• Journal of the Korean GEO-environmental Society
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• v.16 no.11
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• pp.5-11
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• 2015

The development of Controlled Low Strength Material (CLSM), which is a highly flowable material, has been performed for the application of backfill. The objective of this study is to compare the compressive strength and compressive wave velocity of CLSM according to the curing time. To investigate the characteristics of the CLSM consisting of sand, silt, water, flyash, and CSA cement, uniaxial compression test and flow test were carried out. For the measurement of compressional waves, a cell and a couple of transducers were used. The test results show that the compressive strength increases with the curing time, while the increment of compressive strength decreases with the curing time. In addition, the compressive wave velocity increases with the curing time, and the correlation between the compressive wave velocity and compressive strength is similar to exponential function. This study suggests that the correlation between the compressive wave velocity and compressive strength may be effectively used for the estimation of compressive strength of the CLSM at early curing time.

• Journal of the Korean Geotechnical Society
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• v.31 no.2
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• pp.39-46
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• 2015

Dielectric constant depends on the variation of soil water content, and the estimation of soil water content using time domain reflectometry (TDR) has been studied by many researchers. The purpose of this study is the development and application of TDR penetrometer (TDRP) in order to evaluate the soil water content according to the penetration depth. The TDRP consists of cone, sleeve, driving rod, hammer, and guide. Three electrodes, which are used to measure the dielectric constant of soils, are mounted on the surface of sleeve and, in turn, connected with coaxial cable and time domain reflectometer. To establish the relationship between the volumetric water content and dielectric constant, several laboratory tests by using the TDRP are performed in the specimens with a variety of volumetric water content. The experimental results show that the dielectric constant is strongly correlated to volumetric water content as polynomial equations with an order of 3. In addition, the volumetric water content calculated from the dielectric constant is similar to that obtained from the sample weight. In the field, a small sampler is used to compare the volumetric water content calculated from the dielectric constant with the volumetric water content obtained from the sample. The results of field application demonstrate that the volumetric water content estimated by the TDRP shows similar trend to the gravimetric water content of sample. This study suggests that the TDRP is effectively used to evaluate the volumetric water content of unsaturated soils according to the penetration depth.

• Tuberculosis and Respiratory Diseases
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• v.72 no.2
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• pp.149-155
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• 2012

Background: This study is to evaluate the effect of systemic corticosteroid on the clinical outcomes and the occurrence of complications in mechanical ventilated patients with severe community-acquired pneumonia (CAP). Methods: We retrospectively assessed the clinical outcomes and complications in patients with severe CAP admitted to ICU between March 1, 2003 and July 28, 2009. Outcomes were measured by hospital mortality after ICU admission, duration of mechanical ventilation (MV), ICU, and hospital stay. Complications such as ventilator associated pneumonia (VAP), catheter related-blood stream infection (CR-BSI), and upper gastrointestinal (UGI) bleeding during ICU stay were assessed. Results: Of the 93 patients, 36 patients received corticosteroids over 7 days while 57 patients did not receive corticosteroids. Age, underlying disease, APACHE II, PSI score, and use of vasopressor were not different between two groups. In-hospital mortality was 30.5% in the steroid group and 36.8% in the non-steroid group (p>0.05). The major complications such as VAP, CR-BSI and UGI bleeding was significantly higher in the steroid group than in the non-steroid group (19.4% vs. 7%, p<0.05). The use of steroids and the duration of ICU stay were significantly associated with the development of major complications during ones ICU stay (p<0.05). Conclusion: Systemic corticosteroid in patients with severe CAP requiring mechanical ventilation may have no beneficial effect on clinical outcomes like duration of ICU stay and in-hospital mortality but may contribute to the development of ICU acquired complications.

• Journal of the Korean Society for Library and Information Science
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• v.47 no.4
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• pp.143-167
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• 2013

The power of human capital in a library is the main resource that determines the level of library services, which in turn should play a pivotal role in forming the intellectual power of the country. This research conducted a survey on the employment perspectives of LIS undergraduates, which resulted as follows. First, among the LIS undergraduates, 40% of students responded that their desire was to be employed in the library as librarians. Although there were some negative opinions regarding the working environment of the industry, the undergraduates appreciated the developmental possibilities. Second, the most desired task was working with cultural programs. Third, the respondents were satisfied with the current curriculum overall, acknowledging the extra need for job search support programs, which include career support, employment-related mentoring, and internships. Fourth, the main requirements for their future employability were perceived as grade point average, language skills, obtaining licenses, internship and apprenticeship experience, and career management. Fifth, influential factors on employment decision making were divided into two aspects: environmental and personal factors. The environmental factors included salary, welfare, opportunities in personal development, workplace environment, organizational culture, and development possibilities of the organization. The personal factors included fitness with personal aptitude, the level of knowledge and technology in the job industry, social norms and acknowledgement, rewarding opportunities with their major, and location of job.

• Journal of The Korean Society of Grassland and Forage Science
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• v.29 no.3
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• pp.165-170
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• 2009

A system for the production of transgenic plants has been developed for perennial ryegrass (Lolium perenne L.) via Agrobacterium-mediated transformation. Included in this study were two factors which may affect the gene transfer efficiency: concentrations of acetosyringone (AS, 0 to 300 ${\mu}M$), and co-culture period (1 to 7 days). Both factors were very important to achieve high efficiency gene transformation in the perennial ryegrass. The highest transformation efficiency was obtained when embryogenic calli were inoculated with Agrobacterium in the presence of 100 ${\mu}M$ AS with the culture medium for 5 days. Phosphinothricin resistant calli were developed with into complete plants. GUS histochemical assay, polymerase chain reaction (PCR) and Northern blot analysis of transgenic plants demonstrated that transgenes were integrated into the genome of perennial ryegrass. Using this protocol, it was possible to obtain transformants efficiently for further study.

