• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1041-1049
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• 1994

Longitudimal and transverse normal zone propagations in the superconducting coil are analyzed and propagation velocity is derived from the heat balance equations in the propagating boundary region. The results of applying to the specific superconducting wire show that propagation velocity is linearly proportional to the transport current and increasing ramp current speeds up the longitudinal velocity by 1.22[m/s] under the applied field of 2T. Transient heat transfer has a significant effect on the normal zone propagation velocity and it decreases longitudinal velocity by 5.2[m/s] under the applied field of 2T as being compared to the steady-state heat transfer. Increasing ramp current speeds up the Z-axis transverse propagation velocity by 0.042[m/s] and transverse velocity of R and Z axis is costant regardless of the current flows.

• Journal of the Korean earth science society
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• v.23 no.1
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• pp.72-86
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• 2002

The Middle to Late Cambrian Machari Formation in the Machari area, Yeongweol, Korea consists of 7 lithofacies and 3 facies associations, which are thought to be deposits of carbonate ramp (mid to outer ramp) to basin environment. These lithofacies are bedded lime mudstone, laminated lime mudstone, bioclastic/peloidal packstone to grainstone, poloidal/bioclastic wackestone, conglomerate, mottled lime mudstone, and shale. Bedded lime mudstone facies, a few cm thick lime mudstone alternating with shale layer, is believed to have been deposited by intermittent dilute turbidity currents. Laminated lime mudstone facies, alternating lime mudstone with laminated shale, is interpreted to have been formed by fine-grained turbidity currents. Bioclastic/peloidal packstone to grainstone facies was deposited by turbidity current and peloidal/bioclastic wackestone faceis was deposited by debris flow. Conglomerate facies is thought to be deposits of storm activities. Mottled lime mudstone facies is interpreted to have been formed by bioturbation. Shale facies is interpreted to have been formed by suspension settling. Seven lithofacies of the Machari Formation are divided into three facies associations. Facies association I consisted of bedded lime mudstone facies, mottled lime mudstone facies, conglomerate facies, and bioclastic/peloidal packstone to grainstone facies, is interpreted to have been deposited on the mid ramp. Facies assocaition II consisted of bedded lime mudstone facies, laminated lime mudstone facies, bioclastic/peloidal packstone to grainstone facies, and peloidal/bioclastic wackestone facies is thought to be deposits of the outer ramp. Facies association III consisted of laminated lime mudstone facies and shale facies is interpreted to have been formed on the basin environment.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1078-1080
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• 1993

The quench performance and ramp rate sensitivity of eighteen 5-cm-aperature, 15-m-long SSC dipole magnet prototypes are discussed. All the magnets appear to reach a quench plateau near their extrapolated short sample current limit and well in excess of the operating current with very little training. Most of the magnets, however, exibit a dramatic degradation of thier quench current as a function of ramp rate, which for the most part, can be attributed to large cable eddy currents.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.189-192
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• 2000

We fabricated rapid single-flux-quantum RS flip-flop circuits with and without Y$_1$Ba$_2$Cu$_3$O$_{7-{\delta}}$(YBCO) ground plane. The circuit consists of SNS-type ramp-edge Josephson junctions that have cobalt-doped YBCO and Sr$_2$AITaO$_6$(SAT) for barrier layer and insulator layer, respectively. The fabricated Josephson junction showed a typical RSJ-like current-voltage(I-V) characteristics above 50K. We sucessfuly demonstrated RS flip-flop at temperatures around 50K. The RS flip-flop fabricated on ground plane showed more definite set and reset state in voltage-flux(V-${\phi}$) modulation curve for read SQUID, which may be attributed to a shielding effect of the YBCO ground plane.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.5
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• pp.386-392
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• 2020

In this study, the drift current characteristics of charged particles are analyzed for panels fabricated by varying the waveform biasing of the active particle loading method (APLM), which is a method driven by the electrophoretic principle of loading charged particles into a cell of a barrier rib-type electronic paper. We prepare 3 panels using APLM and 1 panel without APLM. The waveform of APLM uses square wave and ramp wave, and the step voltage wave is applied to the driving voltage. The drift currents measured from the square wave and ramp wave with the same period applied by APLM are 4.872 µC and 5.464 µC, respectively, and the ramp wave is shown to be relatively advantageous for loading charged particles that have a large q/m. The time-current curve results confirm that the abrupt movement of charged particles is occurring. When the step form wave signal with a short time of 1s is first applied, initial large movement of the charged particles is confirmed to occur in all samples, which is understood as the effect of applying the voltage necessary to remove the imaging force. The results of this study are expected to improve the loading of charged particles into the electronic paper cell, driven by the electrophoretic principle and optimization of the driving conditions.

