• Journal of Mushroom
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• v.20 no.2
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• pp.50-54
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• 2022

This study was conducted to reduce the phenomenon of the biased cultivation of certain mushroom varieties and to develop a competitive variety of Grifola frondosa. We developed the first Korean white commercial mushroom strain, 'Bakyeon', by crossing monokaryons derived from brown strains. We have collected and tested the characteristics of mushrooms from domestic and international genetic resources since 2018. We bred the unique domestic variety, 'Bakyeon', which has the following characteristics. The optimal temperature for mycelial growth was 25~28℃ and the optimal temperature for fruit body growth was 16~18℃. The new variety was similar to the control variety (Daebak) in terms of the pileus, which formed a pine cone shape, and the number of days of cultivation. The yield was 94.1 g/bottle, which was 23% lower than the 108.5 g/bottle yield of the control variety. When incubating the parent and control varieties, the replacement line was clear. Moreover, polymerase chain reaction analysis of mycelial DNA resulted in different band patterns between the parent and control varieties, confirming the hybrid species.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1195-1200
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• 2020

The DOM (: Digital Optical Method), which measures the turbidity of chimney smoke, is a method of calculating the turbidity by setting the area to be measured and the contrast area using a low-cost digital camera that can be easily obtained. However, it is difficult to measure clouds and white smoke in a cloudy sky. In this paper, we develop a background sky type model that can represent the background sky and classify the type by periodically photographing it with a digital camera to solve this problem. In addition, based on the model, we develop a filter to optimize white smoke image and prove its excellence through experiments.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.6
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• pp.74-85
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• 2022

Since the late 1990s, the demand for developing green or reduced-toxic storable propellants has been rising to replace the existing toxic propellants. Most of the research activities are focusing on development of new hypergolic fuels and either white fuming nitric acid or hydrogen peroxide is utilized as an oxidizer. The newly-developed hypergolic fuels are classified as three types, catalytic fuel, reactive fuel, and ionic fuel. In the present study, recent R&D trend of ionic liquid propellants is described and the main results in the previous studies are analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6072-6081
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• 2013

In this study, experiments were performed on air heater samples with three different shapes (chevron, wave and dimple type) to reduce the plumes from cooling towers. The tests were conducted for a range of frontal air velocities of 1~3 m/s and water flow rate 0.19~0.33 kg/s. The results showed that the heat transfer rate increased with increasing air velocity or water flow rate. The air-side pressure drop also increased with increasing air velocity. At the same frontal air velocity, the highest heat transfer rate was obtained for the chevron sample (1.5~1.7 times compared to that of the plate sample), followed by the dimple, wave and plate samples. The heat transfer rate per unit power consumption was also 15% larger than that of the dimple sample. On the other hand, there was no noticeable difference between the other samples.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.8
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• pp.537-544
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• 2017

The purpose of this study is to analyze the flow characteristics when a staggered hollow fiber membrane module is modeled as a porous medium. The pressure-velocity equation was used for modeling the porous medium, using pressure drop data. In terms of flow characteristics, we compared the case of the "porous medium" when the membrane module was modeled as a porous medium with the case of the "membrane module" when considering the original shape of the membrane module. The difference in pressure drop between the "porous medium" and "membrane module" was less than 0.6%. However, the maximum flow velocity and mean turbulent kinetic energy of the "porous medium" were 2.5 and 95 times larger than those of the "membrane module," respectively. Our results indicate that modeling the hollow fiber module as a porous medium is useful for predicting pressure drop, but not sufficient for predicting the maximum flow velocity and mean turbulent kinetic energy.

• Journal of Environmental Science International
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• v.2 no.2
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• pp.153-160
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• 1993

The problem of supply and transport of sediment from a mountainous catchment is very important in explaining dynamic geomorphology and the hydrological cycle. The discharge of suspended sediment is determined by a morphological system. Human interference to environment Is also an important, not negligible factor in sediment production. Moreover, growing concern in recent years for the problems of nonpoint pollution and for the transport of contaminants through terrestrial and aquatic ecosystems has highlighted the role of sediment-associated transport in fluvial systems. This study was conducted in forested and quarried catchments in order to clarify the different discharge process and the mechanism of suspended sediment dynamics for each catchment. As a forested catchment, the Yamaguchi River catchment which drains a $3.12km^2$ area was chosen. On the other hand, the Futagami River basin which is formed by three subbasins (1.07, 1.59 and $1.78km^2$), as a quarried catchment was selected. These catchments are situated to the north and east of Mt. Tsukuba, Ibaraki, Japan. The discharge pattern of suspended sediment from the Futagami River basin is more unstable and irregular than that from forested catchment, the Yamaguchi River catchment. Under the similar rainstorm conditions, suspended sediment concentration from quarried catchment during a rainstorm event increases from 43 to 27,340 mg/l. However, in the case of the forested catchment it changes only from nearly zero to 274 mg/l. Generally, the supply source of suspended sediment is classified into two areas, the in-channel and non-channel source areas. As a result of field measurements, in the case of the forested catchment the in-channel (channel bed, channel bank and channel margin) is the main source area of suspended sediment. On the other hand, remarkable sediment source area on the Quarried catchment is the non-channel that is unvegetated ground.