• Journal of Korean Society of Water and Wastewater
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• v.23 no.2
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• pp.207-214
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• 2009

This study examines the optimum filtration conditions in pretreatment of seawater desalination by reverse osmosis. For this purpose, Masan bay seawater is treated through a gravity filter column while $FeCl_3$ is added as coagulant. The conditions of coagulantd osage, media depth, filtration rate, and backwash time are evaluated. The study results show that the filtrate quality improved with increasing coagulant dosage, but head loss rapidly increased. After 4mg/L, the unit filter run volume reduced to less than $200m^3/m^2$. Considering the head loss development, 4mg/L is determined as the optimum dosage. The better filtrate qualities are obtained with depth of 100cm than that of 80cm. The two stage filtration, which outperformed the single stage filtration, is suggested for treatment of Masan bay. The filtration rate of 5m/h is decided as the optimum condition considering the head loss development. At 10m/h, the filtrate quality deteriorated even though the extent was minimal, and head loss increased rapidly. The backwash time of 10 min is decided appropriate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1684-1699
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• 2017

The deblocking filter (DF) reduces blocking artifacts in encoded video sequences, and thereby significantly improves the subjective and objective quality of videos. Statistics show that the DF accounts for 5-18% of the total decoding time in high-efficiency video coding. Therefore, speeding up the DF will improve codec performance, especially for the decoder. In view of the rapid development of multicore technology, we propose a parallel DF scheme based on a modified order of accessing the coding tree units (CTUs) by analyzing the data dependencies between adjacent CTUs. This enables the DF to run in parallel, providing accelerated performance and more flexibility in the degree of parallelism, as well as finer parallel granularity. We additionally solve the problems of variable privatization and thread synchronization in the parallelization of the DF. Finally, the DF module is parallelized based on the HM16.1 reference software using OpenMP technology. The acceleration performance is experimentally tested under various numbers of cores, and the results show that the proposed scheme is very effective at speeding up the DF.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.254-269
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• 2004

Polysilicato-iron coagulant (PSI) is receiving attention in Japan as a substitute for aluminum-based coagulants. In the first part of this article, coagulation, sedimentation and filtration experiments were carried out using kaolin clay particles as the turbidizing material and four types of PSI with various molar ratios of polysilicic acid to ferric chloride (Si/Fe ratio). Results demonstrate that use of a PSI with a high Si/Fe ratio can cause a more dramatic decrease in treated water turbidity but a higher suction time ratio (STR) than when PACl is used. However, optimization by increasing the rapid agitation strength GR is found to greatly improve the STR. In addition, the series of filtration experiments verified that optimization of GR is greatly effective in controlling rapid increases in filter head loss, and also formation of a thin aging layer in the upper part of the filter bed by slow-start filtration is effective in improving filtered water turbidity over the entire filtration process. The second part of this article describes two innovative filtration techniques to increase the particle separation efficiency; (1) coagulant-coated filter medium by enhancing the electrical potential of the surface of the filter medium, and (2) coagulant dosing in influent by controlling the electrical potential of particles entering the filter layer. From the results of the various filtration experiments using a pilot plant, these two techniques were found to be very effective to reduce the effluent water turbidity from the start to the end of a filter run. Moreover, in the filtration experiments using these two methods simultaneously, higher removal efficiency of approximately 3-log (99.7%) was realized, resulting that the finished water turbidity was accordingly reduced to 0.004mg/L.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.1123-1126
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• 1999

In this paper, we propose a real-time implementation of the MPEG-1 layer III and MPEG-2 layer III LSF audio decoding system based on OAK DSP Core. In order to solve the problem of resolution, the system has been used floating-point operation and double precision in dequantization module. The size of ROM is reduced by using the Run-length algorithm of reordered index. The subband synthesis filter module is optimized to have low computational complexity in terms of the size of ROM or RAM. To construct a efficient system, we used both the DSP Core and Parser-Huffman decoder which is implemented with VHDL.

• Journal of Pharmaceutical Investigation
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• v.30 no.1
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• pp.51-54
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• 2000

A column-switching high performance liquid chromatographic method has been developed for the determination of a fluconazole in human plasma. Each plasma sample was centrifuged for 10 min at 5000 g. After an aliqout of the supernatant was taken to nylon microcentrifuge filter, these samples were centrifuged for 10 min at 5000 g. An aliqout of the supernatant was injected directly onto the HPLC column. Deionized water was run for 2 min at a flow rate of 1.0 ml/min to retain fluconazole in an extration column, while proteins and endogenous interferences were eluted to the waste. The analyte was then back-flushed onto an analytical column, $C_{18}$ reversed-phase column. The mobile phase for analytical column, 0.01 M sodium acetate (pH 5.0)-methanol (65:35, v/v), was run at a flow rate of 1.0 ml/min. The column effluent was monitored by ultraviolet detection at 261 nm. The retention time for fluconazole was 11.76 min in human plasma. The detection limit for fluconazole in human plasma was $0.2\;{\mu}g/ml$. No interference from endogenous substances was observed.

