• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.3
• /
• pp.128-137
• /
• 2013

Due to the global warming and air pollution, interest in renewable energies has increased in recent years. In particular, the crisis of the depletion of fossil energy resources in the near future has accelerated the renewable energy technologies. Among the renewable energy resources, oceans covering almost three-fourths of earth's surface have an enormous amount of energy. For this reason, various approaches have been made to harness the tremendous energy potential. In order to achieve two purposes: to improve harbor water quality and to use wave energy, this study proposed a sea water exchange structure applying an Oscillating Water Column (OWC) wave generation system that utilizes the air flow velocity induced by the vertical motion of water column in the air chamber as a driving force of turbine. In particular, the airflow velocity in the air chamber was estimated from the time variations of water surface profile computed by using 3D-NIT model based on the 3-dimensional irregular numerical wave tank. The relationship of the frequency spectrums between the computed airflow velocities and the incident waves was analyzed. This study also discussed the characteristics of frequency spectrums in the air chamber according to the presence of the structure, wave deformations by the structure, and the power of the water and air flows were also investigated. It is found that the phase difference exists in the time series data of water level fluctuations and air flow in the air chamber and the air flow power is superior to the fluid flow power.

• Journal of the Korean earth science society
• /
• v.36 no.3
• /
• pp.222-235
• /
• 2015

Samples were collected from both places including the coastal area within the height of 5 m above the mean sea level (msl) (DH) and the top of the coastal terrace of 10-15 m msl (KS) high in Gwangseungri, Gochanggun, Korea. To find the origin of the deposit in the coastal area, granulometric analysis and geochemical analysis were performed. The result showed that the DH samples were originated from the reddish soils overlaying weathered bedrock which presented gradual change of chemical composition from the bottom toward the top. Clay minerals were found from the DH samples. These results concluded that the DH samples were found as in-situ weathered materials. The KS samples were originated from the soil layer covering gravel layer at the foot slope of the hill along the coast. The KS samples contained different chemical compositions from the DH. It is inferred that some of this layer was disturbed or experienced the influx of foreign material. The particle size of the KS samples was different from those found on the beach. The particle size of lower parts of KS site was finer than that on the beach, but the particle size of middle part of the site was coarser than that on the beach. The sorting of the KS site was poorer than that on the beach. Thus, it is inferred that some parts of the layer were formed by short-lived high energy event rather than sustained and continuous action of tidal currents and/or waves. Analysis using an optically stimulated luminescence (OSL) method showed that the burial age of samples from KS site were found 0.65-0.71 ka. Though the characteristics of the sediment layer and forming event in this area should be further studied, it can be inferred that this sedimentary layer formed by coastal flooding with storm.

• The Journal of Engineering Geology
• /
• v.26 no.4
• /
• pp.473-484
• /
• 2016

This study aims to establish a monitoring method for managing the effective maintenance of tailings dams. The monitoring of a tailings dump area involves several parameters and their investigation through a selection of evaluation items. The extents of defects and progressive failures also need to be effectively estimated. Therefore, the monitoring items can be subdivided into categories relating to the retaining wall structure (concrete wall, reinforcing stone wall, mesh gabions) and general facilities (liner, covering soil, slope, tailings, rain protection facility, leachate, planting), and quantitative evaluations can then be conducted for each condition. In doing so, we developed a systematic monitoring method that assesses the dam maintenance condition with grades and scores. The field application of the monitoring method results showed it to provide a more detailed evaluation than existing monitoring methods: the method detected an additional 16 defects missed by conventional methods. The evaluation gave scores of 89.3, 22.2, and 27.8 to the Geumjang mine tailings dam, the Gupoong mine tailings dam, and the Hwachun mine tailings dam, respectively. The advanced method can provide quantitative evaluation and perform detailed monitoring of the dams. This quantitative evaluation can be used to decide on maintenance priorities, select the main management items, and establish schedules of maintenance.

• Journal of the Korean Society of Groundwater Environment
• /
• v.1 no.1
• /
• pp.33-50
• /
• 1994

The Hydrogeologic data of 455 water wells comprising geologic log and aquifer test were analyzed to determine hydrogeologic characteristics of the Cheju island. The groundwater. of the Cheju island is occurred in unconsolidated pyroclastic deposits and crinker interbedded in highly jointed basaltic and andesic rocks as high level, basal and parabasal types under unconfined condition. The average transmissivity and specific yield of the aquifer are at about 29,300㎡/day and 0.12 respectively, The total storage of groundwater is estimated about 44 billion cubic meters. Average annual precipitation is about 3,390 million ㎥ among which average recharge is estimated for 1,494 million ㎥ being equivalent 44.1% of total annual precipitation with 638 million ㎥ of runoff and 1,256 million ㎥ of evapotranspiration. Based on groundwater budget analysis, the sustainable yield is about 620 million ㎥(41% of annual recharge)and rest is discharging into the sea. The geologic logs of recently drilled thermal water wells indicate that very low-permeable marine sediments(Sehwa-ri formation) composed of loosely cemented sandy silt derived from mainly volcanic ashes at the 1st stage volcanic activity of the area is situated at the 120${\pm}$68m below sea level. Another low-permeable sedimentary rock called Seogipo-formation which is deemed younger than the former marine sediment is occured at the area covering north-west and western part of the Cheju island at the ${\pm}$70m below sea level. If these impermeable beds art distributed as a basal formation of fresh water zone of the Cheju island, the most of groundwater in the Cheju island will be para-basal type. These formations will be one of the most important hydrogeologic boundary and groundwater occurences in the area.

