• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.665-680
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• 1997

The specific absorption rate (SAR) distributions in various models of the human head have been analyzed when the models are exposed to 350 MHz and 900 MHz plane waves. The numerical analysis is performed with the finite-difference time-domain (FDTD) method. A homogeneous sphere including a cylinderical neck, a homogeneous head shaped model, and a heterogeneous realistic model are used as models of human head. The incident plane wave used for these calculations is propagating from the front to the back or from the back to the front of the head model, with its E-field vector orientation being parallel to the major length of the body. The specific findings are: 1) the average SARs of the three models are similar mutually but the local SARs of them differ greatly mutually; 2) the power is deposed more deeply in the head at 350 MHz, which is roughly the resonant frequency of a human head, than at 900 MHz; 3) for a plane wave propagating from the back, "hot spot" is found in the neck region, not in the head; 4) for a plane wave propagating from the front, "hot spot" is found in the nose at 900 MHz, and in the upper part of the lip and the jaw region at 350 MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.131-139
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• 2011

In this paper, we propose a double-faced window printed antenna for aircraft applications. The proposed antenna structure consists of a feeding line and a multi-loop radiator located on different sides of the window to use the limited given-area effectively. The proposed antenna is optimized by the genetic algorithm in conjunction with the FEKO EM simulator. The optimized antenna is built and installed on a 1/10 sized KUH-Surion mock-up and antenna performances such as the reflection coefficient and the radiation patterns are measured. The optimized antenna shows a half power matching bandwidth of about 33 % at 60 MHz and an average bore-sight gain of about -3.49 dBi. To verify the reception capability of the optimized antenna, we simulated the received power according to a flight scenario. The result confirms that the optimized antenna shows a minimum received power level above -60 dBm at a range of 200 km, which is similar to the pole antenna that is currently used as a FM voice antenna for KUH-Surion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2433-2442
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• 2014

In this paper, an efficiency grade standard for imaging equipments using electrophotograph printing such as a printer, copier, fax, and MFD (Multi Function Device) is studied. By emphasizing domestic standby power reduction program's problem, and proposing the necessity of efficiency management, the efficiency standard is developed by reliable data registered in domestic standby power reducing program. To find an efficiency indication for grade, correlation analysis is used and as a result, printing speed has the biggest correlation coefficient. By applying the efficiency indication for grade, the proposed certification standard is established in 1st to 5th level products and super-high-efficiency product (energy frontier) which is better than 1st to 5th level products. If these efficiency standards are chosen by government policies, it is expected to save 65 billion won reduction of energy cost per year.

• Journal of IKEEE
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• v.25 no.4
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• pp.716-720
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• 2021

In this study, we examine the availability of a cooling patch to enhance the output power of a hybrid energy device (HED) comprising a photovoltaic cell (PVC) and a thermoelectric generator (TEG). The cooling patch attached on the back of the TEG drops the temperature of the PVC via the TEG and makes a large thermal gradient across the TEG under irradiances in a range of 200 to 1000 W/m². The cooling patch is more effective for the output power of the HED as the irradiance increases, and it enhances the maximum output power of the HED to 42.1 mW at an irradiance of 1000 W/m². The increment in the maximum output power reaches 27% owing to the attachment of the cooling patch that does not consume any power.

• Journal of the Korea Society of Computer and Information
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• v.27 no.7
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• pp.9-16
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• 2022

Today, with the advent of the 4th industrial revolution, IoT (Internet of Things) systems are advancing rapidly. For this reason, a various application with high-performance and large-capacity are emerging. Therefore, there is a need for low-power and high-performance memory for computing systems with these applications. In this paper, we propose an effective structure for the L1 cache memory, which consumes the most energy in the computing system. The proposed cache system is largely composed of two parts, the L1 main cache and the buffer cache. The main cache is 2 banks, and each bank consists of a 2-way set association. When the L1 cache hits, the data is copied into buffer cache according to the proposed algorithm. According to simulation, the proposed L1 cache system improved the performance of energy delay products by about 65% compared to the existing 4-way set associative cache memory.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.94-101
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• 2007

This paper, we analyzed that the measured data of the radiated power spectrum of electromagnetic waves and the standing wave ratio(SWR) of the spark plug cable and spark plug. The measured data are the power strength of the electromagnetic waves radiated from the spark ignition system, the measured frequency ranges are 110 to 610MHz. The results show that the strength of radiated power spectrum and bandwidth have relation to the SWR of the the spark plug cable and spark plug, and the SWR of them is different because of the characteristics of resistor at the spark plug is different with the manufacturers. From the analyzed results, it can be concluded that the less SWR is little, the less maximum level of power spectrum is weak and bandwidth above the reference level is small.

• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.459-473
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• 1998

As the satellite system becomes more complex, the probability of unpredictable failures may be increased due to design inadequacy, experience deficiency, lack of problem recognition. Poor quality control, improper testing, and workmanship fault. Consequently, these problems can lead to the reduction or end of the satellite mission lifetime. This article addresses general satellite failure modes and factors influencing satellite mission life. The mission life factors of LEO sun-synchronous KOMPSAT spacecraft are investigated, in which its mission life is predicted based on these factors. Since the end of mission due to random failures is not predictable, the predictable mission life factors such as power budget, propellant budget, battery charging/discharging cycle, radiation effects payload reliability, single point failure, and redundancy are primarily investigated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1131-1140
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• 2004

In this paper, we proposed a flate-plate antenna employing semi-annular slots for satellite broadcast reception. The radiating element of the antenna is dual annular slots fed by a strip dipole, which have a wider bandwidth than the rectangular slot. A $16{\times}16$ array antenna is designed using stripline T-junction power dividers. Measurements of the fabricated antenna show a gain of 28.0$\~$29.5 dB in 11.7$\~$12.8 GHz frequency range.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.807-811
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• 2001

In this paper we proposed a dual-frequency circular sector microstrip antenna with orthogonal polarized modes and high isolation between the two feeding ports. And then we designed a transceiver operating at 5.6 GHz for transmitting and at 5.5 GHz for receiving. The good isolation provided by the proposed antenna is used as the basis for the transmit-receive filtering of transceiver. The operating frequencies and polarization characteristics of the proposed antenna is calculated by using a cavity model. The 5-parameters and radiation patterns of the antenna are measured. A power amplifier and a low noise amplifier are designed and integrated with antenna to make a transceiver, which has about 13dB transmitting gain and about 8㏈ receiving gain.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.427-432
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• 2020

In this study, a multi-zone furnace analysis method that couples a 1D energy and mass balance calculation with a 3D radiative heat transfer calculation is tested in order to verify its reliability. The calculated results for a domestic 500 MW capacity coal-fired boiler furnace were compared with the design data of the boiler manufacturer and CFD analysis, and a good agreement was achieved. Although this calculation method is less sophisticated than the CFD furnace analysis, it has an advantage in terms of calculation time while being able to provide the furnace behavior according to the fuel characteristics and operational variable changes. Therefore, it is expected to be useful for boiler operation diagnosis and daily fuel/operation planning.