여드름의 원인 및 관리실태 분석

박시연,이종헌 대한구강악안면병리학회 2020 대한구강악안면병리학회지 Vol.44 No.1

The need for skin health care is newly recognized in accordance with the importance and needs of skin care due to harmonious interpersonal relation. In this study, collected 202 questionnaire sheets in Seoul were analyzed by SPSS 18.0 program through data coding and data cleaning, and frequency analysis for general characteristics was done. Heredity, environmental factors and management condition of acne, and the differences according to general characteristics were analyzed by Crosstabs. Mainly, women used skin care shop and their age groups were varied from twenties to fifties. Recognition of skin trouble were compound(42.1%), and significant statistical difference(p<.05), while oily or compound to man and compound or acne skin to woman were observed. First occurrence of acne was generally middle school(33.7%). Facial acne progress areas was cheek(36.1%), forehead(30.7%), chin(28.2%) and neck(5.0%) in descending order, and present state of acne was in progress(60.9%). Etiologic factors were stress(39.1%), pre and post-menstruation(22.8%), environment(20.8%), heredity(17.3%). There was significant statistical difference between gender(p<.01). Treatment places were at dermatologist(45.0%) and special skin care shop(27.2%). The most reliable place for treatment was special skin care shop(44.6%) and dermatologist(42.6%). It suggested that in acne of skin trouble, age groups of customers could be varied among male and female and in order to meet such requirements of customers, high quality service ought to be provided so that acne care could satisfy customers with the differentiated and careful service.

항균, 항진균 및 항바이러스 액티브 패키징의 최근 연구 동향

박시연,지하니,최지은,임슬기,장윤지 한국포장학회 2023 한국포장학회지 Vol.29 No.1

Since the COVID-19 crisis, the use of disposable packaging materials and delivery services, which raise environmental and social issues with waste disposal, has significantly increased. Antimicrobial active packaging has emerged as a viable solution for extending the shelf-life of foods by minimizing microbial growth and decomposition. In this review article, we provide a comprehensive overview of current research trends in antimicrobial active film and coating published over the last five years. First, we introduced various polymer materials such as film and coating that are used in active packaging. Next, various types of antimicrobial (antibacterial, antifungal, and antiviral) packaging including essential oil, extracts, biological material, metal, and nanoparticles were introduced and their activities and mechanisms were discussed. Finally, the current challenges and prospects were discussed. Overall, this review provides insights into the recent advancements in antimicrobial active packaging research and highlights the potential of the technology to enhance food safety and quality.

Comparison of time and cost between conventional surgical planning and virtual surgical planning in orthognathic surgery in Korea

박시연,황대석,송재민,김욱규 대한악안면성형재건외과학회 2021 Maxillofacial Plastic Reconstructive Surgery Vol.43 No.-

BackgroundThe purpose of this study was to measure the time of the conventional surgical planning (CSP) and virtual surgical planning (VSP) in orthognathic surgery and to compare them in terms of cost. Material and methodThis is a retrospective study of the patients who underwent orthognathic surgery at the OOOOO University Dental Hospital from December 2017 to August 2018. All the patients were analyzed through both CSP and VSP, and all the surgical stents were fabricated through manual and 3-dimensional (3D) printing. The predictor variables were the planning method (CSP vs. VSP) and the surgery type (group I: Le Fort I osteotomy+bilateral sagittal split osteotomy [LFI+BSSO] or group II: only bilateral sagittal split osteotomy [BSSO]), and the outcomes were the time and cost. The results were analyzed using paired t test. ResultsThirty patients (12 females, 18 males) met the inclusion criteria, and 17 patients were excluded from the study due to missing or incomplete data. There were 20 group I patients (LFI+BSSO regardless of genioplasty) and 10 group II patients (BSSO regardless of genioplasty). The average time of CSP for group I was 385±7.8 min, and that for group II was 195±8.33 min. The time reduction rate of VSP compared with CSP was 62.8% in group I and 41.5% in group II. On the other hand, there was no statistically significant cost reduction. ConclusionsThe time investment in VSP in this study was significantly smaller than that in CSP, and the difference was greater in group I than in group II.

