• Progress in Medical Physics
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• v.14 no.4
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• pp.211-217
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• 2003

The Principal component analysis (PCA) is a well-known data analysis method that is useful in linear feature extraction and data compression. The PCA is a linear transformation that applies an orthogonal rotation to the original data, so as to maximize the retained variance. PCA is a classical technique for obtaining an optimal overall mapping of linearly dependent patterns of correlation between variables (e.g. neurons). PCA provides, in the mean-squared error sense, an optimal linear mapping of the signals which are spread across a group of variables. These signals are concentrated into the first few components, while the noise, i.e. variance which is uncorrelated across variables, is sequestered in the remaining components. PCA has been used extensively to resolve temporal patterns in neurophysiological recordings. Because the retinal signal is stochastic process, PCA can be used to identify the retinal spikes. With excised rabbit eye, retina was isolated. A piece of retina was attached with the ganglion cell side to the surface of the microelectrode array (MEA). The MEA consisted of glass plate with 60 substrate integrated and insulated golden connection lanes terminating in an 8${\times}$8 array (spacing 200 $\mu$m, electrode diameter 30 $\mu$m) in the center of the plate. The MEA 60 system was used for the recording of retinal ganglion cell activity. The action potentials of each channel were sorted by off­line analysis tool. Spikes were detected with a threshold criterion and sorted according to their principal component composition. The first (PC1) and second principal component values (PC2) were calculated using all the waveforms of the each channel and all n time points in the waveform, where several clusters could be separated clearly in two dimension. We verified that PCA-based waveform detection was effective as an initial approach for spike sorting method.

• Neonatal Medicine
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• v.17 no.2
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• pp.224-231
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• 2010

Purpose: Hospital readmissions have recently increased due to early hospital discharge and increased trends in breast-feeding. Neonatal hyperbilirubinemia can lead to fatal permanent neurological sequelae without appropriate management. Early detection and intervention are critical. We evaluated the clinical features, risk factors, and brain MRI findings of Korean newborns with idiopathic nonhemolytic hyperbilirubinemia to determine the optimal management policy. Methods: A retrospective review of the medical records of 79 newborns with idiopathic nonhemolytic hyperbilirubinemia was performed at the NICU of the Kyungpook National University Hospital from January 2006 to September 2009. All patients were 35 or more weeks of gestation, and their peak level of serum total bilirubin was more than 20 mg/dL. Results: The mean gestational age was $38^{+3}{\pm}1^{+4}$ weeks, and the mean age on admission was 8.8$\pm$4.0 days. The mean body weight (3,105$\pm$479 g) was decreased by 2.8$\pm$6.4 percent compared to the mean birth weight (3,174$\pm$406 g). There were no statistically significant differences for the peak serum bilirubin level or the duration and effects of phototherapy between the patients with and without risk factors, which included: breastfeeding, cephalohematoma, subdural hemorrhage, and/or ABO incompatibility. Patients were grouped according to change of body weight. Group I consisted of patients that gained weight compared to birth weight, and group II of patients that lost weight compared to birth weight. There were significant differences in the peak serum total bilirubin level between the two groups. Thirty nine patients had brain MRI evaluation; 21 patients had bilateral symmetric signal intensity increases in the globus pallidus compared to adjacent corticospinal tract and putamen on T1-weighted images. Conclusion: Bilirubin encephalopathy is preventable with early screening and proper management. Parents require instruction on feeding practices and follow-up to prevent complications from idiopathic nonhemolytic hyperbilirubinemia.

• Geophysics and Geophysical Exploration
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• v.8 no.2
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• pp.145-155
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• 2005

