• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.4
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• pp.225-233
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• 2010

In this paper, we try to improve the performance of the demand paging loader suggested to use the demand paging way that is not based on operating system. The demand paging switching strategy used in the existing operating system can know the recently used pages by running multi-processing. Then, based on it, some page switching strategies have been made for the recently used pages or the frequently demanded pages. However, the strategies based on operating system cannot be applied in single processing that is not based on operating system because any context switching never occur on the single processing. So, this paper is trying to suggest the demand paging switching strategies that can be applied in paging loader running in single process. In the Return-Prediction-Algorithm, we saw the improved performance in the program that the function call occurred frequently in a long distance. And then, in the Most-Frequently-Used-Page-Remain-Algorithm, we saw the improved performance in the program that the references frequently occurred for the particular pages. Likewise, it had an enormous effect on keeping the memory reduction performance by the demand paging and reducing the running time delay at the same time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9C
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• pp.843-850
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• 2003

Turbo coding and turbo processing have been known as methods close to Shannon limit in the aspect of wireless MIMO communications similarly to wireless single antenna communication. The iterative processing can maximize the mutual effect of coding and interference cancellation, but turbo coding has not been used for turbo processing because of the inherent decoding process delay. This paper proposes a turbo coded MIMO system with adaptive turbo parallel space-time (Turbo-PAST) processing for high-speed wireless communications and a enhanced cyclic redundancy check (E-CRC) scheme as an efficient and simple priori stopping criterion. Simulation results show that the Turbo-PAST outperforms conventional system with 1.3dB and the proposed E-CRC scheme effectively reduces the amount of turbo processing iterations from the point of average number of iterations.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.694-702
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• 2007

The SSWM(Software Switching Mechanism) of I-processor concept using non-real time in-house software simulation program is an effective method in order to develop the flight control law in desktop or HQS environment. And, this system has some advantages compare to HSWM(Hardware Switching Mechanism) such as remove the time delay effectiveness and reduce the costs of development. But, if this system loading to the OFP(Operational Flight Program), the OFP guarantee the enough throughput in order to calculate the two control law at once. Therefore, the HSWM(Hardware Switching Mechanism) of 2-processor concept is necessary. This paper addresses the concept of HSWM of the HQS-PC interface using TCP/IP(Transmission Control Protocol/Internet Protocol) communication based on flight control law of advanced supersonic trainer. And, the fader logic of TFS(Transient Free Switch) and stand-by mode of reset '0' type are designed in order to reduce the abrupt transient response and minimize the integrator effect in pitch axis. The result of the analysis based on HQS pilot simulation using HSWM reveals that the flight control systems are switching between two computers without any problem.

• Journal of Korean Society of Transportation
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• v.12 no.4
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• pp.35-52
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• 1994

In order to operate the computerized traffic signal system, it requires the detectors which ensure the exact detections of actual traffic data (e.g., traffic volume, occupancy and velocity of vehicles). The octagonal detectors are used currently in Korea. However, the maintenance of the detectors has many problems with the road repairs and the constructions on the pavement, and failure due to the disconnection of the wires. Serious delay due to the long installation time of loops also causes the traffic disturbances. The low sensitivities and splash-over effect can sometimes create error data after installation of the octagonal loops. The mai purpose of this study is to evaluate the feasibility of domestic use of the round (circular) inductive loops which developed recently in U.S.A. It was found that the round loops are comparable to the existing octagonal loops. In addition, the use of the high quality of materials in the round loop system can reduce the current problems and weakpoints of the octagonal loops. The installation cost of the round loop was found out as economic as the octagonal loop. The installation time of the round loop system can be reduced with the specially equipped loop truck, and wide/deep slots without sharp corners can extend the durability without serious stress of loop head wires. In conclusion, the round loop is superior to the octagonal type in overall points. It is recommended that the localization of the materials and equipments of round loop system is required to carry out the extensive local installations. Also, several contractors to meet the nationwide demand should be arranged to gurantee the proper maintenance and operation of the systems.

• Earthquakes and Structures
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• v.11 no.6
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• pp.1143-1164
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• 2016

Time Delay of Arrival (TDOA) estimation methods based on correlation function analysis play an important role in the micro-seismic event monitoring. It makes full use of the similarity in the recorded signals that are from the same source. However, those methods are subjected to the noise effect, particularly when the global similarity of the signals is low. This paper proposes a new approach for micro-seismic monitoring based on cross wavelet transform. The cross wavelet transform is utilized to analyse the measured signals under micro-seismic events, and the cross wavelet power spectrum is used to measure the similarity of two signals in a multi-scale dimension and subsequently identify TDOA. The offset time instant associated with the maximum cross wavelet transform spectrum power is identified as TDOA, and then the location of micro-seismic event can be identified. Individual and statistical identification tests are performed with measurement data from an in-field mine. Experimental studies demonstrate that the proposed approach significantly improves the robustness and accuracy of micro-seismic source locating in mines compared to several existing methods, such as the cross-correlation, multi-correlation, STA/LTA and Kurtosis methods.

