• Korean Journal of Materials Research
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• v.21 no.5
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• pp.243-249
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• 2011

To reduce manufacturing costs of crystalline silicon solar cells, silicon wafers have become thinner. In relation to this, the properties of the aluminium-back surface field (Al-BSF) are considered an important factor in solar cell performance. Generally, screen-printing and a rapid thermal process (RTP) are utilized together to form the Al-BSF. This study evaluates Al-BSF formation on a (111) textured back surface compared with a (100) flat back surface with variation of ramp up rates from 18 to $89^{\circ}C$/s for the RTP annealing conditions. To make different back surface morphologies, one side texturing using a silicon nitride film and double side texturing were carried out. After aluminium screen-printing, Al-BSF formed according to the RTP annealing conditions. A metal etching process in hydrochloric acid solution was carried out to assess the quality of Al-BSF. Saturation currents were calculated by using quasi-steady-state photoconductance. The surface morphologies observed by scanning electron microscopy and a non-contacting optical profiler. Also, sheet resistances and bulk carrier concentration were measured by a 4-point probe and hall measurement system. From the results, a faster ramp up during Al-BSF formation yielded better quality than a slower ramp up process due to temperature uniformity of silicon and the aluminium surface. Also, in the Al-BSF formation process, the (111) textured back surface is significantly affected by the ramp up rates compared with the (100) flat back surface.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.254-259
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• 2014

In this paper, we describe construction of a wind stabilization demo-site and effects of output power control of wind turbines for suppression of ramp rate using ESS (Energy Storage System). It is difficult to control the output power of distributed generator such as wind turbine which of variation is very large. If the large capacity wind farm be interconnected into power system may cause blackout due to Power Quality. For these reasons, the international standards such as Grid-Code is limited to less than 10 [%/min] of renewable energy ramp rate. The case of Korea, government actively conducts propagating large-scale renewable energy for green growth policy, to interconnecting more renewable energy into power system is necessary for stabilization technology. For these reasons, the POSCO consortium has constructed a wind stabilization demo-site that is configured as 500 [kWh] battery energy storage systems can output up to 3 [C-Rate] and two wind turbines rated 750 [kW]. In POSCO consortium, which implements various methods stabilizing output power of wind turbine such as smoothing, section firming and ramp control, we derive the results of long-term demonstration that can be controlled to satisfy to the international standard about ramp rate [%/kW] of wind turbine output power.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.579-585
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• 2009

In spite of the proven effectiveness of ramp metering system, it has not been successfully implemented in Korean setting. The purpose of this paper is to select target locations to introduce ramp metering into the Korean expressway system. For this, domestic standards to introduce ramp metering have been presented after reviewing those of the US. The major criteria are level of service (LOS), the existence of detour route, space for queue build-up and opened ramp. 15 different locations were selected and AHP has been used to make priority among them. Intuitively, the result of priority was in accordance with the congestion and traffic volume. The core results identified in this paper is expected to be used in different cities and expressway networks elsewhere.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.57-60
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• 2002

This paper deals with the effect of ramp-type erase pulse waveform on the high temperature driving characteristics of ac PDP driven by ramp up-down reset waveform. The experimental results show that the discharge characteristics in the reset period are significantly affected by the erase pulse waveform and ambient temperature. The firing voltage is increased with ambient temperature. This can cause misfirings during the sustain period and should be avoided. As one of possible solutions, we propose the optimization of erasing pulse shape.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1636-1639
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• 2002

We proposed the new reset waveform for reducing reset period. The square pulse is applied to the address electrode when the ramp pulse increases before a discharge occurs between sustain electrodes. If the discharge occurs between address electrode and X electrode, the wall charge is reversely accumulated between sustain electrodes compared with the applying voltage before the discharge occurs between sustain electrodes. So the next discharge more weakly occurs between sustain electrodes. If the more weak discharge is obtained, it can make the low background luminance and the high contrast ratio and reduce ramp up time in the ramp reset waveform.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.17-17
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• 2000

