• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.192-197
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• 2022

Although various studies have focused on the relationship between essential oils (EOs) and skin flora, there are only few comparative studies on the antibacterial properties of EOs and their efficacy against common microorganisms. In this study, we tested the antibacterial activity of 10 different EOs against Staphylococcus epidermidis(S. epidermidis) with oxacillin as control. Optical density was used to measure the activity of solutions containing the EOs and S. epidermidis at two different concentrations. Three EOs (palmarosa, lemongrass, and Mellissa True) had higher antibacterial activity than oxacillin, but their concentrations had negligible effect on antibacterial activity.

• Korean Journal of Remote Sensing
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• v.40 no.1
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• pp.45-56
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• 2024

Faced with aging populations, declining resources, and limited agricultural productivity, rural areas in South Korea require innovative solutions. This study investigated the potential of drone-based vegetation indices (VIs) to analyze soybean growth patterns in open-field smart agriculture in Goesan-gun, Chungbuk Province, South Korea. We monitored multi-seasonal normalized difference vegetation index (NDVI) and the normalized difference red edge (NDRE) data for three soybean lots with different irrigation methods (subsurface drainage, conventional, subsurface drip irrigation) using drone remote sensing. Combining NDVI (photosynthetically active biomass, PAB) and NDRE (chlorophyll) offered a comprehensive analysis of soybean growth, capturing both overall health and stress responses. Our analysis revealed distinct growth patterns for each lot. LotA(subsurface drainage) displayed early vigor and efficient resource utilization (peaking at NDVI 0.971 and NDRE 0.686), likely due to the drainage system. Lot B (conventional cultivation) showed slower growth and potential limitations (peaking at NDVI 0.963 and NDRE 0.681), suggesting resource constraints or stress. Lot C (subsurface drip irrigation) exhibited rapid initial growth but faced later resource limitations(peaking at NDVI 0.970 and NDRE 0.695). By monitoring NDVI and NDRE variations, farmers can gain valuable insights to optimize resource allocation (reducing costs and environmental impact), improve crop yield and quality (maximizing yield potential), and address rural challenges in South Korea. This study demonstrates the promise of drone-based VIs for revitalizing open-field agriculture, boosting farm income, and attracting young talent, ultimately contributing to a more sustainable and prosperous future for rural communities. Further research integrating additional data and investigating physiological mechanisms can lead to even more effective management strategies and a deeper understanding of VI variations for optimized crop performance.

• Journal of Korean Society of Forest Science
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• v.76 no.2
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• pp.99-108
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• 1987

Half-sib seeds and one-year-old seedlings of Ginkgo biloba were treated with various simulated acid rains (pH 2.0, pH 3.0, pH 4.0 and pH 5.0) to examine the effects of acid rain on seed germination and seedling growth. The seeds were sown in a pot ($4500cm^3$) containing one of three different soils (nursery soil, mixed soil and sandy soil) and the seedlings were grown in the same pots as the seeds. Simulated acid rain was made by diluting sulfuric and nitric acid solution ($H_2SO_4$: $HNO_3$ = 3:1, V/V) with tap water and tap water (pH6.4), and treated by 5mm each time for three minutes during the growing seasons (April to October 1985 and April to August 1986). Acid rain treatments were done three times per week to potted seeds and seedlings by spraying the solutions. The seed germination, seedling growth and physiological characteristics of potted seedlings were compared among three soil types as well as among the various pH levels. The results obtained in this study were as follows: 1. Seed germination of Ginkgo biloba decreased significantly at pH 2.0 level in the field test, and also at the levels of both pH 2.0 and pH 3.0 in the laboratory test, compared to that at control. 2. For two-year-old seedlings, total, top and root dry weights per seedling were significantly different among the three soil types and among the levels of pH, and shoot growth was different only among the levels of pH. 3. For one-year-old seedlings, height and total and stem-branch dry weights per seedling were significantly different among the levels of pH.

• Journal of Korean Academy of Oral Health
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• v.42 no.4
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• pp.199-203
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• 2018

