• Steel and Composite Structures
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• 제37권1호
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• pp.99-115
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• 2020

This article deals with the dynamic analysis in pad concrete foundation containing Silica nanoparticles (SiO₂) subject to seismic load. In order to control the foundation smartly, a piezoelectric layer covered the foundation. The weight of the building by a column on the foundation is assumed with an external force in the middle of the structure. The foundation is located in soil medium which is modeled by spring elements. The Mori-Tanaka law is utilized for calculating the equivalent mechanical characteristics of the concrete foundation. The Kevin-Voigt model is adopted to take into account the structural damping. The concrete structure is modeled by a thick plate and the governing equations are deduced using Hamilton's principle under the assumption of higher-order shear deformation theory (HSDT). The differential quadrature method (DQM) and the Newmark method are applied to obtain the seismic response. The effects of the applied voltage to the smart layer, agglomeration and volume percent of SiO₂ nanoparticles, damping of the structure, geometrical parameters and soil medium of the structure are assessed on the dynamic response. It has been demonstrated by the numerical results that by applying a negative voltage, the dynamic deflection is reduced significantly. Moreover, silica nanoparticles reduce the dynamic deflection of the concrete foundation.

• Steel and Composite Structures
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• 제37권2호
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• pp.253-258
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• 2020

Vibration response in a sandwich plate with a nanocompiste core covered by magnetic layer is presented. The core is armed by functionalyy graded-carbon nanotubes (FG-CNTs) where the Mori-Tanaka law is utilized assuming agglomeration effects. The structure plate is located on elastic medium simulated by Pasternak model. The governing equations are derived based on Mindlin theory and Hamilton's principle. Utilizing diffrential quadrature method (DQM), the frequency of the structure is calculated and the effects of magnetic layer, volume percent and agglomeration of CNTs, elastic medium and geometrical parameters of structure are shown on the frequency of system. Results indicate that with considering magnetic layer, the frequency of structure is increased.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.789-792
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• 1999

Reinforced concrete structures covered creek for road vehicle located in urban areas have been experiencing corrosion of concrete and reinforcing steel caused by $H_2S$ gases generated by anaerobic bacterial. H2S gases react with oxygen and water to form sulfuric acid ($H_2SO_4$). This acid chemically attacks concrete, and sulfate ions penetrate into the concrete, causing rebar corrosion. In this work, to determine the conditions of RC culvert boxes which were constructed in the 1970s, various tests were conducted, including carbonation depth, compressive strength, half-cell potential measurements, and XRD analyses. Results indicated that the concrete deterioration was caused by sulfate attack and rebar corrosion. This paper discusses the evaluation on the durability of reinforced concrete structures covered creek for road vehicle.

• 한국조경학회지
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• 제19권2호
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• pp.52-64
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• 1991

The actual vegetation and environmental impact grade of Daekwanrim in Hamyang were investigated and the structure of the plant community was analyzed by the classification of TWINSPAN and three kinds of multivariate ordination (PCA, RA, DCA) techniques.Twenty-eight plots were set up by the clumped sampling method in June of 1990. Carpinus laxiflora and C. tschonoskii communities covered 38% and Quercus species communities covered 39% of the total rea. Environmental impact class 3 and 4 area. Twenty-eight plots were divided into three groups according to the degree of damage by TWINSPAN and ordination techniques. The dominant species in the shrub layer of the heavily damaged site and the light damaged site were Styrax japonica and Sasamorpha purporanscens, so the sucessional trends should be disturbed. As a result of the analysis for the relationship between the stand scores of DCA and the environmental impact class, they had a tendancy to increase from the light damaged to heavily damaged site.

• 한국조경학회지
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• 제25권3호
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• pp.56-65
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• 1997

This research was conducted to suggest some directions for desirable urban green space planning through 1) establishing a new classification system by examining the existing concept, problems and characteristics of green space and 2) defining the essence of green space environment and finding some analytical and evaluative methods through a clear establishment of functions, indicators of green space. In the research, measurements of the amount of green space was accompanied with measurements of green covered space, green volume, and the structure of greenery within the frame of vision. As result, three-dimensional measurement was possible, three-dimensional measurement was possible, which turned out to be more effective than the existing 2-dimensional measuring method. It is found that the ratio of green covered space is to proportional to the ratio of green volume in this study. Therefore in green space planning process it is desirable to consider the ratio of green volume all together.

• Journal of Electrochemical Science and Technology
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• 제12권2호
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• pp.167-172
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• 2021

he progressively improved sensing sensitivity (∆λ_SPR/∆n, nm/RIU) to detect the refractive index is observed on the SPR platform of an Au-covered epoxy gratings in an increase in potential cycling in a typical three-electrode cell. Here, a DVD-R optical disc was used as a structure template to prepare an Au-covered epoxy gratings, and the newly formed reverse track pitch structure on the epoxy substrate was used as a working electrode directly in aqueous sulfuric acid solution. It is expected that Au reconstruction by potential cycling in sulfuric acid electrolyte increases the packing density of Au atoms in the grain boundary and improves the propagation of electromagnetic waves.