와인색 반영구 문신용 염료가 자기공명영상에 미치는 영향 및 발열 감소 방안

박시연,박영우,강경민,이수빈,변재후,허영철 대한자기공명기술학회 2023 대한자기공명기술학회 학술대회 Vol.2023 No.05

법인세율 인하에 따른 배당기업의 주주가치 상승효과 분석

박시연,최문섭,최정화 한국세무학회 2013 세무학 연구 Vol.30 No.1

법인세율의 변동은 기업 활동에 영향을 미쳐 미래 수익과 재무 건전성에 경제․통계적으로 유의미한 영향을 줄 수 있다. 이에 본 연구는 2008년과 2009년에 걸쳐 실시된 국내 법인세율 인하에 따른 한국거래소 유가증권시장 상장 배당기업의 주주가치 상승효과를 사건연구(event study)를 통해 분석하였다. 사건일은 2008년과 2009년 각각 법인세율 인하 개정안 발표일과 의결일로 지정하였다. 분석 결과 국회에서 법인세율 인하 개정안 발표 시 배당기업의 누적초과수익률(cumulative abnormal return)이 무배당기업의 그것을 상회했으며, 배당기업 중 배당성향이 높은 고배당기업의 누적초과수익률이 저배당기업의 그것 보다 높게 관찰되었다. 또한 다중회귀분석 결과 법인세율 인하 개정안 발표일 전후 5일([-2, +2]) 및 11일([-5, +5])의 사건구간에서 배당성향과 누적비정상수익률 간에 양(+)의 상관관계가 나타났다. 이는 효율적 시장가설에 반하는 이례현상(anomaly)이며, 법인세율 인하가 발표되는 시점에 투자자들이 이를 새롭고 의미 있는 정보로 인지하여 투자 의사결정에 반영했음을 함의한다. 과거 법인세율 인하시 기업의 배당성향 상승을 경험한 투자자들의 행태가 고배당기업과 누적초과수익률 간 유의적인 양(+)의 상관관계에 영향을 주었다는 추론이 가능하다. Corporate tax rate changes are known to wield economically and statistically significant influences on the future revenues and financial conditions of firms through their operation channels. In this regard, we study the shareholder value effects of the Korea Stock Exchange-listed firms due to the 2008 announcement and 2009 enactment of marginal tax rate reduction made by the Government and Assembly of the Republic of Korea. The empirical implications of our event study are as follows: First, the cumulative abnormal return (CAR) of an average dividend-paying company dominates that of a non-dividend cohort. Second, a high-dividend listing, on average, posts a higher CAR than a low-dividend peer. Lastly, controlled for a variety of firm-level factors, the payout ratio positively affects the CAR through 5-day and 11-day event periods around the announcement made in 2008. This is an anomaly that counter-exemplifies the efficient market hypothesis:The traders are deemed to acknowledge a tax rate decrease as new and meaningful information for their amended investment behavior, reminiscent of their past learning experience of a positive correlation between a high-dividend stock and its high announcement return.

