• Journal of the Korean Geosynthetics Society
• /
• v.2 no.1
• /
• pp.27-37
• /
• 2003

The factors affecting shear strength and friction characteristics of the fiber-mixed soil can be classified into engineering properties of soil; particle-size, distribution, and particle shape, physical and mechanical properties of fiber; shape, length, diameter, tensile strength, elastic modulus, friction coefficient, and mixed ratio and external factors; confined stress and compaction condition. In this study, a series of shear friction tests and pull-out tests were performed to evaluate the friction properties of fiber-mixed soil according to soil type, fiber type, fiber mixed ratio and compaction degree. The materials and test conditions used in this study are as follows. Soils: SM and ML; mixing fibers: three types of polypropylene fibers(net type 38mm and 60mm, and line type 60mm); reinforcement: geogrid; mixing ratio: 0.2% and 0.3%; degree of compaction : 85% and 95%.

• Geotechnical Engineering
• /
• v.13 no.4
• /
• pp.95-108
• /
• 1997

For normally consolidated clay, several researchers have developed a number of theoretical time factors to determine the coefficient of consolidation However, depending on the assumptions and analytical techniques, it could considerably vary even for a specific degree of consolidation. In this paper, a method is proposed to determine a consistent coefficient of consolidation over all ranges of degree of consolidation by applying the concept of the Optimum Design Technique. The initial excess pore pressure distribution is assumed to be obtainable by the successive spherical cavity expansion theory. The dissipation of pore pressure is simulated by means of two dimensional linear-uncoupled axisymmetric consolidation analysis. The minimization of the differences between the measured and the predicted excess pore pressures was carried by BFGS unconstrained optimum design algorithm with one dimensional golden section search technique. By analyzing numerical and real field examples, it can be found that the adopted optimum technique gives a consistent and convergent results.

• Earthquakes and Structures
• /
• v.1 no.4
• /
• pp.327-344
• /
• 2010

This paper summarizes results of a comprehensive analytical study aimed at evaluating the influence of strong ground motion duration on residual displacement demands of single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems. For that purpose, two sets of 20 earthquake ground motions representative of short-duration and long-duration records were considered in this investigation. While the influence of strong ground motion duration was evaluated through constant-strength residual displacement ratios, $C_r$, computed from the nonlinear response of elastoplastic SDOF systems, its effect on the amplitude and height-wise distribution of residual drift demands in MDOF systems was studied from the response of three one-bay two-dimensional generic frame models. In this investigation, an inelastic ground motion intensity measure was employed to scale each record, which allowed reducing the record-to-record variability in the estimation of residual drift demands. From the results obtained in this study, it was found that long strong-motion duration records might trigger larger median $C_r$ ratios for SDOF systems having short-to-medium period of vibration than short strong-motion duration records. However, taking into account the large record-to-record variability of $C_r$, it was found that strong motion duration might not be statistically significant for most of the combinations of period of vibration and levels of lateral strength considered in this study. In addition, strong motion duration does not have a significant influence on the amplitude of peak residual drift demands in MDOF systems, but records having long strong-motion duration tend to increase residual drift demands in the upper stories of long-period generic frames.

• Polymer(Korea)
• /
• v.35 no.5
• /
• pp.478-482
• /
• 2011

In this study, several poly(styrene-co-(trimethoxysilyl)propyl methacrylate)-grafted ETFE films were prepared by a simultaneous irradiation grafting method. After mixing of styrene/(trimethoxysilyl)propyl methacrylate(TMSPM) monomers with various solvents, the effects of various irradiation conditions such as total dose, dose rate and monomer concentration on the degree of grafting of the prepared membranes were investigated. Results indicated that the higher degree of grafting was obtained when acetone was used as a solvent. The formation of poly(styrene-co-TMSPM) grafts on the ETFE films was verified using FTIR spectrometry and the distribution of the poly(PTMSPM) graft polymer over the cross-section of the grafted film was confirmed using SEM-EDX instrument.

• Korean Journal of Environment and Ecology
• /
• v.22 no.1
• /
• pp.1-10
• /
• 2008

The Bulyeongsa Valley in Uljin-gun(Gyeungbuk) has a unique beautiful landscape and plentiful ecosystem, and Pinus densiflora for. erecta is distributed widely. Recently as the widening of national road in Bulyeongsa Valley, comprehensive survey is needed. So to investigate the forest distribution and structure, ninety-nine plots were installed and surveyed. Each plot size is $100m^2$. Important percentage analysis of the summarize results, vegatation of Bulyeung valley is found out that dominant species is Pinus densiflora mainly and Quercus variabilis and Quercus serrata are compatitive relation with Pinus densiflora partially. The analysis results of the actual vegetation and degree of green naturality(DGN) showed that Pinus densiflora community is 47.75%, and DGN 8 is 69.14% in total. From the above results, vegatation of Bulyeungsa valley is found out that dominant species is Pinus densiflora mainly, and Quercus variabilis and Quercus serrata are competitive relation with Pinus densiflora partially.

• Polymer(Korea)
• /
• v.27 no.6
• /
• pp.542-548
• /
• 2003

Nanoparticles with unsaturated poly(hydroxyalkanoate)s (UPHAs) biosynthesized with Pseudo-monas oleovorans were prepared by spontaneous emulsification solvent diffusion method. The influence of nanoparticle formation was investigated with various experimental parameters such as sonication conditions, sol-vent, surfactant and polymer contents, etc. The physical and chemical properties of UPHAS and its nanoparticles were characterized using $^1$H- and $\^$13/C-nuclear magnetic resonance spectroscopies, attenuated total reflection infrared spectroscopy, differential scanning calorimetry and gel permeation chromatography. The morphology of particles was observed using scanning electron microscope and the size and distribution of nanoparticles were measured with electrophoretic light scattering spectrophotometer. The mean diameter of particles decreased with increasing sonication amplitude and time. The addition of ethanol into UPHAS chloroform solution decreased the particle size presumably due to increased solvent diffusion into water phase. The particle size increased with increased the concentration of UPHAS solution. Under the 2-4％ poly(vinyl alcohol) (PVA) aqueous solution the minimum mean diameter of particles was shown. The higher degree of hydrolysis and degree of polymerization of PVA increased the mean diameter of particles.

