• Journal of Hydrogen and New Energy
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• v.12 no.1
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• pp.65-73
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• 2001

Carbon nanotubes were prepared by catalytic decomposition of $CH_4$ using Ni-MgO catalyst at various temperatures. $H_2$ effect on crystallinity and morphology during the synthesis of carbon nanotubes was investigated. The crystallinity and morphology were characterized by SEM, TEM, XRD, TGA, and Raman spectroscopy. In addition, the hydrogen adsorption properties were evaluated by PCT measurement in a hydrogen pressure range between 1 and 120 bar. The optimal synthesis temperature of carbon nanotubes was elevated in the presence of $H_2$, although significant difference of carbon nanotube morphology was not found. It is believed that hydrogen served as self-cleaner mops the amorphous carbon on the catalyst surface. It is proved that the carbon nanotubes have multi-walled structure, short length with a outer diameter of 20 ~40nm and open tips after elimination of the catalyst. The amount of hydrogen adsorbed in carbon nanotubes is increased as the pressure of hydrogen is increased and reaches 1.3 wt % under the hydrogen pressure of 120 bar at room temperature.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.131-139
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• 2010

Avionics technologies have been developed with a development of an airplane since 1903. Historically, radio communication was started in 1910's, radio navigations in 1920's and autopilot was applied first in 1930's. Glass cockpit was initiate on MD-80 in 1979 first and now spreaded widely and similar with GPS navigation. Avionics in modern aircraft has a great deal of importance in view of flight safety and maintaining comfortableness. As avionics develops, so do the certification technologies. This paper introduces update avionics certification technologies developed recently.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.4
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• pp.349-358
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• 2023

The Satellite-Based Augmentation System (SBAS) plays a significant role in the fields of aviation and navigation: it corrects signal errors of the Global Navigation Satellite System (GNSS) and provides integrity information to facilitate precise positioning. These SBAS systems have been adopted as international standards by the International Civil Aviation Organization (ICAO). In recent SBAS system design, the Minimum Operational Performance Standards (MOPS) defined by the Radio Technical Commission for Aeronautics (RTCA) must be followed. In October 2014, South Korea embarked on the development of a Korean GPS precision position correction system, referred to as Korea Augmentation Satellite System (KASS). The goal is to achieve APV-1 Standard of Service Level (SoL) service level and acquisition of CAT-1 test operating technology. The first satellite of KASS, KASS Prototype 1, was successfully launched from the Guiana Space Centre in South America on June 23, 2020. In December 2022 and June 2023, the first and second service signals of KASS were broadcasted, and full-scale KASS correction signal broadcasting is scheduled to start at the end of 2023. The aim of this study is to analyze the precision of both the GNSS system and KASS system by comparing them. KASS is also compared with Japan's Multi-functional Satellite Augmentation System (MSAS), which is available in Korea. The final objective of this work is to validate the usefulness of KASS correction navigation in the South Korean operational environment.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.237-242
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• 2004

Recombinant human ferritin homopolymers (rHF and rLF) were successfully produced in the Saccharomyces cerevisiae Y2805, which was transformed with human ferritin H or L-chain genes, respectively. In order to characterize the molecular properties of the recombinant ferritins in relation to mineralization, the proteins were isolated and apoferritins were prepared. The apoferritins were reconstituted with 2000 Fe atoms per protein molecule under various experimental conditions (the concentration of the protein, the buffer concentration of the MOPS buffer, the total volume of the reaction and the reconstitution method). The structure and composition of the iron cores formed in the ferritins were examined using transmission electron microscopy. The recombinant ferritins behaved in a similar manner to other mammalian ferritins in accumulating iron in the core. Proteins of rHF and rLF showed varying reconstitution yields of 37-72% depending on the reaction conditions. In general, the rHF showed higher reconstitution yield than the rLF at the protein concentrations and the reaction volumes we examined. Iron cores with a similar mean particle size were obtained in the rHF, rLF and horse spleen ferritin reconstituted at a protein concentration of 1.0 mg/mL. Electron diffraction of all the three ferritins showed 2-3 diffuse lines, with d-spacings corresponding to those of the mineral ferrihydrite with a limited crystallinity.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2266-2270
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• 2007

