• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.2
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• pp.204-208
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• 2018

In this paper, we proposed and evaluated the time series deep learning prediction model for learning fluctuation pattern of stock price. Recurrent neural networks, which can store previous information in the hidden layer, are suitable for the stock price prediction model, which is time series data. In order to maintain the long - term dependency by solving the gradient vanish problem in the recurrent neural network, we use LSTM with small memory inside the recurrent neural network. Furthermore, we proposed the stock price prediction model using bidirectional LSTM recurrent neural network in which the hidden layer is added in the reverse direction of the data flow for solving the limitation of the tendency of learning only based on the immediately preceding pattern of the recurrent neural network. In this experiment, we used the Tensorflow to learn the proposed stock price prediction model with stock price and trading volume input. In order to evaluate the performance of the stock price prediction, the mean square root error between the real stock price and the predicted stock price was obtained. As a result, the stock price prediction model using bidirectional LSTM recurrent neural network has improved prediction accuracy compared with unidirectional LSTM recurrent neural network.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.2
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• pp.77-83
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• 2002

본 연구에서는 가솔린 시계열 예측전문가들이 수요를 예측하고, 더 나아가 직감적으로 행하고 있는 보정과정을 자동화하기 위해 신경망을 사용한다. 가솔린 수요 예측분야에서 보정을 위해 사용되는 전형적인 판단요소는 정부 에너지 절약 정책, 에너지 산업의 파업, 공휴일 등이 있다. 주요 추세가 순환신경망에 의해 예측되고 이들 판단요소의 효과가 다층신경망에 의해 탐지되어 보정된다. 가솔린 수요에 대한 실험결과는 보정과정을 갖는 예측구조가 하나의 신경망을 사용하는 예측구조 보다 더 나은 예측력을 보였다. 그리고 본 연구에서 제시한 접근방법이 순환신경망이나 ARIMA 모델을 사용하는 것보다 더 나은 결과를 가졌다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.8
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• pp.1759-1766
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• 2010

The performance of noise attenuation of the adaptive active noise control algorithm is improved using the recurrent neural network. The FXLMS that has been frequently used in the active noise control is simple and has low computational load, but this method is weak to nonlinearity of the main or secondary path since it is based on the FIR linear filter method. In this paper, the recurrent neural network filter has been developed and applied to improvement of the active noise attenuation by simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.6
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• pp.759-767
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• 2020

This paper proposes a new Recurrent neural network (RNN) based spectrum sensing technique for cognitive radio communications. The proposed technique determines the existence of primary user's signal without any prior information of the primary users. The method performs high-speed sampling by considering the whole sensing bandwidth and then converts the signal into frequency spectrum via fast Fourier transform (FFT). This spectrum signal is cut in sensing channel bandwidth and entered into the RNN to determine the channel vacancy. The performance of the proposed technique is verified through computer simulations. According to the results, the proposed one is superior to more than 2 [dB] than the existing threshold-based technique and has similar performance to that of the existing Convolutional neural network (CNN) based method. In addition, experiments are carried out in indoor environments and the results show that the proposed technique performs more than 4 [dB] better than both the conventional threshold-based and the CNN based methods.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.8
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• pp.307-324
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• 2018

Recently, recurrent neural networks have been attracting attention in solving prediction problem of sequential data through structure considering time dependency. However, as the time step of sequential data increases, the problem of the gradient vanishing is occurred. Long short-term memory models have been proposed to solve this problem, but there is a limit to storing a lot of data and preserving it for a long time. Therefore, research on memory-augmented neural network (MANN), which is a learning model using recurrent neural networks and memory elements, has been actively conducted. In this paper, we describe the structure and characteristics of MANN models that emerged as a hot topic in deep learning field and present the latest techniques and future research that utilize MANN.

• KIISE Transactions on Computing Practices
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• v.23 no.5
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• pp.322-327
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• 2017

The classification problem in the field of Natural Language Processing has been studied for a long time. Continuing forward with our previous research, which classifies large-scale text using Convolutional Neural Networks (CNN), we implemented Recurrent Neural Networks (RNN), Long-Short Term Memory (LSTM) and Gated Recurrent Units (GRU). The experiment's result revealed that the performance of classification algorithms was Multinomial Naïve Bayesian Classifier < Support Vector Machine (SVM) < LSTM < CNN < GRU, in order. The result can be interpreted as follows: First, the result of CNN was better than LSTM. Therefore, the text classification problem might be related more to feature extraction problem than to natural language understanding problems. Second, judging from the results the GRU showed better performance in feature extraction than LSTM. Finally, the result that the GRU was better than CNN implies that text classification algorithms should consider feature extraction and sequential information. We presented the results of fine-tuning in deep neural networks to provide some intuition regard natural language processing to future researchers.

