• Journal of Korean Society of Rural Planning
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• v.27 no.1
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• pp.103-116
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• 2021

The purpose of this study is to analyze and diagnose the actual state of extinction risk in rural villages by analyzing time series population characteristics and extinction risk index of rural villages(Haengjeong-ri). As a research method, a time series analysis was performed on the 'population over 65' and the 'female population aged 20 to 39' related to the local extinction index. In addition, the disappearance of Haengjeong-ri village was analyzed using the existing local extinction index. For the study, Haengjeong-ri village-level GIS spatial data was constructed, and population attribute data in 2010, 2015, and 2020 were constructed. In order to derive implications, the change of the 'high risk of extinction 'village in the 2020 local extinction index, the distribution of the population of 'high risk of extinction' villages by three years, the population analysis of 'high risk of extinction' villages continuously from 2010 to 2020, and 'high risk of extinction' An analysis of the increase and decrease of the population of the village and the change of the local extinction index of Haengjeong-ri, where the city, county, and towns are located were analyzed. As a result of the analysis of this study, it was found that the number of villages with an aging of more than 50% increased by 2 to 3 times over 10 years. As a result of the analysis of the local extinction index, in 2010, the southwestern and central regions of South Chungcheongnam-do were high-risk extinction areas, but in 2020, all cities except Cheonan and Asan were converted to high risk extinction areas. Research has shown that Chungnam is facing a serious aging and village extinction crisis, and since the disappearance of villages gradually spreads, an initial response policy is needed. This result will be the same not only in Chungcheongnam-do but also in other rural villages. Therefore, in the case of rural villages, it is necessary to analyze and diagnose the Haengjeong-ri village unit, not the Eup-Myeon unit, and a response policy through diagnosis must be prepared urgently.

• Journal of Korean Society of Rural Planning
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• v.29 no.3
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• pp.15-24
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• 2023

The sense of crisis regarding regional extinction due to low birth rates and an aging population is expanding. Generally, the local extinction index is used to analyze local extinction. However, it is challenging to diagnose the actual situation of village extinction risk in rural areas, even though the regional extinction index can be analyzed in units such as Si-Gun-Gu and Eup-Myeon-Dong. This difficulty arises because the regional extinction index solely relies on natural population growth indicators (elderly population and female population aged 20-39). Therefore, the purpose of this study is to develop a village extinction index that can identify the disappearance of rural villages. Additionally, the aim is to apply the developed indicators to the village (administrative ri) spatial unit. The existing regional extinction index used only mortality-related indicators as factors for natural population decline and fertility-related indicators as factors for natural population growth. However, the developed village extinction index included not only the factors of natural population change but also incorporated social population growth factors and factors related to the pace of village extinction. This is the key difference between the developed village extinction index and the existing regional extinction index. In this study, the indicators of "total population," "number of young women aged 20-44," "number of elderly population aged 70 or older," and "number of incoming population" were selected to develop a village extinction index. The village extinction index was developed by incorporating both natural population growth indicators and social population growth indicators. The developed village extinction index was applied to administrative villages. This research is expected to provide a more accurate understanding of the current state of rural villages facing extinction.

• Health Policy and Management
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• v.31 no.3
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• pp.301-311
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• 2021

Background: This study purposed to analyze the relationship between the local extinction index and medical service uses of chronic diseases. The local extinction index is an indicator of the demographic structure and population aging of the region. Methods: The 2014-2018 statistics of National Health Insurance Corporation and Korean Statistical Information Service data were used for the analysis. First, descriptive statistics were used to analyze the general status of research variables. Second, a panel analysis was performed to analyze the relationship between the local extinction index and medical service uses of chronic diseases (hypertension, diabetes mellitus, periodontal disease, arthritis, mental health, epidemic disease, liver disease). Medical service uses were measured by the number of visits/inpatient days and medical charges of seven chronic diseases. Results: Panel analysis results showed that higher local extinction risks (meaning lower local extinction index) had a positive relationship with the number of visits/inpatient days and medical charges of chronic diseases. But the relationships were varied when the seven chronic diseases were analyzed separately. Conclusion: This study showed a significant relationship between the local demographic structure and medical service uses of chronic disease. Analyzing the local demographic structure will be an essential prerequisite step for implementing appropriate regional health care policies.

