• Communications for Statistical Applications and Methods
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• 제17권3호
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• pp.377-390
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• 2010

In the case of time-series analysis, it is often more convenient to rely on the frequency domain than the time domain. Spectral density is the core of the frequency-domain analysis that describes autocorrelation structures in a time-series process. Possible ways to estimate spectral density are to compute a periodogram or to average the periodogram over some frequencies with (un)equal weights. This can be an attractive tool to measure the similarity between time-series processes. We employ the metrics based on a smoothed periodogram proposed by Park and Kim (2008) for the classification of different classes of time-series processes. We consider several lag windows with unequal weights instead of a modified Daniel's window used in Park and Kim (2008). We evaluate the performance under various simulation scenarios. Simulation results reveal that the metrics used in this study split the time series into the preassigned clusters better than do the raw-periodogram based ones proposed by Caiado et al. 2006. Our metrics are applied to an economic time-series dataset.

• 대한수학회지
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• 제34권4호
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• pp.809-824
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• 1997

With the primitive orders in quaternion algebra, theta series associated with these orders are constructed. Here, we studied the space of modular forms generated by these theta series.

• Korean Journal of Mathematics
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• 제30권1호
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• pp.25-42
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• 2022

In this paper, we derive analogues of a couple of classes of infinite series identities with the confluent hypergeometric functions involving Dirichlet characters.

• 한국임상약학회지
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• 제30권4호
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• pp.226-233
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• 2020

Background: Currently, the over-the-counter (OTC) drug market is flooded with series OTC products. The pharmacist must follow the OTC product's indication, given that the most critical role of a pharmacist is the right selection and recommendation of an OTC drug for a patient's symptoms in a dynamic pharmacy environment. Therefore, pharmacists must know each OTC product information precisely to avoid any ambiguity due to several OTC series brand names. Objective: We evaluated the risk and effectiveness of OTC series medicines. Methods: From December 5 to December 18, 2019, an online survey was conducted among 145 community pharmacists. Results: A total of 51.0% of pharmacists knew the difference between products named in a series and could explain it spontaneously. Only 0.7% of the pharmacists admitted to not knowing the difference between products named in a series. While 42.9% of pharmacists who owned a pharmacy opined that the OTC medicines named in a series have health benefits for patients, 50.0% of employee pharmacists admitted that they were rather confused because there are several OTC series medicines. In contrast, 69.2% of pharmacists who owned pharmacies and 72.2% of employee pharmacists admitted that OTC series drugs with names similar to popular OTC drugs sell better. Conclusion: While pharmacists had different opinions regarding OTC series drugs per employment status, they opined that OTC series are more helpful in pharmacy management than completely new brand names. Further studies in this regard are needed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권6호
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• pp.1530-1544
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• 2023

Data monitoring is an important foundation of modern science. In most cases, the monitoring data is time-series data, which has high application value. The deep learning algorithm has a strong nonlinear fitting capability, which enables the recognition of time series by capturing anomalous information in time series. At present, the research of time series recognition based on deep learning is especially important for data monitoring. Deep learning algorithms require a large amount of data for training. However, abnormal sample is a small sample in time series, which means the number of abnormal time series can seriously affect the accuracy of recognition algorithm because of class imbalance. In order to increase the number of abnormal sample, a data augmentation method called GANBATS (GAN-based Bi-LSTM and Attention for Time Series) is proposed. In GANBATS, Bi-LSTM is introduced to extract the timing features and then transfer features to the generator network of GANBATS.GANBATS also modifies the discriminator network by adding an attention mechanism to achieve global attention for time series. At the end of discriminator, GANBATS is adding averagepooling layer, which merges temporal features to boost the operational efficiency. In this paper, four time series datasets and five data augmentation algorithms are used for comparison experiments. The generated data are measured by PRD(Percent Root Mean Square Difference) and DTW(Dynamic Time Warping). The experimental results show that GANBATS reduces up to 26.22 in PRD metric and 9.45 in DTW metric. In addition, this paper uses different algorithms to reconstruct the datasets and compare them by classification accuracy. The classification accuracy is improved by 6.44%-12.96% on four time series datasets.

