• Journal of Environmental Impact Assessment
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• v.26 no.2
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• pp.93-104
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• 2017

CCS (Carbon Capture and Storage) is a technical process to capture $CO_2$ from industrial and energy-based sources, to transfer and sequestrate impressed $CO_2$ in geological formations, oceans, or mineral carbonates. However, potential $CO_2$ leakage exists and causes environmental problems. Thus, this study was conducted to analyze the spatial and temporal variations of $CO_2$ fluxes and concentrations after artificial $CO_2$ release. The Environmental Impact Evaluation Test Facility (EIT) was built in Eumseong, Korea in 2015. Approximately 34kg $CO_2$ /day/zone were injected at Zones 2, 3, and 4 among the total of 5 zones from October 26 to 30, 2015. $CO_2$ fluxes were measured every 30 minutes at the surface at 0m, 1.5m, 2.5m, and 10m from the $CO_2$ releasing well using LI-8100A until November 13, 2015, and $CO_2$ concentrations were measured once a day at 15cm, 30cm, and 60cm depths at every 0m, 1.5m, 2.5m, 5m, and 10m from the well using GA5000 until November 28, 2015. $CO_2$ flux at 0m from the well started increasing on the fifth day after $CO_2$ release started, and continued to increase until November 13 even though the artificial $CO_2$ release stopped. $CO_2$ fluxes measured at 2.5m, 5.0m, and 10m from the well were not significantly different with each other. On the other hand, soil $CO_2$ concentration was shown as 38.4% at 60cm depth at 0m from the well in Zone 3 on the next day after $CO_2$ release started. Soil $CO_2$ was horizontally spreaded overtime, and detected up to 5m away from the well in all zones until $CO_2$ release stopped. Also, soil $CO_2$ concentrations at 30cm and 60cm depths at 0m from the well were measured similarly as $50.6{\pm}25.4%$ and $55.3{\pm}25.6%$, respectively, followed by 30cm depth ($31.3{\pm}17.2%$) which was significantly lower than those measured at the other depths on the final day of $CO_2$ release period. Soil $CO_2$ concentrations at all depths in all zones were gradually decreased for about 1 month after $CO_2$ release stopped, but still higher than those of the first day after $CO_2$ release stared. In conclusion, the closer the distance from the well and the deeper the depth, the higher $CO_2$ fluxes and concentrations occurred. Also, long-term monitoring should be required because the leaked $CO_2$ gas can remains in the soil for a long time even if the leakage stopped.

• Journal of the Korea Society of Computer and Information
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• v.14 no.12
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• pp.157-167
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• 2009

Recently, the leakage of confidential information and personal information is taking place on the Internet more frequently than ever before. Most of such online security incidents are caused by attacks on vulnerabilities in web applications developed carelessly. It is impossible to detect an attack on a web application with existing firewalls and intrusion detection systems. Besides, the signature-based detection has a limited capability in detecting new threats. Therefore, many researches concerning the method to detect attacks on web applications are employing anomaly-based detection methods that use the web traffic analysis. Much research about anomaly-based detection through the normal web traffic analysis focus on three problems - the method to accurately analyze given web traffic, system performance needed for inspecting application payload of the packet required to detect attack on application layer and the maintenance and costs of lots of network security devices newly installed. The UTM(Unified Threat Management) system, a suggested solution for the problem, had a goal of resolving all of security problems at a time, but is not being widely used due to its low efficiency and high costs. Besides, the web filter that performs one of the functions of the UTM system, can not adequately detect a variety of recent sophisticated attacks on web applications. In order to resolve such problems, studies are being carried out on the web application firewall to introduce a new network security system. As such studies focus on speeding up packet processing by depending on high-priced hardware, the costs to deploy a web application firewall are rising. In addition, the current anomaly-based detection technologies that do not take into account the characteristics of the web application is causing lots of false positives and false negatives. In order to reduce false positives and false negatives, this study suggested a realtime anomaly detection method based on the analysis of the length of parameter value contained in the web client's request. In addition, it designed and suggested a WAF(Web Application Firewall) that can be applied to a low-priced system or legacy system to process application data without the help of an exclusive hardware. Furthermore, it suggested a method to resolve sluggish performance attributed to copying packets into application area for application data processing, Consequently, this study provide to deploy an effective web application firewall at a low cost at the moment when the deployment of an additional security system was considered burdened due to lots of network security systems currently used.

