• Journal of Korean Society of Water and Wastewater
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• v.37 no.4
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• pp.177-186
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• 2023

Perfluorooctanoic acid(PFOA) was one of widely used per- and poly substances(PFAS) in the industrial field and its concentration in the surface and groundwater was found with relatively high concentration compared to other PFAS. Since various processes have been introduced to remove the PFOA, adsorption using GAC is well known as a useful and effective process in water and wastewater treatment. Surface modification for GAC was carried out using Cu and Fe to enhance the adsorption capacity and four different adsorbents, such as GAC-Cu, GAC-Fe, GAC-Cu(OH)₂, GAC-Fe(OH)₃ were prepared and compared with GAC. According to SEM-EDS, the increase of Cu or Fe was confirmed after surface modification and higher weight was observed for Cu and Fe hydroxide(GAC-Cu(OH)₂ and GAC-Fe(OH)₃, respectively). BET analysis showed that the surface modification reduced specific surface area and total pore volumes. The highest removal efficiency(71.4%) was obtained in GAC-Cu which is improved by 17.9% whereas the use of Fe showed lower removal efficiency compared to GAC. PFOA removal was decreased with increase of solution pH indicating electrostatic interaction governs at low pH and its effect was decreased when the point of zero charges(pzc) was negatively increased with an increase of pH. The enhanced removal of PFOA was clearly observed in solution pH 7, confirming the Cu in the surface of GAC plays a role on the PFOA adsorption. The maximum uptake was calculated as 257 and 345 ㎍/g for GAC and GAC-Cu using Langmuir isotherm. 40% and 80% of removal were accomplished within 1 h and 48 h. According to R², only the linear pseudo-second-order(pso) kinetic model showed 0.98 whereas the others obtained less than 0.870.

• Steel and Composite Structures
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• v.52 no.3
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• pp.327-341
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• 2024

This paper is the first in a series of articles dealing with the study and analysis of imperfections in thin-walled, cold-formed steel sections with modified cross-sectional shapes. A study was conducted, using 3D scanning techniques, to determine the most vulnerable geometric imperfections in the profiles. Based on a review of the literature, it has been determined that few researchers are studying thin-walled sections with modified cross-sectional shapes. Each additional bend in the section potentially generates geometric imperfections. Geometric imperfections significantly affect the resistance to loss of stability, which is crucial when analyzing thin-walled structures. In addition, the most critical locations along the length where these imperfections occur were determined. Based on the study, it was found that geometric imperfections cause a reduction in critical load. It should be noted that the tests performed are preliminary studies, based on which a program of further research will be developed. In addition, the article presents the current state of knowledge in the authors' field of interest. The future objective is to ascertain if these imperfections could potentially contribute positively to structural integrity. This enhanced understanding may pave the way for novel methodologies in structural engineering, wherein imperfections are viewed not solely as flaws but also as elements that could enhance the end product.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2153-2162
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• 2024

The purpose of this study is to develop a high-energy neutron shielding material applied in proton therapy environment. Composite shielding material consisting of 10.00 wt% boron carbide particles (B₄C), 13.64 wt% surface-modified cross-linked polyethylene (PE), and 76.36 wt% tungsten particles were fabricated by hot-pressure sintering method, where the optimal ratio of the composite is determined by the shielding effect under the neutron field generated in typical proton therapy environment. The results of Differential Scanning Calorimetry measurements (DSC) and tensile experiment show that the composite has good thermal and mechanical properties. In addition, the high energy-neutron shielding performance of the developed material was evaluated using cyclotron proton accelerator with 100 MeV proton. The simulation shows a 99.99% decrease in fast neutron injection after 44 cm shielding, and the experiment result show a 99.70% decrease. Finally, the shielding effect of replacing part of the shielding material of the proton therapy hall with the developed material was simulated, and the results showed that the total neutron injection decreased to 0.99‰ and the neutron dose reduced to 1.10‰ before the enhanced shielding. In summary, the developed material is expected to serve as a shielding enhancement material in the proton therapy environment.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.188-193
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• 2010

