• Science of Emotion and Sensibility
• /
• v.22 no.1
• /
• pp.15-22
• /
• 2019

The purpose of this study is to develop a strain sensor based on a nanoweb by applying electrical conductivity to a polyurethane nanoweb through the use of Graphene. For this purpose, 1% Graphene ink was pour-coated on a polyurethane nanoweb and post-treated with PDMS (Polydimethylsiloxane) to complete a wearable strain sensor. The surface characteristics of the specimens were evaluated using a field emission scanning electron microscope (FE-SEM) to check whether the conductive material was well coated on the surface of the specimen. Electrical properties of the specimens were measured by using a multimeter to measure the linear resistance of the specimen and comparing how the line resistance changes when 5% and 10% of the specimens are tensioned, respectively. In order to evaluate the performance of the specimen, the gauge factor was obtained. The evaluation of the clothing was performed by attaching the completed strain sensor to the dummy and measuring the respiration signal according to the tension using MP150 (Biopac system Inc., USA) and Acqknowledge (ver. 4.2, Biopac system Inc., U.S.A.). As a result of the evaluation of the surface characteristics, it was confirmed that all the conductive nanoweb specimen were uniformly coated with the Graphen ink. As a result of measuring the resistance value according to the tensile strength, the specimen G, which was treated with just graphene had the lowest resistance value, the specimen G-H had the highest resistance value, and the change of the line resistance value of the specimen G and the specimen G-H is increased to 5% It is found that it increases steadily. Unlike the resistance value results, specimen G showed a higher gauge rate than specimen G-H. As a result of evaluation of the actual clothes, the strain sensor made using the specimen G-H measured the stable peak value and obtained a signal of good quality. Therefore, we confirmed that the polyurethane nanoweb treated with Graphene ink plays a role as a breathing sensor.

• Korean Chemical Engineering Research
• /
• v.60 no.1
• /
• pp.93-99
• /
• 2022

With the rapid development of ultra-small and wearable device technology, continuous electricity supply without spatiotemporal limitations for driving electronic devices is required. Accordingly, Triboelectric nanogenerator (TENG), which utilizes static electricity generated by the contact and separation of two different materials, is being used as a means of effectively harvesting various types of energy dispersed without complex processes and designs due to its simple principle. However, to apply the TENG to real life, it is necessary to increase the electrical output. In addition, stable generation of electrical output, as well as increase in electrical output, is a task to be solved for the commercialization of TENG. In this study, we proposed a method to not only improve the output of TENG but also to stably represent the improved output. This was solved by using the contact layer, which is one of the components of TENG, as an electret for improved output and stability. The utilized electret was manufactured by sequentially performing corona charging-thermal annealing-corona charging on the Fluorinated ethylene propylene (FEP) film. Electric charges artificially injected due to corona charging enter a deep trap through the thermal annealing, so an electret that minimizes charge escape was fabricated and used in TENG. The output performance of the manufactured electret was verified by measuring the voltage output of the TENG in vertical contact separation mode, and the electret treated to the corona charging showed an output voltage 12 times higher than that of the pristine FEP film. The time and humidity stability of the electret was confirmed by measuring the output voltage of the TENG after exposing the electret to a general external environment and extreme humidity environment. In addition, it was shown that it can be applied to real-life by operating the LED by applying an electret to the clap-TENG with the motif of clap.

• Korean Journal of Remote Sensing
• /
• v.38 no.5_1
• /
• pp.497-510
• /
• 2022

Agricultural reservoirs are essential structures for water supplies during dry period in the Korean peninsula, where water resources are temporally unequally distributed. For efficient water management, systematic and effective monitoring of medium-small reservoirs is required. Synthetic Aperture Radar (SAR) provides a way for continuous monitoring of those, with its capability of all-weather observation. This study aims to evaluate the applicability of SAR in monitoring medium-small reservoirs using Sentinel-1 (10 m resolution) and Capella X-SAR (1 m resolution), at Chari (CR), Galjeon (GJ), Dwitgol (DG) reservoirs located in Ulsan, Korea. Water detected results applying Z fuzzy function-based threshold (Z-thresh) and Chan-vese (CV), an object detection-based segmentation algorithm, are quantitatively evaluated using UAV-detected water boundary (UWB). Accuracy metrics from Z-thresh were 0.87, 0.89, 0.77 (at CR, GJ, DG, respectively) using Sentinel-1 and 0.78, 0.72, 0.81 using Capella, and improvements were observed when CV was applied (Sentinel-1: 0.94, 0.89, 0.84, Capella: 0.92, 0.89, 0.93). Boundaries of the waterbody detected from Capella agreed relatively well with UWB; however, false- and un-detections occurred from speckle noises, due to its high resolution. When masked with optical sensor-based supplementary images, improvements up to 13% were observed. More effective water resource management is expected to be possible with continuous monitoring of available water quantity, when more accurate and precise SAR-based water detection technique is developed.

