• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.272-276
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• 2000

Reverse engineering refers to the process that creates a physical part from acquiring the surface data of an existing part using a scanning device. In recent years, as the non-contact type scanning devices become more popular, the huge amount of point data can be obtained with high speed. The point data handling process, therefore, becomes more important since the scan data need to be refined for the efficiency of subsequent tasks such as mesh generation and surface fitting. As one of point handling functions, the cross-sectioning function is still frequently used for extracting the necessary data from the point cloud. The commercial reverse engineering software supports cross-sectioning functions, however, these are only for cross-sectioning the point cloud with the constant spacing and direction. In this paper, adaptive cross-sectioning point cloud which allow the changes of the spacing and directions of cross-sections according to the constant spacing and direction. In this paper, adaptive cross-sectioning algorithms which allow the changes of the spacing and directions of cross-sections according to the curvature difference of the point cloud data are proposed.

• 대한안전경영과학회지
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• 제19권3호
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• pp.129-135
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• 2017

The respective delivering vehicle loaded with the own cargo moves into the respective delivery area. At the base, the delivery points D1 and D2, for example, have the same starting point but the destination is different. The average delivering time of the delivery vehicle is mostly more than 8 hours a day. Therefore, the efficiency of delivery is generally low. In this study, the deliveries will be forwarded from a base station to a delivery point where cross docking will be applied to a single vehicle, and will be distributed from the cross docking point through cross docking. If the distribution is implemented, one vehicle will not have to be operated from the base to the cross docking point. In that case, logistics cost will be reasonably saved by the reduction of transportation cost and labor time. If one vehicle only runs from the base to the cross docking point, each vehicle will be operated in two shifts, and the vehicle operation can be efficiently implemented. This research model is based on the assumption that the 3 types of ratios between the traffic volume of the vehicles starting at the base and the vehicles waiting at the cross docking point are set to the first ratio of 30% to 70%, the second ratio of 50% to 50% and the final ratio of 70% to 30%. As a result of the study, The delivery time in the cross docking point is much higher than that in present on the condition that the cargo volume in the D2 area is more than 50%. Likewise, the delivery time is slightly higher on the condition that the cargo volume is less than 50%. Time is reduced in terms of 50% model like AS-IS model.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1874-1875
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• 2007

전력선 통신(Power Line Communication)은 전력선과 연결되어 있는 디바이스들을 간단히 제어하기 위한 기술로 제안 되었으며, 홈오토메이션, 원격 검침(AMR) 분야에서 많이 사용되고 있다. 최근에는 스마트 홈, 유비쿼터스와 관련해 다양한 홈 네트워크 시스템들이 제안되면서 이들 시스템을 효과적으로 구현할 수 있는 방안으로 전력선 통신기술이 많이 제안되고 있다. 전력선 통신은 많은 유용성에도 불구하고 전력선 채널에 대한 정확한 채널 모델링과 전력선 모뎀의 성능에 관해서는 많은 문제점을 나타내고 있다. 본 논문에서는 전력선 통신을 위한 전송선로의 주파수에 대한 잡음과 임피던스 특성 및 전력선 채널에 데이터 신호를 Chirp-SS(Spread Spectrum) 신호로 맵핑하여 채널의 Zero Cross Point 구간에 전송하였을 때의 시뮬레이션 결과와 설계된 FPGA 보드를 비교분석 하였다. 채널 모델은 배경 잡음과 할로겐 잡음, 전송선로의 감쇄 특성만을 고려하였으며, 전력선 채널 상에서의 Zero Cross Point를 이용한 전력선 통신 모뎀의 성능을 분석하였다.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.680-681
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• 2015

This study develops an algorithm that automatically performs reverse engineering on three-dimensional (3D) sweeping shapes using a user's pre-defined feature templates and 3D point cloud data (PCD) of sweeping shapes. Existing methods extract 3D sweeping shapes by extracting points on a PCD cross section together with the center point in order to perform curve fitting and connect the center points. However, a drawback of existing methods is the difficulty of creating a 3D sweeping shape in which the user's preferred feature center points and parameters are applied. This study extracts shape features from cross-sectional points extracted automatically from the PCD and compared with pre-defined feature templates for similarities, thereby acquiring the most similar template cross-section. Fitting the most similar template cross-section to sweeping shape modeling makes the reverse engineering process automatic.

