• Journal of Power Electronics
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• 제8권1호
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• pp.1-9
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• 2008

This paper presents the design and analysis of a new input AC current wave shaping AC-DC converter for cost effective harmonic mitigation under varying loads. The proposed converter consists of a delta-polygon connected autotransformer based twelve-pulse AC-DC converter and a small rating passive shunt filter tuned at $11^{th}$ harmonic frequency. The proposed AC-DC converter eliminates the most dominant $5^{th},\;7^{th}$ and $11^{th}$ harmonics and reduces higher order harmonics; thereby, resulting in an improved power quality at AC mains. Moreover, the design of the autotransformer is modified to make it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. To validate the proposed approach, various power quality indices are presented under varying loads. Experimental results obtained on the developed converter are given to validate the model and design of the proposed converter.

• International Journal of Internet, Broadcasting and Communication
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• 제16권1호
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• pp.241-252
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• 2024

We analyze the types of Web3 business model innovation (BMI) of the six major Korean game companies by market size. As a result of the analysis, Nexon is watched as the adapter. It introduces blockchain (BC) layer 2, 'Polygon' to the extended ecosystem such as the creator's secondary creation, item utility, and compensation experience using the existing core intellectual property (IP). KakaoGames and Neowiz are watched as the adventurers. KakaoGames introduces BC layer 2, 'Polygon' and 'Near Protocol' to various experiments using tokenomics models in casual games and massively multiplayer online role-playing games (MMORPGs) using several existing popular IPs. Neowiz also introduces BC layer 2, 'Polygon' and 'Avalanche' to the IntellaX platform using existing game IPs. As the reinventor, Netmable positions as a game publisher that releases third-party games based on multi-chain infrastructure such as Klaytn, BNB Chain, Near Protocol, Aptos Foundation, and introduces BC to new core IPs. Finally, there are Wemade and Com2us as the mavericks. They aim to be the Web3 platform operators that create a BC layer 1 ecosystem and provide services that encompass BC games, GameFi, and non-fungible tokens (NFTs). Here are the implications of the four types of BMI. In terms of infrastructure, Nexon, KakaoGames, and Neowiz try to introduce a part of cross-chain, whereas Netmable tries to move toward a complete multi-chain strategy, and Wemade and Com2us also try to consider multi-chain, even if they have the full BC introduction. In terms of defending against market decline, Nexon and Netmable have a different position. Nexon which has a greater market dominance, only tries to continuously experiment, but Netmable is aggressively focusing on monetizing new products. Attacks on growth aspirations also show two different positions. KakaoGames and Neowiz only try to aggressively explore, while WeMade and Com2us try to set new standards for industrial innovation.

• 한국컴퓨터그래픽스학회논문지
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• 제4권1호
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• pp.55-66
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• 1998

This paper presents a simple method for relieving the ambiguity problems within the sub-voxel based surface-fitting approach for the surface construction. ECB algorithm is proposed to avoid the ambiguity problem which is the root of the holes within the resulting polygon based approximation. The basic idea of our disambiguation strategy is the use of a set of predefined modeling primitives (we call SMP) which guarantees the topological consistency of resulted surface polygons. 20 SMPs are derived from the extension of the concept of the elementary modeling primitives in the CB algorithm [3], and fit one to five faces of them to the iso-surface crossing a cell with no further processing. A look-up table which has a surface triangle list is pre-calculated using these 20 SMPs. All of surface triangles in the table are from the faces of SMPs and are stored in the form of edge list on which vertices of each surface triangle are located. The resulted polygon based approximation is unique at every threshold value and its validity is guaranteed without considering the complicated problems such as average of density and postprocessing. ECB algorithm could be free from the need for the time consuming post-processing, which eliminates holes by revisiting every boundary cell. Through three experiments of surface construction from volume data, its capability of hole avoidance is showed.

