• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.61-64
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• 2011

There are many applications that require robust and accurate eye tracking, such as human-computer interface(HCI). In this paper, a novel approach for eye tracking with a principal component analysis on rotated face. In the process of iris detection, intensity information is used. First, for select eye region using principal component analysis. Finally, for eye detection using eye region's intensity. The experimental results show good performance in detecting eye from FERET image include rotate face.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.117-126
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• 2010

In order to obtain more clear x-ray images, an antiscatter grid, which can absorb the scattered rays, is employed. In the high-resolution direct digital radiography, however, the artifacts due to the grid are visible. In this paper, the grid artifacts are reduced by applying simple 1-dimensional low-pass filters in the spatial domain based on the rotated grid. Since the proposed algorithm does not use any detection scheme for the artifact frequencies and discrete Fourier transforms for 2-dimensional filters, it can simply and fast reduce the grid artifacts. The performance using the order 1 average filter is compatible to that of using 2-dimensional filters in the frequency domain.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.8-14
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• 2020

In the air current pulverizing type grinding method, the blade wings fitted inside a casing are rotated at a high speed to generate a cornering air current, which facilitates the collision of materials with one another, leading to the pulverizing phenomenon. In contrast to mechanical grinding, grit pulverizing leads to fine grinding and less acid waste and degeneration of the material. Moreover, this approach prevents the loss of nutritional value, while allowing the milling grain to have an excellent texture. However, the existing air current pulverizing type machines consist of prefabricated blades, which cannot be rotated at a speed higher than 5,000 rpm. Consequently, the grinding process becomes time consuming with a low productivity. To overcome these problems, in this study, the shape and structure of the air current pulverizing type wings were optimized to allow rapid grinding at more than 8,000 rpm. Moreover, the optimal design for the ripening parts for the air current pulverizing type device was determined by performing a computational fluid dynamics analysis based on airflow analyses to produce machinery that can grinding materials to the order of micrometers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.681-687
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• 2001

Two-phase cross-flow exists in many shell-tube heat exchangers such as steam generators, condensers and reboilers. An understanding of flow-induced vibration excitation mechanism is necessary to avoid problems due to excessive tube vibration. This paper presents the results of a series of experiments done on tube bundles of different geometries subjected to two-phase cross-flow simulated by air-water mixtures. Normal(30$^{\circ}$) and rotated (60$^{\circ}$)triangular, and normal(90$^{\circ}$) and rotated (45$^{\circ}$) square tube bundle configurations of pitch-to-diameter ratio of 1.2 to 1.5 were tested over a range of mass fluxes from 0 to 1,000kg/$m^2$ㆍ s and void fraction from 0 to 100%. The effects of tube bundle geometry on vibration excitation mechanism such as fluidelastic instability and random turbulence, and on dynamic parameters such as damping and hydrodynamic mass are discussed. A lower pitch-to-diameter results in a higher hydrodynamic mass. The effect of tube bundle configurations on damping and random turbulence excitation is minor. The effect of pitch-to-diameter on the fluidelastic instability, however, is significant.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.784-785
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• 2008

In general, in most case of high temperature superconducting (HTS) rotating machinery, HTS field coil is rotated. HTS homopolar motor field coil is nat necessary to be rotated and the torque of motor is not strongly related with the field coil. Therefore, HTS homopolar motor has a superior mechanical stability comparing with other HTS rotating machines. These advantages can make the design of HTS field coil and cryostat much more simple. In this paper, HTS field coil was fabricated and tested. Before test, authors habe estimated the critical current of HTS field coil at 77K by simulation using FEA (Finite Element Analysis) software and power law equation. The experiment details and results are presented in this paper, and discussed. The field windings are made with HTS Bi-2223 wire which operates at 77K.

• Journal of Information Processing Systems
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• v.9 no.3
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• pp.349-364
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• 2013

The big challenge in current content-based image retrieval systems is to reduce the semantic gap between the low level-features and high-level concepts. In this paper, we have proposed a novel framework for efficient image retrieval to improve the retrieval results significantly as a means to addressing this problem. In our proposed method, we first extracted a strong set of image features by using the dual-tree rotated complex wavelet filters (DT-RCWF) and dual tree-complex wavelet transform (DT-CWT) jointly, which obtains features in 12 different directions. Second, we presented a relevance feedback (RF) framework for efficient image retrieval by employing a support vector machine (SVM), which learns the semantic relationship among images using the knowledge, based on the user interaction. Extensive experiments show that there is a significant improvement in retrieval performance with the proposed method using SVMRF compared with the retrieval performance without RF. The proposed method improves retrieval performance from 78.5% to 92.29% on the texture database in terms of retrieval accuracy and from 57.20% to 94.2% on the Corel image database, in terms of precision in a much lower number of iterations.

• Journal of Korean Society of Steel Construction
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• v.8 no.4 s.29
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• pp.3-17
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• 1996

The purpose of this paper is to investigate experimentally and theoretically the strength and deformation of K-joints in welded Warren-type square hollow structural section truss. There are 2 types in K-joints in K-joints having one compression bracing member and one tension bracing member. One type is KP-series that brae members are rotated to $45^{\circ}$, another type is KS-series that are not rotated. Principal parameters are the ratio of the chord width to thickness (D/T=33.3, 25, 16.7), the ratio of brace width to chord width(d/D=0.4, 0.5, 0.67, 0.83, 1.0) and the ratio of eccenticity to chord height (e/D=0.25, 0.125, 0, -0.125, -0.25, -0.375, -0.5). The important results obtained from the experiments are as follow ; The strength of K-joints increase proportionally as the D/T ratio decreases, and the d/D ratio increases. But the e/D ratio has no correlation with the strength of K-joints. Generally the strength and ductility ratio of KP-series increase more than a current type(KS-series) in full ${\beta}$range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.805-814
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• 1998

An efficient image processing algorithm is proposed to recognize both the height and width modulated barcodes which are rotated and printed at an arbitrary position. The main feature of this algorithm is to utilize the gradient information of a rotated barcode with a Sobel operator. The barcode area is extracted using the gradient information, and the barcode is decoded from the binary image of the extracted area. Theis algorithm is successfully applied to the 4 state and width modulated barcodes. It takes 0.86 secoden to process a letter, and the recognition rate reaches above 98% under various testing conditions. Since both the width and height modulated barcodes are processed with the proposed algorithm, it can be applied to postal service automation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.54-62
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• 2015

This paper describes the design and fabrication of an electronically rotated Tactical Air Navigation(TACAN) antenna using parasitic elements and PIN diode switches. We used parasitic elements arranged in a circular array and PIN diode switches to electronically rotate the antenna instead of employing a mechanically rotated antenna using motor. The antenna's physical characteristics and design features to generate the cardioid pattern and nine-lobe pattern including bearing information are described and simulated. The measured result shows a very good agreement with simulation and meets the specification of MIL-STD-291C.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.16-23
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• 2018

PM synchronous motor may be rotated to an arbitrary direction and speed by outside wind under natural condition in cases where the fan is applied outside, such as in vehicle radiators and outdoor air-conditioners. Sensorless controls that cannot detect rotor position requires additional sensorless control algorithm because a rotor is rotated by an external load. In this study, the sensorless control of a PM synchronous motor under naturally rotating condition is proposed. The natural rotation conditions are classified as forward high-speed rotation, reverse high-speed rotation, and low-speed rotation. Experiment results verify the performance of the sensorless control, including the rotor speed and position detection at natural rotation mode and switch to the closed-loop sensorless control.