• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.113-118
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• 2015

Mobile wireless networks have received a lot of attention as a future wireless network due to its rapid deployment without communication infrastructure. In these networks communication path between two arbitrary nodes break down because some links in the path are beyond transmission range($r_0$) due to the mobility of the nodes. The set of total path break down time(${\bigcup}T_i$), which is the union of path break down time of every node pair, can be a good measure of the connectivity of the dynamic mobile wireless network. In this paper we show that the distribution of the total path break down time can be approximated as a exponential probability density function and confirms it through experimental data. Statistical knowledge of break down time enables quantitative prediction of delay, packet loss between two nodes, thus provides confidence in the simulation results of mobile wireless networks.

• Journal of Korean Public Health Nursing
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• v.27 no.1
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• pp.113-128
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• 2013

Purpose: The purpose of this study was to investigate the degree of suicidal risk, meaning in life, and life respect in various ages of patients and identify factors influencing their life respect. Method: The participants were 229 patients in a public hospital who completed questionnaires. Data were analyzed using descriptive statistics, t-test, Fisher's exact test, ANOVA with Duncan post hoc test, and multiple regression. Results: There was a negative correlation between the meaning of life and life respect in the old age group (r=-.23, p=.02) and all subjects (r=-.14, p=.01) after controlling for age. Factors significantly influencing life respect were gender (${\beta}$=0.11, p=.050) and educational status (${\beta}$=-0.17, p=.022), and the multiple regression model explained 16.7% of the variance in all subjects (p<.001). In the early adulthood group, factors significantly influencing the life respect were gender (${\beta}$=0.18, p<.001) and suicidal thoughts (${\beta}$=0.21, p=.028), and the multiple regression model explained 6.8% of variance in all subjects (p=.001). Conclusion: The results of this study suggest that suicidal prevention and educational programs for increasing an appreciation of life should consider subject's characteristics, such as gender and educational status.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.94-99
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• 2005

Sixty four bacterial colonies which were able to oxidize the manganese were isolated from soil samples in Mokcheon and Ochang area. Among them, one bacterial strain was selected for this study based on its higher manganese oxidation, and this selected bacterial strain was identified as Aeromonas sp. MN44 through physiological-biochemical test and analysis of its 16s rRNA sequence. Aeromonas sp. MN44 was able to utilize lactose but did not utilize various carbohydrates as a sole carbon source. Aeromonas sp. MN44 showed a very sensitive to antibiotics such as kanamycin, chloramphenicol, ampicillin, tetracycline and spectinomycin, and heavy metal such as cadmium. But this strain showed a high resistance up to mg/ml unit to heavy metals such as lithium and manganese. Optimal manganese oxidation condition of Aeromonas sp. MN44 was pH 7.4 and manganese oxidation activity was inhibited by proteinase K and boiling treatment. So, we concluded that this factor was protein. The manganese oxidizing factor produced by Aeromonas sp. MN44 was partial purified by ammonium sulfate precipitation, DEAE-Toyopearl 650M ion exchange chromatography and Sephadex gel filtration chromatography. Its molecular mass was about 113 kDa.

• Journal of Ginseng Research
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• v.34 no.2
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• pp.113-121
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• 2010

The fresh ginseng roots were extracted with aqueous methanol, and the obtained extracts were partitioned using ethyl acetate, n-butanol, and water, successively. The repeated silica gel and octadecyl silica gel column chromatogaraphy for n-butanol fraction afforded four diol ginseng saponins, ginsenosides $Rb_1$, $Rb_2$, $R_c$, and Rd. The physicochemical, spectroscopic, and chromatographic characteristics of these ginsenosides were measured and compared with those reported in the literature. Some of the peak assignments in previously published $^1H$- and $^{13}C$-nuclear magnetic resonance (NMR) spectra were inaccurate. This study employed two-dimensional NMR experiments, including $^1H-^1H$ correlation spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity, to determine exact peak assignments.

• Journal of Life Science
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• v.19 no.12
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• pp.1698-1704
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• 2009

Gemcitabine is an anticancer drug used to treat a variety of solid tumors. The drug is rapidly inactivated by cytidine deaminase in plasma and its hydrophilicity restricts the extent of quantification that is possible using reversed-phase liquid chromatography. In this paper, we report a rapid and precise method to analyze velocity and peak efficiency using ultra-performance liquid chromatography (UPLC) with a reversed-phase column. The retention periods of gemcitabine and 2'-deoxycytidine at 283 nm were 3.2 and 2.1 min, respectively. The assay provided highly linear results in the range of $0.1{\sim}20{\mu}g/ml$ ($r^2$ > 0.999). The coefficients of variation of the intra-day and inter-day assays were less than 10.0%. We observed that the estimated average concentrations of the intra-day and inter-day assays ranged from 97.3 to 113.5% to verify the accuracy. These results suggest that this new reversed-phase UPLC method is a rapid and reliable way of determining gemcitabine levels.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.113.2-113.2
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• 2011

