• Proceedings of the KSME Conference
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• 2001.06e
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• pp.373-379
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• 2001

When a train runs into a tunnel at high-speed, aerodynamic drag suddenly increases and the booming noise is generated at the exit of tunnel. The noise shape is very important to reduce the aerodynamic drag in tunnel as well as on open ground, and the micro-pressure wave that is a source of booming noise is dependent on nose shape, especially on area distribution. In this study, the nose shape has been optimized employing the response surface methodology and the axi-symmetric compressible Navier-Stokes equations. The optimal designs have been executed imposing various conditions of the aerodynamic drag and the micro-pressure wave on object functions. The results show that the multi-objective design was successful to decrease micro-pressure wave and aerodynamic drag of trains.

• Proceedings of the IEEK Conference
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• 2003.07d
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• pp.1343-1346
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• 2003

상거래와 통신을 위한 주된 매개체로써 등장한 인터넷 뿐 아니라 새로이 대두되는 다양한 유무선 네트워크 환경, 그리고 정보 저장에 있어서 암호화 알고리즘은 보안의 중요한 요소로 자리잡고 있다. 본 논문에서는 대칭 및 비대칭 암호화 알고리즘을 가속시키기 위한 암호화 프로세서의 명령어와 해당 Functional Unit 을 제안하였다. 현재 암호화 알고리즘을 가속시키기 위한 방법으로 사용되는 주문형 반도체(ASIC)는 알고리즘 가속 속도는 빠르지만, 새로운 암호화 알고리즘을 지원할 수가 없고, 지원하는 알고리즘을 사용하지 않는 경우 비효율성을 야기한다. 또한 범용프로세서는 다양하고 새로운 암호화 알고리즘을 지원할 수 있지만 암/복호화 가속속도가 느리다. 이는 암호화 알고리즘이 범용 프로세서에서는 지원하지 연산을 주로 사용하기 때문이다. 따라서 이 논문에서는 대칭 및 비대칭 암호화 알고리즘의 주된 연산을 분석하고, 각각의 연산을 가속시키기 위한 명령어 집합, 그리고 해당하는 Functional Unit을 제안하여 Programmable 한 암호화 프로세서를 설계하기 위한 토대를 마련한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4962-4967
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• 2010

Security of the electronic commercial transaction especially through the information communication network is gaining its significance due to rapid development of information and communication related fields. For that, some kind of cryptographic algorithm is already in use for the smart card. However, the growing needs of handling multimedia and real time communication bring the smart card into more stringent use of its resources. Therefore, we proposed a key scheduler block of the smart card to facilitate multimedia communication and real time communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1142-1148
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• 1999

In this paper, the characteristics of frequency dependent dispersion are analyzed for the phase shifters in Ku-band phased array antenna system using full-wave method, SDA(Spectral Domain Approach).The design technique of asymmetric coupled-line phase shifter with dielectric overlay is proposed. The compared results of phase responses are shown with conventional symmetric coupled-line Schiffman phase shifter. The experimental results verify the improvement of broadband characteristics by the increasing bandwidths and the decreasing phase deviations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.108-113
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• 2008

A proposed system can decrypt each contents block through a double buffer algorithm which can continually buffer contents by dividing a multimedia contents into some blocks and provides more improved method of encryption than existing system by being not capable of decrypting the whole multimedia contents if one key is exposed. Also, using digital signature and public encryption algorithm for mutual authentication between systems, this paper proposes the system which sends and encrypts symmetric keys for contents encryption through SOAP messages.

• Archives of Plastic Surgery
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• v.47 no.5
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• pp.483-486
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• 2020

Midline clefts of the upper lip are rare, and it is therefore important that surgeons have access to a methodical approach for when these presentations are encountered. We adapted principles of the anatomic subunit approximation for unilateral cleft lip, to the repair of midline clefts. The overt use of anatomic landmarks to define the repair results in a design that inherently adjusts to varying degrees of clefts and can accommodate asymmetries. The "measure twice, cut once" style is an advantage to new surgeons and to surgeons who seldom encounter this presentation. We describe the details of surgical repair in the context of a patient with Pai syndrome and associated nasal hamartomas that resulted in nasolabial asymmetry. This is the first report of surgical outcome following treatment of Pai syndrome and includes early and 5-year follow-up. The system of repair that we describe is applicable to both symmetric and asymmetric midline clefts.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.160-165
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• 1998

The sub-resonance modes can be easily excited by the assembling tolerance in the asymmetric type optical pick-up actuators, compared with the symmetric type. In this paper, we propose the novel method for reducing the vibration due to the sub-resonance modes where undesirable modes can be decreased by adding the damping, which can be achieved by increasing the flexibility of holder PCB, against to the sub-resonance modes. Using the finite element method, the change of mode shapes is investigated as the shape of holder PCB is modified. Experimental results support that the proposed method reduces remarkably the vibration of sub-resonance modes of the optical pick-up actuator.

• Structural Engineering and Mechanics
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• v.62 no.3
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• pp.303-310
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• 2017

The model updating problems, which are to find the optimal approximation to the discrete quadratic model obtained by the finite element method, are critically important to the vibration analysis. In this paper, the structured model updating problem is considered, where the coefficient matrices are required to be symmetric and positive semidefinite, represent the interconnectivity of elements in the physical configuration and minimize the dynamics equations, and furthermore, due to the physical feasibility, the physical parameters should be positive. To the best of our knowledge, the model updating problem involving all these constraints has not been proposed in the existed literature. In this paper, based on the semidefinite programming technique, we design a general-purpose numerical algorithm for solving the structured model updating problems with incomplete measured data and present some numerical results to demonstrate the effectiveness of our method.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05d
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• pp.1012-1016
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• 2002

분산시스템에서 부하균형을 유지하기 위해서는 네트워크상의 각 노드는 다른 노드들의 부하상태정보를 가져야만 한다. 네트워크상에 ν개의 노드가 존재할 때 모든 노드간에 부하상태정보를 교환하기 위해서는 Ο(ν²)의 트래픽 오버헤드가 필요하게 된다. 이 논문에서는 분산된 노드간에 동기적으로 동작하는 부하균형 알고리즘을 제시한다. 이를 위해 먼저 SBIBD(symmetric balanced incomplete block design)에 근거하여 (ν,k,1)-configuration에 의해 ν=k²-k＋1개의 노드를 갖는 네트워크 토폴로지를 구성하였다. 이 망에서 동작하도록 고안된 부하상태정보 전파 알고리즘은 (equation omitted)의 메시지 오버헤드를 가지면서 각각의 노드가 ν개의 모든 노드에 대한 부하상태정보를 가지도록 한다. 또한 이 부하균형 알고리즘은 모든 링크가 부하상태정보 전송을 위해 동일한 트래픽을 갖도록 설계되었다.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1252-1255
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• 1987

In this paper an approach for the analysis of the transient field response of radially symmetric transducer due to a wideband ultrasonic pulse is presented, which is based on a development of Green's function and applies the linear system theory to obtain an analytic expression for the impulse response of an annulus with a planar or spherical geometry. For the focused annular array, the impulse responses of the indivisual annuli are convolved with the delayed excitation pulse, and then summed to obtain the resultant response of the array. This process is very effective in the study of the various focusing abilities of the annular array. For illustration, the field distribution of a five element annular array is treated in detail for several focusing system.