• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.449-455
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• 2016

This study is a part of research to develop a steel-concrete hybrid girder using ultra high-performance concrete with a compressive strength of 80 MPa. To this end, the Eurocode design formula for the shear resistance developed in a concrete-to-concrete interface was examined for the interface between concrete layers of different strengths. To examine the effect of the surface roughness on the shear resistance, a push-out test was conducted on specimens while considering the parameters of the Eurocode design equation. The actual behavior was evaluated with respect to the compressive strength of the concrete, the reinforcement ratio of the shear rebar, and the interfacial surface condition. The specimen with a rough interface shows 20-50% higher shear strength than that estimated by the design equation. In the case of failure mode, abrupt failure tends to occur at the interface of the concrete layer for the specimen with a low reinforcement ratio. It is expected that the shear strength of the concrete layer will increase according to the strength differential in the concrete layers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.61-69
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• 2011

Fiber Reinforced Plastic (FRP) sheets have been widely used to retrofit and rehabilitate RC structures, while in case of retrofitting steel structures, there are no codes and researches. It stems from configuration of member and characteristics of bonding behavior. This study focused on the static behavior of steel beams reinforcement by AFRP sheets. The main objective of the experimental programme was the evaluation of the force transfer mechanism, the increment of the beam load carrying capacity and the bending stiffness. A bending test was conducted on a H-shaped steel beam, with aramid FRP sheets bonded to its flanges. The mid-span deflection and the strain from three points along AFRP sheets were recorded Test results exhibit that the increment of the load-carrying capacity with reference to a mid-span deflection level of 15 mm(1/125mm of the clear span) was equal to 9.4% and for the two layers case, an elastic stiffness increment is slightly higher than one layer case.

• Korean journal of food and cookery science
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• v.14 no.1
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• pp.1-8
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• 1998

The characteristics of Kimchi, associated with proceeding velocity of fermentation, and microbial changes, were investigated during fermentation where kimchi were prepared by the addition of different kinds of minor ingredients. In all samples, total acidity increased, and the pH and total reducing sugar content decreased as the fermentation proceeded. Redox potentials decreased from early to middle fermentation period but thereafter increased and had the lowest value at optimum ripening stage. The counts of total viable and lactic acid bacteria increased rapidly at the begining and decreased slowly. These bacterial counts of kimchi samples containing ginger, red pepper powder, and mixture of all minor ingredients were higher than those of other samples. The number of Leuconostoc mensenteroides reached the maximum at the optimum fermenting stage, Lactobacillus plantarum appeared at the time when Leu. mesenteroides reduced. All these phenomena were observed earlier in the samples containing raw red pepper and later in the samples added garlic than in other samples. It is suggested that garlic is the ingredient which improved storage capacity by prolonging fermentation period by lactic acid bacteria beneficial to less acidification, and ginger and red pepper powder are materials which gave better taste to kimchi by stimulating the growth of Leu. mesenteroids. And redox potential was an useful indicator in choosing optimum ripening time during fermentation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.165-174
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• 1993

This work was conducted to study the use of L. acidophilus, which exists in humun intestine for the fermentation of Chinese cabbage kimchi. The changes in vitamins, the number of microflora and sensory quality were observed during fermentation after the microflora which was not related to kimchi fermentation was eliminated by treatment with ozone water or ozone gas. The growth rate of L. acidophilus in the cabbage juice was higher than that in MRS broth. The growth of L. acidophilus was slightly promoted by adding 1~2% hot pepper powder while that was inhibited by ginger and garlic. Therefore, it was shown that the regulation of fermentation was possible by addition of spices. The result of treating spice with ozone gas and ozone water 6mg/L/sec for 1 hour was that the survival ratio of total microflora was 6~20%. When L. acidophilus was added to materials after ozone treatment, the fermentation rate was improved and the polysaccharides in the cell wall were used when the usable free sugar was all consumed. The contents of vitamin B$_1$ and C in the ozone treated kimchi was higher than in the control.

