• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1316-1322
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• 2005

Specially, though electronic commerce and electron signature technology through internet rose, PKI (Public Key Ifrastructure) is one of technologies. PKI brought several kind of new standards in encryption base technology. In spite of several kind of standardizations consist lively, shortcoming of solutions that apply PKI is expensive and slow. If main interest of encryption technology including PKI is the fast speed and security that improve, this is very serious problem. The various kinds alternatives about these problem are presented. But, we must consider about replace expense and stability etc. still. So, I propose that use suitable encryption policy by method to solve such problem. I improved some problems of existent PKI structure. Subject of this treatise designs and embody communication component could use easily and simply short message communication or simplicity way encryption communication.

• Korean Journal of Materials Research
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• v.28 no.1
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• pp.43-49
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• 2018

The demand for energy storage devices capable of operating at high temperatures is increasing. In order to operate at high temperatures, a device must have excellent thermal stability and no risk of explosion. Ionic liquids are electrolytes that satisfy the above conditions, and studies on improving their performance have attracted great interest. Here, we report the results of a study on the fabrication of a supercapacitor that has a composite electrolyte prepared by dispersing fumed silica in an ionic liquid. The fumed silica filler exhibits improved ionic conductivity and lower interfacial resistance. In particular, the silica nanoparticles with diameters of 10 nm exhibit better electrochemical properties than fillers of other diameters and have excellent device performance of 33 times higher than the pristine ionic liquid at high temperatures. This study can be used to improve the electrolytes of electrochemical devices, such as the next generation battery or lithium ion battery.

• KSBB Journal
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• v.29 no.4
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• pp.239-243
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• 2014

Recently, there is a growing interest in efficient biomass pretreatment and saccharification processes to produce biofuels and biochemicals from renewable non-food biomass resources. In this study, glucose was produced from cellulose by immobilizing cellulase enzyme on chitosan beads which was reported to have high pH and temperature stability. The immobilized amounts of cellulase on chitosan beads linearly increased with increasing the concentrations of cellulase solution. The glucose production increased to 7.2 g/L from 1% carboxymethyl cellulose (CMC) substrate when immobilized at 20% cellulase solution. The maximum specific activity was 0.37 unit/mg protein when immobilized at 8% cellulase solution. At pH 7 and $37^{\circ}C$, the optimum reaction composition was 0.5 g beads/L from 1% CMC substrate. At this condition, the conversion to glucose completed at ca. 20 min.

• The Journal of Asian Finance, Economics and Business
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• v.4 no.3
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• pp.19-26
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• 2017

Banks play a crucial role in bringing stability and economic development through their expected contribution in proper financial resource mobilisation across the economy. Despite the importance, there is little focus in recent literature which provided the empirical evidence how the global financial crisis affect the bank efficiency in Bangladesh. Thus, this paper aims to examine the effect of the global financial crisis and other factors on the efficiency of Bangladesh commercial banks. By employing the Data Envelopment Analysis (DEA) method, we computed the technical efficiency of individual banks operating in the Bangladesh banking sector during 2000 to 2013. The empirical findings indicate that the Bangladesh banking sector has exhibited the highest efficiency level during 2001, while efficiency seems to be at the lowest level during 2010. The study finds that crisis along with bank size, capital adequacy ratio, return on average equity and real interest rate have a significant effect on bank efficiency in Bangladesh. In order to keep the sound financial development of Bangladesh, banks operating in the Bangladesh banking sector have to consider all the potential technologies which could improve their profit efficiency levels, since the main motive of banks is to maximise shareholders' value or wealth through profit maximisation.

• Korean Security Journal
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• no.3
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• pp.175-204
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• 2000

In modern society, a spontaneous phenomenon that community residents' participation in crime prevention sphere is increasing now due to the recognition that it is extremely difficult to control crime only by the limited official power(police) is spreading in the society. In the consideration of crime occurrence, the fear of crime does not belong to a certain person any more, but it turns to a matter of common interest for all people. If the recognition of community problems is well understood and analysed, the effect of community residents' participation in crime prevention will appear more eminent and definite. For a long period of time, thanks to the community residents' participation in crime prevention, it has been possible to sustain safety and stability of local community. Ultimately not only the police could reduce the crime problems but local community could decrease a fear of crime. In this study, for maximized effect of crime prevention, it is focused on the role of the community residents' participation in crime prevention. For desirable interrelations among service group and residents, police, first the review of situational crime prevention and community crime prevention theory was studied. And the community residents participation to crime prevention activity in U.S.A, Japan etc was reviewed. By interviewing actual participants in community crime prevention activity, the problems and countermeasures of the community residents' participation in crime prevention activity and desirable direction was suggested

