• Journal of Environmental Health Sciences
• /
• v.49 no.3
• /
• pp.159-168
• /
• 2023

Background: An ongoing environmental exposure assessment of humidifier disinfectants (HDs) has been conducted since November 2011 among individuals who experienced HD exposure-related adverse health effects. It is being performed in order to determine and quantify exposure to humidifier disinfectants in victims and their families. To date, the assessment has encompassed Cycles I-to-V. There is no report summarizing the characteristics of the subjects from the overall cycles. Objectives: We intended to examine the individual characteristics related to demographics, HD usage, and HD exposure using integrated data from Cycles I-to-V of the environmental exposure assessment of HDs and the changes with the cycles. Methods: We included 7,543 individuals who participated in Cycles I-to-V of the environmental exposure assessment of HDs. We summarized the participants' characteristics regarding their demographics (e.g., sex, education level, and age), HD usage history (e.g., product name, ingredient, and frequency of HD use), and HD exposure (e.g., daily time of HD use, cumulative time of HD use, and exposure intensity). In addition, their characteristics were compared across the cycles of the exposure assessment. Results: Among the 7,543 participants from Cycles I-to-V, there were more male participants than females (51.05% overall), except for Cycles I and III. Across all cycles, a higher proportion of survivors was observed than deceased individuals. While PHMG was the most prevalent ingredient in HDs throughout all the cycles, its proportion gradually decreased over the course of the examination cycles. Participants in Cycle I reported longer daily times of HD use compared to those in the subsequent cycles. On the other hand, cumulative time of HD use was shorter in the earlier cycles than in the later cycles. Conclusions: Using the integrated data from the full cycles of the environmental exposure assessment, this study identified changes in demographic characteristics as well as the HD exposure characteristics between the participants across different cycles.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.33 no.3
• /
• pp.375-383
• /
• 2023

Objectives: Coal-fired power plants feature diverse working conditions, including multi-layered employment structures and irregular work cycles due to outsourcing and non-standardized tasks. The current uniform occupational environment measurement systems have limitations in accurately assessing and evaluating these varied conditions. This study aims to propose alternative measurement and assessment strategies to supplement existing methods. Methods: Major domestic coal-fired power plants were selected as the study targets. To prepare for the study and establish strategies, work processes were identified and existing occupational environment measurement results were compared and analyzed. The study proceeded by employing three strategies: specific exposure groups (SEGs) measurement, continuous monitoring, and supplementary measurements, which were then compared and discussed. Results: Previous exposure index evaluations (5,268 cases) indicated that crystalline silica, a type of respirable particulate matter, had detection limits below the threshold (non-detectable) in 82.6% (4,349 cases) of instances. Exposures below 10% of the exposure limit were observed at a very low concentration of 96.1%. Similar exposure group measurements yielded results where detection limits were below the threshold in 38.2% of cases, and exposures below 10% of the limit were observed in 70.6%. Continuous monitoring indicated detection limits below the threshold in 12.6% of cases, and exposures below 10% of the limit were observed in 75.6%. Instances requiring active workplace management accounted for more than 30% of cases, with SEGs at 11.8% (four cases), showing a higher proportion compared to 3.0% (four cases) in continuous monitoring. For coal dust, exposures below 10% of the limit were highest in legal measurements at 90.2% (113 cases), followed by 74.0% (91 cases) in continuous monitoring, and 47.0% (16 cases) in SEGs. Instances exceeding 30% were most prevalent in SEGs at 14.7% (five cases), followed by legal measurements at 5.0% (eight cases), and continuous monitoring at 2.4% (three cases). When examining exposure levels through arithmetic means, crystalline silica was found to be 104.7% higher in SEGs at 0.0088 mg/m³ compared to 0.0043 mg/m³ in continuous monitoring. Coal dust measurements were highest in SEGs at 0.1247 mg/m³, followed by 0.1224 mg/m³ in legal measurements, and 0.0935 mg/m³ in continuous monitoring. Conclusions: Strategies involving SEGs measurement and continuous monitoring can enhance measurement reliability in environments with irregular work processes and frequent fluctuations in working conditions, as observed in coal-fired power plants. These strategies reduce the likelihood of omitting or underestimating processes and enhance measurement accuracy. In particular, a significant reduction in detection limits below the threshold for crystalline silica was observed. Supplementary measurements can identify worker exposure characteristics, uncover potential risks in blind spots of management, and provide a complementary method for legal measurements.

