• Journal of Environmental Science International
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• v.31 no.4
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• pp.329-339
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• 2022

Better understanding the mechanism of black ice occurrence on the road in winter is necessary to reduce the socio-economic damage it causes. In this study, intensive observations of road weather elements and surface information under the influence of synoptic high-pressure patterns (22^nd December, 2020 and 29^th January, and 25^th February, 2021) were carried out using a mobile observation vehicle. We found that temperature and road surface temperature change is significantly influenced by observation time, altitude and structure of the road, surrounding terrain, and traffic volume, especially in tunnels and bridges. In addition, even if the spatial distribution of temperature and road surface temperature for the entire observation route is similar, there is a difference between air and road surface temperatures due to the influence of current weather conditions. The observed road temperature, air temperature and air pressure in Nongong Bridge were significantly different to other fixed road weather observation points.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.99-109
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• 2010

Existing research about automated wafer transport management strategy for semiconductor manufacturing equipment was mainly focused on dispatching rules which is optimized to specific system layout, process environment or transfer patterns. But these methods can cause problem as like requiring additional rules or changing whole transport management strategy when applied to new type of process or system. In addition, a lack of consideration for interconnectedness of the added rules can cause unexpected deadlock. In this study, in order to improve these problems, propose dynamic priority based transfer job decision making algorithm which is applicable with regardless of system lay out and transfer patterns. Also, extra rule handling part proposed to support special transfer requirement which is available without damage to generality for maintaining a consistent scheduling policies and minimize loss of stability due to expansion and lead to improve productivity at the same time. Simulation environment of Twin-slot type semiconductor equipment was built In order to measure performance and examine validity about proposed wafer scheduling algorithm.

• Tribology and Lubricants
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• v.39 no.6
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• pp.250-255
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• 2023

This study applies various surface patterns to minimize material loss in construction equipment that is subject to severe wear due to sand, such as the wear-resistant steel plates of dump trucks or the teeth of excavators. The relationship between surface morphology and wear behavior is investigated using PLA+ polymer to observe the effect of the surface pattern. Five types of samples - smooth, concave, convex, wavy concave, and wavy convex designs - are created using a 3D printer. A wear experiment is conducted for a duration of 3 h using 6.5 kg of abrasive particles. The mass loss of the samples after the experiment is measured to assess the extent of wear. Additionally, the surface morphology of the samples before and after the experiment is analyzed using SEM and confocal microscopy. The study results reveal that the smooth design exhibits the highest wear loss, whereas the concave and wavy concave designs show relatively lower wear loss. The convex and wavy convex designs exhibit varying contact areas with the abrasive particles depending on the surface pattern, resulting in different levels of wear. Furthermore, a comparison between the experimental results and DEM simulations confirms the observed wear trends. This study reveals the relationship between wear damage according to surface pattern shape and is expected to be of substantial help in the analysis of wear and tear on agricultural and heavy equipment.

• Korean journal of applied entomology
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• v.55 no.1
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• pp.45-51
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• 2016

Thirty-seven species of insect pests were surveyed on different area blueberry farms in Jeonbuk province during 2013~2014. Six principal insect pests were found, including Dasineura oxycoccana Johnson, Aphis gossypii Glover, Scirtothrips dorsalis Hood, Ricania sp., Hyphantria cunea Drury, and Latoia consocia Walker. A. gossypii infestation was severe at Iksan and Jinan in middle May. S. dorsalis infestation was severe at all surveyed area in early June, which is the flowering season, and the degree of damage caused was higher in young plants. Ricania sp. was abundant in Jinan and Sunchang, and then appeared to spread across all areas in Jeonbuk. H. cunea had a tendency to concentrate in Iksan during June. Five species of Limacodidae was found, including L. consocia, which was dominant in all areas surveyed, with densities higher then those of the others four species. The degree of damage due to D. oxycoccana was higher in the plain areas (Iksan) than in the middle-mountain areas (Jinan, Sunchang). The rate of damage was 60~78% higher in young plant stages (i.e., those under 3 years of tree age) than in those over 5 years old (30~50%). Moreover, the rate of damage observed in greenhouses was 50~80% higher than that observed in the field (30~40%).

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.355-361
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• 2018

