• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1235-1240
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• 2010

Wire-woven Bulk Kagome (WBK) is fabricated by assembling helically formed wires in six directions. To date, WBK samples have been assembled manually. For industrial application, the assembly process must be automated. Furthermore, if WBK is to be fabricated using flexible wires that cannot maintain their helical shape during fabrication, a specialized automatic machine, i.e., a loom needs to be developed. In this work, we designed and constructed a loom for fabricating WBKs using flexible wires. This loom is operated by one rotation of the upper plate, two translations of the insertion device, and insertion of wires. So-called "comb devices" are placed between multiple layers of Kagome nets to prevent the wires that are already in place from getting entangled with those that are being inserted. This loom can be also used to fabricate semi-WBKs composed of helically formed wires and rigid straight wires.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3080-3086
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• 2009

We have analyzed the output characteristics of a LGP with pyramid shaped pattern by using a 3-D simulation tool. The influences on the LGP output of various parameters such as the pattern shape, pattern occupation ratio, pattern size, and etching angle were investigated. Comparing the pyramid shaped pattern with hemispherical patterns, little difference was observed. And, it was proved that the pattern occupation ratio and etching angle have relatively large effects on LGP output characteristics, while the pattern size has no effect. Therefore, we can improve the LGP characteristics by optimizing pattern structure and distribution.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.305-314
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• 2001

A modified model is proposed for calculation of transitional boundary layer flows. In order to develop the eddy viscosity model for the problem, the flow is divided into three regions; namely, pre-transition region, transition region and fully turbulent region. The pre-transition eddy-viscosity is formulated by extending the mixing length concept. In the transition region, the eddy-viscosity model employs two length scales, i.e., pre-transition length scale and turbulent length scale pertaining to the regions upstream and the downstream, respectively, and a universal model of stream-wise intermittency variation is used as a function bridging the pre-transition region and the fully turbulent region. The proposed model is applied to calculate three benchmark cases of the transitional boundary layer flows with different free-stream turbulent intensity (1%∼6%) under zero-pressure gradient. It was found that the profiles of mean velocity and turbulent intensity, local maximum of velocity fluctuations, their locations as well as the stream-wise variation of integral properties such as skin friction, shape factor and maximum velocity fluctuations are very satisfactorily predicted throughout the flow regions.

• Journal of Digital Convergence
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• v.15 no.2
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• pp.355-360
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• 2017

This study, which was begun in order to create a metal molding by using lines, a basic element of design, examined various characteristics and concept of line and the beauty of lines based on previous research on the subject. The result showed that formative interpretation of lines largely depends on intentional expression by using thickness and rhythm of lines. In order to obtain a metal molding that provides both visual freedom and beauty, rather than the conventional formative expression of lines, I used red copper plate and Phosphor bronze line for creating a pattern based on transformation and repetition of lines and an artwork based on the pattern. The result was not only a creation of a plane but the senses of three-dimension, speed, and unity in the overall shape. Further research will need to be conducted regarding formative interpretation of lines and emotional and intrinsic beauty through expression of lines.

• Parasites, Hosts and Diseases
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• v.22 no.1
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• pp.21-29
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• 1984

A scanning eletron microscopic study was performed to observe the tegumental surface of adult Fibricola seoulensis. The adult worms were collected from the small intestine of mice 5 days to 3 weeks after experimental infection with the metacercariae. The metacercariae were obtained from the viscera of the snakes, Matrix tigrina lateralis, by artificial digestion technique. The results were as follows: 1. The tegument of anterior body was covered with cobblestone-like cytoplasmic processes and that of posterior body showed finger-like processes. The posterior body had 4-5 large transverse wrinklings which formed many discontinued shallow rugae. 2. The entire surface of anterior body was regularly arranged with the spines of which tips diverged into 3 to 4 points. They were densely packed in anterior mid-median portion of dorsal surface where appeared a few spines indented upto 5 points. Farther laterally and posteriorly from this portion, the pointed spines were more sparse and became single tipped and extended to anterior one-third of posterior body, 3. The posterior surface of oral sucker was armed with 50-60 spines having 2-3 tips and ventral sucker also covered with such spines. On anteriormost dorsal surface arranged 60-70 spade-shaped spines. The tribocytic organ was armed with many stout recurved pile-like spines arranged radially. 4. There were 3 types of sensory papillae. The ciliated knob-like (Type I) papillae were almost bilaterally symmetrical in ventral and dorsal surfaces of anterior body, and abundant especially aroundbases of oral and ventral suckers, tribocytic organ, and in lateral margins of anterior body. About 24 non-ciliated round swellings (Type II) were observed around each lip of oral and ventral suckers. The plate-like elevated papilla without cilium (Type III) was found to distribute only in posterior body. These 3 types of papillae seem to be tangoreceptive and/or rheoreceptive in function when their morphology and distributions are considered.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.1 s.12
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• pp.15-24
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• 2004

