• 아태비즈니스연구
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• 제15권1호
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• pp.1-14
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• 2024

Purpose - We investigate whether a potential missing pricing factor plays a significant role in the idiosyncratic volatility puzzle. Design/methodology/approach - We theoretically show how a missing pricing factor can affect the idiosyncratic volatility puzzle, and also show how to get around the problem empirically. We adopt the Fama-French five factor model for the estimation of the idiosyncratic risk and use randomly constructed portfolios as test assets. Findings - We find that a missing factor does not drive the idiosyncratic volatility puzzle. Thus, we conclude that the idiosyncratic volatility does affect the risk premium of its stock. Research implications or Originality - The Fama-French five factor model does a pretty good job in explaining the risk premiums of stocks, and it can be used to reliably estimate idiosyncratic risk of stocks.

• 동의생리병리학회지
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• 제28권4호
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• pp.411-416
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• 2014

Simple formulas (單方) of muscle section in Donguibogam (東醫寶鑑) have long been prescribed for strengthening muscle and/or prevention of age-related muscle loss. However, biological activity and mechanisms by which they influence myoblast differentiation have not been studied. Therefore, in this study, we evaluated the effects of 14 simple formulas on myoblast differentiation in C2C12 myoblast cells under non-cytotoxic ($0.5mg/m{\ell}$) conditions. C2C12 cells were treated with water extracts of simple formulas for 72 h, and RT-PCR was performed to determine the gene expression levels of myogenic regulatory factors (MRFs), including myoD, myogenin, MRF4, myf5, and insulin like growth factor-1 (IGF-1). Treatment with Colocasiae Rhizoma (CR), Pini Semen (PS), and Sesami Semen (SS) resulted in a significant increase in expression of myogenin in C2C12 cells. Treatment with Allii Macrostemi Bulbus (AM), Colocasiae Rhizoma (CR), and Pini Semen (PS) also resulted in increased expression of MRF4 in C2C12 cells. In addition, enhanced expression of IGF-1 was observed in treatment with Eucommiae cortex (EC), Dioscoreae Rhizoma (DR), Colocasiae Rhizoma (CR), Pini Semen (PS), and Sesami Semen (SS) in C2C12 cells. These results indicate that simple formulas of muscle section in Donguibogam could potentially enhance myoblast differentiation at least in part via increasing expression of myogenin, and/or MRF4 and/or IGF-1.

• 한국물환경학회지
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• 제24권6호
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• pp.793-800
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• 2008

Recently domestic drinking water industry has recognized membrane-based technology as a promising alternative for water treatment. To ensure successful application of membrane processes, the integrity of membrane systems should be maintained. According to US EPA guidance, the pressure decay test based on the bubble point theory is recommended to detect any membrane defection of which size is close to the smallest diameter of Cryptosporidium oocysts, $3{\mu}m$. Proper implementation of the pressure decay test is greatly affected by initial test pressure, and the interpretation of the test results is associated with upper control limit. This study is conducted to investigate various factors affecting determination of initial test prtessure and upper control limit, including membrane-based parameters such as pore shape correction factor, surface tension and contact angle, and system-based parameters, such as volumetric concentration factor and total volume of system. In this paper, three different hollow fibers were used to perform the pressure decay test. With identical initial test pressure applied, their pressure decay tendency were different from each other. This finding can be explained by the micro-structure disparity of those membranes which is verified by FESEM images of those membranes. More specifically, FESEM images revealed that three hollow fibers have asymmetry, deep finger, shallow finger pore shape, respectively. In addition, sensitivity analysis was conducted on five parameters mentioned above to elucidate their relation to determination of initial test pressure and upper control limit. In case of initial pressure calculation, the pore shape correction factor has the highest value of sensitivity. For upper control limit determination, system factors have greater impact compared to membrane-based parameters.