• Journal of Environmental Science International
• /
• v.24 no.11
• /
• pp.1405-1415
• /
• 2015

This study is conducted to determine the damage, distinguish the types and identify the restoration by that type for 13 Korea national parks out of 21. There are 21 Korea national parks are in Korea covering 6.67% of the country or $6,656km^2$ ($3,902km^2$ on land and $2,754km^2$ in the sea) currently since the area around Jirisan ($440km^2$) was designated as the first Korea national parks in 1967. With the cancellation of entrance admission on Korea national parks since 2007, annual visitors to the Korea national parks have grown from 37 millions in 2008 to 46 millions by 2013 and continue to grow due to numerous leisure activities, alpine activities and social changes. As such, Korea national parks are natural resource with high value to be conserved and are attracting significant attention as recreational spaces for people at the same time. On the other hand, there have been issues of soil erosions or disturbed vegetation due to increased number of visitor to the national parks. Korea national parks area damage to its type and damage characteristics to analyse the 13 Korea national parks out of 21 on July 2012 March, Korea national parks over the subjects of the National Park from damaged area status Survey analysis by the Korea National Park Service. As a result, 203 million units in the 16 Korea national parks damaged land of the reform package during ecological trail (including non-regular hiking trails) 153 (77.66%), damaged valleys 20(9.14%) independent damaged area, 13 disconnected ecological axis(7.61%), closed trail(2.03%) (3.55%), and line type damage(like a non-regular hiking trails) appears to be a high ratio. Korea national parks damaged land of the results identified, by contrast ratio and the annual number of visitors Bukhansan national park(49.26%), Gyeongju national park(23.65%) damaged land rates, such as Seorasan national park(4.93%), Songnisan national park (4.43 %), Gyeryongsan national park(3.45%), and the annual number of visitors be similar result. The National Park Service has been reporting on damages and restorations but damages and their types have not been established yet. Damages have been generally studied and categorized on hiking trails due caused by heavy traffic on them but the reports were limited on hiking trails only. Since damage to the Korea national parks are not limited on the hiking trails, it is necessary to determine damages in various aspects. Thus, in this study, damage types, spatial characteristics, causes and restorations are analyzed based on the survey results of damages to national parks in order to provide a basis for the efficient management and operation of the Korea national parks.

• Research in Plant Disease
• /
• v.15 no.1
• /
• pp.1-7
• /
• 2009

Viruses diagnosed on crops including rice plants from farmers or agricultural extension agencies cover the country were 11 species including Broad bean wilt virus 2 (BBWV2) in 2008. Tomato spotted wilt virus (TSWV) was the most important virus having the detection rate of 22.9%. Two viruses of Tomato yellow leaf curl virus (TYLCV) and Tobacco leaf curl virus (TLCV) inducing leaf yellow and curl diseases on tomatoes were occurred newly with the detection rate of 12.2% and 4.0%, respectively, in 2008. Rice stripe virus (RSV) was occurred on 869.5 ha mainly at Jindo and Haenam areas in Jeollanamdo province. At Jindo area, 12 plots were damaged severely with the infected hill rate of 83.8%. At the main production area of oriental melon at Seongju, almost all fruits from whole sale market at Seongju were infected with Cucumber green mottle mosaic virus (CGMMV) as the detection rate of 87%. The areas occurred TSWV in Korea were 25 totally from 2003 including 7 areas newly reported in 2008 including Naju in Jeoallanamdo. TSWV could be reduced as 0.1 % from 5.3% by covering insect proof net in vinyl house after chemical soil sterilization. Tomato yellow leaf curl disease was occurred on April in 2008 at Tongyoung area in Kyeongsangnamdo, and detected continuously at 13 areas, 7 in Kyeongsangnamdo, 4 in Jeollabukdo and 2 in Jejudo. Potato spindle tuber viroid (PSTVd) was occurred abruptly in a confined space of a civil breeding greenhouse and a cultivar evaluation field followed by disuse 17.4 M/T of potato tubers. No PSTVd was detected at 17 fields cultivated the related potatoes to the bred company by RT-PCR.

