• Journal of Auto-vehicle Safety Association
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• v.7 no.4
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• pp.26-30
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• 2015

Exceeding the speed limit during vehicle driving is a key factor in the severity of lots of road accidents, and SLIF(Speed Limit Information Function) application is in the initial phase in Korea. SLIF helps the drivers to observe a speed limit when they are driving by providing alert and informing the current limit speed information based on external data using camera and/or digital map, for that reason, environmental conditions could be causes of SLIF malfunctions. In this study, design adequacy analysis of SLIF in respect of false recognition as the Korea traffic environment has been performed. As tentative results, road conditions and structure of speed limit sign as well as system performance often caused misrecognition.

• Structural Engineering and Mechanics
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• v.50 no.2
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• pp.201-214
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• 2014

Due to the confinement effects, Steel-Straps Tensioning Technique (SSTT) can significantly enhance the strength and ductility of high-strength concrete (HSC) members (Moghaddam et al. 2008). However, the enhancement especially in strength may result in slender member and more susceptible to instability (Jiang and Teng 2012a). This instability is particularly significant in HSC member as it inherent the brittle nature of the material (Galano et al. 2008). The current slenderness limit expression used in the design is mainly derived from the experiment and analysis results based on Normal strength concrete (NSC) column and therefore the direct application of these slenderness limit expressions to the HSC column is being questioned. Besides, a particular slenderness limit for the SSTT-confined HSC column which incorporated the pre-tensioned force and multilayers effects is not yet available. Hence, an analytical study was carried out in the view of developing a simple equation in order to determine the slenderness limit for HSC column confined with SSTT. Based on the analytical results, it was concluded that the existing slenderness limit expressions used in the design are appropriate for neither HSC columns nor SSTT-confined HSC columns. In this paper, a slenderness limit expression which has incorporated the SSTT-confinement effects is proposed. The proposed expression can also be applied to unconfined HSC columns.

• Korean System Dynamics Review
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• v.10 no.3
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• pp.47-79
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• 2009

The paper examines dynamic relationship among 'Limit to Growth' factors in Korea using causal loop diagram. It also aims to explore policy implications for Korea in overcoming current difficulties and future crisis we may face. For this purpose, five factors -economy, population, resource, environment, food- used in the were adopted as an analytical framework. Findings show that Korea is fragile to external shock such as world economic crisis, food price surge, and resource price -including energy price- hike. High dependency of energy, food and resource on foreign market was found to be a major source of limit to growth in Korea. Furthermore, environmental problems like global warming could be a major external shock that could hit Korea harder than the rest of the world. Policy implications and measures for these problems were discussed too.

• Transactions of Materials Processing
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• v.24 no.5
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• pp.361-367
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• 2015

The forming limit diagram (FLD) is the most commonly used tool for evaluating of sheet metal formability in the manufacturing field as well as the finite element analysis (FEA)-based design process. Determination of the forming limits is considerably influenced by testing/measuring machines, techniques and conditions. These influences may cause a large scatter in FLD from laboratory to laboratory. Scatter is especially true when the ‘position-dependent method’, as is specified in most national and international standards, is used. In the current study a new ‘time-dependent method’ is proposed, which is to determine the forming limit strains more accurately and reasonably when producing a FLD from experimental data. This method is based on continual strain measurement during the test. The results are compared to those from the existing standardized methods.

• Transactions of Materials Processing
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• v.22 no.6
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• pp.328-333
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• 2013

The current study aims to determine the limit strains more accurately and reasonably when producing a forming limit curve (FLC) from experiments. The international standard ISO 12004-2 in its recent version (2008) states that the limit major strain should be determined by using the best-fit inverse second-order parabola through the experimental strain distribution. However, in cases where fracture does not occur at the center of the specimen, due to insufficient lubrication, the inverse parabola does not give a realistic fit because of its intrinsic symmetry in shape. In this study it is demonstrated that an inverse quartic function can give a much better fit than an inverse parabola in almost all FLC test samples showing asymmetric strain distributions. Using a quartic fit creates more reliable FLCs.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.2
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• pp.83-89
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• 2001

This paper introduces a power flow model of SSSC for voltage stability analysis of power system installed with Static Synchronous Compensators. The SSSC model is obtained from the injection model of voltage source inverter by adding the condition that SSSC injection voltage is in quadrature with current of SSSC-installed branch. This model is incorporated into modified CPF algorithm to study effects of SSSC on the security-constrained interface flow limit. Determination of interface flow limit is simply briefed. In case study a 771-bus real system is used to show that interface flow limit can be improved by appropriate control of SSSC in terms of voltage stability.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.680-683
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• 2005

This paper proposes a simple MPPT control scheme of a Current-Control-Loop Error system Based that can be obtains a lot of advantage to compare with another digital control method, P&O and IncCond algorithm that is applied mostly a PV system. An existent method is needed an expensive processor such as DSP that calculated to change the measure power of a using current and voltage sensor at the once. Therefore, it is applied a small home power generation system that required many expenses. But, a proposed method is easy to solve the cost reduction and power unbalance problems that it is used by control scheme to limit error of a current control of common sensor. This proposed algorithm had verified through a simulation and an experiment on battery charger using PIC that is the microprocessor of a low price.

• Journal of Environmental Impact Assessment
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• v.5 no.1
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• pp.15-29
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• 1996

Composting is very important in practicing environmentally sustainable agriculture because compost application conserve soil and its fertility. Composting is also another important factor in achieving high national recycling goal above 20%. To encourage composting, it is necessary to revise current regulations on composting. Current regulation set the limit only for 4 metals and the limit is significantly strict, especially for lead, which dictates less than 150ppm. In this paper, authors suggested reasonable standard for some heavy metal concentration in compost taking into account other country's criteria.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.456-458
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• 1997

The phase-lock technique is applied to a three-phase semi-bridge type battery charger system. Using an inner fast dynamic loop, the phase-locked voltage control (PLVC) technique of three-phase semi-bridge converter is proposed to give a frequency synchronism and to reduce the subharmonics due to the unbalance of transformer or power line. To protect the power devices, the two stage soft-start, function with softly locking the phase and softly increasing the current is presented. As limiting the reference voltage of the inner voltage control loop, muti-lock phenomena are removed on the PLVC loop. A current limit function is also proposed to limit the current of battery and converter. The proposed controller is confirmed through experiment results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.8-17
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• 2008

This paper presents a stable lighting method for HID lamp for ship from initial discharging current limit with discharging voltage control. The output voltage of the proposed control scheme is boosted for ignition, and the charging voltage is decreased by the resistor discharging. The proposed controller fires the initial discharge at the designed discharging voltage to limit the discharge current. After the discharging, constant current controller is used for brightness in steady state. The proposed control scheme can limit the initial discharge current using the starting point control without a complex voltage controller. so it can improve the life-time of HID lamp and get a stable discharge from restricted the initial discharge current. In order to improve the protection of the system, a simple instantaneous error detecting circuit for open state and short state of HID lamp is used. The proposed error detecting of HID lamp can protect the power system of lamp control. The effectiveness of the proposed controller is verified from the experiments of practical 2.5[kW] HID search light for ship.