• International Journal of Contents
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• 제3권3호
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• pp.20-25
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• 2007

Standards impact the economy in various ways. Moreover, intense competition exists between a variety of standards in this era of globalization. This paper quantifies the economic effect of multiple standards in the Information Communications and Technology (ICT) sector. Thus, it identifies and specifies which standard applies when economic gains exist. A model is developed which quantifies the magnitude of the economic effect of multiple standards as compared with a single standard or no standard. The model allows for both the micro- and macroeconomic gains from standardization to be quantified. Preliminary estimates indicate that at the macro level the multiple standards multiplier is approximately three. That is for every dollar invested, the gain is on the order of three dollars. Although not as robust. preliminary results indicated a similar economic gain at the micro level Overall, multiple standards dominate a single standard. This paper applies the model to IMT-2000, an example of multiple standards, to demonstrate this approach to quantify the standards economic effect.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.219-224
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• 1988

A decentralised computational procedure is proposed for the optimal feedback gain matrix of large-scale discrete-time systems with time-delays. The constant feedback gain matrix is computed from the optimal state and input trajectries obtained hierarchically by the interaction prediction method. All the calculation in this approach are done off-line. The resulting gains are optimal for all the initial conditions. The interaction prediction method is applied to time-delay large-scale systems with general structures by extending the dimensions of coupling matices. A numerical exampie illustrates the algorithm.

• Journal of Biosystems Engineering
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• 제37권2호
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• pp.106-112
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• 2012

Purpose: A lab-scale timber carriage using a servo motor system was built. When two motors move a carriage, wire tension is changed according to the different line speeds caused by a wire drum's changing diameter, leading to inappropriate traveling characteristics of the carriage. In order to overcome this problem, PID Control was used to control the motor speed. Methods: Ziegler-Nichols method was used to determine PID gains. Results: The initial PID gains were 1.8, 0.025, and 0.006, respectively, and optimal gains of 1.4 and 0.010 for P and I gain were obtained experimentally. Conclusions: The results showed that constant wire tension could be maintained by controlling the speed of the motor using PI control. Overshoot occurred at initial motor operation due to vibration and elasticity of the wire itself.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권11호
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• pp.503-509
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• 2002

In this paper, the robust non-fragile guaranteed cost control problem is studied for a class of linear large-scale systems with uncertainties and a given quadratic cost functions. The uncertainty in the system is assumed to be norm-bounded and time-varying. Also, the state-feedback gains for subsystems of the large-scale system are assumed to have norm-bounded controller gain variations. The problem is to design a state feedback control laws such that the closed-loop system is asymptotically stable and the closed-loop cost function value is not more than a specified upper bound for all admissible uncertainties and controller gain variations. Sufficient conditions for the existence of such controllers are derived based on the linear matrix inequality (LMI) approach combined with the Lyapunov method. A parameterized characterization of the robust non-fragile guaranteed cost controllers is given in terms of the feasible solutions to a certain LMI. A numerical example is given to illustrate the proposed method.

• Journal of applied mathematics & informatics
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• 제9권1호
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• pp.61-76
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• 2002

The robust non-fragile guaranteed cost control problem is studied in this paper for class of uncertain linear large-scale systems with time-varying delays in subsystem interconnections and given quadratic cost functions. The uncertainty in the system is assumed to be norm-hounded arid time-varying. Also, the state-feedback gains for subsystems of the large-scale system are assumed to have norm-bounded controller gain variations. The problem is to design state feedback control laws such that the closed-loop system is asymptotically stable and the closed-loop cost function value is not more than a specified upper bound far all admissible uncertainties. Sufficient conditions for the existence of such controllers are derived based on the linear matrix inequality (LMI) approach combined with the Lyapunov method. A parameterized characterization of the robust non-fragile guaranteed cost contrellers is 7iven in terms of the feasible solution to a certain LMI. Finally, in order to show the application of the proposed method, a numerical example is included.

