• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.109-118
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• 2005

A functional suspension model is proposed as a kinematic describing function of the suspension that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center and steering rack displacement. The relative velocity and acceleration of the wheel is represented in terms of first and second derivatives of the kinematic describing function. The system equations of motion for the full vehicle dynamic model are systematically derived by using velocity transformation method of multi-body dynamics. The comparison of field test results and simulation results of the ADAMS/Car demonstrates the validity of the proposed functional suspension modeling method. This model is suitable for real-time vehicle dynamics analysis.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1151-1152
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• 2023

본 연구에서는 전동 차량의 자율주행 기능 구현을 위한 방법을 제시한다. 주요 구성 요소로는 카메라, PC, 아두이노, 모터드라이브, 가변저항 등이 사용되었다. 카메라를 통해 데이터를 수집한다. YOLOPv2 lane detection 딥러닝 모델을 사용하여 차선을 탐지하고, 후처리 과정을 통해 주행 경로를 정확히 인식한다. RANSAC 알고리즘을 활용하여 outlier 에 강건한 2 차 함수 회귀를 수행하고, 이를 바탕으로 주행 중 필요한 정보를 파악한다. 이러한 정보를 바탕으로 차량의 조향각을 조절하여 안전하고 효율적인 자율 주행을 구현하였다.

• The Journal of the Acoustical Society of Korea
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• v.29 no.2
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• pp.118-124
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• 2010

In this paper, design parameters of dynamic vibration absorber, which is used to reduce bending vibrations of a vehicle drive line, is optimized. For obtaining the correct dynamic response characteristics, a flexible-body drive line is made by applying the flexibility data extracted from vibration analysis of propeller shafts to the drive line dynamic model. Inner tube mass, rubber stiffness and rubber damping coefficient of the dynamic vibration absorber are taken as design parameters for optimization. To minimize the vertical acceleration of the drive line, a second-order regression equation of the objective function is generated by performing the central composite experimental design with 3 factors, 2 levels and 15 test runs. And the design parameters of the dynamic vibration absorber are determined by using optimization program. The vehicle model with optimized dynamic vibration absorber reduces the vertical acceleration peak of the drive line by 17.1 % in compared with the initial model.

• The KIPS Transactions:PartD
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• v.10D no.1
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• pp.45-56
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• 2003

In the wireless environment, according to the development of technology, which is able to obtain location information of spatiotemporal moving object, the various application systems are developed such as vehicle tracking system, forest fire management system and digital battle field system. These application systems need the data model, which is able to represent and process the continuous change of moving object. However, if moving objects are expressed by a relational model, there is a problem which is not able to store all location information that changed per every time. Also, existing data models of moving object have a week point, which constrain the query time to the time that is managed in the database such as past or current and near future. Therefore, in this paper, we propose a data model, which is able to not only express the continuous movement of moving point and moving region but also process the operation at all query time by using shape-change process and location determination functions for past and future. In addition, we apply the proposed model to forest fire management system and evaluate the validity through the implementation result.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.624-627
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• 2010

최근 자동차 업계서는 차량의 온실가스 배출량을 줄이고 연비를 개선시킬 수 있는 방법 중의 하나로 경량화 소재를 사용하여 차체의 중량을 줄이는 연구가 활발히 진행 중에 있다. 특히 알루미늄 합금의 경우 기존 강재에 비해 비중이 낮아 가볍고 부식에 대한 저항성이 높아 많이 사용되어지고 있는 추세이다. 본 연구에서는 먼저, 저입열 용접공정을 적용하여 용접 변수와 토치의 각도에 따른 인장강도 특성을 비교하여 적정 용접 범위를 산정하였으며, 인장강도와 비드형상의 관계를 다중 회귀 분석을 이용하여 비드 예측 회귀 모델을 제시하였다. 또한 호감도 함수를 적용한 반응표면분석법을 이용하여 자동차 생산 현장에서 겹치기 용접 이음부의 강건한 용접 품질을 가질 수 있는 최적용접 공정 조건을 도출할 수 있는 효과적인 방법을 제안하고자 한다.