• Korean Journal of Microbiology
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• v.41 no.3
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• pp.177-182
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• 2005

H. pylori strains were isolated from antral biopsies taken during upper endoscopy in 114 dyspeptic patients with no previous therapy against H. pylori. Rapid urease test, PCR amplification of SSA and cagA gene for H. pylori detection, and Western blot for CagA expression detection were performed. H. pylori infected patients were treated with omeprazole, clarithromycin (a macrolide), and amoxicillin. At 6 weeks after the discontinuation of therapy, the bacterial eradication rate was determined by endoscopy. The resistance rate to clarithromycin and amoxicillin was $20.2\%$ and $0.0\%$, respectively. The clarithromycin resistance was mainly caused by the A2142G mutation in the 23S rRNA gene of H. pylori. MICs of clarithromycin for the A2142G mutant isolates were significantly higher than MICs for the A2143G mutant isolates. H. pylori eradication was obtained in all patients with clarithromycin-susceptible isolates but not in patients with clarithromycin-resistant isolates (P = 0.0001). These results did not appear to be biased by any differences in CagA expression. The resistance of H. pylori to clarithromycin included in the therapeutic regimens is the most important reason for treatment failure. H. pylori antimicrobial susceptibility testing of the gastric biopsy culture should be performed before choosing the first triple therapy in infected patients and the increase in prevalence of clarithromycin resistance in Korea was problematic.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3472-3480
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• 2010

The Clustering technology of Energy efficiency wireless sensor network gets the energy efficiency by reducing the number of communication between sensor nodes and sink node. In this paper, First analyzed on the clustering technique of the distributed clustering protocol routing scheme LEACH (Low Energy Adaptive Clustering Hierarchy) and HEED (Hybrid, Energy-Efficient Distributed Clustering Approach), and based on this, new energy-efficient clustering technique is proposed for the cause the maximum delay of dead nodes and to increase the lifetime of the network. In the proposed method, the cluster head is elect the optimal efficiency node based on the residual energy information of each member node and located information between sink node and cluster node, and elected a node in the cluster head since the data transfer process from the data been sent to the sink node to form a network by sending the energy consumption of individual nodes evenly to increase the network's entire life is the purpose of this study. To verify the performance of the proposed method through simulation and compared with existing clustering techniques. As a result, compared to the existing method of the network life cycle is approximately 5-10% improvement could be confirmed.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.43-52
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• 2011

The characteristics of shear zone in granular soils largely affect the stability of geo-structures. The goal of this study is to evaluate shear zone in a direct shear test using shear wave, electrical resistivity, and cone tip resistance. Bender elements and electrical resistivity probe are embedded into the wall of a direct shear box made of transparent acrylic material to estimate the shear wave velocities and the electrical resistivity at shear and non-shear zones. At the point of peak and residual strength, micro cone penetration test which can be available to measure tip resistance has been performed. Experimental results show that the shear wave velocities at upper shear zone increase during shearing while the values remain constant at bottom and lower shear zone. Also, resistivities at lower shear zone depend on relative density while resistivities at bottom remain constant. The results of cone penetration test demonstrate the correlation of the cone tip resistance and small strain shear modulus at shear zone. This study suggests that the application of the modified direct shear box including shear wave, electrical resistivity and the micro cone tip resistance may become effective tools for analyzing the characteristics of a shear zone.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.385-390
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• 2016

ELoran Systems can provide Position, Navigation, and Time services with comparable performance to Global Positioning Systems (GPS) as a back up or alternative system. High timing and navigation performance can be achieved by eLoran signals because eLoran receivers use "all-in-view" reception. This incorporates Time of Arrival (TOA) signals from all stations in the service range because each eLoran station is synchronized to Coordinated Universal Time (UTC). Transmission station information and the differential Loran correction data are transmitted via an additional Loran Data Channel (LDC) on the transmitted eLoran signal such that eLoran provides improved Position Navigation and Timing (PNT) over legacy Loran. In this paper, we propose a technique for adapting the delay time compensation values in eLoran timing receivers to provide precise time comparison. For this purpose, we have designed a system that measures time delay from the crossing point of the third cycle extracted from the current transformer at the end point of the transmitter. The receiver delay was measured by connecting an active H-field, an E-field and a passive loop antenna to a commercial eLoran timing receiver. The common-view time transfer technique using the calibrated eLoran timing receiver improved the eLoran transfer time. A eLoran timing receiver calibrated by this method can be utilized in the field for precise time comparison as a GNSS backup.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.217-231
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• 2017

The subsidence of ground in urban area can be caused by the occurrence of the cavity and the change in ground volumetric water content. The objective of this study is the detection of abnormal area of ground in urban area where the cavity or the change in ground volumetric water content is occurred by the ground penetrating radar signal. GPR survey is carried out on the test bed with a circular buried object. From the GPR survey, the signals filtered by the bandpass filtering are measured, and the methods consisting of gain function, time zero, background removal, deconvolution and display gain are applied to the filtered signals. As a result of application of the signal processing methods, the polarity of signal corresponds with the relation of electrical impedance of the cavity and the ground in test bed. In addition, the relative permittivity calculated by GPR signal is compared with that of predicted by volumetric water content of the test bed. The relative permittivities obtained from two different methods show similar values. Therefore, the abnormal area where the change in ground volumetric water content is occurred can be detected from the results of the GPR survey in case the depth of underground utilities is known. Signal processing methods and estimation of relative permittivity performed in this study may be effectively used to detect the abnormal area of ground in urban area.