• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.245-253
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• 2021

RC slab bridges account for the largest portion of deteriorated bridges in Korea. However, most RC slabs are not included in the first and second classes of bridges, which are subject to bridge safety management and maintenance. The highest damaged components in highway bridges are the subsidiary facilities including expansion joints and bearings. In particular, leakage through expansion joints causes deterioration and cracks of concrete and exposure of reinforced bars. Therefore, this study analyzed the effect of adhesion damage at expansion joints on the response of the deck in RC slab bridges. When the spacing between the expansion joints at both ends was closely adhered, cracks occurred in the concrete at both ends of the deck due to the resistance rigidity at the expansion joints. Based on the response results, the correlation analysis between displacements in the longitudinal direction of the expansion joint and concrete stress at both ends of the deck for each damage scenario was performed to investigate the effect of the occurrence of damage on the bridge behavior. When expansion joint devices at both sides were damaged, the correlation between displacement and stress showed a low correlation of 0.18 when the vehicles proceeded along all the lanes. Compared with those in the intact state, the deflections of the deck in the damaged case at both sides showed a low correlation of 0.34 to 0.53 while the vehicle passed and 0.17 to 0.43 after the vehicle passed. This means that the occurrence of cracks in the ends of concrete changed the behavior of the deck. Therefore, data-deriven damage detection could be developed to manage the damage to expansion joints that cause damage and deterioration of the deck.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.23-33
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• 2021

In Korea, many reservoirs have been built for the purpose of solving the food shortage problem and supplying agricultural water. However, the current 75.6% of the reservoirs are in serious aged as more than 50 years have passed since the year of construction. In the case of such an aging reservoir, the stability due to scour and erosion inside the reservoir is very reduced, and if concentrated rainfall due to recent abnormal weather occurs, the aging reservoir may collapse, leading to a lot of damage to property and human life. Accordingly, each agency that manages aging reservoirs uses Ordinary Portland Cement (OPC) as an injection material and applies the grouting method. However, in the case of OPC, it may deteriorate over time and water leakage may occur again. And there are environmental problems such as consumption of natural resources and generation of greenhouse gases. So, there is a need to develop new materials and methods that can replace the OPC. In this study, an laboratory test and analysis were performed on the grout material developed to induce a curing reaction similar to that of OPC by recycling power plant byproduct. In addition, test in the field such as electric resistivity survey, Standard Penetration Test (SPT), and field permeability test were performed to analyzed to reinforcement effect and determine the possibility of using instead of OPC. As a results of the test, in the case of recycled power plant byproduct, the compressive strength was 2.9 to 3.2 times and the deformation modulus was 2.3 to 3.3 times higher, indicating that it is excellent in strength and can be used instead of OPC. And it was analyzed that the N value of the reservoir was increased by 1~2, and the coefficient of permeability (k) decreased to the level of 8.9~42.5%. showing sufficient reinforcing effect in terms of order.

• 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.

• The Journal of Engineering Geology
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• v.34 no.2
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• pp.279-294
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• 2024

Large-scale civil engineering structures such as dams require a systematic approach to jointed rock-mass grouting to prevent water leakage into the foundations and to ensure safe operation. In South Korea, rock grouting design often relies on the experience of field engineers that was gained in similar projects, highlighting the need for a more systematic and reliable approach. Rock-mass grouting is affected mainly by hydrogeology and the presence of discontinuities, involving factors such as the rock quality designation (RQD), joint spacing (Js), Lugeon value (Lu), and secondary permeability index (SPI). This study, based on data from field investigations of 14 domestic sites, analyzed the correlation between hydrogeological factors (Lu and SPI), discontinuity characteristics (RQD and Js), and grout take, and systematically established a design method for rock grouting. Analysis of correlation between the variables RQD, Js, Lu, and SPI yielded Pearson correlation (r) values as follows: Lu-SPI, 0.92; RQD-Lu, -0.75; RQD-Js, 0.69; RQD-SPI, -0.65; Js-Lu, -0.47; and SPI-Js, -0.41. The grout take increases with Lu and SPI values, but there is no significant correlation between RQD and Js. The proposed approach for grouting design based on SPI values was verified through analysis and comparison with actual curtain-grouting construction, and is expected to be useful in practical applications and future studies.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.2
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• pp.179-185
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• 2004

