• Proceedings of the Korean Information Science Society Conference
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• 2006.10b
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• pp.562-565
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• 2006

가상기계(Virtual Machine)는 소프트웨어로 제작되어 논리적인 시스템 구성을 갖는 컴퓨터이기 때문에 그 수행 속도와 필요 저장 공간 측면에서 성능이 떨어질 수 밖에 없다. 따라서 가상기계의 성능에 있어서 보다 효율적인 코드로의 최적화가 중요하다. 본 논문에서는 가상기계 코드(Virtual Machine Code) 최적화를 위해 코드를 실행하여 얻을 수 있는 동적 정보인 프로파일링 데이터(Profiling Data)를 정의하고, 프로파일링 시스템을 설계하여 프로파일링 데이터를 가상기계 코드 최적화에 적용 할 수 있는 기반을 마련하였다. 나아가 EVM(Embedded Virtual Machine)에서 실행되는 SIL(Standard Intermediate Language) 코드를 대상으로 프로파일링 시스템을 구현하여 실제 가상 기계 코드에 대하여 프로파일링 데이터를 추출하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.541-544
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• 2005

EVM(Embedded Virtual Machine)은 모바일 디바이스, 디지털 TV 등 임베디드 컴퓨팅 환경에서 동적인 응용프로그램을 실행할 수 있는 가상기계 플랫폼(Virtual Machine Platform)이다. 가상기계를 이용한 응용프로그램은 플랫폼 독립적인 실행 및 효과적인 다운로드 솔루션을 통한 동적인 실행이 가능하다. EVM을 위한 가상기계 코드인 SIL(Standard Intermediate Language)은 언어/기계 독립적으로 설계되었다. 본 논문은 SIL 코드가 시스템 리소스의 제한이 큰 임베디드 시스템상에서 보다 효율적으로 실행되기 위하여 최적화를 수행하였다. 기존의 최적화 방법론에 관한 연구를 통하여 SIL 코드 특성을 고려한 최적화 방법론을 제시하고, 최적화된 코드를 생성하기 위한 코드 최적화기를 설계하고 구현현하였다. SIL 코드 최적화기는 컴파일러에 의해 생성된 SIL 코드를 입력으로 받아 효율적인 코드로 변환하여, 전체 코드의 크기를 줄이고 수행 속도의 개선효과를 얻을 수 있다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.2
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• pp.103-121
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• 2015

In this paper, we briefly review and describe a projection algorithm for numerically computing the two-dimensional time-dependent incompressible Navier-Stokes equation. The projection method, which was originally introduced by Alexandre Chorin [A.J. Chorin, Numerical solution of the Navier-Stokes equations, Math. Comput., 22 (1968), pp. 745-762], is an effective numerical method for solving time-dependent incompressible fluid flow problems. The key advantage of the projection method is that we do not compute the momentum and the continuity equations at the same time, which is computationally difficult and costly. In the projection method, we compute an intermediate velocity vector field that is then projected onto divergence-free fields to recover the divergence-free velocity. Numerical solutions for flows inside a driven cavity are presented. We also provide the source code for the programs so that interested readers can modify the programs and adapt them for their own purposes.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.51-56
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• 1996

In a NNP (Nuclear Power Plant) severe accident, radionuclides are dispersed into the air. The official regulatory institute, KINS (Korea Institute of Nuclear Safety), has been authorized and developing Computerized technical Advisory system for the Radiological Emergency preparedness (CARE). In this paper, in line with the CARE system, we presented the result of a modularized intermediate-level emergency dose assessment computer code. The RADCON (RADiological CONsequence analysis) version 3.0, which is operable on PC, is developed for simulating emergency situation by considering continuous washout phenomena, and provide a function of effective emergency planning. The source files are coded by using C language in order to increase the compatibility with the other computer system and modularized to adjust the functions and characteristics of each module fer easy understanding and further modification.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.49.3-50
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• 2016

Two major radiative transfer (RT) techniques have been developted to model late-type galaxies: approximate RT and Monte Carlo (MC) RT. In the approximate RT, first proposed by Kylafis & Bahcall, only two terms of unscattered (direct) and single-scattered intensities are computed and higher-order multiple scattering components are approximated, saving computing time and cost compared to MC RT. However, the approximate RT can yield errors in regions where multiple scattering effect is significant. In order to examine how significant the errors of the approximate RT are, we compare results of the approximate RT with those of SKIRT, a state-of-the-art MC RT code, which is basically free from the approximation errors by fully incorporating all the multiple scattered intensities. In this study, we present quantitative errors in the approximate RT for late type galaxy models with various optical depths and inclination angles. We report that the approximate RT is not reliable if the central face-on optical depth is intermediate or high (${\tau}_V$ > 3).