• Journal of Practical Engineering Education
• /
• v.15 no.2
• /
• pp.243-258
• /
• 2023

The purpose of this study is to examine the mediating effect of organizational commitment in the relationship between transformational and transactional leadership and innovative behavior and demonstrate the moderated mediating effect of job satisfaction. To this end, 4,133 cases from the 『2021 Public Servant Life Survey』 conducted to general public servants belonging to central administrative agencies and metropolitan governments by the Korea Institute of Public Administration were used for the analysis, and SPSS 21.0 and Mplus 8.4 programs were used to test the research hypotheses. As a result of the analysis, it was confirmed that transformational and transactional leadership had a positive effect on organizational commitment and innovative behavior, and organizational commitment had a positive effect on innovative behavior. In addition, it was confirmed to have a significant mediating effect in the relationship between transformational and transactional leadership and innovative behavior. Finally, it was confirmed that the mediating effect of transformational and transactional leadership on innovative behavior through organizational commitment was moderated by the level of job satisfaction, and all the proposed hypotheses were adopted. Based on theses findings, theoretical and practical suggestions and future research suggestions were discussed.

• Journal of Korean Physical Therapy Science
• /
• v.30 no.4
• /
• pp.82-91
• /
• 2023

Background: Randomized controlled trials (RCTs) provide evidence on the effectiveness and safety of interventions and inform systematic reviews and guideline preparation for clinical application. However, methodological flaws can occur in many RCTs, and Cochrane's risk of bias version 2 (RoB2) can be used to evaluate RCTs' risk of bias (RoB). However, physical therapy RCTs in Korea did not confirm RoB. Therefore, the purpose of this study was to evaluate RoB using RoB2 in RCTs published in the Korean Physical Therapy Journal. Design: Review. Methods: The RCTs subject to evaluation were RCTs published in 11 physical therapy journals in Korea from 2018 to 2022. RoB2 evaluated a total of five domains: bias arising from the randomization process, bias due to deviations from intended interventions, bias due to missing outcome data, bias in measurement of the outcome, and bias in selection of the reported result. Results: A total of 616 RCTs were evaluated. As for bias arising from the randomization process, high risk was the highest at 555 (90.1%), followed by low risk at 41 (6.7%) and some concerns at 20 (3.2%). For bias due to deviations from intended interventions, the proportion of some concerns was the highest at 390 (63.3%), followed by high risk at 218 (35.4%) and low risk at 8 (1.3%). As for the bias due to missing outcome data, the rate of low risk was the highest at 399 (64.8%), followed by high risk at 159 (25.8%) and some concerns at 58 (9.4%). As for bias in measurement of the outcome, high risk was the highest at 294 (47.7%), followed by low risk at 224 (36.4%) and some concerns at 98 (15.9%). In the bias due to missing outcome data, the ratio of high risk was the highest at 610 (99%), followed by low risk at 4 (0.7%) and some concerns at 2 (0.3%). Conclusion: Most of the RoB evaluation results of RCTs published in the Korean Physical Therapy Journal were rated as high risk. Methodological quality of RCTs needs to be improved.

• The Journal of Engineering Geology
• /
• v.33 no.4
• /
• pp.519-530
• /
• 2023

Moye's analytical solution was examined as a method for constant-head tests under steady-state conditions, and results were compared with transient-state analyses in in situ hydraulic tests. The sensitivity of hydraulic conductivities calculated using Moye's method increased with the length of the test section, which should be as large as possible under test conditions. Particularly in low-permeability media with less than 10^-8 m/sec of hydraulic conductivity, hydraulic conductivity is lower than that under transient-state conditions and can be recalculated by adjusting the boundary between radial and spherical flow assumed in Moye's equation. Constant-head tests performed in the research borehole at the KAERI Underground Research Tunnel (KURT) indicated that transmissivities derived from the constant-head withdrawal test under transient-state conditions in low-permeability media were higher than those derived from steady-state tests, likely because the groundwater flow boundary was smaller than the "half of the test-section length"assumed by Moye's equation. When interpreting constant-head test results for crystalline rock, the hydrogeological properties of the medium may be better understood by considering assumed conditions accompanying analysis of the steady-state condition and comparing them with results for the transient-state analysis, rather than simply assuming properties based on steady-state analyses.