A two-dimensional (2-D) interpretation of MT data has been performed for the purpose of fracture detection for geothermal development. Remote stations have been operated in Kyushu, Japan (480 km apart) as well as in Korea (60 km and 165 km apart in 2002 and 2003 data set, respectively). Apparent resistivity and phase curves calculated by remote processing with the Japan remote data showed enough quality for 2-D inversion for the whole frequency range. Remote reference processing with Korea remote reference data also showed quite good continuity in apparent resistivity and phase curves except some noisy frequency bands; around the power frequency, 60 Hz, and around the dead band $10^{-1}Hz\;Hz\;\~1\;Hz$, where the natural EM signal is known to be very weak. Even though the subsurface showed severe three-dimensional (3-D) characteristics in the survey area so that 2-D inversion by itself could not give enough information for deep geological structures, the 2-D inversion for the 5 survey lines showed several common features. The conductive semi-consolidate mudstone layer is dipping from north to south (about 500 m depth on the south and 200 m on the north most part of the survey area). The boundary between the low (L-2) and high (H-2) resistivity anomalies can be thought as a major fault with strike $N15^{\circ}E$, passing through the sites 206, 112 and 414. The shallow (< 1 km) conductive anomalies (L-4) seem to be fracture zones having strike E-W (at site 105) and $N60^{\circ}W$ (at site 434). And there exists a conductive layer in the western and west-southern part of the survey area in the depth below $2\~3\;km$, for which further investigation is to be needed.

• Tuberculosis and Respiratory Diseases
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• v.53 no.6
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• pp.635-643
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• 2002

Background : The Aim of this study was to compare the recovery of mycobacteria from sputum samples of pulmonary tuberculosis patients using the MB/BacT rapid culture system(Organon Teknika, USA) with that obtained using Lowenstein-Jensen solid medium. Methods : The two culture systems were compared using sputum samples of 99 pulmonary tuberculosis patients. Culture media were incubated at $35-37^{\circ}C$ for six weeks in the MB/BacT system and for 12 weeks in Lowenstein-Jensen solid medium. Solid media were examined macroscopically once a week, and the MB/BacT system positive vials were unloaded from the machine as soon as possible after positive signal from the connected computer was detected Confirmation of growth for mycobacteria was done by Ziehl-Neelson stained smears. Isolates were identified to differentiate Mycobacterium tuberculosis from mycobacterium other than tuberculosis(MOTT) by phenotypic and molecular methods. Results : Of the sputum samples of the 99 patients, 58 samples were smear positive and 41 in negative smear. Mycobacteria were recovered from 67(67.7%) samples by using both culture systems. The yield with MB/BacT was higher than that with Lowenstein-Jensen [67(67.7%) vs. 52(52.5%), p<0.001]. Moreover, 15(15.2%) samples were positive only in the MB/BacT, whereas none of samples was positive only in Lowenstein-Jensen. In smear-positive and smear-negative samples, the recovery rate with MB/BacT was also higher than that with Lowenstein-Jensen [sputum-positive; 56/58(96.6%) vs. 46/58(79.3%), p=0.005, sputum-negative; 6/41(14.6%) vs. 5/41(12.2%), p<0.001]. The mean times to detection of Mycobacteria were 13.3 and 27.2 days with MB/BacT and Lowenstein-Jensen respectively(p<0.001). Conclusion : This results indicate that the the MB/BacT is more efficient and faster than Lowenstein-Jensen for the recovery of mycobacteria.

• Tuberculosis and Respiratory Diseases
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• v.44 no.2
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• pp.251-263
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• 1997

Background : The emergence of multidrug-resistant strains of Mycobacterium tuberculosis presents a significant challange to the treatment and control of tuberculosis, and there is an urgent need to understand the mechanisms by which strains acquire multidrug resistance. Recent advances in molecular methods for the detection of M. tuberculosis genetic targets have approached the sensitivity of culture. Furthermore the prospect of determining resistance in mycobacteria at the nucleic acid level particulary to first-line drugs like rifampin, isoniazid has provided a glimps of the next generation of sensitivity test for M. tuberculosis. Previous studies in RMP resistant M. tuberculosis have shown that mutation in $\beta$subunit of RNA polymerase is main mechanism of resistance. Method : In this study, rpoB gene for the $\beta$subunit of RNA polymerase from M. tuberculosis of 42 cultured samples (32 were RMP resistant and 10 were sensitive cases) were isolated and characterised the mutations. Direct sequencing data were compared with the results of INNO-LiPA Line Probe Assay (LiPA, Innogenetics, Belgium), commercial RMP resistance detecting kit using reverse hybridization method. Results : All of the RMP resistant samples were revealed the presence of mutation by LiPA. In 22 samples (68.8%) out of 32 RMP resistant cases, the mutation types were confirmed by the positive signal at one of 4 mutation bands in the strip. The most frequent type was R5 (S531L) which were 17 cases (77.3%). Results of direct sequencing were identified the exact characteristics of 8 mutations which were not confirmed by LiPA. S522W type point mutation and 9 base pair deletion at codon 513~515 were new identified mutations for the first time. Conclusion : Mutations in rpoB gene is the main mechanism of RMP resistance in M. tuberculosis and LiPA is a very useful diagnostic tool for the early diagnosis of RMP resistance in M. tuberculosis.

