• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.492-497
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• 2005

In this study, we propose an advanced nanoindentaion test, Nano Pillar Compression Test (NPCT) to measure a stress-strain relation for micro scale polymer structures. Firstly, FEM analysis is performed to research behavior of micro polymer pillars in several specimen aspect ratios and different friction conditions between specimen and tip. Based on the FEM results, micro scale UV-curable polymer pillars are fabricated on a substrate by Nano Stereo Lithography (NSL). To measure their mechanical properties, uniaxial compression test is performed using nanoindentation apparatus with flat-ended diamond tip. In addition, the dependency of compression properties on loading condition and specimen size are discussed.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.41-53
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• 2024

Titanium alloy is gaining attention in the medical industry due to its excellent biocompatibility and osteoconductivity. However, the natural oxide film on the titanium surface is insoluble, resulting in inadequate bone adhesion. Therefore, it is necessary to optimize the contact between biological tissues and implant surfaces, and alter the chemical composition and morphological characteristics of the implant surface. In this study, the anodization method was applied to titanium surface treatment to form a uniform and robust oxide film. Subsequently, a chemical process, pore-widening, was employed to change the morphological characteristics of the oxide film. The concentration of the pore-widening solution was varied at 2, 4, 6, and 8 wt% and the process time was set at 30 and 60 minutes. As the concentration of the pore-widening solution increased the pore diameter of the oxide film increased. Notably, at 6 wt% for 60 minutes, the oxide film exhibited a coexistence of pillars and pores. Based on this, it was determined that surface roughness increased with higher concentration and longer process time. Additionally, the presence of pillars and pores structures maximized hydrophilicity. This study provides insights into enhancing the surface properties of titanium for improved performance in medical implants.

• Industry Promotion Research
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• v.9 no.1
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• pp.203-212
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• 2024

The purpose of this study is to examine the validity of Hidden Stems (支藏干) in the Four Pillars of Destiny with regard to the use of human governance periods in the hidden stems (人元用事). First, there is a theory of assigning period of governance for designated constituents (司令論) in the Hidden Stems of the Earthly Branch. Second, there is a theory that determines the structure of the Four Pillars by the Exposed Constituent from the Hidden Stems (透出論) in the Month Earthly Branch. Since these two theories conflict with each other and cause confusions, this study examined the theory of Hidden Stems in the Four Pillars Classics and examined the historical development of governance period for constituent hidden stems and their validity. The results of the study are as follows: Firstly, the number of dates assigned to respective constituents does not correspond to the calendarical principle, and the assignment of the governance dates for each constituent does not correspond to the principles proposed in ancient books of Four Pillars. Second, though it is said in the Classics that 72 days are equally assigned to each of the Five Elements, actual distributed days for the five elements was 65 days for Wood, 55 days for Fire, 100 days for Earth, 65 days for Metal, and 65 days for Water. Third, though it is said that 7 days should be designated to Yang Earth Mu for the months of Tiger 寅, Monkey, Snake, and Pig, it is logically more legitimate to assign those days to Yin Earth Ki since the month before Tiger is Ox, and the month before Monkey is Goat. Lastly, rationale behind assigning Ki Earth only to Horse Oh as constituting Hidden Stem while disregarding months of Rat, Rabbit, and Rooster is considered not reasonable. Looking at these results comprehensively, it is concluded that the Exposed Constituent theory is logically more appropriate than Assigned Governance theory.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.107-107
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• 2009

Micro pillar structure was investigated for the energy havesting applications. The micro pillar structures were investigated to find proper size of pillars. In this experiments, the aspect ratio between the height and diameter were changed to extract maximum peizoelectric coefficient. We proposed the idea and model for the energy harvesting systems based on the micro-pillar structure.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.423-428
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• 1994

High strength concrete was placed at the mass concrete slabs, walls, pillars of RC building from August till August. And the construction is going on now. This paper presents mix design, production, quality control and experience with field application of high strength ready-mixed concrete under hot weathered conditions. It is shown to be possible to produce high strength concrete that has 45MPa compressive strength using superplasticizer and cement replaced with 20% fly-ash with appropriate control.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.1-11
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• 2008

The purpose of this study is to examine the species of wooden members used in the Youngsanjeon Hall of the Sucknamsa temple in Anseong, Korea. Ninety-five wood samples from pillars, head-penetrating ties, beams, corner rafter, rafter, floor board and other wood members were identified. Seven species identified were hard pine, exotic pine, Zelkova serrata, Ginkgo biloba, Diospyros, Quercus(Cerrus) and Pyrus spp. In the case of pillars, eight were hard pines and the others Zelkova and Pyrus. Species of angle rafter were Ginkgo biloba and Zelkova. and those of beams were one hard pine and one Zelkova. Two purlin samples were Quercus(Cerrus) and rafters were hard pines except one Ginkgo and one exotic pine. Roof-filling timbers were identified as Zelkova and Diospyros spp. The other samples of roof-filling timbers were all identified as hard pines. The use of Ginkgo and several hardwoods in addition to hard pines may indicate supply of local logs near the Sucknamsa temple.

