• 대한수학회지
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• 제50권5호
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• pp.1051-1066
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• 2013

By utilizing known characterizations of ${\omega}$-Noetherian rings in terms of injective modules, we give more characterizations of ${\omega}$-Noetherian rings. More precisely, we show that a commutative ring R is ${\omega}$-Noetherian if and only if the direct limit of GV -torsion-free injective R-modules is injective; if and only if every R-module has a GV -torsion-free injective (pre)cover; if and only if the direct sum of injective envelopes of ${\omega}$-simple R-modules is injective; if and only if the essential extension of the direct sum of GV -torsion-free injective R-modules is the direct sum of GV -torsion-free injective R-modules; if and only if every $\mathfrak{F}_{w,f}(R)$-injective ${\omega}$-module is injective; if and only if every GV-torsion-free R-module admits an $i$-decomposition.

• 전자공학회논문지A
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• 제33A권7호
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• pp.216-222
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• 1996

Since many typical 2.5 Gbps optical transmitter modules use a 50$\Omega$ characteristic impedance, they require relatively high voltage and high power sources compared to the 25$\Omega$ module. However, simple replacement of the 50$\Omega$ internal matching impedance with 25$\Omega$ results in bandwidth reduction and consequent problem of data transmitter module is proposed in order to expand the modulator bandwidth. From the calculated resutls based on accurate 3-dimensional inductance analysis, we have found that the series parasitic inductance is a dominant element limiting the bandwidth and the insertion of a 2.5pF capacitor in parallel to the 20$\Omega$ matching resiter can increase the 3 dB bandwidth about 1.4GHz wider. The time-domain results show the rise time (140 psec) without the compensation is greatly improved to 63 psec with the compensation. This capacitive ocmpensation can be implemented easily and be compatible with common manufacturing process of the optical transmitter module.

• 마이크로전자및패키징학회지
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• 제7권3호
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• pp.1-6
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• 2000

폐수의 온도차등의 폐열 에너지를 이용한 에너지 절약 시스템으로써 구조가 간단한 소형의 열전 발전기를 개발하였다. 열원으로 끊는 물을 이용하고, Bi-Te 계 열전반도체 모듈 16개를 전기적으로 직렬로 연결하고 패키징하여 열전 변환 시스템을 제작하였다. 열전 발전기의 출력은 온도차가 75 K, 전기저항이 40$\Omega$, 전류가 0.35 A에서 약 4.5 W정도를 얻을 수 있었다.