Generally, a ${\pi}$-type girder composed of two I-type girders is known to have a significant disadvantage in wind resistance design because of aerodynamic instability. A representative bridge for this girder was Tacoma Narrows Bridge. Since Tacoma Narrows Bridge had very low stiffness of the bridge structure and its cross-section shape had aerodynamic instability, the bridge collapsed after severe torsion and vibration events in 19m/s wind speed. Aerodynamic vibration can be avoided by enhancing structural stiffness and damping factor and conducting a study of cross-section shapes. This study shows the angle of attack for the four-span cable stayed bridge having ${\pi}$-type cross-section and describes the aerodynamic characteristics of the changed cross-section with aerodynamic vibration damping additions, by carrying out two-dimension vibration tests. As a result of uniform flow and turbulent flow, the study shows that because the basic ${\pi}$-type cross-section alone can have efficient wind resistant stability, there is no need to have additional aerodynamic damping equipment. Since this four 230m-main-span bridge has a large frequency and also has a big stiffness compared to other bridges containing a similar cross-section, it has aerodynamic stability under the design wind speed.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.309-320
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• 1999

Medial patellar luxation in dogs is one of the most common patellar problems presented to the veterinary practitioner. It is observed in toy and miniature breed and the majority of cases is a congenital form. Because of extensor mechanism's instability, it causes deformity and disorder in the growth of the affected limb when the luxation is left without treatment As lameness is not easily detectable in puppies, early diagnosis and correction are essential for therapy. Up to now, there has not been any reports refering to the diagnostic methods and the optimal age for correction in young dogs. Thirteen 45-90 days old puppies, have grade I and/or II medial patellar luxation. Only by palpation, all 13 dogs were diagnosed of patelar luxation. Skyline radiographic view was useful to interpret patellar morphology and depth of trochlear groove only above 60 days old. However, it was difficult to make definite diagnosis patellar luxation. The caudocranial and lateral radiographic view as well as ultrasonographic skyline view were not showed of patellar luxation. 2 puppies had unilateral patellar luxation and 11 puppies had bilateral patellar luxation which more serious on the left than on the right. Only 3 puppies among 11 puppies with bilateral patellar luxation were observed of lameness degree 1. Regardless of grade of patellar luxation and lameness, we performed trochlear chondroplasty using a U-shape sculpture blade to minimize cartilage injury, transposition of tibia tuberosity with No. 1 Supramid to align extensor mechanism and lateral imbrication. After surgery, we examined the operated animal daily for 10 days and on 15, 30 and 60 days after surgery respectively. After operation, pain and fever became normal on 7 days, swelling on 10 days, respectively. On 10 days after surgery, dogs showed normal standing position, and normal walking was observed in 15 days after surgery. In force plate analysis, the operated legs were normal weight bearing at 30 days after operation. After surgery, not only patellar luxation and clinical signs have been gradually reduced but also bone growth have become normal without showing growth physeal plate injury. The survival rate of puppies over 62 days old was 100%, while 42-45 days old 37.5%. The above results suggest that optimal age for surgical correction of congenital medial patellar luxation is recommended over 60 days old. In conclusion, combination of trochlear chondroplasty, transposition of tibia tuberosity, and lateral retinacular imbrication is appropriate for over 60 days old puppies to efficiently correct patellar luxation.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.45-57
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• 2002

