• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.18-25
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• 2024

Objectives: The primary aim of this study is to create an Occupational Safety and Health (OSH) guide for high-risk maintenance tasks, specifically one designed for maintenance work (MW) in the electronics industry. Methods: The methodology involved a literature review, field investigations, and discussions. An initial draft of the OSH guide was created and then refined through consultations with experts possessing extensive experience in MW for electronic processes. Results: Specific MW tasks within electronics processing facilities identified as high-risk by the research were selected. A comprehensive OSH guide for these tasks was developed consisting of approximately 11 to 12 components and encompassing about 20-25 pages. Implementing safety and health measures before, during, and after MW is crucial for the protection of maintenance personnel. The guide is enriched with real-case scenarios of industrial accidents and occupational diseases to enhance maintenance workers' comprehension of the OSH principles. For a clearer understanding of and adherence to the safety protocols, the guide incorporates visual aids, including cartoons and photographs. Conclusions: This OSH guide is designed to ensure the protection of workers involved in maintenance activities in the electronics industry. It aligns with global standards set by the International Organization for Standardization (ISO) and Semiconductor Equipment and Material International (SEMI) to ensure a high level of safety and compliance.

• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.214-224
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• 2024

Valves play an essential role in a chemical plant such as regulating fluid flow and pressure. Therefore, optimal selection of the valve size and type is essential task. Valve size and type have been selected based on theoretical formulas about calculating valve sizing coefficient (Cv). However, this approach has limitations such as requiring expert knowledge and consuming substantial time and costs. Herein, this study developed a model for predicting valve sizes and types using machine learning. We developed models using four algorithms: ANN, Random Forest, XGBoost, and Catboost and model performances were evaluated using NRMSE & R² score for size prediction and F1 score for type prediction. Additionally, a case study was conducted to explore the impact of phases on valve selection, using four datasets: total fluids, liquids, gases, and steam. As a result of the study, for valve size prediction, total fluid, liquid, and gas dataset demonstrated the best performance with Catboost (Based on R², total: 0.99216, liquid: 0.98602, gas: 0.99300. Based on NRMSE, total: 0.04072, liquid: 0.04886, gas: 0.03619) and steam dataset showed the best performance with RandomForest (R²: 0.99028, NRMSE: 0.03493). For valve type prediction, Catboost outperformed all datasets with the highest F1 scores (total: 0.95766, liquids: 0.96264, gases: 0.95770, steam: 1.0000). In Engineering Procurement Construction industry, the proposed fluid-specific machine learning-based model is expected to guide the selection of suitable valves based on given process conditions and facilitate faster decision-making.

• Journal of Life Science
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• v.34 no.9
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• pp.656-665
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• 2024

Enzymes, as proteins that regulate various metabolic processes within the human body, play a crucial role in maintaining health. However, the overexpression of certain enzymes can disrupt metabolic balance, leading to various diseases. Enzyme inhibitors are vital in treating these diseases or conditions by inhibiting the action of these enzymes, making them indispensable in the development of effective therapies for a wide array of diseases. Quercetin, a natural product derived from plants, is a type of flavonoid that belongs to the polyphenol family. Quercetin, a natural flavonoid from the polyphenol family, has emerged as a potent enzyme inhibitor. This low-molecular-weight secondary metabolite is known for its inhibitory effects on enzymes such as α-glucosidase, acetylcholinesterase, bacterial neuraminidase, and xanthine oxidase due to its structural advantages. Quercetin is isolated from biomaterials and can be classified into glycosylated, methoxylated, and alkylated derivatives based on its structural variations. These natural quercetin derivatives possess unique substituents that enable specific binding patterns with catalytic residues in enzyme active sites. Therefore, quercetin derivatives can be expected to have better enzyme inhibitory activity than basic quercetin. Due to their specificity and enhanced activity, quercetin and its derivatives hold promise as candidates for developing potent enzyme inhibitors to treat diseases resulting from enzyme imbalances.

