• Economic and Environmental Geology
• /
• v.54 no.6
• /
• pp.709-716
• /
• 2021

In this study, an adsorbent prepared by natural drying of iron hydroxide-based sludge collected from settling basin at a mine drainage treatment facility located in Gangneung, Gangwon-do was used to remove fluoride in an artificial fluoride solution and mine drainage, and the adsorption characteristics of the adsorbent were investigated. As a result of analyzing the chemical composition, mineralogical properties, and specific surface area of the adsorbent used in the experiment, iron oxide (Fe₂O₃) occupies 79.2 wt.% as the main constituent, and a peak related to calcite (CaCO₃) in the crystal structure analysis was analyzed. It was also identified that an irregular surface and a specific surface area of 216.78 m²·g^-1. In the indoor batch-type experiment, the effect of changes in reaction time, pH, initial fluoride concentration and temperature on the change in adsorption amount was analyzed. The adsorption of fluoride showed an adsorption amount of 3.85 mg·g^-1 16 hours after the start of the reaction, and the increase rate of the adsorption amount gradually decreased. Also, as the pH increased, the amount of fluoride adsorption decreased, and in particular, the amount of fluoride adsorption decreased rapidly around pH 5.5, the point of zero charge at which the surface charge of the adsorbent changes. Meanwhile, the results of the isotherm adsorption experiment were applied to the Langmuir and Freundlich isotherm adsorption models to infer the fluoride adsorption mechanism of the used adsorbent. To understand the thermodynamic properties of the adsorbent using the Van't Hoff equation, thermodynamic constants 𝚫H° and 𝚫G° were calculated using the adsorption amount information obtained by increasing the temperature from 25℃ to 65℃ to determine the adsorption characteristics of the adsorbent. Finally, the adsorbent was applied to the mine drainage having a fluoride concentration of about 12.8 mg·L^-1, and the fluoride removal rate was about 50%.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.7
• /
• pp.987-994
• /
• 2021

The Yellow sea, as described in article 123 of UNCLOS, is semi-enclosed sea surrounded by the Republic of Korea, the People's Republic of China and North Korea. In addition, the Yellow Sea is one of the 66 large marine ecosystems as it contains large amounts of marine resources. According to article 194 of UNCLOS, states should be aware of rights and duties with respect to the protection and preservation of the marine environment to be engaged with countries directly as regional entity or indirectly. Therefore, the legal blank is urgent in terms of trans-boundary environmental pollutant issues. The UNDP has conducted a project called Yellow Sea Large Marine Ecosystem (YSLME) which has reached the 2^nd phase. The project has some notable achievements, namely performing joint activities on analysis of diagnostic trans-boundary issues in collaboration with China and South Korea, developing a strategic action plan based on TDA, and establishing regional strategic action plan. However, on the other hand, the project could not reflect the full participation of North Korea as a state party. As a result, the project has a limitation on effective implementation of RSAP. Therefore, this study focuses on the suggestion of a legally-binding trilateral treaty as a blue print for the next, 3^rd phase of the project. By analyzing the best practice of the Wadden Sea Trilateral Treaty case, the study verifies the validity of legislative measures on establishing and managing a legally-binding trilateral YSLME Commission. By suggesting a three phase treaty, incorporating a joint declaration by establishing the commission, the signing of the treaty, and formulating an umbrella convention and implementation arrangement, the study expects to guarantee the consistency and sustainability of the trilateral treaty regardless of political issues pertaining to North Korea.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.67 no.4
• /
• pp.253-264
• /
• 2022

