• Archives of Plastic Surgery
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• v.45 no.4
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• pp.357-362
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• 2018

Background The most common complication after tendon repair is the development of adhesion, with subsequent rupture. Methods In this study, we present a new method in which the tendon healing contact surface is increased to reduce these complications. The tendons of chickens in groups 1, 3, and 5 were transversely cut and repaired with in the traditional fashion with double-modified Kessler method and 5/0 polypropylene. In the other groups, 3 mm of the tendon was removed from the proximal half of the upper end and from the distal half of the lower end of the tendon, and they were repaired with the modified Kessler method. The tendons of the chickens in groups 1 and 2 were evaluated immediatelly after surgery. Groups 3 and 4 were evaluated at 4 weeks after surgery. Groups 5 and 6 were evaluated at 6 weeks. Results Increases in transient inflammation and connective tissue formation were observed more clearly in the group treated with the new method in histopathological investigations at weeks 4 and 6. The stretching test showed statistically significant differences between groups 3 and 4 (P<0.05) and groups 5 and 6 (P<0.05). Conclusions When repairing tendons with the new method, the healing surface increases and the direction of collagen fibers at the surface changes. Because of these effects, the strength of the tendon healing line increases; we therefore expect that this technique will enable patients to safely engage in early active exercise after the operation, with less risk of tendon rupture.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.281-284
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• 2007

Recently, we have developed p-i-n a-Si:H single junction thin film solar cells with RF (13.56MHz) plasma enhanced chemical vapor deposition (PECVD) system, and also successfully fabricated the mini modules ($>300cm^2$), using the laser patterning technique to form an integrated series connection. The efficiency of a mini module was 7.4% ($Area=305cm^2$, Isc=0.25A, Voc=14.74V, FF=62%). To fabricate large area modules, it is important to optimise the integrated series connection, without damaging the cell. We have newly installed the laser patterning equipment that consists of two different lasers, $SHG-YVO_4$ (${\lambda}=0.532{\mu}m$) and YAG (${\lambda}=1.064{\mu}m$). The mini-modules are formed through several scribed lines such as pattern-l (front TCO), pattern-2 (PV layers) and pattern-3 (BR/back contact). However, in the case of pattern-3, a high-energy part of laser shot damaged the textured surface of the front TCO, so that the resistance between the each cells decreases due to an incomplete isolation. In this study, the re-deposition of SnOx from the front TCO, Zn (BR layer) and Al (back contact) on the sidewalls of pattern-3 scribed lines was observed. Moreover, re-crystallization of a-Si:H layers due to thermal damage by laser patterning was evaluated. These cause an increase of a leakage current, result in a low efficiency of module. To optimize a-Si:H single junction thin film modules, a laser beam profile was changed, and its effect on isolation of scribed lines is discussed in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.911-916
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• 2012

It is important to identify dynamic characteristics of nuclear fuel components. Since the fuel always exposed to turbulent flow, the dynamic contact between grids and rods is one of the fuel failure modes. The dynamic behavior of grids in nuclear fuels is quite complex, since two pairs of spring support are placed in the limited space. The strap in a cell has single spring and double dimples and this paper focuses on investigation of the grid strap(Test Fuel Strap, TFS) vibration in one cell. To identify the grid strap vibration, modal analysis of the strap is performed using Finite Element Method (FEM). Modal testing on a $5{\times}5$ grid structure without rods is performed. The modal testing results are compared to analytic results. In addition, random test considering rod effect is performed about a $5{\times}5$ grid with rods under real contact condition in the air. Finally, the strap vibration of a $5{\times}5$ fuel bundle in INvestigation of Flow INduced vIbraTion(INFINIT) facility is measured in real fluid velocity condition without heating. It is shown that modal frequencies from the test are almost equal to those peak frequencies in the INFINIT test.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.39-45
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• 1999

