• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.630-634
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• 2016

In this paper, we analyzed the power consumption and the accumulated energy in HTSC (high-TC superconducting elements) according to the resistance of HTSC element and the winding current of transformer type SFCL (superconducting fault current limiter) using double quench. For the analysis, two different inductances of the one secondary winding among two secondary windings comprising the transformer type SFCL were selected and the short-circuit tests were carried out. The consumed power and the accumulated energy in HTSC element connected into the secondary winding with larger inductance were analyzed to be larger compared to the one connected into the secondary winding with lower inductance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.71-79
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• 2015

Recently, new Low Voltage DC (LVDC) power distribution systems have been constantly researched as uses of DC in end-user equipment are increased. As in conventional AC distribution system, High Impedance Fault (HIF) which may cause a failure of protective relay can occur in LVDC distribution system as well. It, however, is hard to be detected since change in magnitude of current due to the fault is too small to detect the fault by the protective relay using overcurrent element. In order to solve the problem, this paper presents an algorithm for detecting HIF using accumulated energy in LVDC distribution system. Wavelet Singular Value Decomposition (WSVD) is used to extract abnormal high frequency components from fault current and accumulated energy of high frequency components is considered as the element to detect the fault. LVDC distribution system including AC/DC and DC/DC converter is modeled to verify the proposed algorithm using ElectroMagnetic Transient Program (EMTP) software. Simulation results considering various conditions show that the proposed algorithm can be utilized to effectively detect HIF.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.383-393
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• 2024

Monopile foundations of offshore wind turbines embedded in soft clay are subjected to the long-term cyclic lateral loads induced by winds, currents, and waves, the vibration of monopile leads to the accumulation of pore pressure and cyclic strains in the soil in its vicinity, which poses a threat to the safety operation of monopile. The researchers mainly focused on the hysteretic stress-strain relationship of soft clay and kinds of stiffness degradation models have been adopted, which may consume considerable computing resources and is not applicable for the long-term bearing performance analysis of monopile. In this study, a modified cyclic stiffness degradation model considering the effect of plastic strain and pore pressure change has been proposed and validated by comparing with the triaxial test results. Subsequently, the effects of cyclic load ratio, pile aspect ratio, number of load cycles, and length to embedded depth ratio on the accumulated rotation angle and pore pressure are presented. The results indicate the number of load cycles can significantly affect the accumulated rotation angle of monopile, whereas the accumulated pore pressure distribution along the pile merely changes with pile diameter, embedded length, and the number of load cycles, the stiffness of monopile can be significantly weakened by decreasing the embedded depth ratio L/H of monopile. The stiffness degradation of soil is more significant in the passive earth pressure zone, in which soil liquefaction is likely to occur. Furthermore, the suitability of the "accumulated rotation angle" and "accumulated pore pressure" design criteria for determining the required cyclic load ratio are discussed.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.63-69
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• 2003

In this study seismic design procedure for buckling-restrained braced frame systems was proposed using hysteretic energy spectrum and accumulated ductility spectrum constructed from single degree of freedom systems. The hysteretic energy spectra and accumulated ductility spectra corresponding to target ductility ratio were constructed first. The cross-sectional area of braces required to meet a given target displacement was obtained by equating the hysteretic energy demand to the accumulated plastic energy dissipated by braces. Twenty earthquake records were utilized to construct the spectra and to verify the validity of the design procedure. According to analysis results of three- and eight-story buckling-restrained braced frame structures designed using the proposed method, the mean values for the top story displacement correspond well with the given performance target displacements. Also, the inter-story drifts turned out to be relatively uniform over the structure height, which is desirable because uniform inter-story drifts indicate uniform damage distribution. Therefore if was concluded that the proposed energy-based method could be a reliable alternative to conventional strength-based design procedure for structures with buckling-restrained braces.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.279-286
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• 2013

Purpose: This study was conducted to analyze the utilization efficiencies of electric energy and photosynthetically active radiation of lettuce grown under red LED, blue LED and fluorescent lamps with different photoperiods. Methods: Red LED with peak wavelength of 660 nm and blue LED with peak wavelength of 450 nm were used to analyze the effect of three levels of photoperiod (12/12 h, 16/8 h, 20/4 h) of LED illumination on light utilization efficiency of lettuce grown hydroponically in a closed plant production system (CPPS). Cool-white fluorescent lamps (FL) were used as the control. Photosynthetic photon flux, air temperature and relative humidity in CPPS were maintained at 230 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $22/18^{\circ}C$ (light/darkness), and 70%, respectively. Electric conductivity and pH were controlled at 1.5-1.8 $dS{\cdot}m^{-1}$ and 5.5-6.0, respectively. The light utilization efficiency based on the chemical energy converted by photosynthesis, the accumulated electric energy consumed by artificial lighting sources, and the accumulated photosynthetically active radiation illuminated from artificial lighting sources were calculated. Results: As compared to the control, we found that the accumulated electric energy consumption decreased by 75.6% for red LED and by 70.7% for blue LED. The accumulated photosynthetically active radiation illuminated from red LED and blue LED decreased by 43.8% and 33.5%, respectively, compared with the control. The electric energy utilization efficiency (EEUE) of lettuce at growth stage 2 was 1.29-2.06% for red LED, 0.76-1.53% for blue LED, and 0.25-0.41% for FL. The photosynthetically active radiation utilization efficiency (PARUE) of lettuce was 6.25-9.95% for red LED, 3.75-7.49% for blue LED, and 2.77-4.62% for FL. EEUE and PARUE significantly increased with the increasing light period. Conclusions: From these results, illumination time of 16-20 h in a day was proposed to improve the light utilization efficiency of lettuce grown in a plant factory.

