• Journal of Positioning, Navigation, and Timing
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• v.7 no.2
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• pp.73-90
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• 2018

Various navigation systems are integrated with the Global Navigation Satellite System (GNSS) to improve navigation performance so that continuous navigation information can be obtained even when navigation performance is degraded or navigation is not available due to the outage of GNSS. Time and cost can be reduced by evaluating performance of the integrated navigation system through Modeling and Simulation (M&S) software prior to the deployment of the integrated navigation system. The measurements of the navigation system should be generated to evaluate performance through of the navigation system M&S software. This paper proposes a method of designing a navigation environment generation module in M&S software of the integrated navigation system. To show applicability of the proposed method to M&S software design of the integrated navigation system, functions are verified through MATLAB. And then visual C++ based M&S software for the integrated navigation system is implemented to check the operation of the navigation environment generation module. The reference trajectory is generated and true measurements of Global Positioning System (GPS), Korea Positioning System (KPS), and enhanced Long range navigation (eLoran) are generated from the reference trajectory. The navigation results obtained from the true measurements are compared with the reference trajectories. The results show that the measurements generated using the design generation module by the proposed method are valid and the navigation environment generation module can be applied to M&S software of the integrated navigation system.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.347-352
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• 2012

Understanding infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese infrared satellite, AKARI, provided unique data sets to probe this both at low and high redshifts. The AKARI performed an all sky survey in 6 IR bands (9, 18, 65, 90, 140, and $160{\mu}m$) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can measure the total infrared luminosity ($L_{TIR}$) of individual galaxies much more precisely, and thus, the total infrared luminosity density of the local Universe. In the AKARI NEP deep field, we construct restframe $8{\mu}m$, $12{\mu}m$, and total infrared (TIR) luminosity functions (LFs) at 0.15 < z < 2.2 using 4,128 infrared sources. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and $24{\mu}m$) by the AKARI satellite allows us to estimate restframe $8{\mu}m$ and $12{\mu}m$ luminosities without using a large extrapolation based on a SED fit, which was the largest uncertainty in previous work. By combining these two results, we reveal dust-hidden cosmic star formation history and AGN evolution from z = 0 to z = 2.2, all probed by the AKARI satellite.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.271-276
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• 2017

This project has been conducted to improve the usability of Chatbot Services such as Google(Allo) and Facebook M(Messenger. Based on the evaluation, this study aims to suggest the solutions to improve the usability of domestic Chatbot services and future directions for their development. It provides the overall understanding of the AI Chatbot service and the feature of Chatbot service through literature search. Furthermore, we summarized the current standing and the prospect of domestic messenger-based assistant Chatbot services. For conducting user evaluation, Peter Morville's honeycomb model is applied to in-depth user interviews. The followings are elements that could be amended to improve the service. The service should be incorporated by intuitive elements for users' understanding its functions and eliminate any elements that interfere with usability. The accuracy should be increased to improve the user satisfaction. This research will provide the future guidelines to improve the usability of Chabot services through continuous evaluation by users.

• Journal of Korean Neurosurgical Society
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• v.54 no.6
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• pp.484-488
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• 2013

Objective : To examine the synergistic effects of both computer-assisted cognitive rehabilitation (CACR) and transcranial direct current stimulation (tDCS) on cognitive function in patients with stroke. Methods : The current double-blind, sham-controlled study enrolled a total of 11 patients who were newly diagnosed with stroke. The patients of the tDCS group (n=6) completed sessions of the Korean computer-assisted cognitive rehabilitation program five times a week for 30 minutes a session during a mean period of 18.5 days concomitantly with the anodal tDCS over the bilateral prefrontal cortex combined with the CACR. The patients of the control group (n=5) also completed sessions of the sham stimulation during a mean period of 17.8 days. Anodal tDCS over bilateral prefrontal cortex (F3 and F4 in 10-20 EEG system) was delivered for 30 minutes at an intensity of 2 mA. Cathode electrodes were applied to the non-dominant arm. All the patients were evaluated using the Seoul Computerized Neuropsychological Test (SCNT) and the Korean Mini-Mental State Examination. Results : Mann-Whitney U test revealed a significant difference between the two groups. The patients of the tDCS group achieved a significant improvement in the post/pre ratio of auditory continuous performance test and visual continuous performance test on the SCNT items. Conclusion : Our results indicate that the concomitant use of the tDCS with CACR to the prefrontal cortex may provide additional beneficial effects in improving the cognitive dysfunction for patients with stroke.

• Structural Engineering and Mechanics
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• v.21 no.1
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• pp.67-82
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• 2005

This study analyzes stress intensity factors for a number of periodic edge cracks in a semiinfinite medium subjected to a far field uniform applied load along with a distribution of eigenstrain. The eigenstrain is considered to be distributed arbitrarily over a region of finite depth extending from the free surface. The cracks are represented by a continuous distribution of edge dislocations. Using the complex potential functions of the edge dislocations, a simple as well as effective method is developed to calculate the stress intensity factor for the edge cracks. The method is employed to obtain the numerical results of the stress intensity factor for different distributions of eigenstrain. Moreover, the effect of crack spacing and the intensity of the normalized eigenstress on the stress intensity factor are investigated in details. The results of the present study reveal that the stress intensity factor of the periodic edge cracks is significantly influenced by the magnitude as well as distribution of the eigenstrain within the finite depth. The eigenstrains that induce compressive stresses at and near the free surface of the semi-infinite medium reduce the stress intensity factor that, in turn, contributes to the toughening of the material.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.963-977
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• 2015

