• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.485-487
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• 2006

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been performed for the elimination of speed and position sensors. This paper investigates an Improved sliding mode observer for the speed sensorless control of a permanent magnet synchronous motor. The proposed control strategy is the sliding mode observer with a variable boundary layer for a low-chattering and fast-reponse control. The proposed algorithm is verified through the simulation and experimentation.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.235-237
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• 2005

This study investigates Characteristic analysis of Line-start Synchronous Reluctance Motor to substitute for Induction Motor. The results of machine characteristics are analyzed by simulation using Flux2D. Characteristic analysis result of Line-start Synchronous Reluctance Motor is confirmed by the Experimental result.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.933-935
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• 2005

This study investigates Characteristic analysis of Line-start Synchronous Reluctance Motor to substitute for Induction Motor. The results of machine characteristics are analyzed by simulation using Flux2D. Characteristic analysis result of Line-start Synchronous Reluctance Motor is confirmed by the analysis result of 3-Phase Induction Motor.

• Journal of Gastric Cancer
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• v.9 no.3
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• pp.128-135
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• 2009

Purpose: The aim of this study was to compare synchronous and metachronous hepatic metastases in patients with gastric cancer to determine clinicopathologic features and differences in prognosis as a function of the timing of the metastasis and the treatment modality rendered. Materials and Methods: Sixty-seven patients who were diagnosed with gastric cancer metastatic to the liver and treated at the Hanyang University Hospital between June 1992 and December 2006 were retrospectively analyzed to study the pertinent clinicopathologic features and effect of treatment methods. Results: There was a significant difference with respect to lymphatic (P=0.041) and vascular invasion (P=0.036) in comparing the clinicopathologic features between the patients with synchronous and metachronous hepatic metastases. The 1-year survival rate and median survival time of patients with gastric cancer and liver metastases were 38.9% and 9.2 months in the entire patient cohort, 30.9% and 9.2 months in the synchronous group, and 44.5% and 9.7 months in the metachronus group, respectively (P=0.436). The group of patients undergoing local treatment (such as surgery and radiologic intervention) followed by systemic chemotherapy, the group of patients receiving systemic chemotherapy only, and the untreated group of patients were compared, and there was no difference between the synchronous and metachronous groups. The synchronous and metachronous groups had high survival rates with local treatment. Conclusion: In patients with gastric cancer and liver metastases, there was no difference in prognosis based on the timing of the hepatic metastases. Independent of the timing of hepatic metastasis, aggressive treatment, such as surgery and radiologic intervention, may help improve the prognosis.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.12-14
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• 2005

This study investigates the characteristic analysis of Line-start Permanent Magnet Synchronous Motor considering skew effect. The effects of the skew on machine characteristic are analyzed by using direct co-simulation of Matlab Simulink and Flux2D. Validity of analysis method is confirmed by the analysis result of Non-skew Model.

• Journal of the Korean Operations Research and Management Science Society
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• v.24 no.4
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• pp.157-170
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• 1999

The web-based groupware systems hold many possibilities for system developers and users. Especially, web-based group collaborative systems are emerging as enterprise-wide information systems. Since data in group collaborative systems are apt to be shared among multiple concurrent users and modified simutaneously by them, the web-based group collaborative systems must support synchronous collaboration in order to provide users with synchronized and consistent views of shared data. However, current web technologies have limitations in supporting this, largely because the existing Hypertext Transfer Protocol(HTTP) is unidirectional and does not allow web servers to send messages to their web browsers without first receiving requests from them. This paper proposes an active web server that can overcome such limitations and facilitate synchronous collaboration in web-based group collaborative systems. To accomplish such goals, the active web server manages dependency relationships beween shared data and web browsers referencing them and actively propagates changing details of the shared data to all web browsers referencing them. And, this paper examines usefulness and effectiveness of the active web server to apply it to the ball-bearing design example of concurrent engineering design systems. The prototype system of the active web server is developed on a commercial Object-oriented Database Management System(0DBMS) called OBJECTSTERE using the C++ programming language.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.162-169
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• 2022

Arduino is used in various places such as education, experimentation, and industry. Due to the easy accessibility of Arduino, it is often used by non-majors, and it is also used in media art and toy programs. Although Arduino is relatively easy to use compared to other devices, it is not easy to control various IoT components at the same time. Some tasks run independently of other tasks, while others run dependently. In this paper, I proposed the Arduino Task Framework to efficiently execute many tasks in these various situations. The design framework of this paper is largely composed of two types: synchronous execution and asynchronous execution. These two execution methods can be combined to create several independent and dependent execution routines. Asynchronous tasks are independently executed tasks and are managed by AsyncTaskGroup, while synchronous tasks are dependently executed tasks and are managed by SyncTaskGroup. AsyncTaskGroup instance and SyncTaskGroup instance are instances of the same Task and can be used in combination with another task. The Arduino framework proposed in this paper simplifies the program structure and can easily compose various tasks.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.86-88
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• 2003

The efficiency of electric machine is important due to increase of interest about energy saving. Single Phase Line Start Permanent Magnet Synchronous Motor has high efficiency and power factor. LSPMSM offer a high efficiency as compared induction motor which are used in the home appliance. The analysis and design of LSPMSM is difficult because of unbalanced rotating magnetic field, nonlinear characteristics and rotor saliency. To consider these effects, F.E.M(Finite Element Methods) is coupled equivalent circuit methods. In this paper, a methods of analysis and design using F.E.M and equivalent circuit is represented.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.37-39
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• 2004

This study investigates the characteristic analysis of Line-start Permanent Magnet Synchronous Motor considering PWM Inverter. The effects of the PWM inverter on machine characteristic are analyzed by using direct co-simulation of Matlab Simulink and Flux2D. Validity of analysis method is confirmed by the analysis result of Sin-wave power Model.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1025-1026
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• 2007

Recently study on components for a electric golf car and a utility car driven by a electric motor has been performed actively, and the study on a drive motor, a inverter and a battery focuses on a small, light weight and high power density source to improve fuel efficiency using limited electric energy. Especially, since a utility car such as a golf car performance depends on initial acceleration and maximum speed capability, a drive system requires high power and large and wide operation area, This study therefore investigates on the interior permanent magnet synchronous motor with high power density and wide operation, and is verified with the test result after design and characteristic analysis is performed