• The KIPS Transactions:PartB
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• v.14B no.7
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• pp.473-480
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• 2007

Feature tracking in video frame sequences has suffered from the instability and the frequent failure of feature matching between two successive frames. In this paper, we propose a robust 2D feature tracking method that is stable to long video sequences. To improve the stability of feature tracking, we predict the spatial movement in the current image frame using the state variables. The predicted current movement is used for the initialization of the search window. By computing the feature similarities in the search window, we refine the current feature positions. Then, the current feature states are updated. This tracking process is repeated for each input frame. To reduce false matches, the outlier rejection stage is also introduced. Experimental results from real video sequences showed that the proposed method performs stable feature tracking for long frame sequences.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.19-28
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• 2015

In this paper, we proposed an algorithm for the identification of relieving or worsening current traffic congestion using historic traffic congestion patterns. Historical congestion patterns were placed in an adjacency list. The patterns were constructed to represent spatial and temporal length for status of a congested road. Then, we found information about historical traffic congestions that were similar to today's traffic congestion and will use that information to show how to change traffic congestion in the future. The most similar pattern to current traffic status among the historical patterns corresponded to starting section of current traffic congestion. One of our experiment results had average error when we compared identified changes of the congestion for one of the sections in the congestion road by using our proposal and real traffic status. The average error was 15 minutes. Another result was for the long congestion road consisting of several sections. The average error for this result was within 10 minutes.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.4
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• pp.575-582
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• 2013

This paper proposes a map building using the ICP algorithm based robot localization prediction. Proposed method predicts a robot location to dead reckoning, makes a map in the ICP algorithm. Existing method makes a map building and robot position using a sensor value of reference data and current data. In this case, a large interval of the difference of the reference data and the current data is difficult to compensate. The proposed method can map correction through practical experiments.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.215-216
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• 2008

In this paper, we describe a UHF-band CMOS fractional-N frequency synthesizer using a ring - type VCO. It has been designed using $0.18{\m}m$ CMOS technology. First, The newly designed charge-pump circuit includes an OTA for matching between the upper current and the lower current In addition, a ring - type VCO is also used for small chip sire. The simulation results show that the designed circuit has a phase noise of -109.53dBc/Hz at 1MHz offset and consumes 19.4mA from a 1.8V supply. The lock time is less than 30usec and the chip size is $0.45mm{\times}0.5mm$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.585-588
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• 2010

The prediction of user location within a building can be applied to many areas like visitor guiding. The existing methods for solving this problem consider limited number of locations a user visited in the past to predict the current location. It cannot model the complex movement patterns, and makes the system inefficient by modeling simple ones too detail. Also it causes prediction errors. In this paper, there is no restriction on the length of past movement patterns to consider for current location prediction. For this purpose, a modified search tree is used. The search tree is constructed to make exact matching as needed for location prediction. The search tree makes the efficient and accurate prediction possible.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.47-54
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• 2003

New efficiency enhancement techniques have been devised and implemented to InGaP/GaAs HBT MMIC power amplifiers for W-CDMA mobile terminals applications. Two different types of bias current control circuits that select the efficient quiescent currents in accordance with the required output power levels are proposed for overall power efficiency improvement. A dual chain power amplifier with single matching network composed of two different parallel-connected power amplifier is also introduced. With these efficiency enhancement techniques, the implemented MMIC power amplifiers presents power added efficiency (PAE) more than 14.8 % and adjacent channel leakage ratio(ACLR) lower than -39 dBc at 20 dBm output power and PAE more than 39.4% and ACLR lower than -33 dBc at 28 dBm output power. The average power usage efficiency of the power amplifier is improved by a factor of more than 1.415 with the bias current control circuits and even up to a factor of 3 with the dual chain power amplifier.