• Health Policy and Management
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• v.33 no.3
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• pp.253-263
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• 2023

Background: The purpose of this study was to explore the relationship between the local extinction index and total medical service utilization. Methods: A fixed effects model in panel analysis was performed for the 228 administrative districts in Korea. The statistical yearbook on the usage of medical services by region and Korean Statistical Information Service data were used from 2010 to 2019 for analysis. Medical service utilization was represented by the number of visits day, the number of inpatient days, and medical charges. Control variables were selected by using an Anderson model. The local extinction index was calculated using resident registration population data. Results: Descriptive statistics showed that the number of areas at risk of extinction increased from 61 to 95 for the study years. In addition, the number of visits, the number of inpatient days, and medical charges all increased during the study years. After controlling for variables affecting medical service utilization and doing a panel fixed effects model, the result suggested that a one-step increase in the local extinction index was significantly associated with a 12.29% decrease in medical charges of inpatients, a 7.33% decrease in medical charge of outpatient, a 5.21% decrease in the number of inpatient day, and a 5.54% decrease in the number of visits day. Conclusion: This study showed that the higher the region's extinction risks, the higher the region's total medical service utilization. The results of this study suggested that there was a disparity in medical service utilization between areas at risk of extinction and areas not at risk of extinction, so measures should be taken to address this disparity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1982-1988
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• 1995

Methane/Air premixed flames are studied numerically, using a detailed chemical model, to investigate the flame strech effects on the extinction in a counterflow. The finite difference method, time integration and modified Newton iteration are used, and adaptive grid technique and grid smoothing have been employed to adjust the grid system according to the spatial steepness of the solution profiles. Results show that the flame stretch, or the conventional nondimensionalized stretch having the tangential flow characteristics of the stretched flame alone cannot adequately describes the extinction phenomena. On the other hand, the local flame stretch having both the normal and tangential flow characteristics of the stretched flame can give a proper explanation to the extinction of the symmetric planar premixed flames stabilized in a counter flow. The extinction condition were found to be a constant local stretch regardless of the equivalence ratio.

• Journal of the Korean Regional Science Association
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• v.40 no.1
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• pp.37-51
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• 2024

To respond to local extinction, South Korea, under the leadership of the Ministry of the Interior and Safety, identified depopulated areas in 2021 and launched the Local Extinction Response Fund in 2022. However, due to its early stage of implementation, analyzing the characteristics and changes of policy response to local extinction at the central government level remains a challenge. In contrast, Japan, facing similar issues of local extinction as South Korea, has established a robust central government-led response system based on the Regional Revitalization Act and the Comprehensive Strategy and Basic Policy on Community-Population-Job Creation. Hence, this study examines Japan's policy responses to local extinction by analyzing the first and second periods of the Comprehensive Strategy and Basic Policy on Community-Population-Job Creation. For the analysis, topic modeling was employed to enhance text analysis efficiency and accuracy, complemented by expert interviews for validation. The results revealed that the first-period strategy's topics encompassed economy and society, start-up, local government, living condition, service, and industry. Meanwhile, the second-period strategy's topics included resource, the New Normal, woman, digital transformation, industry, region, public-private partnership, and population. The analysis highlights that the policy target, policy direction, and environmental change significantly influenced these policy shifts.

• Journal of Ecology and Environment
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• v.32 no.2
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• pp.103-107
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• 2009

We investigated colonization and extinction patterns in a meta population of the gold-spotted pond frog (Rana planeyi ehoseniea) near the Korea National University of Education, Chungbuk, Korea, by surveying the frogs in the nine occupied habitat patches in the study area four times per breeding season for three years (2006$\sim$2008) and recording whether the patches were occupied by frogs as well as how many frogs were calling in the patches. We then developed five a priori year-specific models using the Akaike Information Criterion (AIC). The models predicted that: 1) probabilities of colonization and local extinction of the frogs were better explained by year-dependent models than by constant models, 2) there are high local extinction and low colonization probabilities, 3) approximately 31% number of patches will be occupied at equilibrium, and 4) that considerable variation in occupation rate should occur over a 30-year period, due to demographic stochasticity (in our model, the occupation rate ranged from 0.222 to 0.889). Our results suggest that colonization is important in this metapopulation system, which is governed by mainly stochastic components, and that more constructive conservation effects are needed to increase local colonization rates.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.125-131
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• 1997

