• East Asian Economic Review
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• 제20권4호
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• pp.469-491
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• 2016

In this paper, we estimate the exchange rate exposure, indicating the effect of exchange rate movements on firm values, for a sample of 1,400 firms in seven East Asian countries. The exposure estimates based on various exchange rate variables, return horizons and a control variable are compared. A key result from our analysis is that the long term effect of exchange rate movements on firm values is greater than the short term effect. And we find very similar results from using other exchange rate variables such as the U.S. dollar exchange rate, etc. Second, we add exchange rate volatility as a control variable and find that the extent of exposure is not much changed. Third, we examine the changes in exposure to exchange rate volatility with an increase in return horizon. Consequently the ratio of firms with significant exposures increases with the return horizons. Interestingly, the increase of exposure with the return horizons is faster for exposure to volatility than for exposure to exchange rate itself. Taken as a whole, our findings suggest that the socalled "exposure puzzle" may be a matter of the methodology used to measure exposure.

• Journal of Radiation Protection and Research
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• 제31권4호
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• pp.197-201
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• 2006

Daily and seasonal variations of the ambient gamma ray exposure rates were measured by using a pressurized ion chamber from January 2003 to December 2005 in the CheongJu Regional Radiation Monitoring Post and the patterns of the distributions were studied. The annual average of the daily variation of the exposure rate was $\sim0.17{\mu}R/h$. The exposure rate was found to be maximum during 8:00 am to 9:00 am and minimum during 8:00 pm to 10:00 pm. For the annual data, the exposure rate was the minimum during the month of February. The exposure rate increased from February to mid-October (except during the period from May to July with no change) and decreased from October to February. The seasonal variation was found to be about $1{\mu}R/h$. Most of the measured values (96%) of the exposure rates fell under the normal distribution with a deviation of less than 4.8% and the remaining 4% had large fluctuations caused mainly by the rainfalls.

• 한국산업보건학회지
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• 제30권2호
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• pp.185-195
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• 2020

Objectives: The purpose of this study was to analyze noise exposure levels and the rate of exceedance of exposure limits in workplaces from a 2015 measurement of working environments according to area, industry, and scale of workplace and to determine changes compared to the past. Methods: Among the 408,875 measurements of noise in working environments from 27,030 workplaces in 2015, 16,359 workplaces that were linked to special health examination data were selected as the subjects of this study. The eight-hour corrected measurements and geometric mean values of the individual noise measurements of the workplaces were used to calculate noise exposure levels and the exceedance rate of exposure limits. Results: The average noise exposure level of the overall workplaces making up the subjects of this study was 83.6 dBA, and the exceedance rate of exposure limits was 15.1%. At least half of the noise measurements exceeded the exposure limits in 13.7% of the workplaces. Noise exposure levels were higher in the manufacturing industry and in smaller-scale workplaces. The exceedance rate of noise exposure limits was higher in the mining and manufacturing industries and in smaller-scale workplaces. Conclusions: Noise exposure has shown improvements compared to the past, but the exceedance rate of exposure limits was still high, and more than half of the workers were being exposed to noise of 85 dBA or higher. Therefore, it is necessary to make more active improvements in working environments in terms of noise exposure.

• Journal of Radiation Protection and Research
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• 제26권2호
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• pp.113-117
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• 2001

NaI 스펙트럼으로부터 조사선량을 계산하는 에너지대 방법은 $1300{\sim}3000keV$ 영역의 에너지 스펙트럼을 사용하여 조사선량을 계산하기 때문에 자연방사선만의 조사선량이 계산되어지지만, 총에너지 방법은 $150{\sim}3400keV$ 영역의 에너지 스펙트럼을 사용하기 때문에 인공방사선의 조사선량도 포함하여 계산한다. 따라서 총에너지 방법에 의한 조사선량과 에너지대 방법에 의한 조사선량의 차이는 인공방사선에 의한 조사선량이 될 것이다. 본 연구에서는 인공방사선이 없는 지역에서 단지 기상요인에 의해서 조사선량 변동이 심한 기간동안 NaI 검출기로 스펙트럼을 측정하였다. 이와 같이 측정한 스펙트럼에 대해서 두 방법으로 계산한 조사선량률들은 통계적 변동 ${\pm}0.3{\mu}R\;h^{-1}$ 이내에서 잘 일치하였다. 결과적으로 두 방법에 의해 계산된 조사선량값이 차이가 있다면 그것은 인공방사선에 의한 조사선량으로 해석할 수 있을 것이다.

