• Journal of the Society of Naval Architects of Korea
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• v.56 no.4
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• pp.343-351
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• 2019

Green water impact may sometimes cause some structure damages on ship's bow deck. Prediction of proper design pressure against the green water impact is an essential task to prevent the possible damages on bow deck. This paper presents a computational method of the bow deck's design pressure against the green water impact. Large heave and pitch motions of ship are calculated by the time domain nonlinear strip method. Green water flow and pressure on bow deck are simulated by the predictor-corrector second kind upstream finite difference method. This green water simulation method is based on the shallow water wave equations expanded for moving bottom conditions. For various kind of ships such as container ship, VLCC, oil tanker and bulk carrier, the green water design pressures on bow deck are computed and discussed. Also, the obtained results of design pressure on bow deck are compared with those of the classification society rules and discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.71-79
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• 2018

The purposes of this study were to identify the stress level of nursing students prior to clinical training and to examine the effects of aromatherapy on stress, stress perception, and mood during clinical practice. This study was a randomized control trial using a pre-post test conducted from May-July 2016. A total of 41 junior nursing students were recruited. The experimental group (n=22) underwent aroma inhalation using a necklace containing lavender essential oil and a control group (n=19) used a normal saline necklace. There were significant improvements in stress (p=.023) and mood levels in the experimental group (p=.006). The difference in stress perception between the experimental and control groups was not statistically significant (p=.382). Aroma therapy might be useful for decreasing stress and improving their positive mood during clinical practice for nursing students.

• Stress
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• v.25 no.4
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• pp.239-245
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• 2017

Background: A quasi-experimental study with non-equivalent control groups was performed to determine an effect of aromatherapy foot bath on stress and autonomic nervous activity. Methods: To confirm the effect of aromatherapy foot bath, aromatherapy foot bath group was asked to have a bathing by dropping 0.5 cc in 18 L water after blending with a ratio of 6:3:1 with essential oil lavender, lemon, and tea tree and a foot bath group was asked for bathing only by water. Results: Aromatherapy foot bath group showed significant decrease in subjective stress score (t=3.465, p=0.001) and stress index (t=3.021, p=0.004) in addition to simultaneous increase in sympathetic nervous activity (t=-2.913, p=0.005). However, no significant stimulation of parasympathetic nervous system was observed (t=-1.831, p=0.072). Conclusions: As aromatherapy foot bath is a possible effective intervention for stress relief, it can be applied as an effective method to relieve the stress for healthy adults and patients.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.41-47
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• 2020

As modern industries are highly being developed, it is required that mechanical parts have to be manufactured with a high precision. In order to have precise parts, error-free designs have to be done before manufacturing with accuracy. For this intention being fulfilled, a mechanical analysis is essential for design proof. Nowadays, FEM simulation is a popular tool for verifying a machine design. In this paper, an impeller, being utilized in a compressor or an oil mixer as an actuator, is studied for an evaluation. The purpose of this study is to present a safety of an impeller for a proof of its mechanical stability. A static analysis for stress, strain, and deformation within a regular usage is examined. This simulation test shows 357.26×106 Pa for maximum equivalent stress and 0.207mm for total deformation. A fatigue test is carried to provide durability and its result shows that minimum safety factor is 3.2889, which guarantees that it runs without a fatigue failure in 106 cycles. The natural frequencies for the impeller is ranged from 228.09Hz to 1,253.6Hz for the 1st to the 6th mode. Total deformations at these natural frequencies are shown from 6.84mm to 12.631mm. Furthermore, Campbell diagram reveals that a critical speed is not found throughout regular rotational speeds. From the test results for the analysis, this paper concludes that the suggested impeller is proved for its mechanical safety and good to utilize at industries.