• 정보처리학회논문지C
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• 제17C권3호
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• pp.251-258
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• 2010

래터레이션 기법을 사용한 실내 위치 측위 기법은 단말기의 위치 예측을 위하여 RSS(Received Signal Strength)를 기반으로 예측된 단말기와 AP(Anchor Point)사이의 거리와 AP의 위치 정보를 사용한다. 따라서 단말기와 AP사이의 거리 예측 정확도가 단말기 위치 예측 정확도에 많은 영향을 미치게 된다. 무선 전파 환경은 시간과 공간에 따라 변화하므로 가장 높은 RSS 측정 값이 거리 예측에 가장 적합한 RSS 값은 아닐 수 있다. 이러한 문제를 해결하기 위하여 다수의 AP들이 사용되었으나 일정 수준 이상의 AP의 사용은 오히려 위치 측위 대상 면적이 증가하게 되어 단말기 위치 예측 정확도를 악화시킨다. 따라서 본 논문에서는 위치 측위 대상 면적을 감소시킴으로써 위치 예측 정확도를 향상시키기 위한 기법을 제안한다. 이를 위하여 본 논문에서는 단말기의 신호를 수신한 AP들로 구성된 다각형의 무게중심을 사용하여 단말기의 상대적인 위치를 예측하였다. 일단 단말기의 상대적인 위치가 예측되면 단말기에서 지리적으로 가장 근접한 AP를 단말기 위치 예측을 위한 기준 AP로 선택함으로써 측위 대상 다각형의 면적을 줄일 수 있다. 본 논문에서 구현한 실내 측위 시스템을 이용한 다양한 환경에서의 실험을 통하여 위치 예측 정확도 측면에서의 제안 기법의 타당성을 검증하였다.

• 한국BIM학회 논문집
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• 제13권3호
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• pp.30-38
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• 2023

Building Information Models(BIM) provides rich geometric and attribute information throughout the entire life cycle of a building and infrastructure object, while Geographic Information System(GIS) enables the detail analysis of urban issues based on the geo-spatial information in support of decision-making. The Integration of BIM and GIS data makes it possible to create a digital twin of the land in order to effectively manage smart cities. In the perspective of integrating BIM data into GIS systems, this study performs literature reviews on georeferencing techniques and identifies limitations in carrying out the georeferencing process using attribute information associated with absolute coordinates probided by Industry Foundation Classes(IFC) as a BIM standard. To address these limitations, an automated georeferencing process is proposed as a pilot study to position a IFC model with the Local Coordinate System(LCS) in GIS environments with the Reference Coordinate System(RCS). An evaluation of the proposed approach over a BIM model demonstrates that the proposed method is expected to be a great help for automatically georeferencing complex BIM models in a GIS environment, and thus provides benefits for efficient and reliable BIM and GIS integration in practice.

• 교육시설
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• 제16권6호
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• pp.13-20
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• 2009

The purpose of this study is to analyze the configuration and properties of university campus cores for systematic approach and planning through space syntax based on master plans of 55 universities in Korea. The results of this study showed that: first, the campus cores were classified into 10 types through axial map analysis. They were '一 type', '二 type', 'ㄱ type', 'T type', '+ type', 'radiation type', 'grid type', 'polygon type', 'tree structure type' and 'combination type'.(table 7) The frequency of '一 type' was the highest by 27.2%, and 'radiation type' was the next by 14.5%; second, the integration value was 2.03(+ type), te90(grid type), te75(ㄱ type), te74(一 type), te67(二 type), te63(T type), te46(polygon type), te347(tree structure type) and te343(radiation type).(table 9) We could categorize the 'radiation type' and the 'tree structure type' as the first group, the 'polygon type' as the second group, the 'T type', the '二 type', the '一 type', and the 'ㄱ type' as the third group, the 'grid type' as the fourth group, the '+ type' as the fifth group; third, cases that the integration value of access road was very low(58.2%) was much more frequent than that of very high(32.7%); fourth, the most important space in the campus core were as follows: library and media center(18.1%), administration buildings and headquarters(15.7%), student center(15.7%), lecturing building(13.9%), streets and squares(13.3%).

• 만화애니메이션 연구
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• 통권37호
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• pp.143-158
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• 2014

