• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.249-255
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• 2004

Here we present a linear stability analysis and an MHD 2D model for the Parker-Jeans instability in the Galactic gaseous disk. The magnetic field is assumed parallel to a Galactic spiral arm, and the gaseous disk is modelled as a multi-component, magnetized, and isothermal gas layer. The model employs the observed vertical stratifications for the gas density and the gravitational acceleration in the Solar neighborhood, and the self-gravity of the gas is also included. By solving Poisson's equation for the gas density stratification, we determine the vertical acceleration due to self-gravity as a function of z. Subtracting it from the observed gravitational acceleration, we separate the total acceleration into self and external gravities. The linear stability analysis provides the corresponding dispersion relations. The time and length scales of the fastest growing mode of the Parker-Jeans instability are about 40 Myr and 3.3 kpc, respectively. In order to confirm the linear stability analysis, we have performed two-dimensional MHD simulations. These show that the Parker-Jeans instability under the self and external gravities evolves into a quasi-equilibrium state, creating condensations on the northern and southern sides of the plane, in an alternate manner.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.139-146
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• 1995

The bright part of the halo luminosity function is derived from a sample of the 233 NLTT propermotion stars, which are selected by the 220 km/ see of cutoff velocity in transverse to rid the contamination by the disk stars and corrected for the stars omitted in the sample by the selection criterion. It is limited to the absolute magnitude range of $M_v=4-8$, but is based on the largest sample of halo stars up to now. This luminosity function provides a number density of $2.3{\cdot}10^{-5}pc^{-3}$ and a mass density of $2.3{\cdot}10^{-5}M_{o}pc^{-3}$ for 4 < $M_v$ < 8 in the solar neighborhood. These are not sufficient for disk stability. The kinematics of the sample stars are < U > = - 7 km/sec, < V > = - 228 km/sec, and < W > = -8 km/sec with (${\sigma_u},{\sigma_v},{\sigma_w}$) = (192, 84, 94) km/sec. The average metallicity of them is [Fe/H] = $- 1.7{\pm}0.8$. These are typical values for halo stars which are selected by the high cutoff velocity. We reanalyze the luminosity function for a sample of 57 LHS proper-motion stars. The newly derived luminosity function is consistent with the one derived from the NLTT halo stars, but gives a somewhat smaller number density for the absolute magnitude range covered by the LF from NLTT stars. The luminosity function based on the LHS stars seems to have a dip in the magnitude range corresponding to the Wielen Dip, but it also seems to have some fluctuations due to a small number of sample stars.

• Architectural research
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• v.14 no.4
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• pp.125-132
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• 2012

In contemporary Korean society, urban community environment is often associated with high-density and high-rise residences that make people's relationships superficial, instrumental and impersonal. Furthermore, urban community consistently interplays with neighboring residents and childhood emotional experience are influential on their unconscious images and attitude about their current neighborhood environment, while affecting the environmental attitude and the formation of community sense. Previous research found evidences that increased level of community sense is fostering more feeling of living in so-called "real neighborhood environment." This study aimed to cross-culturally examine what the respondents' emotional perception and their attitude were about the community environment in their childhood through environmental autobiography method and to examine the effects of the results on adults' formation of sense of community for their current community environment. Extensive literature review explored a few important theoretical framework which are closely related to sense of community (SOC) as a result of emotional experience: membership, influence, integration and fulfillment of needs, shared emotional connection and community satisfaction. Chi-square and GLM analysis revealed that there were no demographic, and socio-economic differences between two groups of Korean and US residents. Correlation analysis indicated that childhood emotional experience of Koreans and US citizens was statistically significant on sense of community for their current living community. Multi-regression analysis also found that the degree of influence were the main predictors for building strong sense of current community throughout a cross-cultural group. Furthermore, the relationship between various emotional experience of each factor in previous and current community environment were statistically significantly related. It is concluded that as the positive childhood experience of influence in their past community was going up, the level of sense of community for their current community was strengthened across their cross-cultural background.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2004.11a
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• pp.111-116
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• 2004

This study is aimed to be used as basic data to plan Korean style cohousing for double-income families in the future by studying their lifestyle, housing needs and housing awareness on cohousing. The results of the study are as follows. 1) As for the life style of the subject families, it was a housewife that mainly does the household affairs despite of the status of double-income family. Also, as for the social activity, almost half of the respondents said that the spending in child-care facilities was not sufficient and wanted to send their children to ones within their neighborhood. 2) As far as housing awareness on cohousing concerned, among specific items, the child care area, the household affairs division area, and participatory awareness of residents in housing planning and management got higher scores, while as for awareness on utilizing common space, using the common hobby rooms, promenades and benches, exercise facilities, common yard, and study rooms got higher scores. When asked about the necessity for cohousing in Korea, they gave very positive answers, but the answer to their willingness to reside in it was less positive. 3) Summarizing the housing needs on cohousing, it turned out that more people wanted to reside in suburban area with others having common grounds with them as for a desirable residence environment. They wanted the neighborhood to be composed of 10${\sim}$29 families, and medium-density semi-detached house occupied by owners. They wanted a mixture of independent management and entrust management for managing common facilities, and common meal once a week. They wanted indoor exercise facilities to be more extended than other common facilities, and the house of $100m^{2}{\sim}130m^{2}$ with 3 bedrooms, 2 bath rooms, and a large living room and dining room.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.33-42
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• 2020

