• Journal of the Korean Geotechnical Society
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• v.27 no.5
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• pp.5-15
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• 2011

Recent increase of large scale construction near costal area has also increased the application of soft ground treatment. As a result, solidification with cement and lime which increases stability and durability of soils, is frequently used for surface layer stabilization in soft ground site. While stabilization of very soft clay with high plasticity and compressibility has widely been studied, studies on silty clay with low plasticity and compressibility are relatively rare. In this study, after stabilizing low plasticity silty clay of Songdo area with cement and lime under various water contents, mixing ratio, and curing time, uniaxial compression test and plate load test were performed. Strength properties from both tests were considerably consistent. And trackability of construction equipment on the treated surface layer of dredged land was estimated. Finally, optimum mixing condition for Songdo silty clay was proposed.

• International Commerce and Information Review
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• v.11 no.1
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• pp.291-308
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• 2009

The implied obligation under the contract of affreightment not to carry dangerous goods without prior notice to the carrier applies to the contractual relationship between the charterer and the owner under charterparties. The charterers will be in breach of an implied undertaking under the common law if they load dangerous cargoes without making notice of dangerous nature of them to the owner. It is indicated to be necessary to change the term "shipper" to "charterer", with relation to such implied obligation, where the Hague/Hague-Visby Rules are incorporated into the charter, however, it is not so apparent where an actual shipper is involved. So long as an actual shipper could be identified, the shipper rather than the charterer shall be responsible for damages arising from the dangerous nature of the cargo itself. In this case, the actual shipper is interpreted to have an implied contractual relationship with the carrier just by the act of delivering the cargo to the carrier for loading. If the vessel were damaged by shipment of the dangerous cargo under charterparty, the carrier can claim against such damages based on the contractual obligations under charterparties: "implied and expressed duty not to ship dangerous cargo without notice to the carrier"; "Art.IV.6 of the Hague/Hague-Visby Rules"; "Indemnity Clause" and "Redelivery Clause". The carrier has the conventional right under the Hague/Hague-Visby Rules to land, destroy or render the goods innocuous where the dangerous cargo threatens the means of transport or other interests on board. When the carrier has not consented to make the shipment, the carrier's disposal right could be exercised without limitation. However, where the carrier has consented to make the shipment of the dangerous goods with the knowledge concerned, the right of disposal of such goods should be exercised with limitation.

• Journal of Environmental Science International
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• v.20 no.8
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• pp.977-986
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• 2011

This study analyzed the characteristics of stormwater runoff in the orchard areas and quantitatively estimated effluence of nonpoint source pollutants for the volume of runoff. Two target areas under vine cultivation were each $2,000m^2$ and $1,800m^2$, located in Gyeongju City. Since grape was the only crop on the target area, the characteristics of stormwater runoff at vineyard could be evaluated independently. A total of 51 rainfall events in the vineyard area during two years(2008-2009) was surveyed, and 19 of them became stormwater runoff, with rainfall ranging 16.5 - 79.7 mm and antecedent dry period of 1-13 days. The pollutant runoff loads by volume of stormwater runoff showed BOD ranging 19.5 - 45.3% in 30% of runoff volume. The average pollution discharge rate was 32.4%, indicating small first flush effect of BOD. The range of SS concentrations was 5 - 52.0% in 10% of runoff volume, showing the average 28.7% of discharge rate, about 3 times more than rainfall effluent. TOC and TN appeared to be similar to the results of BOD, the average discharge rate of 30.9% and 30.6% for TOC and TN, respectively, for 30% of stormwater runoff volume. Average discharge rate of COD and TP in the same runoff volume was 35.1% and 36%, respectively, showing comparatively high discharge ratio. As the targeted vineyard area was permeable land, the pollution load ratio against rainfall-runoff volume appeared to be 1:1, implying no strong first flush effect for all the survey items.

• Journal of Environmental Science International
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• v.26 no.2
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• pp.211-220
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• 2017

For areas with the diverse contamination sources, the change of 4-nitrophenol contamination and impact of potential contamination sources have been evaluated using monitoring data and a numerical model (HydroGeoSphere). The model considered several parameters including land cover, precipitation, and flow rate. And, the model has been performed to investigate the effect of decay rate of 4-nitrophenol. The results of the simulations showed that the influence on 4-nitrophenol in downstream was mainly greater than that in upstream, and the tributaries did not significantly affect the mainstream because of their low flow rates. In addition, the effect of contamination sources was simulated for each section, then the measured data were higher than the corresponding simulated data in most sections of the Geumho river. In particular, the impact of the potential contamination sources in the upstream area was much higher than that in the other area, thus more monitoring data for the upstream area is required.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1202-1203
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• 2015

