• Journal of Korean Society for Geospatial Information Science
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• v.13 no.1 s.31
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• pp.89-96
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• 2005

As the number of the municipalities which have finished the phase I of their GIS system development projects increases, it is very natural that GIS system operation and maintenance rather than development itself has been a more important concern for these municipalities. It seems to me that these phenomena will be amplified as time goes by, and this is the right time for a series of proper guidelines regarding the GIS system maintenance to be supplied to the related municipalities. The subject which is called as 'GIS maintenance' is surely a very comprehensive area. It has been also founded that the necessity is widely agreed among the concerned people working for the municipalities which have already finished their first GIS projects. Nevertheless, it has been investigated that the studies done up to now in this area is in a very infant state from the quality and also quantity points of views. This paper, therefore, makes one of the very initial trials for the systematical GIS maintenance. Among the areas of GIS maintenance, the GIS database maintenance has been selected as the first trial area because of its natural characteristics of the basic element composing IS(Information System). For this, the present conditions of a variety of municipalities have been investigated as far as GIS maintenance is concerned, and the results are analyzed to produce a series of useful outcomes in terms of facing problems and accompanied plans. For each problem, a solution is defined and for each solution a detailed action plan (item) is derived. For each of the two kinds of GIS data given which are the fundamental map and the underground facilities map, an effective GIS data maintenance plan is suggested for the concerned municipalities.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.452-460
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• 2000

This study was to investigate the growth characteristics, physiological adaptation of Pinus densiflora(Japanese Red Pine) seedlings at the artificial canopy gap in the Quercus acutissima plantation and to analyze its natural regeneration mechanism. Photosynthetic and transpiration rates were analyzed by different levels of photosynthetically active radiation and by seedling growth. Comparing to seedlings at the open area, those at the canopy gap showed more growth in height than in diameter with different levels of light quality and low light intensity, and the increase rate of dry weight was higher in the aboveground than in the underground, maintaining relatively high T/R rate. The C/F(the ratio of non-photosynthetic organs to photosynthetic organs in dry weight) of the aboveground at the canopy gap was higher than that at the open area by 0.1~0.2, while light saturation and light compensation points at the canopy gap were lower than that at the open area by $300{\mu}mol\;m^{-2}s^{-1}$ and 40%, respectively. The seedlings appeared to have shade tolerance to a certain extent at the young growth stage despite Pinus densiflora is typically classified shade-intolerant species. With light intensity lower than $400{\sim}450{\mu}mol\;m^{-2}s^{-1}$, photosynthetic rate and water use efficiency relatively increased by effective use of light energy.

• The Journal of Engineering Geology
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• v.29 no.1
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• pp.1-12
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• 2019

Earthquake can change underground stress condition around the hypocenter and affect the fracture systems of the rocks. In Korea, the M5.8 Gyeongju earthquake on September 12, 2016 and M5.4 Pohang earthquake on November 15, 2017 occurred inside the Yangsan fault zone and possibly affected the fracture systems in the Yangsan fault zone and nearby rock masses. In this study, the characteristics of the fracture system (fracture orientation, number of the fractures, fracture spacing and aperture, dip angle, fracture density along depth, and relative rock strength) of the rocks in the low/intermediate level radioactive waste repository site located in the coastal area of the East Sea are analyzed by the impact of the Gyeongju and Pohang earthquakes using acoustic televiewer data taken from the boreholes at the radioactive waste repository site in 2005 and 2018. As a result of acoustic televiewer logging analysis, the fracture numbers, fracture aperture, and fracture density along depth overall increased in 2018 comparing to those in 2005. This increase tendency may be due to changes in the fracture system due to the impact of the earthquakes, or due to weathering of the wall of the boreholes for a long period longer than 10 years after the installation of the boreholes in 2005. In the borehole KB-14, on the whole, the orientation of the fractures and the average fracture spacing are slightly different between 2005 and 2018, while dip angle and relative rock strength in 2005 and 2018 are similar each other.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.91-103
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• 2021

