• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.6
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• pp.57-69
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• 2011

The present paper deals with a research of life form and vegetation of the plants extant in the habitat of endangered Parnassius bremeri in Uiseong, Gyeongsangbuk-do with a view to restore their habitat and create substitute habitats. The research found that there are a total of 130 vascular plants including 47 families, 96 genera, 113 species, 1 subspecies and 16 varieties. In terms of their life form, hemicryptophytes (H) is the majority of dormancy form with 41 species or 31.54%, while $R_5$ is majority of radicoid form with 72 species or 55.38%, gravitational disseminule form ($D_4$) is majority among the disseminule forms with 68 species or 52.31% and erect type (e) is majority of growth form with 57 species or 43.85%. Major constituents of the habitat are Sedum kamtschaticum, Selaginella tamariscina, Orostachys japonica, Arundinella hirta, Cymbopogon tortilis var. goeringii, Themeda triandra var. japonica, Carex humilis, Indigofera kirilowii, Imperata cylindrica var. koenigii, Festuca ovina, Artemisia capillaris, etc., all of species which are in the initial stage of succession and show simultaneously features characteristic of vegetation on the rock. In the habitat 1. Sedum kamtschaticum- Selaginella tamariscina community and Pinus densiflora community are distributed whereas, in the habitat 2. Sedum kamtschaticum-Selaginella tamariscina community, Sedum kamtschaticum-Carex humilis community, Sedum kamtschaticum-Cymbopogon tortilis var. goeringii community and Sedum kamtschaticum-Imperata cylindrica var. koenigii community are growing and in the habitat 3. Sedum kamtschaticum-Selaginella tamariscina community, Selaginella tamariscina community, Sedum kamtschaticum-Indigofera kirilowii community and Quercus acutissima community are seen distributed there, too. Typical of food plants growing in the habitat is Sedum kamtschaticum, found mostly in the rocky area and its surroundings. Absorption plants are those that usually bloom in the season when imagoes emerge. From the research, it becomes evident that the blooming season of Sedum kamtschaticum, obviously a food plant, corresponds exactly to the emergence timing of imagoes. Cirsium japonicum var. ussuriense, Rosa multiflora, Erigeron annuus, Spiraea prunifolia var. simpliciflora are found to belong to these plants.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.126-136
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• 2017

We describe characteristics of diversity and distribution of oak forests on the Daegok-cheon gorge of the Southeastern Korean Peninsula, the oldest prehistoric site, in view of a sort of food resources of acorns. The $Z{\ddot{u}}rich$-Montpellier School's method was adopted for field investigation on the oak dominant stands. A total of 20 phytosociological $relev\acute{e}s$ composed of 193 taxa were analyzed by syntaxonomy and ecological flora. The Daegok-cheon's oak forests occupied 36.9% ($513,374m^2$) of the surveyed area, and its 99% ($507,677m^2$) was Quercus variabilis and Q. serrata stands. Oak forests of the Daegok-cheon gorge are a kind of regional vegetation type characterizing by the high relative net contribution degree (r-NCD) of Platycarya strobilacea and Sapium japonicum, which are an edaphic type of the xerophilous and thermophilic oak forests. The region of the Daegok-cheon petroglyphs is defined as an ecoregion with rich acorn supply and abundant water resources, and the warmer environment, which attracts prehistoric man.

• Journal of Korean society of Dental Hygiene
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• v.13 no.2
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• pp.351-360
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• 2013

Objectives : The purpose of this study was to evaluate the effects of tooth bleaching agent contained 15% carbamide peroxide on the color, microhardness and surface roughness of tooth-colored restorative materials by using pH cycling model. Methods : Four types of tooth-colored restorative materials, including a composite resin(Filtek Z350 ; Z350), a flowable composite resin(Filtek P60 : P60), a compomer(Dyract$^{(R)}$ AP ; DY), and a glass-ionomer cement(KetacTM Molar Easymix ; KM). were used in the study. Eighty-eight specimens of each material were fabricated, randomly divided into two groups(n=44): experimental group(15% carbamide peroxide) and control group(distilled water). These groups were then divided into four subgroups(n=11). All groups were bleached 4 hours per day for 14 days using pH cycling model. The authors measured the color, microhardness, and roughness of the specimens before and after bleaching. The data were analyzed with ANOVA and T-test. Results : Z350 and P60 showed a slight color change(${\Delta}E^*$), whereas DY and KM showed significantly color change(p<0.05). Among them, the greatest color change was observed in DY. Percentage microhardness loss(PML) of the distilled water group was 1.8 to 5.1%, and 15% peroxide peroxide group was 5.0 to 25.2%. Microhardness of DY and KM showed a statistically significant decrease(p<0.05). Roughness was increased in all groups after bleaching. Z350 and P60 does not have a significant difference(p>0.05), however DY and KM significantly increased more than the 0.2 ${\mu}m$(p<0.05). Conclusions : The effects of bleaching on restorative materials were material dependent. It is necessary to consider the type of the material before starting the treatment.

