• Korean journal of communication and information
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• v.18
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• pp.199-229
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• 2002

This study analyzed the trends of broadcaster licensing policy during 1990-2001 in Korea. It is to seek the answers about how the examination standards and procedures applied to broadcaster licensing has been changed for the last decade. For the purpose this study inquired six cases such as private broadcasting licence (1990 October), cable TV program provider licences(1993 July), cable TV system operator licences(1994 January), private local broadcaster licences(1994 July), satellite broadcaster licence(2000 December) and cable TV home shopping channel licences(2001 March). It examined the degree of specification and measurement of the standards based upon the government white paper; average points per item, average points per quantitative item, and average points per qualitative item etc. The government hadn't opened the standards and procedures how it licensed broadcasters until 1990 and the uncertain attitude brought distrust on the government broadcasting policy. The first white paper about broadcaster licensing was made in 1994 after cable TV broadcaster licensing was finished. The results indicated that Korean broadcasting licensing policy rapidly developed in the dimension of transparency from 'a secret room policy' to 'a sunshine policy' for the last decade. But it still needs improvement in the dimension of fairness of examination. Now one of the main distrust is the ratio that the one of qualitative examination standards are much more than the qualitative one.

• Economic and Environmental Geology
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• v.44 no.3
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• pp.239-246
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• 2011

Groundwater in small islands is used as main water resource but the overuse of groundwater may cause seawater intrusion and temperature decrease in geothermal wells. This study aimed to characterize the hydrogeology of Maeum-ri area in Seokmo Island of Ganghwagun using long-term monitoring at groundwater wells and geothermal wells. In the monitoring period seasonal water level change, consistent drop or increase of water levels are not detected. The groundwater temperature about 10m below ground surface shows year cycle variation having two to five months difference with ambient temperature cycle. The storativity was calculated by tidal method. The storativity estimated by adapting tidal efficiency factor showed some larger values than that by using tidal time lag. The result suggested that the tidal method assuming several assumptions on aquifer condition may produce broad ranges but the calculated ranges at this application are reasonable. The similar shape of groundwater level change and tidal effects was observed at several wells clustered east-south-east direction which may implicate the distribution of vertical fracture system strongly related with groundwater flow channels. The applied methodology and study results will bc valuable to evaluate optimal pumping rate for the preservation of groundwater resources, and to manage geothermal development.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.45-55
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• 2009

This study was intended to increase efficiency of traffic flow management on intersection. The result suggested to establish a left-turn at own risk lane to increase efficiency of traffic flow on intersection. The scope of the research was to investigate the geometric structure of a signal-controlled intersection, traffic volume(density) with respect to directions and traffic signal display, and to select a signalling intersection into which a car waiting for a traffic signal enters by adjusting the display sequence of traffic signal. The delay with respect to directions and for the whole intersection was compared for the current situation and an improvement plan. Using TSIS, a traffic analysis package, the traffic situation on an intersection was investigated. Based on the simulation result for Seok-Jeon intersection in Ma-San selected from the field investigation of intersections to which an improvement plans would be applicable, the waiting time in the direction without a entering traffic signal was decreased to be 78.6 seconds per car and that of the direction expecting the increase of waiting time was increased by 4 seconds per car only. It was confirmed that the waiting time for the whole intersection was improved.

• Environmental and Resource Economics Review
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• v.15 no.2
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• pp.201-245
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• 2006

We applied general equilibrium model to analysis the economic impact of international emission trading by sector and the efficiency of the Convention to study whether Climate Change Convention satisfy the efficiency. We divided the world as 4 groups : USA, OECD members w/o USA (OEC), Former Soviet Union (FSU) and Developing countries (DEV). Compared to no trading, global trading would accomplish the same environmental effect with less cost as much as 97.8 billion$, which is the surplus of trading. However, half of it is taken by USA and 20% by OEC. FSU and DEV have only 18% and 10%. This result suggest the two things. First, the emission trading is effective as far as the participation of developing countries are guaranteed. If they do not take part in the coalition and emit the leakage, it may threaten the stability of the international trading coalition. Second, we found the logical ground of the side payment for developing countries. The permit buying countries take more share of the surplus under the emission trading, while the energy sector of developing countries shrinks to sell permits, which may adversely affect to economic growth of the countries. Therefore, the Annex-I countries need to provide side payment to lead the participation of the developing countries.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.10
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• pp.513-519
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• 2001

