• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.453-467
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• 2016

Overall risks that can occur in a shield TBM tunnelling are studied in this paper. Both the potential risk events that may occur during tunnel construction and their causes are identified, and the causal relationship between causes and events is obtained in a systematic way. Risk impact analysis is performed for the potential risk events and ways to mitigate the risks are summarized. Literature surveys as well as interviews with experts were made for this purpose. The potential risk events are classified into eight categories: cuttability reduction, collapse of a tunnel face, ground surface settlement and upheaval, spurts of slurry on the ground, incapability of mucking and excavation, and water leakage. The causes of these risks are categorized into three areas: geological, design and construction management factors. Bayesian Networks (BN) were established to systematically assess a causal relationship between causes and events. The risk impact analysis was performed to evaluate a risk response level by adopting an Analytic Hierarchy Process (AHP) with the consideration of the downtime and cost of measures. Based on the result of the risk impact analysis, the risk events are divided into four risk response levels and these levels are verified by comparing with the actual occurrences of risk events. Measures to mitigate the potential risk events during the design and/or construction stages are also proposed. Result of this research will be of the help to the designers and contractors of TBM tunnelling projects in identifying the potential risks and for preparing a systematic risk management through the evaluation of the risk response level and the migration methods in the design and construction stage.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.363-368
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• 2003

We have successfully developed a more effective algorithm to extract the lineament in the area covered by wide alluvial deposits characterized by a relatively narrow range of brightness in the Landsat TM image, while the currently used algorithm is limited to the mountainous areas. In the new algorithm, flat areas mainly consisting of alluvial deposits were selected using the Local Enhancement from the Digital Elevation Model (DEM). The aspect values were obtained by 3${\times}$3 moving windowing of Zevenbergen & Thorno's Method, and then the slopes of the study area were determined using the aspect values. After the lineament factors in the alluvial deposits were revealed by comparing the threshold values, the first rank lineament under the alluvial deposits were extracted using the Hough transform In order to extract the final lineament, the lowest points under the alluvial deposits in a given topographic section perpendicular to the first rank lineament were determined through the spline interpolation, and then the final lineament were chosen through Hough transform using the lowest points. The algorithm developed in this study enables us to observe a clearer lineament in the areas covered by much larger alluvial deposits compared with the results extracted using the conventional existing algorithm. There exists, however, some differences between the first rank lineament, obtained using the aspect and the slope, and the final lineament. This study shows that the new algorithm more effectively extracts the lineament in the area covered with wide alluvlal deposits than in the areas of converging slope, areas with narrow alluvial deposits or valleys.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.194-194
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• 2017

Camelina (Camelina sativa L.) is a potential bio-energy crop that has short life cycle about 90 days and contains high amount of unsaturated fatty acid which is adequate to bio-diesel production. Enhancing environmental stress tolerance is a main issue to increase not only crop productivity but also big mass production. CsRCI2s (Rare Cold Inducible 2) are cold and salt stress related protein that localized at plasma membrane (PM) and assume to be membrane potential regulation factor. These proteins can be divide into C-terminal tail (CsRCI2D/E/F/G) or no-tail group (CsRCI2A/B/C/H). However, function of CsRCI2s are less understood. In this study, physiological responses and functional characterization of CsRCI2s of Camelina under salt stress were analyzed. Full-length CsRCI2s (A/B/E/F) and CsPIP2;1 sequences were confirmed from Camelina genome browser. Physiological investigations were carried out using one- or four-week-old Camelina under NaCl stress with dose and time dependent manner. Transcriptional changes of CsRCI2A/B/E/F and CsPIP2;1 were determined using qRT-PCR in one-week-old Camelina seedlings treated with NaCl. Translational changes of CsRCI2E and CsPIP2;1 were confirmed with western-blot using the antibodies. Water transport activity and membrane potential measurement were observed by cRNA injected Xenopus laevis oocyte. As results, root growth rate and physiological parameters such as stomatal conductance, chlorophyll fluorescence, and electrolyte leakage showed significant inhibition in 100 and 150 mM NaCl. Transcriptional level of CsPIP2;1 did not changed but CsRCI2s were significantly increased by NaCl concentration, however, no-tail type CsRCI2A and CsRCI2B increased earlier than tail type CsRCI2E and CsRCI2F. Translational changes of CsPIP2;1 was constitutively maintained under NaCl stress. But, accumulation of CsRCI2E significantly increased by NaCl stress. CsPIP2;1 and CsRCI2A/B/E/F co-expressed Xenopus laevis oocyte showed decreased water transport activity as 61.84, 60.30, 62.91 and 76.51 % at CsRCI2A, CsRCI2B, CsRCI2E and CsRCI2F co-expression when compare with single expression of CsPIP2;1, respectively. Moreover, oocyte membrane potential was significantly hyperpolarized by co-expression of CsRCI2s. However, higher hyperpolarized level was observed in tail-type CsRCI2E and CsRCI2F than others, especially, CsRCI2E showed highest level. It means transport of $Na^+$ ion into cell is negatively regulated by expression of CsRCI2s, and, function of C-terminal tail is might be related with $Na^+$ ion influx. In conclusion, accumulation of NaCl-induced CsRCI2 proteins are related with $Na^+$ ion exclusion and prevent water loss by CsPIP2;1 under NaCl stress.