Purpose: Perinatal mortality rates have been used as a summary statistic for evaluating child health and medical status. Neonatal mortality rates have decreased over the past 30 years in Korea. To understand the current status of neonatal surgical gastrointestinal diseases in Daegu Busan area, we have studied about neonatal gastrointestinal diseases with their clinical features, postoperative outcome, and mortality rates. Methods: A clinical analysis on 202 neonates who underwent neonatal surgery from January 1996 to July 2003 at Pusan National University, Kyungpook National University, Youngnam University, and Daegu Catholic University was carried out. Results: The main diseases of surgical conditions were anorectal malformation (23.8%), atresia/stenosis of midgut (13.4%) and pyloric stenosis (13.4%). The male to female ratio was 2.8 : 1. Thirty-five cases (17.0%) had one or more associated anomalies including congenital heart disease, cryptoorchidism, hydronephrosis, and chromosomal anomaly. Twenty cases (10.0%) were diagnosed by antenatal ultrasound. Patients with esophageal atresia had the longest hospitalization for 54.6 days. Postoperative complications occurred in 18 cases (8.9%). The main postoperative complications were wound infection (3.5%) and anastomotic leakage (2.5%). Overall mortality was 5.9%. Diaphragmatic hernia showed the highest mortality rate (37.5%), and esophageal atresia (28.6%) and omphalocele (20.0%) were followed. Conclusion: The current status of neonatal surgical gastrointestinal diseases in Daegu Busan area has improved because the disease categories are various, postoperative complications and mortality rates are decreased.

• Journal of Korean Neurosurgical Society
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• v.29 no.11
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• pp.1437-1444
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• 2000

Objectives : Traditionally intracranial meningiomas are regarded as benign and curable tumors. About half of all intracranial meningiomas locate in the skull base region. However, surgical removal of these tumors may be challenging and require special considerations. Here general aspects of skull base meningiomas including clinical presentation, surgical approaches, complications and their recurrence rate are discussed based on our experiences. Methods : A retrospective analysis of 61 consecutive patients with skull base meningioma among 210 patients of meningioma between 1989 and 1998 were done. Results : There were 41 women and 20 men ranging from 13 to 74 years(mean 52 years). These tumors were divided into seven categories according to location : olfactory groove(n＝9), sphenoid ridge(n＝16), cavernous sinus(n ＝2), tuberculum sellae(n＝8), tentorium(n＝13), cerebellopontine angle(n＝12), and foramen magnum meningiomas (n＝1). Surgical approaches were selected on the basis of the tumor attachment, size and extension on preoperative radiologic findings. Total removal(Simpson grade I and II) was achieved in 50 cases(82%), and subtotal removal (Simpson grade III) in 11 patients(18%). According to WHO classification, there were 52 of cases of benign meningioma( 86%), 6 atypical cases(10%), and 3 malignant cases(5%). The most common postoperative complications were CSF leakage(23.0%) and cranial nerve injury(8.2%). Three patient died related with tumor(one was due to surgical complication and the other two due to recurrence) but three patients died from other systemic causes. Mean follow-up period was 51.7 months after surgery. Recurrence occurred in six patients(10.9%) ; three with tentorial meningioma, two with sphenoid ridge, and one in cerebellopontine angle. Conclusion : With advances in neuroradiology and microsurgical techniques, the surgical outcome of miningiomas has been markedly improved with acceptable morbidity and mortality rates. Overall, our surgical results of skull base meningiomas is comparable to other reports. Therefore, with the appropriate operative strategy and techniques, these tumors can be completely removed and good surgical results can be expected.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.7
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• pp.37-43
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• 2008

In this paper, the dependence of electrical characteristics of Silicon-$Al_2O_3$-Nitride-Oxide-Silicon (SANOS) memory cell transistors and program/erase (P/E) speed, reliability of memory device on interface trap between Si substrate and tunneling oxide and bulk trap in nitride layer were investigated using charge pumping method which has advantage of simple and versatile technique. We analyzed different SANOS memory devices that were fabricated by the identical processing in a single lot except the deposition method of the charge trapping layer, nitride. In the case of P/E speed, it was shown that P/E speed is slower in the SANOS cell transistors with larger capture cross section and interface trap density by charge blocking effect, which is confirmed by simulation results. However, the data retention characteristics show much less dependence on interface trap. The data retention was deteriorated as increasing P/E cycling number but not coincides with interface trap increasing tendency. This result once again confirmed that interface trap independence on data retention. And the result on different program method shows that HCI program method more degraded by locally trapping. So, we know as a result of experiment that analysis the SANOS Flash memory characteristic using charge pumping method reflect the device performance related to interface and bulk trap.

