• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.385-390
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• 2006

This paper examines the sampling and jitter specifications and considerations for Global Navigation Satellite Systems (GNSS) software receivers. Software radio (SWR) technologies are being used in the implementation of communication receivers in general and GNSS receivers in particular. With the advent of new GPS signals, and a range of new Galileo and GLONASS signals soon becoming available, GNSS is an application where SWR and software-defined radio (SDR) are likely to have an impact. The sampling process is critical for SWR receivers, where it occurs as close to the antenna as possible. One way to achieve this is by BandPass Sampling (BPS), which is an undersampling technique that exploits aliasing to perform downconversion. BPS enables removal of the IF stage in the radio receiver. The sampling frequency is a very important factor since it influences both receiver performance and implementation efficiency. However, the design of BPS can result in degradation of Signal-to-Noise Ratio (SNR) due to the out-of-band noise being aliased. Important to the specification of both the ADC and its clocking Phase- Locked Loop (PLL) is jitter. Contributing to the system jitter are the aperture jitter of the sample-and-hold switch at the input of ADC and the sampling-clock jitter. Aperture jitter effects have usually been modeled as additive noise, based on a sinusoidal input signal, and limits the achievable Signal-to-Noise Ratio (SNR). Jitter in the sampled signal has several sources: phase noise in the Voltage-Controlled Oscillator (VCO) within the sampling PLL, jitter introduced by variations in the period of the frequency divider used in the sampling PLL and cross-talk from the lock line running parallel to signal lines. Jitter in the sampling process directly acts to degrade the noise floor and selectivity of receiver. Choosing an appropriate VCO for a SWR system is not as simple as finding one with right oscillator frequency. Similarly, it is important to specify the right jitter performance for the ADC. In this paper, the allowable sampling frequencies are calculated and analyzed for the multiple frequency BPS software radio GNSS receivers. The SNR degradation due to jitter in a BPSK system is calculated and required jitter standard deviation allowable for each GNSS band of interest is evaluated. Furthermore, in this paper we have investigated the sources of jitter and a basic jitter budget is calculated that could assist in the design of multiple frequency SWR GNSS receivers. We examine different ADCs and PLLs available in the market and compare known performance with the calculated budget. The results obtained are therefore directly applicable to SWR GNSS receiver design.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.6
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• pp.982-996
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• 2010

This study classified the body shapes of Korean obese women and investigated the differences of each body shape, using 2004 Size Korea data. For selecting the obesity sample, 7 obesity judgment indices were chosen through previous clothing-related studies. A total of 636 females defined as "obese" by 5 out of 7 indices were selected as subjects and 54 body measurements and obesity judgment indices were used in this study. Firstly, mean, standard deviation, minimum, and maximum values of each measurement and item were obtained from the descriptive analysis of 53 measurements. According to the descriptive analysis, all measurements and obesity judgment indices of the subjects demonstrated a serious obesity level shown by BMI 27.11, R$\ddot{o}$hrer index 1.76, Vervaeck index 104.77, Relative weight 133.00, WHR 0.90, and waist circumference 86.71cm. In addition, the measurements and indices showed considerable differences between minimum and maximum values. Significant differences were identified in all measurements and items at a significant level, p=.001. Each distribution of body types according to age, stature, bust, and waist circumference groups was provided in this study. Secondly, factor analyses were conducted using 38 measurement items to extract the body characteristics of obese women. Factor 1 was "circumference measurements & obesity judgment indices," Factor 2 was "heights & arm-related lengths," and Factor 3 was "size and ratio of waist circumference & hip circumference." Factor 4 was "lengths in upper body," Factor 5 was "back width in upper body," Factor 6 was "side neck point to bust & bust circumference," Factor 7 was "length in lower body & arm circumferences" and Factor 8 was "neck base circumference & front width in upper body." These 8 factors explained 76.54% of the total variance. Finally, 5 body types were selected in the cluster analysis. Type 1 (with big back widths & arm circumferences) was 15.5% of the entire subjects, Type 2 (the shortest and fattest, with big upper body) was 18.8%, Type 3 (with big breast) was 27.8%, Type 4 (the tallest and longest in arm lengths, with the smallest arm circumferences and lengths in torso) was 22.5%, and Type 5 (with big hips compared to waist circumferences, smaller height and upper body) was 15.5%. Fundamental differences were identified in all measurements and items at the significant level of p=.001. In addition, each distribution of body type according to age, height, bust, and waist circumference groups was provided in this study.