• KIISE Transactions on Computing Practices
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• v.23 no.7
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• pp.440-445
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• 2017

Due to the advance of e-commerce systems, the number of people using online shopping and products has significantly increased. Therefore, the need for an accurate recommendation system is becoming increasingly more important. Recurrent neural network is a deep-learning algorithm that utilizes sequential information in training. In this paper, an evaluation is performed on the application of recurrent neural networks to recommendation systems. We evaluated three recurrent algorithms (RNN, LSTM and GRU) and three optimal algorithms(Adagrad, RMSProp and Adam) which are commonly used. In the experiments, we used the TensorFlow open source library produced by Google and e-commerce session data from RecSys Challenge 2015. The results using the optimal hyperparameters found in this study are compared with those of RecSys Challenge 2015 participants.

• Annual Conference on Human and Language Technology
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• 2017.10a
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• pp.47-50
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• 2017

문서 요약은 입력 문서가 가진 주제를 유지하면서 크기가 축약된 새로운 문서를 생성하는 것이다. 문서 요약의 방법론은 크게 추출 요약과 추상 요약으로 구분된다. 추출 요약의 경우 결과가 문서 전체를 충분히 대표하지 못하거나 문장들 간의 호응이 떨어지는 문제점이 있다. 최근에는 순환 신경망 구조의 모델을 이용한 추상 요약이 활발히 연구되고 있으나, 이러한 방법은 입력이 길어지는 경우 정보가 누락된다는 문제점을 가지고 있다. 본 논문에서는 이러한 단점들을 해소하기 위해 추출 요약으로 입력 문서의 중요한 일부 문장들을 선별하고 이를 추상 요약의 입력으로 사용했을 때의 성능 변화를 관찰한다. 추출 요약을 통해 원문 대비 30%까지 문서를 요약한 후 요약을 생성했을 때, ROUGE-1 0.2802, ROUGE-2 0.1294, ROUGE-L 0.3254의 성능을 보였다.

• 한국어정보학회:학술대회논문집
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• 2016.10a
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• pp.321-323
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• 2016

최근 연구에서 기계학습 중 지도학습 방법으로 개체명 인식을 하고 있다. 그러나 지도 학습 방법은 데이터를 만드는 비용과 시간이 많이 필요로 한다. 본 연구에서는 주석 된 말뭉치를 사용하여 지도 학습 방법을 사용 한다. 의생명 개체명 인식은 Protein, RNA, DNA, Cell type, Cell line 등을 포함한 텍스트 처리에 중요한 기초 작업입니다. 그리고 의생명 지식 검색에서 가장 기본과 핵심 작업 중 하나이다. 본 연구에서는 순환형 신경망과 워드 임베딩을 자질로 사용한 조건적 임의 필드에 대한 성능을 비교한다. 조건적 임의 필드에 N_Gram만을 자질로 사용한 것을 기준점으로 설정 하였고, 기준점의 결과는 70.09% F1 Score이다. RNN의 jordan type은 60.75% F1 Score, elman type은 58.80% F1 Score의 성능을 보여준다. 조건적 임의 필드에 CCA, GLOVE, WORD2VEC을 사용 한 결과는 각각 72.73% F1 Score, 72.74% F1 Score, 72.82% F1 Score의 성능을 얻을 수 있다.

• 한국어정보학회:학술대회논문집
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• 2017.10a
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• pp.47-50
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• 2017

문서 요약은 입력 문서가 가진 주제를 유지하면서 크기가 축약된 새로운 문서를 생성하는 것이다. 문서 요약의 방법론은 크게 추출 요약과 추상 요약으로 구분된다. 추출 요약의 경우 결과가 문서 전체를 충분히 대표하지 못하거나 문장들 간의 호응이 떨어지는 문제점이 있다. 최근에는 순환 신경망 구조의 모델을 이용한 추상 요약이 활발히 연구되고 있으나, 이러한 방법은 입력이 길어지는 경우 정보가 누락된다는 문제점을 가지고 있다. 본 논문에서는 이러한 단점들을 해소하기 위해 추출 요약으로 입력 문서의 중요한 일부 문장들을 선별하고 이를 추상 요약의 입력으로 사용했을 때의 성능 변화를 관찰한다. 추출 요약을 통해 원문 대비 30%까지 문서를 요약한 후 요약을 생성했을 때, ROUGE-1 0.2802, ROUGE-2 0.1294, ROUGE-L 0.3254의 성능을 보였다.