• Journal of Surface Science and Engineering
• /
• v.52 no.2
• /
• pp.103-110
• /
• 2019

As an anti-corrosion method in seawater, cathodic protection is widely recognized as the most effective and technically appropriate corrosion prevention methodology for marine structures against harsh corrosive environment. When applying the cathodic protection in seawater, the surface of the metal facilities the formation of compounds of $CaCO_3$ and $Mg(OH)_2$. These mixed compounds are generally called 'calcareous deposits'. This layer functions as a barrier against the corrosive environment and functions to further inhibit the corrosion process and then leading to a decrease in current demand for cathodic protection. However, calcareous deposit films are partially formed on the surface of the cathode and there are some difficulties to maintain both a corrosion resistance for a long period of time and a strong adhesion between deposits and base metal. In this study, the pulse electrodeposition process was applied to improve adhesion and corrosion resistance of the calcareous deposit films, and to solve the problem of hydrogen embrittlement at high current density. The uniform and compact calcareous deposit films were prepared by pulse electrodeposition process, and their properties were characterized using various surface analytical techniques together with electrochemical methods.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.27 no.4
• /
• pp.372-380
• /
• 2005

Condylar process of mandible, has the specialized anatomic structure compared with any other body structure, acts directly in connection with mastication and speech and so on. In general, mandibular condyle fractures have been managed by two methods as open and closed reduction. But, there are no reasonable consensus about the proper management of this injury. This study was designed for analysis of the prognosis of two methods of treatment, open and closed reduction, with positional change of fractured condyle and complications within 6 months post-intermaxillary fixation period. We conducted a retrospective analysis of 154 patients whose unilateral mandibular condyle fractures were treated by open or closed reduction in our department. The horizontal, sagittal, and coronal change of the condyle was examined using modified Towne's and panoramic radiographs before intermaxillary fixation(IMF), immediately after IMF, and at 6 months after IMF. Patients, whose mandibular condyle fractures were treated by closed reduction, had significantly shorter ramus height on the side of injury(P<0.05). But, fractured condylar fragments were displaced insignificantly with aspect to sagittal and coronal plane(P>0.05). The level of the fracture influenced the ramus length and the degree of coronal change in the closed reduction group(P<0.05). There was no significant correlation among the level of the fracture, treatment methods and complications(P>0.05). From the results obtained in this study, fractured mandibular condyles, were treated by closed reduction, had a tendency that continuous condylar displacement was occurred with aspect to horozontal and coronal plane in treatment period including intermaxillary fixation. And then there was a correlation between the level of the fracture and the position change in close reduction group statistically. These result suggested that care must be taken in basing treatment decisions on the degree of displacement of the condyle and in treating the mandibular condyle fractures for a long time.

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1578-1580
• /
• 1999

Silicone rubber is being used for the housing material of outdoor high voltage insulators such as composite insulator, bushing, surge arrestor and cable terminator because of good tracking and erosion resistance, good hydrophobicity and recovery of hydrophobicity, and chemical stability. In this paper, tracking and erosion resistance of silicone rubber having fluids and different ATH contents were examined. Fluids were selected under the consideration of their molecular weight and chemical structure, expecting the high migration rate, the good pollutant encapsulation, and the long period with good hydrophobicity. Good tracking and erosion resistance and arc resistance have been achieved for the silicone rubber above ATH content 130 phr.

• 한국연소학회:학술대회논문집
• /
• 2006.10a
• /
• pp.73-78
• /
• 2006

The lifted oscillating flame has been studied using experiments of inverse diffusion flames that the air jet injected into a methane background. To find out the characteristics of inverse diffusion flames, fundamentally flame stabilized diagram is investigated with various air and fuel jet velocities. It has five regions - flame extinction, stable attached flame, anchored flame, liftoff flame and blow off region. In inverse diffusion flame, lifted flames were observed near the blow off region. As long as flames lift off, flames oscillate by periods. In this oscillating lifted flame region, the frequency of 1 and under were observed in various air and methane jet velocities. Characteristics of lifted flames are also examined by using the ICCD direct image. And intensity of flame chemiluminescence is very different in rising and falling period from photographs. For the present, it is predicted that the changes of flame structure are related with flame oscillation, but more experiments will be needed to make clear the phenomenon.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.277-282
• /
• 2011

Bogie frame is typical safety part of railway vehicle. Total serviceable life of bogie frame will be evaluated by Cumulative Damage Approach Method that is defined by dynamic strain measurement during revenue service under the actual track conditions. As a result of the standardization process developed in British Standard Institution, BS 7608 defines for fatigue design and test method of steel structure by fatigue test results over the long period. This paper evaluates the total serviceable life applying BS 7608 for the bogie frame of Electric Multiple Unit to verify structural safety of the bogie frame.

