• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.1
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• pp.17-30
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• 2016

In this paper, we propose an efficient public key trace and revoke scheme. An trace and revoke scheme is a broadcast encryption scheme which has a tracing and revocation algorithm. It would maintain security of the scheme to revoke pirate keys which are colluded by malicious users. In addition, property of revocation can be applied to various circumstances because it can help cipher text delivered to certain users who are supposed to. In this paper, we would change the scheme[Augmented broadcast encryption scheme] based on the bilinear groups of the composite order into that of prime order and we can improve the size of public key, secret key, ciphertext considerably. Furthermore, we define property of revocation precisely, so we can obtain the result that the scheme with limited revocation can be expanded to have a full revocation. This paper can be easily applied to the organization such as government, military, which has a hierarchical structure.

• Korea and Global Affairs
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• v.1 no.1
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• pp.97-114
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• 2017

This article aims for searching the clue of North Korea nuke-problem by understanding it contextually. We must see this from the beginning as many trials in settling the problem have failed. North Korea nuke-problem is related to the change of international implication as well as the domestic process of its development. At first, it started from the regime survival, which evolved with the effect of learning. During the Cold War, its development had combined the principle of 'self-defense' because of Sino-Russia conflict. Particularly, its meaning varied dramatically due to the collapse of Cold War system plus the advent of post-Cold War system. North Korea nuclear program has became a global problem based on the deterioration of North Korea's security milieu and Bush administration's policy. Therefore, the area of common solution for NK nuke-problem must be found in the context of regime survival and the change of its meaning by continual convergence effort.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.4
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• pp.551-558
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• 2016

We analyzed wind speed over South Korea for HALE UAV(High Altitude Long Endurance Unmaned Aerial Vehicle) flight safety. Annual variation of wind speed at 200 hPa showed that winter season was stronger than summer. According to latitude, wind speeds in January and August were found to be $52{\sim}74m\;s^{-1}$ and $15{\sim}26m\;s^{-1}$, respectively. Wind speed was stronger(weaker) at lower latitudes than higher latitudes in winter(summer). Frequency(%) of wind speed less than threshold value($18m\;s^{-1}$) for the operation date was investigated. The days showing the frequency greater than 60 % in all altitudes of surface ~ 50 hPa showed the range of 1 ~ 33 days at 7 stations. Operation date was the longest period at Gosan. The appropriate date of HALE UAV operation at Gosan and Osan is considered as the middle of July ~ middle of August and end of July ~ early August, respectively. These results can be used to determine the operation date of HALE UAV.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1425_1426
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• 2009

In this study, commercially available polyethylene terephthalate(PET), which is widely used as a substrate of flexible electronic devices, was modified by dielectric barrier discharge(DBD) method in an air condition at atmospheric pressure, and aluminium - doped zinc oxide (ZnO:Al) transparent conducting film was deposited on PET substrate by r. f. magnetron sputtering method. Surface analysis and characterization of the plasma-treated PET substrate was carried out using contact angle measurements, X-ray Photoelectron Spectroscopy(XPS) and Atomic Force Microscopy (AFM). Especially the effect of surface state of PET substrate on some important properties of ZnO:Al transparent conducting film such as electrical and morphological properties and deposition rate of the film, was studied experimentally. The results showed that the contact angle of water on PET film was reduced significantly from $62^{\circ}$ to $43^{\circ}$ by DBD surface treatment at 20 min. of treatment time. The plasma treatment also improved the deposition rate and electrical properties. The deposition rate was increased almost linearly with surface treatment time. The lowest electrical resistivity as low as $4.97{\times}10^{-3}[\Omega-cm]$ and the highest deposition rate of 234[${\AA}m$/min] were obtained in ZnO:Al film with surface treatment time of 5min. and 20min., respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.4
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• pp.368-374
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• 2008

The basic Trainer Aircraft of The Korean Air force KT-1/KO-1, which was designed and developed by Korean Technology has been a primary candidate as a replacement for the aging basic trainer or armed version for surface support operation for the nations such as Mexico, Philippine, Turkey, Venezuela and etc. In this study, competitors for the same class aircraft and the present operational status of the basic trainer of the world were identified and the fade out periods were also predicted. The result of this market analysis showed the required number of aircraft by the year 2025 for 33 countries as 4500. The exportable number of KT-1 aircraft was predicted considering the political/diplomatical environments, economic environment and also by the ability of producing same class aircraft of the country.

