• Korean Journal of Social Welfare Studies
• /
• v.44 no.3
• /
• pp.301-322
• /
• 2013

By analyzing wave 1~11 (1998~2008) of Korean Labor and Income Panel Study(KLIPS) database, this study examines the effects of household characteristics and poverty duration on poverty exit. A special concern is to decide whether the decrease of poverty exit rates comes from true duration dependency or from the sample heterogeneity as poverty duration progresses. I also analyzed how the effects of independent variables are changed when unobserved heterogeneity is controlled. The results show that duration dependency disappears after controlling observed household characteristics and unobserved individual heterogeneity. This finding confirms that the apparent relationship between poverty exit rate and poverty duration is in fact a spurious association due to the sample heterogeneity rather than true duration dependency. In addition, the effects of household characteristics on poverty exit rate become more stronger when unobserved heterogeneity is controlled. Socioeconomic factors affecting poverty exit rates are such as householders' age, education, household composition, number of family members, labor force participation, and work status.

• Wind and Structures
• /
• v.29 no.5
• /
• pp.323-337
• /
• 2019

Wind tunnel testing technique has been established as a powerful experimental method for predicting wind-induced loads on high-rise buildings. Accurate assessment of the design wind load combinations for tall buildings on the basis of wind tunnel tests is an extremely important and complicated issue. The traditional design practice for determining wind load combinations relies partly on subjective judgments and lacks a systematic and reliable method of evaluating critical load cases. This paper presents a novel optimization-based framework for determining wind tunnel derived load cases for the structural design of wind sensitive tall buildings. The peak factor is used to predict the expected maximum resultant responses from the correlated three-dimensional wind loads measured at each wind angle. An optimized convex hull is further developed to serve as the design envelope in which the peak values of the resultant responses at any azimuth angle are enclosed to represent the critical wind load cases. Furthermore, the appropriate number of load cases used for design purposes can be predicted based on a set of Pareto solutions. One 30-story building example is used to illustrate the effectiveness and practical application of the proposed optimization-based technique for the evaluation of peak resultant wind-induced load cases.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.31 no.5
• /
• pp.305-313
• /
• 2019

Number of coastal protection structures have been increased rapidly due to rising sea levels and deteriorated sea conditions. Coastal structures should be designed to meet coastal engineering requirements and ecosystem conditions, while they are not lost or removed. In this study, trapezoidal gabion block was developed for the purpose, and two-dimensional laboratory experiments were conducted to validate applicability of the block. The experiments were carried out with eight types of erosive and accretive wave conditions. As a result, it was confirmed that the gabion blocks have a feature of preventing erosion of beach. The newly designed gabion blocks could be an alternative as a countermeasure method for beach erosion.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.14 no.4
• /
• pp.10-15
• /
• 2010

Light gas guns have a large number of applications in various fields of engineering. A two-stage light-gas gun can produce an extremely high pressure in a very short interval of time. In general, the two-stage light-gas gun is made up of a high pressure tube, a compression tube and a launch tube, each stage being separated by diaphragms. This can be employed efficiently in the application of ultra-high pressure liquid jets. In the present study, experiments are carried out to investigate the projectile velocity and pressure behavior in the tubes according to the pressure changes at the frist diaphragm opening. In the present study result was found that the rupture pressure of the first diaphragm has a dominant influence on piston acceleration.

• Journal of Convergence for Information Technology
• /
• v.7 no.2
• /
• pp.37-42
• /
• 2017

In order to estimate chaff RCS, we suggest here a novel method using the probability distribution. Normally, a chaff is assumed that it is a thin dipole antenna and the RCS can be calculated by the scattering wave theory. Most of the theoretical methods presented were mainly focusing on a single chaff cloud. In this paper, the RCS calculation was done for two or more chaff clouds and the changes of RCS with azimuth angle were observed. Matlab was used for presenting the probability distribution of chaff clouds and RCS calculation. A more accurate RCS estimation method is suggested by estimating the number of chaffs except the blocked elements.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.3
• /
• pp.19-30
• /
• 1990

This note describes an application of Hamiton's principle to nonlinear free-surface flow problems. Two functionals are constructed based on classical Hamilton's principle with a modification due to the presence of a free surface. As an effort towards the development of an efficient numerical scheme for our problem, we present the following three test results: i) The bounding principles of the eigenvalues for the linear dispersion relation. ii) By assuming steady solitary waves, an approximate relation between the amplitudes and the speeds of solitary waves are derived from the two functionals constructed. Their numerical results are compared with those of Longuet-Higgins & Fenton(1974). iii) The shapes and charicteristics of solitary waves are computed from two sets of functionals by varying the number of total finite elements in the fluid domain.

