• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.127-134
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• 2009

This study investigated their properties of spalling resistance and residual compressive strength after fire test corresponding to various ISO, RABT heating curves, and contents of hybrid organic fiber of high strength concrete. The results were summarized as following. As fundamental characters of concrete with hybrid organic fiber, the flowability was directly declined as the increase of fiber contents, and air contents were decreased or increased a little bit, but there was not big difference. The compressive strength was gradually declined sluggishly at 28 days. As properties of fire resistance, in case of RABT heating curves, compare with ISO heating curves a spalling aspect showed till range that has much contents of hybrid organic fiber, but they are mostly peeling spalling, which means spalling aspect didn't happen to inside. In conclusion, in case of W/B 25% high strength concrete, the spalling was prevented over 0.04% of contents of fiber at ISO heating curve and over 0.10% of contents of fiber at the RABT heating curve. In case of spalling was prevented, mass reduction rate according to the change of heating temperature curves showed around 7% at ISO heating curves and around 9% at RABT heating curves. The residual compressive strength rate corresponding to the change of heating temperature curves showed 50%~60% at ISO heating temperature curves and 30%~35% at RABT heating temperature curves in case of spalling was prevented.

• Archives of Plastic Surgery
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• v.34 no.5
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• pp.599-604
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• 2007

Purpose: Blowout fractures of the orbit are common sequelae to blunt facial trauma and now increasing in number due to automobile accidents, violence and industrial disasters. There are some reports of diagnosis and treatment of this fracture, but detailed data provided in overall aspects are very few. We analysed extensive data to provide guide line of blowout fracture patients care. Methods: We retrospectively studied 387 orbital blowout fracture patients who had been followed up at least 3-6 months. Their hospital records were reviewed according to causes, fracture site, operation methods, and follow up results, etc. Results: The ratio of males to females was 7 : 3 and fractures were most often seen in the 20-29 age group. 180(47%) patients had medial orbital wall fractures, 155(40%) patients had floor fractures and 52(13%) patients had a combination of orbital floor and medial wall fractures. The highest associated bone fracture was the nasal bone(37%). The open reduction was done in the 324 patients(83.7%) and insertion materials were used in the 249 patients(77%). Total 45 patients(14%) complained of residual diplopia and 26 patients(8%) kept mild enophthalmos. 24 patients(7%) showed some restriction of extraocular muscle movements. Conclusion: We broadly surveyed the information of blow out fracture patients and believe that this study provides important prognostic information that can be of benefit to both patient and surgeon during preoperative counseling and postoperative analysis of orbital blowout fractures.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.459-465
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• 2014

In this study, Si-SiC composites were fabricated using a Si melt infiltration method using ${\beta}$-SiC/C composite powders synthesized by the carbothermal reduction of $SiO_2-C$ precursors made from a TEOS and a phenol resin. The purity of the synthesized SiC-C composite powders was higher than 99.9993 wt% and the average particle size varied from 4 to $6{\mu}m$ with increasing carbon contents of the $SiO_2-C$ precursors. It was found that the Si-SiC composites fabricated in this study consist of ${\beta}$-SiC and residual Si, without any trace of ${\alpha}$-SiC. The 3-point bending strengths of the fabricated Si-SiC composites were measured and found to be higher than 550 MPa, although the density of the fabricated Si-SiC composite was less than $2.9g/cm^3$. The bending strengths and the densities of the fabricated Si-SiC composites were found to decrease with increasing C/Si mole ratios in the SiC-C composite powders. The specific resistivities of the Si-SiC composites fabricated using the SiC-C composite powders were less than $0.018{\Omega}cm$. With increasing C content in the SiC-C composite powders used for the fabrication of Si-SiC composites, the specific resistivity of the Si-SiC composites was found to slightly increase from 0.0157 to $0.018{\Omega}cm$.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.5 s.51
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• pp.25-33
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• 2006

This paper provides a method to predict the ductile capacity of reinforced concrete beam-column joints that fail in shear after the plastic hinges occur at both ends of the adjacent beams. After the plastic hinges occur at both ends of the beams, the longitudinal axial strain at the center of the beam section in the plastic hinge region abruptly increases because the neutral axis continues to move upward toward the extreme compressive fiber and the residual strain of the longitudinal bars continues to increase with each cycle of inelastic loading. An increase in the axial strain of the beam section after flexural yielding widens the cracks in the beam-column joints, thus leading to an decrease of the shear strength of the beam-column joints. The proposed method takes into account shear strength deterioration in the beam-column joints. In order to verify the shear strength and the corresponding ductility of the proposed method, test results of 52 RC beam-column assembles were compared. Comparisons between the observed and calculated shear strengths and their corresponding ductilities of the tested assembles, showed reasonable agreement.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.598-607
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• 2004

