• Korean Journal of Health Education and Promotion
• /
• v.27 no.4
• /
• pp.177-188
• /
• 2010

Objectives: The aim of this study was to examine factors related to smoking behavior, and to develop multilevel communication strategies for smoking cessation. Methods: This paper reviewed theories and empirical findings with currents ecological models to develop communication strategies. Theory comparison was also performed to identify important mediators in the process of smoking cessation. Results: Factors that have been identified to influence smoking behavior ranges from individual perception, attitudes and self efficacy toward smoking to organizational norms, regulations, community capacity, media advocacy and public smoking regulation policy. In order to address these multi-level determinants of smoking behavior, objectives and strategies for smoking cessation intervention were developed utilizing ecological perspectives to cover intrapersonal, interpersonal(mainly family member and peers), organizational and community/public policy level factors. Conclusion: Multilevel approaches have advanced the existing knowledge on determinants of health behaviors. New direction of research focusing on testing multilevel intervention approaches should be expanded to inform the efficacy of applying social ecological models to health behavior change process.

• International Commerce and Information Review
• /
• v.10 no.1
• /
• pp.395-414
• /
• 2008

The objective of this study is to introduce the concepts and theories of conditional heteroscedastic volatility models and the news impact curves and apply them to the Korea inbound tourism market. Three volatility models were introduced and used to estimate the conditional volatility of monthly arrivals of inbound tourists into Korea and news impact curves according to the three models. Results of this study are as follows. As the proportion of American tourists occupied a large amount of Korea inbound tourism market, the markets' forecasting is very important. The news impact curves which used EGARCH model (1,1) and TGARCH model(1,1), with data on these tourists to Korea showed an asymmetry effect of volatility. It was common that bad news means that it was estimated more sensitively than good news. From these results, we will notice that American tourists who visited Korea only for tourism are affected by good news. The result suggests that the Korea government and tourism industry should pay more attention to changes in the tourism environment following bad news because conditional volatility increases more when a negative shock occurs than when a positive shock occurs.

• Korean Journal of Biological Psychiatry
• /
• v.20 no.3
• /
• pp.66-73
• /
• 2013

Sexual behavior is crucial in life, yet comparatively little is known about the mechanisms in the sexual response in humans. A lot of theories and models have been developed to explain about the process of the sexual response in humans. The first model of sexual function was described by Masters and Johnson, defined the four-phase model (phases of excitation, plateau, orgasm and resolution). Helen Kaplan proposed a slightly different model of human sexual response by adding the conception of the desire phase. Some years later, a new model of circular sexual response pattern was described by Whipple and Brash-McGreer, who acknowledged the cyclic nature of women's sexual response. Basson presented an alternative model of women's normative sexual function, which featured a responsive form of desire in women's sexual response. Bancroft developed a new theoretical model, the Dual Control Model, which postulates sexual response and arousal is ultimately determined by the balance between the sexual activation or excitation system and the sexual inhibition system. The Sexual Tipping Point is a model created by Perelman, suggesting that a sexual response is determined by a balance between excitatory or inhibitory factors that may be psychological, organic, psychosocial, or cultural. A comprehensive understanding of sexual response and function is of paramount importance for the psychiatrist to study sex, offer counseling to the patient on sex, and practice sex therapy. In this literature, models of sexual response would be reviewed to understand the knowledge of the sexual functioning in humans.

• Journal of The Korean Astronomical Society
• /
• v.36 no.3
• /
• pp.177-187
• /
• 2003

