• Journal of Korean Society of Steel Construction
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• v.29 no.2
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• pp.147-158
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• 2017

The present study focused on the structural performance of newly developed prefabricated composite columns (PSRC composite column) using bolt-connected steel angles. Concentric axial loading tests were performed for four 2/3 scaled PSRC column specimens and two conventional SRC column specimens. The test parameters were the spacing and sectional configurations of lateral reinforcement, and width-to-thickness ratio of steel angles. The test results showed that the axial load-carrying capacity and deformation capacity of the PSRC column specimens were comparable to those of the conventional SRC column specimens. Closely spaced steel plates and Z-shaped steel plates for lateral reinforcement increased the deformation capacity of the PSRC column specimens. The load-carrying capacity was greater than the prediction by current design codes. Numerical analysis was performed for the specimens. The results agreed well with the test results in terms of initial stiffness, load-carrying capacity, except for strength degradation due to cover concrete spalling.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.139-152
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• 2006

A spent fuel storage cask is required to prove the safety of a canister under a hypothetical accidental drop condition. A hypothetical accidental drop condition means that a canister is assumed to be a lee drop on to a pad of the storage cask during loading it into a storage cask. A pad of the storage cask absorbs shock to maintain the structural integrities of a canister under a hypothetical accidental drop condition. In this paper a finite element analysis for various pad structures was carried out to improve the structural integrity of a canister under a hypothetical accidental drop condition. A pad of a storage cask was designed a steel structure with concrete. The 1/4 height of a pad was modified with a structure composed of a steel and a polyurethane foam as a impact limiter. The effect of a shape of a steel structure was studied. The effects of the thickness of a steel structure and the density of a polyurethane foam was also studied.

• Korean Journal of Remote Sensing
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• v.23 no.6
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• pp.493-500
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• 2007

In general, it accomplished a spectral reflectance analysis to be, the measurement results appear differently by targets, methods and condition. This paper presents a standard methodology for preprocessing mineral/rock samples and setting the distance from a target to the sensor, and then examines closely the spectral features for pyrophyllite. The size of mineral/rock samples is various according to the condition and scale of outcrop, so it is important to maintain the distance between the sensor and the sample. Before standardization for preprocessing samples and the sensor and sample distance, we prepare various rock samples (Quartz Porphyry) such as natural rock, pebble, powder and cutting rock. For a qualitative analysis to minimize the effect of surface condition of the sample and shadow, we maintains the distance from the sample to the sensor at 30cm and measures three times repeatedly for cutting the sample at $1{\sim}2cm$ thickness. To illustrate the proposed methodology, a case study for pyrophyllite was carried out. In this study, pyrophyllite showed an absorption pattern at wave length of 1.406nm, 1,868nm, 2.180nm and 2.309nm, and a higher grade represented strong absorption at 1.406nm and 2.180 nm. These absorption feature corresponds the band 7 of LANDSAT TM and band 8 of ASTER imageries. So, using these results, pyrophyllite deposits were extracted from other features (such as barren area, concrete area, bed of river, stone pit area etc.).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.317-325
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• 2020

The Korea Radioactive Waste Agency plans to expand the storage capacity of radioactive waste by constructing a radioactive waste inspecting building to solve the problem of the lack of inspection space and drum-handling space in the radioactive waste receipt and storage building for the first-stage disposal facility. In this study, the exposure doses of radiation workers that handle new disposal containers for decommissioning waste in the storage areas of the radioactive waste inspecting building were calculated using the Monte Carlo N-particle transport code. The annual collective dose was calculated as a total of 84.8 man-mSv for 304 new disposal containers and an estimated annual 306 working hours for the radiation work. When the 304 new disposal containers (small/medium type) were stored in the storage areas, it was found that 25 radiation workers should be involved in acceptance/disposal inspection, and the estimated exposure dose per worker was calculated as an average annual value of 3.39 mSv. When the radiation workers handle the small containers in high-radiation dose areas, the small containers should be shielded further by increasing the concrete liner thickness to improve the work efficiency and radiation safety of the radiation workers. The results of this study will be useful in establishing the optimal radiation working conditions for radiation workers using the source term and characteristics of decommissioning waste based on actual measurements.

