• Review of KIISC
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• v.27 no.2
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• pp.34-40
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• 2017

제어시스템(발전시설, 전력시설, 교통시설 등)은 생산성, 가용성, 안전성을 목적으로 다양한 제어기기들로 구성되며, 물리적으로 다양한 위치에 분산되어 운영되고 있다. 그리고 안전성과 가용성을 유지하기 위해 시스템 도입 시 기존 시스템에 영향을 미치지 않는지 검증을 수행 후 시스템을 도입한다. 이러한 이유로 신규 기술의 도입이나, 기기의 변경이 자유롭지 않다. 이와 같은 제어시스템의 특성으로 인해 현재 증가되고 있는 제어시스템 사이버공격에 대한 보안대책 또는 기술들의 적용이 쉽지 않아 사이버공격에 취약한 상황이다. 제어시스템은 상위 시스템의 제어 명령을 통해 하위 제어기기 또는 필드기기를 제어하는 형태로 제어 명령의 무결성 유지가 특히 중요하다. 이는 곧 제어시스템에 환경에 접근한 공격자가 인가되지 않은 장비를 제어시스템에 연결하고, 악성 제어명령을 전송하게 된다면 제어기기는 이를 인지하지 못하고 정지되거나 오작동을 유발 할 수 있다는 것을 의미한다. 본 논문에서는 제어시스템 내 제어명령의 무결성 유지를 위해 임베디드 Add-on 단말을 통해 OTP 값을 생성, 전달, 검증하는 방안을 제안한다. 해당 방안은 상위노드와 하위노드 사이에 Add-on 장치를 두어 상위노드에서 제어명령 발생 시, 제어명령에 OTP값을 통해 캡슐화하고 하위노드로 전달한다. Add-on 장비는 일반 IT시스템과 상이한 제어시스템의 특성에 맞게 고안되었으며 제어시스템 내에 발생되는 제어명령 위변조, 제어명령 재사용 공격 등을 차단 할 수 있다.

• Journal of KIISE:Software and Applications
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• v.26 no.5
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• pp.692-701
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• 1999

수퍼스칼라(superscalar)나 VLIW 와 같은 명령어 수준 병렬화(ILP) 프로세서의 성능을 극대화하는 과감한 명령어 스케쥴링은 소프트웨어 파이프라이닝과같은 스케쥴링 과정을 거치면서 일반적인 복사 명령어 제거 기법으로 없앨 수 없는 서로 간섭하는 복사 명령을 많이 만들어내는데 루프 내부에 생성된 이러한 복사명령은 적절한 루프 펼침을 수행하여 간섭관계를 없앰으로서 제거할 수 있다. 본 논문에서는 이와 같이 루프 펼침이 수행된 루프 내부의 복사명령을 제거하는 기법으로 그래프 컬러링 상에 구현한 낙관적 융합기법을 제안한다. 그래프 컬러링에서의 융합기법은 간선의 개수가 많은 노드를 만들어 낼수 있으므로 채색성에 부정적인 영향을 주는 것으로 알려져 왔으나 본 기법에서는 융합되는 노드에 동시에 간섭하는 노드의 간선의 수가 줄어드는 긍정적인 영향을 최대한 이용하여 채색성을 높이고 융합된 노드에 대한 실제 버림(spill)이 일어나는 경우 유효 범위 분절(live range splitting)을 통하여 버림의 부담을 최대한 줄이도록 하였으며 이를 VLIW 스케쥴링 된 SPEC 정수벤치마크 루프내부의 복사 명령 제거에 적용한 결과 제거 가능한 복사 명령의 99%를 제거하면서도 버림명령은 다른 융합 기법과 비교하여 가장 적게 발생하는 우수한 결과를 얻을수 있었다.

• Journal of Korea Multimedia Society
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• v.12 no.4
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• pp.512-520
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• 2009

Maximum intensity projection (MIP) is a volume rendering method which extracts maximum values along the viewing direction through volume data. It visualizes high-density structures, such as angio-graphic datasets so that it is frequently used in medical imaging systems. We have proposed an efficient two-step MIP acceleration method that uses the recent CPUs. First, we exploited SIMD instructions to reduce conditional branch instructions which take up a considerable part of whole rendering process, so that we improved rendering speed. Second, we proposed a new method, which accesses volume and image data successively by modifying the shear-warp rendering. This method improves memory access patterns so that cache misses are reduced. Using the current CPUs, our method improved the rendering speed by a factor of 7 than that of the shear-warp rendering.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.100-109
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• 2005

This paper introduce electromagnetic environmental requirements, test procedures and test results for the Command Telemetry Unit(CTU), which is engineering qualification model for communication satellite in geostationary earth orbit. Also, through debugging of the CTU during the Electro Magnetic Compatibility(EMC) tests, this paper evaluates characteristics of noise generated by the CTU. It is also obtained that better EMC performance can be acquired by improving electrical power converter module of the CTU.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6B
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• pp.544-552
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• 2003