The issue of reflow profiling continues to be a complex topic. The pains often associated with profiling can be reduced greatly if certain guidelines are followed and if there is a strong understanding of the variables that can be encountered during the reflow process. This paper shall discuss the appropriate guidelines and trouble shooting methods for reflow profiling, and in particular shall focus upon the benefits of implementing the linear ramp-to-spike profile. Delta T(T) is defined as the variation of temperature found on an assembly during the reflow process. Too large of a T can result in soldering defects, so to combat T a Ramp-Soak-Spike(RSS) reflow profile often is utilized. However, when using a newer-style reflow oven, the T often is minimized or eliminated, thus, the soak zone of the reflow profile becomes an unnecessary step. Because of this, the implementation of a linear Ramp-To-Spike(RTS) reflow profile should be considered. Benefits such as reduced energy costs, reduced solder defects, increased efficiency, improved wetting, and a simplification of the reflow profile process may be experienced when using the RTS profile. Included in this paper are the suggested process parameters for setting up the RSS and RTS profiles and the chemical and metallurgical reactions that occur at each set point of these profiles. The paper concludes with a discussion and pictures of several profile-related defects. Each of these defects is described, analyzed, and instructions are given for troublshooting these defects.

• Wind and Structures
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• v.30 no.4
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• pp.393-403
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• 2020

One of the growing concerns of the wind energy production is wind ramp events. To improve the wind ramp event forecasts, the nonlinear Kalman filter bias correction method was applied to 24-h wind speed forecasts issued from the WRF model at 70-m height in Zhangbei wind farm, Hebei Province, China for a two-year period. The Kalman filter shows the remarkable ability of improving forecast skill for real-time wind speed forecasts by decreasing RMSE by 32% from 3.26 m s_-1 to 2.21 m s_-1, reducing BIAS almost to zero, and improving correlation from 0.58 to 0.82. The bias correction improves the forecast skill especially in wind speed intervals sensitive to wind power prediction. The fact shows that the Kalman filter is especially suitable for wind power prediction. Moreover, the bias correction method performs well under abrupt weather transition. As to the overall performance for improving the forecast skill of ramp events, the Kalman filter shows noticeable improvements based on POD and TSS. The bias correction increases the POD score of up-ramps from 0.27 to 0.39 and from 0.26 to 0.38 for down-ramps. After bias correction, the TSS score is significantly promoted from 0.12 to 0.26 for up-ramps and from 0.13 to 0.25 for down-ramps.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.2
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• pp.107-112
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• 2016

The purpose of this study was to determine the effect of aquatic ramp walking exercise on the activity of the quadriceps, gait and activity of daily living in child with Spinal Muscular Atrophy (SMA) type II. A 5 years-old girl with SMA type II participated in this study. This study used single-subject reverse(A-B-A) design study. There are 12 sessions(4weeks 3 times a week) each during the baseline phase(A), the intervention phase(B), the follow up phase(A). During the baseline phase and the follow up phase performed general aquatic therapy, the intervention phase additional performed walking activity on ramp in pool (60m). Surface electromyogram, Timed Up and Go (TUG) test, ACTIVLIM were used as outcome. During the intervention phase, there were decrease on the activity of the quadriceps. In modified TUG test, gait time reduced during the intervention phase. The ACTIVLIM logit score increased during intervention phase by comparison with the baseline phase. These findings suggest that an aquatic ramp walking exercise activities have the therapeutic possibility on the quadriceps activity and gait ability for child with SMA type II.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.69-72
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• 1999

During the fast current and field ramp up experiment with CICC (Cable-In-Conduit Conductor) non-insulated 3 strand superconducting magnet, the unbalanced current distribution associated with the loop current has been obtained directly from the shunt resistor voltage data. To explain the generation of the loop current during the current ramp up, the steady-state three strand loop current model was proposed. This model gives an explanation for the relation between the loop current and the relation between the loop current and the twist geometry of the strands. According to this model, the twist geometry of the strand has significant influence on the generation of the loop current especially in the large superconducting magnet.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.10
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• pp.458-463
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• 2006

The purpose of this work is to investigate the fundamental properties of the gradual muscle force potentiation. We investigated the dependence of force potentiation on both the pulse-amplitude and the pulse-duration with different ramp-up time. The experimental results showed that the force increment ratio (FIR) during constant electrical stimulation decreased with pulse-amplitude and also with pulse-duration. The FIR was greater with short ramp-up time in both the pulse-amplitude and pulse-width modulation. The feasible mechanism might be that the myosin light chain phosphorylation induces the force potentiation and it occurs only in the fast type muscle fibers which are recruited first. These observations indicate that muscle potentiation must be understood well for the accurate control of muscle force.