• Sleep Medicine and Psychophysiology
• /
• v.9 no.1
• /
• pp.41-47
• /
• 2002

Objectives: In a number of simulated night shift studies, timed exposure to bright light improves sleep quality and work performance. We evaluated the effect of bright light on adaptation to night shift work with a field study. Methods: Five female nurses working shifts at Korea University Hospital were recruited for participation in this study. We investigated two series of six consecutive shift rotations comprising three day and three night shifts, using wrist Actigraphy, the Stanford Sleepiness Scale, Visual-analogue scales, STIM and tympanic membrane temperature for daytime sleep quality, alertness, subjective feeling, attention performance, and temperature rhythm. The subjects were exposed to bright light (2,500 lux) from 24:00 to 04:00 a.m. on three consecutive night shifts during the second series, whereas they worked under normal lightening (650 lux) conditions during the first series. Results: Actigraphic assessment of daytime sleep showed no significant difference between the first and third night shift in both baseline and light exposure phase. The mean lowest temperature shifted earlier during baseline phase but not during the light exposure phase. Also, the score for subjective feelings of depression, anxiety, physical discomfort and sleepiness was significantly higher in the third night shift than the first during baseline phase but not during the light exposure phase. Attention and attention switching ability was significantly improved in the third night shift compared to the first night during the light exposure phase but there were no significant changes during the baseline phase. Conclusion: This result suggests that there were no significant differences between the two phases in measures of quality of daytime sleep, but subjective feelings, attention and alertness were enhanced during light exposure. Although some placebo effects and learning effects might influence this result, bright light exposure between midnight and 4:00 a.m. may improve adaptation to night shift. In future, further controlled studies with a larger sample size, including melatonin measurement, are needed for real shift workers.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.30 no.4
• /
• pp.342-352
• /
• 2020

Objectives: The characteristics of research workers are different from those working in the manufacturing industry. Furthermore, the reagents used change according to the research due to the characteristics of the laboratory, and the amounts used vary. In addition, since the working time changes almost every day, it is difficult to adjust the time according to exposure standards. There are also difficulties in setting standards as in the manufacturing industry since laboratory environments and the types of experiments performed are all different. For these reasons, the measurement of the working environment of research workers is not realistically carried out within the legal framework, there is a concern that the accuracy of measurement results may be degraded, and there are difficulties in securing data. The exposure evaluation based on an eight-hour time-weighted average used for measuring the working environment to be studied in this study may not be appropriate, but it was judged and consequently applied as the most suitable method among the recognized test methods. Methods: The investigation of the use of chemical substances in the research laboratory, which is the subject of this study, was conducted in the order of carrying out work environment measurement, sample analysis, and result analysis. In the case of the use of chemical substances, after organizing the substances to be measured in the working environment, the research workers were asked to write down the status, frequency, and period of use. Work environment measurement and sample analysis were conducted by a recognized test method, and the results were compared with the exposure standards (TWA: time weighted average value) for chemical substances and physical factors. Results: For the substances subject to work environment measurement, the department of chemical engineering was the most exposed, followed by the department of chemistry. This can lead to exposure to a variety of chemicals in departmental laboratories that primarily deal with chemicals, including acetone, hydrogen peroxide, nitric acid, sodium hydroxide, and normal hexane. Hydrogen chloride was measured higher than the average level of domestic work environment measurements. This can suggest that researchers in research activities should also be managed within the work environment measurement system. As a result of a comparison between the professional science and technology service industry and the education service industry, which are the most similar business types to university research laboratories among the domestic work environment measurements provided by the Korea Safety and Health Agency, acetone, dichloromethane, hydrogen peroxide, sodium hydroxide, nitric acid, normal hexane, and hydrogen chloride are items that appear higher than the average level. This can also be expressed as a basis for supporting management within the work environment measurement system. Conclusions: In the case of research activity workers' work environment measurement and management, specific details can be presented as follows. When changing projects and research, work environment measurement is carried out, and work environment measurement targets and methods are determined by the measurement and analysis method determined by the Ministry of Employment and Labor. The measurement results and exposure standards apply exposure standards for chemical substances and physical factors by the Ministry of Employment and Labor. Implementation costs include safety management expenses and submission of improvement plans when exposure standards are exceeded. The results of this study were presented only for the measurement of the working environment among the minimum health management measures for research workers, but it is necessary to prepare a system to improve the level of safety and health.

