• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.3
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• pp.6-15
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• 2000

In this paper, we propose a high speed parallel multiplier with a hierarchical architecture using a fast 4-2 compressor and 6-2 compressor. Generally, the performance of parallel multiplier depends on the processing speed of partial products summation tree with CSA adder. In this paper we propose a new circuit of 4-2 compressor and 6-2 compressor which reduces the propagation delay time, compared with conventional one. We Propose a hierarchical multiplier architecture in order to improve the execution speed of 16$\times$16 parallel multiplier using proposed compressors in this paper and make layout design easily by regular structure. The propagation delay time of the proposed 4-2 compressor circuit was 14% reduced as a result of SPICE simulation, compared with the conventional 4-2 compressor. The total propagation delay time of proposed 16$\times$16 parallel multiplier was 12% reduced using proposed 4-2 compressor and 6-2 compressor.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.173-180
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• 2022

Approximate Computing is a promising method for designing hardware-efficient computing systems. Approximate multiplication is one of key operations used in approximate computing methods for high performance and low power computing. An approximate 4-2 compressor can implement hardware-efficient circuits for approximate multiplication. In this paper, we propose an approximate multiplier with low area and low power characteristics. The proposed approximate multiplier architecture is segmented into three portions; an exact region, an approximate region, and a constant correction region. Partial product reduction in the approximation region are simplified using a new 4:2 approximate compressor, and the error due to approximation is compensated using a simple error correction scheme. Constant correction region uses a constant calculated with probabilistic analysis for reducing error. Experimental results of 8×8 multiplier show that the proposed design requires less area, and consumes less power than conventional 4-2 compressor-based approximate multiplier.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.401-402
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• 2009

4-2 compressor는 곱셈기의 부분 곱 합 트리(partial product summation tree)의 기본적인 구성요소이다. 본 논문은 고속 연산이 가능한 4-2 compressor 구조를 제안한다. 제안한 회로는 최적화된 XORXNOR와 MUX로 구성하였다. 이 회로는 기존의 회로와 비교하였을 때 회로 구성에 필요한 트랜지스터수가 12개 감소하였으며, 지연시간이 32.2% 감소하였다. 제안한 회로는 Samsung 0.18um CMOS 공정을 이용하여 HSPICE로 시뮬레이션 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.405-406
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• 2009

4-2 compressor는 곱셈기의 부분 곱 합 트리(partial product summation tree)의 기본적인 구성요소이다. 본 논문은 저 전력 특성을 갖는 4-2 compressor 구조를 제안한다. 제안한 회로는 한 개의 전가산기와 MUX로 구성하였다. 이 회로는 기존의 회로와 비교하였을 때 회로 구성에 필요한 트랜지스터수가 14개 감소하였으며, 6.3%의 전력소모가 감소하였다. 제안한 회로는 Samsung 0.18um CMOS 공정을 이용하여 HSPICE로 시뮬레이션 하였다.

• The KSFM Journal of Fluid Machinery
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• v.14 no.4
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• pp.5-11
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• 2011

This study investigated on details of flow characteristics in a vaneless diffuser of a compressor with 2-dimensional impeller at various flow rates. Experiment for a low speed compressor model in a water reservoir was performed to analyze the flow field in the vaneless diffuser and volute casing, which was done by PIV measurement. It was also focused on the periodic flow patterns occurring at low flow rate near unstable operating region of the compressor. At low flow rate condition, the flow visualization clearly shows that the flow energy from impeller is highly accumulated at the compressor exit by the blockage effect of a flow damper and consequently the reverse flow occurs in the diffuser.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.2
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• pp.285-290
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• 2023

Compressors are widely used in high-speed electronic systems and are used to reduce the number of operands in multiplier. The proposed compressor is constructed based on the m-GDI(: modified gate diffusion input) to reduce the propagation delay time. This paper is compared the performance of compressors by applying 4-2, 5-2 and 6-2 m-GDI compressors to the multiplier, respectively. As a simulation results, compared to the 8-bit Dadda multiplier using the 4-2 and 6-2 compressor, the multiplier using the 5-2 compressor is reduced propagation delay time 13.99% and 16.26%, respectively. Also, the multiplier using the 5-2 compressor is reduced PDP(: Power Delay Product) 4.99%, 28.95% compared to 4-2 and 6-2 compressor, respectively. However, the multiplier using the 5-2 compression circuit is increased power consumption by 10.46% compared to the multiplier using the 4-2 compression circuit. In conclusion, the 8-bit Dadda multiplier using the 5-2 compressor is superior to the multipliers using the 4-2 and 6-2 compressors. The proposed circuit is implemented using TSMC 65nm CMOS process and its feasibility is verified through SPECTRE simulation.

