• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2004년도 정기총회 및 학술대회
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• pp.271-276
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• 2004

디지털방송이 시작되면서 고품질의 A/V(비디오/오디오)프로그램과 다양한 멀티미디어 컨텐츠를 제공하는 데이터방송을 처리하기 위한 수신 장치의 비중이 커지고 있다 이와 관련하여 데이터방송 환경에서 새로운 기술과 서비스가 등장할 때마다 이를 수용할 수 있는 소프트웨어를 탑재한 새로운 수신 장치가 필요하다. 일반적으로 한번 가정 내에 보급된 디지털 수신 장치의 소프트웨어 업그레이드가 용이하지 않기 때문에, 방송을 통해 이를 실현한다. 본 논문은 TV 셋탑박스 (STB) 내에 상주하는 middleware native application software 를 방송으로 다운받아 수정하는 기능을 지닌 STB 의 구현에 대해서 기술한다. 소프트웨어 업데이트 시스템은 소프트웨어를 포함하는 데이터 카루셀 스트림을 다운받아 파싱하는 다운로더, 추출된 소프트웨어를 설치하는 업데이트 로더, 그리고 예치상황이 발생하면 셋탑박스가 새로 부팅될 때, 로그 파일을 이용하여 소프트웨어를 옛날 상태의 회복시켜주는 리커버러 (recoverer)로 구성되어 있다. 다운로더는 지상파 디지털 방송 규격인 ATSC 규약에 맞게 구현하고, ATSC용 STB환경에서 테스트하고 있다.

• 방송공학회논문지
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• 제19권1호
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• pp.14-23
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• 2014

본 논문은 최근 이동통신 네트워크에서 폭발적으로 증가하고 있는 비디오 트래픽이 야기한 문제와 요구사항의 해결책으로써, SDN(Software Defined Network)을 기반으로 하는 다중 무선 접속 기술(Multiple Radio Access Technology)의 제어 기법을 제안하고 그 성능을 자체 구축한 테스트베드를 통하여 평가한다. 이를 위하여, 먼저 사업자 입장에서 3rd-party의 비디오 트래픽을 사업자망으로부터 우회(off-loading)시키는 방안의 필요성과, 사용자에게 저비용으로 고속의 대용량 비디오 콘텐츠 서비스를 제공하는 방안에 대하여 논의한다. 또한 성능평가를 위한 테스트베드는 OpenStack 클라우드 및 SDN 기반으로 구축 하였다. 이를 통해, OpenFlow와 Open Switch를 이용하여 2개의 2.4GHz 무선 랜 링크와 3개의 5GHz 무선 랜 링크가 동시에 하나의 서비스를 지원하도록 함으로서 820 Mbps 급의 초고속 클라우드 비디오 서비스를 위한 전송 속도를 실현하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1904-1926
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• 2016

Iris recognition for biometric personnel identification has gained much interest owing to the increasing concern with security today. The image quality plays a major role in the performance of iris recognition systems. When capturing an iris image under uncontrolled conditions and dealing with non-cooperative people, the chance of getting non-ideal images is very high owing to poor focus, off-angle, noise, motion blur, occlusion of eyelashes and eyelids, and wearing glasses. In order to improve the accuracy of iris recognition while dealing with non-ideal iris images, we propose a novel algorithm that improves the quality of degraded iris images. First, the iris image is localized properly to obtain accurate iris boundary detection, and then the iris image is normalized to obtain a fixed size. Second, the valid region (iris region) is extracted from the segmented iris image to obtain only the iris region. Third, to get a well-distributed texture image, bilinear interpolation is used on the segmented valid iris gray image. Using contrast-limited adaptive histogram equalization (CLAHE) enhances the low contrast of the resulting interpolated image. The results of CLAHE are further improved by stretching the maximum and minimum values to 0-255 by using histogram-stretching technique. The gray texture information is extracted by 1D Gabor filters while the Hamming distance technique is chosen as a metric for recognition. The NICE-II training dataset taken from UBRIS.v2 was used for the experiment. Results of the proposed method outperformed other methods in terms of equal error rate (EER).

