• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.1-8
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• 1994

Laboratory experiments were conducted to investigate the effect of digestion temperature on the settleability and dewaterability of anaerobically digested sludge. The digesters were operated at a hydraulic retention time of 20 days with a loading rate of 0.63~0.66kg volatile solids per cubic meter per day at the temperature of $35^{\circ}C$ and $55^{\circ}C$. A mixed primary and secondary municipal sludge was used as a feed. The interface height of the sludge during settling test was recorded to identify settleability. As a measure of dewaterability of the sludge, specific resistance and capillary suction time were also measured with and without chemical conditioning. Higher digestion efficiency was obtained at $55^{\circ}C$ than $35^{\circ}C$. However, the settleability and dewaterability of the sludge at $35^{\circ}C$ were quite higher than those of the sludge digested at $55^{\circ}C$. The optimum dosages of ferric chloride for sludge conditioning were 0.4% and 0.6% at $35^{\circ}C$ and $55^{\circ}C$, respectively. The filtrate COD of the sludge digested at $55^{\circ}C$ was higher than at $35^{\circ}C$, which means that poor dewaterability of the sludge result in high filtrate COD.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.3
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• pp.284-291
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• 2007

The Ni-MH batteries for HEV and industry are normally placed in outdoor, consequently causing an too weak discharge power problem due to a cold weather specially in winter time. In order to improve the low temperature performances of the Ni-MH battery for HEV and industrial uses, it has been investigated the low temperature discharge characteristics of Ni-MH battery with various electrolytes at $-18^{\circ}C$. The summary of experimental results are as follows. The low temperature characteristics depended strongly on the characteristics of electrolytes. When the concentration of the electrolytes were too high or too low the low temperature performance was poor. The best electrolyte was composed of KOH 6.2M+LiOH 1.2M. An addition of RbOH or CsOH to electrolyte improved the low temperature performance. The best total concentration of electrolyte composed of KOH, NaOH and LiOH was about 7M.

• Journal of Preventive Medicine and Public Health
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• v.55 no.6
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• pp.595-603
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• 2022

Objectives: Poor menstrual health may lead to school absenteeism and adverse health outcomes for adolescents. The purpose of this study was to determine the effect of pubertal and menstrual health education on health and preventive behaviors among Iranian secondary school girls. Methods: A quasi-experimental study was conducted to evaluate the effectiveness of a health intervention program. A total of 578 students (including intervention and control participants) in 12 schools in Tehran Province, Iran were included by multistage random sampling. The program comprised seven 2-hour educational sessions. After confirming the reliability and validity of a researcher-made questionnaire, that questionnaire was used to collect the required data, and the groups were followed up with after 6 months. Results: After the educational intervention, the mean scores of menstrual health-related knowledge and constructs of the theory of planned behavior were significantly higher in the intervention group than in the control group (p<0.001 for all dimensions). Conclusions: The results of this study emphasize the effectiveness of menstrual health interventions in schools. These findings should also encourage health policy-makers to take committed action to improve performance in schools.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.140-145
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• 2015

This study was aimed at analyzing NOx conversion characteristics in the HC-SCR with biodiesel content changes of the secondary fuel injection (BD0, BD10, BD25). Test conditions for temperature were set to $290^{\circ}C$, $320^{\circ}C$ and $350^{\circ}C$ considering the upstream temperature of a HC-SCR, distillation of the secondary injected fuels and etc. The amount of fuel injection was adjusted with a fixed space velocity of 55,000(1/h). According to the test results of distillation, the T90 was the same level about $350^{\circ}C$ on all test fuels and the amount of evaporation was reduced at lower than $350^{\circ}C$ temperature condition with increasing biodiesel content. As biodiesel content which is mixed with the secondary injected fuel is increased, NOx reduction efficiency was determined to decrease. The difference of the Nox reduction ratio in a high temperature condition($320^{\circ}C$ and $350^{\circ}C$) than the low temperature($290^{\circ}C$) was more significant. These results are thought to be poor evaporation properties (distillation) and high molecular weight of the biodiesel.

• Journal of Integrative Natural Science
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• v.10 no.4
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• pp.175-191
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• 2017

In organic chemistry amide synthesis is performed through condensation of a carboxylic acid and an amine with releasing one equivalent of water via the corresponding ammonium carboxylate salt. This method is suffering from tedious processes and poor atom-economy due to the adverse thermodynamics of the equilibrium and the high activation barrier for direct coupling of a carboxylic acid and an amine. Most of the chemical approaches to amides formations have been therefore being developed, they are mainly focused on secondary amides. Direct carbonylations of tertiary amines to amides have been an exotic field unresolved, in particular direct carbonylation of trimethylamine in lack of commercial need has been attracted much interests due to the versatile product of N,N-dimethylacetamide in chemical industries and the activation of robust N-C($sp^3$) bond in tertiary amine academically. This review is focused mainly on carbonylation of trimethylamine as one of the typical tertiary amines by transition metals of cobalt, rhodium, platinum, and palladium including the role of methyl iodide as a promoter, the intermediate formation of acyl iodide, the coordination ability of trimethylamine to transition metal catalysts, and any possibility of CO insertion into the bond of Me-N in trimethylamine. In addition reactions of acyl halides as an activated form of acetic acid with amines are reviewed in brief since acyl iodide is suggested as a critical intermediate in those carbonylations of trimethylamine.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.237-243
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• 2019