In this study, the effects of two pre-treatment processes were observed prior to membrane filtration: pre-coagulation and pre-ozonation. To compare the effect of two above-mentioned pre-treatments, we adopted the four schemes: first one is direct membrane filtration of river surface water, second one is membrane filtration after pre-coagulation, third one is membrane filtration after pre-ozonation and fourth one is membrane filtration after pre-coagulation and pre-ozonation. There are two exceptional characteristics in applied processes. One is the usage of the MF membrane which has high ozone resisting characteristic. Therefore, ozone resides in membrane module during filtration. The other is adoption of Jet Mixed Separator (JMS) as coagulation-sedimentation process. The change in transmembrane pressure and permeate water quality were also examined. As a result, considering the filtration performance efficiency and permeate water quality, the process composed of filtration with combination of both pre-coagulation and pre-ozonation was proved most effective. The improved efficiency was due to the reduction of loading rate of fouling inducing materials to membrane module by coagulation process as well as variable reactions, such as degradation, particle destabilization and coagulation, occurred by residual ozone in membrane module. The additional effect of pre-coagulation before pre-ozonation is suppression of AOC, one of the by-products induced by ozonation. Therefore, combination of pre-coagulation and pre-ozonation is the effective process to overcome the major de-merit of ozonation i.e. by-products formation.

• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.241-247
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• 2016

The tracking filter plays a key role in the accurate estimation and prediction of maneuvering a vessel's position and velocity when attempting to enhance safety by avoiding collision. Therefore, in order to achieve accurate estimation and prediction, many oceangoing vessels are equipped with the Automatic Radar Plotting Aid (ARPA) system. However, the accuracy of prediction depends on the tracking filter's ability to reduce noise and maintain a stable transient response. The purpose of this paper is to derive the optimal values of the gain parameters used in tracking a High Dynamic Warship. The algorithm employs a ${\alpha}-{\beta}-{\gamma}$ filter to provide accurate estimates and updates of the state variables, that is, positions, velocity and acceleration of the high dynamic warship based on previously observed values. In this study, the filtering coefficients ${\alpha}$, ${\beta}$ and ${\gamma}$ are determined from set values of the damping parameter, ${\xi}$. Optimization of the damping parameter, ${\xi}$, is achieved experimentally by plotting the residual error against different values of the damping parameter to determine the least value of the damping parameter that results in the optimum smoothing coefficients leading to a reduction in the noise corruption effect. Further investigation of the performance of the filter indicates that optimal smoothing coefficients depend on the initial and average velocity of the target.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.57-60
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• 2003

Electro-Optical (EO) performances for the ion beam (IB) aligned twisted-nematic (TN)-liquid crystal display (LCD) with ion beam exposure on the new of diamond like carbon (DLC) thin film surface were investigated. Voltage-transmittance (V-T) curve and response time without backflow bounce in the ion beam aligned TN-LCD with ion beam exposure for 0.5 and 1min on the DLC thin film was observed. Also. the fast response time of ion beam aligned TN-LCD with ion beam exposure for 1min on the DLC thin film surface can be achieved. The residual DC voltage of the ion beam aligned TN-LCD on the DLC thin film surface was almost the same as that of the rubbing aligned TN-LCD on the polyimide(PI) surface.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.635-641
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• 2010

Time-varying channel characteristics in OFDM systems over doubly selective channels cause inter-carrier interferences(ICI) in the frequency domain. Time domain windowing gives rise to restriction on the bandwidth of the frequency domain channel matrix and makes it possible to approximate the OFDM system as a simplified linear input-output model. When successive interference cancellation based on linear MMSE estimation is employed for channel equalization in OFDM systems, symbol detection ordering produces considerable effects on overall system performances. In this paper, we show the reduction of the residual ICI by time domain windowing and the resultant performance improvements, and investigate the effects of SINR- and CSEP-based symbol detection ordering on the performance of successive interference cancellation.

• Journal of Energy Engineering
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• v.11 no.1
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• pp.18-25
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• 2002

One of the most serious concern in nuclear power plant piping maintenance is thickness reduction due to flow-accelerated corrosion (FAC). Since the FAC occurs under specific conditions of pH, dissolved oxygen, temperature, flow velocity, steam quality of the fluid and materials and geometry of the piping, a systematic approach is required for managing the FAC problem. In this study, construction of a secondary piping database, analyzing the FAC rate using the database and predicting the residual life was performed for a domestic CANDU nuclear power plant. Also FAC mechanism and factors affecting FAC were reviewed. By showing a case study on analysis for a pipe line between a separator and a flash tank, a procedure for managing FAC problem is suggested. The procedure proposed in this paper can be widely applied to the secondary piping of other domestic nuclear polder plants.

• Economic and Environmental Geology
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• v.37 no.4
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• pp.383-389
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• 2004

Understanding flow pattern of water and solute in subsurface is essential for the reduction and prevention of contamination of soil and groundwater and for the investigation and remediation of contaminated site. The objective of this study is to examine the infiltration pattern in a soil developed from the Jurassic granite using (Brilliant Blue FCF $C_{37}H_{34}N_{2}Na_{2}O_{9}S_{3}$), the nonfluorescent and nontoxic food dye. All image processing was conducted using geographic image processing software, ER Mapper, Version 6.2. The dye coverage was determined by counting the stained pixels in the photographs (80${\times}$80cm, 80TEX>${\times}$5cm) for the vertical and horizontal view. A homogeneous matrix flow occurred in the A horizon with weak, medium granular structure and fingering at the interface of finer-textured A horizon and coarser-textured C horizon. Pegmatitic vein originated from the granite and plant root in C horizon induced preferential flow.