• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.3
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• pp.149-155
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• 2022

This paper proposes a method for estimating the road surface condition and tilt angle using an inertial measurement unit (IMU) to improve the safety in the use of mobility aids for the elderly. The measurements of the accelerometers of the IMU usually include the accelerations caused by not only the gravitational force but also linear and rotational motions. Thus, the gravitational accelerations are first extracted using several physical constraints and then incorporated into the Kalman filter to estimate the tilt angle. In addition, because the magnitudes of the accelerations produced by the rotational motions (roll and pitch motions) vary with the road surface condition, a criterion based on such accelerations is presented to classify the condition of the road surface. The obtained road surface condition and tilt angle are finally combined to provide the safety information (e.g., safe, warning, and danger) for the user to improve the walking safety. Experiments were carried out and the results showed that the proposed method can provide the condition of the road surface, the tilt of the road surface, and the safety information correctly.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.4
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• pp.181-199
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• 2022

This study presented a methodology for evaluating the performance of the lane departure warning system was derived by calculating the relationship between the behavior information of the car and the location of the high-precision map using a high-precision map. The evaluation criteria of the mood and lane departure warning system for the installation of road markings in Korea were analyzed, a high-precision map was constructed to meet the evaluation criteria, and an evaluation system was constructed to verify the proposed methodology. Evaluation of lane departure warning systems using high-precision maps can be quantified and applied to various road environments through accurate location-based comparative analysis and reduced manual post-processing work time to confirm evaluation results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.29-35
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• 2022

When a vehicle is driven off a road surface, the deformations of the road surface and tire are combined. Consequently, the dynamic behavior of wheel movement becomes difficult to predict and control. Herein, we propose a tire test bed to capture the dynamic behavior of tires moving on sand and soil. Based on this study, it is discovered that the slip rate can be controlled, and the vertical force can be measured using a load cell. The test results show that this test bed can be useful for capturing the dynamic behavior of the tire and validating dynamic simulations. In fact, the tire test bed developed in this study can be used to verify the results of computer simulations. In addition, it can be used for basic experiments pertaining to the speed control of unmanned autonomous vehicles.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.101-109
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• 1995

Axisymmetric and quasi-static finite element analysis of an inflated tire rotating with constant angular velocity and contact to road has been performed. Centrifugal force effect was added to load stiffness matrix and equation of effective material properties were calculated by the Halpin-Tsai formulation. In this report, radial truck/bus tire was analyzed. It was inflated and rotated at speeds up to 140 km/h. Then, contact problem was performed to calculate stress-strain field of tire wiht flat rigid road under the load due to the self-weight of a vehicle. Significant changes of stress-strain field of tire were observed in the finite element analysis. Shear stress, strain and strain energy density were rapidly increased at the dege of #2 belt at freely rotating state. This concentrated stress and strain made belt edge sparation. Under the condition of flat riged road contact, strain energy density of #2 belt, carcass turn-up part were concentrated and bigger values than only freely rotation state. Therefore, dynamic behaivor of tire has to considered as design factors which are affected to belt edge separation and bead breakage.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.353-353
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• 2020

기후변화에 적응하기 위해 많은 나라들이 수자원 관리 전략을 마련하고 있으며, 대체 수자원 활성화 방안에 관심을 기울이고 있다. 본 연구에서는 대체 수자원 활성화 방안 중 빗물 저류지의 용량 결정 방법을 제시하고자 한다. 빗물 저류지의 용량을 결정하기 위해 메타 휴리스틱 방법 중 하나인 입자 군집 최적화(particle swarm optimization; PSO)를 선정하였다. 이는 기존 실제 설계에 사용되고 있는 시행착오법보다 시간을 단축시킬 수 있다. 최적화 모형은 python의 pyswarm package를 이용해 구성하였다. 모형의 입력자료는 저류지 유입량과 목표 공급량, 목표 보장률이고, 목적함수는 빗물 저류지 용량의 최소화이다. 제약조건은 모의된 보장률이 목표 보장률 이상을 달성하는 것이다. 여기서, 보장률은 전체 모의 기간 중 목표 공급량을 공급한 기간의 비율이다. 제시한 방법론의 적용성을 검토하기 위해 실제 저류지가 설계된 인천의 청라지구 1공구를 선정하여 적용하였다. 최적화 모형의 입력 유입량은 SWMM으로 산정된 1995년부터 2004년까지의 유출량이며, 목표 공급량은 실제 설계에 활용된 용수 목적별 요구 수량이다. 여기서 용수 목적별 요구 수량은 대상지역의 노면 청소수, 화장실 세정수, 호수 유지수 등이다. 산정 결과 계산 시간은 약 30초 소요되며, 목표 보장률을 만족하는 저류지 용량이 결정되었다. 본 연구에 제시한 방법은 제약조건이 추가되어도 기존 시행착오법에 비해 간편함을 확인하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.289-294
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• 2010

