운동에 의한 뇌 활성과 인지기능에 대한 고찰

김경애,정유진,안나리,장혁기 서울여자대학교 자연과학연구소 2013 자연과학연구논문집 Vol.25 No.-

We reviewed literatures on human brain activity on exercise. It was proved that exercise activate brain function through various equipments. Among methods to evaluate brain activation, there are Electroencephalography (EEG), Magnetoencephalography (MEG), transcranial doppler sonography (TCD), Magnetic resonance imaging (MRI), Near Infrared Spectroscopy (NIRS) methods. There were different characteries in each measurement methods to demonstrate exercise effects. NIRS is a spectroscopic method that uses the near infrared region of the electromagnetic spectrum. According to using brain scanning equipments involved NIRS, moderate exercise increased frontal lobe (specially prefrontal cortex) and improves cognitive performance. This review will be discussed about brain activation and cognitive functions.

Corporate Corruption Prediction Evidence From Emerging Markets

Yang Sok Kim,Kyunga Na,Young-Hee Kang 강원대학교 경영경제연구소 2021 Asia-Pacific Journal of Business Vol.12 No.4

Purpose - The purpose of this study is to predict corporate corruption in emerging markets such as Brazil, Russia, India, and China (BRIC) using different machine learning techniques. Since corruption is a significant problem that can affect corporate performance, particularly in emerging markets, it is important to correctly identify whether a company engages in corrupt practices. Design/methodology/approach - In order to address the research question, we employ predictive analytic techniques (machine learning methods). Using the World Bank Enterprise Survey Data, this study evaluates various predictive models generated by seven supervised learning algorithms: k-Nearest Neighbour (k-NN), Naïve Bayes (NB), Decision Tree (DT), Decision Rules (DR), Logistic Regression (LR), Support Vector Machines (SVM), and Artificial Neural Network (ANN). Findings - We find that DT, DR, SVM and ANN create highly accurate models (over 90% of accuracy). Among various factors, firm age is the most significant, while several other determinants such as source of working capital, top manager experience, and the number of permanent full-time employees also contribute to company corruption. Research implications or Originality - This research successfully demonstrates how machine learning can be applied to predict corporate corruption and also identifies the major causes of corporate corruption.

Design, synthesis and characterization of thermoresponsive polypeptide for biological applications

Kyunga Na,Okgene Kim,Jaeyeon Jung,Jonghwan Lee,Jinho Hyun 한국생물공학회 2007 한국생물공학회 학술대회 Vol.2007 No.4

에센셜 오일의 항균성 증진을 위한 셀룰로오스 나노크리스탈 기반의 에멀젼 제조

나경아(Kyunga Na),신성철(Sungchul Shin),신동혁(Donghyeok Shin),곽호정(Hojung Kwak),신종현(Jonghyun Shin),이현지(Hyunji Lee),현진호(Jinho Hyun) 한국펄프·종이공학회 2017 한국펄프·종이공학회 학술발표논문집 Vol.2017 No.10