• Journal of Gastric Cancer
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• v.9 no.4
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• pp.223-230
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• 2009

Purpose: Circular stapled gastrectomy has been the favored procedure with its feasibility and the shortened operative time, but anastomotic leakage, stenosis and bleeding have been reported as problems. The aim of this study was to identify what can be done to supplement the safety of this technique by examining the potential complications of performing circular stapled gastrojejunosomy after radical subtotal gastrectomy. Materials and Methods: As subjects, this study selected 1,391 patients who underwent gastrojejunostomy after radical subtotal gastrectomy because of gastric cancer at our Department of Surgery from Jan. 1998 to Dec. 2007. The patients were divided into Group I (n=479) who underwent hand-sewn gastrojejunostomy, Group II (n=48) who underwent linear stapled gastrojejunostomy and Group III (n=864) who underwent circular stapled gastrojejunostomy. Group III was re-divided into two subgroups on the basis of the point of time that a visual check was intraoperatively performed at the anastomotic site: Group III-A (n=198) before and Group III-B (n=666) after. The characteristics and complications of the patients were then compared. Results: For the comparison of the complications between Group I, Group II and Group III, anastomotic leakage was found in 7 cases (1.5%) in Group I, in 1 case (2.0%) in Group II and in 10 case (1.2%) in Group III, and anastomotic stenosis were found in 4 cases (0.8%) in Group I, 1 case (2.0%) in Group II and 5 case (0.6%) in Group III. Anastomotic bleeding was found in 32 cases (6.7%) in Group I, in 5 cases (10.4%) in Group II and in 67 cases (7.7%) in Group III. For the comparison of complications between Group III-A and Group III-B, anastomotic bleeding was found in 57 cases (28.8%) in Group III-A and 10 cases (1.5%) in Group III-B and the difference was statistically significant (P=0.037). Conclusion: Circular stapled gastrojejunostomy after radical subtotal gastrectomy is recommended because of the safety and feasibility of this technique, but bleeding at the anastomotic site may be the critical issue. In conclusion, direct inspection for bleeding at the anastomotic site during the operation will improve the safety of performing circular stapler anastomosis.

• Journal of the Korean GEO-environmental Society
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• v.13 no.1
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• pp.5-13
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• 2012

For the last decade the amount of waste has rapidly been increased in South Korea and many waste landfills have been built according to government guidelines specifying required systems such as landfill liner, leachate collecting facilities, final cover system, etc. This effort has led the recently constructed landfills to be under well managed sanitary condition. In a meanwhile closed waste-landfill sites in the past before the adoption of the government guidelines exits under unsanitary condition. In these cases untreated leachate flew out to the surroundings due to the absence of liner and leachate collecting facilities and caused groundwater and soils to be contaminated. Waste generated odor and gas also brought civil complaints. Because environmental influences bring serious problems nearby sites, it is required to have unsanitary waste-landfills to be appropriately treated and managed. A study to evaluate environmental influence and contamination level of surroundings nearby and on the unsanitary landfills is necessary before the establishment of "Management guide of closed landfill site." This paper presents an environmental evaluation for the closed site, Doil-dong landfill, according to "Closed landfill management regulation" by Ministry of Environment. "D" landfill, located in Pyeongtaek city, has possobility to contaminate surrounding surfacewater and groundwater by leakage of leachate. The in-situ stabilization carried out to build the DMW(deep soil mixing cutoff wall) wall and drainage systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.789-799
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• 2019

