• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.65-75
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• 2022

Livestock industry in Korea has been growing rapidly and has reached 23 trillion Korean won in 2021. This study focuses on broiler, which is one of the largest sectors in livestock industry. As the effects of climate change get more serious, primary industry such as livestock industry is fragile to climate change since it directly interacts with nature. Therefore, maintaining suitable rearing environment is important. One of the most frequently used ventilation type for controlling the rearing environment of broiler house, tunnel ventilation, causes frequent air velocity fluctuation which makes maintaining the rearing environment important. By measuring the air temperature, relative humidity and air velocity in various points inside the broiler house, the internal thermal environment uniformity was analyzed according to length, width and zone. The experimental house was found to have dead zone with high air temperature, relative humidity and low air velocity near the end of the inlet and at the end of the broiler house. By using heat stress index to analyze quantitatively, zone with highest heat stress index was found to increase by 7.55% compared to the lowest zone. As a result, to maintain uniform rearing environment inside the broiler house, different factors must be measured and analyzed and used to operate the environmental control facilities.

• Journal of Biomedical Engineering Research
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• v.35 no.5
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• pp.119-124
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• 2014

A Ventricular assist device (VAD) is one of the most efficient treatments to raise the survivability of the end stage heart failure patient. However, some of LVAD patients have died for the failures and improper control of LVAD. To detect critical dangers in LVAD, the monitoring methods of LVAD outflow have been requested, because it can be affected by patient's hemodynamic states and abnormal conditions of LVAD. In the case of an external pulsatile LVAD, the air movement through the air line can be used to estimate LVAD outflow. In this study, the air movement in the air-line of the extracorporeal pulsatile LVAD was measured with a differential pressure sensor between different points. The precise estimation of air movement could be achieved by additional measurement of air pressure. In a series of in-vitro experiments, the LVAD outflow were changed according to the afterload of LVAD and the differential pressure of LVAD didn't have close correlation with the LVAD outflow that were measured with an ultrasonic flowmeter at the same time. However, new precise estimation with the data from differential pressure and one point pressure in the air-line showed higher correlations with LVAD outflow.

• Journal of the Korean Solar Energy Society
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• v.39 no.1
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• pp.77-89
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• 2019

The solar air heater has various performances according to an obstacle installed in the air duct. Many studies on thermal performance have been conducted. But many of these studies were using a kind of rib type obstacle attached at the bottom of absorbing plate, but they are so hard to be manufactured. In this study, characteristics of the heat transfer and pressure drop in the solar air heater with various horizontal rectangular obstacles was investigated by CFD (Computational Fluid Dynamics) analysis. As a result, the heat transfer performance was improved from 1.2 to 3.32 times depending on installation conditions of rectangular obstacle. The pressure drop, however, also increased with increment of heat transfer performance from 2.8 to 180 times only by changing installation conditions of rectangular obstacle. Thus, the performance factor presenting the thermal performance enhancement on the same pressure drop was also confirmed. As a result, the highest value of 0.828 as better performance factor was obtained at the lower height of rectangular obstacle and this value has started to decrease with increment of heat transfer performance. In the end, it could be confirmed that the pressure drop was carried higher than the quantity of improvement of the heat transfer performance when the heat transfer performance was increased by change of installation conditions of rectangular obstacle. Both heat transfer enhancement and pressure drop to be required for system need to be considered before the rectangular obstacles are applied to the solar air heater.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1279-1284
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• 2012

Micro structures which are widely used at various fields are commonly fabricated by lithograph, etching and laser methods. Recently, with the emergence of micro tools and ultra-precision machine tools, fabrication of the micro structures obtained using end-milling are studied. However, there are some problems due to the diameter of the micro end-mill getting smaller below $100{\mu}m$. The micro run-out resulted from miniaturization of end-mills have influence seriously on accuracy of micro structures. The error of run-out with a tooling jig showed a decrease of about $9.3{\mu}m$. Furthermore, micro structures with width of $30{\mu}m$ could be applied through experiments of slot machining obtained using 30 and $50{\mu}m$ end-mill. Also, narrow angle structures with $30^{\circ}$ angle could be applied through analysis of machining acute angle structures. Based on basic experiments, micro fluidics channels and spiral patterns for air bearing were machined.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.567-571
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• 2008

PEM Fuel Cell operation mode can be classified into dead-end mode or open mode by whether the outlet port is blocked or not. Generally, dead-end type fuel cell has some merits on the pressure drop and system efficiency because it can generate more power than the open type fuel cell due to high operating pressure condition. However, the periodic purging process should be done for removing water which is formed as product of a reaction in the gas diffusion layer. In this study, cathode side dead-end type operation has been conducted. Moreover, pulsating flow generator at the outlet of cathode side has been suggested for increasing the period to purge the formed water because the pulsating flow can make formed water scattered uniformly over the whole channel. As a result, the purging period with pulsation increased by 1.5-2 times longer than that without pulsating.

• Journal of Environmental Health Sciences
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• v.36 no.6
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• pp.472-479
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• 2010

The purpose of this study was to investigate the concentration of indoor air pollutants at 63 elementary schools, 41 middle schools and 51 high schools in Ulsan from the beginning of May to the end of December, 2008. To assess the indoor air quality of the various classrooms, the 8 indoor air pollutants such as $CO_2$, CO, $NO_2$, $O_3$, $PM_{10}$, TVOCs, HCHO and TBC were measured and analyzed. The mean concentrations of $PM_{10}$ and TBC in the elementary schools were significantly higher than those of middle and high schools (p < 0.01). For the HCHO, the multi-use practice rooms showed an average 1.5 times higher than general classrooms. In schools located in urban areas, the concentrations of CO, $O_3$, $PM_{10}$, HCHO and TBC were lower than in the vicinity of industrial complexes. The exceeding rate of the school air quality maintenance limits in the 6 air pollutants by law were 6.7%, 3.5%, 1.7%, 18.2%, 13.0% and 18.4% for $CO_2$, $NO_2$, $O_3$, $PM_{10}$, HCHO and TBC, respectively. Based on these results $PM_{10}$ and TBC have to be in the order of priority of need to improve the classroom air quality in elementary school of Ulsan.