• Journal of Food Hygiene and Safety
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• v.33 no.5
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• pp.369-374
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• 2018

In this study, Lactobacillus brevis SM61 from traditional Kimchi was used for fermentation of aqueous extract of P. brevitarsis larva and mountain ginseng. As measured by MTT assay, aqueous extract of P. brevitarsis larva and fermented mixture of aqueous extract and mountain ginseng did not show specific cellular toxicity in RAW264.7 cells until a concentration of $5-1000{\mu}g/mL$. The polyphenol contents was highest in the fermented mixture of aqueous extract and mountain ginseng. DPPH radical scavenging activity was stronger in the fermented mixture of aqueous extract and mountain ginseng than the aqueous extract. Also, antibacterial activity was tested against E. coli, L. monocytogenes and S. aureus. The fermented mixture of aqueous extract and mountain ginseng showed antibacterial activity against the tested bacteria. Therefore, L. brevis SM61 as a starter might be used to improve functionality of P. brevitarsis larva.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.2
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• pp.96-104
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• 2001

Usage of ecosystem models has been extended to landscape scales for understanding the effects of environmental factors on natural and agro-ecosystems and for serving as their management decision tools. Accurate prediction of spatial variation in daily temperature is required for most ecosystem models to be applied to landscape scales. There are relatively few empirical evaluations of landscape-scale temperature prediction techniques in mountainous terrain such as Korean Peninsula. We derived a periodic function of seasonal lapse rate fluctuation from analysis of elevation effects on daily temperatures. Observed daily maximum and minimum temperature data at 63 standard stations in 1999 were regressed to the latitude, longitude, distance from the nearest coastline and altitude of the stations, and the optimum models with $r^2$ of 0.65 and above were selected. Partial regression coefficients for the altitude variable were plotted against day of year, and a numerical formula was determined for simulating the seasonal trend of daily lapse rate, i.e., partial regression coefficients. The formula in conjunction with an inverse distance weighted interpolation scheme was applied to predict daily temperatures at 267 sites, where observation data are available, on randomly selected dates for winter, spring and summer in 2000. The estimation errors were smaller and more consistent than the inverse distance weighting plus mean annual lapse rate scheme. We conclude that this method is simple and accurate enough to be used as an operational temperature interpolation scheme at landscape scale in Korea and should be applicable to elsewhere.

• Journal of The Korean Association For Science Education
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• v.33 no.7
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• pp.1285-1299
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• 2013

Nurturing students' scientific creativity is considered an important element in science education in Korea. The study aims to explore patterns displayed by well-known scientists in their quest for problem finding. Each case of scientists' course of problem solving is described in terms of historical background, a process of problem finding, and a process of problem solving. There are five patterns from ten scientists which are as follows: Pattern 1 is that scientists find problems from insufficiencies and/or errors from explanation of theories at the time and the related cases are A. Lavoisier, G. Mendel, and J. Watson. Pattern 2 shows that scientists find a problem because of strange phenomena unexplained by theories at the time, and here important case studies are E. Rutherford and W. R$\ddot{o}$ntgen. Pattern 3 demonstrates that scientists find a problem from analogical reasoning between known theories and unknown science phenomena. The cases include S. Carnot and T. Young. Pattern 4 points to the fact that scientists find a problem while they utilize a newly invented experimental instrument. Here, G. Galilei is an important example. Pattern 5 establishes that scientists happen to find a problem while they conduct research projects. The works of M. Faraday and J. Kepler are prominent case studies related to this pattern.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1170-1174
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• 2009

Two frequency-reconfigurable antennas have been designed and combined in a space with limited volume, i.e., 40mm ${\times}$ 20mm ${\times}$ 6mm. Each antenna can be reconfigured to operate at different frequency bands depending on the state of an embedded switch, which is implemented using a PIN diode. The first antenna can be switched between 0.82GHz ${\sim}$ 0.96GHz band (GSM/ CDMA) and 1.7GHz ${\sim}$ 2.17GHz band (DCS/ PCS/ WCDMA), which are cellular bands. The second antenna can be switched between 3.4GHz ${\sim}$ 3.6GHz band (mWiMax) and 2.3GHz ${\sim}$ 2.5GHz, 5.15GHz ${\sim}$ 5.35GHz bands (WiBro/ WLAN 11a/b/g/n), which are connectivity bands. The proposed combined antenna operates both over cellular bands and connectivity bands concurrently. The choice of the operation bands is made independently by the states of the two switches.

