• Korean Journal of Agricultural Science
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• v.31 no.2
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• pp.105-114
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• 2004

This study was performed to examine the physical and mechanical properties of eco-concrete using soil, natural coarse aggregate, soil compound and polypropylen fiber. The mass loss ratio was decreased with increasing the content of coarse aggregate and soil compound. The compressive strength, flexural strength, ultrasonic pulse velocity and dynamic modulus of elasticity were increased with increasing the content of coarse aggregate, soil compound and polypropylene fiber. The compressive and flexural strengths were showed in 8.07 MPa and 2.641 MPa at the curing age 28 days, respectively. The coefficient of permeability was decreased with increasing the content of coarse aggregate and soil compound, but it was increased with increasing the content of polypropylene fiber. The lowest coefficent of permeability was showed in $5.066{\times}10^{-9}cm/s$.

• Korean Journal of Agricultural Science
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• v.26 no.1
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• pp.65-70
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• 1999

This study is performed to evaluate the engineering properties of rice-straw ash concrete using normal portland cement, natural aggregates and rice-straw ash. The following conclusion are drawn; 1. The dynamic modulus of elasticity is in the range of $289{\times}10^3{\sim}345{\times}10^3kgf/cm^2$, which is showed about the same compared to that of the normal cement concrete. The highest dynamic modulus is showed by 5% rice-straw ash filled rice-straw ash concrete 2. The static modulus of elasticity is in the range of $268{\times}10^3{\sim}335{\times}10^3kgf/cm^2$, which is showed about the same compared to that of the normal cement concrete. The dynamic modulus is increased approximately 3~10% than that of the static modulus. 3. The poisson's number of rice-straw ash concrete is less than that of the normal cement concrete. 4. Accordingly, if we use suitable quantity of rice-straw ash as a replacement of cement, it will greatly improve engineering properties of concrete.

• International Journal of Highway Engineering
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• v.4 no.2 s.12
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• pp.1-8
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• 2002

Latex modified concrete(LMC) became to be applied as a new material for newly constructed bridge deck overlays in Korea due to its excellent bond strength, flexural strength and impermeability against water and chloride. However, it could not be adopted at repair job site because of its long curing time required. Thus, a research on latex modified concrete with rapid-setting cement(RSLMC) is necessary if it could develope the sufficient strength for early opening to traffic. This study focused on the durability of latex modified concrete with rapid-setting cement mainly on water permeable resistance and freeze-thaw resistance. The main experimental variables were latex contents(0, 5, 10, 15 and 20%) and antifoamer contents (0, 1.6, 3.2, 4.8 and 6.4%). Test results show that the permeability of RSLMC is very low indicating below 100 coulombs at 15% of latex contents at all antifoamer contents. The freeze-thaw resistance of RSLMC maintains above 90% of relative dynamic modulus at 3.2% of antifoamer content until 300 freezing-thawing cycles.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.60-71
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• 2024

The present study aims to investigate the level difference of floor impact noises of composite floor structure using EVA resilient materials. In order to this, four different types of resilient materials were designed combining PET, PP sheet and EVA mount including Flat type, Deck type, Cavity type and Mount type. Totally 9 different samples were made for acoustic measurements which were carried out twice with bang-machine and impact ball as the heavy-weight floor impact noise sources. All the floor impact noise measurements were undertaken at the authentication institution. As a result, concerning Flat and Cavity types, it was found that 2 dB ~ 5 dB of heavy-weight floor impact noise was reduced supplementally when PET was added, while floor impact noise larger than 50 dB was acquired when single resilient material was used. Especially, most high performance was obtained for Mount type with 1st grade of light-weight floor impact noise and 2nd grade of heavy-weight floor impact noise. This is because of material property with low dense PET sound absorption materials which fill all around EVA mounts. Also, it was considered that this results are due to the sound impact absorption by the both EVA mounts and the air cavity between EVA mount and PP sheet. Also, it was found that at least 36 EVA mounts per 1m2 area of resilient panel make more noise reduction of heavy-weight floor impact noises.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.4
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• pp.1-17
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• 2024

This study analyzed the behaviors and satisfaction of park users in nine parks representing first and second-generation new towns, aiming to propose directions for planning new town parks. According to the analysis, park users in new towns mainly visit parks for purposes such as relaxation, strolling, and exercise, often with family, alone, or with friends. They typically spend 1-2 hours in the park and mostly access it on foot. Additionally, satisfaction with park accessibility is high, particularly among pedestrians. Satisfaction survey results indicate that pedestrian pathways, trees and vegetation, water features, rest areas, and cultural facilities have the greatest impact on overall park satisfaction. Playgrounds and sports facilities show relatively lower satisfaction levels, indicating a need for improvement. Furthermore, according to NPS analysis, park users are highly willing to recommend parks, especially with Gwanggyo Lake Park and Dongtan Central Park receiving high recommendation scores. IPA analysis shows that pathways and vegetation are perceived as highly important and satisfactory, while playgrounds and sports facilities are categorized as areas needing improvement. Thus, there is a need to consider improvement strategies for each. Additionally, identifying park users' grievances can lead to creating a better park environment. Finally, concerning the planning direction for new town parks, linear-shaped parks facilitating walking are preferred, with parks preserving natural terrain and forests deemed the most desirable. Based on these results, future city parks, including those in the third-generation new towns, should harmonize with nature and prioritize pedestrian access.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.6
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• pp.138-149
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• 2015

