• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.746-752
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• 2016

In this study, soft carbon was prepared by carbonization of carbon precursor (pitch) obtained from PFO (pyrolysis fuel oil) heat treatment. Three carbon precursors prepared by the thermal reaction were 3903 (at $390^{\circ}C$ for 3 h), 4001 (at $400^{\circ}C$ for 1 h) and 4002 (at $400^{\circ}C$ for 2 h). After the prepared soft carbon was ground to a particle size of $25{\sim}35^{\circ}C$, the soft carbon was synthesised by the chemical treatment with boric acid ($H_3BO_3$). The prepared soft carbon were analysed by XRD, FE-SEM and XPS. Also, the electrochemical performances of soft carbon were investigated by constant current charge/discharge test, cyclic voltammetry and impedance tests in the electrolyte of $LiPF_6$ dissolved inorganic solvents (EC:DMC=1:1 vol%+VC 3 wt%). The coin cell using soft carbon of $25{\sim}35^{\circ}C$ with 3903 soft carbon ($H_3BO_3$/Pitch=3:100 in weight) has better initial capacity and efficiency (330 mAh/g, 82%) than those of other coin cells. Also, it was found that the retention rate capability of 2C/0.1C was 90% after 30 cycles.

• Journal of the Korean GEO-environmental Society
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• v.17 no.1
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• pp.13-19
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• 2016

Soft ground stabilization is needed to construct large civil facilities on the soft clay ground. Pre-loading method, which is accelerating consolidation method, is generally used to stabilize the soft ground. However, pre-loading method is required long construction period and quantities of fill material. Therefore, electro-osmosis method is used to replace pre-loading method for stabilizing the soft ground. Electro-osmosis method is disadvantageous in constructive and economic aspects because it is needed a metallic electrode. So, in order to solve the those disadvantages, plastic electrode was developed to replace metallic electrode. Plastic electrode, which is made by using nano-technology on existing Plastic Drain Board (PDB), was used to supply the electric power. In this study, therefore, the model test was conducted to confirm the effect of improvement and electrical characteristics of soft ground by spacing of plastic electrode. The result shows that the effect of improvement of soft ground was decreased up to 45% by increasing electrode spacing and electrical characteristics on the soft ground were influenced by consolidation settlement with electrode spacing.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.295-300
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• 2001

A variety of high voltage DC power supplies employing the high frequency inverter are difficult to achieve soft switching considering a quick response and no overshoot response under the wide load variation ranges which are used in medical-use x-ray high voltage generator from 20kV to 150kV in the output voltage and from 0.5mA to 1250mA, respectively. The authors develops soft switching high voltage DC power supply designed for x-ray power generator applications, which uses series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the second-side of a high-voltage transformer with a large turn ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary transformer turn-numbers and stray capacitance of high-voltage transformer is effective to be greatly reduced. It is proved that the proposed high-voltage converter topology with dual mode frequency modulation mode control scheme is able to be the transient response and steady-state performance in high-voltage x-ray tube load. The effectiveness of this high voltage converter is evaluated and discussed on the basis of simulation analysis and observed data in experiment.

• Geomechanics and Engineering
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• v.28 no.4
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• pp.385-396
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• 2022

The accurate determination of the subgrade reaction modulus (K_s) of soil is an important factor for geotechnical engineers. This study estimated the K_s of soft soil improved with floating deep cement mixing (DCM) columns. A novel prediction model was developed that emphasizes the accuracy of identifying the most significant parameters of K_s. Several multi-layer perceptron (MLP) models that were trained using the Levenberg Marquardt (LM) backpropagation method were developed to estimate K_s. The models were trained using a reliable database containing the results of 36 physical modelling tests. The input parameters were the undrained shear strength of the DCM columns, undrained shear strength of soft soil, area improvement ratio and length-to-diameter ratio of the DCM columns. Grey wolf optimization (GWO) was coupled with the MLPs to improve the performance indices of the MLPs. Sensitivity tests were carried out to determine the importance of the input parameters for prediction of K_s. The results showed that both the MLP-LM and MLP-GWO methods showed high ability to predict K_s. However, it was shown that MLP-GWO (R = 0.9917, MSE = 0.28 (MN/m²/m)) performed better than MLP-LM (R =0.9126, MSE =6.1916 (MN/m²/m)). This proves the greater reliability of the proposed hybrid model of MLP-GWO in approximating the subgrade reaction modulus of soft soil improved with floating DCM columns. The results revealed that the undrained shear strength of the soil was the most effective factor for estimation of K_s.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.2
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• pp.116-123
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• 2014

