• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.54 no.2
• /
• pp.218-224
• /
• 2009

In organic fanning systems, integration of cover crops into cropping system are recommended to improve the soil quality, to prevent soil erosion, and to provide biological control of weeds. The aim of the present study was to evaluate the optimal seeding dates of major cover crops. To know optimal seeding dates, crimson clover, alfalfa, rye and hairy vetch were sown on 20. Sep., 27. Sep., 4. Oct., 11. Oct., 18. Oct., 25. Oct. Rye could germinate and grow well in all the tested sowing dates. Hence, it was concluded that the sowing of rye could be conducted later in fall or more earlier in spring than any other cover crops tested in this study. Growth and ground covering capacity were significantly decreased by late sowing in alfalfa and crimson clover. For safe overwintering, alfalfa and crimson clover should be sown before late September. Similarly, field emergence of hairy vetch was found to be sensitive to soil temperature, however, its growth and ground covering capacity after overwintering was enough to compensate the delay in sowing. Germination tests in laboratory revealed that hairy vetch grew faster at $25^{\circ}C$ compared to $20^{\circ}C$. The result suggested that germination and growth rate of hairy vetch was rapidly decreased at low temperature. Therefore, it is recommended that hairy vetch should be sown as soon as possible in September for improving stand establishment after overwintering.

• Journal of Wetlands Research
• /
• v.10 no.1
• /
• pp.59-68
• /
• 2008

Three phases of development in construction projects (i.e. pre-development, construction and post construction) diversely effect the environment, hydraulics and ecosystem. Currently, the domestic environmental policy is in control of the various environmental hazards produced after completion of development operations. Nevertheless, with the enforcement of water pollution total amount management system, improving the water quality; also the water and ecosystem preservation law recommends enforcing the sediment management for development operations in order to lessen the negative impacts to the environment. Recently, the country is experiencing difficulties in various development project locations due to insufficiency of interpreting the fundamental data for sediment loss and miscalculation of soil loss unit loads of sediment. This research utilizes data from 2000 to 2005 discussing a total of 1,036 environment impact assessment projects gathered from various ministries and offices namely Ministry of Environment (MOE), Ministry of Agriculture, the Office of Forestry, and Ministry of Construction and Transportation. Moreover, quantity of sediment from high land agriculture reports involving contaminant discharge characteristic investigation previously did concerning old land agriculture and So-Yang lake non-point pollution source management area as well as management measured data from MOE. The findings of this study reveal that the highest soil loss rate occurred from mountain district for pre-development and post construction and sports facility during construction.

• Journal of the Korean Vacuum Society
• /
• v.16 no.2
• /
• pp.79-90
• /
• 2007

Prototype of $800{\ell}$ vacuum web coater (Vic Mama) consisting of ion source with low energy less than 250 eV for high speed surface modification and 4 magnetron sputter cathodes was designed and constructed. Its performance was evaluated through fabricating the adhesiveless flexible copper clad laminate (FCCL). Pumping speed was monitored in both upper noncoating zone pumped down by 2 turbo pumps with 2000 l/sec pumping speed and lower surface modification and sputter zone vacuumed by turbo pumps with 450 1/sec and 1300 1/sec pumping speed respectively. Ion current density, plasma density, and uniformity of ion beam current were measured using Faraday cup and the distribution of magnetic field and erosion efficiency of sputter target were also investigated. With the irradiation of ion beams on polyimide (Kapton-E, $38{\mu}m$) at different fluences, the change of wetting angle of the deionized water to polyimide surface and those of surface chemical bonding were analyzed by wetting anglometer and x-ray photoelectron spectroscopy. After investigating the deposition rate of Ni-Cr tie layer and Cu layer was investigated with the variations of roll speed and input power to sputter cathode. FCCL fabricated by sputter and electrodeposition method and characterized in terms of the peel strength, thermal and chemical stability.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2007.12a
• /
• pp.141-142
• /
• 2007