• Journal of Intelligence and Information Systems
• /
• v.23 no.1
• /
• pp.127-141
• /
• 2017

Advances in Internet technologies and the proliferation of mobile devices enabled consumers to approach a wide range of goods and services, while causing an adverse effect that they have hard time reaching their congenial items even if they devote much time to searching for them. Accordingly, businesses are using the recommender systems to provide tools for consumers to find the desired items more easily. Association Rule Mining (ARM) technology is advantageous to recommender systems in that ARM provides intuitive form of a rule with interestingness measures (support, confidence, and lift) describing the relationship between items. Given an item, its relevant items can be distinguished with the help of the measures that show the strength of relationship between items. Based on the strength, the most pertinent items can be chosen among other items and exposed to a given item's web page. However, the diversity of the measures may confuse which items are more recommendable. Given two rules, for example, one rule's support and confidence may not be concurrently superior to the other rule's. Such discrepancy of the measures in distinguishing one rule's superiority from other rules may cause difficulty in selecting proper items for recommendation. In addition, in an online environment where a web page or mobile screen can provide a limited number of recommendations that attract consumer interest, the prudent selection of items to be included in the list of recommendations is very important. The exposure of items of little interest may lead consumers to ignore the recommendations. Then, such consumers will possibly not pay attention to other forms of marketing activities. Therefore, the measures should be aligned with the probability of consumer's acceptance of recommendations. For this reason, this study proposes a model-based approach to combine those measures into one unified measure that can consistently determine the ranking of recommended items. A regression model was designed to describe how well the measures (independent variables; i.e., support, confidence, and lift) explain consumer's acceptance of recommendations (dependent variables, hit rate of recommended items). The model is intuitive to understand and easy to use in that the equation consists of the commonly used measures for ARM and can be used in the estimation of hit rates. The experiment using transaction data from one of the Korea's largest online shopping malls was conducted to show that the proposed model can improve the hit rates of recommendations. From the top of the list to 13th place, recommended items in the higher rakings from the proposed model show the higher hit rates than those from the competitive model's. The result shows that the proposed model's performance is superior to the competitive model's in online recommendation environment. In a web page, consumers are provided around ten recommendations with which the proposed model outperforms. Moreover, a mobile device cannot expose many items simultaneously due to its limited screen size. Therefore, the result shows that the newly devised recommendation technique is suitable for the mobile recommender systems. While this study has been conducted to cover the cross-selling in online shopping malls that handle merchandise, the proposed method can be expected to be applied in various situations under which association rules apply. For example, this model can be applied to medical diagnostic systems that predict candidate diseases from a patient's symptoms. To increase the efficiency of the model, additional variables will need to be considered for the elaboration of the model in future studies. For example, price can be a good candidate for an explanatory variable because it has a major impact on consumer purchase decisions. If the prices of recommended items are much higher than the items in which a consumer is interested, the consumer may hesitate to accept the recommendations.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_4
• /
• pp.1267-1276
• /
• 2020

To quantitatively predict the impacts of large-scale volcanic eruptions of Mt. Baekdu on air quality and damage around the Korean Peninsula, a three-dimensional chemistry-transport modeling system (Weather Research & Forecasting - Sparse Matrix Operation Kernel Emission - Comunity Multi-scale Air Quality) was adopted. A worst-case meteorology scenario was selected to estimate the direct impact on Korea. This study applied the typical worst-case scenarios that are likely to cause significant damage to Korea among worst-case volcanic eruptions of Mt. Baekdu in the past decade (2005~2014) and assumed a massive VEI 4 volcanic eruption on May 16, 2012, to analyze the concentration of PM_2.5 caused by the volcanic eruption. The effects of air quality in each region-cities, counties, boroughs-were estimated, and vulnerable areas were derived by conducting an exposure assessment reflecting vulnerable groups. Moreover, the effects of cities, counties, and boroughs were analyzed with a high-resolution scale (9 km × 9 km) to derive vulnerable areas within the regions. As a result of analyzing the typical worst-case volcanic eruptions of Mt. Baekdu, a discrepancy was shown in areas between high PM_2.5 concentration, high population density, and where vulnerable groups are concentrated. From the result, PM_2.5 peak concentration was about 24,547 ㎍/㎥, which is estimated to be a more serious situation than the eruption of Mt. St. Helensin 1980, which is known for 540 million tons of volcanic ash. Paju, Gimpo, Goyang, Ganghwa, Sancheong, Hadong showed to have a high PM_2.5 concentration. Paju appeared to be the most vulnerable area from the exposure assessment. While areas estimated with a high concentration of air pollutants are important, it is also necessary to develop plans and measures considering densely populated areas or areas with high concentrations of susceptible population or vulnerable groups. Also, establishing measures for each vulnerable area by selecting high concentration areas within cities, counties, and boroughs rather than establishing uniform measures for all regions is needed. This study will provide the foundation for developing the standards for disaster declaration and preemptive response systems for volcanic eruptions.