This study analyzed the bicycle traffic patterns and identified the influence factors for each traffic purpose using the household traffic conditions survey for Seoul. The results are summarized as follows. First, as a result of surveying the bicycle traffic ratios according to the administrative dongs, there was a difference of 14.2% by region. Second, various personal characteristic variables, such as age, gender, income, occupation, and housing type, affect the bicycle mode choice, and bicycle passage increases when using facilities in residential areas. Third, among the neighborhood environments, the bicycle traffic for commuting purposes appeared to increase more in the areas of higher land use mix and lower crime rates. In addition, the bicycle road density and the inclination of the area commonly affect bicycle travel for commuting, shopping, exercising, and leisure.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.738-740
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• 2003

A method for identifying the released region and time of Asian dust using the long-range inverse transport model that traces the wind field in the backward direction from positions where Asian dust was observed is described. Initial conditions for the inverse transport simulation were obtained from the time variation of the density distribution of the suspended particulate matter (SPM) in the air measured at various places in Japan. Based on a concentration of trajectories of the air mass computed by the inverse transport model, the source region of Asian dust clouds observed at meteorological stations in Japan on March 17 to 18, 2002 was estimated. As a result, it was found that dust particles were released at about 6h on March 15 in the neighborhood of Inner Mongolian Autonomous Region.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.1
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• pp.42-54
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• 1996

Many of urban parks which have been designated for urban planning regulation are not well developed because the priority of investment is inferior to that of other public facilities. Park development is an urgent urban policy and it is hard to decide priority among parks. Therefore, it is necessary to evaluate the priority of park development. Thus the Analytic Hierarchy Process has been introduced because it is suitable for achieving objectivity by collecting the professional opinions. The goals of park development are evaluated by AHP method and the priorities among goals are conservation of natural environment, satisfying the residents' residents' needs, population density, regional pollution, land acquisition cost, ratio of greeneries and facilities within park areas. Priority of park development is decided by the standardization of each individual inventory data and considering of the professional opinions. Among the multi-attribute judgement methods, AHP method may be the most widely used. Despite the critical evaluations of the AHP, such as limitation of the nine-point scale and the rank reversal problem, application of AHP to decide the priority of park development is suitable for actual circumstances.

• Journal of Biomedical Engineering Research
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• v.14 no.3
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• pp.209-220
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• 1993

Microspheres are expected to be applied to biomedical areas such as solid-phase immunoassays, drug delivery systems, Immunomagnetic cell separation. To synthesize micro-spheres for biomedical application, "two stage shot growth method" was developed. The uniformity ratio or synthesized microspheres was always smatter than 1.05. And the surface charge density (or the number of ionizable functional groups) of the microspheres synthesized by "two stage shot growth method" was 6-13 times higher than thats of the ml crospheres synthesized by conventional seeded batch copolymerization. As a previous step for biomedical application, adsorption experiments of bovine albumin on microspheres were carried out under various conditions. The maximum adsorbed amount was obtained in the neighborhood of pH 4.5. Isoelectric point of bovine albumin Is pH 5.0, so experimental result shows that it shifted to acid area. The adsorption Isotherm was obtained, the plateau region was always reached at 2.Og/L (bulk concentration of bovine albumin ) . The effect of the kind and the amount of surface functional group was also examined.p was also examined.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.183-190
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• 1986

Microspheres are expected to be applied to biomedical areas such as solid-phase immunoassays, drug delivery systems, immunomagnetic cell separation. To synthesize microspheres for biomedical application, "two stage shot growth method" was developed. The uniformity ratio of synthesized microspheres was always smaller than 1.05. And the surface charge density (or the number of ionizable functional groups) of the microspheres synthesized by "two stage shot growth method" was 6~13 times higher than that of the microspheres synthesized by conventional seeded batch copolymerization. As a previous step for biomedical application, adsorption experiments of bovine albumin on microspheres were carried out under various conditions. The maximum adsorbed amount was obtained in the neighborhood of pH 4.5. Isoelectric point of bovine albumin is pH 5.0, so experimental result shows that it shifted to acid area. The adsorption isotherm was obtained, the plateau region was always reached at 2.Og/L (bulk concentration of bovine albumin).The effect of the kind and the amount of surface functional group was also examined.p was also examined.

• The Korean Journal of Applied Statistics
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• v.22 no.6
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• pp.1345-1353
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• 2009

We introduce a simple methodology, so-called generalized gamma-polynomial approximation, based on moment-matching technique to approximate survival and hazard functions in the context of parametric survival analysis. We use the generalized gamma-polynomial approximation to approximate the density and distribution functions of convolutions and finite mixtures of random variables, from which the approximated survival and hazard functions are obtained. This technique provides very accurate approximation to the target functions, in addition to their being computationally efficient and easy to implement. In addition, the generalized gamma-polynomial approximations are very stable in middle range of the target distributions, whereas saddlepoint approximations are often unstable in a neighborhood of the mean.