• 로봇학회논문지
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• 제12권1호
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• pp.33-41
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• 2017

We present a region-based approach for accurate pose estimation of small mechanical components. Our algorithm consists of two key phases: Multi-view object co-segmentation and pose estimation. In the first phase, we explain an automatic method to extract binary masks of a target object captured from multiple viewpoints. For initialization, we assume the target object is bounded by the convex volume of interest defined by a few user inputs. The co-segmented target object shares the same geometric representation in space, and has distinctive color models from those of the backgrounds. In the second phase, we retrieve a 3D model instance with correct upright orientation, and estimate a relative pose of the object observed from images. Our energy function, combining region and boundary terms for the proposed measures, maximizes the overlapping regions and boundaries between the multi-view co-segmentations and projected masks of the reference model. Based on high-quality co-segmentations consistent across all different viewpoints, our final results are accurate model indices and pose parameters of the extracted object. We demonstrate the effectiveness of the proposed method using various examples.

• 한국가스학회지
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• 제7권3호
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• pp.32-43
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• 2003

이 연구는 단성분계(메탄)과 다성분계(천연가스) 하이드레이트의 상평형 조건을 관찰하고, 반응시간에 따른 하이드레이트 생성 거동을 관찰하여 비교 분석하였다. 단성분과 다성분계 하이드레이트의 차이점은 크게 유도지체시간과 안정 영역이다. 반응시 다성분계 하이드레이트는 가스의 성분들이 서로 다른 농도변화를 나타내었으며, 제조된 하이드레이트를 해리시켰을 때도 서로 다른 해리 속도에 의해 각 가스 성분들의 농도가 변화되었다. 압력이 6 MPa이고, 온도가 276.65 K이며, 교반속도가 600 rpm일때 다성분계 하이드레이트 제조시 메탄이외의 여러 가스 성분들에 의해 하이드레이트 핵 생성이 빠르게 진행되어 유도지체시간은 짧다. 그리고 단성분계 하이드레이트는 단일 성분으로 이루어져 있으므로 안정 영역이0.055 mole of $CH_4$/mole of water에서 보다 뚜렷하게 관찰되고, 다성분계 하이드레이트는 안정 영역이 0.04 mole of $CH_4/$mole of water에서 관찰된다.

• Journal of Positioning, Navigation, and Timing
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• 제10권3호
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• pp.215-220
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• 2021

As the role of robots expands, flexible task planning methods are attracting attention from various domains. Many task planning frameworks are introduced to efficiently work in a wide range of areas. In order to work well in a broad region with multiple robots, various communication conditions should be controlled by task planning frameworks. However, few methods are proposed. In this paper, we propose mission planning methods according to the communication status of robots. The proposed method was verified through experiments assuming different communication states with a multi-robot system.

• 한국광학회지
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• 제17권2호
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• pp.191-197
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• 2006

두 개의 DFB 영역과 위상조정 영역으로 구성된 다중 영역 복소 결합 DFB 레이저에서 방출되는 두 모드의 비팅에 의해서 발생하는 Self-Pulsation(SP) 동작 특성을 전산 모의 하였다. SP 주파수는 두 DFB 영역에서 발진하는 모드의 파장 차이에 의해 결정되며, 각각의 DFB 영역의 발진 모드의 파장은 회절격자 주기의 변화에 의해 달라진다. 두 DFB 영역의 회절격자의 주기 차이를 변화시킴으로써 다중 영역 DFB 레이저에서 밭생하는 SP 주파수를 매우 낮은 주파수에서 THz 영역까지 변화시킬 수 있었다. 또한 발진 모드가 다른 DFB 영역의 금지대역에 놓이지 않는 경우 발진되는 모드는 다른 DFB 영역으로 큰 반사 없이 진행하여 두 모드들 사이의 상호작용이 크게 발생하여 index-coupled 회절격자를 가지는 다중 영역 DFB 레이저와는 달리 변조 지수가 매우 큰 출력을 얻을 수 있었다.

• Journal of Positioning, Navigation, and Timing
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• 제8권1호
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• pp.1-12
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• 2019

In this paper, we implement a navigation software of a Global Navigation Satellite System (GNSS) receiver based on a commercial purpose GNSS software receiver platform and verify its performance by performing experimental tests for various GNSS signals available in Korea region. The SX3, employed in this paper, is composed of an application program and a Radio Frequency (RF) frontend, and can capture and process multi-constellation and multi-frequency GNSS signals. All the signal processing procedure of SX3 is accessible by the receiver software designer. In particular for an easy research and development, the Application Programing Interface (API) of the SX3 has a flexible architecture to upgrade or change the existing software program, equipped with a real-time monitoring function to monitor all the API executions. Users can easily apply and experiment with the developed algorithms using a form of Dynamic Link Library (DLL) files. Thus, by utilizing this flexible architecture, the cost and effort to develop a GNSS receiver can be greatly reduced.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.395-402
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• 2006