In recent years, the rate of mean sea level rise is increasing rapidly from the phenomena of global warming, together with the increasing trend of the storm scale. The issue of sea level rise is multifaceted and produces a range of environmental problems. Especially, high tides and the tidal currents become higher, and wave base increases, so the energy received at the coastal boundary may increase. This brings that many coastal environments go into disequilibrium, such as damages to the structures, erosion, and deposition Similarly it was known that the problems of nearshore processes and damage of berth and counter facilities during storm period had appeared at the small fishery port. Here we try to analyze the impact of the rearrangement of counter facilities and berth layout adopted for tranquility of its'inner harbor. Because this harbor is being connected to channel and open sea, the rearrangement of the structures might affect to the current speed and direction and wave height, so do to the sea bottom undulation. Therefore, we made model test for the several layouts of the berth and breakwater in this area.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.7
• /
• pp.33-38
• /
• 2017

The number of damaged lifeline structures have been increasing with urban acceleration under earthquakes. To predict the damage, damage mitigation technology of lifeline structures should be analyzed using damage prediction technology. Therefore, in this paper, the degree of the fragility of structures under an earthquake was evaluated stochastically through an evaluation of the seismic fragility. The aim was to develop damage prediction technology of sewage pipes among the lifeline facilities. The site response was performed using the data from 158 boreholes in Seoul and 7 real earthquake waves to determine the responses in real urban areas. The seismic fragility was deduced through a total of 29822 time history analysis. In addition, sewer pipes were evaluated and the persisting period was passed by applying the research results of strength reduction which is due to sulphate erosion. As a result, the difference in failure probability between 300 and 800 with the smaller diameter of the representative pipes was approximately double and the size of the pipes has a significant effect on the seismic fragility function. Moreover, the failure probability of a seismic load increases by up to 10 fold as the strength reduction rate increases. The results of this study can be used as a means of predicting the damage and countermeasures of sewer pipes and might be reflected in the seismic design of underground facilities.

• Radiation Oncology Journal
• /
• v.5 no.1
• /
• pp.1-11
• /
• 1987

Total 390 mice were irradiated with $2{\times}3cm$ abdominal field and $200{\times}5/wk$ regimen with orthovoltage x-ray machine. All animals were divided into 2 large groups, damage and recovery, and histopathologic changes were analyzed at various total dose level (1,000 cCy-5,000 cCy) and intervals (1 week-15 weeks). Almost acute changes such as decreased mitotic activity, villi shortening and focal erosion of mucosa recovered within 1-2 weeks in 1,000-3,000 cGy irradiated group but mild changes persisted in 4,000 and 5,000 cCy irradiated groups. Chronic delayed changes such as thickening of vessel wall with focal thrombosis, submucosal fibrosis, mucosal atrophy and chronic ulcer were observed from 2-3 week specimens in 4,000 and 5,000 cGy groups, These late changes recovered slightly, as increasing time intervals after irradiation but mild, persistant changes were observed throught all follow up period. These data suggest hat even 4,000 cCy is not completely safe for possible permanent damage and judicious modificiation of total dose, dose rate, fraction size, and field size should be considered for better results.

• Journal of the Mineralogical Society of Korea
• /
• v.27 no.3
• /
• pp.107-114
• /
• 2014

In this study, we tried to determine the origin of fine-grained sediments in Southeastern Yellow Sea Mud patch (SEYSM) using principal component analysis coupled with semi-quantitative X-ray diffraction analysis for 4 major clay minerals. We used 51 marine surface sediments from SEYSM and 33 surface sediments of rivers flowing into the Yellow Sea. We made bioplot diagram using R program with principal component 1 and component 2 because the two components might contain about 98% of all data. The content of each clay mineral in the south and north regions of SEYSM are almost similar. In the biplot, SEYSM sediments distribute close to Korean rivers sediments than Huanghe and Changjiang sediments. Based on these results, we suggest that SEYSM is originated from the Korean rivers sediments. The higher accumulation rate in the SEYSM compared to the sediment discharge from neighboring Korean rivers can be explained by erosion and reworking of surface sediments in this area. The principal component analysis can be used for the provenance research of marine sediments around the Korean Peninsula.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.21 no.3
• /
• pp.48-62
• /
• 2018

