• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.25-32
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• 2006

Weapon systems composed of several subsystems execute various engagement missions in distributed combat environments in cooperation with a large number of subordinate/adjacent weapon systems as well as higher echelons through tactical data links. Such distributed weapon systems require distributed real-time simulation test beds to integrate and test their operational software, analyze their performance and effects of cooperated engagement, and validate their requirement specifications. These demands present significant challenges in terms of real-time constraints, time synchronization, complexity and development cost of an engagement simulation test bed, thus necessitate the use of high-performance distributed real-time simulation architectures, and modeling and simulation techniques. In this paper, in order to meet these demands, we presented a distributed real-time simulation system based on High Level Architecture(HLA) and Discrete Event System Specification(DEVS). We validated its performance by using it as a test bed for developing the Engagement Control System(ECS) of a surface-to-air missile system. The proposed technique can be employed to design a prototype or model of engagement-level distributed real-time simulation systems.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.88-94
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• 2006

In order to substitute current aluminum sabot and to increase the penetration performance of the kinetic energy projectiles, the research and development program for composites sabot has been conducted. For carbon/epoxy composites sabot, unidirectional carbon fiber reinforced epoxy prepreg was chosen and thick sectioned composites preforms with the different fiber angles along the circumferential direction of sabot were prepared by compression molding under the careful processing conditions at $150^{\circ}C$ for 1hour with $70kgf/cm^2$ curing pressure. The composites sabot demonstrated a weight reduction by approximately 30% than that of current aluminum sabot. The muzzle velocity of a kinetic energy projectile with composites sabot was measured to be about 63m/s higher than that with aluminum sabot. These results imply that the penetration performance is expected to be considerably increased when the composite sabot is applied to the kinetic energy projectiles.

• KIEAE Journal
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• v.15 no.3
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• pp.57-63
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• 2015

Purpose: Ground source heat pump system has been attracted in the horticulture industry for the reduction of energy costs and the increasing of farm income. Even though it has higher initial costs, if it uses in combination with heat storage, it is able to reduce the initial costs and operate efficiently. In order to have significant effect of heat storage type ground source heat pump system, it is required to design the capacity considering various conditions such as energy load pattern and operating schedule. Method: In this study, we have designed heat storage type ground source heat pump system in 5 cases by the operating schedule, and examined the system to find the most economic and having superb performance regarding the system COP(Coefficient of Performance) and energy consumption, using dynamic energy simulation, TRNSYS 17. Result: Conventional ground source heat pump system has lower energy consumption than heat storage type, but following the result of LCC(Life Cycle Cost) analysis, the heat storage type was more economic due to the initial costs. In addition, it has the most efficient performance and energy costs in the case of the smallest heat storage time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.650-659
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• 2004

Domestic wireless network environment is changing rapidly while adapting to meet service requirements of users and growth of market. As a result, reliable data transmission using TCP is also expected to increase. Since TCP assumes that it is used in wired networt TCP suffers significant performance degradation over wireless network where packet losses are not always result of network congestion. Especially RTO imposes a great performance degradation of TCP. In this paper, we propose DAC$^{＋}$ and EFR in order to prevent performance degradation by quickly detecting and recovering loss without RTO during fast recovery. Compared with TCP NewReno, proposed scheme shows improvements in steady-state in terms of higher fast recovery Probability and reduced response time.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.191-195
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• 2006

It is definitely required to control dispersion of the rocket engine performance in order to accomplish the mission of a launch vehicle successfully. A performance dispersion analysis was conducted for a gas generator cycle liquid rocket engine and the required pressure drops were estimated for engine tunning. As a result, the vacuum thrust dispersion of the engine was from +9.1% to -8.7% and the mixture ratio deviated from +9.7% to -9.6% from the nominal value due to the errors of components and the engine inlet condition of propellants. The required pressure drop in the LOx line to the combustor is higher than in the fuel line for same mixture ratio change.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.1
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• pp.100-109
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• 1993

In this paper, the performance of DS /SSMA BPSK communication system with maximal ratio combining microscopic diversity and selection macroscopic diversity is analyzed. The effects of Rayleigh fading and log normal shadowing on system performance are analyzed, and the validity of microscopic and macroscopic diversity to mitigate the two fading effects are estimated. The increase of the number of chips is effective for mitigating log norma; shadowing, while the increase of the order of microscopic diversity is not. And the higher the standard deviation of shadowing, the more effective the macroscopic diversity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.11
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• pp.600-605
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• 2013

