• Journal of KIISE:Software and Applications
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• v.30 no.9
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• pp.867-875
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• 2003

This paper concerns continuous density HMM topology optimization. There have been several researches for HMM topology optimization. BIC (Bayesian Information Criterion) is one of the well known optimization criteria, which assumes statistically well behaved homogeneous model parameters. HMMs, however, are composed of several different kind of parameters to accommodate complex topology, thus BIC's assumption does not hold true for HMMs. Even though BIC reduced the total number of parameters of HMMs, it could not improve the recognition rates. In this paper, we proposed two new model selection criteria, HBIC (HMM-oriented BIC) and BIC_Anti. The former is proposed to improve BIC by estimating model priors separately. The latter is to combine BIC and anti-likelihood to accelerate discrimination power of HMMs. We performed some comparative research on couple of model selection criteria for online handwriting data recognition. We got better recognition results with fewer number of parameters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.6
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• pp.628-636
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• 2014

This paper describes the design and analysis of five-element planar array antenna of an anti-jamming satellite navigation system. We propose a design of multi-layer patch antenna for Global Positioning System(GPS) $L_1/L_2$ dual bands. The proposed antenna has two ports feeding network with a hybrid chip coupler for a broad bandwidth with Right-Handed Circular Polarization(RHCP). The measurement results show the bore-sight gains of 1.10 dBic($L_1$) and 0.37 dBic($L_2$) for the center element. The bore-sight gains of an edge element are 0.99 dBic($L_1$) and -0.57 dBic($L_2$). At a fixed elevation angle of $30^{\circ}$, antennas show average gains of -2.08 dBic ($L_1$) and -5.33 dBic($L_2$) for the center element, and average gains of -0.40 dBic($L_1$) and -2.09 dBic($L_2$) for the edge elements. The results demonstrate that the proposed array antenna is suitable for anti-jamming applications.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.83-88
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• 2017

In this paper, we propose a three-element CRPA array with improved low-elevation gain. The proposed antenna consists of a feed patch and a radiating patch, and the feed patch is connected by a coaxial cable. The radiating patch is electromagnetically coupled to the feed patch, which allows to improve the low-elevation gain of the antenna. To demonstrate the suitability of the proposed antenna, the antenna characteristics are measured in a full anechoic chamber. The resulting bore-sight gain is 2.8 dBic with an axial ratio of 2.7 dB, and the average gain at the low-elevation direction of $75^{\circ}$ is -1.4 dBic. The results verify that the proposed antenna is suitable for CRPA arrays with anti-jamming capability.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.571-573
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• 2002

음성인식과 온라인 필기인식에서 우수한 성능을 보이는 은닉 마르코프(HMM)의 HMM의 구조는 휴리스틱 한 방법에 의해 결정되는 것이 일반적이기 때문에 최적의 모델을 선택하는데 어려움이 있다. 이에 본 논문에서는 HMM의 구조를 체계적인 방법으로 정함과 동시에 변별력의 단점을 개선 할 수 있는 방법으로 Anti-likelihood를 이용한 모델간의 변별력을 살펴보고 최적의 모델 선택 기준인 BIC와의 결합하여, 체계적이고 효율적인 최적 모델 선택이 가능한 방법론에 대해 연구하고 필기데이터에 대해 검증한 결과, 기존의 방법보다 파라미터의 수는 감소되고 인식률이 향상됨을 알 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.853-855
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• 2005

은닉 마르코프(HMM)의 HMM의 구조 최적을 위한 모델 선택 방법에 많은 방법들이 연구되어지고 있다. HMM의 구조를 어떻게 최적으로 정해야 하는 가에 대해 HMM의 구조를 체계적인 방법으로 정함과 동시에 변별력의 단점을 개선 할 수 있는 방법으로 Anti-likelihood(ALC1)를 제안하였고 이를 모델 선택 기준인 BIC와의 결합(ALC2)하여 필기 데이터에 대해 실험한 결과 기존의 방법보다 파라미터의 수는 감소되고 인식률이 향상됨을 알 수 있었다. 이를 Discrete HMM에도 적용하여 제안된 ALC2가 HMM 구조를 최적화하는 모델 선택 기준임을 Continuous-Density HMM과 비교하여 실험 검증 한다.