• Journal of Pharmacopuncture
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• v.27 no.3
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• pp.211-222
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• 2024

Objectives: Tilia viridis (Bayer) Simonk. (Malvaceae) is widely distributed in Argentina and employed for its tranquilizing properties. Other species of the genus (Tilia europaea L., Tilia cordata Mill., Tilia platyphyllos Scop.) have been traditionally used for the treatment of epilepsy. Epilepsy affects approximately 65 million people worldwide and is characterized by an imbalance between excitatory and inhibitory processes in the brain, leading to unpredictable, unprovoked, recurrent seizures. Current pharmacological interventions often present mild to moderately severe side effects. Epilepsy has been associated with oxidative and nitrative stress as well as neuroinflammation. Herbal medicine therapies may offer new treatment options with multi-target antioxidant and anticonvulsant effects for patients whose seizures remain uncontrolled, potentially providing cost-effective solutions for individuals worldwide suffering from uncontrolled epilepsy.The aim of this study was to demonstrate the anticonvulsant activity of a standardized T. viridis aqueous extract (TE). Methods: Study of the constituents of TE, TE's antioxidant and anticonvulsant activities and toxicity, and analysis of the possible relation between the potential activities and the compounds present in the extract. In order to demonstrate TE's anticonvulsant activity a zebrafish model was used. The study also assessed TE's toxicity and antioxidant activity. To standardize the extract, total polyphenols and flavonoids were quantified and specific flavonoids were identified and quantified using HPLC-MS/MS and HPLC-UV. Results: TE exhibited anticonvulsant activity at low concentrations and demonstrated antioxidant effects by scavenging free radicals, exhibiting superoxide dismutase and peroxidase-like activities, as well as inhibiting lipoperoxidation. These actions can be attributed to the presence of polyphenols, particularly flavonoids. Conclusion: TE holds promise as a complementary herbal medicine in the treatment of epilepsy and may also offer benefits for other neuropathies associated with oxidative stress, such as Parkinson's disease and Alzheimer's disease.

• Applied Chemistry for Engineering
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• v.35 no.5
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• pp.410-417
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• 2024

Steel mill gases, including coke oven gas (COG), blast furnace gas (BFG), and Linz-Donawitz gas (LDG), are mainly used as fuels within steel plants, resulting in substantial CO₂ emissions. This combustion process accounts for 10% of South Korea's total CO₂ emissions. These off-gases, rich in CO, CH₄, and hydrogen, have the potential to be converted into valuable chemicals through catalytic processes, thereby reducing CO₂ emissions and increasing their economic value. This study investigates the conversion of steel mill gases into methanol, an important platform chemical and cleaner transportation fuel. By using COG and LDG as sources of CO and H₂, respectively, a novel process was developed. In this process, H₂-rich COG from a simple single-step membrane separation and raw LDG are converted into methanol with high selectivity using a Cu-Zn-Al catalyst. The study identified the optimal gas compositions for methanol production through experimental results, demonstrating efficient methanol synthesis from various compositions of LDG, COG, pure hydrogen, and H₂-rich COG. This innovative approach not only aims to reduce specific CO₂ emissions from steel plants but also enhances the economic value of the byproduct gases. Thus, the study provides a sustainable and economically advantageous solution for the steel industry.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.75-88
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• 2005

Ameloblastoma is the most commonly occurring odontogenic tumor in oral cavity. Although most are benign epithelial neoplasm, they are generally considered to be locally aggressive and destructive, exhibiting a high rate of recurrence. The biological behavior of this neoplasm is a slowly growing, locally invasive tumor without metastasis, therefore malignant neoplasm, changed its histological appearance to carcinoma or showed distant metastasis, is only defined clinically. In this study, we identified the differentially expressed genes(DEGs) in stages under benign or malignant ameloblastoma compared with normal patient using ordered differential display(ODD) reverse transcription(RT)-PCR and $GeneFishing^{TM}$ technology. ODD RT-PCR is rather effective when the investigation of samples containing very small amounts of total RNA must be accomplished. ODD RT-PCR used the means of amplification with anchored T-primer and adaptor specific primer. bearing definite two bases at their 3' ends and so this method could display differential 3'-expressed sequence taqs(ESTs) patterns without using full-length cDNAs. Compared with standard differential display, ODD RT-PCR is more simple and have enough sensitivity to search for molecular markers by comparing gene expression profiles, However, this method required much effort and skill to perform. $GeneFishing^{TM}$ modified from DD-PCR is an improved method for detecting differentially expressed genes in two or more related samples. This two step RT-PCR method uses a constant reverse primer(anchor ACP-T) to prime the RT reaction and arbitrary primer pairs(annealing control primers, ACPs) during PCR. Because of high annealing specificity of ACPs than ODD RT-PCR, the application of $GeneFishing^{TM}$ to DEG discovery generates reproducible, authentic, and long(100bp to 2kb) PCR products that are detectable on agarose gels. Consequently, various DEGs observed differential expression levels on agarose gels were isolated from normal, benign, and malignant tissues using these methods. The expression patterns of the some isolated DEGs through ODD RT-PCR and $GeneFishing^{TM}$ were confirmed by Northern blot analysis and RT-PCR. The results showed that these identified DEGs were implicated in ameloblastoma neoplasm processes. Therefore, the identified DEGs will be further studied in order to be applied in candidate selection for marker as an early diagnosis during ameloblastoma neoplasm processes.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.137-148
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• 2010

