• Journal of KIISE:Computing Practices and Letters
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• v.15 no.12
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• pp.1008-1012
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• 2009

Obfuscation is known as one of the most effective methods to protect software against malicious reverse engineering transforming the software into more complicated one with still preserving the original semantic. However, obfuscating a program can increase both code size of the program and execution time compared to the original program. In mobile devices, the increases of code size and execution time incur the waste of resources including the increase of power consumption. This paper has analyzed the effectiveness of some high-level obfuscation algorithms as well as their power consumption with implementing them under an embedded board equipped with ARM processor. The analysis results show that there is (are) an efficient obfuscation method(s) in terms of execution time or power consumption according to characteristics of a given program.

• Tunnel and Underground Space
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• v.21 no.1
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• pp.66-81
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• 2011

In this study, it was aimed to develop a thermal-hydraulic-mechanical coupled fracture mechanics code that models a fracture initiation, propagation and failure of underground rock mass due to thermal and hydraulic loadings. The development was based on a 2D FRACOD (Shen & Stephasson, 1993), and newly developed T-M and H-M coupled analysis modules were implemented into it. T-M coupling in FRACOD employed a fictitious heat source and time-marching method, and explicit iteration method was used in H-M coupling. The validity of developed coupled modules was verified by the comparison with the analytical result, and its applicability to the fracture initiation and propagation behavior due to temperature changes and hydraulic fracturing was confirmed by test simulations.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.401-411
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• 2006

We propose an optical encryption/decryption technique for a security system based on 2-step phase-shifting digital holography. Phase-shilling digital holography is used for recording phase and amplitude information on a CCD device. 2-step phase-shifting is implemented by moving the PZT mirror with phase step of 0 or ${\pi}/2$. The binary data and the key are expressed with random code and random phase patterns. The digital hologram is a Fourier transform hologram and is recorded on CCD with 256 gray level quantization. We remove the DC term of the digital hologram fur data reconstruction, which is essential to reconstruct the original binary input data/image. The error evaluation fer the decrypted binary data is analyzed. One of errors is a quantization error in detecting the hologram intensity on CCD, and the other is generated from decrypting the data with the incorrect key. The technique using 2-step phase-shifting holography is more efficient than a 4-step method because 2-step phase-shifting holography system uses less data than the 4-step method for data storage or transmission. The simulation shows that the proposed technique gives good results fur the optical encryption of binary information.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.86-88
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• 2012

코드 포인터 공격을 이용한 제어 흐름은 실행 중에 간접 분기의 무결성을 검사하는 것으로 보호할 수 있다. 간접 분기는 반복되는 목적지 주소로의 분기인 경우가 많지만, 목적지 주소는 실행 시간에만 알 수 있기 때문에 여러 가지 예외적인 상황을 적절히 대처할 방법이 필요하다. 본 논문에서는 동적 이진 계측화를 활용하여 실행 중 발생하는 간접 분기를 분석하고, 수집한 주소들을 빠르게 비교하는데 효과적인 주소 비교 기법들을 제시한다. 또한 각 기법을 비교하여 프로그램에 따라 주소 비교의 효율성을 극대화하는 방안을 모색하였다. 이러한 기법을 통해 간접 분기가 야기하는 여러 문제점에서부터 보안 분야에 이르기 까지 활용 범위를 넓힐 수 있을 것으로 기대한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.181-187
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• 2013

Performance of DI diesel engine with high fuel injection method is directly related to its emission characteristics and fuel consumption. In this study, numerical model of 3rd generation piezo-driven injector was designed to analyze the hydraulic performance. Also the injection response characteristics was investigated by using the AMESim simulation code. From this study, it was shown that 3rd generation piezo-driven injector had a faster response and had better control capability due to its hydraulic bypass-circuit that has potential to higher hydraulic characteristics and improved accuracy of injected fuel quantity.

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.263-266
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• 2009

임베디드 시스템을 지원하는 JAVA API를 개발하면 임베디드 시스템을 개발자가 JAVA를 사용함으로서 코드의 재사용, 객체지향 개념의 시스템 개발들을 가능하게 한다. JAVA API를 구현하는데 있어 시스템에 의존적인 부분들이 존재하게 되는데, 이는 native 함수에서 구현한다. 본 논문에서는 리눅스 기반의 임베디드 시스템 디바이스를 제어하기 위한 JAVA API를 구현하는데 있어 플랫폼 독립적인 자바 부분과 의존적인 native 부분으로 나눠 설계 및 구현하였고, 임베디드 시스템 디바이스의 JAVA API를 통한 제어에 초점을 두었다.

• Journal of ILASS-Korea
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• v.17 no.2
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• pp.57-63
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• 2012

For reduction of CO, NOx and soot emission emitted by diesel diffusion combustion, the authors focused on injection actuator to improve fuel availability inside combustion chamber. In this study, it was investigated the internal dynamic characteristics of two-stage injection with diesel injectors with different driving type for the common rail direct injection by using the AMESim simulation code. The analysis parameter defined such as fuel pressure, injection hole's diameter and driven voltage. As the results, it was shown that the piezo-driven injector had a faster response and had better control capability than the solenoid-driven injector. It was found the piezo-driven injector can be utilized effectively as multiple injector than solenoid-driven injector.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.256-259
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• 2003

This paper proposes OPTICAL MARKER fer registering process - one of the 3D measurement process : scan registering - merging - measurement. If the registering work is carried out manually, it can be accompanied with much time and many errors. Because the patterned marker make registering process automatic, many firms use it now. But the physical shape of existing markers is the source of the data loss caused by hiding surface, and the marker arrangement is the source of the time loss. The optical marker proposed in this paper has marker generator, organized a large number of binary coded control laser diode, separate from 3D scan object. So, it does not take much time for the marker disposition, and it is not the origin of the data loss, and the binary coded laser information make the auto-registering possible.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.233-238
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• 2011

In piping design of nuclear power plant facilities, the load stress according to self-weight is important for design values in test run(shutdown and starting). But sometimes it needs more studies, such as seismic analysis of an earthquake of power plant area and fatigue life and stress of thermal expansion and anchor displacement in operating run. In this paper, seismic evaluations were performed to nuclear piping system of Shin-Kori NO. 3&4 being built in Pusan lately. Results of seismic analysis are evaluated on basis of KEPIC MN code. The structural integrity on RCB piping system was proved.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1997.10a
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• pp.93-98
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• 1997

도시폐기물의 효율적인 소각 처리를 위해서 폐기물 처리량 50 ton/day의 화격자 소각로를 대상으로 화학반응을 고려하여 연소실 내부의 열유동 현상을 전산모사하였다. 수치해석 프로그램으로 상용코드인 PHOENICS를 사용하여 3차원 모사를 하여 실험으로 파악할 수 없는 연소실 내부의 유동 및 폐기물과 산화제와의 반응을 계산하였다. 건조부, 주연소부, 후연소부에 1차연소용공기, 연료의 분포 및 폐기물의 발열량이 노내 열유동 현상에 미치는 영향을 조사하였다. 1차연소용 공기의 분포에 따라 노내 유동장의 형태에 변화가 있었으며, 벽면에서의 복사열전달을 고려한 경우 2차연소실과 출구근처에서 온도분포가 파일롯트 플랜트 실험결과와 잘 일치하는 r서으로 나타났다.