The settlement hardly occurs in structures supported by pile foundation such as abutment, culvert but a cavity is formed in the lower part of a structure. As a result, soil discharged from the lateral ground to the cavity accelerates the settlement of the lateral ground of the structure, resulting in a larger settlement. Therefore, in order to prevent problems caused by cavity under the structure supported by pile foundation, soil Flow Protector (briefly called 'FLP'), which can be easily installed on the side of structure, was developed. In this study, an laboratory model test was carried out to prove the reduction effect of settlement and to estimate the optimal installation length of the FLP. As a result, the installation of the FLP reduced the settlement of the lateral ground and prevented the leakage of lateral ground soil into the cavity. If the stiffness of the FLP is small, the state or active earth pressure is generated in the upper part, which is not favorable for stability. But if the stiffness of the FLP is high enough, the passive earth pressure area is generated in the upper part, which will be advantageous for the stability. Also, the increased installation length of FLP is effective to reduce the settlement. And the ratio of the optimal length of the FLP to the box structure height (H = 250 mm) are flexible FLP 1.38, stiff FLP 0.73.

• Annals of Clinical Neurophysiology
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• v.11 no.2
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• pp.41-47
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• 2009

Background: Discogenic pain can develop into chronic low back pain that is very difficult to treat effectively, because the pathogenesis of the disease still remains controversial. To clarify the pathogenesis, numerous animal models of intervertebral disc degeneration have been proposed in the literature, each with attendant advantages and disadvantages. The aim of this study was to determine the most efficacious method and dose of complete Freund's adjuvant (CFA) injection into intervertebral disc to develop a discogenic pain in a rat. Methods: CFA was injected into the L5-L6 or L4-L5 disc of male Sprague-Dawley rats in various conditions including a dose of CFA (10, 20, or 50 uL), drilling, injection site sealing using cyanoacrylate, and injection velocity. Sham animals were subjected to the same procedure, except for the CFA injection. Mechanical and heat allodynia were serially measured at both hindpaws until 8 weeks post-operatively. Serial MRI analyses were performed to observe degenerative changes of the discs. In addition, CGRP & Substance P-immunoreactivities (ir) in the superficial dorsal horn were evaluated at 4 weeks using immunohistochemistry. Results: Each condition provoked various problems such as development of hindpaw paralysis, CFA leakage, and no pain development. Mid-sagittal T2 MRI revealed no significant degenerative changes in the CFA injected disc. The CGRP-ir of the bilateral superficial dorsal horns at the level of L5-L6 was significantly increased in the CFA group. Conclusions: A total of 10 uL CFA injection into L5-L6 disc for a period of 10 minutes using a 26-gauge needle without drilling was the most efficacious way to develop discogenic pain animal model.

• The Korean Journal of Pain
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• v.18 no.2
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• pp.204-207
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• 2005

Background: Transpedicular percutaneous vertebroplasty, along with kyphoplasty of the thoracic vertebrae, is technically more difficult than those of the lumbar vertebrae due to the anatomical differences. During the last four years, all the percutaneous vertebroplasty and kyphoplasty of the thoracic vertebrae carried out at our institution were performed using a transpedicular approach; therefore, we tried to find if there were any problems or complications associated with the process. Methods: The medical records of all the patients who had undergone thoracic percutaneous vertebroplasty or kyphoplasty were retrospectively reviewed. The following were looked up: the procedure name, unipedicular or bipedicular, the level of the thoracic vertebrae treated, and the pre- and postoperative changes in the Visual Analog Scales (VAS), the volume of cement injected and complications. Results: In the last four years, 58 vertebral bodies in 58 patients were treated. Twelve and 46 vertebral bodies were treated by kyphoplasty and vertebroplasty, respectively. A total of 58 mid and lower thoracic levels were treated: T5 (n=1), T6 (n=1), T7 (n=3), T8 (n=4), T9 (n=1), T10 (n=4), T11 (n=14) and T12 (n=30). The mean preoperative and postoperative VAS scores were $8.1{\pm}1.4$ and $5.2{\pm}1.7$, respectively. The mean volume of cement injected was $4.01{\pm}1.85ml$; $3.18{\pm}0.60ml$ at T5-8 and $4.22{\pm}2.27ml$ at T9-12. There were no clinical complications, such as pedicular fracture or cement leakage. Conclusions: Although transpedicular vertebroplasty and kyphoplasty at the mid to lower thoracic vertebral bodies is technically difficult compared to that at the lumbar region, the procedures can be performed safely.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.735-747
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• 2019

