• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.41-48
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• 2001

The exact general bit error rate (TIER) expression of M-ary square quadrature amplitude modulation (QAM) for arbitrary M has not been derived so far. In this paper, a generalized closed-form expression for the BER performance of M-ary square QAM with Gray code bit mapping is derived and analyzed in the presence of additive white Gaussian noise (AWGN) channel. The derivation is based on the consistency of the format in signal constellation o[ Gray coding and it has been derived from the results for M-16, 64, and 256.

• Journal of Korea Spatial Information System Society
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• v.4 no.1 s.7
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• pp.5-14
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• 2002

The generalization of geospatial data is an important way in deriving a new database from an original one. The generalization of a geospatial object changes not only its geometric and aspatial attributes but also results in propagation to other objects along their relationship. We call it generalization propagation of geospatial databases. Without proper handling of the propagation, it brings about an inconsistent database or loss of semantics. Nevertheless, previous studies in the generalization have focused on the derivation of an object by isolating it from others. And they have proposed a set of generalization operators, which were intended to change the geometric and aspatial attributes of an object. In this paper we extend the definition of generalization operators to cover the propagation from an object to others. In order to capture the propagation, we discover a set of rules or constraints that must be taken into account during generalization procedure. Each generalization operator with constraints is expressed in relational algebra and it can be converted to SQL statements with ease. A prototype system was developed to verify the correctness of extended operators.

• Journal of Korea Multimedia Society
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• v.17 no.3
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• pp.294-299
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• 2014

In this paper, we propose a novel algorithm to improve the performance of a voice activity detection(VAD) which is based on the generalized normal-Laplace(GNL) distribution. In our algorithm, the probability density function(PDF) of the noisy speech signal is represented by the GNL distribution and the variance of the speech and noise of GNL distribution are estimated using higher order moments. Experimental results show that the proposed algorithm yields better results compared to the conventional VAD algorithms.

• Journal of the Korean association of regional geographers
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• v.15 no.2
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• pp.307-315
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• 2009

The purpose of map generalization is a method of map making to transmit the concise cartographic representation and geographic meaning. New generalization algorithm has been developed to be applied in the digital environments by the development of computer cartography. This study aims to look into possibilities of the multiscale mapping by generalization in application with the coordinate transformation and LoD(level of detail) in the web cartography. A method of the coordinate transformation is to improve a transmission of spatial data. Lod is a method which is making web map with selection spatial data by zoom level of users. Layers for test constructed contour line, stream network, the name of a place, a summit of mountain, and administrative office. The generalization was applied to zoom levels by scale for the linear and polygonal features using XML-Based scalable vector graphics(SVG). Resultantly, storage capacity of data was minimized 41% from 9.76mb to 4.08mb in SVG. Generalization of LoD was applied to map elements by stages of the zoom level. In the first stages of zoom level, the main name of places and administrative office, higher order of stream channels, main summit of mountain was represented, and become increase numbers of map elements in the higher levels. Results of this study can help to improve esthetic map and data minimization in web cartography, and also need to make an efforts to research an algorithm on the map generalization over the web.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.1
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• pp.43-52
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• 1994

This paper outlines a new approach to the line generalization when preparing small scale map on the basis of existing large scale digital map. Line generalizations are conducted based on Douglas algorithm using 1/25,000 scale topographic maps of southeastern JEJU island which produced by National Geographic Institute to analyze the fitness to the original and problems of graphical representation. Compare to the same scale map which was generated by manual method, a verity of small, but sometimes significant errors ＆ modification of topological relationship have been detected. The research gives full details of three algorithms that operationalize the smallest visible object method, together with some empirical results. A comparison of the results produced by the new algorithms with those produced by manual generalization and Douglas method of data reduction is provided. Also this paper presents the preliminary results of an relationships between the size of smallest visual object and requiring data storages for each algorithms.

