• Smart Structures and Systems
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• 제31권3호
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• pp.213-227
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• 2023

A passive prismatic-shaped isolation platform (PIP) is proposed to realize enhanced quasi-zero stiffness (QZS) effect. The design concept uses a horizontal spring to produce a tunable negative stiffness and installs oblique springs inside the cells of the prismatic structure to provide a tunable positive stiffness. Therefore, the QZS effect can be achieved by combining the negative stiffness and the positive stiffness. To this aim, firstly, the mathematical modeling and the static analysis are conducted to demonstrate this idea and provide the design basis. Further, with the parametric study and the optimal design of the PIP, the enhanced QZS effect is achieved with widened QZS range and stable property. Moreover, the dynamic analysis is conducted to investigate the vibration isolation performance of the proposed PIP. The analysis results show that the widened QZS property can be achieved with the optimal designed structural parameters, and the proposed PIP has an excellent vibration isolation performance in the ultra-low frequency due to the enlarged QZS range. Compared with the traditional QZS isolator, the PIP shows better performance with a broader isolation frequency range and stable property under the large excitation amplitude.

• 한국환경보건학회지
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• 제49권6호
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• pp.353-361
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• 2023

Background: Noise has been linked to an increased risk of various health issues, including stress, anxiety, insomnia, and cardiovascular disorders. However, research on the relationship between residential traffic noise and mental health in South Korea is limited. Objectives: This study aims to examine the correlation between regional traffic noise levels and mental health using an ecological study design. Methods: In this ecological study, all data were collected from the Korean Statistical Information Service. Traffic noise data in residential areas and the prevalence of mental health indices in 44 cities with noise monitoring stations were obtained. Pearson correlation coefficients were calculated to assess the relationship between regional traffic noise levels and mental health indices. Results: Daytime traffic noise levels were found to have a positive correlation with stress perception (r=0.428, p=0.004) and showed a borderline positive correlation with depressive symptom prevalence (r=0.273, p=0.073). In cities with airports, significant correlations was observed between 24-hour average noise levels and depressive symptoms (r=0.604, p=0.010), whereas this relationship was not observed in cities without airports (r=0.048, p=0.813). Multiple regression analysis, which adjusted for factors such as age, gender ratio, smoking, obesity, unemployment, urban size, and the presence of an airport, confirmed the relationship between 24-hour average noise levels and stress perception (beta=0.287, p=0.024). Conclusions: This study identified correlations between regional traffic noise levels and depressive symptoms or stress perception in adults, with a more pronounced effect in areas with airports. These findings suggest a potential impact of residential traffic noise on mental health, highlighting the importance of preventive measures like noise management in urban planning to promote mental well-being.

• 한국컴퓨터정보학회논문지
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• 제29권1호
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• pp.97-109
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• 2024

이 연구에서는 국내 주요 도시들이 스마트시티 관련 기술을 활용하는 방식을 조사하여 도시의 스마트성과 효율성을 측정하기 위한 핵심성과지표(KPI)를 개발하고, DEA 분석을 통해 도시의 운영 효율성을 파악한 내용을 기반으로 스마트시티 정책 방향을 제안하는 방법론을 제시하고자 한다. CITYkeys의 스마트시티 성과측정 프레임워크를 참고하여 10개의 핵심성과지표(KPI)를 도출하였으며, 각 KPI마다 도시 통계데이터를 투입변수와 산출변수에 할당하고, 15개 도시들을 DMU에 할당하였다. DEA 방법론을 활용하여 도시의 효율성과 규모수익성을 평가하였다. 이를 통하여 도시의 운영효율성을 파악하였다. 최종적으로 각 DMU 간의 운영효율성을 순위화하여 도시별 스마트시티 정책 방향을 제안하였다.

• 한국의류학회지
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• 제48권1호
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• pp.1-19
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• 2024

The purpose of this study is to examine the color characteristics of menswear in different cities, focusing on the Paris, Milan, New York, Tokyo, and London collections. To answer the research question, the sampled colors were classified according to their hues and tones for frequency analysis and cross-analysis. The results are as follows: 'Red', which appeared frequently in the S/S and F/W seasons, was a core color in menswear design, and regardless of the season, 'blackish tones' were most commonly used. The cross-analysis uncovered a significant difference in the trends of hues in the F/W season between the cities. The colors that were more frequently used among the cities were as follows: 'blue-green' in the Paris collection, 'blue' and 'purple' in the Milan collection, 'purple' and 'purple-blue' in the London collection, 'yellow' in the New York collection, and 'red' and 'green' in the Tokyo collection. This study illustrates the significance of the F/W season's use of colors in menswear design and discovered through analysis that hues, rather than tones, were used to express individuality. These results are expected to be used as basic data for the analysis of menswear design trends.

• International Journal of Computer Science & Network Security
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• 제24권5호
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• pp.135-155
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• 2024

Urban public health monitoring in smart cities focuses on the control of conditions and health challenges in urban environments. Considering the rapid spread of diseases and pandemics, it is important for health authorities to trace people carrying the virus. In smart cities, this tracing must be interoperable and intelligent, especially in indoor surfaces characterized by small distances between people. Therefore, to fight pandemics, it is necessary to start with the already-existing digital equipment of the Internet of Things, such as connected objects and smartphones. In this study, the developed system is employed to provide a social IoT network and suggest a strategy which allows reliable traceability without threatening the privacy of users. This IoT-based system allows respecting the social distance between persons sharing public services in smart cities without applying smartphone applications or severe confinement. It also permits a return to normal life in case of viral pandemic and ensures the much-desired balance between economy and health. The present study analyses previous proposed social distance systems then, unlike these studies, suggests an intelligent and distributed IoT based strategy for positioning students. Two scenarios of static and dynamic optimization-based placement of Bluetooth Low Energy devices are proposed and an experimental study shows the contribution and complementarity of the introduced contact tracing strategy with the applications on smartphones.

