• Journal of the Korean Wood Science and Technology
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• v.35 no.1
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• pp.73-80
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• 2007

This study was carried out to separate the heavy toxic metals in eco-building materials by low-temperature pyrolysis, especially arsenic (As) compounds in CCA wood preservative as a solid in char. The pyrolysis was carried out to heat the CCA-treated Hemlock at $280^{\circ}C$, $300^{\circ}C$, $320^{\circ}C$, and $340^{\circ}C$ for 60 mins. Laboratory scale pyrolyzer composed of [preheater$\rightarrow$pyrolyzer$\rightarrow$1st water scrubber$\rightarrow$2nd bubbling flask with 1% $HNO_3$ solution$\rightarrow$vent], and was operated to absorb the volatile metal compound particulates at the primary water scrubber and the secondary nitric acid bubbling flask with cooling condenser of $4^{\circ}C$ under nitrogen stream of 20 mL/min flow rate. And the contents of copper, chromium and arsenic compounds in its pyrolysis such as carbonized CCA treated wood, 1st washing and 2nd washing liquors as well as its raw materials, were determined using ICP-AES. The results are as follows : 1. The yield of char in low-temperature pyrolysis reached about 50 percentage similar to the result of common pyrolytic process. 2. The higher the pyrolytic temperature was, the more the volatiles of CCA, and in particular, the arsenic compounds were to be further more volatile above $320^{\circ}C$, even though the more repetitive and sequential monitorings were necessary. 3. More than 85 percentage of CCA in CCA-treated wood was left in char in such low-temperature pyrolytic condition at $300^{\circ}C$. 4. Washing system for absorption of volatile CCA in this experiment required much more contacting time between volatile gases and water to prevent the loss of CCA compounds, especially the loss of arsenic compound. 5. Therefore, more complete recovery of CCA components in CCA-treated wood required the lower temperature than $320^{\circ}C$, and the longer contacting time of volatile gases and water needed the special washing and recovery system to separate the toxic and volatile arsenic compounds in vent gases.

• Journal of Wetlands Research
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• v.8 no.2
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• pp.53-64
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• 2006

A study on the restoration process of a stream ecosystem and the water quality renovation technique by removing algae, vegetation and fish monitoring as evaluating the removal of the algae by dietetic characteristics of fishes were performed on Sangdong stream in the B city after stream restoration it to the artificial stream as the cases, restoring urban stream into close-to-nature stream are being increased domestically with the aim of ecological city. As a result, restoration and rehabilitation of the fundamental stream ecosystem was well maintained 4 years later the reclamation at the moment and total 93 diagnosis which were all vascular plant phylum including 44 families, 73 genuses, 79 species and 14 varieties in flora and vegetation community were observed. 3 families, 8 species and 354 populations in total among Fishes were found and Pseudorasbora Parva, Cyprinus Carpic and Carassius Auratus strongly resistant to water pollution were dominantly appeared in order of 50.5% of Pseudorasbora Parva 21.2% of Cyprinus Carpic, 20.9% of Carassius Auratus, 7.1% of Macropodus chinensis and 0.3% of Misqurnus anguillicaudatus according to relative richness index. It turned out to be that Cyprinus Carpic ingests algae over 90% and Carassius Auratus takes it over 30% according to the analysis about the alimentary object of the fishes as a consequences of algae's excrescent from characteristics of the tested experimental stream. It is reported that a Cyprinus Carpic, about 34 cm in length, ingested wet-weight 43.2g algae on the rough analysis toward the sample which makes us recognize how effective a macro community Cyprinus Carpic is for removing algae.As a consequence of this research, the effect of stream ecosystem characteristics and water quality purification could not be expected by aquatic plants and trees which were eliminated at experimental stream. From now on, a close-to-nature stream should be formed of ecological hydraulic and hydrologic engineered modeling from the beginning so that it can perform the water quality purifying function. It is determined that the structure of food chain will be abundantly influenced by the induction of oversized macro community like Cyprinus Carpic because a biomass of a consumer of higher order is increased. It is estimated that the removal algae by fishes is not effective despite in some cases of dietetic characteristics so much more studies should be executed in the future.

