• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.339-349
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• 2006

The purpose of this study is to investigate the seismic behavior of circular reinforced concrete bridge piers with confinement steel and to provide the data for developing improved seismic design criteria. Fourteen circular reinforced concrete bridge piers were tested under a constant axial load and a cyclically reversed horizontal load. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. In the companion paper, the proposed numerical method for the seismic performance assessment of circular reinforced concrete bridge piers with confinement steel is verified by comparison with experimental results.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.822-831
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• 2021

Although programs have been developed to evaluate the risk of dragging anchors, it is practically difficult for VTS(vessel traffic service) operators to calculate and evaluate these risks by obtaining input factors from anchored ships. Therefore, in this study, the gross tonnage (GT) that could be easily obtained from the ship by the VTS operators was set as an independent variable, and linear and nonlinear regression analyses were performed using the input factors as the dependent variables. From comparing the fit of the polynomial model (linear) and power series model (nonlinear), the power series model was evaluated to be more suitable for all input factors in the case of container ships and bulk carriers. However, in the case of tanker ships, the power supply model was suitable for the LBP(length between perpendiculars), width, and draft, and the polynomial model was evaluated to be more suitable for the front wind pressure area, weight of the anchor, equipment number, and height of the hawse pipe from the bottom of the ship. In addition, all other dependent variables, except for the front wind pressure area factor of the tanker ship, showed high degrees of fit with a coefficient of determination (R-squared value) of 0.7 or more. Therefore, among the input factors of the dragging anchor risk assessment program, all factors except the external force, seabed quality, water depth, and amount of anchor chain let out are automatically applied by the regression analysis model formula when only the GT of the ship is provided.

• Journal of Korean Society of Transportation
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• v.28 no.1
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• pp.157-163
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• 2010

It is well known that weather conditions are closely related with the number and severity of traffic accidents. At present, installation of safety countermeasures including systems is common approach to reduce the damage of traffic accidents at expressways. In this study, the differences of causation factors to influence traffic accidents considering road alignment characteristics and weather conditions. In order to identify the relationship between road and weather conditions, discriminant analysis has been performed with 500 traffic accident data at expressways. Weather conditions are divided into several categories such as snow, sunny, rain, fog, and cloud. Also, road conditions such as types of pavements, grades are analyzed. As the results, major impacting road conditions to traffic accidents are concrete pavement and 3% or more down grades. In these road conditions, visible distance will be reduced and actual braking distances will be increased. This study shows that the expressway sections under concrete pavement and down grades should be more cautious than other sections. It also shows that fog condition is the mose dangerous situation in terms of traffic accidents.

• Journal of the Korean Data and Information Science Society
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• v.27 no.5
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• pp.1215-1224
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• 2016

Climate information of the high resolution grid units is an important factor to explain the phenomenon in a variety of research field. Statistical linear interpolation models are computationally inexpensive and applicable to any climate data compared to the dynamic simulation method at regional scales. In this paper, we considered four different linear-based statistical interpolation models: general linear model, generalized additive model, spatial linear regression model, and Bayesian spatial linear regression model. The climate variable of interest was the daily mean temperature, where the spatial variability was explained using geographic terrain information: latitude, longitude, elevation. The data were collected by weather stations in January from 2003 and 2012. In the sense of RMSE and correlation coefficient, Bayesian spatial linear regression model showed better performance in reflecting the spatial pattern compared to the other models.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.27-33
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• 2008

Damping behavior of various soil models are compared to actual observed soil damping behavior. Several nonlinear soil models were used and evaluated to predict damping behavior of soils. A combined damping model incorporating both nonvisous and hysteretic damping behavior was developed to better approximate soil behavior. The strengths and limitations of this model are discussed.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.182-185
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• 2001

