• Particle and aerosol research
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• v.17 no.1
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• pp.1-8
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• 2021

The purpose of this study is to assess respirable crystalline silica (RCS) exposure levels in workers who collect and dispose used coal briquette ash (CBA) in sanitation companies that are subcontracted by one medium-sized local government on the collection of municipal household waste (MHW), and to analyze the quartz content in CBA. When the CBA powder that undergone specialized pretreatment in several steps were subjected to mineral identification and quantitative analysis using X-ray diffraction (XRD), it was found that quartz represented 18%, and in addition, mullite, and plagioclase were included. For two CBA collectors, samples were collected by the personal sampling evaluation method. After respirable dust was collected in accordance with the National Institute for Occupational Safety and Health 7500 method, the concentration of quartz was analyzed using XRD. Meanwhile, a portable real-time dust monitor (Sidepak AM520, TSI Inc., USA) was also used to observe the dust exposure level for each time zone and job task. The RCS exposure level of one worker was as high as 0.024 mg/㎥, which was the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV) level. The other worker also exhibited a concentration of 0.013 mg/㎥, which was more than half of TLV. The Sidepak results revealed that the work of collecting CBA and loading it onto a vehicle was hardly exposed to the dust of a significant level. It was found, however, that the work of transferring the collected CBA to a container through a conveyor belt was exposed to a very high average respirable dust concentration of 2.238 mg/㎥. The results of this study confirmed that quartz, which is crystalline silica and a carcinogen, is contained in CBA, one of municipal household waste (MHW), in high concentration. It was also confirmed that workers are exposed to high RCS concentrations while transferring collected CBA into a container. Although each local government in South Korea handles CBA in different ways, it is imperative to investigate the CBA exposure level of sanitation workers and improve their working conditions.

• Journal of the Korean Society for information Management
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• v.38 no.2
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• pp.39-63
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• 2021

This study suggested following specialized strategies to be operated in additionally constructing a library, based on a variety of cultural properties and contents, which exist in Dong-gu, Incheon, and the Dong-gu development zone proposed by 'Dong-gu Master Plan 2022'. First, it attempted to select specialized themes based on local characteristics such as cultural properties and contents by each region, by dividing Dong-gu in Incheon into four areas: culture tourism/theme tourism, historical culture, central commercial and infrastructure industry area. Second, it proposed a specialized theme and strategy for children's library to be completed in 2022 by considering the local characteristics. Third, it also suggested the specialized strategy which the representative library should pursue, by considering the social characteristics of Dong-gu.

• Steel and Composite Structures
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• v.43 no.3
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• pp.327-340
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• 2022

A vast amount of experimental and analytical research has been conducted related to the seismic behavior and performance of concrete filled steel tubular (CFT) columns. This research has resulted in a wealth of information on the component behavior. However, analytical and experimental data for structural systems with CFT columns is limited, and the well-known behavior of steel or concrete structures is assumed valid for designing these systems. This paper presents the development of an analytical model for nonlinear analysis of composite moment resisting frame (CFT-MRF) systems with CFT columns and steel wide-flange (WF) beams under seismic loading. The model integrates component models for steel WF beams, CFT columns, connections between CFT columns and WF beams, and CFT panel zones. These component models account for nonlinear behavior due to steel yielding and local buckling in the beams and columns, concrete cracking and crushing in the columns, and yielding of panel zones and connections. Component tests were used to validate the component models. The model for a CFT-MRF considers second order geometric effects from the gravity load bearing system using a lean-on column. The experimental results from the testing of a four-story CFT-MRF test structure are used as a benchmark to validate the modeling procedure. An analytical model of the test structure was created using the modeling procedure and imposed-displacement analyses were used to reproduce the tests with the analytical model of the test structure. Good agreement was found at the global and local level. The model reproduced reasonably well the story shear-story drift response as well as the column, beam and connection moment-rotation response, but overpredicted the inelastic deformation of the panel zone.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.637-644
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• 2022

Loess soils are unsaturated and widely distributed in the northwest zone in China. Many steep slope of unsaturated are observed are observed to be naturally stable. However, a low factor of safety (FoS) for these slopes would be computed from the slope stability analysis following local code practices. It seems that the analyzed results following the local code practices do not agree with the real condition as observed in the field. It is commonly known that soil suction plays an important role in slope stability due to a higher shear strength of the unsaturated soil as compared with that of the saturated soil. In this paper, it is observed that the computed FoS can also be affected by unsaturated unit weight of the soil. However, the effect of unsaturated unit weight of the soil on the slope stability is commonly ignored in engineering practice. Therefore, both the effects of shear strength and unit weight of the unsaturated soil on the computed FoS of unsaturated soil slope are investigated in this study. It is observed that the unsaturated unit weight of soil on the computed FoS increases with increase in slope angle. It is also observed that the effects of the unsaturated shear strength and unsaturated unit weight on the computed FoS are more significant than the effect of 3D analyses compared to the 2D analyses on the FoS.

