• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.91-96
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• 2005

In this paper, a general performance of the PSS-LCD or Polarization Shielded Smectic Liquid Crystal Display is discussed. This smectic base LCD does not use any spontaneous polarization, but uses induced polarization just same with current nematic base LCDs. Specific initial molecular alignment as well as specific cell design realizes extremely fast optical response speed with native wide viewing angle. Moreover, this performance is provided by full compatible electronics for current conventional LCDs. A general performance of the PSS-LCD is introduced here.

• 조명전기설비학회논문지
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• 제15권4호
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• pp.14-22
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• 2001

본 논문에서는 전력계통의 저주파 진동 억제와 안정도 향상을 위해 적응 뉴로-퍼지 전 보상기(Adaptive Neuro-Fuzzy Precompensator, ANFP)를 설계하였다. 여기서 ANFP는 종래의 전력계통 안정화 장치(Power System Stabilizer, PSS)를 보상하도록 설계되며, 이 설계기법은 기존의 PSS 최적 파라미터를 구하는 방식과는 달리 현재 사용중인 PSS 파라미터를 고정시켜놓고, ANFP만을 추가하는 구조적인 장점을 나타낸다. 먼저, 학습 능력을 가지는 퍼지 전 보상기가 구성되며, 이는 발전 유니트의 입출력 데이터로부터 학습된다. ANFP는 학습의 특성을 가지기 때문에 보상기의 퍼지규칙과 소속함수는 학습 알고리즘에 의해 자동으로 동조될 수 있다 학습은 ANFP와 목표 제어기(desired controller)의 출력을 비교하여 평가되는 오차를 최소화하도록 수행된다. 사례 연구 들에서 다양한 동작 조건들 상에서 전력계통의 우수한 제동을 제공할 수 있었으며, 시스템의 동특성을 향상시킬 수 있었다

• 디자인융복합연구
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• 제16권3호
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• pp.69-84
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• 2017

서비스 블루프린트(Service blueprint)는 새로운 서비스 시스템을 제안하는 단계에서 고객을 중심으로 각 서비스 요소 간의 상호작용을 한 눈에 보여 주고 서비스 전체의 흐름을 파악하기 위해 사용되는 것으로서 온라인 비즈니스가 개발되기 전인 1980년대에 제안된 것이다. 그러나 오늘날의 서비스는 제품 서비스 시스템(PSS)으로 확장되거나, 온라인과 오프라인으로 채널이 다양해져, 기존의 서비스 블루프린트는 이를 표현하기에 불충분하다. 이에 본 연구는 각 비즈니스에 최적화된 서비스 블루프린트 유형을 제안하고자 하였다. 이를 위해 연구에 활용될 PSS사례 137개를 수집한 후 비즈니스 매트릭스를 제작하여 사례를 분류하고, 대표사례를 선정하여 총 두 차례의 실험을 진행하였다. 그 결과 매트릭스에 대응하는 6가지의 서비스 블루프린트 유형인 온라인 서비스형, 온라인 원격지원형, 셀프렌탈형, 온라인 주문형, 전통적 유형, 오프라인 지원형을 도출할 수 있었다. 이후 해당 유형의 적합성을 판단하기 위하여 검증을 진행하여 제안한 서비스 블루프린트의 6가지 유형이 적합함을 확인하였다. 이를 통하여 PSS디자인 또는 개발 시 비즈니스의 특성에 맞게 선택적으로 사용할 수 있음을 입증하였고, 향후 본 연구에서 제안하는 서비스 블루프린트의 유형이 클라이언트에게 효과적으로 전달될 수 있는 템플릿이 되길 바라며 서비스 디자이너나 개발자, 기획자와의 커뮤니케이션에도 효과적으로 사용되길 기대한다.

• 대한전기학회논문지:전력기술부문A
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• 제51권9호
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• pp.441-450
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• 2002

In this paper, optimal tuning problem of power system stabilizer using IA-QFT is investigated to improve power system dynamic stability in spite of parameter variation and disturbance uncertainties. The most important feature of QFT is that it is able to deal with the design problem of complicated uncertain plants. However, loop shaping is currently performed in computer aided design environments manually and it is usually a trial and error procedure. It is difficult to design a controller to satisfy all specifications manually. To solve this problem, a study of design automation using IA needs to be taken into account. The robustness of the proposed controller has been investigated on a single machine infinite bus model. The results are shown that the proposed PSS using IA-QFT is more robust than conventional PSS.