• 대한상한금궤의학회지
• /
• v.14 no.1
• /
• pp.1-26
• /
• 2022

Objectives: We aimed to confirm the safety and effectiveness of the decoction of Sibjo-tang, which is a powder type purgative. In addition, we checked whether the '發作' of 『Shanghanlun』 can be interpreted to have the same meaning as "seizure" in English. By confirming these objectives, we intend to lead the progress in the application of Sibjo-tang and to expand the clinical application of the 152nd provision and Sibjo-tang. Methods: We analyzed the medical records of patients who visited Apgujeongjeongin Oriental Clinic and Almyeon Oriental Clinic for seizures. We confirmed side effects in patients who took Sibjo-tang for a long time. Sibjo-tang was prepared as a hot water extract by using 5 g each of Euphorbiae Pekinensis Radix, Eurphobiae Kansui Radix, and Genkwae Flos and 15 g of Zizyphi Fructus. The "seizure" recorded in the 152nd provision was interpreted through the shape analysis of Oracle bone scripts. The seizure frequency of patients diagnosed with epilepsy after taking Sibjo-tang was compared, and we analyzed other symptoms and psychosocial conditions associated with seizures at the first episode. Results: No side effects were found in 7 patients who took Sibjo-tang for 16.57 ± 14.10 months. Seizures were eliminated in 6 cases while taking Sibjo-tang and significantly decreased in 1 case. Frequent indigestion (in 7 cases), mild exhaustion (in 5 cases), and inferiority complex (in 5 cases) were identified as accompanying pathogenic conditions. The "seizure" in the 152nd provision was interpreted as "a state of being stabbed by a sharp substance in clothes", confirming a deep connection with epileptic seizures. Conclusions: The results suggest that using a decoction of Sibjo-tang is safe and efficacious. In addition, the necessity of conducting an advanced study on epileptic seizures accompanied by frequent indigestion using Sibjo-tang was confirmed.

• Journal of Korea Water Resources Association
• /
• v.56 no.11
• /
• pp.721-728
• /
• 2023

Agricultural drought is triggered by a depletion of moisture content in the soil, which hinders photosynthesis and thus increases carbon dioxide (CO₂) concentrations in the atmosphere. The aim of this study is to analyze the relationship between soil moisture (SM) and vegetation activity toward quantifying CO₂ concentration in the atmosphere. To this end, the MODerate resolution imaging spectroradiometer (MODIS), an optical multispectral sensor, was used to evaluate two regions in South Korea for validation. Vegetation activity was analyzed through MOD13A1 vegetation indices products, and MODIS gross primary productivity (GPP) product was used to calculate the CO₂ flux based on its relationship with respiration. In the case of SM, it was calculated through the method of applying apparent thermal inertia (ATI) in combination with land surface temperature and albedo. To validate the SM and CO₂ flux, flux tower data was used which are the observed measurement values for the extreme drought period of 2014 and 2015 in South Korea. These two variables were analyzed for temporal variation on flux tower data as daily time scale, and the relationship with vegetation index (VI) was synthesized and analyzed on a monthly scale. The highest correlation between SM and VI (correlation coefficient (r) = 0.82) was observed at a time lag of one month, and that between VI and CO₂ (r = 0.81) at half month. This regional study suggests a potential capability of MODIS-based SM, VI, and CO₂ flux, which can be applied to an assessment of the global view of the agricultural drought by using available satellite remote sensing products.

