• Journal of Korea Society of Digital Industry and Information Management
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• v.17 no.1
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• pp.35-44
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• 2021

With the development of information technology, the cybersecurity threat continues as digital-related technologies are applied to the instrumentation and control system of nuclear power plants. The malfunction of the instrumentation and control system can cause economic damage due to shutdown, and furthermore, it can lead to national disasters such as radioactive emissions, so countering cybersecurity threats is an important issue. In general, the study of cybersecurity in instrumentation and control systems is concentrated on safety systems, and diverse protection systems perform protection and reactor shutdown functions, leading to reactor shutdown or, in the worst case, non-stop situations. To accurately analyze cyber threats in the diverse protection system, its linked facilities should be analyzed together. Risk analysis should be conducted by analyzing the potential impact of inter-facility cyberattacks on related facilities and the impact of cybersecurity on each configuration module of the diverse protection system. In this paper, we analyze the linkage of the diverse protection system and discuss the cybersecurity linkage threat by analyzing the availability of equipment, the cyber threat impact of the linked equipment, and the configuration module's cybersecurity vulnerability.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.596-603
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• 2010

This paper presents a homing guidance law of anti-ship missiles using flight path angle to achieve an impact time constraint as well as an impact angle constraint. the independent variable in the nonlinear engagement model is change d from the flight time to the heading angle of the missile. The proposed guidance law can home a missile to the target with zero miss distance as well as satisfying both of the impact angle and time constraints. The performance of the proposed guidance law is evaluated by the computer simulations.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.723-728
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• 2015

In the conventional hot rolling process, the defects of products such as scratches occur due to impact and friction. Impact occurs as a result of the contact of between rollers and the slab. Also, friction occurs in the rolling process. To improve these defects, a variety of processes were developed. The flying touch method is also one of the processes to reduce defects and uses a movable upper roller. To use this unfixed roller, the impact and frictions between rollers and the slab should be minimized. This paper proposes a hot rolling process simulator to verify and test the efficiency of the flying touch method. The simulator was designed to verify the method. This paper also proposes a new impact reducing method and velocity synchronization method which are simulated to realize the method.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.411-418
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• 2002

In domestic road construction sites, the compaction control based on strength are widely performed through the direct method with high accuracy, such as Plate Loading Test or Field CBR test. It is impossible to manage all construction sites using the direct method because the direct method requires heavy reaction loads and long measurement time. Therefore, it is necessary to apply the indirect method that could control the relative density of construction sites on the whole. Indirect methods, such as Cone Penetration Test and Fall Cone Test, require extra time for data analyzing and fixed area for test device. In this paper, the field applicability of Soil Impact Hammer (SIH) was investigated comparing with the results of field measurement tests and laboratory compaction tests. SIH developed by Japan Construction Administration and Asanuma Ltd., is a kind of indirect methods for compaction checking. According to the results of SIH performed in domestic road construction site, the subgrade reaction modulus obtained from SIH are similar to that from Plate loading tests in the range of 10 to 40. In comparison with laboratory compaction test, similar compaction line are shown in the dry side of optimum moisture contents.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.199-207
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• 2008

As infrastructures are being deteriorated, nondestructive evaluation of existing structures and construction quality control are increasingly demanded. The importance of predicting compressive strength of concrete structure is also gradually increasing in construction industry. The estimation of concrete compressive strength is a critical factor of the construction management and quality control. This study has been conducted using Schmidt hammer test and Impact echo method, which are nondestructive test methods for the comparison of the concrete compressive strength. It is focusing to examine the relationship between compressive strength of concrete and rebound number by Schmidt hammer test result by Impact echo method. It was found that concrete compressive strength and rebound number have a close correlation.

• Journal of Convergence for Information Technology
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• v.11 no.10
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• pp.250-257
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• 2021

The author tried to verify the mediating effect of the variable, perceived behavioral control, in the relationship between the independent variables(cosmetics-related variables, consumer's preference, advice & inducement), and the dependent variable(purchasing behavior), through AMOS structural equation modeling. As a result of analyzing the mediating effect in the impact relationship between latent variables, it was found that PBC(perceived behavior control) plays a mediating role in the impact relationship between CQ(cosmetics quality) and PB(purchasing behavior). Author found that the higher the quality of cosmetics and the greater the perceived behavior control in domestic cosmetics purchasing behavior, the more likely it will lead to purchasing behavior. In this context, while efforts are being made to improve cosmetic quality, measures to increase perceived behavior control, which can be said to be autonomy in purchasing behavior, should be sought.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1803-1806
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• 2007

The General roles of a spacer grid(SG) are providing a lateral and vertical support for fuel rods, promoting a mixing of coolant and keeping guide tubes straight so as not to impede a control rod insertion under any normal or accidental conditions. To evaluate the impact characteristics of a SG such as impact velocity, critical buckling strength and duration time, a few types of impact tests for SGs have been conducted. In a previous study, a new welding method, a through-welding method, was proposed to increase critical buckling strength of a SG without any design change or material change and was verified by impact tests with $7{\times}7$ partial SG specimens.In this paper, the effect of through-welding method in case of a $16{\times}16$ full-size SG is investigated by pendulum impact tests with $16{\times}16$ SG specimens. And the increase of critical buckling strength for full-size SGs is measured by comparison with impact results of spot-welded and through-welded SGs.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.1
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• pp.5-13
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• 2017

Noise complaints among neighbors in apartment building are mainly caused by floor impact noise that is structure born noise due to occupant induced floor vibration. To control this noise problems many researchers have investigated floor systems and finishing materials. Light-weight impact noise affects by finishing materials, but heavy-weight impact noise induced by heel impacts during normal walking or jumping of children is concerned with structural system and floor vibration. To figure out the characteristics of floor impact noise and transmission of floor vibration due to human activities, vibration tests were conducted in apartment buildings. Impact hammer, heel drop and walking activities were loaded at center of upstairs living room, and accelerations of slabs for both upstairs and downstairs and sound pressure levels for downstairs were measured. The acceleration ratio of transmitted floor vibration to downstairs and human induced vibration in upstairs was between 0.5 and 1.0 according to slab size, wall, and load type. And floor impact noise occurred in the range of natural frequency of slab.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.7 s.112
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• pp.754-761
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• 2006

This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed to reduce force transmitted to the vehicle chassis and finally to protect occupants from injury. In the case of head-on collision, the bumper makes main role of isolation material for collision attenuation. In this study, the proposed bumper system consists of MR impact damper and structures. The MR impact damper utilizes MR fluid which has reversible properties with applied magnetic field. The MR fluid operates under flow mode. The bellows is used for generation of fluid flow. A mathematical model of the MR impact damper is derived incorporating with Bingham model of the MR fluid. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.147-152
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• 2006

This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed for reduce transmitted force to vehicle chassis and finally protect occupants from injury. In the case of frontal collision, the bumper make main role of isolation material for collision attenuation. In this study, proposed bumper system composed of MR impact damper and structures. The MR impact damper is to adopted MR fluid which has reversible properties with applied magnetic field. MR fluid operates under flow mode with Bingham flow and bellows is used for generation of fluid flow. Mathematical model of MR impact damper incorporated with MR fluid is established. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.