• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2012년도 추계학술발표대회
• /
• pp.1468-1471
• /
• 2012

It is always a dream to recreate the experience of a particular place, the Panorama Virtual Reality has been interpreted as a kind of technology to create virtual environments and the ability to maneuver angle for and select the path of view in a dynamic scene. In this paper we examined an efficient algorithm for Image registration and stitching of captured imaged from a video stream. Two approaches are studied in this paper. First, dynamic programming is used to spot the ideal key points, match these points to merge adjacent images together, later image blending is use for smooth color transitions. In second approach, FAST and SURF detection are used to find distinct features in the images and a nearest neighbor algorithm is used to match corresponding features, estimate homography with matched key points using RANSAC. The paper also covers the automatically choosing (recognizing, comparing) images to stitching method.

• 한국CDE학회논문집
• /
• 제6권4호
• /
• pp.236-243
• /
• 2001

A key factor far realizing the internet-based virtual manufacturing system(VMS) and virtual enter-prise(VE) is how to precisely and effectively represent the machine elements and mechanics. In this paper, we present methods to represent the numerically controlled machine tools in the internet environment. The method is composed of: 1) geometrical modeling of the machine tools, 2) kinematic modeling for the movements of the machine tools, and 3) representing the developed model in the internet infrastructure. Based on the models. a web-based virtual machine tools (WVMT) is developed, and it can be accessed at hrrp://wvmt.postech.ac.kr. The WVMT can be used for various purposes: 1) web-based virtual manufacturing system, 2) web-based CAM system, and 3) CNC educational tools for the vocational school through internet.

• 산업공학
• /
• 제14권2호
• /
• pp.127-133
• /
• 2001

Virtual Manufacturing is a technology facilitating effective development and agile production of products via computer models representing physical and logical schema and the behavior of the real manufacturing systems. For the successful application of this technology, a virtual plant as a well-designed and integrated environment is essential. We propose a series of systematic approaches and effective methods for construction and operation of a virtual plant in this paper, such as a 3-D CAD modeling, cell and line simulations and databases. We developed key technologies for measuring and 3-D CAD modeling of many equipments, facilities and structures of the buildings. In order to study the benefit of virtual manufacturing, we constructed a sophisticated virtual plant model of a Korean automotive company's body shop, and conducted precise simulations of unit cell, lines and the whole plant. We could obtain the benefit of savings in time and cost in many manufacturing preparation activities in the new car development processes.

• Journal of Power Electronics
• /
• 제18권4호
• /
• pp.1111-1126
• /
• 2018

In modern power systems, distributed generators (DGs) result in high stress on system frequency stability. Apart from the intermittent nature of DGs, most DGs do not contribute inertia or damping to systems. As a result, a new control method referred to as a virtual synchronous machine (VSM) has been proposed, which brought new characteristics to inverters such as synchronous machines (SM). DGs employing an energy storage system (ESS) provide inertia and damping through VSM control. Meanwhile, energy storage presents some physical constraints in the VSM implementation level. In this paper, a VSM mathematical model is built and analyzed. The dynamic responses of the output active power are presented when a step change in the frequency occurs. The influences of the inertia constant, damping factor and operating point on the ESS volume margins are investigated. In addition, physical constraints are proposed based on these analyses. The proposed physical constraints are simulated using PSCAD/EMTDC software and tested through RTDS experiment. Both simulation and RTDS test results verify the analysis.

• 한국디자인학회:학술대회논문집
• /
• 한국디자인학회 2003년도 봄 학술발표대회논문집
• /
• pp.254-255
• /
• 2003

• Journal of Information Technology Applications and Management
• /
• 제14권1호
• /
• pp.117-135
• /
• 2007

Globalization changes in market structures and consumer needs, as well as technology innovations force organizations to adopt new structures and collaborative networks to cope with rapidly changing environments. These Collaborative Networks are based on the Idea of virtual enterprise. A virtual enterprise(VE) is a temporary alliance of globally distributed independent enterprises that share core competencies and computer networks. This paper presents a proposal for a methodology to measure a key factor of success and risk First of all, we chose thirty experts' defines on virtual enterprise, fifteen are academic specialist and other fifteen are from industry. For this study we define twenty two factors determining VE's success and seventeen factors determining VE's risk using by Delphi method. And we built the influence model on virtual enterprise. A research model was established according to preceeding research and consensus on experts then the revised model of key factors on virtual enterprise. This survey was based on the Analytical Hierarchy Process (AHP). AHP is an approach to decision making that involves structuring multiple choice criteria into a hierarchy, the assessing the relative important of these criteria, comparing alternative for each criteria, and determining an overall ranking of the alternatives. A model was constructed as 3 level hierarchy. The hierarches are organizational, strategic, technical criteria. for success model on VE has 22 factors and 17 factors for risk model. They are selected by all 30 experts. 14 copies among 30 copies distributed to carry out on the Analytical Hierarchy Process (AHP). Consistency ratio confirm high validity and reliability of instrument and support theoretical model. The results of this study are summarized as follows. (1) This study presented success on VE influenced strategic criteria, and essential factor is Creating a value. Risk on VE influenced strategic criteria, and essential factor is Outcome/Distribution. (2) Its enable that ranking the criteria influence on VE. These are supported VE management and using guideline of VE.

