• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1198-1203
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• 2000

In this study, a nonlinear aeroelastic analysis system for the fighter wing with tip-store has been developed additionally in the transonic and supersonic flow region. The unsteady CFD code based on the transonic small disturbance theory has been incorporated to consider the numerical capability for the aerodynamic nonlinear effects. The coupled time-integration method is used to observe the detailed nonlinear aeroelastic responses for elastic wings in their flight. condition. A conservative wing-box model of a fighter wing with tip-store is modeled by MSC/PATRAN and the corresponding free vibration analysis has been performed by MSC/NASTRAN. The results of flutter analyses are presented in the subsonic, transonic and supersonic flow regime.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.229-234
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• 2006

Acquisition is to detect the presence of the GPS signal. Once the signal is detected, the estimated frequency and code phase are passed to a tracking loop to demodulate the navigation data. In order to detect the weak signal, multiple length of data integration is always needed. In this paper, we present five different acquisition approaches based on circular correlation and Fast Fourier Transform (FFT), using coherent as well as non-coherent integration techniques for the multiple length of collected GPS satellite signal. Moreover a general approach of determining the acquisition threshold is introduced based on noise distribution which has been proved effective, and independent of the hardware. In the end of this paper, the processing speed and acquisition gain of each method are illustrated, compared, and analyzed. The results show that coherent approach is much more time consuming compared to noncoherent approaches, and in the case of multiple length of data integration from 2ms to 8ms, the processing times consumed by the fastest non-coherent acquisition method are only 25.87% to 1.52% in a single search, and 34.76% to 1.06% in a global search of those in the coherent acquisition. However, coherent acquisition also demonstrates its better performance in the acquisition gain, and in the case of 8ms of data integration it is 4.23 to 4.41 dB higher than that in the non-coherent approaches. Finally, an applicable scheme of combining coherent and non-coherent acquisition approaches in the development of a real-time Software GPS receiver in the University of Tokyo is provided.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제22권12호
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• pp.632-645
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• 2016

엔터프라이즈 환경의 시스템은 다양한 시스템을 활용하여 업무를 처리하고, 인터페이스 시스템을 이용하여 메시지를 교환한다. 인터페이스 통신 기반의 환경에서는 업무 복잡도가 증가할수록 많은 시스템과 인터페이스 시스템이 연계한다. 시스템 연계도가 증가할수록 개발 투입 인력이 증가하며, 이에따라, 정보 불일치 발생, 표준 미 준수 등 다양한 개발위험이 발생한다. 본 제안은 이러한 문제를 해결하기 위해 메시지 기반의 인터페이스 시스템의 정보를 집중, 관리하는 시스템을 제안한다. 시스템을 통해 인터페이스 시스템의 정보 통합 관리, 메시지 정보 배포, 표준 코드를 생성, 위험 관리 및 회피 방법을 제안한다. 제안된 시스템을 통해 개발환경의 정보 불일치 방지, 위험의 분석 및 회피, 자동 정보 배포 및 코드 생성이 가능하며, 궁극적으로 개발환경의 효율성 및 위험을 회피 할 수 있다.

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6495-6503
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• 2013

본 논문은 설계도 등 도로점용허가에서 발생하는 정보의 관리를 위한 웹기반의 도로점용시스템 개발에 대해 기술하였다. 도로점용시스템 개발은 도로점용허가 관련 국내외 정보시스템 사례조사, 도로점용허가 업무분석, 도로점용허가 관리대상 정보정의, 시스템 개발 및 적용의 순으로 진행하였다. 도로점용허가 업무분석은 도로법 등 법령조사와 도로관리청의 업무처리 사례를 조사하고, 사용자 요구사항파악을 위해 도로관리청 업무담당자 및 민원인을 대상으로 설문조사를 시행하였다. 도로점용허가 각 업무에서 발생하는 정보의 관리를 위해 정보의 특성을 나타낼 수 있는 정보분류코드를 개발하고, 각 정보간의 위계관계를 고려하여 메타정보를 정의하였다. 정보분류코드 및 메타정보를 기반으로 도로점용허가 업무흐름 및 사용자요구사항을 반영하여 도로점용시스템 개발을 진행하였다. 개발한 도로점용시스템은 일선 도로관리청에 적용하였으며, 종이문서로 관리하던 도로점용허가 정보를 전자문서로 관리하게 됨에 따라 도로관리청의 도로점용허가 도서 관리업무 개선과 대국민 민원행정서비스의 품질이 향상될 것으로 기대된다.