• The Journal of the Acoustical Society of Korea
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• v.28 no.1
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• pp.77-83
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• 2009

This paper proposes a new noise-biased compensation of minimum statistics(MS) method using a nonlinear function and a priori speech absence probability(SAP) for speech enhancement in non-stationary noisy environments. The minimum statistics(MS) method is well known technique for noise power estimation in non-stationary noisy environments. It tends to bias the noise estimate below that of true noise level. The proposed method is combined with an adaptive parameter based on a sigmoid function and a priori speech absence probability (SAP) for biased compensation. Specifically. we apply the adaptive parameter according to the a posteriori SNR. In addition, when the a priori SAP equals unity, the adaptive biased compensation factor separately increases ${\delta}_{max}$ each frequency bin, and vice versa. We evaluate the estimation of noise power capability in highly non-stationary and various noise environments, the improvement in the segmental signal-to-noise ratio (SNR), and the Itakura-Saito Distortion Measure (ISDM) integrated into a spectral subtraction (SS). The results shows that our proposed method is superior to the conventional MS approach.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.5
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• pp.1153-1166
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• 2015

With the acceleration of information digitization caused by fast growth of Information Technology, the application of digital forensics has increased but it is underestimated because digital evidence is easy to forge. Especially, the evaluation of the reliability of digital forensics organization is judged only by judges domestically because there is no objective verification system or evaluation method of the capability of digital forensics organization. Therefore, the evaluation model and indices of the capability of digital forensics concentrated on the digital forensics organization, personnel, technology, facilities and the procedure in domestic justice system was presented in this research after reviewing the domestic and foreign evaluation method and the standard of the capability of digital forensics and information security. The standard for judicial evaluation of digital evidence and composition, management, evaluation of digital forensics organization would be presented based on this research.

• Journal of the Korea Institute of Building Construction
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• v.21 no.4
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• pp.347-359
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• 2021

Recently, construction projects have emerged in the form of program management, which is complicated by the large-scale of construction, and requires astronomical construction costs. In particular, projects that absolutely require management at the program level, such as large-scale construction projects, require overall control of the planned schedule and cost as a set of various projects, including infrastructure. But in Korea, there is no specific management standard for delays in construction. In order to avoid the risk of cost increase and project delay in the program-level construction project, it is necessary to apply more systematic management standards to prevent delay and to take a more preemptive response in the construction process. Therefore, in this study, a delay management index (DMI) was developed to successfully carry out large-scale construction projects at the program level and prevent delays in advance. In addition, case studies were conducted for large-scale construction projects, and a delay prevention system was established for program-level construction projects.

• Journal of Convergence for Information Technology
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• v.12 no.1
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• pp.83-90
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• 2022

In order for effective informatics education it is premisd that students have digital literacy. But the absence of informatics education for about 10 years has make students have low digital literacy, and as a result, there are many voices in the school field that it is difficult to have a smooth class. Therefore in this study, the elements of digital literacy required to efficiently operate the 2015 middle school informatics curriculum and digital literacy of middle school students was analyzed. As a result, the students showed biased use of the computing devices and software the frequently use. They were inexperienced in using hardware necessary for learning, understanding basic terms for online collaboration, understanding operating systems, information searching, and producing documents. This study is meaningful in that it provides basic data that serves as a guideline for the direction of digital literacy education for effective informatics education.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.104-115
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• 2023

User-centered public transportation services such as DRT, Autonomous Transit etc. have been provied but current minimum level of service for public transportation has been evaluated by the operator because there is no data on user's accessibility to use public transportation. This study was performed GRID analysis using altteul transport card data including user's accessibility to use public transportation. The analysis result showed that user's accessibility to use public transportation was different within a same dong area. We proposed improving minimum level of service for public transportation considered by the user. The result of applying the proposed method showed that many area was changed to unsatisfied area for minimum level of service for public transportation

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.237-240
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• 2008

The objective of this study is to evaluate the seismic performance of the low-rise RC apartment buildings having piloties at ground level by using nonlinear static analysis with regards to the maximum considered and design earthquakes in Korea. To do this, the target displacement at roof was estimated according to FEMA356 (or ASCE/SEI-41), and the deformations of the critical members were compared with the failure criteria of Life Safety(LS) and Collapse Prevention(CP) given in FEMA356. The conclusions are as follows: (1) columns satisfy criteria of LS and CP, but (2) the shear wall in the longitudinal direction failed to satisfy those of both LS and CP while those in the transverse direction satisfy that of LS, but failed that of CP.