• 한국토양비료학회지
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• 제9권4호
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• pp.235-244
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• 1976

1964~1969년간(年間) 농가포장(農家圃場)에서 실시(實施)한 3요소(要素) 및 개량제효과(改良劑效果) 시험중(試驗中)에서 곡간저구릉지(谷間低丘陵地)에 분포(分布)한 식양질(埴壤質)의 논 토양(土壤)인 지산통(芝山統)(배수(排水) 약간 불량(不良))과 용지통(龍池統)(배수(排水) 약간 양호(良好))에 대(對)한 시험결과(試驗結果)를 비교분석(比較分析)하여 다음과 같은 결과(結果)를 얻었다. 1. 평균(平均) 정조수량에서 무비구(無肥區)와 시비구중(施肥區中) 최고(最高) 수량(收量)은 각각(各各) 용지통(龍池統) 319, 507kg/10a이고 지산통(芝山統) 396, 567kg/10a이었다. 두 토양간(土壤間)의 현저한 생산력차이(生産力差異)는 지산통(芝山統)이 개답년대(開畓年大)가 긴 숙답(熟畓)인 반면(反面) 용지통(龍池統)은 반숙답(半熟畓)이라는 점(點)에 연유(然由)된 것이라고 보았다. 2. 표토(表土)의 평균(平均) 화학적(化學的) 성질(性質)에 있어서는 지산통(芝山統)은 CEC 12.8m.e, Exch. Ca 6.5m.e, OM3.9%이고 용지통(龍池統)은 CEC 10.4m.e, Exch. Ca 4.7m.e, OM 3.2% 이었고 유효(有效) $P_2O_5$ 함량(含量)은 전자(前者)가 64, 후자(後者)가 103ppm이었다. 3. 용지통(龍池統) 및 일부(一部) 비옥도(肥沃度)가 낮은 지산통(芝山統)에 속(屬)하는 답토양(畓土壤)들의 지력증진(地力增進)을 위하여 심경(深耕)과 유기물(有機物) 및 석회(石灰)와 고토(苦土) 시용(施用)이 유효(有效)할 것으로 보았다. 4. 질소반응(窒素反應)에서는 일반적(一般的)으로 지산통(芝山統)은 다질소수준(多窒素水準)에서도 수량증감폭(收量增減幅)이 적어서 비교적(比較的) 다비안전성(多肥安全性)인 반면(反面) 용지통(龍池統)은 동질소하(冬窒素下)에서 급격히 수량감소(收量減少)가 크다. 그러나 두 토양(土壤) 공(共)히 유기물함량(有機物含量) 3% 이하(以下)의 토양(土壤)들은 다질소수준(多窒素水準)에서 수량감소(收量減少)가 컸으며 3% 이상(以上)의 토양(土壤)은 다비(多肥)에 안전(安全)한 경향(傾向)을 보였다. 5. 일반품종(一般品種)에 대(對)한 질소적량(窒素適量)은 지산통(芝山統)에서 8~9kg/10a, 용지통(龍池統)에서 10~11kg/10a이었으며 질소(窒素) 1kg의 생산능률(生産能率)은 지산통(芝山統) 12kg 용지통(龍池統) 13㎏정도이었다. 6. 인산효과(燐酸效果)는 질소시비수준(窒素施肥水準)에 따라 다르나 각(各) 토양(土壤)의 질소적량수준선(窒素適量水準線)에서 인산적량(燐酸適量)은 용지통(龍池統) 6kg, 지산통(芝山統) 3kg이었다. 지산통(芝山統)의 유효인산함량(有效燐酸含量)(64ppm)이 낮음에도 불구하고 인산적량(燐酸適量)이 용지통(龍池統)(110ppm) 보다도 낮은 이유(理由)는 재배기간중(栽培期間中) 토양환원(土壤還元)의 발달(發達)이 용지통(龍池統) 보다도 심(甚)하여 토양인산(土壤燐酸)의 유효화율(有效化率)이 크기 때문이라고 생각되었다. 7. 가리비효(加里肥效)도 질소수준(窒素水準)에 따라 차이(差異)가 있었다. 용지통(龍池統)에서는 N 8kg/10a 수준(水準)에서 가리시비량(加里施肥量)들이 증가할수록 현저(顯著)히 감수(減收)되었고 다질소수준(多窒素水準)일수록 가리(加里) 비효(肥效)가 컸으며 지산통(芝山統)에서는 어느 질소수준(窒素水準)에서나 가리비효(加里肥效)가 나타났다. 각(各) 토양(土壤)의 적량(適量) 질소수준(窒素水準)에서 가리적량(加里適量)은 각각(各各) 8kg 정도이었다. 8. 3 요소(要素)의 시비량화율(施肥量比率)은 N:$P_2O_5$:K를 용지통(龍池統)에서는 1(11kg/10a):0.6:0.6, 그리고 지산통(芝山統)에서는 1 (8kg/10a):0.4:1이 좋은 것으로 보았다.

