• Genomics & Informatics
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• v.21 no.1
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• pp.12.1-12.8
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• 2023

A wave of new technologies has created opportunities for the cost-effective generation of high-throughput profiles of biological systems, foreshadowing a "data-driven science" era. The large variety of data available from biological research is also a rich resource that can be used for innovative endeavors. However, we are facing considerable challenges in big data deposition, integration, and translation due to the complexity of biological data and its production at unprecedented exponential rates. To address these problems, in 2020, the Korean government officially announced a national strategy to collect and manage the biological data produced through national R&D fund allocations and provide the collected data to researchers. To this end, the Korea Bioinformation Center (KOBIC) developed a new biological data repository, the Korea BioData Station (K-BDS), for sharing data from individual researchers and research programs to create a data-driven biological study environment. The K-BDS is dedicated to providing free open access to a suite of featured data resources in support of worldwide activities in both academia and industry.

• Korean Journal of Psychosomatic Medicine
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• v.29 no.1
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• pp.67-76
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• 2021

Objectives : The aim of this study was to compare activities of daily living (ADLs) according to degenerative changes in brain [i.e., medial temporal lobe atrophy (MTA), white matter hyperintensities] and to examine the association between neurocognitive functions and ADLs in Korean patients with dementia due to Alzheimer's disease (AD) and mild cognitive impairment (MCI). Methods : Participants were 111 elderly subjects diagnosed with AD or MCI in this cross-sectional study. MTA in brain MRI was rated with standardized visual rating scales (Scheltens scale) and the subjects were divided into two groups according to Scheltens scale. ADLs was evaluated with the Korean version of Blessed Dementia Scale-Activity of daily living (BDS-ADL). Neurocognitive function was evaluated with the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease assessment packet (CERAD-K). Independent t-test was performed to compare ADLs with the degree of MTA. Pearson correlation and hierarchical multiple regression analyses were performed to analyze the relationship between ADLs and neurocognitive functions. Results : The group with high severity of the MTA showed significantly higher BDS-ADL scores (p<0.05). The BDS-ADL score showed the strongest correlation with the word list recognition test among sub-items of the CERAD-K test (r=-0.568). Findings from the hierarchical multiple regression analysis revealed that the scores of MMSE-K and word list recognition test were factors that predict ADLs (F=44.611, p<0.001). Conclusions : ADLs of AD and MCI patients had significant association with MTA. Our study, which identifies factors correlated with ADLs can provide useful information in clinical settings. Further evaluation is needed to confirm the association between certain brain structures and ADLs.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.31-39
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• 2010

The goal of automatic velocity analysis is to extract accurate velocity from voluminous seismic data with efficiency. In this study, we developed an efficient automatic velocity analysis algorithm by using bootstrapped differential semblance (BDS) and Monte Carlo inversion. To estimate more accurate results from automatic velocity analysis, the algorithm we have developed uses BDS, which provides a higher velocity resolution than conventional semblance, as a coherency estimator. In addition, our proposed automatic velocity analysis module is performed with a conditional initial velocity determination step that leads to enhanced efficiency in running time of the module. A new optional root mean square (RMS) velocity constraint, which prevents picking false peaks, is used. The developed automatic velocity analysis module was tested on a synthetic dataset and a marine field dataset from the East Sea, Korea. The stacked sections made using velocity results from our algorithm showed coherent events and improved the quality of the normal moveout-correction result. Moreover, since our algorithm finds interval velocity ($\nu_{int}$) first with interval velocity constraints and then calculates a RMS velocity function from the interval velocity, we can estimate geologically reasonable interval velocities. Boundaries of interval velocities also match well with reflection events in the common midpoint stacked sections.

