• 제어로봇시스템학회논문지
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• 제20권9호
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• pp.895-899
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• 2014

This paper presents the balancing control of a unicycle robot using air power. Since the robot has one wheel to move forward and backward, the balancing control is quite challenging. To control the balancing angle, the accurate angle estimation by a tilt and a gyro sensor is required a priori. A complementary filter is implemented to eliminate the defects of two sensors and to fuse together to estimate an accurate balancing angle. The optimal design of air ducts is found empirically. Experimental studies of the balancing control of a unicycle robot confirm that the robot is well regulated without falling down.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.103-108
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• 2001

The structure of hard disk drive(HDD) is excited by dynamic motion of a disk-spindle motor, and it makes sound noise. Therefore, the cover and the base of HDD should be designed to reduce noise and vibration induced by spindle motor. The prediction technique of sound pressure level(SPL) of a given structural shape enables us to design a cover and a base with much less vibration and noise. In this paper, we measured the force of disk-spindle motor and predicted SPL from HDD by computational simulation. To get a SPL of HDD by computational simulation, modal analysis and forced vibration analysis were performed with ANSYS, and sound radiation was computed using SYSNOISE. The calculated results were compared with experimental results and a good agreement was obtained. With this computer simulation procedure and design of experiment(DOE), optimal thickness of noise barrier and damper was calculated.

• 소음진동
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• 제7권2호
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• pp.301-310
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• 1997

This paper presents active noise control method to form the near-field quiet zone for passengers in an automobile. The actuator model including interior acoustic plant, speaker and amplifier is experimentally identified in forms of auto-regressive and moving average by means of least mean square algorithm, The digital controller is composed of the regulator and Kalman filter to be designed based on LQG (linear quadratic gaussian). If the actuator model is prefiltered with digital filter to be properly designed for concentrating control performance index on the frequency band of primary noise source, LQG design approach can be effectively applied for the design of headset controller. Experimental results demonstrate that near-field quiet zone showing about 10dB noise reduction at microphone position can be formed using the headset located at passenger seat.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.627-630
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• 2003

This work presents a numerical procedure to optimize the shape of three-dimensional channel with angled ribs mounted on one of the walls to enhance turbulent heat transfer. The response surface method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of flow and heat transfer. SST turbulence model is used as a turbulence closure. The width-to-height ratio of the rib, rib height-to-channel height ratio, pitch-to-rib height ratio and attack angle of the rib are chosen as design variables. The objective function is defined as a linear combination of heat-transfer and friction-loss related terms with weighting factor. D-optimal experimental design method is used to determine the data points. Optimum shapes of the channel have been obtained for the weighting factors in the range from 0.0 to 1.0.

• 대한조선학회논문집
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• 제33권2호
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• pp.36-43
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• 1996

현재 전 세계적으로 해상교통의 주역이 되리라고 생각되는 고속선에 대한 시험 연구를 수행하였다. 본 논문은 주행중 고속선에 가장 문제가 되는 파도중의 운항자세를 제어하는 시험을 수행한 결과이다. 선형은 카타마란 선형을 선택하였으며, 운항자세를 제어하기 위하여 선수와 선미부분에 제어판을 장치하였다. 자세제어 시스템으로는 제어판과 제어판 구동장치, 운동 계측장비로 되어있으며, 운동 계측장비로부터 데이타를 취득하고, 제어판 구동장치로 신호를 보내기 위하여 A/D, D/A보드를 각각 1장씩 사용하였다. 이 장비를 이용하여 규칙 정면파중의 고속선의 운항자세를 제어하는 시험을 수행하였으며, 실험결과로부터 자세제어 시스템이 작동하지 않을 때와 작동할 때의 차이를 비교하였다. 비교결과 종동요(Pitch)는 진폭이 많이 감소하였으나, 상하동요(Heave)는 많이 감소하지 않았다.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.578-584
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• 2019

The occurrence of white plume in the cooling tower is phenomenon that the steam in the air through the cooling tower fan is condensed again by the cold ambient air to become saturated moist air. Accordingly, this can cause many problems like spoiling landscape around the cooling tower, odor of ambient air, falling accident by frozenness in the winter, and traffic accident, etc. This study was to install the heat exchanger in the inside of the cooling tower in order to prevent the white plume phenomenon in the cooling tower without affecting the performance of cooling tower. In addition, this study was to discharge the part of cooling water into the atmosphere through the recirculation of heat exchanger after creating dry air by heating the saturated moist air to the dew point temperature. At that time, this study was to conduct the experimental study in order to secure the optimal design data to prevent the white plume in the cooling tower because it checked the dry·moist temperature and relative humidity in the inside·outside of cooling tower on the moist air, and evaluated the performance of the heat exchanger.

