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Rene 80/B/Rene 80 액상 확산접합부의 기계적 성질
정재필,강춘식 대한용접접합학회 1995 대한용접·접합학회지 Vol.13 No.3
Rene80 superalloy was liquid phase diffusion bonded by using pure boron (B) as an insert material. As a basic study for the possibility of practical application of this bonding method, hardness and high temperature tensile strength of the bonded joint and metallurgical analysis were investigated. As experimental results, hardness of the bonded joint was homogenized after bonding and the tensile strength at 1144K was obtained to 90% of that of base metal. But there were some problems to be improved also, that means the joint was hardened after bonding due to increase of B content and elongation was much lower than that of base metal. Flat area and (Mo, Cr, W) boride, which should be harmful for bonding strength, were observed on the fractured surface of the tensile tested specimen.
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주파수 오프셋을 고려한 OFDM/M-ary PSK 시스템의 성능 분석
정재필 京畿專門大學 2001 京畿專門大學 論文集 Vol.- No.29
In this thesis, it is analyzed theoretically that the performance degradation, caused by carrier frequency offset, in an OFDM/ M-ary PSK system. As results of analysis, it is shown that the more the number of M-ary is, the worse the BER performance is. Moreover, 7dB, 9dB, and 17dB of Eb/No are required in QPSK, 8PSK and 16PSK systems, respectively, in order to satisfy the error performance, BER= 10^(-3), for voice communication.
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정재필,김인재 한국정보기술학회 2012 한국정보기술학회논문지 Vol. No.
This paper investigates the performance of Turbo equalization in wireless multipath fading channels. Turbo equalization mainly consists of a SISO(soft-in soft-out) equalizer and a SISO decoder. Iterative channel estimators can improve the accuracy of channel estimates by soft information fed back from the SISO decoder. Comparing iterative channel estimators with LMS(least mean square) and RLS(recursive least squares) algorithms, which are the most common algorithms to estimate and track a time-varying channel impulse response, the iterative channel estimator with RLS converges more faster than the one with LMS. However, the difference of BER(bit error rate) performances gradually decreases as the number of iterations for Turbo equalization increases. 무선 통신시스템에서 널리 사용되는 적응 등화기(adaptive equalizer) 등은 통신 채널에서 ISI영향을 줄이기 위해서는 반드시 필요하다. 따라서 본 논문에서는 무선 다중경로 페이딩 채널에서 터보 등화기(turbo equalizer)를 사용한 시스템의 성능을 분석하였다. 터보 등화기는 크게 SISO(soft-in soft-out) 등화기와 SISO 복호기로 구성이 되는데, 반복 채널 추정기(channel estimator)는 SISO 복호기로부터 얻은 소프트 정보를 사용함으로써 채널 추정치의 정확도를 향상시킬 수 있다. 시변 채널 임펄스 응답을 추정하고 추적하는 대표적인 알고리듬인 LMS(least mean square)와 RLS(recursive least square)를 반복 채널 추정기에 적용하여 성능을 해석한 결과, RLS 알고리즘을 이용하는 터보 등화기가 LMS 알고리즘을 이용하는 터보 등화기 보다 성능이 우수하지만 반복회수가 증가함에 따라 BER(bite error rate) 성능 차이는 감소함을 알 수 있었다.
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Effect of Diniconazole Treatments on Growth of Plug Seedlings in Melon (Cucumis melo L.)
정재필,배창휴 한국자원식물학회 2024 한국자원식물학회지 Vol.37 No.6
Abstract - In order to promote healthy seedlings, foliar spraying of triazole-based diniconazole is mainly used in nurseries. As the inhibitory effect of foliar spraying weakens, plant growth inhibitors are sprayed several times for prevention of over-growth and healthy seedling in some varieties, so the foliar spraying method causes fatal damage to the growing point of the plants. To solve the problem of the foliar spraying treatment, the effects between the foliar spraying and the irrigation with drenching methods on the growth inhibition of plug seedlings were evaluated using diniconazole treatments in melon (Cucumis melo L. var. ‘Ochigi’). As a result of the experiments, plant height, hypocotyl length, leaf length and width of all the melon seedlings were decreased significantly as the treatment concentration of diniconazole increased. In particular, compared to the foliar spraying, the inhibiting effect of the irrigation treatment on seedling growth was maintained until the shipment time of plug seedlings. Thus, the irrigation treatment was more effective than the foliar spraying to yield healthy seedlings. The result be able to be used as fundamental data for yielding healthy seedlings of gourd crops.
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페이딩 채널 환경에서 MC-CDMA/QPSK 시스템의 성능분석
정재필 京畿專門大學 1999 京畿專門大學 論文集 Vol.- No.27
This paper has analyzed the Error performance of MC-CDMA/QPSK system adopting error control coding and diversity reception techniques in fading channel Environment. Also, this paper has compared the Error performance of MC-CDMA/QPSK system with that of DS-CDMA/QPSK system. From the obtained results it is found that the Error performance of MC-CD77A/QPSK system has been improved considerably by convolutional coding and MRC diversity reception techniques. Also, it is confirmed that MC-CDMA/QPSK system produces better Error performance than DS-CDMA/QPSK system in fading channel Environment as the number of users increases.
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