• The Korean Journal of Ecology
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• v.27 no.6 s.122
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• pp.347-353
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• 2004

This study was carried out to analyze pH, Electrical conductivity(EC), cation and anion on rainfall and throughfall raining at industrial area(Onsan and Nongso of Ulsan city), suburban area(Myeongsek-myeon of Jinju city) and rural area(Haman and Changyoung-gun), and to investigate $SO_2\;and\;NO_2$ concentration in the air of industrial area and rural area, and to survey degree of decline of Pinus thunbergii growing at each area. The rainfall pH was higher than the throughfall pH at the all surveyed areas. The rainfall pH and throughfall pH was $4.76{\sim}5.15\;and\;4.64{\sim}4.98,\;4.95{\sim}5.30\;and\;4.87{\sim}5.13,\;5.29{\sim}5.76\;and\;5.12{\sim}5.73$ at the industrial area, suburban area and rural area, respectively. The EC of rainfall and throughfall was $13.64{\sim}17.22\;and\;41.60{\sim}103.59,\;4.18{\sim}8.65\;and\;17.02{\sim}23.89,\;4.09{\sim}6.65\;and\;13.75{\sim}21.44$ at the industrial area, suburban area and rural area, respectively. Generally EC at the industrial area was higher than those of suburban area and rural area. In the correlation analysis among Degree of decline on Pinus thunbergii and ingredients of rainfall, it showed that there was a negative correlation between Degree of decline and pH. There was a positive correlation between pH and $Cl^-$ respectively.

• Journal of the Korean Institute of Gas
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• v.22 no.1
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• pp.64-77
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• 2018

This paper presents the prediction of the original gas in place(OGIP) by using the material balance method and decline curve analysis method with production history and pressure transient test data for four coalbed methane wells in the Horseshoe Canyon field. In this study, the conventional gas equation and the Jensen and Smith(J&S) equation were used to material balance analysis, and the Arps' empirical correlation and Khaled method were applied to decline curve analysis. From the results, the OGIP estimated from the conventional gas and the J&S method was small in difference as under 12%. Also, in case of decline curve analysis, it was found that the Khaled method has appropriated to calculate the OGIP, because the OGIP was estimated as unlimited value by the Arps' equation from the decline exponent of 1 - 3.5. The OGIP difference between conventional gas method and Khaled method was calculated as 8.67% ~ 31.04%, and those between J&S method and Khaled method was 13.67% ~ 26.49%.

• Membrane Journal
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• v.15 no.1
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• pp.52-61
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• 2005

Permeate flux decline in a microfiltration was analyzed by measuring the permeability of bentonite colloidal solution through polyethylene capillary membranes. The flux decline with time was due to the growth of cake layer on the membrane surface and to the pore blocking by particles. As the time approaches to steady state, the permeate flux is almost controlled by the cake filtration model. Faster flux decline at high trans-membrane pressure was attributed to the formation of denser packed cake layer and pore blocking. The ratio of permeate flux to the initial permeate flux, J/J₁, decreased with increasing the trans-membrane pressure, from 45% for 0.5 kg/sub f//㎠ to 38% for 2.0 kg/sub f//㎠. In comparing the ratio of each fouling component to the total fouling for the 0.5 kg/sub f//㎠ TMP condition, complete blocking was 23.4%, standard blocking was about 14.6% and cake filtration was 62.0%, respectively. Permeate flux through the membrane increases with cross flow velocity, and the effect of the variation of velocity is more significant at 1.0 kg/sub f//㎠ rather than at 2.0 kg/sub f//㎠ of the operation pressure. Permeate flux for the membrane having the average pore diameter of 0.34 ㎛ was higher than that for the membrane of 0.24 ㎛ pore size, with the higher flux with the low concentration of feed. On the operation using the membrane of 0.34 ㎛ pore, the pore blocking in the low concentration of 200 ppm is negligible relative to the pore blocking in the 1000 ppm feed.