Active galactic nuclei (AGNs) are distant, powerful sources of radiation over the entire electromagnetic spectrum, from radio waves to gamma-rays. There is much evidence that they are driven by gravitational accretion of stars, dust, and gas, onto central massive black holes (MBHs) imprisoning anywhere from $\~$1 to $\~$10,000 million solar masses; such objects may naturally form in the centers of galaxies during their normal dynamical evolution. A small fraction of AGNs, of the radio-loud type (RLAGNs), are somehow able to generate powerful synchrotron-emitting structures (cores, jets, lobes) with sizes ranging from pc to Mpc. A brief summary of AGN observations and theories is given, with an emphasis on RLAGNs. Preliminary results from the imaging of 10000 extragalactic radio sources observed in the MITVLA snapshot survey, and from a new analytic theory of the time-variable power output from Kerr black hole magnetospheres, are presented. To better understand the complex physical processes within the central engines of AGNs, it is important to confront the observations with theories, from the viewpoint of analyzing the time-variable behaviours of AGNs - which have been recorded over both 'short' human ($10^0-10^9\;s$) and 'long' cosmic ($10^{13} - 10^{17}\;s$) timescales. Some key ingredients of a basic mathematical formalism are outlined, which may help in building detailed Monte-Carlo models of evolving AGN populations; such numerical calculations should be potentially important tools for useful interpretation of the large amounts of statistical data now publicly available for both AGNs and RLAGNs.

• Journal of Korean Elementary Science Education
• /
• v.22 no.1
• /
• pp.109-120
• /
• 2003

The purpose of this study is to observe, to analyze of the preservice teachers' naive theories about the change of season. And it is to find a instruction strategy which can solve problem about this. The general idea about the change of season is observed by the 3 methods which are simply explaining with words, explaining with pictures and models. The author is to find the similarity. difference and relationship which the preservice teachers have about the general idea about the change of season. The important changable primary factors, which can effect to the general Idea formation, are naturally dragged out through the observation of preservice teachers participation. For this study, 4 first year preservice teachers of one of national university of education are used. Before the interview. the author tries to form rapport with the preservice teachers. Experiment materials, pencil. paper, camcorder, digital recorder and interview note were used for the study with reflection of them just way they are. As the result of the interview. all of 4 preservice teachers had not being understand the concept about the change of season and the three ways of explanation methods were not matched each other, so it is revealed that the general Idea of the change of season, which the preservice teachers have, is not strongly formed. In spite of the repeated study of the change of season from elementary school to university, it has many problem about recognition of the general idea about the change of season which pre-elementary teachers have. Therefore it is needed to improve the experiment in elementary science text book and naive theories by the activity which is explaining the change of season in three dimension space. to prevent the naive theories which the preservice teachers may have.

• Structural Engineering and Mechanics
• /
• v.6 no.5
• /
• pp.497-516
• /
• 1998

A relatively simple two-dimensional multilayered shell model is presented for predicting both global quantities and stress distributions across the thickness of multilayered thick shells, that is based on a third-order zig-zag approach. As for any zig-zag model, the layerwise kinematics is accounted for, with the stress continuity conditions at interfaces met a priori. Moreover, the shell model satisfies the zero transverse shear stress conditions at the upper and lower free surfaces of the shell, irrespective of the lay-up. By changing the parameters in the displacement model, some higher order shell models are obtained as particular cases. Although it potentially has a wide range of validity, application is limited to cylindrical shell panels in cylindrical bending, a lot of solutions of two-dimensional models based on rather different simplyfying assumptions and the exact three-dimensional elasticity solution being available for comparisons for this benchmark problem. The numerical investigation performed by the present shell model and by the shell models derived from it illustrates the effects of transverse shear modeling and the range of applicability of the simplyfying assumptions introduced. The implications of retaining only selected terms depending on the radius-to-thickness ratio are focused by comparing the present solutions to the exact one and to other two-dimensional solutions in literature based on rather different simplyfying assumptions.

