미용업 종사자의 사고재해 경험 및 사용제품의 안전 인식도에 관한 연구

최서연,허국강,박동현 대한안전경영과학회 2012 대한안전경영과학회지 Vol.14 No.4

한국 및 미국 주식시장과 가상화폐의 동조화

최서연,신정순 한국금융공학회 2018 금융공학연구 Vol.17 No.4

This paper examines the synchronization on the US and Korean stock markets and the cryptocurrency for the period of February 16, 2016∼September 30, 2018. The results of the analysis can be summarized as follows First, there are a positive correlation between the volatility index of the Korean stock market and the bitcoin price change rate, a negative correlation between the volatility index of the US stock market and the bitcoin price change rate. Second, the recent trends between the volatility of the Korean and US stock markets, and the bitcoin price change are contradictory. Third, there is an interaction between the VIX and the bit coin price change. Fourth, the VIX has a granger-causal relationship with the bitcoin price change rate. The implications of this study are as follows. First, the stock market has an impact on bitcoin. Second, even though we can not account for the full synchronization between the US stock market and the bitcoin until now, there is evidence that the synchronization is proceeding. 본 연구는 미국과 한국 주식시장 및 대표적인 가상화폐인 비트코인의 동조화 현상에 대해 살펴보았다. 실증분석을 위한 표본 기간은 2016년 2월 16일∼2018년 9월 30일로 설정하였다. 미국 주식시장의 내재변동성지수(VIX), 한국 주식시장의 내재변동성지수(VKOSPI) 그리고 비트코인 가격변화율(VBTC)의 일별 자료를 사용하였다. 분석 결과는 다음과 같이 요약할 수 있다. 첫째, 한국 주식시장의 내재변동성지수와 가상화폐 시장인 비트코인 가격변화율 사이에 양(+)의 상관관계가 있고, 미국 주식시장의 내재변동성지수와 비트코인 가격변화율 사이에 음(-)의 상관관계가 확인되었다. 둘째, 최근의 한국 및 미국 주식시장의 내재변동성지수와 비트코인 가격변화율 사이의 변화 추이는 상반된 것으로 나타났다. 셋째, 전체 표본 기간을 기준으로 미국 주식시장의 내재변동성지수와 비트코인 가격변화율 사이에는 상호의존관계가 있다. 넷째, 전체 표본 기간을 기준으로 미국 주식시장의 내재변동성지수는 비트코인 가격변화율과 인과관계가 있다. 본 연구의 시사점은 다음과 같다. 첫째, 보다 효율적 시장인 주식시장이 가상화폐에 영향력이 있다. 둘째, 현재까지는 미국 주식시장과 가상화폐 시장 간의 완전한 동조화가 확인되지는 않았으나 동조화를 예상한다.

Signal Amplification in a Microfluidic Paper-based Analytical Device (μ-PAD) by Confinement of the Fluidic Flow

최서연,이정현,곽봉섭,김영우,이준상,최종순,정효일 한국바이오칩학회 2015 BioChip Journal Vol.9 No.2

This is a one-step POC biosensor that guarantees rapid assay times, low-cost analysis, simplehandling, stability, and is easy to mass product. However, it has several drawbacks such as limited samplevolume and relatively low sensitivity. To overcome these disadvantages, we have designed and fabricatedthe μ-PAD to confine fluid flow by creating a hydrophobic channel in the paper to improve the sensitivity. The channel pattern was drawn by a computer-aided design program and directly printed by a commercially available wax printer which generates the hydrophobic channel pattern. While maintaining a constant sample, absorption, and conjugation pad, the width of the detection pad was reduced from 5 mm to 2 mm at intervals of 1 mm. The intensity of bands from the single- and double-orifice patterns increased identically compared with the device with no orifice. The relative intensity of the signal bands increased from 141 to 158. Also, numerical simulation was performed to validate the experimental result by using lattice Boltzmann method. We observed that the sensitivity was enhanced at a specific detection pad width (3 mm). Therefore, our simple structural change of the channel led to improve the colorimetric intensity. Cortisol, which is a known stress biomarker, was used to validation the device, an enhanced signal was obtained indicating that our device can be used for the detection psychological stress in humans.

