• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.576-583
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• 2008

In this study, we attempt to design a real-time autonomic nervous system(ANS) evaluation system usable during exercise using heart instantaneous frequency(HIF). Although heart rate variability(HRV) is considered to be a representative signal widely used ANS evaluation system, the R-peak detection process must be included to obtain an HRV signal, which involves a high sampling frequency and interpolation process. In particular, it cannot accurately evaluate the ANS using HRV signals during exercise because it is difficult to detect the R-peak of electrocardiogram(ECG) signals with exposure to many noises during exercise. Therefore, in this study, we develop the ground for a system that can analyze an ANS in real-time by using the HIF signal circumventing the problem of the HRV signal during exercise. First, we compare the HRV and HIF signals in order to prove that the HIF signal is more efficient for ANS analysis than HRV signals during exercise. Further, we performed real-time ANS analysis using HIF and confirmed that the exerciser's ANS variation experiences massive surges at points of acceleration and deceleration of the treadmill(similar to HRV).

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.157-164
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• 2001

The grinding for hard-to-machine materials, such as ceramics, super alloys etc., has proven to be a very difficult and consuming process utilizing ordinary methods. In order to conduct high efficiency machining of such materials, grinding processes using metallic bond diamond wheels and applying electrolytic in-process dressing(ELID) have been attempted on a surface grinding machine. In this study, the effects of grinding parameters, and grit sizes have been evaluated in view of surface roughness, grinding force as well as step difference in simultaneous grinding of different materials. The study and experimental results are presented in this paper.

• Current Optics and Photonics
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• v.7 no.6
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• pp.692-700
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• 2023

We present a method for improving the accuracy of the modal wavefront reconstruction in the radial shearing interferometers (RSIs). Our approach involves expanding the reduced radial terms of Zernike polynomials to high-order, which enables more precise reconstruction of the wavefront aberrations with high-spatial frequency. We expanded the reduced polynomials up to infinite order with symbolic variables of the radius, shearing amount, and transformation matrix elements. For the simulation of the modal wavefront reconstruction, we generated a target wavefront subsequently, magnified and measured wavefronts were generated. To validate the effectiveness of the high-order Zernike polynomials, we applied both low- and high-order polynomials to the wavefront reconstruction process. Consequently, the peak-to-valley (PV) and RMS errors notably decreased with values of 0.011λ and 0.001λ, respectively, as the order of the radial Zernike polynomial increased.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.5
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• pp.318-323
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• 2000

The planarization of rough polycrystalline diamond films synthesized by DC arc discharge plasma jet CVD (chemical vapor deposition) was attempted using KrF excimer laser pulses. The effects of laser incidence angle and reaction gases (ozone and oxygen) on etching rate of diamond were studied. The temperature change of diamond and graphite with different laser fluences was calculated by computer simulation to explain the etching behavior of diamond films. The threshold energy density from the experiment for etching of pure crystalline diamond was about $1.7J/cm^2$ and fairly matched the simulation value. Preferential etching of a particular crystallographic plane was observed through scanning electron microscopy. The etching rate of diamond with ozone was lower than that with oxygen. When the angle of incidence was $80^{\circ}$ to the diamond surface normal, the peak-to-valley surface roughness was Significantly reduced from $20{\mu}m$ to $0.5{\mu}m$.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.2
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• pp.75-80
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• 1994

AlAs/GaAs/AlAs RTDs(Resonant Tunneling Diodes) are fabricated and current-voltage properties of them are measured. At room temperature, peak to valley ratio is 2.4 NOT.AND.OR logic gates and Flip-Flop are fabricated using the bistable characteristics of RTDs. Although NOT.AND.OR logic gates need 5~8 transistors. only one RTD is sufficient to fabricate the logic gates. Since the switching time is very short(<10$^12$sec), it is possible to drive the semiconductor circuits fast and integrate them very large. And it is convinced the possibility of integrating RTDs to multilevel logic circuits by observing two peaks of similar current in the serial connection of two RTDs.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.53-58
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• 2008

This study was conducted to evaluate the flatness of the porous type of dicing chuck. Two measurement systems for a vacuum chuck with a porous type of ceramic plate were prepared using a digital indicator and a laser interferometer. 6 inch of silicon and glass wafer were also used. Vacuum pressure from 100mmHg to 700mmHg by 100mmHg was increased. From experiments, chucked-wafer flatness was converged to the dicing chuck flatness itself even though the repeatability of contact method using indicator was unstable. Finally, the chuck flatness was estimated below $2{\mu}m$ with peak-to valley value.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.580-589
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• 1990

This paper describes an efficient method of texture image segmentation based on conditional 1-dimensional histograms. We consider the multi-dimensional histogram, and it is projected into each axis in order to obtain conditional 1-dimensional histograms. And we extract uniform regions by iteratively applying the peak-valley detection method to conditional 1-dimensional histograms. In view of the amount of memory and computation time, the proposed method is superior to the conventional method which uses the multi-dimensional histogram. By applying the proposed method to the artificial and natural texture images some desirable results are obtained.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.89-96
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• 2006

In this study, fabrication of the large area silicon mirror is accomplished by anisotropic wet etching using micromachining technology for implementation of integrated slim optical pickup and the process condition is also established for improving the mirror surface roughness. Until now, few results have been reported about the production of highly stepped $9.74^{\circ}$ off-axis-cut silicon wafers using wet etching. In addition rough surface of the mirror is achieved in case of tong etching time. Hence a novel method called magnetorheolocal finishing is applied to enhance the surface quality of the mirror plane. Finally, areal peak to valley surface roughness of mirror plane is reduced about 100nm in large area of $mm^2$ and it is applicable to optical pickup using infrared wavelength.

• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.49-55
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• 2002

This paper proposes speaker recognition algorithm which includes both the pitch parameter and the fuzzy. This study proposes a pitch detection method for the peak and valley pitch detection function by means of comparing spectra which utilizes the transform characteristics between time and frequency. It measures the similarity to the original spectrum while arbitrarily varying the period in the time domain. It heavily weights the error due to the changing characteristics of the phonemes, while it is strong against noise. In this paper, makes reference pattern using membership function and performs vocal track recognition of common character using fuzzy pattern matching in odor to include time variation width for non-linear utterance time.

• Journal of the Korea Society of Computer and Information
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• v.5 no.3
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• pp.51-57
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• 2000

This paper proposes speaker recognition algorithm which includes both the pitch and the fuzzy. This study proposes a pitch detection method for the peak and valley pitch detection function by means of comparing spectra which utilizes the transform characteristics between time and frequency. It measures the similarity to the original spectrum while arbitrarily varying the period in the time domain. It heavily weights the error due to the changing characteristics of the phonemes, while it is strong against noise. In this paper, makes reference pattern using membership function and performs vocal track recognition of common character using fuzzy pattern matching in order to include time variation width for non-linear utterance time.