• Preventive Nutrition and Food Science
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• v.6 no.3
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• pp.152-157
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• 2001

Accumulated photon counts in immediate measurement after irradiation of marjoram, basil and thyme were shown to be below 625$\pm$162, 577$\pm$178 and 1261$\pm$640 Pc, respectively. The accumulated photon counts increased linearly with increasing irradiation doses up to 5 kGy and slightly increased from 5 kGy to 10 kGy. This trend was similar after storage periods. According to storage conditions, the difference of the accumulated photon counts was net clearly observed. The accumulated photon counts of irradiated spice samples decreased with increasing storage periods. The rate of decrease was higher in 5 and 10 kGy irradiated samples than that in 1 kGy, and in room conditions than that in darkroom conditions. The photon counts of the irradiated spice samples measured for 120 s were higher than those measured for 60 s. The irradiated spice samples showed higher photon counts than those of unirradiated samples in both room and darkroom conditions during all the storage periods. These results indicate that detection of irradiation was still possible after 24 weeks, although the PPSL signal of all spice samples decreased with increasing storage times.

• Preventive Nutrition and Food Science
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• v.6 no.4
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• pp.216-223
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• 2001

A study was carried out to examine the effect of sample form and storage conditions on the accumulated PPSL signals. Korean perilla and sesame seeds were tested as whole samples and separated minerals. Radiation-induced PPSL signals of perilla and sesame seeds themselves significantly increased with irradiation dose up to 5 kGy. On the other hand, a slight decrease in the accumulated PPSL signals was shown at 10 kGy. Similar results were also found in separated minerals. The accumulated PPSL signals of irradiated samples decreased with increasing storage periods. The decay rate was higher in 5 or 10 kGy-irradiated samples than in 1 kGy, in room conditions than in darkroom conditions, and in sesame and perilla seeds themselves than in separated minerals. The accumulated PPSL signals of the irradiated samples measured fur 120 s were higher than those measured for 60 s. These results indicated that although the PPSL signal of all samples decreased with increasing the storage time, detection of irradiated samples was still possible after 12 months of storage regardless of sample form and measurement times (60 and 120 s) in both room and darkroom conditions.

• BioChip Journal
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• v.12 no.4
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• pp.340-347
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• 2018

$F{\ddot{o}}rster$ resonance energy transfer (FRET) is extremely sensitive to the separation distance between the donor and the acceptor which is ideal for probing such biological phenomena. Also, FRET-based probes have been developing for detecting an unamplified, low-abundance of target DNA. Here we describe the development of FRET based DNA sensor based on an accumulated QD system for detecting KRAS G12D mutation which is the most common mutation in cancer. The accumulated QD system consists of the polystyrene beads which surface is modified with carboxyl modified QDs. The QDs are sandwich-hybridized with DNA of a capture probe, a reporter probe with Texas-red, and a target DNA by EDC-NHS coupling. Because the carboxyl modified QDs are located closely to each other in the accumulated QDs, these neighboring QDs are enough to transfer the energy to the acceptor dyes. Therefore the FRET factor in the bead system is enhancing by the additional increase of 29.2% as compared to that in a single QD system. These results suggest that the accumulated nanobead probe with conjugated QDs can be used as ultrasensitive DNA nanosensors detecting the mutation in the various cancers.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1124-1129
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• 2008

Recently, two-port time-domain passivity approach was modified for time-varying communication delay. The newly proposed approach could achieve stable teleoperation even under the serious time-varying delay and packet loss communication condition. However, after some operation hour, the accumulated energy difference between the input energy from one port and the output energy at the other port caused unstable behavior until the passivity controller is activated. Resetting scheme is introduced for solving this problem, and stable bilateral teleoperation can be guaranteed without worrying about the accumulated energy difference.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.8
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• pp.1792-1798
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• 2010

Home Gateway is always on for continuous services of home networks. Ubiquitous home networks are extended. so power consumption of home gateways increases by geometric progression. Our algorithm is for home gateway to sleep, listen or wakeup according to network traffic adaptively, as well as to keep always-on service. To do this, it traces the accumulated average of previous sleep periods. In addition to this basic algorithm, we make the profiles for user's living pattern per the day to reflect network usages in detail and adaptively. As the simulation results by comparing with overall accumulated average and per-day accumulated average, in case of the overall accumulated average, the difference the estimation and real value is distributed from 0.43% to 4%. In contrast of this, in case of the per-day accumulated average is distributed from 0.06% to 2%. From this results, we know the profiling of per-day usage pattern can help reduce the difference of the real sleep period and the estimated sleep period.