• Journal of the Korean Institute of Navigation
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• v.5 no.2
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• pp.41-47
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• 1981

Many new radar techniques have appeared on the electronic scene in recent years, such as a variety of automatic computer processing. However, even with the advent of these sophisticated radar techniques, an old problem continues to plague all radars: the problem of transmission line losses. With the higher performance required today, the Waveguide testing and trouble-shooting techniques remain essentially unchanged in principle. This paper dealt with the rf pulse "Time-domain Reflectometry" to inspect radar wave-guide system and compared with the conventional methods. During the investigation, it was verified that the pulsed TDR for wave-guide is superior to the conventional methods; 1. Disassembling is not needed to locate the discontinity points and measure the reflections of trobled points. 2. The results of the data are more precise. 3. The condition of individual component is able to the photographed and recorded permanently. 4. Since rf pulse TDR is based on the well-known basic radar principle, such a test set requires the minimum of training to operate. With the level of transmission line problems, the prospect of increasing complexity of equipment, and no relief in sight, the benifits must be emphasizied to adopt such a testing procedure.procedure.

• Earthquakes and Structures
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• v.4 no.6
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• pp.649-670
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• 2013

It is known that a base-isolated building exhibits a large response to a long-duration, long-period wave and an inter-connected system without base-isolation shows a large response to a pulse-type wave. To compensate for each deficiency, a new hybrid passive control system is investigated in which a base-isolated building is connected to another building (free wall) with oil dampers. It is demonstrated that the present hybrid passive control system is effective both for pulse-type ground motions and long-duration and long-period ground motions and has high redundancy and robustness for a broad range of disturbances.

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.138-142
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• 2016

A pulse measurement by tonometry provides useful information for diagnosis, including not only blood pressure and heart rate but also parameters for estimating a condition of the cardiovascular system. Currently, various pulse measurement devices based on the tonometry have been developed. A reliability of these devices is determined by a positioning technic between the sensor and the blood vessel and a controlling technique of the pressurization level. An angle of the sensor for the pulse measurement seems to be highly related with a measured signal, however, the objective studies for this issue have been not published. In this paper, the variation of the pulse signals by tonometry direction was experimentally assessed according to the angle of the sensor. In order for guaranteeing the repeatability of the experiment, we used a pulse generator device, which can generate human pulse signal by using silicon tube and fluid pump, and developed a structure for precise adjustment of the angle and the pressurization level of the sensor. The angle of the sensor was acquired by an inclinometer, which was attached at the opposite side of the sensor. As results, a coefficient of variation (CV) of a maximum amplitude (MA) of the pulse wave was largely increased over the angle range of $-9{\sim}9^{\circ}$. Furthermore, the changes of the pulse shape showed different aspects according to the sign of the angle tilted along the blood vessel. It is expected that the results of this study can be helpful for developing more precise pulse measurement devices based on the tonometry and applying in clinic.

• Journal of the Korean Society of Visualization
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• v.16 no.3
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• pp.8-15
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• 2018

Recently, as the high speed railway becomes more common, new environmental problems such as noise around tunnels are appearing. When a high speed train enters a tunnel, a compression wave in the tunnel is generated and propagated toward the tunnel exit at a sonic speed. When it reaches the tunnel exit, a part of compression wave radiates as a pulse typed impulse wave to the outside of tunnel. The impulse wave has an explosive noise. When the impulse wave is propagated around a village, it induces a serious noise or other problems to the resident. In order to solve these engineering problems, it is important to investigate the radiation characteristics of the impulse wave radiated from the tunnel exit. In this study, the effect of the length and angle of the baffle plate at the tunnel exit on the impulse wave radiated from the tunnel exit was investigated by numerical analysis. As a results, the baffle plate greatly affected the propagation of impulse wave.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.962-967
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• 2014

In this paper, through a digital potentiometer and exponentially weighted moving average filter, pulse and PPG waveform measurable device was fabricated in radial artery. If this device is not proper about signal size in analog part, MCU can judge easily by adjusted amplification through digital potentiometer, using exponentially weighted moving average filter is able to filter out more clear value of ADC. I presumed pulse rate as value of measuring time between point of maximum contraction from sensing signal in radial artery of wrist. Therefore, this means can measure stable pulse rate and PPG waveform, finger as well as radial artery, whether signal size of each person is different finger as well as radial artery.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.255-265
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• 1995

