• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1100-1109
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• 2022

Herein, a case study was conducted on the bilge pumping performance of a 24,000TEU class container ship with an overall length of 400m. Although the bilge system of the 24,000TEU class container ship was designed in accordance with the rule requirements of the Classification Society, the bilge system did not satisfy the 2 m/s requirements of SOLAS Reg.II-1/35-1 under the rated flow rate and maximum flow rate conditions of the bilge pump installed in the ship. In particular, assumptions were made that No.1 ~ No.4 cargo holds were flooded and filled entirely by sea water and the evaluation of bilge pumping performance had been performed for No.1 ~ No.4 cargo holds. According to the evaulation results of the, the mean water velocity at the main bilge pipe for No.2, No.3, and No.4 cargo holds did not meet the 2 m/s criterion. To resolve this problem, in this study, the branch bilge pipe in each cargo hold was changed from 150A to 200A and the mean water velocity at the main bilge pipe for No.2, No.3, and No.4 was calculated as 2.479m/s, 2.476m/s, and 2.459m/s, respectively.

• Journal of the Korea Institute of Building Construction
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• v.22 no.2
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• pp.161-169
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• 2022

The government [3] specifies steel pipe scaffolding as conventional scaffolding and is promoting the installation of system scaffolding, an integrated work platform, and avoidance of the use of steel pipe scaffolding as much as possible. However, in places where equipment cannot enter, such as power plants and plant sites, places the structure is complex, and places where scaffolding cannot be stacked on the ground, there is no choice but to install steel pipe scaffolding. When installing steel pipe scaffolding on an H-beam structure at a high place, the performance of the steel frame clamp is very important in order to form a work space which workers can work safely. In this study, the displacement magnitude and tensile load of members in each installation direction of the clamp for steel frame were verified through performance tests and structural analysis modeling. As a result, it was confirmed that the performance for each installation direction satisfies the safety certification standard tensile load of 10,000N. Although the performance value is satisfactory, deformation of the attachment pressing bolt was verified and was confirmed to have minimal deformation. Thus, to ensure the load is properly to the attachment body, the clamp for a steel frame must be installed in the direction in which the load is transmitted.

• Korean Journal of Construction Engineering and Management
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• v.23 no.3
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• pp.104-115
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• 2022

Safety accidents in the construction industry account for the highest percentage of all industries; and thus, it is encouraged to introduce a virtual reality (VR)-based experiential education system into the basic occupational safety and health training for construction as a way to solve the problem. However, there are some limitations such as a lack of competent workforce, and insufficient content and equipment for VR-based construction safety education. In this background, this study aimed to analyze the difference in learning effect between the CG-based experiential VR education (direct method, type B) and the existing photo-based audiovisual VR education (indirect method, type A), in which a CAMIL (Cognitive & Affective Model of Immersive Learning) theory was used as objective assessment tool. The learning effect of the direct education method (type B) was found to be superior to that of the indirect education method (type A) in terms of all areas in the CAMIL theory. It is expected that the VR-based experiential construction safety education will increase the learning effect of construction workers.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.357-364
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• 2023

Selective catalytic reduction (SCR) is the most effective method for reducing nitrogen oxide emissions, but the operating temperature range of V₂O₅-WO₃/TiO₂ catalysts is narrow (300~400℃). In this study, a new catalyst with an operating temperature range of 200~450℃ was developed. The catalyst poison, ammonium bisulfate, generated during the SCR process can be removed by heating above 350℃. To increase the number of active sites and promote the dispersion of active materials, titanium isopropoxide (TTIP) treatment was performed on the TiO₂ support with various TTIP/TiO₂ mass ratios. Among them, the 5 wt% TTIP loaded catalyst showed improved performance due to higher thermal stability caused by high W dispersion and the formation of V⁵⁺. In addition, the 5 wt% TTIP-loaded catalyst prepared by a one-step co-precipitation method showed greater V-OH and W-OH dispersion and enhanced interactions in contrast to conventional methods, resulting in higher catalytic activity at lower temperatures. This review article aims to provide an accessible explanation for researchers investigating how to improve the surface properties of TiO2 catalysts using TTIP.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.372-379
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• 2023