K-IFRS와 K-GAAP 하에서의 영업이익의 상대적 가치관련성의 차이에 대한 재검토

나경아(Na, Kyunga) 계명대학교 산학연구소 2014 經營經濟 Vol.47 No.2

연구목적 - 본 연구의 목적은 2011년도 초기의 한국채택국제회계기준(이하 K-IFRS)에 의해 공시된 영업이익(발표영업이익)이 과거의 K-GAAP 방식으로 재작성된 영업이익(조정영업이익)과 비교하여 어떤 영업이익의 보고방식이 가치관련성 측면에서 투자자들에게 더 유용한 정보를 제공하는지에 대하여 실증적으로 재검토하는 것이다. 연구방법 - 본 연구에서는 두 회계기준의 따른 영업이익의 가치관련성에 차이가 있는지에 대하여 통계적인 방법인 평행성 검증(parallelism test)을 이용하여 전체 상장기업뿐만 아니라 유가 증권상장과 코스닥상장기업으로 나누어 분석하였다. 주요 결과 - 본 연구는 Ohlson(1995)의 주가수준 모형의 표준화 여부에 따라서 결과에 차이가 있다는 것을 발견하였다. 표준화하지 않은 모형을 사용하여 분석하면 K-IFRS방식의 발표영업 이익이 K-GAAP 방식의 조정영업이익보다 가치관련성이 더 높게 나타나는 경우가 있는 반면, 주가수준 모형을 전기 주가로 표준화하면 모든 결과에서 두 회계기준에 따른 영업이익의 가치관련성은 통계적으로 유의한 차이가 없었다. 시사점 - 본 연구에서 분석한 결과에 의하면 Ohlson(1995)의 모형식을 표준화한 경우 (시장가치 모형이나 주가수준 모형) 전체 상장기업뿐만 아니라 유가증권상장 및 코스닥상장기업 모두 K-IFRS의 발표영업이익과 K-GAAP 방식의 조정영업이익에 대한 주가관련성 측면에서의 차이는 통계적으로 유의하지 않았다. 이러한 결과로 볼 때 관련 선행연구에서 주장하는 것과 달리 과거 규정중심의 K-GAAP 방식에 의해 산출된 영업이익이 원칙중심의 K-IFRS 하에서 보고된 영업이익에 비해 보다 더 유용한 정보를 제공하지는 않으며, 그러한 맥락에서 K-IFRS 하에서 기업들이 기회주의적으로 이익지속성이 낮은 항목 등을 영업이익에 포함시킴으로써 결과적으로 발표영업이익의 미래이익 예측능력이 저하될 것이라는 주장과 결과해석에 대해서는 재해석될 필요가 있다. Purpose - This paper re-examines whether the reported operating income based on the Korean International Financial Reporting Standard (K-IFRS) provides more useful information than the restated operating income based on the previous Korean Generally Accepted Accounting Principle (K-GAAP) in 2011. Design/Methodology - I re-test each model in the previous two studies, as well as two additional models to check the effect of using a deflator. I also use a more direct statistical method, the parallelism test, in order to test the significance of difference between coefficients on operating income based on the K-IFRS and that based on the K-GAAP. Findings - The results based on the original Ohlson’s model show the value relevance of reported operating income based on the K-IFRS is higher than that based on the K-GAAP in the full sample as well as in the KOSDAQ sub-sample. In comparison, the significance in the differences disappears when using the deflated models. Implications - This study shows using un-deflated Ohlson’s model could lead to biased results due to heteroscedasticity and scale effects. Also, from these results, it is unlikely to be warranted that operating income under the rule-based K-GAAP provides more useful information than that under the principle-based K-IFRS.

< 연구논문 > : 상장여부가 재무제표의 비교가능성에 미치는 효과

나경아 ( Kyunga Na ),지승민(교신저자) ( Seungmin Chee ),박종일(공동저자) ( Jong Il Park ) 한국회계학회 2016 회계저널 Vol.25 No.2

