• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.857-861
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• 2016

In this study, we proposed a new method that can be measure ECG (Electrocardiography) and PPG (Photoplethysmography) in realtime on the site of the wrist for check the state of health in daily life. For convenience measurement of ECG the lead I method was used on the wrist, and omit the reference junction ECG I was measured in the right hand and the left hand of the potential difference. Then the measured electrocardiogram was amplified by the differential amplifier and the signals were passed HPF, LPF, and BPF filters. For removing the PPG's noise from the Motion artifact and temperature, we apply the reflective photoelectric volume pulse wave measurement method using green LED as a light source. The circuits was designed to be able to check the waveform using higher active amplification method at weak signals. For the validation of our device, the measured signals were compared with E2-KIT on same time. The results shows that the error does not exceed the maximum one, most of the data is confirmed to be issued Peak inspection of the same number.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.796-804
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• 1994

This paper presents Inverse SAR imaging algorithm for a unknown velocity target and a real ISAR data is processed and applied to the algorithm. The real ISAR data is obtained by transmitting a number of pulse modulated by a stepped-frequency method and the received data are undersampled. We present a method applicable for the case of a undersampled data base. In this method, the original echoed signal is mixed with a reference signal to make it unaliased, followed by being interpolated. Target`s velocity required for the algorithm is estimated via subaperture processing and after the coordinate transformation into squint-mode SAR with the estimated velocity, a recently proposed SAR/ISAR imaging algorithm derived without any approximation is utilized to produce the output image. We also propose an ISAR image scheme that is usable when a target changes its velocity during ISAR data acquisition time.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.285-288
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• 1998

A least-squares identification method is studied that estimates a finite number of coefficients in the series expansion of a transfer function, where the expansion is in terms of recently introduced generalized basis functions, We will expand and generalize the orthogonal functions as basis functions for dynamical system representations. To this end, use is made of balanced realizations as inner transfer functions. The orthogonal functions can be considered as generalizations of, for example, the pulse functions, Laguerre functions, and Kautz functions, and give rise to an alternative series expansion of rational transfer functions. We show that the Laplace transform of the expansion for some sets$\Psi_{\kappa}(Z)$ is equivalent to a series expansion . Techniques based on this result are presented for obtaining the coefficients $c_{n}$ as those of a series. One of their important properties is that, if chosen properly, they can substantially increase the speed of convergence of the series expansion. This leads to accurate approximate models with only a few coefficients to be estimated. The set of Kautz functions is discussed in detail and, using the power-series equivalence, the truncation error is obtained.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.1
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• pp.43-62
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• 2017

Mobile pulse scanning Light Detection And Ranging (LIDAR) are essential components of intelligent vehicles capable of autonomous travel. Obstacle detection functions of autonomous vehicles require very low failure rates. With the increasing number of autonomous vehicles equipped with scanning LIDARs to detect and avoid obstacles and navigate safely through the environment, the probability of mutual interference becomes an important issue. The reception of foreign laser pulses can lead to problems such as ghost targets or a reduced signal-to-noise ratio. This paper will show the probability that any two scanning LIDARs will interfere mutually by considering spatial and temporal overlaps. We have conducted four experiments to investigate the occurrence of the mutual interference between scanning LIDARs. These four experimental results introduced the effects of mutual interference and indicated that the interference has spatial and temporal locality. It is hard to ignore consecutive mutual interference on the same line or the same angle because it is possible the real object not noise or error. It may make serious faults because the obstacle detection functions of autonomous vehicle rely on heavily the scanning LIDAR.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.721-726
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• 2020

Genetic algorithm was first introduced to study adaption phenomena occurring in nature based on Darwin's theory of survival of the fittest. It has been used when analytical approach is not possible because of a large number of variables. In this paper, we demonstrated that genetic algorithm could be used to obtain physically optimized experimental values. We programmed a genetic algorithm that uses a few Gaussian functions to find a given function value and the same algorithm was connected to the laser system to obtain laser pulses of 40fs of maximum pulse width and 1mJ of maximum output power. This study shows that genetic algorithm can be applied to laser systems to obtain the optimized laser pulses.