본 연구에서는 쾌, 불쾌, 긴장, 이완의 네 가지 상상을 통해 감성의 변화를 유도하였고, 생리 신호 분석을 통해 감성의 변화를 변별하고자 하였다. 20명의 피험자를 대상으로 네 가지 상상을 각각 30초씩 수행하게 하면서 EEG, ECG, GSR, PPG, RSP, Skin-Temperature를 각각 측정하였고 측정 종료 후 주관적 평가를 실시하였따. 주관적 평가 분석 결과, 피험자는 뚜렷이 구별되는 네 가지 상상을 한 것으로 나타났고, 쾌도는 “쾌 > 이완, 긴장 > 불쾌” 상상 순서의 3단계로, 긴장도는 “긴장 > 불쾌, 쾌 > 이완” 상상 순서의 3단계로 뚜렷이 구별되었다. EEG 분석 결과에서는 쾌와 불쾌, 쾌와 이완 상상 사이에서만, 자율신경계 반응 역시 약 2.5 단계의 긴장도 감성 변별이 가능하여 정확한 3단계의 감성 변별에는 어려움이 있었다. 그러나 향후 비선형 분석법을 적용하고 피험자 수를 증가시킨다면 생리 신호 분석을 통한 감성 변별 민감도를 증가시킬 수 있을 것으로 사료된다. 본 연구로부터 쾌/불쾌와 긴장/이완의 2차원의 감성 영역의 각 축을 EEG와 자율신경계의 생리 신호를 통해 변별할 수 있다는 가능성을 확인하였다.

• International Journal of Highway Engineering
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• v.18 no.4
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• pp.63-68
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• 2016

PURPOSES : The nonlinear model of fatigue cracking is typically used for determining the maintenance period. However, this requires that the model parameters be known. In this study, the particle filter (PF) method was used to determine various statistical parameters such as the mean and standard deviation values for the nonlinear model of fatigue cracking. METHODS : The PF method was used to determine various statistical parameters for the nonlinear model of fatigue cracking, such as the mean and standard deviation. RESULTS : On comparing the values obtained using the PF method and the least square (LS) method, it was found that PF method was suitable for determining the statistical parameters to be used in the nonlinear model of fatigue cracking. CONCLUSIONS : The values obtained using the PF method were as accurate as those obtained using the LS method. Furthermore, reliability design can be applied because the statistical parameters of mean and standard deviation can be obtained through the PF method.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1513-1514
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• 2008

다 개체 동종 시스템의 분산 편대 추종 제어는 최근 몇 년간 많은 연구가 이루어져 왔다. 이러한 관심은 군사 분야, 모발 센서 네트워크, 지능형 교통 시스템과 같은 흥미롭고 새로운 응용 사례가 대두됨에 따라 집중되었다. 분산 편대 제어는 여러 가지 이론과 방법으로 연구되어 왔는데 대부분의 경우 여러 동종 시스템의 상호 연결성을 토대로 라플라스 인접 행렬의 성질로 설명하고 있다. 이러한 접근법은 합의 문제와 동기화 문제와도 관계가 있는데 이 경우 편대 제어의 경우와 유사한 방식으로 안정도를 설명하며 설계 고려 사항을 도출한다. 본 논문에서, 우리는 분산된 방법으로 여러 대의 동종 비선형 시스템을 다루며 이 시스템들은 시간에 대해 부드럽게 변하는 상대 기준 위치에 따라 편대를 이룰 수 있고 또한 전체 그룹은 모든 방향으로 자유롭게 움직이는 것이 가능하다. 우리의 주요 목표는 위와 같은 편대 추종 제어의 안정도를 해석하고 제어기를 설계하는 것이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2833-2842
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• 1996

This paper is to practice optimal rigidity design by the strain energy density estimation method for static buckling and sizing design sensitivity analysis for dynamic buckling of a nonlinear vehicle frame structure from those results. Using these sizing design sensitivity resutls, an optimization of a nonlinear vehicle frame structure with dynamic buckling constraint is carrried out with the graient projection method.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.1-1
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• 2000

본 논문에서는 3축이 연성되어 비선형 운동 방정식으로 표현되는 3축 안정화 인공위성 시스뎀에 입릭외란과 시스템의 불확실성이 존재할 경우에도 자제 정밀도를 유지하는 제어기를 설계한다. 비선헝 운동 방정식으로 표현되는 운동 방정식을 선형화하고 PID제어기를 구성하였다 선형화에 의한 시스템의 불확실성과 입력 외란을 신경회로망으로 추정하여 외란의 엉향을 제거하도록 구성된 PR제어기의 제어입력을 수정한다 수정된 제어입력은 외란을 상쇠시켜 시스템 출력에서 외란의 효과를 제거하게 된다. 신경회로망은 제어입력과 시스템 출력, 기준 운동 방정식간의 관계를 이용하여 외간과 시스템의 불확실성을 추정하며, 역전파 알고리즘을 사용한 학습 알고리즘으로 신경 회로망을 교육한다. 제안된 신경회로망을 이용한 외란 제거 제어기는 시뮬레이션을 통하여 자세 정밀도의 향상을 검증한다