• ETRI Journal
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• v.26 no.1
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• pp.21-26
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• 2004

This paper proposes a new architecture for a Viterbi decoder with an efficient memory management scheme. The trace-back operation is eliminated in the architecture and the memory storing intermediate decision information can be removed. The elimination of the trace-back operation also reduces the number of operation cycles needed to determine decision bits. The memory size of the proposed scheme is reduced to 1/($5{\times}$ constraint length) of that of the register exchange scheme, and the throughput is increased up to twice that of the trace-back scheme. A Viterbi decoder complying with the IS-95 reverse link specification is designed to verify the proposed architecture. The decoder has a code rate of 1/3, a constraint length of 9, and a trace-forward depth of 45.

• Structural Engineering and Mechanics
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• v.54 no.4
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• pp.741-754
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• 2015

This study evaluates prediction models for three EDPs (engineering demand parameters) using data from three symmetrical structures with RC walls designed according to the currently enforced Romanian seismic design code P100-1/2013. The three analyzed EDPs are: the maximum interstorey drift, the maximum top displacement and the maximum shear force at the base of the RC walls. The strong ground motions used in this study consist of three pairs of recordings from the Vrancea intermediate-depth earthquakes of 1977, 1986 and 1990, as well as two other pairs of recordings from significant earthquakes in Turkey and Greece (Erzincan and Aigion). The five pairs of recordings are rotated in a clockwise direction and the values of the EDPs are recorded. Finally, the relation between various IMs (intensity measures) of the strong ground motion records and the EDPs is studied and two prediction models for EDPs are also evaluated using the analysis of residuals.

• Earthquakes and Structures
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• v.23 no.5
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• pp.463-472
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• 2022

Reinforced concrete (RC) beam column joints (BCJ) have mostly exhibited poor seismic performance during several past earthquakes, typically due to the poor-quality concrete or lack of reinforcement detailing typical of pre-code design practice. The present study is motivated towards numerical simulation and seismic fragility assessment of one such RC-BCJ. The BCJ is loaded to failure and strengthened using Ultra High Performance-Hybrid Fiber Reinforced Concrete (UHP-HFRC) jacketing. The strengthening is performed for four different BCJ specimens, each representing an intermediate damage state before collapse. viz., slight, moderate, severe, and collapse. From the numerical simulation of all the BCJ specimens, an attempt is made to correlate different modelling and design parameters of the BC joint with respect to the damage states. In addition, seismic fragility analysis of the original as well as the retrofitted damaged BCJ specimens show the relative enhancement achieved in each case.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.13-14
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• 2009

Intermediate Representation(IR)은 컴파일러가 Target code 를 생성하기까지의 중간 단계에서 프로그램을 표현하는 수단이다. 본 논문에서는 컴파일러의 IR을 직접 Simulation 해서 각종 profiling information을 수집하여 프로그램의 성능 향상에 도움을 줄 수 있는 IR Simulator를 제안하고자 한다. 더 나아가 IR Simulator를 위한 Data structure와 Interface는 Target Simulation에도 재사용이 가능하도록 고안되었기 때문에 재겨냥성 컴파일러의 Target Simulator를 자동으로 생성하는 연구를 진행하고 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.265-268
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• 2011

자바는 개발환경의 편리성과 재사용성, 이식성으로 다양한 시스템 환경에서 사용한다. 그러므로 자바는 오류 없이 안전하게 실행하는 것이 중요하다. 하지만 자바 바이트 코드를 통한 자바의 안전한 실행에 대한 검증은 스택코드, 코드의 정보부족 등의 이유로 검증을 어렵게 한다. 본 논문에서는 자바 바이트코드의 문제점을 해결하여 검증을 수행하는데 적합한 중간표현 언어를 소개한다. 중간표현 언어는 스택리스코드로 구현되며, 모든 명령어의 정보를 담고 있다. 이를 통해, 자바 바이트코드를 통한 검증을 수행할 것이다.