Home-based Lazy Release Consistency (HLRC) shows poor performance on lock based applications because of two reasons:(1) a whole page is fetched on a page fault while actual modification is much smaller , and(2) the home is at the fixed location while access pattern is migratory, In this paper we present an efficient lock protocol for HLRC. In this protocol, the pages that are expected to be used by acquirer selectively updated using diffs. The diff accumulation problem is minimized by limiting the size of diffs to be sent for each page. Our protocol reduces the number or page faults inside critical sections because pages can be updated by applying locally stored diffs . This reduction yields the reduction of average lock waiting time and the reduction of message amount. The experiment with five applications shows that our protocol archives 2%~40% speedup against base HLRC for four applications.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.6-10
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• 2015

RF energy harvesting technology is a promising technology for generating the electrical power from ambient RF signal to operate low-power consumption devices(eg. sensor) in wireless communication networks. This paper, motivated by this and building upon existing CR(Cognitive Radio) network model, proposes a optimal control policy for RF energy harvesting CR networks model where secondary users that have low power consumption harvest ambient RF energy from transmission by nearby active primary users, while periodically sensing and opportunistically accessing the licensed spectrum to the primary user's network. We consider that primary users and secondary users are distributed as Poisson point processes and contact with their intended receivers at fixed distances. Finally we can derive the optimal frame duration, transmission power and density of secondary user from the proposed model that can maximize the secondary users's throughput under the given several conditions and suggest future directions of research.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.612-621
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• 2013

Microwave-assisted extraction (MAE), which is known as less time and less solvent than current extraction methods, was applied to hydrocarbons extraction from irradiated soybean. Among the transported agricultural products, soybean was selected as representative samples for possible application of irradiated treatment and identification of radiation-induced markers. Using 4 kGy-irradiated soybean, different microwave extraction conditions (extraction time and microwave power) were applied and the changes in hydrocarbon concentrations were monitored. The predicted optimum extracted condition for hydrocarbon analysis of soybean was found to be microwave extraction with a microwave power of 97 W and extraction time of 2.2 min. This extraction time was significantly lower compared to the common extraction time of 12-24hr.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.4
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• pp.141-146
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• 2015

Data have been increased enormously due to the development of IT technology such as recent smart equipments, social network services and streaming services. To meet these environments the technologies that can treat mass data have received attention, and the typical one is Hadoop. Hadoop is on the basis of open source, and it has been designed to be used at general purpose computers on the basis of Linux. To initial Hadoop nearly no security was introduced, but as the number of users increased data that need security increased and there appeared new version that introduced Kerberos and Token system in 2009. But in this method there was a problem that only one secret key can be used and access permission to blocks cannot be authenticated to each user, and there were weak points that replay attack and spoofing attack were possible. Hence, to supplement these weak points and to maintain efficiency a protocol on the basis of group key, in which users are authenticated in logical group and then this is reflected to token, is proposed in this paper. The result shows that it has solved the weak points and there is no big overhead in terms of efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.512-519
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• 2016

This paper presents spectrum utilization strategies in cognitive radio (CR) networks powered by multi-antenna based wireless energy transfer. Secondary access point (AP) with multiple antennas should transfer the energy to the secondary sensor nodes with energy beamforming and simultaneously induces no interference to PUs. In addition, sensor nodes can transmit information to the secondary AP using the harvested energy, only when the spectrum is not utilized by PUs. We analyze the achievable rate of the CR sensor networks and propose an interference nulling energy beamforming method to maximize the achievable rate. Finally, we also propose a frame scheduling algorithm in which the durations of wireless energy transfer/information transfer frames (phases) are optimized.

• Geotechnical Engineering
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• v.2 no.3
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• pp.67-78
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• 1986

This paper presents how to determine the system reliability of a typical shallow foundation constituted four potential correlated failure modes of hearing capacity (BCM), consolidation settlement (CSM), moment (MFM), and tension shear (PCM). Through the idenfication of the distinct and different modes and evaluation of range of system reliability, the obtained conclusions are as follows; 1. The CSM and the PCM are the lowest and highest of reliability indices of single performance function, and the BCM and the MFM are medium of them. 2. For the correlated failure modes, the hi-modal bounds Is narrower and lower of failure probability than the unimodal bounds. Not to be overestimated, therefore, the system reliability should be based on the second-order bounds using correlated performance functions.