• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.134-142
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• 2017

Crop production in rice paddy fields is of great importance because of declining rice consumption and the low self-sufficiency ratio for field crops in Korea. A controlled drainage system (CDS) is recognized as an effective means to adjust water table (WT) levels as needed and control soil water content to improve the soil environment for optimum crop growth. The present study evaluated the effects of a CDS on soil characteristics, including soil water distribution and soybean development in paddy fields. The CDS was installed with two drain spacing (3 m and 6 m) at the experimental paddy field at the National Institute of Crop Science, Miryang, Korea. It was managed with two WT levels (0.3 m and 0.6 m) during the growing season. Soil water content, electrical conductivity and plant available nitrogen content in the soil were significantly greater in the 0.3 m WT management plots than in the 0.6 m plot and the control. At the vegetative stage, chlorophyll content was significantly lower with higher WT control because of excess soil moisture, but it recovered after the flowering stage. Soybean yield increased with WT management and the 0.6 m WT treatment produced the greatest grain yield, $3.38ton\;ha^{-1}$, which was 50% greater than that of the control. The CDS directly influenced outflow through the drains, which significantly delayed nutrient loss. The results of this study indicated that WT management by CDS can influence soil characteristics and it is an important practice for high yielding soybean production in paddy fields, which should be considered the crop growth stages for stable crop production.

• Tunnel and Underground Space
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• v.29 no.1
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• pp.52-63
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• 2019

It is highly in demand to establish a bunker-type underground data center to ensure the safety of national critical data, such as financial information and medical information, and prevent those outflow of national important data. In particular, the security of a data center which is a key national structure has become a social issue due to EMP weapon and earthquakes, but data centers in the nation have not been able to deal with it properly. Therefore, it is necessary to develop an underground data center that is safe from human-induced and natural disasters while reducing power costs by utilizing the benefits of underground spaces such as constant temperature and isolation. In this analysis, the status and trends of data centers around the world were analyzed and based on those trend analyses, the research strategy for underground data center were discussed.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.515-526
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• 2021

The frequency of typhoons and torrential rainfalls has increased due to climate change, and the concurrent risk of breakage of dams and reservoirs has increased due to structural aging. To cope with the risk of dam breakage, a more accurate emergency action plan (EAP) must be established, and more advanced technology must be developed for the prediction of flooding. Hence, the present study proposes a method for establishing a more effective EAP by performing flood and inundation analyses using one- and two-dimensional models. The probable maximum flood (PMF) under the condition of probable maximum precipitation (PMP) was calculated for the target area, namely the Gyeong-cheon reservoir watershed. The breakage scenario of the Gyeong-cheon reservoir was then built up, and breakage simulations were conducted using the dam-break flood forecasting (DAMBRK) model. The results of the outflow analysis at the main locations were used as the basis for the one-dimensional (1D) and two-dimensional (2D) flood inundation analyses using the watershed modeling system (WMS) and the FLUvial Modeling ENgine (FLUMEN), respectively. The maximum inundation area between the Daehari-cheon confluence and the Naeseong-cheon location was compared for each model. The 1D flood inundation analysis gave an area of 21.3 km², and the 2D flood inundation analysis gave an area of 21.9 km². Although these results indicate an insignificant difference of 0.6 km² in the inundation area between the two models, it should be noted that one of the main locations (namely, the Yonggung-myeon Administrative and Welfare Center) was not inundated in the 1D (WMS) model but inundated in the 2D (FLUMEN) model.

• Journal of Environmental Impact Assessment
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• v.19 no.5
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• pp.475-481
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• 2010

Lots of pollutants typically originating from urban transportation are accumulating on the paved surfaces during dry periods and are washed-off directly to the river during a storm. Also, paved surfaces are contributing to increase in peak flows and volume of stormwater flows. These are the main reasons why the water quality of rivers and lakes remain polluted and still below standards. Currently, several management practices are being applied in developed countries but the design standards are still lacking. This research was conducted to develop a treatment technology that can be useful to address the problems concerning runoff quality and quantity. A lab scale infiltration device consisting of a pretreatment tank and media zone was designed and tested for various flow regimes characterizing the low, average and high intensity rainfall. Based on the experiments, the high intensity flow resulted to increase in outflow event mean concentration (EMC) of pollutants, about twice as much as the average outflow EMC. However, 78 to 88% of the total suspended solids were captured and retained in the pretreatment tank because of sedimentation. The removal of heavy metals such as zinc and lead was greatly affected by the vertical placement of woodchip layer prior to the media zone. It was observed that the high carbon content (almost 50%) in the woodchip provided opportunity for enhancing its uptake of metal by adsorption. The findings implied that the reduction of pollutants can be greatly achieved by means of proper pretreatment to allow for settling of particles with a combination of using high carbon source media like woodchip and a geotextile mat to reduce the flow before filtering into the media zone and finally discharging to the drainage system.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.268-280
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• 2009

Oncheon basin which are located in Busan is divided into 43 basin on the basis of main pipe, constructed with Storm Water Management Model (SWMM). Occurrence situation for Outflow and pollutant loads by long-term continuous rainfall is examined for treatment district and river analysis point of Oncheon basin and a reduction vs effectiveness table for effective CSOs managements is made for each of treatment districts according to each of managements. In case that treatment equipment is located at the discharge point of CSO, treatment efficiency is analysed. It is supposed that treatment equipment have an efficiency on the basis of a concentration and runoff discharge over a critical flow is discharged with it untreated and treating runoff discharge with treatment equipment at each of runoff discharge points and treating it gathered at sewage treatment plant (STP) through trunk sewer is compared for a relative treatment efficiency.