In order to search for the reasonable planning directions for representing traditional landscape, this study conducted the comparative analysis of the designs on the panels and their constructions from both winners of "The Landscape Design Competitions for City Infrastructure of Minlak(2) District in Uijeongbu" and "The Design Competition for Dongtan(2) District Land Development Phase 1". The representing targets and views, the composition and placement of representing space, the design of representing facilities and landscape planting were examined based on the text, master plans, elevations and cross sections, diagrams, images, and perspective drawings proposed from the competition panels. Then, the landscape constructions were reviewed. The results are as follows: First, the types of the representing targets and views are the agricultural landscape, as the local landscape of target area, which are divided into the life space of a traditional village, the traditional water space, and the traditional culture. Second, as to the composition and placement of representing space, the traditional theme spaces are formulated considering the surrounding land use and the local cultural heritage. However, some spaces were changed to the exercise space or convenient facility spaces required in a neighborhood park. Third, in the case of the representing facilities, a round island in the square pond, a traditional pavilion and Hwagye(terraced flower bed) were made without the facilities designed creatively. Fourth, the application of traditional planting techniques was focused on planting trees in the village forest on an island in the square pond and on Hwagye. Fifth, the traditional representing work has gradually advanced with the selection of subject and experimental facility designs based on the professional references. Sixth, the choice of the realizable subject, the expertise for information analysis and the creative design of the traditional facility are required in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5673-5682
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• 2015

Purpose of this study is to examine and investigate the utilization of low-rise floor Pilotis space which is frequently selected as a major planning element in recent high-rise apartment complex and to identify the interrelationship between the placement of Pilotis space in the complex and space utilization frequency by comparing circulation related indicators of Connectivity, Control Value, Global Integration and Local Integration through Space Syntax axial analysis. Conclusions of this study are, first, Pilotis space is not used as a space to improve regional community consciousness because it is mostly used as a 'simple movement space'. Second, regarding space utilization frequency differences in Pilotis space in each apartment building, projecting entry access+pilotis addition type complex shows more significant utilization frequency than pilotis access type complex, and the vandalism phenomenon is observed more often. Third, Pilotis space utilization is related with Connectivity, Control Value, Global Integration and Local Integration which are circulation related indicators in Space Syntax, and Pilotis spaces with high indicator values over 2 tend to show higher utilization frequency and those with low indicator values over 2 tend to show low utilization frequency.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.3
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• pp.89-102
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• 2024

This study aims to examine the characteristics of the user experience of New Town neighborhood parks and explore issues that diversify the experience of the parks. In order to quantitatively analyze a large amount of park visitors' experiences, text-based Naver blog reviews were collected and analyzed. Among the Phase 1 and 2 New Towns, the parks with the highest user experience postings were selected for each city as the target of analysis. Blog text data was collected from May 20, 2003, to May 31, 2022, and analysis was conducted targeting Ilsan Lake Park, Bundang Yuldong Park, Gwanggyo Lake Park, and Dongtan Lake Park. The findings revealed that all four parks were used for everyday relaxation and recreation. Second, the analysis underscores park's diverse user groups. Third, the programs for parks nearby were also related to park usage. Fourth, the words within the top 20 rankings represented distinctive park elements or content/programs specific to each park. Lastly, the results of the network analysis delineated four overarching types of park users and the networks of four park user types appeared differently depending on the park. This study provides two implications. First, in addition to the naturalistic characteristics, the differentiation of each park's unique facilities and programs greatly improves public awareness and enriches the individual park experience. Second, if analysis of the context surrounding the park based on spatial information is performed in addition to text analysis, the accuracy of interpretation of text data analysis results could be improved. The results of this study can be used in the planning and designing of parks and greenspaces in the Phase 3 New Towns currently in progress.

• Journal of the Korean Wood Science and Technology
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• v.27 no.2
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• pp.15-22
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• 1999

Polymeric meterials that are used for noise and vibration damper in wood/polymer/wood sandwich composites, must have a high loss factor(tan ${\delta}$), and at the same time the storage modulus(E) of $5{\times}10^7$ to $10^9$ dyne/$cm^2$ must withstand over a wide temperature and frequency ranges. In this study, the series of epoxy resinlpolyacrylate interpenetrating polymer networks(IPNs) were synthesized by simultaneous polymerization. Their dynamic tensile properties were measured at 110Hz using Rheovibron instrument. Composite damping factor(tan ${\delta}_c$) and dynamic bending modulus($E_c,\;E_^{\prime\prime}c$) of wood/polymer/wood sandwich composites were measured at 110Hz using a Rheovibron in bending mode of vibration. These dynamic tensile studies indicated that cured epoxy resin/polyacrylates IPNs were semicompatible in the sense that both the shifting of T($E^{\prime\prime}_{max}$) or T(tan ${\delta}_{max}$) and the broadening of glass transition temperature range were observed. Especially, the cured Epikote871/P(n-BMA) IPNs of composition 70/30 to 50/50 showed a relatively high tan a and appropriate E' value over a wide temperature range; consequently the tan a e curves of wood/IPNs/wood sandwich composites was broadened over a wide temperature range.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.419-429
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• 2003

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies of thick, hyperboloidal shells of revolution. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u/sub r/, u/sub θ/, u/sub z/ in the radial, circumferential, and axial directions, respectively, we taken to be sinusoidal in time, periodic in θ, and algebraic polynomials in the r and z directions. Potential(strain) and kinetic energies of the hyperboloidal shells are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four digit exactitude is demonstrated for the first five frequencies of the hyperboloidal shells of revolution. Numerical results are tabulated for eighteen configurations of completely free hyperboloidal shells of revolution having two different shell thickness ratios, three variant axis ratios, and three types of shell height ratios. Poisson's ratio (ν) is fixed at 0.3. Comparisons we made among the frequencies for these hyperboloidal shells and ones which ate cylindrical or nearly cylindrical( small meridional curvature. ) The method is applicable to thin hyperboloidal shells, as well as thick and very thick ones.