• 한국자동차공학회논문집
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• 제16권5호
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• pp.100-105
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• 2008

In the design process of an automobile part, several analysis methods are usually utilized to evaluate the performance of the part. However, most automobile design engineers do not directly utilize CAE (Computer Aided Engineering) tools since specific skills are required to obtain practical results. Moreover, CAE requires a huge amount of computation time and cost. In order to resolve these problems, a new design approach named First Order Analysis (FOA) technique has been proposed. In this paper, the FOA technique is employed to design a vehicle sub-frame. An equivalent model of the vehicle sub-frame which only consists of beam elements is proposed and the modal properties obtained with the model are compared to those obtained with a full scale finite element model. The effect of some parameter tolerances on the modal characteristics of the vehicle sub-frame is investigated by employing the FOA equivalent model.

• Steel and Composite Structures
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• 제48권3호
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• pp.321-333
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• 2023

This paper proposes a comprehensive investigation on lateral stiffness of corner-supported steel modular frame using splice connection. A full-scale modular frame with two stacked steel modules under lateral load is tested. Ductile pattern in the transfer of lateral load is found in the final failure mode. Two types of lateral stiffness, including tangent stiffness and secant stiffness, are defined from the load-displacement due to the observed nonlinearity. The difference between these two types of stiffness is found around 20%. The comparisons between the experimental lateral stiffness and the predictions of classical methods are also conducted. The D-value method using hypothesis of independent case is a conservative option for predicting lateral stiffness, which is more recommended than method of contraflexural bending moment. Analyses on two classical short-rod models, including fix-rod model and pin-rod model, are further conducted. Results indicate that fix-rod model is more recommended than pin-rod model to simplify splice connection for simulation on lateral stiffness of modular frame in elastic design stage.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.146-155
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• 2012

This study aims to analyze durability by comparing displacement on vibration at driving bicycle frame models of 1, 2, 3 and 4. Among maximum equivalent stresses at 4 kinds of models, model 1 has highest value with 410.39 MPa and becomes 30 times than model 4 with lowest value. The natural frequency number at Model 4 increases more than the other models. Among four models, the number of frequency at model 1 becomes lowest at harmonic vibration with real loading condition. In cases of four kinds of models, the maximum stress is shown near the assembly of rear wheel and the maximum displacement is shown near saddle assembly at this harmonic condition. The structural result about this study can be effectively utilized on the design of bicycle frame by investigating durability and prevention against its damage.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.272-275
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• 2004

This study is to propose a modified equivalent frame method under lateral loading. ACI 318-02 allows the equivalent frame method to conduct slab analysis subjected to lateral loads. However, current method can not predict the behavior of the slabs particularly under lateral loading because the equivalent frame method in the ACI 318 has been developed against gravity loads. This study provides more precise model for the analysis of the flat plate slabs under lateral loading. The model reflect the force transfer mechanism of slabs, column and torsional member more accurately than the existing model. The accuracy of this model is verified by compared with finite element method analysis results.

• Earthquakes and Structures
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• 제5권1호
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• pp.111-127
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• 2013

This paper describes effects of infill walls on behavior of RC frame with low strength, including numerical modeling, modal testing and finite-element model updating. For this purpose full scaled, one bay and one story RC frame is produced and tested for plane and brick in-filled conditions. Ambient-vibration testis applied to identify dynamic characteristics under natural excitations. Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods are used to obtain experimental dynamic characteristics. A numerical modal analysis is performed on the developed two-dimensional finite element model of the frames using SAP2000 software to provide numerical frequencies and mode shapes. Dynamic characteristics obtained by numerical and experimental are compared with each other and finite element model of the frames are updated by changing some uncertain modeling parameters such as material properties and boundary conditions to reduce the differences between the results. At the end of the study, maximum differences in the natural frequencies are reduced on average from 34% to 9% and a good agreement is found between numerical and experimental dynamic characteristics after finite-element model updating. In addition, it is seen material properties are more effective parameters in the finite element model updating of plane frame. However, for brick in-filled frame changes in boundary conditions determine the model updating process.

• 한국음향학회지
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• 제21권3호
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• pp.323-329
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• 2002

본 논문에서는 임의의 시점에서 발생하여 음성 신호의 일부분을 심하게 손상시키는 시간선택 잡음 (time-selective noise)을 보상하기 위한 프레임 신뢰도 가중 방법을 제안한다. 음성 프레임들은 서로 다른 정도의 신뢰도를 갖으며, 신뢰도는 프레임의 신호대잡음비 (signal-to-noise ratio)에 비례한다. 잡음이 일정한 경우에는 무음구간에서 획득한 잡음 정보를 이용하여 프레임의 신호대잡음비 추정이 용이하나, 시간선택 잡음은 잡음추정이 어렵다. 따라서, 본 연구에서는 프레임 신뢰도를 추정하기 위해 깨끗한 음성의 통계적 모델을 사용하였다. 제안한 MFR (model-based frame reliability) 방법은 탐조 모델의 평균 벡터열과 입력 MFCC (mel-frequency cepstral coefficient) 특징 벡터 열의 역변환에 의해 얻은 필터뱅크 에너지를 이용하여 프레임 신호대잡음비를 근사한다. 다양한 버스트 (burst) 잡음에 대한 인식 실험 결과, 제안한 방법은 프레임의 신뢰도를 효과적으로 나타낼 수 있었으며, 이 신뢰도를 우도 계산에서 가중치로 적용하여 인식 성능을 향상시킬 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.575-580
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• 1997