• Corrosion Science and Technology
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• 제2권4호
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• pp.183-188
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• 2003

Corrosion of carbon and weathering steels were evaluated under 3 environmental exposures in Thailand (urban, rural and marine) for a year. The seasonal study was designed to determine different corrosion mechanisms by 6 months of dry season and 6 months of rainy season in a year. The sheltered exposure racks were used to determine the washing effect of min. At each site, climatic and pollutants analyses were carried out. The present study showed that the difference in corrosion rates of carbon and weathering steels was not so distinguished in both rural (AIT) and urban (TISTR) environments. The corrosion rate of weathering steel was somewhat lower than that of carbon steel and the decreasing tendency of corrosion rate with time was slightly higher for weathering steel than for carbon steel. In marine (Rayong) environment, the corrosion rate was higher and the effect of wet and dry seasons was observed. The corrosion rate in 6 dry months was higher for direct exposure than for sheltered exposure. However, in 6 rainy months. the corrosion rate of sheltered exposure was higher than that of direct exposure. In direct exposure for I year, that is, the first 6 dry months and the next 6 rainy months, the corrosion rate decreased with time. but in sheltered exposure, the corrosion rate did not decrease with time. instead, increased in the next 6 rainy months. This indicated that the protect ive layer formed in the first 6 dry months could be destroyed by high deposition of chloride to r sheltered exposure in the next 6 rainy months; whereas the rust layer for direct exposure could be kept sound due to washing effect in rainy season, even though the deposition rate of chloride was almost the same for direct and sheltered exposures. In marine environment, the weathering steel showed higher corrosion resistance than carbon steel but its corrosion rate was higher than those in other environments.

• 재무관리연구
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• 제25권4호
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• pp.53-78
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• 2008

외국인 투자자가 한국 시장에 투자를 하는 경우 외국인 투자자는 투자자산에 내재된 환위험과 함께 수익을 환산하는 과정에서의 환위험에 노출된다. 외국인 투자자의 이러한 상황은 투자자산에 내재된 환위험만을 고려하면 되는 국내 투자자와는 구분되는 상황이다. 이러한 차이는 외국인 투자자가 환위험에 대해 국내 투자자와는 다르게 반응하는 원인이 될 수 있다. 환위험에 관한 국내의 기존 연구는 한국 기업들이 환위험에 노출되어 있고 이에 대한 관리가 필요하다는 점을 잘 보여주었다. 또한 동일한 시장이라 하더라도 시장 참여자의 특성에 따라 시장이 분할 될 수 있다는 증거들이 보고되었다. 이러한 기존 연구 결과는 환위험이 시장을 분할하는 요인이 될 수 있음을 지지하는 것이다. 이 연구는 한국유가증권시장에서 외국인 투자자들의 환위험에 대한 반응을 거래량 자료와 주문량 자료를 이용하여 분석하였다. 분석 결과 외국인 투자자는 환위험을 나타내는 공분산이 음수인 경우 매도거래를 증가시킨다. 이는 환율이 상승하면서 주식수익률이 하락하는 환위험을 적극적으로 관리하기 위한 거래의 결과로 해석할 수 있다. 주문자료에 대한 분석 결과도 이러한 해석을 뒷받침한다. 한편, 외국인 투자자는 공분산이 음수인 경우 매입거래도 증가시키는 것으로 분석되었는데 이는 환율이 하락하면서 주식수익률이 상승하고 투자수익의 환산이익도 함께 증가하는 관계를 적극적으로 활용하기 위한 거래의 결과로 해석할 수 있다. 그러나 외국인 투자자의 매입주문비율 분석 결과는 거래자료 분석 결과와는 달리 유의적인 결과가 나타나지 않았다. 이 연구의 분석 결과는 외국인 투자자는 국내 자산에 내재된 환위험에 대해서 국내 투자자와는 다른 반응을 보인다는 가설을 지지한다. 외국인 투자자는 환율이 상승(하락)하는 경우 기업가치가 상승(하락)하는 방향의 환위험에서는 국내 투자자와 차별적인 반응을 보이지 않는다. 그러나 환율이 상승(하락)하면 기업 가치가 하락(상승)하는 방향의 환위험에서는 국내투자에 비해 거래를 증가시키는 차별적인 특성을 보인다. 이러한 결과는 한국유가증권시장에서 외국인투자자는 환위험에 대하여 국내 투자자와는 다른 평가를 하고 있으며 이러한 차이는 투자자산의 평가에 반영되고 있음을 나타낸다.