• Korean Journal of Weed Science
• /
• v.32 no.3
• /
• pp.280-284
• /
• 2012

No-tillage direct seeding of rice is consumed less labor and oil energy by no plowing and rotary tillage. And it has other advantages of soil and water conservation and accumulation of organic matter on paddy surface due to crowded water foxtail (Alopecurus aequalis var. amurensis). When no-tillage seeding of rice, many water foxtail occurred in winter paddy field. In this experiment their covering degrees were 97.6% and 95.2% in clay loam and sandy loam paddy soils, respectively. Because of this, Stellaria alsine var. undulata, Cardamine flexuosa, Rorippa indica and Ixeris chinensis etc. annual and perennial wintering weeds occurrence was reduced. And annual weeds Chenopodium serotinum and Polygonum hydropiper that occurred early in spring were also reduced. As well as Echinochloa crusgalli var. praticola, Cyperus difformis, Monochoria vaginalis and Lindernia procumbens etc. summer annual weeds that occurred after irrigation were also reduced. In conclusion, no-tillage direct seeding of rice has another advantages of weed management by water foxtail.

• Journal of the Korean Geosynthetics Society
• /
• v.13 no.3
• /
• pp.1-10
• /
• 2014

Several types of methods such as resistivity survey, ground penetration radar, etc are used for detection of levee leakage and according to the river design guidelines detection of levee leakage is performed by measuring the hydraulic conductivity of levee soil. But, the former can not verify the leakage point and degree of saturation, the latter is an after treatment method. Movable sensor, which is a high-tech TDR system developed since 2000, can obtain directly the dielectric constant profile covering the whole depth of levee. In this study, laboratory and field model experiments were carried out using movable TDR sensor in order to evaluate the applicability as detection system of levee leakage, As the result, movable TDR system has proven to be 3 times more sensitive to water contents than dry unit weight, and the results conclude that the dielectric constant, water contents and density of the ground proved to have a correlation among them, and the dielectric constant is expected to be a basic data on detection of levee leakage.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.10 no.2
• /
• pp.84-96
• /
• 2007

The purpose of this study was to select herbaceous plants that can be used for presenting various views and biodiversity on the extensive rooftop greening. Experiment plots were constructed in July 2005 on the rooftop of the Administration Building in the Seoul Women's University. For this experiment, planters were used to design rooftop greening. The size of a planter is 500mm${\times}$500mm${\times}$100mm and each planter has the water storage plate in the lower part of it. The soil was constructed by mixing pearlite, vermiculite, cocopeat, and leaf mold in the ratio of 6 : 2 : 1 : 1. The plot was divided into the watered plot and the dry plot. Since each plot was constructed 2 times, finally 4 planters were constructed in total. One hundred species were used for the experiment and 9 plants per species were planted in each planter. Plants were organized according to types of plants and the experiment used 86 native herbaceous plants, 6 herbs, and 8 foreign plants. The plots were monitored once a month, from July to November 2005. The length and width of plants were tape-measured and covering rate was calculated by CAD program. "SPSS 10.1" was used for a statistical analysis. The result showed no significant difference between the watered plots and the dry plots. In cases of some plants, there were statistically significant differences between the watered planter and dry planter such as follows : Astilbe chinensis and Polygonatum odoratum which are shade plants were measured as the highest value on the watered pots, and Aquilegia buergeriana, Chrysanthemum zawadskii, Calendula arvensis and Gypsophila cerastioides D.Don which are sunny plants were measured as the highest value on the dry plots. According to the final analysis of the data collected and observed for growth condition during the first year of the research, 51 species including Prunella vulgaris var. lilacina and Veronica linaiaefolia in native herbaceous plant, 5 species with Lavandula angustifolia in herbs, and 3 species with Lantana camara and Muscari armeniacum in foreign plants showed the highest growth condition. In conclusion, it is suggested that various plants including sedums could be effectively used for extensive rooftop greening to improve landscape(a view) of the rooftop and increase ecological values.

• Resources Recycling
• /
• v.26 no.2
• /
• pp.80-88
• /
• 2017

Globally, there has been a lot of research related to recycling coal ash from power plant stations. This research is happening because there is a considerable shortage of sites for reclamation of increased coal ash every year. In addition, a variety of environmental pollutants have appeared because of mining activity. Abandoned coal mine, pits, and mine tailing piles caused pollutants to come to the surface resulting in serious damage for humans and the environment. Therefore in this study, we investigated whether or not coal ashes have the ability to prevent several environmental problems by mining in Korea and a manageable form recycling coal ashes. In overseas countries, there is a sufficient field of applicable cases where coal ash is used for neutralizing AMD (Acid Mine Drainage), covering of the waste materials, grouting, and soil amendments. However in Korea, since the coal ash is classified as a 'waste', there is an insufficient field applicable cases so far. Therefore it is necessary to establish a specific standard and management system for the utilization of coal ash based on the relevant precedent cases applied abroad in order to prevent environmental pollution caused by mining activity in Korea.