Objectives: The market for bottled water is increasing steadily in South Korea. Bottled water contains several naturally occuring minerals, such as calcium, magnesium, sodium, and fluoride. Fluoride is proven to be effective in preventing dental caries. In South Korea, the maximum permissible concentration of fluoride is 2 ppm for bottled water and 1.5 ppm for tap water. The aim of this study was to investigate the fluoride content of different commercially available brands of bottled water in South Korea, and compare the measured fluoride concentration to the concentration written on the label of each brand of bottled water. Methods: Twenty-seven of the 59 different brands of bottled water produced in South Korea were investigated in this study. Three bottles of each brand were purchased from supermarkets, marts, and convenience stores in each region of Korea in August 2016. For each bottled water brand, the fluoride content was measured three times using a fluoride-ion selective electrode (Orion ionplus Fluoride Electrode 9609, Orion Research, USA). The calibration curve was generated using 0.2 and 2 ppm standard solutions, and confirmed using a 1 ppm standard solution. Results: The mean fluoride content of the 27 brands of bottled water was $0.374{\pm}0.332mg/L$ (range=0.040 to 1.172 mg/L). The fluoride content was labeled by the manufacturer, on each of the tested brands of bottled water. In eight brands, the labeled fluoride content differed from the experimental data. The minimum to maximum fluoride content measured from 10 brands showed a variation of 0.3 mg/L or more when compared to the labeled fluoride content. Conclusions: This study investigated the fluoride content of various brands of bottled water produced in South Korea and compared the measured fluoride levels with fluoride information on the bottle labels. To ensure that consumers are suitably informed regarding their exposure to fluoride, correct labelling of fluoride content in bottled water is important.

• Journal of Radiation Protection and Research
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• v.44 no.4
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• pp.128-148
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• 2019

Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

• Preventive Nutrition and Food Science
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• v.14 no.2
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• pp.142-147
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• 2009

In this study, the selenium (Se) accumulations of soybean sprouts and mungbean sprouts treated with various concentrations of Se-solutions were evaluated, as part of a broader effort to produce Se-enriched variants of the plants. Four levels of sodium selenate ($Na_{2}SeO_{4}$)-dissolved solutions (i.e. 0, T0; 6, T1; 60, T2; and $600{\mu}g/mL$, T3) were prepared and sprayed onto the plants during cultivation. The effect of different spraying periods on Se accumulation was also assessed by watering plant groups once a day for periods of one, two, or three days. Se solution remaining on the surfaces of the plants was washed out by spraying with distilled water on the final day of cultivation. However, the increase of Se accumulation in the plants was found to depend on both Se-concentration and watering period, and the soybean sprouts were determined to accumulate Se more effectively than the mungbean sprouts. Additionally, with regard to Se accumulation in the plants, the period of application of Se solution was determined to be more important than the concentration of the Se solution applied. The averaged total levels of Se-enrichment in whole soybean sprouts at T0, T1, T2, and T3 were 0.26, 65.86, 179.62, and $525.12{\mu}g/dry$ matter (DM) g, respectively, and the relative equations relating Se enrichment in soybean sprouts (Y) against watering days (X) were Y=32.505X-36.17 (T1), Y=88.46X-92.04 (T2), and Y=251.11X-254.9(T3). The averaged total levels of Se-enrichment in the whole mungbean sprouts at T1, T2, and T3 group were 0.05, 3.64, and $101.43{\mu}g/DM$ g, respectively, and the relative equations relating Se enrichment (Y) to watering days (X) for mungbean sprouts were Y=1.67X-1.3467 at T1 and Y=48.035X-46.907 at T2. The results of this study suggest that soybean sprouts and mungbean sprouts enriched with bioavailable Se can be produced on a large scale by Se supplementation, allowing for the development of healthy functional foods such as Se-enriched mungbean sprout soups and salads, Se-enriched functional drink and food additives, and selenium tablets to promote health.

• The Journal of Society for e-Business Studies
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• v.20 no.4
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• pp.193-208
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• 2015

In knowledge based society, information technology (IT) has been playing a key role in economic growth. In recent years, it is surprisingly notable that the source of value creation moved from hardware to software in IT industry. Especially, among many kinds of software products, the economic potential of open source was realized by many government agencies. Open source means software codes made by voluntary and open participation of worldwide IT developers, and many policies to promote open source activities were implemented for the purpose of fast growth in IT industry. But in many cases, especially in Korea, the policies promoting open source industry and its ecosystem were not considered successful. Therefore, this study provides the practical reasons for the low performance of Korean open source industry and suggests the pragmatic requisites for effective open source policy. For this purpose, this study applies soft system model (SSM) which is frequently used in academy and industry as a methodology for problem-solving and we link the problems with corresponding policy solutions based on SSM. Given concerns which Korean open source faces now, this study suggests needs for the three different kinds of government policies promoting multiple dimensions of industry: research and development (R&D)-side, supply-side, and computing environment-side. The implications suggested by this research will contribute to implement the practical policy solutions to boost open source industry in Korea.

