• Ocean and Polar Research
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• v.25 no.4
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• pp.427-435
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• 2003

Growth and pigment responses to different levels of solar radiation with or without ultraviolet (UV)-B component $({\lambda}=280-315nm)$ were investigated in Antarctic rhodophytes, Kallymenia antarctica and Palmaria decipiens, collected around King George Island during the summer of 2000. In K. antarctica specific growth rate, based on thallus area or fresh weight, decreased with increasing solar irradiances while P. decipiens were relatively insensitive to the effects of light. It is noticeable that the presence or absence of UV-B had no significant effect on growth for either species. However, K. antarctica showed a more pronounced reduction in chlorophyll (Chl a) concentrations at higher irradiances in the presence of UV-B. In P. decipiens, Chl a concentrations did not differ despite radiation level fluctuations being lower albeit than initial measurements. Thallus thickness was greater in K. antarctica than in P. decipiens. There were higher relative amounts of UV-absorbing pigments (UVAPs) in P. decipiens than in K, antarctica. The single absorbance peak obtained from the methanol extracts was resolved into three (316,332 and 346nm) in K. antarctica and four peaks (315,326,333 and 349 nm) in Palmaria as a result of the fourth-derivative. After 7 days exposure to solar radiation, the amount of UVAPs in K. antarctica was significantly reduced to a similar degree at all light levels, whereas that of P. decipiens remained unchanged except at 5% of surface irradiance. High performance liquid chromatography (HPLC) analysis of purified extracts indicated that P. decipiens possesses porphyra-334 in addition to three other mycosporine-like anlino acids (MAAs; asterina-330, palythine, shinorine), which are commonly present in K. antarctica. Significantly lower tolerance of K. antarctica to high levels of solar radiation may be connected with its usual absence in the eulittoral, while the active growth and elastic pigment responses of P. decipiens over a wide range of solar irradiance levels up to full sunlight seems to correspond well with its wide vertical distribution from rock pools down to 25-30m.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.217-226
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• 2007

Purpose: Distraction osteogenesis is considered to take favorable effect on the TMJ and be beneficial to prevent the relapse after the mandibular advancement of Class II malocclusion patient. This is the report with literature review on the mandibular advancement in the patients showing preoperative condylar resorption and who need larger amount of advancement. Patients and method: Distraction osteogenesis using intraoral device was performed for three mandibular hypoplasia patients (one male and two females). All patients were adult over 18 years old. The patients showed condylar bony resorption preoperatively. The distraction was performed intraorally with modified SSRO. After 7 days of latency period, activation was performed at the rate of 1.0 mm/day with twice turn. The devices were removed after 4-8 month consolidation period. Results: Total advancement of mandible was average 13 mm. One patient showed openbite immediately after removal of distraction device. It took long time to guide the openbite with elastics. The comparison between cephalometries immediately after device removal and postoperative six month revealed average 3.4 mm relapse. This means that mandibular advancement with distraction osteogenesis needs overcorrection and elastic rehabilitation even after enough consolidation periods. Conclusion: Larger amount of mandibular advancement could be achieved with distraction osteogenesis in severe mandibular hypoplasia with condylar resorption. However, some relapse was found during the follow-up period and the over correction is considered to be needed. The effect of distraction osteogenesis seems to be investigated with long-term follow-up.

• Parasites, Hosts and Diseases
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• v.36 no.2
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• pp.91-98
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• 1998