The aim of this study is to evaluate the effects of organic materials on soil organisms. Changes in the community structure, and population density of soil organisms (microbes, nematodes, and microarthropods) were studied in a Korean ginseng field. Phospholipid fatty acids analysis showed that the relative abundances of bacteria, fungi, and actinomycetes did not differ significantly. The aerobes/anaerobes ratio was the lowest in soils amended with leaf mold, indicating that the decomposition speed was slow. Further, the addition of leaf mold to the soil enhanced the saturated/monounsaturated fatty acid ratio and cyclopropyl fatty acid/precursor ratio, which indicated an increase in environmental stresses. Application of pig manure compost (PMC) had positive effects on the population density of nematodes, and negative effects on that of oribatid mites. The population densities of nematodes, and microarthropods remained relatively low in the plots that had been treated with leaf mold or pig manure compost. It is suggested that pre-planting soil management directed at enhancing the biological decomposition efficiency should be continued over a long period to increase the soil bioactivity in virgin soils.

• Journal of Hospice and Palliative Care
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• v.11 no.1
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• pp.12-29
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• 2008

Purpose: To develop the standardized record forms for home hospice team members, made up of nurse, doctor, social worker, minister and volunteer, to share information and communicate efficiently in their specialized field. Methods: A methodological study revising and complementing initially developed record forms by obtaining content validity from the experts in each field. Results: Reflecting total 27 experts' opinions, final 11 types of home hospice team documents (registration form, visiting record form for a nurse, initial assessment form for a doctor, progress note for a doctor, initial assessment form for spiritual care, visiting record form for a minister, care note for social worker, visiting record form for a volunteer, final summary note, initial assessment form for bereaved family, and follow-up record form for bereaved family) have been developed. Conclusion: It is believed that this study initiated of effective communication between home hospice team members and enhanced quality of home hospice service and its records.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2961-2966
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• 2012

Extremely low frequency electro magnetic fields (EMFs) have been classified as possibly carcinogenic to humans by the International Agency for Research on Cancer. An increased number of chromosomal alterations in peripheral lymphocytes are correlated with elevated incidence of cancer. The aim of the present study was to assess occupationally induced chromosomal damage in EMF workers exposed to low levels of radiation. We used conventional metaphase chromosome aberration (CA) analysis and the micronucleus (MN) assay as biological indicators of non ionizing radiation exposure. In the present study totally 70 subjects were selected including 50 exposed and 20 controls. Informed written consent was obtained from all participants and the study was performed in accordance with the Declaration of Helsinki and the approval of the local ethical committee. A higher degree of CA and MN was observed in exposed subjects compared to controls, the frequency of CA being significantly enhanced with long years of exposure (P<0.05). Moreover increase in CA and MN with age was noted in both exposed subjects and controls, but was significantly greater in the former. The results of this study demonstrated that a significant induction of cytogenetic damage in peripheral lymphocytes of workers occupationally exposed to EMFs in electric transformer and distribution stations. In conclusion, our findings suggest that EMFs possess genotoxic capability, as measured by CA and MN assays; CA analysis appeared more sensitive than other cytogenetic end-points. It can be concluded that chronic occupational exposure to EMFs may lead to an increased risk of genetic damage among electrical workers.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.4
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• pp.292-297
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• 2007

