• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.171.2-171.2
• /
• 2016

The 2-dimensiona electron gas (2DEG) layers have opened tremendous interests in the heterooxide interfaces formed between two insulating materials, especially between LaAlO3 and $SrTiO_3$. The 2DEG layers exhibit extremely high mobility and carrier concentrations along with metallic transport phenomena unlike the constituent oxide materials, i.e., $LaAlO_3$ and $SrTiO_3$. The current work inserted artificially the interfacial layer, $Sr_xCa_{1-x}TiO_3$ between $LaAlO_3$ and $SrTiO_3$, with the aim to controlling the 2-dimensional transports. The insertion of the additional materials affect significantly their corresponding electrical transports. Such features have been probed using DC and AC-based characterizations. In particular, impedance spectroscopy was employed as an AC-based characterization tool. Frequency-dependent impedance spectroscopy have been widely applied to a number of electroceramic materials, such as varistors, MLCCs, solid electrolytes, etc. Impedance spectroscopy provides powerful information on the materials system: i) the simultaneous measurement of conductivity and dielectric constants, ii) systematic identification of electrical origins among bulk-, grain boundary-, and electrode-based responses, and iii) the numerical estimation on the uniformity of the electrical origins. Impedance spectroscopy was applied to the $LaAlO_3/Sr_xCa_{1-x}TiO_3/SrTiO_3$ system, in order to understand the 2-dimensional transports in terms of the interfacial design concepts. The 2-dimensional conduction behavior system is analyzed with special emphasis on the underlying mechanisms. Such approach is discussed towards rational optimization of the 2-dimensional nanoelectronic devices.

• Journal of Korean Academy of Nursing
• /
• v.38 no.2
• /
• pp.321-331
• /
• 2008

Purpose: To examine the relationship between body fat percentage (BFP) and N-K cell activity (NKCA) in Korean breast and rectal cancer patients just after diagnosis. Methods: With 35 subjects enrolled between November 2002 and May 2003, Bioelectrical Impedance Analysis was used to estimate BFP. FACS Analysis was used to measure N-K cell activity. The relationships between BFP and NKCA were identified by using curve estimation, simple regression, and multiple regression, Results: The mean BFPs of the subjects and all the sub-groups were higher than acceptable BFPs. Both the mean NKCAs of male and female subjects were lower than that of healthy women. NKCA was explained by BFP with a 14.9% variance in the total subjects (p<.05). There were significant negative relationships between BFP and NKCA after controlling age, type of cancer, and stage of cancer while no significant relationship was found after controlling for gender. The relationships between BFP and NKCA in the sub-groups of female, breast cancer, and stage I, and II were significant. The relationships between male, rectal cancer, and the stage III, and VI sub-groups were not identified, but they revealed a mild to moderate steep in curve estimation. Conclusion: Weight reduction could prevent the risk and advancement of breast and rectal cancer in Koreans.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.7
• /
• pp.987-993
• /
• 2013

Integrity of the control and instrumental cables in nuclear power plant is important to maintain the stability of the nuclear power plants. In order to diagnose the integrity of the cables, the diagnostic methods based on reflectometry have been studied. The reflectometry is a non-destructive method and it is applicable to diagnose the live cables. We introduce a Gaussian enveloped linear chirp reflectometry to diagnose the cables in the nuclear power plants. In this paper, we estimate the instantaneous frequency of the Gaussian enveloped linear chirp signal by using the weighted robust least squares filtering to localize the impedance discontinuities in the class 1E instrumental cable.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.7
• /
• pp.820-826
• /
• 2016

The acoustic performance estimation formulas for silencers are developed mainly by theoretical or empirical methods. However, the existing formulas are available only for a limited range of silencers. In this paper, the procedures for noise analysis of the silencers are established by comparing analytic results to experimental results. With the proven analysis procedures, impedances of the rectangular silencers for ships are adversely predicted from National Environmental Balancing Bureau (NEBB) data, and with the estimated impedances, insertion loss formulas for large silencers are developed using boundary element method (BEM). The developed formulas can be efficiently used for predicting acoustic performance of the silencers for ships.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.32B no.7
• /
• pp.1010-1024
• /
• 1995