The present study was performed to observe characteristics of the lifE history of Echinoparvphium recunpatum under both natural and laboratory conditions in Korea. A batch of Rcnix aunculnria corecna was collected from Sunamchon, one of the stream of West Naktonggang (River), in Kangso-gu, Pusan during August and September 1992. Out of 106 snails examined by crushing,52 (49.0%) were infected with larval E. recurvaum i.e. rediae, cercariae and metacercariae. Cercariae naturally shed from snails encysted in the snails of same species and loaches, but not in mud-snails. Adult worms were detected from chicks and ducks experimentally infected with metacercariae, but not from rats and mice. The average recovery rate of adults from chicks was 13.1%. Rediae were sac-like, $2.437{\;}{\times}{\;}0.317{\;}mm$ in average size, with a muscular pharynx and a brownish cecum which reached the anterior half of the body. Cercariae consisted of a spindle-shaped body ($0.262{\;}{\times}{\;}0.129{\;}mm$ in average) and a rod-like tail ($0.528{\;}{\times}{\;}0.056{\;}mm$ in average). In the cercarial body, 45 collar spines were observed on the head crown, and double rows of excretory ducts with fine granules were laterally arranged between the pharynnx and the ventral sucker. Metacercariae were spherical, $0.144{\;}{\times}{\;}0.142{\;}mm in average size, with thick hyaline outer and thin elastic inner walls, and many excretory granules. Adults were slender and more attenuated in the anterior end, $0.2760{\;}{\times}{\;}0.550{\;}mm$ in average size, and had 45 collar spines including four end group spines on both ventral corners. From the above results, it was confirmed that R. auriculnna corennc plays a pivotal role in the life cycle of 5. recuwatum as the first and/or second intermediate hosts in Korea.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.135-140
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• 1995

Changes in pH of the soaking solution and physical properties of the soybean curd during immersing in solution of different concentrations at different temperatures were determined. Compared with $0{\sim}3%$ NaCl soaking solution, 5% NaCl soaking solution distinctively reduced the pH drop, increasing rate of turbidity and microorganism growth during storage. This indicated the concentration of soaking solution influences the shelf life of curd. As the storage temperature was lowered to $5^{\circ}C$, their changing rates were also reduced. Physical properties such as initial stress $({\sigma}_0)$, elastic constant (E), viscous constant $({\eta})$ and failure test were influenced by storage temperature, but not a function of concentration of salt solution. The result of the sensory test indicated the hardness and salty taste of curd were statistically significant among samples and $1{\sim}5%$ NaCl solutions did not show any significant difference in the salty taste.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.129-136
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• 2018

The estimation of the fatigue design life for large welded structures is usually performed using the liner cumulative damage method such as Palmgren-Miner rule or the equivalent damage method. When a fatigue crack is detected in a welded steel structure, the residual service life has to be estimated base on S-N curve method and liner elastic fracture mechanics. In this study, to examine the 3D fatigue crack behavior and estimate the fatigue life of out-of-plane gusset fillet welded joint, the fatigue tests were carried out on the model specimens. Investigations of three-dimensional fatigue crack propagation on gusset welded joint was used the finite element analysis of FEMAP with NX NASTRAN and FRANC3D. Fatigue crack growth analysis was carried out to demonstrate the effects of aspect ratio, initial crack length and stress ratio on out-of-plane gusset welded joints. In addition, the crack behaviors of fatigue tests were compared with those of the 3D crack propagation analysis in terms of changes in crack length and aspect ratio. From this analysis result, SIFs behaviors and crack propagation rate of gusset welded joint were shown to be similar fatigue test results and the fatigue life can also be predicted.

• Elastomers and Composites
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• v.43 no.2
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• pp.88-103
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• 2008

This study was purposed to investigate the effects of surfactants and fillers on physical properties of hydrophilic polyvinylsiloxane dental impression materials (PVS). Incorporation of surfactants enhanced the hydrophilicity of the PVS, however, it induced increased viscosity and permanent deformation ratio, delayed setting, and decreased tensile strength. At high concentrations of surfactant, the tensile strength was observed to decrease significantly due to the internal pore formation. Especially, the hydrophilicity of the PVS was significantly enhanced with the addition of Silwet L-77. However, the viscosity, strain in compression, pore formation, and setting time increased whereas the elastic recovery rate and strength remarkably decreased. The PVS dental materials containing Span 20 showed the lowest degree of viscosity increase, delayed setting, pore formation, and hydrophilicity. The delayed setting, pore formation, and strength decrease caused by the incorporation of surfactant were improved by substituting the crystalline quartz filler with diatomaceous earth while the contact angle of PVS dental materials increased.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.143-150
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• 1996

