• Journal of The Geomorphological Association of Korea
• /
• v.20 no.3
• /
• pp.95-107
• /
• 2013

In order to examine the temperature regime responsible for periglacial processes, air and ground temperatures were monitored from October 2010 to May 2011 at a subalpine bare patch (1,710m asl) of Mt. Halla. Four thermistor sensor probes were installed at 55 cm above a ground surface and depths of 2 cm, 10 cm, and 20 cm, respectively. A mean air temperature is $-0.1^{\circ}C$, while mean ground temperatures are $1.8^{\circ}C$ at 2 cm, $2.6^{\circ}C$ at 10 cm and $3.2^{\circ}C$ at 20 cm deep. A mean monthly ground temperature at 2 cm deep demonstrates below $0^{\circ}C$ successively from January to March, while those at 10 cm and 20 cm deep show no sub-zero temperature. A total of 72 freeze-thaw cycle was observed in air temperature. However, the numbers in ground temperature reduced into 17 at 2 cm, 8 at 10 cm, and 3 at 20 cm deep. The cycles of air temperature and ground temperature at 2 cm deep mostly fluctuated diurnally, while those of ground temperature at 10 cm and 20 cm deep exhibited a several-daily oscillation. Snow cover over 55 cm high remained from January to early April, and it seemed to disappear completely on April 16. A seasonal frost of at least 2 cm thick was formed on late December and the isotherm of $0^{\circ}C$ descended slowly into 10 cm deep on late March to early April due to the insulating snow cover. It showed the maximum freezing depth of 20 cm on April 7 to 14 and then thawed rapidly so that the frozen ground did not longer after April 17. Periglacial processes are predominant during a freezing period than a thawing period when the ground surface is still covered with snow. The periglacial mass movement in the subalpine zone of Mt. Halla is mainly generated by frost creep in terms of the occurrence depth of diurnal freeze-thaw cycle and the maximum freezing depth of ground.

• Journal of the Korean Society of Child Welfare
• /
• no.36
• /
• pp.165-196
• /
• 2011

With the increasing concerns of victimization of school violence, this paper is intended to present a pioneering study on the victims' conscientization which may result from their own experience of school violence by peers. The predominant concern of the study consists in: (1) the direct effects of individuals' perception toward violence in general, non-assertiveness, school violence experience by peers, and prosocial behavioral tendency on the individual conscientization of school violence problems; (2) the indirect effects of both individual prosocial behavioral tendency and perceptions toward violence through non-assertiveness on individual conscientization of school violence problems;(3) the sexual differences of the five latent variables(perceptions toward violence in general, non-assertiveness, prosocial behavioral tendency, school violence experience by peers, and conscientization of school violence problems; (4) the sexual differences of both direct and indirect correlates on conscientization of school violence problems. Research is based on a survey conducted with 526 adolescents (268 males and 258 females) from 16 middle schools located in different districts of the city of Pohang. In order to address the research questions, structural equation models on adolescents' conscientization of school violence are explored. A variety of tests are conducted (configural invariance, metric invariance and structural invariance, intercept invariance, critical ratio for difference test, multi-group analysis, latent mean analysis including Cohen's effect test). The major findings of the study support the significance of both direct effects and indirect effects of the four latent factors(perceptions of violence in general, non-assertiveness, prosocial behavioral tendency, school violence experience by peers). The individual prosocial behavioral tendency has a positive mediating effect on the enhancement of individual conscientization toward school violence problems. However, we fail to find the direct positive effect of individual violence experience on the conscientization of school violence problems. In conclusion, a range of practical implications for social workers and other related professionals who are engaged in helping out the adolescents with school violence by peers are suggested based on the study findings.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.31 no.1 s.49
• /
• pp.43-49
• /
• 2005

