• Economic and Environmental Geology
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• v.50 no.6
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• pp.497-508
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• 2017

This study was carried out to document and diagnose the conditions of the seated stone statue of Buddhist Master Seungga in Seunggasa temple immediately after its conservation treatment, which was found to be long covered in surface of white materials. The stone Halo was researched along with the Statue, and basic data was secured through precisely examination and nondestructive diagnosis. The result from the surface deterioration evaluation shows that both the Statue and Halo had a little bit of physical deterioration, although their level of chemical deterioration was proportionally higher due to discoloration. The physical property diagnosis using ultrasonic measurements on the Statue and Halo showed that the average ultrasonic velocity was found to be 3,570 m/s and 3,373 m/s, respectively, which corresponds to grade III, an indication of a favorable physical property. The surface covered materials were detected to be Ca, Ti, Pb, Fe, Al and Si, emanating from Hobun (Oster shell powder; $CaCO_3$) or lime ($CaO{\cdot}Ca(OH)_2$) and silicate minerals. Furthermore, Ti and Pb seems to be the component of the white coloring pigments, titanium white ($TiO_2$) and white lead ($2PbCO_2{\cdot}Pb(OH)_2$). Therefore, the seated stone statue of Buddhist Master Seungga is presumed to be painted with Hobun or lime and thereafter painted over with titanium white and white lead.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.162-167
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• 2015

Although the perfomance indicators of the nuclear power plants in Korea show optimal, it requires detailed analysis and discussion centered on the radiation dose. As analysis methods, analysis on the radiation dose of nuclear power plants over the past five years was assessed by comparing the relevant radiation dose of radiation workers and per capita average annual radiation dose of the world's major nuclear power stations was also analyzed. The radiation workers over the annual radiation dose limit of 50 mSv were not. The contrast ratio of the radiation exposure according to the reactor type was the normal operation of PHWR was 6.2% higher than those of the PWR. This shows the radiation work of PHWR during normal driving operation is much more than those of PWR. According to the Performance Indicators of the World Association of Nuclear Operator, the annual radiation dose per unit in 2013 showed 527 man-mSv of Korea is the best country among the major nuclear power generating states, the world average was 725 man-mSv. The annual per capita radiation dose is about 80% less than 1 mSv of the public dose limit and also the average per capita dose showed a very low level as 0.82 mSv. Workers in related organizations showed 1.07 mSv, the non-destructive inspection agency workers showed 3.87 mSv. The remarkable results were due to radiation reduced program such as development of radiation shielding and radiation protection. In conclusion, the radiation exposured dose of nuclear power plants workers in Korea showed a trend which is ideally reduced. But more are expected to be difficul and the psychological insecurity against the operation of the nuclear power plants is existed to the residents near the nuclear power plants. So the radiation dose reduction policy and radiation dose follow up study of nuclear power plants will be continously excuted.

• Journal of Conservation Science
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• v.31 no.1
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• pp.21-27
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• 2015

The Phoenix-shaped Glass Ewer, which is No. 193 National Treasure, was seriously damaged by a unique form of green glass pieces when excavated among a number of burial accessories of Hwangnamdaechong known to have been formed in the 5th century. While it has long been exhibited at the National Museum of Korea since its treatment for conservation treatment at conservation science laboratory in 1984, the existing adhesive materials seriously deteriorated for the 30 years, and the condition was quite unstable. The epoxy resin used as a restorative materials turned yellowing due to the light and heat so much that it was no longer able to exhibit it in a stable and effective manner. As a result, a re-treatment for conservation was conducted lately. This study focuses on the three pieces of Gold wires used to carefully wrap up the handle of the Phoenix-shaped Glass Ewer broken into three pieces, which has not been studied so far. As for the analysis method for Gold wires, SEM-EDS and Stereo Microscope were used for nondestructive analysis. First of all, the result of the SEM-EDS analysis shows that the composition was Au 91.9 wt.%-Au 92.8 w.t% and Ag 5.9 wt.%-Ag 6.5 wt.%, which indicates that it was an alloy made of Au and Ag. The production technique of Gold wires was also observed by means of optical microscopes. In general, Gold wires were manufactured by a drawing process in which a lump of gold was beaten or pulled out of a hole or by a process of twisting a gold plate. However, Gold wires separated from the handle of the Phoenix-shaped Glass Ewer did not involve any trace of twisting on the surface. Rather, fine vertical stripes were observed with the sections filled up. Hence, it is thought that this Ewer went through a drawing process and then was mended. As a result, no certain relation with the golden mending material used for the Phoenix-shaped Glass Ewer was verified. The findings above indicate that most of the existing researches on Gold wires recognized them, not as separate remains, but merely as a component of other golden remains. Thus, there has been little systematic study on the manufacturing techniques of Gold wires. The future study on Gold wires may verify the correlation between the Gold wires used to fix the handle of the Phoenix-shaped Glass Ewer, which is examined in this study, with that of golden remains in the Silla era.

