• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.125-134
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• 2020

This study examines the nominal price anomaly in the Vietnamese stock market, that is, whether stocks with low nominal price outperform stocks with high nominal price. Using a sample of all 351 companies listed on the Ho Chi Minh Stock Exchange (HOSE) from June 2009 to March 2018, we confirm our hypothesis and document that cheaper stocks yield higher subsequent abnormal returns. The results are robust after controlling for various stock characteristics that have been documented to be value-relevant in prior literature, including firm size, book-to-market ratio, intermediate-term momentum, short-term reversal, skewness, market risk, idiosyncratic risk, illiquidity and extreme daily returns, using both the portfolio analysis and the Fama-MacBeth cross-sectional regression. The negative effect persists in the long term (i.e., after up to 12 months), implying a slow adjustment of stock prices to their intrinsic value. Further analysis show that the observed nominal price anomaly is mainly driven by mispricing but not a latent risk factor proxied by stock price, thus the observed anomaly reflects a mispricing but not a fundamental risk. The study highlights the irrational behaviour of investors and market inefficiency in the Vietnamese stock market and provides important implication for investors in the market.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.249-255
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• 2023

In this study, radiation exposure doses were measured in the course of clinical practice of radiation workers, radiological technologists in the radiation-related worker group, and preliminary-radiological technologists who were classified as frequent visitors. Radiological technologists who worked in the radiation area of C University Hospital in Incheon for a year from January 2021 and 121 students who completed clinical practice at the same medical institution from July 1 to August 31 were the subjects of the study. The nominal risk factor based on ICRP 103 was used to evaluate the probability of side effects due to the exposure dose to the lungs, which are organs at risk of damage due to radiation exposure dose. During the clinical practice period, radiology students, who were classified as frequent visitors, had a surface dose of 0.98 ± 0.14 mSv and a deep dose of 0.93 ± 0.14 mSv. In other words, 6.7 per 1,000,000 for shallow dose and 6.4 per 1,000,000 for deep dose were found to have side effects due to exposure to the lungs. This is a value in terms of exposure dose in one year. Considering that the radiation (science) education course is 3 or 4 years, systematic management and attention to prospective radiation workers who are going to clinical practice are required, and the stochastic effect of radiation In relation to this, it is considered that it will be used as basic data for radiation safety management.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.351-356
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• 2022

The purpose of this study was to evaluate the cancer incidence rate and provide basic data by measuring the photoneutron dose generated during intensity-modulated radiation therapy and volumetric modulated arc therapy used in radiation therapy for prostate cancer. The optically stimulated luminescence albedo neutron dosimeter for neutron measurement was placed on the Rando phantom in the abdomen and thyroid and photoneutron dose generated was measured. As a result of the study, intensity-modulated radiation therapy (7 portal) was measured to be higher than volumetric rotational radiation therapy in both abdominal and thyroid locations. When the cancer incidence rate was evaluated using the nominal risk coefficient of ICRP 103, the cancer incidence rate due to exposure to the colon and thyroid during intensity-modulated radiation therapy was 9.9 per 1,000 people, and volumetric rotational radiation therapy for 1,000 people. It was 3.5 per person. Based on the principle of ALARA (As low as reasonably archievable), it is considered to be a guideline for minimizing the exposure dose to normal organs in the establishment of a radiation treatment plan.

• Journal of Biomedical Engineering Research
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• v.39 no.6
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• pp.243-249
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• 2018

The indoor radon concentration was measured in the lecture room of the university and the radon concentration was converted to the amount related to the radon exposure using the dose conversion convention and compared with the reference levels for the radon concentration control. The effect of indoor radon inhalation was evaluated by estimating the life effective dose and the risk of exposure. To measure the radon concentration, measurements were made with a radon meter and a dedicated analysis Capture Ver. 5.5 program in a university lecture room from January to February 2018. The radon concentration measurement was carried out for 5 consecutive hours for 24 hours after keeping the airtight condition for 12 hours before the measurement. Radon exposure risk was calculated using the radon dose and dose conversion factor. Indoor radon concentration, radon exposure risk, and annual effective dose were found within the 95% confidence interval as the minimum and maximum boundary ranges. The radon concentration in the lecture room was $43.1-79.1Bq/m^3$, and the maximum boundary range within the 95% confidence interval was $77.7Bq/m^3$. The annual effective dose was estimated to be 0.20-0.36 mSv/y (mean 0.28 mSv/y). The life-time effective dose was estimated to be 0.66-1.18 mSv (mean $0.93{\pm}0.08mSv$). Life effective doses were estimated to be 0.88-0.99 mSv and radon exposure risk was estimated to be 12.4 out of 10.9 per 100,000. Radon concentration was measured, dose effective dose was evaluated using dose conversion convention, and degree of health hazard by indoor radon exposure was evaluated by predicting radon exposure risk using nominal hazard coefficient. It was concluded that indoor living environment could be applied to other specific exposure situations.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.2075-2081
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• 2016