• Ocean Systems Engineering
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• v.6 no.1
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• pp.61-97
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• 2016

This is the second of two papers on the 3D numerical modeling of nearshore hydro- and morphodynamics. In Part I, the focus was on surf and swash zone hydrodynamics in the cross-shore and longshore directions. Here, we consider nearshore processes with an emphasis on the effects of oceanic forcing and beach characteristics on sediment transport in the cross- and longshore directions, as well as on foreshore bathymetry changes. The Delft3D and XBeach models were used with four turbulence closures (viz., ${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES) to solve the 3D Navier-Stokes equations for incompressible flow as well as the beach morphology. The sediment transport module simulates both bed load and suspended load transport of non-cohesive sediments. Twenty sets of numerical experiments combining nine control parameters under a range of bed characteristics and incident wave and tidal conditions were simulated. For each case, the general morphological response in shore-normal and shore-parallel directions was presented. Numerical results showed that the ${\kappa}-{\varepsilon}$ and H-LES closure models yield similar results that are in better agreement with existing morphodynamic observations than the results of the other turbulence models. The simulations showed that wave forcing drives a sediment circulation pattern that results in bar and berm formation. However, together with wave forcing, tides modulate the predicted nearshore sediment dynamics. The combination of tides and wave action has a notable effect on longshore suspended sediment transport fluxes, relative to wave action alone. The model's ability to predict sediment transport under propagation of obliquely incident wave conditions underscores its potential for understanding the evolution of beach morphology at field scale. For example, the results of the model confirmed that the wave characteristics have a considerable effect on the cumulative erosion/deposition, cross-shore distribution of longshore sediment transport and transport rate across and along the beach face. In addition, for the same type of oceanic forcing, the beach morphology exhibits different erosive characteristics depending on grain size (e.g., foreshore profile evolution is erosive or accretive on fine or coarse sand beaches, respectively). Decreasing wave height increases the proportion of onshore to offshore fluxes, almost reaching a neutral net balance. The sediment movement increases with wave height, which is the dominant factor controlling the beach face shape.

• Journal of the Korea Institute of Building Construction
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• v.14 no.5
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• pp.389-396
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• 2014

The set accelerator used for shotcrete at high pH environment often causes the dusting problem in practice. In this research, a slurry-type set accelerator was developed to avoid this problem and its effectiveness was investigated by applying it to shotcrete mortars. Set time, stiffening, compressive strength, and chloride ion penetration resistance were examined with different amounts of slag, used as partial replacement of cement. According to the experimental results, it was found that the earlier responses such as set time, stiffening, and 1-day compressive strength were probably affected by the amount of ettringite, formulated by the hydration between C12A7 and calcium sulfate polymorphs present in blast furnace slag. Whereas, it is believed that the result of compressive strength after 3 days was attributed to the hydration of tricalcium silicates. As for the results of a chloride ion penetration test, the partial replacement of cement with slag significantly reduced the total charge passed through the shotcrete mortar.

• Earthquakes and Structures
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• v.13 no.1
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• pp.59-66
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• 2017

Modern seismic codes rely on performance-based seismic design methodology which requires that the structures withstand inelastic deformation. Many studies have focused on the inelastic deformation ratio evaluation (ratio between the inelastic and elastic maximum lateral displacement demands) for various inelastic spectra. This paper investigates the inelastic response spectra through the ductility demand ${\mu}$, the yield strength reduction factor $R_y$, and the inelastic deformation ratio. They depend on the vibration period T, the post-to-preyield stiffness ratio ${\alpha}$, the peak ground acceleration (PGA), and the normalized yield strength coefficient ${\eta}$ (ratio of yield strength coefficient divided by the PGA). A new inelastic deformation ratio $C_{\eta}$ is defined; it is related to the capacity curve (pushover curve) through the coefficient (${\eta}$) and the ratio (${\alpha}$) that are used as control parameters. A set of 140 real ground motions is selected. The structures are bilinear inelastic single degree of freedom systems (SDOF). The sensitivity of the resulting inelastic deformation ratio mean values is discussed for different levels of normalized yield strength coefficient. The influence of vibration period T, post-to-preyield stiffness ratio ${\alpha}$, normalized yield strength coefficient ${\eta}$, earthquake magnitude, ruptures distance (i.e., to fault rupture) and site conditions is also investigated. A regression analysis leads to simplified expressions of this inelastic deformation ratio. These simplified equations estimate the inelastic deformation ratio for structures, which is a key parameter for design or evaluation. The results show that, for a given level of normalized yield strength coefficient, these inelastic displacement ratios become non sensitive to none of the rupture distance, the earthquake magnitude or the site class. Furthermore, they show that the post-to-preyield stiffness has a negligible effect on the inelastic deformation ratio if the normalized yield strength coefficient is greater than unity.