM 캔틸레버의 고안, 제작, 보정 및 측정 방법을 중심을 기술한다.

• Journal of the Mineralogical Society of Korea
• /
• v.31 no.3
• /
• pp.161-172
• /
• 2018

Multi-anvil press (MAP) is one of the high pressure apparatuses and often generates the pressure-conditions ranging from 5 to 25 GPa and temperature-conditions up to $2,300^{\circ}C$. The MAP is, therefore, suitable to explore the pressure-induced structural changes in diverse earth materials from Earth's mantle and the bottom of the mantle transition zone (~660 km). In this study, we present the experimental results for pressure-load calibration of the 1,100-ton multi-anvil press equipped in the authors' laboratory. The pressure-load calibration experiments were performed for the 14/8 step, 14/8 G2, 14/8 HT, and 18/12 assembly sets. The high pressure experiments using ${\alpha}$-quartz, wollastonitestructure of $CaGeO_3$, and forsterite as starting materials were analyzed by powder X-ray diffraction spectroscopy. The phase transition of each mineral indicates the specific pressure that is loaded to a sample at $1,200^{\circ}C$: a transition of ${\alpha}$-quartz to coesite at 3.1 GPa, that of garnet-structure of $CaGeO_3$ to perovskite-structure at 5.9 GPa, that of coesite to stishovite at 9.2 GPa, and that of forsterite to wadsleyite at 13.6 GPa. While the estimated pressure-load calibration curve is generally consistent with those obtained in other laboratories, the deviation up to 50 tons is observed at high pressure above 10 GPa. This is partly because of the loss of oil pressure at high pressure resulting from the differences in a sample chamber, and the frictional force between pressure medium and second anvil. We also report the ${\sim}200^{\circ}C/mm$ of thermal gradient in the vertical direction of the sample chamber of 14/8 HT assembly. The pressure-load calibration curve and the observed thermal gradient within the sample chamber can be applied to explain the structural changes and the relevant macroscopic properties of diverse crystalline and amorphous earth materials in the mantle.