• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.123-128
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• 2010

This paper analyzes that the global positioning system (GPS) receiver differential code bias (DCB) has effect on the estimation the ionosphere total electron content (TEC). The data from nine permanent GPS sites of the Korea Astronomy and Space Science Institute (KASI) were used for the estimation of the receiver DCB before (Trimble 4000 SSi) and after (Trimble NetRS) the receiver replacement, using the singular value decomposition method. The results showed that the estimated mean value of the receiver DCB varied from 0.11 ns (nanosecond) to 7.54 ns before the receiver replacement, but the receiver DCBs shoed large values than 20 ns except some stations after the replacement. The receiver DCB showed a relatively large difference by types of the receivers, and, as a result, it had a great effect on the estimation the ionosphere TEC using GPS.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.157-160
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• 2006

The Dish/Stirling system with the Stirling engine is currently used to convert solar energy directly to electrical energy successful operation of dish/Stirling system is supported by hybrid system, which will allow continuous operation driven by solar and combustion heat ins. The hybrid Receiver has to be provided with an additional combustion system. The heat pipe receiver and conbustion system were manufactured and tested for thermal characteristics of receiver. Maximum temperature difference along the heat pipe surface is $200^{\circ}C$. Emission measurements showed low NOx values of 28 to 46 ppm and very high CO values of 18 to 201 ppm.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.33-38
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• 2006

The Dish/Stirling system with the Stirling engine is currently used to convert solar energy directly to electrical energy. Successful operation of dish/Stirling system is supported by hybrid system, which will allow continuous operation driven by solar and combustion heating. The hybrid Receiver has to be provided with an additional combustion system. The heat pipe receiver and conbustion system were manufactured and tested for thermal characteristics of receiver. Maximum temperature difference along the heat pipe surface is $200^{\circ}C$. Emission measurements showed low NOx values of 28 to 46 ppm and very high CO values of 18 to 201 ppm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.218-223
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• 2016

This study examined the order of the Butterworth filter for the correlation on the sensitivity of the receiver in the receiver of an optical system. In the general case, the sensitivity of the receiver is increased if the order of the filter was increased more. This is because increasing the order of the filter response of the normalized frequency of the filter is similar to the rectangular wave. For that reason, the method used to increase the order of the filter increases the sensitivity of the receiver. On the other hand, a method of increasing the order of the filter and makes the system complicated increases the cost of the system. This study examined the correlation between the order of the sensitivity of the receiver filter and to configure the system by simply looking for ways to reduce the cost of the system. The simulation results showed that increasing the order of the filter resulted in a receiver that can determine if the sensitivity is raised. In addition, the order of the Butterworth filter range that does not reduce the sensitivity of the receiver was 2. Therefore, it will be possible to implement an inexpensive optical system of the receiver using the data from this study.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.188-193
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• 2010

With GPS being the primary navigation system, Loran use is in steep decline. However, according to the final report of vulnerability assessment of the transportation infrastructure relying on the global positioning system prepared by the John A. Volpe National Transportation Systems Center, there are current attempts to enhance and re-popularize Loran as a GPS backup system through the characteristic of the ground based low frequency navigation system. To advance the Loran system such as Loran-C modernization and eLoran development, research is definitely needed in the field of Loran-C receiver signal processing as well as Loran-C signal design and the technology of a receiver. We have developed a set of Matlab tools, which implement a software Loran-C receiver that performs the receiver's position determination through the following procedure. The procedure consists of receiving the Loran-C signal, cycle selection, calculation of the TDOA and range, and receiver's position determination through the Least Square Method. We experiences the effect of an incorrect cycle selection and various error factors (ECD, ASF, sky wave, CRI, etc.) from the result of the Loran-C signal processing. It is apparent that researches which focus on the elimination and mitigation of various error factors need to be investigated on a software Loran-C receiver. These aspects will be explored in further work through the method such as PLL and Kalman filtering.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.11
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• pp.66-75
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• 1997

