• The Journal of Engineering Geology
• /
• v.28 no.2
• /
• pp.133-160
• /
• 2018

$CO_2$ storage is a very important technology for reduction of greenhouse gas emissions and has been considered as almost the only viable and effective option for immediate large-scale $CO_2$ sequestration. Small-scale demonstration project for offshore $CO_2$ storage in the Pohang Basin is the transitional stage R&D program for technological preparation of large-scale $CO_2$ storage project in Korea. Through the extensive exploration research for prospective $CO_2$ storage sites, the offshore strata in the Pohang Basin was recommended for the storage formation of the small-scale demonstration project. The Pohang Offshore Storage Project launched at 2013, and has accomplished the technical demonstration and technological independence in a wide range of $CO_2$ storage technology, such as geophysical exploration, storage site characterization, storage design, offshore platform construction, injection-well drilling and completion, deployment of injection facility, operation of $CO_2$ injection, and $CO_2$ monitoring. The project successfully carried out $CO_2$ test injection in early 2017, and achieved its final goal for technical development and demonstration of $CO_2$ storage in Korea. The realization of $CO_2$ injection in this project is the measurable result and has been recorded as the first success in Korea. The Pohang Offshore Storage Project has a future plan for the continuous operation of $CO_2$ injection and completion of $CO_2$ monitoring system. The project has provided in-house technical and practical expertises, which will be a solid foundation for the commercial-scale $CO_2$ storage business in Korea. Additionally, the project will help to secure national technical competitiveness in growing international technology market for $CO_2$ storage.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.5
• /
• pp.516-522
• /
• 2020

Water trees can cause considerable damage to the performance of underground cables. Theymay formwithin the dielectric used in buried or water-immersed high voltage cables. They grow in a bush-like or tree-like form, often taking decades before causing damage to a cable's performance. They are usually found on very old underground cables, often in an inaccessible place. It is costly and time-consuming to detect watertrees in underground cables. Tree detection technology, including mathematical modeling,can reduce the maintenance cost and time necessary for detecting these trees.To simulate detection of water trees in this study, a mathematical model ofan XLPE cable and a water tree were developed. The complex water tree structure was simplified, based on two identified patterns of aventedtree. A Matlab simulation was performed to calculate and analyze the capacitance and resistance of a cable insulation layer,based on growth of a watertree. Capacitance size increased about 0.025×10^-13[Farads/mm] compared to normal when the tree area of the cable was advanced to 95% of the insulation layer. The resistance value decreased by about 0.5×10¹⁶[ohm/m]. These changesand changesshowninaBurkes paper physical modeling simulation are similar.The value of mathematical modeling for detecting water trees and damage to underground cables has been demonstrated.

• Journal of Korea Port Economic Association
• /
• v.37 no.2
• /
• pp.91-105
• /
• 2021

The current increasing size of container vessels affects the container port's situation. The containerization has changed the inter-modal handling process, which brought more flexibility and comfortableness in the shipping industry sector. Thus, it is very crucial to analyze the efficiency of container ports in the regional sphere. Such kind of efficiency analysis provide a powerful management tool for port operators and shipping managers in the Mediterranean market, and it also helps to form an information for planning new regional and national port operations. This paper aims to analyze the ports' technical efficiency of Mediterranean major container ports. It is conducted to establish the model of port performance and efficiency through the empirical test of the various factors. Regarding to the panel data collected from the 48 DMUs (decision making units), this study attempts to provide the empirical basis of the port efficiency relative to another factors in the total port performance. Due to the complexity of the various activities carried out at container ports, the study focuses only on the technical efficiency at the level of the Mediterranean container port. Unlike the practice of cross-sectional data analysis, originally established by Charnes et al. (1985), the panel data in DEA window analysis applications are used. The main focus of this study is the relative technical efficiency of 12 container ports from 7 countries in the Mediterranean market. The selection of ports under study is based on their high handling capability and rankings in World Top 100 (Containerization International, 2018).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.841-844
• /
• 2009

Recently our society is changing from an information era to an ubiquitous era. The centralization of an ubiquitous city has been developing among the countries and cities competitively. At this point, a reconfiguration of proper network environment is very important factor for a city competitive power. The centralization of an ubiquitous city is progressing with two kinds of category divided into existing cities and new cities. For example, Unlike new cities, the existing cities should consider the physical space restriction of communication network configuration because they can not design an underground cord lining. This paper describes the comparison and analysis of ubiquitous proceeding cases between the existing cities and new cities. And also, we investigated infrastructure features of proceeding ubiquitous city which is regarded as a reviving concept for the existing cities. In addition, a political proposal of wireless network configuration is suggested to solve these problems for the ubiquitous city.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.5
• /
• pp.274-279
• /
• 2006

The exact estimation of crop evapotranspiration containing reference or potential evapotranspiration is necessary for decision of crop water requirements. This study was carried out for the evaluation and application of various meteorological elements used for the calculation of reference evapotranspiration (RET) by FAO Penman-Monteith (PM) model. Meteorological elements including temperature, net radiation, soil heat flux, albedo, relative humidity, wind speed measured by meteorological instruments are required for RET calculation by FAO PM model. The average of albedo measured for crop growing period was 0.20, ranging from 0.12 to 0.23, and was slightly lower than 0.23. Determinant coefficients by measured albedo and green grass albedo were 0.97, 0.95 and standard errors were 0.74, 0.80 respectively. Usefulness of deductive regression models was admitted. To assess an influence of soil heat flux (G) on FAO PM, RET with G=0 was compared with RETs using G at 5cm soil depth ($G_{5cm}$) and G at surface ($G_{0cm}$). As the results, RET estimated by G=0 was well agreed with RET calculated by measured G. Therefore, estimated net radiation, G=0 and albedo of green grass could be used for RET calculation by FAO PM.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.8
• /
• pp.65-73
• /
• 2013