Global warming and climate changes have been major issues for decades andvarious researches have reported their impact on our environment. According to recent researches, increased carbon dioxide ($CO_2$) concentration in the atmosphere is considered as a dominant contributor to global climate changes and thus numerous researches were conducted to control $CO_2$ concentration in the atmosphere. Soil management practices, such as reducing tillage intensity, returning plant residues, and enhancing cropping system have recommended for restoring organic carbon into the soils effectively. However, few studies on soil carbon sequestration have reported for Korean paddy soils. Therefore, evaluation of soil organic carbon (SOC) dynamics in the long-term single rice cropping system is essential in order to find out potential capacity of paddy field as a carbon sink source. The objective of this research was to evaluate SOC dynamics on the long-term single rice cropping system. Research was conducted in the research farm at National Institute of Agricultural Science and Technology, Rural Development Administration, Suwon. Long-term phosphorus and potassium fertilization and lime application didn't significantly affect on SOC compared to controls. We found that SOC contents were increased continually at the long-term composting plots with enhanced rate of carbon storage. In conclusion, continuous incorporation of plant residues (i.e., composting) is recommended to effectively sequester soil carbon for Korean paddy soils. This result implies that continuous composting in a paddy field may contributenot only for increasing SOC in the soils but also for mitigating global warming through reducing carbon dioxide emission into atmosphere. Therefore, we recommend that a strategy or policy measures to encourage farmers to return plant residues continuously for mitigation of global warming as well as soil fertility is being developed.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.175-179
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• 2016

Recent advances in technology of medical image have made surgical simulation that is helpful to diagnosis, operation plan, or education. Improving and enhancing the medical imaging have led to the availability of high definition images and three-dimensional (3D) visualization, it allows a better understanding in the surgical and educational field. The Real human field of view is stereoscopic. Therefore, with just 2D images, stereoscopic reconstruction process through the surgeon's head, is necessary. To reduce these process, 3D images have been used. 3D images enhanced 3D visualization, it provides significantly shorter time for surgeon for judgment in complex situations. Based on 3D image data set, virtual medical simulations, such as virtual endoscopy, surgical planning, and real-time interaction, have become possible. This article describes principles and recent applications of newer imaging techniques and special attention is directed towards medical 3D reconstruction techniques. Recent advances in technology of CT, MR and other imaging modalities has resulted in exciting new solutions and possibilities of shoulder imaging. Especially, three-dimensional (3D) images derived from medical devices provides advanced information. This presentation describes the principles and potential applications of 3D imaging techniques, simulation and printing in shoulder and elbow practice.

• Composites Research
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• v.32 no.6
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• pp.301-306
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• 2019

Triboelectric nanogenerator (TENG) is one of the energy harvesting methods in spotlight that can convert mechanical energy into electricity. As TENGs produce high electrical output, previous studies have shown TENGs that can power small electronics independently. However, recent studies have reported limitations of TENG due to air breakdown and field emission. In this study, we developed a triboelectric nanogenerator that utilizes the metal-to-metal surface contact to induce ion-enhanced field emission and electron avalanche for electrons to flow directly between two electrodes. The average peak open-circuit voltage of this TENG was measured as 340 V, and average peak closed-circuit current was measured as 10 mA. The electrical output of this TENG has shown different value depending on the surface charge of surface charge generation layer. The TENG developed in this study have produced RMS power of 0.9 mW, which is 2.4 times higher compared to conventional TENGs. The TENG developed in this study can be utilized in charging batteries and capacitors to power portable electronics and sensors independently.

• Journal of Life Science
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• v.20 no.9
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• pp.1339-1344
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• 2010

In order to produce environmental-friendly fermented compost, a cattle manure-sawdust compost (antifungal compost) was developed by inoculation of B. licheniformis KJ-9 to cattle manure-sawdust. The thermal stability of the antifungal substance produced by B. licheniformis KJ-9 maintained more than 60% antifungal activity with heat treatment at $100^{\circ}C$ for 10 min, and the optimum pH of antifungal activity of the substance was 7.0. In a pot experiment with red pepper, the antifungal compost increased 1.5~2 times in leaf number and stem and root growth rate compared to those of commercial compost. Also, the diameter of stems increased 1.5-3 times in the antifungal compost treated group. The amount of microbes increased markedly in soil supplemented with antifungal compost compared to the control. In the field experiment for cultivation of garlic and Perilla japonica, the growth of both crops was significantly enhanced in the field treated with antifungal compost as compared to the commercial compost.