연구의 목적은 상장여부에 따라 재무제표의 비교가능성에 어떤 차이가 있는지를 실증적으로 규명하는데 있다. 선행연구들은 상장기업과 비상장기업 간의 재무보고의 질에 차이가 있는지를 보수주의, 이익조정 및 발생액의 질 측면에서 살펴보았다(Ball and Shivakumar 2005; Burgstahler et al. 2006; Hope et al. 2013). 이와 달리, 본 연구는 De Franco et al.(2011)에서 제안된 재무제표의 비교가능성 측면에서 상장기업과 비상장기업 간의 재무보고의 질에 어떤 체계적인 차이가 있는지를 실증적으로 분석하였다. 비상장기업은 상장기업과 달리, 주식이 시장에 공개되지 않아 소유와 경영이 분리되지 않은 경우가 많고, 그로 인해 이해관계자 수가 적어 상장기업과 비교하면 상대적으로 자본시장압력이 낮다. 따라서 자본시장압력이 낮은 비상장기업은 양질의 재무정보를 산출할 유인보다는 조세절감의 유인이 더 강할 수 있어 이러한 특성이 동일산업 내의 기업 간의 재무제표 비교가능성에도 영향을 미칠 수 있다. 반면, 상장기업은 상대적으로 자본시장압력이 높고, 공시량이 많으며, 자본시장에서의 이해관계자가 역시 많기 때문에 재무보고에 대한 규제도 높다. 또한 상장기업은 비상장기업과 비교하여 이해관계자들의 신뢰할만한 재무정보에 대한 수요가 있고, 이에 따른 기업의 양질의 재무정보를 산출한 유인 역시 더 높다. 이러한 상장기업의 특성은 동일산업 내의 기업 간의 재무제표 비교가능성에도 영향을 줄수 있다. 따라서 본 연구는 앞서의 특성에 따라 상장기업의 재무제표 비교가능성이 비상장기업과 비교하여 보다 더 높을 것으로 예상하였다. 이러한 실증적 의문을 살펴보기 위하여 De Franco et al.(2011) 및 Francis et al.(2014)에서 이용된 순이익의 비교가능성과 순이익의 두 가지 구성요소인 영업현금흐름 및 총발생액에 대한 비교가능성을 측정한 후, 분석기간 2008년부터 2014년까지 금융업을 제외한 12월 결산법인 중 상장기업(유가증권상장과 코스닥상장)과 외부감사를 받은 비상장기업 간을 비교분석하였다. 최종표본은 33,543개 기업/연 자료가 분석되었다. 본 연구의 실증결과는 다음과 같다. 첫째, 비교가능성에 영향을 미칠 것으로 예상되는 일정변수를 통제한 후에도 상장기업의 경우 비상장기업보다 순이익, 영업현금흐름 및 총발생액으로 측정된 비교가능성이 유의하게 높은 결과로 나타났다. 이는 비교가능성 측면에서 전반적으로 상장기업이 비상장기업에 비해 자본시장에서 정보이용자들에게 보다 더 유용한 정보를 제공한다는 것을 시사해 준다. 둘째, 표본을 Big 4 감사인여부에 따라, IFRS 의무도입 전후기간에 따라, 감사인 교체여부에 따라, 유가증권상장기업 vs. 비상장기업 간 또는 코스닥상장기업 vs. 비상장기업 간으로 표본을 나누어 분석한 결과 모두 앞서와 일치된 결과가 관찰되었다. 이는 본 연구의 발견, 즉 상장여부 자체가 비교가능성에 미치는 효과는 감사품질, 감사인 교체를 통한 이익조정 유인, IFRS의 의무도입여부 및 시장유형의 영향에 민감하지 않게 강건성이 있음을 나타낸다. 본 연구는 상장여부 자체가 재무제표의 비교가능성에 중요한 결정요인이라는 것을 보여주었다는데 의의가 있다. 또한 이러한 본 연구의 발견은 상장기업과 비상장기업 간의 비교가능성에 어떤 체계적인 차이가 있는지를 보여준 최초의 연구라는 점에서 관련연구(예로, 상장기업과 비상장기업 간의 이익의 질을 비교분석한 연구 및 비교가능성을 분석한 연구)에 추가적인 실증적 증거를 제공해 줄 것으로 예상된다. 아울러, 본 연구는 비교가능성에 대한 정보이용자 측면을 살펴본 대부분의 기존 연구들과는 달리 비교가능성을 자본시장의 특성(capital market characteristics) 측면에서 경영자의 재무보고에 대한 수요 관점에서 논의하고 이와 관련된 실증적 증거를 제공한다는 점에서 학계뿐만 아니라 실무계, 회계기준제정기관 및 감독당국에게도 상장기업과 비상장기업 간에 재무제표의 비교가능성 차이와 관련한 이해에 유익한 시사점을 더불어 제공해 줄 것으로 기대된다. This study examines whether the listing status affects the quality of financial reporting in terms of financial statement comparability. The comparability of financial statements is considered to be a qualitative characteristic which enables accounting information users to compare financial information of a certain firm with that of its peers or with that in the different periods. It may be difficult for accounting information users to make useful decision if they cannot compare numbers in the financial statements of a firm with benchmarks such as those of peer firms or those in the past periods. Although previous studies analyze the difference in quality of financial reporting between listed firms (i.e., public firms) and unlisted firms (i.e., private firms or privately held firms), most of them focus on accounting conservatism, earnings management, or accrual quality (Ball and Shivakumar 2005; Burgstahler et al. 2006; Hope et al. 2013). Also, although there has been a growing body of literature on the accounting comparability, the effect of listing status on the financial statement comparability is still unknown. To fill this gap in the prior accounting literature, we address the question on whether the quality of financial reporting differs between listed firms and unlisted firms from the perspective of accounting comparability, as suggested in De Franco et al. (2011). Unlike listed companies which trade their stocks to the general public, an unlisted firm is held privately by a small number of shareholders without separation of ownership and management. Consequently, unlisted firms have less capital market pressures due to a relatively small number of owners compared to listed firms. The low capital market pressure in turn would give unlisted firms an incentive to avoid corporate