• Structural Engineering and Mechanics
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• v.78 no.4
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• pp.425-437
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• 2021

Under foundation shock mats have been used in the current practice in order to reduce/damp vibrations received by buildings through the surrounding environment. Although some investigations have been made on under foundation shock mats performance, their effectiveness in the reduction of railway induced-vibrations has not been fully studied, particularly with the consideration of underneath soil media. In this regard, this research is aimed at investigating performance of shock mat used beneath building foundation for reduction of railway induced-vibrations, taking into account soil-structure interaction. For this purpose, a 2D finite/infinite element model of a building and its surrounding soil media was developed. It includes an elastic soil media, a railway embankment, a shock mat, and the building. The model results were validated using an analytical solution reported in the literature. The performance of shock mats was examined by an extensive parametric analysis on the soil type, bedding modulus of shock mat and dominant excitation frequency. The results obtained indicated that although the shock mat can substantially reduce the building vibrations, its performance is significantly influenced by its underneath soil media. The softer the soil, the lower the shock mat efficiency. Also, as the train excitation frequency increases, a better performance of shock-mats is observed. A simplified model/method was developed for prediction of shock mat effectiveness in reduction of railway-induced vibrations, making use of the results obtained.

• International Journal of Industrial Entomology and Biomaterials
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• v.34 no.2
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• pp.32-37
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• 2017

The purpose of this study was (1) to demonstrate the anti-microbial properties of 4-hexylresorcinol (4HR) loaded silk mat and (2) comparison of bone formation between 4HR incorporated silk mat and collagen membrane. Anti-microbial properties of 4HR incorporated silk mat was done after sterilization of silk mat (autoclaving and ethylene oxide gas). For the evaluation of bone formation, bilateral bony defects (size: 8 mm) were prepared in the parietal bone of the rabbits (n=10). 4HR incorporated silk mat (size: $10{\times}10mm$) was applied on the right defect. For the comparative purpose, the same size of commercial collagen membrane was applied on the left defect. The anti-microbial properties of 4HR incorporated silk mat were maintained after sterilization process. When compared bone mineral density and bone volume, there was no statistically significant difference between groups at 4 weeks and 8 weeks after operation (p>0.05). In conclusion, 4HR incorporated silk mat could be autoclaved without concern of anti-microbial properties loss. In addition, 4HR incorporated silk mat showed similar bone regeneration to collagen membrane. Therefore, 4HR incorporated silk mat might be considered for the application of open membrane technique.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.97-104
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• 2010

The purpose of this study is to evaluate sediment yield reduction under various field slope conditions with rice straw mat. The Vegetative Filter Strip Model-W (VFSMOD-W) and Soil and Water Assessment Tool (SWAT) were used for simulation of sediment yield reduction effect of rice straw mat. The Universe Soil Loss Equation Practice factor (USLE P factor), being able to reflect simulation of rice straw mat in the agricultural field, were estimated for each slope with VFSMOD-W and measured soil erosion values under 5, 10, and 20 % slopes. Then with the regression equation for slopes, USLE P factor was derived and used as input data for each Hydrological Response Unit (HRU) in the SWAT model. The SWAT Spatially Distributed-HRU (SD-HRU) pre-processor module was utilized, moreover, in order to consider spatial location and topographic features (measured topographic features by field survey) of all HRU within each subwatershed in the study watershed. Result of monthly sediment yield without rice straw mat (Jan. 2000 - Aug. 2007) was 814.72 ton/month, and with rice straw mat (Jan. 2000 - Aug. 2007) was 526.75 ton/month, which was reduced as 35.35 % compared without it. Also, during the rainy season (from Jun. to Sep. 2000 - 2007), when without vs. with rice straw mat, monthly sediment indicated 2,109.54 ton and 1,358.61 ton respectively. It showed about 35.60 % was reduced depending on rice straw mat. As shown in this study, if rice straw mat is used as a Best Management Practice (BMP) in the sloping fields, rainfall-driven sediment yield will be reduced effectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1075-1081
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• 2008

