• Journal of the Korean Applied Science and Technology
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• v.29 no.4
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• pp.618-625
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• 2012

In this study, prepared synthesis waterborne acrylic resin and water soluble milk casein resin. And than extent of casein contents in acrylic resin. We measured property of these samples by Lamb leather which is coated by acrylic-casein resins. According to measure data for solvent resistance, WAR resin and Hybrid resins had good property. Among this result knew that increase of casein constant did not influence to big change of hybrid resin property. As test of tensile strength, WAR had lowest strength($1.399kg_f/mm^2$) and WAC-3 had highest strength($1.426kg_f/mm^2$). Also we knew that best property of abrasion was WAC-3(69.774 mg.loss). In elongation case, WAR had best property(820%) in this experiment.

• Explosives and Blasting
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• v.37 no.4
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• pp.1-9
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• 2019

In this study the applicability of a Digital Image Correlation (DIC) method was investigated by measuring the displacement and vibration of rock pillar due to underground mining blasting. When combined with a high speed photography technology, the DIC method provides an excellent photographic image processing ability that can be used to convert the evolving full-field surface properties of structures to 2D or 3D set of coordinate values. The measured coordinate sets are then used to calculate the displacement, strain, and velocity of the target structure. This technique is widely used in science and engineering, and continuously finds its new application areas. In this study, the DIC system and the conventional seismograph were compared for their ability to measure the displacement and vibration produced by blasting. In the field test both methods showed similar results. Thus, it is concluded that the DIC method is feasible to measure the ground displacements and vibrations from blasting.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.649-658
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• 1997

When steel tube as a column is filled with concrete, it is common that the load-bearing capacities of CFST(Concrete Filled Steel Tube) column are increased substantially, And the CFST column can obtain a capacity of fire resistance without any additional detail on the surface of the steel tube for fire protection. In order to clarify the behavior of CFST column during fire occurrence, a theoretical study is performed, that is, a thermal analysis is used to find temperature gradient dependent on the time on the steel tube and the infilled concrete. N-M (axial force-moment) interaction curves are summarized under the consideration for time dependent variation. The material properties of concrete and steel in accordance with a temperature variation are referred to the existing general data. Thermal transient analyses are performed by finite element method through ANSYS and then these results are verified by comparing with the existing test results. On the basis of analytical results, load-carrying capacities (N-M interaction curves) are calculated by numerical analysis method.

• Tribology and Lubricants
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• v.24 no.6
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• pp.374-377
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• 2008

Due to the environmental concerns, especially the greenhouse effect and GWP (Global Warming Potential), the carbon dioxide was investigated as an alternative natural refrigerant to replace HFCs (HydroFluoroCarbons) in refrigerator or air conditioning systems. Because new compressor with carbon dioxide is going to be operated under the high pressure, the tribology of sliding surfaces in the compressor becomes very important. To improve of wear resistance in compressor parts, especially rotary type, the friction and wear characteristics of improved sliding surfaces between vane and flange were evaluated in this paper. The method of reformed sliding surface, such as micro-dimple processes, was applied on surfaces in order to improve the tribological characteristics, and their performances were evaluated experimentally. The vane-on-flange type lubricated sliding tests were performed with a high pressure wear tester using carbon dioxide. Test results showed that the reformed surfaces were very effective to reduce the friction and the wear amounts of vane surfaces. The method of improved surfaces showed good tribological properties at vane and flange.

• Journal of Pharmaceutical Investigation
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• v.26 no.3
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• pp.221-232
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• 1996

An abrasive, calcium hydrogen phosphate dihydrate (DCPD), was synthesized in a Box-wilson experimental design by reactions between phosphoric acid and milk of lime, and calcium chloride and sodium phosphate solutions, and stabilized with TSPP and TMP. The optimum conditions for preparation of DCPD from phosphoric acid with milk of lime were such as; reaction temp.; $51.9^{\circ}C$, conc. of lime; 25.9%, conc. of phosphoric acd; 77.9%, drying temp.; $60.2^{\circ}C$ and final pH; 6.46. The physico-chemical and pharmaceutical properties of DCPD were showed as follows: glycerin absorption value(68 ml/100g), whiteness(99.5%), particle size(10.9 nm), pH(7.8), and set test(pass). XRD and SEM of DCPD indicated a monoclinic system crystallographically. $N_2$ adsorption isotherm curve by BET showed non porous type II form. The micromeritic parameters of DCPD showed that surface area was $3.27{\sim}4.6\;cm^{2}/g$ and pore volume, pore area and pore radius were negligible. The rheogram of the toothpaste containing DCPD showed pseudoplastic flow with yield value of 321, and thixotropic behavior forming hysteresis loop. These results meet the requirements as abrasive standard, and sythesized DCPD is expected as a good dental abrasive such as a high quality grade in practice.