This paper suggests an instruction code sufficiency algorithm preventing data collision when multiple transponders attempt to connect in the radio frequency identification system. Conventional time domain procedure generates unconditional collision. On the other hand, this algorithm prevents data collision by transmitting data when it meets instruction code. When multiple transponders are transmitting data coincidently, they exploit desired data with using difference of arrival time generated by recognition distance, respectively. As a result of simulation, utilizing the wireless recognition system, adopting the suggested algorithm, operating in 13.56MHz frequency band, it verify that there is Anti-collision and data loss by ensuring transmission time difference of one bit by adopting this algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.6
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• pp.429-437
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• 2019

This paper deals with a ZEM (Zero-Effort-Miss) based guidance law for the interception of moving targets and characteristics of the guidance law according to time-to-go estimation methods. To derive the ZEM vector feedback guidance command, we introduce a polynomial function with unknown coefficient, and then we determine the coefficient to satisfy initial and terminal constraints. Since the directions of the guidance command and ZEM vectors are adjusted by the time-to-go, general time-to-go estimation methods are proposed, which can generate the vertical and horizontal guidance commands with respect to an arbitrary reference frame. By performing various numerical simulations, the performance and characteristics of the proposed methods are investigated.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.55-62
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• 2014

FTSR(Flight Termination System Receiver) is a device that receives a ground command signal to abort a flight mission when abnormal conditions occur in the space launch vehicle. The secure tone command message shall consist of a series of 11 character tone pattern. Each character consists of the sum of two tones which taken from a set of 7 tones defined by IRIG(Inter-Range Instrumentation Group) in the audio frequency range. The MHA(Modified High alphabet) command adds a security feature to the secure tone command by using the predefined difference code. In order to check the function and performance of MHA FTSR, which is under development, for KSLV-II, the testbed should have functions of RF signal generation, receiver's output port monitoring, RS-422 communication and test data management. In this paper, we first briefly introduce MHA command and FTSR interface, and then show the LavVIEW based testbed include its H/W configuration, S/W implementation and test results.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.5
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• pp.721-736
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• 2023

The Command and Control Framework was developed for penetration testing and education purposes, but threat actors such as cybercrime groups are abusing it. From a cyber threat hunting perspective, identifying Command and Control Framework servers as well as proactive responding such as blocking the server can contribute to risk management. Therefore, this paper proposes a methodology for tracking the Command and Control Framework in advance. The methodology consists of four steps: collecting a list of Command and Control Framework-related server, emulating staged delivery, extracting botnet configurations, and collecting certificates that feature is going to be extracted. Additionally, experiments are conducted by applying the proposed methodology to Cobalt Strike, a commercial Command and Control Framework. Collected beacons and certificate from the experiments are shared to establish a cyber threat response basis that could be caused from the Command and Control Framework.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.5
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• pp.147-156
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• 2022

Industrial control systems that manage and maintain various industries were mainly operated in closed environment without external connection, but with the recent development of the Internet and the introduction of ICT technology, the access to the industrial control system of external or attackers has become easier. Such incorrect approaches or attacks can undermine the availability, a major attribute of the industrial control system, and violation of availability can cause great damage. In this paper, when issuing commands in an industrial control system, a verification group is formed using a random list to verify and execute commands, and a trust score technique is introduced that applies feedback to the verification group that conducted verification using the command execution result. This technique can reduce overhead generated by random generation in the process of requesting command verification, give flexibility to the verification process, and ensure system availability. For the performance analysis of the system, we measured the time and gas usage when deploying a smart contract, gas usage when verifying a command. As a result, we confirmed that although the proposed system generates a random list compared to the legacy system, there was little difference in the time when it took to deploy smart contract and that the gas used to deploy smart contract increased by about 1.4 times in the process of generating a random list. However, the proposed system does not perform random operations even though the operation of command verification and confidence score technique is performed together during the command verification process, thus it uses about 9% less gas per verification, which ensures availability in the verification process.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.863-872
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• 2017

Digital material transferred to the court for litigation shall be disposed by the procedure in the court records management regulations and the digital material collected by the investigator in order to prove the suspect's allegation shall be disposed by the Supreme Public Prosecutor's Regulation No.876(digital material's regulation of collection, examine and management). the court ordered the disposal of digital material that is the subject of litigation based on the related laws when criminal lawsuits and civil lawsuits are finalized. however, there is no specific procedure to enforce the disposal order of the court, and the enforcement order stipulates that the enforcement agent is not a professional officer who has proven expertise but a related public official. there is a problem in the enforcement of digital material that the court ordered to disposal because it is not specified. therefore, this is paper proposes a procedure for effectively enforcing the court's order to revoke digital material.