• 융복합기술연구소 논문집
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• 제4권1호
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• pp.33-35
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• 2014

Investigation of flow characteristics behind a edged backward facing step is important for selecting appropriate positions of building constructions in the desert area. In the present study, the effect of edge angles on the flow characteristics is investigated using a commercial software CFD-ACE+. When the edge angle is less than 30 degree, reattachment length decreases, whereas when the edge angle is larger than 30 degrees, reattachment angle increases. It can be concluded that the flow patterns behind an edged backward facing step is classified as the two, streamlined and bluffed bodies. Appropriate edge angles have an effect of increasing the momentum toward the wall, which can reduce the reattachment length. It can be said that present results can be utilized for diverse industrial applications that includes the backward facing step.

• 한국산업융합학회 논문집
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• 제22권5호
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• pp.575-582
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• 2019

Advanced driving assist system can support safety of driver and passengers which may require vehicle dynamics states as well as road geometry. It is essential to have in real-time estimation of related variables and parameters. Among the road geometry parameters, road slope angle which can not be measured is essential parameter in pose estimation, adaptive cruise control and others on sag road. In this paper, Kalman filter based method for the estimation of the vehicle dynamics and road slope angle using a nonlinear vehicle model is proposed. It uses a combination of Kalman filter as Cascade Extended Kalman Filter. CEKF uses measured vehicle states such as yaw rate, longitudinal/lateral acceleration and velocity. Unknown vehicle parameters such as center of gravity and inertia are obtained by 2 D.O.F lateral model and experimentally. Simulation and Experimental tests conducted with commercialized vehicle dynamics model and real-car.

• 한국군사과학기술학회지
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• 제25권3호
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• pp.231-238
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• 2022

Mine detection has been mainly studied with images of the forward-looking sonar. Forward-looking sonar assumes the propagation path of the sound wave as a straight path, creating the surrounding images. This might lead to errors in the detection by ignoring the refraction of the sound wave. In this study, we propose a mine localization method that can robustly identify the location of mines in an underwater environment by considering the refraction of sound waves. We propose a method of estimating the elevation angle of arrival of the target echo signal in a single receiver, and estimate the mine location by applying the estimated elevation angle of arrival to ray tracing. As a result of simulation, the method proposed in this paper was more effective in estimating the mine localization than the existing method that assumed the propagation path as a straight line.

• ETRI Journal
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• 제37권3호
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• pp.617-625
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• 2015

In this paper, a steering control system for the path tracking of autonomous vehicles is described. The steering control system consists of a path tracker and primitive driver. The path tracker generates the desired steering angle by using the look-ahead distance, vehicle heading, and a lateral offset. A method for applying an autonomous vehicle to path tracking is an advanced pure pursuit method that can reduce cutting corners, which is a weakness of the pure pursuit method. The steering controller controls the steering actuator to follow the desired steering angle. A servo motor is installed to control the steering handle, and it can transmit the steering force using a belt and pulley. We designed a steering controller that is applied to a proportional integral differential controller. However, because of a dead band, the path tracking performance and stability of autonomous vehicles are reduced. To overcome the dead band, a dead band compensator was developed. As a result of the compensator, the path tracking performance and stability are improved.

• 한국운동역학회지
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• 제31권2호
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• pp.119-125
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• 2021

Objective: The purpose of this study was to identify the effect of dynamic postural balance control against tilting platform between golfers and non-golfers. Method: 24 golfers and 26 non-golfers were participated. Eight motion capture cameras, two force plates, and one dynamic balance control platform were used for sensory perception test. It was performed two-way repeated ANOVA with a Bonferroni adjustment at a significant level of a 0.05. Results: Golfers' perception ability was higher than non-golfer according to slope. the CoP, time, angle variables were indicated main effect and interaction effect between golfer and non-golfer. Conclusion: It was known that golfer's proprioception perception ability was higher than non-golfers. Repeated practice such as shots and putting on the uneven ground might improve their balance control.

• ETRI Journal
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• 제31권3호
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• pp.321-323
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• 2009

A wideband beamforming algorithm for estimating the azimuth angle, elevation angle, velocity, and range using a planar phased radar array with antenna switching is proposed. It uses the time-variant steering vector model. Simulation results illustrating the performance of the proposed beamformer are presented.

• 대한치과재료학회지
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• 제44권4호
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• pp.329-336
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• 2017

본 연구는 맞춤형 지대주 (custom abutment) 설계 시 CAD 프로그램 내에서 선택된 수렴 각 그리고 곡률 반경 값 사용에 따른 가공 정확도를 평가하고자 한다. 치과용 CAD를 기반으로 10개의 맞춤형 지대주를 설계하였다. 제작된 맞춤형 지대주를 정밀 접촉식 스캐너를 이용하여 한 개의 시편을 10회 반복 스캔하였다. 스캔 된 맞춤형 지대주의 데이터는 "Test STL" 파일로 지정하여 저장하였다. Geomagic studio 소프트웨어를 이용하여 각 "Test STL" 파일과 동명 번호로 지정하여 저장된 CAD-reference-model STL 파일 (CRM)과 중첩하였다. 실험 결과에서 A8 군(수렴 각 $8^{\circ}$) 군은 A4 군(수렴 각 $4^{\circ}$) 보다 낮은 오차 수치를 나타났다. 또한, 곡률 반경 값이 높을 수록 맞춤형 지대주의 Top 그리고 chamfer 부위에 오차가 적게 나타냈다(p< 0.05). 전체적으로, 맞춤형 지대주 설계 시 곡률 반경 값은 가공 정확도에 영향을 미치는 것을 알 수 있었다.

