• Journal of the Society of Naval Architects of Korea
• /
• v.61 no.4
• /
• pp.226-235
• /
• 2024

A method for quantifying the adaptability of ship maneuver scenarios for data-driven modeling of ship dynamics is developed based on the principal component analysis. A random maneuver scenario is suggested as a reference for ship dynamics, which can obtain the converged principal components of ship dynamics features by the Monte Carlo simulation. Principal components of conventional maneuver scenarios defined by the International Maritime Organization (IMO) are compared to that of the random maneuver. A conventional ship dynamics model for a container carrier vessel for four degrees of freedom dynamics is introduced to simulate the random and IMO maneuver scenarios. It is confirmed that the IMO tests follow the tendency of random maneuver scenario in terms of execution time and adaptability.

• Journal of KIISE:Software and Applications
• /
• v.35 no.2
• /
• pp.118-127
• /
• 2008

In this paper, we propose a method for construction of robust 3D statistical shape model in the mandible CT datasets. Our method consists of following four steps. First, we decompose a 3D input shape Into patches. Second, to generate a corresponding shape of a floating shape, all shapes in the training set are parameterized onto a disk similar to the patch topology. Third, we generate the corresponding shape by one-to-one mapping between the reference and the floating shapes. We solve the problem failed to generate the corresponding points near the patch boundary Finally, the corresponding shapes are aligned with the reference shape. Then statistical shape model is generated by principle component analysis. To evaluate the accuracy of our 3D statistical shape model of the mandible, we perform visual inspection and similarity measure using average distance difference between the floating and the corresponding shapes. In addition, we measure the compactness of statistical shape model using the modes of variation. Experimental results show that our 3D statistical shape model generated by the mandible CT datasets with various characteristics has a high similarity between the floating and corresponding shapes and is represented by the small number of modes.

• The Korean Journal of Applied Statistics
• /
• v.28 no.1
• /
• pp.103-114
• /
• 2015

The role of small and medium enterprises as an economic growth factor has been accentuated; consequently, the need to develop a business forecast model and indexes that accurately examine business situation of small and medium enterprises has increased. Most current business model and indexes concerning small and medium enterprises, released by public and private institutions, are based on Business Survey Index (BSI) and depend on subjective (business model and) indexes; therefore, the business model and indexes lack a capacity to grasp an accurate business situation of these enterprises. The business forecast model and indexes suggested in the study have been newly developed with Principal Component Analysis(PCA) and weight method to accurately measure a business situation based on reference dates addressed by the National Statistical Office(NSO). Empirical studies will be presented to prove that the newly proposed business model and indexes have their basis in statistical theory and their trend that resembles the existing Composite Index.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.11
• /
• pp.1272-1280
• /
• 2008

In this paper, we have proposed a phase noise model of fast frequency hopping synthesizer with DDS Driven PLL architecture. To accurately model the phase noise contribution of noise sources in frequency hopping synthesizer, they were investigated using model of digital divider for PLL, DAC for DDS and Leeson's model for reference oscillator and VCO. Especially it was proposed that the noise component of low pass filter was considered together with the phase noise of VCO. Under assuming linear operation of a phase locked loop, the phase noise transfer functions from noise sources to the output of synthesizer was analyzed by superposition theory. The proposed phase noise prediction model was evaluated and its results were compared with measured data.

• Proceedings of the Korean Information Science Society Conference
• /
• 2011.06b
• /
• pp.185-188
• /
• 2011

스마트폰의 대중화로 인해 사용자의 다양한 요구사항이 발생하고 있고, 스마트폰 용 어플리케이션에 대한 개발이 활발히 수행되고 있으나 하드웨어와의 밀접한 관계 및 재사용성의 요구를 반영하고 있지 못하므로 향후 수요를 감안하여 객체지향 개발방법론을 적용한 체계적인 접근이 필요하다. 본 논문에서는 대표적인 스마트폰 플랫폼인 안드로이드와 아이폰 플랫폼의 수명주기, 하드웨어, 어플리케이션 간의 관계를 통해 스마트폰 어플리케이션 개발절차를 도출하도록 시도하였으며, 객체지향 개발방법론 중에서 Reference Model 중심의 안드로이드 플랫폼과 Rich Client를 지원하는 아이폰 플랫폼에 각각 스마트폰 플랫폼에 준한 하드웨어 특성을 고려하여 특화된 CBD(Component Based Development)기반인 마르미-EM방법론과 서비스 기반의 어플리케이션을 지향하고 있는 MVC(Model-View-Control)패턴이 적용된 SaaS(Software-as-a-Service) 개발방법론을 적용하여 어플리케이션 개발 절차를 비교한다. 이를 통하여 개발방법론의 절차상의 차이점, 강점 및 보완 사항을 분석하고 방법론별 특징을 토대로 향후 보완점을 제안한다.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.6
• /
• pp.2354-2363
• /
• 2018

