• Tuberculosis and Respiratory Diseases
• /
• v.62 no.5
• /
• pp.365-373
• /
• 2007

Background: Smoking is one of the most important leading causes of morbidity and mortality. Smoking habit is recognized as nicotine dependence, which consists of physical and psychosocial dependence. To evaluate social nicotine dependence, the Kano Test for Social Nicotine Dependence (KTSND) working group developed a new questionnaire, which consists of 10 questions with a total score of 30 in Japan. We examined the social nicotine dependence among healthy adults using the new KTSND questionnaire and evaluated validity of the KTSND questionnaire in Korea. Method: We applied Korean KTSND questionnaire version 2 to employees of hospital, university students and people for medical examination and promotion test. Complete data obtained from the 741 responders were analyzed. Result: The mean age of responders was 31.8 years. Among them, males were 57.8%. Current smokers, ex-smokers, and non-smokers were 13.8%, 12.8%, and 73.4% respectively. According to smoking status, the total KTSND scores of current smokers were significantly higher than those of ex-smokers, and of non-smokers ($17.1{\pm}5.4$ versus $14.3{\pm}5.5$, and $12.3{\pm}5.5$, $p{\leq}0.001$). The total KTSND scores of males were higher than those of females, suggesting that males have a propensity for depending nicotine socially much more than females ($14.3{\pm}5.7$ and $11.7{\pm}5.4$ respectively, p<0.001). Eight of ten questions produced significantly different scores among three different smoking groups. When current smokers were sub-classified by heavy smoking index (HSI) that represented physical nicotine dependence, we did not find a significant difference of KTSND score between low HSI group (<4) and high HSI group (${\geq}4$), This finding suggested that the psychosocial dependence might play a different role from physical nicotine dependence in smoking. Most of the non-smokers (62.5%) had an experience of harmful passive smoking especially in public place. Conclusion: Our study suggested that the KTSND questionnaire could be a useful method to evaluate psychosocial aspects of smoking.

• Journal of Korean Society of Transportation
• /
• v.18 no.6
• /
• pp.63-75
• /
• 2000

Stated Preference (SP) data has been regarded as more useful than Revealed Preference (RP) data, because researchers can investigate the respondents\` Preference and attitude for a traffic condition or a new traffic system by using the SP data. However, the SP data has two bias: the first one is the bias inherent in SP data and the latter one is the attrition bias in SP panel data. If the biases do not corrected, the choice model using SP data may predict a erroneous future demand. In this Paper, six route choice models are constructed to deal with the SP biases, and. these six models are classified into cross-sectional models (model I∼IH) and dynamic models (model IV∼VI) From the six models. some remarkable results are obtained. The cross-sectional model that incorporate RP choice results of responders with SP cross-sectional model can correct the biases inherent in SP data, and also the dynamic models can consider the temporal variations of the effectiveness of state dependence in SP responses by assuming a simple exponential function of the state dependence. WESML method that use the estimated attrition probability is also adopted to correct the attrition bias in SP Panel data. The results can be contributed to the dynamic modeling of SP Panel data and also useful to predict more exact demand.

• Journal of the Korea Convergence Society
• /
• v.9 no.10
• /
• pp.355-362
• /
• 2018

This study aims to examine the relationship between physical education class activity of youth, smartphone dependence and school life adaptation. The data set of Korean Children and Youth Panel Survey(KCYPS) by National Youth Policy Institute was reanalyzed for this study. The subjects of this study were 2,351 second grade middle school students from 2011. The data were coded with the use of the statistics program on Windows, SPSS 23.0. To analyse the data, descriptive analysis, reliability analysis, one-way ANOVA and regression analysis were employed. The findings of this research are as follows. First, the difference between the activity hours of youth physical education classes and the reliance on smartphones is less dependent on smartphones as they participate enthusiastically in physical education classes. Second, the difference of physical education class activity time and school life adaptation among adolescents was more positive for school life adaptation as learning activity, peer relationship and teacher relationship were more active. third, the dependence of youth on smartphones has a positive effect on learning activities and school rules as the reliance on smartphones is low.

