• Magazine of the Korean Society of Hazard Mitigation
• /
• v.6 no.4 s.23
• /
• pp.57-64
• /
• 2006

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.26 no.6
• /
• pp.381-387
• /
• 2014

Recently the large-height swell-like waves generated in the eastern coast of South Korea have been observed frequently. The characteristics of the runup and overtopping of the large-height swell-like waves formed in deep water and attack the coast, causing damages to both lives and facilities have been studied. The correlation between spectral shape parameters and significant wave height has been investigated by analyzing long term wave spectrum data. Numerical runup experiments using MIKE21 BW Module were performed with $Q_p$, additional shape parameter, and identified the variations and characteristics of runup heights with respect to the variations of spectral shape.

• Journal of Korean Society of Forest Science
• /
• v.17 no.1
• /
• pp.17-22
• /
• 1973

A study on the wood quality from planted Pinus koraiensis Sieb. et Zucc. has been undertaken by the University Forest in order to gain results of the gross structural features of stem. For this study some groups of trees were felled and several characteristics such as the degree of stem, slenderness, eccentric growth, heartwood diameter, height of butt sweep and butt-swell were analyzed. The results of the study are as follows. 1) The relation between diameter of log and its height in sample trees are nearly parallel to each other. But their degrees of slenderness in logs cut from intermediate and codominant trees are some what gentle as compared with that of logs from dominant tree. 2) The eccentric growth at transverse section of sample trees is generally decreased with the increase of tree height on all sample trees. 3) On the eccentric growth at transverse section of tree, a rather distinct tendency was noticed that all of sample trees showed the direction of eccentric growth in $R_2$ side. 4) Heartwood diameter appeares to become larger as tree growth decrease under same diameter of logs and log diameter in which heartwood appeares is larger in rapid growth rate trees. 5) The maximum height of butt-sweep generally shows that the larger the breast height diameter of tree is, the smaller its height becomes. On the contrary it was noticed that the larger the breast height diameter of trees, the higher the maximum height of butt-swell became. The direction of butt-sweep and butt-swell were shown in $R_1$ side in all sample trees.

• Applied Biological Chemistry
• /
• v.25 no.3
• /
• pp.119-125
• /
• 1982

Using piston type extruder, barley flour was extruded at various processing conditions, The used variables were three shear rates (apparent shear rate 118, 534, $1169sec^{-1}$), four extrusion temperatures(90, 120, 150, $180^{\circ}C$) and three moisture contents (15, 25, 35%). The rheological properties and the extrudate quality were monitored in extrusion. Barley flour showed pseudoplastic behavior having average power law index 0.28 in used shear rate range. When viewed from general appearance, die swell, density, water uptake, rehydration swell and gelatinization degree of extrudate, $25{\sim}35%$ moisture and $120^{\circ}C$ temperature was suitable processing condition for noodle-like product, and 25% moisture and $150^{\circ}C$ temperature was good for snack or flake product. Moisture content of the extrudate can be pretty well estimated from energy balance at higher temperature and higher moisture content.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.5
• /
• pp.42-48
• /
• 2006

The number of confine-disease of elevator increases every year and then sudden rise, sudden stop, error of level indication, stand; those can bring to uneasiness of elevator passenger and malfunction accidents related life accident are increasing. For confirmation those malfunction accident, we are measuring and analyzing power quality(Sag, Swell, Interruption) of the actual site and evaluated the performance for stop and stating by testing the two imitation test equipment with EN12016(2004) standard level. This paper will be used data of the analysis for mutual relation between Power Quality and malfunction and fault of elevator.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.28 no.4
• /
• pp.212-221
• /
• 2016

In this study, characteristics of swell-like high waves in the East Sea were analyzed using observed wave data and predicted meteorological data from the National Oceanic and Atmospheric Administration (NOAA). And, the wave prediction system using the data from the NOAA has been established. Furthermore, the applicability of the system has been verified by comparing the predicted results with the corresponding observed data. For some case, there were two times of wave height increase and the second increase occurred in a calm weather condition on the coast which might cause casualties. The direction of wave energy propagation was estimated from observed wave data in February, 2008. Through comparison between the direction of wave energy propagation and the meteorological data, it turns out that the second increase of waves is originated from the seas between Russia and Japan which is far from the East Sea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.10
• /
• pp.41-48
• /
• 2008

