• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.435-442
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• 2014

This paper describes an improved design model that can be used to configure a non-contact pneumatic device to turn a large sheet at the in-line system. For rotational moving in the conveyor system, the conventional method is to turn the system itself. The improved non-contact pick-up system mainly uses 8 pairs of L-shaped latches and 12 swirl type heads. It is positioned above the upward air flow table. This system performs the non-contact gripping and side-edge contact support in the vertical and rotational directions to hold the self-weight of a large flat sheet. A non-contact air head can exert a sufficient gripping ability at 4N lower than the standard working pressure. The side latches support 60% of the lifting force required. Through structural and flow analysis, the working conditions were simultaneously considered in accordance with the deflection and flatness of the glass.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.185-191
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• 2002

In this study a 3-dimensional analytical model is developed, which can analyses dynamic responses of curved bridges subject to moving vehicles. A 5-axle semi-trailer is modeled to simulate the actual tire forces that are redistributed by vehicle rolling effect due to the centrifugal force. The 1-span curved bridge with two steel box girders is modeled using the frame elements. The dynamic response characteristics of curved box girder bridges are examined and compared for two different support conditions. One is the case that two shoes are arranged at the outer sides of box girders with larger space between the two shoes and the other is that two shoes at the center of each box girder. In the curved bridges, the dynamic effect of moving vehicles influences the reaction force much more than other responses, such as displacement or stress, especially the upward reaction of inner-radius shoes. It is more advantageous for the reaction considering dynamic effect when shoes are arranged further at the outer sides of box girders than when shoes at the center of each box. The shoes for curved bridges with two-box girder system should be arranged to have larger distance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.109-110
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• 2018

Preloading Strut applied during installation of the wall jack, but additionally serves to minimize the displacement of soil pressure acting upon dissolution due to the difficulty. In this study, we developed an index of support for the release of stress to facilitate the dismantling of the strut uninstall. The refractive support the axial force acting on the strut are supportable, is refracted at minimum load, disassembly should be easy. In order to find the optimal shape and structural stability of the refractive support We have performed the numerical analysis and performance test to determine the final model. We carried out model tests and UTM test in order to understand the refractive performance and durability of the refractive support for optimal model. Results of the test UTM is refracted all shot 5 times within a target hit number, it was found that there is no problem of the refractive performance. Further, the results of model experiments, it was found that to ensure sufficient durability more than the performance target value of the pin joint support structure.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.47 no.3
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• pp.75-85
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• 2024

Airpower is a crucial force for suppressing military threats and achieving victory in wars. This study evaluates newly introduced fighter forces, considering factors such as fighter performance and power index, operational environment, capacity of each airbase, survivability, and force sustainment capability to determine the optimal deployment plan that maximizes operational effectiveness and efficiency. Research methods include optimization techniques such as MIP(mixed integer programming), allocation problems, and experimental design. This optimal allocation mathematical model is constructed based on various constraints such as survivability, mission criticality, and aircraft's performance data. The scope of the study focuses the fighter force and their operational radius is limited to major Air Force and joint operations, such as air interdiction, defensive counter-air operations, close air support, maritime operations and so on. This study aims to maximize the operational efficiency and effectiveness of fighter aircraft operations. The results of proposed model through experiments showed that it was for superior to the existing deployment plan in terms of operation and sustainment aspects when considering both wartime and peacetime.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.492-500
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• 2018

The performance evaluation of cold weather clothing is mainly carried out with thermal resistance. However, the results of the revised test method regarding the same specimen were decreased compare to previous one. In addition, there were deviations of the results among the authorized testing institutes according to the different interpretation of the KS test method. This makes it a considerable difficulty to the quality assurance of combat supplies. The purpose of this study is to minimize the variation of the results before and after the revision by analyzing the cause of the decrease in the heat insulation rate according to the revised test method. For this purpose, the difference between the test conditions before and after the revision of KS is analyzed and the possible results are reviewed. In addition, we want to minimize the result deviation between testing laboratories by analyzing the cause of the result deviation between test laboratories according to arbitrary interpretation of the standard. Based on this, we propose a standardized test method to prevent the decrease of the heat insulation rate by checking the pre-revision test method and the condition with the least deviation.