• The Journal of Korean Physical Therapy
• /
• v.25 no.6
• /
• pp.417-421
• /
• 2013

Purpose: This study was to identify the effect of cervical stabilization exercise on pain and structure in patients with cervical artificial disc replacement. Methods: Forty-four individuals with cervical artificial disc replacement volunteered to participate from FEB 2012 to MAR 2013 in this study. They were allocated to either Experimental Group (EG) or Control Group (CG), with 22 subjects in each group. Subjects from the EG performed cervical stabilization exercise program and subjects from the CG performed isometric exercise program. Assessment tools were made with the Visual Analogue Scale (VAS), Neck Disability Index (NDI), and Cervical Lordosis Angle (CLA). Results: In this study, in within-group and between-group comparison, the EG and CG showed significant differences in all parameters(p<0.05). But EG showed more improvement than CG at all parameters. Conclusion: These findings suggest that cervical stabilization exercise may be favorably used to improve VAS, NDI and CLA in patients with cervical artificial disc replacement. Further studies with larger sample and long-term follow-up period need to generalize the results of this study.

• Journal of Power System Engineering
• /
• v.20 no.4
• /
• pp.5-11
• /
• 2016

This study analyzed the damage to a slitting knife after cutting steel sheets. Damages to the structure were observed and wear tests were conducted. In addition, the degradation on the damaged and undamaged parts was compared with a micro Vickers hardness test. Weibull statistical analysis was carried out in order to evaluate the reliability of the micro Vickers hardness measured data. Spalling of the edge portion occurred by degradation during use over a long period. Rough parts in the specimens were caused by damage because the slitting knife was used for 1 year. The friction coefficient and wear loss at the damaged parts of the knife edge were slightly larger from shock due to repetitive cutting operation. The micro Vickers hardness followed a two-parameter Weibull probability distribution.

• Journal of the Korean Society of Combustion
• /
• v.17 no.3
• /
• pp.46-52
• /
• 2012

3D DNS is performed for n-heptane spray turbulent jet combustion. Diesel-like conditions are considered including single and multiple injections. Conditional statistics are obtained for multiple Lagrangian flame groups of sequentially evaporating fuel. Each fuel group represents the conditional statistics of an independent Lagrangian flame group. Sequentially evaporating fuel goes through different histories and residence times over the ignition delay period. Multiple flame groups are required for accurate description of combustion of a spray jet that goes through a long injection duration or multiple injections.

• Journal of the Korean Professional Engineers Association
• /
• v.16 no.1
• /
• pp.13-19
• /
• 1983

As one of staff members participated in the full course of the plant construction project of On-san Refinery to its successful completion. I had my past expierence that the plant construction project was so complicated, and a Long period required, and thus there were so money problems to be solved. Among the problem, I mainly noticed that the following listed points were solved and improved. 1. Each drawing should be in every accuracy possible. 2. Contract should be specified in every detail possible. 3. All invoiced prices of breack down list should be coped with the current market prices. 4. All execution of work should be in the most accuracy. A. Planing execution of work. B. Coordination with supervisor group. C. Economical method for execution of work. D. Safety control. 3, Calculation work field should be established seperately 6. Each staff members should be work at the best of his pride.

• Wind and Structures
• /
• v.12 no.5
• /
• pp.401-412
• /
• 2009

A method is applied for the estimation of structural damage of tall slender structures using natural frequency and displacements measurements by GPS. The relationship between the variation in the global stiffness matrix (or in the stiffness of each finite element) and the change in the natural frequencies of the structure is given. In engineering practice the number of frequencies which can be derived by GPS measurement of long-period structures will be equal to one, two or three first natural frequencies. This allows us in initial studies to detect damage with frequency changes based on forward methods in which the measured frequencies are compared with the predicted analytical data. This idea, of health monitoring from possible changes to natural frequencies, or from a statement of excessive displacements is applied to the Stuttgart TV Tower.