• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.99-109
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• 2004

Most traffic congestion on a freeway occurs in the merge area, where conflicts between mainline traffic and on-ramp traffic are frequently generated. So far, research on the merge area has mainly dealt with free flow traffic and research on the congested traffic at the merge area is rare. This study investigates the relationships between mainline traffic and on-ramp traffic at three different segments of the merge area. For this purpose, new indicators based on such traffic variables as flow, speed, and density are used. The results show that a negative relationship exists between mainline and on-ramp flow. It is also found that the speed and the density of the right two lanes in the mainline traffic are significantly affected by the on-ramp flow. Based on the correlation analysis of the indicators, it is confirmed that the ramp influence area is the right two lanes of the freeway mainline. The revealed relationships between mainline and on-ramp traffic may help to analyze the capacity of the downstream freeway segment of the merging area in congested traffic. The findings of this studyalso provide a basis to develop a model that estimates the merge traffic volume in congested traffic, which is neither theoretically nor empirically sound in most other traffic flow models developed so far.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.1004-1008
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• 2012

The effect of address discharge characteristics by selective reset method is investigated to prevent the weakness of address discharge in the middle of a TV-field without increase of the black luminance. To reduce black luminance in AC PDP usually, the first subfield during one TV frame adopted the conventional rising ramp-reset waveform, whereas the other subfields adopted the subsidiary reset waveform without rising ramp type. As the wall charge for the address discharge was accumulated by only the rising ramp waveform during the first reset period, the wall charge on three electrodes was disappeared as time passed and the address discharge would be weakened in the rear subfields. To prevent a reduction of the address discharge characteristics without decrease the black luminance, the modified rising ramp reset waveform was adopted only in the sixth subfield. As a result, a modified driving method could improve the address discharge characteristics compared with selective reset driving scheme with almost the same black luminance.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.4
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• pp.488-503
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• 2012

The stern boat deployment system was investigated to evaluate the capability of launching and recovering rigid hull inflatable boat (RHIB) via the stern ramp. The main parameters to launch and recover RHIB were tested at the design stage. The combined hydrodynamic effect of the stern wake and the water jet flow made it difficult to maintain the maneuvering and sea-keeping ability of RHIB approaching to the stern ramp. The safe recovery course was proposed to maintain the directional control of RHIB and to reduce the combined hydrodynamic effect in the transom zone. To evaluate the feasibility of RHIB recovery, the stern sill depth was measured in various conditions and the ramp availability time was obtained. Also, the experimental percent time operability (PTO) test was performed by the number of successive launching and recovering operations.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2031-2042
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• 2017

In this paper, a novel traffic flow control method based-on ramp metering and speed regulation using an adaptive sliding mode control (ASMC) method along with a deadzoned parameter adaptation law is proposed at a stochastic macroscopic level traffic environment, where the influence of the density and speed disturbances is accounted for in the traffic dynamic equations. The goal of this paper is to design a local traffic flow controller using both ramp metering and speed regulation based on ASMC, in order to achieve the desired density and speed for the maintenance of the maximum mainline throughput against disturbances in practice. The proposed method is advantageous in that it can improve the traffic flow performance compared to the traditional methods using only ramp metering, even in the presence of ramp storage limitation and disturbances. Moreover, a prior knowledge of disturbance magnitude is not required in the process of designing the controller unlike the conventional sliding mode controller. A stability analysis is presented to show that the traffic system under the proposed traffic flow control method is guaranteed to be uniformly bounded and its ultimate bound can be adjusted to be sufficiently small in terms of deadzone. The validity of the proposed method is demonstrated under different traffic situations (i.e., different initial traffic status), in the sense that the proposed control method is capable of stabilizing traffic flow better than the previously well-known Asservissement Lineaire d'Entree Autoroutiere (ALINEA) strategy and also feedback linearization control (FLC) method.

