• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.3
• /
• pp.1684-1691
• /
• 2015

For performance improvement and compactness, usage of enhanced tube is inevitable. However, studies on enhanced tubes for generator is very limited. In this study, pool boiling tests were conducted for 7 heat transfer tubes. Test range covered pressure 7.38~101.3 kPa and heat flux $20{\sim}40kW/m^2$. Results show that boiling heat transfer coefficient increases as pressure or heat flux increases. Under atmospheric condition, high heat transfer coefficients were obtained for notched fin and low fin tubes(225% and 202% of the 19.0 mm smooth tube, which yielded the lowest heat transfer coefficient). As pressure decreased, high heat transfer coefficients were obtained for a low fin tube(290% and 288% of the 19.0 mm smooth tube at 12.34 and 7.38 kPa).

• Journal of Korean Elementary Science Education
• /
• v.25 no.3
• /
• pp.331-337
• /
• 2006

This study examined the elementary school teachers' present utilization of science museums in teaching-learning and their perceptions of the educational programs in science museums. The results indicate that teachers have not utilized science museums as intimately as possible with formal instruction, therefore, the students' experiences of science museums are usually limited. The main reasons for lower than optimum usage of science museums in their teaching and learning is not because of its insignificant educational effects, but because of the lack of external and administrative support mechanisms. The elementary school teachers prefer to commit to programs in science museums such as science camps or experiment activities, and those exhibitions which have some kind of clear and discernable relation to the school curriculum. The results also indicate that most teachers want to participate in the various activities of science museums, such as developing and managing the programs or pre- and post activities for museum field trips, participating in the teachers' community in science museums, and so on.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.5
• /
• pp.49-58
• /
• 2003

Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance for electric cables. In this paper, stress and strain of flexible pipes with various installation depth are compared using traditional formula, FEM analysis, model soil box test and field test. from the findings of various analyses, considering the strain criteria-maximum 3.5%, it is suggested that flexible pipes can be buried at the depth of 80cm without additional soil improvement.

• International Journal of Highway Engineering
• /
• v.5 no.2 s.16
• /
• pp.25-35
• /
• 2003

During construction of circular lifeline pipe, the non-proper compaction along the pipe and the decrease of compaction efficiency are the main problems to induce the failure of underground pipe. The use of CLSM(controlled low strength materials) is one of the applications to overcome those problems. In this research, the numerical analysis by PENTAGON FEM program was carried out for 20 cases with the couple of combinations on bedding materials, backfill materials, and pipes. From the FEM analysis, the use of CLSM as backfill materials reduced the settlement of ground surface and the deformation of pipe employed. In case of the vertical deformation on the pipe, common soil backfill for flexible pipes showed 2 times for rigid pipes, but CLSM backfill case did less deformation than the soil backfill for rigid pipes. CLSM backfills for rigid pipes showed the similar results. Judging from the FEM analysis, the use of CLSM increases the structure capacity of the underground pipes.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.2 no.3
• /
• pp.18-24
• /
• 2011

In this paper, we present the load-deflection behavior of GRP pipes. GRP buried pipes are widely used in construction in the advantage of their superior mechanical and physical characteristics such as high chemical resistance, high corrosion resistance, right weight, smooth surface of the pipe, and cost effectiveness from soil-structure interaction. To design flexible pipes to be buried underground, it should be based on the ASTM D2412(2010). When applying ASTM D 2412(2010) to the design, pipe stiffness(PS) must be predetermined by the parallel-plate test which requires tedious and laborious working process. To overcome such problems, the finite element simulations for finding the load-deflection behavior of the GRP flexible pipes is installed at UTM testing machine. In the finite element simulations, basic data, such as the modulus of elasticity of the material and cross-sectional dimension, is used. From the investigation, we found that the difference between experimental result and analytical prediction is less than 15% when the pipe deflected 3% and 5% of its vertical diameter although the pipe material is not uniform across the cross-section.