International oil prices are expected to increase from $85 a barrel this year to up to $100 a barrel in the second half of the year; this is likely to increase orders for offshore plants in the global market. One main characteristic of offshore plants is that a large helideck is located on the top side, and aluminum alloys are used as the basic material of the structure for weight reduction and corrosion resistance. Shipowners are increasing the size of helicopters to quickly evacuate lives in the event of an emergency, and the safety use load of devices that can stably secure helicopters to the deck is also required to increase. Owing to the nature of the aluminum material, the structural strength caused by welding is greatly reduced; therefore, the fixing device must be designed by embedding it in the deck and fixing it with bolts. In this study, a model applying aluminum alloy 6082-T6 was developed to develop a helicopter fastening device that can be used for large helidecks (diameter = 28 m). The developed item was verified through nonlinear structural strength calculation to satisfy the load used for the actual fastening condition. The load condition with a 45° showed a lower ultimate strength than the 90° case owing to local plastic collapse. The nonlinear structural collapse behavior showed a result similar to that of the experimental test. The main contents derived from this study are considered to be reference materials when evaluating the structural strength of similar aluminum equipment.

• Composites Research
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• v.37 no.2
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• pp.101-107
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• 2024

Demand for submarine cable is increasing due to advances in submarine power transmission technology and submarine cable manufacturing technology. Submarine cable use various types of protective equipment to prevent problems such as high maintenance costs in the event of cable damage and power outages during maintenance periods. Among them, flexible protection tube is a representative protective equipment to protect cables and respond to external forces such as waves and current. The flexible protection tube is made of polyurethane 85A hyperelastic material, so the calculation of mechanical behavior is carried out using mechanical properties based on experimental results. In this study, a study was conducted to determine the bending performance and tensile performance of flexible protection tube through analytical methods. The physical properties obtained through the multiaxial tensile test of polyurethane 85A were used for the analysis. Bending and tensile performance were determined for the maximum bending moment standard of 15 kN·m and the tensile load standard of 50 kN. As a result, it was confirmed that when the maximum bending moment of 15 kN·m of the flexible protection tube occurred, the bending performance of the MBR was secured at 13 m and when a tensile load of 50 kN, it was applied the maximum vertical displacement was 968 mm, confirming that the tensile performance was secured.

• Journal of Korean Elementary Science Education
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• v.43 no.3
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• pp.402-414
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• 2024

The purpose of this study is to explore the experiences of Science Chief Teachers in schools, focusing on the specific activities in which they engage during the school year as a part of the science curriculum in the school. To do so, five research participants were selected who were in charge of the activities of the Science Chief Teacher in elementary schools. After the interviews, their activities and roles were categorized into "planning and implementation" and "management and supplementation." In addition, the research participants were asked to bring documents they had drafted and provide information about accomplishments related to science contests, lists of materials and equipment used in science labs, and other materials to be used as reference data for the research. As prompted by the research, the category of "planning and implementation," which represented the activities conducted by the Science Chief Teachers, was further classified into "operation of the intramural events for the Month of Science at the beginning of the school year," "participation in contests sponsored by the Office of Education in accordance with the results of the intramural events," " the operation of the science club in school," and "preparation for the end of the year evaluation of the science education performance." As for the category of "management and supplementation," it was further classified into "constant management and improvement of the science lab," "maintenance of the relationship with the public service officials present at science lab," and "management of other matters related to the science education." Through this study, it was possible to look into the activities of the Science Chief Teachers who supported the smooth progress of science education in schools. This study will provide implications for improving the work efficiency of the Chief Science Teachers and indicate the difficulties expected in the future.

