• Journal of Chest Surgery
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• v.14 no.1
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• pp.9-16
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• 1981

Twenty eight patients with conpnital heart disuse underwent lung biopsy to assets pulmonary obstructive vascular disease at cardiac surpry. Thirteen patients had patent ductus arteriosus, 10, ventricular septal defects and S, atrial septal defects. The aaes were between 2 and 30 years. In patients with patent ductus arteriosus lung biopsy was performed from the IIngular Hlment. The anterior seament of the right upper lobe was blopsled in cases with ventricular septal defect and atrial septal defect. Grading of pulmonary obstructive vascular disease could not be assessed In 9 cases. In 2 cases poor quality of the slides made us impossible to evaluate and In 7 cases there were no suitable small muscular arteries to evaluate in the slides of lung tissue especially taken from the IIngular seament. Nineteen cases were evaluated pulmonary obstructive vascular disease. Among them 17 cases had Heath-Edwards changes of grade 1 and 2 patients had that of grade 3. The thickness of media was measured. It was expressed as percentage of medial thickness to outer diameter of artery. The medial thickness was correlated proportionally with elevation of pulmonary arterial pressure and pulmonary vascular resistance to systemic vascular resistance ratio. There were no complications related to the procedure of lung biopsy.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.385-390
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• 1997

In the mixing proportion of high flowing concrete we have to use quantity of power such as cement and superplasticizer, and increase the proportion of fine aggregate more than that of plain concrete to increase flowability and segregation resistance. Therefore, the fresh state of high flowing concrete is largely affected by superplasticizer and change of grade the percentage of surface water. This study aims at development of self-filling up high flowing concrete without compaction, in case of using the fine aggregate of standard grade range, by examination on the influence of fresh state of high flowing concrete, and by understanding influence on various fluidity such as flowability, reinforcement passibility, fillingability, segregation resistance.

• Journal of Welding and Joining
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• v.30 no.2
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• pp.76-80
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• 2012

In this study, the effect of the welding current on the hardness characteristics and microstructure in the resistance spot welding of 1GPa grade cold-rolled DP steel was investigated, Also, correlation between the hardness and microstructure was discussed. In spite of the change in the welding current, the hardness distributions near weld was similar. the hardness in the HAZ and the fusion zone was higher than that of the base metal and the hardness in the fusion zone was variated with the location. Especially, the hardness of HAZ adjacent to the base metal showed maximum value, and softening zone in the base metal adjacent to HAZ was found. With the increasing of welding current, there were no difference in maximum hardness and average hardness in the fusion zone were, but the hardness of the softening zone reduced. The difference in the hardness in each location of weld due to grain size of prior austenite. The softening of the base metal occurred by tempering of the martensite.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.193-200
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• 2023

Titanium alloy (grade-4) is commonly used in industrial and medical applications. To improve its corrosion resistance and biocompatibility for medical use, it is necessary to form a titanium oxide film. In this study, the morphology of the oxide film formed by anodizing Ti-grade 4 using different electrolytes was analyzed. Wetting properties before and after surface modification with SAM coating were also observed. Electrolytes used were categorized as A, B, and C. Electrolyte A consisted of 0.3 M oxalic acid and ethylene glycol. Electrolyte B consisted of 0.1 M NH₄F and 0.1 M H₂O in ethylene glycol. Electrolyte C consisted of 0.07 M NH₄F and 1 M H₂O in ethylene glycol. Samples B and C exhibited a porous structure, while sample A formed a thickest oxide film with a droplet-like structure. AFM analysis and contact angle measurements showed that sample A with the highest roughness exhibited the best hydrophilicity. After surface modification with SAM coating, it displayed superior hydrophobicity. Despite having the thickest oxide film, sample A showed the lowest insulation resistance due to its irregular structure. On the other hand, sample C with a thick and regular porous oxide film demonstrated the highest insulation resistance.

• Magazine of the Korea Concrete Institute
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• v.18 no.5 s.94
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• pp.10-13
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• 2006

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.200-201
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• 2005

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.285-292
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• 2006

The objective of this study is to introduce the development of the first Korean full-scale APT(Accelerated Pavement Tester) and to compare the performances of general dense grade asphalt mixture and modified asphalt mixtures as the first running of the tester. The tests evaluated the rutting resistance for dense grade mixture and three different modified asphalt mixture under three different temperature conditions (25-30, 40, $50^{\circ}C$). The results of the testing were compared with the laboratory test results. Results of the tests indicated that the all the modified asphalt sections showed higher rutting resistance than the dense grade section. Especially, the difference was more noticeable at higher temperature condition. Additionally, $G^*/sin{\delta}$ is found out to be an important factor for permanent deformation prediction whereas the resilient modulus was not.

• Journal of the Korean institute of surface engineering
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• v.50 no.4
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• pp.272-276
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• 2017

The response of AISI 310 type austenitic stainless steel to the novel low temperature plasma carburizing process has been investigated in this work. This grade of stainless steel shows better corrosion resistance and high temperature oxidation resistance due to its high chromium and nickel content. In this experiment, plasma carburizing was performed on AISI 310 stainless steel in a D.C. pulsed plasma ion nitriding system at different temperatures in $H_2-Ar-CH_4$ gas mixtures. The working pressure was 4 Torr (533Pa approx.) and the applied voltage was 600 V during the plasma carburizing treatment. The hardness of the samples was measured by using a Vickers micro hardness tester with the load of 100 g. The phase of carburized layer formed on the surface was confirmed by X-ray diffraction. The resultant carburized layer was found to be precipitation free and resulted in significantly improved hardness and corrosion resistance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.7-10
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• 2011

In this study, evaluation system of impact resistance performance is proposed. Compressive strength of concrete is 40, 60 and 80MPa. It evaluate impact resistance performance to use projectile 6, 7 and 8mm size. As a result, safety performance is more higher when the compressive strength is increased in. Compared with Hughes's formula, evaluation system of impact resistance performance is appropriated.

• Journal of the Korea Institute of Building Construction
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• v.3 no.4
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• pp.73-78
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• 2003

In this Study, we examined the influence of characteristics of rolling loads by casters on separation resistance of substrate concrete and synthetic resin floor coating. In the experiment, we first prepared floor samples having substrate concrete of various compressive strength, surface hardness and surface configurations, then put the coated samples to the test of separation resistance with Rolling Caster Loading Machine. Three loading conditions consisted of different kinds of casters, rolling conditions, and coating materials. Consequently, we clarified that the grade of separation resistance varied widely according to the characteristics of substrate concrete and rolling loads.