• Journal of Power Electronics
• /
• 제19권5호
• /
• pp.1224-1234
• /
• 2019

Hybrid rotor position estimation methods that integrate a fundamental model and high frequency (HF) signal injection are widely used for the wide speed-range sensorless control of interior permanent-magnet synchronous machines (IPMSMs). However, the direct transition of two different schemes may lead to system fluctuations or system instability since two estimated rotor positions based on two different schemes are always unequal due to the effects of parameter variations, system delays and inverter nonlinearities. In order to avoid these problems, a seamless transition strategy to define and construct a virtual q-axis inductance is proposed in this paper. With the proposed seamless transition strategy, an estimated rotor position based on a fundamental model is forced to track that based on HF signal injection before the transition by adjusting the constructed virtual q-axis inductance. Meanwhile, considering that the virtual q-axis inductance changes with rotor position estimation errors, a new observer with a two-phase phase-locked loop (TP-PLL) is developed to accurately obtain the virtual q-axis inductance online. Furthermore, IPMSM sensorless control with maximum torque per ampere (MTPA) operations can be tracked automatically by selecting the proper virtual q-axis inductance. Finally, experimental results obtained from an IPMSM demonstrate the feasibility of the proposed seamless transition strategy.

• 한국컴퓨터정보학회논문지
• /
• 제27권12호
• /
• pp.111-119
• /
• 2022

본 연구는 빅데이터 분석을 이용하여 코로나19 전후의 3D가상패션에 대한 인식의 변화를 알아보기 위하여 코로나19 발생 전인 2017년 1월1일부터 발생 이후인 2022년 10월30일까지 소셜미디어 네이버, 다음, 구글, 유튜브에서 추출한 3D 가상패션 관련 주요 단어들을 대상으로 텍스톰을 이용하여 빅데이터 자료를 수집하였다. 수집된 단어는 정제 과정을 거친 후 워드클라우드, 단어의 빈도, 연결중심성, 네트워크 시각화와 CONCOR 분석을 실시하였다. 3D 가상패션을 키워드로 32,461개의 단어를 추출하여 분석한 결과 패션, 가상, 기술의 출현빈도와 중심성이 가장 높게 나타났으며 디지털, 디자인, 의상, 활용, 제조의 출현빈도도 높게 나타났다. 이를 통해 3D 가상패션이 기술의 발달과 더불어 산업 전반에 활용되고 있음을 알 수 있었다. 특히 코로나19 이후 가장 부각되는 주요 단어는 메타버스와 3D 교육으로서 패션산업에서의 요구도가 높게 나타나고 있다.

• 정보보호학회논문지
• /
• 제32권5호
• /
• pp.827-835
• /
• 2022

온라인상에서 안전하게 금융서비스를 이용하기 위해서는 사용자를 인증하는 기술이 요구된다. 키보드를 사용한 비밀번호 입력 방식이 가장 일반적이나, 키보드 입력이 쉽게 유출될 수 있음이 알려짐에 따라 많은 인터넷 뱅킹 서비스 및 간편 결제 서비스에서는 가상키보드를 사용하고 있다. 하지만 안전할 것이라는 기대와 달리, 가상키보드 역시 키보드 입력이 유출될 위험성이 존재했다. 본 논문에서는 가상키보드의 비밀번호 유출 가능성을 분석하고, PC 환경에서 마우스 이벤트 후킹과 화면캡처를 활용한 비밀번호 유출 방안을 제시했다. 또한, 국내 유명 인터넷 뱅킹 웹사이트 및 간편결제 서비스에서 비밀번호 유출 공격 가능성을 직접 검사하였으며, 그 결과 PC 운영체제에서 수행되는 가상키보드를 통한 비밀번호 입력방식이 안전하지 않음을 검증하였다.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
• /
• pp.62-63
• /
• 2003

We propose an improved image encryption and the shift-tolerance method in the Fourier space using a virtual phase image. The encrypted image is obtained by the Fourier transform of the product of a phase-encoded virtual image, not an original image, and a random phase image. We demonstrate the robustness to noise, to data loss and shift of the encrypted image or the Fourier decryption key in the proposed technique.