• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.6
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• pp.311-321
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• 2012

When developing a CPS, since it is nature of CPS to interact with a physical system, CPS should be verified during its development process by real-time simulation supporting timely interactions between the simulator and existing implemented hardwares. Furthermore, when a part of a simulated system is implemented to real hardwares, i.e., incremental development, the simulator should aware changes of the simulated system and apply it automatically without manual description of the changes for effective development. For this, we suggest a real-time simulation framework including the concept of 'port' which abstracts communication details between the tasks, and a scheduling algorithm for guaranteeing 'real-time correctness' of the simulator.

• Journal of the Korea Convergence Society
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• v.10 no.3
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• pp.135-140
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• 2019

This study is aimed at analyzing cyber motion sickness factors focus on virtual environment-based VR and real-world VR. First literature study of cyber motion sickness, 3D animations and documentaries were conducted. As a measurement tool for the degree of motion sickness, the symptom values were measured in a standardized SSQ (Simulator Sickness Questnire) questionnaire. Following the measurement, an in-depth interview was conducted based on the SSQ questionnaire. The results are as follows, First, actual environment based VR caused bigger cyber motion sickness, second, values of strong saturation of VR contents cause cyber motion sickness. This study is expected to be used as design guidelines for configuring VR early contents and to be used for cyber motion sickness research.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.181-188
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• 2014

Heterogeneous physical systems and computational devices are incorporated on a large-scale in a CPS (cyber-physical system) environment. Simulations can be useful for the reliable behaviors of CPSs. Time synchronization is one of major technical issues for the simulations. In the CPS, distributed systems control themselves by interacting with each other during runtime. When some simulation models have high complexity, wrong control commands as well as incorrect data can be exchanged due to the time error. We propose a time synchronization algorithm for the hybrid model that has characteristics of both continuous time systems and discrete event systems. In addition, we develop a CPS simulator based on our algorithm. For the verification of the algorithm and the execution of the simulator, we develop an example hybrid model and simulate considering user controls as well as interactions among the distributed systems.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.4
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• pp.211-217
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• 2014

Cyber-Physical Systems(CPS) that mostly provides safety-critical and mission-critical services requires high reliability, so that system testing is an essential and important process. Hardware-In-the-Loop Simulation(HILS) is one of the extensively used techniques for testing hardware systems. However, most conventional HILS has problems that it is difficult to support a distributed operating environment and to reuse a HILS platform. In this paper, we introduce EcoHILS(ETRI CPS Open Human-Interactive hardware-in-the-Loop Simulator) in order to test CPS effectively. Moreover, feasibility tests and performance tests of EcoHILS are performed to confirm its effectiveness.

• International Journal of Advanced Culture Technology
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• v.8 no.4
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• pp.299-305
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• 2020

With the advancement of the 4th Industrial Revolution(4IR), microprocessor education is on the rise due to the explosive demand for IoT (Internet of Things) and M2M devices. However, it is difficult due to many constraints to efficiently transfer training on hardware assembly and implementation through online training. Thus, we developed a cost-effective online content based on Arduino simulations, Atmel Studio 7, and WinAvr simulator that are required for the utilization of AVR 128. These Camtasia videos overcame the limitation of theory focused on-line education by visually introducing the practical utilization of an actual AVR 128. In this paper, the proposed educational content was provided to university students, and the results of student feedback show that it has a strong effect.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.255-258
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• 2010

계산 집약적인 다양한 응용 프로그램들이 서로 유기적으로 통합되어 결과를 도출하는 컴퓨팅 환경에서는 응용들을 관리하기 위한 효과적인 워크플로우 기법과 컴퓨팅 자원관리 기술이 필요하다. 본 논문에서는 인체 생리기능 단위들을 모사한 신약개발 시뮬레이션을 지원하기 위한 OSICC (e-Organ Simulator-Integrated Cyber Computing) 시스템의 협업 기능을 평가한다. 제안하는 시스템은 워크플로우 관리자를 이용하여 시뮬레이션의 객체간 자원관리를 최적화하고 있으며, 프로토타입으로 구현되어 협업 컴퓨팅을 지원하는 OSICC 시스템에서 효율성을 확인하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.6
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• pp.1021-1031
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• 2023

