• International Journal of Concrete Structures and Materials
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• v.7 no.3
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• pp.183-191
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• 2013

Prestress losses assumed for bridge girder design and deflection analyses are dependent on the concrete modulus of elasticity (MOE). Most design specifications, such as the American Association of State Highways and Transportation Officials (AASHTO) bridge specifications, contain a constant value for the MOE based on the unit weight of concrete and the concrete compressive strength at 28 days. It has been shown in the past that that the concrete MOE varies with the age of concrete. The purpose of this study was to evaluate the effect of a time-dependent and variable MOE on the prestress losses assumed for bridge girder design. For this purpose, three different variable MOE models from the literature were investigated: Dischinger (Der Bauingenieur 47/48(20):563-572, 1939a; Der Bauingenieur 5/6(20):53-63, 1939b; Der Bauingenieur, 21/22(20):286-437, 1939c), American Concrete Institute (ACI) 209 (Tech. Rep. ACI 209R-92, 1992) and CEB-FIP (CEB-FIP Model Code, 2010). A typical bridge layout for the Dallas, Texas, USA, area was assumed herein. A prestressed concrete beam design and analysis program from the Texas Department of Transportation (TxDOT) was utilized to determine the prestress losses. The values of the time dependent MOE and also specific prestress losses from each model were compared. The MOE predictions based on the ACI and the CEB-FIP models were close to each other; in long-term, they approach the constant AASHTO value. Dischinger's model provides for higher MOE values. The elastic shortening and the long term losses from the variable MOE models are lower than that using a constant MOE up to deck casting time. In long term, the variable MOE-based losses approach that from the constant MOE predictions. The Dischinger model would result in more conservative girder design while the ACI and the CEB-FIP models would result in designs more consistent with the AASHTO approach.

• Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.103-115
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• 2014

The engineering design process is a creative process, and the designers must repeatedly apply Undo/Redo operations to modify CAD models to explore new solutions. Undo/Redo has become one of most important functions in interactive graphics and CAD systems. Undo/Redo in a collaborative CAD system is also very helpful for collaborative awareness among a group of cooperative designers to eliminate misunderstanding and to recover from design error. However, Undo/Redo in a collaborative CAD system is much more complicated. This is because a single erroneous operation is propagated to other remote sites, and operations are interleaved at different sites. This paper presents a multi-user selective Undo/Redo approach in full distributed collaborative CAD systems. We use site ID and State Vectors to locate the Undo/Redo target at each site. By analyzing the composition of the complex CAD model, a tree-like structure called Feature Combination Hierarchy is presented to describe the decomposition of a CAD model. Based on this structure, the dependency relationship among features is clarified. B-Rep re-evaluation is simplified with the assistance of the Feature Combination Hierarchy. It can be proven that the proposed Undo/Redo approach satisfies the intention preservation and consistency maintenance correctness criteria for collaborative systems.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.80-84
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• 2008

We constructed the null mutants of fission yeast Schizosaccharomyces pombe spDbp5 gene that is homologous to DEAD-box RNA helicase DBP5 in budding yeast Saccharomyces cerevisiae, which plays important roles in mRNA export out of nucleus. A null mutant in an $h^+/h^+$ diploid strain was constructed by replacing the spDbp5-coding region with an $ura4^+$ gene using one-step gene disruption method. Tetrad analysis showed that the spDbp5 is essential for vegetative growth. The haploid spDbp5 null mutants harboring pREP81X-spDbp5 plasmid showed extensive $poly(A)^+$ RNA accumulation in the nucleus and decrease in the cytoplasm after repression of spDbp5 expression. These results suggest that spDbp5 is also involved in mRNA export from the nucleus.

• The Korean Journal of Archival Studies
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• no.68
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• pp.243-279
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• 2021

Rep. Roh Hoe-chan is a representative politician in Korean progressive politics. From the labor movement to the workers' political organization movement, they devoted themselves to the movement to build a progressive party. As a member of the 17th, 19th, and 20th National Assembly, he carried out legislative activities. The record he left is the record of the political power of workers, the record of the progressive party, and the record of a politician who suffers and practices. Also, as the son of a displaced person, as a student activist suffering from the restoration period, it is also a record of a human being of cultural literacy who played the cello. Archivist's basic research is expected to play a role in creating a virtuous cycle of archive management by structuring the archive and presenting various access points to various users, allowing more diverse research and use in the future.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.273-284
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• 2018

