• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.168-177
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• 2024

When designing an underwater Piezoelectric Energy Harvester (PEH), Vortex Induced Vibration (VIV) is generated throughout the cantilever through a change in curvature, and the generation of VIV increases the vibration displacement of the curved cantilever PEH, which is an important factor in increasing actual power. The material of the curved PEH selected a Polyvinyline Di-Floride (PVDF) piezoelectric film, and the flow velocity is set at 0.1 m/s to 0.50 m/s for 50 mm, 130 mm, and 210 mm with various curvatures. The strain energy change of PEH by VIV was observed. The smaller the radius of curvature, the larger the VIV, and as the flow rate increased, more VIV appeared. Rapid shape transformation due to the small curvature was effective in generating VIV, and strain energy, normalized voltage, average power, etc. To increase the amount of power of the PEH, it is considered that the average power will increase as the number of curved PEHs increases as well as the steep curvature is improved.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2004.06a
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• pp.55-60
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• 2004

XML 문서의 관계형 데이터베이스로의 맵핑과. 데이터베이스의 성능을 향상시키기 위한 방안으로 내용질의와 함께 XML 문서의 특성을 활용한 구조 검색 질의를 하기 위한 효율적인 색인 모델을 제안한다. 내용 색인과 구조 색인, 애트리뷰트 색인을 각각 구성하여 내용과 구조가 혼합된 효율적인 검색이 가능하도록 하였다. 검색의 효율성을 위해 노드 간의 위치 정보와 함께 독립적인 ID를 부여하여 경로테이블을 생성하여 질의의 효율을 높인다.

• Journal of Bio-Environment Control
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• v.33 no.2
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• pp.120-128
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• 2024

Since ChatGPT was released in 2022, the generative artificial intelligence (AI) industry has seen massive growth and is expected to bring significant innovations to cognitive tasks. AI-based image generation, in particular, is leading major changes in the digital world. This study investigates the technical foundations of Midjourney, Stable Diffusion, and Firefly-three notable AI image generation tools-and compares their effectiveness by examining the images they produce. The results show that these AI tools can generate realistic images of tomatoes, strawberries, paprikas, and cucumbers, typical crops grown in greenhouse. Especially, Firefly stood out for its ability to produce very realistic images of greenhouse-grown crops. However, all tools struggled to fully capture the environmental context of greenhouses where these crops grow. The process of refining prompts and using reference images has proven effective in accurately generating images of strawberry fruits and their cultivation systems. In the case of generating cucumber images, the AI tools produced images very close to real ones, with no significant differences found in their evaluation scores. This study demonstrates how AI-based image generation technology can be applied in agriculture, suggesting a bright future for its use in this field.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.244-245
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• 2022

최근에는 우수한 성능의 딥러닝 기술을 활용한 장비와 프로그램이 개발되고 있으나 기술의 특성상 모든 환경에서 우수한 성능을 보여주지 못하고 고 사양의 서버와 같은 환경에서의 성능만을 보장하고 있다. 따라서 이에 대한 개선으로 엣지 디바이스 독립적으로 혹은 클라우드 의존과 인터넷 연결을 최소화 할 수 있는 엣지 컴퓨팅 기술이 제안되고 있으며 경량 내장형 시스템에 적합한 인공지능 기술의 개발이 필요하다. 본 논문에서는 객체검출 모델을 적은 연산과 효율적인 구조로 설계하고 생성된 모델을 임베디드 보드에서 원활하게 실행할 수 있도록 중립 모델로 변환하고 경량화 하는 방법에 대해 소개한다. Qualcomm snapdragon 프로세서가 갖춰진 임베디드 보드를 목표로 하였고 편의를 위해 SNPE(snapdragon neural processing engine) SDK를 이용하여 실험을 진행하였다. 실험 결과 변환된 중립모델이 기존 모델과 비교하여 압축된 모델 크기 대비 미미한 성능 저하가 발생함을 확인할 수 있었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.4
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• pp.385-392
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• 2015

Open city information model can increase the understanding of the situation, enable the effective reuse of information due to access the semantic and relational conditions of objects, and support the reliable decision-making through linking with external references. The city information model focused on terrain and buildings was implemented based on the actual data. In addition, a process for flooding simulation was proposed using hydraulic analysis data and the city information model. The deaths and damages were estimated by flooding simulation. The availabilities were examined by detailed queries and responses based on model data of the city information model, hydraulic analysis data and the estimated damages.

