• Current Photovoltaic Research
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• v.11 no.3
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• pp.67-74
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• 2023

The earth-abundant element-based Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film solar cells (TFSCs) have attracted greater attention in the photovoltaic (PV) community due to their rapid development in device power conversion efficiency (PCE) >13%. In the present work, we demonstrated the fine-tuning of the bandgap in the CZTSSe TFSCs by altering the sulfur (S) to the selenium (Se) chalcogenide ratio. To achieve this, the CZTSSe absorber layers are fabricated with different S/(S+Se) ratios from 0.02 to 0.08 of their weight percentage. Further compositional, morphological, and optoelectronic properties are studied using various characterization techniques. It is observed that the change in the S/(S+Se) ratios has minimal impact on the overall Cu/(Zn+Sn) composition ratio. In contrast, the S and Se content within the CZTSSe absorber layer gets altered with a change in the S/(S+Se) ratio. It also influences the overall absorber quality and gets worse at higher S/(S+Se). Furthermore, the device performance evaluated for similar CZTSSe TFSCs showed a linear increase and decrease in the open circuit voltage (V_oc) and short circuit current density (J_sc) of the device with an increasing S/(S+Se) ratio. The external quantum efficiency (EQE) measured also exhibited a linear blue shift in absorption edge, increasing the bandgap from 1.056 eV to 1.228 eV, respectively.

• Safety and Health at Work
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• v.14 no.3
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• pp.279-286
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• 2023

Background: This study aimed to evaluate the association between exposure to occupational hazards and the metabolic syndrome. A secondary objective was to analyze the additive and multiplicative effects of exposure to risk factors. Methods: This retrospective cohort was based on 31,615 health examinees at the Pusan National University Yangsan Hospital in Republic of Korea from 2012-2021. Demographic and behavior-related risk factors were treated as confounding factors, whereas three physical factors, 19 organic solvents and aerosols, and 13 metals and dust were considered occupational risk factors. Time-dependent Cox regression analysis was used to calculate hazard ratios. Results: The risk of metabolic syndrome was significantly higher in night shift workers (hazard ratio = 1.45: 95% confidence interval = 1.36-1.54) and workers who were exposed to noise (1.15:1.07-1.24). Exposure to some other risk factors was also significantly associated with a higher risk of metabolic syndrome. They were dimethylformamide, acetonitrile, trichloroethylene, xylene, styrene, toluene, dichloromethane, copper, antimony, lead, copper, iron, welding fume, and manganese. Among the 28 significant pairs, 19 exhibited both positive additive and multiplicative effects. Conclusions: Exposure to single or combined occupational risk factors may increase the risk of developing metabolic syndrome. Working conditions should be monitored and improved to reduce exposure to occupational hazards and prevent the development of the metabolic syndrome.

• Korean Journal of Materials Research
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• v.33 no.11
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• pp.491-496
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• 2023

As the demand for p-type semiconductors increases, much effort is being put into developing new p-type materials. This demand has led to the development of novel new p-type semiconductors that go beyond existing p-type semiconductors. Copper iodide (CuI) has recently received much attention due to its wide band gap, excellent optical and electrical properties, and low temperature synthesis. However, there are limits to its use as a semiconductor material for thin film transistor devices due to the uncontrolled generation of copper vacancies and excessive hole doping. In this work, p-type CuI semiconductors were fabricated using the chemical vapor deposition (CVD) process for thin-film transistor (TFT) applications. The vacuum process has advantages over conventional solution processes, including conformal coating, large area uniformity, easy thickness control and so on. CuI thin films were fabricated at various deposition temperatures from 150 to 250 ℃ The surface roughness root mean square (RMS) value, which is related to carrier transport, decreases with increasing deposition temperature. Hall effect measurements showed that all fabricated CuI films had p-type behavior and that the Hall mobility decreased with increasing deposition temperature. The CuI TFTs showed no clear on/off because of the high concentration of carriers. By adopting a Zn capping layer, carrier concentrations decreased, leading to clear on and off behavior. Finally, stability tests of the PBS and NBS showed a threshold voltage shift within ±1 V.