This paper describes the development of HVDC ${\pm}500kV$ polypropylene laminated paper (PPLP) mass-impregnated (MI) type cable system for HVDC transmission lines. As you know, mass-impregnated type cable generally has only insulating layer with the Kraft paper impregnated with a high-viscosity insulating compound. But polypropylene laminated paper is made of a layer of extruded polypropylene (PP) film sandwiched between two layers of Kraft paper. Thanks to PP film and its combination with Kraft paper, PPLP has higher AC, Impulse (Imp.) and DC breakdown (BD) strengths as well as lower dielectric loss than conventional Kraft paper insulation. In addition, Kraft MI cable has a limitation for the maximum conductor temperature as $55^{\circ}C$ But this PPLP MI cable has higher maximum conductor temperature than that of Kraft MI cable due to advantage of oil drainage characteristics. It is the most economic type of cable for HVDC transmission. Also HVDC ${\pm}500kV$ PPLP MI cable system was developed including land joints and outdoor-terminations. In order to prove the mechanical and electrical performances, the type test was carried out according to CIGRE recommendations. A full scale cable system has been tested successfully. And additional load cycle and polarity reversal tests on the cable system showed a higher performance compared with a similar mass impregnated paper cable.

• Journal of the Korean Geosynthetics Society
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• v.11 no.1
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• pp.23-33
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• 2012

The stability of urban railway foundation can be a problem due to the excessive settlement. The settlement at the base of railway is monitored by the installed settlement gauges. The piezometer and pore water pressure measurement device are installed to measure the variation of pore water pressure and ground water table during the continuous pullout of sheet piles which were used for the braced cut. The settlement of railway is predicted with using the computer program CAIN RDA. The input data for the numerical analysis are obtained from the field soil exploration data and soil properties. The surcharged load from landscaping over the ground surface and the weight of train are taken into account for the estimation of settlement. As a result of numerical analysis, the range of settlement for six different Sites is from 5.94 cm to 12.77 cm. Thus, the settlement level at Site 2 is occurred 12.77 cm which is higher than the allowable settlement of 10 cm.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.501-506
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• 2019

This paper presents a prescriptive alternative for establishing a FRMS suitable for us based on scientific data ahead of the introduction and implementation of the FRMS for air traffic controllers in order to meet the International Civil Aviation Organization (ICAO) international standards. I would like to present. Therefore, we confirmed the operation of each air traffic control agency against the current domestic operating standards, and compared and reviewed the operation methods and standards of air traffic control agencies in each country. The controller in Korea defines 10 hours of working hours per day, 8 hours of minimum breaks, and 40 hours per week. Currently, in the case of air traffic control agencies, the daytime and the appropriate working hours are used in the daytime, but in the nighttime, the average time exceeds 5.9 hours. In the case of 40 hours a week, they work an average of 15.7 hours overtime. By adjusting the nighttime work time, this work can be solved by diversifying the form of the worker's input method according to the personal schedule rather than the two-day (day / night) method, as well as the appropriate nighttime time distribution by supplementing the personnel.

• Journal of Wetlands Research
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• v.9 no.2
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• pp.71-84
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• 2007

Masan Bay is a representative semi-closed bay acted as a sedimentation reservoir with a slow current velocity and a poor water circulation in Korea. The pollutants from terrestrial sources into the Masan Bay have apparently environmental pollution problems, such as eutrophication, red tied, and hypoxia. In this study, An ecological modeling work was performed to estimate the material circulation including the growth of bivalve in ecosystem. Furthermore, the effect of water purification was calculated by filter feeding bivalve to particulate organic matter just like COD and phytoplankton. And Water quality management strategy by bio-purification of bivalve is derived through selection of location, quantification of bivalve aquaculture farm. The results showed that the optimum location for bivalve farming is where phytoplankton accumulation by physical processes is maximized and the optimum density and area of bivalve are 35 individuals $m^{-3}$ and ca. 500 hectare, respectively. When assuming conditions for the optimum growth of bivalve, COD could decrease by up to 18% even without other reduction of pollution loads.

• Journal of Wetlands Research
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• v.9 no.2
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• pp.9-20
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• 2007

The nonpoint pollutants are originated from various land uses. Of the landuses, the development means the changes of the soil cover and the increases of imperviousness rate, which will increase the nonpoint pollutant emissions during a storm. Therefore, the Ministry of Environment in Korea has programed TPLMS(Total Pollution Load Management System) for four major large rivers to improve the water quality in rivers by controling the total pollutant loadings from the watershed area. The study area was forest landuse before resort development, however it is now changing to the resort. Some of the forest areas will be changed to parking lots, roads and buildings, which can be the major pollutant sources in the future. The paved areas are highly polluted landuses because of high pollutant accumulation rate by vehicle activities during dry periods. Therefore, this research is achieved to determine the changes of pollutant loading rate by development plan and to provide the best management practices for controlling nonpoint pollutants. Finally this research will provide the environment-kindly development technology for protecting the water quality.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.5-11
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• 2006

This study was carried out to analyse the landslide characteristics by structure stability analysis at the landsliding area occurred in Maeri, Sangdong-myeon, Gimhaesi, Gyeongsangnam-do. External stability of the retaining wall and the retaining stonewall was accessed as unstable condition except for the II-D profile. It is needed to consider a counter plan to stabilize the structure. Also, it is necessary to stabilize the unstable retaining wall reinforced with adding draining measure. It is useful to reduce the load from upper retaining stonewall by alleviating the slope degree from stonewall structures.