In this study, landslide of debris flow occurred at 51 sites around Daeryounsan located in between Chuncheon-si and Hongcheon-gun during July in 2013 were investigated in field and behavior characteristics of debris flow were analyzed on the basis of records of rainfall and site investigation. According to debris flow types of channelized and hill slope, location and slope angle of initiation and deposit zone, and width and depth of erosion were investigated along entire runout of debris flow. DEM(Digital Elevation Model) of Daeryounsan was constructed with digital map of 1:5,000 scale. Land slide hazard was estimated using SINMAP(Stability INdex MAPping) and the predicted results were compared with field sites where debris flow occurred. As analyzed results, for hill slope type of debris flow, predicted sites were quite comparable to actual sites. On the other hand, for channelized type of debris flow, debris flow occurrence sites were predicted by using stability index associated with topographic wetness index. As analyzed results of 4 different conditions with the parameter T/R, Hydraulic transmissivity/Effective recharge rate, proposed by NRCS (Natual Resources Conservation Service), predicted results showed more or less different actual sites and the degree of hazard tended to increase with decrease of T/R value.

• Journal of Environmental Science International
• /
• v.19 no.11
• /
• pp.1423-1436
• /
• 2010

The effects of meteorological and reclaiming conditions on the reduction of suspended particles are investigated using a computational fluid dynamics (CFD) model with the k-$\varepsilon$ turbulence closure scheme based on the renormalization group (RNG) theory. Twelve numerical experiments with different meteorological and reclaiming conditions are performed. For identifying the meteorological characteristics of the target area and providing the inflow conditions of the CFD model, the observed data from the automatic weather station (AWS) near the target area is analyzed. Complicated flow patterns such as flow distortion, horse-shoe vortex, recirculation zone, and channeling flow appeared due to the topography and buildings in the domain. Specially, the flow characteristics around the reclamation area are affected by the reclaiming height, reclaiming size and windbreak height. Reclaiming height affected the wind speed above the reclaiming area. Windbreak induces more complicated flow patterns around the reclaiming area as well as within the reclaiming area. In front of the windbreak, flow is distorted as it impinges on the windbreak. As a result, upward flow is generated there. Behind the windbreak, a secondary circulation, so called, a recirculation zone is generated and flow is reattached at the end of the recirculation zone (reattachment point). At the lower part of the recirculation zone, there is a reverse flow toward the windbreak. Flow passing to the reattachment point starts to be recovered. Total amounts of suspended particles are calculated using the frictional and threshold frictional velocities, erosion potential function, and the number of surface disturbance. In the case of a 10 m-reclaiming and northerly wind, the amount of suspended particles is largest. In the presence of 5 m windbreak, the friction velocity above the reclaiming area is largely reduced. As a result, the total amount of the suspended particles largely decreases, compared to the case with the same reclaiming and meteorological conditions except for the windbreak The calculated suspended particle amounts are used as the emission rate of the dispersion model simulations and the dispersion characteristics of the suspended particles are analyzed.

• Journal of Korean Society of Forest Science
• /
• v.109 no.1
• /
• pp.81-98
• /
• 2020

In this study, forest-related research papers published in North Korean journals were analyzed to understand the research trends in North Korean forest science. The Korea Science and Technology Information Institute (KISTI) North Korea Science and Technology Network (NKtech) is constructing a database related to science and technology in North Korea. From this, a total of 1,389 articles published from 1962 to 2016 were collected with forest science key words based on the South Korean National Science and Technology Standard Classification System. The topics were divided into four categories: afforestation, forest protection, forest use, and forest management. In the field of afforestation, research activities on nursery and agroforestry were active, and the survival rate was emphasized. In the forest protection field, there was a significant research effort into forest pests, and efforts were being made to reduce soil erosion through agroforestry. In the field of forest use, research activities on pulp/paper and mushrooms were active. In the forest management field, activities related to "ecological information" were conspicuous, and efforts were being made to reduce carbon. These results suggest that the perspective of North Korean forest research has changed from nature reorganization to nature protection. Thus, a comparative study on forest science and technology in each sub-sector of the forest research field, along with analysis of the relationship between policy direction and research direction of North Korea over time, would be worthwhile future investigations. To overcome the problem of technical terminology, a compilation/dictionary of inter-Korean forestry terminology would be useful for effective communication between the two Koreas.