• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4759-4780
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• 2017

Full Dimension multiple input multiple output (FD-MIMO) architecture employs a planar array design at the Base Station (BS) to provide high order multi-user MIMO (MU-MIMO) via simultaneous data transmission to large number of users. With FD-MIMO, the BS can also adjust the beam direction in both elevation and azimuth direction to concentrate the energy on the user of interests while minimizing the interference leakage to co-scheduled users in the same cell or users in the neighboring cells. In a typical highly populated macrocell environment, modelling the elevation angular characteristics of three-dimensional (3D) channel is critical to understanding the performance limits of the FD-MIMO system. In this paper, we study the throughput performance of FD-MIMO system with varying elevation angular spread and inter-element spacing using a 3D spatial channel model. Our results show that for a typical urban scenario, horizontal beamforming with correlated antenna spacing achieves optimal performance but by restricting the spread of elevation angles of departure, elevation beamforming achieves high array gain with wide inter-element spacing. We also realize significant gains due to spatial array processing via modelling the elevation domain and varying the inter-element spacing for both the transmitter and receiver.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.71-78
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• 2014

Method a target estimation in spatial are mobile wireless communication using network cell and GPS. It have much error that mobile wireless communication depend on cell size. GPS method can't find a target in shadow and inner area. In this paper, we estimate a target as direction of arrival method using adaptive array antenna system. Adaptive array antenna system can obtain desired signal to remove other signal This paper studied digital beamforming method in order to estimation a target. Proposed method is modified optimum weight and antenna error correction to estimation an optimal receive signal. Digital beamforming method decided a signal phase and amplitude from received signal on array antenna element. But if it is not to do error correction of received signal, system performance have decreased. Firstly, we proposed modified optimum weight in order to finding desired target. Secondly, we are error correction of antenna incident signals by optimal weight before digital beamforming method. Thirdly, throughly simulation, we showed that system performance of proposed method compare proposal method with general method. It have improved resolution of estimation target to good performance more proposed method than general method.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.63-70
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• 2014

Method a target estimation in spatial are mobile wireless communication using network cell and GPS. It have much error that mobile wireless communication depend on cell size. GPS method can't find a target in shadow and inner area. In this paper, we estimate a target as direction of arrival method using adaptive array antenna system. Adaptive array antenna system can obtain desired signal to remove other signal This paper studied digital beamforming method in order to estimation a target. Proposed method is modified optimum weight and antenna error correction to estimation an optimal receive signal. Digital beamforming method decided a signal phase and amplitude from received signal on array antenna element. But if it is not to do error correction of received signal, system performance have decreased. Firstly, we proposed modified optimum weight in order to finding desired target. Secondly, we are error correction of antenna incident signals by optimal weight before digital beamforming method. Thirdly, throughly simulation, we showed that system performance of proposed method compare proposal method with general method. It have improved resolution of estimation target to good performance more proposed method than general method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.71-74
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• 2001

Using the Taguchi method, optimum process condition of lead frame blanking has been determined in the point of view of shape of blanked profile. As the main process parameters, clearance, strip holding pressure and bridge width are selected. According to the orthogonal array table, three levels of experiment have been carried out for each factors. The optimal blanking condition is analyzed with the SN ratio. It has been verified that the optimal process condition can be determined with a combination of basic blanking experiment and experiment design method. Both the effect of each factors and gain can be judged in the quantitative manners from the analysis of SN ratio.

• Transactions of Materials Processing
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• v.11 no.2
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• pp.132-137
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• 2002

Using the Taguchi method, optimum process condition of lead frame blanking has been determined in the point of view of shape of blanked profile. As the main process parameters, clearance, strip holding pressure and bridge width are selected. According to the orthogonal array table, three levels of experiment have been carried out for each factor. The optimal blanking condition is analyzed with the SN ratio. It has been verified that the optimal Process condition can be determined with a combination of basic blanking experiment and experiment design method. Both the effect of each factor and gain can be judged in the quantitative manner from the analysis of SN ratio.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.11 s.170
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• pp.1871-1877
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• 1999

An optimal design method using a response surface method for dynamic characteristics of a washer is presented. The proposed method uses the design of experiment and a computer model is used for the experiment. The value of the cost function is estimated using a computer model for each case of the design variable variation. An orthogonal array is used to obtain best cases to be considered with minimum number of experimentation. Using these experimental values, optimal design is performed using a response surface method. The method used in this paper can be applied to any complicated mechanical systems that can be modelled and analyzed by a computer program. The method is applied to the design of dynamic characteristics of a washer.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.295-300
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• 2010

Inconel 718 alloy, widely used as material of aircraft engine, has a good mechanical property in high temperature, strong anti-oxidation characteristics in oxidated current over $900^{\circ}C$, and also is not easily digested in the air containing sulfur, therefore, its usage as mechanical component is expanding rapidly. Even though Inconel alloy 718 is difficult to machine, it requires highly precise processing/machining to sustain its component quality of high accuracy. In this paper, general turning operation conditions arc tested to select the best cutting process condition by measuring surface roughness through implementing experiments with orthogonal array of cutting speed, feeding speed and cutting depth as processing parameters based on the Taguchi method. Optimal turning operation conditions are extracted from the proposed experimental models.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.4
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• pp.48-53
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• 2009

Inconel 718 alloy, widely used as material of aircraft engine, has a good mechanical property in high temperature, strong anti-oxidation characteristics in oxidated current over $900^{\circ}C$, and also is not easily digested in the air containing sulfur, therefore, its usage as mechanical component is expanding rapidly. Even though Inconel alloy 718 is difficult to machine, it requires highly precise processing/machining to sustain its component quality of high accuracy. In this paper, general turning operation conditions are tested to select the best cutting process condition by measuring surface roughness through implementing experiments with orthogonal array of cutting speed, feeding speed and cutting depth as processing parameters based on the Taguchi method. Optimal turning operation conditions are extracted from the proposed experimental models.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1
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• pp.40-45
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• 1996

In this paper, a nonlinear optimal design technique is presented to find an optimal beam pattern. With this technique, the beam width is minimized with respect to a given maximum allowable side-lobe level considering the self- and mutual radiation impedances of vibrators. The proposed method is applied to design a planar array consisting 37 vibrators which are symmetric in X, Y and $45^{circ}$ axes. The results show that significantly low side-lobe level maintaining a main beam width can be obtained using this method.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.7
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• pp.50-61
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• 1999

\In this paper, we consider the optimal scheduling of detection and tracking parameters in phased array radars to minimize the radar energy required for track maintenance in a cluttered environment. We develop a mathematical model of target detection induced by a search process in phased array radars. In the mathematical development, we take into account the effect of unwanted measurements that may have originated from clutter or false alarms in the detection process. We use and analytic approximation of the modified Riccati equation of the probabilistic data association (PDA) filter to take into account the effect of clutter interference in tracking. Based on the search process and the tracking models, we formulate the optimal scheduling problem into a nonlinear optimal control problem. We solve a constrained nonlinear optimization problem to obtain the solution of the optimal control problem.