• Journal of IKEEE
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• v.19 no.3
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• pp.288-294
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• 2015

CRC function has been built into the high-speed semiconductor memory device in order to increase the reliability of data for high-speed operation. Also, DBI function is adopted to improve of data transmission speed. Conventional CRC(ATM-8 HEC code) method has a significant amounts of area-overhead(~XOR 700 gates), and processing time(6 stage XOR) is large. Therefore it leads to a considerable burden on the timing margin at the time of reading and writing of the low power memory devices for CRC calculations. In this paper, we propose a CRC method for low cost and high speed memory, which was improved 92% for area-overhead. For low-cost implementation of the CRC scheme by the DBI function it was supplemented by data bit error detection rate. And analyzing the error detection rate were compared with conventional CRC method.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.333-340
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• 2018

This paper introduces a BCH code decoder using parallel CRC(: Cyclic Redundancy Check) generation. Using a conventional parallel syndrome generator with a LFSR(: Linear Feedback Shift Register), it takes up a lot of space for a short code. The proposed decoder uses the parallel CRC method that is widely used to compute the checksum. This scheme optimizes the a syndrome generator in the decoder by eliminating redundant xor operation compared with the parallel LFSR and thus minimizes chip area and propagation delay. In simulation results, the proposed decoder has accomplished propagation delay reduction of 2.01 ns as compared to the conventional scheme. The proposed decoder has been designed and synthesized in $0.35-{\mu}m$ CMOS process.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.473-480
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• 1996

Synthesis of n-perfluorooctanesulfonyl fluoride(n-PFOSF), which is valuable precursor perfluoro-chemicals, was studied by electrochemical fluorination(ECF). Of prime concern was to investigate the cyclic voltamograms of Ni electrode in anhydrous hydrogen fluoride(AHF) with and without the reactants and to measure fluorine evolution potential. In a batch cell, chronoampherometric electrolysis and various chemical analysis such as GC, GC/MS and IR were used to understand the amphere change of electrode and the reaction paths. Fluorine equilibrium potential was found to be about 2.8V(vs. $Cu/CuF_2$) from the cyclic voltammograms and decay curves of anode potential in AHF. In batch processes, the ECF proceeded in two distinguished steps. The first step proceeded electrochemically and the second one chemically. Under 7V(vs. $Cu/CuF_2$), amount of crude products was proportional to the applied anode potential. Above 7V(vs. $Cu/CuF_2$), it had a hundred percentage with weight ratio of reactants and productivity of PFOSF was almost constant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.113-122
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• 2010

In this paper, we propose a CP (Cyclic Prefix) detection based SSS (Secondary Synchronization Signal) detection method for initial cell search in 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) FDD/TDD (Frequency Division Duplex/Time Division Duplex) dual mode downlink receiver. In general, a blind coherent SSS detection method which can detect SSS without CP detection is applied. However, coherent detection method caused performance degradation by channel compensation error at high speed environment because it uses estimated CFR (Channel Frequency Response) at PSS (Primary Synchronization Signal), and it can be more serious problem in TDD mode due to increased distance between PSS and SSS. Also blind detectionhas the drawback of high computational complexity. Therefore, we proposed a CP type pre-decision structure with non-coherent SSS detection which has stable operation in high speed channel environments for 3GPP LTE TDD mode as well as FDD mode, and can reduce computational complexity by applying CP detection before SSS detection. Simulation results show that the proposed method has stable operation for 3GPP LTE TDD/FDD dual mode downlink receiver in various channel environments.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2139-2146
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• 2023

During reactor operation, the divertor must withstand unprecedented simultaneous high heat fluxes and high-energy neutron irradiation. The extremely severe service environment of the divertor imposes a huge challenge to the bonding quality of divertor joints, i.e., the joints must withstand thermal, mechanical and neutron loads, as well as cyclic mode of operation. In this paper, potassium-doped tungsten (KW) is selected as the plasma facing material (PFM), oxygen-free copper (OFC) as the interlayer, oxide dispersion strengthened copper (ODS-Cu) alloy as the heat sink material, and reduced activation ferritic/martensitic (RAFM) steel as the structural material. In this study, a vacuum brazing technology is proposed and optimized to bond Cu and ODS-Cu alloy with the silver-free brazing material CuSnTi. The most appropriate brazing parameters are a brazing temperature of 940 ℃ and a holding time of 15 min. High-quality bonding interfaces have been successfully obtained by vacuum brazing technology, and the average shear strength of the as-obtained KW/Cu and ODS-Cu alloy joints is ~268 MPa. And a fabrication route for manufacturing the flat-type divertor target based on brazing technology is set. For evaluating the reliability of the fabrication technologies under the reactor relevant condition, the high heat flux test at 20 MW/m² for the as-manufactured flat-type KW/Cu/ODS-Cu/RAFM mockup is carried out by using the Electron-beam Material testing Scenario (EMS-60) with water cooling. This paper reports the improved vacuum brazing technology to connect Cu to ODS-Cu alloy and summarizes the production route, high heat flux (HHF) test, the pre and post non-destructive examination, and the surface results of the flat-type KW/Cu/ODS-Cu/RAFM mockup after the HHF test. The test results demonstrate that the mockup manufactured according to the fabrication route still have structural and interfacial integrity under cyclic high heat loads.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.695-700
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• 2014

