• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.2
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• pp.34-43
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• 2008

An OpenLDI receiver circuit for flat-panel display systems was designed and fabricated using $1.8-{\mu}m$ high-voltage CMOS technology. Designed circuit roughly consists of DLL circuit and parallelizers, which recovers clock and parallelize data bits, respectably. It has one clock input and four data inputs. Measurement results showed that it successfully recovers clock signal from input whose frequency is $10Mhz{\sim}65Mhz$, which corresponds data rate of $70Mbps{\sim}455Mbps$ per channel, or $280Mbps{\sim}1.82Gbps$ when all of the four data channels were utilized. A commercial LCD monitor was modified into a test-bench and used for video data transmission at clock frequency of 49Mhz. In the experiment, power consumption was 19mW for core block and 82.5mW for output buffer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.791-798
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• 2011

In this study, performance of R410A(50%R32/50%R125) and HFC32/HFC125 mixture is measured to examine the effect of composition shift of R410A used for various air-conditioners and heat pumps. The composition of HFC32/HFC125 mixture varies from the reference composition of R410A ${\pm}10%$ with 5% interval. Tests carried out in a heat pump bench tester at the evaporation and condensation temperatures of $7/45^{\circ}C$ and $-7/41^{\circ}C$ for summer and winter conditions, respectively. Test results show that both the coefficient of performance (COP) and compressor power of the HFC32/HFC125 mixture have the maximum difference of 2.0% as compared to those of R410A. Compressor discharge temperatures of HFC32/HFC125 mixture are increased up to $6.7^{\circ}C$ as compared to that of R410A. The amount of charge for HFC32/HFC125 mixture vary within 5.6% as compared to that of R410A. Overall, performance of R410A is not appreciably affected by the composition shift of ${\pm}10%$ of R32 under both air-conditioning and heat pumping conditions.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.597-606
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• 2021

Due to the characteristics of the farmland in Korea, forward and reverse shift is the most used. The fatigue of farmers is caused by forward and reverse shifting with a manual transmission. Therefore, it is necessary to improve the convenience of forward and backward shifting. This study was a basic study on the development of a current control system for forward and reverse shifting of agricultural tractors using proportional control valves and a controller. A test bench was fabricated to evaluate the current control accuracy of the control system, and the stability of the controller was evaluated through CPU (central processing unit) load measurements. A controller was selected to evaluate the stability of the proportional valve controller. The stability evaluation was performed by comparing and analyzing the command current of the controller and the actual current measured. The command current was measured using a CAN (controller area network) communication device and DAQ (data acquisition). The actual current was measured with a current probe and an oscilloscope. The control system and stability evaluation was performed by measuring the CPU load on the controller during control operations. The average load factor was 12.27%, and when 5 tasks were applied, it was shown to be 70.65%. This figure was lower than the CPU limit of 74.34%, when 5 tasks were applied and was judged to be a stable system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.645-653
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• 2013

Seoul National University flap(SNUF) blade is a small-scale rotor blade incorporating a small trailing-edge flap control surface driven by piezoelectric actuators at higher harmonics for vibration attenuation. Initially, the blade was designed using two-dimensional cross-section analysis and geometrically exact one-dimensional beam analysis, and its material configuration was finalized. A flap-deflection angle of ${\pm}4^{\circ}$ was established as the criterion for enhanced vibration reduction based on an earlier simulation. The flap-linkage mechanism was designed and static bench tests were conducted for verifying the performance of the flap-actuation mechanism. Different versions of test beds were developed and tested with the designed flap and the selected APA 200M piezoelectric actuators. Through significant improvements, a maximum deflection of ${\pm}3.7^{\circ}$ was achieved. High-frequency experiments were conducted for evaluating the performance, and the transfer function of the test bed was determined experimentally. With the static tests almost complete, the rotor power required for testing the blade in a whirl tower (centrifugal environment) was calculated, and further preparations are underway.