Refining in papermaking plays an important role in changing fiber properties as well as paper properties. The major effects of refining on pulp fibers are internal and external fibrillation, fiber shortening, and fines formation. Many workers showed that internal fibrillation of the primary refining effects was most influential in improving paper properties. In particular, refining produces separation of fiber walls into several lamellae, thus causing fiber wall swelling with water penetration. This leads to the increase of fiber flexibility and of fiber-to-fiber contact during drying. If the fibers are very flexible, they will be drawn into close contact with each other by the force of surface tension as the water is removed during the drainage process and drying stages. In order to study the effect of fiber wall delamination on paper properties, cross-sectional image of fibers in a natural condition had to be generated without distortion. Finally, it was well recognized that confocal laser scanning microscope (CLSM) could be one of the most efficient tool for creating and quantifying fiber wall delamination in combination with image analysis technique. In this study, the CLSM could be used not only to observe morphological features of transverse views of swollen fibers refined under low and high intensity, but also to investigate the sequence of fiber wall delamination and fiber wall breakage. From the CLSM images, increasing the specific energy or refining decreased the degree of fiber collapse, fiber cross-sectional area, fiber wall thickness and lumen area. High intensity refining produced more external fibrillation.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.9-15
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• 2000

Flip chip assembly on organic substrates using ACAs have received much attentions due to many advantages such as easier processing, good electrical performance, lower cost, and low temperature processing compatible with organic substrates. ACAs are generally composed of epoxy polymer resin and small amount of conductive fillers (less than 10 wt. %). As a result, ACAs have almost the same CTE values as an epoxy material itself which are higher than conventional underfill materials which contains lots of fillers. Therefore, it is necessary to lower the CTE value of ACAs to obtain more reliable flip chip assembly on organic substrates using ACAs. To modify the ACA composite materials with some amount of conductive fillers, non-conductive fillers were incorporated into ACAs. In this paper, we investigated the effect of fillers on the thermo-mechanical properties of modified ACA composite materials and the reliability of flip chip assembly on organic substrates using modified ACA composite materials. For the characterization of modified ACAs composites with different content of non-conducting fillers, dynamic scanning calorimeter (DSC), and thermo-gravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), and thermo-mechanical analyzer (TMA) were utilized. As the non-conducting filler content increased, CTE values decreased and storage modulus at room temperature increased. In addition, the increase in tile content of filler brought about the increase of Tg$^{DSC}$ and Tg$^{TMA}$. However, the TGA behaviors stayed almost the same. Contact resistance changes were measured during reliability tests such as thermal cycling, high humidity and temperature, and high temperature at dry condition. It was observed that reliability results were significant affected by CTEs of ACA materials especially at the thermal cycling test. Results showed that flip chip assembly using modified ACA composites with lower CTEs and higher modulus by loading non-conducting fillers exhibited better contact resistance behavior than conventional ACAs without non-conducting fillers.ers.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.1
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• pp.41-49
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• 2000

Flip chip assembly on organic substrates using ACAs have received much attentions due to many advantages such as easier processing, good electrical performance, lower cost, and low temperature processing compatible with organic substrates. ACAs are generally composed of epoxy polymer resin and small amount of conductive fillers (less than 10 wt.%). As a result, ACAs have almost the same CTE values as an epoxy material itself which are higher than conventional underfill materials which contains lots of fillers. Therefore, it is necessary to lower the CTE value of ACAs to obtain more reliable flip chip assembly on organic substrates using ACAs. To modify the ACA composite materials with some amount of conductive fillers, non-conductive fillers were incorporated into ACAs. In this paper, we investigated the effect of fillers on the thermo-mechanical properties of modified ACA composite materials and the reliability of flip chip assembly on organic substrates using modified ACA composite materials. For the characterization of modified ACAs composites with different content of non-conducting fillers, dynamic scanning calorimeter (DSC), and thermo-gravimetric analyser (TGA), dynamic mechanical analyzer (DMA), and thermo-mechanical analyzer (TMA) were utilized. As the non-conducting filler content increased, CTE values decreased and storage modulus at room temperature increased. In addition, the increase in the content of filler brought about the increase of $Tg^{DSC}$ and $Tg^{TMA}$. However, the TGA behaviors stayed almost the same. Contact resistance changes were measured during reliability tests such as thermal cycling, high humidity and temperature, and high temperature at dry condition. It was observed that reliability results were significantly affected by CTEs of ACA materials especially at the thermal cycling test. Results showed that flip chip assembly using modified ACA composites with lower CTEs and higher modulus by loading non-conducting fillers exhibited better contact resistance behavior than conventional ACAs without non-conducting fillers.