• Journal of Korea Water Resources Association
• /
• v.56 no.9
• /
• pp.543-551
• /
• 2023

Snow is an essential climate factor that affects the climate system and surface energy balance, and it also has a crucial role in water balance by providing solid water stored during the winter for spring runoff and groundwater recharge. In this study, statistical analysis of Local Data Assimilation and Prediction System (LDAPS), Modern.-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), and ERA5-Land snow depth data were used to evaluate the applicability in South Korea. The statistical analysis between the Automated Synoptic Observing System (ASOS) ground observation data provided by the Korea Meteorological Administration (KMA) and the reanalysis data showed that LDAPS and ERA5-Land were highly correlated with a correlation coefficient of more than 0.69, but LDAPS showed a large error with an RMSE of 0.79 m. In the case of MERRA-2, the correlation coefficient was lower at 0.17 because the constant value was estimated continuously for some periods, which did not adequately simulate the increase and decrease trend between data. The statistical analysis of LDAPS and ASOS showed high and low performance in the nearby Gangwon Province, where the average snowfall is relatively high, and in the southern region, where the average snowfall is low, respectively. Finally, the error variance between the four independent snow depth data used in this study was calculated through triple collocation (TC), and a merged snow depth data was produced through weighting factors. The reanalyzed data showed the highest error variance in the order of LDAPS, MERRA-2, and ERA5-Land, and LDAPS was given a lower weighting factor due to its higher error variance. In addition, the spatial distribution of ERA5-Land snow depth data showed less variability, so the TC-merged snow depth data showed a similar spatial distribution to MERRA-2, which has a low spatial resolution. Considering the correlation, error, and uncertainty of the data, the ERA5-Land data is suitable for snow-related analysis in South Korea. In addition, it is expected that LDAPS data, which is highly correlated with other data but tends to be overestimated, can be actively utilized for high-resolution representation of regional and climatic diversity if appropriate corrections are performed.

• Journal of the Korean Applied Science and Technology
• /
• v.40 no.3
• /
• pp.534-546
• /
• 2023

In this study, we investigated the antioxidant and anti-winkle activity in human fibroblast cell (CCD-986sk) of Persimmon Leaves (PL) as a cosmetic ingredient. As a result of investigating antioxidant activity through electron-donating ability and ABTS⁺ radical scavenging assay, the PL showed concentration-dependent antioxidant activity similar to ascorbic acid, a control group, at a concentration of 1,000 ㎍/ml. As a result of investigating the anti-wrinkle effect through elastase inhibition and collagenase inhibition assay, the PL showed concentration-dependent antioxidant activity similar to epigallocatechin gallate, a control group, at a concentration of 1,000 ㎍/ml. As a result of measuring the synthesis rate of pro-collagen type I and the inhibition rate of MMP-1 in UVB-induced CCD-986sk cells, the control group EGCG showed a 90.2% pro-collagen synthesis rate at 20 ㎍/ml and PL showed an 88.5% synthesis rate at 30 ㎍/ml. In addition, the inhibition rate of MMP-1 of 33.0% and 40.8% were confirmed in EGCG 20 ㎍/ml and PL 30 ㎍/ml, respectively. As a result of measuring the protein expression of pro-collagen type I and MMP-1 in the PL through western blot, it was confirmed that the protein expression of pro-collagen type I increased, and MMP-1 decreased when the PL was treated together compared to the UVB alone group. According to the above experimental results, it is expected to be used as a natural product material for cosmetics by confirming that the PL prevent photoaging caused by UVB stimulation and have antioxidant and anti-wrinkle effects.

• Journal of Cadastre & Land InformatiX
• /
• v.52 no.2
• /
• pp.53-65
• /
• 2022