Recently, according as people who have sensitive skin increase, we've been giving more importance to the safety of cosmetics. Especially, preservative is known to be one of the main stimuli which cause side-effects of cosmetics. However, there have been few reports describing cell cytotoxicity, skin penetration, oil-aqueous phase partition, anti-microbial activity of preservatives and their correlation with skin irritation. The study is aimed to develop low irritable preservative system with phenoxyethanol, one of the most commonly used preservatives in cosmetics, considering various factors mentioned above. According to our results of cell cytotoxicity against human normal fibroblasts by means of MTT assay, phenoxyethanol showed the lowest cytotoxicity when compared to other preservatives tested (cytotoxicity: pro-pylparaben > butylparaben > ethylparaben > methylparaben > triclosan > phenoxyethanol), but human patch test for assessing shin primary irritation revealed that phenoxyethanol has higher skin irritation than methylparaben and triclosan. We performed in vitro skin penetration test using horizontal Franz diffusion cells with skin membrane prepared from hairless mouse (5 ${\~}$ 8 weeks, male) to evaluate the rate of skin penetration of preservatives. From the results, we found that the higher irritable property of phenoxyethanol in human skin correlates with its predominant permeability (skin penetration: phenoxyethanol > methylparaben > ethylparaben > propylparaben > butylfaraben > triclosan). Therefore, we made an effort to reduce skin permeability of phenoxyethanol and found that not only the rate of skin penetration of phenoxyethanol but also its skin irritation is dramatically reduced in formulas containing oils with low polarity. In the experiments to investigate the effect of oil polarity on the oil-aqueous phase partition of phenoxyethanol, more than $70\%$ of phenoxyethanol was partitioned in aqueous phase in formulas containing oils with low polarity, while about $70 {\~} 90\%$ of phenoxyethanol was partitioned in oil phase in formulas containing oils with high polarity. Also, in aqueous phase phenoxyethanol showed greater anti-microbial activity. Conclusively, it appears that we can develop less toxic preservative system with reduced use dosage of phenox-yethanol and its skin penetration by changing oil composition in formulas.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.31 no.1 s.49
• /
• pp.97-102
• /
• 2005

One of the key molecules involved in skin moisture is hyaluronan (hyaluronic acid, HA) with its associated water of hydration. The predominant component of the ECM (extracellular matrix) of skin is HA. It Is the primordial and the simplest of the GAGs (glycosaminoglycans), a water-sorbed macromolecule In extracellular matrix, Included between the vital cells of epidermis. In the skin, HA was previously thought to derive extlusively from dermis. But, recent studies revealed that HA could be synthesized in epidermis. Flavonoids are polyphenolic compounds that is found mainly in foods of plant origin. Kaempferol was known to increase glutathione synthesis in human keratinocyte. And quercetin blocked PPAR-meidated keratinocyte differentiation as lipoxygenase inhibitors. In this study, we sought to evaluate the effect of flavonid, kaempferol and quercetin on production HA in keratinocyte. We examined the changes of three human hyaluronan synthase genes (HASI, HAS2, HAS3) expression by semi-quantitative RT-PCR when kaempferol or quercetin was added to cultured human keratinocytes. We found that these flavonoids slightly upregulated HAS2, HAS3 mRNA after 24 h. And we investigated the effect on HA production by ELISA. When we evaluated the level of HA in culture medium after 24 h incubation. We found enhanced accumulation of HA in the culture medium. Although the effects of above flavonoids are less than retinoic acid, the data indicate that kaempferol, quercetin can dose-dependently increase the level of HA in epidermis cell line. It suggested that flavonoid, kaempferol, and quercetin increased production of HA in skin and it helped to elevate skin moisture and improve facial wrinkle.

• Korean Journal of Mineralogy and Petrology
• /
• v.34 no.3
• /
• pp.157-167
• /
• 2021

Lead (Pb) is one of the key trace elements, exhibiting a peculiar partitioning behavior into silicate melts in contact with minerals. Partitioning behaviors of Pb between silicate mineral and melt have been known to depend on melt composition and thus, the atomic structures of corresponding silicate liquids. Despite the importance, detailed structural studies of Pb-bearing silicate melts are still lacking due to experimental difficulties. Here, we explored the effect of lead content on the atomic structures, particularly the evolution of silicate networks in Pb-bearing sodium metasilicate ([(PbO)_x(Na₂O)_1-x]·SiO₂) glasses as a model system for trace metal bearing natural silicate melts, using ²⁹Si solid-state nuclear magnetic resonance (NMR) spectroscopy. As the PbO content increases, the ²⁹Si peak widths increase, and the maximum peak positions shift from -76.2, -77.8, -80.3, -81.5, -84.6, to -87.7 ppm with increasing PbO contents of 0, 0.25, 0.5, 0.67, 0.86, and 1, respectively. The ²⁹Si MAS NMR spectra for the glasses were simulated with Gaussian functions for Qⁿ species (SiO₄ tetrahedra with n BOs) for providing quantitative resolution. The simulation results reveal the evolution of each Qⁿ species with varying PbO content. Na-endmember Na₂SiO₃ glass consists of predominant Q² species together with equal proportions of Q¹ and Q³. As Pb replaces Na, the fraction of Q² species tends to decrease, while those for Q¹ and Q³ species increase indicating an increase in disproportionation among Qⁿ species. Simulation results on the ²⁹Si NMR spectrum showed increases in structural disorder and chemical disorder as evidenced by an increase in disproportionation factor with an increase in average cation field strengths of the network modifying cations. Changes in the topological and configurational disorder of the model silicate melt by Pb imply an intrinsic origin of macroscopic properties such as element partitioning behavior.