• Journal of Korea Water Resources Association
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• v.39 no.12 s.173
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• pp.997-1012
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• 2006

We have presented a nonparametric stochastic approach for the SOI(Southern Oscillation Index) series that used nonlinear methodology called Nonlinear AutoRegressive(NAR) based on conditional kernel density function and CAFPE(Corrected Asymptotic Final Prediction Error) lag selection. The fitted linear AR model represents heteroscedasticity, and besides, a BDS(Brock - Dechert - Sheinkman) statistics is rejected. Hence, we applied NAR model to the SOI series. We can identify the lags 1, 2 and 4 are appropriate one, and estimated conditional mean function. There is no autocorrelation of residuals in the Portmanteau Test. However, the null hypothesis of normality and no heteroscedasticity is rejected in the Jarque-Bera Test and ARCH-LM Test, respectively. Moreover, the lag selection for conditional standard deviation function with CAFPE provides lags 3, 8 and 9. As the results of conditional standard deviation analysis, all I.I.D assumptions of the residuals are accepted. Particularly, the BDS statistics is accepted at the 95% and 99% significance level. Finally, we split the SOI set into a sample for estimating themodel and a sample for out-of-sample prediction, that is, we conduct the one-step ahead forecasts for the last 97 values (15%). The NAR model shows a MSEP of 0.5464 that is 7% lower than those of the linear model. Hence, the relevance of the NAR model may be proved in these results, and the nonparametric NAR model is encouraging rather than a linear one to reflect the nonlinearity of SOI series.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1447-1455
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• 2009

Two novel avian $\beta$-defensins (AvBDs) isolated from duck liver were characterized and their homologies with other AvBDs were analyzed. They were shown to be duck AvBD9 and AvBD10. The mRNA expression of the two genes was analyzed in 17 different tissues from 1-28-day-old ducks. AvBD9 was differentially expressed in the tissues, with especially high levels of expression in liver, kidney, crop, and trachea, whereas AvBD10 was only expressed in the liver and kidney of ducks at all the ages investigated. We produced and purified GST-tagged recombinant AvBD9 and AvBDI0 by expressing the two genes in Escherichia coli. Both recombinant proteins exhibited antimicrobial activity against several bacterial strains. The results revealed that both recombinant proteins retained their antimicrobial activities against Staphylococcus aureus under a range of different temperatures ($-70^{\circ}C-100^{\circ}C$) and pH values (pH 3-12).

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.115-115
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• 2011

Biodiesel (BD) was made from animal-fats reacting with methanol and potassium hydroxide in the laboratory. The biodiesel made in the laboratory was sent to K-petro, the government agency, to inspect the quality of animal-fats biodiesel, of which generally the quality was acceptable for heating oil for agricultural hot air heater. Kinematic viscosity and calorific values of the biodiesels were measured. BD20(K), kerosene based biodiesel, showed 18cSt at $-20^{\circ}C$. It seems that BD100 can not be suitable for heating fuel under some temperature. As BD content increased calorific value decreased, up to 40,000J/g for 100% BD, while light oil calorific value was 45,567J/g, showing difference of 5,567J/g, about 12% difference. Several different fuels, BD20, BD50, BD100 and light oil, were prepared and tested for fuel combustion qualities for agricultural hot air heater and their combustion performances were compared and analyzed. Flame dimensions of biodiesels and light oil were almost same shape at the same combustion condition in the burner of the hot air heater. Generally $CO_2$ amounts of BDs are greater than light oil. But,the differences are so small that it is hard to tell there was significant difference existed between the BDs combustion and light oil.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.353-361
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• 2021

This paper presents the jamming effect on the L5 band of Global Navigation Satellite System (GNSS) by analyzing real data collected via measurement campaigns in Korea region. In fact, the L5 band is one of the dedicated bands for various satellite navigation systems such as Global Positioning System (GPS), Galileo, BeiDou (BDS), and Quasi Zenith Satellite System (QZSS). And this band is also allocated along with various systems used for aeronautical radio navigation systems (ARNS). Among ARNS, the Distance Measuring Equipment (DME) and the Tactical Air Navigation System (TACAN) are systems that transmit and receive strong power pulse signals, which may cause unintentional jamming in the reception of GNSS signals. In this paper, signals in the main lobe of GPS L5, Galileo E5a, BDS B2a, and QZSS L5 are collected in Korean region to confirm whether the jamming effect exists in the band. And then, the pulse blanking technique, which is a simple signal processing technique capable of responding to pulsed jamming, is applied to analyze the jamming effect of DME/TACAN on the L5 band.