• Journal of KIISE:Software and Applications
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• v.37 no.7
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• pp.548-557
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• 2010

In this paper, we propose a semi-automatic modeling approach of ontology to annotate VOD to realize the IPTV's intelligent searching. The ontology is made by combining partial tree that extracts hypernym, hyponym, and synonym of keywords related to a service domain from WordNet. Further, we add to the partial tree new keywords that are undefined in WordNet, such as foreign words and words written in Chinese characters. The ontology consists of two parts: generic hierarchy and specific hierarchy. The former is the semantic model of vocabularies such as keywords and contents of keywords. They are defined as classes including property restrictions in the ontology. The latter is generated using the reasoning technique by inferring contents of keywords based on the generic hierarchy. An annotation generates metadata (i.e., contents and genre) of VOD based on the specific hierarchy. The generic hierarchy can be applied to other domains, and the specific hierarchy helps modeling the ontology to fit the service domain. This approach is proved as good to generate metadata independent of any specific domain. As a result, the proposed method produced around 82% precision with 2,400 VOD annotation test data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04a
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• pp.565-570
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• 1995

자동화 시스템이 형상모델링 시스템을 기반으로 구축된다면 형상모델링 시스템의 자료구조 및 제공되는 기능에 의존하게 된다. 따라서 형상모델링 시스템의 자료구조로 부터 각 시스템이 필요로하는 정보를 추출 하는 인터페이스 모듈 개발이 중요하다. 본 논문에서는 개방형 형상모델러를 기반으로, 설계 자동화의 대상이 되고 있는 유한 요소 모델링 방법에대해 살펴보고, 이 결과를 가시화 도구 PEX1ib와 X- window/Motif를 이용하여 가시화 하는 시스템에 대해 기술한다. 개방형 형상모델러로는 미국 Spatial Technology사의 ACIS를 이용하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1463-1471
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• 2012

In this study, a 3-axis camera system design is proposed for application to an existing 2-axis surveillance robot. A camera-image-based target-tracking algorithm for this robot has also been proposed. The algorithm has been validated using a virtual simulation. In the algorithm, the heading direction vector of the camera system in the mobile surveillance robot is obtained by the position error between the center of the view finder and the center of the object in the camera image. By using the heading direction vector of the camera system, the desired pan and tilt angles for target-tracking and the desired roll angle for the stabilization of the camera image are obtained through inverse kinematics. The algorithm has been validated using a virtual simulation model based on MATLAB and ADAMS by checking the corresponding movement of the robot to the target motion and the virtual image error of the view finder.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.393-398
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• 2016

Collective Adaptive System is an adaptive multi-agent system which accomplishes its goal by collaborating various agents. Because the collective property of the Collective Adaptive System is accomplished by the goal of the system being based on collaboration, testing the goal accomplishment and their interactions among heterogeneous agents is important. This paper presents a feasibility study of applying a model-based testing approach using task-based test model to a Collective Adaptive System. This paper describes additional information to be applied for Collective Adaptive System for future studies. To analyze our approach, we applied the proposed approach to a smart home system as a case study; our results indicated that we can systematically derive test cases to check whether the Collective Adaptive System successfully achieved its goals by modifying and extending the existing task model.

• Journal of the Korea Society for Simulation
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• v.16 no.4
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• pp.77-86
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• 2007

Web services are considered as the critical component in the business plans of corporations as they offers the potential for creating highly dynamic and versatile distributed applications that span across business boundaries. Web Service Orchestration studies composition of already-existing web services to create new value-added services. The composite web services could be executed in a centralized or peer-to-peer(P2P) orchestration model. Compared with centralized-orchestration model, the P2P-based orchestration model provides better scalability, reliability, and performance for the overall services. However, recent P2P-orchestration solutions have limitation in supporting complex workflow patterns. Therefore, they could not effectively handle sophisticated business workflow, which contains complex workflow patterns. In this paper, we propose the WORKGLOW system, which can deal with complex workflow patterns while it is able to perform composite services in P2P orchestration manner. Comparing with centralized orchestration systems, the WORKGLOW brings up more business logic advantages, better performance, and higher flexibility with only a little overhead.