• Journal of the Korean Mathematical Society
• /
• v.33 no.4
• /
• pp.1039-1046
• /
• 1996

In the theory of partial differential equations with given initial values and boundary values one usually investigates to examine the well-posedness, that is, the unique existence of the solution as well as its continuous dependence on the data. This theory is strong enough for us to determine the situation anywhere and anytime provided that the initial data are actually given. However, in many cases the data are not completely known for us. Then in those situations arise the new problem to determine the unknown initial data by taking other conditions for the solutions.

• Journal of Digital Convergence
• /
• v.14 no.2
• /
• pp.295-303
• /
• 2016

This study aimed to assess the influence of nicotine dependence with satisfaction of basic psychological needs, social support, attitude on smoking among middle school students. From Sep, 2015 to Nov, 2015, participants included 150 middle school students from D city and K province in Korea. Data for basic psychological needs, social support, attitude on smoking and nicotine dependence were collected through a self-reported questionnaire and were analyzed with independent t-test and analysis of variance, Pearson's correlation analysis, and multiple linear regression analysis. This study shows negative correlations between nicotine dependence and satisfaction of basic psychological needs(r=-.221, P=.008), competency(r=-.194, P=.021), relatedness(r=-.219, P=.009). The variables predicting nicotine dependence were satisfaction of basic psychological needs(${\beta}=.221$, p=.008). These variables accounted for 42% of the variance of nicotine dependence in smoking middle school students. Our results indicated that it is necessary to increase basic psychological needs to decrease nicotine dependence. Therefore we should develop programs in order to increase satisfaction of basic psychological needs.

• Journal of Digital Contents Society
• /
• v.16 no.3
• /
• pp.463-470
• /
• 2015

The angular dependence of active dosimeters, EPD, is analysed and compared with that of passive dosimeters, OSLD, after evaluating their relative response and uncertainty of measurement, where it is known that the personal use of them has been increased recently. There appeared a minor variation for average relative response of OSLD in the horizontal and vertical directions within the range $0^{\circ}{\sim}{\pm}90^{\circ}$, which are 0.97 and 0.95 respectively. The variations of angular dependence in the same situations with OSLD are 0.65 and 0.62, respectively, which also reveals a negligible effect on the overall uncertainty. EPDs within the interval $0^{\circ}{\sim}{\pm}60^{\circ}$ for horizontal and vertical directions are 0.94 and 0.97, respectively. These satisfy the requirements of IEC 61526. Uncertainties about the dependence of direction from horizontal and vertical directions are 0.44, 0.40, respectively. The impact of these uncertainties on the overall uncertainty was negligible. However, we observed a significant change in reactivity: the relative reactivities for $+90^{\circ}$ and $-90^{\circ}$ from the horizontal direction are 0.60, 0.37, while that form vertical direction is 0.06. The direction dependence of OSLD was superior to EPD in the range of $0^{\circ}{\sim}{\pm}90^{\circ}$. There appeared a rapidly changing structural features in EPD response for a certain direction. Therefore, we conclude that concurrent use of passive dosimeters and auxiliary dosimeter provides accurate data for personal dose measurements.

• Korea-Australia Rheology Journal
• /
• v.13 no.4
• /
• pp.189-196
• /
• 2001

The phase morphology is an important factor in the rheology of immiscible polymer blends. Through its size and shape, the interface between the two phases determines how the components and the interface itself will contribute to the global stresses. Rheological measurements have been used successfully in the past to probe the morphological changes in model blends, particularly for dilute systems. For more concentrated blends only a limited amount of systematic rheological data is available. Here, viscosities and first normal stress differences are presented for a system with nearly Newtonian components, the whole concentration range is covered. The constituent polymers are PDMS and PIB, their viscosity ratio can be changed by varying the temperature. The data reported here have been obtained at 287 K where the viscosities of the two components are identical. By means of relaxation experiments the measured stresses are decomposed into component and interfacial contributions. The concentration dependence is quite different for the two types of contribution. Except for the component contributions to the shear stresses there is no clear indication of the phase inversion. Plotting either the interfacial shear or normal stresses as a function of composition produces in some cases two maxima. The relaxation times of these stresses display a similar concentration dependence. Although the components have the same viscosity, the stress-component curves are not symmetrical with respect to the 50/50 blend. A slight elasticity of one of the components seems to be the cause of this effect. The data for the more concentrated blends at higher shear rates are associated with a fibrillar morphology.

