• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.1525-1527
• /
• 2004

Modeling of the battery for 42V Power-Net system is presented. For the Battery Management System(BMS) algorithm in a Mildhybrid vehicle, accuracy in SOC estimation is crucial. The battery model is needed for the BMS algorithm as well as system computer symulation for the energy management. The battery model was composed of impedance elements and the each element of the model is estimated by the analysis of the terminal voltage. The result of the model is confirmed by experimental data.

• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.526-527
• /
• 2015

본 논문은 계통에 전력을 변동하여 계통 임피던스를 추정하는 기법의 문제점을 분석하고 개선된 역상분 전류 주입을 이용한 임피던스 추정 기법을 제안한다. 기존의 계통 임피던스 추정 기법에서는 유, 무효 전력의 크기를 변화시키고, 그에 따른 두동작점에서 측정된 전압의 변동량을 통해 계통 임피던스를 계산한다. 하지만 일반적인 계통 연계형 인버터에는 전원 전압의 위상을 추종하는 PLL이 동작하고 있으며, 이 PLL은 정상 상태에서 얻을 수 있는 전류 주입에 따라 발생하는 d-q축 전압의 변동량을 왜곡시켜 추정 오차를 유발한다. 따라서 본 논문에서는 불평형 전원을 독립적으로 제어하는 듀얼 제어기와 정상분 PLL 기법을 사용하여 역상분 전류에 의한 역상분전압의 변동량만으로 PLL에 의한 PCC 전압의 정상 상태 측정 오차를 제거하여 계통 임피던스를 정확히 추정하는 기법을 제안한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.10a
• /
• pp.379-384
• /
• 1997

This paper proposes a method for estimating the vibrational power supplied by a machine that generates excitation force to its supporting structure via the coupling points. The basis of the method is that the vibrational power can be calculated using the mechanical impedance and the velocity at the coupling points on the supporting structure. First, a method is described to estimate the mobilities at the coupling points when the machine is not separable from the supporting structure, then the vibrational power is calculated using the estimated mobilities and measured velocities at the coupling points. The mobilities are estimated from the result of impulsive testing of the coupled structure. The method is investigated using an experimental model. The estimated and measured values of the mobilities and the vibrational power are compared. It is shown that the estimated values agree well with the measured values.

• Proceedings of the KIPE Conference
• /
• 2019.07a
• /
• pp.358-359
• /
• 2019

철교나 석유비축기지 탱크저판 및 각종 매설관로 등 대부분 철 성분 골조는 시간이 경과하면 주변의 환경에 따라 부식이 급격히 일어난다. 이러한 철강재가 부식되는 철강재가 시설물의 주요 구성물이 되고 있는 시설물의 수명을 크게 단축시키는 주요원인이 되고 있다. 이에 대한 대비책으로 방청도료나 코팅을 이용하는 방법과 달리, 전기적으로 전위차를 같게 하여 부식을 방지하는 전기방식법을 적용함에 있어 방식전류가 불균일한 경우 양극 소모가 불균일함에 따라 교체시기 문제를 극복하기 위해 회로 등가 임피던스 추정 및 RF 릴레이 장착한 TB를 이용한 방식전류제어장치를 개발하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.8
• /
• pp.67-73
• /
• 2009

The magnetic saliency effect in surface-mounted permanent-magnet (SMPM) motors on the torque control at high speeds is first presented and analyzed in this paper. The d- and q- axes impedance are measured by proposed State-Filter. Measurement of the d- and q- axes impedance difference is performed to prove the existence of the magnetic saliency. Then, the saliency effects on the torque control performance in the flux weakening region are discussed. Based on the developed motor modeling with the reluctance torque, the proposed control adjusts the d- and q-axis current toward the operating point to track the commanded torque. The feasibility of the presented idea is verified by experimental results on a commercial 600[W] SMPM motor.

• Journal of Astronomy and Space Sciences
• /
• v.39 no.3
• /
• pp.117-126
• /
• 2022

The Ionospheric Anomaly Monitoring by Magnetometer And Plasma-probe (IAMMAP) is one of the scientific instruments for the Compact Advanced Satellite 500-3 (CAS 500-3) which is planned to be launched by Korean Space Launch Vehicle in 2024. The main scientific objective of IAMMAP is to understand the complicated correlation between the equatorial electro-jet (EEJ) and the equatorial ionization anomaly (EIA) which play important roles in the dynamics of the ionospheric plasma in the dayside equator region. IAMMAP consists of an impedance probe (IP) for precise plasma measurement and magnetometers for EEJ current estimation. The designated sun-synchronous orbit along the quasi-meridional plane makes the instrument suitable for studying the EIA and EEJ. The newly-devised IP is expected to obtain the electron density of the ionosphere with unprecedented precision by measuring the upper-hybrid frequency (f_UHR) of the ionospheric plasma, which is not affected by the satellite geometry, the spacecraft potential, or contamination unlike conventional Langmuir probes. A set of temperature-tolerant precision fluxgate magnetometers, called Adaptive In-phase MAGnetometer, is employed also for studying the complicated current system in the ionosphere and magnetosphere, which is particularly related with the EEJ caused by the potential difference along the zonal direction.