• Journal of Life Science
• /
• v.31 no.12
• /
• pp.1079-1087
• /
• 2021

To analyze gut microbiota of livestock in Korea and compare taxonomic differences, we conducted 16S rRNA metagenomic analysis through next-generation sequencing. Fecal samples from broiler chickens, pigs, and cattle were collected from domestic feedlots randomly. α-diversity results showed that significant differences in estimated species richness estimates (Chao1 and ACE, Abundance-based coverage estimators) and species richness index (OUTs, Operational taxonomic units) were identified among the three groups. However, NPShannon, Shannon, and Simpson indices revealed that abundance and evenness of the species were statistically significant only for poultry (broiler chickens) and mammals (pigs and cattle). Firmicutes was the most predominant phylum in the three groups of fecal samples. Linear discriminant (LDA) effect size (LEfSe) analysis was conducted to reveal the ranking order of abundant taxa in each of the fecal samples. A size-effect over 2.0 on the logarithmic LDA score was used as a discriminative functional biomarker. As shown by the fecal analysis at the genus level, broiler chickens were characterized by the presence of Weissella and Lactobacillus, as well as pigs were characterized by the presence of provetella and cattele were characterized by the presence of Acinetobacter. A permutational multivariate analysis of variance (PERMANOVA) showed that differences of microbial clusters among three groups were significant at the confidence level. (p=0.001). This study provides basic data that could be useful in future research on microorganisms associated with performance growth, as well as in studies on the livestock gut microbiome to increase productivity in the domestic livestock industry.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.47 no.4
• /
• pp.50-60
• /
• 2019

In the late 1980s, a financial crisis and Compulsory Competitive Tendering (CCT) in green space services brought with it a profound impact on the quality of parks in the UK. Such government projects, e.g. Urban Task Force (1999) and Public Parks Assessment (2001), aimed to raise the awareness of the severity of the declining standards of urban parks. Since the late 1990s, the UK governments (The New Labour (1997-2010) and The Conservative Government (2010-2019)), have often adopted community-led governance schemes to enhance the quality of parks and address problems derived from the financial crisis. Accordingly, community groups, notably 'Friends of', enlarged their involvement in the decision-making process of park management. However, there is little empirical evidence concerning the impact of community-led governance on park management, in particular, the effect on the users' perceptions of park use. This study explored the context of community-led park management to reclassify the level of build-up of governance underlined by 'A Ladder of Citizen Participation'. In addition, questionnaire surveys were conducted around two Sheffield district parks, which are located in deprived areas. As a result, community involvement in the status quo of UK urban park management has changed its form of governance based on the extent of involvement in the decision-making process. The forms of governance could be categorised in three levels: general, active, and predominant governance, where the extents of decision-making and sharing responsibility vary. The results obtained through the questionnaires show that one park (active governance), which has a stronger tendency of sharing responsibility to get involved in park management, had better contribution to park management and positive impacts on users' satisfaction than the other park (general governance). The findings highlight that stronger governance in partnerships with the non-public sectors can shed light on current and future park management through a shift in sharing responsibility for park management.

