• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.1-10
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• 2012

The purpose of this study was to promote the utilization of wind velocity of kitchen and bathroom exhaust ducts for wind power generation in high-rise apartments. The research content can be summarized as follows: 1) Nine high-rise apartments were examined for the installation of kitchen and bathroom exhaust ducts located in the pipe shaft (PS) section. After selecting simulation candidates, a simulation was performed with the STAR-CCM+ Ver 5.06 program. 2) Of nine high-rise apartments, seven had kitchen and bathroom exhaust ducts, whose cross section was in the range of $0.16m^2{\sim}0.4m^2$. The area ratio between the exhaust ducts and PS section (cross section of exhaust duct/area of PS section ${\times}$ 100) was on average 3.2%. 3) The simulation results were analyzed. As a result, the smaller cross section kitchen and bathroom exhaust ducts had, the more advantages there were for increasing exhaust wind velocity. If an out air inlet duct is installed to the old kitchen and bathroom exhaust ducts, it will increase exhaust wind velocity by 3.01~3.98m/s and contribute to the proper wind velocity level (3.0m/s). 4) When the simultaneous usage rate between the kitchen and bathroom exhaust fan increased from 20% to 60%, exhaust wind velocity increased. The "entire house holds" condition for exhaust fan operation provided more even exhaust wind velocity than the "some house holds" condition. 5) Exhaust wind velocity increased in the order of amplified (T-3), induced (T-2) and vertical (T-1) top of kitchen and bathroom exhaust ducts. Of them, the amplified type (T-3) was under the least influence of external wind velocity and thus the most proper for kitchen and bathroom exhaust duct tops.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.206-206
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• 2017

Sorghum is a crop with a various plant height depending on the planting density. If the height exceeds 1.8m, which is the harvestable height of the combine, loss is caused by clogging of the installation, entrance of the threshing section and the threshing section. The purpose of this study is to set the planting distance and number of plants per hill suitable for combine harvesting as the plant length does not exceed 1.8m. The experimental variety was Nampungchal. The experiment design was a split-plot design with three replications. The treatments were as follow: Main-plot were 1 and 2 plants as number of plants per hill and sub-plots were $60{\times}20cm$ (practice), $70{\times}15$, 20, 25, 30 cm as planting distance. The amount of nitrogen, phosphate and potassium fertilization were 100, 70, $80kg\;ha^{-1}$. Data were collected: (1) grain yield: weight of grain in $kg\;ha^{-1}$, (2) 1000 grain weight: average weight of 1000 grain, (3) plant height: distance from soil to top of panicle, (4) ear length: distance from top of stem to top of ear in cm, (5) stem diameter: diameter of second internode, (6) tiller number per hill. Analyses of variance were performed using R version 3.3.1(https://www. r- project. org). The Duncan's multiple range test(DMR) was used to separate treatment means at P < 0.05. As number of plants per hill increased, plant height and yield increased and tiller number decreased. As planting distance increased, plant height and yield decreased and tiller number increased. At 1 plant per hill, the plant height did not exceed 1.8m at all planting distance. At 2 plants per hill, the plant height did not exceed 1.8m from the planting distance of $70{\times}25cm$. At 1 plant per hill, the tiller number increased to 0.23, 0.27, 0.60 and 0.70 as the planting distance increased to $70{\times}15$, 20, 25 and 30 cm, respectively. At 2 plants per hill, the tiller number increased to 0.03, 0.03, 0.14 and 0.40 as the planting distance increased to $70{\times}15$, 20, 25 and 30 cm, respectively. At 1 plant per hill, the yield decreased to 6030, 4280, 3400 and $3230kg\;ha^{-1}$ as the planting distance increased. At 2 plant per hill, the yield decreased to 7850, 5770, 5720 and $4960kg\;ha^{-1}$ as the planting distance increased. We recommend that the optimum number of plants per hill and planting distance is 2 and $70{\times}25cm$ suitable for combine harvesting.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.473-483
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• 2014