• Journal of the Korean Society of Safety
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• v.31 no.1
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• pp.13-18
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• 2016

KTX wheelset bearings have thus far been maintained in accordance with the maintenance system of French national railway company, SNCF. The overhaul cycle time (OCT) of KTX wheelset bearings is now 1.4 million km in mileage. This value, however, has not been validated in Korea that has much different railway environments with France. In fact, it is impossible to validate OCT of wheelset bearings directly because they are disassembled and cleaned only when some faults are detected. In this paper, the accuracy of the current OCT value was evaluated indirectly by investigating the effect of grease lubricants on the bearing life. Five grease samples (one new and four aged greases) were used in this study. Four aged greases of different conditions were obtained from four wheelset bearings whose mileages were about 0.3, 1.2, 1.3, and 1.8 million km, respectively. Each grease sample was then injected into the RCF (Rolling Contact Fatigue) tester and fatigue lifetime was experimentally estimated. In addition, the wt% of Fe in each grease sample was analysed. The experiment results reveal that the bearing lifetime is inversely proportional to the mileage of grease sample while the wt% of Fe increases with the mileage of grease sample. Based on the experimental results, it can be concluded that the current OCT value is appropriate for the first overhaul of wheelset bearings. However, further validation is required to determine the second and third OCT values.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.7
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• pp.695-701
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• 2013

The suppression of a thermocapillary flow (Marangoni flow) by a nonionic surfactant is experimentally investigated for evaporating pure water droplets on hydrophobic substrates. The experiment shows that as the initial concentration of the surfactant increases, the velocity and lifetime of the flow monotonically decrease. The result confirms the no-slip boundary condition at a liquid-air interface, which is explained on the basis of the previous model regarding the effect of surfactants on the no-slip condition. Interestingly, at an initial concentration much less than a critical value, it is found that depinning of the contact line occurs during the early stage of evaporation, which is ascribed to a reduction in the contact angle hysteresis owing to the presence of the Marangoni flow.

• Journal of Nutrition and Health
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• v.22 no.2
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• pp.84-90
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• 1989

Allergic disorders may be defined as the abnormal reactions to proteins. Cow milk is the first foreign protein which the human being would contact postnatally. Serveral studies suggested that this contact had certain effects on the development o allergic disorders with great controlversies. Seven hundred seventy eight students from middle class in Seoul, aged 6 to 17 wears, were surveyed to delineate the relationshpis between the cow's milk contacts in infancy and the subsequent development of allergic disorders in Koran population. Questionaire were included the nursing patterns in infancy, the past medical history of asthma or wheezy bronchitis and the presence of infantile eczema. Skin tests to three common resporatory allergens in Korea(house dust, house dust mite; D. farinae, D. ptoeronssinus) were performed. The positivity was determined by the wheal size larger than that to histamine. 70.2% of whole mateials was fed by breast milk, 13.1% by cow's milk and 16.7% by mixed nutsing. From the obsevation of nursing patterns by (table 2), we find that the number of breast milk group has been decreasing in 1970's. 10.1% of breast milk group(BMG) had wheezy bronchitis, 8.8% of cow's milk group(CMG) and 11.5% of mixed nursing group(MNG). Infantile eczema history was positive in 27.8% of BMG, in 26.5% of CMG and in 29% of MNG. Skin test positivity was 23.8% in BMG, 25.5% in CMG and 26.2% in MNG. There prevalences of allergic disorders in each nursing group did not reveal any statistically significant differences. In conclusion, nursing patterns in infancy do not seem to have certain effects on the development of allergic disorders such as infantile eczema. wheezv bronchitis or skin test positivity.

• Composites Research
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• v.14 no.2
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• pp.22-32
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• 2001

Damage induced by low-velocity impact on the curved composite laminates was experimentally evaluated for CFRP cylindrical shells with the radius of curvatures of 50, 150, 300, and 500 mm. The result was then compared with that of flat laminates and with the results by nonlinear finite-element analysis. The radius of curvatures and the effective shell stiffness appeared to considerably affect the dynamic impact response of curved shells. Under the same impact energy level, the maximum contact force increased with the decreasing radius of curvatures, with reaching 1.5 times that for plates at the radius of curvature of 50 mm. Since the maximum contact farce is directly related to the impact damage, curved laminates can be more susceptible to delamination and less resistant to the low-velocity impact damage. Delamination was distributed rather evenly at each interface along the thickness direction of curved laminates on the contrary to the case of flat laminates, where delamination is typically concentrated at the interfaces away from the impact point. This implies that the effect of curvatures has to be considered for the design of a curved composite laminate.