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.19-23
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• 2000

We are developing a small-sized superconducting magnetic energy storge ($\mu$SMES) magnet with the storage capacity of a few megajoules, which provides electric power with high quality to sensitive electric loads. A kA class superconductor with a high coppe $r^erconductor ratio was selected as a candidate conductor. The superconductor was tested in two points of view, which are basic and important in development of the $\mu$SMES magnet. First, stabilities of the superconductor against localized disturbances such as wire motions were estimated by using a wire heater. Second, the quench current characteristics for different charge rates were also tested. The stability data showed that the short heat pulses made the conductor more unstable. The superconductor had relatively high recovery currents ranging between 40% and 50% of its critical currents. The quench tests indicated that the quench currents of the conductor were independent of current ramp rates up to 3000 A/s and nearly equal to its cuitical current data.ta.

• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.79-87
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• 2007

The interchanges of urban freeways have many problems with traffic operation due to high off-ramp flows and frequent congestion at adjacent intersections. The flow exiting from off-ramps is affected by the operational status and traffic volume conditions of the nearest signalized intersection. As a result, off-ramp flow cannot exit and the queue backs up the freeway mainline when queues from the signalized intersection form up to the junction of the off-ramp and street. The spacing between an off-ramp and an adjacent intersection is likely to determine the traffic conditions at the adjacent intersection. However, the current design guidelines do not consider such a factor. This study is to develop a model calculating the spacing between off-ramps and adjacent intersections considering the signal, traffic, and road conditions. The variables affecting the model in this study are effective green time (g/C), volume-capacity ratio (v/c), the number of lanes, and off-ramp volume. Various scenarios are designed to represent the effects of the variables and the road networks are constructed using VISSIM, which is a common traffic micro-simulation software package. The queue length is derived from VISSIM and this length is considered as the recommended spacing between the off-ramp and the adjacent intersection. Through the simulation analysis, regression models are developed to calculate the queue length reflecting the various conditions such as signals, traffic, and road configurations. The developed model can be used to create road design guidelines to determine the location of off-ramps in the planning stage.

• Journal of Korean Society of Transportation
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• v.31 no.5
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• pp.71-78
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• 2013

This paper investigated the influences of ramp traffic flow on the lane utilization for signalized intersection approaches which are adjacent to an off-ramp-street junction. The statistical test showed a correlation between lane utilization and the ramp traffic flow. As the ramp traffic flow increases, the left lanes are less utilized and the right lanes are more utilized. The lane utilization factors are calculated by applying traffic data collected from the Seoul Metropolitan area. The utilization factors are 1.113 for 2 lanes, 1.124 for 3 lanes, and 1.131 for 4 lanes. The lane utilization factors proposed in the paper show higher values than those in current Korea Highway Capacity Manual (KHCM) under the conditions that the number of lanes is 2 or 3. However, the lane utilization factor for 4 lanes in the paper shows lower value than in KHCM. The ramp traffic flow causes more utilization of the right lanes than at normal signalized intersections and the extent gets larger as the number of lanes decreases. Based on the results of the paper, the lane utilization factors at signalized intersection approaches should be revised and reasonable capacity should be recalculated if the signalized intersection is adjacent to an off-ramp-street junction.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.145-151
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• 2009

Current highway design standards is based on the safety under the free flow condition. The length of deceleration lane is also determined in terms of the deceleration distance which is necessary for the driers to adjust the vehicle speed from the speed limit on the main road to that on the exit ramp of the interchange. However, the queues are frequently developed on the deceleration, and the following vehicles to exit must decelerate on the main road. It may cause delay on the main road and traffic accidents. This study is to suggest a methodology to minimize such problems with the shock-wave theory. The queue length of exiting vehicles can be estimated by the design speeds, traffic volumes of main road and the exiting ramp, and the countermeasures to the operational problems. According to the results, the queue length can be shortened to 80% by upgrading the design speed of exit ramp as the amount of 10km/h. Fifty percent of queue length can be shortened by adding an additional lane on the ramp to two lanes.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.75-77
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• 2003

We have measured the escape rates of the Nb Josephson junction from its zero-voltage state. The critical current measurements were carried out in repeatedly sweeping the current-voltage characteristics of the junction with a current ramp. From the distribution of the critical current the escape temperature was determined by applying the thermal activation model.