• 정보처리학회논문지D
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• 제14D권7호
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• pp.773-782
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• 2007

소프트웨어 프로덕트 라인은 소프트웨어 재사용에 대한 활동들을 미리 계획하고 개발 프로세스의 연속적인 부분으로 이루어지도록 지원하기 위한 방법이다. 이 방법에서 가장 중요한 기술은 관련된 시스템들, 즉 도메인에서 공통성과 가변성(commonality and variability: C&V)을 분석하고 관리하는 것이다. 본 논문에서는 소프트웨어 프로덕트 라인 방법과 RFID 적용 기술을 결합시키고자 한다. 즉, 각 기업 또는 도메인마다 RFID 기술을 도입하려고 할 때, 애플리케이션이 공통적으로 처리해야 하는 활동들을 식별하고 각 활동들이 가지는 가변요소들을 분석하여, 이를 재사용 가능한 소프트웨어 프로덕트 라인 아키텍처로 자산화 하는 방법을 제시한다. 또한 이를 실현하기 위하여 재사용 가능한 프로덕트 라인 아키텍처를 모델링 할 수 있고 식별된 공통된 기능들을 재사용 가능한 컴포넌트로 제공해주는 프레임워크를 개발한다. 공통된 아키텍처를 공유하고 반복적인 기능들을 자산으로 만들어 재사용하는 것은 경제적인 측면과 품질에서 상당한 이점을 가져다 준다.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.957-962
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• 2018

The gamma radiation shielding capability (GRSC) of two clay-materials (Ball clay and Kaolin)of Southwestern Nigeria ($7.49^{\circ}N$, $4.55^{\circ}E$) have been investigated by determine theoretically and experimentally the mass attenuation coefficient, ${\mu}/{\rho}(cm^2g^{-1})$ of the clay materials at photon energies of 609.31, 1120.29, 1173.20, 1238.11, 1332.50 and 1764.49 keV emitted from $^{214}Bi$ ore and $^{60}Co$ point source. The mass attenuation coefficients were theoretically evaluated using the elemental compositions of the clay-materials obtained by Particle-Induced X-ray Emission (PIXE) elemental analysis technique as input data for WinXCom software. While gamma ray transmission experiment using Hyper Pure Germanium (HPGe) spectrometer detector to experimentally determine the mass attenuation coefficients, ${\mu}/{\rho}(cm^2g^{-1})$ of the samples. The experimental results are in good agreement with the theoretical calculations of WinXCom software. Linear attenuation coefficient (${\mu}$), half value layer (HVL) and mean free path (MFP) were also evaluated using the obtained ${\mu}/{\rho}$ values for the investigated samples. The GRSC of the selected clay-materials have been compared with other studied shielding materials. The cognizance of various factors such as availability, thermo-chemical stability and water retaining ability by the clay-samples can be analyzed for efficacy of the material for their GRSC.

• The Journal of Advanced Prosthodontics
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• 제11권2호
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• pp.120-127
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• 2019

PURPOSE. To determine wear amount of single molar crowns, made from four different restoratives, and opposing natural teeth through computerized fabrication techniques using 3D image alignment. MATERIALS AND METHODS. A total of 24 single crowns (N = 24 patients, age range: 18 - 50) were made from lithium disilicate (IPS E-max CAD), lithium silicate and zirconia based (Vita Suprinity CAD), resin matrix ceramic material (Cerasmart, GC), and dual matrix (Vita Enamic CAD) blocks. After digital impressions (Cerec 3D Bluecam, DentsplySirona), the crowns were designed and manufactured (Cerec 3, DentsplySirona). A dualcuring resin cement was used for cementation (Variolink Esthetic DC, Ivoclar). Then, measurement and recording of crowns and the opposing enamel surfaces with the intraoral scanner were made as well as at the third and sixth month follow-ups. All measurements were superimposed with a software (David-Laserscanner, V3.10.4). Volume loss due to wear was calculated from baseline to follow-up periods with Siemens Unigraphics NX 10 software. Statistical analysis was accomplished by Repeated Measures for ANOVA (SPSS 21) at = .05 significance level. RESULTS. After 6 months, insignificant differences of the glass matrix and resin matrix materials for restoration/enamel wear were observed (P>.05). While there were no significant differences between the glass matrix groups (P>.05), significant differences between the resin matrix group materials (P<.05) were obtained. Although Cerasmart and Enamic were both resin matrix based, they exhibited different wear characteristics. CONCLUSION. Glass matrix materials showed less wear both on their own and opposing enamel surfaces than resin matrix ceramic materials.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3440-3447
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• 2022

