• Geotechnical Engineering
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• v.13 no.5
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• pp.145-154
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• 1997

Though the static pile load tests gives the mosts accurate estimation on the load carrying capacity of tested pile, it appears time-consuming and not economical. Many test methods using equipments, such as Pile Driving Analyzer(PDA), STATNAMIC, and Osterberg cell, have been introduced in Korea, and pile best using PDA has been gaining popularity because of iris fast and simple operation. Static and dynamic tests results on the piles installed in the granular coils were analyzed to investigate the effect of geometrical damping on the estimated load carrying capacity. It was found that the CAPWAP analysis without considering geometrical damping effect underestimates the pile capacity by 30~60% under certain conditions. It was observed that the underestimation of pile capacity by CAPWAP occurs on the piles installed in the water-borne granular boils by SIP methods. When Smith skin damping value(SSkn) greater than 1.0 sec/m is obtained in CAPWAP analysis, it may reflect the large possibility of underestimation of pile capacity. The introduction of the geometircal damping option in CAPWAP analysis gives reasonable pile capacity, compared with the static pile load test results, and reduces the SSb value under 0.7 sec/m.

• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.557-561
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• 1998

A die-back fungus isolated from Pinus koraiensis was identified as Cenangium ferruginosum. Mycelial growth of the fungus was the best on PDA among five media tested. Mycelial growths on agar media supplemented with extracts from coniferous trees were relatively better than those on media with extracts from non-coniferous trees. Optimum temperature and pH for the mycelial growth of C. ferruginosum on PDA were $10^{\circ}C$ and pH 5, respectively. When five-years-old P. koraiensis seedlings were artificially inoculated with the fungus for the pathogenicity test of this fungus, 80% of seedlings were infected. and the same symptoms and signs were developed as those of naturally-infected trees.

• Polymer(Korea)
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• v.31 no.2
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• pp.130-135
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• 2007

To enhance the thermo-mechanical properties of polyimide films which have potential application for the FCCL, we have synthesized the poly (amic acid) s composed of 4-components PMDA/BTDA and PDA/ODA as monomer system, u4 then they were effectively converted into 4-component polyimide films by thermal imidization process. It has been found that CTE values in the range of $100\sim200^{\circ}C$ decreased with the amount of PDA, which also caused 36% and 59% increases in tensile modulus and strength respectively. And also, peel test results on 3-layered copper clad laminate using 4-component polyimide films showed excellent adhesion strength above 1.8 kgf/cm. On the basis of obtained results it can be concluded that 4-component polyimide films may be applied for the high performance FCCL base films.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.249-258
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• 1999

Dynamic load and static load tests are performed on steel pipe piles and concrete piles at five construction sites in highway to compare the difference of load bearing mechanisms. At each site, one steel pile is instrumented with electric strain gages and dynamic tests are performed on the pile during installation. Damages of strain gages due to the installation are checked and static test is performed upon the same pile after two or seven days as well. It shows that load transfer from side friction to base resistance behaves somewhat differently according to the results of load-settlement analysis obtained from PDA and static load test. Initial elastic stage of load settlement curves of two load tests is almost similar. But after the yielding point, dynamic resistance of pile behaves more stiffer than static resistance, thus, dynamic load test result might overestimate the real pile capacity compared with static result. Analysis of gage readings shows that unit skin friction increases exponentially with depth. The skin friction is mobilized at the 1∼2m above the pile tip and contributes to the considerable side resistance. Comparison of side and base resistances between the measured value and the calculated value by Meyerhof's bearing capacity equation using SPT N value shows that the calculated base resistance is higher than the measured. Therefore, contribution of side resistance to total capacity shouldn't be ignored or underestimated. Finally, based upon the overall test results, a construction control procedure is suggested.