• Journal of the Korean Regional Science Association
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• v.35 no.1
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• pp.3-18
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• 2019

Urban sprawl has been criticized due to its negative effects, including the encroachment of farmland and open spaces, the increase in traffic congestion and air pollution, the decline of central city, the decrease in social capital, and the unfairness of tax burdens on infrastructure and public services. This study measures urban sprawl in the capital region of South Korea where the characteristics of urban sprawl have been known to be different from those identified in the U.S. metropolitan areas. In particular, the study examines whether the capital region has experienced the decline of the central city with an expansion of low density residential development in suburban areas. Three measurements, the sprawl index with population density, the ratio of changes in urbanized areas to changes in population, and the population density gradient, were employed to measure urban sprawl, and GIS mapping and descriptive analysis were used to examine the central city decline and the characteristics of development patterns in suburban areas. The results show that the capital region of South Korea is moving to the American style sprawled development with the decline of the central city and an increase of single detached homes in suburban areas, implying that policy makers need to develop growth management strategies to prevent urban sprawl and its negative effects that many U.S. metropolitan areas have suffered from.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.1
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• pp.68-79
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• 2021

The recent occurrence of vacant houses in urban areas is a remarkable social problem. One of the physical declines, the occurrence of vacant houses, accelerates various social and economic declines, such as a decline in population and a slump in the commercial district. Vacant houses have regional characteristics and spatial influence, and it is necessary to approach them locally in order to grasp the exact status of vacant houses. Therefore, in this study, the effect of urban decline on the occurrence of vacant homes was examined by region using global Moran's I and Geographic Weighted Regression(GWR) model. As a result of the analysis, there were spatial autocorrelation and heterogeneity in the occurrence of vacant houses in each eup·myeon·dong, Busan metropolitan city. In addition, there is a difference in the influence of each variable of urban decline on the occurrence of vacant houses, and even the same variable of urban decline has different effects on the occurrence of vacant houses in different regions. Therefore, it is expected that a more efficient vacant home management plan can be presented if the GWR model is used to analyze the coefficient values differentiated by region and categorize the occurrence of vacant houses.

• Journal of The Korean Association For Science Education
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• v.42 no.2
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• pp.215-226
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• 2022

This study analyzed the trends and causes of the decline in Korean students' positive experiences about science (PES). To do this, 4th to 10th grade students were sampled by grade at general elementary, middle, and high schools in Seoul, and then a questionnaire was administered to ask the students about their PES and the causes for their decline. The results of one-way ANOVA for Test for Indicators of Positive Experiences about Science (TIPES) revealed that there were no statistically significant differences according to grade and school level in the overall mean of TIPES scores. However, the results were slightly different for each sub-component. That is, in 'science academic emotion,' the mean of elementary school students was statistically significantly higher than that of middle school students. In addition, the mean of 4th graders was significantly higher than the mean of middle school 1st graders, middle school 3rd graders, and high school 1st graders, respectively. The mean of high school students was statistically significantly higher than that of middle school students in 'science-related career aspiration.' In the 'science-related self-concept', 'science learning motivation,' and 'science-related attitude,' the differences in scores according to grade and school level were not statistically significant. The main causes of the decline in each sub-components of PES were somewhat different depending on the school level. Based on these results, the ways to improve students' PES were sought according to grade and school level.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.95-102
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• 2023

This study aims to empirically verify the moderating effect of population drop on the relationship between demographic changes and crime decline in local cities facing population decline in Korea. The study employs changes in the population of young adults, men, elderly, foreign residents, and population movement as factors of demographic changes, including types of the city as a control variable in the research model. The rate of change in population drop is used as a moderator variable and the rate of change in crime decline as a dependent variable. Data are collected from 155 cities with declining populations from 2010 to 2022 through KOSIS, the National Statistics Portal, and information disclosure requests. Data collected are analyzed using moderated regression analysis. In the first and second stages of the analysis, they show that changes in the population of young adults, population movement, foreign people, population drop, and the type of city affect the change in crime. Moderated regression analysis shows that only the interaction terms among changes in the population of young adults, changes in population movement, and changes in the population of foreigners and the population drop affects change in crime significantly.