We observed a low-mass pre-main sequence star, HBC722 (also known as $LkH{\alpha}$ 188 G4), with Camera for QUasars in EArly uNiverse (CQUEAN) attached to 2.1 Otto Struve telescope at McDonald Observatory, USA. HBC722 is a new FU orionis-type object in the direction of NGC7000/IC5070, which produced large amplitude optical outbursts (${\delta}V$=4.7 mag over one year) for a few months and reached the peak in 2010 September. We carried out the photometric observation in SDSS r,i, and z band in 2011 April, July and August to monitor the long term decrease of its brightness. We also made continuous observation in r-band for half night in July, and whole two nights in August to investigate short term variability which could be related to the rotation of the central star or the inner circumstellar disk. In this poster, we present a preliminary result of the photometric observation for HBC722.

• The Journal of the Korea Contents Association
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• v.19 no.1
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• pp.96-107
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• 2019

The purpose of this study is to empirically analyze the causal relationship between mother's parenting stress and family resilience in children with ADHD. Methods: The results of the survey were hierarchically regressed. The participants were 113 mothers of children with ADHD and who lived in resident in Busan and Gyeongsangnam-do Province. The main contents of the study were as follows: First, there was a significant difference in family resilience level according to mother's educational background and family monthly income. Second, the higher the parenting stress, the lower the family resilience ($r=-.622^{**}$), and all three types of coping methods showed the highest correlation with family resilience. Third, the variables affecting family resilience were in the order of problem - centered coping (${\beta}=.376$), parenting stress (${\beta}=-.338$) and mother's academic ability (${\beta}=.239$). Based on this study, this study suggested a social welfare practice plan to reduce the parenting stress and increase the resilience of the mother of the child with ADHD.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.391-397
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• 2019

In 2016, the number of suicides per 100,000 population in Korea was 24.6, which is the highest record of OECD countries. The number of suicide deaths increased with age. Elderly people have a higher risk of completed suicide than any other age group. The purpose of this study was to analyze the panel data of the Korean Welfare Panel Study to identify the factors affecting the suicide of Korean older people. This study analyzed the data of the 11th Korean Welfare Panel Study, which was constructed in 2016. The mean age of the participants was 75.55 years and 37% were man and 63% were women. The annual prevalence of suicidal ideation was 3.4%. The effects of depression(Exp(B)=1.113) and subjective health status((Exp(B)=.767) on suicidal ideation was statistically significant by stepwise logistic regression analysis(Nagelkerke $R^2=.248$). Therefore, for the effective application of suicide prevention program for the older people, assessment of subjective health status and depression screening should be preceded.

• Journal of the Korean Dietetic Association
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• v.27 no.2
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• pp.113-123
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• 2021

This study aimed to examine the association between sleep duration, stress levels, and dietary behavior in adolescents. A survey was conducted on 453 students (227 male, 226 female) in high schools in the Chungbuk area. The participants were divided into groups based on daily sleep duration: group I (<5 hrs/d), group II (≥5 hrs/d and <6 hrs/d), group III (≥6 hrs/d and <7 hrs/d), and group IV (≥7 hrs/d). To measure the stress levels of participants, the survey had questions covering a variety of areas, including school life, family life, social relationships, and personal evaluation. To assess the dietary behaviors of participants, the survey included questions encompassing the Nutrition Quotient for Korean adolescents (NQ-A). Among female students, the sleep duration group IV had significantly lower total stress (P=0.022) and significantly lower stress in the personal evaluation area than the sleep duration group I (P=0.004). In the analysis of NQ-A, among female students, the sleep duration group IV showed significantly higher scores in balance (P=0.004), diversity (P=0.016), and total NQ-A score area (P=0.007) compared to other groups. There was a significant negative correlation between sleep duration and stress scores in total students (r=-0.24, P<0.001), while a significant positive correlation was seen between sleep duration and NQ-A scores in female students (r=0.16, P<0.05). To sum up, the longer the sleep duration, the lower the degree of stress, and the quality of meals which can be said to be a significant finding for high school students.

• Analytical Science and Technology
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• v.19 no.6
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• pp.519-528
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• 2006

An analytical method for the determination of thyroid hormones in urine samples has been studied by using solid-phase extraction and high-performance liquid chromatography/diode array detector/electro-spray mass spectrometry. Seven thyroid hormones were successfully separated by gradient elution on the reverse phase Hypersil ODS column (4.6 mm I.D., 100 mm length, particle size $5{\mu}m$) with ammonium formate buffer and acetonitrile, and UV spectra and mass fragment could be confirmed. The extraction recoveries of thyroid hormones in the urine samples (pH 3) were in the range of 89.0-113.1% with solid-phase extraction by C18, followed by elution with 4 ml of methanol/ammonium hydroxide (9 : 1). The calibration curves showed good linearity with the correlation coefficients ($r^2$) varying from 0.992 to 0.998 and the detection limits of all analytes were obtained in the range of 2-4 ng/ml (3.8-13.0 pmol/ml).