• Clean Technology
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• v.25 no.1
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• pp.14-18
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• 2019

In general after the etching process, waste etching solution contains metals. (ex. Nickel (Ni), Chromium (Cr), Zinc (Zn), etc.) In this work, we proposed a recycling process for waste etching solution and refining from waste liquid contained nickel to make nickel metal nano powder. At first, the neutralization agent was experimentally selected through the hydrolysis of impurities such as iron by adjusting the pH. We selected sodium hydroxide solution as a neutralizing agent, and removed impurities such as iron by pH = 4. And then, metal ions (ex. Manganese (Mn) and Zinc (Zn), etc.) remain as impurities were refined by D2EHPA (Di-(2-ethylhexyl) phosphoric acid). The nickel powders were synthesized by liquid phase reduction method with hydrazine ($N_2H_4$) and sodium hydroxide (NaOH). The resulting nickel chloride solution and nickel metal powder has high purity ( > 99%). The purity of nickel chloride solution and nickel nano powders were measured by EDTA (ethylenediaminetetraacetic) titration method with ICP-OES (inductively coupled plasma optical emission spectrometer). FE-SEM (field emission scanning electron microscopy) was used to investigate the morphology, particle size and crystal structure of the nickel metal nano powder. The structural properties of the nickel nano powder were characterized by XRD (X-ray diffraction) and TEM (transmission electron microscopy).

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.576-583
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• 2018

Investigation of optimal temperature, irradiance and photoperiod conditions for free-living gametophytes of Saccharina sculpera for natural resources conservation and mass cultivation of endangered species in the eastern coast of Korea. Induction of regeneration and maturation of the free-living gametophytes of S. sculpera were cultured at temperatures (5, 10, 15, 20 and $25^{\circ}C$), irradiance (10, 20, 40, 60 and $80{\mu}mol\;photons\;m^{-2}\;s^{-1}$ and photoperiods (14:10, 12:12 and 10:14 h L:D). The female gametophyte were actively regenerated without reaching sexual maturity under $10^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$ and 12:12 h (L:D) conditions. In contrast, the conditions for male gametophytes were slightly different at $15^{\circ}C$, $10{\mu}mol\;photons\;m^{-2}\;s^{-1}$ and 12:12 h (L:D). The sexual maturation of female and male gametophytes took place under $15^{\circ}C$, $40{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 14:10 h (L:D) and $10^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10:14 h (L:D), respectively. These results provide basic information for controlling the regeneration and maturation of free-living gametophytes for conservation and utilization of S. sculpera.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.590-596
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• 2019

Uses of fossil fuels like coal and oil increases with industrial development, and problems like abnormal climate come up as greenhouse gas increases. Accordingly, studies are actively conducted on eco-friendly renewable energy as a replacement for the main resources, and especially, wood pellets with high thermal efficiency are in the limelight as an alternative fuel in thermal power stations and gas boilers. However, despite a constant increase in their usage, few studies are conducted on their risks like fire and spontaneous combustion. Thus, this study found the auto-ignition temperature and critical ignition temperature of wood pellets with a change in flow rate in a thermostatic bath, using a sample vessel with 20 cm in length, 20 cm in height and 14 cm in thickness to predict their ignition characteristics. Consequently, at the flow rate of 0 NL/min, as the core temperature of the sample increased to higher than the ambient temperature, they ignited at $153^{\circ}C$, when the critical ignition temperature was $152.5^{\circ}C$. At the flow rates of 0.5 NL/min and 1.0 NL/min, it was $149.5^{\circ}C$, and at the flow rate of 1.5 NL/min, it was $147.5^{\circ}C$. Consequently, at the same storage, the more the flow rate, the lower the critical ignition temperature became.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.240-245
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• 2011

Vegetation changes were studied for 16 yr in clearcut logged Pinus densiflora forests in the southern Gangwon-do province in Korea by applying chronosequence approach. Ambient temperature and relative humidity, Detrended Correspondence Analysis (DCA), Multiple Responses Permutation Procedure (MRPP), Indicator Species Analysis (ISPAN) were used to examine successional trajectory and compositional changes. After clearcutting, canopy openness was increased abruptly at three folds (1yr 68.3% and R1 23.0%) and then decreased, but relative moisture was slightly decreased (6%) compare to control site. In the result of DCA, right after clear cutting, vegetation composition was developed heterogeneously compared to control sites, and then approached to control sites within 16 years. Based on MRPP, species composition of each developmental stages (1yr, 3yr, 10yr and 16yr) revealed signigicant differences to that of control vegetation (R1, R3, R10 and R16). Indicator species in 1yr and 3yr samples included various woody species rather than herbaceous species, but in 10yr and 16yr, herbaceous were more abundant. Earlier succession of pine forests likely can explain to Initial Floristic Composition (IFC) Model.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.47-52
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• 2021

Recently, the share of wind power in energy markets has sharply increased with the active development of renewable energy internationally. In particular, large-scale wind farms are being developed far from the coast to make use of abundant wind resources and to reduce noise pollution. In addition to the electromagnetic interference (EMI) caused by offshore wind farms to coastal or air surveillance radars, it is necessary to investigate the EMI on global maritime distress and safety system (GMDSS) communications between ship and coastal stations. For this purpose, this study investigates whether the transmitted field of MF/HF band from a ship would be subject to interference or attenuation below the threshold at a coastal receiver. First, using geographic information system digital maps and 3D CAD models of wind turbines, the area of interest is electromagnetically modeled with patch models. Although high frequency analysis methods like Physical Optics are appropriate to analyze wide areas compared to its wavelength, the high frequency analysis method is first verified with an accurate low frequency analysis method by simplifying the surrounding area and turbines. As a result, the received wave power is almost the same regardless of whether the wind farms are located between ships and coastal stations. From this result, although wind turbines are large structures, the size is only a few wavelengths, so it does not interfere with the electric field of MF/HF distress communications.

