• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.4
• /
• pp.259-267
• /
• 2022

The existing method of deriving the fail-safe design requirements for the domestic developed rotary-wing aircraft system may miss the factors that cause critical system function failures, when being applied to the latest integrated avionics system. It is because the existing method analyzes the severity effect of the failures caused by a single item. To solve the issue, we present a systematic analysis procedure for deriving fail-safe design requirements of system architecture by utilizing functional hazard assessment and development assurance level analysis of SAE ARP4754A, international standard for complex system development. To demonstrate that our proposed procedure can be a solution for the aforementioned issue, we set up experimental environments that include common factors that can cause critical function failures of a system, and we conducted a cross-validation with the existing method. As a result, we showed that the proposed procedure can identify the potential critical common factors that the existing method have missed, and that the proposed procedure can derive fail-safe design requirements to control the common factors.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.8 no.10
• /
• pp.871-882
• /
• 2018

This study investigated meaning of life as mediator of the relationships of meaning of work and happiness in Koran middle aged. A sample of 171 middle aged were participated. in survey about meaning of work, meaning of work and happiness. The data were analyzed using correlation test and path analysis. The results was followed. First, every factors was positively correlated. The meaning of work was positively correlated with meaning in life and happiness. And meaning in life was also positively correlated with happiness. Second, the meaning in life had partial mediation effect between meaning of work and happiness. The middle aged's higher score of meaning of work not only directly increased happiness, but also induced higher level of meaning in life, which, in turn, increased happiness. The results of this study suggested that meaning of work is a predictor meaning in life and happness, and meaning in life can be important factor of the relationship between meaning of work and happiness.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.33 no.2
• /
• pp.115-125
• /
• 2023

Objectives: This study was conducted to measure the level of radon in the air at a highway tunnel construction site in a gneiss area using the New Austrian Tunneling Method (NATM) and to evaluate exposure levels by occupation. Methods: Radon concentrations in the air were measured using E-PERM at points 300 m, 600 m, and 900 m from the tunnel entrance during the excavation and waterproofing work inside the tunnel. In addition, radon concentrations were measured during external excavation to compare with the inside of the tunnel. Personal exposure levels for major occupations including tunnel workers, construction equipment operators, waterproofers, shotcrete workers, and safety and health managers who participated in the construction were estimated using radon concentration measured in the work process area and working hours by occupation. Results: As a result of a total of 77 radon measurements, the geometric mean (GM) concentration was 71.1 Bq/m³, and the maximum concentration was 127.3 Bq/m³, which was below the indoor air quality criteria. Radon concentration by process decreased in the order of the tunnel excavation process (GM= Bq/m³, GSD=1.2), waterproofing process (GM=73.35 Bq/m³, GSD=1.2), and outside excavating process (GM=45.28 Bq/m³, GSD=1.2). Processes inside the tunnel were significantly higher than outside excavating processes (p<0.05). There was no statistically significant difference in radon concentration measured inside by distance from the tunnel entrance, but the innermost point of the tunnel, 900 m (GM=79.24 Bq/m³, GSD=1.27), measured the highest. Conclusions: The occupation with the highest individual exposure to radon was tunnel worker (64.16 Bq/m³), followed by construction equipment driver (64.04 Bq/m³) and waterproofer (63.13 Bq/m³).

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.4
• /
• pp.485-492
• /
• 2023

Among the methods to improve traffic congestion by providing real-time traffic information and solving problems like traffic congestion and traffic crashes, private enterprise is implementing policies to lower insurance premiums like compensation for drivers' driving safety scores. Despite the emergence of various incentive policies, a study on the level of incentive payment for safe/eco-friendly driving is insufficient. The research analyzed the satisfactory factors that affect the scale of incentives through questionnaires and the applicable scale of incentives that enable safe/eco-friendly driving using a binary logistic regression model. As a result of analyzing the incentive scale of the appropriate payment amount for each driving score increase, 0.4% of the toll fee was derived when the driving score increased by 20 points, and 0.5% of the toll fee was derived when the driving score increased by 30 points. This study on calculating the appropriate incentive payment scale for driver information sharing and driving score increase will help optimize incentives and prepare system implementation plans.

• Korean Journal of Environmental Agriculture
• /
• v.41 no.4
• /
• pp.310-317
• /
• 2022

BACKGROUND: The salt in soil interrupts crop growth. Therefore, water resources are used to remove any salt found in the soil. However, water resources have been reduced by global warming; thus, a new study is required into reducing the salt in soil. Recently, the bottom ash (BA) of a biomass power plant was found to be similar to biochar. Hence, it can be used to remove heavy metals and wastewater through the adsorption characteristics of BA. The objective of this study was to evaluate the improvement effects on crop growth in saline soil containing the BA from biomass power plants. METHODS AND RESULTS: The effect on crop growth in the saline soil supplemented with BA was studied with the crop-planted pots, which were packed by reclaimed greenhouse soils collected from Byolyang, Suncheon. The BA application level was 25, 50, 100, 200, and 400 kg/10a (referred as BA25, BA50, BA100, BA200, and BA400, respectively). The BA increased the fresh weights of the leaf and root, while nitrogen uptake increased by approximately 24-102% and 54-77%, respectively for the lead and root. The phosphorous uptake increased by 38%, although only in the leaf of the lettuce. In the case of soil, BA increased water content, pH, EC, CEC, and NH₄⁺ and the SAR of the soil decreased by 5-15%. The bottom ash increased the contents of Ca²⁺ and Mg²⁺, and fixed the amount of Na⁺. CONCLUSION(S): It was confirmed the bottom ash of a biomass power plant, based on wood pellets, improved crop growth, and increased the nutrient uptake of crops in saline soil. In addition, bottom ash, which has a wide range of porosity and high values of pH and EC, improved properties of the saline soil. However, the BA has a large amount of B, As, and heavy metals. Finally, it may require a study on the safety and contamination of heavy metals contained in the bottom ash, which would be applied in soil for a long time.

