• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2426-2438
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• 1994

In this paper we present for the first time the electric circuit model for direct frequrncy modulation(FM) response of the conventional distributed-feedback(DFB) semiconductor laser diodes. Especially, in this paper, the proposed model includes not only the carrier density modulation effect, but also the temperature modulation effect determining the DFM characteristics of DFB characteristics of DFB semiconductor lasers. The DFM response due to injection current modulation was obtained as a function of modulation frequency from DC to a few GHz. The circuit model representing the temperature modulation effect is obtained from the structure of DFB LD chip and the simulation results are compared with the published experimental results. The circuit model representing the temperature modulation effect is obtained from the structure of DFB LD chip and the simulation results are compared with the published experimental results. The circuit model representing carrier density modulation effect is obtained from the rate equations of DFB lasers and the simulation results are compared with the results that were obtained by the conventional numerical analysis approach. The results showed good agreements.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.951-954
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• 1999

A direct digital frequency synthesizer is designed in full custom method using 0.65${\mu}{\textrm}{m}$ CMOS n-well technology The chip provides the capability of the parallel operation using up to 4 chips with an operation frequency of 440MHz. The generated waveform can be modulated by various modulation techniques such as QPSK, 256 . 64. 32 . 16 QAM and FM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.145-152
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• 2009

Ultra-wideband communication systems for impulse radio have merits that are possible for either high resolution ranging system or radio determination. Conventionally, in order to accomplish these functions, the rapid analog to digital convertor (ADC) is necessary to apply radio determination system operating in time domain. However, considering that low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces the high resolution ranging system operating in frequency domain with using low sampling rate ADC, and a new non-coherent ranging scheme utilizing analog Frequency Modulation (FM) mode for the frequency domain transformation. To verify the superiority of the proposed ranging algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.911-914
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• 2004

This paper discusses on new two LCD technologies featured by the fast electro-optic response:one is polymer-stabilized FLCDs that exhibit V-shaped electro-optic (EO) switching called PSV-mode FLCDs with response time of 400 ${\mu}$ s; and the other is TN-mode LCDs that exhibit a frequency modulation response (called PM-TN LCDs)and a peculiar sensitivity to the high frequency component of driving voltage waveforms resulting in a short decay time constant of 5ms and an enhancement in the over-driving that yields short response time of 1ms between two gray levels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11C
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• pp.1083-1090
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• 2005

This paper presents the design of a video encoder for the device of need TV-OUT function. The designed video encoder satisfies the standard conditions of International Telecommunication Union-Radiocommunication (ITU-R) BT.470. ITU-R BT.470 can be classified as NTSC, PAL or SECAM. NTSC and PAL use Amplitude Modulation (AM) to transmit color difference signals and SECAM uses Frequency Modulation (FM). SECAM must have an antic-cloche filter but the filter recommended by ITU-R BT.470 is not easy to design due to sharpness of the frequency response. So formerly the filter was designed as analog. This paper proposes that the filter is designed as digital and the special quality of the filter is transformed easy to design. And the modulation method is modified to be identical with the result required at standard. The encoder can control power consumption by output mode to apply mobile phone, mobile devices, etc. The proposed encoder is experimentally demonstrated with ALTERA FPGA APEX20KE EP20K1000EBC652-3 device and SAMSUNG LCD-TV.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1047-1056
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• 2007

In this paper, we analyze the performance of the encoding and the modulation processes in the downlink and uplink of the EPCglobal Gen-2 system through the analysis and simulation. Furthermore, the synchronization issues on time and frequency domain and the preamble architecture are evaluated. By incorporating the encoding and the modulation technigue in the downlink and uplink, we assess the performance of the EPCglobal Gen-2 system. We also introduce the encoding and backscatter modulation process as well as the BER performance of FM0 code. In addition, the importance and the role of the frequency and time synchronization, such as the preamble and frame synchronization are explained. Through the simulation in the uplink on the detection probability through preamble, we find that the detection probability approaches 1 for 13 dB $E_b/N_0$.