• 건축역사연구
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• 제32권3호
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• pp.77-88
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• 2023

In the late Joseon Dynasty, the floor of the royal palace was covered with grass mat called ji-ui. Ji-ui was produced by connecting several mats named seokja(席子) and trimming the edge with narrow fabric named seon(縇). The standard manufacturing technique was to connect the shorter sides of the seokjas by overstitching them. A room was covered with either single or multiple ji-uis, depending on the case. In the case of the main and the subsidiary halls (jeong-jeon and pyeon-jeon, respectively) where the king conducted official meetings with the civil servants, multiple ji-uis were laid out to signify the division of space, which reflected the ceremonial aspects of the governing acts. The most essential division was the distinction of yeong-wae(楹外) and yeong-nae(楹內), with the jeon-goju (a tall frontal pillar inside the hall) functioning as the breakpoint. Jeong-jeon was divided into four spaces each covered with one ji-ui: yeong-nae, yeong-wae, and the left and the right sides of the royal seat named jwa-tap(座榻). Pyeon-jeon was covered with three ji-uis that divided the hall into three spaces: yeong-nae, yeong-wae, and hu-twae(後退) (the hind section) where the royal seat was placed on.

• 한국주거학회논문집
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• 제25권6호
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• pp.133-146
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• 2014

This study aims to analyze the changes of adjacent residential area after the restoration of covered urban streams in seoul. The changes of adjacent residential area after restoration were analyzed by changes of land using, urban structure, individual lot of land and architecture to investigate relationship of the urban stream and residential change. The result as follows: the first one is the change of land use and urban structure in adjacent residential area. This change of infrastructure through stream restoration has transformed land use and urban structure in adjacent residential area. Secondly, there is the changes of the individual lot of land. It seemed that new development by combined lots would be concentrated in stream-side blocks. But, the changes of lots such as combining or dividing lots tend to be concentrated in stream-side, main road and main streets. In stream-side, commercial function of land use has changed to residential one which has restored streams landscape by transformation of lots use without changes of ownership-lots. Finally, there is the change of architecture. It turned out new building in adjacent residential area is similar to general development. However, new building in streamside is related to direction of stream. In addition, remodeling and expansion tend to change in commercial buildings on stream-side bridges of corner lots intensively. As a result, it is related to expectation of architectural activation and improvement of sidewalk environment by stream restoration.

• 한국공간구조학회지
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• 제2권2호
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• pp.11-15
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• 2002

Formerly, it was called a tent and now, it is called membrane structure. If saying a tent, it imagines the tent of Bedouin, Mongolia and North American Indian. It became clear from the excavated wall painting that have been covered with the retractable roof of the canvas on the auditorium at the amphitheater in Pompeii and became a topic. These tents were made of the animal skins or fabric woven with the flax plants, and these tents are still used. However, if saying membrane material at present, it says the one to have applied a coating resin to the textile. Because the base fabric of membrane material is a woven fabric, the relation between the stress and the strain is different to the direction of the weaving thread. Moreover, the tensile force must always occur in the membrane surface. From these reasons, because the membrane structure corresponds to the particular building material and the construction method about the Building Standard Law, it must be examined specially that the membrane structural building have the same or any more safety as the provisions which was set to the Building Standard Law. Therefore, the technical standards about the membrane structural building became indispensable. In the paper, the kinds of the membrane materials, which are used for the membrane structural buildings, and technical standards process of the creating for the membrane structure buildings are introduced. Lastly, some of the soccer stadiums for 2002 FIFA World Cup KOREA/JAPAN which be covered with the roof of the membrane structures are presented.

• 한국조경학회지
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• 제23권2호
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• pp.148-156
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• 1995

This study was conducted to investigate the actual vegetation and plant community structure of the urban forest in Kwangju Metropolitan City. Thirty eight plots in the urban forest were set up by the clumped sampling method. The degree of green naturality, 6 that is artifical planting area covered 10.9% in Kwangju Metropolitan City and Pinus densiflora community covered 48.7% of the actual vegetations of urban forest. Canopy height, Diameter of breast height (DBH) and No. of species in urban forest were 13.5m, 21cm and 24 species, respectively. The soil conditions and community structure of the urban forest were differenced by location of urban and suburban area. The plant communities divided into six groups which were Quercus acutissima community, Q. acutissima-Robinia pseudo-acacia community, Pinus rigida Community, P. rigida-P. densiflora community, P. densifrora-Q. acutissima community and Q, serrata-P. densiflora community. Successional series of the urban forest in the surveyed area were proceeding from P. dinsiflora to Quercus species. The species diversity of plant were high in natural plant community but low in artificial plant community. Tree density in the canopy layer varied from 600ea/ha to 2,800ea/ha.