• Journal of Digital Contents Society
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• v.19 no.6
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• pp.1207-1212
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• 2018

The ultrasound image uses ultrasonic pulses to receive the reflected waves and construct an image necessary for diagnosis. At this time, when the signal becomes weak, noise is generated and a slight difference in brightness occurs. In addition, fluctuation of image due to breathing phenomenon, which is the characteristic of ultrasound image, and change of motion in real time occurs. Such a noise is difficult to recognize and diagnose visually in the analysis process. In this paper, morphological features are automatically extracted by using image processing technique on ultrasound acquired images. In this paper, we implemented a GPU - based fast filter using a cloud big data processing platform for image processing. In applying the GPU - based high - performance filter, the algorithm was run with performance 4.7 times faster than CPU - based and the PSNR was 37.2dB, which is very similar to the original.

• Journal of IKEEE
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• v.22 no.2
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• pp.460-475
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• 2018

In the variable-speed wind energy system, to achieve maximum power point tracking (MPPT), the wind turbine should run close to its optimal angular speed according to the wind speed. Non-linear control methods that consider the dynamic behavior of wind speed are generally used to provide maximum power and improved efficiency. In this perspective, the mechanical power is estimated using Kalman filter. And then, from the estimated mechanical power, the wind speed is estimated with Newton-Raphson method to achieve maximum power without anemometer. However, the blade shape and air density get changed with time and the generator efficiency is also degraded. This results in incorrect estimation of wind speed and MPPT. It causes not only the power loss but also incorrect wind resource assessment of site. In this paper, the adaptive maximum power point tracking control algorithm for wind turbine system based on the estimation of wind speed is proposed. The proposed method applies correction factor to wind turbine system to have accurate wind speed estimation for exact MPPT. The proposed method is validated with numerical simulations and the results show an improved performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.217-224
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• 2002

One of the dominant aspects governing the accuracy of the FDTD method is the size of the spatial increment used in the model. The effect of having reduced cell size is to increase the computational time and memory requirements. To overcome these problems, sub-gridding technique can be used. This implies that the application of a sub-grid cell would provide improved accuracy without increasing the run time and computer resources considerably. In this paper, we describe the three dimensional sub-gridding technique that is applied to model only the fine structure region of interest. The detailed solution procedure is described and some test geometries were solved by both uniform grid and sub-grid models to validate the suggested approach. While keeping the accuracy, the computational time becomes 6 times faster and the memory requirement is reduced by a factor of 2.5 comparing to the conventional FDTD approach.

• Journal of Environmental Science International
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• v.24 no.12
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• pp.1551-1558
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• 2015

In Korea, many drinking water treatment plants (DWTPs) have introduced and are going to introduce biological activated carbon (BAC) process to treated dissolved organic matter (DOM) in water which are difficult to control by conventional water treatment processes. Even though more decade have passed since introduced BAC in Korea, most of BAC operating method was followed to the modified sand filter operating manuals. In case of BAC backwashing, many DWTPs set the periods of backwashing about 3~5 days. In this study, we have collected data to set the proper BAC backwashing periods from both pilot-plant and real DWTPs. We had measured heterotrophic plate count (HPC), turbidity, water temperature, dissolved organic carbon (DOC) and headloss from just after backwashing to the next backwashing time for two years. Considering water quality factors, the BAC run time from backwashing to the next backwashing could extend more 30 days without water quality deterioration if the head loss do not reach the limited level which depends on each BAC facilities' condition. It means the BAC treated water could be saved in the proportion of extended the backwashing period to the existing backwashing period.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.398-403
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• 2004

The demand of high speed machining is increasing because the high speed cutting providers high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting. The automatic control concept of magnetic bearing system provides ability of intelligent control of spindle system to increase accuracy and flexibility by means of adaptive vibration control. This paper describes a design and development of a milling spindle system which includes built-in motor with power 5.5㎾ and maximum speed 70,000rpm, HSK-32C tool holer and active magnetic bearing system. Magnetic actuators are designed for satisfying static load condition. The Performances of manufactured spindle system was examined for its static and dynamic stiffness, load capacity, and rotational accuracy. This spindle was run up to 70,000 rpm stably, which is 3.5 million DmN.