Ground source heat pump systems (GSHP) can achieve higher performance of the system, by supplying more efficient heat source to the heat pump, than the conventional air-source heat pump system. But building clients and designers have hesitated to use GSHP systems, due to expensive initial cost, and uncertain economic feasibility. In order to reduce the initial cost, many researches have focused on the energy-pile system, using the structure of the building as a heat exchanger. Even though several experimental studies for the energy-pile system have been conducted, there was not enough data of quantitative evaluation with economic analysis and comprehensive analysis for the energy-pile. In this study, a prediction method has been developed for the energy pile system with barrette pile, using the ground heat transfer model and ground heat exchanger model. Moreover, a feasibility study for the energy pile system with barrette pile was conducted, by performance analysis and LCC assessment. As a result, it was found that the heat exchange rate of a barrette pile was 2.55 kW, and the payback period using LCC analysis was 8.8 years.

• Korean Journal of Poultry Science
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• v.25 no.3
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• pp.147-155
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• 1998

Dietary levels of fermented poultry manure(FPM) 0%, 5%, 10% and 20% were included in experimental diets. It is to examine the effects of diets containing different levels of FPM on the performance of broiler chicks, including the nutrient availabilities, compared with that of the commercial diet. In order to evaluate the nutritive value of FPM, feeding and metabolism trials were conducted with a total of 160 broiler chicks for a period of 4 weeks. Contents of CP, crude fat, crude ash, crude fiber and NFE of FPM were 19.43, 2.43, 15.44, 16.57 and 38.31 %, respectively. Although there were no statistical difference in the body weight gain among treatments, weight gain achieved by the group fed diets of 5% substitution of FPM was slightly better than others. The amount of feed intake was significantly higher for FPM included groups than for control group, especially in the group fed diets of 10% substitution of FPM. The feed efficiency tended to be better for the control group than the FPM groups. The feed efficiency tended to get worse as the levels of FPM increased. The digestibility of DM, CP and NFE tended to be similar among treatments, especially it was lower for the group fed diets of 20% substitution of FPM compared with that of another groups. In conclusion, up to 10% substitution of FPM to the diet can be utilized effectively as a broiler feed ingredient, without adversely affecting growth performance.

• Journal of Power System Engineering
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• v.17 no.2
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• pp.38-45
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• 2013

In this study, for carrying out the spray and combustion experiment using a Common Rail Direct Injection(CRDI) system, the controller was fabricated to drive a high speed camera, a injector and a laser beam sequentially at a low cost. CB280 module of one-chip micro processer was used for the controller. In order to confirm responsibility and utility of the controller, the current drive performance, the spray behavior and the injection rate were tested and analyzed under various experimental conditions. As this research results, we found that the fabricated controller was able to control the devices for the spray experiment precisely with the input value in program and it had the dynamic load responsibility and repetition. Also, we found that the injection rates of our experimental results were higher than those of others at the same injection pressure and the controller connected with the laser system and the data acquisition system had validity for carrying out the spray visualization experiment.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.1
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• pp.52-62
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• 2004

In this paper we look at the effect of Fringe-Enhanced-Barrier-lowering (FEBL) for high-K dielectric MOSFETs and the dependence of FEBL on various technological parameters (spacer dielectrics, overlap length, dielectric stack, S/D junction depth and dielectric thickness). We show that FEBL needs to be contained in order to maintain the performance advantage with scaled high-K dielectric MOSFETs. The degradation in high-K dielectric MOSFETs is also identified as due to the additional coupling between the drain-to-source that occurs through the gate insulator, when the gate dielectric constant is significantly higher than the silicon dielectric constant. The technology parameters required to minimize the coupling through the high-K dielectric are identified. It is also shown that gate dielectric stack with a low-K material as bottom layer (very thin $SiO_2$ or oxy-nitride) will be helpful in minimizing FEBL. The circuit performance issues with high-K MOS transistors are also analyzed in this paper. An optimum range of values for the dielectric constant has been identified from the delay and the energy dissipation point of view. The dependence of the optimum K for different technology generations has been discussed. Circuit models for the parasitic capacitances in high-K transistors, by incorporating the fringing effects, have been presented.