• ETRI Journal
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• 제40권1호
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• pp.51-60
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• 2018

In Long Term Evolution (LTE) cellular networks, the transmit power control (TPC) mechanism consists of two parts: the open loop (OL) and closed loop. Most cellular networks consider OL/TPC because of its simple implementation and low operation cost. The analysis of OL/TPC parameters is essential for efficient resource management from the cellular operator's viewpoint. In this work, the impact of the OL/TPC parameters is investigated for homogeneous small cells and heterogeneous small-cell/macrocell network environments. A mathematical model is derived to compute the transmit power at the user equipment, the received power at the eNodeB, the interference in the network, and the received signal-to-interference ratio. Using the analytical platform, the effects of the OL/TPC parameters on the system performance in LTE networks are investigated. Numerical results show that, in order to achieve the best performance, it is appropriate to choose ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in a homogenous small-cell network. Further, the selections of ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in the small cells and ${\alpha}_{macro}=0.8$ and $P_{o-macro}=-100dBm$ in the macrocells seem to be suitable for heterogeneous network deployment.

• Journal of Power Electronics
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• 제17권3호
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• pp.835-847
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• 2017

A transmitting coil with an optimal topology and number of turns can effectively improve the performance of the wireless power transfer (WPT) systems for endoscope robots. This study proposes the evaluation parameters of the transmitting coils related to the performance of the WPT system to standardize the design of the transmitting coils. It considers both the quality factor of transmitting coils and the coupling factor between the two sides. Furthermore, an analytical model of transmitting coils with different topologies is built to exactly estimate the evaluation parameters. Several coils with the specified topologies are wound to verify the analytical model and the feasibility of evaluation parameters. In the case of a constant power received, the related evaluation parameters are proportional to the transfer efficiency of the WPT system. Therefore, the applicable frequency ranges of transmitting coils with different topologies are determined theoretically. Then a transmitting coil with a diameter of 69 cm is re-optimized both theoretically and experimentally. The transfer efficiency of the WPT system is increased from 3.58% to 7.37% with the maximum magnetic field intensity permitted by human tissue. Finally, the standardized design of the transmitting coil is achieved by summing-up and facilitating the optimization of the coils in various situations.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.165-168
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• 1999

Thermodynamic cycle analysis has been performed for the power generation systems to utilize the cold energy of liquefied natural gas (LNG). Among many possible configurations of the cycle, the open Rankine cycle, the closed Rankine cycle, and the closed Brayton cycle are selecte for the analysis because of their practical importance. The power output per unit mass of LNG has been analytically calculated for various design parameters. The optimal conditions for the parameters to maximize the power output are presented and some of the design considerations are discussed.

• 한국국방경영분석학회지
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• 제13권1호
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• pp.45-64
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• 1987

Power algorithms for analysis of variance tests are presented. In experimental design of operational tests and evaluations the selection of design parameters so as to attain an experiment with desired power is a difficult and important problem. An interactive computer program is presented which uses the power algorithms for ANOVA tests and creates graphical presentations which can be used to assist decision makers in statistical design. ANOVA tests and associated parameters (such as sample size, types and levels of treatments, and alpha-level)are examined.

• 동력기계공학회지
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• 제21권3호
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• pp.66-73
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• 2017

In order to identify the design parameters of a hydraulic engine mount with a nonlinear characteristics, an experimental method has been used generally. The method takes a considerable time and expense because of preparing an experimental apparatus, conducting a test, and analyzing results. Therefore, this paper presents a simple method to identify the design parameters of a cylindrical hydraulic engine mount, and optimize the design parameters. The physical model and mathematical equations of the mount were derived, and values of the design parameters of the mount were identified by optimization method with minimizing difference between the analytical results with the equations and the experimental results. This method is more simpler than the conventional experiment method and identify successfully the design parameters. In addition, the technique can optimize the design parameters of the mount to improves the isolation performance of the mount.

• 동력기계공학회지
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• 제2권3호
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• pp.55-59
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• 1998

This paper probes into the influence of tire uniformity on tire's modal parameters with the method of experimental modal analysis. Two radial tires of the same kind with different uniformity level are taken to be tested at different exciting points and real modal parameters are abstracted. The differences of their modal parameters are presented. Then tire transfer functions are constructed with experimental modal parameters and ideal modal parameters respectively. It is found that the measured transfer functions of tire of good uniformity are closer to ideal transfer function than that of tire of bad uniformity. The study shows evident interrelation of experimental modal parameters and tire uniformity, and further study should be of great value.

• 조명전기설비학회논문지
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• 제25권4호
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• pp.71-78
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• 2011

This paper contains the selection of operation parameters for protection and control of steam turbine in a Korea Standard Type Nuclear Power Plant. The safety of nuclear reactor must be ensured which generates nuclear energy and produces steam. Also, the safety of turbine, which consume the nuclear energy as a core machine, must be ensured. For the purpose of this, we describe how the operating parameters were selected, reviewed, implemented into the operator console and finally put into actual operation of the system.

• 한국유체기계학회 논문집
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• 제8권5호
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• pp.13-21
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• 2005

This study aims to analyze operating performance of a micro gas turbine with the aid of detailed measurements of various system parameters. In addition to embedded measurements, parameters such as exhaust temperatures, engine inlet temperatures and fuel flow rates are measured. Variations in measured data and estimated performance parameters are analyzed. Those data are processed to calculate losses along the power transmission line and the net gas turbine performance (power and efficiency based on the gas turbine shaft end) is isolated from the overall system performance. A method to estimate characteristic parameters such as component efficiencies, based on the comparison between measured and predicted performance data, is suggested and exemplified for the full load condition.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.132-139
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• 2004

This study aims to analyze operating performance of a micro gas turbine with the aid of detailed measurements of various system parameters. In addition to embedded measurements, parameters such as exhaust temperatures, engine inlet temperatures and fuel flow rates are measured Variations in measured data and estimated performance parameters are analyzed. Those data are processed to calculate losses along the power transmission line and the net gas turbine performance (power and efficiency based on the gas turbine shaft end) is isolated from the overall system performance. On the basis of the measured data, analytical approach is tried to estimate design characteristic and performance parameters such as component efficiencies and unmeasured temperatures.

• 동력기계공학회지
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• 제3권1호
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• pp.67-73
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• 1999

It is not easy to control the speed of AC motors accurately without modeling with some parameters for the controlled system. However, there are some application parts which do not require high speed responses strictly and the motor parameters can not to be identified simply. In this paper, a speed control method for a synchronous motor(S.M) with unknown parameters of the motor is investigated. The method is based on the current control algorithm. Speed controller and current controller are designed using PI control law. Some experiments are performed using DSP and power expert system to prove the validity of the proposed method. Throughout experimental results, the method is confirmed successfully. This method is expected to control the system with unknown parameters of the S.M efficiently.