• Tuberculosis and Respiratory Diseases
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• v.47 no.6
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• pp.797-806
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• 1999

Background: About 20% of small cell lung cancer(SCLC) patients have bone marrow(EM) metastasis at the time of diagnosis and the remaining patients are also considered with micrometastasis. In an attempt to detect EM micrometastasis, we used cytokeratin(CK)-20 as a molecular marker, which is specific for epithelial cells. Method: A sensitive RT-PCR assay was used to compare CK-20 expression both in SCLC cell line H209 and normal leukocyte and to evaluate EM aspirates of 28 SCLC patients. Result: H209 cell line showed CK-20 expression but normal leukocyte did not, suggesting CK-20 expression is lung tissue-specific. Of 28 patients(11 limited disease, 17 extensive disease), only 2(1/11, 1/17) samples tested revealed positive signal for CK-20. Two patients with CK-20 expression had EM metastasis or multiple bone involvement during follow-up. Conclusion: Although circulating tumor cells were detected in EM of small portion of patients with bone metastasis, CK-20 doesn't seem to be a reliable marker for the detection of micrometastasis in SCLC. This study emphasizes that identification of more specific marker for micrometastsis is mandatory prior to clinical application.

• Journal of radiological science and technology
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• v.29 no.1
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• pp.1-6
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• 2006

Purpose: Renal stones are common and typically arise within the collecting system. The renal sinus are contains the collection system, the renal vessels, lymphatcs, fat, and fibrous tissue. Because of the compression of all the large echoes in signal processing, the echo from the renal stone generally cannot be distinguished from large echoes emanating from normal structures of the renal sinus. Use of ultrasonography has been difficult for detecting small renal stone without posterior shadowing and chemical composition of stone. The aim of study was measuring for posterior acoustic shadowing to a stone for various scan parameter and it examines a help in renal stone diagnosis. Material & Methods: The stone was place on sponge examined in a water bath with a 3.5MHz or 7.5MHz transducer(LOGIQ 400, USA). First, tested a variety of gain. Second, tested a variety of dynamic range. Third, tested a variety of focal zone. Fourth, measuring of the echo level for low and high frequency for depth. Results: 1) Average echo level was 98 for low total gain(10 dB) and was 142 for high total gain(40 dB). Posterior acoustic shadowing of renal stone was clear for low gain. 2) Average echo level was 129 for low dynamic range(42 dB) and was 101 for high dynamic range(72 dB). Posterior acoustic shadowing of renal stone was clear for high dynamic range. 3) When stone is in focal zone of transducer, definite posterior acoustic shadow is identified. 4) Stone was clear appeared for high frequency(7.5 MHz) than low frequency(3.5 MHz) and it is not distorted. Conclusion: The demonstration of an posterior acoustic shadow of renal stone dependents on several technical factors such as gain, dynamic range, focus, and frequency. This various factors are a help in renal stone diagnosis.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.317-324
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• 2015

