• Korea journal of population studies
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• v.16 no.2
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• pp.125-139
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• 1993

Korea has successfully achieved a lowered fertility level owing to the strong population control policy and effective family planning program. Along with fertility decline and decreased number of children in family, average number of household members has decreased and nontraditional households such as one person household and households composed of unrelated individuals have prolifirated, even though the absolute number of them are found minimal in Korea. However in recent years several data and survey results suggest that one person households are gradually in the increasing trend. The study aimed at investigating the real state of one person households in Korea and next analyzing the proportional distribution of one person households by a few socioeconomic characteristics, thus providing basic for eatablishing far-singhted population and social welfare policy in the future. Korea has experienced high growth rate of economy through government-led development plans starting from the 1960s. During the past three decades, Korea has shifted from the agricultural state to the industrialized one. In compliance with the economic growth, urbanization and industrialization have brought about rural-to-urban migration and a great bulk of young population migrated to urban areas, who are seeking for educational and job opportunities. Korean society has also been under drastic change in every aspect of life involving norms, tradition, and attitude, etc. Therefore, in spite of the prejudice on 'living alone' still remaining, young people gradually leave parents and home, and further form nontraditional households in urban areas. Current increase in the number of one person households is partly attributable to the increase in high female educational attainment and female participation in economic activities. As the industrial structure in Korea changes from primary into secondary and tertiary industries, job opportunities for service/sales and manufacturing are opened to young female labor force in the process of industrialization. Contrary to the formation of one person households by young people, the aged single households are composed when children in family leave one by one because of marriage, education, employment. In particular, a higher proportion of aged female single households occur in rural areas due to the mortality difference by sex. Based on the data released form the 1990 Population and Housing Census and National Fertility and Family Health Survey in 1985 and 1991, the study tried to examine the state of one person households in Korea. According to Census data, the number of one person households increased to 1, 021, 000 in 1990, comprising 9.0 percent of total households. And the survey reveal that among total 11, 540 households, 8.0 percent, 923 households, are composed of one person households. Generally, the proportion of female single households is greater than that of male ones, and a big proportion of one person households is concentrated in the 25-34 age bracket in urban areas and 65 years and more in rural areas. It is shown than one person householders in urban areas have higher educational attainment with 59.2 percent high schooling and over in 1991, Job seeking proved to be the main reason for leaving home and forming one person households. The number of young female single households with higher education and economic self-reliance are found nil and the study did not allow to analyze the causal realtionship between female education and employment and one person household formation. However more research and deep analysis on the causal facors on one person household formation using statistical method are believed to be necessary.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.33.1-33.1
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• 2015

M85 is a nearby merger remnant galaxy located at the northern part of the Virgo Cluster. Because of its remarkable merging features, it is an interesting object to investigate its formation history. Globular clusters are a great tracer of the formation history of early-type galaxies, so that we study the globular cluster system of M85. It has been already found that there are "intermediate-color" globular clusters as well as blue and red ones based on the photometric survey using CFHT/Megacam. For follow-up research, we obtain the spectra of 21 globular clusters in the central region of M85 using Gemini-N/GMOS. We estimate their ages and metallicities based on the strength of Lick indices. We detect the intermediate-age population (~ 2 Gyr) with solar metallicities, comprising about 50% of the observed globular clusters, as well as old and metal-poor population. It suggests that M85 experienced a major merging event around 2 Gyr ago. We discuss these results regarding to the formation history of M85.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.854-862
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• 2024

Lactobacillus is a commonly used probiotic, and many researchers have focused on its stress response to improve its functionality and survival. However, studies on persister cells, dormant cells that aid bacteria in surviving general stress, have focused on pathogenic bacteria that cause infection, not Lactobacillus. Thus, understanding Lactobacillus persister cells will provide essential clues for understanding how Lactobacillus survives and maintains its function under various environmental conditions. We treated Lactobacillus strains with various antibiotics to determine the conditions required for persister formation using kill curves and transmission electron microscopy. In addition, we observed the resuscitation patterns of persister cells using single-cell analysis. Our results show that Lactobacillus creates a small population of persister cells (0.0001-1% of the bacterial population) in response to beta-lactam antibiotics such as ampicillin and amoxicillin. Moreover, only around 0.5-1% of persister cells are heterogeneously resuscitated by adding fresh media; the characteristics are typical of persister cells. This study provides a method for forming and verifying the persistence of Lactobacillus and demonstrates that antibiotic-induced Lactobacillus persister cells show characteristics of dormancy, sensitivity of antibiotics, same as exponential cells, multi-drug tolerance, and resuscitation, which are characteristics of general persister cells. This study suggests that the mechanisms of formation and resuscitation may vary depending on the characteristics, such as the membrane structure of the bacterial species.