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.1
• /
• pp.50-62
• /
• 1994

This paper presents the results of a comparative analysis of the model test results to investigate the effect of bulbous bow installed on a large full form ship to the ship resistance performance. Seven parameters related to the shape of bulbous bow were selected and varied systematically to inquire their effects experimentally. A total number of twenty-three ship models with different bulbous bow were manufactured, and resistance tests. flow visualization test, and wave profile measurement were carried out for each model. For the comparative analysis between the various bulb forms and their model test results, bulbous bow forms are classified into nine groups according to their form characteristics. From the analysis of the trend of the resistance components, it was verified that form resistance has dominant effect on the total resistance of a slow full form ship. The model test and its statistical analysis showed that the direction of streamlines around bulbous bow has close relationship with resistance components. especially with form resistance

• Solar Energy
• /
• v.11 no.1
• /
• pp.27-40
• /
• 1991

Research and development works on practical application of natural energy utilization systems involving solar, wind and sea wave energies are under promoting for the purpose of improving the energy consumption structure. These natural energies, made available with the use of relatively simple apparatus, are clean economically efficient and highly effective in the conservation of environment. However, these natural energies also have low energy density, randomness and regional variations. To compensate for these characteristics, hybrid utilization of solar and wind energies is currently under study. The introduction of a plural number of the natural energy hybrid utilization systems into a specific area will affect the economic efficiency, reliability and environmental conservation. Evaluation method of such effects has been examined in this study. The present method consisted of the steps described below. First, available energy was calculated from insolation distribution and wind velocity distribution in the specified area, and then the effect on the configuration of the power system load was obtained. This was followed by the determination of the optimal power dispatch over the specified period and by evaluations in light of economic efficiency, reliability and environmental indices.

• Korea Real Estate Review
• /
• v.28 no.3
• /
• pp.79-94
• /
• 2018

This study analyzed the factors associated with residential mobility based on the data from the 11th to the 19th wave of the Korean Labor & Income Panel Study (KLIPS). After grouping low-income households within the first to the fourth income bracket into households that exhibited no income bracket change and those with income bracket changes during the research period, this study examined the effects of the income situation of each group on residential mobility. According to the results of the analysis, in the group of households that showed no low-income bracket change, significant effects were found only in the age of the head of the household, housing cost, and rental deposit (Jeonse) and monthly rental of the household. In the group of households that showed low-income bracket changes, findings were generally in line with those of the whole household, where total income and the number of full-time employees in the household were the same as those of the whole household, indicating that it would be necessary to improve the employment stability of low-income households. Based on the findings of this study, housing inequality is intensifying within low-income households, and, thus, housing policies, based on continuing surveys, must be implemented to enhance income opportunities and stabilize the housing needs of low-income households.

• Cross-Cultural Studies
• /
• v.29
• /
• pp.177-199
• /
• 2012

Nowadays migrations between the countries are getting each day more active and a mixture of people with different cultural backgrounds strengthens the hybridism, whereupon the point of view on the migration of Koreans has been changed from a diasporan perspective to an transnational one. The expansion of the transnationalism affects the identity of the subsequent generations of the immigration giving way to a psychologically deterritorialized social identity, which is an important consideration in the study of subsequent generations of the immigration. This study examined the Korean immigration history and the current status of the Korean community in Spain since the 1960s. The early immigrants like fishing vessel crew members, instructors of Taekwondo, chicken sexers who, despite the limits of foreigners in Spain, went to find out the source of life with no hesitation, overcame the difficulties of the early settlers and finally managed to achieve local success. Current history of immigration that began in the mid-1960s went through the maturity during the 1970s and 80s and the Koreans in Spain these days, who have undergone differentiation in the occupational structure because of the crisis of pelagic fisheries, face new challenges due to changes in the environment of the country they reside. The Korean community is regarded as an 'exemplary minority group (Model Minority)' even though it is a minority group in number. Now that the interest for overseas Koreans is higher than ever at home and abroad, due to the economic growth of the Republic of Korea, the spread of its cultural influence -the Korean Wave as proof-, and the overseas Koreans suffrage conducted, the research of the Korean residents in Spain will be important as an advanced research of an unexplored field, as well as an opportunity to broaden the horizons of the existing study area that has mainly dealt with major regions only.