The accuracy of the photoatomic cross-section data is of great importance in the field of radiation protection, particularly in the characterization of radiation shielding materials. With the release of the latest and probably the most accurate photoatomic data library, EPDL2017, the need to re-evaluate all the existing and already established mass attenuation coefficients (MACs) of all radiation shielding materials arises. The MACs of several polymers, alloy-based, glasses, and building materials used in a nuclear medicine facility were investigated using the EPDL2017 library embedded in EpiXS software and were compared to MACs available in the literature. The relative differences between MAC_EpiXS and MACXCOM were negligible, ranging from 0.02% to 0.36% for most materials. However, for material like a glass comprising of elements Te and La evaluated near their corresponding K-edge energies, the relative differences in MACs increased up to 1.46%. On the other hand, a comparison with MACs calculated based on EPDL97 (a predecessor of EPDL2017) revealed as much as a 6.61% difference. Also, it would seem that the changes in MACs were more evident in the materials composed of high atomic number elements evaluated at x-ray energies compared to materials composed of low atomic number elements evaluated at gamma-ray energies.

• Imaging Science in Dentistry
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• 제34권1호
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• pp.13-18
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• 2004

Purpose : This study was to evaluate the influence of slice thickness of computed tomography (CT) and rapid protyping (RP) type on the accuracy of 3-dimensional medical model. Materials and Methods: Transaxial CT data of human dry skull were taken from multi-detector spiral CT. Slice thickness were 1, 2, 3 and 4 mm respectively. Three-dimensional image model reconstruction using 3-D visualization medical software (V-works /sup TM/ 3.0) and RP model fabrications were followed. 2-RP models were 3D printing (Z402, Z Corp., Burlington, USA) and Stereolithographic Apparatus model. Linear measurements of anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared according to slice thickness and RP model type. Results: There were relative error percentage in absolute value of 0.97, 1.98,3.83 between linear measurements of dry skull and image models of 1, 2, 3 mm slice thickness respectively. There was relative error percentage in absolute value of 0.79 between linear measurements of dry skull and SLA model. There was relative error difference in absolute value of 2.52 between linear measurements of dry skull and 3D printing model. Conclusion: These results indicated that 3-dimensional image model of thin slice thickness and stereolithographic RP model showed relative high accuracy.

• Computers and Concrete
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• 제12권5호
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• pp.717-737
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• 2013

In this study, experiment and numerical analysis were conducted to identify the heat transfer characteristics and behavior of high-strength concrete upon a fire. The numerical analysis was employed to forecast the characteristics and properties of the high-strength concrete upon a fire, which can not be accomplished through a fire test due to the specific conditions and restrictions associated with the test. The result of the numerical analysis was compared with that of the test to verify the reliability of the analysis. In the numerical analysis of the heat transfer characteristics and behavior of 80 and 100 MPa high-strength concrete upon a fire, the commercial software of ABAQUS(V.6.8) was used. It was observed from the experiment that the contraction of the concrete with fiber-cocktail was mitigated by 25~55 % compared with that without fiber-cocktail because the fiber controlled the heat transfer of the concrete and thus improved the fire-resistance performance of the column.

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.909-917
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• 2020

The research aims to analyze the firm-specific and macroeconomic factors that affect insurance company's financial performance. The research explores the variables that influence the financial performance of the United Arab Emirates (UAE)' insurance companies. The analysis for determining financial performance considers the following variables: the firm's age, retention ratio, capital adequacy, underwriting risk/loss ratio, financial-leverage, reinsurance dependency, and macro-economic factors such as GDP per capita, inflation rate considered as independent factors. The return-on-asset (ROA) is the key measuring indicator; it is regarded as the dependent variable for financial performance measures. The research focuses on secondary information obtained from insurance companies' financial statements. The researcher targeted 18 insurance companies listed on the UAE stock exchanges for study purposes. The research examines the overall factors that influence the financial performance of an insurance company. For analysis of data, software package of social sciences (SPSS version 20) is used. The studies used correlation and multiple linear regression analysis to determine financial performance and their effects. The analysis suggests that there are important and constructive relationships between the size, capital adequacy, and reinsurance dependency, while loss ratio, retention ratio, and financial leverage indicate a major negative relationship. And there's no link between GDP per capita and inflation.