• The KSFM Journal of Fluid Machinery
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• v.19 no.1
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• pp.5-10
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• 2016

As a key component of a Francis turbine facility, the runner performance plays a vital role in the performance of the turbine. It is effective and successful to design a Francis turbine runner blade with good performance by one dimensional hydraulic design method. On the basis of one dimensional hydraulic analysis, there are a lot of parameters of the internal flow passage shapes determined by experience. Among those parameters, the effect of port area of blade on the performance of a Francis turbine is investigated in this study. A given Francis turbine model was selected for investigating the port area of blade on the performance. The result shows that the effect of port area of runner blade on the outflow angle from runner passage on the performance is quite significant. A correct exit flow angle reduces the energy loss at draft tube, which has the best efficiency of the turbine model.

• Journal of Information Technology Services
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• v.15 no.3
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• pp.33-50
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• 2016

In a dynamic IT environment, employees often utilize external IT resources to work more efficiently and flexibly. However, the use of external IT resources beyond its control may cause difficulties in the company. This is known as "Shadow IT." In spite of efficiency gains or cost savings, Shadow IT presents problems for companies such as the outflow of enterprise data. To address these problems, appropriate measures are required to maintain a balance between flexibility and control. Therefore, in this study, we developed a new information security management system called AIIMS (Advanced IT service & Information security Management System) and the Shadow IT Evaluation Model. The proposed model reflects a Shadow IT's attributes such as innovativeness, effectiveness, and ripple effect. AIIMS consists of five fields: current analysis; Shadow IT management plans; management process; education and training; and internal audit. There are additional management items and sub-items within these five fields. Using AIIMS, we expect to not only mitigate the potential risks of Shadow IT but also create successful business outcomes. Now is the time to draw to the Light in the Shadow IT.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.365-370
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• 2004

At the present, e-commerce takes the place of existing transaction form in structure in the world trade by advancement of Information Technology and diffusion of Internet. There is no exceptions of this tendency even in industry of maritime and logistics. So, global shipping lines and logistics companies try to construct the e-Business network system for increasing their competitiveness in an are of cyber. However, in Korea, most of companies prefer "final handshake" as the traditional way of transaction to "e-commerce", because they bear a distrust in mind about the outflow of transaction information and security of settlement. So, number of companies using e-commerce is very small, and this situation causes the limited factor for activating the transaction structure of it. The rate of using e-commerce in logistics industry is lower than other industries, even more higher effectiveness is expected when they use it. Especially, it is very necessary not only e-commerce but also e-Logistics which can serve information of freight cost on cargo flow, operation cost and schedule, and tracing information of cargo. Increasing the necessity of e-Logistics, this study research the rate rf using e-Logistics focused on maritime and logistics companies, and analyze the transaction form among members of these industries for improving them. In detail, this paper examine the drivers for activating e-Logistics, and present the effective factors for a successful development of these industries.

• Ocean and Polar Research
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• v.26 no.3
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• pp.501-506
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• 2004

The observational proxy estimates suggest that the North Atlantic overturning stream function associated with the North Atlantic Deep Water (NADW) production and outflow was substantially weaker during the last glacial maximum (LGM) than that observed under present conditions. The impact of the changes in overturning circulation on the glacial carbon budget is investigated using a box model. The carbon box model reveals that the atmospheric $CO_2$ concentration is more sensitive to change in the overturning circulation of the North Atlantic than that of the Southern Ocean, especially when North Atlantic overturning becomes weaker. For example, when the strength of the North Atlantic overturning circulation is halved, the atmospheric $CO_2$ concentration is reduced by 50ppm of that associated with the accumulation of $CO_2$ in the deep ocean. This result implies that a weaker North Atlantic overturning circulation may play an important role in the lowering of LGM atmospheric $CO_2$ concentration.

• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.25-33
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• 2010

Collision between vessels may lead to structural damage and penetration of hulls. The structural damage of a hull may eventually bring about global collapse of the hull girder and outflow of oil, which would contaminate seawater. Therefore, various regulations require the strength of a vessel after collision to satisfy given criteria, and owners usually request collision analyses to confirm the structural safety of their vessels. In the process of designing a vessel to satisfy the collision strength criteria, the strength has been assessed mostly by conducting collision analyses using numerical techniques, such as dynamic, non-linear, finite-element analysis. Design is an inherently iterative process during which many changes are necessary due to the endless needs for reinforcement and modification. Numerical techniques are not adequate for coping with a situation in which collision analysis is frequently required to provide the revised results that reflect the repetitive changes in designs. Numerical techniques require a lot of time and money to conduct in spite of recent improvements in computing power and in the productivity of modeling tools. Therefore, in this paper, an analytical technique is introduced and a collision problem is idealized and simplified using reasonable assumptions based on appropriate background. The technique was applied to an example of an actual FPSO and verified by comparing the results with results from the numerical technique. A good correlation was apparent between the results of the analytical and numerical techniques.