요중 비소농도와 N-acetyl-β-D-glucosaminidase 농도와의 관련성 평가

이용찬,임동혁,엄상용,김용대,김헌 충북대학교 의과대학 충북대학교 의학연구소 2010 忠北醫大學術誌 Vol.20 No.1

Purposes: This study was performed to evaluate the possibility of impairment of renal tubular function by exposure to inorganic arsenic of low concentration. Materials and methods: Study subjects were 867 individuals (365 men and 502 women) who resided around abandoned mine areas in Chungbuk Province, Republic of Korea. Information about the life style, drinking water type, seafood intake, and mine working history was gathered, and urinary arsenic concentration and N-acetyl-β-d-glucosaminidase (NAG) activity were measured. The correlation between arsenic concentration and urinary NAG activity was tested in groups classified according to urinary NAG activity and seafood consumption prior to urine sampling. Results: No statistically significant difference in urinary arsenic concentrations was observed between different gender and age groups. The participants those who ate seafood within three days before the urinary sample showed a higher mean urinary arsenic concentration than those who did not. In a correlation analysis between natural logarithm of urinary arsenic concentrations and that of urinary NAG activities, no statistical significance was found in a total sample as well as within a gender group. In a group with the urinary arsenic concentrations higher than the geometric mean and the urinary NAG activities higher the geometric mean, the correlation coefficient between two variables was 0.182 and significant. (p-value<0.05) Conclusions: It is suggested that renal tubular damage could be induced by non-occupational exposure to low level inorganic arsenic. 연구목적 : 본 연구는 폐금속광산 주변지역 주민들을 대상으로, 저농도 비소노출에 의하여 신세뇨관 기능이상이 유발될 수 있는지를 평가하는 것을 목적으로 시행하였다. 대상 및 방법 : 충청북도에 소재하고 있는 폐금속광산의 주변에 거주하는 주민 867명을 대상으로 직접 면접조사를 실시하였다. 대상자의 소변을 채취하여 요중 비소농도와 요중 N-acetyl-β-D-glucosaminidase (NAG) 활성을 측정하였고, 조사대상자를 역학적 변수에 따라 구분하여 두 변수 사이의 상관관계를 분석하였다. 결과 : 소변시료를 채취하기전 3일 이내에 해산물을 섭취한 사람들의 요중 비소농도는 그 기간동안 해산물을 섭취하지 않은 사람들의 농도에 비하여 유의하게 높았다. 조사 대상자들의 요중 NAG 농도의 평균값은 남녀차이가 없었으나, 65세 미만 대상자와, 표본을 채취하기 전 3일 이내에 해산물을 섭취한 사람들의 요중 NAG 활성도의 평균값은 그렇지 않은 사람들에 비하여 유의하게 낮았다. 요중 비소농도가 기하평균 이상이고, 요중 NAG 활성이 기하평균 이상인 군에서 두 변수의 상관관계가 0.182 로 유의하였다. 결론 : 정상범위의 비소 노출이라도 요중 비소농도가 8.28 μg/g creatinine을 초과하는 경우에는 미세한 신장손상을 유발할 가능성이 있으며, 해산물을 섭취함으로써 체내에 흡수되는 비소는 이러한 신독성이 거의 없다.

주식시장간 수익률 전이

정헌용 남서울대학교 2012 남서울대학교 논문집 Vol.18 No.2

The purpose of this study is to examine the relevence of return among stock markets in countries. We use Granger causality test to examine the revelence existing in 9 Asian countries and U.S.A. before and after 1997 Asian financial crises. As a result, first, in the total period, US stock market return transmitted to Japan, Korea, Hong Kong, and Singapore stock markets. Japan stock market return transmitted to US, Singapore, and Indonesia stock markets. And Korea stock market return transmitted to US, Malaysia, Indonesia, and Thailand stock markets. Second, in the before Asian financial crises period, we do not find the relevence of return among stock markets in countries. Third, in the after Asian financial crises period, US stock market return transmitted to Japan, Korea, Hong Kong, and Singapore stock markets. Japan stock market return transmitted to US, Hong Kong, and Singapore stock markets. And Korea stock market return transmitted to US, Hong Kong, Malaysia, Indonesia, and Thailand stock markets. The results suggest substantial increased Asian stock market comovement. This implies that the benefits of diversification within the 9 Asian stock markets have decreased over the recent years. Key Words : Granger causality, KOSPI, return spillover

이해관계자 이론과 주주 이론 관점에서의 ESG

정헌용 남서울대학교 출판국 2023 남서울대학교 논문집 Vol.29 No.-

This study examines the recent research on the impact of ESG performance on firm value or financial performance from the perspectives of stakeholder theory and shareholder theory, and analyzes which theory is more appropriate for research in this field. In the analysis of studies conducted before 2015, there was a significant proportion of research indicating a positive impact of ESG performance on firm value or financial performance. However, in recent studies conducted after 2015, there has been a significant increase in the proportion of mixed relationships showing positive or negative relationships depending on the cases. This is believed to be due to the increasing understanding and interest of stakeholders as ESG gains traction. Therefore, it is deemed that future research should analyze the impact of ESG performance on firm value or financial performance from a multidimensional perspective rather than a one-sided analysis in order to derive more meaningful results. Therefore, it is anticipated that future research can generate more meaningful results by analyzing the multidimensional impact of ESG performance on firm value or financial performance. Key Words : ESG, Financial Performance, Stakeholder Theory, Shareholder Theory, Sustainability