• Korean Journal of Environment and Ecology
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• v.32 no.6
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• pp.686-697
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• 2018

Due to the advance in remote sensing technology, it has become easier to more frequently obtain high resolution imagery to detect delicate changes in an extensive area, particularly including forest which is not readily sub-classified. Time-series analysis on high resolution images requires to collect extensive amount of ground truth data. In this study, the potential of land coverage mapas ground truth data was tested in classifying high-resolution imagery. The study site was Wonju-si at Gangwon-do, South Korea, having a mix of urban and natural areas. KOMPSAT-3A imagery taken on March 2015 and land coverage map published in 2017 were used as source data. Two pixel-based classification algorithms, Support Vector Machine (SVM) and Random Forest (RF), were selected for the analysis. Forest only classification was compared with that of the whole study area except wetland. Confusion matrixes from the classification presented that overall accuracies for both the targets were higher in RF algorithm than in SVM. While the overall accuracy in the forest only analysis by RF algorithm was higher by 18.3% than SVM, in the case of the whole region analysis, the difference was relatively smaller by 5.5%. For the SVM algorithm, adding the Majority analysis process indicated a marginal improvement of about 1% than the normal SVM analysis. It was found that the RF algorithm was more effective to identify the broad-leaved forest within the forest, but for the other classes the SVM algorithm was more effective. As the two pixel-based classification algorithms were tested here, it is expected that future classification will improve the overall accuracy and the reliability by introducing a time-series analysis and an object-based algorithm. It is considered that this approach will contribute to improving a large-scale land planning by providing an effective land classification method on higher spatial and temporal scales.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.344-351
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• 2019

The purpose of this study was to obtain the basic data for developing more advanced courses on character education by surveying and analyzing the perception and demands of character education of university students and further, to provide useful information for creating institutional protocol on character education. The study was conducted from April 2018 to May 2018 on students attending the departments of non-health science and health science university students. A total of 206 students participated in this study, and all the students in the non-health science and health science departments were found to be highly aware of the need for character education, its importance and the possibility of personality development through learning. Students from all the departments showed high levels on average in terms of self-understanding according to their personality abilities, and especially their high levels of 'consideration' and 'responsibility'. For the differences in perception of self-efficacy, the lowest level of recognition was for 'will' and the average values were not high. In their response to personality level, all students answered that their personality was 'high' (42.1%), and that the personality education courses at the schools they are currently attending were 'not satisfied' with both the non-health science and health science students. As a result, there were higher results overall for the health science students than that for the non-health science students, but there were not many significant differences. To this end, education institutes will have to prepare conditions for university students to cultivate their expertise in character, while at the same time helping them grow into human beings with the qualities demanded by society. In addition, the government should establish curriculums and content by accurately identifying the needs of character education and devising concrete measures for their implementation, and by more faithfully considering quantitative and qualitative context types for the content base of character education.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.201-210
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• 2019

Recently, due to the efforts to mitigate traffic congestion and expansion of space efficiency, the construction of underground roads has been increased in big-scale cities. Since tunnels in the city have a higher chance for a fire leading to a great tragedy during a severe traffic jam than mountain tunnels, it is highly likely that it will be constructed as a tunnel, having a small cross section, for small vehicles. However, if they are constructed as such small-vehicle tunnels, it would be possible to reduce the design fire intensity while the concentration of harmful gases would increase due to a reduction in the small cross sectional area, led by a decrease in the tunnel height. In this study, behaviors of fire smoke by the installation interval and format of large-scale exhaust-gas ports were examined and compared in the analysis of temperatures and CO concentrations of a tunnel and its results were as the following. Although there were no significant differences in the smoke spreading distance between installation intervals, but in this study, 100 m was found to be the most effective installation interval. The smoke exhaustion performance was found to be excellent in the order of $4m{\times}3m$, $6m{\times}2m$, and $3m{\times}2m$ (2 lane) of the smoke spreading distance. Although there was no significant difference in the smoke spreading distance between formats of large-scale exhaust-gas ports, it was found that the smoke spreading distance was larger than other cases when it was $3m{\times}2m$ in the fire growing process. The analysis of smoke spreading distances by the aspect ratio showed that a smoke spreading distance was shorted when its the smoke spreading distance was found to be shorter when its traverse distance was relatively longer than its longitudinal distance.