tax at the expense of high financial reporting quality, causing a difference in the financial statement comparability between unlisted firms and listed firms. In contrast, the financial reporting of listed firms is more strictly regulated because listed firms are more likely to have greater capital market pressures, greater ownership dispersion and greater number of disclosures. Listed firms also face strong demands from stakeholders such as investors and creditors for reliable financial information, which motivates listed firms to produce higher quality financial information. Based on this discussion, we hypothesize that the financial statements of listed firms are more comparable than those of unlisted firms. To investigate the addressed research question, we first estimate the comparability of net income following De Franco et al. (2011) and Francis et al. (2014). We also consider the comparability of two elements of net income, cash flow from operations and total accruals. We collect the sample from all listed companies in the Korean Stock Exchange (KSE) and Korean Securities Dealers Automated Quotations (KOSDAQ) as well as all unlisted firms audited by an external auditor between 2008 and 2014. The final sample is 33,543 firms-year observations, consisting of non-financial firms with fiscal month of December. The main results are as follows. Firstly, after controlling for factors which are expected to affect the comparability of financial reporting of a firm, accounting comparability of listed firms in terms of net income, cash flow from operations, and total accruals appears to be significantly higher than that of unlisted firms. This result implies listed firms provide more useful accounting information in terms of financial statement comparability than unlisted firms do. Secondly, all results still remain when we partition the sample into two subsamples based on the following dimensions: (1) firms audited by Big 4 auditor vs. those by non-Big 4 auditor, (2) Pre-IFRS adoption period vs. Post-IFRS adoption period, (3) firms with auditor change vs. firms without auditor change, and (4) firms listed on the KSE and unlisted firms vs. firms listed on the KOSDAQ and unlisted firms. Thus, our main findings regarding the effect of listed status on the financial statement comparability are robust to audit quality, IFRS mandatory adoption, auditor change, and stock exchange type of listed firms. To summarize, this study makes several contributions to the current accounting literature. First, we reveal that the listing status is an important factor on the financial statement comparability. This is the first paper to address the difference in the accounting comparability between listed firms and unlisted firms. Second, our findings can provide additional empirical evidence to the related accounting research (for example, accounting literature on the comparison of earnings quality between listed firms and unlisted firms, and/or that on the accounting comparability). Also, this study discusses the financial statement comparability from the perspectives of capital market characteristics, especially capital market demands on the quality of financial reporting, rather than from the perspectives of information users documented in the previous studies. Finally, the empirical evidence of this paper can shed light into the effect of listing status on the comparability of financial statements, which serves as an important empirical evidence to practitioners, business corporations, accounting standard setters, policy makers as well as academia. Also, our study contributes not only to the debate on unlisted versus listed financial statement comparability but also to the broader literature attempting to understand the determinants of financial reporting quality.