• Journal of Biomedical Engineering Research
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• v.40 no.6
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• pp.260-267
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• 2019

In the present study, we aimed to demonstrate that MV2000-MT(SU:M2)^® (MV, MEK-ICS, Paju, Korea), a domestic ventilator, is not inferior in terms of usability, safety, and medical staff satisfaction as compared to Hamilton G5 (G5, Hamilton Medical AG, Rhäzuns, Switzerland). A total of 39 patients who applied MV (group M) or G5 (group H) were included in the study sample. Usability was evaluated by the following factors: the number of alarm errors, replacement requirement of breathing circuit, replacement requirement of a right-angle connector, and ease of ventilator weaning. For safety evaluation, the number of ventilator replacements due to malfunction of the ventilator was evaluated. Items for medical staff satisfaction survey were as follows: the number of MV and G5 uses, hardware, and software assessment. In the usability evaluation, the replacement requirement of the right-angle connector was lower in Group M than in Group H (mean ± standard deviation, Group M: 7.39 ± 6.72, Group H: 14.19 ± 10.24, p = 0.021); however, the evaluations of other parts were not significantly different between the two groups. The number of ventilator replacements due to a malfunction of the ventilator did not differ between two groups. The number of MV and G5 uses was 3.0 [3.0-4.0] and 10.0 [5.0-10.0] (median [interquartile range], p < 0.001). Overall, the mean medical staff satisfaction score of Hamilton G5 was higher than that of MV2000-MT(SU:M2)^®. The usability of MV is comparable to that of G5. However, medical staff satisfaction with Hamilton G5 was higher than that with MV2000-MT(SU:M2)^®, and this difference could be due to the difference in the number of uses. In order to improve the penetration rate of the domestic mechanical ventilator, it is necessary to find ways to increase familiarity of medical staff with domestic mechanical ventilators.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4429-4436
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• 2013

Measurements of CNR(Contrast to Noise Ratio) and SNR(Signal to Noise Ratio) of T-spine breathing technique (TBT) using spontaneous breathing and T-spine exhalation technique (TET) with full exhalation were carried out, and with which the more appropriate method was suggested. Both TBT and TET were examined in a sample of fifty-three patients who visit to our hospital for spinal disease from June 2012 to November 2012. All images were evaluated with CNR measured from the differences between the mean pixels and contrast density as setting ROI of spinous process, pedicle, vertebral body, intervertebral foramen, and intervertebral disk using Image J. SNR was measured with the mean pixels and the standard deviation as setting ROI of vertebral body using Image J. In CNR comparison and SNR comparison of TET and TBT, TBT was indicated as excellent in ROI of pedicle, vertebral body, intervertebral foramen and intervertebral disk, and statistical analysis were significant(p<.01). As TBT indicated excellent images compared to the existing T-spine lateral radiography, T-spine lateral radiography would be reestablished and significant as applying to various medical institutions.

