• 전기학회논문지
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• 제60권1호
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• pp.205-213
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• 2011

The Long Term Evolution (LTE) system is designed to provide a high quality data service for fast moving mobile users. It is based on the Orthogonal Frequency Division Multiplexing (OFDM) and relies its channel estimation on the training samples which are systematically built within the transmitting data. Either a preamble or a lattice type is used for the distribution of training samples and the latter suits better for the multipath fading channel environment whose channel frequency response (CFR) fluctuates rapidly with time. In the lattice-type structure, the estimation of the CFR makes use of the least squares estimate (LSE) for each pilot samples, followed by an interpolation both in time-and in frequency-domain to fill up the channel estimates for subcarriers corresponding to data samples. All interpolation schemes should rely on the pilot estimates only, and thus, their performances are bounded by the quality of pilot estimates. However, the additive noise give rise to high fluctuation on the pilot estimates, especially in a communication environment with low signal-to-noise ratio. These high fluctuations could be monitored in the alternating high values of the first forward differences (FFD) between pilot estimates. In this paper, we analyzed statistically those FFD values and propose a postprocessing algorithm to suppress high fluctuations in the noisy pilot estimates. The proposed method is based on a localized adaptive moving-average filtering. The performance of the proposed technique is verified on a multipath environment suggested on a 3GPP LTE specification. It is shown that the mean-squared error (MSE) between the actual CFR and pilot estimates could be reduced up to 68% from the noisy pilot estimates.

• 정보처리학회논문지B
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• 제18B권4호
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• pp.181-192
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• 2011

스마트 폰의 등장과 모바일 인터넷을 제공함에 따라 휴대폰은 음성통신 수단이 아닌 웹을 통하여 서비스를 제공받는 도구 또는 각종 게임 및 응용 어플리케이션을 제공하는 놀이 수단으로도 발전하였고, 이로 인하여 사용량도 증가하였다. 사용량의 급증으로 인하여 모바일 광고에 대한 업계의 관심도 증가 하였지만, 한정적인 출력 화면에 의하여 광고 효과가 제한적일 수밖에 없다. 이를 보완하기 위해, 본 논문에서는 기업의 로고 광고의 효과를 극대화 할 수 있는 안드로이드 기반 로고 인식 증강 현실 시스템을 제안하였고, 이를 구현하여 실제 스마트 폰에 탑재한 후 다양한 성능 분석을 하였다. 실험결과, 그 가능성은 확인하였지만 현 하드웨어 성능상 실시간으로 지원하기에는 역부족임을 알 수 있었다.

• 약학회지
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• 제52권6호
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• pp.507-513
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• 2008

The purpose of this study is to analyze the factors affecting financial performance of community pharmacies after the implementation of the new drug policy in Korea: separation of drug prescription and dispensing (SPD). The online survey questionnaires were sent to the active pharmacists of the total 20,633 community pharmacies in Korea and 1,147 pharmacists responded to the survey (the response rate was 5.5%). The questionnaire asked simple financial data in order to compare their financial performances before and after the policy. With the SPSS package (version 12.0), two levels of data analysis were used: 1) descriptive statistics to see the financial status of the pharmacies; and 2) multiple regression analysis to find the factors. {or A multiple regression method was used for the data analysis.} The finding illustrated that the average net benefit of the pharmacies was 4,870 thousand won in August 2006, and the major factors affecting the net benefit were the location of pharmacy (geographical proximity to medical institutions), number of prescriptions, drug management services for patients, chain pharmacy membership. The findings of this study suggest that service improvement for patients, revitalization of non-prescription drug sales, professional management will contribute to promote community based pharmacy business.

• Current Optics and Photonics
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• 제1권5호
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• pp.456-467
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• 2017