In this study, we investigated the occurrence of viral diseases in the early growth stage of soybean to establish management practices. We collected 83 soybean samples showing abnormal symptoms, approximately 3-4 weeks after seeding in the breeding field of the National Institute of Crop Science. Viruses were detected in the collected samples using reverse transcription polymerase chain reaction (RT-PCR) and metatranscriptome analysis of all those samples. The incidence of viral diseases in the field was less than 1% overall and up to 50% in certain cultivars and lines. RT-PCR and metatranscriptome analysis detected Soybean yellow mottle mosaic virus (SYMMV), Soybean mosaic virus (SMV), Soybean yellow common mosaic virus, Peanut stunt virus, and soybean geminivirus A (SGVA). Among these detected viruses, SYMMV and SMV were identified as major viruses causing infection in the early growth stage of soybean, with detection rates of 53.7% and 42.6%, respectively. Soybeans infected with SYMMV showed typical mosaic symptoms, whereas those infected with SMV showed a variety of symptoms such as mosaic, mottle, stunt, and chlorotic spots. Transmission characteristics of these viruses are variable, such that SMV is primarily transmitted by seeds, whereas SYMMV could be transmitted by insects, soil, and seeds. In this study, SGVA was detected in the early growth stage of soybean, and research on the current status and its effects on soybean after the early growth stage should be conducted.

• Journal of Korea Entertainment Industry Association
• /
• v.13 no.3
• /
• pp.193-202
• /
• 2019

This study focuses on what changes are required as to a curriculum of dance department in the university in the age of the 4th industrial revolution. By comparing and analyzing the curricula of dance department in the five universities in Seoul, five academic subjects as to curricula of dance department, which covers what to learn for dance education in the age of the 4th industrial revolution, are presented. First, dance integrative education, the integration of creativity and science education, can be referred to as a subject that stimulates ideas and creativity and raises artistic sensitivity based on STEAM. Second, the curriculum characterized by prediction of the future prospect through Big Data can be utilized well in dealing with dance performance, career path of dance-majoring people, and job creation by analyzing public opinion, evaluation, and feelings. Third, video education. Seeing the images as modern major media tends to occupy most of the expressive area of art, dance by dint of video enables existing dance work to be created as new form of art, expanding dance boundaries in academic and performing art viewpoint. Fourth, VR and AR are essential techniques in the era of smart media. Whether upcoming dance studies are in the form of performance or education or industry, for VR and AR to be digitally applied into every relevant field, keeping with the time, learning about VR and AR is indispensable. Last, the 4th industrial revolution and the curriculum of dance art are needed to foresee the changes in the 4th industrial revolution and to educate changes, development and seeking in dance curriculum.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.1
• /
• pp.252-264
• /
• 2023

This paper proposes a design of a dual-band band-pass filter that integrates a λg/2 open SIR structure, a transmission line, and a fork-type structure with symmetric and asymmetric open stubs. To obtain the dual-band effect, the proposed filter uses the SIR structure and adjusts the impedance ratio of the SIR structure. Therefore, the position of the harmonics of the filter is shifted through the adjustment of the impedance ratio, and this can obtain a double-band effect. In order to obtain the dual-band characteristics, the dual-band effect is obtained by inserting a open stub between the SIR structures with the SIR structure divided in half. In addition, the second frequency response is obtained by adjusting the length of the open symmetrical stub in the fork-shaped structure. The asymmetrical open stub in the fork form achieves optimum bandwidth by adjusting the length. Therefore, the first center frequency of the proposed band-pass filter is 5.896 GHz and the bandwidth is 13.6 %. At this time, the measurement results are 0.13 dB and 33.6 dB. The second center frequency is 5.906 GHz and the bandwidth is 13.6 %. At this time, the measurement results are 0.15 dB and 19.8 dB. The reason is that when the impedance ratio (Δ) is higher than 1, the position of the harmonic is shifted to a lower frequency band. However, if the impedance ratio (Δ) is lowered by one step, the position of harmonics will move to a higher frequency band. The function of the filter designed using these characteristics can be obtained from the measurement result. The proposed band-pass filter has no coupling loss and no via energy concentration loss because there is no coupling structure of input/output and no via hole. Therefore, system integration is possible due to its excellent performance, and it is expected that dedicated short-range communication (DSRC) system applications used in traffic communication systems will be possible.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.12
• /
• pp.87-105
• /
• 2009