In this work, the effects of shade combination, shade height and wind regime on greenhouse climate were quantified. A two-dimensional (2-D) computational fluid dynamics (CFD) model was developed based on an 11-span plastic greenhouse in eastern China for wind almost normal to the greenhouse orientation. The model was first validated with air temperature profiles measured in a compartmentalized greenhouse cultivated with mature lettuce (Lactuca sativa L., 'Yang Shan'). Next, the model was employed to investigate the effect of shade combinations on greenhouse microclimate patterns. Simulations showed similar airflow patterns in the greenhouse under different shade combinations. The temperature pattern was a consequence of convection and radiation transfer and was not significantly influenced by shade combination. The use of shade screens reduced air velocity by $0.02-0.20m{\cdot}s^{-1}$, lowered air temperature by $0.2-0.8^{\circ}C$ and raised the humidity level by 0.9-2.0% in the greenhouse. Moreover, it improved the interior climate homogeneity. The assessment of shade performance revealed that the external shade had good cooling and homogeneity performance and thus can be recommended. Furthermore, the effects of external shade height and wind regime on greenhouse climate parameters showed that external shade screens are suitable for installation within 1 m above roof level. They also demonstrated that, under external shade conditions, greenhouse temperature was reduced relative to unshaded conditions by $1.3^{\circ}C$ under a wind speed of $0.5m{\cdot}s^{-1}$, whereas it was reduced by merely $0.5^{\circ}C$ under a wind speed of $2.0m{\cdot}s^{-1}$. Therefore, external shading is more useful during periods of low wind speed.

• Journal of Animal Environmental Science
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• v.18 no.3
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• pp.157-164
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• 2012

This study was conducted to investigate the effect of different farrowing space, narrow and wide, on the sow performances and piglet growth performances. The $1.5m^2$ of narrow farrowing space was determined as the size of farrowing crate. The $3.0m^2$ of wide space for farrowing sow was the same of farrowing pen to allow the behavior freedom of sow. Baby piglets in the wide farrowing space was protected from crushing of sow by installation of safety bar. The pregnant sows used in this study were stall-housed during gestation and moved to each farrowing spaces on 8 d before parturition. Feed intake, backfat thickness and body condition score of sow were not affected by both farrowing spaces. However, the changes in backfat thickness and body condition score between farrowing and weaning in wide farrowing space were lower (p<0.05) than in narrow farrowing space. The return to estrus of sow was remarkably decreased in wide farrowing space compared to sows in narrow farrowing space. The lower number of stillbirth and higher mortality of piglets were observed in wide farrowing space. From the results, although wide farrowing space could be practically acceptable in terms of sow performances, possible cause of mortality of piglets should be scrutinized through observation of piglet and sow behaviors.

• Journal of the Korean Wood Science and Technology
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• v.40 no.6
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• pp.397-405
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• 2012

Installation of deck has been on the rise in Korea recently, but there is little of research on the safety of deck. One of the major factors affecting maneuverability of a pedestrian is frictional force between an outsole of shoe and a surface of the deck. The frictional force is influenced by many factors such as raw material variance of deck, surface convex shape of deck, outsole patterns of shoes, and moist condition of contact surface between deck and shoes. This study focused on evaluating the effect of these factors on the frictional force. Two kinds of deck, which were made of natural wood and wood plastic composite, were used in this study. The surface convex patterns of deck were classified to single nonslip (longitudinal groove processing) and double nonslip (longitudinal and transverse groove processing). Two kinds of shoe outsole patterns, W-shape and rectangle-shape, were used in the tests. Also, the friction tests were carried out at dried surface conditions and water-adsorbed surface condition.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.271-278
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• 2014

In spite of that stop line and crosswalk should be aware of the most basic objects in transportation system, its features extracted are very limited. In addition to image-based recognition technology, laser and RF, GPS/INS recognition technology, it is difficult to recognize. For this reason, the limited research in this area has been done. In this paper, the algorithm to recognize the stop line and crosswalk is designed and implemented using image-based recognition technology with the images input through a vision sensor. This algorithm consists of three functions.; One is to select the area, in advance, needed for feature extraction in order to speed up the data processing, 'Region of Interest', another is to process the images only that white color is detected more than a certain proportion in order to remove the unnecessary operation, 'Color Pattern Inspection', the other is 'Feature Extraction and Recognition', which is to extract the edge features and compare this to the previously-modeled one to identify the stop line and crosswalk. For this, especially by using case based feature comparison algorithm, it can identify either both stop line and crosswalk exist or just one exists. Also the proposed algorithm is to develop existing researches by comparing and analysing effect of in-vehicle camera installation and changes in recognition rate of distance estimation and various constraints such as backlight and shadow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.778-784
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• 2017