This paper proposes a three-phase Z-source dynamic voltage restorer (Z-DVR) to mitigate the voltage sag for the critical loads. The proposed system is composed of passive filter and Z-source topology inverter. As an ESS(Energy Storage System) of the proposed system is employed the Proton Exchange Membrane Fuel Cells (PEMFC). To calculate and control the harmonics and compensation voltage, $i_{d}-i_{q}$ theory in dq rotating reference frame and PI controller are used. In case that three-phase voltage sags occurred, a PSIM simulation was done for the performance comparison of the conventional method employed battery stacks and proposed method. As a result, considering the voltage compensation performance, each method was nearly similar. Also, the compensation performance and the %THD(%Total Harmonic Distortion) result under the various source voltage conditions (sag or swell) were presented and discussed to show the performance of the proposed system.

• Journal of IKEEE
• /
• v.25 no.4
• /
• pp.710-715
• /
• 2021

Power line signal can show disturbances due to various causes. Typical anomalies are temporary sag/swell of the amplitude, flat topped signal, and harmonic distortions. The disturbances need to be detected and treated properly for the quality of the power signal. In this study, the power disturbances are detected using the inflection points (IP). The inflection points are defined as points where local maxima/minima or the slope changes occur. The power line signal has a fixed IP pattern since it is basically sinusoidal, and it may have additional inflection points if there is any disturbance. The disturbance is detected by comparing the IP patterns between the normal signal and distorted signal. In addition, by defining a cost function, the time instant where the disturbance happens can be decided. The computer simulation shows that the proposed method is useful for the detection of various disturbances. The simple sag or swell signal only shows the amplitude changes at the detected inflection points. However, the flat top signal and harmonically distorted signal produce additional inflection points and large values in the cost function. These results can be exploited for the further processing of disturbance classification.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.6
• /
• pp.394-404
• /
• 2013

In the present study, the characteristics of spectral peakedness parameter $Q_p$, bandwidth parameter ${\varepsilon}$, and spectral width parameter ${\nu}$ were analyzed as a first step to define the swell waves quantitatively. For the analysis, the joint probability density function of significant wave heights and peak periods were newly developed. The MCMC(Markov Chain Monte Carlo) simulations have been performed to generate the significant wave heights and peak periods from the developed probability density functions. Applying the simulated significant wave heights and peak periods to the theoretical wave spectrum models, the spectral shapes parameters were obtained and analyzed. Among the spectral shape parameters, only the spectral peakedness parameter $Q_p$, is shown to be independent with the significant wave height and peak wave period. It also best represents the peakedness of the spectral shape, and henceforth $Q_p$ should be used to define the swell waves with a wave period. For the field verification of the results, wave data obtained from Hupo port and Ulleungdo were analyzed and results showed the same trend with the MCMC simulation results.

• Geophysics and Geophysical Exploration
• /
• v.18 no.4
• /
• pp.181-196
• /
• 2015

A 3.5 kHz or chirp sub-bottom profiling survey is widely used in the marine geological and engineering purpose exploration. However, swells in the sea degrade the quality of the survey data. The horizontal continuity of profiler data can be enhanced and the quality can be improved by correcting the influence of the swell. Accurate detection of sea bottom location is important in correcting the swell effect. In this study, we tried to pick sea bottom locations by finding the position of crossing a threshold of the maximum value for the raw data and transformed data of envelope or energy ratio. However, in case of the low-quality data where the sea bottom signals are not clear due to sea wave noise, automatic sea bottom detection at the individual traces was not successful. We corrected the mispicks for the low quality data and obtained satisfactory results by picking a sea bottom within a range considering the previous average of sea bottom, and excluding unreliable big-difference picks. In case of trace by trace picking, fewest mispicks were found when using energy ratio data. In case of picking considering the previous average, the correction result was relatively satisfactory when using raw data.