• Structural Engineering and Mechanics
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• v.75 no.2
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• pp.175-191
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• 2020

In this study, multi-story structures are actively controlled using metaheuristic algorithms. The soil conditions such as dense, normal and soft soil are considered under near-fault ground motions consisting of two types of impulsive motions called directivity effect (fault normal component) and the flint step (fault parallel component). In the active tendon-controlled structure, Proportional-Integral-Derivative (PID) type controller optimized by the proposed algorithms was used to achieve a control signal and to produce a corresponding control force. As the novelty of the study, the parameters of PID controller were determined by different metaheuristic algorithms to find the best one for seismic structures. These algorithms are flower pollination algorithm (FPA), teaching learning based optimization (TLBO) and Jaya Algorithm (JA). Furthermore, since the influence of time delay on the structural responses is an important issue for active control systems, it should be considered in the optimization process and time domain analyses. The proposed method was applied for a 15-story structural model and the feasible results were found by limiting the maximum control force for the near-fault records defined in FEMA P-695. Finally, it was determined that the active control using metaheuristic algorithms optimally reduced the structural responses and can be applied for the buildings with the soil-structure interaction (SSI).

• Journal of Computing Science and Engineering
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• v.4 no.3
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• pp.189-206
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• 2010

It is generally accepted that dynamic voltage scaling (DVS) is one of the most effective techniques of energy minimization for real-time applications in embedded system design. The effectiveness comes from the fact that the amount of energy consumption is quadractically proportional to the voltage applied to the processor. The penalty is the execution delay, which is linearly and inversely proportional to the voltage. According to the granularity of tasks to which voltage scaling is applied, the DVS problem is divided into two subproblems: inter-task DVS problem, in which the determination of the voltage is carried out on a task-by-task basis and the voltage assigned to the task is unchanged during the whole execution of the task, and intra-task DVS problem, in which the operating voltage of a task is dynamically adjusted according to the execution behavior to reflect the changes of the required number of cycles to finish the task before the deadline. Frequent voltage transitions may cause an adverse effect on energy minimization due to the increase of the overhead of transition time and energy. In addition, DVS needs to be carefully applied so that the dynamically varying chip temperature should not exceed a certain threshold because a drastic increase of chip temperature is highly likely to cause system function failure. This paper reviews representative works on the theoretical solutions to DVS problems regarding inter-task DVS, intra-task DVS, voltage transition, and thermal-aware DVS.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.498-505
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• 2000

Performance of a hydraulic system is influenced by its working temperature. Therefore, it is very important to make the system perform uniformly in an entire range of the working temperature. In this study a simulation of a hydraulic control system for the powershift transmission of tractors was conducted and the effect of the temperature was investigated in terms of design conditions of the system. Results of the simulation are as follows. The hydraulic control system with a spring accumulator was found to be more convenient to control the shifting time than that with a gas accumulator. By returning the oil from the clutches to the system through a path between the filter and pump, the time delay due to the pressure difference between the low and high temperatures could be reduced. Therefore, it was recommended that the hydraulic control system for the powershift transmission of tractors must be equipped with a spring accumulator and a circuit to return oil from the clutches to the system through a path between the filter and pump.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.446-450
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• 2012

I.G.G is abbreviation for inert gas generator high temperature in cargo tank it desulfurize, exhaust and froze the gas that combined brimstone element and soot, then supply inert gas by blower and mack tank inside incombustible range this is equipment that nip in the bud the explosion. The blower for suppling inactivated gas has big impeller with heavy weight to achieve the high pressure, it causes a delay for first operation time and too much load is delivered to motor, total destruction by fire of motor is happen frequently. On this research, we will reduce the size and weight of impeller and install it with several stage, it makes an effect for reducing the first operation time. We also intend to contribute to efficient I.G.G. blower design by research a flow rate and pressure specialty from the diameter of impeller number of blades and size of casing.

• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.112-117
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• 2015

Purpose: The purpose of this study was to examine the effects of a task-specific obstacle crossing rehabilitation program on functional gait ability in patients with cerebellar ataxia. Overall, we sought to provide ataxia-specific locomotor rehabilitation guidelines for use in clinical practice based on quantitative evidence using relevant analysis of gait kinematics including valid clinical tests. Methods: Patients with cerebellar disease (n=13) participated in obstacle crossing training focusing on maintenance of dynamic balance and posture, stable transferring of body weight, and production of coordinated limb movements for 8 weeks, 2 times per week, 90 minutes per session. Throughout the training of body weight transfer, the instructions emphasized conscious perception and control of the center of body stability, trunk and limb alignment, and stepping kinematics during the practice of each walking phase. Results: According to the results, compared with pre-training data, foot clearance, pre-&post-obstacle distance, delay time, and total obstacle crossing time were increased after intervention. In addition, body COM measures indicated that body sway and movement variability, therefore posture stability during obstacle crossing, showed improvement after training. Based on these results, body sway was reduced and stepping pattern became more consistent during obstacle crossing gait after participation in patients with cerebellar ataxia. Conclusion: Findings of this study suggest that task-relevant obstacle crossing training may have a beneficial effect on recovery of functional gait ability in patients with cerebellar disease.