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.527-538
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• 2017

The evaluation of the loss-of-support conditions of frictional beam-to-column connections using simplified numerical models describing the transverse response of a portal-like structure is presented in this paper considering the effects of the seismic-hazard disaggregation. Real earthquake time histories selected from European Strong-motion Database (ESD) are used to show the effects of the seismic-hazard disaggregation on the beam loss-of-support conditions. Seismic events are classified according to different values of magnitudes, epicentral distances and soil conditions (stiff or soft soil) highlighting the importance of considering the characteristics of the seismic input in the assessment of the loss-of-support conditions of frictional beam-to-column connections. A rigid and an elastic model of a frame of a precast industrial building (2-DoF portal-like model) are presented and adopted to find the minimum required friction coefficient to avoid sliding. Then, the mean value of the minimum required friction coefficient with an epicentral distance bin of 10 km is calculated and fitted with a linear function depending on the logarithm of the epicentral distance. A complete parametric analysis varying the horizontal and vertical period of vibration of the structure is performed. Results show that the loss-of-support condition is strongly influenced by magnitude, epicentral distance and soil conditions determining the frequency content of the earthquake time histories and the correlation between the maxima of the horizontal and vertical components. Moreover, as expected, dynamic characteristics of the structure have also a strong influence. Finally, the effect of the column nonlinear behavior (i.e. formation of plastic hinges at the base) is analyzed showing that the connection and the column are a series system where the maximum force is limited by the element having the minimum strength. Two different longitudinal reinforcement ratios are analyzed demonstrating that the column strength variation changes the system response.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.4
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• pp.635-641
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• 2010

In this paper, we propose an efficient public key broadcast encryption system which can also extend traitor trace and revoke system. Although the proposed system has limited collusion size, the ciphertext size in the system can be sublinear in the number of total users, the private key size is constant, the computational cost can be sublinear and it can support black-box tracing algorithm, therefore, our system can be an option to applications where reducing the ciphertext size, private key size is a top priority. Furthermore, we can also apply our system to military document broadcast system, because it has such an efficient measurement.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.56
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• pp.57-76
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• 2012

As globalization accelerates and the trade environment rapidly changes, a more prepared trade workforce is required for the business world. The trade department is an important educational institution that educates and trains future trade talent. Thus, in the evolving trade environment, their role has significant implications for the economic growth of Korea. The present paper is a comparative study of the importance of the university education system in terms of the trade work force through the Person-Organization fit (P-O fit) perspective. We observe that the American trade education system is more oriented to meet and reflect the needs from the real world. It contains a support structure through various governmental organizations that offer financial incentives as well as educational opportunities through internships and other hands-on experiences. The trade education systems in universities in Korea are still static by comparison and are recommended to implement changes that will give students more practical exposure to trade. The governmental and business sectors are also encouraged to support universities in achieving these goals through building a strong cooperative network with university trade departments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.328-341
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• 2017

In the control actuator system of a launch vehicle based on thrust vectoring, the interaction between electro-mechanical position servo and inertial load are combined with the dynamic characteristics of the flexible vehicle support to generate synthetic resonance. This occurred resonance is fed back to the attitude control system and can influence stability of launch vehicle. In this study, we proposed a simulation model to analyze synthetic resonance of electro-mechanical actuation system for thrust vector control and explained the results of simulation and test using dynamic force feedback control which improves dynamic characteristics of servo actuation system by reducing synthetic resonance.

• Smart Structures and Systems
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• v.26 no.2
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• pp.195-211
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• 2020

Among anti-seismic technologies, base isolation is a very effective means of mitigating damage to structural and nonstructural components, such as equipment. However, most seismic isolation systems are designed for mitigating only horizontal seismic responses because the realization of a vertical isolation system (VIS) is difficult. The difficulty is primarily due to conflicting isolation stiffness demands in the static and dynamic states for a VIS, which requires sufficient rigidity to support the self-weight of the isolated object in the static state, but sufficient flexibility to lengthen the isolation period and uncouple the ground motion in the dynamic state. To overcome this problem, a semi-active VIS, called the piezoelectric inertia-type vertical isolation system (PIVIS), is proposed in this study. PIVIS is composed of a piezoelectric friction damper (PFD) and a leverage mechanism with a counterweight. The counterweight provides an uplifting force in the static state and an extra inertial force in the dynamic state; therefore, the effective vertical stiffness of PIVIS is higher in the static state and lower in the dynamic state. The PFD provides a controllable friction force for PIVIS to further prevent its excessive displacement. For experimental verification, a shaking table test was conducted on a prototype PIVIS controlled by a simple controller. The experimental results well agree with the theoretical results. To further investigate the isolation performance of PIVIS, the seismic responses of PIVIS were simulated numerically by considering 14 vertical ground motions with different characteristics. The responses of PIVIS were compared with those of a traditional VIS and a passive system (PIVIS without control). The numerical results demonstrate that compared with the traditional and passive systems, PIVIS can effectively suppress isolation displacement in all kinds of earthquake with various peak ground accelerations and frequency content while maintaining its isolation efficiency. The proposed system is particularly effective for near-fault earthquakes with long-period components, for which it prevents resonant-like motion.