A high-efficiency and small-sized switched-mode line transformer (SMLT) is proposed in this study. The conventional structure of an adapter is composed of line transformer and rectifiers. This structure has a limit in miniaturizing due to low-frequency line transformer. Another structure is composed of power factor correction (PFC) and DC/DC converter. This structure has a limit in reducing volume due to two-stage structure. As the proposed SMLT is composed of an LLC resonant converter, a high-frequency transformer can be adopted to achieve isolation standards and size reduction. This proposed structure has different operation modes in accordance with line input voltage to overcome poor line regulation. In addition, the proposed SMLT is applied to the front of a conventional PFC converter, because the SMLT output voltage is restored to rectified sinusoidal wave by using a full-bridge rectifier in the secondary side. The design of the PFC converter is easy, because the SMLT output voltage is controlled as rectified sinusoidal wave. The validity of the proposed converter is proven through a 350 W prototype.

• Research in Community and Public Health Nursing
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• v.33 no.4
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• pp.418-431
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• 2022

Purpose: The aims of this study were to examine the rate of depression among older adults living alone and to identify factors associated with depression in older adults living alone during the COVID-19 pandemic. Methods: A secondary data analysis was performed using data from the 2020 Korea Community Health Survey. The study participants were 18,824 older adults aged 65 years and over living alone. The data of the complex sample design was analyzed with consideration for weights, stratification, and clustering. Complex sample multiple logistic regression was conducted to identify factors associated with depression in older adults living alone during the COVID-19 pandemic. Results: The results showed that the rate of depression in older adults living alone was 6.3%. Older adults living alone with decreased physical activity, decreased hours of sleep, and an increased or similar frequency of meeting with friends or neighbors were found to be more likely to have depression. In terms of factors related to the practice of COVID-19 infection prevention and control rules, not disinfecting regularly and not wearing a mask indoors were related to depression. For health-related factors, fair or poor self-rated health status, not having breakfast every day, and feeling stressed were related to depression. Conclusion: It is recommended to develop tailored interventions to prevent depression among older adults living alone by considering the factors related to their depression during the COVID-19 pandemic.

• Journal of Environmental Science International
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• v.29 no.5
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• pp.495-506
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• 2020

This study investigated the nitrate formation process, and mass closure of Particulate Matter (PM) were calculated over the urbanized area of Jeju Island. The data for eight water-soluble inorganic ions and nineteen elements in PM_2.5 and PM₁₀ were used. The results show that the nitrate concentration increased as excess ammonium increased in ammonium-rich samples. Furthermore, nitrate formation was not as important in ammonium-poor samples as it was in previous studies. According to the sum of the measured species, approximately 45~53% of gravimetric mass of PM remained unidentified. To calculate the mass closure for both PM_2.5 and PM₁₀, PM chemical components were categorized into secondary inorganic aerosol, crustal matter, sea salt, trace matter and unidentified matter. The results by the mass reconstruction of PM components show that the portion of unidentified matter was decreased from 52.7% to 44.0% in PM_2.5 and from 45.1% to 29.1% in PM₁₀, despite the exclusion of organic matter and elemental carbon.

• Clinical and Experimental Pediatrics
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• v.62 no.6
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• pp.199-205
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• 2019

Although Mycoplasma pneumoniae pneumonia (MPP) has been generally susceptible to macrolides, the emergence of macrolide-resistant MPP (MRMP) has made its treatment challenging. MRMP rapidly spread after the 2000s, especially in East Asia. MRMP is more common in children and adolescents than in adults, which is likely related to the frequent use of macrolides for treating M. pneumoniae infections in children. MRMP is unlikely to be related to clinical, laboratory, or radiological severity, although it likely prolongs the persistence of symptoms and the length of hospital stay. Thereby, it causes an increased burden of the disease and poor quality of life for the patient as well as a societal socioeconomic burden. To date, the only alternative treatments for MRMP are secondary antimicrobials such as tetracyclines (TCs) or fluoroquinolones (FQs) or systemic corticosteroids; however, the former are contraindicated in children because of concerns about potential adverse events (i.e., tooth discoloration or tendinopathy). A few guidelines recommended TCs or FQs as the second-line drug of choice for treating MRMP. However, there have been no evidence-based guidelines. Furthermore, safety issues have not yet been resolved. Therefore, this article aimed to review the benefits and risks of therapeutic alternatives for treating MRMP in children and review the recommendations of international or regional guidelines and specific considerations for their practical application.

• Research in Community and Public Health Nursing
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• v.28 no.4
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• pp.472-481
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• 2017

Purpose: The purpose of this study were to compare working condition, socioeconomic status, and health status between elderly and non-elderly workers and to examine the influencing factors of health status according to age groups. Methods: This study is a secondary analysis of data extracted from the 2014 Korean Working Conditions Survey. For the present analysis, 15,980 elderly workers over the age of 55 and 32,037 non-elderly workers under the age of 55 were selected. Results: The prevalence of subjective unhealthy status and poor mental health were significantly higher among the elderly workers than the non-elderly workers. The elderly workers were more likely to have lower level of education and income than the non-elderly workers. They also reported less support from colleagues and managers, however, have more decision authority. Among the elderly workers, long working hours, awkward posture, physical environmental risks, quantitative demand, decision authority, social support, age discrimination, education level, and income level were significant predictors of subjective health status or mental health. Conclusion: For keeping elderly workers healthy and productive, work environment needs to become more age-friendly. An age-friendly workplace may include: accommodative support, workers' participation, minimization of environment risk, etc.