• Progress in Superconductivity
• /
• v.1 no.2
• /
• pp.85-88
• /
• 2000

The temperature dependent Josephson critical current $J_c(T)/J_c(0)$ between high $T_c$ superconductors along the a-axis is theoretically studied. The interface influence on the wave functions of quasi-particles is included in the theory within the framework of the two-dimensional t-J model. It is found that the experimental results can be satisfactorily explained by the present model with d wave pairing symmetry.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.427-432
• /
• 1999

When a high-speed train enters a tunnel, a compression wave is generated. This wave subsequently emerges from the exit portal of the tunnel, which causes an impulsive noise called 'Sonic boom' or 'micro-pressure wave'. In the present study, new method is presented for prediction of sonic boom noise, especially focusing on the effect of the nose shape of the train on the resultant noise. Acoustic theory for monopole source is used to represent a nose shape of the train in wave equation. Compression wave propagation in tunnel considering tunnel track condition and emission of sonic boom was calculated. The predicted compression waves and impulsive sound waves are compared with recent measurements, and show reasonable agreements.

• Proceedings of the IEEK Conference
• /
• 2001.06e
• /
• pp.77-80
• /
• 2001

In this paper, we devised volume pulse detection system which can quantitatively represent a artery elasticity for oriental clinic. Volume pulse wave detecter system consist of transducer which has IRLED-photodiode detecter, temperature sensor and filter and preprocessing circuits, data conversion and serial communication parts, and computer system. The high-pass filter are detect volume pulse wave and lowpass filter detect tissue thickness. The detected volume pulse wave are normalized by tissue thickness value with a division process. As the result of experiment, we can detect normalized volume pulse wave with effectively.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.19 no.4
• /
• pp.53-59
• /
• 1982

Relative bow-motions of a ship in wave are investigated by using linear theory. The relative displacement is assumed to be composed of incident wave elevation, motion response, dynamic swell-up and ship wave elevation. Radiation problem is solved by distributing sources on the hull surface and wave elevation in a uniform stream is obtained by integrating Havelock's function with centerplane source distributions. Relative displacements for I.T.T.C. S7-175 model are calculated. Dynamic swell-ups make the relative displacement larger except small heading angles. Amplitudes of relative motion on weather-side are generally larger than those on lee-side. Ship wave elevations in a uniform stream also give considerable contributions and our calculations are verified to be reasonable in comparison with experimental results.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.5
• /
• pp.1218-1226
• /
• 1994

The shock tube is a useful device for investigating shock phenomena, spray combustion, unsteady gas dynamics, etc. Therefore, it is necessary to analyze exactly the flow phenomena in shock tube. In this study, the mechanics of its reflected shock zone has been investigated by using of the one-dimensional gas dynamic theory in order to estimate the transition from initial reflection of shock wave region. Calulation for four kinds of reflected shock tube temperature (i.e. (a) 1388 K (b) 1276 K (c) 1168 K (d) 1073 K) corresponding to the experimental conditions have been carried out sumarized as follows. (1) The qualitative tendency is almost the same as in that conditions in region of reflected wave region. (2) High temperature period (reflected shock wave temperature) $T_{5}$, exists 0-2.65 ms. (3) Transition period from temperature of reflection shock wave is far longer than the calculated one. This principally attributed to the fact that the contact surface is accelerated, also, due to the release of energy by viscoity effect. This apparatus can advance the ignition process of a spray in a ideal condition that involved neither atomization nor turbulent mixing process, where, using a shock tube, a column of droplets freely from atomizer was ignited behind a reflected shock.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.30 no.2
• /
• pp.51-60
• /
• 2018

This study was conducted to observe the effects of gravity and infra-gravity wave of detached submerged breakwater in the coast of Yeongnang-dong, Sokcho, as analyzing continuous wave data by performing field observations on the front area (W0) and rear area (W1, W2). Wave transmission coefficient ($K_t$) of submerged breakwater was analyzed in two parts, short-period wave (gravity wave) and infra-gravity wave. The wave energy reduction effect was analyzed and compared with the value of the design. In case of above wave height 2.0 m at the front area (W0) of the submerged breakwater, the short-period wave height at point W1 is reduced by about 65% and the short-period wave height at point W2 is reduced by about 59%. The depth of crest of submerged breakwater conducted in a sea area differs from the design, and the wave energy reduction effect is analyzed to be smaller than the design plan. The infra-gravity waves were amplified to 2.11 and 1.71 at the W1 and W2 points, respectively, and the wave height at W2 point was smaller than that at W1 point.

