• Journal of Computational Design and Engineering
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• 제2권2호
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• pp.113-118
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• 2015

An important problem in low-dose CT is the image quality degradation caused by photon starvation. There are a lot of algorithms in sinogram domain or image domain to solve this problem. In view of strong self-similarity contained in the special sinusoid-like strip data in the sinogram space, we propose a novel non-local filtering, whose average weights are related to both the image FBP (filtered backprojection) reconstructed from restored sinogram data and the image directly FBP reconstructed from noisy sinogram data. In the process of sinogram restoration, we apply a non-local method with smoothness parameters adjusted adaptively to the variance of noisy sinogram data, which makes the method much effective for noise reduction in sinogram domain. Simulation experiments show that our proposed method by filtering in both image and projection domains has a better performance in noise reduction and details preservation in reconstructed images.

• 한국실내디자인학회논문집
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• 제27권3호
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• pp.136-144
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• 2018

The purpose of this study is to examined the unconscious response of the pupil in the observation toward the image in the eye-tracking experiments that target on a large complex cultural space. Twenty-five men participated in this experiment and the observation data were analyzed in seconds per minute on watching time. It could examine the unconscious response of information searching in the change of pupil size in the process of observing the space. The results could be defined as following several points. First, it was possible to outline the unconscious response characteristics of pupil by analyzing sudden changes in pupil size as total, cumulative, and individual. The response characteristics using frequency and time can be utilized as the analytical method to examine the degree of interest of spatial components according to the purpose of analysis in the future. Second, according to the over ${\pm}5%$ of cumulative variation rate on the pupil size change, during in the 60 seconds, the continuous pupil dilation was used 25.2 seconds in 8.8 rounds and the pupil reduction was used 18.0 seconds in 7.0 rounds. Third, when the variation rate of ${\pm}5%$ or more was regarded as the sudden changes on pupil size by individual variation, the pupil dilation was 7.2 rounds of 8.6 seconds and pupil reduction was 6.0 seconds in 5.0 rounds. This means that the pupil increases 9.3% in one expansion and decreases -8.5% in the reduction process. As regarding pupil changes as cumulative rate, it appeared high change rate on pupil reduction but it became higher on pupil dilation in individual.

• Advances in Computational Design
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• 제8권3호
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• pp.237-253
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• 2023

Torque ripple content and variable switching frequency operation of conventional direct torque control (DTC) are reduced by the integration of space vector modulation (SVM) into DTC. Integration of space vector modulation to conventional direct torque control known as SVM-DTC. It had been more frequently used method in renewable energy and machine drive systems. In this paper, SVM-DTC is used to control the rotor side converter (RSC) of a wind driven doubly-fed induction generator (DFIG) because of its advantages such as reduction of torque ripples and constant switching frequency operation. However, flux and torque ripples are still dominant due to distorted current waveforms at different operations of the wind turbine. Therefore, to smoothen the torque profile a Neural Network Controller (NNC) based SVM-DTC has been proposed by replacing the PI controller in the speed control loop of the wind turbine controller. Also, stability analysis and simulation study of DFIG using process reaction curve method (RRCM) are presented. Validation of simulation study in MATLAB/SIMULINK environment of proposed wind driven DFIG system has been performed by laboratory developed prototype model. The proposed NNC based SVM-DTC yields superior torque response and ripple reduction compared to other methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.38-40
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• 2009

In order to achieve a gearless construction of the wind energy conversion system(WECS), a low-speed generator should be used. Of the various candidate machine types, radial-field, multi-pole, permanent magnet, synchronous machines may be used for low-speed applications. So, this paper deals with the design of direct-coupled, multi-pole radial field machines with permanent magnet(PM) excitation for wind power applications for cogging torque reduction through the determination of optimum pole arc/pitch ratio. On the basis of an equivalent magnetic circuit method(EMCM) and a space harmonic method(SHM), an initial design is performed considering restricted conditions. And then, a detailed design is made using a non-linear finite element analyses(FEA). Finally, test results concerning generating characteristics are given to confirm the validation of the design.

• 한국터널지하공간학회 논문집
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• 제6권1호
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• pp.17-23
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• 2004

터널 하중을 예측하는 것은 터널 설계에서 가장 중요한 문제 중의 하나이다. 개나다 에드몬턴시의 여러 터널로 부터 측정된 계측자료와 기존에 존재하는 설계방법을 이용하여 계산된 터널 하중의 비교를 통하여 기존 설계방법들의 정확도를 검토하였다. 그러나 기존의 방법들은 터널 하중을 예측하는데 만족하지 못한 결과를 보여 주었다. 일자 라이닝의 설치 이전에 발생하는 응력감소 인자를 구한 후, 기존의 설계방법을 결합하여 터널 하중을 예측할 것을 제안하였다. 에드몬턴시에 건설된 터널에 대한 무차원 하중 인자인 nD/H값이 도표로 제시되었다. 제안된 방법의 타당성을 검증하기 위하여, 제안된 방법으로 계산된 터널 하중과 계측 값을 비교하였다. 다른 지역 터널의 경우, 비교적 견고 (stiff) 하거나 조밀 (dense)한 흙으로 구성된 지반에 터널이 건설될 경우에는 제안된 방법을 사용할 수 있다.