상해증권거래소의 거래제도와 특성

정헌용 남서울대학교 2011 남서울대학교 논문집 Vol.17 No.2

The Shanghai Stock Exchange(SSE) is the most preeminent stock market in mainland China in terms of listed companies, number of shares of listed, total market value, and securities turnover in value. SSE composite index takes December 19, 1990 as the base day and the total market capitalization of all the listed stocks on the same day as the base period, with a base of 100 points. It was published from July 15, 1991and is the most widely used index in China's securities market. We examine the daily stock returns over the eleven years from January 4, 2000 through December 30, 2010. Because of the test statistics of significant skewness, excess kurtosis, autocorrelations, it is reasonable to empoly GARCH models. We use the univariate GARCH(1,1)-M model developed by Engle et al.(1987).The results of the estimation of the GARCH(1,1)-M model for SSECI daily returns show that the risk premium effect on mean equation is not significant. Using the GARCH(1,1)-M model with exogenous variables, we find significant information spillover effect from KOSPI to SSECI and from SSECI to KOSPI in the mean equation. But we cannot find significant information spillover effect from KOSPI to SSECI and from SSECI to KOSPI in the variance equation. Key Words : SSE, SSECI, KOSPI, GARCH model, spillover effect

시효처리와 마모체가 치과용 콤포짓트 레진의 마모에 주는 영향

김승헌,임범순,문현정,이용근,김철위 大韓齒科器材學會 2001 대한치과재료학회지 Vol.28 No.4

Over the last decade, the use of posterior resin composites has grown considerably. Wear resistance of restorative materials is important for clinical longevity, esthetics, and resistance to dental plaque. The purpose of this study was to evaluate the effect of artificial saliva and 75% ethanol solution on the wear resistance of composite resins by measuring the amounts of wear, and compare the effect of antagonistic materials on the wear resistance of composite resins. Four universal composite resins (Z100, Aelitefil, Spectrum, and Unifill F) and two condensable composite resins (Surefil and Synergy Compact) were measured. Cylinder type specimens were light-cured for 40 sec on the wear surface, and 20 sec on each side surface. The surface for wear testing was polished by 600 grit SiC paper. Three different antagonistic materials (600 grit SiC paper, amalgam, and procelain) were used as an antagonist for 2-body wear test. After speciments were aged in 37℃, artificial saliva and 75% ethanol solution for specific periods (1 day, 1 month and 2 month), 2-body wear testing was performed by the FRP-2000 friction tester with applying 500 g load (80 kPa) to the specimen. The wear test was performed for 10 min and 30㎖ distilled water was used as lubricant. Amount of wear was measured by microscopic measuring device of Micro Hardness Tester in 0.1㎛ scale. There was significant difference in wear resistance of composite resins (p<0.05). Composite resins with filler content below 59 vol.% showed higher wear resistance that composite resins those with filler content above 62 vol.%. In composite resins from 1 day to 1 months (p<0.05). On the contray, the wear amounts of groups which filler fraction were above 62 vol.% did not show any significant differences with increasing aging period (p>0.05). In 1 day aged groups, the wear amounts of the groups aged in 75% ethanol solution were more than those of the groups aged for 1 month (p=0.045) and Spectrum group aged for 2 month (p=0.006). Amounts of wear were significantly decreased with changing antagonist from 600 grit SiC paper to amalgam or porcelain (p<0.05).

고객만족과 기업가치의 관계에 관한 연구

정헌용 남서울대학교 2001 남서울대학교 논문집 Vol.7 No.-

This study examines the links between customer satisfaction and the sales of firms. The NCSI provides yearly and Quarterly indices of overall customer satisfaction for major competitors in a variety of product and service industries. The findings indicate that economic returns from improving customer satisfaction are not immediately realized. Because efforts to increase current customers' satisfaction primarily affect future purchasing behavior, the greater portion of any economic returns from improving customer satisfaction also will be realized in distant periods. In the long run, it is possible that customer satisfaction and sales go together.

수중 가청음에 의한 쏨벵이의 청각능력 : 2. 청각 임계비

이창헌,박용석,문종욱,강창익,김고환,서두옥 제주대학교 해양연구소 1999 해양자원연구소연구보고 Vol.23 No.-

수중 가청음은 어군의 행동 제어와 해양목장화에서 음향 순치에 많이 이용되고 있다. 수중 가청음에 의한 어류반응 해석을 하기 위해서는 물고기의 청각능력을 정확히 파악할 필요가 있으며,오래전부터 여러물고기의 청각능력을 관련된 연구가 수행되었다.