• Korean Journal of Materials Research
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• v.10 no.9
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• pp.601-606
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• 2000

Nickel mono-silicide(NiSi) shows no increase of resistivity as the line width decreases below 0.15$\mu\textrm{m}$. Furthermore, thin silicide can be made easily and restrain the redistribution of dopants, because NiSi in created through the reaction of one nickel atom and one silicon atom. Therefore, we investigated the deposition condition of Ni films, heat treatment condition and basic properties of NiSi films which are expected to be employed for sub-0.15$\mu\textrm{m}$ class devices. The nickel silicide film was deposited on the Si wafer by using a dc-magnetron sputter, then annealed at the temperature range of $150~1000^{\circ}C$. Surface roughness of each specimen was measured by using a SPM (scanning probe microscope). Microstructure and qualitative composition analysis were executed by a TEM-EDS(transmission electron microscope-energy dispersive x-ray spectroscope). Electrical properties of the materials at each annealing temperature were measured by a four-point probe. As the results of our study, we may conclude that; 1. SPM can be employed as a non-destructive process to monitor NiSi/NiSi$_2$ transformation. 2. For annealing temperature over $800^{\circ}C$, oxygen pressure $Po_2$ should be kept below $1.5{\times}10^{-11}torr$ to avoid oxidation of residual Ni. 3. NiSi to $NiSi_2$ transformation temperature in our study was $700^{\circ}C$ from the four-point probe measurement.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.4
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• pp.12-18
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• 2008

Researches on particle physics have benefited our everyday life in many aspects. They have tested the safety of the objects we use everyday, conducted experiments to examine harmful environments to man, and treated diseases. Despite the usefulness of particle physics in a range of fields, however, it's difficult to conduct researches and experiments directly. But the advancements in the computer industry have allowed for experiments of particle physics in virtual simulations. One of the foremost simulation libraries for particle physics that have been researched actively these days, Geant4 has been put to diverse uses in particle physics. This study designed GUI so that physicists, who were not good at programming, could use a simulation library faster, more accurately, and more conveniently. It also developed the Geant4Editor, a simulation automation framework. The advantages of the Geant4Editor include automatic generations of essential classes in a simulation using Geant4 libraries and real-time reflection of user demands in a simulation. It also allows for efficient management of resources(user-created data) through the Data Manager.

• Journal of Radiation Protection and Research
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• v.23 no.3
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• pp.149-157
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• 1998

An analysis has been performed to estimate the additional number of workers and the additional collective dose in man-cSv which would be required, nuclear industry-wide as a result of reducing individual dose limit. This analysis can be extended to the reduction in the dose limits recommended by ICRP Publ.60 and BEIR V report as well as the proposed dose limits by regulatory authorities. An industry-wide database was employed in the analysis based on a summary of industry-wide occupational radiation exposure compiled by the Korea Radioisotope Association. Correlation model was employed to compute the affects of setting specific annual individual dose limits. In this study, we have addressed worker non-productivity while in the radiation environment on a parametric or 'sensitivity analysis' basis. This alleviates the need for developing such data underlying a summation of many individual tasks at many nuclear facilities. It has the advantage that very low non-productivity assumptions can readily be defended as conservative, in that it is difficult to approach such low worker non-productivity factors even in the best of environments in any industry. On a per facility basis, for calendar year 1997, the number of workers required would be increased from 231 workers to 269 workers and collective man-cSv dose would be also increased by approximately fourteen percent if the individual dose limit was reduced to 2 cSv/y and an individual worker non-productivity fraction of 0.1 is assumed.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.1-7
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• 2008