• Journal of Environmental Health Sciences
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• v.47 no.6
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• pp.540-547
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• 2021

Background: Indoor air pollutants are caused by a number of factors, such as coming in from the outside or being generated by internal activities. Typical indoor air pollutants include nitrogen dioxide and carbon monoxide from household items such as heating appliances and volatile organic compounds from building materials. In addition there is carbon dioxide from human breathing and bacteria from speaking, coughing, and sneezing. Objectives: According to recent research results, most indoor air pollution is known to be greatly affected by internal factors such as burning (biomass for cooking) and various pollutants. These pollutants can have a fatal effect on the human body due to a lack of ventilation facilities. Methods: We fabricated a polydopamine (PDA) layer with Ti substrates as a coating on supported glass fiber fabric to enhance its photo-activity. The PDA layer with TiO₂ was covalently attached to glass fiber fabric using the drop-casting method. The roughness and functional groups of the surface of the Ti substrate/PDA coated glass fiber fabric were verified through infrared imaging microscopy and field emission scanning electron microscopy (FE-SEM). The obtained hybrid Ti substrate/PDA coated glass fiber fabric was investigated for photocatalytic activity by the removal of ammonia and an epidermal Staphylococcus aureus reduction test with lamp (250 nm, 405 nm wavelength) at 24℃. Results: Antibacterial properties were found to reduce epidermal staphylococcus aureus in the Ti substrate/PDA coated glass fiber fabric under 405 nm after three hours. In addition, the Ti substrate/PDA coated glass fiber fabric of VOC reduction rate for ammonia was 50% under 405 nm after 30 min. Conclusions: An electron-hole pair due to photoexcitation is generated in the PDA layer and transferred to the conduction band of TiO₂. This generates a superoxide radical that degrades ammonia and removes epidermal Staphylococcus aureus.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.209-216
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• 1999

Prefabricated piles used for construction of highway bridges are most of steel pipe piles and few of prestressed concrete piles. Its installation and inspection are less controllable and have much uncertainty due to changes in subsoil and groundwater conditions. However, most of these piles have been controlled using outdated pile driving formula such as Hiley's formula which models just the energy conservation due to its simple applicability in the field. This formula results in overstriking or sometimes understocking due to buckling of pile head. Engineers cannot ensure by the formula whether pile is installed properly. To compensate the drawbacks of excising pile formula, parameters in Hiley's formula and 55 formula are reviewed. Final sets used in pile formula and PDA test results(E.O.I.D) are measured during pile driving along the depth. These measured results along the depth were compared with each other and with N values, so that relations between the each result could be inferred. Also the factor of safety which can be used for pile driving formula are suggested.

• Biomedical Science Letters
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• v.25 no.4
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• pp.367-371
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• 2019

In this study, the author observed the fungal characteristics of T. verrucosum which is commonly known as the cattle ringworm fungus in the farms of Hoengseong, Gangwon-do. After isolating 20 strains of T. verrucosum from cattle, they were cultured on SDA, PDA media and the fungal characteristics were concluded through visual observation of the colonies, microscopic findings, hair perforation test and urease test. The size of the colonies cultured on SDA media at 37 C was on an average 5 mm at 1 week, 33 mm at 2 weeks, 42 mm at 3 weeks and 58 mm after 4 weeks. Observing the characteristics of the colonies, 17 strains of T. album showing central bold radial folds, 2 strains of T. ochraceum having l throughout the colonies and 1 strain of T. discoides with rapid growth rate and gray-white cotton patterns were found. On microscopic observations of the cultured colonies on SDA, PDA media, macroconidia and microconidia were not found in T. verrucosum and hyphae and chlamydospore were only seen in T. album types. Out of 20 strains of T. verrucosum, hair perforation test was positive on only 3 strains and urease test was positive on all of the 20 strains.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.357-362
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• 1996

• Proceedings of the Korean Geotechical Society Conference
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• 1997.03a
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• pp.35-38
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• 1997

• Journal of the Korean Society of Radiology
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• v.1 no.1
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• pp.39-44
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• 2007

In this study, wireless measurement technique for human motion was developed to monitor movement disorder patients during their daily life. MICA, TinyOS, and nesC, developed by UC Berkeley, were used as wireless sensor, its software platform, and programming language. The human motion data, generated by two axial accelerometer(ADXL202) was transmitted to PDA(iPaq3630) by 916Mhz short range communication chip(TR1000). It could be stored at PDA by simple Windows CE programming. To test the developed device, it was attached at human chest and the acquired data was shown as a graph during his motion of sitting, standing, and lying. The result showed that human motion could be logged without any hooking and constraints. Therefore, this device can be used to monitor patient's movement disorder and activity of daily life(ADL).