We derive the system design parameters to implement the receiving system for the PCS mobile station to satisfy the J-sTD-018 which is the PCS mobile station(MS) minimum performance. Also we analyze the system performance and intermodulation spurious due to the values of a device cause the system performance degradation, is proposed. The simulation shows the receiver's maximum system noise figure to satisfy the receiver selectivity is approximately 11 dB. While the MS noise figure is 10dB with system margin 1 dB, the minimum selectivity is -71 dB at 1.25MHz frequency offset from the carrier frequency. And the input 3rd order intercept point of the MS class I and the MS class II~V is -9.5 dBm and -14dBm respectively. When the interference power level at the receiver is small, the receiver has better performance as we increase the gain of the LNA. However, when the interference level at the receiver is large, the receiver performance is heavily affected by the spurious as we increase the gain of the LNA. Thus, we proved the effectiveness of the LNA On/Off switching technique as to reduce the effect of the spurious.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.15-19
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• 2003

In this paper, the bit error rate (BER) performance of the fast frequency hopping/M-ary frequency shift keying system using the clipper receiver is analyzed by using the characteristic function (CF) technique in the presence of n=1 band multitone jamming and additive white Gaussian noise environment. The CFs of the clipper receiver outputs are derived as a infinite series representation using Gamma function and Marcum's Q -function. The analytical results are validated with various simulation results. Performance comparisons with linear combining receiver are shown that the BER performance of the clipper receiver is much better than that of the linear combining receiver In addition, as the clipping level approaches to infinity, it is shown that the clipper receiver simply performs a linear combining without clipping and there exists an optimum value of diversity level (the number of hops per symbol) that maximizes the worst case BER performance of the clipper receiver.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.13-16
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• 2002

In this paper, we propose adaptive despreading receiver for multi-code PW-CDMA system with binary-level clipping. The distortion due to clipping the multi-level signal causes the performance degradation. Adaptive despreading alleviates the effect of clipping. It is shown that the proposed adaptive despreading receiver achieves smaller BER than conventional despreading receiver for multi-code PW-CDMA system with binary-level clipping.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.7-13
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• 2007

A Dish type solar concentrating system consists of a parabolic concentrator and a cavity receiver. In order to achieve high temperatures from solar energy, it is essential to efficiently reflect the solar rays in the concentrator and to minimize thermal losses in the cavity receiver. Improving the economical efficiency of a solar power system required the stirling unit to be operated continuously. For continuous operation of the stilting unit, the receiver must be continuously provided with thermal energy from solar as well as additional combustion heat. It is possible for a hybrid solar receiver system equipped with an additional combustion to be operated 24 hrs/day. A hybrid solar receiver was designed and manufactured for a total thermal load of 35 kW in the operating temperature range $700^{\circ}C$ to $800^{\circ}C$. The hybrid receiver system was tested in gas-only mode by gas-fired heat to investigate thermal characteristics at inclination angle varying from 0 deg to 30 deg(cavity facing down) and the aperture to cavity diameter ratios of 0(closed cavity) and 1.0(open cavity). This paper has been conducted to measure temperature distribution in cavity surface and to analyze thermal resistances, and the evaporation and condensation heat transfer coefficient in all cases(open and closed cavity).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.10
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• pp.987-993
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• 2013

Chaos communication system has characteristics of non-periodic, non-predictability, broadband signal and easy implementation. Also, chaos communication system is sensitive to the initial value, because completely another signal is generated when initial value of chaos equation is changed subtly. By these characteristics, security of chaos communication system is generally evaluated better than other digital communication systems. However, BER(Bit Error Rate) performance is worse than other digital communication systems, because transmitter and receiver of existing chaos communication system are strongly influenced by reference signal and noise. So, studies in order to improve the BER performance of chaos communication system is continuously performed. In this paper, We will propose a new CDSK (Correlation Delay Shift Keying) receiver in order to improve the BER performance. After we compare to the performance of existing receiver and proposed receiver, BER performance of proposed receiver evaluate. A novel receiver has characteristic that BER performance is better than existing receiver. However, if existing transmitter is used, existing receiver is possible to recover information bits even though BER performance is bad. Therefore, we propose a novel CDSK transmitter in order to improve the security of proposed receiver. When information bits are transmitted by using proposed transmitter, existing receiver is impossible to recover information bits, and proposed receiver is possible to recover information bits.