기업의 기부금 지출수준 및 자발적 공시와 전문투자자의 투자의사결정

최서연,표경민 한국회계정책학회 2015 회계와 정책연구 Vol.20 No.5

To test the relation between corporate social responsibility(CSR) and informed trading patterns, we examine how CSR is associated with the trading patterns of foreign and institutional investors, especially in firms with information asymmetry. Prior literature reports that CSR could be related to firm performance, earnings management, and stock returns. In this paper, we focus on the association between trading patterns of informed traders and CSR. After controlling for firm-specific factors, we find a significant association between CSR and informed trading patterns. The negative relation between informed trading patterns and the level of donation is enhanced even in firms with low information asymmetry. However, the informed trading patterns are positively associated with voluntary disclosure of CSR. We infer that informed traders prefer low-monetary expenditures for voluntary disclosure to high-monetary expenditures for donation. A possible limitation with this study is that the testing periods and some variables for capturing donation activities of each firm may limit generalization of the findings of the study. 최근 기업은 사회적 책임활동에 대한 사회적 요구에 강하게 직면하고 있는 실정이다. 하지만, 기존 연구들은 사회적 책임활동 관련하여 인덱스연구, 기업가치, 또는 미래 이익수준에 미치는 영향을 살펴본 경우가 많아 자본시장 참여자들의 특성에 따른 사회적 책임활동의 영향을 살펴본 연구는 많지 않은 실정이다. 이에 따라, 본 연구는 전문투자자들의 투자의사결정과 기업의 사회적 책임활동과의 관련성이 존재하는 지 살펴보고, 기업의 정보환경에 따른 추가적 영향을 살펴보고자 실시되었다. 분석결과, 사회적 책임활동의 자발적 공시는 전문투자자들의 거래규모를 증가시키지만, 기부금 지출수준이 높을 수록 전문투자자들의 거래규모는 감소하는 것으로 나타났다. 또한, 정보비대칭이 낮은 기업이더라도 기부금 지출수준의 증가는 전문투자자들의 순거래규모를 감소시키는 것으로 나타났다. 이는, 상대적으로 자발적 공시 활동에 대한 전문투자자들의 투자선호가 금전적인 기부금지출보다 높을 수 있음을 보여주는 결과라 할 수 있다. 본 연구는 자본시장 참여자들의 투자의사결정에 참고가 될 만한 실증결과를 제공한다는 점에서 의의가 있으며, 자본시장의 환경변화에 의해 분석대상이 제한되었다는 점에서 연구결과를 일반화하는 데에는 한계가 있을 수 있다.

교권보호를 위한 교사들의 내부개혁 지원방안

최서연 한국교원교육학회 2023 한국교원교육학회 뉴스레터 Vol.108 No.-

가상 화폐의 비선형성에 관한 연구

최서연,신정순,임예진 한국자료분석학회 2018 Journal of the Korean Data Analysis Society Vol.20 No.2

본 연구에서는 블록체인 시스템을 기반으로 하는 가상화폐인 비트코인에 대한 특성을 살펴보았다. 비트코인(bitcoin) 가격 지수(price index)를 비선형 모형인 SETAR(self-exciting threshold autoregressive model) 모형을 사용하여 비트코인 가격의 비선형성과 국면의 특성을 분석하였다. 연구 결과, 비트코인 가격 지수는 비선형성을 가지고 있는 것으로 나타났다. 안정기(1기)에 가격 변동시 하락이 지속되었고, 변동기(2기)에서는 가격 상승이 지속된다는 결과가 도출되었다. 즉 비트코인의 가격은 하락기에는 안정적인 반면, 상승기에는 변화가 급격하고 지속된다는 결과를 알 수 있다. 이와 같은 연구결과로 미루어볼 때, 향후 비트코인과 같은 블록체인기술을 활용한 가상화폐시장의 발전을 위해서는 가격 변동성과 비선형성을 고려한 통화제도와 금융제도의 수립이 반드시 선행되어야 한다는 함의를 도출 할 수 있다. This study has studied the asymmetry and nonlinearity of bitcoin price volatility, with the opinion of various experts about whether the bitcoin of virtualization will be a disturbing financial market or a new key currency. This paper shows that bitcoin price index has the asymmetric volatility and nonlinearity. For this purpose, the bitcoin pricing index is tested using the nonlinear model, SETAR (self-exciting threshold autoregressive model). The results show that the bitcoin price index has nonlinearity and the cluster phenomenon appears in the volatility. In the stable period (1), the price fluctuation period continued to decline and the price fluctuation period (2) continued to rise. This means that if the price of the bitcoin begins to fluctuate, this phenomenon will continue for a considerable period of time. This study suggests that monetary policy and monetary system should be preceded by price fluctuation and non-linearity in order to develop the virtual money market using block chain technology such as bit coin.

