• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5465-5470
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• 2012

FPGA(Field Programmable Gate Array) devices are widely used due to their merits in circuit development time, and development cost. Among various FPGA technologies, SRAM-based FPGAs have large cell capacity so that they are attractive for complex circuit design and their reconfigurability. However, they are weak in space environment where radiation energy particles cause Single Event Upset(SEU). In this paper, we designed a controller supervising SRAM-based FPGA to protect configuration memory inside. The controller is implemented on an Anti-Fusing FPGA. Radiation test was performed on the implemented computer board and the result show that our controller provides better SEU-resilience than TMR-only system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.323-329
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• 2018

In this paper, we implemented an access control system that only allows specific users to use documents in Hangul document system. The system structure designed in this paper is to transform header information of Hangul document by analyzing the structure of Hangul document. By modifying the function of a specific field of the header information in Hangul document, it prevents users that do not have data for the modified information to open and view the document. By controlling the access rights to important Hangul documents, it is possible to manage Hangul files more safely. In this paper, the actual design of information was implemented and experiments were carried out. Results of the experiment confirmed that the access control system is operated in normal way. In this paper, we implemented an access control system that only allows specific users to use documents in Hangul document system.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.1 s.12
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• pp.41-50
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• 2004

The objective of this study is to investigate the feasibility of the developed Fuzzy control techniques in dam operation. The simulated results for the 1984, 1990, and 1995 flood events are compared with historical operation results in the view of flood control and disaster prevention. The three models developed in this study determine the outflows based on the two conditions the first one is to consider only two inputs such as reservoir water level and inflow, for operation of the existing situations, the second one is that the possible maximum discharge from each dam does not exceed the allowable design maximum discharge for disaster prevention in downstream area. As the results, it was shown that the suggested models based on Fuzzy control technique could reduce both the peak water level and the maximum peak discharge compared with the historical operation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1697-1705
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• 2022

The safety of marine construction workers and marine pollution problems are occurring due to large-scale offshore construction. In particular, underwater construction work in the sea has a higher risk than other work, so it is necessary to apply an unmanned alternative system that considers the safety of the workers. In this paper, the ROV system for offshore construction has been developed for underwater unmanned work. A monitoring system was developed for position control through the control of underwater propellants, pneumatic gripper, and monitoring of underwater work. As a result of the performance evaluation, the underwater movement speed of the ROV was evaluated to be 0.89 m/s, and it was confirmed that the maximum load of the pneumatic gripper was 80 kg. In addition, the network bandwidth required for underwater ROV control and underwater video streaming was evaluated to be more than 300Mbps, wired communication at 92.7 ~ 95.0Mbit/s at 205m, and wireless communication at 78.3 ~ 84.8Mbit/s.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.813-823
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• 2020

Purpose: In order to maximize the stability and productivity of the work through simulation prior to high-risk facilities and high-cost work such as dismantling the facilities inside the reactor, we intend to use digital twin technology that can be closely controlled by simulating the specifications of the actual control equipment. Motion control errors, which can be caused by the time gap between precision control equipment and simulation in applying digital twin technology, can cause hazards such as collisions between hazardous facilities and control equipment. In order to eliminate and control these situations, prior research is needed. Method: Unity 3D is currently the most popular engine used to develop simulations. However, there are control errors that can be caused by time correction within Unity 3D engines. The error is expected in many environments and may vary depending on the development environment, such as system specifications. To demonstrate this, we develop crash simulations using Unity 3D engines, which conduct collision experiments under various conditions, organize and analyze the resulting results, and derive tolerances for precision control equipment based on them. Result: In experiments with collision experiment simulation, the time correction in 1/1000 seconds of an engine internal function call results in a unit-hour distance error in the movement control of the collision objects and the distance error is proportional to the velocity of the collision. Conclusion: Remote decomposition simulators using digital twin technology are considered to require limitations of the speed of movement according to the required precision of the precision control devices in the hardware and software environment and manual control. In addition, the size of modeling data such as system development environment, hardware specifications and simulations imitated control equipment and facilities must also be taken into account, available and acceptable errors of operational control equipment and the speed required of work.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.710-713
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• 2011