The extinction of premixed flames under the influence of stretch is studied numerically. A wide range of fuel (hydrogen, ethylene, acetylene, methane, propane and methanol) and air mixtures are established in an opposed jet and their flame properties such as flame speed, flame thickness, thermal diffusivity, and stretch rate at extinction are computed. Computations are made using several chemical kinetic mechanism (Smooke, Kee et al. and Peters). The major result is that, in contrast to the various previous claims of extinction Karlovitz number varying over three orders of magnitude, it is found to be constant around two for all of the mixtures tested. That is, premixed flames are extinguished when the physical flow time decreases (due to increased stretch rate) to the point where it approximately equals the chemical reaction time. Here the relevant chemical reaction time is not the one computed using the one-dimensional flame properties as originally suggested in the formulation of Karlovitz number, but rather it is the one obtained using the stretched flame properties which fully reflect the effect of straining on the flame structure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.9 s.240
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• pp.997-1005
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• 2005

The extinction characteristics of low strain rate normal gravity (1-g) nonpremixed methane-air flames were studied numerically and experimentally. A time-dependent axisymmetric two-dimensional (2D) model considering buoyancy effects and radiative heat transfer was developed to capture the structure and extinction limits of 1-g flames. One-dimensional (1D) computations were also conducted to provide information on 0-g flames. A 3-step global reaction mechanism was used in both the 1D and 2D computations to predict the measured extinction limit and flame temperature. A specific maximum heat release rate was introduced to quantify the local flame strength and to elucidate the extinction mechanism. Overall fractional contribution by each term in the energy equation to the heat release was evaluated to investigate the multi-dimensional structure and radiative extinction of 1-g flames. Images of flames were taken for comparison with the model calculation undergoing extinction. The two-dimensional numerical model was validated by comparing flame temperature profiles and extinction limits with experiments and ID computation results. The 2D computations yielded insight into the extinction mode and flame structure of 1-g flames. Two combustion regimes depending on the extinction mode were identified. Lateral heat loss effects and multi-dimensional flame structure were also found. At low strain rates of 1-g flame ('Regime A'), the flame is extinguished from the weak outer flame edge, which is attributed to multi-dimensional flame structure and flow field. At high strain rates, ('Regime B'), the flame extinction initiates near the flame centerline due to an increased diluent concentration in reaction zone, which is the same as the extinction mode of 1D flame. These two extinction modes could be clearly explained with the specific maximum heat release rate.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.66.1-66.1
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• 2021

Extinction curves observed toward individual Active Galactic Nuclei (AGN) usually show a steep rise toward Far-Ultraviolet (FUV) wavelengths and can be described by the Small Magellanic Cloud (SMC)-like dust model. This feature suggests the dominance of small dust grains of size a < 0.1 ㎛ in the local environment of AGN, but the origin of such small grains is unclear. In this paper, we aim to explain this observed feature by applying the RAdiative Torque Disruption (RATD) to model the extinction of AGN radiation from FUV to Mid-Infrared (MIR) wavelengths. We find that in the intense radiation field of AGN, large composite grains of size a > 0.1 ㎛ are significantly disrupted to smaller sizes by RATD up to dRATD > 100 pc in the polar direction and dRATD ~ 10 pc in the torus region. Consequently, optical-MIR extinction decreases, whereas FUV-near-Ultraviolet extinction increases, producing a steep far-UV rise extinction curve. The resulting total-to selective visual extinction ratio thus significantly drops to RV < 3.1 with decreasing distances to AGN center due to the enhancement of small grains. The dependence of RV with the efficiency of RATD will help us to study the dust properties in the AGN environment via photometric observations. In addition, we suggest that the combination of the strength between RATD and other dust destruction mechanisms that are responsible for destroying very small grains of a <0.05 ㎛ is the key for explaining the dichotomy observed "SMC" and "gray" extinction curve toward many AGN.