타워크레인 작업 근로자의 작업환경과 사고 노출 실태에 관한 연구

최서연,조기홍,박동현,최병길 대한안전경영과학회 2015 대한안전경영과학회지 Vol.17 No.3

The study conducted statistical analysis of survey on the 239 workers participating in national Tower Crane installation/dismantlement in order to identify work environment and health hazard exposure of Tower Crane workers. Consequently for work related safety status of Tower Crane workers, the number of installation/dismantlement work was the highest at 15-20 times per month, and safety equipments were not arranged at work and they felt highly anxious when boarding on the Tower Crane. Furthermore, it is found that they feel anxious working in the influence of the weather, noise, vibration, wind, the sun ray, and structure characteristic. They have very low satisfaction in the insecureness of workplace and the work environment, and recognizes that their work affect highly on the health. 81.6% of workers have experienced accident at work, the cause of accidents were mainly due to poor work environment, and the health abnormality they have experienced were mostly fatigue and concentration reduction. For job stress, job demand and conflict in relationship were the highest sections. Total 66.5% of workers complained of musculoskeletal disorder related subjective symptom, and back pain patients were the highest of all groups.

Computational Fluid Dynamics of Intracranial Artery Using 3-Dimensional Angiography: Potentials and Technical Considerations

최서연,박성태,윤경환,고영배,서대철 대한영상의학회 2013 대한영상의학회지 Vol.69 No.1

We report the potentials and limitations of computational fluid dynamics (CFD) analysis of patient-specific intracranial model with modification of proximal and distal length. Flow pattern does not seem to be affected by the length of proximal internal carotid artery. However, most of the flow was directed to the shorter distal part. Our study could serve as a technical reference to validating other tools and CFD results.

CT and MR Imaging Findings of Appendiceal and Hepatic Mucormycosis in a Patient with Acute T-Lymphoblastic Leukemia

최서연,이민희,이혜경,이범하,진수지,박성규,정준철 대한영상의학회 2015 대한영상의학회지 Vol.73 No.5

Fungal infections occur in severely immunocompromised patients having profound and prolonged neutropenia. Here, we report a case of a 41-year-old female who, at the conclusion of induction chemotherapy for acute T-lymphoblastic leukemia, developed angioinvasive mucormycosis involving the appendix and liver, which presented as abdominal pain. This case is the first to provide detailed computed tomography and magnetic resonance imaging findings of angioinvasive appendiceal and hepatic mucormycosis. The implications of these findings as well as the diagnosis and management of mucormycosis, is further discussed.

현장활동 소방공무원의 인간공학적 유해요인 노출이 결근에 미치는 영향

최서연,박동현 대한안전경영과학회 2014 대한안전경영과학회지 Vol.16 No.3

This study tried to identify the effects of ergonomic risk factors for absence from work of fire fighters in Korea. A self-administered questionnaire was prepared for this study. The questionnaire consisted of several parts such as 'general information', 'work-related factors', 'physical & chemical risk factors', 'ergonomic risk factors', and 'absence information'. A total of 7,098 fire fighters participated in this study. The data obtained from the survey was mainly analyzed by logistic regression. A total of 856 out of 7,098 fire fighters experienced absence from work. The risk factors such as gender, age, marital status, education level, total work year, work area. position, job rotation, noise, dust, organic solvent, skin contact with chemical substance, toxic waste, regional vibration, manual material handling, continuous standing posture, awkward working posture were associated with absence from work. Specifically, awkward working posture and manual material handling from ergonomic risk factors were major risk factors for absence from work.