• Membrane Journal
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• v.31 no.6
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• pp.384-392
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• 2021

Growing pollution due to industrialization leads to difficulties in survival of mankind. Generation of clean water from wastewater by membrane separation process is emerging cost efficient technology. Membrane prepared from renewable resources are in lots of demand to reduce burden on synthetic polymers which is one of the source of environmental pollution. Bacterial cellulose (BC) is very pure and distinct form of cellulose nanofibrils (CNF). Nanopapers prepared from CNF are used ad ultrafiltration (UF) and nanofiltration (NF) membrane for different applications. High crystallinity of BC gives rise to excellent mechanical property, an essential criterion for wastewater treatment membrane. In this review, BC based membrane for application in dye, oil, heavy metal and chemical removal from wastewater is discussed.

• Journal of Microbiology and Biotechnology
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• v.32 no.6
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• pp.730-739
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• 2022

Methicillin-resistant Staphylococcus aureus (MRSA) causes severe infections and poses a global healthcare challenge. The utilization of novel molecules which confer synergistical effects to existing MRSA-directed antibiotics is one of the well-accepted strategies in lieu of de novo development of new antibiotics. Thymol is a key component of the essential oil of plants in the Thymus and Origanum genera. Despite the absence of antimicrobial potency, thymol is known to inhibit MRSA biofilm formation. However, the anti-MRSA activity of thymol analogs is not well characterized. Here, we assessed the antimicrobial activity of several thymol derivatives and found that 4-chloro-2-isopropyl-5-methylphenol (chlorothymol) has antimicrobial activity against MRSA and in addition it also prevents biofilm formation. Chlorothymol inhibited staphyloxanthin production, slowed MRSA motility, and altered bacterial cell density and size. This compound also showed a synergistic antimicrobial activity with oxacillin against highly resistant S. aureus clinical isolates and biofilms associated with these isolates. Our results demonstrate that chlorinated thymol derivatives should be considered as a new lead compound in anti-MRSA therapeutics.

• Journal of the Korean Burn Society
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• v.23 no.2
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• pp.42-53
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• 2020

Purpose: It is important to consider both clinical factors and epidemiological factors in treating burn patients in emergency rooms. However, many emergency medical staffs happen to miss their chances of treating burns based on these considerations. This study is designed to find a better treatment for burn patients in emergency rooms along this approach. Methods: This study was conducted based on the data of the burn patients visiting the emergency room of a single general hospital from January 2015 to December 2019. The epidemiological and clinical factors were extracted out of the data, then the relationship between the prognosis and these factors were analyzed. Results: Most of burn accidents occurred at home, and were caused by hot water, soup, drinks, oil, etc. Especially, flame burns showed high hospitalization rate, surgical rate and mortality. In addition, their prognosis was poor when the affected area included facial, limb and perineal areas etc., or any inhalation burn co-existed. Also, the hospitalization rate and period increased when the treatment time was delayed or the pre-treatment was taken. There was a strong relationship between prognosis and the period of follow-up when patients were admitted during the period. Conclusion: It is difficult for medical staffs to evaluate prognosis of burns in emergency rooms due to progressive damages. Precise treatment and disposition are essential for patients' good prognosis. Therefore, medical staffs should establish treatment plans by identifying the patient's epidemiological and clinical factors, rather than giving prescriptions based on fragmentary and superficial symptoms.

• Nutrition Research and Practice
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• v.16 no.5
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• pp.616-627
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• 2022

BACKGROUND/OBJECTIVES: Vitamin E is essential for health, and although vitamin E deficiency seems rare in humans, studies on estimates of dietary intake are lacking. This study aimed to estimate dietary vitamin E intake, evaluate dietary adequacy of vitamin E, and detail major food sources of vitamin E in the Korean population. SUBJECTS/METHODS: This study used data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2016-2019. Individuals aged ≥ 1 year that participated in a nutrition survey (n = 28,418) were included. Dietary intake was assessed by 24-h recall and individual dietary vitamin E intake was estimated using a newly established vitamin E database. Dietary adequacy was evaluated by comparing dietary intake with adequate intake (AI) as defined by Korean Dietary Reference Intakes 2020. RESULTS: For all study subjects, mean daily total vitamin E intake was 7.00 mg α-tocopherol equivalents, which was 61.6% of AI. The proportion of individuals that consumed vitamin E at above the AI was 12.9%. Inadequate intake was observed more in females, older individuals, rural residents, and those with a low income. Mean daily intakes of tocopherol (α-, β-, γ-, and δ-forms) and tocotrienol were 6.02, 0.30, 6.19, 1.63, and 1.61 mg, respectively. The major food groups that contributed to total dietary vitamin E intake were grains (22.3%), seasonings (17.0%), vegetables (15.3%), and fish, and shellfish (7.4%). The top 5 individual food items that contributed to total vitamin E intake were baechu kimchi, red pepper powder, eggs, soybean oil, and rice. CONCLUSIONS: This study shows that mean dietary vitamin E intake by Koreans did not meet the reference adequate intake value. To better understand the status of vitamin E intake, further research is needed that considers intake from dietary supplements.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.134-134
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• 2019