An intelligent trajectory control method that controls a direction and a average velocity for a prosthetic arm by force and direction estimations using EMG signals is proposed. 3 stage linear filters are used as a real time joint trajectory planner to minimize the impact to human body induced by arm motions and to reduce muscle fatigues. We use combination of MLP and fuzzy filter for a limb direction estimation and a time model of force for determining a cartesian trajectory control parameter. EMG signals are acquired by using a amputation simulator and 2 dimensional joystick motion. Simulation results of the proposed method show that the arm is effectively followed the desired trajectory by estimated foreces and directions. This method reduces the number of electrodes and attatched sites compared with the method using Hogan's impedance control.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.3
• /
• pp.727-730
• /
• 2023

The operation of electric automatic windows is used in harsh environments, and the energy density decreases as charging and discharging are repeated, and as soundness deteriorates due to damage to the internal separator, the vehicle's mileage decreases and the charging speed slows down, so about 5 to 10 Batteries that have been used for about a year are classified as waste batteries, and for this reason, as the risk of battery fire and explosion increases, it is essential to diagnose batteries and estimate SOH. Estimation of current battery SOH is a very important content, and it evaluates the state of the battery by measuring the time, temperature, and voltage required while repeatedly charging and discharging the battery. There are disadvantages. In this paper, measurement of discharge capacity (C-rate) using a waste battery of a Tesla car in order to predict SOH estimation of a lithium-ion battery. A Support Vector Machine (SVM), one of the machine models, was applied using the data measured from the waste battery.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.12
• /
• pp.1823-1832
• /
• 2004

In this paper, we proposed a TDC based F/T sensorless active compliance control algorithm for a rehabilitation robot (KARES II). The preference of compliance of the disabled is presented by clinical testing at Korea National Rehabilitation Center with the disabled. The KARES II was designed to work 12 predefined tasks which are very essential for helping the disabled. Among the tasks, some contact tasks between the robot and the disabled exist. Therefore, TDC based F/T sensorless compliance control algorithm is developed for these tasks without additional cost. We verified the proposed algorithm with experiment. Also for the practical use, suitable compliance for contact tasks is chosen by clinical testing at Korea National Rehabilitation Center.

• ETRI Journal
• /
• v.40 no.3
• /
• pp.303-308
• /
• 2018

This paper proposes a simple yet accurate method for estimating the antenna correlation coefficient (ACC) of a high-order multiple-input multiple-output (MIMO) antenna. The conventional method employed to obtain the ACC from three-dimensional radiation patterns is costly and difficult to measure. An alternate method is to use the S-parameters, which can be easily measured using a network analyzer. However, this method assumes that the antennas are highly efficient, and it is therefore not suitable for lossy MIMO antenna arrays. To overcome this limitation, we define and utilize the non-coupled radiation efficiency in the S-parameter-based ACC formula. The accuracy of the proposed method is verified by the simulation results of a 4-port highly coupled lossy MIMO array. Further, the proposed method can be applied to N-port arrays by expanding the calculation matrix.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.54 no.4
• /
• pp.163-170
• /
• 2005

This paper deals with an improved fault location algorithm with compensation ground capacitance through distributed parameter for a long parallel T/L. For the purpose of fault locating algorithm non-influenced by source impedance and fault resistance, the loop method was used in the system modeling analysis. This algorithm uses a positive and negative sequence of the fault current for high accuracy of fault locating calculation. Power system model of 160km and 300km long parallel T/L was simulated using EMTP software. To evaluate of the proposed algorithm, we used the several different cases 64 sampled data per cycle. The test results show that the proposed algorithm was minimized the error factor and speed of fault location estimation.