• The Korea Journal of Herbology
• /
• v.39 no.3
• /
• pp.107-114
• /
• 2024

Objective : Cicadae Periostracum (CP), which is the discarded shell of the Cryptotympana atrata (Fabricius, 1775), is a recognized component of oriental medicine for treatment sore throat, itching, shock, sedation, edema. However, the safety and toxicity of CP have not yet been established. It has been reported that symptoms of addiction or side effects may occur in patients who take high doses of CP or who are hypersensitive to it. Therefore, we investigated the acute toxicity of an CP extracts in Sprague-Dawley (SD) rats. Methods : To study acute toxicity, five SD rats of each sex per group were treated with CP extracts at single doses of 0, 500, 1000, or 2000 mg/kg administrated by oral gavage, and body weight, clinical signs, and mortality were observed after dosing. At the end of 14-day observation period, all animals were sacrificed and complete hematological and macroscopic examinations were performed. Results : There were no dead animal and test article-related effects on body weight change or the gross finding. No toxicologically significant results were observed between control and treated groups in hematology. Although salivation related to stress at the highest dose was observed in clinical signs immediately after administration, it is considered to have no toxicological significance. Conclusion : As the results, we did not find any adverse effect at the dose levels of 500, 1000, or 2000 mg/kg in rats. The minimal lethal dose was considered to be over 2000 mg/kg body weight in rats.

• Journal of Navigation and Port Research
• /
• v.48 no.3
• /
• pp.214-220
• /
• 2024

Remote control is used for operating maritime autonomous surface ships. The operator controls the ship using control data generated by the remote control system. To ensure successful remote control, three principles must be followed: safety, reliability, and availability. To achieve this, the suitability of both the control data and operators for remote control must be established. Currently, there are no international regulations in place for evaluating remote control suitability through experiments on actual ships. Conducting such experiments is dangerous, costly, and time-consuming. The goal of this study is to develop a suitability evaluation method using the output values of control devices used in actual ship operation. The proposed method involves evaluating the suitability of data by analyzing the output values and evaluating the suitability of operators by examining their tracking of these output values. The experiment was conducted using a shore-based remote control system to operate the training ship 'Hannara' of Korea National Maritime and Ocean University. The experiment involved an iterative process of obtaining the operator's tracking value for the output value of the ship's control devices and transmitting and receiving tracking data between the ship and the shore. The evaluation results showed that the transmission and reception performance of control data was suitable for remote operation. However, the operator's tracking performance revealed a need for further education and training. Therefore, the proposed evaluation method can be applied to assess the suitability and analyze both the control data and the operator's compliance with the three principles of remote control.

• Steel and Composite Structures
• /
• v.50 no.3
• /
• pp.281-298
• /
• 2024

Stainless steel bolts (SSB) are increasingly utilized in bolted steel connections due to their good mechanical performance and excellent corrosion resistance. Fire accidents, which commonly occur in engineering scenarios, pose a significant threat to the safety of steel frames. The post-fire behavior of SSB has a significant influence on the structural integrity of steel frames, and neglecting the effect of temperature can lead to serious accidents in engineering. Therefore, it is important to evaluate the performance of SSB at elevated temperatures and their residual strength after a fire incident. To investigate the mechanical behavior of SSB after fire, 114 bolts with grades A4-70 and A4-80, manufactured from 316L austenitic stainless steel, were subjected to elevated temperatures ranging from 20℃ to 1200℃. Two different cooling methods commonly employed in engineering, namely cooling at ambient temperatures (air cooling) and cooling in water (water cooling), were used to cool the bolts. Tensile tests were performed to examine the influence of elevated temperatures and cooling methods on the mechanical behavior of SSB. The results indicate that the temperature does not significantly affect the Young's modulus and the ultimate strength of SSB. Up to 500℃, the yield strength increases with temperature, but this trend reverses when the temperature exceeds 500℃. In contrast, the ultimate strain shows the opposite trend. The strain hardening exponent is not significantly influenced by the temperature until it reaches 500℃. The cooling methods employed have an insignificant impact on the performance of SSB. When compared to high-strength bolts, 316L austenitic SSB demonstrate superior fire resistance. Design models for the post-fire mechanical behavior of 316L austenitic SSB, encompassing parameters such as the elasticity modulus, yield strength, ultimate strength, ultimate strain, and strain hardening exponent, are proposed, and a more precise stress-strain model is recommended to predict the mechanical behavior of 316L austenitic SSB after a fire incident.