• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.40.1-40.1
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• 2011

This paper presents a pitch controller which can hold output power constant at the rated value. Although wind turbine contains complicated nonlinearities, its behaviour within a certain operating range of a point can be approximated by that of a linear model. By doing so, we can apply rather simple and systematic linear control techniques such as PID and LQR(Linear Quadratic Regulator) to design a linear pitch controller. Because these linear controllers are valid only in a sufficiently small range around an operating point, linearized wind turbine model under the condition of varying wind speed needs a linear pitch controller can achieve the aims of tracking the rated rotor rotational speed. We propose an improved linear pitch controller taking each merit of LQR and PI controller under the condition of varying operating points in this paper.

• 대한통합의학회지
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• 제4권4호
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• pp.83-90
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• 2016

Purpose : Recommended posture according to the location of operating teeth have been standardized in dental clinic to prevent musculoskeletal disorder. However, clinicians do not comply with this rule in many cases. This study investigated the effects of operating posture on cranio-cervical range of motion (CROM) and muscles activity of neck and upper extremity. Methods : Sixteen healthy dental hygiene students were participated. During operating posture (3 recommended and 3 experimental postures which were set front, side, back, respectively), CROM in the fronal and sagittal plane were measured by Cervical Range of Motion Instrument and muscle activities of Sternocleidomastoid, upper trapezius, middle deltoid, extensor carpi radialis, brachioradialis, and abductor pollicis brevis were measured by Pocket EMG system. Result : CROM were significantly decreased in recommended posture in comparison with experimental posture (p<.05). In addition, muscle activity of middle deltoid was significantly decreased in recommended front posture. Moreover, brachioradialis and extensor carpi radialis showed the same result in recommended back posture (p<.05). Conclusion : Recommended posture is close to neutral posture and to reduce muscle fatigue and overuse, which may considered as a preventing musculoskeletal disorder and partially explain its efficacy in dental clinic.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.160-165
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• 2004

MPA (Multi-Point Averaging) flow element is a new type of differential pressure (DP) flow-sensing device that was developed by Seojin Instech to improve the operating characteristics of the conventional Averaging Pilot Tube (APT) flow elements. Operating characteristics of a flowmeter in general can be defined in terms of measurement accuracy and range. Improvement of accuracy and expanding the range of flow measurement were the two main objectives of the development. To achieve these dual objectives several upstream and downstream pressure-sensing holes were placed in MPA flow element. During the course of the development it was found that certain arrangements of the pressure-sensing holes improved measurement accuracy but did not expand operating flow range of Averaging Pilot Tubes. Development tests were performed with water between Reynolds number of 50,000 and 1,000,000 in the four-inch test line at the Alden Research Laboratory, U.S.A. Purpose of this paper is to present the relationship between the various locations of the pressure-sensing holes and the performance characteristics of MPA flow element. Furthermore, the operating characteristics of the best performing MPA are compared with those of typical orifice and APT.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.68-71
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• 2007

A computational study has been performed using a chimera scheme to study the various operating processes inside a ballistic range. The compression flow fields in the pump tube and projectile motion in the launch tube are captured for various piston masses and diaphragm rupture pressures. The effect of a shock tube in between the pump tube and launch tube is analyzed. The results are compared with available experimental data. It is noted that, by adding a shock tube in between the pump tube and launch tube, the peak pressure in the ballistic range can be reduced without appreciable reduction in the velocity of the projectile.

• Journal of Advanced Marine Engineering and Technology
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• 제26권3호
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• pp.313-319
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• 2002

Since the oil crisis in 1970, a great deal of effort has been made to develop automatic electric load sharing systems as a part of the efforts to save energy. A large scale electric generating system composes more than two generators whose characteristics may be different. When such a system is operated individually or in parallel, the lagrange multiplier's method has difficulty in achieving optimal load distribution because generators usually have the limitations of the operating range with inequality constraints. Therefore, a suitable operating mode of generators has to be decided according to the selection of the generators to meet electric power requirements at the minimum cost. In this study, a method which solves the optimal electric load distribution problem using the dynamic programming technique is proposed. This study also shows that the dynamic programming method has an advantage in dealing with the optimal load distribution problem under the limitations of the operating range with inequality constraints including generator operation mode. In this study, generator operating cost curve of second order equation by shop trial test results of diesel generators are used. The results indicate that the proposed method can be applied to the ship's electric generating system.

