• 한국기계가공학회지
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• 제14권4호
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• pp.118-125
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• 2015

The roll-forming process is a highly productive incremental forming process and is suitable for manufacturing thin, high-strength steel products. Recently, this process has been considered one of the most productive processes in manufacturing high-strength steel automotive structural parts. However, it is very difficult to develop the roll-forming process when the cross-sectional shape of the product changes in the longitudinal direction. In this study, a roll-forming process for manufacturing high-strength steel automotive parts with a linearly variable symmetric hat-type cross-section was developed. The forming rolls were designed by the 3D CAD system, CATIA. Additionally, the designed forming rolls were modified by the simulation through the 3D elastic-plastic finite element analysis software, MARC. The results of the finite element analysis show that the final roll-forming roll can successfully produce the desired high-strength steel automotive part with a variable cross-section.

• Nuclear Engineering and Technology
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• 제13권2호
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• pp.63-72
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• 1981

핵연료 집합체의 예기치 않은 파손으로 인하여 설계 근거 재장전 방침이 변경되면 원자로심내에서의 출력 분포 비균형을 막기 위하여 파손된 핵연로 집합체 이외에 대칭 위치의 집합체도 제거되어야 할 경우가 있다. 이와 같은 때에 제거된 핵연료 집합체가 설계연소도에 미달되는 경우 이를 다시 사용하여 핵연료 이용률을 증진시키는 것이 연구되었다. TDCORE 코드가 노심ㆍ해석을 위해 이용되었으며, 최적장전모형을 찾는 코드로는 RELOAD-II가 이용되었다. 고리 1호기에 적용한 결과, 제 1주기말에 제거된 비교적 적게 연소된 4개의 핵연료집합체를 제 3주기에서 이용할 경우 주기 연소도가 l1648 MWD/MTU(가동율 : 80%)에 이를 수 있음을 알 수 있었으며 평형주기까지의 장전모형을 추적하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.578-580
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• 2017

IoT 기술의 발전으로 IoT 기기들 사이의 통신에 보안이 중요해지고 있으며, 다양한 보안 알고리즘을 사용하고 있다. 많은 대칭 키 알고리즘 중에 AES (Advanced Encryption Standard) 알고리즘은 높은 보안성으로 지금까지 사용하고 있다. 본 논문에서는 효율적인 AES 알고리즘의 하드웨어 구조를 제안한다. 제안하는 하드웨어 구조는 암호화 모듈과 키 생성 모듈에 4단 파이프라인 구조를 적용하여, 높은 처리량과 낮은 지연시간을 가진다. 총 512비트의 일반 텍스트를 46 사이클에 처리가 가능하다. 제안하는 하드웨어 디자인은 65nm 공정에서 1.18GHz의 최대 주파수와 13Gbps의 처리량을 가지며, 180nm 공정에서 800MHz의 최대 주파수와 8.9Gbps의 처리량을 가진다.

• International Journal of Vascular Biomedical Engineering
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• 제1권2호
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• pp.20-29
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• 2003

A new treatment for coronary artery occlusive disease is being developed in which a shunt or conduit is placed directly connecting the left ventricle with the diseased artery at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Simulation results indicate that in complete LAD occlusion, flow can be returned to approximately 65% of normal if the conduit resistance is equal for forward and reverse flow, increasing to 80% in the limit in which backflow resistance is infinite. Increases in flow rate produced by asymmetric flow resistance are considerably enhanced in the case of a partial LAD obstruction since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle("steal") during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but leads to considerable augmentation when the resistance is asymmetric. These results suggest that an LV-LAD conduit will be beneficial when stenosis resistance(Rst) > 27 PRU if resistance is symmetric.

• 대한산업공학회지
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• 제33권1호
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• pp.44-51
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• 2007

The purpose of this study was to identify the relationship between the cumulative fatigue of trunk muscles andthe period of recovery time during repetitive lifting and lowering tasks with symmetric and asymmetric postures.Ten subjects participated in the experiment. Subjects had 1, 2, 3, 4 and 5 minutes recovery time respectivelywhile they were performing the lifting and lowering task repeatedly for 3 minutes with the weight equivalent to25% level of MVC. EMG signals from ten trunk muscles were collected and the fatigue level was analyzedquantitatively. In results, the local muscle fatigue was no longer accumulated when 5 minutes recovery time wasgiven in symmetric position. For asymmetric position, it took longer minutes to prevent the fatigue accumul-ation. Different trunk muscles indicated slightly different recovery patterns in terms of MPF (Mean Powerfrequency) value.This result would help ergonomist design the length of recovery time to control the cumulative fatigue of trunkmuscles in industry with repetitive lifting and lowering task.