Due to the lack of ground space by urbanization, the demand of utility tunnels for laying social facilities is increasing. During the construction of a utility tunnel in downtown area using a shield TBM, various problems may occur when difficult ground is encountered such as mixed ground and cobbly ground. Thus, in this study, using MIDAS GTS NX (Ver. 280), a numerical analysis was performed on characteristics of difficult ground, reinforced area, depth of cover and groundwater level to analyze the optimal ground reinforced area according to combination of parameters. As a result, it was difficult to secure stability in unconstrained excavation cases on both the mixed ground and the cobbly ground. However, when ground reinforcement grouting as much as 2.0D is applied, convergence occurred within the allowable limit, except for mixed ground with a depth of cover 30 m. In addition, excessive leakage occurred during excavation of both the mixed ground and the cobbly layers. It was able to secure stability after applying waterproof grouting.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.117-127
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• 2006

Recently International Water Association(IWA) has proposed new performance indicators for water supply services and their successful applications are being reported continually. According to the various reports, the percentage indicators were suggested not to be used for performance comparison, especially where the targeted areas have great difference in consumption per service connection. But unfortunately in Korea the revenue water ratio, one of the percentage indicators is still being used to set up the goal of water-related administration and to compare the performances between systems. Therefore this study aimed to prove the inapplicability of the percentage indicators with nation-wide data and to suggest better performance indicators for more efficient water loss management. According to the result of the comparison of various performance indicators with conventional one, it is roved that percentage indicators ca not evaluate the performance efficiently where the local situations are significantly different. It is suggested that the better performance indicators such as real losses per service connection or ILI should be used to benchmark the performances of water suppliers on water loss management so thai the problems of water losses could be identified easily and recovered effectively.

• Journal of Biomedical Engineering Research
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• v.38 no.2
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• pp.62-73
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• 2017

To identify a solution for the restricted availability of healthy lungs and the high risk of immune rejections following organ transplantation, tissue engineering techniques for culturing lungs have been studied by many research groups. The most promising method for culturing lungs is the utilization of a bio-scaffold that was prepared using harvested organs from human donors or other animals by removing their original cells. In this study, a pulsatile perfusion pump was used to alleviate the cell removal effect with the high fluid-dynamic power of the perfusion stream during the decellularization process, while other conventional studies focused on chemical methods to identify efficient detergents. The purpose of this study was to analyze the developed device by using energy equivalent pressure (EEP), which is an indicator of pulsatility, to understand the characteristics of pulsatile energy transmitted according to the load size by using the artificial model and compare it with the measured EEP. The pulsatility of the device can be estimated with the concept of fluid-dynamic energy during a particular constant time period or fluid-dynamic power represented as EEP and EEP increment. Because the measured EEP of perfusion flow during decellularization can be changed by the amount of fluid leakage and the degree of clogging in the capillary vessels, EEP should be measured to determine whether the decellularization is progressing without problems. The decrement of EEP caused by the high perfusion resistance was observed from some experimental results that were obtained with artificial models. EEP can be used to monitor the decellularization process after analyzing the varying EEP according to the amount of load. It was confirmed that the EEP was maintained at a high level in the experiment using the harvested lungs from 12-13-week-old rats. In addition, it was confirmed that the cell removal time was faster than when continuous perfusion was performed. In this study, pulsatile power delivered to the lungs was measured to monitor the process of cell removal, and it serve as the evidence for efficient decellularization.