• Journal of the Korean Society of Radiology
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• v.9 no.5
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• pp.295-300
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• 2015

There are various type of particle accelerators such as Kyoungju 100-MeV proton beam accelerator in Korea. And Korea plans to build large particle accelerator such as heavy ion accelerator and 4th generation light source facility. The accelerated high energy particles of these facility produce 2nd neutron after nuclear reaction with target materials. And then these 2nd neutron activate structural materials and surrounding environment. Accordingly, it is important to consider the activation and shielding calculation on design of facility for safety operation. In this study, we tried to calculate and compare the neutron flux from the interaction $^{la}150$ beam with target material(Cu) according to thickness of iron and concrete shielding material by MCNPX 2.7 with nuclear library JENDL/HE 07and la150. To verify the properties of nuclear library, we compared computational results with experimental value. These results can be used for dose evaluation technology in planning of the shielding of large particle accelerator.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.285-294
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• 2020

This study investigated the use of Ground Penetrating Radar (GPR) over a two-decade period on public roads, focusing on the electromagnetic characteristics of the pavement dielectrics and attenuation. From the results, a typical range of characteristic value, influencing factors, and a correction method were suggested. The typical dielectrics of asphalt pavements were 4-7, as measured by an air-coupled 1 GHz GPR antenna. The dielectrics of concrete pavements were very large in the early age, but were drastically reduced with ageing. Ten years on, collection was in the range of 6-12. The dielectrics were proportional to the relative humidity (R.H.) of the atmosphere. The effects were reduced to one eighth with an overlay. Attenuation generally increased with thickness of the road layer, and also increased where there was damage. The GPR results could also vary depending on the weather conditions as well as on the characteristics of the GPR equipment, even at the same frequency. Therefore, GPR surveys should be performed on road surfaces without debris on a single, fine day. The reliability of the GPR analysis could be improved by cores and equipment calibration with other non-destructive test surveys.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.10-18
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• 2018

The primary purposes of this study are to understand a fundamental aspect of current uniformity around a reinforcing bar (rebar) in cement mortar, and to develop an accurate monitoring method in a wet-dry cycling process with the alternative current (AC) impedance method. Three cement mortar specimens with two embedded rebars were prepared in the laboratory. As a main variable, the distance between two rebars was designed to be 10, 20 and 30 mm with the same thickness of 20 mm. To simulate the corrosion of rebars in concrete structures in a marine environment, three cement mortar specimens were exposed to 15 wet-drying cycles (24-hour-immersion in seawater and 48-hour-drying in a room temperature) in the laboratory. It was observed that the potential level shifted to a noble value during corrosion potential monitoring, which is attributed to acceleration of dissolved oxygen diffusion at the drying process. AC impedance was measured in a frequency range from 100 kHz to 1 mHz on a wet-drying process. A theoretical model was proposed to explain the interface condition between the rebars and cement mortar by using the equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE (constant phase element). It was observed that the diffusion impedance appeared in a low frequency range as corrosion of rebars progresses. At the drying stage of the wet-drying cycles, the currents line for monitoring tended to be non-uniform at the interface of rebar/mortar, being phase shift, ${\theta}$, close to $-45^{\circ}$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.3
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• pp.177-197
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• 2011

In this study, a series of fire experiments under $HC_{inc}$ and ISO834 (duration of 4 hour) fire scenarios were carried out for three different types of fire protection measures for the segment joint to evaluate their applicabilities to an immersed tunnel. The experimental results revealed that an expansion joint installed to allow relative movements between concrete element ends in an segment joint is the most vulnerable to a severe fire. For the fire protection measure where the originally designed steel plates at an expansion joint arc replaced by fire-resistant boards, the experiments showed that they cannot achieve good fireproofing performance under both $HC_{inc}$ fire scenario and ISO834 (4 hour) fire scenarios since the installation of fire-resistant boards results in the reduction of the sprayed fire insulation thickness. On the other hand, the application of modified bent steel plates replacing the original steel plates was proved to be very successful in fireproofing of the expansion joint due to more sprayed materials filled in bent steel plate than in the original design concept as well as higher adhesion between the steel plate and the sprayed fire insulation layer.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.537-544
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• 2021