The Myoungbong mine located in Boseong-gun, Jellanamdo consists of Au-Ag bearing quartz veins which filled the fissures of Bulguksa granitic rocks of Cretaceous. The tailings obtained from the Myungbong mine were used to investigate the effects of various processes, such as oxidation of primary sulfides and formation(alteration) of secondary and/or tertiary minerals, on arsenic immobilization in tailings. This study was conducted via both mineralogical and chemical methods. Mineralogical methods used included gravity and magnetic separation, ultrasonic cleaning, and instrumental analyses(X-ray diffractometry, energy-dispersive spectroscopy, and electron probe microanalyzer) and aqua regia extraction technique for soils was applied to determine the elemental concentrations in the tailings. Iron (oxy)hydroxides formed as a result of oxidation of tailings were identified as three specific forms. The first form filled in rims and fissures of primary pyrites. The second one precipitated and coated the surfaces of gangue minerals and the final form was altered into yukonites. Initially, large amounts of acid-generating minerals, such as pyrite and arsenopyrite, might make the rapid progress of oxidation reactions, and lots of secondary minerals including iron (oxy)hydroxides and scorodite were formed. The rate of pH decrease in tailings diminished, in addition, as the exposure time of tailings to oxidation environments was prolonged and the acid-generating minerals were depleted. Rather, it is speculated that the pH of tailings increased, as the contribution of pH neutralization reactions by calcite contained in surrounding parental rocks became larger. The stability of secondary minerals, such as scorodite, were deteriorated due to the increase in pH, and finally arsenic might be leached out. Subsequently, calcimn and arsenic ions dissociated from calcites and scorodites were locally concentrated, and yukonite could be grown tertiarily. It is confirmed that this tertiary yukonite which is one of arsenate minerals and contains arsenic in high level plays a crucial role in immobilizing arsenic in tailings. In addition to immobilization of arsenic in yukonites, the results indicate that a huge amount of iron (oxy)hydroxides formed by weathering of pyrite which is one of typical primary minerals in tailings can strongly control arsenic behavior as well. Consequently, this study elucidates that through a sequence of various processes, arsenic which was leached out as a result of weathering of primary minerals, such as arsenopyrite, and/or redissolved from secondary minerals, such as scorodite, might be immobilized by various sorption reactions including adsorption, coprecipiation, and absorption.

• Journal of the Korean Society of School Health
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• v.22 no.1
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• pp.1-16
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• 2009

Purposes: The objective of this study was to develop a management program for Korean elementary school students suffering from asthma, which would be based on the Australian Asthma-Friendly Schools (AFS) program. Methods: On the basis of the AFS program, we designed a 6-month pilot project for asthmatic students in two elementary schools in a rural area and one elementary school in an urban area of Korea. The pilot project consisted of the following processes: identifying students with asthma in a school, educating school staffs and the parents of an asthmatic child, registering those with asthma, and installing emergency kits for asthma attacks in school health rooms. In order to evaluate these processes, group discussions were held between project team members and school staffs in each area. In addition, we conducted a postal survey of 144 households having an asthmatic child. Results: The screening process adopted in this program resulted in the early diagnosis in asthma; however, it needs to be evaluated economically due to expensive diagnostic test for asthma. For the school nurses, asthma lessons were evaluated as being very helpful for their tasks, while teachers tended to take less interest in the program with only 45% of all teachers attending these lessons. Almost all participating parents reported that such lessons would be beneficial for the care of their child, even though only 24.2% of the survey respondents (122 households) attended the lessons. Installing emergency kits in school health rooms was regarded as a key feature of this project. The introduction of a register card containing more specific health records of asthmatic students was considered necessary to replace the existing list of students with asthma. Conclusion: This study has merit in that a Korean asthma-friendly schools program was developed for the first time, despite the many obstacles to such programs becoming more common.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.1
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• pp.35-45
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• 2023