• 대한건축학회논문집:계획계
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• 제34권8호
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• pp.43-50
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• 2018

The purpose of this study is to analyze the effect of architectural attributes on operating revenue by concentrating on the facility side and to investigate how much individual architectural factors can affect operating revenue. The time range of this study is limited to 2015, and the spatial range is limited to a tourist hotel in Seoul that can be easily surveyed and verified. The analysis method is to confirm the significance and influence of each attribute through regression analysis. According to the results, The room part such as number of rooms or area showed a relatively low correlation with "revenue per available room (Rev.PAR)" than "average daily rate (ADR)", but showed a high correlation with non - architectural attributes such as auxiliary facilities and chain. This shows that factors that influence the operating profit of hotel are not the part of the room but the other factors such as the auxiliary facilities work more. In addition, the presence of spa and the number of auxiliary facilities in the hotel have a positive effect on the operating profit of the hotel due to the non - architectural attributes. This is expected to provide a new direction for future research in studying hotel facilities.

• 한국컴퓨터정보학회논문지
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• 제21권3호
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• pp.91-96
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• 2016

We have surrounded undesired living noises in our life. One of biggest noises coming out of range hood during cooking in the kitchen. A range hood is one of the most important appliances in the kitchen because it ventilates polluted air out during cooking, and maintains air quality in the kitchen. But current kitchen range hoods bring up some issues; First, the range hoods consume massive amount of standby power not in use condition. Second, current models have designed manual fan operating system with sudden onset of noise with starting. In this paper, we propose an auto control system entire processes from air ventilation to noise reduction. Our system is consist of three parts (Eco-sensors pack, Main Controller and Active Noise Controller); Eco-sensors pack detects air pollution of kitchen areas and sends the detection values to Main Controller. Main Controller determines operation of range hood by detected values. Active Noise Controller is located inside of the range hood. It received starting signals from Main Controller which elicits degrees of polluted air condition and fan operating speed from 1 to 3. Once Active Noise Controller detected the signals, it runs a ventilating fan until new value from Main Controller becomes 0. while the range hood works, A noise cancellation algorithm inside of Active Noise Controller become activated to reduce levels of noise. As a result, the proposed system clearly shows reduction in power consumption include standby power and decreases in levels of noise.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2098-2100
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• 1997

The present paper investigates the optimal operation of a switched reluctance motor such that overall drive efficiency is maximized under a variable supply voltage. The operation under a variable supply voltage exhibits the improved drive efficiency in the full range of operating torque and speed, and exhibits the expanded range of operating torque and speed. Furthermore a variable supply voltage may be utilized in reducing torque ripple.

• Journal of Power Electronics
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• 제9권5호
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• pp.772-780
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• 2009

A novel soft-switching two-switch flyback converter is proposed in this paper. This converter is composed of two active power switches, a flyback transformer, a blocking diode, and two passive regenerative clamping circuits. The proposed converter has the advantages of a low cost circuit configuration, a simple control scheme, a high efficiency, and a wide operating range. The circuit topology, analysis, design considerations, and experimental results of the new flyback converter are presented.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.133-142
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• 1992

A kineamatic nonlinear multivariable laundher is modeled of which the azimoth and elevation axes are drived simultaneously and SISO and MIMO LQG/LTR controllers are designed and evaluated for this system. Also, the suitable command input function is suggested for the desired command following performance and the LQG/LTR control system with disturbances and load variation is evaluated for the entire operating range by computer simulation. It is found that the linear SISO LQG/LTR controller can be used for the kinematic nonlinear multivariable launder in the entire operating range and is effective for disturbance rejection and load variation.