• Biomolecules & Therapeutics
• /
• v.24 no.3
• /
• pp.207-243
• /
• 2016

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social and communication impairments, as well as repetitive and restrictive behaviors. The phenotypic heterogeneity of ASD has made it overwhelmingly difficult to determine the exact etiology and pathophysiology underlying the core symptoms, which are often accompanied by comorbidities such as hyperactivity, seizures, and sensorimotor abnormalities. To our benefit, the advent of animal models has allowed us to assess and test diverse risk factors of ASD, both genetic and environmental, and measure their contribution to the manifestation of autistic symptoms. At a broader scale, rodent models have helped consolidate molecular pathways and unify the neurophysiological mechanisms underlying each one of the various etiologies. This approach will potentially enable the stratification of ASD into clinical, molecular, and neurophenotypic subgroups, further proving their translational utility. It is henceforth paramount to establish a common ground of mechanistic theories from complementing results in preclinical research. In this review, we cluster the ASD animal models into lesion and genetic models and further classify them based on the corresponding environmental, epigenetic and genetic factors. Finally, we summarize the symptoms and neuropathological highlights for each model and make critical comparisons that elucidate their clinical and neurobiological relevance.

• East Asian Economic Review
• /
• v.24 no.1
• /
• pp.61-87
• /
• 2020

Five diffusion models are estimated using three different foreign exchange rates to find an appropriate model for each. Daily spot exchange rates expressed as the prices of 1 euro, 1 British pound and 100 Japanese yen in US dollars, respectively denoted by USD/EUR, USD/GBP, and USD/100JPY, are used. The maximum likelihood estimation method is implemented after deriving an approximate log-transition density function (log-TDF) of the diffusion processes because the true log-TDF is unknown. Of the five models, the most general model is the best fit for the USD/GBP, and USD/100JPY exchange rates, but it is not the case for the case of USD/EUR. Although we could not find any evidence of the mean-reverting property for the USD/EUR exchange rate, the USD/GBP, and USD/100JPY exchange rates show the mean-reversion behavior. Interestingly, the volatility function of the USD/EUR exchange rate is increasing in the exchange rate while the volatility functions of the USD/GBP and USD/100Yen exchange rates have a U-shape. Our results reveal that more care has to be taken when determining a diffusion model for the exchange rate. The results also imply that we may have to use a more general diffusion model than those proposed in the literature when developing economic theories for the behavior of the exchange rate and pricing foreign currency options or derivatives.

• Structural Engineering and Mechanics
• /
• v.67 no.5
• /
• pp.527-544
• /
• 2018

In this paper, the effect of homogenization models on stress analysis is presented for functionally graded plates (FGMs). The derivation of the effective elastic proprieties of the FGMs, which are a combination of both ceramic and metallic phase materials, is of most of importance. The majority of studies in the last decade, the Voigt homogenization model explored to derive the effective elastic proprieties of FGMs at macroscopic-scale in order to study their mechanical responses. In this work, various homogenization models were used to derive the effective elastic proprieties of FGMs. The effect of these models on the stress analysis have also been presented and discussed through a comparative study. So as to show this effect, a refined plate theory is formulated and evaluated, the number of unknowns and governing equations were reduced by dividing the transverse displacement into both bending and shear parts. Based on sinusoidal variation of displacement field trough the thickness, the shear stresses on top and bottom surfaces of plate were vanished and the shear correction factor was avoided. Governing equations of equilibrium were derived from the principle of virtual displacements. Analytical solutions of the stress analysis were obtained for simply supported FGM plates. The obtained results of the displacements and stresses were compared with those predicted by other plate theories available in the literature. This study demonstrates the sensitivity of the obtained results to different homogenization models and that the results generated may vary considerably from one theory to another. Finally, this study offers benchmark results for the multi-scale analysis of functionally graded plates.

• Journal of the Korean School Mathematics Society
• /
• v.11 no.1
• /
• pp.69-96
• /
• 2008

The purpose of this paper is to perceive the problems of current geometry education in the middle school mathematics, to develop some learning materials fitted for the mathematising activities based on Freudenthal's learning theories and to analyze the mathematising process followed by teaching-learning activities. For this purpose, we design activity-oriented learning materials for geometry based on Freudenthal's learning theories, and appropriate teaching-learning models are established for the middle school geometry at the 8-NA stage level according to the theory of van Hiele's geometry learning steps. After applied to the practical lessons, the effects of mathematical activities are analyzed.