• Journal of Microbiology
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• v.40 no.2
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• pp.104-108
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• 2002

The hazelnut leaf holer (Anoplus roboris Sufr,, Coleoptera: Curculionidae) is a devastating pest of hazelnut and oak trees. It causes approximately 20-30% economic damage to hazelnut production per year in Turkey. In the present study, in order to fond a more effective and safe biological control agent against A. roboris, we investigated the bacterial flora of the hazelnut leave holer, and tested them for insecticidal effects on it. According to morphological, physiological and biochemical tests bacterial flora were identified as Bacillus circulans (Ar1), Bacillus polymyxa (Ar2), Enterobacter sp. (Ar3) and Bacillus sphaelicus (Ar4). Insecticidal effects of bacterial isolates were performed on adult A. roboris. The highest insecticidal effect determined was 67% by B. sphaericus within eight days. The insecticidal effects of the other isolates (Ar1, Ar2 and Ar3) were determined as 33%, 47% and 47% within the same period, respectively.

• 전기의세계
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• v.17 no.4
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• pp.7-12
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• 1968

In recent years the development of the SCR has made possible the control of the power system. It is one example that the speed control of the induction motor can be done by changing the frequency with the S.C.R. This paper is devoted primarily to a study of the running characteristics of the single phase induction motor through the experimental and theoretical methods when the speed of the motor is controlled by varying the conduction period in current with S.C.R. under the constant frequency. We conclude from the experiments that the adjustment of the phase angle in current is equivalent to the change of the supply voltage to the motor. Therefore, the speed control of the motor such as a fan duty motor is possibly by this methods.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.8
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• pp.440-447
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• 1999

This paper proposes a control method for three-phase PWM rectifier with only single current sensor in DC link side. A PWM modulation strategy for reconstructing three phase currents from the DC link current is given. The states of the retifier switch are modified so that all phase currents can be reconstructed in a switching period although one or two of active vectors is applied only for a short time. Therefore, a new current control using an adjustment scheme of the modulation signal for three-phase PWM rectifier will be discussed, and verified the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.501-510
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• 1996

The gas-turbine generator of Seo-Incheon combined-cycle plant was tested for derivation of a model for dynamic analysis. Load rejection and AVR step test was performed to get the dynamic response of generator. The parameters of generator/control system model were determined by these measured data. No-load saturation test was performed for the saturation characteristics of the generator under steady state. V-curve test was also performed so as to find exact generator parameters. Q-axis parameters of generator was derived by measuring power angle. AVR and governor constants have been tuned by their oscillatory period and setting time characteristics. The derived parameters of generator control system is verified by one-machine infinite bus system simulation. (author). 7 refs., 20 figs., 5 tabs.

• Journal of Power Electronics
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• v.13 no.3
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• pp.409-418
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• 2013

This paper presents an enhanced control strategy which consists of a proportional-integral controller and a repetitive controller (RC) for improving the voltage performance of distributed generation (DG) under nonlinear load conditions. The proposed voltage controller is able to maintain a sinusoidal voltage at the point of common coupling (PCC) of the DG regardless of the harmonic voltage drop in the system impedance due to nonlinear load currents. In addition, by employing the delay time of the RC at one-sixth of the fundamental period, the proposed RC can overcome the slow response drawback of the traditional PI-RC. The proposed control strategy is analyzed and the design of the RC is presented in detail. The feasibility of the proposed control strategy is verified through simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.294-295
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• 2017

태양광발전시스템은 설비 사용률을 최대화하기 위하여 PV 모듈을 최대 전력점에서 운전하는 MPPT(Maximum Power Point Tracking) 제어가 반드시 필요하다. 기존의 MPPT 알고리즘은 경사법에 기반을 두기 때문에 일정한 MPPT 주기마다 일정한 크기의 PWM Duty 비의 자극을 주고, 그에 따른 출력 전력의 변화를 감지하여 최대 전력점을 향한 다음 운전점을 찾는다. 이러한 MPPT 알고리즘을 실제 날씨 환경에 적용할 때 최대전력을 생산하기 위한 최적의 MPPT 주기와 PWM Duty 비의 변량은 다양한 일사량의 프로파일 형태에 따라 달라진다. 그러므로 최적의 MPPT 주기와 PWM Duty 비의 변량을 결정하기 위해서는 실제 날씨 환경에서 다양한 일사량 프로파일의 패턴에 대한 분석이 필수적이다. 본 논문에서는 대한민국 중부지역의 전형적인 맑은 날씨와 흐린 날씨에서 실제 일사량을 측정, 분석하여 MPPT 목표 효율을 최대화할 수 있는 MPPT 주기를 제시하였다.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.3
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• pp.216-228
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• 2011

A logistics system involving a supplier who produces and delivers a single product and a buyer who receives and sells the product to the final customers is analyzed. In this system, the supplier and the buyer establish a contract which specifies that the supplier will deliver necessary amount of the product to raise inventory up to a specified position at the beginning of each period. A new periodic order-up-to-level inventory control policy specifically designed for nonstationary end customer's demand is proposed for the system. Simulations are used to test the efficiency of the proposed policy. An analysis of the test results reveals that the proposed policy performs much better than does the existing order-up-to-level policy, especially when the demand is nonstationary.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.556-558
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• 2008

Secure broadcasting is requirement for payment of TV systems, government or company. Hierarchical key management for access control provides efficient key management in those environment. Also, time-bound hierarchical key management technique generates different keys in each time period. In 2004, Tzeng proposed a time-bound cryptgraphic key assignment scheme for access control in a hierarchy and in 2008, Bertino et al proposed an efficient time-bound hierarchical key management scheme for secure broadcasting. Tzeng's scheme and Bertino et al's scheme are organized in different environment and primitive. In this paper, we analysis above two time-bound hierarchical key management scheme.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.18-20
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• 1994

The cogeneration system has a advantage of producing electrical and thermal energy simultaneously. therefore, this system is encouragable to the business proprietor and the nation like us which has the problem of limited energy. Presently, there is a few cogeneration system for new city and industrial complex. But the building cogeneration system is dull in application because of legal limitation and poor tax support. In this paper, we simulate economic propriety of the building system under the support which is applied to industrial system. And we simulate the effect of each support item on the economic propriety in aspect of payback period.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.55-58
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• 2002

To control the frost formation, a temperature variation of the cooling plate and characteristics on hydrophilic and hydrophobic surfaces was attempted. As a temperature variation of the cooling plate, being closely related to the frost layer density of frost layer is found to be affected by the melting process inside the frost layer during the heating period. At characteristics on surface, completely different structures of frost are appeared in the initial stage of frost formation due to the difference in surface conditions, while those effects are vanished with time. It is found that the frost thickness, density and heat flux characteristics are closely associated with the frost structure.