• 대한물리치료과학회지
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• 제2권3호
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• pp.645-651
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• 1995

The purpose of study was that the functional gains achieved by stroke patients after rehabilitation in the acute phase have been documented. Sixty stroke inpatients who were at least 3.57 month postonset participated;32 males and 28 females;mean age, 57.4 years. By the classification of diagnosis, 20 subjects were cerebral infarction and 27 subjects were cerebral hemorrhage. Activities of daily living(ADL) performance was investigated using the Klein-Bell ADL Scale. ADL test was practiced within physical therapy room. The outcome variables were first analyzed using frequency statistics. The functional gains of the patients with sex and hemiplegic site were then using an ANOVA. Mean score of dressing, elimination, mobility, bathing/hygiene, eating, and telephone use, 26.6, 56.0, 41.4, 36.5, 82.0, and 56.7. Mean score of total, 43.0. There was no significant difference in sex and hemiplegic site.

• 한국콘텐츠학회논문지
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• 제21권11호
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• pp.692-710
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• 2021

본 연구에서는 Brothers 등(2019)에 의해 개발된 노화인식 척도(Awareness of Age-Related Change Scale, AARC)의 한국판 타당화 작업을 수행하였다. 노인 당사자의 노화인식을 확인하기 위해 만 65세 이상의 노인 400명을 대상으로 연구를 수행하였다. 두 개의 표본(표본 1: 185명, 표본 2: 215명)을 대상으로 한국어로 번안한 노화인식 척도에 대해 탐색적 요인분석 및 확인적 요인분석을 시행하였다. 탐색적 요인분석에서는 손실 인식 요인은 건강 영역 손실 인식, 건강 외 영역 손실 인식의 두 가지 하위요인으로 구성되고, 이득 인식은 하위요인 없이 단일 요인으로 구성되는 것으로 나타났다. 확인적 요인분석 결과, 탐색적 요인분석 결과로 도출된 요인 구조가 경쟁모형보다 더 타당하였다. 또한 구성타당도를 검증하기 위해 노화태도와 상관분석, 정서경험에 대해 회귀분석을 수행하였다. 마지막으로 본 연구의 의의 및 활용방안을 논의하고, 한계 및 미래 연구를 위한 제언을 밝혔다.

• Journal of Communications and Networks
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• 제11권2호
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• pp.157-165
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• 2009

In this paper, we investigate a dynamic spectrum sharing problem for the centralized uplink cognitive radio networks using orthogonal frequency division multiple access. We formulate a large-scale joint rate and power allocation as an optimization problem under quality of service constraint for secondary users and interference constraint for primary users. We also suggest admission control to nd a feasible solution to the optimization problem. To implement the resource allocation on a large-scale, we introduce a notion of using the conservative factors $\alpha$ and $\beta$ depending on the outage and violation probabilities. Since estimating instantaneous channel gains is costly and requires high complexity, the proposed algorithm pursues a practical and implementation-friendly resource allocation. Simulation results demonstrate that the large-scale joint rate and power allocation incurs a slight loss in system throughput over the instantaneous one, but it achieves lower complexity with less sensitivity to variations in shadowing statistics.

• 한국경영과학회지
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• 제14권1호
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• pp.51-58
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• 1989

A joint economic ordering problem between supplier and customer has been formulated where a supplier has to pay the freight cost which follows the principle of economy of scale. An algorithm is given to determine order size and price simultaneously which give gains to both parties. A scenario is presented within which both parties come to a mutual agreement on the revised order size and price by utilizing quantity discount schedule.

• Journal of Power Electronics
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• 제16권3호
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• pp.1152-1162
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• 2016

The unequal impedances of the interconnecting cables between paralleled inverters in the island mode of microgrids cause inaccurate reactive power sharing when the traditional droop control is used. Many studies in the literature adopt low speed communications between the inverters and the central control unit to overcome this problem. However, the losses of this communication link can be very detrimental to the performance of the controller. This paper proposes an improved reactive power-sharing control method. It employs infrequent measurements of the voltage at the point of common coupling (PCC) to estimate the output impedance between the inverters and the PCC and then readjust the voltage droop controller gains accordingly. The controller then reverts to being a traditional droop controller using the newly calculated gains. This increases the immunity of the controller against any losses in the communication links between the central control unit and the inverters. The capability of the proposed control method has been demonstrated by simulation and experimental results using a laboratory scale microgrid.