• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.629-634
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• 2011

A prestudy on expendable turbine engine for high-speed vehicle was conducted. The two possible mission profiles were established to decide the engine requirements and Design Point, and Design Point analysis was performed with the values of design parameter which were obtained from similar class engines and technical references. The results showed that Specific Net Thrust is 2599.4 ft/s and Specific Fuel Consumption is 1.483 lb/($lb^*h$) at the flight condition of Sea Level, Mach 1.2. It was also found through the performance analysis on the two possible mission profiles that major design parameters for determining Net Thrust were Turbine Inlet Temperature for low supersonic flight speed and Compressor Exit Temperature for high supersonic flight speed. In addition, simple turbojet engine with axial compressor, straight annular combustor, axial turbine and fixed throat area converge-diverge exhaust nozzle was proposed as the configuration of simple low cost light engine.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.2
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• pp.248-255
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• 2012

Three levels of boron (0, 30, 60 ppm) were supplemented in practical corn-soybean based starter and grower diets, containing either adequate or inadequate Ca or P. A total of 1,800, 1-day-old sexed broiler chicks were assigned to six dietary treatments and fed with the experimental diets for 42 days. Boron improved the overall feed conversion ratio, but increased body weight only at 21 days of age (p<0.01). Boron decreased feed intake in the case of feeding on a diet deficient in Ca and P, and tended to increase feed intake when birds received a diet adequate in Ca and P, signifying significant boron by Ca-P interaction (p<0.01). Mortality was not influenced by boron (p>0.05). Dietary Ca and P deprivation reduced body weight and feed consumption significantly, but did not influence the feed conversion ratio and mortality (p>0.05). Serum Ca level, ALP and ALT activities were not influenced either by dietary Ca and P deficiency or boron supplementation. Serum P content increased with respect to boron at 30 ppm. Bone breakage strength was not affected by dietary variables. Tibia ash, Ca and P were increased in response to the supplementation diet with 30 ppm boron, whereas 60 ppm showed no effect in most cases. Accordingly, the dietary boron supplementation of 30 ppm significantly decreased fecal Ca and P excretion, while there was a numerical decline in the 60 ppm boron as compared to the 0 ppm boron group. Data presented herein indicated that boron, either at the 30 ppm or 60 ppm supplementation level, was effective in conversion of feed to body weight, whereas only boron at 30 ppm contributed to the mineralization of bone thereby augmenting more Ca and P while excreting less through faeces.

• Nutrition Research and Practice
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• v.14 no.4
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• pp.374-383
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• 2020

BACKGROUNDS/OBJECTIVES: To describe the data-based development of a food frequency questionnaire (FFQ) for dietary evaluation of Korean preschool children. SUBJECTS/METHODS: Development of the FFQ was based on the data from 2,766 preschool children aged 1-5 years, who had completed 24-hour dietary recalls in the 2009-2013 Korea National Health and Nutrition Examination Survey. We selected the food list based on the results of nutritional contribution and between-person variability for energy and 13 nutrients. We selected 88 foods with over 80% of total contribution to each nutrient and with over 80% of accumulated r² for each nutrient. A dish containing any of the 88 foods in the recipe was listed, and a total of 903 dishes were extracted. Among the 903 dishes, we selected 438 dishes contributing more than 1% of total consumption. RESULTS: FFQ included 116 dish items combined from 438 dishes based on nutrient profile and recipe. Quantities of dietary intake were assessed by nine categories of frequency and portion size option. In addition, when comparing the food portions of children with the reference portion size, subjects would be asked to select one of three response categories (less, similar, and more) and then to record the amount as a percentage for the reference portion. Percentages of coverage for energy, protein, fat, and carbohydrate were 89.2%, 88.4%, 88.2%, and 89.4%, respectively. CONCLUSIONS: The dietary intake of Korean preschool children can be assessed by this new data-based FFQ. In addition, the new instrument can be used to identify nutritional needs of target groups for planning nutrition education and strategies to improve diet. Further studies are warranted to evaluate the performance of the instrument.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.73-84
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• 2020

