• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.6
• /
• pp.510-515
• /
• 2016

Recently, corrosion occurred on the piles of a marine bridge located on the NamHae expressway in Korea. A sacrificial anode cathodic protection system was installed to prevent corrosion damage in the marine bridge. In the case of the marine bridge in this study, the sacrificial anode cathodic protection system was applied at the tidal and splash zones of the piles because the upper part of the structure was not corroded, and because corrosion occurs at the tidal and splash zones due to sea tides. To verify the performance of the sacrificial anode cathodic protection system 8 years later, cathodic protection (CP) current, CP potential, and degree of depolarization were measured. The experimental results on the performance of the sacrificial anode cathodic protection system from a total of 60 piles were classified into 4 categories: good CP effect results (13 piles), partial CP effect results (27 piles), temporarily erroneous results (5 piles), and need for maintenance because of delamination (15 piles). It was determined that additional repairs are required, such as the application of bulk anodes and jacket casings, for piles where the CP effect is poor.

• Journal of the Korean institute of surface engineering
• /
• v.39 no.4
• /
• pp.190-197
• /
• 2006

The effects of blasting and acidic treatment on the corrosion characteristics of dental implant fabricated with Cp-Ti and Ti-6Al-4V alloy have been researched by using electrochemical methods. The fabricated implants were cleaned and sandblasted by $Al_2O_3$ powder and then acidic treatment was carried out in nitric acid solution. The surface morphology were observed using scanning electron microscope. The corrosion behaviors were investigated using potentiosat and EIS in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The potentio-dynamic test in 0.9% NaCl indicated that the corrosion potential of blasting and acidic treated implant was lower than that of non treated implant, but current density was higher than that of non treated implant. From the cyclic potentiodynamic test results of Ti implant, the passivation current density of blasting and acidic treated implant slightly higher than that of non treated implant. From A.C. impedance test results in 0.9% NaCl solution, polarization resistance($R_p$) value of blasting and acidic treated implant was lower than that of non treated implant. In case of blasting and acidic treated implant surface, the pits were observed in valley and crest of implant surface.

• Physical Therapy Korea
• /
• v.19 no.3
• /
• pp.81-90
• /
• 2012

The aim of the current study was to assess the effectiveness of backward gait training on the treadmill in patients with spastic diplegic cerebral palsy (CP). Twelve patients with spastic diplegic CP participated in the study. An 8-week course of backward gait training was administered to the subjects for 3 days per week. Pre-intervention and post-intervention assessments of temporal-spatial gait parameters, the symmetry of the bilateral lower extremity weight bearing, and gross motor function were analyzed using motion analysis system, force plate, and Gross Motor Function Measurement (GMFM). There were significant improvements (p<.05) in the measures of both step length and right stance phase time. Joint kinematics showed increase in right hip abduction in initial contact and terminal swing, right hip external rotation and knee flexion in mid-swing, left ankle dorsiflexion in initial contact and terminal swing (p<.05). The symmetry of the bilateral lower extremity weight bearing and GMFM also significantly increased (p<.05). These findings indicate that backward gait training using a treadmill is beneficial for patients with spastic diplegic CP.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.7
• /
• pp.1007-1010
• /
• 2011

The objective was to evaluate in vitro prediction of ileal digestibility of protein and amino acids (AA) for current nursery pig diets (n = 10) by using pepsin and pancreatin incubations. To compare in vivo ileal digestibility, forty nursery pigs (4 pigs per diet) with an initial BW of $12.2{\pm}2.7$ kg were surgically equipped with T-cannula in the distal ileum. In all cases, the values of in vitro digestibility were higher than those of in vivo digestibility (p<0.05). With regard to the relationships of essential and non essential AA (CP), the $r^2$ value was 0.76. With regard to AA, high relationships were observed in Ile, Thr, and Gly (0.85, 0.83, and 0.89, respectively). Also, there was a lower relationship for Arg, Met, Ala, Asp, Glu, Pro, Ser, and Tyr with $R^2$ values of 0.56, 0.54, 0.40, 0.54, 0.45, 0.24, 0.49, and 0.35, respectively between in vitro and in vivo digestibility. The EAA relationship ($R^2$ = 0.71) was generally higher than that of NEAA ($R^2$ = 0.50) numerically. In conclusion, there were strong linear relationships between in vivo and in vitro ileal digestibility (CP, Ile, Thr, and Gly). In vitro prediction of ileal digestibility (CP, Ile, Thr, and Gly) seems to have significant potential for practical application.

