• Bulletin of the Korean Mathematical Society
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• v.50 no.6
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• pp.1799-1816
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• 2013

Privacy preserving multiset union (PPMU) protocol allows a set of parties, each with a multiset, to collaboratively compute a multiset union secretly, meaning that any information other than union is not revealed. We propose efficient PPMU protocols, using multiplicative homomorphic cryptosystem. The novelty of our protocol is to directly encrypt a polynomial by representing it by an element of an extension field. The resulting protocols consist of constant rounds and improve communication cost. We also prove the security of our protocol against malicious adversaries, in the random oracle model.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.449-451
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• 2008

This paper studies the instability between homopolar generator and constant power load with negative impedance characteristics, provides the design method of homopolar generator system which overcomes the instability. In case of magnitude and phase of impedance of source and load mismatch, control instability of source can occur. For the safety of phase of load impedance, the gain of P, I controller with sufficient phase margin is applied through analysis on the simulation model of generator system, and the gain limit of load impedance is ensured by limitation of the gain margin of generator system. The stability of power system can be increased by considering and analyzing the impedance of source and load.

• Transactions on Control, Automation and Systems Engineering
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• v.1 no.2
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• pp.87-93
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• 1999

This paper proposes a systematic designs methodology for the Takagi-Sugeno (TS) model based fuzzy control systems with guaranteed stability and pre-specified transient performance for the application to a nonlinear magnetic bearing system. More significantly, in the proposed methodology , the control design problems which considers both stability and desired transient performance are reduced to the standard LMI problems . Therefore, solving these LMI constraints directly (not trial and error) leads to a fuzzy state-feedback controller such that the resulting fuzzy control system meets above two objectives. Simulation and experimentation results show that the proposed LMI-based design methodology yields only the maximized stability boundary but also the desired transient responses.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.433-438
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• 2009

The main objective of this research effort is to develop the performance of C/SiC composites manufactured by LSI (Liquid Silicon Infiltration) method for solid and liquid rocket propulsion system and ensure the performance analysis technique. The high performance and reliability of C/SiC composite are proved for solid and liquid rocket propulsion system. And the performance analysis technique related to mathematical ablation model is originated.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.2
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• pp.116-122
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• 2000

In the high speed range for salient type synchronous reluctance motor, the effect of iron loss can not be negligible. We have investigated the voltage equations including iron loss from the model that is added the equivalent iron loss in the equivalent inductance in series. In this paper, we derive Ld linear approximate equation from saturation range of Ld, Lq vs applied voltage characteristics and obtain equations including saturation and iron loss related to maximum torque control using Ld. The effect of saturation and iron loss is investigated under maximum torque control. And we show that the proposed maximum torque control scheme achieves the desired performances through experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1426-1435
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• 1996

In this paper. a network theory for generaltransmission systme was extended considering the direction of power flow. Also, a modified network model was suggested for a node with 4 shafts in order to verify the power flow. Based on the extended network theory, a simulation program was developed to analyze a hydro-mecaanical tranmission(HMT) system consistion of two hydrostatic pump motors, severeal planetary gear trains steer differential gear. The simulation result showed that the extendednotwork analysis program develped can predict the power circulation as well as the magnitude of torque and speed for each transmission element and can be used design tool for genaral power transmission system.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.5
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• pp.378-386
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• 2017

In this paper, a method is presented for the optimal design of submarine pressure hull structures by taking advantage of genetic algorithm techniques. The objective functions and design constraints in the process of structural optimization are based on the ultimate limit states of hull structures. One of the benefits associated with the utilization of genetic algorithm is that the optimization process can be completed within short generations of design variables for the pressure hull structure model. Applied examples confirm that the proposed method is useful for the optimal design of submarine pressure hull structures. Details of the design procedure with applied examples are documented. The conclusions and insights obtained from the study are summarized.

• Journal of Aerospace System Engineering
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• v.10 no.1
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• pp.82-85
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• 2016

In this study, structural design of exhaust gas sensor of automobile was performed. In order to evaluate the structural design of the measurement sensor, the structural analysis was performed by the finite element method. The vibration and thermal stress analysis was carried out at the high temperature condition. Finally, the structural test of sensor system was performed, and used for comparison with the analyzed model. Through the structural analysis and test, it is confirmed that the designed measurement sensor structure is acceptable.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.131-136
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• 2002

최근 전장환경의 급격한 변화와 고도화된 과학기술로 인해 무기체계의 성능은 매우 발전되었으며 세계 각국은 고성능, 고효율의 최신 무기체계 개발에 역량을 집중하고 있다. 개별 무기체계에 대응하여 새롭게 개발된 무기체계는 기존 무기체계에 대한 패러다임을 뛰어넘어 새로운 개념과 운용방식을 요구하고 있다. 무기체계의 효과를 규명하고 검증하기 위한 수단으로 가장 적합한 것은 실제전장에 무기체계를 투입한 실기동 실험을 통해 효과를 분석하는 것이다. 그러나 무기체계 효과분석을 위해 실기동훈련을 계획하고 실시하는 것은 비용 뿐 아니라 군사력 동원면에 있어서 비효율적이고 부담이 높은 단점이 있으므로, 국방시뮬레이션 기술을 활용하여 저비용 고효율의 모의분석을 실시함으로써 계량적인 효과분석을 수행하고 수치화된 판단 근거를 제공하는 것이 보다 바람직하다고 할 수 있다. 본 고는 대대급 이하 소부대의 전장상황에서 지상군 단위무기체계의 효과 분석을 수행할 수 있는 국방 시뮬레이션 모형의 개발 방향을 제시한다.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.137-141
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• 2002

향후 한국군의 전력발전을 위해 미래전 무기체계엔 대한 획득소요가 활발히 제기되고 있으며, 소요에 부응하기 위한 무기체계 효과분석이 요구되고 있다. 국내외적으로 이와 같은 미래전 무기체계 소요검증 및 효과분석을 위해 전투실험이 수행되고 있다. 현재 미래전 무기체계 분석수단으로 가상자료를 활용한 시뮬레이션이 널리 활용되고 있으며, 시뮬레이션을 활용한 전투실험은 향후 개발될 무기체계의 특성자료를 기준으로 실제 전장환경과 동일한 조건에서의 시뮬레이션을 통해, 각 무기체계의 효과를 정량적으로 분석할 수 있기 때문이다. 본 연구는 이와 같은 미래전 무기체계 효과분석시 활용될 수 있는 시뮬레이션 모형 활용기법을 제안하여 전투실험의 효과를 검증하고, 한국군의 미래 모의분석체계 발전에 기여하고자 한다.