• 지구물리와물리탐사
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• 제7권1호
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• pp.7-13
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• 2004

In this paper, we demonstrate that Common Mid-Point (CMP) cross-correlation gathers of multi-channel and multi-shot surface waves give accurate phase-velocity curves, and enable us to reconstruct two-dimensional (2D) velocity structures with high resolution. Data acquisition for CMP cross-correlation analysis is similar to acquisition for a 2D seismic reflection survey. Data processing seems similar to Common Depth-Point (CDP) analysis of 2D seismic reflection survey data, but differs in that the cross-correlation of the original waveform is calculated before making CMP gathers. Data processing in CMP cross-correlation analysis consists of the following four steps: First, cross-correlations are calculated for every pair of traces in each shot gather. Second, correlation traces having a common mid-point are gathered, and those traces that have equal spacing are stacked in the time domain. The resultant cross-correlation gathers resemble shot gathers and are referred to as CMP cross-correlation gathers. Third, a multi-channel analysis is applied to the CMP cross-correlation gathers for calculating phase velocities of surface waves. Finally, a 2D S-wave velocity profile is reconstructed through non-linear least squares inversion. Analyses of waveform data from numerical modelling and field observations indicate that the new method could greatly improve the accuracy and resolution of subsurface S-velocity structure, compared with conventional surface-wave methods.

• 전기학회논문지
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• 제60권3호
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• pp.669-673
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• 2011

This study explores the numerical analysis method of fluid dynamics in the reaction section to improve the gas processing efficiency in the hazardous gas removal by atmospheric thermal plasma. This study also intends to contribute in technology advance to improve the processing efficiency and make the process more stable. Numerical analysis of temperature distribution in the reaction section dependent on the change in flow velocity of Ar and plasma temperature change, which are major control variables in the cracking process of HFC-23 using arc plasma, was done. The characteristic of incoming oxygen by temperature suggested that when temperature increased to 1600K, 1700K, 1800K respectively, the range of cracking temperature 1500K increased to 75.0%, 83.3%, 90.2% respectively. The temperature change of Ar by velocity change was widest in the area higher than 1500K when the velocity was 2.5m/s; however, since there was no big difference when the velocity was 2m/s, it is believed that 2 m/s would be most proper.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.377-381
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• 2006

A seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. General indicator of gas hydrate in seismic data is commonly inferred from the BSR(Bottom Simulating Reflector) that occurred parallel to the sea floor, amplitude decrease at the top of the BSR, amplitude blanking at the bottom of the BSR, decrease of the interval velocity and the reflection phase reversal at the BSR. In this paper we had analyzed optimum parameters of the field data to detect the 9as hydrate. Shot delay correction is applied 95ms, spherical divergence correction is applied velocity library 3, bandpass filter is applied 25-30-115-120Hz deconvolution operator length is applied 60ms, lag is 6ms and accurate velocity analysis NMO correction, stack is performed. Geobit 2.11.0 developed by the KIGAM was used for all data processing. Processing results say that the BSR occurred parallel to the sea floor were shown at 3,150m/s of two way travel time from the sea floor through shot point 5,000-5,610, and identified the interval velocity decrease around BSR and the reflection phase reversal corresponding to the reflection at the sea floor.

• 오토저널
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• 제15권2호
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• pp.92-104
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• 1993

In the present study, the velocity profiles and entrance length of developing transitional pulsating flows are investigated both analytically and experimentally in the entrance region of a square duct. The systems of conservation equations for transitional pulsating flows in a square duct are solved analytically by linearizing the non-linear convective terms. Analytical solutions are obtained in the form of infinite series for velocity pofiles. The experimental study for the air flow in a square duct(40mm*40mm*4000mm) is carried out to measure velocity profiles and other parameters by using a hot-wire anemometer with a data acquisition and processing system. The distribution of velocity profiles( $u_{ps}$ / $u_{m,ta}$) in the decelerating period is higher than in the accelerating period. The distribution of the axial component of the axial component of velocity in the transitional flow is nearly uniform in the central region of the duct, and decrease rapidly near the wall. The entrance length correlation of the transitional pulsating flows in a square duct is obtained to be $L_{e}$/ $D_{h}$=0.83 $A_{1}$R $e_{ta}$ /(.omega. sup+1)$^{2}$TEX>

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.56-61
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• 2002

In this paper we describe an approach to coordinating the motion of a human with a mobile robot moving in a populated, continuously changing. natural environment. Our test application is a wheelchair accompanying a person through the concourse of a railway station moving side by side with the person. Our approach is based on a method for motion planning amongst moving obstacles known as Velocity Obstacle approach. We extend this method by a method for tracking a virtual target which allows us to vary the robot's heading and velocity with the locomotion of the accompanied person and the state of the surrounding environment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.158.2-158
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• 2001