• Journal of Hospice and Palliative Care
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• v.19 no.4
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• pp.303-309
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• 2016

Purpose: Malignant ascites is a common complication in terminal cancer patients. Less-invasive pigtail catheter insertion is the most frequent procedure in patients who need repeated ascites drainage. This study investigated effects and adverse events associated with catheter insertion for ascites drainage and evaluated prognostic outcomes. Methods: We reviewed medical records between 2010 and 2013 of hospice and palliative care institutions in Seoul, South Korea. Among 2,608 inpatients, 67 patients received ascites pigtail catheter drainage. We reviewed demographic data, palliative performance scale, laboratory data, duration of catheter insertion, prevalence and type of complications, use and duration of antibiotics, and survival time. Univariate and multivariate Cox regression models were used to evaluate prognostic outcomes related with catheter insertion. Results: Ascites drainage was performed most commonly in hepatobiliary and gastric cancer patients. Ascites symptoms improved in 55 patients after the catheter drainage. Adverse events included pain (19.4%), leakage (14.9%), disconnection (7.5%), catheter occlusion (6%) and fever (4.5%). In Cox regression analysis, survival time from the catheter insertion was significantly associated with Palliative Performance Scale (PPS) (HR 0.73; P value 0.045) and serum sodium level (HR 2.77; P value 0.003) in a multivariate model. Conclusion: Patients' PPS and serum sodium level should be considered before making a decision of pigtail catheter insertion.

• Journal of Wetlands Research
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• v.17 no.4
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• pp.391-401
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• 2015

In this study, divided into small category groups for the residential area it was carried out monitoring for the runoff during precipitation. Based on the results analyzed according to the nonpoint sources Housing leakage characteristics. Analysis of the rainfall runoff and concentration of each type of exclusive detached house with apartments, in the majority of precipitation types runoff concentrations were higher in early. In the case of a difference of two points per runoff rate rainfall it was largely investigation. The average runoff is estimated loadings of BOD $101.1kg/km^2$, SS $232.2kg/km^2$, T-N $18.2kg/km^2$, T-P $2.0kg/km^2$ detached house case, if the apartment was estimated at point BOD $108.82kg/km^2$, SS $329.18kg/km^2$, T-N $57.67kg/km^2$, T-P $4.21kg/km^2$. The average EMCs is BOD BOD 6.6 mg/L, SS 12.8 mg/L, T-N 1.518 mg/L, T-P 0.099 mg/L detached house case, if the apartment was estimated at point BOD 6.3 mg/L, COD 11.2mg/L, SS 14.5 mg/L, T-N 3.1 mg/L, T-P 0.2 mg/L. The initial 30 percentage calculated based on the initial results, the total flow of 30% if the outflow of detached house showed a net percentage difference to T-P 1.04 > T-N 0.97 > BOD 0.90 > SS 0.80. The apartment area showed the percentage difference in the water quality in the order of BOD 1.49 > T-P 1.40 > SS 1.30 > T-N 0.96 per item.

• Journal of Life Science
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• v.28 no.11
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• pp.1354-1360
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• 2018

The aim of this study was to develop a simple, environmentally friendly synthesis of silver nanoparticles (SNPs) without the use of chemical reducing agents by exploiting the extracellular synthesis of SNPs in a culture supernatant of Bacillus thuringiensis CH3. Addition of 5 mM $AgNO_3$ to the culture supernatant at a ratio of 1:1 caused a change in the maximum absorbance at 418 nm corresponding to the surface plasmon resonance of the SNPs. Synthesis of SNPs occurred within 8 hr and reached a maximum at 40-48 hr. The structural characteristics of the synthesized SNPs were investigated by various instrumental analysis. FESEM observations showed the formation of well-dispersed spherical SNPs, and the presence of silver was confirmed by EDS analysis. The X-ray diffraction spectrum indicated that the SNPs had a face-centered cubic crystal lattice. The average SNP size, calculated using DLS, was about 51.3 nm and ranged from 19 to 110 nm. The synthesized SNPs exhibited a broad spectrum of antimicrobial activity against a variety of pathogenic Gram-positive and Gram-negative bacteria and yeasts. The highest antimicrobial activity was observed against C. albicans, a human pathogenic yeast. The FESEM observations determined that the antimicrobial activity of the SNPs was due to destruction of the cell surface, cytoplasmic leakage, and finally cell lysis. This study suggests that B. thuringiensis CH3 is a potential candidate for efficient synthesis of SNPs, and that these SNPs have potential uses in a variety of pharmaceutical applications.