• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.479-487
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• 2022

This paper presents the control and guidance algorithm of a KAU-SPUAV(Korea Aerospace University - Solar Powered Unmanned Aerial Vehicle) which is designed and developed in Korea Aerospace University. Aerodynamic coefficients are calculated using the vortex-lattice method and applied to the aircraft's six degrees of freedom equation. In addition, the thrust and torque coefficients of the propeller are calculated using the blade element theory. An altitude controller using thrust was used for longitudinal control of KAU-SPUAV to glide efficiently when it comes across the upwind. Also describes wind estimation technic for considering wind effect during flight. Finally, introduce some guidance laws for endurance, mission and coping with strong headwinds and autonomous landing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.4
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• pp.328-335
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• 2023

In this paper, among the various facilities used in marine farming, young bivalves of the Mytilus galloprovincialis of marine farming was placed on the deck of the fishing vessel to evaluate the environment conditions and drive shaft movement by rolling affecting the separator for the young bivalves and a clean process. There were a few studies on stress analysis of development facilities because it was difficult to access the fishing site due to the use of imported equipment and the lack of development of domestic equipment. In this study, stress analysis of the fixed part of separator for young bivalves and its adjacent part was performed on various phases when the vessel was tilted by rolling using the finite element method. In addition, the structural safety of the internal blade under the driving conditions according to the movement of the drive shaft by the hydraulic motor was confirmed through structural analysis. As a result, the connection part between the deck and the separator by rolling was confirmed to have higher stress than that of other parts due to stress concentration. In addition, it was confirmed that the maximum stress occurred on the connection part between blades. Even though the safety of the separator for marine farming was confirmed by structural analysis, it is necessary to comprehensively consider the age of vessels, the material of the deck, and the corrosion of the deck.

• Korean Journal of Animal Reproduction
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• v.25 no.2
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• pp.93-100
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• 2001

This study was conducted to evaluate the nuclear development of preantral follicle oocytes in dog following collecting from different estrus ovaries and oocyte diameter. To do this, ovaries were collected from Sunchon livestock station by ovarioectomy and then transported to laboratory in 3$0^{\circ}C$ saline within 2 h. All of the ovaries were washed three times with saline supplemented with 100 IU Penicillin and 100 $\mu\textrm{g}$/$m\ell$ Streptomycin and then sliced with blade in 100 mm dish. All of the oocytes collected were classified the oocyte size such as over 110 ${\mu}{\textrm}{m}$ or under 110 ${\mu}{\textrm}{m}$ and the estrus status. To induce the nuclear development, oocytes were cultured in TCM199 $\alpha$-MEM supplemented with 10% FCS, 0.1 $\mu\textrm{g}$/$m\ell$ sodium pyruvate, 100 ng/$m\ell$ FSH, 100 ng/$m\ell$ EGF, 1% ITS, 100 IU/$m\ell$ penicillin, 100 $\mu\textrm{g}$/$m\ell$ streptomycin at 38.5$^{\circ}C$, 5% $CO_2$ incubator for 72 h. After culture, all of the oocytes were stained in 1% orcein following fixed in 45% Acetic acid for 48 h. The oocyte recovery rates of over 110 ${\mu}{\textrm}{m}$ from estrus ovary (63.6%) were significantly higher rather than that in anestrus status (51.5%). Oocyte recovery rate per ovary of over 110 ${\mu}{\textrm}{m}$ in estrus status ovary (22.6/63.8%) was also significantly higher rather than that in anestrus status ovary (8.2/51.6%). Nuclear development to MI of over 110 ${\mu}{\textrm}{m}$ in estrus ovary (24.3%) was significantly higher rather than those in under 110 ${\mu}{\textrm}{m}$ or over and under 110 ${\mu}{\textrm}{m}$ in anestrus (2.5, 6.8 and 0.0%), respectively (P ＜ 0.05). Nuclear development to AT and MII of over 110 ${\mu}{\textrm}{m}$ in estrus was more developed in other groups. Nuclear development to MI in TCM199 (21.8%) was significantly higher than in $\alpha$-MEM (10.0%). Altho $\mu\textrm{g}$h the development rate to AT was significantly different between TCM199 (7.3%) and $\alpha$-MEM (1.1%), but to MII was not different between TCM199 (0.9%) and $\alpha$-MEM (1.1%). The results indicated that over 110 ${\mu}{\textrm}{m}$ oocytes was could be recovery from estrus status ovary, bigger oocytes were more developed to MI, AT or MII in TCM199.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1186-1191
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• 2006

Removal efficiency of As(III) through oxidation and adsorption in column reactors was investigated at different ratios of manganese-coated sand(MCS) and iron-coated sand(ICS) : MCS-alone, ICS-alone and both of ICS and MCS. The breakthrough of arsenic immediately occurred from a column reactor with MCS-alone. However, most of the arsenic present in the effluent was identified as As(V) due to the oxidation of As(III) by MCS. While five-times delayed breakthrough of arsenic was observed from a column reactor with ICS-alone. At a complete breakthrough of arsenic, the removed As(III) was 36.1 mg with 1 kg ICS. To find an optimum ratio of ICS and MCS in the column packed with both ICS and MCS, the removal efficiency of As(III) was investigated at three different ratios of ICS/MCS with a fixed amount of ICS. The breakthrough time of arsenic was quite similar in the different ratios ICS/MCS. However, much slower breakthrough of arsenic was observed as the ratio of ICS/MCS decreased. As the ratio of ICS/MCS decreased the concentration of As(III) in the effluent decreased and then showed below 50 ppb at an equal amount of ICS and MCS, suggesting more efficient oxidation of As(III) by greater amount of MCS. When a complete breakthrough of arsenic occurred, the removed total arsenic with an equal amount of ICS and MCS was 68.5 mg with 1 kg of filter material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.69-76
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• 2018

The present study analyzed the effect of film hole position of 45 degree ribbed cooling channel on film cooling performance of gas turbine blades. We also investigated the influence of the ribs under the fixed blowing ratio. Three-dimensional numerical model was constructed and extensive simulation was conducted using the commercial code (Fluent ver. 17.0) under steady-state condition. Base on the simulation results, We investigated the cooling effectiveness, flow velocity, streamline, and pressure coefficient. Moreover, We analyzed the effect of cooling hole position on ejection of the secondary flow caused by the rib structure. From the results, It was found that internal flow of the cooling channel forms a vortex pair in the counterclockwise from the top side, and clockwise from the bottom side. For the channels with ribs, the vortex flow generated by the ribs caused a higher pressure difference near the hole outlet, resulting in at least 12% higher cooling effectiveness than the channel without ribs. Additionally, when the hole is located on the left side of the ribbed channel (Rib-Left), it can be found that the secondary flow generated by the ribs hits against wall surface near the hole to form a flow in the direction of the hole inclination angle. Therefore, It is considered that the region where the cooling gas discharged to the blade surface stays in the main flow boundary layer is wider than the other cases. In this case, The largest pressure coefficient difference was observed near the outlet of the hole, and as a result, the discharge of the cooling gas was accelerated and the cooling efficiency was slightly increased.