• Korean Journal of Occupational Health Nursing
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• v.32 no.4
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• pp.131-140
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• 2023

Purpose: We reviewed the cases of occupational diseases that occurred in healthcare workers from 2010 to 2019 and the cases of epidemiological investigations conducted by the Occupational Safety and Health Research Institute for them. Methods: In this study, gender, age, working period, occupational characteristics, and disease characteristics by occupation, which are general characteristics of healthcare workers approved for occupational diseases. In addition, 32 cases of epidemiological investigation of healthcare workers conducted by the Institute for Occupational Safety and Health for the past 10 years (2010~2019) were analyzed. Results: The gender, age, working period, occupational characteristics, and disease characteristics by occupation of medical workers recognized as occupational diseases were all statistically significant (p<.001). In the epidemiological investigation, ionizing radiation( 50.0%) and stress (33.3%) were recognized as disease-related factors, and even in cases of disapproval, ionizing radiation (60.0%) and shift work (25.5%) were designated as related factors. And it was statistically significant (p=.008). Conclusion: The current study identified the types of diseases, various causes, and general characteristics and occupational characteristics that occur frequently in healthcare workers. Therefore, if this study is used as basic information to set the priority and direction of disease prevention project for healthcare workers, it is judged that it will be helpful in preventing industrial accidents.

• Korean Journal of Community Nutrition
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• v.28 no.5
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• pp.376-391
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• 2023

Objectives: Our previously published study showed that a workplace nutrition intervention program with personalized goal setting and smartphone-based nutrition counseling improved dietary habits and physical activity in city bus drivers who were overweight/obese. This study explored the facilitators and barriers that participants faced in achieving their dietary and physical activity goals six months after the intervention. Methods: The study included bus drivers and dietitians who participated in the intervention program. Three focus group interviews were conducted with 10 bus drivers (divided by two groups based on their achievement of set goals) and five dietitians who had provided nutrition counseling. Results: Willpower was the most important intrapersonal facilitator for drivers to achieve their goals. Other factors that promoted behavioral changes were nutrition counseling by dietitians, trackable physical activity using smartwatches, and setting of practical and achievable goals. Meanwhile, the most important barriers identified were occupational factors such as long driving hours, short breaks, and shift work. Other barriers were environmental factors such as availability of snackable food, accessibility to convenience stores, and cold weather. Family and colleagues were perceived as both facilitators and barriers. In addition, dietitians identified a lack of knowledge about healthy diet as one of the barriers. Conclusions: Our results suggested that the workplace environment should be improved and that nutrition intervention programs at the workplace could encourage bus drivers to practice healthy eating habits. The facilitators and barriers identified in this study should be considered when planning a nutrition intervention program for bus drivers.

• Journal of Daesoon Thought and the Religions of East Asia
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• v.3 no.2
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• pp.93-119
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• 2024

The introductionof Won Buddhism to the United States has reached its fifty-year mark. Brought to the West by Korean kyomus (Won Buddhist clergy), these initial Won Buddhist clergy set a foundation for future ordained devotees to reside in America and further the religion's mission. Innovation has always played an important role in the formation and growth of Won Buddhism. The founder, Sotaesan, declared the necessity to reform traditional Buddhism to make it accessible to the laity and espoused values such as inclusiveness, equality, public work, and practicality. Over the past few decades, these innovations have helped Won Buddhism in America to shift from a strictly ethnic-related context to an emphasis on its universal nature. However, as the religion continues achieving a foothold in Western soil, critical questions arise such as how can Won Buddhism honor its Korean origins while becoming increasingly international? What are the detriments to decontextualizing and de-emphasizing elements thought to be "too Korean" or "too traditional," or thought to be irrelevant in the West? When Buddhism spreads to a new country, it not only influences the culture it enters but is also shaped by the adopting culture. In American history, this has often meant the erasure of Asian cultures that were home to Buddhism for millennia and from which the dharma is inextricable. I argue in this article that if Won Buddhism is to thrive in the United States conscious consideration will have to be given to the indispensable aspects of its Korean roots and tradition while connecting with the current circumstance in fresh, relevant, and effective ways that include the multi-cultural and ethnic makeup of the US. This entails understanding American history and Asian Buddhism's history in America, as well as cultivating a competency or fluency in the cultures that allowed Won Buddhism to survive for decades.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.140-145
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• 2024

