• 한국환경과학회지
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• 제30권9호
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• pp.727-739
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• 2021

Measurements on mass size distribution of roadside aerosols were obtained in downtown Jeju City from July 2018 to May 2020 using an 8-stage cascade impactor sampler and the compositions of aerosols were analyzed. The mass size distribution of total aerosols was bimodal with aerosols existing in both the fine and coarse modes. The mass size distributions of Na⁺, Mg²⁺, Ca²⁺, Cl^-, NH₄⁺ and SO₄^2- were unimodal, whereas that of K⁺ was bimodal. For NO₃^-, the size distribution in winter and spring was bimodal with the peaks in both fine and coarse modes, whereas for summer and autumn the distribution was unimodal with a peak in the coarse mode. NH₄⁺ was found to co-exist with SO₄^2- in the fine mode with an average molar ratio of [NH₄⁺]/[SO₄^2-] equal to 2.05. Good correlation was observed between NO₃^- and NH₄⁺ in the fine mode particles in spring and winter. Based on the value of the marine enrichment factor for Cl^-, Mg²⁺, K⁺, Ca²⁺ and SO₄^2-, it may be inferred that a major part of the roadside aerosols in downtown Jeju City was largely contributed by terrigenous sources, although the influence of sea salt was normally present.

• 한국조경학회지
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• 제26권4호
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• pp.105-112
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• 1999

Landcover change is an important factor that changes structure and function of regional ecosystem. As the rise of concern on environment quality, many studies are trying to quantify and evaluate the landsacpe in recent days. In this study, using landscape indices with RS(Remote Sensing) and GIS(Geographic Information System) technology, spatio-temporal variations of areas and distribution of forest patches were examined in the Chonan from 1985 to 1996. Fragstats 2.0 was employed to analyze and compute 31 landscape indices from 52 landcover maps. A result of this study showed that area of forest and paddy decreased as a result of urban sprawl. Especially from 1993 to 1996, the change of land use progressed rapidly because of merging a city and a country in Chonan. The size of patch in forest had been smaller and irregular form, heterogeneity of size of forest patches within sub-basin increased, and variety of patch types around forest patches increased from 1985 to 1996.

• Structural Monitoring and Maintenance
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• 제9권3호
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• pp.221-235
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• 2022

Among nondestructive damage detection methods, impedance-based methods have been recognized as an effective technique for damage identification in many kinds of structures. This paper proposes a method to detect cracks in metal structures by combining electro-mechanical impedance (EMI) responses and artificial neural networks (ANN). Firstly, the theories of EMI responses and impedance-based damage detection methods are described. Secondly, the reliability of numerical simulations for impedance responses is demonstrated by comparing to pre-published results for an aluminum beam. Thirdly, the proposed method is used to detect cracks in the beam. The RMSD (root mean square deviation) index is used to alarm the occurrence of the cracks, and the multi-layer perceptron (MLP) ANN is employed to identify the location and size of the cracks. The selection of the effective frequency range is also investigated. The analysis results reveal that the proposed method accurately detects the cracks' occurrence, location, and size in metal structures.

• Asian Journal of Atmospheric Environment
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• 제4권1호
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• pp.9-19
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• 2010

The size distribution of airborne particulate matter (PM) and the concentrations of associated metallic elements were investigated in a busy urban region of a typical Korean industrial city. The PM concentrations measured during the spring, except for those in the size range of 1.1 to 2.1 ${\mu}m$, were slightly higher than the PM concentrations in the summer. Coarse particles contributed greatly to the variation in PM concentrations in the spring, while fine and submicron particles contributed largely to the variation in PM concentrations in the summer. The difference in size modes of the PM concentrations between spring and summer may be explained by the Asian dust effect and its accompanying wind direction and speed. Extremely high enrichment factors (EFs) values (6,971 to 60,966) for all of the size distributions in PM were identified for cadmium (Cd). High EFs values (12 to 907) were also identified for other heavy metals including Cr, Cu, Ni, Pb, Zn and Mn. Low EF values (0.29 to 8.61) were identified for Ca, K, Mg and Na. These results support the common hypothesis that most heavy metals in ambient PM have anthropogenic sources and most light metals have crustal sources. The results of principal components analyses and cluster analyses for heavy metals indicate that the principal sources of PM and metals were emissions from non-ferrous metal smelters, oil combustion, incinerators, vehicular traffic and road dust.

