• Transactions of the Society of Information Storage Systems
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• v.3 no.4
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• pp.196-201
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• 2007

As the demand for the lap-top computer has been increased, most users ask quiet environment to work comfortably. Therefore, noise problems of an ODD are of great interest. For the high speed ODD, the flow induced noise is caused by the turbulent flow[1], which is known to be a major source of overall noise of a slim type ODD. In this study, we introduce a new attempt to reduce the noise level using the concept of Helmholtz resonator[2].The experimental analysis is carried out for several cases at different resonance frequencies and different hole patterns. The results show reductions in the noise level from the acoustic noise absorption point of view.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.65-70
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• 2022

A vacuum system is designed for thermal insulation of a 10 ton/day class air liquefaction cold box for liquid air energy storage. The vacuum system is composed of a turbomolecular pump, a backing pump and vacuum piping for the vacuum pumps. The turbomolecular pump is in combination with the backing pump for pumping capacity. The vacuum piping is designed with system installation conditions, such as distance from the cold box, connections to vacuum pumps and installation space. The capacity of the vacuum pump combination, namely pumping speed, is determined by analysis of the vacuum system, and pump-down time to 1×10^-5 mbar is estimated. Vacuum piping conductance, system pumping speed and outgassing rate are calculated for the pump-down time with the ultimate pumping speed range of the vacuum pump combination of 1400 - 2300 l/s. Although the pump-down time gets shorter by larger capacity vacuum pumps, it mainly depends on target vacuum degree and outgassing rate in the cold box. The pump-down time is estimated as 3 - 6 hours appropriate for cold box operation for the pumping speed range. Considering the outgassing rate has uncertainty, the vacuum pump combination with pumping speed of 1900 l/s is chosen for the vacuum system, which is middle value of the pumping speed range.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1167-1170
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• 2007

This paper introduces a data storage transport protocol internet Advanced Technology Attachment (iATA) for ATA storage devices that can be accessed over (TCP/IP) networks. As the access speed of Advanced Technology Attachment (ATA) type storage is increasing, the importance of sharing the ATA type storages over internet is also increasing. We are proposing a protocol in which we have implemented the basic ATA command set to access the ATA type remote storage devices over the TCP/IP networks.In this paper, we give basic details of the protocol and discuss the existing storage protocols which are mainly used for accessing block storage like internet Small Computer System Interface (iSCSI) Hyper Small Computer System Interface (HyperSCSI) and ATA over Ethernet (AoE).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.5
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• pp.136-146
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• 2012

As information technology used for simulation and virtual reality developed, there is a growing interest in animation technologies which will effectively deliver simulation results to users. Various efforts have been made to improve animation performance, like playback quality and speed, input-output speed and storage space reduction. However, earlier studies generally focused on image compression frame by frame. To significantly improve storage space and playback speed, animation data should be vectorized. Also, spatial and temporal duplication have to be removed. In this study, animation data structure was improved fundamentally through establishment of hierarchy and vectorization. Also Spatial and temporal duplication of animation data was removed through vectorization based on train route. As a result, storage space was reduced, input-output speed and playback speed were considerably improved. According to the test, additional Patternization which followed vectorization brought reduction of over 80% in storage space and input-output speed was quadrupled. Patternization technology can be used as a proper storage method of animation data, and can provide user-specific animation by small data transmission.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.538-545
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• 2020

The outdoor coal storage sheds of thermal power plants are being converted to indoor coal storage sheds worldwide because of the environmental pollution problems in the surrounding areas. On the other hand, indoor coal storage sheds are causing problems, such as indoor coal scattering and harmful gas generation. In this study, the ventilation method of indoor coal storage sheds was analyzed in terms of the internal flow characteristics and ventilation according to the outside wind velocity and direction. CFD analysis was performed based on the actual flow measurement information inside the indoor coal storage sheds. A comparison of the wind speed of 6 m/s and 2 m/s when the outside wind direction was easterly showed that the stream velocity to the monitor louver was faster and the recirculation area was clearer at 6 m/s than at 2 m/s. In addition, the trend of a westerly wind was similar to that of the easterly wind. The ventilation rate according to the wind speed was 13.1 times and 4.4 times for a wind speed of 6 m/s and 2 m/s, respectively. If the wind speed is 2 m/s, the situation does not meet the required number of ventilations per hour in a general plant, and needs to be improved.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.254.2-254.2
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• 2014