Electron transfer of a redox protein at a bare gold electrode is too slow to observe the redox peaks. A novel Nafion-riboflavin functional membrane was constructed during this study and electron transfer of cytochrome c, superoxide dismutase, and hemoglobin were carried out on the functional membrane-modified gold electrode with good stability and repeatability. The immobilized protein-modified electrodes showed quasireversible electrochemical redox behaviors with formal potentials of 0.150, 0.175, and 0.202 V versus Ag/AgCl for the cytochrome c, superoxide dismutase and hemoglobin, respectively. Whole experiment was carried out in the 50 mM MOPS buffer solution with pH 6.0 at 25 oC. For the immobilized protein, the cathodic transfer coefficients were 0.67, 0.68 and 0.67 and electron transfer-rate constants were evaluated to be 2.25, 2.23 and 2.5 s?1, respectively. Hydrogen peroxide concentration was measured by the peroxidase activity of hemoglobin and our experiment revealed that the enzyme was fully functional while immobilized on the Nafion-riboflavin membrane.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.727-736
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• 2009

In this paper, the $arccos(cos^{-1})$ arithmetic unit for mobile graphics accelerator is designed. The mobile vector graphics applications need tight area, execution time, power dissipation, and accuracy constraints compared to desktop PC applications. The designed processor adopts 2nd-order polynomial approximation scheme based on IEEE floating point data format to satisfy speed and accuracy conditions and reduces area via hardware sharing structure. The arccosine processor consists of 15,280 gates and its estimated operating frequency is about 125Mhz at operating condition of $0.35{\mu}m$ CMOS technology. Because the processor can execute arccosine function within 7 clock cycles, it has about 17 MOPS(million arccos operations per second) execution rate and can be applicable to mobile OpenVG processor. And because of its flexible architecture, it can be applicable to the various transcendental functions such as exponential, trigonometric and logarithmic functions via replacement of ROM and minor hardware modification.

• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.463-474
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• 2004

Game theory is a method of mathematical analysis developed to study the decision making process. In 1928, Von Neumann mathematically proved that every two-person, zero-sum game with many pure finite strategies for each player is deterministic. In the early 50's, Nash presented another concept as the basis for a generalization of Von Neumann's theorem. Another central achievement of game theory is the introduction of evolutionary game theory, by which agents can play optimal strategies in the absence of rationality. Through the process of Darwinian selection, a population of agents can evolve to an Evolutionary Stable Strategy (ESS) as introduced by Maynard Smith in 1982. Keeping pace with these game theoretical studies, the first computer simulation of coevolution was tried out by Hillis. Moreover, Kauffman proposed the NK model to analyze coevolutionary dynamics between different species. He showed how coevolutionary phenomenon reaches static states and that these states are either Nash equilibrium or ESS in game theory. Since studies concerning coevolutionary phenomenon were initiated, there have been numerous other researchers who have developed coevolutionary algorithms. In this paper we propose a new coevolutionary algorithm named Game theory based Coevolutionary Algorithm (GCEA) and we confirm that this algorithm can be a solution of evolutionary problems by searching the ESS. To evaluate this newly designed approach, we solve several test Multiobjective Optimization Problems (MOPs). From the results of these evaluations, we confirm that evolutionary game can be embodied by the coevolutionary algorithm and analyze the optimization performance of our algorithm by comparing the performance of our algorithm with that of other evolutionary optimization algorithms.

