• Steel and Composite Structures
• /
• v.33 no.6
• /
• pp.877-889
• /
• 2019

The developments of double skin composite (DSC) walls with novel enhanced C-channel connectors (DSCW-EC) were reported. Followed axial compression tests on prototype walls were carried to evaluate structural performances of this novel DSC composite structures. The testing program consists of five specimens and focused on the layout of the novel enhanced C-channel (EC) connectors, which include the web direction of C-channels, steel-faceplate thickness, vertical and horizontal spacing of C-channels. Crushing in concrete core and buckling of steel faceplate were two main observed failed modes from the compression tests. However, elastic or plastic buckling of the steel faceplate varies with designed parameters in different specimens. The influences of those investigated parameters on axial compressive behaviors of DSCW-ECs were analyzed and discussed. Recommendations on the layout of novel EC connectors were then given based on these test results and discussions. This paper also developed analytical models for predictions on ultimate compressive resistance of DSCW-ECs. Validation against the reported test results show that the developed theoretical models predict well the ultimate compressive resistance of DSCW-ECs.

• Journal of the Korean Society for Railway
• /
• v.9 no.4 s.35
• /
• pp.493-498
• /
• 2006

In this study, two large pile load tests were performed in the deep sand gravel deposit of Nakdong river basin so that the characteristics of the load transfer was identified. The fully instrumented rectangular barrette pile in the size of $1.5\times3.0m$ and the circular bored pile of the diameter 1.5 m were placed into the ground below 50 m. Under the applied loads of 2,400 tonf and 4,000 tonf, the test results of the load transfer showed the portion of 83% and 93% of the applied loads on the barrette pile and the bored pile, respectively, were supported by the skin friction along the pile shaft. It was revealed that the most of these skin friction mobilized in sand layer underlying clay layer having N-value more than 30 and that the friction per unit area of the bored pile was larger than the friction of barrette pile. However, if embedded in the stiff sand graval layer, the both piles were proven to be sufficient for using as the friction piles.

• Proceedings of the KSR Conference
• /
• 2001.10a
• /
• pp.558-561
• /
• 2001

SIP(Soil cement Injected Precast pile) that inserts a precast pile after injecting a cement paste into a boring has been applied rapidly through the change of construction circumstances. But there isnt any logical equation of a bearing capacity fitted to SIP yet. So Meyerhof equation has mainly been used to predict a bearing capacity in a design stage instead. But it has shortcomings such as lack of confidence because it has derived not from a theory but from an experience obtained from the result of SPT (Standard Penetration Test) and because a penetration depth tends to be deeper by an excessive design that depends on an end bearing capacity of a pile more than a skin frictional resistance. In this study, thereupon, a direct shear test in the laboratory was performed to both SM and SC soils in variable conditions to verify skin friction properties for the purpose of presenting some reasons capable of reducing penetration depths. Through the tests, soil to soil of SM in cohesion, rough panel to soil of SM in friction angle and soil to soil of SM in shear strength tended to be high. And a shear strength increased as its total unit weight increased in all cases.

• Steel and Composite Structures
• /
• v.26 no.6
• /
• pp.759-769
• /
• 2018

This paper studies shear and tensile behaviors of headed stud connectors in double skin composite (DSC) structure. Firstly, 11 push-out tests and 11 tensile tests were performed to investigate the ultimate shear and tensile behaviors of headed stud in DSC shear wall, respectively. The main parameters investigated in this test program were height and layout of headed stud connectors. The test results reported the representative failure modes of headed studs in DSC structures subjected to shear and tension. The shear-slip and tension-elongation behaviors of headed studs in DSC structures were also reported. Influences of different parameters on these shear-slip and tension-elongation behaviors of headed studs were discussed and analyzed. Analytical models were also developed to predict the ultimate shear and tensile resistances of headed stud connectors in DSC shear walls. The developed analytical model incorporated the influence of the dense layout of headed studs in DSC shear walls. The validations of analytical predictions against 22 test results confirmed the accuracy of developed analytical models.

• Geomechanics and Engineering
• /
• v.10 no.3
• /
• pp.315-324
• /
• 2016

Frictional forces between soil and structural elements are of vital importance for the foundation engineering. Although numerous studies were performed about the soil-structure interaction in recent years, the approximate relations proposed in the first half of the 20th century are still used to determine the frictional forces. Throughout history, wood was often used as friction piles. Steel has started to be used in the last century. Today, alternatively these materials, FRP (fiber-reinforced polymer) piles are used extensively due to they can serve for long years under harsh environmental conditions. In this study, various ratios of low plasticity clays (CL) were added to the sand soil and compacted to standard Proctor density. Thus, soils with various internal friction angles (${\phi}$) were obtained. The skin friction angles (${\delta}$) of these soils with FRP, which is a composite material, steel (st37) and wood (pine) were determined by performing interface shear tests (IST). Based on the data obtained from the test results, a chart was proposed, which engineers can use in pile design. By means of this chart, the skin friction angles of the soils, of which only the internal friction angles are known, with FRP, steel and wood materials can be determined easily.

