• 한국정보통신설비학회:학술대회논문집
• /
• 2008.08a
• /
• pp.441-446
• /
• 2008

In this papers, a PLDRO(Phase Locked Dielectric Resonator Oscillator) is designed and implemented at the oscillator in which fundamental frequency is 18.3 GHz. The proposed PLDRO so as to improve the PLDRO of the general structure is designed to the goal of the minimize of the size and the performance improvement. Three VCO(Voltage controlled Oscillator) and the power combiner improved the output power. A VCDRO(Voltage Controlled Dielectric Resonator Oscillator) is manufactured using a varactor diode to tune oscillating frequency electrically, and its phase is locked to reference frequency by SPD(Sampling Phase Detector). This product is fabricated on Teflon substrate with dielectric constant 2.2 and device is ATF -13786 of Ka-band using. This PLDRO generates an output power of 5.67 dBm at 18.3 GHz and has the characteristics of a phase noise of -80.10 dBc/Hz at 1 kHz offset frequency from carrier, the second harmonic suppression of -33 dBc. The proposed PLDRO can be used in Ka-band satellite applications

• Proceedings of the KIEE Conference
• /
• 1995.07a
• /
• pp.347-349
• /
• 1995

This paper describes current controlled PWM technique of IPM synchronous motors for a wide variety of speed control applications. They are however limited in their ability to operate in the power limited regime where the available torque is reduced as the speed is increased above its base value. This paper reviews the operation of the IPMSM drives when they are constrained to be within the permissible envelope of maximum inverter voltage and current to produce the rated power and to provide this with the highest attainable rotor speed. This paper proposes a new field-weakening control algorithm using phase current feedback to improve the torque characteristics and to reduce the torque ripple of IPMSM in the constant power region. The improved torque characteristics of speed control strategy with current feedback control algorithm is analyzed and the performance is investigated by the computer simulation results.

• Journal of Korean Society of Rural Planning
• /
• v.11 no.3 s.28
• /
• pp.29-42
• /
• 2005

This study aimed to apply a methodological approach, 'social network analysis' to a case study for the understanding of relational structure among stakeholders related to green tourism development. By doing so, this study argued that it is important to identify stakeholder's network structure to help green tourism planners develop collaborative relationship among stakeholders. This study identified the stakeholders regarding a community-based festival development in the southern area of Korea, and investigated two types of networks among them: decision-making power relational and intimate network. Interviewer-administrated survey and in-depth interview were employed for data collection. The data was analyzed by SPSS (version 10.0) and Net-MinerII (version 2.5.0), and by constant comparison method. The result revealed that low different groups of the stakeholders were separated in the intimate networt and that the festival organizational body was not connected with other stakeholders in the decision-making power relational network. The existence of separated groups and weak relationship among the stakeholders appeared to relate to age-group differences, and different views on the festival between the stakeholders.

• Journal of Power System Engineering
• /
• v.18 no.6
• /
• pp.113-119
• /
• 2014

Due to the development of the petroleum refining technology and continuously increased demand from markets, a quantity of gasoline and diesel oil produced from a restricted quantity of crude oil has been increasing, and residual fuel to be used at marine diesel engines has been gradually becoming low quality. As a result, it was recently reported that trouble oils which cause abnormal combustion such as knocking with extreme noise and misfire from internal combustion engines were increasing throughout the world. In this study, an author investigated ignitability and combustion quality by using combustion analyzer with constant volume(FCA, Fuel Combustion Analyzer) and middle speed diesel engine about MDO(Marine Diesel Oil), HFO(Heavy Fuel Oil), LCO(Light Cycle Oil) and Blend-HFO which was blended LCO of 1000 liters with HFO of 600 liters. Moreover, for betterment of ignitability and combustion quality of injected fuels, multi-injection experiment was carried out in the diesel engine using Blend-HFO. According to the results of FCA analysis, ignitability and combustion quality was bad in the order of MDO

• Journal of Power Electronics
• /
• v.18 no.6
• /
• pp.1642-1649
• /
• 2018

A single-stage flyback LED AC-DC converter based on primary-side control under constant current mode is proposed in this study. The proposed converter features low total harmonic distortion (THD) and high power factor (PF). It also consists of a zero-crossing distortion compensation circuit and a variable duty ratio control compensation circuit to deal with the line current distortions caused by fixed duty ratio control. The system model and layout are built in Simplis and Cadence, respectively. The feasibility and performance of the proposed circuit is verified by designing and fabricating an IC controller in the HHNEC $0.35{\mu}m$ 5 V/40 V HVCMOS process. Experimental results show that the PF can reach a level in the range of 0.985-0.9965. Moreover, the average THD of the entire system is approximately 10%, with the minimum being 6.305%, as the input line voltage changes from 85 VAC to 265 VAC.