The benefits of network coding in all-optical multicast networks have been widely demonstrated. In this paper, we mainly discuss the multicast service efficiently provisioning problem in the network coding enabled elastic optical networks (EONs). Although most research on routing and spectrum allocation (RSA) has been widely studied in the elastic optical networks (EONs), rare research studies RSA for multicast in the network coding enabled EON, especially considering the time delay constraint. We propose an efficient heuristic algorithm, called Network Coding based Multicast Capable-Multipath Routing and Spectrum Allocation (NCMC-MRSA) to solve the multipath RSA for multicast services in the network coding enabled EON. The well-known layered graph approach is utilized for NCMC-MRSA, and two request ordering strategies are utilized for multiple multicast requests. From the simulation results, we observe that the proposed algorithm NCMC-MRSA performs more efficient spectrum utilization compared with the benchmark algorithms. NCMC-MRSA utilizing the spectrum request balancing (SRB) ordering strategy shows the most efficient spectrum utilization performance among other algorithms in most test networks. Note that we also observe that the efficiency of NCMC-MRSA shows more obvious than the benchmark algorithm in large networks. We also conduct the performance comparisons of two request ordering strategies for NCMC-MRSA. Besides, we also evaluate the impact of the number of the linkdisjoint parallel w paths on the spectrum utilization performance of the proposed algorithm NCMC-MRSA. It is interesting to find that the change of the parameter w in a certain range has a significant impact on the performance of NCMC-MRSA. As the parameter w increases to a certain value, the performances of NCMC-MRSA cannot be affected by the change of w any more.

• 대한안전경영과학회지
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• 제13권2호
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• pp.185-193
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• 2011

The successful and sustainable growth of SMEs depends on their ability of strengthen their competitiveness in quality and cost and service more than anything else as a fundamental of operation. Among these key competitive factors of SMEs, quality is the most critical factor in manufacturing business fields. There are many different ways to improve the quality performance but it needs proper management decision to choose the best way what can maximize outputs with minimum inputs. And it needs effective measurement methods and some indicators to analysis the quality performance properly. The quality cost is one of the simplest key indicators to measure the quality performance and the effectiveness of quality related management decisions. In this study, through survey on local SMEs, we found that their average annual quality cost ratio versus turnover - total amount of annual quality cost divided by annual turnover - is around 3.69% excluded some SME's performances what have different quality control measures with others. And we found some results what corresponded with the early studies on the correlations between those categorized quality costs factors and some discrepancies between some of the literature model and the early case study results as follows. There were negative correlations between the Prevention costs and the External failure costs, and the Appraisal costs and the External failure costs, and there was positive correlation between the Appraisal costs and Internal failure costs same as early studies. But, we couldn't found any strong negative correlations between the Cost of control - Prevention costs & Appraisal costs - and the Cost of Failure of control - Internal & External failure costs -.

• 한국의상디자인학회지
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• 제9권3호
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• pp.115-132
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• 2007

The purpose of this research is that to study of musical performer's purchasing behavior, satisfaction and design preference, and to give the information for better performance costume market based on that result. The target for the survey is limited only for above 4th grade female students and have experienced more than three times of performances. Total 364 questionnaires are used for this research. The SPSS was used for the analysis. The results were, first, in the survey of place of purchasing, specialty shop for musical performance shop was the most. The most group for the budget that they spent was under 100,000 Won. Rational price for costume would be 150,000-300,000 Won. Most people purchase costume before 2 weeks and compare 3-4 stores mostly. There were not many complaints about being comfort for costume itself. The preference for costume was different depends on not only scale of performance but also whether solo, duet or trio or more. Also harmony with other person costume was most consideration factor when they perform duet or more. For the choice of shop factor following were considered the most important; various selections, kindness of sales persons and possibility for trying various costumes. However, locations of shop or delivery service were not important relatively. For the choice of costume factor, design color, comfort and functionality were considered the most important but price, quality and decoration were not. For 'the satisfaction after purchase costume' factor, people's opinions, best appearance on the stage and meeting image with themselves were considered the most important. Second, on the subject for 'design preference of costume based on type of performance', people chose different color of dress depends on what types of performance. In case of solo, they prefer vivid primary color; in case of trio or more, they prefer black; in case of duet, they prefer pastel tone. As for preference of sleeve design, all of them prefer non-sleeve type.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.165-170
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• 2006