• Journal of Information Management
• /
• v.40 no.3
• /
• pp.151-176
• /
• 2009

The purpose of this study is to propose effective management plan for official seal guaranteeing authenticity of archival records. For this, this paper attempts to investigate current management conditions of central governments and National Archives. First, disclosure of information on official seal register in central government was requested. In addition, surveys and interviews with person in charge were carried out. Additionally, official seal lists of National Archives were analyzed and the person in charge was interviewed. Based on these, this paper proposed management plans of official seal such as a periodic inspection of management conditions, training programs for the person in charge, selective acquisition, reporting of the current state, improvement of law system, improvement of document formats, and establishment of an electronic seal management system, etc.

• Nuclear Engineering and Technology
• /
• v.27 no.2
• /
• pp.226-233
• /
• 1995

The wall thickness of a pressure tube is increased in order to reduce the probability of failure in a pressure tube of CANDU type reactor. It is presented here that the variation of wall thickness changes stress, hydrogen concentration and delayed hydride cracking in Zr-2.5Nb pressure tube. When the wall thickness is increased from 4.2 mm to 5.2 mm, the stress exerted on the tube and the deuterium taken up during operation are reduced by 19％. Further, the calculated allowable depth of the surface flaw over which delayed hydride cracking(DHC) is susceptible increases by 50％. DHC initiation is controlled by the stress and by the hydrogen concentration in the pressure tube. The results are therefore very significant in such a respect that increased wall thickness may reduce DHC initiation. Ac the wall thickness increases the hydrostatic tension will increase. Its impact on the acceleration of the crack growth rate of DHC deserves further studies.

• The Korean Journal of Archival Studies
• /
• no.59
• /
• pp.321-353
• /
• 2019

As the function and role of the Record Center that manage the processing department, which is the producer of records, are very passive and limited, there are growing demands for expansion of work and organization along with change in this. In order to strengthen the function and role of the Record Center, it is necessary to enrich the substance through identification of the value of preservation and utilization of records under the Record Center, development of various tasks, and the construction of independent Record Center, etc. in addition to complementing institutional devices. In this paper, we examine the construction background and process, the remaining tasks of Record Center in Ministry of Justice, and intend to find out what matters and procedures the central administrative agency should consider when establishing the Record Center based on relevant case study.

• Journal of Creative Information Culture
• /
• v.6 no.3
• /
• pp.107-128
• /
• 2020

In this study, the present state and characteristics of VR exhibits currently exhibited in Korea, Hong Kong, and Japan were studied to derive the improvements in the domestic VR exhibits. The previous literatures on VR exhibits at Science Museum were reviewed and online and offline data were collected, analyzed and compared. As the result of the study, VR exhibits at Science Museum in Korea turned out to focus on interest and fun rather than containing scientific content, and exhibits aimed at recreational play and physical activity. The Hong Kong Science Museum VR exhibits are more physically targeted exhibits than the cognitive target exhibits. In addition, at the Japanese Science Museum, there are many exhibits aimed at the physical target exhibits. As the result of classifying VR exhibits into the similar types, it was possible to derive them into four characteristics. The implications for future KOREA VR museum exhibitions were discussed.

• Journal of Korean Society of Archives and Records Management
• /
• v.21 no.4
• /
• pp.223-242
• /
• 2021

This study aims to find complex service plans for individual presidential archives. It analyzes previous studies dealing with the justification, cases, and services of individual presidential archives. The characteristics, functions, and service aspects of individual presidential archives are theoretically discussed. As a case study, the services of individual presidential archives in the United States are analyzed, and the study finds the complex nature of the services. Furthermore, interviews with archival experts are conducted on the subject of the current status of the presidential archives, experience in use, and improvement measures to discuss the problems and limitations of the current integrated presidential archives services and diagnose the prospects of individual presidential archives. In conclusion, it proposes the individual presidential archives service strategies in four areas, namely, information service, research support service, exhibition service, and outreach service.