This paper proposed a novel double closed control strategy for single-phase voltage source pulse width modulation (PWM) rectifier based on active disturbance rejection control (ADRC) and dq current decoupling control. First, the mathematical model of the single-phase PWM rectifier in the d-q axis synchronous rotating reference frame is established by constructing a virtual component using a second-order generalized integrator (SOGI). Then, the mathematical model is simplified according to the active power conservation, and the first-order equation of single-phase PWM rectifier voltage outer loop is acquired. A linear auto-disturbance rejection controller is used to design the voltage outer loop according to the first-order equation. Finally, the proposed control strategy and the traditional PI control are compared and verified by simulation and physical experiments. Both simulation and experimental results confirm that the proposed control strategy has excellent dynamic performance and strong rejection ability to disturbances.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.25 no.6_1
• /
• pp.537-543
• /
• 2007

Since the GPS absolute positioning with pseudorange measurements can significantly be affected by the observation error, the time series analysis of the GPS receiver clock errors was performed in this study. From the estimated receiver clock errors, the time series model is generated, and constrained back in the absolute positioning process. One of the CORS (Continuously Operating Reference Stations) network is used to analyze the behavior of the receiver clock. The dominant part of the model is the linear trend during 24 hours, and the seasonal component is also estimated. After constraining the modeled receiver clock errors, the estimated position error compared to the published coordinates is improved from ${\pm}11.4\;m\;to\;{\pm}9.5\;m$ in 3D RMS.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.10A
• /
• pp.1521-1528
• /
• 2000

In this paper we analyze the performance of a DS/CDMA system in LEO mobile satellite channels. The channel uses the Extended Suzuki model which is the product of a Rician distribution having a LOS component and a lognormal distribution due to shadowing. We assume that the signal transmitted from the satellite to the mobile undergoes the same fading for the whole coverage of signal's beam. The average bit error probabilities of double coverage system is calculated in this paper. The interference resulting from the reference satellite is calculated for mobile located in the middle of the double coverage region whereas the additive interference from next-satellite is included for mobile located in the edge of the double coverage region. The performance of the mobile's receiving signal is dependent on shadowing and the interference of the next-satellite. We can obtain an obtain an improved average bit error probability by using dual diversity over the conventional correlated receiver for similar shadowing conditions in the coverage area of the satellite channel.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.524-531
• /
• 2008

A method for representing detailed design information of steel bridge member is proposed on the basis of the IFC model. As a first step, bridge related entities in the IFC-BRIDGE V2 and their functions are analyzed. In addition, design documents of steel bridge members are analyzed to extract information items that are not handled in the IFC-BRIDGE V2. It is recommended that several entities in the IFC-BRIDGE V2, such as ifcBridgeFibre, IfcBridgeReferenceLine, and IfcBridgeSection, should be properly relocated. In addition, IfcBridgeStiffener, IfcBridgeJointSystem, IfcBridgeDiaphragm, and IfcBridgeShearConnector are added as subtypes of IfcBridgeElementComponent for representing the stiffener, joint system, diaphragm, and shear connector, respectively. The added new entities inherit all attributes of IfcProduct which is linked with other resources: geometric representation, placement, material information, and so on. Thus, it is considered that a proposed in-depth IFC-BRIDGE model can be used more widely.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1287-1292
• /
• 2005

This paper presents an effective pattern classification model by designing an artificial neural network based pattern classifiers for face recognition. First, a RGB image inputted from a frame grabber is converted into a HSV image which is similar to the human beings' vision system. Then, the coarse facial region is extracted using the hue(H) and saturation(S) components except intensity(V) component which is sensitive to the environmental illumination. Next, the fine facial region extraction process is performed by matching with the edge and gray based templates. To make a light-invariant and qualified facial image, histogram equalization and intensity compensation processing using illumination plane are performed. The finally extracted and enhanced facial images are used for training the pattern classification models. The proposed H-ART2 model which has the hierarchical ART2 layers and F-LVQ model which is optimized by fuzzy membership make it possible to classify facial patterns by optimizing relations of clusters and searching clustered reference patterns effectively. Experimental results show that the proposed face recognition system is as good as the SVM model which is famous for face recognition field in recognition rate and even better in classification speed. Moreover high recognition rate could be acquired by combining the proposed neural classification models.