• Management & Information Systems Review
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• v.2
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• pp.95-106
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• 1998

Color Echo-sounder display signals reflected from underwater objects in eight colors according to the strength of the signal. When the sea bottom is hard due to the presence of rocks, etc, the trailing on the reflection become strong signal and soft to presence of mud, etc the trailing on the reflection become weak signal. Strong signals are displayed in the color range, reddish brown, orange and yellow, in descending order of intensity. Weak signals are displayed in the range blue, light blue, cyan and green, in ascending order of intensity. Image of fish schools at or near the sea bottom vary according to the characteristics of the beam angle setting. When the angle is wide, even fish not near the bottom may be recorded as being on the seabed. A narrow angle should, therefore, be selected when you want to get an accurate recording of fish at or near the sea bottom. The condition of the sea bottom can be determinded more easily when the beam angle is wide and pulse with is long. Though the objects could be verified by the type of reflected signals which have been transformed into digital signals strong middle and weak ones, the experiments have in continue under various condition. Futhermore, the methode of measuring temperature inside the sea ought to be examined.

• Journal of the Korean Home Economics Association
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• v.36 no.6
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• pp.85-94
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• 1998

In this study we tested the physiological influence on human-body according to clothing pressure with reduction rate and varied posture using three kinds of belt with different width. The width of belts were 2.5cm, 3.5cm and 4.5cm, and reduction rates of belts were 0%, 2.5% and 5% of the subject/s waist size respectively. the measured postures were standing state and sitting stste in the chair. The reasults are as follows; 1. Clothing pressure was high in the order of Side part>Front part>Back part and the rate fo change in the side part was highest, according to the reductio rate of belts. The more the width of belt was wide, the less the clothing pressure was small, and this kind of phenomenon could be explained by "The Principle of the power". 2. Both the rate of reduction of belt and the change of average skin temperature in accordance with the width of belt is small, however, the more the width of belts is wider and the reduction rate is bigger, the more the skin temperature at the waist part is increased. 3. The blood pressure and pulse was influenced when the width of belt was narrow and the reduction rate was high. 4. A sense restraining was much influenced by the width of belt, especially when the width of belts was wide, the significant difference was permitted.permitted.

• Journal of Chest Surgery
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• v.10 no.1
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• pp.173-178
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• 1977

A 51 year old man was admitted to the Thoracic and Cardiovascular Department of Kyungpook University Hospital on April 7, 1976, with chief complaints of orthopnea and the chest pain for about 3 months. Physical examination showed narrow pulse pressure, puffy face, engorged neck veins at sitting position, distant heart sound, enlarged liver and edematous upper extremities. The chest roentgenogram demonstrated markedly enlarged cardiac silhouette. Low voltage and the low to diphagic T`s were noted on the electrocardiogram. Paroxysmal ventricular tachycardia was developed intermittently and was subsided spontaneously. Repeated pericardiocentesis were performed each of which yielded from 100 to 300ml. but intractable cardiac failure was progressed. The bacteriology and cytology of the pericardial fluid were not revealed any specific findings. The pericardiectomy was performed to release the intractable cardiac tamponade. Pericardium was found to be thickened and cardiac constriction was noted. The thickened pericardium was easily removed. A large hen`s egg sized dark blue tumor mass occupied the anterior wall of the right atrium and two thumb tip sized pearl gray tumors were placed at the just below portion of the main pulmonary artery. The biopsy report revealed primary fibrosarcoma of the heart. The patient was improved from the symptoms of the cardiac failure during the postoperative course.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.18-22
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• 2010

In this paper, we propose and analyze the two way ranging (TWR) positioning technique using ultra wideband (UWB) for indoor environment. We employed IEEE 802.15.3a channel as a simulation environment and used to time of arrival (TOA) algorithm. UWB technology in a low transmission power the less the effect of interfering with the existing system, the frequency can be shared so that it can improve the spectral efficiency. And, positioning technique based on UWB with a very narrow pulse width has high accuracy in indoor environment. From the simulation results, it is analyzed the probability of error and positioning performance for channel effects and confirmed usefulness of the proposed scheme.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.7
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• pp.359-364
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• 2000

This paper is introducing a newly developed spark-gap switch with dual trigger system, into which the current from the voltage source is injected along with the test sequence during the synthetic testing of high voltage circuit-breaker. The currently-used spark gap switch is narrow in operating range due to the use of the method of triggering energy being injected by single way. As a result, the frequent happening of misoperation has greatly reduced the test quality and test efficiency and has required the cost of maintenance excessively. In this study, accordingly, in order to basically remove these problems, another triggering system is installed to the opposite direction on the existing triggering system; attaching the same time and the same rising time of pulse wave as on the existing system, so that at a comparatively trigger gap distance from the main electrode(the gap can be operated at 60% of self-break voltage, while at 80% in the current system), the main electrode has been enabled to be closed by the development of spark gap switch with dual trigger system.