• 한국수학사학회지
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• 제30권4호
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• pp.233-246
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• 2017

$Ces{\grave{a}}ro$ summability is a generalized convergence criterion for infinite series. We have investigated the classical results of summability for Fourier series from 1897 to 1957. In this paper, we are concerned with the summability and summation methods for Fourier Series from 1960 to 2010. Many authors have studied the subject during this period. Especially, G.M. Petersen,$K{\hat{o}}si$ Kanno, S.R. Sinha, Fu Cheng Hsiang, Prem Chandra, G. D. Dikshit, B. E. Rhoades and others had studied neoclassical results on the summability of Fourier series from 1960 to 1989. We investigate the results on the summability for Fourier series from 1990 to 2010 in section 3. In conclusion, we present the research minor lineage on summability for Fourier series from 1960 to 2010. $H{\ddot{u}}seyin$ Bor is the earliest researcher on ${\mid}{\bar{N}},p_n{\mid}_k$-summability. Thus we consider his research results and achievements on ${\mid}{\bar{N}},p_n{\mid}_k$-summability and ${\mid}{\bar{N}},p_n,{\gamma}{\mid}_k$-summability.

• 벤처창업연구
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• 제10권4호
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• pp.39-47
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• 2015

한국이나 미국 모든 지역에서 창업초기 투자가 활성화되고 이에 힘입은 엔젤투자가 급증하면서 엔젤투자의 투자와 전통적 VC 투자의 사이에 간극이 커지며 Series A Crunch 현상이 심화되고 있다. 따라서 엔젤투자의 투자와 전통적 VC 투자 사이에 존재하는 창업초기 투자펀드 캐즘구간(Series A Crunch)을 보완하며 양자 사이의 가교펀드(Bridge Fund) 역할을 하는 펀드에 대한 필요성이 증가하고 있다. 이에 본 연구는 국내외 Series A Crunch 개념과 현상에 대한 초래원인을 분석하고 이를 극복하는 Micro VC펀드의 도입방안에 대한 정책방안을 제시하였다.

• 한국수자원학회논문집
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• 제35권5호
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• pp.631-638
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• 2002

시계열의 예측은 통상 추계학적 모형에 의해 수행하여 왔다. 그러나 본 연구에서는 퍼지 개념을 이용한 퍼지 시계열 모형에 의해 강수량 예측을 수행하였다. 기존에 제안된 퍼지 시계열 모형을 이용하여 예측을 수행하고, 예측 능력을 향상시키기 위하여 퍼지 시계열과 뉴로-퍼지 시스템을 연계한 새로운 방법론을 제안하여 상호 비교ㆍ분석하였다. 이를 위하여 미국 일리노이주의 강수량 시계열 예측에 적용하였으며, 예측 결과, 기존의 모형보다 본 연구에서 제안한 방법론의 결과가 더 정확함을 알 수 있었다.

• 한국수학사학회지
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• 제28권6호
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• pp.321-332
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• 2015

This paper is concerned with the convergence of double trigonometric series and Fourier series. Since the beginning of the 20th century, many authors have studied on those series. Also, Ferenc $M{\acute{o}}ricz$ has studied the convergence of double trigonometric series and double Fourier series so far. We consider $L^p(T^2)$-convergence results focused on the Ferenc $M{\acute{o}}ricz^{\prime}s$ studies from the second half of the 20th century up to now. In section 2, we reintroduce some of Ferenc $M{\acute{o}}ricz^{\prime}s$ remarkable theorems. Also we investigate his several important results. In conclusion, we investigate his research trends and the simple minor genealogy from J. B. Joseph Fourier to Ferenc $M{\acute{o}}ricz$. In addition, we present the research minor lineage of his study on $L^p(T^2)$-convergence.