• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.1
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• pp.37-45
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• 2011

Mandae watershed in Gangwon province has been known as one of soil erosion hot spot watersheds within Hanggang basin. Thus numerous efforts have been made to reduce soil erosion and pollutant loads into receiving watershed. However, proper best management practices have not been suggested because no monitoring flow and water quality data were available. Thus, modeling technique could not be utilized to evaluate water quality issue properly at Mandae watershed to develop and implement the best management practices. In this study, the SWAT model was applied to the Mandae watershed, Gangwon province to evaluate the SWAT prediction ability and water quality improvement with vegetated filter strip (VFS) in this study. The Nash-Sutcliffe model efficiency (NSE) and Coefficient of determination ($R^2$) values for flow simulation were 0.715 and 0.802, respectively, and the NSE and $R^2$ values were 0.903 and 0.920 for T-P simulation indicating the SWAT can be used to simulate flow and T-P with acceptable accuracies. The SWAT model, calibrated for flow and T-P, was used to evaluate water quality improvement with the VFS in agricultural fields. It was found that approximately 56.19 % of T-P could be reduced with vegetated filter strip of 5 m at the edge of agricultural fields within the watershed (34.86 % reduction with VFS of 1m, 48.29 % with VFS of 3 m). As shown in this study, the T-P, which plays key roles in eutrophication in the waterbodies, can be reduced with proper installation of the VFS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2121-2128
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• 2009

The application range of IEEE 802.11 wireless LAN has rapidly expanding from campus, enterprise to the public network of Hot Spot area due to the advantages of easiness of construction, mobility of wireless client station, convenience of usage and so on. However the security of WLAN(Wireless LAN) is vulnerable inherently because of using RF as a medium, and so the dangers of infringement of personal information and inside data of enterprises have increased and wardriving attack searching for security vulnerability in wireless LAN has become more serious especially. In this paper, we find out the overview of various procedures and preparatory stages for wardriving attack against wireless LAN, and propose complementary methods to prevent information infringement accidents from wardriving attack in wireless LAN. For this purpose, we make an equipment which is suitable for wardriving in wireless LAN and show security vulnerability of AP(Access Point) operation in WLAN around Yangjae-Dong in Seoul as a result of using the equipment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3447-3454
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• 2015

There is increasing demand for enterprise smartwork system by a mobile device increases in these days. Therefore, it has been suggested in the technical platform of smartwork system. But,the research of the changeable smartwork system for quick and immediate correspondence of rapidly changing business affairs is insufficient. In this paper, we propose an adaptable mobile service architecture that can be based on the construction of flexible mobile smartwork system. This adaptable mobile service architecture is possible to dynamic service connecting the adaptable service in an existing smartwork system, and the core elements of the adaptable mobile service architecture propose 'Adaptable Service Manager', 'HotSpot', and 'Configurator'. We propose the dyanmic service processs that based on These core elements. Also, we verify the feasibility through case study that develop the project management mobile service that is usable in business of enterprise. Thus, this research provides the adaptable mobile service architecture that can provide the dynamic mobile service beyond the static mobile service of the existing smartwork system for the various change business of enterprise.

• Steel and Composite Structures
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• v.36 no.1
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• pp.75-86
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• 2020

The grid structures with welded hollow spherical joint (WHSJ) have gained increasing popularity for use in industrial buildings with suspended cranes, and usually welded with steel tube (ST). The fatigue performance of steel tube-welded hollow spherical joint (ST-WHSJ) is however not yet well characterized, and there is little research on fatigue life prediction methods of ST-WHSJ. In this study, based on previous fatigue tests, three series of specimen fatigue data with different design parameters and stress ratios were compared, and two fatigue failure modes were revealed: failure at the weld toe of the ST and the WHSJ respectively. Then, S-N curves of nominal stress were uniformed. Furthermore, a finite element model (FEM) was validated by static test, and was introduced to assess fatigue behavior with the hot spot stress method (HSSM) and the effective notch stress method (ENSM). Both methods could provide conservative predictions, and these two methods had similar results. However, ENSM, especially when using von Mises stress, had a better fit for the series with a non- positive stress ratio. After including the welding residual stress and mean stress, analyses with the local stress method (LSM) and the critical distance method (CDM, including point method and line method) were carried out. It could be seen that the point method of CDM led to more accurate predictions than LSM, and was recommended for series with positive stress ratios.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.2
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• pp.135-143
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• 2016

In this study, an embedded system composed of equipment setting, block importing, scenario setting and output reporting is developed in multi-body dynamics program, ADAMS, for conducting dynamic structural analysis of block lifting process. First, equipment used for block lifting process is set in the simulation environment and the shapes and functions of two lifting beams, and six block loaders are provided as the equipment. Second, the modal analysis result of the lifting block is imported from the static structural analysis system, NASTRAN. Third, the lifting scenarios, such as hoisting, waiting, trolley moving, and wire connecting, are set in the system. Finally, output results in the forms of plots, texts and tables, are reported after the dynamic structural analysis. The test examples conducted in a shipyard are applied into the developed system in various condition and scenarios. The loads at the lug points, the stress contours, and the hot spot tables of the developed system are compared with the result of the static analysis system.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.682-689
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• 2019

This study aims to spatialize the gap between obesity levels through the body mass index, an objective indicator of the level of health among vulnerable people. Thus, areas where the BMI showed cluster patterns with spatial high and low values were extracted and the characteristics of the region were analyzed. The analysis showed that the I statistics for the obesity rate were 0.07 and the z-score was 4.39, confirming spatial autocorrelation. For z-score, it was much larger than the maximum threshold of 2.57. This means that the rate of obesity among the socially vulnerable is regional, and this gap is spatially significant. The results of comparing and analyzing the local environment for these areas of obesity and health care were found to be areas with poor public transportation, less readily available parks, and a concentration of single and multi-generation housing. The analysis results of this study are meaningful in that they provide spatial implications for the health of the socially vulnerable class that previous studies have neglected.