According to the advancement of the GNSS satellite positioning system, the module of hardware and operation software reflecting accuracy and economical efficiency is implemented in the user sector including the multi-channel GNSS receiver, the multi-frequency external antenna and the mobile app (App) base public positioning analysis software etc., and the multichannel GNSS RTK positioning of the active configuration method (DIY, Do it yourself) is possible according to the purpose of user. Especially, as the infrastructure of multi-GNSS satellite is expanded and the potential of expansion of utilization according to various modules is highlighted, interest in the utilization of multi-channel low-cost GNSS receiver module is gradually increasing. The purpose of this study is to review the multi-channel low-cost GNSS receivers that are appearing in the mass market in various forms and to analyze the utilization plan of the "address information facility investigation project" of the Ministry of Public Administration and Security by constructing the multi-channel low-cost GNSS positioning module based RTK survey system (hereinafter referred to as "multi-channel GNSS RTK module positioning system"). For this purpose, we constructed a low-cost "multi-channel GNSS RTK module positioning system" by combining related modules such as U-blox's F9P chipset, antenna, Ntrip transmission of GNSS observation data and RTK positioning analysis app through smartphone. Kinematic positioning was performed for circular trajectories, and static positioning was performed for address information facilities. The results of comparative analysis with the Static positioning performance of the geodetic receivers were obtained with 5 fixed points in the experimental site, and the good static surveying performance was obtained with the standard deviation of average ±1.2cm. In addition, the results of the test point for the outline of the circular structure in the orthogonal image composed of the drone image analysis and the Kinematic positioning trajectory of the low cost RTK GNSS receiver showed that the trajectory was very close to the standard deviation of average ±2.5cm. Especially, as a result of applying it to address information facilities, it was possible to verify the utility of spatial information construction at low cost compared to expensive commercial geodetic receivers, so it is expected that various utilization of "multi-channel GNSS RTK module positioning system"

• Journal of Korea Water Resources Association
• /
• v.56 no.11
• /
• pp.785-799
• /
• 2023

In this study, we proposed a new concept termed the Secondary Peak Constant (SPC) and discerned the temporal characteristics of independent rainstorm events based on unit time and SPC about 24 observation stations in Seoul. Utilizing rainfall observations from 2000 to 2022, independent rainstorm events discreted from rainfall data per unit time. The temporal characteristics of these events were derived according to unit time, and temporal characteristics of the peak rainfall were identified through the SPC. Finally, the temporal characteristics of independent rainstorm events were examined distinctively when analyzed by unit time and SPC. Independent rainstorm events with smaller unit time showed significantly larger total rainfall, rainfall duration, and rainfall intensity. The temporal characteristics of the largest peak rainfall (1^st Peak) within independent rainstorm events followed a sequence of Q4>Q2>Q3>Q1. Additionally, the 2^nd Peak rainfall predominantly occurred the location where the 1^st Peak appeared. The proportion of independent rainstorm events with multiple peak rainfalls exceeded 50.0% when the SPC was 0.7 or lower. The average number of peak rainfalls within independent rainstorm events ranged from 1.5 to 3.4. This study identified the temporal characteristics of independent rainstorm events based on unit time. Then, the peak rainfall of temporal characteristics was quantified by SPC on this study. Hence, it is evident that the temporal characteristics of independent rainstorm events for specific area can be anlayzed and quantified based on unit time and SPC.

• Journal of the Daesoon Academy of Sciences
• /
• v.48
• /
• pp.269-303
• /
• 2024

Donghak's teaching, In-nae-cheon, means "humans are divine." It is said, "When humans were formed, God's blessing was required for their formation." Donghak's Sincerity, Respectfulness, and Faithfulness is based on believing in God, respecting God, and practicing His teachings with utmost sincerity. These are key to implementing In-nae-cheon. On the other hand, the Three Essential Attitudes in Daesoon Thought, also Sincerity, Respectfulness, and Faithfulness, appear in a religious sense. These can be distinguished from Sincerity, Respectfulness, and Faithfulness in the Donghak moral sense. Sincerity, Respectfulness, and Faithfulness in the context of the Three Essential Attitudes in Daesoon Thought goes beyond moral awareness, and calls for belief in God as the Absolute. Accordingly, Sincerity, Respectfulness, and Faithfulness in this context, that of Daesoon Thought, aims at the realization of an Earthly Paradise wherein God's will can be achieved. Humans participating in the construction of Earthly Paradise value the practice of Sincerity, Respectfulness, and Faithfulness. In Daesoon Thought, it is said that when one exerts sincerity, respect, and faith in God (Sangje), all the blessings and fortune of the Later World, even those of longevity, will be endowed through transformation via effortless action (無爲而化). Accordingly, Sincerity, Respectfulness, and Faithfulness in the context of the Three Essential Attitudes in Daesoon Thought is based on God's descent into the world and His Reordering Works of Heaven and Earth (天地公事). This is a religious faith that worships Sangje and is based on the doctrinal dimension of 'guarding against self-deception (毋自欺)' and the philosophical dimension of Sincerity, Respectfulness, and Faithfulness in the context of the Three Essential Attitudes in Daesoon Thought. Donghak's In-nae-cheon and the Three Essential Attitudes in Daesoon Thought can be compared and analyzed. Therefore, in order to clearly compare and analyze the moral significance of Donghak history and the religious meaning of Daesoon Thought, Roderick Ninian Smart's method of religious phenomenology can be actively used. In this way, the ethical and legal dimensions of Donghak's In-nae-cheon and the doctrinal and philosophical dimensions of the Three Essential Attitudes in Daesoon Thought can be compared and analyzed. From this style of research, it can be concluded that the realization of commonly shared spirituality can be an opportunity for greater human dignity.