• Progress in Superconductivity
• /
• v.9 no.1
• /
• pp.29-34
• /
• 2007

The baseline selection is the first and important step to analyze magnetocardiography (MCG) parameters. There are no difficulties to select the baseline between P- and Q-wave peak (P-Q interval) of MCG wave recorded from healthy subjects because the P-Q intervals of the healthy subjects do not much vary. However, patients with ischemic heart disease often show an unstable P-Q interval which does not seem to be appropriate for the baseline. In this case, T-P interval is alternatively recommended for the baseline. However, there has been no study on the difference made by the baseline selection. In this study, we studied the effect of the different baseline selection. MCG data were analyzed from twenty healthy subjects and twenty one patients whose baselines were alternatively selected in the T-P interval for their inappropriate P-Q interval. Paired T-test was used to compare two set of data. Fifteen parameters derived from the R-wave peak, the T-wave peak, and the period, $T_{max/3}{\sim}T_{max}$ were compared for the different baseline selection. As a result, most parameters did not show significant differences (p>0.05) except few parameters. Therefore, there will be no significant differences if anyone of two intervals were selected for the MCG baseline. However, for the consistent analysis, P-Q interval is strongly recommended for the baseline correction.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.35 no.6
• /
• pp.274-279
• /
• 2021

This study was conducted to find objective diagnostic indicators for the Eight Principle Pattern Identification using a pulse wave analyzer. Typology Complexion Pulse and Symptom data from 500 women over the age of 18 were used. Five experts made a diagnosis of Eight Principle Pattern Identification and divided the subjects into 'Yin-Yang', 'Exterior-Interior', 'Cold-Heat', 'Deficiency-Excess' groups. Their pulse waves were measured in the left and right radial arteries, and it was investigated whether there was a significant difference between groups in the pulse wave parameter values. 'Yin' group showed a significantly lower value in the left radial artery for Ener, Emin, EIX, T4T, T4TT parameters and in the Right for T2, T2T, T5. The Vmag, As and Ad parameters were significantly different between the 'Exterior' and 'Interior' groups. 'Heat' group showed a significantly higher value in the right radial artery for RAI/t parameter. 'Deficiency' group showed a significantly higher value in the right radial artery for W, Angl parameters. Through this study, significant pulse wave parameters were found, and they can be used as objective diagnostic indicators for Eight Principle Pattern Identification.

• Journal of Navigation and Port Research
• /
• v.45 no.6
• /
• pp.366-371
• /
• 2021

This study suggests surface wave communication, which uses a metal surface as a medium, to provide wireless communication in the extreme environment due to surrounding metal materials on vessels. The test was conducted on a G/T 265 tons tug boat to confirm the possibility of surface wave communication between a bridge and each designated space in the ship. As a result, the transmission speed was 13Mbps on average. In a test case of the bridge via the engine room, the transmission speed was 4.3Mbps on engine running and 1.2Mbps on sailing. It overcame this by partially changing the equipment installation location. Surface wave communication in bow storage, a fully enclosed space, had 8Mbps better transmission speed than wireless communication; this confirmed the superiority of surface wave communication in confined spaces on a vessel. Additional surface wave generators were designed and applied to resolve the paint issue. It is expected to use surface wave communication to implement the new wireless solution for Maritime-IoT system on vessels.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.6
• /
• pp.687-693
• /
• 1992

To improve dielectric, piezoelectric and temperature stability in 0.50Pb(SnS11/2TSbS11/2T)OS13T - 0.35PbTiOS13T - 0.60PbZrOS13T + 0.4[wt%]MnOS12T piezoelectric ceramics which is used for surface acoustic wave devices, CrS12TOS13T was added and the specimens were fabricated by Hot Press method, and their characteristics were measured with CrS12TOS13T addition. From the results, in the specimen added by 0.2[wt%]CrS12TOS13T, dielectric constant and mechanical quality factor were 380 and 2307, respectively, and it was suited for surface acoustic wave device and the temperature coefficient of the resonant frequency in the specimen added by 0.4[wt%]CrS12TOS13T was the least value of 74.96[ppm/$^{\circ}C$].