In order to estimate the vertical and horizontal structural in the Yangsan fault core line (Naengsuri area, Pohang), we carried out gravity field measurements and interpretation procedures such as Euler deconvolution method and curvature analysis in addition to the forward modelling technique (i.e. IGMAS+). We found a prominent gravity difference of more than 1.5 mGal across the fault core. This indicates a distinct density difference between the western and eastern crustal area across the Yangsan fault line. Comparing this gravity field interpretation with other existent geologic and geophysical survey data (e.g. LiDAR, trenching, electric resistivity measurements), It is concluded that (1) the prominent gravity difference is caused by the density difference of about 0.1 g/㎤ between the Bulguksa Granite in the west and the Cretaceous Sandstone in the east side, (2) the fault core is elongated vertically into a depth of about 2,000 meters and extended horizontally 3,000 meters to the NNE direction from Naengsuri area. Our results present that the gravity field method is a very effective tool to estimate a three -dimensional image of the active fault core.

• Korean Journal of Construction Engineering and Management
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• v.22 no.1
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• pp.55-62
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• 2021

The productivity of rebar-work and form-work was analyzed with data collected from an actual high-rise construction project, and the actual utilization rates of three tower cranes were also investigated. It was found that the average productivity of the form-work increased from 12.00~8.71(㎡/man·day) in the underground and above-ground/lower-floor to 11.94~20.73(㎡/man·day) in the standard floor. Comparing the productivity of core area to outer, the former was found to be about 11% higher. Moreover, the rebar-work productivity of the outer area(1.12 ton/man·day) was approximately 9.6% higher than that of the core area for the standard floor. The average utilization rates of three TC were surveyed to be about 63.49%, and it was revealed that rainy weather(6.1%), strong winds(6.1%), holidays(17.8%), TC lifting work(5.8%), and other failures and repairs(0.07%) were the causes of non-operation. These research results are expected to be beneficial data in planning and managing the process of high-rise RC construction works in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.871-879
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• 2008

Recently, as there are a rise in the standard of living and higher concerns of an electromagnetic wave and environment, undergrounding the aerial cables which are supported by large pylons and generally considered as the least attractive feature of an urban area is on an increasing trend to improve aesthetic benefits and electric reliability. This study applied Contingent Valuation Method (CVM) which is expected to become an effective tool to measure indirect benefit to estimate the substantial benefits of undergrounding overhead power line projects in an urban area. The tunneling construction project of the 345kV Shinsungnam electric power cable in Seongnam city was selected and a hypothetical scenario was given to respondents to determine their levels of Willingness to Pay (WTP) for undergrounding overhead power lines. The result from the estimation of the WTP of undergrounding overhead power lines in Seongnam city was calculated as approximately 17.1 billion won. Placing existing overhead lines underground is difficult to justify economically. Most undergrounding costs appear to be justified by aesthetic and public policy considerations. Therefore, considering the result of this study, undergrounding overhead power lines is of great benefit to public.

• Korean Journal of Plant Resources
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• v.33 no.2
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• pp.73-79
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• 2020

This study was conducted to evaluate the appropriateness cultivation of R. glutinosa by plug seedling. Cultivation by direct seeding (DS) and plug seedling (PS) of R. glutinosa was conducted in each of the Pyeongchang and Eumseong areas. As a result, locally, for the Eumseong area, aerial parts in leaf length, leaf width and number of leaves per plant were better than for the Pyeongchang area. In the cultivation method, leaf width and number of leaves per plant were better with PS cultivation than with DS cultivation. Locally, rhizome yield of underground parts in the Eumseong area was better than that in the Pyeongchang area, but the rhizome yield with DS cultivation in the Eumseong area and PS cultivation in the Pyeongchang area were statistically the same. The fresh rhizome yield for DS in Eumseong, PS in Eumseong, DS in Pyeongchang and PS in Pyeongchang was 1,253 kg/10a, 1,376 kg/10a, 923 kg/10a and 1,256 kg/10a, respectively. Finally, the catalpol content for DS in Eumseong, PS in Eumseong, DS in Pyeongchang and PS in Pyeongchang was 3.67%, 2.03%, 2.96% and 1.60%, respectively. From these results, it can be seen that the R. glutinosa PS cultivation method can increase the rhizome yield.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.231-240
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• 2017