• 대한의생명과학회지
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• 제22권4호
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• pp.199-206
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• 2016

Pesticides are widely used to prevent loss of agricultural production but extensive exposure can induce health problems to pesticide operators. This study was performed to evaluate the health risk of highly produced pesticides used in fruit growing farm land by comparison of estimated exposure level with AOEL using KO-POEM program. AOEL was driven based on NOAEL of each pesticide evaluated by JMPR, EFSA or KRDA. In calculation of exposure level, types of formulation, dilution factors, spraying duration and motor type and exposure protection device were allocated according to actual condition of use. Dermal absorption rate was differently applied among EFSA default values (25% or 75%), general default value (10%) or real test result values to know the plausibility of default values and safety of pesticide to operators in outline. Twenty pesticide ingredients (fungicides and insecticides) were produced more than 30 tons per year, which were mancozeb, chlorothalonil, imidaclopirid and etc in order. Dermal absorption rates obtained from studies were various from 0.07 to 81% but mostly under 10%. The estimated exposure levels showed big differences more than 10 times higher when using EFSA default rate and up to 5 times higher when using general rate of 10% comparing using rates of test results. Mancozeb, chlorthalonil, diazinon and chlorpyrifos presented still higher exposure level than AOEL even when using test absorption rate from study, which suggests that re-evaluation of AOEL or dermal exposure absorption rate or strict management are required for health protection of operators who use those four pesticides in farm land.

• 한국환경보건학회지
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• 제48권2호
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• pp.59-65
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• 2022

Background: Since people move through microenvironments rather than staying in one place, they may be exposed to both indoor and outdoor PM_2.5 concentrations. Objectives: The aim of this study was to assess the exposure level of each sub-population group and evaluate the contribution rate of the major microenvironments. Methods: Exposure scenarios for sub-population groups were constructed on the basis of a 2019 Time-Use survey and the previous literature. A total of five population groups were classified and researchers wearing MicroPEM simulated monitoring PM_2.5 exposure concentrations in real-time over three days. The exposure contribution for each microenvironment were evaluated by multiplying the inhalation rate and the PM_2.5 exposure concentration levels. Results: Mean PM_2.5 concentrations were 33.0 ㎍/m³ and 22.5 ㎍/m³ in Guro-gu and Wonju, respectively. When the exposure was calculated considering each inhalation rate and concentration, the home showed the highest exposure contribution rate for PM_2.5. As for preschool children, it was 90.8% in Guro-gu, 94.1% in Wonju. For students it was 65.3% and 67.3%. For housewives it was 98.2% and 95.8%, and 59.5% and 91.7% for office workers. Both regions had higher exposure to PM_2.5 among the elderly compared to other populations, and their PM_2.5 exposure contribution rates were 98.3% and 94.1% at home for Guro-gu and Wonju, respectively. Conclusions: The exposure contribution rate could be dependent on time spent in microenvironments. Notably, the contribution rate of exposure to PM_2.5 at home was the highest because most people spend the longest time at home. Therefore, microenvironments such as home with a higher contribution rate of exposure to PM_2.5 could be managed to upgrade public health.

• 한국환경보건학회지
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• 제32권4호
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• pp.268-274
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• 2006

In this study in order to evaluate the growth of RF propagation exposure rate generated according to the enhancement of its use, it is proposed for the ground to be able to examine and to contemplate the correlation between the human health and RF propagation exposure rate by measuring and analyzing the RF exposure source and exposure rate in an indoor environment. As a result of research, it is analyzed that the main exposure source of critically making effect in indoor environment is the frequency hand if radio broadcasting, mobile communication, wireless LAN, digital broadcasting, home appliance, etc., including the TV broadcasting. Among these, it is shown that the TV broadcasting and mobile communication band are the highest. And it is the concluded that RF exposure rate of the environmental sensitive equipment, like an institution for the aged, has lower possibility to exceed the human RF protection criteria by this evaluation.

• 환경생물
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• 제42권1호
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• pp.1-14
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• 2024

This study evaluated the risk of single and combined exposure to microplastics in zebrafish (Danio rerio) through biomarkers, such as survival rate, excretion rate, and histological alterations of organ systems. The experimental groups were the control(Cont.), single microplastics exposure group(MPs, 1.83%/fish total weight(g)), the copper group(Cu, 21.6 ㎍ L^-1), and a group with combined exposure to MPs and copper (MPs^*Cu). The experiment was conducted with individual exposure (7 days) for MP excretion rate analysis and group exposure (14 days) for biomarker analysis. The daily excretion rate of MPs tended to decrease in a time-dependent manner. The copper concentration in the body was not significantly different between single and combined copper exposure. The degeneration of mucous cells in the skin, capillary dilation of the gill lamella, increased intestinal mucous, hepatocyte hypertrophy, and the degeneration of glomeruli and renal tubules were observed in all exposure groups. These histological alterations showed the highest tendency in the MPs^*Cu group. In this study, the changes in biomarkers were attributed to the single effect of copper or the combined effect of copper and MPs rather than being solely influenced by MPs.