• Journal of KIISE:Databases
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• v.31 no.5
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• pp.479-491
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• 2004

Location information of mobile objects is applied to vehicle tracking, digital battlefields, location based services, and telematics. Their location coordinates are periodically measured and stored in the application systems. The linear function is mainly used to estimate the location information that is not in the system at the query time point. However, a new method is needed to improve uncertainties of the location representation, because the location estimation by linear function induces the estimation error. This paper proposes an application method of the cubic spline interpolation in order to reduce deviation of the location estimation by linear function. First, we define location information of the mobile object moving on the two-dimensional space. Next, we apply the cubic spline interpolation to location estimation of the proposed data model and describe algorithm of the estimation operation. Finally, the precision of this estimation operation model is experimented. The experimentation comes out more accurate results than the method by linear function, although the proposed location estimation function uses the small amount of information. The proposed method has an advantage that drops the cost of data storage space and communication for the management of location information of the mobile objects.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.345-355
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• 2007

During winter, the CWR (continuous welded rail) may be broken when a temperature drop below the neutral level changes the axial force, causing tensile fracture and creating a rail gap. The passage of a train on a rail with an open gap may lead to very costly derailments. In this paper, the use of a track-and-train-coupled model whose rail has an open gap is proposed for dynamic interaction analysis. Linear track and train systems were coupled in this study by a nonlinear Herzian contact spring, and the complete system matrices of the total track-train system were constructed. Moreover, the interaction phenomenon considering the presence of an open gap in the rail was toughly defined by assigning the irregularity functions between the two sides of the gap. Time history analysis, which has an iteration scheme such as the Newmark-$\beta$ method (based on the Modified Newton-Raphson methods), was conducted to solve the nonlinear equation. .Finally, numerical studies were conducted to assess the effect of the various parameters of the system when applied to various speeds, open-gap sizes, and support stiffnesses of the rail.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.197-199
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• 2010

우리는 CCTV 카메라 영상에서 도로상에 통행중인 차량의 이동영역이 시정에 따라 달라진다는 점에 착안하여 이동영역을 추출하고 이를 이용하여 가시거리를 계산하는 시정 측정 장치를 개발하고 있으며, 이 때 가장 중요한 것은 어떻게 추출된 이동영역을 이용하여 시정측정값을 계산할 것인가 하는 것이다. 이동영역이 추출된 이미지에서 이동영역의 상단라인을 나타내는 가시선의 위치와 시정거리와는 일반적으로 지수함수의 관계를 가지게 된다. 본 논문에서는 가시선의 위치를 이용한 시정측정을 위해 도로의 표면과 카메라의 기하학적인 관계를 설명하고 비선형 곡선적합 방법에 기초한 도로모델과 이를 이용한 도로시정 측정과 실제 적용방안을 제시하고 구현한 결과를 보인다.

• The Journal of the Acoustical Society of Korea
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• v.18 no.5
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• pp.78-82
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• 1999

This paper is a study on weighted cepstrum used broadly for robust speech recognition. Especially, we propose the weighted function of asymmetric glottal pulse shape. which is used for weighted cepstrum extracted by PLP(Perceptual Linear Predictive) based on auditory model. Also, we analyze this glottal weighted cepstrum from the glottal pulse of glottal model in connection with the cepstrum. And we obtain speech features analyzed by both the glottal model and the auditory model. The isolated-word recognition rate is adopted for the test of proposed method in the car moise and street environment. And the performance of glottal weighted cepstrum is compared with both that of weighted cepstrum extracted by LP(Linear Prediction) and that of weighted cepstrum extracted by PLP. The result of computer simulation shows that recognition rate of the proposed glottal weighted cepstrum is better than those of other weighted cepstrums.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.52-59
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• 2015

In the conventional model for the prediction of the railway environmental noise, one used an empirical formula of the total noise level at specific distances. Only a function of the distance to the source was also used to calculate the noise level near the railway bridges. However, the noise varies depending on the position of the receiver as well as the distance from the source especially at concrete bridges. In this paper, a noise propagation model in the railway concrete bridge was derived by considering the diffraction at the bridge deck and the ground effect and applying the ISO 9613-2 noise propagation model. We compared the predicted and measured values of environmental noise at a high-speed railway bridge, and it was confirmed that this prediction model gives relatively small errors.