• Steel and Composite Structures
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• 제1권1호
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• pp.51-74
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• 2001

A series of tests on concrete-filled SHS (Square Hollow Section) stub columns (twenty), columns (eight) and beam-columns (twenty one) were carried out. The main parameters varied in the tests are (1) Confinement factor (${\xi}$) from 1.08 to 5.64, (2) concrete compression strength from 10.7MPa to 36.6MPa, (3) tube width to thickness ratio from 20.5 to 36.5. (4) load eccentricity (e) from 15 mm to 80 mm and (5) column slenderness (${\lambda}$) from 45 to 75. A mechanics model is developed in this paper for concrete-filled SHS stub columns, columns and beam-columns. A unified theory is described where a confinement factor (${\xi}$) is introduced to describe the composite action between the steel tube and filled concrete. The predicted load versus axial strain relationship is in good agreement with stub column test results. Simplified models are derived for section capacities and modulus in different stages of the composite sections. The predicted beam-column strength is compared with that of 331 beam-column tests with a wide range of parameters. A good agreement is obtained. The predicted load versus midspan deflection relationship for beam-columns is in good agreement with test results. A simplified model is developed for calculating the member capacity of concrete-filled SHS columns. Comparisons are made with predicted columns strengths using the existing codes such as LRFD (AISC 1994), AIJ (1997), and EC4 (1996). Simplified interaction curves are derived for concrete-filled beam-columns.

• 지질공학
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• 제12권4호
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• pp.379-394
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• 2002

이 연구는 서울특별시 지하철 A설계구간에서, 현재 시점의 지하수 수질 및 오염을 파악함으로써, 추후 지하철 공사로 인한 수질 악화 발생시, 이에 과학적으로 대처하기 위해 수행되었다. A설계구간을 따라 총 21개 시추공에서 지하수 시료를 채취.분석하였으며, 그 결과 배경수질은 주로 $Ca-HCO_3$ 유형으로 나타났다. 전체시료 가운데, 국내 먹는물 수질기준을 초과하지 않은 시료는 1개이며, 나머지 20개 시료는 $SO_4$, Cd, Pb, Fe, Mn, Al, F, $NO_3-N$ 등이 먹는 물 수질 기준치를 초과하여 있었다. 오염의 형태는 일부 시료에서 몇몇 화학 원소의 농도가 나머지 시료에서의 농도보다 크게 나타나는 점오염의 형태를 띄었다. 화학분석 자료와 포화지수 분석을 통하여, 지하에 매립된 물질과 지표 퇴적물이 일차적인 오염원임을 추정하였다. 요인분석 결과, 연구지역 내 지하수 시료의 수리화학적 특성의 약 47%가 오염 인자에 의해 영향을 받고 있는 것으로 나타났다.

• 한국의류산업학회지
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• 제17권2호
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• pp.265-277
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• 2015

The aim of this study was to successfully reflect human body changes on the transformation of the virtual body within 3D virtual fitting spaces. For this purpose, existing problems of shape transformation of the virtual body were analyzed and regression equations which provides useful basic data for transformation of the virtual body that can be applied usefully to the 3D virtual fitting system was developed. Necessary data for the analyses were body measurement and 3D scan data of women with average physical form between the ages of 40 through 49. The reason that we used human body changes of the female subjects in their forties was based on the recognition that fundamental female body changes start to occur from age of forty. Body shapes were largely divided into 3 groups according to obesity which was found to be the biggest factor of shape change. Seven factors were extracted based on factor analysis of 47 body measurement categories and regression equations were created to extract specific measurements for each BMI group based on these seven factors. The major contribution of this paper can be summarized as follows. First, the regression equations to extract specific measurements based on the 7 representative variables remediated existing problem of virtual bodies as it increased the number of body shape transformation areas. Second, the regression equations helped to overcome the problem of current failing to reflecting changes in body cross-section shape based on simple girth measurements based on analysis of cross-section distances.

