• Communications for Statistical Applications and Methods
• /
• v.2 no.1
• /
• pp.145-154
• /
• 1995

Empirical Bayes approach is applied to estimation of the binomial parameter when there is a cost for observations. Both the sample size and the decision rule for estimating the parameter are determined stochastically by the data, making the result more useful in applications. Our empirical Bayes problems with non-iid components are compared to the usual empirical Bayes problems with iid components. The asymptotic optimal procedure with a computer simulation is given.

• Journal of the Korean Data and Information Science Society
• /
• v.6 no.1
• /
• pp.31-37
• /
• 1995

We consider density estimates of the usual type generated by a kernel function. By using the limit theorems for the maximum of normalized deviation of the estimate from its expected value, we propose to use data dependent bandwidth in the tests of goodness of fit based on these statistics. Also a small sample Monte Carlo simulation is conducted and proposed method is compared with Kolmogorov-Smirnov test.

• 한국해양학회지
• /
• v.24 no.4
• /
• pp.165-171
• /
• 1989

To examine the sample variability of zooplankton, samples were collected at two stations in the nearshore off Anhung (Chungnam, Korea), using a NORPAC net (76 Cm diameter, 0.333 mm mesh size) for two days, April 5 and 6, 1989. The net was towed vertically to eliminate the source of variation due to vertical migration. During the period of 6 hours, triplicate sampling was done every one or two hour at each station. Species composition and abundances at two stations were not so different, but the abundances at each station varied greatly with respect to sampling time. Greater abundance at one sampling time ranged 2.3-8.7 times of smaller abundance at another sampling time. At the level of ${\alpha}=0.05$, however, mean abundances of different sampling time did not differ significantly from each other due to the large variance. It was believed that the large variance was caused by the time dependent effect of patchiness of which parameters were varied with time because of sea water movement. From the variation within the triplicate samples, it was considered that the abundance data obtained from single tow were not significantly different from the data in the range of 50-200% of those from single tow. From these results, the necessity for the replicate and time dependent sampling was indicated. In the nearshore like the sampling site of this study, it seemed to be better to reduce the number of stations for the replicate and time dependent sampling though the proper sampling scheme was to be decided based on the goal of the study.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.3
• /
• pp.338-345
• /
• 2003

Response surface methodology was used for monitoring changes in phenolic compounds properties of Rubi Fructus extract depening on extraction conditons. The three independent variables (extraction conditions) were ratio of solvent to sample content (5, 10, 15 mL/g), ethanol concentration (20, 40, 60%) and extraction time (2, 4, 6 hr). It was anticipated that each of the five dependent Y variables (responses) would be affected by the three independent variables. The dependent responses were total yield, total phenolics content, electron donating ability, antioxidant ability and nitrite-scavenging ability (pH 1.2, 3.0, 4.2, 6.0). Total yield, total phenolics content, electron donating ability and antioxidant ability were affected by ratio of solvent to sample content. Nitrite- scavenging ability at pH 1.2 and pH 6.0 was affected by ethanol concentration, while it was affected by extraction time at pH 3.0 and pH 4.2. The optimum extraction conditions for total yield were 14.16 mL/g ratio of solvent to sample content,39.08% ethanol concentration and 2.99 hr extraction time. The maximum total phenolics content of extracts were shown at 14.06 mL/g ratio of solvent to sample content, 35.51% ethanol concentration and 3.15 hr extraction time.

• Journal of the Korean Ceramic Society
• /
• v.49 no.5
• /
• pp.432-437
• /
• 2012

Electrical properties of the laminated SMD-type PTC thermistor for microcircuit protection were investigated as a function of calcination and sintering temperature. $BaTiO_3$ with $Y_2O_3$ and $MnO_2$ were calcined at 1000 to $1150^{\circ}C$ for 2h and the laminated SMD-type PTC thermistor was sintered at 1350 to $1400^{\circ}C$ for 2h in a reduced atmosphere (1% $H_2/N_2$). Sintered density of the sample was dependent on the calcination and sintering temperature. Electrical properties of the sintered samples were strongly dependent on the densities of samples. For the samples with density below 4.6 g/$cm^3$, the insulator characteristics were observed, while PTC jump characteristics (R150/R30) were disappeared for the sample with density above 5.05 g/$m^3$. Optimal PTC characteristics were obtained for the sintered samples with density of 5.05 g/$m^3$. The laminated SMD-type PTC thermistor prepared by calcination at $1100^{\circ}C$ for 2h and sintering at $1270^{\circ}C$ for 2h showed the room temperature resistivity of $11{\Omega}{\cdot}cm$ and PTC jump characteristics of $10^2$ order.