• 한국환경복원기술학회지
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• 제15권5호
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• pp.165-176
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• 2012

The objective of this study is to set urban ecosystem assessment indicators, assess the status of the urban ecosystems in 31 cities & counties in the capital region and based on which, to examine an improvement plan to resolve problems and raise quality and quantity of urban ecosystems. The study showed that the ecological base of 31 cities & counties was 48% on average, which indicates that their ecological property is the middle class. Their natural-ecological function was 63% and environmental-control function was 25%, showing that environment-control function was poor. Therefore, going forward, urban ecological base should be further improved. When securing an ecological base, creation techniques should be able to further enhance environmental-control function along with natural-ecological function. Also, additional effort should be made to conserve areas with high ecological value as much as possible and increase vegetation vitality by replacing tree species.

• 환경영향평가
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• 제8권2호
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• pp.73-82
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• 1999

This study analyzed the relationship between NDVI(Normalized Difference Vegetation Index) and urban heat island in three cities: Daegu, Kyungju, and Pohang for understanding the degree of nature conservation concentrating in the transition zone of them. Daegu city is the third city in Korea which has a dense population. Kyungju is a traditional city which has good nature. Pohang is an industrial city which has those of characters of Daegu and Kyungju. Landsat 1M data in May 17, 1997 were used for the analysis of heat island. There were about four theoretical models to estimate the surface temperature from TM data: Two-point linear model, Linear regression model, Quadratic regression model, and Cubic regression model. In this study, Linear regression model had been utilized to analyze the urban heat island. On the resultant images, the transition zone of Daegu was urbanized more extremely than those of other two cities. It is thought that the analysis of relationship between NDVI and surface temperature, used in this study, is regarded as one of effective methodologies for urban-environmental detection from satellite imageries.

• 산경연구논집
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• 제11권2호
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• pp.7-16
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• 2020

Purpose: This study explores how demographic transitions with workforce implications taking place in South Korea are affecting the job market, and proposes a novel conceptual model to analyze the increased role that migrant workers will play as the changes progress in the medium term. Research design, data and methodology: A qualitative approach based on the available published data is used in order to create a conceptual model that could be used to determine the order in which job sector strata will be gradually taken over by migrant workers, as the demographic transitions will create an increasing need for workforce reforms. Results: The study determines that migrant workers will replace domestic Korean workers in a stratified manner, initially in rural areas, followed by regional cities and then in the industrial areas on the edges of big cities, and the strata can be analyzed based on a proposed four-category model to determine where the opportunities will open. Conclusion: It is possible to use a conceptual model for this phenomenon. Extensive Government planning is needed to avoid possible social exclusion problems and to determine how to keep the economies of rural and regional Korean cities economically viable while they are becoming increasingly depopulated.

• 전자통신동향분석
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• 제35권6호
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• pp.107-118
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• 2020

The smart city agenda aims to solve various problems arising in cities and promote the welfare and happiness of citizens by utilizing the new technologies of the 4th Industrial Revolution. Smart city policies have been promoted at the national level, but until now, policy implementations have not been effective enough to fundamentally affect citizens. To realize a more realistic and practical smart city, it is necessary to examine the problems occurring in the city in depth and set the direction and tasks of the smart city accordingly. Therefore, this study specifies the issues and problems faced in 12 sectors, including manufacturing, logistics, medical care, and safety. Next, by referring to the existing literature, a future smart city integration model is proposed that can respond to these problems. That is, future smart cities should create detailed services with enhanced efficiency, sustainability, strong risk management, safety, and satisfaction as the main goals. This study is meaningful in that it suggests a vision and tasks of smart cities that can solve problems in various sectors in a form that can be felt by the citizens.

• 한국대기환경학회지
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• 제31권5호
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• pp.437-448
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• 2015

The purpose of this study is to present the source contribution of the fine particles ($PM_{2.5}$) in Chungju area using the CMB (chemical mass balance) method throughout the four seasons in Korea. The Chungju's annual average level of $PM_{2.5}$ was $48.2{\mu}g/m^3$, which exceeded two times higher than standard air quality. Among these particles, the soluble ionic compounds represent 54.2% of fine particle mass. Additionally, the OC concentration in Chungju stayed similar to other domestic cities, while the EC concentration decreased significantly compared to other domestic/international cities. The concentration of sulfur represented the highest composition (8%) among the fine particle compounds. According to the CMB results, the general trend of the $PM_{2.5}$ mass contributors was the following: secondary aerosols (50.5%: ammonium sulfate 26.5% and ammonium nitrate 24.0%) > gasoline vehicle (18.3%) > biomass burning (11.0%) > industrial boiler (6.0%) > diesel vehicles (4.4%). The contribution of the secondary aerosols was the main cause than others. This impact is assumed to be emitted from air pollutants of urban cities or neighbor countries such as China.