• Journal of Embryo Transfer
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• v.16 no.2
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• pp.133-138
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• 2001

The aim of this study was to identify the method on extended canine semen exposed to freezing as assessed by motility, survival and acrosomal changes following different freezing ramp rates. Five ejaculates collected by digital manipulation twice weekly from three dogs (Shih-Tzu) were added Tris-Egg Yolk (TE) buffer and divided into 4 aliquots according to formulation of our laboratory. After cooling to 4$^{\circ}C$ by ramp rate of 0.6$^{\circ}C$/min, the samples frozen by ramp rates of 1.6$^{\circ}C$/min to -$25^{\circ}C$, 3$^{\circ}C$/min to -35$^{\circ}C$, 8.9$^{\circ}C$/min to -7$0^{\circ}C$ and 19$^{\circ}C$/min to -11$0^{\circ}C$, respectively, and then stored in L$N_2$for 2days. Each sample was evaluated on their motility, survivability and acrosome integrity at different thawing temperature. The ramp rate of 3$^{\circ}C$/min to -35$^{\circ}C$/h for freezing and thawing temperature of 37$^{\circ}C$ obtained the highest results to improve survivability, motile spermatozoa and intact acrosome appearance than other onditions. In conclusion, we may suggest freezing semen for canine artificial insemination is more efficient with freezing at a ramp rate of -3$^{\circ}C$/min to -35$^{\circ}C$ and thawing with a water bath adjusted to 37$^{\circ}C$.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.287-293
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• 2008

Density is used as the measure of effectiveness within the ramp junction influence area suggested in the KHCM 2005 in the LOS analysis of the ramp junction, and also density predictive models suggested in the KHCM 2005 is constructed based on the expressway with the speed limit of 100km/h or 110km/h in Korea. So, the density predictive models suggested in the KHCM 2005 are needed to verify if the models could be applied to the urban freeway with the speed limit of 80km/h or less, because the speed limits on most of the urban freeways in Korea are 80km/h or less. The purpose in this study is to construct and verify the appropriate density predictive model within the on-ramp merge influence area of the urban freeway by comparing with the USHCM 2000 and KHCM 2005 models.

• 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.

• Progress in Superconductivity
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• v.2 no.2
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• pp.76-80
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• 2001

We have fabricated YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) ramp-edge Josephson junctions by modifying ramp edges of the base electrodes without depositing any artificial barrier layer. YBa$_2$Cu$_3$O/7-x//SrTiO$_3$ (YBCO/STO) films were deposited on SrTiO$_3$(100) by on-axis KrF laser deposition. After patterning the bottom YBCO/STO layer, the ramp edge was cleaned by ion-beam and then reacted with deionized water under various conditions prior to the deposition of counter-electrode layers. The top YBCO/STO layer was deposited and patterned by photolithography and ion milling. We measured current-voltage (I-V) characteristics, magnetic field modulation of the critical current at 77 K. Some showed resistively shunted junction (RSJ)-type I-V characteristics, while others exhibited flux-flow behaviors, depending on the dipping time of the ramp edge in deionized water. Junctions fabricated using optimized conditions showed fairly uniform distribution of junction parameters such as I$_{c}$R$_{n}$ values, which were about 0.16 mV at 77 K with 1$\sigma$~ 24%. We made a dc SQUID with the same deionized water treated junctions, and it showed the sinusoidal modulation under applied magnetic field at 77 K. 77 K.

• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.17-28
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• 2008

This study examines the ramp-up analysis techniques which have been introduced till now and presents the strength and weakness of each method. The applicability of each technique was reviewed using a case study involving the data of Cheonan-Nonsan motorway usages where seasonal variations of the data were removed. The results showed that all the techniques except F-test have the same ramp-up period of 12 months. The level of Tamp-up was 65%-72% compared to that of the real traffic volume at the beginning of opening. The demand recovered to the stabilized level as time goes on. To apply the methodology to practical demand forecasts actual surveys of real data of traffic demand should be performed. With these efforts to the patronage ramp-up, more reliable demand analyses can be accompanied.