• The Journal of Korean Physical Therapy
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• v.21 no.2
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• pp.109-116
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• 2009

Purpose: $17\beta$-estradiol is the most active endogenous estrogen, which is related to favorable changes in the plasma lipid profile, to relaxation of the coronary vessels, and to a decrease in platelet aggregation and vascular smooth muscle cell migration. However, although the beneficial effect of estrogens on plasma lipoproteins (ie, lowering low-density lipoprotein and increasing high-density lipoprotein cholesterol) contributes to cardiovascular protection, it does not fully account for the protective effect, particularly in the application of physical therapy, including low frequency electrical stimulation. Methods: The aim of this study was to demonstrate the inhibition of stressors, such as endothelin-1 (ET-1), serotonin (5-hydroxytryptamine, 5-HT), prostaglandin $F2\alpha$ ($PGF2\alpha$), and a protein kinase C (PKC) activator 12-deoxyphorbol 13-isobutyrate (DPB), induced isometric tension by $17\beta$-estradiol in vascular smooth muscle strips, respectively. In addition, the effects of low frequency electrical stimulation at the meridian points (CV-3, -4, Ki-12, SP-6, LR-3, BL-25, -28, -32, -52) on the indirect antihypertensive effect were examined by monitoring the changes in the serum $17\beta$-estradiol concentration in healthy volunteers. Results: Isometric tension analysis showed that the responses of inhibited tension by $17\beta$-estradiol were similar to the same stressors in rat aortic smooth muscle strips. Furthermore, although the continued amplitude modulation (AM) type of electrical stimulation was not increased significantly by electrical stimulation, the current of the frequency modulation (FM) type of low frequency electrical stimulation increased the serum $17\beta$-estradiol concentration in normal volunteers. Conclusion: These results, in part, suggest that $17\beta$-estradiol has the capacity to supress stressor-induced muscle tension, and electrical stimulation, particularly current of the FM type, has a modulatory effect on the sex steroid hormones, particularly $17\beta$-estradiol, in healthy volunteers.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.3
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• pp.199-206
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• 2016

This paper describes a simple routing control system. We propose achieving high-speed data transmission without modifying the data frame configuration. To add a routing control signal, called the "labeling signal" in this paper, to the data frame, we use a frequency modulation technique on the transmitted frame. This means you need not change the data frame when you transmit additional signals. Using a prototype system comprising a field-programmable gate array and discrete elements, we investigate the system performance and devise a method to achieve high resolution. A three-channel routing control for a 10 Gb/s data frame was achieved, which confirms the advantages of the proposed system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.4
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• pp.20-30
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• 1969

Several new modulators using Voltage Variable Capacitance Diode are discribed. It was investigated that amplitude modulation which does not need modulation power is obtained by mdulation VVC diode as a tuning element of the quartz oscillator circuit. It offers a good AM system for carryphones in the citizen bands. While frequency modulated quartz oscillators coupled with a quarter wave network were tested as a wide band frequency modulator, Hartley type transistor oscillator offers the most stable and reproducibel FM quartz oscillator.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.42-44
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• 1995

The original DANTE sequence and its variations have limitation in excitation profile (a sinc function-like excitation) due to the finite duration of the DANTE pulsetrain. This sinc function-like selection profile excites only a small fraction of the spins in the pixel thereby results in poor signal to noise ratio (only about ${\sim}1%$ of normal MR imaging sequence). Therefore, this poor signal to noise ratio (SNR) has been the main drawback of the original DANTE sequence. To improve the signal to noise ratio, phases of individual RF pulses in the DANTE pulse train were modulated so that more spins in the object were excited ($1{\sim}3$). We have introduced a new FM (Frequency Modulation) DANTE sequence and analyzed the signal intensity and excitation profiles.