• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.182-186
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• 2015

We investigated that effects of annealing ambient on the characteristics of functional nano thin film synthesized on glass substrate. The functional nano thin films were annealed by using rapid thermal annealing (RTA) equipment in vacuum, oxygen and nitrogen ambient, respectively. The hardness of the functional nano thin films were measured by a standard hardness testing method (ASTM D3363) such as a H-9H, F, HB and B-6B pencil (Mitsubishi, Japan). Also, the adhesion of the functional nano thin films were measured by a standard adhesion testing method (ASTM D3359) using scotch tape (3M, Korea). The contact angle of the functional nano thin films was measured by a contact angle analyzer (Phoenix 300 Touch, S.E.O.). The optical property of functional nano thin films was measured via UV-visible spectroscopy (S-3100, Scinco).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.929-937
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• 2008

A GPS receiver system utilized on satellite launch vehicles should operate normally under harsh environments as well as high-dynamic conditions. The GPS receiver system to use for range safety of KSLV(Korea Space Launch Vehicle)-I that is the first satellite launch vehicle developed by KARI(Korea Aerospace Research Institute) has been confirmed to survive under the environment of the launcher through extensive terrestrial tests including humidity, high and low temperatures, vacuum, sinusoidal and random vibrations, shocks, acceleration, EMI/EMC(Electromagnetic Interference/ Electromagnetic Compatibility), etc. Several performance tests have been also carried out in order to evaluate tracking capability and accuracy of the GPS receiver under high-dynamic conditions using a GPS signal simulator. Some lessons-learned during development of the GPS receiver system and its special characteristics compared with COTS(Commercial-Off-The-Shelf) GPS receiver systems are described in this paper.

• Journal of Life Science
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• v.8 no.6
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• pp.648-653
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• 1998

The development of natural food preservatives instead of chemical synthetic food preservatives is world wide inte-rest. Authors already investigated that cinnamon bark extract revealed antimicrobial activity against general spoilage microorganisms of food especially its acitivity was stronger against molds than against bacteria. In this paper, authors examined the mirobial flora from the spoiled fish meat paste products and also checked the possibility of cinnamon bark extract food preservative for prolong the shelf life of the fish paste product and breads. The predominat bacteria was Bacillus sp. as about 98% of the total microorganisms isolated from unpacked or packed spoiled fish meat paste products. While molds and yeast are not detected from the vacuum packed products. The MIC(minimum inhibitory concentration) of cinnamon bark extract against the isolated spoilage bacteria and molds was 160~640$\mu\textrm{g}$/$m\ell$ and 40~80$\mu\textrm{g}$/$m\ell$, respectively. When the diluted cinnamon bark extract (the extract : ethanol=1 : 3) was sprayed on the surface of fried fish meat paste product, molds growth was delayed by 2 days at room temperature. The shelf lifes of sandwich and glutinousrice bread which surface sprayed with the diluted extract(1 : 1) was extended by 5 and 7 days, respectively.

• Journal of Astronomy and Space Sciences
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• v.12 no.2
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• pp.234-243
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• 1995

Korea's third rocket, which is currently under development for launch in 1997, is expected to reach as high as 160km and thus, it will provide a good opportunity for the direct measurement of the plasmas in the E-region ionosphere of the Korean peninsula. Langmuir probe techniques, which are the basic tools of the plasma experiment, may yield inaccurate results if they are applied in the conventional form as they are used in the laboratory experiments because of the contamination. In the present paper we study the contamination problem by performing the ground experiments in the vacuum chamber using the contaminated probe. The result show that the contamination effect is reduced when the plasma density is low or when the frequency of the sweep voltage is fast. We propose a modified Langmuir probe based upon our experiments which is suitable for the rocket experiments.

• The Korean Journal of Food And Nutrition
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• v.11 no.3
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• pp.272-277
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• 1998

We carried out separation and guantitation of flavor components by GC about essential oils extracted from deodorized corn oil at the different deodorizing temperature. Flavor components were detected total 16 kinds included aldehydes of 8 kinds, major components were propane, pentane, hexanal etc. These major components content was about 70~75% of the total flavor components. According to rise of deodorizing temperature, both ethane and aldehydes of 8 kinds content were in proportion to increase, but propane, pentane, hexane, octan, pentyl furan content were decreased by contraries, respectively. On the other hand, total flavor component content was appeared the lowest level at 245$^{\circ}C$ treating group, aldehydes content was in proportion to increase according to rise of deodorizing temperature. These phenomenons consider that the undesirable reactions such as partial auto-oxidation, degradation, polymerization and hydrolysis etc. by effecting factors of stripping steam and vacuum degree. Conclusively, deodorizing temperature under high temperature was undesirable for the minimization of off-flavor materials.