• Korean Journal of Microbiology
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• v.22 no.3
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• pp.191-195
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• 1984

In order to study on the pigment formation of Serratia marcescens, the synthesis of prodigiosin was examined in the presence of a wide range of concentration of detergents. A high elevation of pigment formation was obtained in case of the treatment with SDC and SAP. And the population growth of the bacteria was increased by SDC and SAP, in the concentration of optimum concentration of pigment formation. The alkaline phosphatase activity was also increased in the treatment of SAP, SDC and SDS. The possible mechanism of the detergents on enhancement of pigment formation could be explained by an increase of enzyme activity and membrane transport.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.745-751
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• 2015

The ecological characteristics of Silvetia siliquosa, an endangered brown alga, were investigated from January to December 2013 in Jindo, South Korea. The S. siliquosa population formed widespread patches on natural rock. Receptacles were observed from March to August when seawater temperatures ranged from 8-26℃. A maturation peak was detected in June, when seawater temperatures were 23.4℃. After embryo release, the alga bleached and only the discoidal holdfast remained after August. Developmental initiation of the thallus occurred at temperatures above 8℃, and receptacle formation required approximately 196 degree-days. This is the first study to examine a S. siliquosa population throughout the entire year in a natural habitat.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.10
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• pp.43-50
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• 1997

In this paper, we present a method that can recognize face images by use of a sparse population code that is a learning model about a receptive fields of the simple cells in the primary visual cortex. Twenty front-view facial images form twenty persons were used for the training process, and 200 varied facial images, 20 per person, were used for test. The correct recognition rate was 100% for only the front-view test facial images, which include the images either with spectacles or of various expressions, while it was 90% in average for the total input images that include rotated faces. We analyzed the effect of nonlinear functon that determine the sparseness, and compared recognition rate using the sparese population code with that using eigenvectors (eigenfaces), which is compact code that makes contrast with the sparse population code.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.49-51
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• 1996

New population synthesis models, with the effects of metallicity spread and the horizontal-branch (HB) morphology, provide a way to break the well-known age-metallicity degeneracy in the analysis of the integrated light of elliptical galaxies. Our models suggest that the far- UV radiation of these systems is dominated by a minority population of metal-poor, hot HB stars and their post-HB progeny, while the optical radiation is dominated by a metal-rich population. The systematic variation of UV upturn depends on the contribution from metal-poor, hot HB stars and their post-HB progeny, which in turn depends on the ages of old stellar populations in galaxies. Our result implies a prolonged epoch of galaxy formation, in the sense that more massive galaxies (in denser environments) formed first. Our models also suggest that the strenghth of H$\beta$ index is strongly affected by HB stars, and hence previous age estimation without detailed modeling of the HB would underestimate the ages of ellipticals by $\~$7 Gyr.

• Journal of the Korean Institute of Rural Architecture
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• v.25 no.1
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• pp.9-16
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• 2023

This study is on the formation and the development process of urban space by referring to the literature in Yeosu where is the important location in logistics & transportation and maritime since the Japanese colonial period. There are many factors and results of the development process in Yeosu by the opening port, railroads, loads and industries. The purpose of this study is to understand the characteristics of the formation process of urban space and the characteristics of physical space in Yeosu. The results are as follow; The urban formation and development process in Yeosu where was a small fishing village in the 1910s is largely divided into four processes. Formation: the population increased due to constructions such as of a railroad, a port, and roads and there were many reclamations around the center of the old city center in the Japanese colonial period. Stagnation: There was no urban development due to stagnation, war, and the Yeo-sun Incident. Expand: the industrialization of the Yeocheon Industrial Complex and Gwangyang Steel and other areas around Yeosu led to a surge in Yeosu's population. To cope with this, the city was expanded through three land readjustment projects and the development of large-scale residential complexes. Decline and Remodeling: Yeosu's urban space declined due to the decline of fisheries and the decrease in marine and railway logistics. And the expansion and improvement of the transportation network for hosting the Yeosu World Expo increased the accessibility of the old city center, transforming it into a tourist city using cultural heritage and nature.

• Journal of the Korean earth science society
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• v.35 no.5
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• pp.362-374
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• 2014

This study investigated the initial mass function (IMF) and star formation history of high-mass stars in the Small Magellanic Cloud (SMC) using a population synthesis technique. We used the photometric survey catalog of Lee (2013) as the observable quantities and compare them with those of synthetic populations based on Bayesian inference. For the IMF slope (${\Gamma}$) range of -1.1 to -3.5 with steps of 0.1, five types of star formation models were tested: 1) continuous; 2) single burst at 10 Myr; 3) single burst at 60 Myr; 4) double bursts at those epochs; and 5) a complex hybrid model. In this study, a total of 125 models were tested. Based on the model calculations, it was found that the continuous model could simulate the high-mass stars of the SMC and that its IMF slope was -1.6 which is slightly steeper than Salpeter's IMF, i.e., ${\Gamma}=-1.35$.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.47.2-47.2
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• 2015

At local, galaxy properties are well known to be clearly different in different environments. However, it is still an open question how this environment-dependent trend has been shaped. In this presentation, we will show the results of our investigation about the evolution of star-formation properties of galaxies over a wide redshift range, from z~2 to z~0.5, focusing its dependence on their stellar mass and environment. In the UKIDSS/UDS region, we estimated photometric redshifts and stellar population properties, such as stellar masses and star-formation rates, using the deep optical and near-infrared data available in this field. Then, we identified galaxy cluster candidates at z~0.5-2. Through the analysis and comparison of star-formation (SF) properties of galaxies in clusters and in field, we found interesting results regarding the evolution of SF properties of galaxies: (1) regardless of redshifts, stellar mass is a key parameter controlling quenching of star formation in galaxies; (2) At z<1, environmental effects become important at quenching star formation regardless of stellar mass of galaxies; and (3) However, the result of the environmental quenching is prominent only for low mass galaxies (M* < $10^{10}M_{\odot}$) since the star formation in most of high mass galaxies are already quenched at z > 1.