• The Journal of the Korea Contents Association
• /
• v.20 no.10
• /
• pp.436-448
• /
• 2020

This study aims to determine the effect of e-cigarettes on oral health by investigating the association between the use of different tobacco products and oral health among Korean adults aged 19 years and older. Data from the 2017 Community Health Survey were used for the study. Respondents were divided into four groups: non-smokers, cigarette smokers, e-cigarette smokers, and users of both products. A sample of 228,357 respondents was selected for analysis. Twenty-four questionnaires with missing values (non-response or refusal) were excluded from the sample. A regression analysis was performed with oral as the dependent variable. A multivariate regression analysis showed a significant difference between cigarette smokers and users of both products when compared to the non-smokers. However, e-cigarette users showed a significant when the variables were correlated with age and gender. There was no significant difference in other dependent variables in a multivariate regression analysis. The results of the study indicated no association between e-cigarette use and oral health. More research is needed on factors such as amount and intensity of e-cigarette use.

• Korean Journal of Materials Research
• /
• v.25 no.12
• /
• pp.703-707
• /
• 2015

In this study, we investigated the effect of annealing conditions on the ferromagnetic resonance(FMR) of yttrium iron garnet ($Y_3Fe_5O_{12}$, YIG) thin film prepared on gadolinium gallium garnet ($Gd_3Ga_5O_{12}$, GGG) substrate. The YIG thin films were grown by rf magnetron sputtering at room temperature and were annealed at various temperatures from 700 to $1000^{\circ}C$. FMR characteristics of the YIG thin films were investigated with a coplanar waveguide FMR measurement system in a frequency range from 5 to 20 GHz. X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to characterize the phase formation, crystal structure and composition of the YIG thin films. Field dependent magnetization curves at room temperature were obtained by using a vibrating sample magnetometer(VSM). The FMR measurements revealed that the resonance magnetic field was highly dependent on the annealing condition: the lowest FMR linewidth can be observed for the $800^{\circ}C$ annealed sample, which agrees with the VSM results. We also found that the Fe and O composition changes during the annealing process play important roles in the observed magnetic properties.

• Journal of the Korean Vacuum Society
• /
• v.15 no.4
• /
• pp.387-394
• /
• 2006

In this study, the effect of using a neutral beam formed by low-angle forward reflection of a reactive ion beam on aspect-ratio-dependent etching (ARDE) has been investigated. When a SF6 Inductively Coupled Plasma and $SF_6$ ion beam etching are used to etch poly-Si, ARDE is observed and the etching of poly-Si on $SiO_2$ shows a higher ARDE effect than the etching of poly-Si on Si. However, by using neutral beam etching with neutral beam directionality higher than 70 %, ARDE during poly-Si etching by $SF_6$ can be effectively removed, regardless of the sample conditions. The mechanism for the removal of ARDE via a directional neutral beam has been demonstrated through a computer simulation of different nanoscale features by using the two-dimensional XOOPIC code and the TRIM code.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.37 no.5
• /
• pp.64-75
• /
• 2000

This paper proposes a color sample selection method that produces a uniform distribution in the display gamut plus a color reproduction method for using a uniform color sample In contrast to the conventional method, the proposed uniform color samples are selected m CIELAB, a device-independent color space, instead of RGB (red, green, and yellow) or CMY (cyan, magenta, and yellow) space, device-dependent color spaces To evaluate the performance of the proposed color samples, they were applied to color space conversion using both a regression model and neural network As a result, in the case of a color sample of the same size, the color space conversion method using the proposed samples showed a lower color difference for color conversions using either neural or regression.

• The Journal of Internal Korean Medicine
• /
• v.21 no.3
• /
• pp.425-432
• /
• 2000

Objective : It is well known that Gagamsojeokbackchool-san show antitumor effects and its activities are result from enhancement of immune function, we investigated the antitumor effects of Sambonggangyongbaneo-tang and its mechanism. Methods : We measured change of body weight, weight of immune organs (Spleen, Thymus), Liver, Kidney, tumor weight, cytotoxicity for investigation of antitumor effects of Sambonggangyongbaneo-tang. Results : 1. The body weight of mouse has no significant difference between control and sample groups. 2. The weights of immune organs (Spleen and Thymus) decreased significantly in sample groups. The weights of Liver and Kidney have no significant difference. 3. The tumor weights in mouse decreased significantly in sample groups and showed dose-dependent effect. 4. Cell viability of Sarcoma 180 has no significant difference in sample groups. 5. HeLa cell viability has no significant difference in low concentration, but it decreased significantly in high concentration. Conclusions : According to the above results, it could be suggested that Sambonggangyongbaneo-tang has prominant antitumor effects and cytotoxicity.