• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.172-178
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• 2021

In the ship repair market, interest in maintenance and repair is steadily increasing due to the reinforcement of prevention of environmental pollution caused by ships and the reinforcement of safety standards for ship structures. By reflecting this effect, the number of requests for repairs by foreign shipping companies increases to repair shipbuilders in the Southwest Sea. However, because most of the repair shipbuilders in the southwestern area are small and medium-sized companies, it is difficult to lead to the integrated synergy effect of the repair shipbuilding companies. Moreover, the infrastructure is not integrated; hence, using the infrastructure jointly is a challenge, which acts as an obstacle to the activation of the repair shipbuilding industry. Floating docks are indispensable to operating the repair shipbuilding business; in addition, most of them are operated through renovation/repair after importing aging caisson docks from overseas. However, their service life is more than 30 years; additionally, there is no structure inspection standard. Therefore, it is vulnerable to the safety field. In this study, the finite element analysis program of ANSYS was used to evaluate the structural safety of the modified caisson dock and obtain additional structural reinforcement schemes to solve the derived problems. For the floating docks, there are classification regulations; however, concerning structural strength, the regulations are insufficient, and the applicability is inferior. These insufficient evaluation areas were supplemented through a detailed structural FE-analysis. The reinforcement plan was decided by reinforcing the pontoon deck and reinforcement of the side tank, considering the characteristics of the repair shipyard condition. The final plan was selected to reinforce the side wing tank through the structural analysis of the decision; in addition, the actual structure was fabricated to reflect the reinforcement plan. Our results can be used as reference data for improving the structural strength of similar facilities; we believe that the optimal solution can be found quickly if this method is used during renovation/repair.

• Journal of Radiation Protection and Research
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• v.41 no.1
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• pp.31-39
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• 2016

Background: It is necessary to consider the overall countermeasure for analysis of nuclear activities according to the increase of the nuclear facilities like nuclear power and reprocessing plants in the neighboring countries including China, Taiwan, North Korea, Japan and South Korea. South Korea and comprehensive nuclear-test-ban treaty organization (CTBTO) are now operating the monitoring instruments to detect radionuclides released into the air. It is important to estimate the origin of radionuclides measured using the detection technology as well as the monitoring analysis in aspects of investigation and security of the nuclear activities in neighboring countries. Materials and methods: A three-dimensional forward/backward trajectory model has been developed to estimate the origin of radionuclides for a covert nuclear activity. The developed trajectory model was composed of forward and backward modules to track the particle positions using finite difference method. Results and discussion: A three-dimensional trajectory model was validated using the measured data at Chernobyl accident. The calculated results showed a good agreement by using the high concentration measurements and the locations where was near a release point. The three-dimensional trajectory model had some uncertainty according to the release time, release height and time interval of the trajectory at each release points. An atmospheric dispersion model called long-range accident dose assessment system (LADAS), based on the fields of regards (FOR) technique, was applied to reduce the uncertainties of the trajectory model and to improve the detective technology for estimating the radioisotopes emission area. Conclusion: The detective technology developed in this study can evaluate in release area and origin for covert nuclear activities based on measured radioisotopes at monitoring stations, and it might play critical tool to improve the ability of the nuclear safety field.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.133-149
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• 1997

In the metapelites around the Ogcheon granite, the metamorphic grade increases from the biotite zone through the andalusite zone to the sillimanite zone towards the intrusion contact. In the metabasites around the Boeun granite, the metamorphic grade increases from transitional zone between the greenchist and amphibolite facies through the amphibolite facies to the upper amphibolite facies towards the intrusion contact. In the Doiri area locating near the intrusion contact of the Boeun granite, sillimanite- and andalusite-bearing metapelites are found with in 500 m away from the contact. The evidence described above indicates that the Ogcheon and Boeun granites caused low-P/T type contact metamorphism to the country rocks. The P-T condition of contact metamorphism due to the intrusion of the Ogcheon granite is $540{\pm}40^{circ}C, 2.8{\pm}0.9$ kb. The temperature condition of contact metamorphism due to the intrusion of the Boeun granite is $698{\pm}28^{\circ}C$. The wide compositional range of amphibole and plagioclase in the metabasites around the Boeun granite is due to the immisibility gab of amphibole and plagioclase and unstable relict composition resulted from an incomplete metamorphic reaction. The compositional range of stable amphibole and plagioclase decreases as a metamorphic grade increases due to a close of immiscibility gab. The thermal effect of contact metamorphism due to the intrusion of the Ogcheon and Boeun granites, are calculated using the CONTACT2 program based on a two dimensional finite difference method. In order to estimate the thermal effect of an introduced pluton, a circle with 10 km diameter and a triangle with 20 km side are used for the intrusion geometries of the Ogcheon granite and the Boeun granite, respectively. The results from the field and modeling studies suggest that the intrusion temperatures of the Ogcheon granite close to $800^{\circ}C$ and the intrusion temperature of the Boeun granite is higher than $1000^{\circ}C$. However, the intrusion temperatures can be lower than the suggested temperature, if the geothermal gradient prior to the intrusion of the Ogcheon and Boeun granites was higher than the normal continental grothermal gradient.