Recently, there have been frequent occurrences of ground sink in the urban area, which have resulted in human and material damage and are accompanied by economic losses. This is caused by artificial factors such as soil loss, poor compaction, horizontal excavation due to the breakage of the aged sewage pipe, and lack of water proof at vertical excavation. The ground sink can be prevented by preliminary restoration and reinforcement through exploration, but it can be considered that it is not suitable for urgent restoration by the existing method. In this study, a model experiment was carried out to simulate the in-ground cavities caused by groundwater flow for developing non-excavation urgent restoration in underground cavity and the range of the relaxation zone was estimated by detecting the around the cavity using a relaxation zone detector. In addition, disturbance region and relaxation region were separated by injecting gypsum into cavity formed in simulated ground. The shape of the underground cavity due to the groundwater flow was similar to that of the failure mode III formed in the dense relative density ground due to water pipe breakage in the previous study. It was confirmed that the relaxed region detected using the relaxation zone detector is formed in an arch shape in the cavity top. The length ratio of the relaxation region to the disturbance region in the upper part of the cavity center is 2: 1, and it can be distinguished by the difference in the decrease of the shear resistance against the external force. In other words, it was confirmed that the secondary damage should not occur in consideration of the expandability of the material used as the injecting material in the pre-repair and reinforcement, and various ground deformation states will be additionally performed through additional experiments.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.69-79
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• 2018

The Korean government attempts to reduce $CO_2$ emissions by 37% to 314.7 Mt $CO_2$, down from the estimated 850.6 Mt $CO_2$ until 2030 in order to confront green house effect. In this context, in 2014, Korean government launched $CO_2$ Storage Environmental Management Research (K-COSEM) Center for carrying out pilot-scale research on $CO_2$ leakage from underground $CO_2$ storage facilities. For the detection of $CO_2$ leakage, it is necessary to identify hydrologeological and geophysical characteristics of the subject area. In the study site of Naesan-ri, Daeso-myeon, Eumseong-gun, Chungbuk Province, two times injection tests (June 28-July 24, 2017 and August 07-September 11, 2017) of $CO_2$ and $SF_6$ dissolved waters, respectively, was conducted to understand the leakage behavior of $CO_2$ from underground. The injection well was drilled to a depth of 24 m with a 21-m casing and screen interval of 21~24 m depth. Two times resistivity surveys on August 18, 2017 and September 1, 2017, were conducted for revealing the flow of the injected water as well as the electrical properties of the study site. The study results have shown that the high-resistivity zone and the low-resistivity zone are clearly contrasted with each other and the flow direction of the injected water is similar to natural groundwater flow. Besides, the low resistivity zone is widely formed from the depth of injection to the shallow topsoil, indicating that the weathered zone of high permeability has high $CO_2$ leakage potential.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.599-608
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• 2009

This study was conducted to examine chemical characteristics and correlations among seepage water, subsurface waters and inland groundwater in and around a coastal underground LPG cavern using factor and cluster analyses. The study area is located in western coast of Incheon metropolitan city and is about 8 km off the coast. The LPG cavern storing propane and butane was built beneath artificially reclaimed island. Mean bathymetry is 8.5 m and maximum sea level change is 10 m. Water sampling was conducted in May and August, 2006 from 22 sampling points. Correlation analysis showed strong correlations among $Fe^{2+}$ and $Mn^{2+}$ (r=0.83~0.99), and Na and Cl (r=0.70~0.97), which indicated reductive dissolution of iron and manganese bearing minerals and seawater ingression effect, respectively. According to factor analysis, Factors 1 (May) and I (August) showed high loadings for parameters representing seawater ingression into the cavern and effect of submarine groundwater discharge, respectively while Factors 2 and IV showed high loadings for those representing oxidation condition (DO and ORP). Factors 4 and II have large positive loadings for $Fe^{2+}$ and $Mn^{2+}$. The increase of $Fe^{2+}$ and $Mn^{2+}$ was related to decomposition of organic matter and subsequent their dissolution under reduced condition. Cluster analysis showed the resulting 6 groups for May and 5 groups for August, which mainly included groups of inland groundwater, cavern seepage water, sea water and subsurface water in the LPG storage cavern. Subsurface water (Group 2 and Group III) around the underground storage cavern showed high EC and major ions contents, which represents the seawater effect. Cavern seepage water (Group 5 and Group II) showed a reduced condition (low DO and negative ORP) and higher levels of $Fe^{2+}$ and $Mn^{2+}$.