Nonlinear dynamic deformation characteristics, expressed in terms of normalized shear modulus reduction curve (G/$G_{max}-\log\gamma$, G/$G_{max}$ curve) and damping curve (D-$\log\gamma$), are important input parameters with shear wave velocity profile ($V_s$-profile) in the seismic analysis of (new or existing) fill dam. In this paper, the reasonable and economical methods to evaluate the nonlinear dynamic deformation characteristics for core zone and rockfill zone respectively are presented. For the core zone, 111 G/$G_{max}$ curves and 98 damping curves which meet the requirements of core material were compiled and representative curves and ranges were proposed for the three ranges of confining pressure (0~100 kPa, 100 kPa~200 kPa, more than 200 kPa). The reliability of the proposed curves for the core zone were verified by comparing with the resonant column test results of two kinds of core materials. For the rockfill zone, 135 G/$G_{max}$ curves and 65 damping curves were compiled from the test results of gravelly materials using large scale testing equipments. The representative curves and ranges for G/$G_{max}$ were proposed for the three ranges of confining pressure (0~50 kPa, 50 kPa~100 kPa, more than 100 kPa) and those for damping were proposed independently of confining pressure. The reliability of the proposed curves for the rockfill zone were verified by comparing with the large scale triaxial test results of rockfill materials in the B-dam which is being constructed.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.25 no.4
• /
• pp.261-283
• /
• 2023

This study aimed to review the performance stability of PET (Polyethylene terephthalate) fiber reinforcing materials among the synthetic fiber types for which the application of performance reinforcing materials to fiber-reinforced concrete is being reviewed by examining short-term and long-term performance changes. To this end, the residual performance was analyzed after exposing the PET fiber to an acid/alkali environment, and the flexural strength and equivalent flexural strength of the PET fiber-reinforced concrete mixture by age were analyzed, and the surface of the PET fiber collected from the concrete specimen was examined using a scanning microscope (SEM). The changes in were analyzed. As a result of the acid/alkali environment exposure test of PET fiber, the strength retention rate was 83.4~96.4% in acidic environment and 42.4~97.9% in alkaline environment. It was confirmed that the strength retention rate of the fiber itself significantly decreased when exposed to high-temperature strong alkali conditions, and the strength retention rate increased in the finished yarn coated with epoxy. In the test results of the flexural strength and equivalent flexural strength of the PET fiber-reinforced concrete mixture, no reduction in flexural strength was found, and the equivalent flexural strength result also did not show any degradation in performance as a fiber reinforcement. Even in the SEM analysis results, no surface damage or cross-sectional change of the PET reinforcing fibers was observed. These results mean that no damage or cross-section reduction of PET reinforcing fibers occurs in cement concrete environments even when fiber-reinforced concrete is exposed to high temperatures in the early stage or depending on age, and the strength of PET fibers decreases in cement concrete environments. The impact is judged to be of no concern. As the flexural strength and equivalent flexural strength according to age were also stably expressed, it could be seen that performance degradation due to hydrolysis, which is a concern due to the use of PET fiber reinforcing materials, did not occur, and it was confirmed that stable residual strength retention characteristics were exhibited.