State-sponsored cyber attacks are highly impactful because they are carried out to achieve pre-planned goals. As a defender, it is difficult to respond to them because of the large scale of the attack and the possibility that unknown vulnerabilities may be exploited. In addition, overreacting can reduce the availability of users and cause business disruption. Therefore, there is a need for a response policy that can effectively defend against attacks while ensuring user availability. To solve this problem, this paper proposes a method to collect the number of processes and sessions of defense assets in real time and use them for learning. Using this method to learn reinforcement learning-based policies on a cyber attack simulator, the attack duration based on 100 time-steps was reduced by 27.9 time-steps and 3.1 time-steps for two attacker models, respectively, and the number of "restore" actions that impede user availability during the defense process was also reduced, resulting in an overall better policy.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.1-9
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• 2004

In this study, we presented a research about the development of the phoropter simulation program for education using the 3-D virtual reality in order to study the ophthalmic optics rather efficiently. Especially, by putting the facility such as the refractive error analysis of the eyeball in the cyber tutor inside, we have made the learner to learn and confirm the present situation of refractive correction through refractive power of principal meridians. By organizing the system which induces the active involvement of the learner and showing the result of the execution to the learner intuitively, the implementation of the more efficient education-environment can be possible. Consequently, it is expected that this program will be greatly helpful for the optician training as well as the ophthalmic optics education. As a next phase of study, we will develope the development technique of this simulator more and extend the cyber tutor contents more and make the web service version of this program to be provided through the internet network in order to inspire the learning desire of the learner more and more.

• Journal of the Korean Society of Systems Engineering
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• v.14 no.2
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• pp.73-82
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• 2018

In this work, a hardware based cryptographic module for the cyber security of nuclear power plant is developed using a system engineering approach. Nuclear power plants are isolated from the Internet, but as shown in the case of Iran, Man-in-the-middle attacks (MITM) could be a threat to the safety of the nuclear facilities. This FPGA-based module does not have an operating system and it provides protection as a firewall and mitigates the cyber threats. The encryption equipment consists of an encryption module, a decryption module, and interfaces for communication between modules and systems. The Advanced Encryption Standard (AES)-128, which is formally approved as top level by U.S. National Security Agency for cryptographic algorithms, is adopted. The development of the cyber security module is implemented in two main phases: reverse engineering and re-engineering. In the reverse engineering phase, the cyber security plan and system requirements are analyzed, and the AES algorithm is decomposed into functional units. In the re-engineering phase, we model the logical architecture using Vitech CORE9 software and simulate it with the Enhanced Functional Flow Block Diagram (EFFBD), which confirms the performance improvements of the hardware-based cryptographic module as compared to software based cryptography. Following this, the Hardware description language (HDL) code is developed and tested to verify the integrity of the code. Then, the developed code is implemented on the FPGA and connected to the personal computer through Recommended Standard (RS)-232 communication to perform validation of the developed component. For the future work, the developed FPGA based encryption equipment will be verified and validated in its expected operating environment by connecting it to the Advanced power reactor (APR)-1400 simulator.

• The Journal of Society for e-Business Studies
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• v.3 no.2
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• pp.37-55
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• 1998

This study describes the works on development of a scenario-based WBT system of electronic commerce to introduce and activate electronic commerce in our society because it is mostly required to correctly understand electronic commerce and timely educate its users and technicians for entering into global electronic commerce that binds every commercial area regardless of the borders and nationalities. This system, WBT(Web - Based Training of Electronic commerce), consists of two parts. The one part provides a general concept of EC. This is developed to meet the needs of beginner for EC. The other is a simulator for cyber shopping mall. It is designed for teaching how to shop at cyber shopping mall based on various scenarios. In addition, we can simulate ourselves for EDI, which enables trading partners to conduct routine business transaction, such as purchase orders, invoices and shopping notices with it. Our commitment to the development of this application is consistent with the objectives of being easy to learn electronic commerce and its applications in real world.