• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.939-944
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• 2002

PD phenomena can be regarded as a deterministic dynamical process where PD should be occurred if the local electric field be reached to be sufficiently high. And thus, its mathematical model can be described by either difference equations or differential equations using several state variables obtained from the time sequential measured data of PD signals. These variables can provide rich and complex behavior of detectable time series, for which Chaos theory can be employed. In this respect, a new PD pattern recognition method is proposed and named as 'Chaotic Analysis of Partial Discharges (CAPD)' for this work. For this purpose, six types of specimen are designed and made as the models of the possible defects that may cause sudden failures of the underground power transmission cables under service, and partial discharge signals, generated from those samples, are detected and then analyzed by means of CAPD. Throughout the work, qualitative and quantitative properties related to the PD signals from different defects are analyzed by use of attractor in phase space, information dimensions ($D_0$ and D2), Lyapunov exponents and K-S entropy as well. Based on these results, it could be pointed out that the nature of defect seems to be identified more distinctively when the CAPD is combined with traditional statistical method such as PRPDA. Furthermore, the relationship between PD magnitude and the occurrence timing is investigated with a view to simulating PD phenomena.

• International Journal of Precision Engineering and Manufacturing
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• 제3권3호
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• pp.37-43
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• 2002

Electronic speckle contouring(ESC) based on electronic speckle pattern interferometry is the optical method for measuring object shape by using fringe-projection techniques. This method has the advantages of being non-contact, non-destructive and a whole-field measurement of the surface under investigation. Fringes in ESC represent the difference in depth along the view direction between the master wavefront and the test component. The contour maps of three-dimensional diffuse objects can be obtained by small shifts of optical fiber carrying the dual-object-beams and 4-frame phase shifting. In this study we proposed the contouring method by shifting the collimated illumination beams through optical fiber in order to obtain the contour fringe patterns. And also, we performed the addition of incremental images through the geometrical analysis to obtain the contour fringe interval when we performed the incremental addition of images and experiments based on this method. We obtained both quantitative increment without decorrelation effect and qualitative improvement by reducing the noise of contour fringes.

• Asia pacific journal of information systems
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• 제24권3호
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• pp.371-391
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• 2014

A long-drawn out debate in the field of technology is whether it is value-neutral or value-laden. While some have argued that this debate has been resolved given the increasingly accepted view that technology is socially constructed, this is still not reflected in mainstream research which still assumes that technology is neutral. What is clear is that both views tend to be linked to studies that primarily focus on explicit forms of technology such as technological designs and their usage. These studies, though significant, may be limited in terms of an underemphasis on the process by which these technologies emerge, a process that requires decision-making activities made by different stakeholders and thus involves value judgments. In order to understand the extent of value-neutrality or value-ladenness of technologies, therefore, it is important to examine not only the final outcomes but also the process involved in technological development (including the artifacts created and used). In this study, we explored how values may be embedded in a specific IT application, and in cases of conflict of values, how they are prioritized. We did this in the context of applications development through an examination of the stages ranging from requirements analysis to coding to testing and deployment.

• Journal of Advanced Marine Engineering and Technology
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• 제10권2호
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• pp.136-145
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• 1986

The perfect and accurate methods to control the wear are not made clear so far. For this phenomenon only mating surface has been studied. In order to control the wear the essence of it has to be made clear. It is reported that adhesive wear might occure as a result of plastic deformation, the fracture and removal or transfer asperities on close contacting surfaces. On this view point the plastic flow was attempted to compare with fluid or electromagnetic flow. The partial differential equations of equilibrium for the plane strain deformation will make use of the method of characteristics. The characteristic curves or characteristics of the hyperbolic equation coincide with the slip lines by R. Hill's papers. By Hencky's stress equation, it is evident that if P and .phi. are prescribed for a boundary condition then it may be possible to proceed along constant .alpha. and .betha. lines to determine the value of the hydrostatic pressure everywhere in the slip line field net work. A wedge formation mechanism has been considered for an explanation of this matters. The analysis shows that there is a critical value, which depends on the hardness ratio and the shear stress on the interface, for the top angle of asperity is less than this critical value, the asperity can yield plastically despite of being harder than the mating surface.

• 정보관리연구
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• 제19권1호
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• pp.73-94
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• 1988

국내(國內) 영양학문헌(營養學文獻)의 서지적(書誌的) 현상 속에 내포된 의미를 파악하기 위하여 20 명의 저자(著者)를 대상으로 저자동시인용분석(著者同時引用分析)을 시도하고 나아가서는 다차원공간(多次元空間)에서 지적구조(知的構造)를 규명하였다. 저자동시인용분석(著者同時引用分析)은 동시인용빈도(同時引用頻度)가 높은 저자(著者)들일수록 밀접한 관계를 형성한다는 가정을 가지고서, "한국영양학회지(韓國營養學會誌)" 1986년과 1987년도 발행분을 기초자료(基礎資料)로 하여 분석 처리하였다. 분석 결과는 (1) 영양학분야(營養學分野)의 저자(著者)그룹, (2) 저자(著者)그룹간(間)의 위치, (3) 그룹내(內)에서의 중심저자와 주변저자, (4) 국내저자(國內著者)와 해외저자(海外著者)들간의 관계를 파악하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.450-453
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• 2006