• Journal of Radiation Protection and Research
• /
• v.47 no.4
• /
• pp.237-245
• /
• 2022

Background: The current study reports measurements of activity concentrations of radon (²²⁰Rn) and thoron (²²⁰Rn) in dwellings, followed by inhalation dose assessment of the public, and then by the development of regulation and the national radon action plan (NRAP) in Cameroon. Materials and Methods: Radon, thoron, and thoron progeny measurements were carried out from 2014 to 2017 using radon-thoron discriminative detectors (commercially RADUET) in 450 dwellings and thoron progeny monitors in 350 dwellings. From 2019 to 2020, radon track detectors (commercially RADTRAK) were deployed in 1,400 dwellings. It was found that activity concentrations of radon range in 1,850 houses from 10 to 2,620 Bq/㎥ with a geometric mean of 76 Bq/㎥. Results and Discussion: Activity concentrations of thoron range from 20 to 700 Bq/㎥ with a geometric mean of 107 Bq/㎥. Thoron equilibrium factor ranges from 0.01 to 0.6, with an arithmetic mean of 0.09 that is higher than the default value of 0.02 given by UNSCEAR. On average, 49%, 9%, and 2% of all surveyed houses have radon concentrations above 100, 200, and 300 Bq/㎥, respectively. The average contribution of thoron to the inhalation dose due to radon and thoron exposure is about 40%. Thus, thoron cannot be neglected in dose assessment to avoid biased results in radio-epidemiological studies. Only radon was considered in the drafted regulation and in the NRAP adopted in October 2020. Reference levels of 300 Bq/㎥ and 1,000 Bq/㎥ were recommended for dwellings and workplaces. Conclusion: Priority actions for the coming years include the following: radon risk mapping, promotion of a protection policy against radon in buildings, integration of the radon prevention and mitigation into the training of construction specialists, mitigation of dwellings and workplaces with high radon levels, increased public awareness of the health risks associated with radon, and development of programs on the scientific and technical aspects.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.3
• /
• pp.75-79
• /
• 2023

ESG management means to thoroughly consider the investor's perspective when evaluating corporate value, and environmental, social, and governance issues are continuous and strategic monitoring issues in identifying risk and opportunity factors related to corporate management activities. In other words, the perspective of value creation is reflected in business relationships. The fundamental purpose of ESG management is continuous business value creation and thorough management of investment risks and business transactions in contractual relationships. It is also a requirement of linked investors. The field that Korean companies are currently experiencing the most is the recognition that 'ESG information collection is necessary and maintenance must be prioritized' in investor IR and global sales and marketing departments, and the primary need for this is emerging. In addition, as the legal affairs office, environmental safety department, and human resources department, which conduct compliance management, carry out related tasks, clarity at the organizational level must precede in order to properly establish an information integration and management system. It covers the scope of securing new market opportunities such as management, disclosure and communication. Therefore, in regard to the newly emerging ESG management and response methods, it is necessary to review and implement it repeatedly so that sustainable exchange profits can be created by simultaneously managing non-financial risks as well as efforts to enhance corporate value for financial returns.

• 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 the Korean GEO-environmental Society
• /
• v.24 no.8
• /
• pp.5-11
• /
• 2023

Due to frequent occurrences of concentrated heavy rainfall caused by abnormal climate conditions in recent years, collapses of steep slopes have been occurring frequently due to surface erosion and increased pore water pressure. Various methods are being applied to prevent slope collapses, such as increasing the resistance to movement and reducing pore water pressure. Research on these methods has been consistently conducted as they provide an efficient response to slope collapses by satisfying both the conditions of resistance to movement and pore water pressure simultaneously. Therefore, in this study, we propose an upward slope reinforcement method by burying drainage materials with an upward slope inclination, instead of the conventional horizontal application. This approach aims to satisfy both slope reinforcement and drainage functions effectively, offering a comprehensive solution for slope stabilization. Furthermore, to determine the optimal burial angle that exhibits the most effective reinforcement and drainage effects of the proposed method, we investigated the reinforcement and drainage effects under conditions where the horizontal drainage materials were set at angles ranging from 0° to 60° in increments of 10° on a representative cross-section. Additionally, indoor model experiments were conducted under the conditions of 40°, which showed the most outstanding drainage effect, and 20°, which exhibited the highest safety factor, to validate the numerical analysis results. The results showed that the burial angle of 40° exhibits a relatively higher drainage effect as with the numerical analysis results, while the angle of 20° results in inadequate drainage and observed slope collapse.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.5B
• /
• pp.501-509
• /
• 2006

The safety of levee that depends on the river flood elevation has been regarded as very important keys to build up various flood prevention systems. However, deterministic methods for computation of water surface profile cannot reflect the effect of possible inaccuracies in the input parameters. The purpose of this study is to develop a methodology of uncertainty computation of design flood level based on steady flow analysis and Monte Carlo simulation. This study addresses the uncertainty of water surface elevation by Manning's coefficients, design discharges, river cross sections and boundary condition. Monte Carlo simulation with the variations of these parameters is performed to quantify the variations of water surface elevations in a river. The proposed model has been applied to the Kumho-river. The reliability analysis was performed within 38.5 km (95 sections) reach considered the variations of the above-mentioned parameters. Overtopping risks were evaluated by comparing the elevations of the flood condition with the those of the levees. The results show that there is a necessity which will raise the levee elevation between 1 cm and 56 cm at 7 sections. The model can be used for preparing flood risk maps, flood forecasting systems and establishing flood disaster mitigation plans as well as complement of conventional levee design.