• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.2
• /
• pp.70-76
• /
• 2000

A numerical study on the viscous flow around a 2-dimensional circulation control foil is carried out for application on the field of naval architecture and ocean engineering. The governing equations are the RANS and the continuity equations. The equations are discretized by finite difference method and MAC method and the pressure poisson equation is calculate by a SOR method and an O-type non-staggered boundary fitted coordinate system which is overlapped near the slot is used to improve the numerical accuracy. Turbulence is approximated by a modified Baldwin-Lomax turbulence model. In the present paper, the Coanda effect on a 2-dimensional foil of a 20% thickness ellipse with modified rounded trailing edge has been numerically studied. The change in drag and lift of the foil with various jet momentums are calculated and compared to the experimental results to show good agreements.

• Journal of Bio-Environment Control
• /
• v.8 no.2
• /
• pp.90-98
• /
• 1999

This study was conducted to select proper substrate and nutrient solution concentration for favorable growth and quality in common thyme (Thymus vulgaris L.). The growth of common thyme was better in deep flow culture (DFT) than in other substrate cultures. As the nutrient solution concentration rose, the ratio of dry matter increased, while the fresh weight and the number of lateral shoots decreased. The contents of total chlorophyll and vitamin C were higher in DFT than others. Ca, K, P were showed high contents in cocopeat, but Mg content was the highest at half-fold concentration in DFT. Common thyme showed low content of nitrate in DFT compared with that in other substrate culture. DFT was the most effective system for pronoting growth and quality of common thyme. The optimal concentration of nutrient solution in common thyme was half-fold(EC=1.2mS/cm) of herbs nutrient solution by European Vegetable R&D Center.

• Natural Product Sciences
• /
• v.16 no.4
• /
• pp.233-238
• /
• 2010

In order to facilitate the quality control of Artemisia capillaris, a simple, accurate and reliable HPLC method was developed for the simultaneous determination of the six bioactive compounds: scopolin (1), chlorogenic acid (2), 2,4-dihydroxy-6-methoxyacetophenone 4-glycoside (3), hyperoside (4), isorhamnetin 3-Orobinobioside (5), and scoparone (6), which were selected as the chemical markers of A. capillaris. Separation was achieved on an Agilent Eclipse XDB-C18 column with a gradient solvent system of 0.1% trifluoroacetic acid aqueous-acetonitrile at a flow-rate of 1.0 mL/min and detected at 254 nm. All six calibration curves showed good linearity ($R^2$ > 0.998). A simple reversed phase HPLC method was developed for extracting pharmacologically active compounds scopolin, chlorogenic acid, 2,4-dihydroxy-6-methoxyacetophenone 4-glycoside, hyperoside, isorhamnetin 3-O-robinobioside, and scoparone from A. capillaris using a binary gradient of acetonitrile : 0.1% trifluoroacetic acid with UV detection at 254 nm. The scopolin (1), chlorogenic acid (2), 2,4-dihydroxy-6-methoxyacetophenone 4-glycoside (3), hyperoside (4), isorhamnetin 3-O-robinobioside (5), and scoparone (6) contents of the herb of A. capillaris collected from fifteen district markets in Korea were 0.00~0.90 mg/g, 0.06~7.29 mg/g, 0.06~0.91 mg/g, 0.07~5.05 mg/g, 0.42~13.11 mg/g, and 1.11~29.82 mg/g, respectively. The results demonstrated that this method is simple and reliable for the quality control of A. capillaris.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1998.10b
• /
• pp.11-25
• /
• 1998