Stainless steel type 304L has been nitrided in the low pressure (600Pa) and high nitrogen (80% $N_2$+20% $H_2$) environment for 5 hours by the square-wave-pulsed-d.c. plasma as a function of temperature $400{\sim}550^{\circ}C$ and pulsation. At the lower temperature range of $400{\sim}500^{\circ}C$ and at the relatively high ratio of pulse duration to pulse period. "S-phase" has been developed in the form of thin nitrided surface layer which has many cracks, leading to be nearly impossible for the industrial anti-wear and anti-corrosion applications. At the higher temperature up to $550^{\circ}C$ with the increasing ratio of the pulse duration to pulse period up to $50{\mu}s/100{\mu}s$, the nitrided layer, whose growth rate has increased also, has been composed mainly of CrN and $Fe_4N$ phases and has become thick, uniform and nearly crack-free.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.373-375
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• 2005

The purpose of this paper is to develop the Plastic Cortex Stimulator(PCS) for stroke patients using ZigBee technology. The PCS consists of an implantable neuro-stimulator and a user controller, The neuro-stimulator has the stimulus circuit which is the H-bridge circuit to generate a bipolar pulse. The bipolar pulse is known to be effective for stroke recovery. The user controller sends several wave-shape parameters (amplitude, pulse width, cycle, etc.) to the neuro-stimulator for variable stimulation using ZigBee technology. The CC2420 and atmega128L was used to implement ZigBee protocol stack. The wireless control of PCS based on ZigBee can help the tele-rehabilitation of the stroke patients. The most effective pulse shape parameters are being investigated through animal experiments. The bio-compatibility and user-friendly interface are supposed to be handled in further study.

• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.4
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• pp.7-16
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• 1971

A negative resistance element in the form of current control can be obtained by using a pair transistor circuit. This negative resistance element can be used in the generation of square pulse, and also in the realization of pulse width modulation circuit by superposing signal current on its bias current. The each bias current of pair circuit increases alternatively according to the polarity of the input signal. In order to satisfy this condition, a modified full wave rectification circuit has been adopted for supplying the input signal. Theoritical analysis of pulse times and design guidances for practical modulation circuit parameters are presented.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.2
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• pp.10-20
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• 1997

This paper describes the design, the manufacture and the development of th eautomatic gain control unit which ajdusts the gain of IF processor in the high sensitive & multifunctional receiver unit (HMR) for pulse doppler radar system. Accodording to the effective distnce of target, radar cross section, and a lot of external environments (such as clutter), the receiving stage of RADAR system often deviates from dynamic range. To solve this kind o fproblem, continuous/pulse wave AGC are realized, make it possible to control the gain characteristics of receiver stably, and can increase dynamic range linearly by adjusting the gain slope of receiver which is limited by 1-dB gain compression point. In this study, AGC unit is designed to regulate the total gain of receiver by using te analog feedback theory. It also has rapid enough response to process pulse signal. This study presents the gain control method of IF, the real manufacture technique (the package-type components) and the measurement performance of AGC.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.153-157
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• 2003

Supersonic and hypersonic aircrafts must pass wide range of speed to reach high speed region. But for existing engines the most efficient operating speed ranges are decided according to their flying speed, so an engine which mixes several engines like TRJ (Turbo Ramjet) and ARJ (Air Turbo Ramjet) has been planed. This mixed type engine has inefficiency that more than two engines must be installed simultaneously, but the pulse detonation engine (PDE) that uses detonation wave has a strong point that it can operate in all speed range with single engine. This paper deals with the simulation of the pulse detonation engine which uses hydrogen peroxide $(H_2O_2)$ mono propellant. Hydrogen peroxide is low-cost propellant, and it is reacted without oxidizer. Comparison between $H_2-O_2$ mixture with $H_2O_2$ mono propellant about thrust, pressure, temperature and velocity shows that $H_2O_2$ is a very useful propellant.