In this paper, a soft-switching scheme for the PWM interleaved buck converter(IBC) is newly proposed to obtain the advantages of both the conventional PWM interleaved buck and resonant converters such as ease of control, reduced switching losses and stresses, and low EMI. To obtain the soft-switching action, the proposed scheme employs an auxiliary circuit, which is added to the conventional interleaved buck converter and used to achieve soft-switching for both the main switches and the output diodes while not incurring any additional losses due to the auxiliary circuit itself. In this paper, the basic operations are discussed and design guidelines are presented. And through the experimental results, the usefulness of the proposed converter is verified.

• Journal of Information Processing Systems
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• v.7 no.3
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• pp.435-446
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• 2011

Microprocessors are becoming increasingly vulnerable to soft errors due to the current trends of semiconductor technology scaling. Traditional redundant multi-threading architectures provide perfect fault tolerance by re-executing all the computations. However, such a full re-execution technique significantly increases the verification workload on the processor resources, resulting in severe performance degradation. This paper presents a pro-active verification management approach to mitigate the verification workload to increase its performance with a minimal effect on overall reliability. An anomaly-speculation-based filter checker is proposed to guide a verification priority before the re-execution process starts. This technique is accomplished by exploiting a value similarity property, which is defined by a frequent occurrence of partially identical values. Based on the biased distribution of similarity distance measure, this paper investigates further application to exploit similar values for soft error tolerance with anomaly speculation. Extensive measurements prove that the majority of instructions produce values, which are different from the previous result value, only in a few bits. Experimental results show that the proposed scheme accelerates the processor to be 180% faster than traditional fully-fault-tolerant processor with a minimal impact on overall soft error rate.

• Journal of Ocean Engineering and Technology
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• v.10 no.4
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• pp.141-148
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• 1996

Use of stone column for deep ground treatment in soft clay soils is an effective method. The stone column significantly increases load carrying capacity of the soft clay soil. A analysis method for bearing capacity of stone column in soft clay soil is developed. The capacity made by developed method are compared wity observed values from field load test and a reasonable correlation is noted.

• Carbon letters
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• v.10 no.2
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• pp.109-113
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• 2009

Various silanes, amino silane, vinyl silane, TESPD, and ZS (TESPD/zinc soap complex), are added into chlorinated isobutylene-isoprene copolymer (CIIR)/soft clay/carbon black (CB). The vulcanization characteristics, the processability, and the mechanical properties are measured. In soft clay/CB filled CIIR system, there are no significant changes in Mooney viscosity among compounds. Vinyl silane added compound shows a low extrusion torque. All the silane added compounds shows an increased modulus. The mechanical properties are significantly increased when the S2 is added into CIIR/soft clay/CB compounds.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1596-1612
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• 2011

Coordinated Multi-Point (CoMP) transmission / reception is being studied in Long Term Evolution-Advanced (LTE-A) for future evolution of the $3^{rd}$ Generation Partnership Project (3GPP) LTE. Support of soft handover is essential for improving the performance of cell edge users. CoMP provides a natural framework for enabling soft handover in the LTE system. This paper evaluates the soft handover gain in LTE-A downlink. Mathematical analysis of signal to interference plus noise ratio (SINR) gain and the handover margins for soft handover and hard handover are derived. CoMP system model is developed and an inter-cell and intra-cell interference model is derived, taking into account the pathloss, shadowing, cell loading, and traffic activity. Reference signal received power (RSRP) is used to define the triggers and the measurements for soft handover. Our results indicate that parameter choices such as handover margin and the CoMP set size impact CoMP performance gain.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.6
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• pp.393-400
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• 2011

Recently, demands of information devices are increasing as we can find so many information devices around us such as smartphone, MID(Mobile Internet Device), Tablet. These characteristics of information devices services should support soft real-time based time guaranteed multimedia services and control internet appliances. In this situation, soft real-time supported system should be developed to consider as a total aspect of hardware, kernel, middleware, application. But this paper will describe soft real-time supporting and evaluation methods for information device as an aspect of only kernel.