• 재활복지공학회논문지
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• 제4권1호
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• pp.15-21
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• 2010

초음파자극기의 오동작이나 부작용에 대한 예방으로 안전성 확보와 품질 향상이 필요하며 이를 위한 시판전의 시험검사나 시판후의 수거검사시에 안전성 및 성능평가를 위한 표준시험방법 이 필요하다. 본 논문에서는 초음파자극기에 대한 전기적 안전성 평가를 위한 필수시험과 성능평가를 위한 표준시험방법을 연구하였다.

• 한국철도학회논문집
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• 제14권1호
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• pp.57-65
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• 2011

교량을 주행하는 열차의 주행안전성과 승차감의 확보를 위해 Eurocode, 신간선 기준, 호남고속철도 설계지침 등에서는 교량의 연직변위, 연직가속도, 면틀림 등의 항목으로 제한하고 있다. 그러나 이와 같은 제한 기준은 교량 설계자의 편의를 위한 간접적인 방법이다. 또한 이와 같은 기준은 일반적인 경간(Eurocode의 경우 120m 이하)에 대한 제한 기준으로서, 이 이상의 장경간 교량의 경우에는 교량/열차 상호작용 해석 등에 의한 면밀한 검토를 제안하고 있다. 본 연구에서는 교량/열차 상호작용 해석을 수행하여 열차에서의 응답을 통해 교량 상을 주행하는 열차의 주행안전성 및 승차감을 직접적으로 평가하고자 하였다. 즉, 중앙경간 300m의 현수교를 주행하는 KTX 열차에 대하여 열차 내부의 가속도와 윤중감소율을 구해 평가하는 방법을 취하였다. 또한, 이동 열차하중과 지진하중이 동시에 작용할 경우를 고려한 교량/열차/지진 상호작용해석을 수행하여 지진 시의 응답을 평가하였다.

• 한국안전학회지
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• 제24권5호
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• pp.69-76
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• 2009

The estimation of costs from industrial accidents is very important because they have a serious effect on individuals, companies, and nation. The department of labor estimates the cost of accidents by using the "Heinrich" method. From that method, the scale of accident cost can be approximately computed, but accurate calculation of uninsured cost is not easy. Therefore, a better method of calculating uninsured cost caused by industrial accident is necessary. This study aimed to construct an estimation method of uninsured cost according to domestic circumstances. The results of this study are as follows: (1) This study derived applicable factors for quantitative estimation of industrial accident cost (2) This study made the equation that the calculation of each item of uninsured cost was possible (3) This study applied the uninsured cost by degrees of disaster to individual items (4) The subjects and types of occurrence in uninsured cost were analyzed and presented. Theses results will provide a basis for further researchers of uninsured cost.

• 대한안전경영과학회지
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• 제11권1호
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• pp.87-91
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• 2009

본 논문은 상대적으로 새로운 기법인 Parzen Density Estimation과 Multi-class SVM을 이용한 지능형 고장 탐색과 진단 방법을 제안하고 있다. 본 연구에서는 롤링 베어링을 대상으로 고장을 탐색하고 진단하기 위한 방법을 제안하는데 Parzen Density Estimation과 Multi-class SVM은 고장 클래스를 잘 표현할 수 있다. Parzen Density Estimation은 새로운 패턴 데이터의 거절과 알려진 데이터 패턴의 밀도의 평가에 의해 새로운 패턴을 찾아낼 수 있고, Multi-class SVM 기반의 방법은 여러 클래스의 고장을 support vector로 표현하여 고장 패턴을 찾아낼 수 있다. 본 연구에서는 실제의 다중 클래스를 가지는 롤링 베어링의 고장 데이터를 사용하여 고장 패턴을 탐색하는 과정을 보여주는데, 커널함수의 적절한 파라미터의 선택에 의한 Multi-class SVM 기반의 방법이 multi-layer perceptron이나 Parzen Density Estimation 방법보다 우수함을 입증한다.

• 자동차안전학회지
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• 제14권4호
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• pp.16-20
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• 2022

Accurate state estimation is important for autonomous driving. However, the estimation error increases in situations that a lot of longitudinal slip occurs. Therefore, this paper presents a vehicle state estimation method using an Extended Kalman Filter. The filter estimates the states of the host vehicle robust to wheel slip. It utilizes the measurements of the four-wheel rotational speeds, longitudinal acceleration, yaw-rate, and steering wheel angle. Nonlinear measurement model is represented by Ackermann Model. The main advantage of this approach is the accurate estimation of yaw rate due to the measurement of the steering wheel angle. The proposed algorithm is verified in scenarios of autonomous emergency braking (AEB), lane change (LC), lane keeping (LK) using an automated vehicle. The results show that the proposed algorithm guarantees accurate estimation in such scenarios.