The well-characterized gram-positive bacterium Bacillus subtilis is an outstanding industrial candidate for protein expression owing to its single membrane and high capacity of secretion, simplifying the downstream processing of secretory proteins. During the last few years, there has been continuous progress in the illustration of secretion mechanisms and application of this robust host in various fields of life science, such as enzyme production, feed additives, and food and pharmaceutical industries. Here, we review the developments of Bacillus subtilis as a highly promising expression system illuminating strong chemical- and temperatureinducible and other types of promoters, strategies for ribosome-binding-site utilization, and the novel approach of signal peptide selection. Furthermore, we outline the main steps of the Sec pathway and the relevant elements as well as their interactions. In addition, we introduce the latest discoveries of Tat-related complex structures and functions and the countless applications of this full-folded protein secretion pathway. This review also lists some of the current understandings of ATP-binding cassette transporters. According to the extensive knowledge on the genetic modification strategies and molecular biology of Bacillus subtilis, we propose some suggestions and strategies for improving the yield of intended productions. We expect this to promote striking future developments in the optimization and application of this bacterium.

• Wind and Structures
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• v.7 no.2
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• pp.107-130
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• 2004

This paper presents a time-domain approach for analyzing nonlinear random vibrations of long-span suspended cables under transversal wind. A consistent continuous model of the cable, fully accounting for geometrical nonlinearities inherent in cable behavior, is adopted. The effects of spatial correlation are properly included by modeling wind velocity fluctuation as a random function of time and of a single spatial variable ranging over cable span, namely as a one-variate bi-dimensional (1V-2D) random field. Within the context of a Galerkin's discretization of the equations governing cable motion, a very efficient Monte Carlo-based technique for second-order analysis of the response is proposed. This procedure starts by generating sample functions of the generalized aerodynamic loads by using the spectral decomposition of the cross-power spectral density function of wind turbulence field. Relying on the physical meaning of both the spectral properties of wind velocity fluctuation and the mode shapes of the vibrating cable, the computational efficiency is greatly enhanced by applying a truncation procedure according to which just the first few significant loading and structural modal contributions are retained.

• Molecules and Cells
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• v.44 no.3
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• pp.127-135
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• 2021

Since the introduction of RNA sequencing (RNA-seq) as a high-throughput mRNA expression analysis tool, this procedure has been increasingly implemented to identify cell-level transcriptome changes in a myriad of model systems. However, early methods processed cell samples in bulk, and therefore the unique transcriptomic patterns of individual cells would be lost due to data averaging. Nonetheless, the recent and continuous development of new single-cell RNA sequencing (scRNA-seq) toolkits has enabled researchers to compare transcriptomes at a single-cell resolution, thus facilitating the analysis of individual cellular features and a deeper understanding of cellular functions. Nonetheless, the rapid evolution of high throughput single-cell "omics" tools has created the need for effective hypothesis verification strategies. Particularly, this issue could be addressed by coupling cell engineering techniques with single-cell sequencing. This approach has been successfully employed to gain further insights into disease pathogenesis and the dynamics of differentiation trajectories. Therefore, this review will discuss the current status of cell engineering toolkits and their contributions to single-cell and genome-wide data collection and analyses.

• Journal of Forest and Environmental Science
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• v.39 no.1
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• pp.40-48
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• 2023

Street trees have been incorporated into urban forests to regulate the microclimate and provide shade as well as provide aesthetic and environmental functions and to evaluate their physiological characteristics. Zelkova serrata is a major tree species that has been planted on various South Korean streets. We determined the physiological characteristics of Z. serrata in street trees of Goyang and Paju in Gyeonggi Province. According to survey sites, net CO₂ assimilation rates was 13.9-16.4 µmol CO₂ m^-2s^-1, chlorophyll fluorescence (Fv/Fm) was 0.80-0.82, and proline contents was showed 3.4-3.7 mg g^-1 FW. The studied trees were assumed to be physiologically stressed, but it was found that Z. serrata was planted as street trees were not significantly stressed when compared to chlorophyll fluorescence responses and proline contents. In the future, the continuous monitoring system is needed to evaluate the physiological characteristics of urban trees.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.605-610
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• 2013

Gamma-aminobutyric acid (GABA) is a non-protein amino acid widely present in organisms, which has shown several important physiological functions such as neurotransmission, hypotension induction, as well as diuretic and tranquilizer effects. They have also been extensively used in food industry. GABA contents in the grain and brown rice are about 1~4 mg/100 g and 4~8 mg/100 g, respectively but it is difficult to expect physiological activity from such low amounts of natural food intake. We investigate the effects of GABA-coated rice on the secretion of melatonin and serotonin which both have been used as sleep inductive compounds. As a result, the secretion of melatonin and serotonin from mice were found to be $3.578{\pm}0.158pg/mL$, $5.918{\pm}0.169ng/mL$ respectively. The melatonin and serotonin in mice increased significantly up to the 8.7 and 22.8 times respectively, when compared to that of the rice, but there was no cumulative effects. Due to the continuous intake of GABA-coated rice, which was developed as a functional food nutrient, inductive effects of melatonin and serotonin from general rice could be achieved and also the similar effect as taking up directly 25 mg/mL of GABA could be obtained.