This paper introduces the design and implementation of a signal processing system for an airborne active homing radar system. This airborne active homing radar system uses the pulse Doppler radar of high PRF (Pulse Repetition Frequency) for computation of exact relative velocity of the target. This system carries out two operations mainly. The first is to transmit and receive microwave signal through the antenna. The second is to calculate the relative velocity of the target taking advantage of the Doppler frequency signal reflected from the target and detect the angle error between a target and an antenna LOS (Line Of Sight) to make the antenna direction coincident with the target. The signal processing system has a role of the latter.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2013년도 추계학술발표대회
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• pp.259-261
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• 2013

금융 IT와 같은 분야에서는 빅데이터의 큰 특징 중 하나인 Velocity의 개선이 가장 큰 문제이다. 이는 산업의 특성상 승자가 시장을 독식하는 구조로 0.1 초라도 빠른 시스템 속도를 확보하면 시장 경쟁력이 매우 크기 때문이다. 비단 금융 IT 뿐만 아니라 다른 산업들도 최근 보다 빠른 속도의 데이터 처리에 매우 민감하게 반응하는 환경으로 변화하고 있으므로 이에 대한 솔루션이 필요하며 본 연구에서는 폭증스트림의 고속처리를 위한 Low-Latency에 대한 다양한 실험과 환경 구축을 통해 빅데이터의 Velocity 문제를 해결할 수 있는 방안을 제시한다.

• 지구물리와물리탐사
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• 제5권3호
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• pp.178-184
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• 2002

탄성파굴절법 탐사는 절차가 단순하고 경제적이기 때문에 대형 구조물 건설을 위한 지반조사나 지질조사에 널리 이용되고 있다. 본 연구에서는 굴절법 탐사자료에 Kirchhoff 구조보정 방법을 적용하여 다양한 모형자료의 반응을 알아보고, 이에 대한 결과를 고찰하여 굴절법 탐사 자료를 이용한 지하 경계면 영상화 기법의 적용성을 파악해보고자 하였다. 모형반응 계산에 필요한 인공주시곡선의 작성에는 Vidale(1988)이 제시한 알고리즘을 사용하였고, 모형에 따른 반응을 살펴보기 위해 2층, 3층 모형 및 불규칙한 지표면을 가지는 모형 등에 대해 다양하게 살펴보았다. 구조보정을 위한 초기 속도 모형으로는 실제 구조와 같은 모형, 토모그래피에 의한 역산 단면, 실제 구조를 평활화한 모형 등을 사용해 초기 속도 모형이 달라질 때 결과에 어떤 영향을 미치는가 살펴보았다. 각각의 모형에 본 연구에 사용된 기법을 적용해 본 결과 반사법 구조보정에 비해 초기 속도 모형에 더욱 민감하다는 것을 확인할 수 있었으며, 현장 자료에 적용되기 위해서는 적절한 초기속도모형을 결정해야 할 것임을 알 수 있었다.

• 융합신호처리학회논문지
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• 제20권3호
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• pp.171-176
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• 2019

드론은 원거리 동영상을 효율적으로 획득할 수 있어서 활용성이 높다. 드론 운용에서 속도의 크기인 속력은 설정할 수 있지만 이동하는 방위의 정확한 값은 설정이 불가능하다. 본 논문에서는 드론에서 획득한 동영상을 이용하여 일정한 속도로 이동하는 드론의 속도를 추정한다. 기준 프레임과 표적 프레임의 Sum of Absolute Difference(SAD)를 최소로 하는 표적 프레임의 변위를 구한다. 드론의 실제 속도(Ground Truth)는 각 프레임에서 일정한 동일 지점(Matching Point)의 위치를 이용하여 계산한다. 실험에서 150m 상공에서 일정한 속력으로 이동하는 드론으로 동영상을 획득하였다. 추정한 x와 y방향의 속도와 속력의 평균 제곱근 오차(RMSE)를 구하여 제안한 방법의 신뢰성을 보였다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.127-133
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• 2000

In the present study flow characteristics of turbulent pulsating flow in a square-sectional 180。 curved duct are investigated experimentally. in order to measure axial velocity and secondary flow distributions experimental studies for air flow are conducted in a square-sectional $180^{\circ}$ curved duct by using the LDV system with the data acquisition and the processing system of the Rotating Machinery Resolver (RMR) and the PHASE software. The experiment is conducted on seven sections form the inlet(${\phi}=180^{\circ}$) at $30^{\circ}$ intervals of the duct. The results obtained from the experimentation are summarized as follows : In the axial velocity distributions of turbulent pulsating flow when the ratio of velocity amplitude(A1) is less than one there is hardly any velocity change in the section except near the wall and any change in axial velocity distribution along the phase. The secondary flow of turbulent pulsating flow has a positive value at the vend angle of $150^{\circ}$ without regard to the ratio of velocity amplitude. The dimensionless value of secondary flow becomes gradually weak and approaches zero in the region of bend angle $180^{\circ}$ without regard to the ratio of velocity amplitude.