• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7A
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• pp.560-568
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• 2012

Spectrum sensing and spectrum decision are the main functions that cognitive radios (CRs) have to perform in order to get the best available spectrum band for the establishment of a wireless communication. These problems are worsened in the presence of users with different demands and spectrum channels with different properties in a heterogeneous network. The primary objective in this work is to design and simulate a new spectrum decision algorithm for heterogeneous cognitive radio system. To this end, first, we consider all cognitive users are separated into different traffic classes according to their Quality of Service (QoS). The cognitive users within one traffic class perform spectrum sensing in centralized group-based cooperative spectrum sensing system and the users of different traffic classes share the sensing results. Second, we propose a novel use of the Analytic Hierarchy Process (AHP) to optimally select available bands according to user requirements and detected spectrum channel characteristics (SCC). In this paper, utility function is used as spectrum decision algorithm. Simulation results demonstrate that the proposed method shows can effectively select the best available spectrum channels with a low complexity.

• Journal of radiological science and technology
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• v.27 no.4
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• pp.37-41
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• 2004

Purpose : Raise ability cultivation in presence at a sicked business by performance management estimation of device through measurement. Also Learn a technology that measure exact tube voltage, exposure time, output dose. And it is to grasp photofluorography X-ray generator existing circumstances using at hospital. Material & Method : Investigated Photofluorography X-ray generator(inside, outside each 10) of 10 university hospitals using tube voltage, exposure time, output dose measuring instrument. Result : Photofluorography device that tube voltage correctness is incongruent by examination PAE decision came out 3, and at exposure time correctness examination 2 incongruent, Also 3 that calculate coefficient of variation about exposure in repeatability examination of exposure were incongruent. Inappropriate photofluorography device is 5 outside hospital(mobile unit) and the thing in hospital was 3 in 3 kind of efficiency test. It appeared high that photofluorography device outside hospital is more incongruent than thing in hospital. Conclusion : May ready situation that can offer patient medical service of good quality by radiation exposure reduction, image quality administration, retake decrease etc. by keeping performance of Photofluorography device. Therefore, is considered that need on-time efficiency test.

• Culinary science and hospitality research
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• v.5 no.2
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• pp.447-467
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• 1999

Most published work on product quality focuses on manufactured goods. The subject of service quality has received less attention. This distinction is important because some of the quality-improving strategies avaliable to manufacturers may be inappropriate for service firms. Services are performances, not objects. They are often produced in the presence of the customer, as in the cause of hotel restaurant services, quality occurs during service delivery, usually in an interaction between the customer and contact personnel of service firm. for this reason, service quality is highly dependent on the performance of employees, an organizational resource that cannot be controlled to the degree that components of tangible goods can be engineered. The study has begun as a basic study for customer satisfaction-oriented management in understanding the service quality of food & beverage products and through a systematic analysis of it. The major purpose of the study was to examine the relationship of the customer satisfaction and service quality in consideration of reliability, empathy, responsiveness, tangibility and assurance. An empirical research was conducted based on the previous theoretical studies. 286 customer at first class hotels in Seoul were selected as samples of this study. The time period of research was from February through March 1999, and answers were processed by SAS to yield frequency analysis, multivariate statistical analysis and regression analysis. The finding of the statistical treatment are frequencies, factor analysis, multiple regression analysis, path analysis. SERVQUAL method was used the service quality evaluation methods. After factor analysis, it was resulted to 3 factors. those were factor 1(assurance.empathy.responsiveness), factor 2(reliability), factor 3(tangibility). The findings of the statistical treatment are as follows. First, the attribute measurement of performance service quality was affected by customer satisfaction. Second, the attribute measurement of performance service qualify was affected by repurchase intention. Third, The attribute measurement of performance customer satisfaction was affected by repurchase intention. The result of study model was followed, service quality was affected repurchase intention than customer satisfaction. indirected effect through, service duality and customer satisfaction was affected repurchase intention.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.454-458
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• 2012

The CBTC(Communication based Train Control) and WPAN(Wireless Personal Area Network) systems employed on 2.4GHz ISM band wireless networks provide complementary service within the same environment. Coexistence between the networks will be impaired if the mutual packets are uncertainty associated the timing or gaussian distance. This paper analyzes the impact of the mutual interference and proposed method to minimize the effect of the WPAN system signals on CBTC system. The performance analysis is illustrated by examining the symbol error rate versus signal to noise interference ratio in terms of carrier frequency offset. The method contributes to reduce the symbol error rate drastically. However it can't be a fundamental solution for the impact on the interference problem. It may be needed for railway only frequency after checking the problems of the current railway frequency.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.1
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• pp.29-37
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• 2020