• Journal of Community Nutrition
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• v.2 no.2
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• pp.105-109
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• 2000

To investigate the correlation between college women's energy intake and body fat percentage, this study was undertaken with 116 college women aged 19-24 years. The subjects were 20.9 years old on the average, and mean height and weight was 161.3 cm, 51.2 kg. Blood pressures were 112.4 mm Hg(systolic pressure), 70.2 mmHg(diastolic pressure). The number of pulse was 75.5 count/min. The energy intake and percent body fat were examined. The average intake of energy was 7652kcal/day(82.3% of RDA), which was lower than the recommended amount. It was similar to the level of energy intake of Korean women. BMI was 19.7 and body fat percent was 24.4%, so they appeared plump. According to BMI, 43.1% of subjects was grouped into normal, 56.9% was thin ; there was no difference between groups in age and stature. Also, normal group(27.1%) shoed significantly higher body fat percent(27.1%) than thin group(22.3%). But, body fat percent of thin group according to BMI was shown normal. Therefore, it may be thought that BMI is unsuitable indicator in this study. As a result of analyzing the correlation between body-measuring value and food intake, body fat percent against body weight and BMI was significant at the level p<0.001, but thee was no significant correlation with food intake. Therefore, it is desirable to recommend a healthful dietary lifestyle and activities for young women who want to reduce body weight due to excessive concerns regarding their outward figure.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1
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• pp.43-49
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• 2001

EVRC (Enhanced Variable Rate Codec) has been adopted as a standard coder for the CDMA digital cellular system in North America and Korea, and known to provide good call quality at 8kbps. In this paper, fast implementation algorithms for EVRC encoder are proposed. The proposed algorithms are based on both efficient pitch detection scheme and fast fixed codebook search algorithm. In the codebook search, computational complexity is reduced down to 70％ of the original EVRC by limiting the number of pulse position combination and by using a truncated impulse response. The proposed algorithms enable us to implement the EVRC with much smaller computational works. Also, informal subjective tests confirmed that the difference in the speech quality between the original EVRC and the proposed method was indistinguishable.

• Journal of Communications and Networks
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• v.14 no.1
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• pp.34-39
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• 2012

Collisions between tags greatly reduce the identification speed in radio frequency identification (RFID) systems and increase communication overhead. In particular for an active RFID system, tags are powered by small batteries, and a large number of re-transmissions caused by collisions can deteriorate and exhaust the tag energy which may result in missing tags. An efficient collision-free arbitration protocol for active RFID systems is proposed in this paper. In this protocol, a new mechanism involving collision detection, collision avoidance, and fast tag access is introduced. Specifically, the pulse burst duration and busy-tone-detection delay are introduced between the preamble and data portion of a tag-to-reader (T-R) frame. The reader identifies tag collision by detecting pulses and transmits a busy tone to avoid unnecessary transmission when collision occurs. A polling process is then designed to quickly access the collided tags. It is shown that the use of the proposed protocol results in a system throughput of 0.612, which is an obvious improvement when compared to the framed-slotted ALOHA (FSA) arbitration protocol for ISO/IEC 18000-7 standard. Furthermore, the proposed protocol greatly reduces communication overhead, which leads to energy conservation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.629-635
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• 2014

This paper describes propagation characteristics obtained by considering semiconducting screen and cross-bonding in underground transmission cables. The semiconducting screen of power cable has effect on propagation characteristics including attenuation, velocity and surge impedance. However, it is very difficult to apply the semiconduction screen for EMTP model because of the number of conductors limitation. Therefore, CIGRE WG 21-05 proposed advanced insulation structure and analysis technique of simplified approach including inner and outer semiconducting screen. In this paper, the various propagation characteristics analyse using this structure and technique for 154kV XLPE $2000mm^2$ cable. The frequency independent model of EMTP CABLE PARAMETER is used for just pattern analysis of propagation characteristics. For exact data analysis, the frequency dependent model of J-marti is used for EMTP modeling. From these result, various propagation characteristics of 154kV XLPE $2000mm^2$ cable according to semi conducting screen consideration, frequency range, cable length and pulse width are analysed. In addition, in this paper, the effects of cross-bonding are also variously discussed according to cross-bonding methods, direct connection and impedance of lead cable.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.681-684
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• 2005

This paper presents a useful multilevel PWM inverter scheme based on a (3$^{n-1}$+2) level generation technique. It consists of a PWM inverter, an assembly of LEVEL inverters, and cascaded transformers. To produce high quality output voltage waves, it synthesizes a large number of output voltage levels using cascaded transformers, which have a series-connected secondary. By a suitable selection of secondary turn-ration of the transformer, the amplitude of an output voltage is appeared at the rate of an integer to an input dc source. Operational principles and analysis are illustrated in depth. The validity of the proposed system is verified through computer-aided simulations and experimental results using prototypes generation output voltages of an 11-level and a 29-level, respectively. And their results are compared with conventional counterparts.