• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.125-130
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• 2002

본 연구는 DEVS를 기반으로 개발된 교통류 시뮬레이션 시스템인 $\ulcorner$I$^3$D$^2$ 교통류 시뮬레이션 시스템$\lrcorner$(이하 I$^3$D$^2$)의 검증을 그 목적으로 한다. I$^3$D$^2$는 본 연구진이 DEVS를 기반으로 개발한 범용 시뮬레이션 도구로써, 이미 서울시 강남 신호교차로와 내부순환로를 대상으로 하여 개발된 내용을 발표한 바 있다. I$^3$D$^2$는 헌재 단속류에서의 최적신호 생성 및 대기행렬 예측 문제, 그리고 연속류 시설의 용량 산정 문제등을 시뮬레이션 할 수 있다. 하지만 아직 문헌자료나 현장 데이터를 토대로 한 충분한 검증이 수행되지 못한 문제가 있다. 따라서 본 연구에서는 문헌자료를 토대로, I$^3$D$^2$를 검증한다. 이를 위하여 고속도로 또는 도시고속도로와 같은 연속 교통류의 대표적인 효과척도인 $\ulcorner$교통량 - 밀도 - 평균주행속도 (시간)$\lrcorner$ 간의 상관관계를 이용하여 미국 HCM과 우리나라의 도로용량편람에 정의되어 있는 기준을 토대로 I$^3$D$^2$ 검증을 수행하였다. 모델링은 서울시 올림픽대로의 양화대교 - 성산대교 - 가양대교 구간을 대상으로 했으며, 검증은 교통량에 따라 크게 3가지 교통류 상태(random, intermediate, constant)를 기준으로 시뮬레이션이 각각의 교통상태에서 예측한 평균주행시간의 정확도를 측정하면서 수행하였다. 검증 결과 random 상태에서는 문헌자료에 부합되는 예측결과를 보여주었으나, intermediate와 constant 상태에서는 문헌보다 다소 낮은 속도를 보여주었다 이러한 속도차는 추후 현장 데이터를 수집하여 보다 실질적인 검증을 통하여 조정되어야 할 것으로 판단된다.

• Journal of IKEEE
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• v.25 no.4
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• pp.584-590
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• 2021

This paper proposes a removal method of signal interference between ultrasound sensors where ghost signals due to interference are excluded and correct signal is recognized in distance mensurement using ultrasound sensors. The proposed method detects and excludes ghost signals when previous measured distance is compared to current measured distance and the distance difference exceeds a threshold. The threshold is fixed in conventional methods, so ghost signals cannot be correctly excluded when ultrasound sensor or target object move rapidly. On the contrary, to improve accuracy, the threshold is not fixed in the proposed method, and the threshold is adpatively determined based on the relative velocity when ultrasound sensor or target object move. Experiments of distance measurement with ultrasound signal interference are carried out where multiple ultrasound sensors of same type are exploited with maximum interference, and the results show that the proposed method efficiently exclude ghost signals.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1841-1844
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• 2009