Background: Breast cancer incidence and mortality rates are increasing in North-Eastern Brazil and the patients with the disease often presented at advanced stages. The present study was focused on identifying variables that affect women's frequency of breast self- examination (BSE) performance. Materials and Methods: Data on BSE, socio-economic parameters and risk factors for breast cancer were obtained from 417 women from a community in North-Eastern Brazil by a self-informant method. To identify independent variables that affect frequency of BSE, nominal logistic regression analysis was performed. Results: Of 417 women, 330 (79.3%) reported performing BSE. Compared to high-income women, BSE performance by low-income women every month was 7.69 (OD=0.130; CI 95%: 0.044- 0.0386; p=0.000) times lower. Women who did not live in a stable union performed BSE each month 2.73 (OD=0.366; CI 95%: 0.171-0.782; p=0.010) less often than those living in a stable union. BSE performance every month and every six months or every year by women with poor knowledge about risk factors for breast cancer was 3.195 (OD=0.313; CI 95%: 0.141- 0.695; p=0.004) times and 2.028 (OD=0.493; CI 95%: 0.248- 0.979; p=0.043) times lower, compared to women with good knowledge. Participants who had a close relative with cancer performed BSE every month and every six months or every year 2.132 (OD=0.469; CI 95%: 0.220-0.997; p=0.049) times and 2.337 (OD=0.428; CI 95%: 0.219-0.836; p=0.013) times less often, compared to those women without close relatives with cancer. Conclusions: The results of this study indicated that income, marital status, knowledge about risk factors and having a close relative with breast cancer, affect the frequency of BSE performance. Information about risk factors in public health campaigns could additionally strengthen avoidance behaviour and also motivate BSE performance.

• Phonetics and Speech Sciences
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• v.3 no.1
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• pp.111-116
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• 2011

The purpose of this study was to analyze the association between self-reported voice problems and voice disorders in the Korean adult population. Data were collected from the 4th Korea National Health and Nutritional Examination Survey (2008) from 3,135 subjects (1,310 men and 1,825 women) aged 19 years and older. Multi-nominal logistic regression analyses were used to examine the association between self-reported voice problems and voice disorders in the Korean adult population. Adjusting for covariates (age, sex, education level, job, smoking, alcohol drinking, thyroid disorders, pain and discomfort during the last 2 weeks), self-reported voice problems included independently associated functional voice disorders (OR=4.70, 95% CI: 3.14-7.03) and organic voice disorders (OR=3.89, 95% CI: 1.57-9.65). The results of the present study verified that self-reported voice problems are valuable indicators for voice disorders. Further research is needed to ascertain the effect of self-reported voice problems on voice disorder in adults.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.125-132
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• 2011

Studies on the risk factors of voice disorders in Korean adults are rare. I evaluated the association between the duration of self-reported voice problem and voice disorders in Korean adults. Data were from the 2008 Korea National Health and Nutritional Examination Survey. Subjects were 3,135 people (1,310 men and 1,825 women) aged 19 years and older. Multi-nominal logistic regression analyses were used to examine the association between the duration of self-reported voice problem and voice disorders. The prevalence of self-reported voice problems was 5.9% among Korean adults. Adjusting for covariates (age, sex, education level, length of employment, tobacco consumption, alcohol consumption, thyroid disorders, pain and discomfort during the last two weeks), self-reported voice problems lasting longer than three weeks were independently associated with functional voice disorders (OR=5.30, 95% CI: 3.30-8.50) and organic voice disorders (OR=4.84, 95% CI: 1.82-12.89). Self-reported voice problems in the past three weeks were significantly associated with functional voice disorders (OR=3.64, 95% CI: 1.84-7.19), but not significantly associated with organic voice disorders. Self-reported voice problems are prevalent among adults. This study highlights that self-perception of a voice problem for more than three weeks is related to functional voice disorders and organic voice disorders.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.165-170
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• 2013