• Journal of Korean Society of Forest Science
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• v.106 no.4
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• pp.487-496
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• 2017

The marketization in North Korea is spreading rapidly. This study proposes forest rehabilitation strategy for North Korea in light of their major shift toward market economy. This current trend of marketization in North Korea is now affecting the forest sector, especially the way the residents utilize small forest land. For analyzing the influence of marketization on forest management in North Korea, we reviewed the official documents issued by North Korea and related materials of North Korean marketization. The government of Kim Jong Eun has set up policies and systems regarding the spread of marketization, such as guaranteeing individuals a right to dispose certain products on their own and establishing a special economic zone to attract foreign investments. In the forestry sector, the North Korean government has been trying to fully implement its forest restoration plan by carrying out measures like re-claiming of sloping lands that had been previously used by residents. However, as marketization progresses, it is expected that there lies much difficulty in government-led massive mobilization for forest restoration due to the increase of illegal logging to meet high demand for timber, illegal firewood harvesting, collecting non-timber products for livelihoods and illegal crop cultivation to sell in the market. Therefore, South Korea's support for forest restoration should also consider the recent marketization phenomenon in North Korea. It is necessary to formulate strategic measures such as conducting joint commercialization project on agroforestry management using cooperative farming unit, helping to improve income source from small forest lands, and to activate a comprehensive mountain village special economic zone by utilizing forest business. We do hope that our proposed forest rehabilitation strategy in this paper regarding the changes in North Korea's marketization and forest policy can give a meaningful suggestion on supporting forest restoration in North Korea in an effective way.

• Journal of Gifted/Talented Education
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• v.21 no.4
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• pp.993-1009
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• 2011

The purpose of this study was to find the effects of RSM-based astronomical observation program about Astronomical Spatial Concept and Self-Directed Learning for the Scientific Gifted Students. For this purpose, this research developed RSM-based astronomical observation program. This program was totally consisted 10 lessen. there was 3 part in this program. It contained Preparation Stage (step 1-2), Observation Stage (step 3-8), Clean up Stage (step 9-10). To find the effects of RSM-based astronomical observation program on Astronomical Spatial Concept and Self-Directed Learning for Scientific Gifted Students. 20 participants was selected. these students were attended at a scientific gifted class(5th grade) of an elementary school located in Ulsan. First, Astronomical Spatial Concept was used to find the effect of the Astronomical Observation program based RSM. And the results were analyzed by SPSSWIN 18.0. The results of this study were as follows. First, RSM-based astronomical observation program was a positive effects on Astronomical Spatial Concept of the Scientific Gifted Students (t=3,875, p=.001). Second, RSM-based astronomical observation program was a positive effects on Self-Directed Learning of the Scientific Gifted Students (t=5.783, p=.000). According to this research, RSM-based astronomical observation program was verified to improve Astronomical Spatial Concept and Self-Directed Learning on the Scientific Gifted Students. It will be contribute on the curriculum construction of the gifted school or gifted class.

• 대한공업교육학회지
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• v.32 no.1
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• pp.153-171
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• 2007

The purpose of this research was to investigate the degree of perceptional change of career education through overseas training of specialized high school teachers who take the leading role in applying Korean vocational education to reality. To accomplish this purpose, the following method were employed: 25 specialized department teachers of Keyngido educational institute who visited career education institute in USA and Canada were selected, and pretest and posttest were taken. Collected data were analyzed by Windows Korean version SPSS 14.0. M, SD, t-test and significant level p<.05 were employed for statistical analysis. The result of this research was as follows: There was significant difference in the degree of perceptional change of vocational education by overseas training of specialized high school teachers. But There was no significant differences in the management of vocational education curriculum(${\alpha}=.327$), reinforcement of preparatory training for technique contest(${\alpha}=.327$) in the statistical significant level(p<.05). The perception level of the trainees varied respectively in these domains. And means of posttest were relatively low in the comparison with those of pretest in the domains of visit of educational institute, educational facilities, scholarship and financial support, and reinforcement of preparatory training for technique contest. It is attributed to the Korea's uniqueness of culture, emotion, school system, educational facilities and financial support different from U.S.A. and Canada. The vocational education program of vocational education training institute in U.S.A. and Canada is mainly composed of industrial department, so there was no statistical significant difference(p<.05) in some questions taken by subjects of agricultural and commercial department. In conclusion, The overseas training program is very helpful for the perceptional change of vocational education and it is desirable to be expanded continuously.