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딥 러닝 군집화를 이용한 QPSK 신호 비트 오류율 성능 평가
마효,왕한호 한국정보기술학회 2017 한국정보기술학회논문지 Vol.15 No.12
We apply the clustering-based unsupervised learning (CUL) in deep learning field to QPSK detection. The conventional QPSK detection has been performed by maximum likelihood (ML) based on the reference symbols. On the other hand, if the CUL is used, the detection is performed with only information of the number of clusters. In the CUL, the detection performance is determined by the size of the symbol set, the number of repetitions and the signal-to-noise ratio (SNR). The detection performance is evaluated through the mean square error between the estimated center and reference symbols and bit error rate (BER). We found that the BER is not improved even if the SNR is improved when using arbitrarily selected initial center points. To solve this problem, we propose an initial center-point selection technique suitable for the QPSK detection, and achieve BER performance equal to that of conventional ML detection. 딥 러닝 분야에서 활용되고 있는 군집화에 기반한 자율학습(CUL, Clustering-based Unsupervised Learning) 기법을 QPSK 검파에 적용하였다. 기존 QPSK 검파는 전송 심볼의 참조 성상점을 기준으로 최대공산(ML, Maximum Likelihood)에 의해서 수행되었던 반면, CUL을 사용하면 군집이 네 개라는 정보만으로 검파를 수행하게 된다. CUL에서는 자율학습에 입력으로 제공되는 심볼 집합의 크기와 중심점 결정을 위한 반복 회수 및 신호 대 잡음비가 검파 성능을 결정하며, 검파 성능은 추정된 중심점과 참조 성상점 사이의 평균 자승 오차와 비트 오류율을 통하여 평가하였다. CUL으로 검파할 때, 임의로 선택된 초기 중심점을 사용하는 경우 신호 대 잡음비가 개선되어도 비트 오류율이 개선되지 않는다는 사실을 발견하였다. 이 문제를 해결하기 위하여 QPSK 검파에 적합한 초기 중심점 선택 기법을 제안하였으며, 이를 통하여 딥 러닝 기법을 이용한 검파에서 기존의 ML 검파와 동일한 수준의 비트오류율 성능을 달성하였다.
기업의 사회적 책임이 재무성과에 미치는 영향: 중국기업을 중심으로
마효기,제혜금 한국유통경영학회 2022 유통경영학회지 Vol.25 No.6
Purpose: The purpose of this study was to examine how Impacts of Corporate Social Responsibility on Financial Performance in China. Regression analysis of social responsibility and financial results was carried out. Considering that different industries may have different impacts, the sub-industry analysis was carried out. Research design, data, and methodology: The current research selects three industries including food and beverage, petroleum and chemical, textile, clothing, and fur manufacturing industries among the A-share listed companies in Shanghai and Shenzhen stock exchanges. A total of 580 observed values from 116 enterprises in the five consecutive years 2015-2019 are selected as the research objects to empirically analyze the relationship between corporate social responsibility and corporate performance. Results: The results show that corporate social responsibility will have a positive impact on financial performance. Different industries have different impactson corporate performance for different stakeholders. Implications: It is hoped that enterprises can enhance their awareness of social responsibility and realize that stakeholders are the basis for their survival and development. Actively fulfilling social responsibility can enhance the satisfaction of all stakeholders, gain the trust and support of all parties, improve corporate image, and promote the improvement of financial performance.
이주영,마효일,김영은 대한신경과학회 2021 대한신경과학회지 Vol.39 No.4
Parkinson’s disease is a neurodegenerative disease compromising progressive motor and non-motor features for a long disease course. Although many drugs controlling parkinsonian symptoms were discovered, treatment with disease-modifying or halting effect was not developed to date. The exploration of reliable biomarkers would be helpful for better predicting disease progression and thereby successful development of disease-modifying therapy. In this review, we will review the clinical biomarkers in the prodromal stage and biomarkers using biological tissue in Parkinson’s disease.
뇌졸중 후 발생한 괴잉성욕에 대한 Cimetidine의 치료효과 : 증례보고
유경호,마효일,정승철,이병철 대한치매학회 2002 Dementia and Neurocognitive Disorders Vol.1 No.1
Most studies have agreed that there is a considerable decline in sexual activity following stroke. but the hypersexuality after stroke as a relatively isolated behavioral abnormality has been less frequently reported Hypersexuality has no proven treatment, although reports have described reductions in hypersexual behavior did not response to three medications were not uncommonly observed in clinical practice A 65-year-old right-handed male presented with acute left hemipararesis. His MRI showed a right middle cerebral artery infarct involving the temporal, parietal regions and the basal ganglia. Four weeks after stroke he showed abnormal behavior, such as incessantly holding and hugging the nursing staff without assent, but no increased orality or change in eating habits But several weeks after taking cimetidine. a histamine H₂-receptor antagonist. his sexual behavior showed a marked improvement This case demonstrates that cimetidine as a non-hormonal anti-androgenic effect decreased libido and hypersexual behavior without serious side effects in patients with cognitive decline after stroke Further studies that obviously define the response and long-term side effects of cimetidine are needed to confirm our observations.