• Journal of the Korean Society of School Health
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• v.4 no.1
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• pp.100-115
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• 1991

The purpose of this study is to provide the necessary data for the effective performance of school nurse's work by comparing with the recognition and expectation on school nurse's work by the students and their teachers in school settings. The sample of this study was consisted of the 441 students and 535 teachers in Suwon. The data were collected by means of a structured questionnaire from 24th, Sept, to 29th, Sept. 1990. The collected data were analyzed utilizing SAS/PC program for percentage, frequency, mean, standard deviation and chisquare test. The major findings of this study were as follows: 1. The result of analysis in recognition on school nurse's work. There is no statistically significant difference 'depending on teachers' school level, sex, age and career with school nurse(P>0.05). The students show significant difference on their school level and sex(P>0.05). Also, in the areas of school nurse's work, school clinic management has the highest recognition and school environment management has the lowest recognition. 2. The result of analysis in expectation on school nurse's work. There is statistically significant difference depending on teachers' and students' school level: the order of expectation is elementary, middle, and high school(P<0.05). In the result of comparison with students' and teachers' expectation in the same school level, there is significant difference only in elementary school(P<0.05). However, there is no statistically significant difference depending on teachers' sex, age, career with school nurse and students' sex(P>0.05). Also, in the areas of school nurse's work, school clinic management has the highest expectation and school environment management has the lowest expectation. Synthesizing the result of the study, we can have the conclusion like following. First, students' recognition on school nurse's work is lower than teachers' because most of school nurse's work is performed through their homeroom teachers or other teachers. That can be the limitation for students to recognize school nurse's work. So, there must be a chance of regular meeting between school nurse and students to perform school nurse's work effectively. For this. we must change our educational system and make school nurse charge regular lesson. Second, in each area of school nurse's work, both students' and teachers' recognition and expectation about the area of school environment management has much lower score than the other areas. This indirectly shows the school nurse don't do the work of the area actively. So, school nurses must make an effort to do the work of the area actively. And we must enforce the education of this area in education for new school nurses or re-education for school nurses.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.16-20
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• 2014

The prevalence of Bacillus cereus was determined in salad and Kimbab obtained from commercial retailers. Among the 100 salad samples analyzed, 54 samples were negative for B. cereus, whereas the bacterial count was < 10 colony forming units (CFU)/g in 8 samples, < 100 CFU/g in 25 samples, < 1,000 CFU/g in 11 samples, and > 1,000 CFU/g in 2 samples. The mean (standard deviation) was 1.18 log CFU/g (${\pm}0.71$ log CFU/g). In Kimbab, B. cereus was isolated from 20 samples; the mean bacterial count was 1.01 log CFU/g (${\pm}0.71$ log CFU/g). On the basis of the monitoring data, a statistical sampling plan was determined with the NEW sampleplan program (ICMSF), which was used as an analytical tool. To identify the most suitable sampling plan, the microbial limits (m, M) and the maximum allowable number of sample units yielding unsatisfactory test results (c) were varied, but the number of samples units, n = 5, was fixed. Sampling plans showing an acceptable probability (Pa) over 0.95 were considered suitable. Two plans (A and B) were finally suggested. Parameters for plan A are n = 5, c = 0, m = 1,000, and M = 10,000 and for plan B are n = 5, c = 2, m = 100, and M = 1,000. Interestingly, the latter plan was identical to the microbial sampling plan used in New Zealand. Thus, it was concluded that the suggested plan can be used as a sampling plan that is in line with international standards.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.50-58
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• 2000

Burning rate of the matrix propellant($r_{sb}$) and burning rate along the metal wire($r_w$) were measured and analyzed for the HTPB/AP/Al propellant embedded with Ag wire($\phi$0.15mm) according to weight % of RDX(0~20%). Variation of burning rate increment ratio($r_w$/$r_{sb}$) and pressure exponent(n) was studied for the nitramine propellant having 10% RDX embedded with three kinds of metal(Ag, Cu, and Ni-Cr) of which diameter range is between 0.1~0.6mm. Maximum burning rate increment ratio of the nitramine propellant embedded with Ag wire($\phi$0.1mm) was 5.94 at $20^{\cire}C$, 1000 psia, 16.4% faster than that of HTPB/AP propellant, it is because that autoignition temperature of the nitramine propellant was higher than that of HTPB/AP propellant. Standard deviation of absolute ($r_{wc}$/$r_{we}$)/$r_{we}$ calculated by using new empiracal equation composed of four dimensionless groups, is 6.11% less than that calculated by using original empirical equation composed of three dimensionless group. The new empiracal equation is derived from Buckingham pi theorem using the parameters such as thermal diffusivity, melting temperature. wire diameter, propellant sample diameter, frame temperature, autoignition temperature and matrix burning rate which influence on $r_w$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.227-236
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• 2018