Hydrographic data including particulate organic carbon (POC) from the Northeastern Gulf of Mexico (NEGOM) study were used along with remotely sensed data obtained from NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS) to develop POC algorithms to estimate POC concentration based on empirical and model-based principal component analysis (PCA) methods. In Case I and II waters empirical maximized simple ratio (MSR) and model-based PCA algorithms using full wavebands (blue, green and red wavelengths) provide more robust estimates of POC. The predicted POC concentrations matched well the spatial and seasonal distributions of POC measured in situ in the Gulf of Mexico. The ease in calculating the MSR algorithm compared to PCA analysis makes MSR the preferred algorithm for routine use. In order to determine the inter-annual variations of POC, MSR algorithms applied to calculate 100 monthly mean values of POC concentrations (September 1997-December 2005). The spatial and temporal variations of POC and sea surface temperature (SST) were analyzed with the empirical orthogonal function (EOF) method. POC estimates showed inter-annual variation in three different locations and may be affected by El $Ni{\tilde{n}}o/Southern$ Oscillation (ENSO) events.

• 한국가시화정보학회지
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• 제9권4호
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• pp.47-53
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• 2011

A water driven ejector loop was designed and constructed for air absorption. The used ejector was horizontally installed in the loop and annular water jet at the throat entrained air through the circular pipe placed at the center of the ejector. Wide range of water flow rate was provided using two kinds of pumps in the loop. The tested range of water flow rate was 100${\ell}$ /min to 1,000 ${\ell}$/min. Two-phase flow inside the ejector loop was simulated by CFD analysis. Homogeneous particle model was used for void fraction prediction. Water and air flow rates and pressure drop through the ejector were automatically recorded by using the LabView based data acquisition system. Flow characteristics and air bubble velocity field downstream of the ejector were investigated by two-phase flow visualization and PIV measurement based on bubble shadow images. Overall performance of the two-phase ejector predicted by the CFD simulation agrees well with that of the experiment.

• Journal of Positioning, Navigation, and Timing
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• 제11권3호
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• pp.181-189
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• 2022

The public open signals from Global Navigation Satellite System (GNSS) including Global positioning system (GPS) are used widely by many peoples in the world except for the public regulated restriction signals which are encrypted. Nowadays there are growing concerns about GNSS signal spoofing which can deceive the GNSS receivers by abusing these open services. To counter these spoofing threats, many researches have been studied including array antenna techniques which can detect the direction of arrival by means of Multiple Signal Classification (MUSIC) algorithm. Originally the array antenna techniques were developed to countermeasure the jamming signal in electronic warfare by using the nulling or beamforming algorithm toward a certain direction. In this paper, we study the anti-spoofing techniques using array antenna to overcome the jamming and spoofing issues simultaneously. First, we will present the theoretical analysis results of spoofing signal response of Minimum Variance Distortionless Response (MVDR) algorithm in array antenna. Then the eigenvector algorithm of covariance matrix is suggested and verified to work with the existing anti-jamming method. The modeling and simulation are used to verify the effectiveness of the anti-spoofing algorithm. Also, the field test results show that the array antenna system with the proposed algorithms can perform the anti-spoofing function. This anti-spoofing method using array antenna is very effective in the view point of solving both the jamming and spoofing problems using the same array antenna hardware.

• 한국식품조리과학회지
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• 제20권3호
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• pp.247-255
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• 2004

The foodservice industry is changing more and more from on-site foodservice management to contract foodservice management. However there are differences according to the level of management and operation of contract foodservice management company (CFMC). The necessity of certification on CFMC is increasing to enable fair discrimination of CFMC among most clients that want to contract with CFMC. This study was performed to identify the foodservice operation evaluation model's criteria items for certifying CFMC. The analysis research methods included literature review, content analysis, individual interview, Delphi technique, and brain storming. First, the following infrastructure items were prepared in the contractor's viewpoint: procurement, transparency of operation, menu development and operation system, nutrition service system, professional employee education, sanitation andsafety management system, customer satisfaction system, facility system, management information system (MIS), business and economics. Second, the evaluation criteria required by the contractor on the client's view point was similar to school foodservice, hospitalfoodservice, and business andindustry foodservice except extraordinary items of field. Third, evaluation criteria and detail categories and items were identified such as financial focus, customer focus, process focus, human focus, and renewal and development by grafting on intellectual capital evaluation methodology for CFMC.

• KIEAE Journal
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• 제9권1호
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• pp.31-38
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• 2009

The purpose of this study is to present direction in outdoors space planning and design after direction through user characteristic analysis through spectacle component establishment of culture art center outdoors space through on-the-site analysis and literature investigation to culture art center of Seoul city and capital region 17 places in this research. The data was collected from classification and bisection kind, subdivision kind, and great classification composed to 17 items. User satisfaction side and Variable that is looked below satisfaction than average appeared to bench, pergola, sculpture facilities, pavement facilities, border facilities. And these facilities were analyzed dissatisfaction. When see satisfaction model, when make up culture art center or similar facilities in local government hereafter because parking facilities and rest area cause big effect in satisfaction, is judged that is item to consider most preferentially. In most case, parking lot security from outdoors space, resting place security, security of field performance facilities etc. taking a serious view because tendency that users see performance or use most vehicles except neighborhood walking area for a rest, a walk etc.. is trend. But, is judged that physical side so that can feel satisfaction as space security of quantitative side is important but users utilize substantially and side that is the program are more important in hereafter.