• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1533-1539
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• 2000

In this paper, we propose a design method using Taguchi method and a neural network. Using this method, we can design a dual-stage actuator having the required tracking/focusing properties in real time. Also, as an application of this method, a proposed dual-stage pick-up actuator having the required properties was designed. The seek time of this designed actuator is less than 13 msec by a time optimal technique. Simulation results show that this method can potentially be implemented in all the dual-stage actuators.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1056-1061
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• 2000

Particles existing in a hard disk drive are known as a major source of TA(thermal asperity). Researchers have investigated how particles induce the TA phenomena, but have not verified yet the reason why and how particles are generated in a HDD. The objective of this study is to investigate why and how particles are generated, and in what condition, the largest number of particles is generated. The number of particles generated in a HDD was measured over the landing zone after various rest times of slider and during various motions and positions of slider. It is found that the large number of particles was generated when the HDD was turned on after a long rest time of slider and that a few of particles were continuously generated when the slider flied over the disk surface. It is thought that the number of particles generated in a HDD was related to the rest time of slider because the rest time of slider increased stiction, and that there were intermittent contacts between the slider and the disk surface when the slider flied over the disk surface.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.1
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• pp.10-21
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• 2003

During seek operation in disk drives, the recording head is moved toward desired track by seek servo controller and then is settled onto the center of the desired track by settling servo controller. If the head speed at the start of settling servo control is not slow, it may produce overshoot relative to the center of track and thus extend the settling time. The degradation in settling performance will be more severe as the track width becomes smaller for higher density of data storage. We design a new settling servo controller for minimizing settling time based on the pole-zero cancellation. In order to cancel slow poles in settling response, we apply discrete pulse signals to the system in addition to the state feedback control. For exact pole-zero cancellation, we consider the dynamics of power amplifier used for actuator current regulation and the effects of delay in control action. In addition, we present system parameter identification algerian for the robustness of our controller to system parameter variation. In order to demonstrate the practical use of our controller, we present experimental results obtained by using a commercially available disk drive.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.111-117
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• 1990

This paper treats the problem to schedule for train with low transit priority so as to maximizing the number that can be sent during given time without interfering with the fixed schedule for train with high transit priority in a track. We transform the this problem into Time-Expanded Network without traverse time through application of Ford-Fulkerson Model, develop a TENET GENerator(TENETGEN) and obtain the data of TENET using developed TENETGEN. Finally, we seek the optimal solution to these data with Dinic's Maximal-Flow Algorithm and examine the availability of our procedures in personal computer.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.8
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• pp.65-73
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• 1997

The effects of time-sampling on linear output regulation problem is ivestigated. It is found that the solvability of linear output regulation problem is generally not robust with respect to time-sampling although the solvability of that for single inut and single output linear systems and the solvability of linear robust output regulation problem are preserved under time-sampling. The resutls imply that one needs to seek a better approximate sampled-data output regulator.

• Cross-Cultural Studies
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• v.34
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• pp.43-68
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• 2014

This writing, focused on by Tarkovsky and by Song, Il-gon, examines moments of sage which is what Eliade described as 'hierophanic time'. These productions, which can be seen as movies that seek after the truth, show important paradoxical ideas and expressions in those moments. This is because symbolic messages from unrealistic and out of ordinary images are specifically shown. If they had to be compared, through the film by Tarkovsky, the technical civilization of contemporary society in an apocalyptic view is criticized and saved, or the prophetic will to not give up the desire for salvation is shown. In the process, the short shots which forces to show hierophanic time not only diversely visualized the author's ideological self-consciousness towards the conversion of the new world, but it also fulfills the metahistorical meanings mentioned by Eliade. However, in the film by Song, Il-gon, the realistic personal sufferings of three women is specifically shown first in extreme. They overcome their unsolvable problems through mysterious rituals and belief in miracles. In the scenes that include hierophanic time, there are many cases that cover Christian faith and the meaning of salvation. In other words, we can say that hierophanic time in , are related to conviction which led to moments of miracles in order to overcome reality. Therefore, even though there is a difference in the way authors use hierophanic time, the scenes that show it in the two movies display individuality of mythical imaginations disclosed by Eliade. This is because the general hope for reproduction, or meaningful symbols related to the ideal conversion of affairs are revealed.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.614-620
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• 2006

Today the automobile has been changed from a mechanical system to an electronic control system fly the development of the electronic technology. In the automobile body, most of these electronic control devices are networked and managed fully by the CAN protocol. But, when a network system is overloaded, unexpected transmission delay for relative low priority objects occurs due to the static priority definition of the CAN protocol. To resolve this problem, this paper proposes a dynamic precedence queue mechanism that creates a queue for the low priority object and its relevant objects to be transmitted, which becomes urgent in an overloaded network system to keep the maximum allowable time delay. For the generated queue, the highest priority is assigned to transmit the queued objects within the shortest time. The mechanism is implemented in the logical link layer of CAN, which does not require any modification of the old CAN hardware. Effectiveness of the proposed mechanism is verified by the real experiments with an automobile network system.

• Bulletin of the Korean Chemical Society
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• v.10 no.4
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• pp.372-374
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• 1989

The new viscosity theory is applied to the abnormal behavior of the viscosity near the critical point. This theory suggests that the viscosity is equal to the product of the absolute pressure(kinetic pressure + internal pressure) and the collision time. We can find this abnormal behavior to be due to the large collision time near the critical point. The agreements between theoriticals and experimentals of the critical enhancement are satisfactory.

• Journal of Environmental Health Sciences
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• v.35 no.2
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• pp.116-123
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• 2009

Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus by the variation of aeration time in four sequencing batch reactors (SBRs). In R1 which has the shortest aeration time as 1 h, MLVSS concentration in reactor decreased by the wash-out of biomass because of the poor sedimentation. The TOC removal efficiencies were almost similar in 3 reactors except R1. At the low aeration time as 1 h, the nitrification was severely inhibited by the deficiency of oxygen. ${NH_4}^+$-N removal efficiency was decreased by the decrease of aeration time. At the aeration time over 2 h, the phosphorus removal efficiency was not affected by the variation of aeration time. The nitrification was inhibited but the phosphorus release and uptake was not inhibited by the decrease of low aeration time. Therefore, we can see that the phosphorus removal microorganisms are superior to nitrification microorganisms in oxygen utilization.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.12
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• pp.660-673
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• 2001

In Video-on-Demand (VoD) servers, disk throughput is an important system design parameter because it is directly related to the number of user requests that can be served simultaneously. In this paper, we propose an efficient periodic request grouping scheme for disk array-based VoD servers that reduces the disk seek time, thus improving the disk throughput of VoD disk arrays. To reduce the disk seek time, the proposed scheme groups the periodic requests that access data blocks stored in adjacent regions into one, and arranges these groups in a pre-determined order (e.g., in left-symmetric or right-symmetric fashion). Our simulation result shows that the proposed scheme reduces the average disk bandwidth required by a single video stream and can serve more user requests than existing schemes. For a data block size of 192KB, the number of simultaneously served user requests is increased by 8% while the average waiting time for a user request is decreased by 20%. We also propose an adaptation technique that conforms the proposed scheme to the user preference changes for video streams.