In this paper, we propose wired and wireless distributed control systems designed to improve the freight logistics efficiency and verify wired distributed control systems. The verification condition required that 50 cargo vehicles be connected and operated to travel 21 km from Busan Sinhang station to Jinlye Station at an average speed of about 100km/h. The verification results show that the traction output and braking output of the control and controlled cars are dispersed by the wired distributed control system. The application is expected to more than double the efficiency of the logistics compared to the existing freight transportation system. However, in the case of the wired distributed control system, cable installation and maintenance are difficult, and it is impossible to change the combination of freight vehicles. Through the verification of the wired distributed control system, the applicability of distributed control systems to freight vehicles in Korea was confirmed and the system was further developed to produce a wireless distributed control system. In order to apply the wireless distributed control system, a propagation environment analysis for the ISM band was performed in the testbed and, as a result, it was confirmed that Wifi technology using the ISM band could be utilized. In order to use the WDP (Wireless Distributed Power) devices newly installed in the target vehicles, the transmission / reception control signals associated with the propulsion / braking / total control devices are defined. In the case of wireless distributed control systems, the convenience of their application and operation is guaranteed, but reliability and emergency safety measures should because of the dependence of the control of the vehicle on radio signals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.39-48
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• 2020

Since the fire accident of ESS (energy storage system) occurred at Gochang KEPCO Power Testing Center in August 2017, 29 fire cases with significant property losses have occurred in Korea. Although the cause of fire accidents have not been identified precisely, it should be considered battery and PCS (power conditioning system) as well as unbalance issues in the distribution system. In particular, circulating currents in a neutral line of a grid-connected transformer, which can affect a magnetized current, may have a negative effect on the ESS with unintentional core saturation and surge voltages at the secondary side of the transformer. Therefore, this paper proposes the modeling of the distribution system, which was composed of a substation, grid-connected transformer, and customer loads using PSCAD/EMTDC S/W, to analyze the phenomena of circulating current and surge voltages of the transformer with unbalanced currents in the distribution system. This paper presents a countermeasure for a circulating current with the installation of NGR (neutral grounding resistor) in grid-connected transformer. From the simulation results, it is clear that exceeding the circulating current and surge voltage at the secondary side of the transformer can be one of the causes of fire accidents.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.2
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• pp.175-187
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• 2014

The subways play an important part in serious traffic problems. Almost seven million citizens a day are using subways as a means of traffic communication in the Seoul metropolitan city in 2012. However, the subway system is a semi-closed environment, so many serious problems occurred in subway stations and injured passengers' health. Platform screen doors (PSD) are expected to prevent negligent accident such as injury or death from falling and improve the air quality of the subway station. Installation of PSD at stations in Seoul metropolitan subway had been completed in December 2009. Consequently, the underground transportation system became a closed environment, so the air quality has improved the platforms, but it has deteriorated in the tunnels. Especially, the subway cabin has many doors, and the doors are frequently opened and closed. For this reason, the effect of door opening on subway cabin, dust flow inside the subway cabin. In this process, the maintenance work may influence the health of people who work underground, as well as that of subway users (passengers). In this study, we measured air quality inside and outside of the subway cabin line 2 in Seoul, Korea. This study focused on the investigation of Indoor Air Quality (IAQ) and measurement target pollutants are PM10, CO, $CO_2$, $NO_2$, $O_3$. It was found that levels of PM10, $CO_2$, and $NO_2$ inside subway cabin line 2 exceeded the Korea IAQ standard. Concentrations of PM10, $CO_2$, and $NO_2$ inside of the cabin are higher than outside of the cabin (Indoor Outdoor ratio is higher than 1.). Concentrations of CO, $O_3$ inside of the cabin are lower than outside of the cabin (Indoor Outdoor ratio is lower than 1.). There is a high correlation between $CO_2$ and passengers inside of the cabin and PM10 is only the weakest correlation with passengers. Therefore, it is important to find out the emission source of $NO_2$. The results of this study will be useful as fundamental data to study indoor air quality of a subway cabin.

• Tunnel and Underground Space
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• v.24 no.1
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• pp.67-80
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• 2014

Long-term stability and delayed failure of granite were evaluated through the laboratory test based on Wilkins method and Brazilian disc test (BDT) which yields tensile strength, mode I fracture toughness and subcritical crack growth parameters. Then, the long-term strength of granite was estimated by using analytical models and long-term stability of compressed air-energy storage (CAES) pilot cavern pressurized up to 5 ~ 6 MPa was evaluated using numerical code, FRACOD with the determined subcritical crack growth parameters. The results of test and analyses showed that the subcritical crack growth index, n was determined as 29.39 and the inner pressure of 5 ~ 6 MPa had an insignificant effect on the long-term stability of pilot cavern. It was also found that the measurement and analysis of acoustic emission events can describe the accumulation of damage due to subcritical crack growth quantitatively. That is, AE monitoring can provide the current status of rock under loading if we make an identical installation condition in the field with that of the laboratory test.