• 대한두개안면성형외과학회지
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• 제22권4호
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• pp.183-192
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• 2021

Background: The purse-string suture (PSS) is a simple and rapid wound closure method that results in minimal scarring. It has been used to treat circular or oval skin defects caused by tumor excision or trauma. However, due to obscurity, it is not widely used, especially for the head and neck. This study aimed to modify the PSS to obtain predictable and acceptable results. Methods: A total of 45 sites in 39 patients with various types of skin and soft tissue defects in the head and neck were treated with PSS. We used PDS II (2-0 to 5-0), which is an absorbable suture. Minimal dissection of the subcutaneous layer was performed. The suture knot was hidden by placing it in the dissection layer. Depending on the characteristics of the skin and soft tissue defects, additional surgical interventions such as side-to-side advancement sutures, double PSS, or split-thickness skin graft were applied. Results: All wounds healed completely without any serious complications. Large defects up to 45 mm in diameter were successfully reconstructed using only PSS. Postoperative radiating folds were almost flattened after approximately 1-2 months. Conclusion: PSS is simple, rapid, and relatively free from surgical design. Owing to the circumferential advancement of the surrounding tissue, PSS always results in a smaller scar than the initial lesion and less distortion of the body structures around the wound in the completely healed defect. If the operator can predict the process of healing and immediate radiating folds, PSS could be a favorable option for round skin defects in the head and neck.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.137-139
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• 2001

In this paper, we design a GA-fuzzy precompensator for enhancement of power system stability. Here, a fuzzy precompensator is designed as a fuzzy logic-based precompensation approach for Power System Stabilizer(PSS). This scheme is easily implemented simply by adding a fuzzy precompensator to an existing PSS. And we optimize the fuzzy precompensator with a genetic algorithm for complements the demerit such as the difficulty of the component selection of fuzzy controller, name1y, scaling factor, membership function and control rules. Simulation results show that the proposed control technique is superior to a conventional PSS in dynamic responses over the wide range of operating conditions and is convinced robustness and reliableness in view of structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.232-234
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• 1998

In this paper, we are considered various possible disturbance conditions in order to design controller, $H_{\infty}$ optimal controller is successfully designed to control in such as situations. To do this, we are determined weighting function and design parameter $\gamma$ to method of trial and error by Glover-Doyle algorithm. To compare with $H_{\infty}$-PSS and conventional-PSS which is applied in nominal system and load variations, the dynamic characteristics of $H_{\infty}$-PSS controller was verified which has a good response.

• Transactions on Electrical and Electronic Materials
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• 제17권6호
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• pp.341-350
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• 2016

The current study is dedicated to design a novel coordinated controller to effectively increase power system rotor angle stability. In doing so, the coordinated design of an AVR (automatic voltage regulator), PSS2B, and TCSC (thyristor controlled series capacitor)-based POD (power oscillation damping) controller is proposed. Although the recently employed coordination between a CPSS (conventional power system stabilizer) and a TCSC-based POD controller has been shown to improve power system damping characteristics, neglecting the negative impact of existing high-gain AVR on the damping torque by considering its parameters as given values, may reduce the effectiveness of a CPSS-POD controller. Thus, using a technologically viable stabilizer such as PSS2B rather than the CPSS in a coordinated scheme with an AVR and POD controller can constitute a well-established design with a structure that as a high potential to significantly improve the rotor angle stability. The design procedure is formulated as an optimization problem in which the ITSE (integral of time multiplied squared error) performance index as an objective function is minimized by employing an IPSO (improved particle swarm optimization) algorithm to tune adjustable parameters. The robustness of the coordinated designs is guaranteed by concurrently considering some operating conditions in the optimization process. To evaluate the performance of the proposed controllers, eigenvalue analysis and time domain simulations were performed for different operating points and perturbations simulated on 2A4M (two-area four-machine) power systems in MATLAB/Simulink. The results reveal that surpassing improvement in damping of oscillations is achieved in comparison with the CPSS-TCSC coordination.

• International Journal of Control, Automation, and Systems
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• 제6권4호
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• pp.506-514
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• 2008

This paper presents an intelligent model; named as free model, approach for a closed-loop system identification using input and output data and its application to design a power system stabilizer (PSS). The free model concept is introduced as an alternative intelligent system technique to design a controller for such dynamic system, which is complex, difficult to know, or unknown, with input and output data only, and it does not require the detail knowledge of mathematical model for the system. In the free model, the data used has incremental forms using backward difference operators. The parameters of the free model can be obtained by simultaneous perturbation stochastic approximation (SPSA) method. A linear transformation is introduced to convert the free model into a linear model so that a conventional linear controller design method can be applied. In this paper, the feasibility of the proposed method is demonstrated in a one-machine infinite bus power system. The linear quadratic regulator (LQR) method is applied to the free model to design a PSS for the system, and compared with the conventional PSS. The proposed SPSA-based LQR controller is robust in different loading conditions and system failures such as the outage of a major transmission line or a three phase to ground fault which causes the change of the system structure.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권4호
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• pp.165-174
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• 2000

This paper presents the application of H$\infty$ control synthesis using LMI optimization method to power system stabilizer(PSS) design. Since power system is usually operated under circumstance of unmeasurable uncertainties and external disturbances, the improvement of small signal stability becomes one of the most important issue for securing system stability and preventing low frequency oscillation phenomena. The LMI optimized H$\infty$ PSS provides robust performance and guarantees the internal stability under these operating conditions. The global optimal H$\infty$ norm is found using LMI convex optimization method which is more systematic than standard two Riccati solution method. The design results are simulated for a case study. We verified that the LMI method shows the best performance characteristic smong standard Riccati method and conventional lead/lag method.