• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.219-226
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• 2020

Nondestructive testing is one of the most commonly used quality inspection methods for evaluating ship structures. However, accurate evaluation is dif icult because various composite materials, such as reinforcements, resin, and fiber-reinforced plastics (FRPs), are used in hulls, and manufacturing quality differences are likely to exist owing to the fabrication environment and the skill level of workers. This possibility is especially true for FRP ships because they are significantly thicker than other structures, such as automobiles and aircraft, and are mainly manufactured using the hand lay-up method. Because the density of a material is a critical condition for ultrasonic inspection, in this study, a hull plate was selected from a vessel manufactured using e-glass fiber, which is widely used in the manufacture of FRP vessels with the weight fraction of the glass content generally considered. The most suitable ultrasonic testing conditions for the glass FRP hull plate were investigated using a pulse-echo ultrasonic gauge. A-scans were performed with three probes (1.00, 2.25, and 5.00 MHz), and the results were compared with those of the hull plate thickness measured using a Vernier caliper. It was found that when the probe frequency was higher, the eco-pulse velocity of the receiver had to be lowered to obtain accurate measurement results, whereas fewer errors occurred at a relatively low probe frequency.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.3
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• pp.246-254
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• 2013

This study is purposed to verify the safety of the floor of the children's playground using polyolefin foam waste and rubber paving. The critical fall height, walking suitability, long term physical fatigue expectation and slipperiness were tested. Polyolefin foam wastes in thickness of 30mm, 50mm and 70mm were prepared with paving the rubber paving materials in 12mm and 15mm thickness respectively. The test on the critical fall height was carried out according to KS G 5758:2009. The floor hardness test equipment (O-Y HMA) was used for the test on hardness of the floor from a viewpoint of walking suitability and fatigue. A portable slipperiness tester (ONO PPSM) was used for slipperiness test. It was revealed from the test that the floor made of the polyolefin foam waste and rubber paving were considerably safe from a viewpoint of impact absorption. With regards to the hardness of the floor, it was shown the excellent performance in the aspects of walking and fatigue for male. But it was not suitable with walking on the shoes(middle heels) for female. And they will be very fatigue if they were in a long time walking or standing. As far as the slipperiness is concerned, it was shown that it was comparatively safe for the ordinary motions even though the surface was wet.

• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.350-358
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• 2014

The demand for the lightweight wall has increased as the structure of the multi-unit dwelling has shift to the rahmen structure. The lightweight wall is required to secure certain degree of shock resistance for the structural safety. The study performed the load analysis test for 7 small hard bodies with different masses and shapes and 5 hard materials which applied the impact load on the wall. It was found out from the experiment that different pendulum weight doubled the load maximum even though the shock energy was the same. In addition, the study compared and analyzed the weight of materials and the load of small hard bodies to propose fundamental data for the material design of the lightweight wall.

• Journal of Information Technology Services
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• v.19 no.5
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• pp.33-47
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• 2020

In recent years, due to the demand for operating efficiency and cost reduction of industrial facilities, remote access via the Internet is expanding. the control network accelerates from network separation to network connection due to the development of IIoT (Industrial Internet of Things) technology. Transition of control network is a new opportunity, but concerns about cybersecurity are also growing. Therefore, manufacturers must reflect security compliance and standards in consideration of the Internet connection environment, and enterprises must newly recognize the connection area of the control network as a security management target. In this study, the core target of the control system security threat is defined as the network boundary, and issues regarding the security architecture configuration for the boundary and the role & responsibility of the working organization are covered. Enterprises do not integrate the design organization with the operation organization after go-live, and are not consistently reflecting security considerations from design to operation. At this point, the expansion of the control network is a big transition that calls for the establishment of a responsible organization and reinforcement of the role of the network boundary area where there is a concern about lack of management. Thus, through the organization of the facility network and the analysis of the roles between each organization, an static perspective and difference in perception were derived. In addition, standards and guidelines required for reinforcing network boundary security were studied to address essential operational standards that required the Internet connection of the control network. This study will help establish a network boundary management system that should be considered at the enterprise level in the future.