• 융합보안논문지
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• 제18권5_1호
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• pp.19-24
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• 2018

지금까지 오랜 시간 동안 범용 프로세서는 개발자에게 버그 수정을 할 수 있는 도구들을 제공하기 위해 전용 하드웨어/소프트웨어 트레이싱 모듈을 제공했다. 전용 하드웨어 트레이서는 성능 분석 및 디버깅에 모두 사용되는 막대한 양의 데이터를 로그로 실시간으로 생성한다. 프로세서 트레이스 (PT)는 CPU에서 실행되는 분기를 추적하는 Intel CPU를 위한 새로운 하드웨어 기반 추적 기능으로 최소한의 노력으로 모든 실행 코드의 제어 흐름을 재구성할 수 있다. 이러한 하드웨어 트레이스 기능들은 운영체제에 통합되어 프로파일 링 및 디버깅 메커니즘과의 긴밀한 통합이 가능하게 되었다. 본 논문에서는 윈도우 환경에서 PT가 제공하는 기능을 이용하여 실시간 트레이스 및 악성코드 검출을 위한 기본 데이터를 제공하는 확장된 PT 디코더 구조를 제안하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.111-118
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• 2004

For the precise analysis of high velocity impact problem though FEM with element erosive method, the adequate mesh size and critical equivalent plastic strain(EQPS) is chosen prior to the simulation. In this research, it is strongly required from a standpoint that critical EQPS is used to decide whether perforation occurs or not. The optimization of dual armor plate consisting of 4340 steel and 2024 aluminium against a die steel sphere with high-velocity has been suggested using Lagrangian explicit time-integration code, NET2D. The response surface method based on the design of experiment is utilized for the size optimization. The optimized thickness of each layer, in which perforation does not occur, the strength of multi-layer is maximized and total weight is minimized, is obtained at a constant velocity of a pellet with a designated total thickness.

• 소성∙가공
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• 제10권3호
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• pp.206-213
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• 2001

Dynamic deformation of metallic materials mostly accompanies substantial amounts of deformation heat. Since the flow stress of deformation is sensitive to temperature, implication of heat due to plastic work is essential to the evaluation of constitutive relations. In this study, a series of compression tests were conducted for SAF 2507 super duplex stainless steel at various temperatures and strain rates. The accumulation of plastic work was calculated through numerical integration and converted into the elevation of temperature. Subsequent logarithmic interpolation deduced isothermal flow surfaces, which were primary input data of finite element analysis. Simple closed die forging process was analyzed and optimized with commercial FEM code applying both raw and calibrated material database. The effect of accounting deformation heat was more noticeable in high-speed forming process.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.138-144
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• 1998

The BGK equation, which is the kinetic model equation of Boltzmann equation, is solved using FDDO(finite difference with the discrete-ordinate method) to compute the rarefied flow of monatomic gas. Using reduced velocity distribution and discrete ordinate method, the scalar equation is transformed into a system of hyperbolic equations. High resolution ENO(Essentially Non-Oscillatory) scheme based on Harten-Yee's MFA(Modified Flux Approach) method with Strang-type explicit time integration is applied to solve the system equations. The calculated results are well compared with the experimental density field of NACA0012 airfoil, validating the developed computer code. Next. the computed results of circular cylinder flow for various Knudsen numbers are compared with the DSMC(Direct Simulation Monte Carlo) results by Vogenitz et al. The present scheme is found to be useful and efficient far the analysis of two-dimensional rarefied gas flows, especially in the transitional flow regime, when compared with the DSMC method.

• Structural Engineering and Mechanics
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• 제22권1호
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• pp.107-130
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• 2006

The paper deals with the numerical solution of the dynamic problem of masonry structures. Masonry is modelled as a non-linear elastic material with zero tensile strength and infinite compressive strength. Due to the non-linearity of the adopted constitutive equation, the equations of the motion must be integrated directly. In particular, we apply the Newmark or the Hilber-Hughes-Taylor methods implemented in code NOSA to perform the time integration of the system of ordinary differential equations obtained from discretising the structure into finite elements. Moreover, with the aim of evaluating the effectiveness of these two methods, some dynamic problems, whose explicit solutions are known, have been solved numerically. Comparisons between the exact solutions and the corresponding approximate solutions obtained via the Newmark and Hilber-Hughes-Taylor methods show that in the cases under consideration both numerical methods yield satisfactory results.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.74-87
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• 2015

A numerical parametric study has been accomplished to figure out the effect of grille shape built in a small passenger car on the aerodynamic performance such as drag and mass flow rate through CRFM(Condenser Radiator Fan Module). Three grille opening parameters and three grille mesh parameters are selected and adopted to a simple shape passenger car model. This research will provide a design guideline for grille opening geometry and mesh shape in the grille. FLUENT, which is very well known commercial code, hires k-${\epsilon}$ turbulence model at the driving speed of 110km/h with moving wall boundary condition. A porous media condition is prepared to estimate the pressure drop amount through CRFM parts.