• Korean Journal of Psychosomatic Medicine
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• v.25 no.2
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• pp.136-144
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• 2017

Objectives : Cognitive complaints are reported frequently after breast cancer treatments. The causes of cognitive decline are multifactorial, a result of the effect of cancer itself, chemotherapy, and psychological factors such as depression and anxiety. However, cognitive decline does not always correlate with neuropsychological test performance. The purpose of this study was to examine the relationship of subjective cognitive decline with objective measurement and to explore associated factors of cognitive function in breast cancer survivors. Methods : We included 29 breast cancer survivors who complain cognitive decline at least 6 months after treatment and 20 age-matched healthy controls. Neuropsychological tests were performed in all participants. Multivariable regression analysis evaluated associations between neuropsychological test scores and psychological distress including depression and anxiety, also considering age, education, and comorbidity. Results : There were no statistically significant differences in neuropsychological test performances. However, the breast cancer survivors showed a significantly higher depression(p=0.002) and anxiety(p<0.001) than the healthy controls did. Among the cancer survivors, poorer executive function was strongly associated with higher depression(${\beta}=-0.336$, p=0.001) and anxiety(${\beta}=-0.273$, p=0.009), after controlling for age, education, and comorbidity. In addition, poorer attention was also significantly related with depression(${\beta}=-0.375$, p=0.023) and anxiety (${\beta}=-0.404$, p=0.013). Conclusions : The results of this study showed the discrepancies between subjective complaints and objective measures of cognitive function in breast cancer survivors. It suggests that subjective cognitive decline could be indicators of psychological distress such as depression and anxiety.

• Korean Journal of Heritage: History & Science
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• v.48 no.1
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• pp.24-43
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• 2015

This study constitutes an inquiry into the decline of Government Office(官衙) facilities carried out intensively during modern era, focusing on provincial government offices of Jeollabuk-do. There have been several studies of changes in provincial government offices till now, but there have been few studies of government offices of the counties and prefectures(郡縣) during the period of the Japanese Resident-General of Korea and after the National Liberation, temporally and there have still been lacking studies on Jeollabuk-do, spatially. Thus, this study attempts to empirically prove the reasons and the time of the decline of provincial government offices in Jeollabuk-do and the characteristics in the process of decline focusing on modern era. As a result of the study, four factors: demolition, abolition, appropriation and disaster had the most decisive impacts on the decline of government office facilities. Demolition refers to the destruction of government office facilities, and abolition, to the decline and the discontinuation of the operation of the facilities. Appropriation refers to conversion to facilities to meet public functions, and disaster, damage from a typhoon or fire. These factors had already been started from the 1900s, and by the 1930s, most of the government office facilities came to lose their original looks and functions. In the meantime, there was an essential purpose in demolition, the most direct factor in the destruction of the government office facilities in terms of function: that is new construction of public facilities necessary for administration and rule. The existing government office facilities were appropriated, sometimes, but behind that, many cases of demolition of the government office facilities for the new construction of public facilities are found. The appropriation of the government office facilities is divided into educational, administrative, financial and security facilities, and generally, Gaeksa(客舍) and Dongheon(東軒) were used respectively as educational and administrative facilities while their attached facilities were used as financial and public order and security facilities in general. Especially, some government office facilities were utilized as distinctive facilities such as housing or hospital. In the process of appropriation, a lot of modification occurred inside and outside the government office facilities, due to which, the government office facilities gradually declined losing their traditional styles.

• Journal of Life Science
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• v.29 no.6
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• pp.747-753
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• 2019

Cognitive decline is characterized by reduced long-/short-term memory and attention span, and increased depression and anxiety. Such decline is associated with various degenerative brain disorders, especially Alzheimer's disease (AD) and Parkinson's disease (PD). The increases in elderly populations suffering from cognitive decline create social problems and impose economic burdens, and also pose safety threats; all of these problems have been extensively researched over the past several decades. Possible causes of cognitive decline include metabolic and hormone imbalance, infection, medication abuse, and neuronal changes associated with aging. However, no treatment for cognitive decline is available. In neurodegenerative diseases, changes in the gut microbiota and gut metabolites can alter molecular expression and neurobehavioral symptoms. Changes in the gut microbiota affect memory loss in AD via the downregulation of NMDA receptor expression and increased glutamate levels. Furthermore, the use of probiotics resulted in neurological improvement in an AD model. PD and gut microbiota dysbiosis are linked directly. This interrelationship affected the development of constipation, a secondary symptom in PD. In a PD model, the administration of probiotics prevented neuron death by increasing butyrate levels. Dysfunction of the blood-brain barrier (BBB) has been identified in AD and PD. Increased BBB permeability is also associated with gut microbiota dysbiosis, which led to the destruction of microtubules via systemic inflammation. Notably, metabolites of the gut microbiota may trigger either the development or attenuation of neurodegenerative disease. Here, we discuss the correlation between cognitive decline and the gut microbiota.