• Proceedings of the KSME Conference
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• 2000.11b
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• pp.205-209
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• 2000

The performances of cascade-type thermoelectric modules are analysed by numerical simulations. The geometrical variations are used as design parameters.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1663-1674
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• 2017

This paper deals with the robust speed regulation of a surface-mounted permanent magnet synchronous motor (SPMSM) that is subject to parametric uncertainties and external disturbances. The proposed approach retains a conventional cascade control configuration composed of an outer-loop speed control module and inner-loop current control modules. Baseline proportional-integral (PI) controllers are designed for nominal modular systems without accounting for the uncertainties to set a desired control performance of the closed-loop system. After studied in both frequency and time domains, a reduced-order proportional-integral observer (PIO), as a modular disturbance observer, is incorporated with each control module to maintain the ideal performance of the modules. Theoretical analysis confirms the desired performance recovery of the augmented system with modular PIOs to the nominal system. Comparative computer simulations and experimental results validate the proposed cascade control method for SPMSM speed regulation.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.366-370
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• 2003

This paper introduces a new design and fabrication technology of 28 GHz low-cost up and down converter modules for digital microwave radios, The design of the converter module is based on unit circuit blocks, which are to be characterized using a special test fixture. Based on the cascade analysis of the module the 28 GHz up and down converter modules have been designed and implemented. The measured module performance agrees with the cascade analysis. New components such as a tapped edge-coupled filter and a new Ka-band waveguide-to-microstrip transition, which are less sensitive to fabrication tolerances, have been used in the module implementation.

• Journal of the Korea Society of Computer and Information
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• v.22 no.3
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• pp.27-34
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• 2017

We propose a cascade lane detector that uses biased discriminant analysis (BDA) to work effectively even when there are various external factors on the road. The proposed cascade detector was designed with an existing lane detector and the detection module using BDA. By placing the BDA module in the latter stage of the cascade detector, the erroneously detected results by the existing detector due to sunlight or road fraction were filtered out at the final lane detection results. Experimental results on road images taken under various environmental conditions showed that the proposed method gave more robust lane detection results than conventional methods alone.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.118-125
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• 2017

In this paper, we propose a smart transformer for a smart transformer miniature model, which can replace a 60 [Hz] single-phase transformer installed in an electric vehicle. The proposed smart transformer is lighter than a conventional transformer, can control instantaneous voltage, and can be expected to improve power quality through harmonic compensation. The proposed intelligent transformer consists of an incoming part, an AC/DC converter, and a dual active bridge. Only the incoming part and the AC/DC converter are described in this paper. The proposed intelligent transformer has 75 kVA 3.3 kV input and 750 V DC output, which are verified by simulation and experiment.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.87.2-87.2
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• 2011

Many type of fuel cell stacks have been developed to improve the efficiency of reactants usage. The cascade type fuel cell stack using dead end operation is able to attain above 99% usage of hydrogen and oxygen. It is sectionalized to several parts and the residual reactants which are used previous parts would be supplied again to next parts which have less number of cells in dead end operation stack. The oversupply of reactants which is usually 120%~150% of the theoretical amount to generate current for preventing the flooding effect could be provided to each part except the last one. The final section which is called monitoring cells is supposed to be supplied insufficient the fuel or oxidant that would have some accumulated inert gas from former parts. It makes some voltage drop in the part and the fresh reactants must be supplied to the part for recovering it by venting the residual gas. So the usage of fuel and oxidant is depend on the time and frequency of opening valves for venting of residual gas and it is important to optimize the vent logic for achieving higher usage of hydrogen and oxygen. In this research, many experiments are performed to find optimal condition by evaluating the effect of time and frequency under several power conditions using over 100kW class fuel cell module. And the characteristics of the monitoring cells are studied to know the proper cell voltage which decide the condition of opening the vent valve for stable performance of the cascade type fuel cell module.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.12
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• pp.641-646
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• 2013

The purpose of this study is to improve the cooling performance of single and cascade refrigeration systems using thermoelectric modules. The system consists of a heat sink, fan, and thermoelectric module. The operating parameters considered in this study include power distribution between the first- and second-stage thermoelectric modules, air flow, and variable condensing unit. The cooling capacity increased with decreases in the temperature difference between hot and cold surfaces, but decreased with increases in the condensing temperature. The COP decreased with increasing electric power of the thermoelectric module because of the increased Joule heat. The cooling performance improvement using the thermoelectric module is represented by the freezer temperature.

• Journal of Power Electronics
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• v.14 no.1
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• pp.143-155
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• 2014

The stability issues of a multi-module distributed DC power system without current-sharing loop are analyzed in this study. The physical understanding of the terminal characteristics of each sub-module is focused on. All the modules are divided into two groups based on the different terminal property types, namely, impedance (Z) and admittance (Y) types. The equivalent circuits of each group are established to analyze the stability issues, and the mathematical equations of the equivalent circuits are derived. A generalized criterion for multi-module distributed systems is proposed based on the stability criterion in a cascade system. The proposed criterion is independent of the power flow direction.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.295-299
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• 2004

A new design technique of fabricating 40 GHz up-converter modules for digital microwave radios has been developed. The design of the up-converter module is based on unit circuit blocks, which are to be characterized using a special test fixture. The complete module design may be as simple as a cascade layout of these unit circuit blocks. Also, the 40 GHz up-converter module employs a new microstrip-to-waveguide transition and a tapped edge-coupled filter, which are less sensitive to fabrication tolerances.

• Journal of IKEEE
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• v.11 no.4
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• pp.358-363
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• 2007

This paper presents a floating point unit(FPU) with 3 stages for a 3D graphics shader engine. It targeted to accelerate 3D graphics in portable device environments. In order to design a balanced architecture for a shader engine, we analyzed shader assembly instructions and estimated the performance of FPU with the method we propose. The proposed unit handles 4-dimensional data through separated two paths that are lead to general operation module and special function module. The proposed FPU is compiled as a form of the cascade FPU with 3 stages to efficiently handle a matrix operation with relatively low hardware overhead. Except some complex instructions that are executed using macro instructions, all instructions complete an operation in a single instruction cycle at 100MHz frequency. A special function module performs all operations in a single clock cycle using the Newton Raphson method with the look-up table.