• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.261-270
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• 2002

The artificial aeration in the middle and the small scale reservoirs is widely used to destroy the stratified layer and algal boom. This study has been conducted at the Youncho reservoir located in Keoje island since Jan. 2000 to suggest the most suitable control strategy of the artificial aeration and reduce the side effect. The main results obtained from this research are as follows. The starting time of aeration for destratification was adjusted from the end of March to the beginning of April when the natural stratification is started. In order to prevent an anoxic condition the artificial mixing should be started by the middle of April when the DO in hypolimnion is dropped to less than $5mg/{\ell}$. The decrease DO, caused by the increase in water temperature, spreads rapidly from hypolimnion to themocline. Thermal stratification disappeared after the onset of artificial aeration within 7 days in the Yuncho reservoir. The air diffusers decrease water temperature in the layer of epilimnion and thermocline, but rise it in hypolimnion. The continuous operation of air diffuser prevent the stratification and anoxic condition in hypolimnion despite of the rising of water temperature and algal abundance. The algal abundance is not observed in effective zone by aeration. The turbidity rising problem induced from the aeration is avoided by keeping an air diffuser about 1.5m high from the bottom of lake. During the summer season, ceasing the aeration should be decided carefully. And also, it is necessary to operate the system it considering weather and temperature, and depending on the number and the position of aerators.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.190-200
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• 2022

In this study, the island's land-use and land-cover change (LULCC) is analyzed in South Korea using remotely sensed land cover data(Globeland 30) acquired from 2000 to 2020 to meet the requirement of providing practical information for forest management. Analysis of LULCC between the 2000 and 2020 images revealed that changes to agricultural land were the most common type of change (7.6% of pixels), followed by changes to the forest (5.7%). The islands forests maintain 157,246 ha (42.2% of the total island area). Land cover types that changed to the forest from grasslands were 262 islands, while reverse cases have occurred on 421 islands. These 683 islands have a possibility of transition and disturbance. The artificial land class was newly calculated in 22 islands. The forests, which account for 42.2% of the 22 island area, turned into grassland, and 27.8% of agricultural land and grassland turned into forests. The development of artificial land often affects developed areas and surrounding areas, resulting in deforestation, management of agriculture, and landscaping. This study can provide insights concerning the fundamental data for assessing ecological functions and constructing forest management plans in islands ecosystems.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1134-1139
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• 2005

Seismic motion amplification owing to the input motion level at bedrock is one of the important topics to understand various geomaterials behavior. The extremely valuable borehole records at Port Island were obtained during the 1995 Hyogoken Nanbu Earthquake and also before and after the main event. In this study, the seismic motion amplification at the soft reclaimed ground was discussed. Comparison of measured records with numerical simulation results were made with focus on seismic motion amplification characteristics at the soft reclaimed ground.

• The Korean Journal of Ecology
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• v.4 no.3_4
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• pp.80-92
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• 1981

The vegetation of Saeng-il Island was surveyed over four times from July, 1979 to May, 1981. The results obtained are summarized as follows: Plants of this island consisted of 3 foma, 28 varieties, 211 species, 203 genera, and 89 families. Evergreen broad-leaved trees consisted of 24 species, including Camellia japonica and Castanopsis cuspidata var. sieboldii. The vegetatiion of the southwest slope was more favorable than that of the northeast slope and the vegetation of other areas were negligible. Pueraria thunbergiana and Clerodendron trichotomum were predominant in the area between Yucheon-ri and Geummo-ri. Evergreen broad-leaved trees, such as Camellia Japonica, Neolitsea sencea, Castanopsis cuspidata var. sieboldii, etc. were predominated in the areas of Gulzeon-ri, Yongchul-ri and Geummo-ri. However, artificial succession to pinus thunbergii presently dominating the areas has taken place due to human interferences (for charcaol, building materials, grazing etc.). It seems to be worthy of conserving the community of Camellia japonica on the back slope of Geummo-ri and that of Castanopsis cuspidata var. sieboldii between Gulzeon-ri and Hangdo-dong. It is notceable, in particular, that Damnacanthus indicus distributed in Jeju and Dolsan islands was also discovered in this island.

• Archives of Reconstructive Microsurgery
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• v.10 no.2
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• pp.163-168
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• 2001

The defects of the abdominal wall could be brought about either congenitally, for instances in such cases as omphalocele or gastroschisis, or by various acquired causes-trauma, excision of tumors, excision of burn scar, tissue necrosis caused by infection, hematoma after abdominal surgery, tissue necrosis after radiation therapy and so on. As for the techniques of the reconstruction of the abdominal wall defects, many authors have developed and reported diverse methods. To summarize, primary closure, skin graft, local skin flaps, various myocutaneous flaps, free flap, fascia graft, artificial mesh, tissue expansion, etc could be used in the reconstruction of the abdominal wall defects. The periumbilical perforator-based island skin flap has a many advantages such as no significant sacrifice of the rectus abdominis muscle, wide rotation arc, reliable blood flow of the perforator, short elevation time for flap, and for middle-aged, obese patients, the donor site may be the best from the cosmetic point of view. We used perforator-based island skin flap in 5 cases with reasonable result from March 1999 to May 2001. There were no significant complications and donor sites could be repaired primarily.

• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.16-22
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• 2003

The mechanical characteristics of newly recycled aggregate concrete on the basis of the proposed mix design model have been studied to develop the precast artificial fishing reefs. In the first task, the experimental test for the recycled aggregates taken from Jeju Island has been carried out to verify the material properties in terms of specific gravity, percentage of solids, absorption and abrasion of coarse aggregates. In the second task, the experimental parameters of newly recycled aggregate concrete are investigated to meet with the requirements of guidelines with respect to slump, unit weight, pH, ultrasonic velocity, void ratio, and compressive strength which are made of sea-shore sand ad slag cement. The natural aggregate and polypropylene fiber are added to newly recycled aggregate concrete to improve the compressive strength and quality. The optimal mix proportions for compressive strength are W/C=30％, S/a=15％, NA/G=50％ in porous concrete case, W/C=40％, S/a=45％ in plain concrete case, and W/C=40％, S/a-45％, PF=1.0kg/㎥ in fiber reinforced concrete case.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.948-955
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• 2005

In this case of study, Incheon International Airport 2nd phase site preparation 1st section estimated final settlement to improve soft ground. Final settlement is very important in preloading method. Recently, Hyperbolic method, Hoshino method and Asaoka method are used mostly in prediction of final settlement and this paper, Comparing a result of Final settlement, used to Artificial Neural Network. The structure of Dynamic Artificial Neural Network which predicted Final settlement, has application to Young_Jong Island other site, If new investigation data will be added. Also, It is expected to save measuring_system cost in soft ground.

• The Korean Journal of Malacology
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• v.27 no.1
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• pp.29-33
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• 2011

This study was conducted to investigate the recruitment pattern of sessile organisms on the artificial substrates of PVC in Jangmok Bay, Geoje Island, southern coast of Korea. Five PVC plates were submerged from March to October, 2007 at one month interval, and two plates were retrieved after one month. The dominant recruiters were a green algae, Entermorpha prolifera in March, Mytilus galloprovincialis in April, M. galloprovincialis and Styela plicata in May, S. plicata and Bugula sp. in June. During August, Balanus amphtrite and anthozoans were dominant recruiters, and a serpulid worm, Hydroides ezoensis in October. There was a clear specific recruiting period of sessile faunas depending on their reproduction cycles in a sheltered embayment like Jangmok Bay.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.1
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• pp.31-44
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• 2024

The coastal dune ecosystem is one of the ecosystems under the most development pressure in Korea. Therefore, it is necessary to study the ecological location and related ecological phenomena of coastal dune plants, but related studies are lacking. Through this study, we intend to conduct research on the structure and restoration of dune plants, focusing on the coastal dunes in Jeju Island, which are affected by artificial development pressure and the continuous increase in tourists among many coastal dunes in Korea. Ecosystems of coastal sand dunes for vegetation survey in Jeju Island are selected based on naturalness and preservation. In this study, 23 major coastal dunes on Jeju Island including Udo were selected. In the coastal dunes of Jeju Island, a whole species survey and quadrat survey were carried out. The vegetation survey at study sites were conducted on May to September 2022, when the vegetation is clearly visible. At the survey site, the dune area was identified at the beginning and the plant species were recorded until no more new species appeared. Vegetation survey in the field was performed by 103 quadrat establishments and was conducted using Braun-Blanquet method. A total of 277 species appeared, and the most common species were Vitex rotundifolia and Calystegia soldanella. The frequency of both Vitex rotundifolia and Calystegia soldanella was approximately over 90%. The proportion of woody and herbaceous in all emerging species was 7.2% and 92.8%, respectively. The total number of species found in the quadrat survey was 98. As a result of classifying plant communities based on species dominance in the quadrats, it was analyzed into 30 plant communities. The plant communities that appeared with a frequency of 2 or more on the main island of Jeju were Vitex rotundifolia, Imperata cylindrica var. koenigii, Ischaemum antephoroides, Wedelia prostrata, Elymus mollis, Calystegia soldanella, Artemisia scoparia, and Tetragonia tetragonoides. The DCCA(detrended canonical correspondence analysis) based on the vegetation and environment factor matrix showed that the height and covers of the dominant plant species explain significantly the variation and distribution of coastal sand dune species on Jeju island. Thus, we may propose a plan to restore the coastal dunes of Jeju island as helping colonization and establishment of mainly sand dune native perennials and trees, preserving native plant communities that are declining and preserving present tree strips of Pinus thunbergii, Litsea japonica, Pittosporum tobira and Vitex rotundifolia.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.88-97
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• 2009

In these days, it attracts our attention to create a green outdoor environment around the building block in urban area. Green space and permeable ground covering are increased by laws and regulations. According to these trends, variety researches for improving outdoor environment are accomplished at this moment. However, the problems for outdoor environment such as heat island effect and air contaminant in urban area are still reported. The purpose of this study is to examine the variables to affect the formation of outdoor thermal environment by quantitative analysis. As a initial study, in this paper, the effect of ground composition on changes of surface temperature and heat flux in multi-residential building were analyzed by field measurement and numerical simulation. Through field measurement, the surface temperature and heat flux of artificial ground in multi-residential building in Suwon city were measured. The result showed that the surface temperature was decreased by about $20^{\circ}C$ with afforestation of artificial ground compared with those of concrete covering. Moreover, the inner temperature of artificial ground was changed as same behaviors of outdoor temperature changes to depths of 20cm. In simulation, the effect of soil types and depth of artificial ground on the changes of the surface temperature and heat flux were analyzed. As results, the natural soil ground was more effective against lowering the surface temperature than any other cases in the analyzed cases.