• Journal of Software Assessment and Valuation
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• v.15 no.2
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• pp.101-109
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• 2019

Lasers for optical broadband communication systems should have excellent frequency selectivity and modal stability. DFB(Distributed Feedback) lasers have low lasing frequency shift during high speed current modulation. In this paper, I have developed a simulation software and analysed threshold gain and lasing frequency of a lasing mode in longitudinal direction of an 1.55um DFB laser with two mirrors and without anti-reflection coatings, that have both an index- and gain-gratings. The grating phase on a left mirror face is fixed as π/2 and the grating phase on a right mirror face is varied. As the phases of the index and gain gratings on the right mirror facet are π and 0, κL should be in the range of 2~6 in order to enhance the frequency stability. In order to reduce the threshold current of a lasing mode, κL should be greater than 8, regardless of the grating phases on the mirror faces.

• Journal of Animal Science and Technology
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• v.56 no.5
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• pp.20.1-20.5
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• 2014

An experiment was conducted to evaluate the effect of form and particle size of feed supplemented with L-threonine on growth performance, carcass characteristic and blood biochemical parameters of broiler chickens. The experimental design was a $2{\times}2{\times}2$ factorial arrangement of treatments evaluating two feed forms (pellet or mash), two feed particle sizes (fine or course), and two inclusion rates of dietary L-threonine (with or without) which adopted from 7 to 42 days of age. In this experiment, 360 a day old chicks in two sexes were assigned in each treatment and each experimental unit was included 15 chicks. Feed consumption and weight gain were measured weekly. At 35 days of age, blood samples were taken to analysis blood biochemical parameters. At the end of the experimental period, two birds were slaughtered in each treatment and carcass analysis was carried out. The results showed that the effect of feed form on body weight gain and feed intake in whole of experimental period was significant (P < 0.05). Broilers fed pelleted diets had more weight gain than the mash group. Growth performance parameters were not affected by feed particle size and dietary L-threonine supplementation in whole of experimental period (P > 0.05). The results of carcass analysis showed that liver and gizzard relative weights were influenced by feed form (P < 0.05). However, pancreas and liver relative weights were affected by feed particle size and dietary L-threonine supplementation, respectively (P < 0.05). Triglyceride and VLDL levels were affected by feed form and dietary L-threonine supplementation (P < 0.05). The effect of feed particle size on blood biochemical parameters was not significant (P > 0.05). In conclusion, the experimental results indicated that feed form increased feed consumption and weight gain in whole of experimental period (1 to 42 days of age) while feed particle size and dietary L-threonine had no effect on broiler performance.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.2
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• pp.7-14
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• 1979

Design considerations of I2L are discussed with particular emphasis on the upward current gain of the npn transistor, 6J Several test structures have been fabricated to measure the DC and AC characteristics of the I2L basic cell and the base current components of the npn transistor. A T flip-flop has also been designed and fabricated using the I2L technology. The upward current gain of 10 the speed -power product of the 2.6pJ/gate and the minimum propagation delay time of 36 nsec have been obtained from the test structure. The maxmum toggle frequency of the T flip -flop has been measured to be 3.5 MHz.

• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.74-78
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• 2014

This paper presents a modified TEM horn that improves radiation characteristics at a low frequency region. The proposed antenna consists of an asymmetric TEM (ATEM) horn and a loop structure with an elliptical shape. The bandwidth and gain at low frequency region can be enhanced by using the ATEM horn configuration and adding a loop structure with an elliptical shape to the ATEM horn. The bandwidth of the proposed antenna is from 2.14 to over 20 GHz, whereas that of the conventional TEM horn is from 2.7 to over 20 GHz, where the dimensions of both antennas are the same except for the thickness of the loop structure. The physical and electrical dimensions of the proposed antenna are $60mm{\times}62.5mm{\times}64mm$ ($width{\times}height{\times}length$) and $0.428{\lambda}_L{\times}0.445{\lambda}_L{\times}0.456{\lambda}_L$, where ${\lambda}_L$ corresponds to the lowest frequency of the bandwidth. The realized gain of the proposed antenna is improved by 0.802 dB on average at the low frequency region (2 to 8 GHz), where the maximum gain increase is 2.932 dB when compared to a conventional TEM horn.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1249-1255
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• 2008