• Journal of Periodontal and Implant Science
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• 제54권2호
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• pp.65-74
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• 2024

Purpose: This longitudinal cohort study aimed to evaluate the relationship between osteonecrosis of the jaw and pulp and periapical disease in patients who were administered bisphosphonates. Methods: Using data from a nationwide cohort, we examined the association among dental caries, pulp and periapical disease, and osteonecrosis of the jaw in women aged >50 years who received bisphosphonates for more than 1 year between 2002 and 2015. Because of ambiguities in the diagnosis of osteonecrosis of the jaw in population-based data, we operationally defined and categorized the condition into established and potential osteonecrosis of the jaw. Results: Pulp and periapical disease significantly increased the development of both established and potential osteonecrosis of the jaw (hazard ratio, 2.21; 95% confidence interval, 1.40-3.48; and hazard ratio, 2.22; 95% confidence interval, 1.65-2.98, respectively). Root canal treatment did not have any influence on the development of osteonecrosis of the jaw. Conclusions: Pulp and periapical disease may be a major risk factor for osteonecrosis of the jaw. The study findings suggest that patients should undergo regular dental examinations to detect pulp and periapical disease before or during the administration of bisphosphonates and that root canal treatment should be considered to decrease the risk of osteonecrosis of the jaw.

• 한국지반신소재학회논문집
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• 제17권1호
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• pp.111-118
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• 2018

단층 등 취약지반 조건에서의 터널굴착 시 터널천단 및 측벽변위의 억제를 목적으로 하는 각부보강공이 일반적으로 적용되고 있으며, 터널 단면증가 변화율에 따른 각부보강공 설치각도 및 길이를 고려한 지보안전성 확인을 위한 주요 인자로서 내공변위 천단침하 각부침하 각부축력 등의 여러 응력변위 특성 변수들이 있다. 이러한 굴착중 안전성확인을 위한 변수들에 대한 검토 결과, 우각부 침하영향성이 단면증가율 보다 더 큰 변위경향을 보이는 가장 중요한 중점관리 지배요소로 분석되었으며, 터널단면 증가 변화율에 대한 각 보강공 길이별 축력의 변화관점에서는 큰 연관성을 보여주지 못하는 터널단면 증가율 대비 작은 증가율을 나타냈다. 또한, 각부 보강공 축력의 발생경향은 터널 단면증가율보다 보강공 마찰지지 개념 메커니즘에 따른 거동 영향성을 보여주는 것으로 분석되었다. 본 연구결과, 일정한 길이의 각부 보강공이 선정될 경우 지반불량 구간에서의 터널 단면이 다소 대단면화하여도 무리하게 각부보강공의 길이를 연장시키지 않는 것이 시공성 및 경제성을 고려한 보다 더 합리적인 방법으로 판단된다.

• Geomechanics and Engineering
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• 제15권5호
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• pp.1039-1046
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• 2018

This paper presents a limit analysis of the series of construction stages of shallow tunneling method by investigating their respective safety factors and failure mechanisms. A case study for one particular cross-section of Beijing Subway Line 7 is undertaken, with a focus on the effects of multiple soil layers and construction sequencing of dual tunnels. Results show that using the step-excavation technique can render a higher safety factor for the excavation of a tunnel compared to the entire cross-section being excavated all at once. The failure mechanisms for each different construction stage are discussed and corresponding key locations are suggested to monitor the safety during tunneling. Simultaneous excavation of dual tunnels in the same cross-section should be expressly avoided considering their potential negative interactions. The normal and shear forces as well as bending moment of the primary lining and locking anchor pipe are found to reach their maximum value at Stage 6, before closure of the primary lining. Designing these struts should consider the effects of different construction stages of shallow tunneling method.

• Advances in pediatric surgery
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• 제10권1호
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• pp.60-62
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• 2004

Leveling colostomy with a frozen-section biopsy in a Hirschsprung's disease is an important factor for a successful procedure. Two neonatal cases of Hirschsprung's disease in the descending colon are reported. In both cases, loop ileostomy was established because of the unavailability of frozen-section biopsy on an emergency basis. At the time of definitive procedure of the first case, transition zone at the splenic flexure was noted and was compatible with the frozen section biopsy. In the second case, an unexpected longer resection at a higher level than transition zone was required because of the poor vascularity after dissection. In conclusion, a leveling colostomy should be selected as a choice in long-segment Hirschsprung's disease. Confirming preservation of the marginal artery of Drummond is particularly important in case of Hirschsprung's disease in the descending colon.