Purpose: Conventional headland turning typically requires repeated forward and backward movements to move the farming equipment to the next row. This research focuses on developing an upland agricultural robot with an optimized headland turning mechanism that enables a $180^{\circ}$ turning positioning to the next row in one steering motion designed for a two-wheel steering, four-wheel drive agricultural robot named the HADA-bot. The proposed steering mechanism allows for faster turnings at each headland compared to those of the conventional steering system. Methods: The HADA-bot was designed with 1.7-m wide wheel tracks to travel along the furrows of a garlic bed, and a look-ahead path following algorithm was applied using a real-time kinematic global positioning system signal. Pivot turning tests focused primarily on accuracy regarding the turning radius for the next path matching, saving headland turning time, area, and effort. Results: Several test cases were performed by evaluating right and left turns on two different surfaces: concrete and soil, at three speeds: 1, 2, and 3 km/h. From the left and right side pivot turning results, the percentage of lateral deviation is within the acceptable range of 10% even on the soil surface. This U-turn scheme reduces 67% and 54% of the headland turning time, and 36% and 32% of the required headland area compared to a 50 hp tractor (ISEKI, TA5240, Ehime, Japan) and a riding-type cultivator (CFM-1200, Asia Technology, Deagu, Rep. Korea), respectively. Conclusion: The pivot turning trajectory on both soil and concrete surfaces achieved similar results within the typical operating speed range. Overall, these results prove that the pivot turning mechanism is suitable for improving conventional headland turning by reducing both turning radius and turning time.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.211-220
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• 2021

Low-pressure sodium lamps, high-pressure sodium lamps, and fluorescent lamps are mainly used for tunnel lighting in Rep. of Korea, which accounts for the highest percentage in the tunnel maintenance costs. Therefore, tunnel lights are being replaced by LED lamp that have advantages with respect to low power consumption and sustainability. To analyze the effect of replacement high pressure sodium lamp with LED lamp, illumination and monthly power usage per year have been investigated for 10 tunnels. The usage of LED lamp results in illumination improvement from 27.9% to 490% and power saving around average 47.1%.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.187-194
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• 2022

This study is to encourage physical activity and exercise in people with spinal cord disabilities so that they can have a positive effect on health outcomes. Current evidence shows that IT-based muscle strength and muscle endurance, cardiopulmonary exercise, electrical stimulation exercise, and robot exercise can all improve physical components, reduce the risk of secondary health complications, and have a positive impact on the overall health of people with chronic physical disabilities. To improve muscle strength and muscle endurance, exercise frequency should be conducted twice and three sets a week, <5 Reps to improve muscle strength, general strength should be repeated 6 to 15 times, and 15 to 30 times to improve muscle endurance. In order to improve cardiopulmonary ability, it should be conducted 3-5 times a week, 20-60 minutes, and 50-80% of the maximum heart rate. Therefore, higher resource investment is needed to realize various IT-based exercise benefits and access professional equipment, facilities and trainers.

• Composites Research
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• v.19 no.5
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• pp.12-19
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• 2006

In this paper, conceptual structural design of the main wing for a small scale WIG(Wing in Ground Effect) among high speed ship projects, which will be a high speed maritime transportation system for the next generation in Rep. of Korea, was performed. The Carbon/Epoxy material was selected for the major structure, and the skin-spar with a foam sandwich structural type was adopted for improvement of lightness and structural stability. As a design procedure for the present study, firstly the design load was estimated through the critical flight load case study, and then flanges of the front and rear spars from major bending loads and the skin and the spar webs from shear loads were preliminarily sized using the netting rule and the rule of mixture. Stress analysis was performed by a commercial FEA code, NASTRAN. From the stress analysis results for the first designed wing structure, it was confirmed that the upper skin between the front spar and the rear spar was unstable fer the buckling. Therefore in order to solve this problem, a middle spar and the foam sandwich type structure at the skin and the web were added. After design modification, the structural safety and stability for the final design feature was confirmed. In addition to this, the insert bolt type structure with eight high strength bolts to fix the wing structure to the fuselage was adopted for easy assembly and removal as well as in consideration of more than 20 years fatigue life.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.2
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• pp.185-196
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• 2020

Low-pressure sodium lamps, high-pressure sodium lamps and fluorescent lamps etc are mainly used tunnel lighting in Rep. of Korea. Power rates for tunnel lighting are known to account for the highest percentage in the tunnel maintenance costs. Therefore, tunnel lights are being replaced by LED that have advantages such as low power consumption and longevity. To analysis effect of replacement low pressure sodium lamp with LED, illumination and monthly power usage for a year are investigated for 8 tunnels. Power usage for tunnel lighting is decreased by 26.1% to 59.6%, and illumination is increased by 34.1% to 293% replacing low pressure sodium lamp with LED.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.2 s.40
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• pp.3-14
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• 2007

This study proposes an automatic method to generate 3D building models using a draft map, which is an intermediate product generated during the map generation process based on aerial photos. The proposed method is to generate a terrain model, roof models, and wall models sequentially from the limited 3D information extracted from an existing draft map. Based on the planar fitting error of the roof corner points, the roof model is generated as a single planar facet or a multiple planar structure. The first type is derived using a robust estimation method while the second type is constructed through segmentation and merging based on a triangular irregular network. Each edge of this roof model is then projected to the terrain model to create a wall facet. The experimental results from its application to real data indicates that the building models of various shapes in wide areas are successfully generated. The proposed method is evaluated to be an cost and time effective method since it utilizes the existing data.