• The KIPS Transactions:PartA
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• v.14A no.1 s.105
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• pp.1-14
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• 2007

MPICH-G2 is an MPI implementation to solve complex computational problems by utilizing geographically dispersed computing resources in grid environments. However, the computation nodes in MPICH-G2 are exposed to the external network due to the lack of supporting the private IP clusters, which raises the possibility of malicious security attacks. In order to address this problem, we propose MPICH-GP with a new relay scheme combining NAT(Network Address Translation) service and an user-level proxy. The proxy running on the front-end system of private IP clusters forwards the incoming connection requests to the systems inside the clusters. The outgoing connection requests out of the cluster are forwarded through the NAT service on the front-end system. Through the connection path between the pair of processes, the requested MPI jobs can be successfully executed in grid environments with various clusters including private IP clusters. By simulations, we show that the performance of MPICH-GP reaches over 80% of the performance of MPICH-G2, and over 95% in ease of using RANK management method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.391-395
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• 2015

A 15-Lead ECG has been developed to diagnose posterior wall diseases of the heart that a 12-Lead ECG cannot diagnose. However, 15-Lead ECG data for developing heart-diseases-detecting algorithm are limited, and previous ECG simulators cannot predict the ECG waveform according to the changes in electrode. To solve these problems, the lumped parameter model (LPM), which divides the heart into 15 sections with varying electrical capacitance and electrical resistance. To imitate the electrical conduction in the heart, each node was connected to a current source and delivered the specific current considering the positions and time delay. The purpose of this study is to acquire the waveform that can be used in an ECG by delivering the specific current to LPM.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.754-760
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• 2012

This paper describes peak shaving algorithms as long-term cycle scheduling in the power management system (PMS) for MW-scale battery energy storage systems (BESS). The purpose of PMS is basically to manage the input and output power from battery modules placed in the systems. Assuming that an one-day ahead load curve is provided, off-line peak shaving algorithms can be employed, but applying the results of the off-line algorithm may result in the difference in the real-time performance because there is uncertainty in the provided load curve. This paper adopts fuzzy based LP (linear programming) algorithms for describing the peak shaving algorithm in PMS and discusses a solution technique and real-time operation strategies using the solution.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.11
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• pp.151-162
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• 1994

A new neural network structure called Self-organized Distributed Networks (SODN) is proposed for developing the neural network-based multidimensional system models. The learning with the proposed networks is fast and precise. Such properties are caused from the local learning mechanism. The structure of the networks is combination of dual networks such as self-organized networks and multilayered local networks. Each local networks learns only data in a sub-region. Large number of memory requirements and low generalization capability for the untrained region, which are drawbacks of conventional local network learning, are overcomed in the proposed networks. The simulation results of the proposed networks show better performance than the standard multilayer neural networks and the Radial Basis function(RBF) networks.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.12
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• pp.1061-1066
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• 2016

Corrugation of a corrugated panel dramatically increases the bending stiffness per weight. However, corrugated panels show lower sound insulation performance than that of the flat plate having the same weight. Especially, in a particular frequency region, the sound transmission loss significantly decreases. Main reason of the problem is known as the local resonance. A number of local resonance modes occur above a certain frequency band and modal density rapidly increases. In this study, we investigate the relation of the sound transmission loss and the modal density. Finally, we propose a design methodology in terms of the modal density to improve the sound insulation performance of the corrugated panels without weight increase.

• Geophysics and Geophysical Exploration
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• v.3 no.2
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• pp.61-69
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• 2000

The free-surface boundary conditions are persistent problem in elastic wave equation modeling by finite-difference method, which can be summarized with the degradation of the accuracy of the solution and limited stability range in Poisson's ratio. In this paper, we propose the mid-point averaging scheme as an alternative way of implementing the free-surface boundary conditions, and present the solution to Lamb's problem to verify our approach.

• The Journal of Society for e-Business Studies
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• v.9 no.4
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• pp.137-155
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• 2004

A video-conference system is being utilized in web based application services in various fields due to the widespread use of Internet and the progress of computer technologies. This system should use the public IP address for sharing file and white board and it is difficult to manage the internal network users of the firewall and non-public IP address users. In this paper, we propose an Application Level Gateway which transforms non-public IP address into public IP address. This mechanism is for the internal network users of the firewall or non-public IP address users over the Internet. We also propose a Control Daemon which manages video and audio media dynamically according to network bandwidth. This mechanism can start and terminate a video conference and manage the process of the video conference.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.655-657
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• 2002

현재 네트웍 보안을 위한 방화벽과 유일한 공용 IP 주소 부족 문제를 해결하기 위한 NAT 사용이 일반화되고 있다. 그러나 이러한 환경 안에 있는 사용자들은 외부 피어의 연결을 받지 못하여 제한된 서비스만을 받고 있기 때문에, 순수 P2P 환경에서 피어들간의 연결을 방해하는 가장 큰 요소가 되고 있다. 본 논문에서는 이러한 문제점을 해결하기 위해P2P 환경에서 방화벽／NAT가 아닌 피어들 중 네트웍 트래픽이 많지 않은 피어를 동적으로 선정하여 프락시 서버를 할당한 후 피어들의 통신 매개체로 사용하는 기법을 제안한다. 이 제안기법은 모든 운영체제에서 사용 가능하고, 양방향 통신을 가능하게끔 해주며, 네트웍 트래픽을 여러 피어들 에게 분산키는 장점을 갖고 있다. 차후 파일 전송, 화상 채팅 등의 여러 가지 서비스를 사용하는데 유용한 기법이 될 것이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.149-156
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• 2012

In fracture mechanics, the weight function can be used for calculating stress intensity factors. In this paper, a two-dimensional electroelastic analysis is performed on a transversely isotropic piezoelectric material with an open crack. A plane strain formulation of the piezoelectric problem is solved within the Leknitskii formalism. Weight function theory is extended to piezoelectric materials. The stress intensity factors and electric displacement intensity factor are calculated by the weight function theory.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.157-160
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• 2000

다중 워터마킹은 하나의 컨텐츠에 2개 이상의 다른 워터마크를 삽입하는 것으로 각 워터마크는 유일한 키로 정확하게 추출할 수 있어야 한다. 대역확산법(spread spectrum)을 이용한 다중 워터마킹은 삽입되는 워터마크간의 직교성(orthogonality)이 제공되어야 삽입된 워터마크들의 정확한 추출이 가능하다. 랜덤계열과 Hadamard 계열을 이용한 기존의 방법은 직교성이 보장되지 않기 때문에 워터마크가 정확히 추출되지 않은 문제가 발생한다. 따라서, 본 논문에서는 랜덤계열들을 Gram-schmidt 직교화 과정을 이용하여 직교화시킨 후, 직교화 된 랜덤계열로 워터마크를 삽입하여 정확한 추출이 가능한 방법을 제안하였다.