• KSBB Journal
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• v.16 no.4
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• pp.398-402
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• 2001

Enzymatic hydrolysis of agar was carried out continuously to produce agarooligosaccharides by immobilized agarase in Packed-Bed Reactor. The reactor was constructed using a acryl tube with an internal diameter of 10 mm and a useful height of 140 mm. The Packed-Bed Reactor was 11 mL reactor volume as its length : diameter ratio was 14 : 1. The operation condition of reaction was performed with an 1 g/L agar concentration at 40$^{\circ}C$, 10 mM MOPS buffer(pH 7.0) and with the flow rate 3 mL∼48 mL/h at a dilution rate of 1.09∼5.45 h$\^$-1/. The hydrolysis products was identified DP6, DP4 and DP2 by HPLC. The conversion rate of agar was about 80% and amount of total agarooligosaccharide was 0.88 mg/mL at Packed-Bed Reactor.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.253-261
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• 2004

Game theory is mathematical analysis developed to study involved in making decisions. In 1928, Von Neumann proved that every two-person, zero-sum game with finitely many pure strategies for each player is deterministic. As well, in the early 50's, Nash presented another concept as the basis for a generalization of Von Neumann's theorem. Another central achievement of game theory is the introduction of evolutionary game theory, by which agents can play optimal strategies in the absence of rationality. Not the rationality but through the process of Darwinian selection, a population of agents can evolve to an Evolutionary Stable Strategy (ESS) introduced by Maynard Smith. Keeping pace with these game theoretical studies, the first computer simulation of co-evolution was tried out by Hillis in 1991. Moreover, Kauffman proposed NK model to analyze co-evolutionary dynamics between different species. He showed how co-evolutionary phenomenon reaches static states and that these states are Nash equilibrium or ESS introduced in game theory. Since the studies about co-evolutionary phenomenon were started, however many other researchers have developed co-evolutionary algorithms, in this paper we propose Game theory based Co-Evolutionary Algorithm (GCEA) and confirm that this algorithm can be a solution of evolutionary problems by searching the ESS.To evaluate newly designed GCEA approach, we solve several test Multi-objective Optimization Problems (MOPs). From the results of these evaluations, we confirm that evolutionary game can be embodied by co-evolutionary algorithm and analyze optimization performance of GCEA by comparing experimental results using GCEA with the results using other evolutionary optimization algorithms.

• Korean journal of food and cookery science
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• v.19 no.3
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• pp.339-353
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• 2003

The rapid increase in food borne illness outbreaks in Korea has been one of the major threats to the Nation's Health. Foodservice establishments have been identified as the major place for these outbreaks, mainly due to the lack of sanitary management and sanitary facility management practices. The purposes of the study were to develop hospital foodservice facility evaluation tools, based on the general HACCP-based standards and guidelines, for hospital food service establishments, to ensure the safety of these foodservices and to reduce the risk of food home illness. The scope of this study included: 1) an assessment of the current foodservice sanitation practices and managements for 6 general hospitals, with more than 400 beds, and 3 general hospitals, with less than 400 beds; 2) the development of foodservice establishments sanitation evaluation tools and sanitation standards, based on the HACCP system. The survey data showed varied results between the hospitals surveyed. Most of the hospital foodservice operations had many problems with ventilation and the plumbing. The total dimensional mean scores for the hospitals with more than 400 beds and less than 400 beds were 31.5 and 27.0, respectively. The highest dimension scores were for the water supply facility and lighting, with the lowest for insect and rodent control and toxic materials management. The levels of the mean scores were very low, especially for the general hospitals with less than 400 beds. These low mean scores may have arisen from critical problems within the hospital foodservice operations. The most needed facility management items for improvement were: storage shelf should be spaced 6 inches from the floor and walls, the use of three compartment sinks, utility sinks and cleaning facilities, with a floor drain for cleaning mops or liquid wastes, a ventilation hood designed to prevent dripping onto food, cooking facilities should be disassembled for washing and sanitizing, a separated hand washing sink and a sanitized food board for each area should be provided, all toxic material must have warning labels attached, and be stored in an area away from food preparation under padlock. The evaluation tool consisted of 14 dimensions, with 65 check-off items. The results of this study will provide basic facilities' guidelines to regulators, or foodservice industry personnel, wishing to build, or expend, and establish an efficient flow of food. As a result, food borne illnesses will be effectively prevented, and the Nation's health will be promoted for the development of their own sanitation standards, with a checklist for the safe production of foods.