In order to describe the fill-up stages of a near-surface disposal facility vault, a mock-up test is performed, and its behavior during the fil l -up stages is investigated. On an in-site concrete foundation with a l ength of 6600mm, a width of 6600mm and a thickness of 400mm, a reinforced concrete disposal vaul t is manufactured with 4 precast (PC) corner wal l s and 8 PC side wal l s. 36 wasted drums are pl aced on the 1st fl oor in 6 by 6, and then the empty space is fil l ed with grout fil l er. These processes are repeated up to the 5th floor, and the verticality and the joint gaps are measured for each fill-up stage. The verticality is measured using a level at 6 positions on each side wall (3 positions on the left and right sides, respectivel y), i.e. a total of 24 positions on the 4 side wal l s. The joint gaps are measured at 9 positions on each side wal l (3 positions on the left, center and right sides, respectively), I.e. a total 36 positions on the 4 side walls. To measure the joint gaps, crack tips are installed on the left and right sides of every joint gap, and vernier calipers are used. The measured verticality obtained through the mock-up test was found to be ±0.1° based on the initial stage (ST0), and the result of the joint gap was up to 0.38mm. This appears to have a negligible effect on the structure.

• Korean Journal of Heritage: History & Science
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• v.52 no.4
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• pp.56-77
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• 2019

Bi-Seok is a treasure trove of funeral rites and an important cultural asset that can shed light on the historical and social history of calligraphy, but research of the topic is still insignificant. In particular, research on the production method of Bi-Seok remains an unproven field. The production of Bi-Seok can be roughly divided into ma-jeong (refining stone), sculpture, and the Buk-chil (process of engraving letters) process. This article reveals some facts: First, performing ma-jeong to the Sang-Seok, Honyu-Seok, Bi-seok, which are known to be God's things. This process is needed because of the change in the perception of the Honyu-Seok due to the settlement and propagation of Confucian ceremonial rituals in the times of hardship in 1592 and 1636. As the crafting process of ma-jeong did not remain concrete, it was only possible to examine the manufacturing process of Bi-Seok through its materials and tools. Second, the rapid proliferation of Oh-Seok and Sa-jeo-chwi-yong (purchase of things made by private citizens) in the Yeongjo era has great importance in social and cultural history. When the Gang-Hwa-Seok of the commodity were exhausted, the Oh-Seok that was used by Sadebu (upper civil class) were used in the tomb of Jangneung, which made Oh-Seok popular among people. In particular, the use of Oh-Seok and the Ma-Jeong process could minimize chemical and physical damage. Third, the writing method of the Bi-seok is Buk-chil. After Buk-Chil of Song Si-Yeol was used on King Hyojong's tomb, the Buk-Chil process ( printing the letters on the back of the stone and rubbing them to make letters) became the most popular method in Korea and among other East Asian countries, and the fact that it was institutionalized to this scale was quite impressive. Buk-Chil became more sophisticated by using red ink rather than black ink due to the black color that results from Oh-Seok. Fourth, the writing method changes in the late Joseon Dynasty. Until the time of Yeongjo's regime, when inscribing, the depth of the angle was based on the thickness of the stroke, thus representing the shade. This technique, of course, did not occur at every Pyo-Seok or Shindobi, but was maintained by outstanding artisans belonging to government agencies. Therefore, in order to manufacture Bi-Seok, Suk-seok, YeonJeong, Ma-jeong, Jeong-Gan, ChodoSeoIp, Jung-Cho, Ip-gak, Gyo-Jeong, and Jang-Hwang, a process was needed to make one final product. Although all of these methods serve the same purpose of paying respects and propagandizing the great work of deceased persons, through this analysis, it was possible to see the whole process of Pyo-Seok based upon the division of techniques and the collaboration of the craftsmen.