• Clean Technology
• /
• v.25 no.1
• /
• pp.46-55
• /
• 2019

CdS and CdZnS/ZnO materials were prepared using precipitation method and used as photocatalysts for the photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. The prepared photocatalysts were also characterized by XRD and UV-vis DRS. The results indicated that the photocatalysts with intended crystalline structures were successfully obtained and both the CdS and CdZnS/ZnO can absorb visible light as well as UV. The photocatalytic activities were examined with the addition of scavenger for various active chemical species and the difference of reaction mechanisms over the catalysts were discussed. The $CH_3OH$, KI and p-benzoquinone were used as scavengers for ${\cdot}OH$ radical, photogenerated positive hole and ${\cdot}O_2{^-}$ radical, respectively. The CdS and CdZnS/ZnO showed different photocatalytic degradation mechanisms of RhB. It can be postulated that ${\cdot}O_2{^-}$ radical is the main active species for the reaction over CdS photocatalyst, while the photogenerated positive hole for CdZnS/ZnO photocatalyst. As a result, the predominant reaction pathways over CdS and CdZnS/ZnO photocatalysts were found to be the dealkylation of chromophore skeleton and the cleavage of the conjugated chromophore structure, respectively. The above results may be mainly ascribed to the difference of band edge potential of conduction and valence bands in CdS, CdZnS and ZnO semiconductors and the redox potentials for formation of active chemical species.

• Korean Journal of Environmental Biology
• /
• v.36 no.4
• /
• pp.517-524
• /
• 2018

The purpose of this study was to investigate the density of thrips, and insecticidal resistance for effective control of Western flower thrips in greenhouse. The presence and density of the thrips was investigated using yellow colored-sticky trap in a cucumber field from May to August in Cheon-an. The results of the investigation revealed the existence of the following thrips species; Frankliniella occidentalis, F. intonsa, Thrips palmi, T. tabaci, Scirtothrips dorsalis, Microcephalothrips abdominalis, and T. nigropilosus. The predominant pest was found to be the western flower thrips. To survey the western flower thrips insecticidal resistance, we established the discriminating concentration (DC), recommended concentration (RC) and $2{\times}$recommended concentration ($2{\times}RC$) of nine insecticides; Emamectin benzoate EC, spinetoram SC, Chlorfenapyr EC, Spinosad SC, Cyantraniliprole EC, Acetamiprid WP, Dinotefuran WG, thiacloprid SC and thiamethoxam SC. The bioassay of about five local populations was conducted using the leaf-dipping method. In all local populations, insecticidal resistance in western flower thrips had not developed in emamectin benzoate EC (RC, $10.8{\mu}L\;L^{-1}$), chlorfenapyr EC (RC, $50.0{\mu}L\;L^{-1}$), spinetoram SC (RC, $25.0mg\;L^{-1}$), and spinosad SC (RC, $50.0mg\;L^{-1}$). However, insecticidal resistance in RC was found to have developed in cyantraniliprole EC (RC, $50.0{\mu}L\;L^{-1}$) and four insecticides of neonicotinoid type. Insecticidal activity of 95% or more was observed in each population when cyantraniliprole EC tested in $2{\times}RC$. However, the neonicotinoid types showed different insecticidal activity in $2{\times}RC$.

• Korean Journal of Environmental Biology
• /
• v.39 no.1
• /
• pp.46-54
• /
• 2021

The seasonal and vertical biomass of marine forest seaweeds were examined to select a suitable species at 12 sites of the South Sea in Korea between 2018 and 2019. The Habitat Suitability Index (HSI) was also calculated in terms of biomass for six species (three kelp and three Sargassum species). A total of 16 marine forest-forming species including four kelp and 12 Sargassum species were observed at the 12 sites. The average annual seaweed biomass by season and depth ranged from 843.73-2,925.85 g wet wt. m^-2 at the eastern South Sea and from 343.87-4,580.10 g wet wt. m^-2 at the western South Sea. In the kelp species, the Ecklonia cava biomass was predominant, followed by E. stolonifera. The macroalgal species with the greatest biomass was Sargassum macrocarpum, followed by S. horneri. The HSI values of E. stolonifera were between 0.76-1.0 at eight sites and those of E. cava were 0.58-0.92 at four sites, indicating that E. stolonifera was more suitable than E. cava. In the HSI values of the Sargassum species, S. horneri ranged between 0.84-1.0 at all 12 sites and the S. macrocarpum values were between 0.68-0.99. The results indicate that E. cava and S. macrocarpum were the most suitable for the marine forest construction in terms of the seaweed biomass, and E. stolonifera and S. horneri in terms of the HSI values. Thus, we suggest that seaweed biomass and HSI values should be considered when choosing suitable forest-forming species.