GNSS was firstly proposed for application in weather forecasting in the mid-1980s. It has continued to demonstrate the practical uses in GNSS meteorology, and other relevant researches are currently being conducted. Precipitable Water Vapor (PWV), calculated based on the GNSS signal delays due to the troposphere of the Earth, represents the amount of the water vapor in the atmosphere, and it is therefore widely used in the analysis of various weather phenomena such as monitoring of weather conditions and climate change detection. In this study we calculated the PWV through the meteorological information from an Automatic Weather Station (AWS) as well as GNSS data processing of a Continuously Operating Reference Station (CORS) in order to analyze the heavy snowfall of the Ulsan area in early 2014. Song’s model was adopted for the weighted mean temperature model (T_m), which is the most important parameter in the calculation of PWV. The study period is a total of 56 days (February 2013 and 2014). The average PWV of February 2014 was determined to be 11.29 mm, which is 11.34% lower than that of the heavy snowfall period. The average PWV of February 2013 was determined to be 10.34 mm, which is 8.41% lower than that of not the heavy snowfall period. In addition, certain meteorological factors obtained from AWS were compared as well, resulting in a very low correlation of 0.29 with the saturated vapor pressure calculated using the empirical formula of Magnus. The behavioral pattern of PWV has a tendency to change depending on the precipitation type, specifically, snow or rain. It was identified that the PWV showed a sudden increase and a subsequent rapid drop about 6.5 hours before precipitation. It can be concluded that the pattern analysis of GNSS PWV is an effective method to analyze the precursor phenomenon of precipitation.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.3
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• pp.187-197
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• 2009

Objective: Phosphorylation and dephosphorylation of proteins are important in regulating cellular signaling pathways. Bead-based multiplex phosphorylation assay was conducted to detect the phosphorylation of seven proteins to maximize the information obtained from a single lysate of stage-specific mouse oocytes at a time. Methods: Cumulus-oocyte complexes (COCs) were cultured for 2 h, 8 h, and 16 h, respectively to address phosphorylation status of seven target proteins during oocyte maturation process. We analyzed the changes in phosphorylation at germinal vesicle (GV, 0 h), germinal vesicle breakdown (GVBD, 2 h), metaphase I (MI, 8 h), and metaphase II (MII, 16 h in vitro or in vivo) mouse oocytes by using Bio-Plex phosphoprotein assay system. We chose seven target proteins, namely, three mitogen-activated protein kinases (MAPKs), ERK1/2, JNK, and p38 MAPK, and other 4 well known signaling molecules, Akt, GSK-$3{\alpha}/{\beta}$, $I{\kappa}B{\alpha}$, and STAT3 to measure their phosphorylation status. Western blot analysis and kinase inhibitor treatment for ERK1/2, JNK, and Akt during in vitro maturation of oocytes were conducted for the confirmation. Results: Phosphorylation of ERK1/2, JNK, p38 MAPK and STAT3 was increased over 3 folds up to 20 folds, while phosphorylation of the other three signal molecules, Akt, GSK-$3{\alpha}/{\beta}$, and $I{\kapa}B{\alpha}$ was less than 3 folds. All of these results except for Akt were statistically significant (p<0.05). Conclusion: This is the first report on the new and valuable method measuring many phosphoproteins simultaneously in one minute sample such as oocyte lysates. All of the three MAPKs, ERK1/2, JNK, and p38 MAPK are involved in the process of mouse oocyte maturation. In addition, STAT3 might be important regulator of oocyte maturation, while Akt phosphorylation at Serine 473 may not be involved in the regulation of oocyte maturation.

• Journal of The Korean Astronomical Society
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• v.52 no.1
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• pp.11-21
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• 2019

Intensive Monitoring Survey of Nearby Galaxies (IMSNG) is a high cadence observation program monitoring nearby galaxies with high probabilities of hosting supernovae (SNe). IMSNG aims to constrain the SN explosion mechanism by inferring sizes of SN progenitor systems through the detection of the shock-heated emission that lasts less than a few days after the SN explosion. To catch the signal, IMSNG utilizes a network of 0.5-m to 1-m class telescopes around the world and monitors the images of 60 nearby galaxies at distances D < 50 Mpc to a cadence as short as a few hours. The target galaxies are bright in near-ultraviolet (NUV) with $M_{NUV}$ < -18.4 AB mag and have high probabilities of hosting SNe ($0.06SN\;yr^{-1}$ per galaxy). With this strategy, we expect to detect the early light curves of 3.4 SNe per year to a depth of R ~ 19.5 mag, enabling us to detect the shock-heated emission from a progenitor star with a radius as small as $0.1R_{\odot}$. The accumulated data will be also useful for studying faint features around the target galaxies and other science projects. So far, 18 SNe have occurred in our target fields (16 in IMSNG galaxies) over 5 years, confirming our SN rate estimate of $0.06SN\;yr^{-1}$ per galaxy.