• Analytical Science and Technology
• /
• v.19 no.3
• /
• pp.263-271
• /
• 2006

The levels of total PCBs, Co-PCBs and PCDD/Fs in the transformer insulation oil samples obtained using GC/ECD and HRGC/HRMS were ranged from N.D. to 77.3 ppm, from 0.0863 to 2.49 ppm and from N.D. to 0.00241 ppm, respectively. In terms of WHO-TEQ values, Co-PCBs and PCDD/Fs were ranged from 23.3 to 600 pgTEQ/g and from N.D. to 128 pgTEQ/g, respectively (${\Sigma}Co$-PCBs+PCDD/Fs concentration was calculated 24.4~728 pgTEQ/g). Although, the contribution of PCDD/Fs was below 12% in total TEQ concentration, it is suggested contamination of PCDD/Fs in transformer insulation oils. Among 10 samples, 4 samples showed higher concentration than 2 ppm (specific waste criterion of Korea) and Aroclor 1242, 1248, 1254 and 1260 was detected in samples as a single or mixture of Aroclor. It was shown reliable relationship between concentration of Co-PCBs and those of PCDD/Fs (p<0.003), however, was not shown between production year of transformer and concentration of PCBs. The distribution pattern of Co-PCB congeners showed that the ratios of mono-ortho substituted congeners were higher than non-ortho substituted congeners. Among that, PCB-118 congener was predominant. In addition, the OCDD congener was predominated in PCDD/Fs congeners as above 53%. Moreover, the congener pattern of Co-PCBs was similar to that of Aroclor as well as ambient air, which suggested that PCBs volatilization from transformer insulation oil affected the pattern of Co-PCBs in ambient air.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.2
• /
• pp.17-24
• /
• 2023

A post-processing technique for the measurement signal of a solenoid-type sensor is introduced. The solenoid-type sensor nondestructively evaluates an external tendon of prestressed concrete using the total flux leakage (TFL) method. The TFL solenoid sensor consists of primary and secondary coils. AC electricity, with the shape of a sinusoidal function, is input in the primary coil. The signal proportional to the differential of the input is induced in the secondary coil. Because the amplitude of the induced signal is proportional to the cross-sectional area of the tendon, sectional loss of the tendon caused by ruptures or corrosion can be identified by the induced signal. Therefore, it is important to extract amplitude information from the measurement signal of the TFL sensor. Previously, the amplitude was extracted using local maxima, which is the simplest way to obtain amplitude information. However, because the sampling rate is dramatically decreased by amplitude extraction using the local maxima, the previous method places many restrictions on the direction of TFL sensor development, such as applying additional signal processing and/or artificial intelligence. Meanwhile, the proposed method uses amplitude demodulation to obtain the signal amplitude from the TFL sensor, and the sampling rate of the amplitude information is same to the raw TFL sensor data. The proposed method using amplitude demodulation provides ample freedom for development by eliminating restrictions on the first coil input frequency of the TFL sensor and the speed of applying the sensor to external tension. It also maintains a high measurement sampling rate, providing advantages for utilizing additional signal processing or artificial intelligence. The proposed method was validated through experiments, and the advantages were verified through comparison with the previous method. For example, in this study the amplitudes extracted by amplitude demodulation provided a sampling rate 100 times greater than those of the previous method. There may be differences depending on the given situation and specific equipment settings; however, in most cases, extracting amplitude information using amplitude demodulation yields more satisfactory results than previous methods.

• Resources Recycling
• /
• v.32 no.3
• /
• pp.57-67
• /
• 2023

The treatment of waste plastic has primarily been entrusted to small companies, which has resulted in challenges in obtaining an accurate overview of the current state of affairs and ensuring profitability. Consequently, despite the presence of recycling technology, their practical application has proven to be challenging. In this study, as part of the waste plastic material recycling plan, it is assumed that the PET/OPP laminated waste film is peeled off at the waste film generation site for the second use. The recycling rate of PET/OPP delaminated waste film is assumed to be 2%, 10%, and 30% referring to the figures suggested by "Life-cycle Post Plastic Measures" from the Korean government. In this study, a physical separation method was developed as a recycling approach for waste PET. A result of cost-benefit analysis was conducted to evaluate the economic viability of the recycling process based on changes in the recycling rate. The findings indicated that a recycling rate of waste PET was 30% or higher resulted in a cost-benefit ratio (Benefit-cost ratio, BCR) of 1.32, exceeding the threshold of BCR ≥1, which is considered to meet the minimum requirement for cost-benefit balance. As the government's allocation ratio and unit price are expected to increase in the future, the cost-benefit ratio is expected to increase further. This case is expected to serve as a pilot initiative for waste PET recycling and foster profit creation for businesses in similar industries.