• Journal of Wetlands Research
• /
• v.26 no.2
• /
• pp.168-181
• /
• 2024

Constructed wetlands (CWs) deliver a range of ecosystem services, including the removal of contaminants, sequestration and storage of carbon, and enhancement of biodiversity. These services are facilitated through hydrological and ecological processes such as infiltration, adsorption, water retention, and evapotranspiration by plants and microorganisms. This study investigated the correlations between microbial populations, soil physicochemical properties, and treatment efficiency in a horizontal subsurface flow constructed wetland (HSSF CW) treating runoff from roads and parking lots. The methods employed included storm event monitoring, water quality analysis, soil sampling, soil quality parameter analysis, and microbial analysis. The facility achieved its highest pollutant removal efficiencies during the warm season (>15℃), with rates ranging from 33% to 74% for TSS, COD, TN, TP, and specific heavy metals including Fe, Zn, and Cd. Meanwhile, the highest removal efficiency was 35% for TOC during the cold season (≤15℃). These high removal rates can be attributed to sedimentation, adsorption, precipitation, plant uptake, and microbial transformations within the CW. Soil analysis revealed that the soil from HSSF CW had a soil organic carbon content 3.3 times higher than that of soil collected from a nearby landscape. Stoichiometric ratios of carbon (C), nitrogen (N), and phosphorus (P) in the inflow and outflow were recorded as C:N:P of 120:1.5:1 and 135.2:0.4:1, respectively, indicating an extremely low proportion of N and P compared to C, which may challenge microbial remediation efficiency. Additionally, microbial analyses indicated that the warm season was more conducive to microorganism growth, with higher abundance, richness, diversity, homogeneity, and evenness of the microbial community, as manifested in the biodiversity indices, compared to the cold season. Pollutants in stormwater runoff entering the HSSF CW fostered microbial growth, particularly for dominant phyla such as Proteobacteria, Actinobacteria, Acidobacteria, and Bacteroidetes, which have shown moderate to strong correlations with specific soil properties and changes in influent-effluent concentrations of water quality parameters.

• Journal of Bio-Environment Control
• /
• v.32 no.4
• /
• pp.416-422
• /
• 2023

This study was aimed to determine the changes in CO₂ concentration according to the temperatures of daytime and nighttime in the CO₂ supplemental greenhouse, and to compare calculated supplementary CO₂ concentration during winter and spring cultivation seasons. CO₂ concentrations in experimental greenhouses were analyzed by selecting representative days with different average temperatures due to differences in integrated solar radiation at the growth stage of leaf area index (LAI) 2.0 during the winter season of 2022 and 2023 years. The CO₂ concentration was 459, 299, 275, and 239 µmol·mol^-1, respectively at 1, 2, 3, and 4 p.m. after the CO₂ supplementary time (10:00-13:00) under the higher temperature (HT, > 18℃ daytime temp. avg. 31.7, 26.8, 23.8, and 22.4℃, respectively), while it was 500, 368, 366, 364 µmol·mol^-1, respectively under the lower temperature (LT, < 18℃ daytime temp. avg. 22.0, 18.9, 15.0, and 13.7℃, respectively), indicating the CO₂ reduction was significantly higher in the HT than that of LT. During the nighttime, the concentration of CO₂ gradually increased from 6 p.m. (346 µmol·mol^-1) to 3 a.m. (454 µmol·mol^-1) in the HT with a rate of 11 µmol·mol^-1 per hour (240 tomatoes, leaf area 330m²), while the increase was very lesser under the LT. During the spring season, the CO₂ concentration measured just before the start of CO₂ fertilization (7:30 a.m.) in the CO₂ enrichment greenhouse was 3-4 times higher in the HT (>15℃ nighttime temperature avg.) than that of LT (< 15℃ nighttime temperature avg.), and the calculated amount of CO₂ fertilization on the day was also lower in HT. All the integrated results indicate that CO₂ concentrations during the nighttime varies depending on the temperature, and the increased CO₂ is a major source of CO₂ for photosynthesis after sunrise, and it is necessary to develop a model formula for CO₂ supplement considering the nighttime CO₂ concentration.