• Journal of Environmental Impact Assessment
• /
• v.19 no.3
• /
• pp.271-279
• /
• 2010

We conducted a quantitative human health risk assessment with respect to inhalation of heavy metals for residents of housing developments in "new towns" where an incinerator will be operated within the area scheduled for construction thereof. To assess potential human health risk we calculated the amount of heavy metals emitted from the incinerator, and then forecasted the potential health impact on adjoining areas where new housing is to be developed (i.e. "new towns") at different altitudes by a using SCREEN-3 model. We assessed Cancer Risk (CR) caused by known carcinogens using the Inhalation Unit Risk criteria developed by the US Environmental Protection Agency. Notably, we assessed risk by determining concentrations of heavy metals on a floor by floor basis, as apartment buildings are to be constructed near the incinerator according to a pre-devised plan. Results indicated that cancer risk for most carcinogens exceeded US EPA standards for the highest locations at each collection point. This result indicates that construction of high buildings in areas adjoining incinerators is undesirable, and that measures to lower carcinogens are needed. The results of this study, which assessed health risk from exposure to heavy metals emitted from a nearby incinerator, can be useful in land use planning with respect to the location of housing developments in new towns, as well as the heights of any buildings constructed. Furthermore, the methodology deployed herein with respect to risk assessment can be helpful for policy makers and the general public in the event of conflicts regarding incinerator projects in the future. The results herein may also be of merit in determining priorities when establishing harm reduction measures for carcinogens at incinerators. However, the study does contain several limitations. The SCREEN-3 model, a kind of screening model that provides conservative results, can provide higher forecasted concentrations of air pollutants than other models. Moreover, although the incinerator in question is set to be a thermoselect type, domestic data for emissions from these incinerators is not available, and assumptions were based on a stoker type incinerator. Insufficient domestic data likewise compelled the use of data of USA, resulting in possible errors in results. Continued research will thus be required to develop systematic methodologies that address the foregoing factors and produce more reliable outcomes.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.2
• /
• pp.801-810
• /
• 2013

The main purpose of this study is to reframe sustainability or sustainable development concept in the field of planning in consideration of climate change and natural hazards. The new concept is expected to provide a theoretical foundation for upcoming hazard mitigation measures addressing climate change. The first and main argument of the new concept is that environmental protection should be inclusive enough to address urban (or community) security from current natural hazards. The second is that the balance between structural and nonstructural mitigation measures is critical to cope more effectively with extreme natural hazards in the era of climate change and also with conflicts driven by three goals of sustainability--environmental protection, economic development, and social justice. The following studies, based on this new concept of sustainablity, are expected (1) to address new participation methods for the conflict resolution, (2) to explore detailed and substantive planning strategies and creative technical and institutional solutions for environmental protection, natural hazard mitigation, and conflict resolution. Two of APFM(the Associated Programme on Flood Management)'s three natural hazard risk criteria, Exposure and Vulnerability, may guide the exploration.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.10
• /
• pp.4661-4664
• /
• 2016

Background: Artificial light at night (ALAN) has been linked to increased risk of cancers in body sites like the breast and colorectum. However exposure of ALAN as an environmental risk factor and its relation to cancers in humans has never been studied in detail. Objective: To explore the association of ALAN with all forms of cancers in 158 countries. Materials and Methods: An ecological study encompassing global data was conducted from January to June 2015, with age-standardized rates (ASR) of cancers as the outcome measure. ALAN, in the protected areas, as the exposure variable, was measured with reference to the Protected Area Light Pollution Indicator (PALI) and the Protected Area Human Influence Indicator (PAHI). Pearson's correlations were calculated for PALI and PAHI with ASR of cancers for 158 countries, adjusted for country populations, electricity consumption, air pollution, and total area covered by forest. Stratified analysis was conducted according to the country income levels. Linear regression was applied to measure the variation in cancers explained by PALI and PAHI. Results: PALI and PAHI were positively associated with ASR of all forms of cancer, and also the four most common cancers (p < 0.05). These positive correlations remained statistically significant for PAHI with all forms of cancer, lung, breast, and colorectal cancer after adjusting for confounders. Positive associations of PALI and PAHI with cancers varied with income level of the individual countries. Variation in all forms of cancers, and the four most common cancers explained by PALI and PAHI, ranged from 3.3 - 35.5%. Conclusion: Artificial light at night is significantly correlated for all forms of cancer as well as lung, breast, colorectal, and prostate cancers individually. Immediate measures should be taken to limit artificial light at night in the main cities around the world and also inside houses.

