• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2213-2215
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• 2000

In this paper we implemented a novel re-entrant mode microstrip directional coupler for realizing the high directivity characteristic using finite element (FE) analysis. In microstrip configuration, the high directivity can be reached by matching the even- and odd-mode effective phase velocities. Through the values of capacitance obtained from 2-dimensional finite element(FE) analysis, the phase velocities for each mode and the design parameter were extracted for the proposed coupled-line configuration. Based on the extracted design parameter with phase matching condition we designed and fabricated 30dB directional coupler at 850MHz. Experimental results show good performance with excellent isolation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.111-112
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• 2015

Garak Market Modernization Project Phase 1, which is the public projects worth 1,75 billion won, was delivered by adopting modifiable bid of BOQ on the lowest price award system. The modifiable bid of BOQ system allows bidders to modify quantities based on their own drawings and construction specifications and requirements. It was initiated by the government for minimizing design error and for inducing technical competition between tenders by checking errors. At that time the bidding, it allowed modifying the BOQ all the works. In the construction phase, the responsibility for the design changes, due to mistakes and omissions on design documents and BOQ were disputed between the owner and the contractors. This study analyzed the problem of the system and addressed a need of improvement.

• Journal of the Korean Professional Engineers Association
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• v.26 no.1
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• pp.18-28
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• 1993

The Studies on Quality Assurance Activities at the Phase of Planning - Design Are Quite Rare, While Those Activies are very Important, This Study is Focused on the Applicability of Quality Function Development System to the Phase of Planning-Design, With a Matrix of the Quality Assurance Activities and Quality Function Develop-ment System. The Application of a Quality Function Development System to the Quality Assurance Activities (1) Makes it Easier to Easier out the Quality Level that Consumers Demand and Varies Rapidly, and (2) Makes it Possible to Link the Production to the Quality Level that Consumers Demand by the Quality Specification.

• Proceedings of the KIEE Conference
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• summer
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• pp.884-886
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• 2004

This paper introduces Flux-Reversal Machine(FRM) and presents the design of a single phase FRM to improve its starting torque. The effects of the design parameters on the characteristic and starting torque are analyzed by Finite Element Method(FEM). The considered design parameters are tapered airgap, stewed airgap, asymmetric PM width and slotted teeth. As a result, we can find the best model in producing starting torque of a single phase 2/3 FRM

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.226-228
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• 2007

SRM drive systems are designed to meet operating standards such as low cost, constant torque independent of rotor position, a desired operating speed range, high efficiency, and high performance. In applications using small motors, low cost and high performance with self-starting capabilities are highly desired. This paper discusses a novel two phase SRM (TPSRM) that has high performance characteristics with self-starting capability, low manufacturing cost with a two phase inverter and simple magnetic structure, and high efficiency. The principle of operation, analysis, and simulation for design are presented. The machine design is verified using finite element analysis (FEA) software. Analysis and simulation results are given to validate the TPSRM design.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1002-1004
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• 2005

This paper describes the performance analysis and design of single-phase self-excited induction generators. In this study, it is proposed to design the proper capacitance for self-excitation and voltage regulation, also. This methods are based on the induced MMF equations between main and the auxiliary winding. For the least influence between the two capacitors, the self-excited capacitor is selected under no load condition, while the series capacitor is designed under loaded condition. For the steady state analysis, the equivalent circuit of single-phase induction generators is used as circuit modeling using the double-revolving field theory. The validity of proposal methods and designed generator system will be confirmed by experimental and computed results.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.70-79
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• 2012

A design guide to type-3 PLLs for FMCW radars is provided. To do that, the cross-over frequencies of the open-loop transfer functions were normalized to 1 Hz and closed-loop properties were compared through simulations using Pspice. As a result, several guides to design type-3 PLLs were provided: 1) secure 45 degrees of phase margin, 2) locate two zeroes at an identical frequency, and 3) poles may be added to raise order of the PLL at higher frequencies than the cross-over frequency of the open-loop transfer function about ten times.

• Journal of Magnetics
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• v.18 no.1
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• pp.57-64
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• 2013

Flux linkage of phase windings is a key parameter in determining the behavior of a switched reluctance motor (SRM) [1-8]. Therefore, the accurate prediction of flux linkage at aligned and unaligned rotor positions makes a significant contribution to the design of an SRM and its analytical approach is not straightforward due to nonlinear saturation in flux. Although several different approaches using a finite element analysis (FEA) or a curve-fitting tool have been employed to compute phase flux linkage [2-5], they are not suitable for a simple design procedure because the FEA necessitates a large amount of time in both modeling and solving with complexity for every motor design, and the curve-fitting requires the data of flux linkage from either an experimental test or an FEA simulation. In this paper, phase flux linkage at aligned and unaligned rotor positions is estimated by means of a reluctance network, and the proposed approach is analytically verified in terms of accuracy compared to FEA.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1118-1124
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• 2023

Experimental study on the fluidelastic instability (FEI) of a curved tube bundle in single phase downward cross flow is investigated for the design qualification and analysis input preparation of helical coiled steam generator tubing. A 6×9 normal square curved tube array with equal and different vertical/horizontal pitch-to-diameter ratio was under-tested up to 6 m/s in term of gap flow velocity to measure the critical velocity for FEI. The critical velocity for FEI was measured at the turning point from the vibration amplitude plot along the gap flow velocity. Our test results were compared with straight tube results and published data in the design guideline. The applicability of the current design guidelines to a curved tube bundle is also assessed. We found that introducing frequency difference in a curved tube array increases the critical velocity for fluidelastic instability.

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.10a
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• pp.57.2-57
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• 2001