본 논문에서는 교량의 주부재에 교량용 고성능강을 적용하여 설계해 본 후, 이러한 적용이 교량의 진동사용성에 어떠한 영향을 미치는지 그 영향을 분석해 보고자 한다. 최근들어 교량상의 구조적인 결함이 없더라도 진동에 의해 교량을 통행하는 운전자나 보행자에게 불안감을 주는 경우가 빈번히 발생하기 때문에 진동사용성이란 문제는 보다 부각되고 있다. 특히 고성능강이 개발되고 이를 교량에 적용하게 되면 허용응력의 증가로 이어져 거더의 형고감소를 가능하게 한다. 그러나 이러한 형고의 감소는 교량의 휨강성을 저하시켜 사용성의 악화를 초래할 것이란 예측이 있었다. 따라서 본 연구는 차량-교량의 상호작용에 의해 발생하는 진동영향의 분석을 위해 유한요소해석 프로그램인 Abaqus 6.10을 이용해 수치해석을 수행하였고 이때의 진동영향을 평가했다. 차량-교량 상호작용의 해석을 위해 ASSHTO 기준의 HS 20-44 차량을 해석 대상교량 위로 주행하도록 하였다. 해석대상교량은 인장강도가 각각 600MPa와 800MPa인 교량용 고성능강재(HSB, High-Performance Steel for Bridge)를 적용하여 주거더를 설계한 강플레이트 거더교를 대상으로 삼았다. 차량이 교량을 통과하면서 발생하는 교량의 경간 중앙부에서 발생하는 수직진동의 시간이력을 분석하여 진동평가의 기준으로 삼았다. 해석결과 HSB600과 HSB800으로 각각 설계된 교량은 가속도이력에서는 큰 차이가 없었으나 변위이력에서는 HSB800적용 교량이 진동사용성 측면에서 매우 불리한 거동을 보였다. 따라서 고성능강 적용에 따른 교량의 진동사용성을 평가하기 위해서는 변위를 기준으로한 평가가 이루어져야하며, 변위의 진동을 제어하기 위한 방안이 모색되어야 할 것으로 판단된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.335-341
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• 2016

In this paper, we propose the method of controling the turns of a receiving coil for the matching directly to the receiver input impedance(typically $50{\Omega}$) with a maximum wireless power transfer(WPT) efficiency. Based on the presented the expression of the optimum load depending on a system figure of merit, number of the turns of a receiving coil, and proximity effect between conducting lines, the theoretical efficiencies have been compared with the measured ones with a good agreement. The results of this work may be used to realize a allowable maximum efficiency with a simple and low-profile 2-coil WPT system not requiring a separate feeding loop.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.67-75
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• 2014

A full-scale static test for a composite structure small aircraft (KC-100) was conducted in the KARI. The test includes 15 full-scale test and 7 local test conditions. Test requirements with test schedule, test article with dummy structures, test load generation, test system, and equipment are introduced for the test. Test load data of the 1st test condition(U1) was analyzed to evaluate an accuracy of load control for the test. The analysis results show that load data obtained during test were within tolerance of Static Null Pacing Error(SNPE) and the error value of load control was 8.6N. The error of load controls for the full-scale static test using dozens of actuators was calculated by a method suggested by authors. Test data for all other test conditions is also shown in this paper. Finally, reactions measured from restraint system of the U1 test condition show that the reaction changes as load increment. The factors which may change the change of reactions for a full-scale static test are introduced in this study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.1015-1026
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• 2002

As per increasing research interest in the field of collaborative computing in recent year, the importance of security issues on that area is also incrementally growing. Generally, the persistency of collaborative system is facilitated with conventional authentication and cryptography schemes. It is however, hard to meet the access control requirements of distributed collaborative computing environments by means of merely apply the existing access control mechanisms. The distributed collaborative system must consider the network openness, and various type of subjects and objects while, the existing access control schemes consider only some of the access control elements such as identity, rule, and role. However, this may cause the state of security level alteration phenomenon. In order to handle proper access control in collaborative system, various types of access control elements such as identity, role, group, degree of security, degree of integrity, and permission should be taken into account. Futhermore, if we simply define all the necessary access control elements to implement access control algorithm, then collaborative system consequently should consider too many available objects which in consequence, may lead drastic degradation of system performance. In order to improve the state problems, we propose a novel access control framework that is suitable for the distributed collaborative computing environments. The proposed scheme defines several different types of object elements for the accessed objects and subjects, and use them to implement access control which allows us to guarantee more solid access control. Futhermore, the objects are distinguished by three categories based on the characteristics of the object elements, and the proposed algorithm is implemented by the classified objects which lead to improve the systems' performance. Also, the proposed method can support scalability compared to the conventional one. Our simulation study shows that the performance results are almost similar to the two cases; one for the collaborative system has the proposed access control scheme, and the other for it has not.

• Journal of the Korean Institute of Gas
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• v.24 no.1
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• pp.41-48
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• 2020

This study performed a quantitative risk assessment for hydrogen-CNG complex refueling stations. Individual and societal risks were calculated by deriving accident scenarios that could occur at hydrogen and CNG refueling stations and by considering the frequency of accidents occurring for each scenario. As a result of the risk assessment, societal risk levels were within the acceptable range. However, individual risk has occurred outside the allowable range in some areas. To identify and manage risk components, high risk components were discovered through risk contribution analysis. High risks at the hydrogen-CNG complex refueling station were large leakage from CNG storage containers, compressors, and control panels. The sum of these risks contributed to approximately 88% of the overall risk of the fueling station. Therefore, periodic and intensive safety management should be performed for these high-risk elements.