• Nutrition Research and Practice
• /
• v.5 no.3
• /
• pp.246-252
• /
• 2011

Bioelectrical impedance analysis (BIA) models must be validated against a reference method in a representative population sample before they can be accepted as accurate and applicable. The purpose of this study was to compare the eight-electrode BIA method with DEXA as a reference method in the assessment of body composition in Korean adults and to investigate the predictive accuracy and applicability of the eight-electrode BIA model. A total of 174 apparently healthy adults participated. The study was designed as a cross-sectional study. FM, %fat, and FFM were estimated by an eight-electrode BIA model and were measured by DEXA. Correlations between BIA_%fat and DEXA_%fat were 0.956 for men and 0.960 for women with a total error of 2.1%fat in men and 2.3%fat in women. The mean difference between BIA_%fat and DEXA_%fat was small but significant (P < 0.05), which resulted in an overestimation of $1.2{\pm}2.2$%fat (95% CI: -3.2-6.2%fat) in men and an underestimation of $-2.0{\pm}2.4$%fat (95% CI: -2.3-7.1%fat) in women. In the Bland-Altman analysis, the %fat of 86.3% of men was accurately estimated and the %fat of 66.0% of women was accurately estimated to within 3.5%fat. The BIA had good agreement for prediction of %fat in Korean adults. However, the eight-electrode BIA had small, but systemic, errors of %fat in the predictive accuracy for individual estimation. The total errors led to an overestimation of %fat in lean men and an underestimation of %fat in obese women.

• Journal of Biomedical Engineering Research
• /
• v.25 no.1
• /
• pp.21-26
• /
• 2004

Recently, many people want to know their state of health, such as a body fat rate, anywhere and anytime. The Personal Digital Assistance(PDA) is the portable wireless apparatus that has become widely popular. There are many application areas of the IDA to be in mobile care devices. In this study, we developed the PDA based body fat measurement system, composed of a cradle type measurement module and a WindowCE operated software module, a regression equation for predicting lean body mass (LBM). Sixty-three weight-stable subjects (53 men, 10 women) aged 20∼32yr participated in this study. A regression model, LBM ＝ (0.0005＊Height2 - 0.0160＊Impedance ＋ 0.3920＊Weight - 0.0684＊Age - 5.8141＊Sex ＋ 25.984, was found. The correlation coefficient( r) of body fat rate between developed system and HTM1000plus(BionetTM) was 0.928. HTM1000plus is a commercially available and approved by KFDA. These results indicated that developed system is reliable for estimation of body fat rate. Although developed system is the PDA based miniaturized, it shows good performance comparing with other commercial product.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.1
• /
• pp.217-222
• /
• 2018

The deterioration of the Battery is decided by SoC and SoH. To determine Battery deterioration, SoC measurement method of Battery by Transfer Function was studied. The SoC of the Battery changes most greatly in the 1Hz band where the DC resistance is detected. but it is a narrow band to observe, therefore, the observation band was moved to 1kHz using the tone busrst signal. Welch's method was used to observe the frequency domain characteristics of the signal. As a result of the spectral estimation, it was confirmed that the response signal of the battery is 1dB difference when the SoC is 40%, 60%, and 80%, respectively. Through this, Proposed the new method of Battery SoC measurement.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.9
• /
• pp.740-753
• /
• 2008

The conventional Split Hopkinson Pressure Bar (C-SHPB) technique with aluminum pressure bars to achieve a closer impedance match between the pressure bars and the specimen materials such as hot temperature degraded POM (Poly Oxy Methylene) and PP (Poly Propylene) to obtain more distinguishable experimental signals is used to obtain a dynamic behavior of material deformation under a high strain rate loading condition. An experimental modification with Pulse shaper is introduced to reduce the nonequilibrium on the dynamic material response during a short test period to increase the rise time of the incident pulse for two polymeric materials. For the dynamic stress strain curve obtained from SHPB experiment under high strain rate, the Johnson-Cook model is applied as a constitutive equation, and we verify the applicability of this constitutive equation to the probabilistic reliability estimation method. The methodology to estimate the reliability using the probabilistic method such as the FORM and the SORM has been proposed, after compose the limit state function using Johnson-Cook model. It is found that the failure probability estimated by using the SORM is more reliable than those of the FORM, and the failure probability increases with the increase of applied stress. Moreover, it is noted that the parameters of Johnson-Cook model such as A and n, and applied stress affect the failure probability more than the other random variables according to the sensitivity analysis.