This study was conducted to define hippocampal volume differences between a stress-laid group and normal individual group via meta-analysis. This investigation included studies that contained hippocampal volume measurements in association with stress from 1990 to 2016. Magnetic resonance imaging (MRI) measurements of hippocampal volumes were used to determine the mean size, standard deviation and sample size. The pooled effect size was measured by the standardized mean difference (SMD) with a 95% confidence interval. This meta-analysis included 13 studies comprising 374 stress subjects and 439 normal subjects. Eight studies targeted war-related veterans and holocaust survivors, while five targeted personal trauma associated with childhood abuse, rape, accident or financial hardship. The overall mean effect size (Hedges' g) was -0.70 (-1.04; -0.37). Overall, the SMD value was -0.70, with a moderate effect size, but high heterogeneity. Depending on the characteristics of the stressor, studies were divided by subgroups of war-related veterans and subjects with personal trauma and then analyzed again. In the war-related subgroup, the Hedges' g was -0.47 (-0.78; -0.16), while in the personal stressor-related subgroup it was -0.91 (-1.57; -0.26). These results indicate that there was a significant negative correlation between psychological stress and hippocampal volume.

• Journal of Korea Society of Waste Management
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• v.35 no.7
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• pp.616-626
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• 2018

The quality standards of solid refuse fuel (SRF) define the values for 12 physico-chemical properties, including moisture, lower heating value, and metal compounds, according to Article 20 of the Enforcement Rules of the Act on Resource Saving and Recycling Promotion. These parameters are evaluated via various SRF Quality Test Methods, but problems related to the heavy metal content have been observed in the microwave acid digestion method. Therefore, these methods and their applicability need improvement. In this study, the appropriate testing conditions were derived by varying the parameters of microwave acid digestion, such as microwave power and pre-treatment time. The pre-treatment of SRF as a function of the microwave power revealed an incomplete decomposition of the sample at 600 W, and the heavy metal content analysis was difficult to perform under 9 mL of nitric acid and 3 mL of hydrochloric acid. The experiments with the reference materials under nitric acid at 600 W lasted 30 minutes, and 1,000 W for 20 or 30 minutes were considered optimal conditions. The results confirmed that a mixture of SRF and an acid would take about 20 minutes to reach $180^{\circ}C$, requiring at least 30 minutes of pre-treatment. The accuracy was within 30% of the standard deviation, with a precision of 70 ~ 130% of the heavy metal recovery rate. By applying these conditions to SRF, the results for each condition were not significantly different and the heavy metal standards for As, Pb, Cd, and Cr were satisfied.

• The Journal of Korean Academy of Sensory Integration
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• v.19 no.3
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• pp.22-31
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• 2021

Purpose : This study aimed to conduct a translation, backtranslation, and content validity test of the Sensory Processing Measure (SPM) for Korean children. Methods : The translation and content validation process involved direct and backward translation; a test of equivalence between the two versions (the original SPM and the Korean version SPM; K-SPM) was performed using content-related evidence collected by a group of experts and a group of parents. Data analysis was carried out using Excel Content validity indices (CVI), mean, and standard deviation were used for the analysis of content validity. Results : The result of the comparison between the original SPM and K-SPM in the group of experts was 3.54 ± .74, the S-CVI/Avg for semanticity was .92, and the S-CVI/Avg for structure was .86. The results for the mean of the understanding test and the S-CVI/Avg were 3.48 ± .63 and .94, respectively. Conclusion : K-SPM will considerately be used as an assessment to identify sensory processing, praxis, and social participation issues for children in Korea. Further studies are suggested to increase the age range and the sample size for a more comprehensive applicability of the K-SPM to Korean children.