• Journal of Broadcast Engineering
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• v.24 no.1
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• pp.118-131
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• 2019

In order to provide 8K UHD contents of terrestrial broadcasting with a large capacity, the terrestrial broadcasting system has various problems such as limited bandwidth and so on. To solve these problems, UHD contents transmission technology has been actively studied, and an 8K UHD broadcasting system using terrestrial broadcasting network and communication network has been proposed. The proposed technique is to solve the limited bandwidth problem of terrestrial broadcasting network by segmenting 8K UHD contents and transmitting them to heterogeneous networks through hierarchical separation. Through the terrestrial broadcasting network, the base layer corresponding to FHD and the additional enhancement layer data for 4K UHD are transmitted, and the additional enhancement layer data corresponding to 8K UHD is transmitted through the communication network. When 8K UHD contents are provided in such a way, user can receive up to 4K UHD broadcasting by terrestrial channels, and also can receive up to 8K UHD additional communication networks. However, in order to transmit the 4K UHD contents within the allocated bit rate of the domestic terrestrial UHD broadcasting, the compression rate is increased, so a certain level of image deterioration occurs inevitably. Due to the nature of UHD contents, video quality should be considered as a top priority over other factors, so that video quality should be guaranteed even within a limited bit rate. This requires packet scheduling of content generators in the broadcasting system. Since the multiplexer sends out the packets received from the content generator in order, it is very important to make the transmission time and the transmission rate of the process from the content generator to the multiplexer constant and accurate. Therefore, we propose a variable transmission scheduler between the content generator and the multiplexer to guarantee the image quality of a certain level of UHD contents in this paper.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.272-279
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• 2021

A pump-type eDNA filtering system that can control voltage and hydraulic pressure respectively has been developed, and applied a filter case that can filter out without damaging the filter. The filtering performance of the developed system was evaluated by comparing the eDNA concentration with the conventional vacuum-pressured filtering method at the catchment conduit intake reservoir. The developed system was divided into a voltage control (manual pump system) method and a pressure control (automatic pump system) method, and the pressure was measured during filtering and the pressure change of each system was compared. The voltage control method started with 65 [KPa] at the beginning of the filtering, and as the filtering time elapsed, the amount of filtrate accumulated in the filter increased, so the pressure gradually increased. As a result of controlling the pressure control method to maintain a constant pressure according to the designed algorithm, there was a difference in the width of the hydraulic pressure fluctuation during the filtering process according to the feedback time of the hydraulic pressure sensor, and it was confirmed that the pressure was converged to the target pressure. The filtering performance of the developed system was confirmed by measuring the eDNA concentration and comparing the voltage control method and the hydraulic control method with the control group. The voltage control method obtained similar results to the control group, but the hydraulic control method showed lower results than the control group. It is considered that the low eDNA concentration in the hydraulic control method is due to the large pressure deviation during filtering and maintaining a constant pressure during the filtering process. Therefore, rather than maintaining a constant pressure during filtering, it was confirmed that a voltage control method in which the pressure is gradually increased as the filtrate increases with the lapse of filtering time is suitable for collecting eDNA. As a result of comparing the average concentration of eDNA in lentic zone and lotic zone as a control group, it was found to be 96.2 [ng µL^-1] and 88.4 [ng µL^-1l], respectively. The result of comparing the average concentration of eDNA by the pump method was also high in the lentic zone sample as 90.7 [ng µL^-1] and 74.8 [ng µL^-1] in the lentic zone and the lotic zone, respectively. The high eDNA concentration in the lentic zone is thought to be due to the influence of microorganisms including the remaining eDNA.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.603-620
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• 2021