In this paper, we propose a code acquisition algorithm using optical orthogonal code (OOC) for optical code division multiple access (CDMA) systems. Generally, a good code acquisition algorithm offers short mean acquisition time (MAT). The conventional multiple-shift (MS) algorithm consists of two stages and has shorter MAT than that of well-known serial-search (SS) algorithm. This paper proposes a novel code acquisition algorithm called enhanced multiple-shift (EMS) algorithm. By using multiple thresholds, the proposed EMS algorithm provides shorter MAT compared with that of the MS algorithm. The simulation results show that the EMS algorithm presents shorter MAT compared with the MS algorithm in both single-user and multi-user environments.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.1
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• pp.54-61
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• 2000

Covering rate, visual rating and sod development were evaluated under three natural fiber materials with Phragmites spp. when over a plastic sheet. The results were as follows. (1) The last covering rate was high on jute net, coir mat and on Miscanthus sacchariflorus, respectively while the early covering rate was high on coir mat and on Miscanthus sinensis+perennial ryegrass. (2) The early growth was good on perennial ryegrass but the covering rate gradually turned poor because of summer drought. (3) Sod was highly developed on Phragmites japonica, Miscanthus sacchariflorus and Miscanthus sinensis compared with other species and mixtures. (4) The covering rate and visual rating were high on natural fiber materials such as coir mat and jute net when compared with on natural fiber materials such as none treatment plots. (5) The natural fibers materials on Phragmites spp. and Miscanthus spp. were effect on sod establishment. Sod coir mat was highly established. (6) The carpet-type sod was best developed on the coir mat.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.81-84
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• 2002

Recently Bentonite mat is applied various structure : External waterproofing for underground structure, A reclaimed land, Artificial lake, Large-scaled civil structure, etc. With these various structure environment, water quality for application of Bentonite Mat affects watertightness. Specially spot with a large quantity of Chloride ion like salt water, degree of watertightness revelation is evaluated and applied. In this study, it is a main goal to investigate watertightness of Bentonite Mat with distilled water and salt water dissolved chloride ion Contents 0.88%. The result of this paper is as follows. 1) Water permeability coefficient of Bentonite Mat : distilled water(1.21$\times$10$^{-9}$cm/sec), salt water(3.12$\times$10$^{-7}$cm/sec). 2) Variation of thickness : distilled water(187%), salt water(108%). 3) Swelling ratio : distilled water(1500%), salt water(350%).

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.253-253
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• 2007

• BMB Reports
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• v.34 no.4
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• pp.305-309
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• 2001

MatR in Rhizobium trifolii is a malonate-responsive transcription factor that regulates the expression of genes, matABC, enabling decarboxylation of malonyl-CoA into acetyl-CoA, synthesis of malonyl-CoA from malonate and CoA, and malonate transport. According to an analysis of the amino acid sequence homology, MatR belongs to the GntR family The proteins of this family have two-domain folds, the N-terminal helix-turn-helix DNA-binding domain and the C-terminal ligand-binding domain. In order to End the malonate binding site and amino acid residues that interact with RNA polymerase, a site-directed mutagenesis was performed. Analysis of the mutant MatR suggests that Arg-160 might be involved in malonate binding, whereas Arg-102 and Arg-174 are critical for the repression activity by interacting with RNA polymerase.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.1-4
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• 2003

Recently, a structure has been larger and higher under the improvement of construction technique. So, a concrete constructions that a mat foundation thickness of structure is over 80cm have been many. Also, because of the reason high strength concrete, the matter of thermal crack have become an important task to be solved absolutely. In a cause a thermal crack occurrence, there used, mixture of concrete, construction and so forth. In this study, we executed temperature and stress analysis of mat foundation to know the effect the construction condition a thermal crack of mat foundation. And we evaluated quantitatively about the occurrence possibility of thermal crack using the hydration heat analysis program. By using of this analysis technique, will can control skilfully the quality of a mat foundation in advance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.1-4
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• 2003

Recently, a structure has been larger and higher under the improvement of construction technique. So, a mass concrete constructions that a mat foundation thickness of structure is over 80cm have been many. Also, because of the reason of high strength of concrete, the matter of thermal crack have become an important task to be solved absolutely. tn a cause of a thermal crack occurrence, there are material used, mixture of concrete, construction condition and so forth. In this study, we executed temperature and stress analysis of mat foundation to know the effect of the construction condition on a thermal crack of mat foundation. And we evaluated quantitatively about the occurrence possibility of thermal crack using the hydration heat analysis program. By using of this analysis technique, we will can control skilfully the quality of a mat foundation in advance.