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.438-438
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• 2011

White light-emitting diodes (LEDs), the so-called next-generation solid-state lighting, offer benefits in terms of reliability, energy-saving, maintenance, safety, lead-free, and eco-friendly. Recently, rare-earth-doped oxynitride or nitride compounds have attracted a great deal of interest as a photoluminescent material because of their unique luminescent property, especially for white LEDs applications. Ce doped ${\beta}$-SiAlON has been studied as a wavelength conversion phosphor in white LEDs thanks to its high absorption rates, high quantum efficiency, and excellent thermal stability. Previously researches were not enough to understand the detail mechanism and characteristics of ${\beta}$-SiALON. The bandgap structures and electronic structures were not exact due to limitation of calculation methods. In this study, to elucidate the Ce doping effect on the SiAlON system, accurate band structures and electronic structure of the Ce doped ${\beta}$-SiAlON was intensively investigated using density functional theory calculations. In order to get a better description of the band gaps, MBJLDA method were used. We have found a single Ce atom site in ${\beta}$-SiAlON super cell. Furthermore, the density of state, band structure and lattice constant were intensively investigated.

• 전기의세계
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• v.26 no.2
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• pp.99-103
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• 1977

The object of this work is to study an optimal design problem of the proportional load-frequency controller for the single-control area power system. The selfservice power station is still a popular means as a power supplying source on ships or in a certain manufacturing area. The power system of this kind can be formulated as a single control-area system and it attracts a certain academic interest in controlling the system frequency under disturbances. In this paper, the single control-area system is mathematically formulated as a linear, time-invariant system in state-space under certain assumptions. The optimal proportional control law and the realization of the controller in closed loop-version is studied so that the final system designed can attain the system frequency to the nominal stationing value after the small load-disturbance. As in general cases of optimal design problems, the performance index is assumed to be quadratic in states and the control effort, and the infinite time control process is assumed in this work. The final control system realized depicts certain improvements in case study; in stability, transient responses and in steady-state frequency deviation, even though the steady state error did not attain the zero value.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.107-118
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• 2017

As the interest in lunar exploration increases, a throttleable engine is regarded as a important technology. Variable area injectors have been identified to be the most reliable throttling method. Pintle injector is a representative injector of the variable method. It has a simple design and inherent combustion stability. Therefore, it is necessary to research the pintle injector. The present study investigates the concept of the injector, the design factors, and the latest development trends for pintle injector design.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1802-1808
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• 2008

Recent interest in the construction sector, rising about the environment and eco-friendly recycled material resources, and increase the development of method But despite these efforts, and the diverse functional and structural changes in the structure can not be an appropriate response to the functional waterproof structural changes in the structures and appropriate response Diversification does not waterproof and functional issues such as durability, and which are occurring due to the structure to secure stability and durability, never sees the conservative economic losses due to import constructability reinforcement situation. Therefore, this study applies to structure the existing waterproof method (hereinafter referred to as structures water-resistant methode), and to review recent issues of environmental pollution and resource waste, and taking on environmental issues, such as Revelation and functional Inorganic mixed in a way to leverage the manufacturing water-resistant material "Re Inorganic, functional and environmentally friendly high-viscosity mix asphalt waterproof rubber reinforcements, and taking conservative" for the characterization and performance assessment to the issues raised by the structure and whether the judge would respond.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.61
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• pp.165-190
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• 2014

The purpose of this study is to measure the trade insurance's macroeconomic effects by analyzing the causality between major economic variables(GDP per capita, market interest rate, inflation, unemployment rate, exchange rate) and trade insurance variable. I conducted empirical analyses using First-difference GMM(Generalized Method of Moments), System GMM and Panel-VAR Model, with panel data from 11 countries(Korea, United States, Japan, BRICs, Indonesia, Singapore, Hong Kong, Vietnam) between 1992 and 2011. There are several important findings. Above all, Trade insurance is positively and significantly related to GDP. This results show that trade insurance serves to increase economic growth. In other words, trade insurance leads to economic growth by helping increase GDP per capita. Especially, trade insurance negatively related to unemployment rate, it is for sure that trade insurance contribute to decrease unemployment rate. And trade insurance helps control of inflation. It is also confirmed that trade insurance contributes to price stability, which in turn serves to stabilize the overall economy. And this research finds as uncertainty in the market increases, seen it as increase of exchange rate, increasing trade insurance supply is stabilize the exchange rate.