• Journal of Astronomy and Space Sciences
• /
• v.29 no.2
• /
• pp.97-101
• /
• 2012

Monitoring sunspots consistently is the most basic step required to study various aspects of solar activity. To achieve this goal, the observers must regularly calculate their own correction factor $k$ and keep it stable. Relatively recently, two observing teams in South Korea have presented interesting papers which claim that revisions that take the yearly-basis $k$ into account lead to a better agreement with the international relative sunspot number $R_i$, and that yearly $k$ apparently varies with the solar cycle. In this paper, using artificial data sets we have modeled the sunspot numbers as a superposition of random noise and a slowly varying background function, and attempted to investigate whether the variation in the correction factor is coupled with the solar cycle. Regardless of the statistical distributions of the random noise, we have found the correction factor increases as sunspot numbers increase, as claimed in the reports mentioned above. The degree of dependence of correction factor $k$ on the sunspot number is subject to the signal-to-noise ratio. Therefore, we conclude that apparent dependence of the value of the correction factor $k$ on the phase of the solar cycle is not due to a physical property, but a statistical property of the data.

• Bulletin of the Korean Chemical Society
• /
• v.7 no.1
• /
• pp.29-35
• /
• 1986

An empirical formula for semiconductive metal oxides is proposed relating nonstoichiometric value x to a temperature or an oxygen partial pressure such that experimental data can be represented more accurately by the formula than by the well-known Arrhenius-type equation. The proposed empirical formula is log x = A + $B{\cdot}1000/T\;+\;C{\cdot}$exp$(-D{\cdot}1000/T)$ for a temperature dependence and $log\;{\times}\;=a\;+b{\cdot}log\;Po_2\;+\;c{\cdot}$exp$(-d{\cdot}log\;Po_2)$ for an oxygen partial pressure dependence. The A, B, C, D and a, b, c, d are parameters which are evaluated by means of a best-fitting method to experimental data. Subsequently, this empirical formula has been applied to the n-type metal oxides of $Zn_{1+x}O,\; Cd_{1+x}O,\;and\;PrO_{1.8003-x}$, and the p-type metal oxides of $CoO_{1+x},\; FeO_{1+x},\;and\;Cu_2O_{1+x}$. It gives a very good agreement with the experimental data through the best-fitted parameters within 6% of relative error. It is also possible to explain approximately qualitative characters of the parameters A, B, C, D and a, b, c, d from theoretical bases.

• Communications for Statistical Applications and Methods
• /
• v.30 no.4
• /
• pp.369-388
• /
• 2023

In this paper, we develop the two-step procedure that detects and estimates the position of structural changes for multivariate nonstationary time series, either on mean parameters or second-order structures. We first investigate the presence of mean structural change by monitoring data through the aggregated cumulative sum (CUSUM) type statistic, a sequential procedure identifying the likely position of the change point on its trend. If no mean change point is detected, the proposed method proceeds to scan the second-order structural change by modeling the multivariate nonstationary time series with a multivariate locally stationary Wavelet process, allowing the time-localized auto-correlation and cross-dependence. Under this framework, the estimated dynamic spectral matrices derived from the local wavelet periodogram capture the time-evolving scale-specific auto- and cross-dependence features of data. We then monitor the change point from the lower-dimensional approximated space of the spectral matrices over time by applying the dynamic principal component analysis. Different from existing methods requiring prior information on the type of changes between mean and covariance structures as an input for the implementation, the proposed algorithm provides the output indicating the type of change and the estimated location of its occurrence. The performance of the proposed method is demonstrated in simulations and the analysis of two real finance datasets.