• Korean Journal of Plant Taxonomy
• /
• v.43 no.4
• /
• pp.274-284
• /
• 2013

This study presents a survey on the bryophytes in Dongbaek-dongsan located at Seonheul Gotjawal on the north-eastern face of Mt. Halla in Jeju Island, Korea. A total of 85 taxa belonging to the Bryophyta (22 families 44 genera 62 species), Marchantiophyta (12 families 16 genera 23 species) were found. Among them, 3 moss species, Diphyscium perminutum Takaki, Racomitrium japonicum Dozy & Molk., and Isopterygium minutirameum (M$\ddot{u}$. Hal.) A. Jaeger. were new additions to the bryophyte flora of Korea. The liverwort index was 27.0%. Predominant life-form was weft. The rates for the bryophytes dominating in mesic to hygric sites were higher than for the bryophytes mainly observed in xeric habitats. We considered that the composition and distribution of species are affected by the different environmental factors according to the evergreen broad-leaved forests, wetlands and exposed spaces. Moreover, the rocks were the substrate type that play a major role in providing the micro-habitats for bryophytes in this area. Particularly, the bryophytes of swamps in this area were very unique and various for its limited space and showed plant communities with mosaic spatial pattern, along with vascular plants. We suggest more detailed and comprehensive studies on the swamps where endemic fern Mankyua chejuense B. -Y. Sun, M. H. Kim & C. H. Kim inhabits to provide valuable information for the conservation and restoration of the species and habitats.

• Korean Journal of Environmental Biology
• /
• v.38 no.3
• /
• pp.355-370
• /
• 2020

We conducted a field survey to analyze the ecological structure and spatial distribution of microplankton (phytoplankton and ciliates) in relation to water masses at 21 stations on the surface and chlorophyll-a maximum layers (CML) in the Northern East China Sea (nECS; 32°-33°N; 124°00'-127°30'E) from August 3 to August 6, 2019. The results showed that the water masses were divided into Chinese Coastal Waters (CCW) and the Tsushima Warm Current (TWC). The CCW showed the environmental characteristics of high temperature and low salinity, and the TWC showed high temperature and high salinity. The characteristics of the phytoplankton community in the CCW showed various community structures related to the nutrients supplied from the large rivers of the Chinese continent. However, the TWC had simple community structures because it originated near the equator and moved northward. The standing crops of phytoplankton and ciliates were very high in the CCW but showed low at the TWC. In particular, from the higher standing crops of protozoa than plant plankton at the TWC, the energy flow at the lower tropic levels caused by the microbial loop that fed on heterotrophic bacteria played an important role in the production of resource organisms. In other words, the marine ecological structure of the nECS in summer could be estimated as a bottom-up system at the CCW and a top-down system at the TWC.

• Journal of Wetlands Research
• /
• v.12 no.1
• /
• pp.41-49
• /
• 2010

Web building of the spider is an investment behavior for prey foraging with genetic constraint. Individual's decision-making on the web construction depends on diverse environmental variables. This study investigated web structure of the wasp spider, Argiope bruennichi, to compare individual's behaviors in dry field and in wet field. We measured 35 web structures in dry field (Chunma-San, Incheon) showing relatively low humidity (46.4%) and luxuriant herbage, and 13 web structures in the wet rice field (73.9%; Taean-Gun, Chungnam). Comparing to the wet field the individuals in the dry field invested significantly more silk: $32.5{\pm}12.8$ number of silk spirals used in the dry field vs. $16.9{\pm}5.4$ in the wet field. The web area of the dry field was greater than that of the wet field: $976{\pm}643cm^2$ vs. $532{\pm}254cm^2$. The web height, distance between the ground and the center of the web, appeared higher in the dry field than in the wet field: $71.4{\pm}39.6cm$ vs. $49.6{\pm}31.2cm$. Also the web constructed in the dry field showed longer stabilimentum than the web of the wet field: $18.8{\pm}3.4cm$ vs. $3.9{\pm}3.2cm$. The perpendicular inclination and the inclination to East-West of the web showed no difference between the two fields. This study suggests that adult females of A. bruennichi could modulate its construction behavior depending on the micro-habitat factors.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.8
• /
• pp.125-135
• /
• 2008

Rigid-soft particle mixtures, which consist of sand and rubber, are investigated for the understanding of the stress-deformation and elastic moduli. Specimens are prepared with various size ratio sr between sand and rubber particles, and different volumetric sand fraction sf. Small strain shear waves are measured under $K_o$-loading condition incorporated with the stress-deformation test by using oedometer cell with bender elements. The stress-deformation and small strain shear wave characteristics of rigid-soft particle mixtures show the transition from a rigid particle behavior regime to a soft particle behavior regime under fixed size ratio. A sudden rise of $\Lambda$ factor and the maximum value of the $\zeta$ exponent in $G_{max}=\;{\Lambda}({\sigma}'_{o}/kPa)^{\zeta}$ are observed at $sf\;{\approx}\;0.4{\sim}0.6$ regardless of the size ratio sf. Transition mixture shows high sensitivity to confining stress. The volume fraction for the minimum porosity may depend on the applied stress level in the rigid-soft particle mixtures because the soft rubber particles easily distort under load. In this experimental study, the size ratio and volumetric sand fraction are the important factors which determine the behavior of rigid and soft particle mixtures.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.2
• /
• pp.153-160
• /
• 2023

In this study, nano-sized C-S-H crystals were synthesized using the liquid phase reaction method and their properties were investigated. The synthesized C-S-H crystals were added to the cement composite in suspension form to determine their effect on the hydration properties of the cement. The amount of chemical admixture was varied to obtain nano-sized C-S-H crystals with optimal agglomerated morphology, and SEM photographs were analyzed. A cleaning process was added to remove harmful substances other than the synthesiz ed C-S-H crystals. It was found that the concentration of harmful substances was reduced in the case of C-S-H crystals subjected to the cleaning process. The synthesized C-S-H suspensions were prepared with and without the cleaning process, and cement composites were prepared with the cement weight content as the main variable. The effect of C-S-H crystals on the initial hydration properties of the cement was confirmed by microhydration heat analysis. In addition, mortar specimens were prepared to measure the compressive strength over time. The test results showed that the nano-sized C-S-H crystals act as nucleation sites in the cement paste to promote the early hydration of the cement and increase the early compressive strength.