This study presents the techniques to manufacture the model concrete and model reinforcement for the 1/5-scale 3-story reinforced concrete frame. The used model concrete has sufficient workability but shows a little lower strength than expected model steel was made of commercial $\phi$3.2mm and $\phi$2.0mm wire by using deforming device and vacuum tube electric furnace. The yield strength can be simulated but it was difficult to simulate the other properties. The load cell was specially manufactured to measure the shear force in the columns of the first story. The carrying frame and the hinge adapter of artificial mass are explained. The special problems in the process of construction of model are also dressed.

• 대한전자공학회논문지SP
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• 제45권3호
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• pp.93-102
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• 2008

본 논문에서는 동영상의 화질을 일정하게 하기 위한 실시간 비트율 제어 기법을 제안한다. 일정 화질을 만족하기 위한 기존의 비트율 제어 알고리즘은 프레임의 부호화 복잡도를 잔여 신호인 MAD(mean absolute of difference)로 추정하여 비트 할당을 수행하였다. 그러나 MAD는 영상의 특성이나 부호화 파라미터에 따라 동일한 MAD라도 다른 비트를 생성하므로 영상의 부호화 복잡도를 적절히 나타내기 어렵다. 본 논문에서는 이 문제를 해결하기 위해 비트와 MAD사이의 기울기인 모델 파라미터를 프레임의 복잡도의 측도로 보고 이전 프레임과 현재 프레임의 모델 파라미터의 비율로 비트 할당을 수행한다. 또한 기존의 비트-복잡도 모델에서 구한 모델 파라미터는 양자화 파라미터가 변함에 따라 그 값이 크게 변하여 영상의 내재적 복잡도를 나타내기 어렵다. 따라서 본 논문에서는 비트-복잡도 모델에 양자화 파라미터를 추가하여 양자화 파라미터가 변하더라도 영상의 복잡도의 측도인 모델 파라미터는 변하지 않게 하였다. 광범위한 실험결과는 제안한 알고리즘이 기존의 알고리즘에 비해 비슷한 평균 화질을 유지하면서 화질의 변동을 큰 폭으로 줄였음을 보여준다.

• International journal of advanced smart convergence
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• 제5권4호
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• pp.1-9
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• 2016

In order to reconstruct a 3D model in video sequences, to select key frames that are easy to estimate a geometric model is essential. This paper proposes a method to easily extract informative frames from a handheld video. The method combines selection criteria based on appropriate-baseline determination between frames, frame jumping for fast searching in the video, geometric robust information criterion (GRIC) scores for the frame-to-frame homography and fundamental matrix, and blurry-frame removal. Through experiments with videos taken in indoor space, the proposed method shows creating a more robust 3D point cloud than existing methods, even in the presence of motion blur and degenerate motions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권1호
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• pp.165-182
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• 2014

An RFID systems employ efficient Anti-Collision Algorithms (ACAs) to enhance the performance in various applications. The EPC-Global G2 RFID system utilizes Frame Slotted Aloha (FSA) as its ACA. One of the common approaches used to maximize the system performance (tag identification efficiency) of FSA-based RFID systems involves finding the optimal value of the frame length relative to the contending population size of the RFID tags. Several analytical models for finding the optimal frame length have been developed; however, they are not perfectly optimized because they lack precise characterization for the timing details of the underlying ACA. In this paper, we investigate this promising direction by precisely characterizing the timing details of the EPC-Global G2 protocol and use it to derive a precise-optimal frame length model. The main objective of the model is to determine the optimal frame length value for the estimated number of tags that maximizes the performance of an RFID system. However, because precise estimation of the contending tags is difficult, we utilize a parametric-heuristic approach to maximize the system performance and propose two simple schemes based on the obtained optimal frame length-namely, Improved Dynamic-Frame Slotted Aloha (ID-FSA) and Exponential Random Partitioning-Frame Slotted Aloha (ERP-FSA). The ID-FSA scheme is based on the tag set estimation and frame size update mechanisms, whereas the ERP-FSA scheme adjusts the contending tag population in such a way that the applied frame size becomes optimal. The results of simulations conducted indicate that the ID-FSA scheme performs better than several well-known schemes in various conditions, while the ERP-FSA scheme performs well when the frame size is small.