일반 하천에서의 유량측정 방법은 하천 조건에 따라 다르다. 전통적인 방법으로는 구조물에 의한 방법, 유속계 측정에 의한 유속-면적법, 부자에 의한 방법, 그리고 희석법 등이 있다. 그러나 이러한 방법들은 측정 위험성을 가지고 있다. 홍수시 발생되는 고유속과 심한 난류, 거대한 부유물질들은 하천 접근에 어려움을 가져오고, 측정 기기의 파손 위험성뿐만 아니라 인명피해까지 발생시킬 가능성이 있다. 최근 기존 방법들의 문제점을 해결하기 위하여 음파, 초음파, 레이더 등을 이용한 유량 측정 방법과 장비들이 개발되었다. 본 연구에서 사용한 레이더 유속계는 하천의 표면유속을 측정하는 비접촉식 센서로 홍수기 전 미리 유속 측정 단면 측량을 실시한다면 홍수시에도 비교적 신속하고 안전하게 유속을 측정할 수 있다. 따라서 본 연구에서는 레이더 유속계를 충청북도 괴산군 달천에 위치한 수전교에 설치하여 괴산댐 방류량 및 동시유량 측정 성과와 비교하였다. 2007년 7월부터 2008년 8월까지 $36m^3/s\;\sim\;821m^3/s$의 사상에서 총 10회 측정한 결과, 레이더 유속계를 사용하여 측정한 유량의 상대오차는 댐방류량 대비 -3.3% $\sim$ 27.5%로 나타나 평균11.8%의 상대오차를 보였다. 레이더 유속계 측정과 동시에 실시한 유속-면적법 측정, ADCP법 측정의 상대오차는 각각 평균 5.7%, 6.5%로 나타난 것과 비교한다면 다소 높은 오차를 보였다. 그러나 측정 시간의 경우 수위에 따라 다소 차이는 있지만 레이더 유속계를 이용하면 30분 정도의 시간이 소요되었으며, 유속면적법은 1시간 이상, ADCP법은 40분의 시간이 소요되었다. 이와 같이 레이더 유속계는 다른 방법에 비해 정확성은 다소 떨어지지만 측정 속도와 안정성 면에서는 우수하다고 판단된다. 문제점으로 지적되는 정확도 측면의 경우 레이더 유속계로 측정되는 표면유 속과 평균 유속 사이의 보정계수 문제를 보완한다면 보다 정확한 측정이 가능할 것으로 판단된다.

• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.112-119
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• 2004

This paper proposes an attitude determination GPS/INS integrated system scheme for a UAV and presents experimental flight test results. The proposed system is designed as a part of an autopilot system and comprises a GPS attitude determination receiver, an off-the-shelf inertial measurement unit (IMU), and a navigation computer unit (NCU). UAV requires accurate attitude information for stable automatic flight control. The proposed system can provide accurate attitude information for the flight control computer (FCC) so that stable automatic flight control can be achieved. In order to verify the performance of the proposed scheme, an integrated navigation system has been developed. In order to evaluate the developed navigation system, the flight test has been performed. In the flight test, the developed system was shown to provide the position, the velocity and the attitude satisfactorily enough for stable flight control. The accuracy of the attitude information of the developed system was confirmed by comparing attitude of vertical gyro.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.60-67
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• 2022

An Electro-Optical Tracking System (EOTS) is an electric optical system with EO/IR cameras, laser sensors, and an IMU. The EOTS calculates coordinates of targets, using attitude and acceleration measured by the IMU. In particular for an armed aircraft, the performance of the weapon system depends on how quickly and accurately it acquires the target coordinates. The IMU should be operated after alignment is complete, to meet the coordinate accuracy required by the weapon system so the initial stabilization time of the IMU should be reduced, by quickly measuring the attitude and acceleration. Alignment is the process of determining the initial attitude by resolving the attitude error of the IMU, and the IMU of mission equipment such as an airborne EOTS, uses velocity matching based on the velocity from GPS/INS for aircraft navigation. In this paper, a method is presented to improve the transfer alignment performance of the airborne EOTS, by maneuvering aircraft and the mission equipment. First, the performance factor of the alignment was identified, as a heading error through the velocity matching model and simulation results. Then acceleration maneuvers and attitude changes were necessary, to correct the error. As a result of flight tests applied to an EOTS on a OOO aircraft system, the transfer alignment performance was improved as the duration time was decreased, by more than five times when the aircraft accelerated by more than 0.2g and the EOTS was moving until 6.7deg/s.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.391-397
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• 2017