• 대한기계학회논문집A
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• 제21권1호
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• pp.133-143
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• 1997

Piezoelastic materials have recently attracted considerable attention because of their potential use in intelligent structural systems. In this paper, we treat a transient piezothermoelastic problem in a hexagonal plate of crystal class 6mm subjected to antisymmetric heating temperature. We analyze this problem by use of the potential function method. Numerical calculations are carried out for a cadmium selenide solid, and the results are presented graphically in comparison with those derived from the similar problem in a cadmium selenide plate subjected to symmetric heating temperature for a symmetry transient problem.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.720-724
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• 2004

This paper introduces a new type of driving mechanism for rescue robot that has a variable geometry single-track which satisfies the pre-conditions of rescue robot. This mechanism is a symmetric configuration that has dual directions and prepares against overturn. By using transformation, it can reduce the energy consumption in steering and rotating. And also it maximizes the ability to overcome obstacles, like steps. It is designed to make the size of robot compact and to have the low center of gravity in driving on steps. Finally, we optimized the design variables of components determining the shape of reverse-trapezoid frame to enhance the adaptability to 4 phases of climbing steps.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1983년도 제25회 수공학 연구발표회 논문초록집
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• pp.78-79
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• 1983

It is well known that small amplitude wave theory, a first approximation to the complete theoretical description of wave behavior, yields a maximum investment in mathematical endeavor. But, if the wave amplitude is large, the small amplitude considerations are not valid, and finite amplitude wave theory which retains higher-order terms to obtain an accurate representation of the wave motion is numercal theory. The Stream function wave theory, one of the numerical methods, was developed by Dean for use with asymmetric measured wave profiles and with symmetric theoretical wave profiles. Dalrymple later improved the comjputational procedure by adding two Lagrangian constraints so that more efficient convergence of the iterative numerical method to a specified wave heigh and to a zero mean free surface displacement resulted. This paper introduces in details the Dean and Darlymple Stream Function Method in case of the symmetric theoretical wave, because in design purposes, wave height and wave period are given.

• Investigative Magnetic Resonance Imaging
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• 제1권1호
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• pp.79-85
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• 1997

Fast spin echo imaging utilizes multiple spin echoes to encode multiple k-space lines instead of multiple $T_2-weighted$ images. As results, intensities in k-space data are varying according to T2 decay, which generates Gibb's artifact in the reconstructed image. The echo time for e encoding dc block determines contrast, as is specified by the effective echo time, however, all location of other echoes to different k-space frequency blocks in fast spin echo imaging is not f fully investigated. In this study, symmetric arrangement of multiple echoes in k-space is investigated to reduce Gibb's artifact. Design of filters based on the measurement of multiple e echo intensities is also proposed in two stage manner, i.e., equalization and filtering. From s simulation and experiment, it was observed that Gibb's phenomena were substantially reduced b by the proposed methods.

• Journal of Multimedia Information System
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• 제4권4호
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• pp.219-224
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• 2017

This paper is to introduce an application of face recognition algorithm in parallel. We have experiments of 25 images with different motions and simulated the image recognitions; grouping of the image vectors, image normalization, calculating average image vectors, etc. We also discuss an analysis of the related eigen-image vectors and a parallel algorithm. To develop the parallel algorithm, we propose a new type of initial matrices for eigenvalue problem. If A is a symmetric matrix, initial matrices for eigen value problem are investigated: the "optimal" one, which minimize ${\parallel}C-A{\parallel}_F$ and the "super optimal", which minimize ${\parallel}I-C^{-1}A{\parallel}_F$. In this paper, we present a general new approach to the design of an initial matrices to solving eigenvalue problem based on the new optimal investigating C with preserving the characteristic of the given matrix A. Fast all resulting can be inverted via fast transform algorithms with O(N log N) operations.