• Journal of the Korean Data and Information Science Society
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• 제23권4호
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• pp.765-775
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• 2012

교차타당성은 커널추정량의 평활모수인 띠폭의 선택 방법으로 흔히 활용되고 있다. 연속인 확률밀도함수의 커널추정량의 띠폭 선택으로 널리 쓰이는 교차타당성 방법으로는 최대가능도교차타당성과 더불어 최소제곱교차타당성과 편의교차타당성이 있다. 확률밀도함수가 하나의 불연속점을 가질 때, Huh (2012)는 불연속점 추정을 위한 커널추정량의 띠폭 선택으로 최대가능도교차타당성을 이용한 방법을 제시하였다. 본 연구에서는 Huh (2012)에 의해 최대가능도교차타당성으로 제안된 띠폭선택의 방법과 같이 한쪽방향커널함수를 이용한 최소제곱교차타당성과 편의교차타당성으로 띠폭 선택 방법을 제시하고, 이들 띠폭 선택 방법들과 Huh (2012)의 최대가능도교차타당성을 이용한 띠폭 선택 방법을 모의실험을 통하여 비교연구 하고자 한다.

• 소음진동
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• 제7권3호
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• pp.477-488
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• 1997

In order to control vibration in structures, it is desirable to be able to identify dominant paths of vibration transmission from sources through the structure to some points of interest. Structural intensity vector(power flow per width of cross section) using cross spectra is able to measure the vibration power flow at a point in a structure. This paper describes the structural intensity measurement of 2-dimensional structure. Structural intensity of 2-dimensional structure can be obtained from eight point cross spectral measurement per axis, or two point measurement per axis on the assumption of far field. Approximate formulation of the relation between bending waves in structures and structural intensity makes it possible to separate the wave components by which one can get a state of the vibration field. Experimental results are obtained on an infinite plate at the near and far field in flexural vibration. The measurement error of two point measurement is rather bigger than eight point measurement on account of the assumption that Poisson's ratio is 1. The structural intensity vectors on the plate are checked the ability to identify the path of vibration power flow in random excitation and 200Hz sine excitation, the result of two point measurememt is almost the same as the result of eight point measurement in 200Hz sine excitation.

• 한국정보처리학회논문지
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• 제1권3호
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• pp.409-417
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• 1994

고도행렬로부터 등고선을 추출하는데 있어, 가장 중요한 문제는 하나의 격자에 네개의 통과점이 발생하는 이상 상황(degenerate case)의 해결이다. 본 논문은 이상 상황 검사와 다음점 결정을 동시에 수행하는 방법을 기술한다. 이 방법은 최소 횟수 의 배열 인덱싱을 필요로 한다. 또한 통과점을 모서리점의 높이차에 따라 LOWER/ HIGHER로 표시하고, 이 정보를 이용하여 보다 적은 횟수의 배열 인덱싱을 필요로하는 방법을 제안한다. 그리고 통과점을 표시하고 이들을 추적하기에 적합한 자료구조를 구체적으로 기술한다.

• 대한수학회논문집
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• 제21권4호
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• pp.701-717
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• 2006

The positive coexistence of a simple food chain model with ratio-dependent functional response and cross-diffusion is discussed. Especially, when a cross-diffusion is small enough, the existence of positive solutions of the system concerned can be expected. The extinction conditions for all three interacting species and for one or two of three species are studied. Moreover, when a cross-diffusion is sufficiently large, the extinction of prey species with cross-diffusion interaction to predator occurs. The method employed is the comparison argument for elliptic problem and fixed point theory in a positive cone on a Banach space.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.755-758
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• 2002

The physical phenomena of rectangular open cavity are numerically investigated in this paper Two-dimensional cavity problems with laminar boundary layers in upstream are simulated by using the compressible Wavier-Stokes equations. The high-order and high-resolution numerical schemes are used for the evaluation of spatial derivatives and the time integration. Cross-correlation is used to analyze the characteristics of wave propagation along time and spatial. Sudden phase shifting of 90 degrees is appeared near downstream edge, and this is coincident with the phase lag suggested in original Rossiter's equation. The results give a further understanding of the physical phenomenon of noise generation, and the resonance of flow and acoustic in cavity. Moreover, modified Rossiter's equation, which is more accurate and can be applied in various conditions, is suggested. The distance from the point of vortex generation to the point of vortex collapsing acts as effective distance of cavity resonance, and the phase difference between the point of vortex collapsing and the point of acoustic source acts as phase lag. The mechanism of acoustic generation is fully understood in this paper. The mechanism of acoustic generation is fully understood in this paper.