• Economic and Environmental Geology
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• v.40 no.2 s.183
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• pp.209-221
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• 2007

Numerical analysis was performed to investigate the effect of heavy metal contamination on neighboring environment in case a dam is constructed by using rockfill materials contaminated by heavy metals. The numerical simulation carried out in this research includes both subsurface flow and contaminant transport in the inside of the CFRD(Concrete Faced Rockfill Dam), using two commercial programs, SEEP2D and FEMWATER. The three representative cases of scenarios were chosen to consider a variety of cases occurring in a dam site; (1) Scenario 1 : no crack in the concrete face slab, (2) Scenario 2 : a crack In the upper part of face slab, and (3) Scenario 3 : a crack between plinth and face slab in the lower part of face slab. As a result of seepage analysis, the amount of seepage in scenario 2 was calculated as $14.31\sim14.924m^3/day$ per unit width, corresponding to the 1,000 times higher value than that in other scenarios. Also, in the simulation of contaminant transport by using FEMWATER, specified contaminant concentration of 13 ppb in main rockfill zone was set to consider continuous leakage from the rock materials. Through the analysis of contaminant transport, we found that elapsed times to take for the contaminant concentration of about 2 ppb to arrive at the end of a dam are as follows. Scenario 1 has the elapsed time of 55,000 years. In Scenario 2. it is 50 years. Finally, scenario 3 has 27,000 years. The rapid transport of the contaminant in scenario 2 was attributed to greater seepage flow by 500 times than other scenarios. Although, in case of upper crack in the face slab, it was identified that the contaminant might transport to the end of a dam within 100 years with about 2 ppb concentration, however, it happened that the contaminant was hardly transported out of the dam in other scenarios, which correspond to either no crack or a crack between plinth and face slab. In conclusion, the numerical analysis showed that the alternative usage of the contaminated sand and gravel as the dam embankment material can be one of the feasible methods with the assumption that the cracks in a face slab could be controlled adequately.

• Economic and Environmental Geology
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• v.53 no.1
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• pp.23-32
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• 2020

