• Journal of IKEEE
• /
• v.22 no.4
• /
• pp.1006-1011
• /
• 2018

This paper proposes a three level buck converter utilizing multi-bit flying capacitor voltage control. The conventional three-level buck converter can not control the flying capacitor voltage, so that the operation is unstable or the circuit for controlling the flying capacitor voltage can not be applied to the PWM mode. Also when the load current is increased, an error occurs in the inductor voltage. The proposed structure can control the flying capacitor voltage in PWM mode by using differential difference amplifier and common mode feedback circuit. In addition, this paper proposes a 3bit flying capacitor voltage control circuit to optimize the operation of the three level buck converter depending on the load current, and a triangular wave generation circuit using the schmitt trigger circuit. The proposed 3-level buck converter is designed in $0.18{\mu}m$ CMOS process and has an input voltage range of 2.7V~3.6V and an output voltage range of 0.7V~2.4V. The operating frequency is 2MHz, the load current range is 30mA to 500mA, and the output voltage ripple is measured up to 32.5mV. The measurement results show a maximum power conversion efficiency of 85% at a load current of 130 mA.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.2
• /
• pp.37-44
• /
• 2008

This paper presents a 5.8 GHz PLL using high-speed ring oscillator for WLAN. The proposed ring oscillator has been designed using the negative skewed delay scheme and for differential mode operation. Therefore, the oscillator is insensitive to power-supply-injected noise, and it has the merit of low 1/f noise because tail current sources are not used. The output frequency ranges from 5.13 to 7.04 GHz with the control voltage varing from 0 to 1.8 V. The proposed PLL circuits have been designed, simulated, and proved using 0.18 um 1.8 V TSMC CMOS library. At the operation frequency of 5.8 GHz, the locking time is 2.5 us and the simulated power consumption is 59.9 mW.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.769-772
• /
• 2005

This paper describes a low-voltage and low-power channel selection analog front end with continuous-time low pass filters and highly linear programmable-gain amplifier(PGA). The filters were realized as balanced Gm-C biquadratic filters to achieve a low current consumption. High linearity and a constant wide bandwidth are achieved by using a new transconductance(Gm) cell. The PGA has a voltage gain varying from 0 to 65dB, while maintaining a constant bandwidth. A filter tuning circuit that requires an accurate time base but no external components is presented. With a 1-Vrms differential input and output, the filter achieves -85dB THD and a 78dB signal-to-noise ratio. Both the filter and PGA were implemented in a 0.18um 1P6M n-well CMOS process. They consume 3.2mW from a 1.8V power supply and occupy an area of $0.19mm^2$.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.11
• /
• pp.27-33
• /
• 2011

Recently many display devices support the digital display interface as display market growth. DisplayPort is a next generation display interface at the PC, projector and high definition content applications in more widely used connection solution development. This paper implements multiple streams based on the behavior of the main link that is suitable for the display port v1.1a standard. The limit point of Displayport, interface between the Sink Device and Sink Device is also implemented. And two or more differential image data are enable to output the result through four Lanes stated in display port v1.1a, of two or more display devices without the addition of a separate Lane. The Multiple Video Streaming Controller is implemented with 6,222 ALUTs and 6,686 register, 999,424 of block memory bits synthesized using Quartus II at Altera Audio/Video Development board (Stratix II GX FPGA Chip).

• Journal of Sensor Science and Technology
• /
• v.9 no.2
• /
• pp.113-119
• /
• 2000

In this work, Pd/Pt gate MISFET sensor using Pd membrane was fabricated to detect the hydrogen in DI water. A differential pair-type was used to minimize the intrinsic voltage drift of the MISFET. To avoid hydrogen induced drift of the sensor, the silicon dioxide/silicon nitride double layer was used as the gate insulator of the FET's. In order to eliminate the blister formation on the surface of the hydrogen sensing gate metal, Pd/Pt double metal layer was deposited on the gate insulator. For this type of application sensors need to be isolated from the DI water, and a Pd membrane was used to separate the sensor from the DI water. The output voltage change due to the variation of hydrogen concentration is linear from 100ppm to 500 ppm.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.5
• /
• pp.857-864
• /
• 2020