Work to improve network throughput has been focused on network coding as the utilization of IoT-based application services increases and network usage increases rapidly. In network coding, nodes transform packets received from neighboring nodes into a combination of encoded packets for transmission and decoding at the destination. This scheme is based on trust among nodes, but in the IoT environment where nodes are free to join, a malicious node can fabricate the packet if it legally participates in the configuration. It is difficult to identify the authenticity of the encoded packet since the packet received at destination is not a single source but a combination of packets generated by several nodes. In this paper, we propose a method to detect "look-like-valid" packets that have been attacked and disguised in packets received at destination, and to identify valid messages in the reconstructions. This method shows that network coding performance is significantly improved because the destination can reconstruct a valid message with only received packets without retransmission with a high probability, despite the presence of disguised packets.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.2
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• pp.135-140
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• 2011

Currently, studies have show that the network related energy consumption are increasing. and part of overall energy consumption of our society are too. So, that is important to look for energy-efficient network applications and protocols. A most of network energy consumption are due to network edge devices. in this paper, in order to cut down the emissions of carbon dioxide from ICT business, which contributes 2% of the global energy consumption, it is necessary to understand energy consumption in peer-to-peer system. In this paper, in this paper we propose a architecture based on the introduction of a p2p proxy. The model is analyzed analytically and numerically to reveal how these factors influence the overall power consumption in both steady state and flash crowd information exchange scenarios. Specifically, our results show that the proxy-based solution can provide up to 50% reduction in the energy consumption and, at the same time, a significant reduction in the average file download time.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.137-148
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• 2007

Due to the advance of technology, the technology of various media is rapidly converged into digital technology. However, the conversion into digital radio is not achieved in korea yet. This paper is to suggest the best method of digital conversion of radio in korea by examining some conversion examples in foreign countries. In addition, the survey results on radio audience attitude is analysed by 2,000 audience samples in Korea based on the literature analysis. Radio is the unique media which have the strengths such as mobility, individuality, presence, broad coverage and instant. Most of all, radio cannot help keeping continuously the public broadcasting service in the future. So, the conversion into digital radio is crucial to sustain the competitiveness in digital media environment. This paper suggested that the digital conversion of radio broadcasting needs DRM transmission and should pursuit the policy which is distinguished between a AM and a standard FM, and between domestic broadcast and an international broadcast. Additionally, this paper proposed that we need to develop the multiple device for receiving of signal and the setting of standard technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.851-860
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• 2013

To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.1
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• pp.111-122
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• 2014

The provided habitat of many services from natural capital is important. But because most ecosystem services tools qualitatively evaluated biodiversity or habitat quality, this study quantitatively analyzed those aspects using the species distribution model (MaxEnt). This study used location point data of the goat(Naemorhedus caudatus), marten(Martes flavigula), leopard cat(Prionailurus bengalensis), flying squirrel(Pteromys volans aluco) and otter(Lutra lutra) from the 3rd National Ecosystem Survey. Input data utilized DEM, landcover classification maps, Forest-types map and digital topographic maps. This study generated the MaxEnt model, randomly setting 70% of the presences as training data, with the remaining 30% used as test data, and ran five cross-validated replicates for each model. The threshold indicating maximum training sensitivity plus specificity was considered as a more robust approach, so this study used it to conduct the distribution into presence(1)-absence(0) predictions and totalled up a value of 5 times for uncertainty reduction. The test data's ROC curve of endangered mammals was as follows: growing down goat(0.896), otter(0.857), flying squirrel(0.738), marten(0.725), and leopard cat(0.629). This study was divided into two groups based on habitat: the first group consisted of the goat, marten, leopard cat and flying squirrel in the forest; and the second group consisted of the otter in the river. More than 60 percent of endangered mammals' distribution probability were 56.9% in the forest and 12.7% in the river. A future study is needed to conduct other species' distribution modeling exclusive of mammals and to develop a collection method of field survey data.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.598-601
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• 2008

The people, who can't deal with urine and feces by themselves because they can't recognize it, deal with urine and feces with help of protector (Or nurse). For the case of urine and feces, disease of ulcerated flesh of hip like unpleasant feeling, pressure sore, humid tetter due to wetness of diaper can be prevented by changing diaper instantly. However, those people can't be possible to express their opinion, so they can't express their opinion on urine and feces or endure sense of shame. So there is a problem which can't check presence of urine and feces instantly. Accordingly, in order to solve this problem, qualitative improvement of nursing service can be generated by developing u-Care product which instantly let know urine and feces to protector (Or nurse) by perceiving automatically, and benefit of welfare on social dependent class like low income old people and solitude old people can be increased by reducing social welfare expense with increment of nursing expense.