• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.9
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• pp.4599-4617
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• 2018

Abusing the Simple Server Discovery Protocol (SSDP) can induce an SSDP attack (including SSDP DoS, DDoS, DRDoS) posing a significant threat to UPnP devices. Rapid and extensive developments in computer technology, especially in regards to IoT, have made Upnp devices an indispensable part of our daily lives - but also render them susceptible to a variety of SSDP attacks without suitable countermeasures. This paper proposes the Two-dimensional table scheme, which provides high security at a reasonable computational cost. The feasibility and effectiveness of the proposed scheme are also validated by comparison against four other schemes (Stateless connections, Failing-together, Cookie, and Client puzzle).

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.8
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• pp.623-631
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• 2003

We have fabricated the two-dimensional inverted pendulum system and designed its controller. The two-dimensional inverted pendulum system, which is composed of X-Y table, is actuated through timing belt by each of two geared DC motors. And the control goal is that the rod is always kept to a vertical position to any distrubance and is quickly moved to the desired position. Because this system has generally nonlinear dynamic characteristics and X-axis and Y-axis move together, it is very difficult to find its exact mathematical model and to design its controller. Therefore, we have designed the PID controller with simple structure and excellent performance. Genetic algorithm(GA), which is blown as one of probabilistic searching methods, and human's heuristic control strategy are introduced to design an optimal PID controller. The usefulness of the proposed GA based PID coefficient searching technique is verified through the experiments and computer simulations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1933-1936
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• 2005

The isometric area of the anterior cruciate ligament was calculated during knee flexion-extension. Flexion-extension motion data of the joint were obtained using Fastrak and a three-dimensional motion measurement system. A total of five subjects were seated on a flat table and the tibia sensor position was measured with the femur fixed on the table. A three-dimensional knee model was constructed using a graphic tool to simulate the knee motion. Twenty seven positions of the tibia region and forty two positions of the femur region were selected and the distances between the determined tibial and femoral points were calculated. Highly isometric areas were found and displayed as three dimensional aspects.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.409-416
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• 2006

The seismic characteristics with 3-Dimensional Floor Isolation System have been studied using a shaking table system. In this study, we made two kind of floor system (Type I, Type II) and several seismic tests with and without isolation system were conducted to evaluate 3-Dimensional Floor Isolation Effectiveness. Both type have showed large reduction effectiveness in acceleration, response spectra but Type II have showed lower acceleration and lower first mode in response spectra, compared to type I. On the basis of test results and consideration of application, it is found that type II is more suitable for floor model of main control room of Nuclear Power Plant.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.181-194
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• 2019

Due to the seepage of groundwater, the resisting force of slopes decreases and the sliding force increases, resulting in significantly reduced slope stability. The instability of most natural slopes is closely related to the influence of groundwater. Therefore, it is important to study slope stability under groundwater seepage conditions. Thus, using a simplified seepage model of groundwater combined with the analysis of stresses on the slip surface, the limit equilibrium (LE) analytical solutions for two- and three-dimensional slope stability under groundwater seepage are deduced in this work. Meanwhile, the general nonlinear Mohr-Coulomb (M-C) strength criterion is adopted to describe the shear failure of a slope. By comparing the results with the traditional LE methods on slope examples, the feasibility of the proposed method is verified. In contrast to traditional LE methods, the proposed method is more suitable for analyzing slope stability under complex conditions. In addition, to facilitate the optimization of drainage design in the slope, stability charts are drawn for slopes with different groundwater tables. Furthermore, the study concluded that: (1) when the hydraulic gradient of groundwater is small, the effect on slope stability is also small for a change in the groundwater table; and (2) compared with a slope without a groundwater table, a slope with a groundwater table has a larger failure range under groundwater seepage.

• Structural Engineering and Mechanics
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• v.11 no.6
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• pp.651-662
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• 2001

In order to investigate the seismic behavior and seismic design methods in the transverse direction of a shield tunnel, a series of model shaking table tests and a two-dimensional finite element dynamic analysis on the tests are carried out. Two kinds of static analytical methods based on ground-tunnel composite finite element model and beam-spring element model are proposed, and the validity of the static analyses is verified by model shaking table tests. The investigation concerns the dynamic response behavior of a tunnel and the ground, the interaction between the tunnel and ground, and an evaluation of different seismic design methods. Results of the investigation indicate that the shield tunnel follows the surrounding ground in displacement and dynamic characteristics in the transverse direction; also, the static analytical methods proposed by the authors can be used directly as the seismic design methods in the transverse direction of a shield tunnel.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.8
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• pp.2184-2193
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• 1994

A flow visualization experiment using water-table models was performed. The water-table models simulated the two-dimensional cold flow fields inside the combustion chambers of incinerators. The flow were visualized by small but neutrally bouyant particles photographed by an overhead camera. The experimentally simulated flow fields apparently showed distinct features of two combustion chamber shapes; counter and parallel flow types. The significance of the secondary air injection on the mixing of combustion gases were clearly observed. The effects of the recirculation zones, which were present in the secondary chamber, were discussed by considering the importance of them for optimal combustion.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.1
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• pp.69-77
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• 1996

To evaluate the change of the groundwater flow and the water table response resulting from urbanization, two cases of the transient three-dimensional numerical simulations were performed. Variations of the groundwater flow system caused by withdrawals were analyzed. Two cases of infiltration rates were applied in this study to verify the water table changes. One is the rate under the circumstance during 1994 and the other is the revised rate. The numerical results from this study indicated that groundwater flow was influenced by human impacts. Groundwater flow has been concentrated to Taegu Textile Complex area where had large amount of pumping. Water table so far decreased -2.76m a year due to withdrawals. Water tables of many points were increased more than 30cm when the surface was reformed by infiltrating the rainfall. It was appeared that the improvement of surface to recharge the precipitation was very important to preserve and manage for the groundwater.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.5
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• pp.27-33
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• 1993

This paper describes the hardware implementation of 2-D FIR digital filter for a real-time image processing. Generally, the most time-consuming operation in signal processing is the multiplication operation. To avoid it in digital filter. Pelid and Liu proposed the distributed arithmetic method for the one-dimensional case. The implementation method proposed in this paper is to extend Pelid's method to two-dimensional FIR filter using simple ROM lookup table and to use the technique of pipe lining two main operations of memory access and arithmetic. As a result, the speed of our proposed hardware implementation is two times faster than that of conventional methods and can be close to the real time speed.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.57-66
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• 2008

An experimental study was performed to evaluate seismic reduction performance and applicability of 3-dimensional floor isolation system to the main control room of nuclear power plant. A friction pendulum system(FPS) and air spring were designed and fabricated for 3-dimensional floor isolation system. Two kind of the partial experimental model of a main control room attached to the FPS and air spring were tested on the shaking table. The experimental model consisted of a control panel, a $2.5m{\times}2.5m$ access floor, four FPS and air springs. The artificial time histories based on the vertical and horizontal floor response spectrums(OBE, SSE) of the main control room were used as the earthquake input signals in the test. Compared to non-isolated system, the seismic response of experimental models using 3-dimensional floor isolation system were shown considerable seismic reduction performance.