• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2018년도 공동국제학술발표회
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• pp.9-9
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• 2018

• 제어로봇시스템학회논문지
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• 제19권10호
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• pp.941-946
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• 2013

In this paper, an enhanced method for attitude determination is proposed for systems using an IMU (Inertial Measurement Unit). In attitude determination with IMU, it is generally assumed that the IMU can be located in the center of gravity on the vehicle. If the IMU is not located in the center of gravity, the accelerometers of the IMU are disturbed from additive accelerations such as centripetal acceleration and tangential acceleration. Additive accelerations are derived from the lever arm which is the distance between the center of gravity and the position of the IMU. The performance of estimation errors can be maintained in system with a non-zero lever arm, if the lever arm is estimated to remove the additive accelerations from the accelerometer's measurements. In this paper, an estimation using Kalman filter is proposed to include the lever arm in the state variables of the state space equation. For the Kalman filter, the process model and the measurement model for attitude determination are made up by using quaternion. In order to evaluate the proposed algorithm, both of the simulations and the experiments are performed for the simplified scenario of motion.

• Smart Structures and Systems
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• 제26권6호
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• pp.693-701
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• 2020

The conventional Kalman Filter (KF) provides a promising way for structural state estimation. However, the physical parameters of structural systems or models should be available for the estimation. Moreover, it is not applicable when the loadings applied to the structures are unknown. To circumvent the aforementioned limitations, a two-stage KF with unknown input approach is proposed for the simultaneous identification of structural parameters and unknown loadings. In stage 1, a modified observation equation is employed. The structural state vector is estimated by KF on the basis of structural parameters identified at the previous time-step. Then, the unknown input is identified by Least Squares Estimation (LSE). In stage 2, based on the concept of sensitivity matrix, the structural parameters are updated at the current time-step by using the estimated structural states obtained from stage 1. The effectiveness of the proposed approach is numerically validated via a five-story shearing model under random and earthquake excitations. Shaking table tests on a five-story structure are also employed to demonstrate the performance of the proposed approach. It is demonstrated from numerical and experimental results that the proposed approach can be used for the identification of parameters of structure and the external force applied to it with acceptable accuracy.

• 설비공학논문집
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• 제15권3호
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• pp.196-202
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• 2003

Two dimensional modeling was carried out to find the safety distance between the defrost heater and the plastic inner wall of domestic refrigerator Estimation was processed for the three cases; the estimation of plastic wall temperature (1) without any protection, (2) with an aluminum foil attached on a wall, and (3) with an aluminum shield installed between heater and wall. The former two cases are found to be dangerous during defrosting process, because the temperatures of inner wall reach above 80'C , which is the upper temperature limit of the wall material. The case with an aluminum shield is considered to be safe by maintaining the temperature of the wall in the range of 6$0^{\circ}C$ during defrosting process.

• 산업경영시스템학회지
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• 제14권24호
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• pp.199-206
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• 1991

As the development of modern technology, human works shift whose roll from physical conditions to the system monitoring tasks. In this paper, safety-presentation configuration is discussed instead of well-known fault-warning configuration. Safety-presentation configuration is verified as superior to the fault-warning configuration in hazard prevention. The estimation of system states involves the decision making environments which lack of required in formations and most of all the informations are not precise too. And the limitation of human information processing show doubtful results. So the estimation of system states is regardes as fuzzy number, and its operation produces the parameter that explain the discriminability(d), decision criterion ($\beta$) of system operator's behaviors. These two values served as performance indices. Especially the $\beta$ is a good milestone of the operator's altitude degree of caution.