The Transmission Fourier Transform Infrared spectroscopy (FTIR) of SiOx charge storage layer with the richest silicon content showed an assignment at peaks around 2000~2300 cm-1. It indicated that the existence of many silicon phases and defect sources in the matrix of the SiOx films. The total hysteresis width is the sum of the flat band voltage shift (${\Delta}VFB$) due to electron and hole charging. At the range voltage sweep of ${\pm}15V$, the ${\Delta}VFB$ values increase of 0.57 V, 1.71 V, and 13.56 V with 1/2, 2/1, and 6/1 samples, respectively. When we increase the gas ratio of SiH4/N2O, a lot of defects appeared in charge storage layer, more electrons and holes are charged and the memory window also increases. The best retention are obtained at sample with the ratio SiH4/N2O=6/1 with 82.31% (3.49V) after 103s and 70.75% after 10 years. The high charge storage in 6/1 device could arise from the large amount of silicon phases and defect sources in the storage material with SiOx material. Therefore, in the programming/erasing (P/E) process, the Si-rich SiOx charge-trapping layer with SiH4/N2O gas flow ratio=6/1 easily grasps electrons and holds them, and hence, increases the P/E speed and the memory window. This is very useful for a trapping layer, especially in the low-voltage operation of non-volatile memory devices.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3587-3594
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• 2022

A distributed high-speed data acquisition and monitoring system for the RF negative ion source at Huazhong University of Science and Technology (HUST) is developed, which consists of data acquisition, data forwarding and data processing. Firstly, the data acquisition modules sample physical signals at high speed and upload the sampling data with corresponding absolute-time labels over UDP, which builds the time correlation among different signals. And a special data packet format is proposed for the data upload, which is convenient for packing or parsing a fixed-length packet, especially when the span of the time labels in a packet crosses an absolute second. The data forwarding modules then receive the UDP messages and distribute their data packets to the real-time display module and the data storage modules by PUB/SUB-pattern message queue of ZeroMQ. As for the data storage, a scheme combining the file server and MySQL database is adopted to increase the storage rate and facilitate the data query. The test results show that the loss rate of the data packets is within the range of 0-5% and the storage rate is higher than 20 Mbps, both acceptable for the HUST RF negative ion source.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.485-490
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• 2004

Flywheel Energy Storage System(FESS) consists of a high speed flywheel with an integral motor/generator suspended on non contact bearings and in an evacuated housing. Permanent magnet machines as the FESS motor/generator are a popular choice, since there are no excitation losses which means substantial increase in the efficiency. In this paper, the structural design method of rotor retainer for a high speed motor/generator are presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1750-1756
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• 2009

In this paper, 5 kWh class Superconductor Flywheel Energy Storage System (SFES) was constructed including motor/generator, superconductor magnetic bearing(SMB), composite rotor and electromagnetic damper(EMD) system. High speed rotation test was performed after levitating flywheel rotor only using EMD without SMB. the PD controller of EMD was designed. the control system is constructed using xPC which is real time digital control system. the results of high speed rotation test showed that proposed EMD system have sufficient damping in cylindrical mode and conical mode, and vibration of wheel was suppressed below 10 ${\mu}m$.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.49
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• pp.1-10
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• 1999

A cost minimization model for designing AS/RS (Automated Storage/Retrieval Systems) has been developed, whose objective function includes penalty cost caused by the incapability of meeting throughput rate requirements as well as S/R machine cost, storage rack cost, and interface conveyor cost. Since the model is a nonlinear integer programming problem which is very hard to solve with large problem size the problem is divided into four cases according to the ratio of horizontal S/R machine speed to its vertical speed and the existence of the penalty cost. A solution procedure is developed which solves each problem exactly under the different number of S/R machines.