The multi-functional VoIP phone supports the Ethernet protocol in the TIPS(: Tactical IP Switch), which is one of the sub-systems of the tactical information and communication system (TICN). It provides secured voice / video calls in conjunction with VoIP exchanges and supports differential services such as multi-party calls and command functions. In this paper, improving methods have been proposed to reduce power supply defects in the field of multi-functional VoIP phones. The power supply part was improved by applying TVS of the output voltage inlet of the dedicated adapter of the multi-functional VoIP phone, TVS of the PoE module input, adding blocking diodes, and adding DC / DC converters behind the poly-switch. Also, functional and environmental tests were performed to verify the validity of the proposed methods.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.3
• /
• pp.298-305
• /
• 2015

This paper provides experimental results of an excitation control system of the synchronous generator on board ships in accordance with rules of classification society to make sure its performance. The experiment compares and reviews control results between PID control and fuzzy logic control applied to change of loads of the generator in order to make sure to satisfy the rules of classification society. Both of them are written by Labview program. In case of PID Control, this paper firstly adjusts the gains by ultimate sensitive method and the gains is more tuned by engineer's experience. And the fuzzy logic controller uses Mamdani method to make membership function for error between reference voltage and measuring voltage, differential error rate and output voltage. This paper is to make sure the experimental results of the proposed excitation control system applied to actual small synchronous generator with PID control and fuzzy logic written by using Labview program and it is proved on stability and improvement through experiments.

• Journal of Oriental Neuropsychiatry
• /
• v.28 no.4
• /
• pp.401-408
• /
• 2017

Objectives: The purpose of this study is to obtain the differential variable and learning effect of the serial position effect, targeting individuals aged 60 years and over. A total of 89 individuals were categorized into the following groups: Alzheimer's group, vascular dementia group, elderly depression group, and normal group. Methods: Considering the size of the groups used for comparison, of the total 89 participants, 28 were in the Alzheimer's group, 24 in the vascular dementia group, 16 in the elderly depression group, and 21 were randomly chosen for the normal group. In the CERAD-K word list memory test, 10 words were shown to the subjects. We then asked them to freely recall the words. After changing the order of the words three times, the same process was followed. Results: First, a significant difference was observed among the groups in terms of word recalling rate. The analysis conducted afterward showed that, as predicted, the depressed group showed significantly better performance in recalling the words. Second, the vascular dementia patients and the Alzheimer's patients showed, as predicted, better recall of the largest recency region of words shown. Third, the normal group and the elderly depressed group showed a high-performance rate, proving that the reiterative method can contribute to the recalling process. Thus, we demonstrated that the Alzheimer's group showed the deterioration of short memory recalling skills and the elderly depressed showed deteriorated output performance skill.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.6
• /
• pp.40-48
• /
• 2013

Recently, many types of electric vehicles including a heavy duty vehicle have been developed and released because of the better fuel economy and less gas products. In this study, research about an electric bus which utilizes the wheel motor drive system was conducted. The wheel motor is a motor connected to the wheel directly only with a simple gear so that the developer can utilize the space efficiently and the whole system efficiency will be better because of simple structure. However, because it is different from former types of vehicles which use the differential gear, the development of the integrated control logic is required in order to meet the vehicle stability and driving performance. The developed control logic is composed with direct yaw moment control, regenerative braking control and slip control logics. It is compared to the control logics which does not consist of direct yaw moment control and slip control when the vehicle is exposed in tough situations. For the unification of the control logic, a few maps were developed and applied to determine the output torque of each motor according to the driving status. As a result, it is shown that the developed control logic is more safe and well follow the target speed than the other control logic applied simulations.

• Journal of Astronomy and Space Sciences
• /
• v.25 no.4
• /
• pp.395-404
• /
• 2008

We explore the linkage between the long term variability of the Sun and earth's climate change by analysing periodicities of time series of solar proxies and global temperature anomalies. We apply the power spectral estimation method named as the periodgram to solar proxies and global temperature anomalies. We also decompose global temperature anomalies and reconstructed total solar irradiance into each local variability components by applying the EMD (Empirical Mode Decomposition) and MODWT MRA (Maximal Overlap Discrete Wavelet Multi Resolution Analysis). Powers for solar proxies at low frequencies are lower than those of high frequencies. On the other hand, powers for temperature anomalies show the other way. We fail to decompose components which having lager than 40 year variabilities from EMD, but both residuals are well decomposed respectively. We determine solar induced components from the time series of temperature anomalies and obtain 39% solar contribution on the recent global warming. We discuss the climate system can be approximated with the second order differential equation since the climate sensitivity can only determine the output amplitude of the signal.