• Particle and aerosol research
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• v.17 no.1
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• pp.9-20
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• 2021

As a large city advanced, the urban environment is becoming an issue. The contribution of vehicle emissions in air pollutants was very high according to the clean air policy support system (CAPSS). In order to improve the air quality in large cities, it is necessary to establish improvement measures by sources, analyzing the air quality of roadside. We divided Bucheon city into 4 regions to investigate the roadside pollutants of each district using the mobile laboratory (ML) and air quality monitoring station (AQMS). ML was used to measure pollutants emitted from vehicles and AQMS data was used as a comparison group of ML data. As a measurement result of pollutants in the roadside, the concentration of air pollutants in industrial & engineering complex area was the highest and concentration of air pollutants in residential & forest complex area was lower. By street, Bucheon-ro, Sinheung-ro, Sosa-ro, and Gyeongin-ro were identified as high concentrations. Therefore, further researches on preparing management measures for roads in the hot-spot area are needed.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.61-71
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• 2022

Pool boiling heat transfer is widely applied in nuclear engineering fields. The influence of heating surface orientation on the pool boiling heat transfer has received extensive attention. In this study, the heating surface with different roughness was adopted to conduct pool boiling experiments at different inclination angles. Based on the boiling curves and bubble images, the effects of inclination angle on the pool boiling heat transfer and critical heat flux were analyzed. When the inclination angle was bigger than 90°, the bubble size increased with the increase of inclination angle. Both the bubble departure frequency and critical heat flux decreased as the inclination angle increased. The existing theoretical models about pool boiling heat transfer and critical heat flux were compared. From the perspective of bubble agitation model and Hot/Dry spot model, the experimental phenomena could be explained reasonably. The enlargement of bubble not only could enhance the agitation of nearby liquid but also would cause the bubble to stay longer on the heating surface. Consequently, the effect of inclination angle on the pool boiling heat transfer was not conspicuous. With the increase of inclination angle, the rewetting of heating surface became much more difficult. It has negative effect on the critical heat flux. This work provides experimental data basis for heat transfer and CHF performance of pool boiling.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.97-109
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• 2022

Multi-dimensional coupling analysis is a research hot spot in nuclear reactor thermal hydraulic study and both the full-scale system transient response and local key three-dimensional thermal hydraulic phenomenon could be obtained simultaneously, which can achieve the balance between efficiency and accuracy in the numerical simulation of nuclear reactor. A one-dimensional to three-dimensional (1D-3D) coupling platform for the nuclear reactor multi-dimensional analysis is developed by XJTU-NuTheL (Nuclear Thermal-hydraulic Laboratory at Xi'an Jiaotong University) based on the CFD code Fluent and system code RELAP5 through the Dynamic Link Library (DLL) technology and Fluent user-defined functions (UDF). In this paper, the International Standard Problem (ISP) No. 43 is selected as the benchmark and the rapid boron dilution transient in the nuclear reactor is studied with the coupling code. The code validation is conducted first and the numerical simulation results show good agreement with the experimental data. The three-dimensional flow and temperature fields in the downcomer are analyzed in detail during the transient scenarios. The strong reverse flow is observed beneath the inlet cold leg, causing the de-borated water slug to mainly diffuse in the circumferential direction. The deviations between the experimental data and the transients predicted by the coupling code are also discussed.

• Journal of Preventive Medicine and Public Health
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• v.55 no.1
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• pp.80-87
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• 2022

Objectives: Dengue remains hyperendemic in Malaysia despite extensive vector control activities. With dynamic changes in land use, urbanisation and population movement, periodic updates on dengue transmission patterns are crucial to ensure the implementation of effective control strategies. We sought to assess shifts in the trends and spatial patterns of dengue in Kelantan, a north-eastern state of Malaysia (5°15'N 102°0'E). Methods: This study incorporated data from the national dengue monitoring system (eDengue system). Confirmed dengue cases registered in Kelantan with disease onset between January 1, 2016 and December 31, 2018 were included in the study. Yearly changes in dengue incidence were mapped by using ArcGIS. Hotspot analysis was performed using Getis-Ord Gi to track changes in the trends of dengue spatial clustering. Results: A total of 10 645 dengue cases were recorded in Kelantan between 2016 and 2018, with an average of 10 dengue cases reported daily (standard deviation, 11.02). Areas with persistently high dengue incidence were seen mainly in the coastal region for the 3-year period. However, the hotspots shifted over time with a gradual dispersion of hotspots to their adjacent districts. Conclusions: A notable shift in the spatial patterns of dengue was observed. We were able to glimpse the shift of dengue from an urban to peri-urban disease with the possible effect of a state-wide population movement that affects dengue transmission.