• Journal of the Korea Society for Simulation
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• v.30 no.1
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• pp.113-126
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• 2021

The future energy consumption pattern will show a very different pattern from the present due to the increase of distributed power sources such as renewable energy and the birth of the concept of prosumers, etc. Accordingly, it can be predicted that the direction of establishment of an appropriate production and supply plan considering the stability and consumption efficiency of the entire power grid will also be different from now. This paper proposes a simulation model that can test a new operational strategy when faced with a number of possible future environments. Through the proposed model, it is possible to simulate and analyze power consumed and supplied in a future Smart Grid environment, in which a large amount of new concepts including energy storage service (ESS) and distributed energy resources (DER) will be added. In particular, it is possible to model complex systems structurally by using DEVS formalism among the ABM (Agent-Based Model) methodologies that can model decision-making for each agent existing in the grid, and several factors can be easily added to the grid. The simulation model was verified using given dataset in the current situation, and scenario analysis was performed by simply adding an ESS, one of the main elements of the smart grid, to the model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.33-44
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• 2023

Wind power is one of the most efficient and reliable energy sources in the transition to a low-carbon society. In particular, offshore wind power provides a high-quality and stable wind resource compared to onshore wind power while both present a higher installed capacity than other renewables. In this paper, we present our new program, the X-WIND program well suitable for the assessment of the substructure of offshore wind turbines. We have developed this program to increase the usability of analysis programs for offshore wind energy substructures by addressing the shortcomings of existing programs. Unlike the existing programs which cannot solely perform the substructure analyses or lack pre-post processors, our X-WIND program can complete the assessment analysis for the offshore wind turbines alone. The X-WIND program is embedded in AutoCAD so that both design and analysis are performed on a single platform. This also performs static and dynamic analysis for wind, wave, and current loads, essential for offshore wind power structures, and includes pre/post processors for designs, mesh developments, graph plotting, and code checking. With this expertise, our program enhances the usability of analysis programs for offshore wind energy substructures, promoting convenience and efficiency.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.1-12
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• 2023

Function of salivary gland and saliva composition can be an indicator of individual's health status. Recently, saliva has been thought to have a high potential for usage in the biomedical field to diagnose, evaluate, and prevent systemic health due to the technological advances in analyzing and detecting small elements such as immunological and metabolic products, viruses, microorganisms, hormones in saliva. As a diagnostic specimen, saliva has some useful advantages compared to serum. Because of simple non-invasive method, saliva sampling is quite comfort for the patient, and it doesn't require specialists to collect samples. The possibility of infection during the collection process is also low. For this reason, proteins, genetic materials, and various biomarkers in saliva are actively being utilized on studying stress, microbiomics, genetics, and epigenetics. For the research on collecting big data related to systemic health, the needs on biobank has been focused. Regeneration of salivary gland based on tissue engineering has been also on advancement. However, there are still many issues to be solved, such as the standardization of sample collection, storage, and usage. This review focuses on the recent trends in the field of saliva research and highlight the future perspectives in biomedical and other applications.

• Korea Science and Art Forum
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• v.24
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• pp.143-157
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• 2016

Focusing on the Gwangheemun that have a history of spatial specificity. Gwangheemun increase the value of space in the surrounding area, focused to derive a plan that can be activated. Research method was to analyze the characteristics and advantages and disadvantages of the surrounding space and the associated cultural content through SWOT analysis around the base of Gwangheemun. After considering the potential of the current location of physical characteristics and spatial resources, the possibility Gwangheemun development were mainly fashion and art content for the Space Vitalization in the surrounding area. Fashion and art space of Gwangheemun activated based on the possibility of Gwangheemun cultural meaning and value in the history of the past and the present time presented the main directions and strategic approach. The results of this research suggested Fashion art Hotel in applying urban regeneration methodologies, Cheongguro-16 plan for content development, arts and culture fashion street planning. Through this research, we want to establish the strategic control strategy between the policy decision making structures for the successful development of the fashion arts content.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.3
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• pp.103-113
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• 2024

This study is based on the design project of 'Sun-Garden' within the Solaseado Solar Power Plant located in Solaseado, which is a New City being developed in Haenam, Jeollanam-do. The purpose of this study is to create an integrated and sustainable energyscape that harmonizes energy infrastructure with the natural environment, while supporting the city's carbon neutrality agenda. To achieve this, design principles were established by considering three key aspects. The first aspect is economic, which seeks to create multifunctional spaces that integrate nature and technology, pursuing long-term sustainability while generating additional economic value. The second aspect is natural, emphasizing the creation of planting environments that conserve and enhance ecosystems, introduce region-specific species, and maintain ecosystem services and sustainable resource use. The third aspect is landscape, offering sensory and educational experiences to visitors and functioning as a landmark that symbolizes the carbon-neutral garden city of Solaseado through the aesthetic harmony of nature and technology. Through the creation of the 'Sun-Garden,' the Solaseado Solar Power Plant exemplifies a sustainable energyscape development model that merges economic, environmental, and landscape aspects beyond the conventional energy production facility. This project is expected to provide guidelines and implications for future energy infrastructure design, contributing to global energy transition efforts.