In this study, physico-chemical properties and environmental fate were investigated and ecotoxicity tests using fish, daphnia and algae were conducted for an initial ecological risk assessment of 1,2-Benzisothiazol-3-one. Due to low volatility of the test substance under environmental conditions, it is likely to distributed in soil and water environment. The compound has low adsorption in the soil, with low bioconcentration potential. Acute toxicity results showed that 96 h-$LC_{50}$ for Oryzias laties was 4.7 mg/L (measured) and 48h-$EC_{50}$ for Daphnia magna was 3.3 mg/L (measured). In a growth inhibition test with Pseudokirchneriella subcapitata, 72 h-$EC_{50}$ was 0.456 mg/L (growth rate, nominal) and 0.262 mg/L (yield, nominal). Using the acute toxicity value of algae, predicted no-effect concentration (PNEC) in the aquatic environment was determined to be 2.62 ${\mu}g/L$ using an factor of 100. According to globally harmonized system (GHS), the compound was categorized as aquatic acute 1 for algae, while it was categorized as aquatic acute 2 for fish and daphnia. This screening assessment suggests that the test substance may pose ecological risks in the aquatic environment.

• Journal of Radiation Protection and Research
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• v.46 no.1
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• pp.14-23
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• 2021

Background: For radiological protection and control, the International Commission on Radiological Protection (ICRP) provides the nominal risk coefficients related to radiation exposure, which can be extrapolated using the excess relative risk and excess absolute risk obtained from the Life Span Study of atomic bomb survivors in Hiroshima and Nagasaki with the dose and dose-rate effectiveness factor (DDREF). Materials and Methods: Since it is impossible to directly estimate the radiation risk at doses less than approximately 100 mSv only from epidemiological knowledge and data, support from radiation biology is absolutely imperative, and thus, several national and international bodies have advocated the importance of bridging knowledge between biology and epidemiology. Because of the accident at the Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi Nuclear Power Station in 2011, the exposure of the public to radiation has become a major concern and it was considered that the estimation of radiation risk should be more realistic to cope with the prevailing radiation exposure situation. Results and Discussion: To discuss the issues from wide aspects related to radiological protection, and to realize bridging knowledge between biology and epidemiology, we have established a research group to develop low-dose and low-dose-rate radiation risk estimation methodology, with the permission of the Japan Health Physics Society. Conclusion: The aim of the research group was to clarify the current situation and issues related to the risk estimation of low-dose and low-dose-rate radiation exposure from the viewpoints of different research fields, such as epidemiology, biology, modeling, and dosimetry, to identify a future strategy and roadmap to elucidate a more realistic estimation of risk against low-dose and low-dose-rate radiation exposure.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.357-363
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• 2022

This study aims to improve the safety inspection awareness of occupational exposure and help radiation safety management by analyzing radiation exposure doses by occupational type of radiation related-workers and radiation workers. Radiation-related workers and radiation workers were classified into three occupations (radiological technologist, doctors, and nurses). A nominal risk coefficient based on ICRP 103 was used to calculate the probability of causing side effects of the lungs due to exposure doses. As a result of analyzing the exposure dose of all workers for one year, the exposure dose of radiological technologist among radiation-related workers was 1.63 ± 2.84 mSv, doctors 0.12 ± 0.22 mSv, and nurses 0.59 ± 1.08 mSv. The one-year deep dose for radiation workers was 2.44 ± 3.30 mSv for radiological technologists, 0.19 ± 0.26 mSv for doctors, and 0.12 ± 0.00 mSv for nurses. Due to this dose, the probability of causing side effects in the lungs was 1.2 per 100,000 radiological technologist, 0.096 doctors, and 0.06 nurses. In this study, it is believed that the probability of side effects on lungs by occupation of radiation exposure dose will be studied and used as useful data for radiation safety management in relation to probabilistic effects in the future.