When historical or cultural buildings need to be repaired or reinforced, the changes of original features should be minimized, and the strengths of structures should be improved. Among the existing methods to reinforce historical wood structures, the carbon fiber reinforcement polymer (CFRP) installation method is one of the best ones to achieve the afore-mentioned requirements. Therefore, this study aims at investigating the reinforcing effects and failure modes of timber beams reinforced with the inserted CFRP, a part of roof trusses in modern wood structures, and at providing the fundamental test data to estimate the CFRP rein-forced timber beam in the application of this reinforcing method. The primary parameters in this study were the layout and amount of CFRP. It was observed that, when $0.3{\sim}0.7%$ of CFRP were installed, the strengths of reinforced timber beams increased up to 173% compared to its original strength, but their strengthening effects were heavily influenced by the characteristics of timber such as burls. In order to improve the applicability of this strengthening method, fundamental understandings on the characteristics of wood would be necessary, and there would be in need of researches on the non-destructive test for wood structures as well.

• Journal of the Korean Geophysical Society
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• v.4 no.1
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• pp.57-69
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• 2001

We have carried out a nondestructive close examination for the purpose of the structural safety diagnosis of the Three-Story Pagoda(Seokga Pagoda) in Bulkuk temple in the city of Kyungju, Kyungbuk, Korea. Ultrasonic wave velocities were measured at 456 points of the pagoda comprising 44 blocks to estimate the mechanical properties of rock blocks constituting the pagoda. The measured velocities have the range of 1217 to 4403 m/sec with the average of 3227 m/sec. The empirical relationship between the ultrasonic velocity and the uniaxial compressive strength yielded the estimation of strength of each block, ranging from 134 to 844 kg/cm^2 and averaging 463 kg/cm^2. With an assumption that the strength of each block is described as a random variables having a normal distribution, we calculated the probability of failure of rock blocks of the pagoda. Our investigation revealed that the probability of the structural failure due to the weight of higher blocks is very low. However, the probability of partial failure around contact area is substantial, which is consistent with the appearance that edges and the corners of some blocks were broken off. The platform under the body of the pagoda appeared to be structurally weak as the probability of tensile failure of the lower platform is up to 18%, and diagonal fractures are shown where the probability of failure is high.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.92-95
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• 2019

In this paper, a novel laser-based non-contact and non-destructive stress measurement technique is newly proposed for measuring stress in steel structural members. As the demand of stress monitoring in structural members is increased, various non-destructive techniques are being applied to the field of structural health monitoring. Spectroscopic techniques are non-contact technique and widely used for chemical identification of target materials. Especially, piezospectroscopic technique is a residual stress measurement technique in thermal barrier coatings. Although the piezospectroscopic technique has high possibility of measuring structural stress in steel members, the technique has been rarely applied to this field. In this paper, piezospectroscopy-based stress measurement technique is, therefore, proposed for measuring stress in steel structural member. To do that, alumina particles have been coated onto a specimen of a structural steel rod using a thermal spray coating technique. And then, an uniaxial compression test has been conducted to the specimen to collect each fluorescence spectrum under different loading conditions. Finally, the linear relation of spectral shift and applied compressive stress of the specimen has been experimentally established.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.10
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• pp.701-708
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• 2022

Since the propellant tank structure of the projectile is mainly subjected to a compressive force, there is a high risk of damage due to buckling. Large and lightweight structures such as propellant tank have a complex manufacturing process. So it requires a non-destructive test method to predict buckling load to use the structure after testing. Many studies have been conducted on Vibration Correlation Technique(VCT), which predicts buckling load using the relationship between compressive load and natural frequency, but it requires a large compressive load to predict the buckling load accurately, and it tends to decrease prediction accuracy with increasing internal pressure in structure. In this paper, we analyzed the causes of the decrease in prediction accuracy when internal pressure increases and proposed a method increasing prediction accuracy under the low compressive load for being usable after testing, through VCT combined testing and FEA result. The prediction value by the proposed method was very consistent with the measured actual buckling load.