수면확성기의 음향특성에 관한 연구

이창헌,문종욱,박용석,최찬문,서두옥 제주대학교 해양연구소 1998 해양자원연구소연구보고 Vol.22 No.-

To obtain the fundamental data on a surface speaker made to lure fish school by pure sound, three surface speakers were made of moving coil driver units of 75W and 50W respectively. Their frequency characteristic was measured in the range of 200 - 4mHz that could be used in luring fish school. The results of the measurements in air and sea are follows. 1. The input and output wave forms of a surface speaker were similar to each other in measurement frequencies in air. Then sound pressure of a surface speaker made of 75W driver units among them was over 130dB(0dB re 20μ Pa) in the range of 300 - 400Hz maximally. 2. When the surface speaker with 75W driver units emitted the measurement frequencies at sea. Sound pressure classified by the depth of water were over 140dB at 1m and 120dB at 20m(0dB re 1μ Pa) respectively.

시설투자와 기업가치의 관계에 대한 연구

정헌용 남서울대학교 2002 남서울대학교 논문집 Vol.8 No.-

The purpose of this study is to examine the effect the announcement of facility, equipment and R&D investment. Capital investments and R&D(Research and Development) expenditures are very imporent information resource for external investors because firm's investment and R&D activities are highly correlated with their future cash flows. I review how capital investments affect firm value. Investment in research and development and advertising often leads to new and improved products and brand recognition which may benefit the firm for several years. Because of the inadequacies inherent in traditional accounting reports, firms with significant intangible assets often utilize non-accounting information to supplement their accounting disclosure.

백서 두개관세포에서 Ipriflavone이 골조직 개조에 미치는 영향

이용승,김영준,이기헌,황현식 대한치과교정학회 2005 대한치과교정학회지 Vol.35 No.4

본 연구는 ipriflavone (isopropoxyisoflavone)의 투여가 백서 두개관세포의 증식과 골조직 개조에 미치는 영향을 알아보고자 시도되었다. 태령 20-21일째의 백서 두개관세포를 분리 배양한 후, 10^(-9) M부터 10^(-5) M까지 농도의 ipriflavone을 투여하고 1일째와 3일째에 MTT 분석을 시행하여 흡광도를 평가한 결과, 모든 농도에서 백서 두개관세포의 증식을 보이지 않았다. 한편 골조직 개조에 미치는 영향을 알아보기 위하여 14일째에 alizarin red염색을 시행하여, 형성된 석회화 결절 면적을 측정하였을 때, 10^(-8) M, 10^(-7) M, 10^(-6) M 농도를 투여한 경우 석회화 결절 형성이 유의하게 증가하였다. 골아세포의 분화에 미치는 영향을 알아보기 위하여 ipriflavone을 투여하고 7일째와 14일째에 추출한 RNA를 역전사 중합효소 연쇄반응(RT-PCR)을 시켜 bone sialoprotein (BSP), type 1 collagen (COL I), osteocalcin (OCN) 유전자 발현을 관찰한 결과 BSP와 COL I 유전자는 배양 7일째 높은 발현을 보였고, OCN 유전자는 배양 14일째 높은 발현을 보였다. 이상의 연구결과 ipriflavone이 백서 두개관세포에서 석회화를 촉진시키고 골아세포의 분화에 관여하는 BSP, COL I 및 OCN 유전자 발현을 증가시켜 골조직의 개조를 빠르게 할 수 있음을 시사하였다. lpriflavone (isoprofoxyisoflavone), a synthetic derivative from soy isoflavone diazein, has been shown to inhibit bone resorption and perhaps stimulate bone formation. This study was performed to examine the effects of ipriflavone on the proliferation and bone remodeling in rat calvarial cells in vitro. The rat calvarial cells were isolated from fetus aged 20 to 21 days and cultured in BGJb media. The graded concentration of ipriflavone (10^(-9)-10^(-5) M) was administered into cultured cells. When the cell proliferation was estimated through the measurement of MTT assay, there was no increase in cellular proliferation of the rat calvarial cell at any ipriflavone concentration. The cellular activity was evaluated through the formation of mineralized nodules stained by alizarin red. The formation of mineralized nodules significantly increased at concentrations of 10^(-8) M, 10^(-7) M and 10^(-6) M ipriflavone. Reverse transcription-polymerase chain reaction analyses (RT-PCR) were done at 7 and 14 days after culture to detect the expression of Bone Sialoprotein (BSP), Type I collagen (COL I) and Osteocalcin (OCN). As a result, the expressions of BSP and COL I increased of the 7th day of culture and the expression of OCN increased on the 14th day of culture. These results indicate that ipriflavone facilitates the bone remodeling process by promoting rat calvarial cell differentiation and stimulating mineralization through increased expression of extracellular matrix genes, such as BSP, COL I and OCN.