Proton Exchange Membrane Fuel Cells (PEMFC) can generate hydrogen and oxygen from water by electrolysis. But the electrode and polymer electrolyte membrane degrade rapidly during PEM water electrolysis because of high operation voltage over 1.7V. In order to reduce the rate of anode electrode degradation, unsupported $IrO_2$ catalyst was used generally. In this study, Pt/C catalyst for PEMFC was used as a water electrolysis catalyst, and then the degradation of catalyst and membrane were analysed. After water electrolysis reaction in the voltage range from 1.8V to 2.0V, I-V curves, impedance spectra, cyclic voltammograms and linear sweep voltammetry (LSV) were measured at PEMFC operation condition. The degradation rate of electrode and membrane increased as the voltage of water electrolysis increased. The hydrogen yield was 88 % during water electrolysis for 1 min at 2.0V, the performance at 0.6V decreased to 49% due to degradation of membrane and electrode assembly.

• The Korean Journal of Nuclear Medicine
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• v.24 no.1
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• pp.108-118
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• 1990

It is well known that the glucocorticoid suppresses the osteoblast and the calcitonin suppresses the osteoclast. If the calcitonin prevents the osteoporosis with increased Tc-99m MDP uptake in the long-term use of glucocorticoid, then the calcitonin has some activating effect on the bone formation. The immobilization operation was done on the left hind-leg of 16 male Sprague-Dawley rats weighing about 300 g each. For 12 weeks after operation,8 rats were injected 0.5 mg/kg dexamethasone, and the other 8 rats were injected 0.5 mg/kg dexamethasone and $1\;\bar{u}/kg$ eel calcitonin. The bone mineral content was measured by the single photon absorptiometry and the Tc-99m MDP uptake was used as an index of the osteoblastic activity. 1) The Tc-99m MDP uptakes in the dexamethasone treated group were lower than those in the dexamethasone and calcitonin treated group, and there was no significant difference in Tc-99m MDP uptakes between the immobilized and normal femurs. 2) The bone mineral contents in the dexamethasone treated group were significantly lower than in the dexamethasone and calcitonin treated group, and the immobilized femurs had tower BMC than normal femurs. 3) The slope of regression between the BMC and Tc-99m MDP uptake was stiff in the dexamethasone treated group, and flat in the dexamethasone and calcitonin group, which shows discrepancy between the bone resorption and formation resulting prevention of net bone loss in the dexamethasone and calcitonin treated group. In conclusion, the calcitonin has some effect on the bone formation, and further studies with urinary hydroxyproline and cyclic AMP are expected.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.1
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• pp.122-129
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• 2019

Due to its nature the manufacturing industry faces a cyclical economy, and therefore there is an urgent need for a companion industry to cope with this cyclic pattern in the long run. The sector suitable for meeting this demand is the repair and shipbuilding industry. In order to operate a shipbuilding repair business, a floating dock is indispensable, and most obsolete floating docks were imported from overseas and operated through repair/maintenance. However, there is no precise guideline for floating dock safety, and most models have been in use for at least 30 years without being required to enter classification at the time of operation. In this study, structural strength analysis was carried out using measured thickness information of aged floating docks, and the residual structural strength of floating docks in operation was analyzed. The main results derived from this study can be referred to as guidelines for the review of the structural safety of similar equipment, and it is expected that an optimal solution will be found within a short time using this method for repair/maintenance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.322-323
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• 2022

The most necessary thing for the optimal operation of a water purification plant is to accurately predict the pattern and amount of tap water used by consumers. The required amount of tap water should be delivered to the drain using a pump and stored, and the required flow rate should be supplied in a timely manner using the minimum amount of electrical energy. The short-term demand forecasting required from the point of view of energy optimization operation among water purification plant volume predictions has been made in consideration of seasons, major periods, and regional characteristics using time series analysis, regression analysis, and neural network algorithms. In this paper, we analyzed energy management methods through AI-based complex sensor applicability analysis such as LSTM (Long Short-Term Memory) and GRU (Gated Recurrent Units), which are types of cyclic neural networks.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.115-126
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• 2007

The tilting-train is very attractive to the railroad users in the world because it runs with high speed in curved track using pre-existing infrastructure. The tilting-train has a unique allowable speed and mechanism expecially in curved track. Therefore, it should be evaluated in terms of the stability of the train operation and roadbed. In this study, when the tilting-train is being operated with the allowable speed, the behavior of the roadbed is evaluated by examining the settlement and bearing capacity of the roadbed. Additionally, the stability of the roadbed is estimated in the condition of soft roadbed influenced by the weather effects and cyclic train loading. The numerical results show that the roadbed settlements satisfy the allowable settlement when Young's moduli of the upper roadbed and in-situ soil are more than $2,300t/m^2\;and\;3,300t/m^2$, respectively, in the continuous welded rail (CWR) and $3,800t/m^2\;and\;4,600t/m^2$, respectively, in the rail joint.