• Journal of the Society of Disaster Information
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• v.7 no.2
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• pp.87-95
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• 2011

The skid resistant of pavement surface is an important parameter since it is directly related to the traffic safety under moving vehicular loads. In particular, it should be considered as a major factor in pavement performance evaluations to reduce the traffic accident from vehicular sliding. In this study, a portable and an automatic skid resistance tests were used to evaluate the skid resistances of the in-situ pavements. The test results showed that the skid resistance of the conventional dense graded pavement was more noticeable than the other pavement types such as the drainage pavement and the stone mastic asphalt(SMA) pavement as the service life of pavement was increased.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.4 s.56
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• pp.126-136
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• 2009

The sprayed FRP strengthening technique is combining the Glass fiber and Polyester resin in open air and spraying randomly at concrete's surface with high-speed compressed air. Then it strengthens the structures with a new technique evaluated the structural performance. We applied it to concrete beam and tested for flexural strength, depended on Korea Standard(KS F 2408). Then based on the result of flexural strength, the properties were proposed that applying to structures. Based on the experiment, we have evaluated structural performance by the experiment. 1/5 scale prestressed concrete I-beam were made by Korean Highway's typical drawing in 1993. With these test results, 49.8% increased in flexural strength, improvement of the behavior of serviceability state, and strengthening was surely effective for controlling deflection and crack of structure. Consequently, it can be summarized that Sprayed FRP technique has prospect to improve the performance of structure.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.15-18
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• 2006

The test result of mat concrete applying both hydration heat difference and insulation curing method on new construction of Cheongju university educational building are summarized as following. Both fresh concrete and compressive strength properties were satisfied In aimed value. Setting time of concrete incorporating 15% of fly ash(FA) retarded 1.2 hour than control concrete. Temperature history of mali concrete indicated that the highest temperature of center was exhibited at $126^{\circ}C$ after 51 hours while the highest temperature of upper section was $10.6^{\circ}C$ after 46 hours. Temperature Difference between center and surface was managed at less than $6^{\circ}C$ during whole curing period. In addition the temperature of upper section secured more than $3.3^{\circ}C$ while the temperature of outside was indicated at less than $-10^{\circ}C$. Maturity by parts of construction secured more than $30^{\circ}C$ DD higher than outside at 3 days. The more number of times, applying insulation curing method by double bubble sheets, increased, the higher economic effect was secured. Overall it was clear that applying both double bubble sheets and hydration heat difference method on this new construction can resist hydration heat crack, early frost demage and strength decrease. It also significantly contributed quality improvement of cold weather concreting

• Journal of the Korean GEO-environmental Society
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• v.14 no.5
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• pp.49-56
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• 2013

The necessity of exploration in deep sea increases to develop the natural resources. The deep marine sediments, which were recovered from the hydrate occurrence regions during the Ulleung Basin Gas Hydrate Expedition 2 (UBGH2), East Sea, Korea in 2010, are explored to obtain the geotechnical characteristics and strength parameters. The index properties of the specimens including the atterberg limits, specific surface, and particle size distribution are measured and compared with the previous studies. X-ray diffraction, scanning electron microscope, and X-ray energy dispersive spectroscopy are conducted to analyze the clay mineralogy, chemical composition, and microstructure of the sediments. Strength parameters and shear wave velocities are measured with the axial strain by using an instrumented triaxial device. The strength parameters estimated by empirical equations are compared with the experimental results.

• The Journal of Advanced Prosthodontics
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• v.4 no.1
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• pp.24-29
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• 2012

PURPOSE. To compare the effect of sodium hypochlorite and microwave disinfection on the dimensional stability of denture bases without and with relining. MATERIALS AND METHODS. A brass die was prepared by simulating an edentulous maxillary arch. It was used to fabricate 1.5 mm and 3 mm of thickness denture bases (n = 40). The 1.5 mm of thickness-specimens (n = 20) were relined with 1.5 mm of autopolymerizing relining resin. Five holes were prepared over crest of ridge of brass die with intimately fitting stainless steel pins which were transferred to the intaglio surface of specimens during fabrication of denture bases. For calculation of dimensional changes in denture bases, differences between the baseline area before and after disinfection of the specimens were used. The denture bases without and with relining were divided into 2 groups (each n =20). Data were analyzed using student paired 't'and unpaired 't'test. RESULTS. Microwave disinfection produces significant shrinkage in both denture bases without relining (t =17.16; P<.001) and with relining (t = 14.9; P<.001). Denture bases without relining showed more shrinkage when compared with relined denture bases after microwave disinfection (t = 6.09; P<.001). The changes in dimensional stability after sodium hypochlorite disinfection were not significant for both denture bases without relining (t = 2.19; P=.056) and denture bases with relining (t = 2.17; P=.058). CONCLUSION. Microwave disinfection leads to increased shrinkage of denture bases without and with relining. Chemical disinfection with sodium hypochlorite seems to be a safer method of disinfection with regards to physical properties such as changes in dimensional stability.