Many Countries have made efforts to assist ships navigate accurately , safely and expeditiously for the safety control against increasing marine traffic , in their coastal waters. However, they are exposed in spite of these efforts,to risks of casulaties and marine polluation caused by traffic congestion when ships are navigating through waterways approaches to ports or harbors and in narrow fairways. Therefore, efficient control of VTS in Port is necessary nowadays to provide ships with necessary service , which interacts with shipping and organize the flow of traffic so as to maximize the efficiency of the port or harbor while minimizing the risk of accident and environmental pollution. Even though the navigation condition of ships is very inferior compared to other ports in Korea, such as the big difference between the ebb and flood tide, the frequent fog, the narrow fairway , the density of navigation traffic in Inchon Port is high and transportation quantity of dangerous cargoe increases gradually. In cosideration of the characteristics of natural circumstance and traffic circumstance the VTS established newly in Inchon port have to operate efficiently. The purpose of this study is to help efficient operation of VTS in Inchon port by accomplishing both the literature research and questionnaire survey. Questionnaire survey was read to the VTS personnel in Inchon Port and customer familiar to Inchon Port such as ship navigators, pilots, shipping companies and so on. Most of ship navigators who occupy half of the respondents are Korean Officer who had responded while they were calling at Inchon port. The conclusions and recommendations includes ; First, the service area should be extended over Designated area to provide the vessel with navigational assistance service regarding the information of traffic congestion area, fishing boat and small ship's activities. Second, the types of information service to be offered are ship's movement and weather condition inthe vicinity of the port and state of fairway in the approaching channel to thte fairway. Third, VTS personnel should be upgraded by the on-the-job training and continuous simulation training as well as supplement of the qualified personnel for VTS operation. Fourth , the Harbor Master System to be introduced for safe navigation and efficient port operation.

• Journal of Korean Society of Forest Science
• /
• v.103 no.2
• /
• pp.240-247
• /
• 2014

This study was conducted as a restoration research in a mountain stream of hydrologic cycle system, which is a type of microsites purposely changing vegetation. The status of vegetation in the three experimental sites, water purification site, small dammed pole site, and aquatic plant restoration site, and one control site within the area of the mountain forest stream were investigated in three different periods, namely before sites restoration, year of sites restoration, and year after sites restoration. After one year of restoration, number of vegetation was increased in the small dammed pool and control site respectively. Vegetation coverage ratio of Zizania latifolia was increased at the water purification area. The effects of habitats restoration appeared to be good a year after the restoration of the experimental sites, in terms of families and species composition of the introduced vegetation, and stream flow. Therefore, the results of the study strongly suggest that fairly effective ways to restore and reproduce degrading mountain hydroecological habitats are by way of forming pool sites and small dams in intermittent mountain streams and re-vegetating with selected plants.

• Journal of Embryo Transfer
• /
• v.31 no.4
• /
• pp.355-365
• /
• 2016

The cryopreservation of sperm has become the subject of research for successful artificial insemination technologies. Antifreeze proteins (AFPs), one of the factors necessary for effective cryopreservation, are derived from certain Antarctic organisms. These proteins decrease the freezing point of water within these organisms to below the temperature of the surrounding seawater to protect the organism from cold shock. Accordingly, a recent study found that AFPs can increase the motility and viability of spermatozoa during cryopreservation. To evaluate this relationship, we performed cryopreservation of boar sperm with AFPs produced in the Arctic yeast Leucosporidium sp. AFP expression system at four concentrations (0, 0.01, 0.1, and $1{\mu}g/ml$) and evaluated motility using computer assisted sperm analysis. DNA damage to boar spermatozoa was measured by the comet assay, and sperm membrane integrity and acrosome integrity were evaluated by flow cytometry. The results showed that motility was positively affected by the addition of AFP at each concentration except $1{\mu}g/ml$ (p<0.001). Although cryopreservation with AFP decreased the viability of the boar sperm using, the tail DNA analyses showed that there was no significant difference between the control and the addition of 0.1 or $0.01{\mu}g/ml$ AFP. In addition, the percentage of live sperm with intact acrosomes showed the least significant difference between the control and $0.1{\mu}g/ml$ AFP (p<0.05), but increased with $1{\mu}g/ml$ AFP (p<0.001). Our results indicate that the addition of AFP during boar sperm cryopreservation can improve viability and acrosome integrity after thawing.