• Journal of Environmental Science International
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• v.33 no.2
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• pp.161-168
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• 2024

This study was conducted to identify the pollutants generated by the fuel complex and to determine the health effects of the surrounding residents. In addition, based on the results of epidemiological surveys and health impact surveys of local residents, we analyze the distribution of patient groups and exposure characteristics according to the distance from the fuel complex boundary. Samples were collected from the briquette plant within the fuel complex and analyzed by SEM-EDXA, X-ray Fluorescence Spectrometer, and ICP. In addition, the distribution of patients and exposure characteristics were analyzed according to the distance from the fuel complex and yard boundaries. Analysis of briquette samples from the fuel complex showed that the average particle size was 10-30 ㎛, the shape was irregular, and SiO₂ accounted for more than 50%. It is believed that silica, which causes pneumoconiosis, may have been scattered into the air. In particular, there was a large distribution of 5 ㎛ particles that affect respiratory diseases. According to the analysis of the residential addresses and distribution of pneumoconiosis cases, many pneumoconiosis cases were located in the area between 200 and 500 meters from the boundary of the fuel complex. In addition, 28 pneumoconiosis cases were identified as a result of the epidemiological survey and health impact survey at the fuel complex. In detail, there were 8 cases of occupational pneumoconiosis, 6 cases of environmental pneumoconiosis, and 14 cases of occupational and environmental pneumoconiosis. The confirmed pneumoconiosis cases were located between 0.3 and 1.1 kilometers from the fuel complex. It was found that environmental pollutants generated by the fuel complex adversely affect the health of local residents. In particular, there are many cases of pneumoconiosis in the area between 200 and 500 meters from the boundary of the fuel complex, and this distance is considered to be the direct and indirect impact zone of the briquette plant.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.308-317
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• 2009

In the present work, a sensor system composed of an oscillator sensor and a Lamb wave sensor is proposed for the purpose of structural health monitoring. The oscillator sensing system detecting the shift of a structural resonant frequency in proportion to the amount of defects in the structure is a pretty sensitive and simple device, but its detectable range is limited to its local zone. The Lamb wave sensor system, however, is applicable to global detection of the defects. This study is aimed at investigating the feasible combination of the two systems to exploits their merits simultaneously. The scheme to use PZT patches as the oscillator sensor as well as the Lamb wave sensor was proposed to identify the position, length and number of cracks by means of TOF and amplitude of signals, and its validity was confirmed through experiments.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.4 s.111
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• pp.129-142
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• 2005

Korea's pet-related society has been fast growing without the base and preparations of socio-cultural animal welfare. For the most part, Korea's current public parks, in particular, have a space structure in which a lot of friction between the general public who are not fond of dogs and dog owners in public places has been happening unavoidably. A lot of countries that are taking a lead role in animal welfare have built dog parte that the general public and dogs can enjoy together. This research starts with the realization that the concept of 'dog park' needs to be introduced in Korea as more and more Koreans own dogs and other pets. This research aims to provide guidance for dog park planning by drawing a dog park planning model and to promote basics for co-existence of dogs and people in a park and set in place animal welfare early and raise the level of awareness. Total 7 types of dog put 56 planning items including dog zone, dog playground, and agility, and a selective matrix by which it is possible to select essential recommendatory optional items by each type of dog park were drawn in this research. Overall there were the highest needs in separated area for dogs in park. A dog park planning model is designed as follows. 1) To select a dog park type that was introduced. 2) To set up facilities applicable in common and planning items desired in advance by each type. 3) To zone dog park areas by the priority order of planning items that were introduced and to position necessary facilities. 4) To plan program that should be were introduced. A dog park was expected to take some positive roles such as providing opportunities to socialize dogs, activating social communities, more effective park management by participating local community members and so on.

