• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.247-253
• /
• 2011

An experimental study on performance characteristics of an evaporative heat exchanger based on tests for various operating conditions was presented. The heat exchanger maximizes the heat transfer rate per unit volume by applying mini-channels for both the air and coolant flow paths, and minimizes the amount of the coolant by using its latent heat of evaporation. The heat exchanger was manufactured by etching the flow paths, brazing the heat exchange plates, and welding the in/out ports of the media. The basic performance test has confirmed that the heat exchanger met its design requirements, and the results of the map test were analyzed to produce the performance characteristics quantitatively depending on the air inlet temperature, the air flow rate, and the coolant flow rate.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.721-724
• /
• 2011

A system to pressurize propellants stored in propellant tanks is necessary to feed liquid-propellants into combustion devices at the required pressure and flowrate without having cavitation in turbo-pumps. A pressurization system can be categorized into pre-pressurization stage and main-pressurization stage. This report is regarding to a main-pressurization system. Pressurization methods for propellant tanks are divided into pressurant gas generating method and pressurant gas feeding method. One of pressurant gas generating methods uses the vaporized oxygen gas from cryogenic liquid oxygen and non-flammable gas. In this report, both advantages and disadvantages for pressurization methods and types of pressurization systems are compared. Especially the characteristics and principle of pressurization system using impulsive control strategy applied in launch vehicles are introduced. Additionally the structure, schematics, and specifications of heat exchanger, which is one of main units in pressurization system are also discussed. This paper can be utilized to generate the conceptual requirements and to design preliminary configuration of pressurization system during the development of launch vehicle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.293-298
• /
• 2011

The combustion and flow-rate control characteristics of fuel-rich gas generator which could be adopted to Ducted Rocket propulsion system are investigated. The gas generator is designed considering the design requirements of propulsion system and solid fuel for fuel-rich combustion is developed then adopted to ground test. The results of combustion test show the necessity of the special analysis tool for estimating the gas generator performance where multi-phase flow of fuel-rich gas exists. During the flow-rate control test, characteristics of gas generator pressure with the angle of valve are analyzed and, method to estimate the pressure of gas generator is suggested using the relation between the valve exit area and discharge coefficient.

• Asian-Australasian Journal of Animal Sciences
• /
• v.12 no.8
• /
• pp.1246-1250
• /
• 1999

Rabbits (48) of Soviet chinchilla (24) and White giant (24) were fed from 6 weeks to 12 weeks of age intensively on either of four isonitrogenous - isocaloric diets containing 0 ($D_1$), 5($D_2$), 10($D_3$) and 20($D_4$) percent raw neem seed kernel cake (NSKC), respectively as per NRC (1977) requirements in a Randomized block design and slaughtered at the end to find out differences in their carcass traits due to NSKC feeding. Dietary treatment had no significant effect on weight of edibles and inedibles and their percentages and dressing percentage in terms of carcass, carcass with pluck and carcass with pluck and head. Similarly, the meat-bone ratio of various primal cuts and overall carcass, yield of edibles per unit of inedibles and eye muscle area were not influenced due to the dietary variations. Chemical composition of fresh meat, and organoleptic evaluation of cooked meat with and without salt did not vary significantly due to incorporation of NSKC in the diets. The rabbits fed 20% NSKC ($D_4$) though consumed more (p<0.05) DM and DE per kg meat production, the intake of crude protein and total digestible nutrients was similar with other dietary treatments. Feed cost per unit meat production was, however, lower on 5 and 10% NSKC containing diets by 7.75 and 12.56%, respectively, as compared to deoiled ground nut cake containing control diet. It appears that NSKC could be used as a wholesome vegetable protein supplement upto 10% in diet of rabbits without any adverse effect on commercial carcass traits.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.3 no.3
• /
• pp.231-236
• /
• 2005

HIC transport packaging to transport a high integrity container(HIC) containing dry spent resin generated from nuclear power plants is to comply with the regulatory requirements of Korea and IAEA for Type B packaging due to the high radioactivity of the content, and to maintain the structural integrity under normal and accident conditions. It must withstand 9 m free drop impact onto an unyielding surface and 1 m drop impact onto a mild steel bar in a position causing maximum damage. For the conceptual design of a cylindrical HIC transport package, three dimensional dynamic structural analysis to ensure that the integrity of the package is maintained under all credible loads for 9 m free drop and 1 m puncture conditions were carried out using ABAQUS code.