In this study, the sludge formation in the wastewater drain from the advanced packaging process mechanisms are revealed as well as the key factors, materials, and sludge prevention methods using surfactant. Compared with that of conventional packaging process, advanced packaging process employ similar process to the semiconductor fabrication process, and thus many processes may generate wastewater. In specific, a large amount of wastewater may generate during the carrier wafer bonding, photo, development, and carrier wafer debonding processes. In order to identify the key factors for the formation of sludge during the advanced packaging process, six types of chemicals including bonding glue, HMDS, photoresist (PR), PR developer, debonding cleaner, and water are utilized and mixing evaluation is assessed. As a result, it is confirmed that the black solid sludge is formed, which is originated by the sludge seed formation by hydrolysis/dehydration reaction of HMDS and sludge growth via hydrophobic-hydrophobic binding with sludge seed and PR. For the sludge prevention investigation, three surfactants of CTAB, PEG, and shampoo are mixed with the key materials of sludge, and it is confirmed that the sludge formations are successfully suppressed. The underlying mechanism behind the sludge formation is that the carbon tails of the surfactant bind to PR with hydrophobic-hydrophobic interaction and inhibit the reaction with HMDS-based slurry seeds to prevent the sludge formation. In this regard, it is expected that various problems like clogging in drains and pipes during the advanced packaging process may effectively solve by the injection of surfactants into the drains.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.474-480
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• 2016

In this study, formation background of biodiversity and its changes in the process of geologic history, and effects of climate change on biodiversity and human were discussed and the alternatives to reduce the effects of climate change were suggested. Biodiversity is 'the variety of life' and refers collectively to variation at all levels of biological organization. That is, biodiversity encompasses the genes, species and ecosystems and their interactions. It provides the basis for ecosystems and the services on which all people fundamentally depend. Nevertheless, today, biodiversity is increasingly threatened, usually as the result of human activity. Diverse organisms on earth, which are estimated as 10 to 30 million species, are the result of adaptation and evolution to various environments through long history of four billion years since the birth of life. Countlessly many organisms composing biodiversity have specific characteristics, respectively and are interrelated with each other through diverse relationship. Environment of the earth, on which we live, has also created for long years through extensive relationship and interaction of those organisms. We mankind also live through interrelationship with the other organisms as an organism. The man cannot lives without the other organisms around him. Even though so, human beings accelerate mean extinction rate about 1,000 times compared with that of the past for recent several years. We have to conserve biodiversity for plentiful life of our future generation and are responsible for sustainable use of biodiversity. Korea has achieved faster economic growth than any other countries in the world. On the other hand, Korea had hold originally rich biodiversity as it is not only a peninsula country stretched lengthily from north to south but also three sides are surrounded by sea. But they disappeared increasingly in the process of fast economic growth. Korean people have created specific Korean culture by coexistence with nature through a long history of agriculture, forestry, and fishery. But in recent years, the relationship between Korean and nature became far in the processes of introduction of western culture and development of science and technology and specific natural feature born from harmonious combination between nature and culture disappears more and more. Population of Korea is expected to be reduced as contrasted with world population growing continuously. At this time, we need to restore biodiversity damaged in the processes of rapid population growth and economic development in concert with recovery of natural ecosystem due to population decrease. There were grand extinction events of five times since the birth of life on the earth. Modern extinction is very rapid and human activity is major causal factor. In these respects, it is distinguished from the past one. Climate change is real. Biodiversity is very vulnerable to climate change. If organisms did not find a survival method such as 'adaptation through evolution', 'movement to the other place where they can exist', and so on in the changed environment, they would extinct. In this respect, if climate change is continued, biodiversity should be damaged greatly. Furthermore, climate change would also influence on human life and socio-economic environment through change of biodiversity. Therefore, we need to grasp the effects that climate change influences on biodiversity more actively and further to prepare the alternatives to reduce the damage. Change of phenology, change of distribution range including vegetation shift, disharmony of interaction among organisms, reduction of reproduction and growth rates due to odd food chain, degradation of coral reef, and so on are emerged as the effects of climate change on biodiversity. Expansion of infectious disease, reduction of food production, change of cultivation range of crops, change of fishing ground and time, and so on appear as the effects on human. To solve climate change problem, first of all, we need to mitigate climate change by reducing discharge of warming gases. But even though we now stop discharge of warming gases, climate change is expected to be continued for the time being. In this respect, preparing adaptive strategy of climate change can be more realistic. Continuous monitoring to observe the effects of climate change on biodiversity and establishment of monitoring system have to be preceded over all others. Insurance of diverse ecological spaces where biodiversity can establish, assisted migration, and establishment of horizontal network from south to north and vertical one from lowland to upland ecological networks could be recommended as the alternatives to aid adaptation of biodiversity to the changing climate.