• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.957-966
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• 2023

In this paper, we propose a new real-time adaptive PID temperature control technique. This is a technique that prevents overshoot by introducing a model that represents the control object. To prevent excessive integration that causes overshoot, integral control adjusts the integral gain to track the heat loss of the model in real time. In the conventional PID control, the integration was dependent on proportional control and the gain was fixed to a constant. As a result, applying two gains that mismatch each other could cause excessive overshoot. However, the proposed adaptive control actively eliminates overshoot so that the integral control amount does not always exceed the heat loss. The cause of overshoot in PID control is integration. Basically, proportional control does not cause overshoot. Therefore, according to the proposed technique, adaptive PID control without the need for tuning experiments can be realized.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.10
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• pp.9-15
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• 2002

We propose a new transit time device to extend the operating frequency to submillimeter-wave(extreme infrared) ranges by utilizing velocity overshoot effects in the drift region. We name it a velocity overshoot transit time (OVTT) diode. This device adopts fast heterostructure tunneling as injection mechanism and a short drift region to optimize the velocity overshoot effects. To enhance dc-to-RF conversion efficiencym the drift region is designed with a bandgap grading method. Simulation results demonstrate that a VOTT diode can be operated at THz ranges.

• Journal of IKEEE
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• v.26 no.2
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• pp.313-318
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• 2022

The feedback voltage detection structure is proposed to alleviate overshoot and undershoot caused by the removal of the existing external output capacitor. Conventional LDO regulators suffer from overshoot and undershoot caused by imbalances in the power supply voltage. Therefore, the proposed LDO is designed to have a more improved transient response to form a new control path while maintaining only the feedback path of the conventional LDO regulator. A new control path detects overshoot and undershoot events in the output stage. Accordingly, the operation speed of the pass element is improved by charging and discharging the current of the gate node of the pass element. LDO regulators with feedback voltage sensing architecture operate over an input voltage range of 3.3V to 4.5V and have a load current of up to 200mA at an output voltage of 3V. According to the simulation result, when the load current is 200mA, it is 73mV under the undershoot condition and 61mV under the overshoot condition.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.2
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• pp.18-25
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• 2008

The current display systems including TVs are going digital and large-sized, and high visual quality of those systems becomes a very important selling point in the current display system market. Thus, various researches have been carried out for enhancing the visual quality of digital display systems. One of the important digital image(or video) enhancement techniques is sharpness enhancement, and it is generally based on a transient improvement technique that reduces the edge transition time. However, this technique often generates overshoot and undershoot, which cause undesirable pixel-level changes around the transient improved edge. In this paper, we propose a new nonlinear filter-based adaptive shoot elimination method for effectively suppressing the overshoot and undershoot that occur in the transient improvement, so that we can obtain visually sharper and clearer digital images(or videos). The proposed method uses two orthogonal directional min/max nonlinear filters with an adaptive shoot elimination scheme in order to effectively suppress the visually sensitive overshoot and undershoot. Experimental results show that the proposed method suppresses the overshoot and undershoot almost perfectly while maintaining the effect of the transient improvement. The applications of the proposed method include digital TVs, digital monitors, digital cameras/camcoders, portable media players(PMP), etc.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.3
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• pp.1-8
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• 2004

This paper proposes an LQ-PID controller to reduce errors occurring between input and output speeds in braking or emergency braking and to solve delay of speed or the excessive overshoot problems occurring at the speed control of induction motor. The conventional LQ controller is a method that move the poles in locations that satisfy design specifications such as overshoot and settling time etc. by state-feedback. So it may not be able to satisfy the overshoot requirement in case of the existence of zero in the closed loop transfer function. To attack this zero-problem it is presented a new design methodology of LQ-PID controller by introducing an analytic technique to eliminate the effect of zeros on the closed loop transfer function.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.271-272
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• 2014