A land nodal seismic system was employed to acquire seismic reflection data using stand-alone cable-free receivers in a land-river area. Acquiring reliable data using this technology is very cost effective, as it avoids topographic problems in the deployment and collection of receivers. The land nodal airgun system deployed on the mouth of the Hyungsan River (in Pohang, Gyeongsangbuk Province) used airgun sources in the river and receivers on the riverbank, with subparallel source and receiver lines, approximately 120 m-spaced. Seismic data collected on the riverbank are characterized by a low signal-to-noise (S/N) and inconsistent reflection events. Most of the events are represented by hyperbola in the field records, including direct waves, guided waves, air waves, and Scholte surface waves, in contrast to the straight lines in the data collected conventionally where source and receiver lines are coincident. The processing strategy included enhancing the signal behind the low-frequency large-amplitude noise with a cascaded application of bandpass and f-k filters for the attenuation of air waves. Static time delays caused by the cross-offset distance between sources and receivers are corrected, with a focus on mapping the shallow reflections obscured by guided wave and air wave noise. A new time-distance equation and curve for direct and air waves are suggested for the correction of the static time delay caused by the cross-offset between source and receiver. Investigation of the minimum cross-offset gathers shows well-aligned shallow reflections around 200 ms after time-shift correction. This time-delay static correction based on the direct wave is found essential to improving the data from parallel source and receiver lines. Data acquisition and processing strategies developed in this study for land nodal airgun seismic systems will be readily applicable to seismic data from land-sea areas when high-resolution signal data becomes available in the future for investigation of shallow gas reservoirs, faults, and engineering designs for the development of coastal areas.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.6
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• pp.815-824
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• 2022

Among the main facilities of the power plant, the circulating water used for cooling the power generation system is supplied through the Circulation Water Intake Basin (CWIB). The vortexes of various types generated in the Pump Sump (PS) of CWIB adversely affect the Circulation Water Pump (CWP) and pipelines. In particular, the free surface vortex accompanied by air intake brings about vibration, noise, cavitation etc. and these are the causes of degradation of CWP performance, damage to pipelines. Then power generation is interrupted by the causes. Therefore, it is necessary to investigate the hydraulic characteristics of CWIB through the hydraulic model experiment and apply an appropriate Anti Vortex Device (AVD) that can control the vortex to enable smooth operation of the power plant. In general, free surface vortex is controlled by Curtain Wall (CW) and the submerged vortex is by the anti vortex device of the curtain wall. The detailed specifications are described in the American National Standard for Pump Intake Design. In this study, the circulating water intake part of the Tripoli West 4×350 MW power plant in Libya was targeted, the actual operating conditions were applied, and the vortex reduction effect of the anti vortex device generated in the suction tank among the circulating water intake part was analyzed through a hydraulic model experiment. In addition, a floor splitter was basically applied to control the submerged vortex, and a new type of column curtain wall was additionally applied to control the vortex generated on the free surface to confirm the effect. As a result of analyzing the hydraulic characteristics by additionally applying the newly developed Column Curtain Wall (CCW) to the existing curtain wall, we have found that the vortex was controlled by forming a uniform flow. In addition, the vortex angle generated in the circulating water pump pipeline was 5° or less, which is the design standard of ANSI/HI 9.8, confirming the stability of the flow.

• Journal of Korea Water Resources Association
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• v.55 no.8
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• pp.603-611
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• 2022

In urban areas, the impermeable area continues to increase due to urbanization, which interferes with the surface penetrating and infiltrating of rainwater, causing most rainwater runoff to the surface, deepening the distortion of water circulation. Distortion of water circulation affects not only flood disasters caused by rainfall and runoff, but also various aspects such as dry stream phenomenon, deterioration of water quality, and destruction of ecosystem balance, and the Ministry of Environment strongly recommends the use of Low Impact development (LID) techniques. In order to apply the LID technique, it is necessary to set a rainwater management target to handle the increase in outflow after the development of the target site, and the current standard sets the rainwater management target using the 10-year daily rainfall. In this study, the difference from the current standards was analyzed through statistical analysis and classification of independent rainfall ideas using inter-event time definition (IETD) in setting the target amount of rainwater management to improve water circulation. Using 30-year rainfall data from 1991 to 2020, methods such as autocorrelation coefficient (AC) analysis, variation coefficient (VC) analysis, and annual average number of rainfall event (NRE) analysis were applied, and IETD was selected according to the target rainfall period. The more samples the population had, the more IETD tended to increase. In addition, by analyzing the duration and time distribution of independent rainfall according to the IETD, a plan was proposed to calculate the standard design rainfall according to the rainwater management target amount. Therefore, it is expected that it will be possible to set an improved rainwater management target amount if sufficient samples of independent rainfall ideas are used through the selection of IETD as in this study.