• Journal of Soil and Groundwater Environment
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• v.11 no.1
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• pp.23-36
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• 2006

Experimental leaching of tailings was performed as a function of times (1, 2, 4, 7, 14, 21 and 30 days) in the laboratory using reaction solutions equilibrated to three different pH set-points (pHs 1,3 and 5). The initial pHs of 5 and 3 stabilized at either 4.6-6.1 or 2.8-3.5 in 2 days and decrease gradually with time afterwards. The results of the leaching tests indicate that the significant increase in the sulfate concentrations and in acidity after 7 days of leaching results from the oxidation of sulfide minerals. There were no significant variations in the extractable Pb found in the leach solutions of pH 5 and 3 within the reaction time (1-30 days), while Zn, Cd and Cu concentrations tend to significantly increase with time. In tailings leaching at an initial pH=1, two trends were observed: i) The 'Zn-type' (Zn, Cd and Cu), with increasing concentrations between days 1 and 30, corresponding to the expected trend when continuous dissolution is the dominant process, ii) the 'Pb-type' (Pb), with decreasing concentrations over time, suggesting rapid dissolution of a Pb source followed by the precipitation of 'anglesite' in relation to the large increase in dissolved sulfates. The high sulfate concentrations were coupled with high concentrations of released Fe, Zn and Cd. Release of Zn and Cd and acidity from these leaching experiments can potentially pose adverse impact to surface and groundwater qualities in the surrounding environment. The kinetic problems could be the important factor which leads to increasing concentrations of trace metals in the runoff water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.418-418
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• 2008

The electrochemical etching of silicon in HF-based solutions is known to form various types of porous structures. Porous structures are generally classified into three categories according to pore sizes: micropore (below 2 nm in size), mesopore (2 ~ 50 nm), and macropore (above 50 nm). Recently, the formation of macropores has attracted increasing interest because of their promising characteristics for an wide scope of applications such as microelectromechanical systems (MEMS), chemical sensors, biotechnology, photonic crystals, and photovoltaic application. One of the promising applications of macropores is in the field of MEMS. Anisotropic etching is essential step for fabrication of MEMS. Conventional wet etching has advantages such as low processing cost and high throughput, but it is unsuitable to fabricate high-aspect-ratio structures with vertical sidewalls due to its inherent etching characteristics along certain crystal orientations. Reactive ion dry etching is another technique of anisotropic etching. This has excellent ability to fabricate high-aspect-ratio structures with vertical sidewalls and high accuracy. However, its high processing cost is one of the bottlenecks for widely successful commercialization of MEMS. In contrast, by using electrochemical etching method together with pre-patterning by lithographic step, regular macropore arrays with very high-aspect-ratio up to 250 can be obtained. The formed macropores have very smooth surface and side, unlike deep reactive ion etching where surfaces are damaged and wavy. Especially, to make vertical microwire or nanowire arrays (aspect ratio = over 1:100) on silicon wafer with top-down photolithography, it is very difficult to fabricate them with conventional dry etching. The electrochemical etching is the most proper candidate to do it. The pillar structures are demonstrated for n-type silicon and the formation mechanism is well explained, while such a experimental results are few for p-type silicon. In this report, In order to understand the roles played by the kinds of etching solution and mask patterns in the formation of microwire arrays, we have undertaken a systematic study of the solvent effects in mixtures of HF, dimethyl sulfoxide (DMSO), iso-propanol, and mixtures of HF with water on the structure formation on monocrystalline p-type silicon with a resistivity with 10 ~ 20 $\Omega{\cdot}cm$. The different morphological results are presented according to mask patterns and etching solutions.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.219-228
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• 2010

It has been well known that concrete structures exposed to acid and sulfate environments such as sewer, sewage and wastewater, soil, groundwater, and seawater etc. show significant decrease in their durability due to chemical attack. Such deleterious acid and sulfate attacks lead to expansion and cracking in concrete, and thus, eventually result in damage to concrete matrix by forming expansive hydration products due to the reaction between portland cement hydration products and acid and sulfate ions. Objectives of this experimental research are to investigate the effect of mineral admixtures on the resistance to acid and sulfate attack in concrete and to suggest high-resistance concrete mix against acid and sulfate attack. For this purpose, concretes specimens with three types of cement (ordinary portland cement (OPC), binary blended cement (BBC), and ternary blended cement (TBC) composed of different types and proportions of admixtures) were prepared at water-biner ratios of 32% and 43%. The concrete specimens were immersed in fresh water, 5% sulfuric acid, 10% sodium sulfate, and 10% magnesium sulfate solutions for 28, 56, 91, 182, and 365 days, respectively. To evaluate the resistance to acid and sulfate for concrete specimens, visual appearance changes were observed and compressive strength ratios and mass change ratios were measured. It was observed from the test results that the resistance against sulfuric acid and sodium sulfate solutions of the concretes containing mineral admixtures were much better than that of OPC concrete, but in the case of magnesium sulfate solution the concretes containing mineral admixtures was less resistant than OPC concrete due to formation of magnesium silicate hydrate (M-S-H) which is non-cementitious.