• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.630-643
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• 2001

In this paper, the performance of a Multi-Carrier DS-CDMA system with Hybrid $SC/MRC- L_{c}/L$ diversity in the multipath Rayleigh fading environment is analyzed and compared with that of a Wideband DS-CDMA system. Each carriers of the number of the input diversity branches in the Multi-Carrier DS-CDMA system is L and among L, the branches of $L_c$ are chosen to be maximum-ratio-combined. And the diversity outputs are coherent-detected and despread by the correlator of each carrier. As the result, we have known that the structure of the Wideband DS-CDMA system with Hybrid $SC/MRC-L_{c}/L$ diversity reception becomes simple due to no synchronization of bit or phase and in terms of the error performance, the performance of Hybrid $SC/MRC- L_{c}/L$ diversity is better than that of selection diversity, but worse than that of MRC diversity. Moreover, the performance of a Multi-Carrier DS-CDMA system is better than that of a Wideband DS-CDMA system in multipath Rayleigh fading channel since Hybrid $SC/MRC- L_c/L$ diversity can obtain gain from each diversity branch. In case four carriers are used and required BER is $10^{-6}$ in wireless data communication, Hybrid SC/MRC-2/4 diversity can increase more 17 users than Hybrid SC/MRC-2/3 diversity because the better input branches can be selected through increase of input branches.

• Journal of agriculture & life science
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• v.43 no.5
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• pp.9-15
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• 2009

The purpose of this study was to find out the optimum SMP carriers in seeds of 12 pepper cultivars to alternate Micro-eel E. It showed that calcium carbonate caused the lower germination rates in proportion of water volumes and the radicle protrusion during priming period. Micro-cel E induced also the radical protrusion, even though it shortened $T_{50}$ in Wang cultivar, in proportion of water volumes. Diatomaceous earth shortened both $T_{50}$ and Mean days germination(MDG) in Choyang and Hyangchon cultivars, although it caused the radicle protrusion in treatment of $1.5{\times}$ water proportion. In Wang cultivar, Diatomaceous earth shortened $T_{50}$ by 0.60 and 0.05 days at 1.0 and $1.5{\times}$ water proportions respectively compared to the Micro-cel E at 5.0 and $7.0{\times}$ water proportions. Therefore, it could be suggested that Diatomaceous earth for the carrier might be suitable in pepper cultivars to alternate Micro-cel E, and $1.0{\times}$ water proportion should be available for processing.

• The Korean Journal of Mycology
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• v.42 no.4
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• pp.328-332
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• 2014

For mass production of entomopathogenic fungus Beauveria bassiana 149, isolated from moth larva, by two-phase fermentation, we performed selection of carbon and nitrogen sources for liquid culture and examined solid fermentation on carrier, ingredient, temperature, and water content. Spore production with rice powder, corn powder, and starch from sweet potato was higher than that of sucrose and dissolvable starch for liquid fermentation as first-phase fermentation. As a nitrogen source, addition of peptone and yeast powder showed higher spore production than $NaNO_3$, fish powder, and soybean powder. The isolate produced more conidia in sawdust + wheat bran + corn powder, sawdust + wheat bran and rice shell + wheat bran as carrier and ingredient than vermiculite as carrier. Conidia production of B. bassiana 149 in solid-phase fermentation was twice higher at 30 than 20. Conidia yield was higher at 60% and 70% water content ($26.9{\times}10^8$ and $38.6{\times}10^8conidia/g$) than 40% and 50% ($13.9{times}10^8 $and $11.6{\times}10^8conidia/g$), respectively.

• Electronics and Telecommunications Trends
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• v.18 no.3 s.81
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• pp.67-74
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• 2003

최근 국내에서는 후발사업자에 의해 시내전화 사업자가전선택제가 유선전화 시장개방 수단으로 제기되고 있다. 일본의 경우 2001년 5월부터 시내전화, 장거리전화, 국제전화 부분에서 사업자사전선택제를 도입하여 시행하고 있다. 이 제도의 도입으로 지배적 사업자인 동서 NTT의 시장 지배력은 약화되어 갔다. 뿐만 아니라 지나친 요금경쟁과 과대한 판매촉진 비용으로 신규기업들도 경상이익이 적자로 전화되었다.

• Electronics and Telecommunications Trends
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• v.19 no.4 s.88
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• pp.127-134
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• 2004

OFTEL은 1998년 7월 유럽위원회(EC)의 수정상호접속지침(amended ICD, 97/33/EC)에 의거 유선망의 지배적사업자인 BT, 그리고 Kingston Communications사를 제공의무사업자로 결정하고 사업자사전선택제를 도입하기로 결정하여, 2000년 4월부터 임시적 사업자사전선택제를 도입한 후 단계적으로 유선시장 전화서비스에 대해 multi-basket 유형으로 사업자사전선택제를 시행하고 있으며, 사업자들은 수시영업(marketing) 방식으로 가입자를 확보하고 있다.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.138-147
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• 1995

The conventional PWM method, which was used in controlling the on-off valve, such as high-speed solenoid valve, was modulating the width of the pulse applied to the valve, by selecting arbitrary sampling time and modulating the duty-ratio in proportion to the error. However, in this method, a selection of long sampling time was inevitable and it was unable to get a high accuracy and a quick response. This study is for designing an appropriate controller for high-speed solenoid valve by proposing an improved duty-ratio modulation method using the Saw-toothed Carrier Wave which enables a short sampling time selection, high accuracy of control, and a quick response. Test which was carried out in the laboratory shows that transient and steady state response could be improved by PID controller.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.662-666
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• 2002

Carrier Pre-Selection (CPS) was introduced to Japan in May 1, 2001. CPS reduced telephone charges from minimum of 3.4% to maximum of 12%. But due to competitive marketing by telecommunication companies like NTT, KDDI and Japan Telecom, resulted reduction of revenue.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.57-62
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• 2020

The millimeter wave that uses the spectrum in the 30GHz~300GHz band has a shorter wavelength due to its high carrier frequency, so it is suitable for Massive MIMO systems because more antennas can be equipped in the base station. However, since an RF chain is required per antenna, hardware cost and power consumption increase as the number of antennas increases. Therefore, in this paper, we investigate antenna selection schemes to solve this problem. In order to solve the problem of high computational complexity in the exhaustive search based antenna selection scheme, we propose a approach of applying deep learning technology. An best antenna combination is predicted using a DNN model capable of classifying multi-classes. By simulation tests, we compare and evaluate the existing antenna selection schemes and the proposed deep learning-based antenna selection scheme.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.909-914
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• 2005

This paper proposes an efficient antenna selection scheme for PRT (Personal Rapid Transit) remote control in a wireless MIMO-OFDM systems. Using high correlation among neighboring sub-carriers, transmit antennas are selected by calculation based on the channel response of the center sub-carrier in each subgroup. This scheme reduces complexity of selection algorithm and significantly reduces the feedback channel information with small performance degradation. Especially, when feedback channel rate between a control base and a train is fixed, the proposed scheme can provide a significant advantage in high mobility.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.120-125
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• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.