Geological CO₂ sequestration is a global warming response technology to limit atmospheric emissions by injecting CO₂ captured on a large scale into deep geological formations. The presented results concern mineralogical and hydrogeological investigations (FE-SEM, XRD, XRF, and MICP) of mudstone samples from drilling cores of the Pohang basin, which is the research area for the first demonstration-scale CO₂ storage project in Korea. They aim to identify the mineral properties of the mudstone constituting the caprock and to quantitatively evaluate the hydrogeologic sealing capacity that directly affects the stability and reliability of geological CO₂ storage. Mineralogical analysis showed that the mudstone samples are mainly composed of quartz, K-feldspar, plagioclase and a small amount of pyrite, calcite, clay minerals, etc. Mercury intrusion capillary pressure analysis also showed that the samples generally had uniform particle configurations and pore distribution and there was no distinct correlation between the estimated porosity and air permeability. The allowable CO₂ column heights based on the estimated pore-entry pressures and breakthrough pressures were found to be significantly higher than the thickness of the targeting CO₂ injection layer. These results showed that the mudstone layers in the Yeongil group, Pohang basin, Korea have sufficient sealing capacity to suppress the leakage of CO₂ injected during the demonstration-scale CO₂ storage project. It should be noticed, however, that the applicability of results and analyses in this study is limited by the lack of available samples. For rigorous assessment of the sealing efficiency for geological CO₂ storage operations, significant efforts on collection and multi-aspect evaluation for core samples over entire caprock formations should be accompanied.

• Economic and Environmental Geology
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• v.53 no.1
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• pp.33-43
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• 2020

CO₂ geological storage is currently considered as the most stable and effective technology for greenhouse gas reduction. The saline formations for CO₂ geological storage are generally located at a depth of more than 800 m where CO₂ can be stored in a supercritical state, and an extensive impermeable cap rock that prevents CO₂ leakage to the surface should be distributed above the saline formations. Trough analysis of seismic and well data, we identified the basalt flow structure for potential CO₂ storage where saline formation is overlain by basalt cap rock around PZ-1 exploration well in the Southern Continental Shelf of Korea. To evaluate CO₂ storage capacity of the saline formation, total porosity and CO₂ density are calculated based on well logging data of PZ-1 well. We constructed a 3D geological grid model with a certain size in the x, y and z axis directions for volume estimates of the saline formation, and performed a property modeling to assign total porosity to the geological grid. The estimated average CO₂ geological storage capacity evaluated by the U.S. DOE method for the saline formation covered by the basalt cap rock is 84.17 Mt of CO₂(ranges from 42.07 to 143.79 Mt of CO₂).

• Ecology and Resilient Infrastructure
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• v.5 no.3
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• pp.163-173
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• 2018

The biopolymer (BP) used in this study is mainly composed of xanthan gum and ${\beta}$-glucan derived from microorganism and has been introduced as a novel material for soil stabilization. However, the broad applicability of BP has been suggested in the field of geotechnical engineering while little information is available about the effects of BP on the vegetation. The goal of this study is to find the BP effects on the growth of Camelina sativa L. (Camelina) under drought condition. For more thorough evaluation of BP effects on the plant growth, we examined not only morphological but also physiological traits and gene expression patterns. After 25 days of drought treatment from germination in the soil amended with 0, 0.25, 0.5, and 1% BP, we observed that the BP concentration was strongly correlated the growth of Camelina. When plants were grown under drought stress, Camelina in 0.5% BP mixture showed better physiological parameters of the leaf stomatal conductance, electrolyte leakage and relative water content compared to those in control soil without BP. Plant recovery rate after re-watering was higher and the development of lateral root was lower in BP amended soil. RNA expression of Camelina leaf treated with/without drought for 7 and 10 days showed that aquaporin genes transporting solutes at bio-membrane, CsPIP1;4, 2;1, 2;6 and TIP1;2, 2;1, were induced more in the plants with BP amendment and drought treatment. These results suggest that the soil amended with BP has a positive effect on the transport of nutrients and waters into Camelina by improving water retention in soil under drought condition.