• Korean Journal of Schizophrenia Research
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• v.21 no.2
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• pp.43-50
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• 2018

Objectives : Genome-wide association studies (GWASs) and meta-analyses indicate that single-nucleotide polymorphisms (SNPs) in the a-1C subunit of the L-type voltage-dependent calcium channel (CACNA1C) gene increase the risk for schizophrenia and bipolar disorders (BDs). We investigated the association between the genetic variants on CACNA1C and schizophrenia and/or BDs in the Korean population. Methods : A total of 582 patients with schizophrenia, 336 patients with BDs consisting of 179 bipolar I disorder (BD-I) and 157 bipolar II disorder (BD-II), and 502 healthy controls were recruited. Based on previous results from other populations, three SNPs (rs10848635, rs1006737, and rs4765905) were selected and genotype-wise association was evaluated using logistic regression analysis under additive, dominant and recessive genetic models. Results : rs10848635 showed a significant association with schizophrenia (p=0.010), the combined schizophrenia and BD group (p=0.018), and the combined schizophrenia and BD-I group (p=0.011). The best fit model was dominant model for all of these phenotypes. The association remained significant after correction for multiple testing in schizophrenia and the combined schizophrenia and BD-I group. Conclusion : We identified a possible role of CACNA1C in the common susceptibility of schizophrenia and BD-I. However no association trend was observed for BD-II. Further efforts are needed to identify a specific phenotype associated with this gene crossing the current diagnostic categories.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.3
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• pp.81-86
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• 2010

Since CORDIC (COordinate Rotation DIgital Computer) is able to carry out the phase operation, such as vector to phase conversion or rotation of vectors, with adders and shifters, it is well suited for the design of the frequency synchronization unit in OFDM receivers. It is not easy, however, to fully utilize the CORDIC in the OFDM demodulator because of the non-linear characteristics of the direction sequence (DS), which is the representation of the phase in CORDIC. In this paper a new representation method is proposed to linearize the direction sequence approximately. The maximum phase error of the linearized binary direction sequence (LBDS) is also discussed. For the purpose of designing the hardware, the architectures for the binary DS (BDS) to LBDS converter and the LBDS to BDS inverse converter are illustrated. Adopting LBDS, the overall frequency synchronization hardware for OFDM receivers can be implemented fully utilizing CORDIC and general arithmetic operators, such as adders and multipliers, for the phase estimation, loop filtering of the frequency offset, derotation for the frequency offset correction. An example of the design of 22 bit LBDS for the T-DMB demodulator is also presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.792-796
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• 2005

The methods of times series analysis have been recognized as important tools for assisting in solving problems related to the management of water resources. Especially, After more than 40 years the so-called Hurst effect remains an open problem in stochastic hydrology. Until now, its existence has been explained fly R/S analysis that roots in early work of the British hydrologist H.E. Hurst(1951). Today, the Hurst analysis is mostly used for the hydrological studies for memory and characteristics of time series and many methodologies have been developed for the analysis. So, there are many different techniques for the estimation of the Hurst exponent(H). However, the techniques can produce different characteristics for the persistence of a time series each other. We found that DFA is the most appropriate technique for the Hurst exponent estimation for both the shot term memory and long term memory. We analyze the SOI(Southern Oscillations Index) and 6 tree-ring series for USA sites by means of DFA and the BDS statistic is used for nonlinearity test of the series. From the results, we found that SOI series is nonlinear time series which has a long term memory of H=0.92. Contrary to earlier work of Rao(1999), all the tree- ring series are not random from our analysis. A certain tree ring series show a long term memory of H=0.97 and nonlinear property. Therefore, we can say that the SOI and tree-ring series may show long memory and nonlinearity.