• Proceedings of the Korean Reliability Society Conference
• /
• 2006.05a
• /
• pp.27-31
• /
• 2006

Rubber hoses for automobile radiators are apt to degraded and thus failed due to the influence of contacting stresses of air and coolant liquid under thermal and mechanical loadings. The aging behaviors of the skin part of the hoses due to thermo-oxidative and electro-chemical stresses were experimentally analyzed. Through the thermo-oxidative aging test, it was shown that the surface hardness IRHD(International Rubber Hardness Degrees) of the rubber increased with a considerable reduction of failure strain as the aging time and temperature were large. On account of the penetration of coolant liquid into the skin part the weight of rubber specimens influenced by electro-chemical degradation (ECD) test increased, whereas their failure strain and IRHD hardness decreased. The hardness decreased further as the test site on the hose skin approached to the negative pole.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.34 no.2
• /
• pp.86-90
• /
• 2021

Objectives : The purpose of this study is to report the treatment of the Tinea corporis treated by Korean medicine. Methods : The skin lesion with keratin were scraped and placed on a slide glass, and the KOH solution was dropped and observed under a microscope. After the hyphae was confirmed, a ChoPho-bang was prescribed and applied twice a day. Results : In the KOH test performed again 3 weeks after treatment, no hyphae was found and the skin lesion was completely disappeared. Conclusions : For Tinea Corporis, the KOH test is recommended to distinguish it from other skin diseases, and application of ChoPho-bang is effective for treatment.

• Proceedings of the SCSK Conference
• /
• 2003.09b
• /
• pp.239-240
• /
• 2003

Type I (collagen) and procollagen are reduced in aged human skin. This reduction could result from increased degration by metalloproteinases and from reduced procollagen synthesis and skin collagenase is required for initiation of the degration of type I collagen. In the present study, we study on assay the collagen and collagenase in natural plants using the fibroblast human skin cell. We select the 15 kind of plants used to herbal and 4 kind of fraction(by methylene chloride, ethyl acetate, n-butanol, water). Among these extract, the ethyl acetate fraction from benincasa hispida/prunus persica, trichosanthes kiriowii, trogopterus xanthipes and methylene chloride fractions from benincasa hispida/prunus persica, torilis japonica and n-butanol fraction from cnidium officinale, chrysanthemum sibiricum were selected for further experiments as they exhibited distinctive amount of collagen compared to other natural extracts. These extracts were again subjected to collagenase assay test. Benincasa hispida/prunus persica extract was shown to have exellent collagen synthesis activity from result of the collagen assay test and the other extract was shown to have over 130% of collagen synthesis activity. But, in the study of collagenase assay test just only trogopterus xanthipes extract was shown to have collagenase inhibition.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.48 no.4
• /
• pp.343-355
• /
• 2022

Customized cosmetics are continuously mentioned as cosmetics in response to changes in the social environment and trends that emphasize individuality. Therefore, in this study, four types of nanoemulsion ampoules corresponding to skin types were prepared by different ratios of nanoemulsion formulation and ampoule formulation, and the applicability as a customized cosmetic base was checked. Particle size, polydispersity index, zeta potential, and viscosity according to time for 90 d were measured for four nanoemulsion ampoules with different volatile residues, and turbiscan was measured as a method for evaluating the stability of a colloidal dispersion system. Finally, human usability satisfaction was evaluated. As a result, it was confirmed that four kinds of nanoemulsion ampoules had a higher amount of volatile residue in the dry skin test product than in the oily skin test product. The pH was in the range of 6.41 to 6.88, and the particle size was in the range of 170 to 174 nm, and the change after 90 d was within 1.2% of the maximum, and there was no specificity in particle size stability. It was confirmed that the polydispersity index was almost constant, and showed a particle size distribution close to monodispersity by showing a change within a value smaller than 0.21 in all test products. The zeta potential was initially -63 mV or more for all four types of test products, and although it showed a slight decrease with time, there was little change to the extent of a maximum decrease of 2.5%. Viscosity was initially in the range of 4,100 to 5,100 cps and showed a decreasing trend with time, showing a maximum decrease of 37.7%. In the turbiscan measurement, the turbiscan stability index, a measure of stability, was all below 1.0, indicating dispersion stability. In the usability satisfaction evaluation (6 points) of 4 nanoemulsion ampoules corresponding to skin type, oily skin product (5.42 ± 0.67 points) > neutral oily skin product (5.36 ± 0.67 points) > neutral dry skin product (5.15 ± 0.69 point) > dry skin product (4.75 ± 0.75 points) in the order of evaluation. Four types of nanoemulsion ampoules are physically stable and have confirmed their applicability as a customized cosmetic base according to skin type, and are expected to expand in various ways.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.38 no.3
• /
• pp.219-224
• /
• 2012

European Union prohibited the marketing of cosmetic products containing constituents that have been examined through animal experiments. Thus, non-animal test models are needed to replace animal experiments. The reconstructed skin models are important as a test system for cosmetic, pharmaceutical, and medical device safety testing. In the present study, we tried to develop an optimal skin equivalent model containing basement membrane and epidermis. For this purpose, we used mesenchymal stem cells (MSCs) and/or preadipocytes as well as fibroblasts as the dermal matrix cells. The formation of basement membrane and epidermis was verified by immunohistochemical stains. Among various models, the epidermis was thickest when MSCs were used in the dermal matrix. Furthermore, PCNA and involucrin distribution showed that dermal matrix with MSCs resembled human skin. Therefore, skin equivalents with MSCs could be developed as a non-animal test model to replace animal experiments.