Recently, digital image correlation (DIC) techniques have been used to measure dynamic deformation during tensile testing. The standard tensile test method measures the average displacement of the relevant specimen to calculate the true stress-strain curve. Therefore, the validity of the true stress curve is restricted to the stress incurred within the uniform stretching interval, i.e., the maximum stress corresponds to the starting point of the necking deformation. Alternatively, if DIC is used, the effective range of the strain and strain rate can be extended to the breaking point of the tensile specimen, because of the feasibility of measuring the local strain over the entire area of interest. Because of these advantages, many optical 3D measurement systems have been introduced and used in research and industry. However, the conventional 3D measurement systems are exceedingly expensive and time consuming. In addition, these systems have the disadvantage of a very large equipment size which makes their transport difficult. In this study, a 2D image correction method employing a 2D DIC measurement method in conjunction with a numerical analysis method is developed using a smartphone. The results of the proposed modified 2D DIC method yielded higher accuracy than that obtained via the 3D measurement equipment. In conclusion, it was demonstrated that the proposed 2D DIC and calibration methods yield accurate measurement results with low time costs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.104-112
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• 2015

Non-contact surface wave transmission (SWT) measurements are used to evaluate the depth of a surface-breaking crack in concrete slabs. The author propose a measurement model that includes an appropriate configuration of the source and receivers, and a transmission function for the given configuration. A series of numerical simulations using a 3D finite element model is used to obtain the transmission function. Then, validity of a proposed model is verified through experimental studies. Two air-coupled sensors are used to measured surface waves across surface-breaking cracks with varying depths from 0mm to 100mm with intervals of 10mm in a concrete slab ($1500{\times}1500{\times}180mm^3$) in laboratory. As a result, the proposed method is demonstrated as to be effective for charactering the depth of a surface-breaking crack in concrete bridge deck with an average error of 10%. A discussion on practical applications of the proposed method is also included in this article.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.5
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• pp.42-51
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• 2001

Vehicle detection is the basic of traffic monitoring. Video based systems have several apparent advantages compared with other kinds of systems. However, In video based systems, shadows make troubles for vehicle detection, especially active shadows resulted from moving vehicles. In this paper, a new method that combines background subtraction and edge detection is proposed for vehicle detection and shadow rejection. The method is effective and the correct rate of vehicle detection is higher than 98% in experiments, during which the passive shadows resulted from roadside buildings grew considerably. Based on the proposed vehicle detection method, vehicle tracking, counting, classification and speed estimation are achieved so that traffic parameters concerning traffic flow is obtained to describe the load of each lane.

• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.161-170
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• 2001

Vehicle detection is the basic of traffic monitoring. Video based systems have several apparent advantages compared with other kinds of systems. However, In video based systems, shadows make troubles for vehicle detection. especially active shadows resulted from moving vehicles. In this paper a new method that combines background subtraction and edge detection is proposed for vehicle detection and shadow rejection. The method is effective and the correct rate of vehicle detection is higher than 98(%) in experiments, during which the passive shadows resulted from roadside buildings grew considerably. Based on the proposed vehicle detection method, vehicle tracking, counting, classification and speed estimation are achieved so that traffic information concerning traffic flow is obtained to describe the load of each lane.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.45-46
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• 2021

본 논문에서는 제조산업의 제품 품질검사의 자동화를 위한 딥러닝 기법을 제안하고 모델의 성능 최적화를 위한 특징 추출 필터의 크기를 비교한다. 이미지 특징을 자동 추출할 수 있는 CNN을 사용하여 전문인력 없이 제품의 표면 결함을 검출하고 제품의 적합성을 판단할 수 있는 이미지 처리 알고리즘을 구축하고 산업 현장에 적용하기 위한 검증 지표로 검출 정확도와 연산속도를 측정하여 결함 검출 알고리즘의 성능을 확인한다. 또한 연산량에 따른 성능 비교를 위해 필터의 크기에 따른 CNN의 성능을 비교하여 결함 검출 알고리즘의 성능을 최적화한다. 본 논문에서는 커널의 크기를 다르게 적용했을 때 빠른 연산으로 높은 정확도의 검출 결과를 얻었다.