• International Journal of Aeronautical and Space Sciences
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• 제17권3호
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• pp.332-340
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• 2016

A design optimization is performed for the double-bolted joint in cylindrical composite structures by using a simplified analytical method. This method uses failure criteria for the major failure modes of the bolted composite joint. For the double-bolted joint with a zigzag arrangement, it is necessary to consider an interaction effect between the bolt arrays. This paper proposes another failure mode which is determined by angle and distance between two bolts in different arrays and define a failure criterion for the failure mode. The optimal design for the double-bolted joint is carried out by considering the interactive net-tension failure mode. The genetic algorithm (GA) is adopted to determine the optimized parameters; bolt spacing, edge distance, and stacking sequence of the composite laminate. A purpose of the design optimization is to maximize the burst pressure of the cylindrical structures by ensuring structural integrity. Also, a progressive failure analysis (PFA) is performed to verify the results of the optimal design for the double-bolted joint. In PFA, Hashin 3D failure criterion is used to determine the ply that would fail. A stiffness reduction model is then used to reduce the stiffness of the failed ply for the corresponding failure mode.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.676_677
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• 2009

In this paper, an analytical method used for predicting the magnetic field distribution and cogging torque characteristic in a permanent magnet synchronous motor (PMSM) is presented. The magnetic field is analyzed with the space harmonic analysis, and the cogging torque is calculated based on the air-gap field distribution and slot-opening effect considered by relative permeance. The validity of the presented analytical method is confirmed by 2-dimensional finite element analysis (FEA). Then this analytical method combines with response surface methodology (RSM) is applied to the prototype PMSM model rebuilding in order to minimize the cogging torque. Finally, an optimized PMSM model is built and the cogging torque reduction is confirmed by FEA.

• 한국실내디자인학회논문집
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• 제6호
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• pp.45-52
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• 1995

The presentation of the method by which the furniture and the architecture can be unified in one category, and the study and the verification on the mutual relation in the shape and the function are having been consistently made till the late twenties. The change of the social structure such as increasing the unit dwelling space with the small scale comes to need the efficiency in using space and the open dwelling space by the systematic spa-cial formation. Therefore, the understanding of the mean-ing and the characteristics of system furnitures as the design method which can meet such needs will be made here in this study. The application of the systematic consideration as the method of interior design means the formation of the firm image on the spacial environment through the mix-ture and link of the heterogeneous factors, the organic connection of each surface, the establishment of the natu-ral relation by linking the heterogeneous materials mutu-ally. and the easiness of the entire plan in the end. This study aims at analyzing and studying the typical charac-teristics by understanding the historical background and methodical principle which enabled the appearance of this kind of thought, and the adapted cases of the wood and metal material system furniture. There may be difference between the structural sub-stance and formative consideration. Transformative furni-ture which consists of the factors is the concept for the encrease of the multi purpose value by mixing the unit cabinets. One system can be separated horizontally, verti-cally, and to the drawers, and it gives us the disengage-ment from the artificial environment, since all the heights and width can be transformed as per each situa-tion of the space. The factors which can not be found in the other existing furniture are as follows. 1. disengagement from the artificial environment. 2. establishing the new productiosn trend as freed from the customers' fashion trend. 3. presenting the producing condition which leads the exact technology. 4. flexibility of the furniture which enables the reduction and enlargement in each situation.

• International Journal of Internet, Broadcasting and Communication
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• 제14권3호
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• pp.258-269
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• 2022

In these days, innovative functions are required to unmanned parcel delivery lockers. As non-face-to-face transactions become the center due to the recent COVID-19 pandemic, many problem occurs in society such as theft crimes and lack of loading space. Therefore, New concept storage device is developed in korea. It has the functions that minimizes empty spaces by using the internal transport device to enable efficient space loading and refrigerate goods such as foods. In order to systematically approach the system design of the unmanned parcel delivery lockers which is the new function is applied, We applied model-based system engineering to improve the development efficiency and use a system modeling language to express the system. We conducted interworking research of CAD data including system modeling and design data. it is expected that this method will increase the effective development efficiency such as maintenance traceability and reduction of development period and cost.

• 한국소음진동공학회논문집
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• 제20권6호
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• pp.521-527
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• 2010

This article presents a method to calculate the sound radiation of transmission gearbox housing by using Helmholtz integral. Rayleigh integral is used to verify the method. Half-space radiation is considered because the actual gearbox housing is on hard place like concrete. For optimization, orthogonal array is used as a fractional factorial design method. Sound Radiation is calculated with simple source like plate and sphere shape, then actual gearbox BEM model is applied to the method.