무모생쥐 피부에 siRNA 의 이온토포레시스 경피전달

나경아(Kyunga Na),이슬아(Seul A Lee),조선행(Sun hang Cho),신병철(Byung Cheol Shin) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4

SiRNA decomposing mRNA, genetic information delivery material, has been recently used for gene therapy. However siRNA delivery is difficult due to high molecular weight and low cellular uptake. In our study, iontophoresis was demonstrated using siRNA-lipofectamine complex for efficient delivery of siRNA. SiRNA was trandermally delivered by iontophoresis and evaluated the parameters affecting delivery enhancement of siRNA (eq, PH, current density, and drug concentration) using a side-by-side diffusion cell including the hairless mice skin. SiRNA-lipofectamine complex was also trandermally delivered by iontophoresis, and cellular uptake of siRNA and the complex was evaluated in Hera cell. Under iontophoretic delivery the amount of transported siRNA was apporoximately 47 fold higher than that under passive delivery. Flux was proportionaly increased as drug concentration and current density increased. Although the amount of transported the complex was apporoximately 1.36 fold lower than that under siRNA delivery, it enhanced cellular uptake of siRNA. we suggest enhanced method, iontophoresis for transdermal delivery of siRNA.

Comparison of PDX animal model and brain-on-a-chip made from cells derived from glioblastoma patients through NGS analysis

KyungA Kwak,Taeim Kim,Na-Yeon Koh,Yu Mi Lee,A Reum Shin,Myung Ae Bae,ChulHyun Lee,Nakwon Choi,Sang-Hoon Cha,Chi-Hoon Choi 한국실험동물학회 2022 한국실험동물학회 학술발표대회 논문집 Vol.2022 No.1

Status of the SARS-CoV-2 Mutant Virus (Delta, Omicron) outbreak in Chungcheongnamdo, Korea in Early 2022

KyungA Yun,Ji Hee Kim,Na Hee Kwon,Woo-Sik Kim,박귀성 대한미생물학회 2022 Journal of Bacteriology and Virology Vol.52 No.4

As the coronavirus disease 2019 (COVID-19) spread worldwide, variants viruses are constantly emerging. And there has been a growing interest in the study of variant viruses, for the necessity of response to emergence and diffusion of new coronavirus variants. So, we conducted a survey of variant proportions of SARS-CoV-2 on positive samples of confirmed cases by Real-time Polymerase Chain Reaction (Real-time PCR). From December 26, 2021 to April 2, 2022, a total of 819 SARS-CoV-2 variants of concern (VOCs) were identified in COVID-19 positive samples. In the 2nd week of January 2022, detection rate of the Omicron subvariant BA.1 was 58.1%, overtaking Delta variant to become dominant type. However, in the 5th week of March, detection rate of another Omicron subvariant BA.2 was 75.9%, became dominant variant. These results imply that BA.1 was a dominant variant for two months and after that, omicron BA.1 was rapidly replaced by omicron BA.2. This research is valuable because it provided information which is helpful to response diffusion of new variants. Compared to Delta variant, a large number of mutations in the spike gene(S) of Omicron variant were detected. It raises concerns about changes in pathogenicity and transmissibility in new COVID variants. Therefore, we should develop new strategies against emergence and diffusion of SARS-CoV-2 variants throughout monitoring appearance of the new variants, analyzing the characteristics of new things. In this respect, the results of this research are useful because they offered good basic data for appreciating characteristics of new COVID variants by monitoring the emergence of Delta and Omicron variant.

A cell-repellent sulfonated PEG comb-like polymer for highly resolved cell micropatterns

Jung, Jaeyeon,Na, Kyunga,Shin, Byungcheol,Kim, Okgene,Lee, Jonghwan,Yun, Kyusik,Hyun, Jinho Informa UK (TaylorFrancis) 2008 Journal of biomaterials science, Polymer edition Vol.19 No.2

<P>This paper investigates the chemical modification of a cell-repellent poly(ethylene glycol) (PEG)-based polymer to enhance its hydrophilicity with sulfonate groups, and its application in the fabrication of a cell microarray. First, a polymer comprised of a methyl methacrylate (MMA) backbone with PEG side-chains (PMMA-b-PEG) was synthesized from three monomers by radical polymerization and purified. Despite the hydrophilic side-groups in the amphiphilic polymer, the backbone structure's hydrophobicity allows for local adsorption of biomolecules in incubation media with or without serum. To enhance the hydrophilicity of the polymer, we tethered sulfonate groups to the hydroxyl groups on the PEG side chains (PMMA-b-PEG-SO3). The sulfate groups' physical and mechanical movement competitively repels biomolecules approaching the PMMA-b-PEG surface. Polymers modified with sulfonate were characterized by contact angle measurement, FT-IR, NMR, AFM and GPC. PMMA-b-PEG and PMMA-b-PEG-SO3 were successfully micropatterned on polystyrene and glass surfaces, and cell attachment was performed in either serum-free or serum-containing media, resulting in highly resolved cell micropatterns.</P>