• International Journal of Fluid Machinery and Systems
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• v.4 no.2
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• pp.271-288
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• 2011

The mathematical modelling of screw compressor processes and its implementation in their design began about 30 years ago with the publication of several pioneering papers on this topic, mainly at Purdue Compressor Conferences. This led to the gradual introduction of computer aided design, which, in turn, resulted in huge improvements in these machines, especially in oil-flooded air compressors, where the market is very competitive. A review of progress in such methods is presented in this paper together with their application in successful compressor designs. As a result of their introduction, even small details are now considered significant in efforts to improve performance and reduce costs. Despite this, there are still possibilities to introduce new methods and procedures for improved rotor profiles, design optimisation for each specified duty and specialized compressor design, all of which can lead to a better product and new areas of application. A review of methods and procedures which lead to modern screw compressor practice is presented in this paper. This paper is intended to give a cross section through activities being done in mathematical modelling of screw compressor process through last five decades. It is expected to serve as a basis for further contributions in the area and as a challenge to the forthcoming generations of scientists and engineers to concentrate their efforts in finding future and more extended approaches and submit their contributions.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.124-129
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• 2015

An experimental study was performed estimating COP(Coefficient of Performance) of air-conditioning cycle using inverter scroll compressor with and without $Al_2O_3$ nano particle. All experiments were done for various compressor speeds from 1000~4000 rpm and used the inverter controller called CANDY to change the compressor rpm. The air-conditioning cycle components in the apparatus were used as same with components of YF hybrid car. To estimate the COP, this study measured the temperature and pressure at inlets and outlets of compressor, condenser, and evaporator. And also measured the compressor input power using Powermeter. Through the experiments, the maximum error to estimate COP was shown about ${\pm}6.09%$ at 3500rpm. The COP of refrigeration cycle with $Al_2O_3$ nano-particle was similar with that of the base cycle without nano-particle between 1000~3000 rpm of the compressor speed. But, This study showed that the COP of the cycle with $Al_2O_3$ over 3000 rpm of the compressor speed was higher than that of the base cycle due to the higher heat transfer rate increased in the evaporator from the higher oil flow rate inside the cycle as well known. Those results can be used the basic and fundamental data to design the air-conditioning cycle using inverter scroll compressor with $Al_2O_3$ nano particle.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.58-62
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• 2002

The purpose of this study is to analyze the charging gas effect on the resonance and performance characteristics of the linear compressor for small scale FPFD Stirling refrigerator. To ensure high performance of FPFD type Stirling refrigerator, the operating frequency of the refrigerator should be around the natural frequency of compressor. The gas spring effect which is induced from Pressure change in cylinder due to motion of pistons has significant effect on the natural frequency of the compressor. The numerical results show the linear compressor has high natural frequency when the charging pressure of working fluid is high and the stroke of compressor, current, input power and efficiency of compressor were shown with different operating conditions.

• The KSFM Journal of Fluid Machinery
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• v.15 no.2
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• pp.12-19
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• 2012

This study presents unsteady and unstable characteristics of three stage transonic axial compressor, developed by Korea Aerospace Research Institute. As approaching to the unstable operating region at the 103% design speed of the compressor, a modal type stall precursor appears in front of highly loaded 3rd rotor row at first, and it propagates to the upstream. On the contrary, actual stall cell initiates from the stall precursor in front of the 1st rotor row, and it propagates to the downstream of the compressor. After the stall region reached the 3rd stage and stall cell rotates circumferentially about 360 deg, it develops to one dimensional compressor surge mode. It shows a mild surge behaviour with 3~4 Hz frequency. From the test data, it can be suggested that there is a priority to give an optimum blade loading distributions to construct a multi stage transonic axial compressor stages either to secure more stable compressor operating ranges, or to maximize the compressor efficiency.