Mold grows more easily when humidity is higher in indoor spaces, and as such is found more often on wetted areas in housing such as walls, toilets, kitchens, and poorly managed spaces. However, there have been few studies that have specifically assessed the level of mold in the indoor spaces of water-damaged housing in the Republic of Korea. We investigated the levels of airborne mold according to the characteristics of water damage types and explored the correlation between the distribution of mold genera and the characteristics of households. Samplings were performed from January 2016 to June 2018 in 97 housing units with water leakage or condensation, or a history of flooding, and in 61 general housing units in the metropolitan and Busan area, respectively. Airborne mold was collected on MEA (Malt extract agar) at flow rate of 100 L/min for 1 min. After collection, the samples were incubated at $25^{\circ}C$ for 120 hours. The cultured samples were counted and corrected using a positive hole conversion table. The samples were then analyzed by single colony culture, DNA extraction, gene amplification, and sequencing. By type of housing, concentrations of airborne mold were highest in flooded housing, followed by water-leaked or highly condensed housings, and then general housing. In more than 50% of water-damaged housing, the level of airborne mold exceeded the guideline of Korea's Ministry of Environment ($500CFU/m^3$). Of particular concern was the fact that the I/O ratio of water-damaged housing was greater than 1, which could indicate that mold damage may occur indoors. The distribution patterns of the fungal species were as follows: Penicillium spp., Cladosporium spp. (14%), Aspergillus spp. (13%) and Alternaria spp. (3%), but significant differences of their levels in indoor spaces were not found. Our findings indicate that high levels of mold damage were found in housing with water damage, and Aspergillus flavus and Penicillium brevicompactum were more dominant in housing with high water activity. Comprehensive management of flooded or water-damaged housing is necessary to reduce fungal exposure.

• Korean Journal of Remote Sensing
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• v.38 no.6_3
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• pp.1805-1815
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• 2022

In 2022, wildfires broke out in Uljin-gun and Samcheok-si, which set the record for the longest forest fire in Korea, but there were no casualties. To protect local residents from wildfires, they must evacuate. Predicting the demand for evacuation in the event of wildfires is essential for the efficiency of disaster management. The purpose of this study is to analyze the human mobility patterns according to the occurrence of Uljin-gun and Samcheok-si wildfires. SKT floating population data was used in this study to analyze the human mobility patterns in Uljin-gun and Samcheok-si. The main findings are as follows. First, while the movement of the resident and visiting population decreased, the movement of the worker population was found to be similar to normal. Second, the resident population of Buk-myeon, Uljin-gun moved to the surrounding area to avoid the wildfires. Third, the region is an area judged to be safe from wildfires, and this mobility patterns are related to emergency disaster text messages. This study confirmed human mobility patterns of the population in the area where the wildfires through the floating population data, which is quantitative data. This suggests that it is important to guide residents to shelters through emergency text messages to minimize damage in the event of wildfires.

• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.160-164
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• 2003

Materials processing by ultrashort pulsed laser is actively being applied to micromachining technology due to its advantages with regard to non-thermal machining. In this study, materials processing with ultrashort pulses was studied by using the high repetition rate of a 800 nm Ti:sapphire regenerative amplifier. This revealed that the highly precise micromachining of metallic thin film and bulk glass with a minimal heat affected zone (HAZ) could be obtained by using near damage threshold energy. Grooves with diffraction limited sub-micrometer width were obtained with widths of 620 nm on Cr thin film and 800 nm on a soda-lime glass substrate. The machined patterns were investigated through SEM images. We also phenomenologically examined the influence of variations of parameters and proposed the optimal process conditions for microfabrication.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.433-436
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• 2009

This study is concerned with an effect of frictional condition in a forward/backward combined extrusion process. Generally, the material flow of the billet is influenced by the corners of the die cavity, the ratio in reduction in area, and thickness ratio of backward can thickness to forward can thickness. In addition, the frictional condition in contact area between the billet and the punch/die also affect the material flow. This paper investigated the effect of frictional condition for variable friction factors. The FEM simulation has been carried out in order to examine the effect of frictional condition. Deformation patterns and flow characteristics were examined in terms of design parameters such as extruded length ratio etc. Die pressure exerted on the die-workpiece interface is calculated by the simulation results and analyzed for safe tooling. Therefore the numerical simulation works provide a combined extrusion process of stable cold forging process planning to avoid the severe damage on the tool.

• The KSFM Journal of Fluid Machinery
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• v.17 no.5
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• pp.72-77
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• 2014

Because of overload working condition of sintering cooler, the cooler fan often suffers the break or damage of rotor blade and fixing shaft. Therefore, internal flow characteristics of a steelworks sintering cooler fan by the duct shape of the cooler fan outlet, such as duct outlet opening ratio, duct height and dividing wall shape on the duct outlet flow pattern are examined in detail. The results show that relatively short duct wall height and attachment of dividing wall shape improves flow patterns considerably.

• International Journal of Safety
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• v.8 no.1
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• pp.1-5
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• 2009

The CFRP composite has unique properties that offer high strength and stiffness, even though it has light weight. Therefore it can be used in many industrial applications. When mechanical fasteners are used for joining composites, high stress concentrations appear near the edge of holes prepared for accommodating structural bolts and rivets. This presence of high stress concentrations can be a source of damage. The aim of this work is to evaluate fracture behavior and patterns of plain woven CFRP with circular hole and repairing patch element. The maximum strength and pattern for the plain woven carbon composite specimen with the repaired circular hole were examined. From the results, we show that repairing of the CFRP composite specimen with ($\pi$) 3~5 mm of circular hole diameter results in load rising effect and the repairing is more effective as bigger hole specimen.