High temperature co-electrolysis of H₂O-CO₂ mixtures using solid oxide cells has attracted attention as promising CO₂ utilization technology for production of syngas (H₂/CO), feedstock for E-fuel synthesis. For direct supply to E-fuel production such as hydrocarbon and methanol, the outlet gas ratio (H₂/CO/CO₂) of co-electrolysis should be controlled. In this work, current voltage characteristic test and product gas analysis were carried out under various reaction conditions which could attain proper syngas ratio.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.308-317
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• 2009

In the present work, a sensor system composed of an oscillator sensor and a Lamb wave sensor is proposed for the purpose of structural health monitoring. The oscillator sensing system detecting the shift of a structural resonant frequency in proportion to the amount of defects in the structure is a pretty sensitive and simple device, but its detectable range is limited to its local zone. The Lamb wave sensor system, however, is applicable to global detection of the defects. This study is aimed at investigating the feasible combination of the two systems to exploits their merits simultaneously. The scheme to use PZT patches as the oscillator sensor as well as the Lamb wave sensor was proposed to identify the position, length and number of cracks by means of TOF and amplitude of signals, and its validity was confirmed through experiments.

• Asia-Pacific Journal of Business
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• v.14 no.4
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• pp.289-303
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• 2023

Purpose - The purpose of this study is to investigate the types and forms of various marketing activities actually used in pharmaceutical companies and to empirically analyze the impact of these marketing activities on sales. Design/methodology/approach - This study categorize five years' worth of marketing activity data from a foreign pharmaceutical company 'A' which operates in South Korea into five categories. Multiple regression analysis and interaction effects are employed for data analysis. Findings - First, CRM calls, Detail calls, GP, and Web events have a positive impact on sales, but SoV does not show significant differences. Second, in the comparison between HQ1 and HQ2 based on patent ownership, Detail calls and Web events had a stronger impact on sales in HQ2, where the patent period is still in effect, compared to HQ1. However, SoV showed no difference between HQ1 and HQ2. Research implications or Originality - First, Detail Calls are more effective for drugs with active patents, while CRM Calls work better for drugs with expired patents. This emphasizes the need to customize call strategies based on patent status. Second, the significant impact of Web Events on sales in HQ2 compared to HQ1 suggests that online information access is crucial, indicating that customer receptivity varies based on product nature. Third, these insights, derived from data analysis, call for a shift in pharmaceutical marketing analysis methods away from traditional approaches. Finally, this study holds significance as one of the first empirical analyses using actual marketing data from pharmaceutical companies in South Korea.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.44.1-44.11
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• 2023

Background: A series of breast cancer cases were recently reported in a tertiary university hospital in South Korea. Nurses are generally exposed to risk factors for breast cancer such as night shift work, antineoplastic agents, and job strain. However, the epidemiological evidence of excess incidence among nurses remains lacking. This study aims to investigate the excess incidence of breast cancer among nurses in a tertiary university hospital and provide epidemiological evidence of occupational risk factors. Methods: A retrospective cohort was developed using personnel records of female workers in the nursing department who worked from January 2011 to June 2021 in a tertiary university hospital in South Korea. Sick leave records were used to identify cases of breast cancer. The standardized incidence ratio of breast cancer among nurses was compared to the general population. Results: A total of 5,509 nurses were followed up for 30,404 person-years, and 26 breast cancer cases were identified. This study revealed a significantly increased breast cancer incidence among all included nurses, with a standardized incidence ratio of 1.65 (95% confidence interval [CI]: 1.08-2.41), compared to the general population. Workers, who handle antineoplastic agents in their representative department and current and/or former department, had significantly elevated breast cancer standardized incidence ratios of 2.73 (95% CI: 1.008-5.94) and 3.39 (95% CI: 1.46-6.68), respectively. Conclusions: This study provides significant evidence of increased breast cancer risk among nursing staff in a hospital setting, particularly those who handle antineoplastic drugs. Measures that reduce exposure to risk factors should be implemented, especially anticancer drugs, to protect healthcare professionals. Further research at a national level that focuses on healthcare workers is necessary to validate breast cancer incidence and its contributing factors.