• International Journal of Contents
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• v.12 no.3
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• pp.34-41
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• 2016

A traditional village is cultural property where old buildings and traditions are concentrated and also where indigenous traditional cultures can be recognized and experienced directly or indirectly. In addition, traditional villages have been recognized as precious resources to revitalize regional economies through tourism. Currently, signage systems have been developed as for ordinary tourist sites or cities, and concepts or methods for sign system for traditional villages have not yet been established. Therefore, it is necessary to develop disaster prevention-based signage to prevent large-scale disasters, to guarantee the safety of residents, and to increase the satisfaction of visitors in traditional villages as precious resources. A case study is conducted to apply the proposed sign system for traditional villages in Korea and Japan as a tourist-oriented sign system that has been accomplished in Korea and a large disaster-oriented sign system developed with residents as a priority in Japan. The disaster prevention sign system considers the residents since residents are victims when a disaster happens, and guideline to increase the efficacy and satisfaction are suggested. However, this study has definite limits in sucring objectivity because the objects of study are insufficient, and the development of the sign system based on effective disaster prevention considering the features of traditional villages will continue in the future.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.919-928
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• 2012

The applications of computers and communication system and network technologies in nuclear power plants have expanded recently. This application of digital technologies to the instrumentation and control systems of nuclear power plants brings with it the cyber security concerns similar to other critical infrastructures. Cyber security risk assessments for digital instrumentation and control systems have become more crucial in the development of new systems and in the operation of existing systems. Although the instrumentation and control systems of nuclear power plants are similar to industrial control systems, the former have specifications that differ from the latter in terms of architecture and function, in order to satisfy nuclear safety requirements, which need different methods for the application of cyber security risk assessment. In this paper, the characteristics of nuclear power plant instrumentation and control systems are described, and the considerations needed when conducting cyber security risk assessments in accordance with the lifecycle process of instrumentation and control systems are discussed. For cyber security risk assessments of instrumentation and control systems, the activities and considerations necessary for assessments during the system design phase or component design and equipment supply phase are presented in the following 6 steps: 1) System Identification and Cyber Security Modeling, 2) Asset and Impact Analysis, 3) Threat Analysis, 4) Vulnerability Analysis, 5) Security Control Design, and 6) Penetration test. The results from an application of the method to a digital reactor protection system are described.

• Journal of KIISE:Software and Applications
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• v.34 no.3
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• pp.235-245
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• 2007

UUV(Unmanned Underwater Vehicle) should possess an intelligent control software performing intellectual faculties such as cognition, decision and action which are parts of domain expert's ability, because unmanned underwater robot navigates in the hazardous environment where human being can not access directly. In this paper, we suggest a RVC intelligent system architecture which is generally available for unmanned vehicle and develope an autonomous navigation system for UUV, which consists of collision avoidance system, path planning system, and collision-risk computation system. We present an obstacle avoidance algorithm using fuzzy relational products for the collision avoidance system, which guarantees the safety and optimality in view of traversing path. Also, we present a new path-planning algorithm using poly-line for the path planning system. In order to verify the performance of suggested autonomous navigation system, we develop a simulation system, which consists of environment manager, object, and 3-D viewer.

• 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.

• Korean Journal of Construction Engineering and Management
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• v.24 no.3
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• pp.31-41
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• 2023

This study is a study to develop a configuration management methodology for efficient and systematic management in the event of configuration changes such as deformation, explosion, and remodeling of launch vehicle development test facilities, which are emerging as important national facilities in the era of full-scale space competition. Through the analysis of international standards for configuration management, a configuration management process framework to be applied to launch vehicle development test facilities is extracted, a survey was conducted on experts who performed life cycle engineering of launch vehicle development test facilities, and a configuration management methodology optimized for operation/management of domestic launch vehicle development test facilities was proposed. Identify the configuration for launch vehicle development test facilities, the configuration management manager, configuration management organization, and configuration management board approve/process the configuration changes, and after construction is completed according to design requirements, launch vehicle development test facilities try to manage the configuration in a controlled state.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.431-440
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• 2013

It was tested in field that a Pull-out Capacity and Shear resistance strength change of reed, common reed and sedge which were planted by mat-type turf and used for revegetation of bank. The testes were done for 9 weeks from end of May and the grasses were planted on sandy soil. Roots grew fastly after planted and increasement of a common reed and sedge root were reduced after 4 weeks but increasement of reed roots were not reduced. The difference of increasement of roots is due to a difference of propagation method. Sedge propagate by seed. Reed and commom reed propagate by seed and subterranean stem and reed has bigger subterranean stem than common reed. So increasement of common reed and sedge roots were slow than reed. By root growth pattern, increasement of pull-out capacity and shear resistance strength showed very similar way of root growth, those of common reed and sedge were fast in early stage of cultivation but were reduced. But increasement of pull-out capacity and shear resistance strength of reed was not reduced. A Maximum shear resistance strength called critical shear resistance strength of common reed and sedge can be Analyzed at 11 weeks after planted.