• ETRI Journal
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• 제46권3호
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• pp.404-412
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• 2024

We propose a method for increasing the bandwidth of a substrate-integrated-waveguide (SIW) cavity-backed antenna with taper-based micro-strip SIW transition feeding. For radio transmission, a circular slot is etched on top of the SIW cavity. For optimal antenna design, the slot is etched slightly away from the cavity center to generate circularly polarized waves. Simulations show a wide axial ratio bandwidth of 7.860% between 11.02 GHz and 11.806 GHz. Experimental results confirm a similar wide axial ratio bandwidth of 4.9% between 10.8 GHz and 11.35 GHz. An SIW feed from an inductive window excites the radiating circular slot, resulting in a simulated wide impedance range of 1.548 GHz (10.338 GHz-11.886 GHz) and bandwidth of 13.93%. Experimental results show a wide impedance of 2.08 GHz (10.2 GHz-12.08 GHz) and bandwidth of 18.84%. The SIW cavity-backed antenna creates a unidirectional pattern, leading to gains of 6.61 dBi and 7.594 dBi in simulations and experiments, respectively. The proposed antenna was fabricated on a Rogers RT/Duroid 5880 substrate, and the reflection coefficient, radiation patterns, and gains were tested and compared using a computer simulator. The developed broadband antenna seems suitable for X-band applications.

• 한국환경과학회지
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• 제29권8호
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• pp.793-800
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• 2020

The conventional development of multi-component electrodes is based on the researcher's experience and is based on trial and error. Therefore, there is a need for a scientific method to reduce the time and economic losses thereof and systematize the mixing of electrode components. In this study, we use design of mixture experiments (DOME)- in particular a simplex lattice design with Design Expert^Ⓡ program- to attempt to find an optimum mixing ratio for a three-component electrode for the high RNO degradation; RNO is an indictor of OH radical formation. The experiment included 12 experimental points with 2 center replicates for 3 different independent variables (with the molar ratio of Ru, Ti, Ir). As the Prob > F value of the 'Quadratic' model is 0.0026, the secondary model was found to be suitable. Applying the molar ratio of the electrode components to the corrected response model results is an RNO removal efficiency (%) = 59.89 × [Ru] + 9.78 × [Ti] + 67.03 × [Ir] + 66.38 × [Ru] × [Ir] + 132.86 × [Ti] × [Ir]. The R² value of the equation is 0.9374 after the error term is excluded. The optimized formulation of the ternary electrode for an high RNO degradation was acquired when the molar ratio of Ru 0.100, Ti 0.200, Ir 0.700 (desirability d value, 1).

• 소성∙가공
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• 제13권7호
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• pp.635-641
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• 2004

Today the specific outputs of modern supercharger DI diesel engine for passenger cars reach values exceeding 50kw/1. By development of the articulated piston, specific output of up to 70kw/1 are sought. In doing so, peak cylinder pressure increases from the current 14-16MPa to 18-20MPa. The Articulated piston was composed Al cast skirt part and steel forged crown part. We have the target fer the design of forging process and die of the steel forged crown part. The design parameters of the forging process of the piston were obtained by the forging industry experiences and our experimental data and analysis result of finite element simulation. Especially, the design parameter of preform in blocker die was decided by finite element simulation using numerical package DEFROM3D. And also we can verify the design parameter by conducting visio-plasticity test using plasticine material. When we compared the results of analysis and experiment, a metal flow and load curve showed good agreement. Through this research, we could design optimal preform shape of articulated piston for this supercharged DI diesel engine.

• 응용통계연구
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• 제20권2호
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• pp.267-280
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• 2007

혼합물 성분들의 비율의 상한과 하한에 대한제한조건이 부과된 제한된 혼합물 실험 공간 R에서의 혼합물 실험을 위한 최적 설계를 찾는 데에 D-, G-, V- 최적기준 등과 같은 다양한 최적 설계 기준이 사용된다. 각각의 실험 설계는 선택된 최적 기준에 대해서는 최적이지만, 제한된 혼합물 실험 공간에서의 예측력에 대해서는 만족스럽지 못하다는 것은 잘 알려진 사실이다. (Vining 등, 1993; Khuri 등, 1999). 우리의 관심사는 2차 혼합물 반응표면모형을 가정한 경우에 제한된 혼합물 공간에서의 효율적인 실험 설계를 찾는 것이다. 이 논문에서는 꼭지점, 선중심점, 면중심점, 중앙점과 내부점으로 구성된 확장된 후보 실험점 그룹을 구성한 다음에, D-최적기준, G-최적기준, V-최적기준과 실험점들 간의 거리에 근거한 U-최적기준에 강건한 실험 설계를 제안한다. Khuri 등(1999)에서 분석된 비료 혼합물 실험과Vining과 Cornell(1993)이 분석한 조명탄 혼합물 실험의 사례에서 강건한 실험설계들과 두 논문에서 추천된 실험 설계들에 대한 예측치의 표준화된 분산의 분위수의 그림(SVPQP)을 비교한 결과 강건한 설계가 상대적으로 우월함이 판명되었다.