• Journal of Korea Multimedia Society
• /
• v.10 no.11
• /
• pp.1446-1459
• /
• 2007

This paper presents and analyzes a novel technique that makes it possible to improve the performance of low-end embedded systems through SoC(System-on-a-Chip) platform supporting dynamic cooperation between hardware and software modules. Traditional embedded systems with limited hardware resources have the poor capability of carrying out multi-tasking jobs including complex calculations. The proposed SoC platform, which provides dynamic cooperation between hardware and software modules, decomposes a single specific system into tasks for given system requirements. Additionally, we also propose a technique for efficient communication and synchronization between hardware and software tasks in cooperation with each other. Several experiments are conducted to illustrate the application and efficiency of the proposed SoC platform. They show that the proposed SoC platform outperforms the traditional embedded system, where only software tasks run, as the number of memory access is increased and the system become more complex.

• Journal of Advanced Navigation Technology
• /
• v.19 no.3
• /
• pp.207-216
• /
• 2015

Since the distribution of SBAS reference stations is one of the most important factors that affect the system performance, the effects of the distribution should be analyzed carefully from the beginning of the program to develop the system conforming to given performance requirements. The reference stations of KASS, the Korean SBAS, are planned to be installed only inside South Korea, which limits the number and area of those. It differentiates KASS from others that have much larger sites. In this paper, the author analyzes the performance impact on UDRE and ${\delta}UDRE$ for GPS and GEO due to the limitations by a series of simulations, which showed that the UDRE performance depends on the diversity of the reference station distribution and the impact on the GEO UDRE is significant. The paper concludes by providing KASS design and development considerations to minimize the possible performance risks due to the limitations of KASS reference station distribution.

• Journal of Advanced Navigation Technology
• /
• v.15 no.1
• /
• pp.147-156
• /
• 2011

IATA is playing a central role in the process of changing the international technical standards of common-use system which supports the airport check-in and boarding business in conjunction with the airline systems from CUTE to CUPPS. IATA expects that if the airport common-use system is changed to CUPPS, the development and maintenance costs related to the airline's common-use system can be reduced by the implementation of the standard interface about check-in and boarding business-related equipment and the certification of airline applications. Incheon International Airport is in the face of stiff competition with major Northeast Asian Airports to attract more airlines. To be more competitive than other airports, switching over to CUPPS is vital for airline's cost-saving effect. This study builds on CUPPS international technical standards and suggests design and implementation plans of Incheon International Airport's component-based next-generation common use passenger processing systems to support the various functions of user's requirements.

• Journal of Advanced Navigation Technology
• /
• v.15 no.6
• /
• pp.1104-1110
• /
• 2011

The conventional semiconductor equipment has adopted SRAM module as the test pattern memory, which has a simple design and does not require refreshing. However, SRAM has its disadvantages as it takes up more space as its capacity becomes larger, making it difficult to meet the requirements of large memories and compact size. if DRAM is adopted as the semiconductor inspection equipment, it takes up less space and costs less than SRAM. However, DRAM is also disadvantageous because it requires the memory cell refresh, which is not suitable for the semiconductor examination equipments that require correct timing. Therefore, In this paper, we will proposed an algorithm for punctuality guarantee of memory-free inspection equipment using DDR2 SDRAM. And we will Developed memory controller using punctuality guarantee algorithm. As the results, show that when we adopt the DDR2 SDRAM, we can get the benefits of saving 13.5 times and 5.3 times in cost and space, respectively, compared to the SRAM.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.2 no.1
• /
• pp.121-131
• /
• 1999

Automatic Rudder Trim System(ARTS) is a device to reduce the pilot's work load for rudder trimming greatly required in varying abruptly aircraft's engine power. This paper represents a technical analysis and a design of control law of the ARTS. The control law of the ARTS is designed based on the analysis of aircraft's characteristics, system's requirements, and limitations. The control law is comprised of open loop control using the rudder trim map for a specific aircraft and closed loop control to compensate the error of the open loop control system. flight test results show that the ARTS can reduce pilot's work load for rudder trimming dramatically and can compensate the aircraft's transient yaw motion.