This is an explicit-Implicit, finite element analysis for linear as well as nonlinear hygrothermal stress problems. Additional features, such as moisture diffusion equation, crack element and virtual crack extension(VCE ) method for evaluating J-integral are implemented in this program. The Linear Elastic Fracture Mechanics(LEFM) Theory is employed to estimate the crack driving force under the transient condition for and existing crack. Pores in materials are assumed to be saturated with moisture in the liquid form at the room temperature, which may vaporize as the temperature increases. The vaporization effects on the crack driving force are also studied. The Ideal gas equation is employed to estimate the thermodynamic pressure due to vaporization at each time step after solving basic nodal values. A set of field equations governing the time dependent response of porous media are derived from balance laws based on the mixture theory Darcy's law Is assumed for the fluid flow through the porous media. Perzyna's viscoplastic model incorporating the Von-Mises yield criterion are implemented. The Green-Naghdi stress rate is used for the invariant of stress tensor under superposed rigid body motion. Isotropic elements are used for the spatial discretization and an iterative scheme based on the full newton-Raphson method is used for solving the nonlinear governing equations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.28-36
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• 2022

As port structures are exposed to various extreme external loads such as wind (typhoons), sea waves, or collision with ships; it is important to evaluate the structural safety periodically. To monitor the port structure, especially the rubber fender, a fender segmentation system using a vision sensor and deep learning method has been proposed in this study. For fender segmentation, a new deep learning network that improves the encoder-decoder framework with the receptive field block convolution module inspired by the eccentric function of the human visual system into the DenseNet format has been proposed. In order to train the network, various fender images such as BP, V, cell, cylindrical, and tire-types have been collected, and the images are augmented by applying four augmentation methods such as elastic distortion, horizontal flip, color jitter, and affine transforms. The proposed algorithm has been trained and verified with the collected various types of fender images, and the performance results showed that the system precisely segmented in real time with high IoU rate (84%) and F1 score (90%) in comparison with the conventional segmentation model, VGG16 with U-net. The trained network has been applied to the real images taken at one port in Republic of Korea, and found that the fenders are segmented with high accuracy even with a small dataset.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.494-507
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• 2021

With the increasing use of TBM, research has recently been conducted in Korea to analyze TBM data with machine learning techniques to predict the ground in front of TBM, predict the exchange cycle of disk cutters, and predict the advance rate of TBM. In this study, classification prediction of rock characteristics of slurry shield TBM sites was made by combining traditional rock classification techniques and machine learning techniques widely used in various fields with machine data during TBM excavation. The items of rock characteristic classification criteria were set as RQD, uniaxial compression strength, and elastic wave speed, and the rock conditions for each item were classified into three classes: class 0 (good), 1 (normal), and 2 (poor), and machine learning was performed on six class algorithms. As a result, the ensemble model showed good performance, and the LigthtGBM model, which showed excellent results in learning speed as well as learning performance, was found to be optimal in the target site ground. Using the classification model for the three rock characteristics set in this study, it is believed that it will be possible to provide rock conditions for sections where ground information is not provided, which will help during excavation work.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.238-246
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• 2022

This paper summarizes the development and evaluation of the reinforcement details of CFRP plates to improve the bending performance of wooden beams. In this study, the reinforcing technology using high-strength bolts for the end of beam were developed as reinforcement details for reinforcing wooden beams with CFRP plates by EBM method. In order to evaluate the bending performance, a bending test was conducted for the specimens with details of reinforcement such as the EBM method and the NSM method. From the experimental results, the EBM specimens without end restraints had both the CFRP plate attachment failure and the splitting failure of the wood. In the load-displacement curve, the non-reinforced specimens exhibited linear elastic behavior and then brittle fracture after the maximum load. The maximum load of the specimens reinforced by the EBM method increased by 31.5~63.0% compared to the non-reinforced specimens, and the maximum load according to the end restraints of the high-strength bolts increased by 24.0%. Based on the reinforcement amount of the same CFRP plate, EBM reinforcement was 2.67 times larger in maximum load increase rate than NSM reinforcement.