Utilization of organic waste as a renewable energy source is promising for sustainability and mitigation of climate change. Pyrolysis converts organic waste to gas, oil, and biochar by incomplete biomass combustion. Biochar is widely used as a soil conditioner and adsorbent. Biochar adsorbs/desorbs metals and ions depending on the soil environment and condition to act as a nutrient buffer in soils. Biochar is also regarded as a carbon storage by fixation of organic carbon. Phosphorus (P) and nitrogen (N) are strictly controlled in many wastewater treatment plants because it causes eutrophication in water bodies. P and N is removed by biological and chemical methods in wastewater treatment plants and transferred to sludge for disposal. On the other hand, P is an irreplaceable essential element for all living organisms and its resource (phosphate rock) is estimated about 100 years of economical mining. Therefore, P and N recovery from waste and wastewater is a critical issue for sustainable human society. For the purpose, intensive researches have been carried out to remove and recover P and N from waste and wastewater. Previous studies have shown that biochars can adsorb and desorbed phosphates implying that biochars could be a complementary fertilizer. However, most of the conventional biochar have limited capacity to adsorb phosphates and nitrate. Recent studies have focused on biochar impregnated with metal salts to improve phosphates and nitrate adsorption by synthesizing biochars with novel structures and surface properties. Metal salts and metal oxides have been used for the surface modification of biochars. If P removal is the only concern, P adsorption kinetics and capacity are the only important factors. If both of P and N removal and the application of recovery are concerned, however, P and N desorption characteristics and bioavailability are also critical factors to be considered. Most of the researches on impregnated biochars have focused on P removal efficiency and kinetics. In this study, coffee waste is thermally treated to produce biochar and it was impregnated with Mg/Al to enhance phosphates and nitrate adsorption/desorption and P bioavailability to increase its value as a fertilizer. Kinetics of phosphates and nitrate adsorption/desorption and bioavailability analysis were carried out to estimate its potential as a P and N removal adsorbent in wasewater and a fertilizer in soil.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.4
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• pp.419-426
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• 2023

Objectives: This study aims to develop an Occupational Safety and Health (OSH) guide for the safe cleaning of contaminated machinery, equipment, and parts used in the electronics manufacturing process. Methods: A literature review, field investigations, and discussions were conducted. An initial draft of an OSH guide was developed and reviewed by experts with significant experience in maintenance work in the electronics manufacturing process in order to refine the guide. Results: Workers involved in cleaning processes with chemicals, solvents, and abrasive blasting can face exposure to a wide range of chemicals, abrasives, and noise. Identifying potential risks associated with each cleaning technique was an essential first step toward enhancing safety measures. The OSH guide comprises approximately eleven to twelve sections spanning 20-25 pages. It includes engineering and administrative protocols systematically organized to address the necessary actions before, during, and after cleaning tasks, depending on the technique. It is recommended that airline respirator masks be used in conjunction with an air purification system to ensure adherence to air quality standard "D" for atmosphere level. The use of an oil-free air compressor is advised, preferably a stationary model that does not rely on fuel sources like diesel. Conclusions: This OSH guide is designed to protect workers involved in maintenance activity in the electronics industry and aligns with global standards, such as those from the International Organization for Standardization (ISO) and Semiconductor Equipment and Material International, ensuring a higher level of safety and compliance.