• Advances in aircraft and spacecraft science
• /
• v.4 no.5
• /
• pp.503-514
• /
• 2017

The attitude control of an aircraft is usually fulfilled by means of thrusters at high altitudes. Therefore, the possibility of using also aerodynamic surfaces would produce the advantage of reducing the amount of fuel for the thrusters to be loaded on board. For this purpose, Zuppardi already considered some aerodynamic problems linked to the use of a wing flap in a previous paper. A NACA 0010 airfoil with a trailing edge flap of 35% of the chord, in the range of angle of attack 0-40 deg and flap deflections up to 30 deg was investigated. Computer tests were carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km of Earth Atmosphere. The present work continues this subject, considering the same airfoil and free stream conditions but two flap extensions of 45% and 25% of the chord and two flap deflections of 15 and 30 deg. The main purpose is to compare the influence of the flap dimension with that of the flap deflection. The present analysis is carried out in terms of: 1) percentage variation of the global aerodynamic coefficients with respect to the no-flap configuration, 2) increment of pressure and heat flux on the airfoil lower surface due to the Shock Wave-Shock Wave Interaction (SWSWI) with respect to the same quantities with no SWSWI or in no-flap configuration, 3) flap hinge moment. Issues 2) and 3) are important for the design of the mechanical and thermal protection system and of the flap actuator, respectively. Under the above mentioned test and geometrical conditions, the flap deflection is aerodynamically more effective than the flap extension, because it involves higher variation of the aerodynamic coefficients. However, tests verify that a smaller deflection angle involves the advantage of a smaller increment of pressure and heat flux on the airfoil lower surface, due to SWSWI, as well as a smaller hinge moment.

• Journal of Bio-Environment Control
• /
• v.16 no.3
• /
• pp.222-227
• /
• 2007

In this study, nutrient solution for Liliaceae (Chinese chive) leafy vegetable was developed. The various strength (1/2, 1 and 3/2) of nutrient solution recommended by National Horticultural Research Institute (NSH) was applied to the crops in deep flow technique (DFT) system for 42 days. The growth of Chinese chive were highest in the treatment of 1/2 strength. The proper constitution of nutrient solution developed for liliaceae crops (NSL) was N 12, P 2.5, K 7, Ca 4 and Mg 2 met. The crops were grown two times in March and September to examine the appropriateness of the NSC. As a result, the relative growth rate and the amount of chlorophyll (SPAD value)of Chinese chive treated with NSL were increased 1.11 times. The most important nutrient factor of ascorbic acid were also increased 1.16 times.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.6
• /
• pp.251-257
• /
• 2014

An actuator system is a type of motor designed to control a mechanism operated by a source of energy, in the form of an electric current by converting energy into some kind of motion. As audio actuators, transforming electric voltage signal into audio signal, speakers and amplifiers are commonly used. In applications of industry, high output power systems are required. For these systems to generate high-quality output, it is essential to control output impedance of audio systems. We have developed an adaptable power supply for driving active amplifier systems with variable loads. Depending on the changing values of resistance of the speaker which produces audible sound by transforming electric voltage signal, the power supply source of the active amplifier can generate the maximum power delivered to the speaker by an adaptable change of loads. The amplifier is well protected from the abrupt increment of peak current and an excess of current flow.

• KIEAE Journal
• /
• v.13 no.5
• /
• pp.43-50
• /
• 2013

Recent researches on plant factory system deal with the convergence of lighting technology, agricultural technology inclusive to the high-tech industries worldwide in order to respond to the decreasing crop harvest due to global warming and abnormal weather phenomena. However, the fundamental performance standard is not currently being introduced in the case of plants factory and its commercialization is not activated because of high initial investment and operating cost. Large portion of the initial investment and operating cost of a plant factory is ascribed to artificial light sources and thermal control facilities, therefore, innovation should be provided in order to improve the economics of the plant factory. As an alternative, new plant factory could harness solar thermal and geothermal systems for heating, cooling and ventilation. In this study, a natural light dependent multi-layer plant factory's thermal environment was analyzed with two-dimensional numerical methods to elicit efficient operation conditions for optimized internal physical environment. Depending on the supply air temperature and airflow rate introduced in the facility, the temperature changes around the crops was interpreted. Since the air supplied into the plant factory does not stay long enough, the ambient temperature predicted around the plating trays was not significantly different from that of the supplied air. However, the changes of airflow rate and air flow pattern could cause difference to the temperature around the planting trays. Increasing the amount of time of air staying around the planting trays could improve energy performance in case the thermal environment of a natural light based multi-layer plant factory is considered.