1530nm band has been studied as pump wavelength for long-wavelength-band erbium-doped fiber amplifier (L-band EDFA). The pump source is built using a tunable light source and cascaded conventional-band (C-band) EDFA. The L-band EDFA uses a forward pumping scheme. Within the 1530nm band, 1545nm pump demonstrates 0.45dB/mW gain coefficient, which is twice better than that of conventional 1480nm pumped EDFA. The noise figure of 1530nm pump is at worst 6.36dB, which is 0.75dB higher than that of 1480nm pumped EDFA. Such high gain coefficient indicates that the L-band EDFA consumes low power.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.393-398
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• 1996

In this paper, we consider H.inf. control of nonlinear systems which have not only additive uncertainties but also input-multiplicative uncertainties. Using the relation between the L$_{2}$ gain of a nonlinear system and the Hamilton-Jacobi-Isaacs inequality, we define

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1666-1671
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• 2022

The structure of a high-power gain-flattened long wavelength band (L-band) optical amplifier was optimized, which was implemented for 64-channel wavelength division multiplexed optical signals with a channel spacing of 50 GHz. The output characteristics of this L-band amplifier were measured and analyzed. The amplifier of the optimized two-stage amplification configuration had a flattened gain of 20 dB within 1 dB deviation between 1570 and 1600 nm for -2 dBm input power condition. The noise figure under this condition was minimized to within 6 dB in the amplification bandwidth. The gain flattening was realized by considering only the characteristics of gain medium in the amplifier without using additional optical or electrical devices. The proposed amplifier consisted of two stages of amplification stages, each of which was based on the erbium-doped fiber amplifier (EDFA) structure. The erbium-doped fiber length and pumping structures in each stage of the amplifier were optimized through experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.5
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• pp.757-765
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• 1999

In this paper, L-Type aperture coupled circular polarization patch antenna for mobile communication(IMT-2000, 1.9375 GHz), which is capable of being mounted in mobile unit, was designed and fabricated. This antenna is expanded to the $2\times2$ circular polarization array antenna for satellite mobile communications which are using the L-band frequency. The results are as followings : Returnloss 18.56 dB, beamwidth $60^{\circ}$, gain 7 dBd, axial ratio 0.9 dB in the case of single element and returnloss 28.43 dB, beamwidth $38^{\circ}$, gain 9.8dBd, axial ratio 1.5 dB in the case of $2\times2$ array, respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.133-141
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• 2020

The use of high-gain-voltage step-up converters for distributed power generation systems is being popularized because of the need for new energy generation and power conversion technologies. In this study, a new constructed high-gain-boost DC-DC converter was proposed to coordinate low voltage output DC sources, such as PV or fuel cell systems, with high DC bus (380 V) lines. Compared with traditional boost DC-DC converters, the proposed converter can create higher gain and has wider input voltage range and lower voltage stress for power semiconductors and passive elements. Moreover, the proposed topology produces multilevel DC voltage output, which is the main advantage of the proposed topology. Steady-state analysis in continuous conduction mode of the proposed converter is discussed in detail. The practicability of the proposed DC-DC converter is presented by experimental results with a 300 W prototype converter.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.531-532
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• 2002

This paper present a gain-clamped L-band EDFA based on reflecting back a portion of backward amplified spontaneous emission into the erbium-doped fiber section, utilizing a fiber Bra99 grating. By using FBG with R=66.1 and 99.9%, the gain is clamped at 15.1 and 14.3㏈, respectively, with a variation of less than 0.2㏈ for an input signal power as high as -5 ㏈m. However, a small noise figure penalty is obtained, which is the consequence of the gain clamping effect.