• The Korean Journal of Physiology and Pharmacology
• /
• v.22 no.2
• /
• pp.183-192
• /
• 2018

Post-traumatic stress disorder (PTSD) is a trauma-induced psychiatric disorder characterized by impaired fear extermination, hyperarousal, anxiety, depression, and amnesic symptoms that may involve the release of monoamines in the fear circuit. The present study measured several anxiety-related behavioral responses to examine the effects of berberine (BER) on symptoms of anxiety in rats after single prolonged stress (SPS) exposure, and to determine if BER reversed the dopamine (DA) dysfunction. Rats received BER (10, 20, or 30 mg/kg, intraperitoneally, once daily) for 14 days after SPS exposure. BER administration significantly increased the time spent in the open arms and reduced grooming behavior during the elevated plus maze test, and increased the time spent in the central zone and the number of central zone crossings in the open field test. BER restored neurochemical abnormalities and the SPS-induced decrease in DA tissue levels in the hippocampus and striatum. The increased DA concentration during BER treatment may partly be attributed to mRNA expression of tyrosine hydroxylase and the DA transporter in the hippocampus, while BER exerted no significant effects on vesicular monoamine transporter mRNA expression in the hippocampus of rats with PTSD. These results suggest that BER had anxiolytic-like effects on behavioral and biochemical measures associated with anxiety. These findings support a role for reduced anxiety altered DAergic transmission and reduced anxiety in rats with PTSD. Thus, BER may be a useful agent to treat or alleviate psychiatric disorders like those observed in patients with PTSD.

• Journal of Environmental Policy
• /
• v.8 no.2
• /
• pp.63-82
• /
• 2009

Because many people suffer from physical and mental damage caused by the noise created by transportation infrastructure, including road traffic, rail, and aircraft, developed countries have conducted research on predicting and solving the impact to human health from being exposed to transportation noise. Therefore, this study suggests a fundamental plan to assess the health impact of transportation noise on the basis of domestic and foreign prediction results regarding the health impact of transportation noise. The domestic and foreign exposure-response expressions, including the noise index and the health impact indicator of annoyance and sleep disturbance, are compared, and it is found that domestic individuals show a more sensitive response to transportation noise. Based on domestic and foreign research, and a case study regarding the health impact of transportation noise, a fundamental plan to assess the health impact of transportation noise comprises the preparation of objective assessment standards through the improvement of exposure-response models, and the establishment of reduction measures which can improve the quality of the transportation noise environment.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.12
• /
• pp.5937-5946
• /
• 2012

The term endocrine disruptors is used to describe a variety of natural and manmade substances that have the capacity to potentially interfere with and modify the normal physiology of endocrine system either by mimicking, blocking or modulating the actions of natural endogenous hormones. The rising incidence of breast cancer over the last 50 years and the documented higher incidence in urban as compared to rural areas suggest a relationship to the introduction and increased use of xenoestrogens in our environment. The literature has developed over the last decades where initial experiments on endocrine disruptors did not support an involvement in breast cancer, and then evidence mounted implicating various environmental factors including hormones, endocrine disrupting chemicals and non-endocrine disrupting environmental carcinogens in the pathogenesis of breast cancer. Available data support the hypothesis that exposure to endocrine disruptors in utero leaves a signature on mammary gland morphogenesis so that the resulting dysgenic gland becomes more predisposed to develop tumors upon exposures to additional insults later on during life. Exceptionally, exposure to phytoestrogens could be beneficial to human health. Most of the available data are from well developed countries while the developing countries are still understudied regarding these issues. Here, we raise a note of caution about potential role of environmental toxins including endocrine disruptors in breast cancer development and call for serious measures to be taken by all involved parties in the developing world.