• Journal of the Korean Operations Research and Management Science Society
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• v.35 no.3
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• pp.45-58
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• 2010

Due to rapid developments of IT technologies, convergence services like IPTV (Internet protocol television) are shown up. Even though expert and customer had great expectations for this innovative service, commercialization was delayed for years by the legal dispute between industry players. One of the biggest problems was that whether internet backbone providers have to share their internet network backbone with IPTV service providers (which don't have network backbone) or not. As other countries, Korean government set the rules that ISP have to offer indiscriminate access to other IPTV service provider. At the same time, internet backbone providers can charge access charge based on cost by way of compensation. Thus access charge is very critical to the IPTV industry players. The objective of this paper is to provide model that can calculate the reasonable access charge by system dynamics, based upon real data in Korean telecommunication industry.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.392-394
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• 1995

The interfacial charge distribution was investigated using PE laminate system. It was found that a proper treatment of the interlace could decrease the amount of charge accumulated at the interfaces. High lamination temperature and long lamination time brought about little interfacial charge. It was also observed that the interfacial charge could be decreased by the addition of chemicals which had charge trap or hopping site.

• Journal of the Korean Ceramic Society
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• v.36 no.12
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• pp.1374-1380
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• 1999

The cause of Scond Harmonic Generation (SHG) in thermally poled silica glass is suggested basedon the electrical and dielectric relaxation measurements. The absorption currents as functions of time were measured for various types of silica glasses and analyzed by the theory of Space Charge Polarization. Space charge polarization occurs when an ionic conducting material is subjected to dc electric field with blocking electrode. Thermal poling performed to induce SHG in silica glass is basically identical to the process generating space charge polarization. Hence it was found that gene-ration removal reproduction and temperature dependence of SHG in poled silica is directly related to those of space charge polarization. It turned out that the fundamental parameters governing the SHG in poled silica are charge carrier concentration and mobility. Based on the theory of space charge polarization and experimental results of electrical rela-xation the method to increase the intensity of SHG is proposed.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.339-345
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• 2016

This paper is concerned with the numerical simulation result of pressure propagation to the main charge by warhead penetration into concrete targets. In this study, we developed on-line pressure measurement method in the main charge during warhead penetration. Using the on-line pressure measurement method, we successfully recorded the pressure-time history in the main charge during the field penetration test. Then we compared result of numerical simulations with test data and found that the simulation results are in good agreement with the test results. Finally, through the numerical calculations it is concluded that the installation of liner is effective in reducing pressure level produced in the main charge.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.5
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• pp.639-645
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• 2013

The aim of the study is to investigate the method to estimate a storage life of propelling charge on the decrease of muzzle velocity by stochastic gamma process model. It is required to establish criterion for state failure to estimate the storage life and it is defined in this paper as a muzzle velocity difference between reference value and maximum allowable standard deviation multiplied by 6. The relationship between storage time and muzzle velocity is investigated by nonlinear regression analysis. The stochastic gamma process model is used to estimated the state distribution and the life distribution for storage time for 155mm propelling charge KM4A2 because the regression analysis is a deterministic method and it can't describe the distribution of life for storage time.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.5-6
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• 2012

In this paper, a simplified maximum power point tracking technique for the solar charger is presented. Main advantages of the proposed charger include low cost and optimized charge time. The maximum power point tracking method is used to deliver the maximum power from PV array to the battery thereby reducing the charge time. Moreover, the proposed technique which tracks the maximum power point by adjusting output current helps reduce the quantity of required number of sensors for the charger. The experimental protype was implemented by using an 80W PV array, a buck converter and a digital signal processor to verify the feasibility of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.10
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• pp.479-485
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• 2001

In this paper, we introduce a charge pump phase-locked loop (PLL) architecture which employs a precharge phase frequency detector (PFD) and a sequential PFD to achieve a high frequency operation and a fast acquisition. Operation frequency is increased by using the precharge PFD when the phase difference is within $-{\pi}{\sim}{\pi}$ and acquisition time is shortened by using the sequential PFD and the increased charge pump current when the phase difference is larger than ${\pm}{\pi}$. So error detection range of the proposed PLL structure is not limited to $-{\pi}{\sim}{\pi}$ and a high frequency operation and a higher speed lock-up time can be achieved. The proposed PLL was designed using 1.5 ${\mu}m$ CMOS technology with 5V supply voltage to verify the lock in process. The proposed PLL shows successful acquisition for 200 MHz input frequency. On the other hand, the conventional PLL with the sequential PFD cannot operate at up to 160MHz. Moreover, the lock-up time is drastically reduced from 7.0 ${\mu}s\;to\;2.0\;{\mu}s$ only if the loop bandwidth to input frequency ratio is regulated by the divide-by-4 counter during the acquisition process. By virtue of this dual PFDs, the proposed PLL structure can improve the trade-off between acquisition behavior and locked behavior.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.13-15
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• 2008

Charging or discharging secondary batteries such as a lithium-ion battery is essential in the stage of production and takes long time over two hours. And the charge/discharge system is operated with high switching frequency over several tens kHz. Therefore, to simulate such a system in the conventional way takes very long time and huge files are produced. Finally, the simulation would be unable with general PC class. In this paper, the lithium-ion battery charge/discharge system is analyzed by using state space averaging method. As a result, the simulation time is reduced dramatically and the charge/- discharge characteristics of the lithium-ion battery can be observed.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3359-3366
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• 2023

In this study, a spiking cortical model (SCM) based n-g discrimination method is proposed. The SCM-based algorithm is compared with three other methods, namely: (i) the pulse-coupled neural network (PCNN), (ii) the charge comparison, and (iii) the zero-crossing. The objective evaluation criteria used for the comparison are the FoM-value and the time consumption of discrimination. Experimental results demonstrated that our proposed method outperforms the other methods significantly with the highest FoM-value. Specifically, the proposed method exhibits a 34.81% improvement compared with the PCNN, a 50.29% improvement compared with the charge comparison, and a 110.02% improvement compared with the zero-crossing. Additionally, the proposed method features the second-fastest discrimination time, where it is 75.67% faster than the PCNN, 70.65% faster than the charge comparison and 38.4% slower than the zero-crossing. Our study also discusses the role and change pattern of each parameter of the SCM to guide the selection process. It concludes that the SCM's outstanding ability to recognize the dynamic information in the pulse signal, improved accuracy when compared to the PCNN, and better computational complexity enables the SCM to exhibit excellent n-γ discrimination performance while consuming less time.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.133-138
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• 2017

This paper presents a jitter characteristic improved phase locked loop (PLL) with an RC time constant circuit. In the RC time constant circuit, LPF's voltage is inputted to a comparator through small and large RC time constant circuits. The signal through a small RC time constant circuit has almost same loop filter output voltage. The signal through a large RC time constant circuit has the average value of loop filter output voltage and does as a role of reference voltage to the comparator. The output of the comparator controls the sub-charge pump which provide a current to LPF. When the loop filter output voltage increases, the sub-charge pump discharges the loop filter and decreases loop filter output voltage. When the loop filter output voltage decreases, the sub-charge pump charges the loop filter and increases loop filter output voltage. The negative feedback loop reduces the variation of loop filter output voltage resulting in jitter characteristic improvement.