In the Civil Aviation field, the international trend (through ICAO, EUROCONTROL) is to adopt one positioning system that allows to follow more flight phases. This will allow to release themselves by ground installations and optimize the traffic flows following the aRea Navigation (RNAV) concept. In order to realize this goal the European Scientific Community are focusing on Augmentation Systems based on Satellite infrastructure (SBAS - Satellite Based Augmentation System) and on Ground based ones (GBAS - Ground Based Augmentation System). The goal of this work is to present some results on SBAS and GBAS performances. Regarding SBAS, the Department of Applied Sciences of Parthenope University, after the acquisition of a Novatel OEM4 SBAS receiver has created a monitoring station that reflect as much as possible a standardized measure environment for EGNOS Data Collection Network (EDCN), established by Eurocontrol. The Department of Applied Science has decided to carry out a own monitoring survey to verify the performance of EGNOS that can be achieved in South Europe region, a zone not very covered by official (EDCN) monitoring network. Regarding GBAS, we started from a data set of measurements carried out at the GBAS of Milan-Linate airport where we work on a ground installation (GMS - Ground Monitoring Station) that supervises the GBAS signal and that represent, for our purposes, the Aircraft subsystem. So the set of data collected is to be considered in RTK mode and after the measures session we processed them with the software PEGASUS v 4.11. Both experiences give us the possibility to evaluate the GNSS1 performance that can be achieved.

• 센서학회지
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• 제10권1호
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• pp.33-41
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• 2001

와이어 로프는 무거운 중량을 안전하게 운반하거나 기계적인 에너지를 빠르게 전송하는 곳과 같은 산업응용 분야에 광범위하게 사용되어 왔다. 특히, 운전 중 엘리베이터의 와이어 로프가 파손되면 큰 재산 상 손실과 주변 인명의 심각한 상해를 초래할 수 있다. 따라서, 와이어 로프의 정기적인 검사는 매우 중요하다. 와이어 로프의 고장 검출은 로프의 구조, 특성, 결함 특성, 검출방법과 신호처리 방법에 대한 기본적인 이해가 요구된다. 이 연구에서는 엘리베이터에 노화된 와이어 로프에 대한 마모, 단선, 부식과 형붕괴와 같은 결함을 검출하기 위하여, Hall 센서를 결합한 새로운 결함 검출시스템의 개발에 대하여 다룬다. 휴대용 계측기로서 검출기를 사용하기 위하여, Hall 센서를 가진 센싱 부분과 아날로그 신호처리 및 프로그램의 제작에 대한 몇 가지 특성들이 서술되었다. 제작된 검출시스템에 대한 실험과 실장시험 결과 역시 제시되었다. 그 결과, 검출시스템은 사용 중인 노화된 와이어 로프의 결함을 검출하는데 양호한 효율성을 갖는다는 것을 확인하였다.

• 정보처리학회논문지A
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• 제9A권1호
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• pp.45-52
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• 2002

본 논문에서는 네트워크환경에 따라 모호성을 갖는 집중형 분산처리시스템의 성능평가를 위해 퍼지이론을 적용한 퍼지 폐쇄형 BCMP 큐잉네트워크모델을 제안하였다. 이 모델은 퍼지요소들을 처리할 수 있는 퍼지평균값분석방법을 사용하여 작업소요시간, 시스템처리율, 시스템내 작업수 및 서버 활용율 등의 시스템 성능을 평가할 수 있는 측도를 유도하였다. 이들의 유효함을 검증하기 위하여 퍼지서비스요구시간을 갖는 집중형 분산 처리시스템에 클라이언트의 수의 변화에 따른 유도된 성능평가측도를 시뮬레이션하고, 그 결과를 고찰하였다. 제안된 모델은 모호성을 갖는 시스템의 성능을 평가할 때 기존의 방법보다 유연하고 실제적인 방법을 제공한다.

• 한국정보통신학회논문지
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• 제19권11호
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• pp.2576-2583
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• 2015

전이중(full-duplex) 셀룰라 네트워크에서 상향링크 사용자는 하향링크 사용자에게 간섭을 유발하므로 같은 무선 자원을 동시에 사용하는 상 하향링크 사용자 쌍을 어떻게 결정하는 지가 시스템 성능에 큰 영향을 미친다. 본 논문에서는 사용자의 서비스의 질을 보장하기 위한 목적으로 아웃티지(outage) 발생의 최소화를 위한 최적화 문제를 제시하고, 낮은 복잡도를 갖는 차선의 사용자 스케쥴링 알고리즘을 제안한다. 제안하는 스케쥴링 방식은 나쁜 신호 품질을 갖는 하향링크 사용자에게 간섭을 덜 미치는 상향링크 사용자를 먼저 선택할 수 있도록 우선권을 주는 방식으로 동작한다. 시뮬레이션 결과 제안하는 사용자 스케쥴링 방식을 사용하는 전이중 시스템은 최적에 가까운 아웃티지 성능을 달성하면서 기존 반이중 모드의 셀룰라 시스템 대비 아웃티지 발생을 현저히 줄인다.