• Journal of Wetlands Research
• /
• v.5 no.2
• /
• pp.43-55
• /
• 2003

Vegetation structure was investigated in the Hyeonchang wetland and its watershed around the Nakdong-gang, Changryeong-county, Gyeongsangnamdo, Korea. from May to August, 2001. The vegetation type of the Hyeonchang wetland was classified into 12 communities based on the actual vegetation map: Phragmites communis community, Zizania latifolia community, Phragmites communis - Persicaria perfoliata community, Salix koreensis community, Persicaria perfoliata - Phragmites communis community, Spirodela polyrhiza community, Persicaria perfoliata community, Cyperus amuricus community, Cyperus amuricus-EchinochJoa crus-galli var. frumentacea community, Phragmites communis-Zizania latifolia community, EchinochJoa crus-galli var. frumentacea community, and Persicaria maackiana community. Among them, Phragmites communis community was the largest (4.3 ha, 24%). The dominant vegetation type were Phragmites communis community, Echinochloa crus-galli var. frumentacea-Persicaria maackiana community, and Cyperus amuricus subcommunity based on the phytosociological method. The vegetation type of the Hyeonchang wetland watershed was classified into five communities based on the actual vegetation map: Pinus densilflora community, Pinus rigida community, Pinus densiflora-Quercus acutissima community, Pinus densiflora-Larix gmelini var. principis-ruprechtii community, and Populus tomentiglandulosa community. Among them, Distribution area of Pinus densiflora community was largest (399.3 ha, 61.8%). And the degree of green naturality of the Pinus densiflora community was 7 and 8 degree.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.6
• /
• pp.485-491
• /
• 2013

Recently, with the proliferation of social network services, users and many companies hope that their information spread more faster. In order to study the information diffusion in the social networks, many algorithms such as greedy algorithm and heuristic algorithm have been proposed. However, the greedy algorithm is too complicated to use in real-life social network, and the heuristic algorithms have been studied under the uniform distribution of diffusion probability, which is different from the real social network property. In this paper, we propose an heuristic information diffusion maximization algorithm based on diffusion probability and node degree. For performance evaluation, we use real social network database, and it is verified that our proposed algorithm activates more active nodes than existing algorithms, which enables faster and wider information diffusion.

• The Journal of Korean Medicine
• /
• v.26 no.1 s.61
• /
• pp.103-114
• /
• 2005

Objective; Childhood obesity has become one of the most common health problems facing children in the world. Although a number of regimens have been developed and distributed for the treatment of adult obesity, few studies have focused on therapeutic programs for obese children. The objective of this study was to develop and measure the effects of Taeumin childhood obesity by a sasang constitution­based education program. Methods ; A total of 14$(\%RBW\geq20)$ among 18 taeumin with childhood obesity from June to August 2003 participated in the constitution-based education program. It was designed to examine the effects of a constitution-based education program through anthropometric measurements, body composition indicates, biochemical indicates and serum level of taeumin childhood obesity. Results; The results of this study were as follows: 1. The anthropometric measurement of subscapular skinfold thickness was reduced after 4 weeks of the constitution-based education program. 2. The body composition indicates reduction in degree of obesity, percent body fat, and fat distribution. The other side increased in height, total body water, soft lean mass, and lean body mass. 3. For biochemical indicates, HDL-cholesterol was increased significantly after 4 weeks of the constitution-based education program. The other side decreased in AST and ALT. 4. There was a significant reduction in BMI and $\%RBW$ after the constitution-based education program. Conclusion : A constitution-based education program for weight control results in reduced degree of obesity among taeumin children.

• Restorative Dentistry and Endodontics
• /
• v.16 no.1
• /
• pp.41-59
• /
• 1991

This study was performed to elucidate the distribution and correlation of immunoglobulin G subclasses with the degree of inflammation in the experimentally induced rat pulp and periapical pathoses. The pulp exposures were made in 108 mandibular 1st molars of 54 rats and the teeth were left open to the oral environment The animals were sacrified at 3, 7, 15, 30, 60 and 90 days after pulp exposure, and examined microscopically and radiographically Seventy one specimens were routinely sectioned at the thickness of 4 - $6{\mu}$ and stained with Hematoxylin - eosin for histologic examination, with toluidine blue for mast cells, and with the primary antibodies against rat IgG subclasses by using the Avidin - Biotin complex method. The following results were obtained: 1. As the degree of inflammation of rat pulp and periapeces intensified, the number of IgG subclass containing cells per unit area, especially IgG2a and IgG2c, decresased. 2. The IgG2c cells were most predominantly found in the lesions with slight inflammation, IgG1 cells in mild or severe inflammation, and IgG2a cells in moderate inflammation. 3. IgG subclass containg cells were more predominantly observed in the periapical granuloma than periapical abscess or cyst(p<0.01). 4. IgG2a containing cells were predominant in pulp inflammation, IgG1 containing cells in periapical granuloma, IgG2a cells and IgG1 cells in periapical abscess, and IgG2a cells were significantly predominant in periapical cyst. 5. The number of IgG subclass containing cells and mast cells in periapical tissue decreased with time lapse after pulp exposure. And correlation index between mast cells and IgG1, IgG2a, IgG2b was stastically high.