• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.4
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• pp.28-43
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• 2022

To minimize such loss due to aging, research on energetic materials is being actively conducted though, there are difficulties in identifying the comprehensive aging mechanisms as they focused on the respective materials. In this study, thermal and surface analysis were performed on energetic materials composed of metals(W, Ti, and Zr) and KClO₄ oxidizer to solve the blind spots of this aging study. It was newly found that the metals in the hygrothermally aged compounds can cause significant changes in performance. For example, the growth in the thickness of the oxide film on the metals led to an increase in the average value of activation energy(E_α). In addition, the standard deviation of E_α tends to dependent on the type of metal, which is due to the difference in electronegativity.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.7
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• pp.982-992
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• 2011

Three experiments were carried out to determine the nutritional value and to verify the pig performance in growing and finishing phases (30 to 90 kg) fed on diets containing common corn (CC), high-lysine corn (HLC) and high-oil corn (HOC). In the total digestibility trial (Exp. I) 12 barrows were used. Values of digestible energy (DE) and metabolizable energy (ME) as-fed basis for CC, HLC and HOC, were: 3,396 and 3,275 kcal/kg; 3,248 and 3,139 kcal/kg; 3,445 and 3,308 kcal/kg, respectively. In order to determine the apparent and true ileal digestibility coefficients of amino acids, as well as the values of true digestible amino acids of the CC, HLC and HOC, an ileal digestibility trial was done (Exp. II) with T-cannulated barrows ("T" simple). The treatments consisted of three diets, with one of them as the sole source of protein (CC, HLC and HOC). In the performance experiment (Exp. III), 36 crossbred pigs, allotted in a completely randomized design with three treatments and 12 replications were used. Treatments consisted of three diets: 1 - CC; 2 - HLC and 3 - HOC. It was observed no difference for performance and carcass variables among the corns with different nutritional profiles. Results of the three experiments highlighted the importance of segregating corns in their real chemical and energetic composition as well as the values of true digestible amino acids for formulating diets for growing and finishing pigs.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.10
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• pp.1409-1418
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• 2001

Two trials were carried out during two different grazing seasons to evaluate effect of grass silage supplementation, when amount of pasture is limited on dry matter intake (DMI), milk production, and gross energetic efficiency (GEE) of grazed lactating cows on a high forage-based diet. Fifty-one Holstein cows were randomly assigned to one of two dietary treatments: high pasture group or high silage group. In the spring flush, pasture and silage DMI, milk yield, milk fat percentage, and GEE were not different between the dietary groups. After the spring flush, pasture and silage DMI were higher for the high silage group than for the high pasture group. After the spring flush, although these were the higher total DMI of the high silage group than the high pasture group, milk yield was significantly (p<0.05) higher for the high pasture group than the high silage group. Milk fat percentage tended to be higher for the high silage group than the high pasture group. The GEE was significantly (p<0.05) higher for the high pasture group than the high silage group during after the spring flush. This study indicated that supplementation of grass silage, especially after the spring flush, can have a significant effect of increasing of forage intake and maintenance of the milk fat percentage; but not increase milk yield and GEE.

• Journal of Astronomy and Space Sciences
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• v.35 no.3
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• pp.175-183
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• 2018

Many recent satellites have mission periods longer than 10 years; thus, satellite-based local space weather monitoring is becoming more important than ever. This article describes the instruments and data applications of the Korea Space wEather Monitor (KSEM), which is a space weather payload of the GeoKompsat-2A (GK-2A) geostationary satellite. The KSEM payload consists of energetic particle detectors, magnetometers, and a satellite charging monitor. KSEM will provide accurate measurements of the energetic particle flux and three-axis magnetic field, which are the most essential elements of space weather events, and use sensors and external data such as GOES and DSCOVR to provide five essential space weather products. The longitude of GK-2A is $128.2^{\circ}E$, while those of the GOES satellite series are $75^{\circ}W$ and $135^{\circ}W$. Multi-satellite measurements of a wide distribution of geostationary equatorial orbits by KSEM/GK-2A and other satellites will enable the development, improvement, and verification of new space weather forecasting models. KSEM employs a service-oriented magnetometer designed by ESA to reduce magnetic noise from the satellite in real time with a very short boom (1 m), which demonstrates that a satellite-based magnetometer can be made simpler and more convenient without losing any performance.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.8-13
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• 2018

Zirconium potassium perchlorate(ZPP) is an igniter composed of potassium perchlorate as an oxidizing agent and zirconium as a fuel with a Viton binder. ZPP has been used to provide an ignition source in the aerospace, propulsion, and automotive industries. This study investigates the manufacturing process and characteristics of ZPP, such performance and shape/calorimetry/pressure characteristics with respect to pyrotechnic mechanical device(PMD). During the production of ZPP, the mixing process was designed to produce uniform particle size and shape by mixing the raw materials at high speed.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.56-61
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• 2002

The hexanitrohexaazaisowurtzitane(HNIW) is a polycyclic caged nitramine oxidizer. For most existing weapons systems, the most critical ingredient in explosive and propellant applications is the oxidizer, HNIW, with its increase in performance output and energy capabilities for future in explosive and propellant systems. Two new polyacylhexaazaisowurtzitanes were synthesized. Pentaacetylhexaaza-isowurtzitane(PAIW) or pentaacetylformylhexaazaisowurtzitane(PAFIW) can be a precursor in the preparation of HNIW, recently developed highly energetic material.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.686-688
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• 2013

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.885-890
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• 2006

This study presents analysis results for the hybrid system combining solid oxide fuel cell and gas turbine. Two different system layouts(an ambient pressure system and pressurized system) are considered and their design performance are comparatively investigated taking into account critical design factor, the most critical parameter such as turbine inlet temperature, gas turbine pressure ratio, temperature difference at the fuel cell and fuel cell operating temperature are considered as design constraints. Performance variations according to system layout and design parameters are examined in energetic view point.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.84-90
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• 2017

Explosive bolt is coupled in a variety of guided weapons and space projectiles, to perform the separation function. Thus, the role of the explosive bolt in guided weapons systems is very important, as it can cause failure of the entire system in the case of mission failure. For this reason, the design life prediction for explosive bolt is highly and frequently required recently, but its accurate prediction method has not been presented. In order to apply the existing accelerated aging process, we should know the activation energy and the acceleration factor of the explosive bolt. Since the information required for accelerated aging is not presently secured, it is difficult to predict the design life of explosive. Thus, in the present study, we have evaluated the performance of actual explosive bolts in the condition of natural aging over 10 years in order to present a minimum design life.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.31-37
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• 1999

Recently, the development of propellant trends toward minimum smoke signature, insensitivity and high performance. PSAN has been used as a oxidizer for less sensitive minimum smoke propellant. Unfortunately, it provides low performance to propellant. Energetic polymers such as GAP and PGN are frequently proposed for use in minimum smoke Propellants to overcome the energy Penalty imposed by using AN as the oxidizer. In this study the mechanical properties, glass transition temperature and viscosity of PGN and EPGN binder were investigated.