In this paper, the results gained by applying many impingement models to the cylinder and flat plate were analyzed in comparison with the experimental data to study a spray/wall interaction phenomena. To begin with, the behavior of spray injected normal to the wall was analysed using three different impingement models ; Naber and Reitz model(NR model), Watkins and Wang model(WW model) and Park and Watkins model(PW model) in the present calculation. The results obtained from these models were compared with experimental data of Katsura et. al. The results indicated that PW model was in better agreement with experimental data than the NR and WW model. Also f3r spray injected at 30DEG , the result of three models were compared with experimental data of Fujimoto et. al. The results showed that m model overpredicted the penetration in the radial direction because this model was based on the inviscid jet analogy. WW model did not predicted the radius and height of the wall spray effectively. It might be thought that this discrepancy was due to the lack of consideration of spray film velocity occurred at impingement site. The result of PW model agrees with the experimental data as time goes on. In particular, a height of the spray droplets was predicted more closely to the experimental data than the other two models. The results of PW model in which the spray droplets were distributed densely around the edge of droplet distribution shaped in a circle had an agreement with the experimental data of Fujimoto et. al. Therefore, it was concluded that PW model performed better than M and WW model for prediction of spray behavior. The numerical calculation using PW model performed to the cylinder similar to the real shape of DI engine. The results showed that vortex strength near the wall in the cylinder was stronger than that in the case of flat plate. Contrary to the flat plat, an existence of the side wall in the cylinder caused the tangential velocity component to be reduced and the normal velocity component to be increased. The flow tends to rotate to the inside of cylinder going upward to the right side wall of cylinder gradually as time passes. Also, the results showed that as the spray angle increases, the gas velocity distribution and the tumble flow seemed to be formed widely.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.109-116
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• 2008

This study was performed to get information of self-healing mechanism in cement system and the influence of waterproofing admixtures for concrete on self-healing property. For testing, cement paste specimens cured for 7, 14 and 28 days were prepared and crushed into plate-shape pieces. Screened specimens with thickness not more than 1mm were covered with wet rags and cured in a plastic container for 7 and 28 days. After stopping hydration process of the specimens by treatment with acetone, the surfaces of specimens have been contacted with wet rags were analyzed by XRD, DSC, SEM and EDX. The analysis results showed that cement paste has self-healing property and this property is mainly affected by water. Self-healing in cement system is more effective and faster at an early stage of hydration as there is enough content of unreacted cement to make an additional hydration in this period. The results of this study also showed that waterproofing admixtures for concrete have a considerable effect on self-healing of cement pastes; i.e., they improved self-healing effect of cement and, especially, the specimen using admixture C has shown a lot of needle-like or fibrous hydration products which are estimated as ettringite. It is supposed that these ettringite products are effective to enhance self-healing in cement system.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.3
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• pp.307-326
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• 2004

Statement of problem. The long-term success of implants is the development of a stable direct connection between bone and implant surface, which must be structural and functional. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. Among them, altering the surface properties can modify cellular responses such as cell adhesion, cell motility and bone deposition. Purpose. This study was to evaluate the cellular behaviors on the surface-modified titanium by morphological observation, cellular proliferation and differentiation. Material and methods. Specimens were divided into five groups, depending on their surface treatment: electropolishing(EP) anoclizing(AN), machining(MA), blasting with hydroxyapatite particle(RBM) and electrical discharge machining(EDM). Physicochemical properties and microstructures of the specimens were examined and the responses of osteoblast-like cells were investigated. The microtopography of specimens was observed by scanning electron microscopy(SEM). Surface roughness was measured by a three-dimensional roughness measuring system. The microstructure was analyzed by X-ray diffractometer(XRD) and scanning auger electron microscopy(AES). To evaluate cellular responses to modified titanium surfaces, osteoblasts isolated from neonatal rat were cultured. The cellular morphology and total protein amounts of osteoblast-like cell were taken as the marker for cellular proliferation, while the expression of alkaline phosphatase was used as the early differentiation marker for osteoblast. In addition, the type I collagen production was determined to be a reliable indicator of bone matrix synthesis. Results. 1. Each prepared specimen showed specific microtopography at SEM examination. The RBM group had a rough and irregular pattern with reticulated appearance. The EDM-treated surface had evident cracks and was heterogeneous consisting of broad sheet or plate with smooth edges and clusters of small grains, deep pores or craters. 2. Surface roughness values were, from the lowest to the highest, electropolished group, anodized group, machined group, RBM group and EDM group. 3. All groups showed amorphous structures. Especially anodized group was found to have increased surface oxide thickness and EDM group had titaniumcarbide(TiC) structure. 4. Cells on electropolished, anodized and machined surfaces developed flattened cell shape and cells on RBM appeared spherical and EDM showed both. After 14 days, the cells cultured from all groups were formed to be confluent and exhibited multilayer proliferation, often overlapped or stratified. 5. Total protein amounts were formed to be quite similar among all the group at 48 hours. At 14 days, the electropolished group and the anodized group induced more total protein amount than the RBM group(P<.05). 6. There was no significant difference among five groups for alkaline phosphatase(ALP) activity at 48 hours. The AN group showed significantly higher ALP activity than any other groups at 14 days(P<.05). 7. All the groups showed similar collagen synthesis except the EDM group. The amount of collagen on the electropolished and anodized surfaces were higher than that on the EDM surface(P<.05).