• Journal of the Korean GEO-environmental Society
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• v.21 no.12
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• pp.17-21
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• 2020

Over 60% of South Korea's land consists of mountainous topography, and recently, due to earthquakes, localized heavy rains and road development, the risks of rockfalls are getting higher. As of now, rockfall prevention facilities are being constructed in 70% of Korean roads cut slope and rockfall protections account for about 20% of them. Rockfall protection's supporting capacity is defined by combining performance of wire mesh, pillars and wire ropes. For the existing constructed rockfall protection, standards of pillars that can absorb 48~61 kJ amount of energy, wire ropes and wire mesh are presented in Guidelines for the installation and management of traffic safety facilities, Rockfall prevention facilities by Ministry of Land, Transport and Maritime Affairs (2008). However, each factor's correlation of absorption energy is not presented so it is uncertain. This study will conduct vertical drop test and identify adequacy of rockfall protection net of displacement quantity calculation factor which is delta and evaluate rockfall protection net's absorbable energy through standards of overseas performance evaluation criteria.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.1
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• pp.37-42
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• 2010

The stay cylinder weld at the steam generator of Korean Standard Nuclear Power Plants is safety class I component and is subjected to be inspected by the volumetric examination such as ultrasonic method. As accessibility of this area is limited due to the narrow space and high radiation, the existing manual inspection method involves various difficulties. Moreover operators may be exposed to internal contamination by contaminated dust during the surface buffing process to improve the inspection reliability of this area. Recently the new automatic inspection system for stay cylinder welds has been developed. The inspection system basically consists of a driving assembly, data acquisition device and signal processing units. The driving assembly is classified by 1) the scanner for inspecting and buffing the weld, 2) pillars for guiding the scanner and 3) the base frame for loading and supporting pillars. The scanner has 4 sensor modules to inspect in 4 refracted angles and 4 incident directions. These components can be inserted into the skirt of the stay cylinder through the manway hole and assembled easily by one-touch in the skirt. Data acquisition device and signal processing units developed in previous works are also newly upgraded for better processing of data analysis and evaluation. The system has been successfully demonstrated not only in the mock-up but also in the field. In this paper, newly developed inspection system for the stay cylinder weld of the steam generator is introduced and their field applications are discussed.

• Explosives and Blasting
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• v.36 no.1
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• pp.12-19
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• 2018

When an underground limestone mine selects room-and-pillar mining method, in which the stability of mine openings is maintained by leaving safety pillars, the stability of safety pillars is always incompatible with their productivity. Therefore, the engineering decision for stability and productivity is essential. In this study, a progress of excavation faces by conventional blasting pattern has been examined in field for investigating over-break and stereo-photogrammetry method has been applied to this field measurement for improvement of accuracy. Also this result has been reflected instantly to composite blasting pattern by feedback, for minimizing overbreak. Field tests showed the relevant results that $3.5m^2$ in over-break out of $70m^2$ in total excavation face has been decreased, that is 5% of reduction rate in maximum.

• Journal of Conservation Science
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• v.36 no.1
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• pp.15-27
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• 2020

The Main Hall of the Fengguo monastery in Yixian county, Liaoning province, China, is the best preserved and largest wooden Buddhist structure, typical of the Liao dynasty style, in China. However, some degradation to the timber frame of the Main Hall has been noted, and this is causing concern in terms of the long-term preservation of the structure. In this study, wooden pillars showing the degradation phenomena of whitening, for areas in contact with the stone floor, and extensive surface damage at higher locations(mostly above 1 m) have been examined. Samples taken from wooden pillar surfaces were analyzed using X-ray powder diffraction, Fourier-transform infrared spectroscopy(FTIR), ion chromatography, and pH measurements. With respect to the whitening phenomenon, we found inorganic calcium precipitates and oxalate ions, along with higher pH values. These symptoms indicated that chemical changes were taking place in response to alkaline conditions, suggesting that alkaline mixtures with calcium content in the foundations may be responsible. Regarding the upper surface-damaged areas, no valid evidence for chemical degradation was found using FTIR analysis, while damaged areas exhibited the presence of more bat guano-related materials than which were apparent in undamaged areas. The occurrence of this surface-damaged phenomenon has therefore been attributed to physical damage caused by bat activity over long periods of time.