• 한국BIM학회 논문집
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• 제6권2호
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• pp.29-38
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• 2016

Road bridges are deteriorating gradually, and it is forecasted that the number of road bridges aging over 30 years will increase by more than 3 times of the current number. To maintain road bridges in a safe condition, current safety conditions of the bridges must be estimated for repair or reinforcement. However, budget and professional manpower required to perform in-depth inspections of road bridges are limited. This study proposes an estimation model for safety rating of road bridges by analyzing the data from Facility Management System (FMS) and Yearbook of Road Bridges and Tunnel. These data include basic specifications, year of completion, traffic, safety rating, and others. The distribution of safety rating was imbalanced, indicating 91% of road bridges have safety ratings of A or B. To improve classification performance, five safety ratings were integrated into two classes of G (good, A and B) and P (poor ratings under C). This rearrangement was set because facilities with ratings under C are required to be repaired or reinforced to recover their original functionality. 70% of the original data were used as training data, while the other 30% were used for validation. Data of class P in the training data were oversampled by 3 times, and Repeated Incremental Pruning to Produce Error Reduction (RIPPER) algorithm was used to develop the estimation model. The results of estimation model showed overall accuracy of 84.8%, true positive rate of 67.3%, and 29 classification rule. Year of completion was identified as the most critical factor on affecting lower safety ratings of bridges.

• 한국컴퓨터정보학회논문지
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• 제22권11호
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• pp.49-55
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• 2017

Recently, for safety of people, there are proposed so many technologies which detect density of people at the specific place or space. The representative technology for crowd density estimation was using image analysis method from CCTV images. However, this method had a weakness which could not be used and which's accuracy was lower at the dark or smog space. Therefore, in this paper, to solve this problem, we proposed a user density estimation system at closed space using high frequency and smart device. The system send inaudible high frequencies to smart devices and it count the smart devices which detect the high frequencies on the space. We tested real-time user density with the proposed system and ten smart devices to evaluate performance. According to the testing results, we confirmed that the proposed system's accuracy was 95% and it was very useful. Thus, because the proposed system could estimate about user density at specific space exactly, it could be useful technology for safety of people and measurement of space use state at indoor space.

• 조명전기설비학회논문지
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• 제21권10호
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• pp.13-21
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• 2007

측정 결과와 분석을 바탕으로 전조등 밝기변화의 한계값과 운전자의 안전성을 고려한 평가 알고리즘을 개발하였다. 심리 평가에 의한 전조등 밝기변화의 한계값은 주관적 평가를 토대로 밝기 변화, 눈 깜박임, 불쾌감 등에 대한 값을 제시하였고, 또한, 시인성 측정에 의한 한계값은 차량을 장애물의 위협 없이 안전하게 정지하기 위한 한계값을 제시하였다.

• 드라이브 ㆍ 컨트롤
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• 제13권4호
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• pp.59-67
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• 2016

This paper proposes a model-prediction-based collision-avoidance algorithm for excavators for which the recursive-least-squares (RLS) estimation of the excavator's rotational inertia is used. To estimate the rotational inertia of the excavator, the RLS estimation with multiple forgetting and two updating rules for the nominal parameter and the forgetting factors was conducted based on the excavator-swing dynamics. The average value of the estimated rotational inertia that is for the minimizing effects of the estimation error was computed using the recursive-average method with forgetting. Based on the swing dynamics, the computed average of the rotational inertia, the damping coefficient for braking, and the excavator's braking angle were predicted, and the predicted braking angle was compared with the detected-object angle for a safety evaluation. The safety level defined in this study consists of the three levels safe, warning, and emergency braking. The analytical rotational-inertia-based performance evaluation of the designed estimation algorithm was conducted using a typical working scenario. The results of the safety evaluation show that the predictive safety-evaluation algorithm of the proposed model can evaluate the safety level of the excavator during its operation.

• 한국안전학회지
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• 제35권5호
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• pp.39-48
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• 2020

This study proposes a fast estimation method of dynamic reliability indices or failure probability for SDOF structure subjected to earthquake excitations. The proposed estimation method attempts to derive coefficient function for correcting dynamic effects from static reliability analysis in order to estimate the dynamic reliability analysis results. For this purpose, a total of 60 cases of structures with various characteristics of natural frequency and damping ratio under various allowable limits were taken into account, and various types of approximation coefficient functions were considered as potential candidate models for dynamic effect correction. Each reliability index was computed by directly performing static and dynamic reliability analyses for the given 60 cases, and nonlinear curve fittings for potential candidate models were performed from the computed reliability index data. Then, the optimal estimation model was determined by evaluating the accuracy of the dynamic reliability analysis results estimated from each candidate model. Additional static and dynamic reliability analyses were performed for new models with different characteristics of natural frequency, damping ratio and allowable limit. From these results, the accuracy and numerical efficiency of the optimal estimation model were compared with the dynamic reliability analysis results. As a result, it was confirmed that the proposed model can be a very efficient tool of the dynamic reliability estimation for seismically excited SDOF structure since it can provide very fast and accurate reliability analysis results.