비례-적분(PI) 제어기는 전동기의 간섭성분을 고려하지 않기 때문에 고속회전영역에서 오버슈트가 커지고, 적분기 포화로 인해 정착 시간이 느려지는 단점이 있다. 고속회전영역에서 느린 응답성을 보완하기 위해 전동기의 간섭성분을 고려하는 Cascade PI 전류제어기가 제안되었지만 오버슈트를 증가시키는 문제점이 발생한다. 본 논문에서는 Cascade PI 제어기를 소개하고 Cascade PI 제어기의 오버슈트 특성을 개선하기 위한 전류제어기를 제안하였다. 시뮬레이션을 통하여 각 제어기의 성능을 비교, 분석하였으며 실험을 통해 이를 검증하였다.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.140-142
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• 2005

본 논문은 산업용 전동기 시스템의 속도제어기에서 계단(Step)입력에 대한 속도의 오버슈트를 억제하는 새로운 방식의 반와인드업(Anti-windup)기법을 소개한다. 비례(P)제어기에서 비례적분(PI)제어기로의 전환 시점에 적분기가 적절한 초기값을 가지게 하여 오버슈트를 상쇄 시키고 빠른 응답 시간을 가지게 하였다. 시뮬레이션을 통하여 제안된 방법의 타당성을 확인하고 기존의 반와인드업 기법과 비교하여 그 우수성을 검증하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.505-512
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• 1996

CANDU에서 감속재온도제어기는 칼란드리아 출구에서의 감속재온도를 일정하게 유지하기 위한 제어 프로그램이다. 본 연구에서는 강속재온도제어 알고리즘의 성능을 분석하기 위하여 주감속재계통의 동특성모델식을 적용하여 모의실험을 수행하였다. Setback 모의실험에 대하여는 설정온도를 적절히 유지하였으나, Stepback 모의실험에 대하여는 설정온도를 크게 벗어나는 오버슈트를 나타내었다. 되먹임제어기의 PID 파라메타를 최적화하고, 정상상태모델에 근거하여 앞먹임제어기의 설계를 개선함으로써 Stepback 모의실험에서 나타난 오버슈트를 줄일 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.591-598
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• 2017

Power overshoot phenomenon was observed in microbial fuel cells (MFCs) used non-catalyzed graphite felt as cathode. Voltage loss in MFCs was mainly caused by cathode potential loss. Cheap stainless steel scrubber, which has high conductivity, and Pt/C coated graphite felt as cathode were used for overcoming power overshoot and reducing the cathode potential loss in MFCs. The MFCs used stainless steel scrubber showed no power overshoot even slow catholyte flow rate and produced 29% enhanced maximum current density ($23.9A/m^3$) than MFCs used non-catalyzed graphite felt while the power overshoot phenomenon was existed in Pt/C coated MFCs. Increasing catholyte flow rate resulted in disappearing power overshoot of MFCs used non-catalyzed graphite felt. In addition, maximum power density and current density of both MFCs used non-catalyzed graphite felt and stainless steel scrubber increased by 2-3.5 times. Cathode potential losses in all region of activation loss, ohmic loss, and mass transport loss were reduced according to increase of catholyte flow rate. Therefore, stainless steel scrubber has advantages that are economical materials as electrode and prevents power overshoot, leading to enhance electricity generation. In addition, increasing catholyte flux is one of great solution when power overshoot caused by cathodic overpotential is observed in MFCs.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.56-63
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• 2012

In this paper, adaptive unsharp masking using bilateral filter, edge-preserving smoothing filter is proposed to reduce the overshoot and jagging artifact in sharpening images. Previous image enhancement methods including unsharp masking(UM) can emphasize high-frequency details strongly, but often cause several artifacts such as overshooting, noise, jagging and so on. Proposed image enhancement method preserves edges well because of using bilateral filter and sensitively controls a weight according to edge's directions. Therefore, it enhances sharpness and effectively reduces overshoot and jagging artifacts. Simulation results comparing output of previous AUM with proposed method show that proposed algorithm makes images properly enhanced, and we know that overshoot and jagging artifacts are many reduced.