와인색 반영구 문신용 염료가 자기공명영상검사에 미치는 영향 및 발열 감소 방안 연구

박시연,허영철,박영우,강경민,이수빈,변재후 대한자기공명기술학회 2023 대한자기공명기술학회지 Vol.33 No.4

본 연구에서는 자기공명영상 검사 시 와인색 반영구 문신용 염료가 신호 강도에 미치는 영향을 분석하고, 전자파흡수에 의한 발열 감소 방안을 연구하고자 하였다. 한천과 와인색 반영구 문신용 염료를 이용하여 염료가 퍼진 형태의 팬텀(패드형 팬텀)과 한곳에 뭉친 형태의 팬텀(주사형 팬텀)을 제작하였다. 두 팬텀은 전신용 자기공명영상장치에서 고속스핀에코(turbo spin echo, TSE)와 경사에코(gradient echo, GRE) 계열의 펄스열을 이용하여 2D와 3D로 검사하였다. 검사 후 영상 분석은 팬텀의 몸체, 염료, 공기 방울, 배경을 대상으로 총 720회의 신호강도를 측정하였다. 전자파흡수에 의한 발열 감소 방안을 확인하기 위해 삽입형 온도계를 팬텀에 삽입 후 검사 전후 팬텀의 온도 변화를 확인하였다. 이때, 대기 온도의 상승 변화를 고려하기 위해 검사 전 대기 온도를 측정하였고, 발열 감소를 위한 방법으로 장치에 내장된 팬, 젖은 거즈, 얼음을 이용하였다. 신호 강도는 2D 영상보다 3D 영상이 좋았고, TSE 계열이 GRE 계열보다 좋았다. 특히 와인색 반영구 문신용 염료가 있는 부위의 신호강도는 공기 때문에 발생한 자화율 인공물보다 신호강도가 낮게 측정되었다. 온도 측정 검사는 패드형 팬텀과 주사형 팬텀 모두 검사에 의한 온도상승 효과가 있었으며 온도의 저감을 위한 방법으로 얼음 패드, 팬, 젖은 거즈 순서였다. 본 연구를 통해 와인색 반영구 문신용 염료는 자기공명영상 검사에서 영상과 환자의 안전에 문제를 일으킬 수 있음을 확인하였고, 발열 감소 방안으로 얼음 패드가 효과적이었다는 것을 확인할 수 있었다. The purpose of this study was to analyze the effect of a wine-colored semi-permanent tattoo dye on signal intensity during magnetic resonance imaging (MRI) and to determine how to reduce heat generation using electromagnetic wave absorption. Agar and a wine-colored semi-permanent tattoo dye were used to create a phantom with spreading dye (pad phantom) and a phantom with clumped dye (injection phantom). Both phantoms were examined in 2D and 3D using turbo spin echo (TSE) and gradient (GRE) pulse sequences in a whole-body magnetic resonance imaging system. Post-test image analysis measured the signal intensity of the phantom's body, dye, air bubbles, and background a total of 720 times. In order to determine how to reduce heat generation by absorbing electromagnetic waves, an thermometer was inserted into the phantom to check the temperature change before and after the test. In this case, the atmospheric temperature was measured before the test to take into account the change in atmospheric temperature, and a fan built into the device, wet gauze and ice were used to reduce heat generation. The signal strength was greater in 3D images than in 2D images and the TSE series was better than the GRE series. Most notably, the signal strength of the wine-colored semi-permanent tattoo dye was found to be lower than the magnetization-sensitive artifacts caused by air. For the temperature measurement test, both the pad-type phantom and the injection-type phantom increased the temperature during the test, and the methods to reduce the temperature were ice pads, fans, and wet gauze. The results confirm that a wine-colored semi-permanent tattoo dye can cause imaging and patient safety issues in magnetic resonance imaging, and that ice pads are an effective way to reduce fever.

필환경 트렌드

박시연,전하민,김동영 한국마케팅연구원 2019 마케팅 Vol.53 No.3

Simulation Study on the Scale Change Test for Autoregressive Models with Heavy-Tailed Innovations

박시연,이상열 한국데이터정보과학회 2006 한국데이터정보과학회지 Vol.17 No.4

This paper considers the testing problem for scale changes in autoregressive processes with heavy-tailed innovations. For a test, we propose the CUSUM test statistic based on the trimmed residuals. We perform a simulation study for the mixture normal and Cauchy innovations.

Modelling Online Word-of-Mouth Effect on Korean Box-Office Sales Based on Kernel Regression Model

박시연,김진교 한국데이터정보과학회 2007 한국데이터정보과학회지 Vol.18 No.4

In this paper, we analyse online word-of-mouth and Korean box-office sales data based on kernel regression method. To do this, we consider the regression model with mixed-data and apply the least square cross-validation method proposed by Li and Racine (2004) to the model. We found the box-office sales can be explained by volume of online word-of-mouth and the characteristics of the movies.

Odontogenic Keratocyst with Calcification in Maxillary Sinus

박시연,김욱규,유미현,정연화,황대석 대한구강악안면병리학회 2019 대한구강악안면병리학회지 Vol.43 No.2

Odontogenic keratocyst (OKC), also known as keratocystic odontogenic tumor (KCOT), is an emerging odontogenic tumor originating from the dental lamina. It is an aggressive lesion with a squamous epithelium and a recurrence rate of 15-35%.1 Radiologically, there is a clear, smooth, or shell-like border showing a unilocular or multifocal, polycystic radiographic picture. Hard tissue formation in OKC is a very rare phenomenon and occurs in the form of dystrophic calcification, cartilaginous tissue or dentinoid.2 In this article, we report the case of OKC with calcification. OKC with radiopaque lesion is very rare, these are considered as dystrophic calcification, dentinoid formation, ossification. The incidence of dystrophic calcification in recurrent OKC is low, so it can be inferred that the recurrence rate of OKC with dystrophic calcification is lower than that of conventional OKC.