• Journal of Drive and Control
• /
• v.11 no.3
• /
• pp.31-40
• /
• 2014

This paper proposes a multi absorbing wave energy converter design, in which a hydrostatic transmission is used to transfer wave energy to electric energy. The most important feature of this system is its combination of the pressure coupling principle with the use of a hydraulic accumulator to eliminate the effects of wave power fluctuation; this maintains a constant speed of the hydraulic motor. Tilt motion of a floating buoy was employed as the power take-off mechanism. Furthermore, a PID controller was designed to carry out the speed control of the hydraulic motor. The design offers some advantages such as extending the life of the hydraulic components, increasing the amount of energy harvested, and stabilizing the output speed.

• Journal of Power Electronics
• /
• v.19 no.6
• /
• pp.1496-1504
• /
• 2019

This paper proposes a new THD reduction algorithm for modular multilevel converters (MMCs) with offset voltage injection operated in nearest level modulation (NLM). High voltage direct current (HVDC) is actively introduced to the grid connection of offshore wind powers, and this paper deals with a voltage generation technique with an MMC for wind power generation. In the proposed method, third harmonic voltage is added for reducing the THD. The third harmonic voltage is adjusted so that each of the pole voltage magnitudes maintains a constant value with a maximum number of (N+1) levels, where N is the number of sub-modules per arm. By using the proposed method, the THD of the output voltage is mitigated without increasing the switching frequency. In addition, the proposed method has advantageous characteristics such as simple implementation. As a part of this study, this paper compares the THD results of the conventional method and the proposed method with offset voltage injection to reduce the THD. In this paper, simulations have been carried out to verify the effectiveness of the proposed scheme, and the proposed method is implemented by a HILS (Hardware in the Loop Simulation) system. The obtained results show agreement with the simulation results. It is confirmed that the new scheme achieved the maximum level output voltage and improved the THD quality.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.521-524
• /
• 2009

Response to nerve stimulation platform for implementing measures to detect finger movement has been functioning as an important factor. This stimulated finger on the nerve and muscle responses would vary. In other words, the finger movement of the muscle response to nerve stimulation and sensing Actuator for the H/W development is needed. In addition, a low power embedded CPU based on the top was used. H/W configuration portion of the isolation power, constant current control, High impedance INA, amplifier parts, and the stimulus mode and the Micro-control the status of current, AD converter Low Data obtained through the processing system is implemented.

• Nuclear Engineering and Technology
• /
• v.23 no.1
• /
• pp.30-40
• /
• 1991

For automatic power control of KMRR, a new method, Reactivity Constraint Method, is applied for time optimal control. This method limits the net reactivity to the amount that can be offset by instantaneous control rod action. The reactivity to be constrained for the constant reactor period should be obtained by the dynamic period equation. A new formulation of the dynamic period equation for 2-point kinetics model is presented. A methematical controller model was applied to the plant simulator, KMRSIM to test this control law. The performance test showed that reactivity constraint approach is also a reliable means for reactor power change control.

• Journal of English Language & Literature
• /
• v.55 no.6
• /
• pp.1123-1137
• /
• 2009

Revisiting the horror of slave mutiny in nineteenth century America via Julia Kristeva's concept of abject, this essay examines abject fear in Amasa Delano and Babo's subversive act to deceive Delano in Herman Melville's "Benito Cereno." Babo, the slave, exercises subversive power, thereby reversing racial hierarchy aboard the slave ship-the San Dominick. Babo's ability to mimic and control racial stereotypes exposes how nineteenth-century racial hierarchy was only a social fiction, which becomes the very source of Delano's fear. Delano's dread belies upon the possible disruption of social order triggered by Babo'sblack rebellion. In order to repress his fear, Delano consciously and unconsciously attempts to re-inscribe white dominion and reaffirm black inferiority and stereotypes by means of rationalizing the disturbing signs he witnesses on the San Dominick. When Delano discovers the realsituation of the ship, he must relinquish the abject resonance that disturbs the previous racial order. Employing a legal document, Delano re-inscribes the official position of the blacks as slaves, defining them as violent savages, and thereby silences Babo. However, Melville's text is not a testament to white power. "Benito Cereno" actually endorses abject instability to challenge racial hierarchies through the poignant image of Babo's dead gaze in the last scene of the novella. Thus, "Benito Cereno" exemplifies the recurring power of abject as a threat to social hierarchy and as a constant reminder of the falsity and insecurity of a social order.