3D 컴퓨터 애니메이션의 모델링 작업과정은 사실적 형태 구현을 위한 최적의 작업조건에 대한 방법들이 진일보되고 있다. 1999년 출시된 모델링 전문 소프트웨어인 ZBrush는 기존과 다른 용이한 제작방식으로 인해, 캐릭터 모델 작업에 있어서 필수요소로 자리 잡고 있다. 이에, 본 논문에서는 보다 최적화된 애니메이션 캐릭터 모델 제작을 위한 방법으로써 두 개의 소프트웨어 (Z-Brush, Maya)의 연계된 제작시스템에 대한 효율성에 대해 고찰하고, 그 시사점을 제시하고자 한다. 이를 위해, 첫째 폴리곤 모델링과 리토폴로지(retopology)에 대한 기술적 특성에 대해 살펴보았으며, 둘째, 이를 바탕으로, 기존의 캐릭터 모델링을 위한 ZBrush와 Maya의 연계적 작업 과정의 문제점을 분석한다. 셋째, 새로운 모델링 작업의 최적화 기법의 효율성을 검증하기 위해, 단편 애니메이션 영화 'Cula & Mina'의 Dumvee 캐릭터의 제작과정을 사례로 하여 그 제작과정을 분석하였다. 본 연구를 통해, 두 개의 소프트웨어를 이용한 모델링 공정 연계 시스템은 보다 효과적으로 하이 폴리곤(high polygon) 모델에 대한 제작의 용이함과 높은 완성도를 구현할 수 있음을 알 수 있었다. 이를 통해, 기존과 다른 효율적 모델링 방식을 고찰함으로써, 모델링 관련 수업이나 관련 산업체의 제작 시스템의 최적화를 위한 참고자료가 되리라 사료된다. 또한, 본 연구는 폴리곤 모델링 제작과정의 개선을 위한 '실용적 대안 제시'를 목적으로 하는 기술제작 사례논문으로 접근하였다.

• Computers and Concrete
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• 제23권1호
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• pp.69-80
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• 2019

Modeling approach for mesoscopic model of concrete depicting mass transportation and physicochemical reaction is important since there is growing demand for accuracy and computational efficiency of numerical simulation. Mesoscopic numerical simulation considering binder, aggregate and Interfacial Transition Zone (ITZ) generally produces huge number of DOFs, which is inapplicable for full structure. In this paper, a three-dimensional multiscale approach describing three-phase structure of concrete was discussed numerically. An effective approach generating random aggregate in polygon based on checking centroid distance was introduced. Moreover, ITZ elements were built by parallel expanding the surface of aggregates on inner side. By combining mesoscopic model including full-graded aggregate and macroscopic model, cases related to diffusivity and thickness of ITZ, volume fraction and grade of aggregate were studied regarding the consideration of multiscale compensation. Results clearly showed that larger analysis model in multiscale model expanded the diffusion space of chloride ion and decreased chloride content in front of rebar. Finally, this paper addressed some worth-noting conclusions about the chloride distribution and rebar corrosion regarding the configuration of, rebar diameter, concrete cover and exposure period.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1665-1673
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• 2003

We propose an image-based three-dimensional shape determination system. The shape, and thus the three-dimensional coordinate information of the 3-D object, is determined solely from captured images of the 3-D object from a prescribed set of viewpoints. The approach is based on the shape-from-silhouette (SFS) technique, and the efficacy of the SFS method is tested using a sample data set. The extracted three-dimensional shape is modeled with polygons generated by a new iterative triangulation algorithm, and the polygon model can be exported to commercial software. The proposed system may be used to visualize the 3-D object efficiently, or to quickly generate initial CAD data for reverse engineering purposes, including three dimensional design applications such as 3-D animation and 3-D games.

• 한국산학기술학회논문지
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• 제15권1호
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• pp.418-424
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• 2014

본 논문에서는 영상감시 시스템을 위한 감시영역 입력방법을 제안한다. 이동물체의 침입 여부는 감시영역과 비교를 통해 이루어지므로 이를 입력하는 방법은 영상감시의 가장 기본적인 기능이다. 기존의 방법은 각 카메라 별로 획득된 영상을 기반으로 감시영역을 설정하기 때문에 감시영역의 크기. 카메라 수, 카메라 위치 등 감시환경의 변화에 대응하기 어려운 단점이 있다. 제안하는 입력방법은 위성지도를 기반으로 감시영역 전체를 다각형으로 정의하고, 이를 각 카메라 환경으로 변환하는 접근방법을 사용한다. 이 방법의 특징은 감시환경에 독립적이라는 점이다. 다각형의 정점의 수를 n이라 하면 침입탐지 수행시간은 O(n)의 복잡도를 보인다. 제안하는 방법의 타당성을 검증하기 위해 3D 시뮬레이션을 수행하였으며, 각 카메라 수와 위치에 무관하게 입력된 감시영역을 재사용할 수 있음을 확인하였다.