It is well known that rumble strips contribute to reduce traffic accidents. The present paper provides the reduction effect of traffic accidents under specific highway geometrics after rumble strip installation. Traffic accidents on freeway sections before and after rumble strip installation are compared when conditions of the highway geometric characteristics such as horizontal, vertical geometrics are given. It is shown that rumble strips are effective under highway geometric conditions of down slopes or right curvatures. It is also shown that rumble strips are still effective with shorter length of installation.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.359-359
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• 2022

빈번하게 발생되는 설계빈도 이상의 국지성 호우로 도시지역의 침수피해가 매년 증가하고 있고 특히 저지대의 경우 우수의 집중 및 하수관거의 통수능 부족으로 인한 우수의 배수 불량으로 다른 지역에 비해 침수피해의 규모가 크게 나타나고 있다. 매년 반복되는 피해를 저감하기 위하여 국가 및 지자체에서는 노후관거 개량 및 통수능 확보를 위한 하수관거 신설 등 다양한 방법을 동원하고 있으나 하수관거 개량 및 신설 또는 지하저류조 설치와 같은 사업들은 많은 예산이 필요하여 지자체의 규모에 따라 예산확보가 어려울 수 있고 해당 사업을 완료하기 위한 사업기간이 오래 걸리므로 즉각적인 효과를 기대하기 어려운 실정이다. 따라서 기존 침수저감을 위한 시설을 설치하기 위한 사업에 비해 예산이 적게 소모되며, 큰 설치부지를 요구하지 않는 유출저감시설이 필요하다고 판단된다. 본 연구에서는 도로부의 노면수를 배수하기 위한 시설인 측구를 우수의 저류를 위한 저류조로 활용한 측구 저류조 개념을 이용하여 도시지역에서 침수저감을 위한 적정규모 산정을 위한 연구를 진행하였다. 빈도 30년의 강우를 적용하여 일반적인 지하저류조를 설치하였을 경우와 측구 저류조를 설치하였을 때의 침수저감효과를 비교하고 지하저류조와 비슷한 저감효과를 나타내기 위한 적정규모 산정과 측구 저류조의 배치방법을 제시하고자 한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.314-321
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• 2024

Low road lighting is a lighting device that complements the shortcomings of existing pillar-type street lights. It is a lighting device that emits light from the side of the road surface and adjusts the luminance of the road surface like a light carpet. In this paper, to achieve full commercialization, we analyzed the luminance of the installed road surface and studied whether lighting could replace existing road lighting. In this study, the LMK (Luminance Measurement Camera) LABSOFT program was used to measure and analyze the surface luminance of road lighting, and the RELUX program was used to evaluate and analyze the simulation performance to determine light-based lighting conditions. A study was conducted to determine whether replacing pillar-type road lighting with low-level road lighting in a real environment would ensure comfortable and safe night vision for drivers at night.

• Journal of Environmental Science International
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• v.33 no.2
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• pp.169-178
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• 2024

This study aimed to investigate the impact of pavement design changes on user perceptions, with the objective of enhancing safety in urban streetscape. A total of 72 participants were recruited, and the study focused on alleyways in areas with a high risk of crime. Employing the Semantic Differential (SD) methodology, an assessment was conducted to gauge participants' perceptions of three different pavement types (A-type, B-type, C-type) as well as the existing pavement. The results indicated that the C-type pavement, characterized by vibrant and harmonious color palettes and patterns, elicited the highest levels of perceived safety, comfort, and openness among users. This signifies that physical environmental improvements through color design can mitigate the feelings of insecurity and foster emotional stability. Therefore it is recommended to implement various color schemes and pattern designs to road surface for enhancing user safety in high-risk urban areas.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.112-121
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• 1999

An MR(Magneto-Rheological) fluids damper is designed and applied to vibration suppression of a 1/4 car model. The damping constant of MR damper changes according to input current which is controlled in a semi-active way. Several control algorithms are compared in simulations and experiments. The advantage of the proposed Frequency shaped LQ control is that passenger comfort is emphasized in the range of 4~8Hz and driving safety is emphasized around the resonance frequency of unsprung mass.