• Korean Journal of Metals and Materials
• /
• v.50 no.5
• /
• pp.395-400
• /
• 2012

In this study, we have investigated the surface morphology of hydroxyapatite (HA) coated Ti alloy surface using pulsed laser plating. The HA (tooth ash) films were grown by pulsed KrF excimer laser, film surfaces were analyzed for topology, chemical composition, crystal structure and electrochemical behavior. The Ti-6Al-4V alloy showed ${\alpha}$ and ${\beta}$ phase, Cp-Ti showed ${\alpha}$ phase and the HA coated surface showed HA and Ti alloy peaks. The HA coating layer was formed with $1-2{\mu}m$ droplets and grain-like particles, particles which were smaller than the HA target particle, and the composition of the HA coatings were composed of Ca and P. From the electrochemical test, the pitting potential (1580 mV) of HA coated Ti-6Al-4V alloy was higher than those of Cp-Ti (1060 mV) and HA coated Cp-Ti (1350 mV). The HA coated samples showed a lower current density than non-HA coated samples, whereas, the polarization resistance of HA coated samples showed a high value compared to non-HA coated samples.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.17 no.6
• /
• pp.1600-1619
• /
• 2023

Organizations and other institutions have recently started using cloud service providers to store and share information in light of the Internet of Things (IoT). The major issues with this storage are preventing unauthorized access and data theft from outside parties. The Block chain based Security Sharing scheme with Data Access Control (BSSDAC) was implemented to improve access control and secure data transaction operations. The goal of this research is to strengthen Data Access Control (DAC) and security in IoT applications. To improve the security of personal data, cypher text-Policy Attribute-Based Encryption (CP-ABE) can be developed. The Aquila Optimization Algorithm (AOA) generates keys in the CP-ABE. DAC based on a block chain can be created to maintain the owner's security. The block chain based CP-ABE was developed to maintain secures data storage to sharing. With block chain technology, the data owner is enhancing data security and access management. Finally, a block chain-based solution can be used to secure data and restrict who has access to it. Performance of the suggested method is evaluated after it has been implemented in MATLAB. To compare the proposed method with current practices, Rivest-Shamir-Adleman (RSA) and Elliptic Curve Cryptography (ECC) are both used.

• Proceedings of the KIEE Conference
• /
• 2007.04a
• /
• pp.267-269
• /
• 2007

PLL(Phase Locked Loop) are widely used circuit technique in modern electronic systems. In this paper, We propose the low voltage and high speed PLL. We design the PFD(Phase Frequency Detector) by using TSPC (True Single Phase Clock) circuit to improve the performance and solve the dead-zone problem. We use CP(Charge Pump} and LP(Loop filter) for Negative feedback and current reusing in order to solve current mismatch and switch mismatch problem. The VCO(Voltage controlled Oscillator) with 5-stage differential ring oscillator is used to exact output frequency. The divider is implemented by using D-type flip flops asynchronous dividing. The frequency divider has a constant division ratio 32. The frequency range of VCO has from 200MHz to 1.1GHz and have 1.7GHz/v of voltage gain. The proposed PLL is designed by using 0.18um CMOS processor with 1.8V supply voltage. Oscillator's input frequency is 25MHz, VCO output frequency is 800MHz and lock time is 5us. It is evaluated by using cadence spectra RF tools.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.04a
• /
• pp.18-21
• /
• 2003

The effect of interface bonding strength on the recovery force of SMA wire reinforced polymer matrix composites was investigated by pullout test. Firstly, the recovery forces and transformation temperatures of various prestrained SMA wires were measured and 5% prestrained SMA wires were prepared for the reinforcements of composites. EPDM incorporated with 20vol% silicon carbide particles(SiCp) of 6, 12, $60{mutextrm{m}}$ size were used as matrix. Pullout test results showed that the interface bonding strength increased when the SiCp size decreased due to the increase of elastic modulus of matrix. Cyclic test of composites was performed through control of DC current at the constant displacement mode. The abrupt decrease of recovery force during cycle test at high current was occurred by thermal degradation of matrix. This was in good agreement with temperature related in the thermal degradation of matrix. The hysteresis of recovery force with respect to the temperature was compared between wire and composite and the hysterisis of composites was smaller than the wire due to less thermal conduction.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.1
• /
• pp.1-12
• /
• 2015

This paper discusses current internet interconnection issues according to radical changes of internet traffic pattern. In this context, the recovery of network investment cost for network provider becomes hot issue. For recovery issues of investment cost, there are many disputes among stake holders. Therefore, it is necessary to investigate this issues in the context of internet interconnection. Also, it is important to develop the current regulation about internet interconnection under traffic changing environments. This paper selects four issues to deal with and analyzes the present situations and problems about these issues, and provides alternatives for internet interconnection corresponding to these four issues.

• Corrosion Science and Technology
• /
• v.17 no.6
• /
• pp.310-316
• /
• 2018

The effect of passive film on corrosion of metals and alloys in a static corrosive environment has been studied by many researchers and is well known, however few studies have been conducted on the electrochemical measurement of metals and alloys during cavitation corrosion conditions, and there are no test standards for electrochemical measurements 'During cavitation' conditions. This study used commercially additive manufactured(AM) pure titanium in tests of anodic polarization, corrosion potential measurements, AC impedance measurements, and repassivation. Tests were performed in 3.5% NaCl solution under three conditions, 'No cavitation', 'After cavitation', and 'During cavitation' condition. When cavitation corrosion occurred, the passive current density was greatly increased, the corrosion potential largely lowered, and the passive film revealed a small polarization resistance. The current fluctuation by the passivation and repassivation phenomena was measured first, and this behavior was repeatedly generated at a very high speed. The electrochemical corrosion mechanism that occurred during cavitation corrosion was based on result of the electrochemical properties 'No cavitation', 'After cavitation', and 'During cavitation' conditions.