• Spatial Information Research
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• v.19 no.1
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• pp.73-82
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• 2011

Recently, demand for the use of cadastral map is increasing in both public and private area. To use cadastral map in web or mobile environment, construction of the multi-representation database(MRDB) that is the compressed into multiple scale from the original map data is recommended. In this study, the map generalization methodology for the cadastral map by applying overlay with topographic map and polygon generalization technique is suggested. This process is composed of three steps, re-constructing the network data of topographic map, polygon merging of parcel lines according to network degree, and applying line simplification techniques. Proposed methodologies are applied to the cadastral map in Suwon area. The result map was generalized into 1:5,000, 1:20,000, 1:100,000 scale, and data compression ratio was shown in 15% 8% 1% level respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9C
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• pp.831-839
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• 2006

In this paper, we present an exact and general expression involving two-dimensional Gaussian Q-functions for the bit error rate (BER) of hierarchical MPSK with I/Q phase and amplitude imbalances over an additive white Gaussian noise (AWGN) channel. First we derive a BER expression for the k-th bit of hierarchical 4, 8, 16-PSK signal constellations when Gray code bit mapping is employed. Then, from the derived k-th bit BER expression, we present the exact and general average BER expression for hierarchical MPSK with I/Q phase and amplitude imbalances. This result can readily be applied to numerical evaluation for various cases of practical interest in an I/Q unbalanced hierarchical MPSK system, because the one- and two-dimensional Gaussian Q-functions can be easily and directly computed usinB commonly available mathematical software tools.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.647-649
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• 2000

개념-논리 스키나 설계의 목적은 개념 스키마를 사용 가능한 데이터의 구조화와 제약사항 모델화를 위한 기능들을 가능한 후 효과적으로 표현하는 것이다. 스키마 변환은 이러한 표현을 구현 언어나 데이터베이스와는 독립적인 차원에서 고려할 수 있도록 해준다. 개념-논리 스키마로의 변환에 프리미티브 변환을 적용함으로써 얻을 수 있는 이점은 개념 스키마에 나타난 정보를 손실 없이 구현 모델에 반영할 수 있게 한다는 것이다. 본 논문에서는 다단계 보안 응용을 위한 일반화 계층구조의 스키마 변환에서 발생할 수 있는 프리미티브 변환을 논의한다. 이러한 변환은 다단계 보안 응용의 개념 논리와 설계 단계에 대한 질적 향상을 기할 수 있는 기본적인 도구의 토대가 될 수 있으며 또한 이를 적용함으로써 설계 과정을 변환의 작은 단위로 생각할 수 있게 해 줌으로서 설계 과정을 단순화할 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.63-66
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• 2022

본 논문에서는 분자의 특성을 정확하게 예측하기 위해 효과적인 사전학습(pretraining) 전략과 트랜스포머(Transformer) 모델을 활용한 방법을 제시한다. 딥러닝을 활용한 분자의 성능을 예측하는 연구는 그동안 레이블이 부족한 분자데이터의 특성에 의해 학습 때 사용된 데이터이외의 분자데이터에 대해 일반화 능력이 떨어지는 어려움을 겪었다. 이 논문에서 제시한 모델은 사전학습(pretraining)을 수행할 때 자기지도학습(self-supervised training)을 사용하여 부족한 레이블에 의한 문제점을 피할 수 있다. 대규모 분자 데이터셋으로부터 학습된 이 모델은 4가지 다운스트림 데이터셋에 대해 모두 우수한 성능을 보여주어 일반화 성능이 뛰어나며 효과적인 분자표현을 얻을 수 있음을 보인다.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.117-120
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• 1995

분수차 퓨리에(Fouier) 변환은 퓨리에 면환을 일반화시킨 것으로, 위치와 공간주파수의 복합적인 표현을 주나, 한 개의 렌즈를 광학적 구현이 역시 가능하다. 광신호처리에서 많이 사용되는 정합 필터를 구성하는 퓨리에 면환을 각각 분수차로 일반화시킴으로서, 위치 필터와 공간주파수 필터의 특성이 복합된 새로운 필터를 구성할 수 있게 된다. 이 필터 구조는 신경회로망의 학습으로 대치된다. 최대경사법과 오차역전파(error back-propagation)에 기초한 학습 법칙이 유도되고, 컴퓨터 시뮬레이션 결과가 제시된다.