To overcome ground congestions due to growing number of cars, a lot of companies have proposed personal aerial vehicle (PAV). Among PAV, electric vertical take-off and landing (eVTOL) aircrafts capable of vertical take-off and landing with electric power are drawing attention, and their configurations vary from multicopters to tilt ducted fans. This study tries to analyze the characteristics of each eVTOL design configurations. Parasite drag was calculated using component build up method for Vahana, Aurora, Volocopter representing each eVTOL PAV type of tilt-wing, compound, and multicopter. Wetted area and induced drag was calculated using OpenVSP and XFLR5 that are aircraft design and aerodynamic analysis software. The batteries used in the eVTOL PAV was assumed as Tesla 2170 batteries and flight ranges were calculated. Also, energy consumption and maximum flight time for the given mission profile including take-off and landing, cruising segments were compared for each eVTOL.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.391-400
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• 2014

The number of large scale greenhouses has recently been increasing to cope with mass consumption of agricultural product. Korean government announced a new development plan for constructing greenhouse complex in reclaimed lands for the purpose of improvement in exports and activation of domestic market of agricultural product. Wind environment in the reclaimed land is totally different from that of inland area, and it can give a strong influence on ventilation performance of naturally ventilated greenhouse facilities. In this study, internal airflow analysis of naturally ventilated greenhouse built on a reclaimed land was conducted using wind tunnel and PIV for validation research. Later, the PIV measured results will be used to improve the accuracy of 3 dimensional CFD simulation in the future. Wind profile at a reclaimed land was produced using ESDU program and it was applied to the wind tunnel. The calculated error was only 5% and 0.96 of correlation coefficient, implying that the computed profiles were designed properly. From the measured results, when external wind speed changed from $1m{\cdot}s^{-1}$ to $1.5m{\cdot}s^{-1}$, air velocities inside the greenhouse which PIV measured were also increased proportionately in case of both side vent open and side-roof vent open. Considering reduced ratio of air velocity inside the greenhouse, it was measured a minimum of 40% in case of side vent and 30% in case of side-roof vent compared with external wind speed from each vent type. From the quantitative and qualitative PIV analysis, the PIV measured results indicated that there were well ventilated and stagnant areas in the greenhouse according to external wind condition as well as ventilation design.

• Journal of Evidence-Based Herbal Medicine
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• v.2 no.2
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• pp.33-38
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• 2009

Korean Ginseng has been recognized as a representative special product in Korea and over the world for a long time, since its quality is known to be superior to Chinese, North American Ginseng. However, the export volume of Korean Ginseng products has been diminishing since 1990 because the imports of low price Chinese Ginseng and the effective marketing policy on North American Ginseng. Therefore, this study is to suggest the competitiveness reinforcement strategies through analyses of the present state and transition of the international competitiveness in Korean Ginseng. This study conducts the comparative analysis of international competitive power of ginseng between Korea and other exporting countries. There are many kinds of saponin that are competitive from a quality profile. However, price competitiveness was very low. According to the result of analysis, this study suggest the competitiveness reinforcement strategies of Korean Ginseng as follows ; First, it is necessary to establish the ginseng plan for high-quality environmentally-friendly production. Second, Korean Ginseng producer should develop various consumer-oriented products according to purchasing power and taste of target market consumers. Third, export strategies must be established by finding out every importing country’s characteristics with regard its import, circulation and consumption of the Korean Ginseng. The use of this study is to forecast useful information to concerned organization for the future policies to the ginseng products in the international market.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.684-695
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• 1992

The present study is concerned with the analysis of three-dimensional sheet metal forming process by the upper-bound method. For the analysis a systematic approach is necessary for the expression of geometric configuration of the deforming workpiece. In the present paper geometric configuration is constructed by three unit surfaces which are defined by sweeping the vertical section curves and boundary curve. The principal components of strain increment during the process is calculated directly from the change of geometric configuration for an arbitrary triangular element. The corresponding solution is found through optimization of the total energy consumption with respect to some parameters assumed in the velocity field and geometric profile. In order to verify the effectiveness of the present method, hydrostatic bulging of a rectangular disphragm is analyzed and the computation by the present method for the geometric shape renders the good result. From the comparison of the present results with the existing experimental results and elastic-plastic finite element solutions, good agreements have been obtained for the pressure curves, polar membrane strains and pressure distributions. The present method can thus be further applied to the analysis of other three-dimensional sheet metal forming processes.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.97-102
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• 2013