In analyzing the nano-scale phenomena or behaviors of nano devices or materials, it is often desirable to deal with more atoms than can be treated only with a full atomistic simulation. However, even now, it is advisable to apply the atomistic simulation to the narrow region where the deformation field changes rapidly but to apply the conventional continuum model to the region far from that region. This equivalent continuum model can be formulated by applying the Cauchy-Born rule to the exact atomistic potential as in the quasicontinuum method. To couple the atomistic model with the equivalent continuum model, continuum displacements are conformed to the molecular displacements at the discrete positions of the atoms within the bridging domain. To satisfy the coupling constraints, we apply the Lagrange multiplier method. The continuum model in the bridging model should be applied on the region where the deformation field changes gradually. Then we can make the nodal spacing in the continuum model be much larger than the atomic spacing. In the first step, we generate the atomic-resolution mesh with the nodal spacing equal to the atomic spacing, and then we eliminate the nodal degrees of freedom adaptively using the node deactivation techniques. We eliminate more DOFs as the regions are more far from the atomistic region. Computing time and computational resources can be greatly reduced by the present node deactivation technique in multi scale analysis.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제16권4호
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• pp.246-253
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• 2016

Infrared (IR) imaging has been researched for various applications such as surveillance. IR radiation has the capability to detect thermal characteristics of objects under low-light conditions. However, automatic segmentation for finding the object of interest would be challenging since the IR detector often provides the low spatial and contrast resolution image without color and texture information. Another hindrance is that the image can be degraded by noise and clutters. This paper proposes multi-level segmentation for extracting regions of interest (ROIs) and objects of interest (OOIs) in the IR scene. Each level of the multi-level segmentation is composed of a k-means clustering algorithm, an expectation-maximization (EM) algorithm, and a decision process. The k-means clustering initializes the parameters of the Gaussian mixture model (GMM), and the EM algorithm estimates those parameters iteratively. During the multi-level segmentation, the area extracted at one level becomes the input to the next level segmentation. Thus, the segmentation is consecutively performed narrowing the area to be processed. The foreground objects are individually extracted from the final ROI windows. In the experiments, the effectiveness of the proposed method is demonstrated using several IR images, in which human subjects are captured at a long distance. The average probability of error is shown to be lower than that obtained from other conventional methods such as Gonzalez, Otsu, k-means, and EM methods.

• ETRI Journal
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• 제29권5호
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• pp.700-702
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• 2007

We present a relevance feedback approach based on multi-class support vector machine (SVM) learning and cluster-merging which can significantly improve the retrieval performance in region-based image retrieval. Semantically relevant images may exhibit various visual characteristics and may be scattered in several classes in the feature space due to the semantic gap between low-level features and high-level semantics in the user's mind. To find the semantic classes through relevance feedback, the proposed method reduces the burden of completely re-clustering the classes at iterations and classifies multiple classes. Experimental results show that the proposed method is more effective and efficient than the two-class SVM and multi-class relevance feedback methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1033-1035
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• 2003

Linear induction motor with multilayer region of the single-sided is analyzed considering multi region traveling wave problem. A hybrid method of analysis consisting of field analysis in conjunction with the multilayer transfer matrix concept with adjustment of secondary iron permeability to match the tangential magnetizing field in each layer is developed.

• 한국공간구조학회논문집
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• 제18권4호
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• pp.97-104
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• 2018

A connected control method for the adjacent buildings has been studied to reduce dynamic responses. In these studies, seismic loads were generally used as an excitation. Recently, multi-hazards loads including earthquake and strong wind loads are employed to investigate control performance of various control systems. Accordingly, strong wind load as well as earthquake load was adopted to evaluate control performance of adaptive smart coupling control system against multi-hazard. To this end, an artificial seismic load in the region of strong seismicity and an artificial wind load in the region of strong winds were generated for control performance evaluation of the coupling control system. Artificial seismic and wind excitations were made by SIMQKE and Kaimal spectrum based on ASCE 7-10. As example buildings, two 20-story and 12-story adjacent buildings were used. An MR (magnetorheological) damper was used as an adaptive smart control device to connect adjacent two buildings. In oder to present nonlinear dynamic behavior of MR damper, Bouc-Wen model was employed in this study. After parametric studies on MR damper capacity, optimal command voltages for MR damper on each seismic and wind loads were investigated. Based on numerical analyses, it was shown that the adaptive smart coupling control system proposed in this study can provide very good control performance for Multi-hazards.