Ground-coupled heat pump system has attracted attention as a promising renewable energy technology due to its improving energy efficiency and eco-friendly mechanism for space cooling and heating. Pipes buried in the ground play a role of direct thermal interaction between circulating fluid inside the pipe and surrounding soils in the geothermal exchange system. However, both complexities of turbulent flow coupling thermal-hydraulic phenomena and very long aspect ratio of the pipe make it difficult to model the heat exchange system directly. Energy balance for fluid flow inside the pipe was derived to model thermal-hydraulic phenomena, and one-dimensional pipe element was proposed through Galerkin formation and time integration of the equation. Developed element is combined to pre-developed FEM code for THM phenomena in porous media. Numerical results of Thermal Response Test showed that line-source model overestimates equivalent thermal conductivity of surrounding soils due to thermal interaction between adjacent pipes and finite length of the pipe. Thus, inverse analysis for the TRT simulation was conducted to present optimal transformation matrix with utmost convergence.

• Journal of the Speleological Society of Korea
• /
• no.77
• /
• pp.43-52
• /
• 2007

중국 호남성의 장가계시 무릉원(武陵源)에는 위로 천문산(天門山)의 천문동(天門洞)과 땅 아래로 뻗혀 있는 황룡동굴(黃龍洞窟)이 있다. 천문동은 오나라 때의 대지진으로 인하여 생긴 것이며, 황룡동굴은 이 지역에 분포된 석회암 지대로 말미암아 영겁의 세월을 통하여 생성된 지하생성물의 극치이다. 천문산 고봉의 하늘 맞닿은 높은 곳에 형성된 천문동혈(天門同穴)과, 4층 규모로 된 땅속의 산 같은 석회동 구조물과 강물을 무색케 하는 지중뱃길수로를 끌어안고 있는 황룡동굴은 과연 천산용동(天山龍洞)의 바로 그것이 아닌가. [답사보고서 중에서]

• Proceedings of the Korean Society for Bio-Environment Control Conference
• /
• 1998.05a
• /
• pp.54-60
• /
• 1998

시설재배의 생육은 지상부의 온도에 주로 영향을 받지만, 토양이 저온일 경우에는 양분의 흡수가 불량하고, 토양미생물의 활동이 떨어진다. 특히 세근의 발달이 억제될 뿐만 아니라 코르크화가 촉진되고, 정식후 묘의 활착이 지연되어 토양수분의 흡수가 불량해지므로 생육이 저하된다. (중략)

• Journal of the Korean Geosynthetics Society
• /
• v.10 no.2
• /
• pp.91-100
• /
• 2011

This study presents the estimation for the possibility of liquefaction according to the liquefaction evaluation methods in Saemangeum reclamation area for tide embankment, Jeollabuk-do, Korea. Liquefaction estimation is performed by cyclic triaxial tests and seismic response analysis using earthquake records of the long- and short-term. This area appears to have greatly potential of liquefaction from the grain-size distribution curve of the dredged and reclaimed soil in the area. Because the liquefaction can occur in this area if the foundations or buried structures are built at a depth within 10m below ground surface, the meticulous care is required in the design of them in the future.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.3
• /
• pp.1-13
• /
• 2009

Alkalinity and total carbon contents were measured by acid neutralizing titration (ANT), back titration (BT), gravitational weighing (GW), non-dispersive infrared-total carbon (NDIR-TC) methods for assessing precision and accuracy of alkalinity and total carbon concentration in $CO_2$-rich water. Artificial $CO_2$-rich water(ACW: pH 6.3, alkalinity 68.8 meq/L, $HCO_3^-$ 2,235 mg/L) was used for comparing the measurements. When alkalinity measured in 0 hr, percent errors of all measurement were 0~12% and coefficient of variation were less than 4%. As the result of post-hoc analysis after repeated measure analysis of variance (RM-AMOVA), the differences between the pair of methods were not significant (within confidence level of 95%), which indicates that the alkalinity measured by any method could be accurate and precise when it measured just in time of sampling. In addition, alkalinity measured by ANT and NDIR-TC were not change after 24 and 48 hours open to atmosphere, which can be explained by conservative nature of alkalinity although $CO_2$ degas from ACW. On the other hand, alkalinity measured by BT and GW increased after 24 and 48 hours open to atmosphere, which was caused by relatively high concentration of measured total carbon and increasing pH. The comparison between geochemical modeling of $CO_2$ degassing and observed data showed that pH of observed ACW was higher than calculated pH. This can be happen when degassed $CO_2$ does not come out from the solution and/or exist in solution as $CO_{2(g)}$ bubble. In that case, $CO_{2(g)}$ bubble doesn't affect the pH and alkalinity. Thus alkalinity measured by ANT and NDIR-TC could not detect the $CO_2$ bubble although measured alkalinity was similar to the calculated alkalinity. Moreover, total carbon measured by ANT and NDIR-TC could be underestimated. Consequently, it is necessary to compare the alkalinity and total carbon data from various kind of methods and interpret very carefully. This study provide technical information of measurement of dissolve $CO_2$ from $CO_2$-rich water which could be natural analogue of geologic sequestration of $CO_2$.