• 한국안전학회지
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• 제26권5호
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• pp.27-32
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• 2011

Recently new technological development needs the advances in the fields of new materials. The most advanced design is not useful if new material's performance is not realized adequately for bearing the service loads and conditions. FGMs suggests the reasonable solution for the those requirements because of its wide range microstructure and the continuous constitutions. It's especially good for the heat-resisting components, piezoelectricity and aerocraft fields. However the fabrication and its experimental estimation methods have not been established because of its various freedom of material's properties. Therefore it is necessary to develope the fabrication method and estimation of strength and deformation. The experiments are conducted under a four point flexural test. According to results, this study shows that FGMs is well fabricated and the deformation and strain fields are expressed very well by digital image correlation method.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1153-1160
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• 2022

The application of video processing techniques are useful for the safety of nuclear power plants by tracking the people online on video to estimate the dose received by staff during work in nuclear plants. Nuclear reactors remotely visually controlled to evaluate the plant's condition using video processing techniques. Internal reactor components should be frequently inspected but in current scenario however involves human technicians, who review inspection videos and identify the costly, time-consuming and subjective cracks on metallic surfaces of underwater components. In case, if any frame of the inspection video degraded/corrupted/missed due to noise or any other factor, then it may cause serious safety issue. The problem of missing/degraded/corrupted video frame estimation is a challenging problem till date. In this paper a systematic literature review on video processing techniques is carried out, to perform their suitability analysis for NPP applications. The limitation of existing approaches are also identified along with a roadmap to overcome these limitations.

• 한국안전학회지
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• 제19권4호
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• pp.36-41
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• 2004

This paper presents an qualitative assessment for hazard on the electric power installations of a construction field using FMEL The power installations have the mission to maintain the highest level of service reliability on the works. The more capital the electric power invest the higher service reliability they plausibly will achieve. However, because of limited resources, how effectively budgets can be allocated to achieve service reliability as high as possible. The assessment typically generates recommendations for increasing component reliability, thus improving the power installation safety. The FMEA tabulates the failure modes of components and how their failure affects the power installations being considered. Tn order to estimate the risks of a failures, the FMEA presents criticality estimation or risk priority number using the severity, occurrence, and detectability. The results showed that the highest components of the risk priority number among components were condenser, transformer, MCCB and LA. And In case of the criticality estimation, the potential failure modes were abnormal temperature rise, insulation oil leakage, deterioration for the transformer, overcurrent for the MCCB and operation outage fir the LA.

• 대한임베디드공학회논문지
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• 제17권3호
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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.

• 대한교통학회지
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• 제29권1호
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• pp.103-111
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• 2011

유사한 특성을 갖는 지점 (또는 구간)들에서 연속되고 동일한 시간 간격 동안 관측된 패널 (panel) 교통사고 자료를 시간의 흐름에 따라 비교분석하여 분석지점의 기대교통사고건수를 추정하는 과정은 교통안전 개선사업의 효과 평가와 교통안전 개선사업 수행의 우선순위 결정과 같은 교통안전연구의 핵심이다. 패널 교통사고 자료를 이용한 기대교통사고건수 추정기법은 관측교통사고건수 기반 기법과 경험적 베이지안 기법으로 대별할 수 있으며, 본 연구에서는 시간의 흐름에 따른 기대교통사고건수의 변화 여부와 다양한 패널 교통사고 자료 구조에 따라 전술한 두 가지 기법의 추정오차를 모의실험을 통해 비교 분석하였다. 분석결과 시간의 흐름에 따른 기대교통사고건수의 변화 여부와 패널교통사고자료 구조의 특성과 관계없이 관측교통사고건수 기반 추정치인 평균 관측교통사고건수와 평행비교 추정치의 추정오차는 경험적 베이즈 추정치의 추정오차보다 항상 크게 나타나 향후 패널교통 사고자료를 이용한 교통안전 연구 수행 시 경험적 베이지안 추정기법의 적용이 필요하다고 판단된다. 한편 시간의 흐름에 따라 기대교통 사고건수가 변화하지 않을 경우 분석기간이 늘어날수록 두 가지 기법의 추정오차는 모두 현저하게 감소하는 것으로 분석되어, 현재 국내의 교통사고 잦은 곳 선정 연구에서 기준치로 사용되고 있는 분석기간인 "1년"을 연장하여 보다 효율적으로 시간 불변 기대교통사고건수를 추정할 필요가 있다고 판단된다.