• Journal of Surface Science and Engineering
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• v.47 no.3
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• pp.104-108
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• 2014

To improve emission efficiency of organic light emitting devices (OLEDs), we fabricated the tandem OLED of ITO / 2-TNATA / NPB / SH-1: 3 vol.% BD-2 / Bphen / Liq / Al / $MoO_x$ (X nm) / 2-TNATA / NPB / SH-1: 3 vol.% BD-2 / Bphen / Liq / Al structure. And emission properties of single OLED and tandem OLED with $MoO_x$ thickness as charge generation layer (CGL) were measured. The current emission efficiency and quantum efficiency of tandem OLED with $MoO_x$ of 3 nm thickness were improved compare with single OLED from 7.46 cd/A and 5.39% to 22.57 cd/A and 11.76%, respectively. In case of thicker or thinner than $MoO_x$ of 3~5 nm, the current emission efficiency and quantum efficiency were decreased, because balance of electron and hole in emission layer was not matching. The driving voltage was increased from 8 V of single OLED to 15 V of tandem OLED by thickness increase of OLED. As a result, it was possible to improve the emission efficiency of OLEDs by optimized $MoO_x$ thickness.

• Journal of Electrical Engineering and information Science
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• v.3 no.2
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• pp.202-210
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• 1998

This paper is concerned with an efficient generation of stereoscopic views for complex virtual environments by exploiting frame coherence in visibility. The basic idea is to keep visible polygons throughout the rendering process. P-buffer, a buffer of image size, holds the id of the visible polygon for each pixel. This contrasts to the frame buffer and the Z-buffer which hold the color information and the depth information, respectively. For the generation of a consecutive image, the position and the orientation of the visible polygons in the current view are updated according to the viewer's movements, and re-rendered on the current image under the assumption that, when the viewer moves slightly, the visibility of polygons remains unchanged. In the case of stereoscopic views, it may not introduce much difficulty when we render the right(left) image using visible polygons on the (right) image only, The less difference in two images is, the easier the matching becomes in perceiving depth. Some psychophysical experiments have been conducted to support this claim. The computational complexity for generating a fight(left) image from the previous left(right) image is bounded by the size of image space, and accordingly. It is somewhat independent of the complexity of the 3-D scene.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.1
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• pp.59-69
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• 2002

A semi-analytical model based on exact numerical analysis of the 2DEG channel in pseudo-morphic HEMT (PMHEMT) is presented. The exactness of the model stems from solving both Schrodinger's wave equation and Poisson's equation simultaneously and self-consistently. The analytical modeling of the device terminal characteristics in relation to the charge control model has allowed a best fit with the geometrical and structural parameters of the device. The numerically obtained data for the charge control of the channel are best fitted to analytical expressions which render the problem analytical. The obtained good agreement between experimental and modeled current/voltage characteristics and small signal parameters has confirmed the validity of the model over a wide range of biasing voltages. The model has been used to compare both the performance and characteristics of a PMHEMT with a competetive HEMT. The comparison between the two devices has been made in terms of 2DEG density, transfer characteristics, transconductance, gate capacitance and unity current gain cut-off frequency. The results show that PMHEMT outperforms the conventional HEMT in all considered parameters.

• Advances in Computational Design
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• v.4 no.1
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• pp.43-52
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• 2019

Variation Analysis (VA) is used to simulate final product variation, taking into consideration part manufacturing and assembly variations. In VA, all the manufacturing and assembly processes are defined at the product design stage. Process Capability Data Bases (PCDB) provide information about measured variation from previous products and processes and allow the designer to apply this to the new product. A new challenge to this traditional approach is posed by the Industry 4.0 (I4.0) revolution, where Smart Manufacturing (SM) is applied. The manufacturing intelligence and adaptability characteristics of SM make present PCDBs obsolete. Current tolerance analysis methods, which are made for discrete assembly products, are also challenged. This paper discusses the differences expected in future factories relevant to VA, and the approaches required to meet this challenge. Current processes are mapped using I4.0 philosophy and gaps are analysed for potential approaches for tolerance analysis tools. Matching points of simulation capability and I4.0 intents are identified as opportunities. Applying conditional variations, incorporating levels of adjustability, and the un-suitability of present Monte Carlo simulation due to changed mass production characteristics, are considered as major challenges. Opportunities including predicting residual stresses in the final product and linking them to product deterioration, calculating non-dimensional performances and extending simulations for process manufactured products, such as drugs, food products etc. are additional winning aspects for next generation VA tools.