• Journal of Biosystems Engineering
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• v.25 no.2
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• pp.115-122
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• 2000

This study was performed to develop a prototype continuous flow ginseng dryer with which better product quality and lower drying energy consumption could be achieved compared with conventional ginseng dryers. A dryer having both far infrared ray (IR) and heated-air as the drying energy sources was designed and fabricated . Dryer performance was studied by examining energy efficiencies and dryer performance evaluation indices (DPEI) during the drying tests of medium-sized four year ginseng roots with IR radiating plate temperature and drying air temperature in the range of 80-12$0^{\circ}C$ and 22-5$0^{\circ}C$, respectively. The DPEI of IR /heated -air combined drying was 1/3 of that of the conventional heated-air drying when ginseng were dried to the same final moisture ratio. When ginsengs were dried for 12 hours in the prototype IR/heated-air combination dryer, a linear relationship was found to exist between final moisture ratio and ginseng temperature. As the drying progressed, drying air temperature inside the dryer was nearly constant but ginseng temperature was drastically increased during the first two hours and gradually increased thereafter until the end of drying. With the prototype Ir/heated-air combination dryer, the drying rate changed little but the energy efficiency increased proportionally when the amount of ginseng to be dried increased. Drying capacity, energy efficiency, and DPEI of the prototype IR/heated-air combination ginseng dryer were estimated to 1.500 roots, 65% and 3.800kJ/kg-water , respectively.

• Journal of the Korea Safety Management & Science
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• v.10 no.4
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• pp.181-187
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• 2008

The market of air cargo in Korea grows very quickly and diversifies. It is an essential factor in the process of development of Northeast-Asia as a hub for Air Cargo logistics. But the process of air cargo in Korea is complex as compared with other north-east asia nations and it has many problems and causes inconvenience to owners of freight. We emphasize that 4PL(Fourth party Logistics) is the excellent solution from among many alternatives. The wave of 4PL added to strategic consulting based on new IT techniques, for example RFID, with logistics outsourcing through existing 3PL service is a great issue. It is also worthy of notice that EPCglobal network strengthen the role of 4PL. In conclusion, the 4PL system based on EPCglobal network will result in a good success, so it will raise a prestige of air cargo in Korea to a higher position. This study deals with the new logistics system, air cargo logistics system based on u-4PL system, RFID and EPCglobal network, that will bring many advantages. At the end, we verify the u-4PL air cargo logistics system by simulation tool.

• The Journal of Information Systems
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• v.14 no.3
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• pp.63-70
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• 2005

Compared with land logistics and sea logistics, air logistics takes not only less transportation time, but also makes just-in-time delivery possible. Because of this, in spite of high freight rates, many shippers make good use of airlines. To cope with borderless competition in this global age, most shippers using air logistics want to receive diverse information including just-in-time cargo delivery and dangerous situation as well as convenience and speed in job handling. Nevertheless, most domestic forwarders, who perform many kinds of important businesses for air logistics, mainly put emphasis on demanding information from overseas partners through their business agreements, that is, focusing on horizontal integration, instead of sharing information or improving job performance among air logistics participants. As a result, it is almost impossible to satisfy the needs of shippers. Airline users want to remove the uncertainties over their cargo movement. And in time of emergency, they want to take immediate measures through speedy information sharing and decision-making. In order to satisfy shipper's needs, all the organizations participating in the air logistics supply chain-cargo senders, cargo receivers, forwarders, transporters, licensed customs brokers, airlines as well as foreign partners-have to set up a vertical cooperation system. For effective air logistics SCM, it is very important to remove overlapping jobs, strengthen the efficiency of job handling, and provide online monitoring on cargo information in order to support decision-making. To this end, this paper has applied the concept of RTE (Real Time Enterprise), a new business management system, which tries to maximize competitiveness by removing many hindrance factors on an ongoing basis in managing and fulfilling core business processes based on up-to-the-minute information. In order to realize RTE-based information system for air logistics SCM, this paper has analyzed the information required by business process and by air logistics participant, and suggested the method for information sharing, point of time for information input and output, and its means.

• Korean Journal of Medicinal Crop Science
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• v.26 no.4
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• pp.291-295
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• 2018

Background: The use of Rehmannia glutinosa of the family Scrophulariaceae, in traditional medicine is well known. This study was conducted to elucidate the effect of air curing of the seed rhizome of R. glutinosa on its storability and yield. Methods and Results: The root of the R. glutinosa cultivar (Dagang) was harvested in at the end of November. The seed rhizomes were air cured for one to seven days. They were subsequently wrapped with newspaper and further stored in a plastic container at $1^{\circ}C$. It was observed that the weight loss and decay rates were significantly lower in the air cured seeds than in the untreated ones. Moreover, the decay rate of the control was approximately 50%, 120 days after storage. However. the decay rate of all the air cured treatment groups was less than 1%. Additionally, air curing led to an increase in the germination rate of the seeds and the root yield when compared with the untreated groups. Taken together, the ideal treatment period for air curing was found to be 3 days. Under these conditions, the germination rate and yield were 88.7% and 2,185 ㎏/10a, respectively. Conclusions: This study successfully demonstrated that the air curing of seed rhizomes can lead to a considerable increase in the storability and yield of R. glutinosa.