• Korean Journal of Environmental Biology
• /
• v.35 no.2
• /
• pp.198-206
• /
• 2017

From June 2007 to May 2008, seasonal variations of bacterial abundance and heterotrophic nanoflagellate (HNF), together with environmental factors, were investigated at weekly and monthly intervals in Kyeonggi Bay. During the study period, the water temperature and salinity varied from $1.9^{\circ}C{\sim}29.0^{\circ}C$ and 31~35.1 psu, respectively. The concentration of ammonia, nitrate+nitrite, phosphate, and silicate ranged from 0.01 to $3.22{\mu}M$, 2.03 to $15.34{\mu}M$, 0.06 to $1.82{\mu}M$, and 0.03 to $18.3{\mu}M$, respectively. The annual average concentration of Chl. a varied from $0.86{\mu}g\;L^{-1}$ to $37.70{\mu}g\;L^{-1}$; the concentration was twice as much at the surface than at the deeper layers. The abundance of bacteria and HNF ranged from $0.29{\times}10^6$ to $7.62{\times}10^6cells\;mL^{-1}$ and $1.00{\times}10^2$ to $1.26{\times}10^3cells\;mL^{-1}$, respectively. In particular, there were significant correlations between bacteria and HNF abundance (p<0.05), and then the high abundance of HNF was frequently observed with an increase of bacterial abundance in summer (p<0.001). Our results therefore indicate that bacterial abundance in the bay was mainly controlled by resources supplied as organic and inorganic substances from Lake Shihwa due to the daily water exchange after dike construction. Also, the bacterial abundance was significantly controlled by HNF grazing pressure (top-down) in the warm seasons, i.e. excluding winter, in the Kyeonggi Bay.

• Journal of the Korean Geographical Society
• /
• v.51 no.2
• /
• pp.185-200
• /
• 2016

The discipline of Geography is broadly concerned with the interconnections between people and the environment. Particularly, this unique human-environment relationship often can be typically reflected from, and well illustrated by, the dynamics of microstates' island environment. While Tuvaluans living on vulnerable, low-lying atolls in the Pacific are not primarily responsible for contributing to climate change, yet they are experiencing its dreadful effects. Population pressure, caused by the differences in population size, distribution, and composition, has been constantly affected by resource unavailability and environmental instability on the islands. It also represents one of our challenges in understanding the complex influence of population dynamics on the living environment. What can be learned from Tuvalu in the context of population geography and environmental geography as well as its relationship with other Pacific island microstates? What are Tuvaluans' migration responses to their atolls' environmental crisis as well as the carrying capacity scenarios related to overpopulation? What are the current living experiences and settlement situations of Tuvaluan internal and external migrants both at home and abroad? This research examines the contemporary migration literature in the context of Tuvalu's population geography, while analyzing Tuvaluan migration patterns, discourses and perspectives in relation to environmental change.

• Journal of Digital Convergence
• /
• v.17 no.6
• /
• pp.427-431
• /
• 2019

The purpose of this study was to investigate whether the mirror environment influences the attitude of the client when counselling. A group of 16 experimenters, 16 controls, a group with a mirror environment, and 32 men and women according to the presence or absence of interventional mirror environments in the control group. There was a statistically significant difference in the 'self - alienation' factor of the Authentic Scale(AS) in the experimental group that provided the mirror environment. There was no significant difference in the Semantic Differential Scale(SDS) between the experimental group and the control group. This study was conducted to investigate whether the presence of the mirror environment affects the client 's authenticity. There were significant differences in some of the factors of the Authentic Scale.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.6
• /
• pp.1209-1216
• /
• 2020

In this study, we propose a method for detecting coastal surface wastes using an UAV(Unmanned Aerial Vehicle) remote sensing method and an object detection algorithm based on deep learning. An object detection algorithm based on deep neural networks was proposed to detect coastal debris in aerial images. A deep neural network model was trained with image datasets of three classes: PET, Styrofoam, and plastics. And the detection accuracy of each class was compared with Darknet-53. Through this, it was possible to monitor the wastes landing on the shore by type through unmanned aerial vehicles. In the future, if the method proposed in this study is applied, a complete enumeration of the whole beach will be possible. It is believed that it can contribute to increase the efficiency of the marine environment monitoring field.

• The Journal of the Korea Contents Association
• /
• v.13 no.1
• /
• pp.234-246
• /
• 2013

Microcredit was first introduced by non-profit organization in early 2000s and the Ministry of Health and Welfare promoted the support policy of self-support community and the hope-developing bank. And then, microcredit policy was suddenly changed while the microfinance policy was promoted in 2009. For example, there were changes of the control tower of the policy, the emphasis on financial approach from welfare approach, the establishment of the operation agency. This study analyzed the policy changes on microcredit policy using the framework of Hood(1994) and Joo(1999) in order to analyze causes of sudden changes. As results, the reason affecting microcredit policy change was changes of an unemployment rate and the financial environment, the change of outside situation, the policy idea of the middle practicalism of government and the success of the experiment in microcredit, the passive intervention of stakeholders, the internal factors on the policy custom. So the results suggests that the policy is produced illogically because of the absence of stakeholders' participation.