• 한국융합학회논문지
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• 제10권1호
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• pp.155-161
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• 2019

복합소재는 기존의 일반적인 소재보다 내구성과 기계적 성질들이 뛰어난 경량 소재이다. 본 연구에서는 경량 복합소재에 주목하여, 접착제를 이용하여 접착한 CFRP 접착구조물의 정적 파괴 특성을 조사하고자 했고 적층 각도를 변수로 한 CFRP 이중외팔보 시험편을 설계하여 정적 파괴 해석을 수행하였다. 본 연구를 위하여 설계된 CFRP 이중외팔보 시험편들의 적층각도들은 각각 $30^{\circ}$와 $45^{\circ}$, $60^{\circ}$이며, 연구 결과로서는 적층 각도 $45^{\circ}$인 시험편이 가장 $30^{\circ}$, $60^{\circ}$의 적층 각도를 가진 시험편들보다 더 좋은 내구성을 보였으며, $30^{\circ}$의 적층 각도를 가진 시험편이 모든 시험편 중에서 내구성이 가장 취약한 것을 확인할 수 있었다. 이와 같은 본 연구 결과를 통하여 적층 각도 별 CFRP 접착구조물의 파손데이터를 확보할 수 있었으며, 본 연구결과를 토대로 얻은 접착 계면의 파손데이터를 활용함으로서 실생활에서의 기계나 구조물에 융합하여 그 미적 감각을 나타낼 수 있다.

• 한국융합학회논문지
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• 제9권12호
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• pp.175-180
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• 2018

본 연구에서는 CFRP를 적층각도 45도로 제작하고 구조용 접착제로 접착된 TDCB(Tapered Double Cantilever Beam) 시험편을 CATIA로 설계를 하였고, 유한요소해석 프로그램인 ANSYS를 이용하여 해석을 진행하였다. 연구 모델은 영국 산업 및 ISO 표준에 기초하여 설계하였으며, 모델 형상의 각도에 따라서 형상계수(m)를 변수로 설정하였다. 본 논문의 연구 결과로서, 모든 해석 시험편들 중에서 $4^{\circ}$ 인 경사 각도를 가진 시험편에서 최대 변형량은 12.628mm로 가장 높았으며 $8^{\circ}$에서 12.352mm으로 가장 낮은 값을 각각 보였다. 또한, 최대등가응력은 그 각도가 $6^{\circ}$에서 9210.3MPa가장 높았으며 $8^{\circ}$에서 4800.5MPa로 가장 낮은 값을 각각 보였다. 본 연구 결과를 통하여 CFRP로 제작된 적층각도를 가진 TDCB 구조물의 파손데이터를 확보할 수 있었으며, 본 연구결과를 토대로 얻은 CFRP로 접착된 TDCB 구조물의 파손데이터를 활용함으로서 실생활에서의 기계나 구조물에 융합하여 그 미적 감각을 나타낼 수 있다.

• 전기학회논문지
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• 제67권2호
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• pp.239-247
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• 2018

Adaptive Beamforming (ABF) algorithm, which is a typical jammer suppression algorithm, guarantees the performance on the assumption that the jamming characteristics of the TDS (Training Data Sample) are stationary, which are obtained immediately before and after transmitting the pulse signal. Therefore, effective jammer suppression can not be expected when the jamming characteristics are non-stationary. In this paper, we propose a new jammer suppression algorithm, of which power spectrum fluctuates fast. In this case, we assume that the location of the jammer station is fixed during the processing time. By applying the MPM (Matrix Pencil Method) to the jamming signal in TDS, we can estimate jammer parameters such as power and incident angle, of which the power will vary fast in time or range bins after TDS. Though we assume that the jammer station is fixed, the estimated jammer's incident angle has an error due to the noise, which degrades the performance of the jammer suppression as the jammer power increases fast. Therefore, the jammer's incident angle should be re-estimated at each range bin after TDS. By using the re-estimated jammer's incident angle, we can construct new covariance matrix under the non-stationary jamming environment. Then, the optimum weight for the jammer suppression is obtained by inversing matrix estimation method based on the matrix projection with the estimated jammer parameters as variables. To verify the performance of the proposed algorithm, the SINR (signal-to-interference plus noise ratio) loss of the proposed algorithm is compared with that of the conventional ABF algorithm.