• Environmental Engineering Research
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• v.12 no.4
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• pp.176-193
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• 2007

The ability to measure groundwater contaminant flux is increasingly being recognized as crucial in order to prioritize contaminated site cleanups, estimate the efficiency of remediation technologies, measure rates of natural attenuation, and apply proper source terms to model groundwater contaminant transport. Recently, a number of methods have been developed and subsequently applied to measure contaminant mass flux in groundwater in the field. Flux measurement methods can be categorized as either point methods or integral methods. As the name suggests, point methods measure flux at a specific point or points in the subsurface. To increase confidence in the accuracy of the measurement, it is necessary to increase the number of points (and therefore, the cost) of the sampling network. Integral methods avoid this disadvantage by using pumping wells to interrogate large volumes of the subsurface. Unfortunately, integral methods are expensive because they require that large volumes of contaminated water be extracted and managed. Recent work has investigated the development of an integral method that does not require extraction of contaminated water from the subsurface. We begin with a review of the significance and importance of measuring groundwater contaminant mass flux. We then review groundwater contaminant flux measurement methods that are either currently in use or under development. Finally, we conclude with a qualitative comparison of the various flux measurement methods.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.207-212
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• 2010

Purpose: Rigid gas permeable (RGP) contact lenses, based on fluorosilicone acrylate, were treated with plasma in air. Methods: The chemical compositions were analyzed by using X-ray photoelectron spectroscopy (XPS), the surface morphology and roughness of RGP contact lenses were observed by using atomic force microscopy (AFM), and the wettability changes were estimated by wetting angle measurement. Results: As the contact lenses were treated by the plasma, the F contents decreased significantly, and the O and Si contents increased on the surface. The number of oxygen-containing hydrophilic radicals (C-O and Si-O) increased greatly, the hydrophobic surface decreased, and the wetting angle increased. But the C-O bonds created with exchange of the fluorine did not increase a wettability. The surface compositions were not remarkably changed for the 6 months after plasma treatment, but the wetting angle increased again. Conclusions: It was considered that the improved wettability of the RGP contact lenses of high fluorine content after plasma treatment was affected by the activation of surface, the increase of Si-O, and the decrease of hydrophobic surface.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.47-54
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• 2003

Climate of Mongolia is a driven force on natural conditions as well as socio-economic development of the country. Due to the precariousness of climate conditions and traditional economic structure, natural disasters, specially disasters of meteorological and hydrological origin, have substantial effect upon the natural resources and socio-economic sectors of Mongolia. Mongolia's climate is characterized by high variability of weather parameters, and high frequency and magnitude of extreme climate and weather events. During the last few decades, climate of the country is changing significantly under the global warning. The annual mean air temperature for the whole territory of the country has increased by $1.56^{\circ}C$ during the last 60 years,. The winter temperature has increased by $1.56^{\circ}C$. These changes in temperature are spatially variable: winter warming is more pronounced in the high mountains and wide valleys between the mountains, and less so in the steppe and Gobi regions. There is a slight trend of increased precipitation during the last 60 years. The average precipitation rate is increased during 1940-1998 by 6%. This trend is not seasonally consistent: while summer precipitation increased by 11 %, spring precipitation decreased by 17. The climate change studies in Mongolia show that climate change will have a significant impact on natural resources such as water resources, natural rangeland, land use, snow cover, permafrost as well as major economic activities of arable farming, livestock, and society (i.e. human health, living standards, etc.) of Mongolia. Therefore, in new century, sustainable development of the country is defined by mitigating and adaptation policies of climate change. The objective of the presentation is to contribute one's idea in the how to reflect the changes in climate system and weather extreme events in the country's sustainable development concept.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6446-6451
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• 2014

Pneumatic motors are quite attractive for many applications because of their competitive price, light-weight, easy assembly, safety in hazardous areas as well as other features, such as a good force/weight ratio and operation in exceptionally harsh environments. In contrast to these advantages, pneumatic motors have limited use in applications, particularly those requiring a fast and precise response. These undesirable characteristics are due to the high compressibility of air and from the nonlinearities in pneumatic systems. This paper presents the sliding mode controller based on 3-loop(SMCB3L), which increases the load stiffness to control the rotation angle of a pneumatic motor. The characteristics for the step responses and load disturbances of the proposed controller were compared with the conventional PID controller. The experimental results showed that a properly designed SMCB3L is capable of high positioning accuracy within ${\pm}0.05mm$. Furthermore, the load stiffness of the SMCB3L can be improved 3.5 fold compared to that of PID controllers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.980-985
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• 2008

The environment of IT is, currently, on its developing process to the period of web 2.0 and mashup which not only enable computer and internet to be utilized like the water or the air, but also be a new motivating force for its advance. One of the biggest changes of the industry that lies ahead is consolidated transportation. However, no party outstands as the leading party for nationwide improvement of logistics, nor does the right analysis and design for it. Therefore, successful nationwide logistics model is yet to exist. This study provides individual parties, which consider consolidated transportation model as their implementation and design of the framework, with instructions for logistics information system so that they could be competitive in the market. It also helps companies collect user requirements for logistics information system consolidated transportation, and utilize it for its development. Finally, the study provides a implementation and design of pilot system for consolidated transportation model.