• Childhood Kidney Diseases
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• v.2 no.2
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• pp.95-103
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• 1998

Purpose : To find and solve the common problems of peritoneal dialysis(PD) by analysing the clinical data of pediatric PD performed in Korea. Methods : 264 cases of CAPD and acute PD had been performed from Nov.1987 to Oct. 1997 in 17 institutions of pediatric nephrology in Korea. Results : CAPD was performed in 114 cases. The mean age of the patients was $10.5{\pm}6.6$ years and male to female ratio was 1.4:1. The original renal diseases of ESRD were proven in 92 cases($80\%$). The common renal disease of ESRD were FSGS($17\%$), reflux nephropathy ($11\%$), chronic glomerulonephritis($9.6\%$). Mean duration of CAPD was $20{\pm}16.9$ months. Peritonitis was the most common complication and incidence was one episode/18.2 patient-months. Other complications were exit site infection in 10 cases, obstruction in 7 cases, leakage of dialysate in 6 cases. The most common etiologic organism of peritonitis was staphylococcus aureus and the next was staphylococcus coagulase(-). Acute PD was performed in 150 cases. Most common underlying causes were congenital heart disease, hemolytic uremic syndrome, sepsis and dehydration. The mean duration was $10.3{\pm}11.3$ days. The most common complication was peritonitis($20.6\%$). The most common etiologic organism was staphylococcus aureus and coagulase(-), acinetobactor and pseudomonas. Conclusion : Reflux nephropathy should be emphasized in early diagnosis and treatment to prevent ESRD. Incidence of congenital anomaly($7\%$) as a original disease of ESRD was relatively low in Korea. Growth status was not significantly improved after CAPD. In acute PD, the incidence of peritonitis was rapidly increased at 2weeks after beginning of dialysis.

• Journal of Chest Surgery
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• v.31 no.7
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• pp.679-683
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• 1998

From June 1995 to May 1997, we have implanted 52 Sorin Bicarbon mechanical valves in 41 patients. They were 16 men and 25 women, and their mean age was 47.4${\pm}$14.8(range; 18∼74 y.o.). 35(27 mm∼31 mm) were in mitral position, 15(19 mm∼25 mm) in aortic position, and 2(31 mm) in tricuspid position. 3 CABGs and a tumor excision were taken concomittantly. 35 patients were primary operation, and 6 were re-do operations. By intraoperative transesophageal doppler echocardiography, transvalvular peak/mean pressure gradient was 6.1${\pm}$2.7/2.4${\pm}$1.4 mmHg in mitral position and 27.6/10.7 mmHg in aortic position. The effective valve opening area in mitral position was 3.2${\pm}$0.6 cm2. Follow-up was total 508.6 patient-months, and mean follw-up was 12.7${\pm}$9.2 months. NYHA class was improved from 2.6${\pm}$0.6 to 1.2${\pm}$0.3 in average postoperatively. During that period, there was no operative death. 2 late non-valve related deaths were occurred. One was died of COPD, and the other was possible acute myocardial infarction. Among 7 postoperative complications, one valve related complication(minimal paravalvular leakage) was noticed. In conclusion, Sorin Bicarbon mechanical valve is believed one of the safe choice in clinical settings. It showed excellent hemodynamic and mechanical functions, and very low postoperative valve related complications in short term clinical experience.

• Journal of Chest Surgery
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• v.34 no.9
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• pp.698-703
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• 2001

Background: Endovascular stent-graft insertion in aortic diseases is now generally accepted as an attractive alternative treatment modality. We reviewed our clinical experiences of endovascular stent-graft insertion in thoracic aorta. Material and Method: Since 1995, we performed 8 cases of endovasclar stent-graft insertion. Preoperative diagnoses were aortic aneurysms in 4, traumatic aortic ruptures in 3, and ruptured aortic pseudoaneurysm in 1. All procedures were performed in angiography room with the guidance of fluoroscopy. The stent-graft device is a custom-made 0.35mm thickness Z-shaped stainless steel wires, intertwined with each other using polypropylene suture ligation. It is covered with expanded Dacron vascular graft. Result: All procedures were performed successfully. Follow-up studies revealed 2 minimal perigraft leakages. There was no significant leakage or graft migration. 2 patients expired due to multiple organ failure and fungal sepsis. Other survivors(6) are doing well. Conclusion: Endovascular stent-graft insertion is relatively saft and effective treatment modality in the managment of various types of aortic diseases. In may be an effective alternative in aortic diseases of great surgical risk.