A prestudy on expendable turbine engine for high-speed vehicle was conducted. After two possible mission profiles were established to decide the engine requirements, design point analysis was performed with the values of design parameter which were obtained from similar class engines, references, etc. The results showed that specific net thrust and specific fuel consumption with turbine inlet temperature of 3,600 R are 2,599.4 ft/s and 1.483 lb/(lb*h) respectively at the flight condition of sea level, Mach 1.2. It was also found that major design parameters for determining maximum net thrust were turbine inlet temperature for low supersonic and transonic flight speed and compressor exit temperature for high supersonic flight speed from the results of performance analysis on the two possible mission profiles. In addition, simple turbojet engine with an axial compressor, a straight annular combustor, an one stage axial turbine and a fixed throat area converge-diverge exhaust nozzle was proposed as the configuration of simple low cost lightweight turbine engine.

• Nutrition Research and Practice
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• v.8 no.4
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• pp.360-367
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• 2014

BACKGROUND/OBJECTIVES: The aim of this research was to study the different long term effects of consumption of dietary oil sources with varying omega-6/omega-3 (${\omega}-6/{\omega}-3$) polyunsaturated fatty acids (PUFAs) ratios on bone marrow fatty acid level, ex vivo prostaglandin $E_2$ ($PGE_2$) release, and mineral content of bone in rabbits. MATERIALS/METHODS: For this purpose, weaning and female New Zealand white rabbits were purchased and randomly divided into five groups and offered ad libitum diets containing 70 g/kg of added oil for 100 days. The dietary lipid treatments were formulated to provide the following ratios of ${\omega}-6/{\omega}-3$ fatty acids: 8.68 soy bean oil (SBO control), 21.75 sesame oil (SO), 0.39 fish oil (FO), 0.63 algae oil (DHA), and 0.68 algae oils (DHA/ARA). DHA and ARA are two types of marine microalgae of the genus Crypthecodinium cohnii. RESULTS: The dietary treatments had significant effects on the bone marrow fatty acids of rabbits. Rabbits fed the FO diet, containing the highest ${\omega}-3$ PUFA concentration, and those fed the SBO diet showed the highest ${\omega}-6$ PUFA. On the other hand, a positive correlation was observed between Ex vivo $PGE_2$ level and the ${\omega}-6/{\omega}-3$ dietary ratio. Significant effects of dietary treatment on femur Ca, P, Mg, and Zn contents were observed in both genders. CONCLUSIONS: Findings of the current study clearly demonstrated that dietary PUFA, particularly ${\omega}-6/{\omega}-3$ and ARA/EPA ratios are important factors in determining bone marrow fatty acid profile, and this in turn determines the capacity of bone for synthesis of $PGE_2$, thereby reducing bone resorption and improving bone mass during growth.

• KSBB Journal
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• v.31 no.3
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• pp.171-177
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• 2016

The effects of medicinal mushroom (Sparassis crispa) powder supplementation on the rheological property of dough and the quality of bread were investigated. Naturally dried S. crispa powders (NDSCP) and freeze-dried ones (FDSCP) were prepared. Farinograph profiles of dough showed that mushroom powder addition at levels higher than 1% led to reduced dough stability suggested by decreased development time and increased weakness. The incorporation of S. crispa powders was significantly (p<0.05) lower compared to other mushrooms which might be attributed to its high content of beta-glucan. FDSCP was chosen over NDSCP because of its fragrant flavor which could be ascribed to the preservation of volatile polyphenol components. The quality of FDSCP bread was evaluated with respect to specific volume, texture, color, and organoleptic qualities. The specific volume of bread with S. crispa powder decreased compared to the control, while textural properties, such as hardness, chewiness, and gumminess, were enhanced. Sensory evaluation showed that 0.3% FDSCP incorporation presented the highest bread quality. With its daily consumption, S. crispa supplemented bread can provide consumers with multiple health benefits.