• Rapid Communication in Photoscience
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• v.4 no.1
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• pp.25-28
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• 2015

The time-resolved photoexcitation dynamics of electrical conductivity of the magnetic organic superconductor ${\lambda}-(BETS)_2Fe_{0.45}Ga_{0.55}Cl_4$ has been studied with a nanosecond visible laser pulse at its three different phases, i. e., metallic phase, superconducting phase and insulating phase. A transient increase of the resistance is induced by photoirradiation at all the temperatures measured for all three phases, but the decay profile shows a significant temperature dependence. The relaxation rate in the metallic and insulating phase are different from each other, and the decay time is relatively faster and almost constant in the metallic phase. However, a prolongation of the relaxation time is observed at temperature just around the narrow superconducting phase. Nonbolometric (nonthermal) origin of the observed photoresponse of the electrical conductivity is confirmed in the superconducting phase.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.572-580
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• 2015

RF skin tracking of instrumentation RADAR cannot acquire stable track data, because of effect of multipath interference especially elevation direction. In this paper, low altitude target tracking method using laser tracking system is suggested to overcome this restriction. The effect of multipath can be reduced by increasing angle resolution with laser characteristics of very short pulse and narrow beamwidth. RF skin track, beacon track and laser track data for the integrated calibration target on the ground and target ship on the sea are gathered. And they are compared and analyzed to confirm the performance of laser tracking system. As a result, it shows that the suggested laser track method has better performance than RF skin track under multipath conditions.

• Design & Manufacturing
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• v.15 no.3
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• pp.26-31
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• 2021

In this study, laser-induced periodic surface structure (LIPSS) was fabricated on Ni, Si, and GaAs samples using a flat-top beam with a uniform energy distribution that was fabricated using a Gaussian femtosecond laser with a mechanical slit and tube lens. Unlike the Gaussian beam, the flat-top beam has a uniform beam profile, therefore the center and the periphery of the fabricated LIPSS have similar line periodicity. In addition, LIPSS was obtained not only in metals but also in metalloids and metals and metalloid compounds by using the narrow pulse width characteristic of a femtosecond laser.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6432-6439
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• 2014

The NAUT (Non-contact Air coupled Ultrasonic Testing) technique is one of the ultrasonic testing methods that enables non-contact ultrasonic testing by compensating for the energy loss caused by the difference in acoustic impedance of air with an ultrasonic pulser receiver, PRE-AMP and high-sensitivity transducer. As the NAUT is performed in a state of steady ultrasonic transmission and reception, testing can be performed on materials of high or low temperatures or specimens with a rough surface or narrow part, which could not have been tested using the conventional contact-type testing technique. For this study, the internal defects of spot weld, which are often applied to auto parts, and CFRP parts, were tested to determine if it is practical to make the NAUT technique commercial. As the spot welded part had a high ultrasonic transmissivity, the result was shown as red. On the other hand, the part with an internal defect had a layer of air and low transmissivity, which was shown as blue. In addition, depending on the PRF (Pulse Repetition Frequency), an important factor that determines the measurement speed, the color sharpness showed differences. With the images obtained from CFRP specimens or an imaging device, it was possible to identify the shape, size and position of the internal defect within a short period of time. In this paper, it was confirmed in the above-described experiment that both internal defect detection and image processing of the defect could be possible using the NAUT technique. Moreover, it was possible to apply NAUT to the detection of internal defects in the spot welded parts or in CFRP parts, and commercialize its practical application to various fields.

• Earthquakes and Structures
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• v.4 no.4
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• pp.397-428
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• 2013

This paper examines whether the "effective period" of bilinear isolation systems, as defined invariably in most current design codes, expresses in reality the period of vibration that appears in the horizontal axis of the design response spectrum. Starting with the free vibration response, the study proceeds with a comprehensive parametric analysis of the forced vibration response of a wide collection of bilinear isolation systems subjected to pulse and seismic excitations. The study employs Fourier and Wavelet analysis together with a powerful time domain identification method for linear systems known as the Prediction Error Method. When the response history of the bilinear system exhibits a coherent oscillatory trace with a narrow frequency band as in the case of free vibration or forced vibration response from most pulselike excitations, the paper shows that the "effective period" = $T_{eff}$ of the bilinear isolation system is a dependable estimate of its vibration period; nevertheless, the period associated with the second slope of the bilinear system = $T_2$ is an even better approximation regardless the value of the dimensionless strength,$Q/(K_2u_y)=1/{\alpha}-1$, of the system. As the frequency content of the excitation widens and the intensity of the acceleration response history fluctuates more randomly, the paper reveals that the computed vibration period of the systems exhibits appreciably scattering from the computed mean value. This suggests that for several earthquake excitations the mild nonlinearities of the bilinear isolation system dominate the response and the expectation of the design codes to identify a "linear" vibration period has a marginal engineering merit.