• Ocean Systems Engineering
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• 제12권4호
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• pp.403-411
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• 2022

Annually, about 48-60% of sediment discharge of the Mekong River is delivered near the mouths of the Mekong River branches which is mostly coinciding with the southwest (SW) monsoon. This sediment budget in turn will be southwestwardly transported along the coast of the Mekong Delta (MD) during the northeast (NE) monsoon. Analysis of monsoonal changes in grain-size distribution (GSD) of surface sediment contributes to a better understanding of erosion and deposition processes along the MD. This study aims to figure out changes in GSD and sediment textures along the MD between SW and NE monsoons based on 183 surficial sediment samples collected along the MD during two field surveys carried-out in October 2016 and February-March 2017. Compared to the GSD during the SW and NE monsoon, the GSD along the MD changed significantly, especially in the estuary areas and along the coast of Bac Lieu and Ganh Hao. Whereas, in the west coast of the MD, GSD seem no changes between the two seasons. These changes in seabed sediment suggest that sediment with grain-sizes ranging from silt to fine sand can be transported during only a NE season.

• 한국조경학회지
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• 제24권3호
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• pp.164-188
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• 1996

We discussed the formative nature of a city square reffered to be the frame of creating environment in the this study. We raised a question that the place, the size and the form of a city square are out of harmony with a surrounding environmental condition, and examined the functional effect and the formate value of a sunken square at the same time. We got hold of the special shape and the specific character, the distinctive structure, and the influence of the minute temperature of a cuty aquare, and showed the improved direction how to make them better focusing on the target square of a cosmopolitan city of Seoul. Finally, to correct the above-mentioned problems, we emphasized the our traditional city square which is reffered to have a peculiar property, and proposed that a public institutuion should develope the city square, and should make an effort to reflect the design based on the scientific experiment.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 춘계학술대회
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• pp.5-8
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• 2004

Domestic city gas is supplying in an about 10 million household on present 34 city gas companies because is begun to supply regularly after two 1980 years middle. But, result that focus on city gas supply spread and stable supply for supply area and neglects about safety problem, hundreds casualties such as Ahyun explosion accident and Deagu city gas explosion accident were reached in situation that occurred large size calamity occurs it is dizzliness. In the case of advanced nation, can see that accomplish system and progress that in technology after experience major accident. Therefore, grasp problem investigating safety actual conditions for city gas institution and study about solvable plan is required this. Also, must guide reform and level elevation of a domestic company safety technology through induction and development of safety technology that is suitable in supply, domestic real condition etc. Must help in power positivity that is full text executing high-quality safety education about step High firing mechanism safety technology than present safety education.

• 통합자연과학논문집
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• 제12권1호
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• pp.24-27
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• 2019

Smart city has effect toward its sustainability. Citizens should be viewed as co-creators of cities, not consumers. From this point of view, citizen responsibility and ethics should be emphasized. Now, Smart cities are becoming more important than ever. From now on, urban development is divided into two major categories. One side is the development based on smart city, and the other is urban development that revives the old city. As the city grows bigger and bigger, many problems arise and there are many problems. This tendency must become stronger in the future. But, Stones shall be dressed to exact size and shapes before being laid. Until now, No attempt has been made to declare about Citizen Spirit in Fourth Industrial Revolution. In the era of the Fourth Industrial Revolution, in order to become a leading country of Smart City, we must first complete the spiritual revolution. From this aspect, this study proposes the "Declaration of the Fourth Industrial Spirit Revolution".

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.732-733
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• 2015

Currently, since the total energy amount has been increased continuously, the effort for energy efficiency of apartment building is necessary. Although the previous studies have been focused on the issue. Almost studies are about the simulation by applying the energy analysis tools and a lack of studies have been conducted the data analysis about real city gas amount of apartment building. Therefore, the objective of this study is to analyze the city gas consumption difference according to the exclusive dwelling in apartment building. To address this issue, the descriptive, correlation, analysis of variance (ANOVA) statistics are used in this study. As a result, in the case of annual total amount, the city gas is increased as the size of the exclusive dwelling area is increased. In the future, the findings of this study can be used as a basic material to develop the prediction model of city gas in apartment building.

• 산업기술연구
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• 제12권
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• pp.3-13
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• 1992

The purpose of this study is to investigate the historical changes in popular house form of chuncheon city. 177 samples of the houses built in the period of 1951~1992 were selected. The house structure, size, equipment system were analyzed as well as material, color and types of roof along the historical development.