• Journal of Powder Materials
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• v.18 no.2
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• pp.141-148
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• 2011

Carbon material shows relatively high strength at high temperature in vacuum atmosphere and can be easily removed as CO or $CO_2$ gas in oxidation atmosphere. Using these characteristics, we have investigated the applicability of carbon mold for precision casting of high melting point metal such as nickel. Disc shape carbon mold with cylindrical pores was prepared and Ni-base super alloy (CM247LC) was used as casting material. The effects of electroless Nickel plating on wettability and cast parameters such as temperature and pressure on castability were investigated. Furthermore, the proper condition for removal of carbon mold by evaporation in oxidation atmosphere was also examined. The SEM observation of the interface between carbon mold and casting materials (CM247LC), which was infiltrated at temperature up to $1600^{\circ}C$, revealed that there was no particular product at the interface. Carbon mold was effectively eliminated by exposure in oxygen rich atmosphere at $705^{\circ}C$ for 3 hours and oxidation of casting materials was restrained during raising and lowering the temperature by using inert gas. It means that the carbon can be applicable to precision casting as mold material.

• Journal of Powder Materials
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• v.21 no.5
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• pp.349-354
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• 2014

This study is a basic research for repair material production which manufactured a Cu repair coating layer on the base material of a Cu plate using kinetic spray process. Furthermore, the manufactured material underwent an annealing heat treatment, and the changes of microstructure and macroscopic properties in the Cu repair coating layer and base material were examined. The powder feedstocks were sphere-shaped pure Cu powders with an average size of $27.7{\mu}m$. The produced repair coating material featured $600{\mu}m$ thickness and 0.8% porosity, and it had an identical ${\alpha}$-Cu single phase as the early powder. The produced Cu repair coating material and base material displayed extremely high adhesion characteristics that produced a boundary difficult to identify. Composition analysis confirmed that the impurities in the base material and repair coating material had no significant differences. Microstructure observation after a $500^{\circ}C/1hr$. heat treatment (vacuum condition) identified recovery, recrystallization and grain growth in the repair coating material and featured a more homogeneous microstructure. The hardness difference (${\Delta}H_v$) between the repair coating material and base material significantly reduced from 87 to 34 after undergoing heat treatment.

• Journal of Astronomy and Space Sciences
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• v.31 no.2
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• pp.177-186
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• 2014

The Immersion Grating Infrared Spectrometer (IGRINS) is a near-infrared wide-band high-resolution spectrograph jointly developed by the Korea Astronomy and Space Science Institute and the University of Texas at Austin. IGRINS employs three HAWAII-2RG Focal Plane Array (H2RG FPA) detectors. We present the design and fabrication of the detector mount for the H2RG detector. The detector mount consists of a detector housing, an ASIC housing, a Field Flattener Lens (FFL) mount, and a support base frame. The detector and the ASIC housing should be kept at 65 K and the support base frame at 130 K. Therefore they are thermally isolated by the support made of GFRP material. The detector mount is designed so that it has features of fine adjusting the position of the detector surface in the optical axis and of fine adjusting yaw and pitch angles in order to utilize as an optical system alignment compensator. We optimized the structural stability and thermal characteristics of the mount design using computer-aided 3D modeling and finite element analysis. Based on the structural and thermal analysis, the designed detector mount meets an optical stability tolerance and system thermal requirements. Actual detector mount fabricated based on the design has been installed into the IGRINS cryostat and successfully passed a vacuum test and a cold test.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.596-603
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• 2020

In this study, a mathematical model for optimal operation of the fusion fuel cycle is developed based on scheduling approach. The fusion fuel cycle consists of a system for storing and supplying deuterium and tritium, and receiving and separating process after the fusion reaction. Except that tritium is a radioactive material, most of these processes consist of catalytic reactions and separation process. For these reasons, it is possible to apply scheduling approach which is also widely utilized to chemical plants to derive the optimal operating scenarios. The developed model determined the optimal regeneration cycle to minimize the amount of tritium inside the vacuum pumps. Based on the characteristics of various device in the fusion reactor, the optimal tritium plant operation scenario is evaluated. The formulated model was applied to the actual tokamak scenario and utilized to analyze the fuel flow and balance of ITER fuel cycle.

• Journal of Korean Library and Information Science Society
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• v.15
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• pp.179-205
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• 1988

The purpose of this research is to analyze the differences between electronical engineering class in KDC3 and electronical engineering class in DDC 19. The results of the study can be summarized as follows ; 1. The characteristics of the classification items in classification schemes of the electronical engineering fields is that KDC is classified by the vacuum tubes, electron tubes, special tubes, computers etc and DDC is classified by the microwave electronics, short-and long-wave electronics, X-ray and gamma-ray electronics, computers etc. 2. There is a blank in KDC and there are three blanks in DDC of the electronical engineering fields, but the total classification items number is much more in DDC than in KDC. This means that DDC is more classified than in the special classification items. 3. Classification items over 70% in the total classification items of computer fields in KDC, are classified a classification items of the short-and long-wave electronics in DDC. 4. There is a blank of computer fields in KDC and there are three blanks of computer fields in DDC, but the total classification items are many eighteen items. This means that DDC is more classified than KDC. 5. The sections of computers in DDC were established the 621.38195 classification item and the subsection of analogue computers in DDC were established the 621.381957 classification item and the subsection of digital computer in DDC were established the 621.381958 classification item. As we have seen, because of the development in technology and the subdivision of knowledge, the number of items is increased, and the terminology also become simplified and specified in the field of electronic engineering in KDC and DDC.