• Journal of the Economic Geographical Society of Korea
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• v.6 no.2
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• pp.403-419
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• 2003

Busan Port, Korea, is a region that must take integrated measures against problems such as the excessive handling of cargo volume, the intensification of port congestion, and the construction of a new port to improve port competitive power. In particular, if a great deal of function in the existing area of Busan Port transfers to a new port, then the problems of port redevelopment will occur as shown in the cases of port developed countries explained hereafter. For Korean ports, port redevelopment in a port zone is implemented for improving the port productivity that targets a local area, but the entire and systematic port redevelopment is not accounted for. Focused on this point, the paper is to present the directions for full-scale port redevelopment of the existing zone of Busan Port. The findings are as follows: First, the region of Busan is divided according to a regional classification that is necessary for port redevelopment. Thereby, 4 zones, total 26 regions of redevelopment were selected. Second, overseas case studies were considered for port redevelopment. From these same studies, appropriate types of port development in Korea were extracted and presented. Third, the status and problems of the selected redevelopment regions were analyzed, and types of port redevelopment were assigned. This study was not applied to the strict evaluation technique by quantitative analysis, but the concept and directions for unprecedented port redevelopment were first defined and established. It is significant to select target areas for redevelopment by regional classification and present directions for developing each region by choosing Busan Port as a real case study. This initiation will greatly contribute to the succeeding study.

• Ocean Systems Engineering
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• v.6 no.1
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• pp.23-60
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• 2016

The major objective of this study was to develop further understanding of 3D nearshore hydrodynamics under a variety of wave and tidal forcing conditions. The main tool used was a comprehensive 3D numerical model - combining the flow module of Delft3D with the WAVE solver of XBeach - of nearshore hydro- and morphodynamics that can simulate flow, sediment transport, and morphological evolution. Surf-swash zone hydrodynamics were modeled using the 3D Navier-Stokes equations, combined with various turbulence models (${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES). Sediment transport and resulting foreshore profile changes were approximated using different sediment transport relations that consider both bed- and suspended-load transport of non-cohesive sediments. The numerical set-up was tested against field data, with good agreement found. Different numerical experiments under a range of bed characteristics and incident wave and tidal conditions were run to test the model's capability to reproduce 3D flow, wave propagation, sediment transport and morphodynamics in the nearshore at the field scale. The results were interpreted according to existing understanding of surf and swash zone processes. Our numerical experiments confirm that the angle between the crest line of the approaching wave and the shoreline defines the direction and strength of the longshore current, while the longshore current velocity varies across the nearshore zone. The model simulates the undertow, hydraulic cell and rip-current patterns generated by radiation stresses and longshore variability in wave heights. Numerical results show that a non-uniform seabed is crucial for generation of rip currents in the nearshore (when bed slope is uniform, rips are not generated). Increasing the wave height increases the peaks of eddy viscosity and TKE (turbulent kinetic energy), while increasing the tidal amplitude reduces these peaks. Wave and tide interaction has most striking effects on the foreshore profile with the formation of the intertidal bar. High values of eddy viscosity, TKE and wave set-up are spread offshore for coarser grain sizes. Beach profile steepness modifies the nearshore circulation pattern, significantly enhancing the vertical component of the flow. The local recirculation within the longshore current in the inshore region causes a transient offshore shift and strengthening of the longshore current. Overall, the analysis shows that, with reasonable hypotheses, it is possible to simulate the nearshore hydrodynamics subjected to oceanic forcing, consistent with existing understanding of this area. Part II of this work presents 3D nearshore morphodynamics induced by the tides and waves.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.841-847
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• 2018

Since global energy consumption and demand for energy have dramatically risen, a focus on environmental problems and sustainability has become more important. Clean and renewable energy sources such as offshore wind power generation have received attention among new renewable energy options as alternative energy resources. Due to maintenance and operational perspectives, offshore wind farms have been planned for installation in many coastal waters. However, development of offshore wind farms faces interference from existing maritime traffic along the planned areas. In order to safely and effectively govern marine traffic in the vicinity of wind farms and inner areas, standard criteria are suggested to allow vessels to sail the internal waters of offshore wind farm areas. Therefore, the purpose of this study is to establish allowable criteria for sailing vessels and safety zones for offshore wind farms by investigating the local regulations of various offshore wind farm cases overseas. The commended inner safety zone of wind farms is proposed to be a distance of 150 % of the rotation diameter of the wind turbine rotor and a distance of 200 m from the outer wind turbine for the outer safety zone. Besides this, the allowable criteria for sailing vessels within a wind farm is proposed to have an air draft of 14.47 m south-west wind farm sea areas for a minimum margin to avoid hull contact through evaluation of the tide and height of a wind turbine. further studies will be needed to establish vessel sailing criteria among adjacent offshore wind farms as well as vessel sailing criteria within a single offshore wind farm.