• Journal of the Korean Chemical Society
• /
• 제64권6호
• /
• pp.327-333
• /
• 2020

Performance of a portable GC that can be utilized for the real time determination of volatile organic compounds in air was evaluated. It employs purified/compressed ambient air as the carrier gas eliminating the need for high pressure gas tanks. The compact system with dimensions of 35 × 26 × 15 ㎤ and weight of 5 kg is powered by either a 24 V DC external adapter or battery pack. Chromatograms of the mixture sample including benzene, toluene, ethylbenzene, and oxylene at concentrations of 1 ppmv and 20 ppmv represent a good reproducibility: 3.79% and 0.48% relative standard deviations (RSDs) for peak area variations; 0.40% and 0.08% RSDs for retention times. The method detection limit was 0.09 ppmv. A 30 m long, 0.28 mm I.D. column operated at an optimal condition yielded a peak capacity of 61 with good resolution for a 10 min isothermal analysis. The relative standard deviations (RSD) of the peak area variations and retention times during consecutive measurements over 27 h were less than 2.4%RSD and 0.5%RSD, respectively. Thus, this instrument makes it suitable for continuous and field analysis of low-concentration VOC mixtures in the indoor/outdoor environment as well as the spillage accident of hazardous chemicals.

• Journal of Korean Society of Forest Science
• /
• 제111권3호
• /
• pp.435-449
• /
• 2022

Forest canopy height is an indispensable vertical structure parameter that can be used for understanding forest biomass and carbon storage as well as for managing a sustainable forest ecosystem. Plot-based field surveys, such as the national forest inventory, have been conducted to provide estimates of the forest canopy height. However, the comprehensive nationwide field monitoring of forest canopy height has been limited by its cost, lack of spatial coverage, and the inaccessibility of some forested areas. These issues can be addressed by remote sensing technology, which has gained popularity as a means to obtain detailed 2- and 3-dimensional measurements of the structure of the canopy at multiple scales. Here, we reviewed both international and domestic studies that have used remote sensing technology approaches to estimate the forest canopy height. We categorized and examined previous approaches as: 1) LiDAR approach, 2) Stereo or SAR image-based point clouds approach, and 3) combination approach of remote sensing data. We also reviewed upscaling approaches of utilizing remote sensing data to generate a continuous map of canopy height across large areas. Finally, we provided suggestions for further advancement of the Korean forest canopy height estimation system through the use of various remote sensing technologies.

• Journal of Wetlands Research
• /
• 제24권3호
• /
• pp.155-160
• /
• 2022

The debate of South-North transboundary rivers must be expanded from the existing cooperation in water resources towards cooperation within ecosystem conservation. Regarding the Han and Imjin rivers confluence water system, the nature of the estuarine ecosystem must be conserved considering the aspect of climate change. Furthermore, the agenda of maintaining continuous inter-Korean communication and cooperation should focus on ecosystem conservation, including conserving migratory species that inhabit both Koreas. Notably, within the Han and Imjin rivers confluence, transboundary rivers are abundant legally protected species such as Grus vipio, Anser fabalis, Anser cygnoides, Platalea minor, Lutra lutra, Prionailurus bengalensis which suggests a strong need for a debate regarding habitat conservation. This study analyzed the ecosystem conditions and environmental aspects within the confluence of Han and Imjin rivers. In addition, this study provided step wise approach of ecosystem conservation that consider conditions for potential direct inter-Korean cooperation. The inter-Korean cooperation mentioned in this study will be developed into legitimate cooperation once the results from monitoring the ecosystem of transboundary rivers, awareness raising are exchanged.

• Journal of Internet Computing and Services
• /
• 제24권6호
• /
• pp.73-80
• /
• 2023

The recent steep increase in the minimum hourly wage has increased the burden of labor costs, and the share of unmanned stores is increasing in the aftermath of COVID-19. As a result, theft crimes targeting unmanned stores are also increasing, and the "Just Walk Out" system is introduced to prevent such thefts, and LiDAR sensors, weight sensors, etc. are used or manually checked through continuous CCTV monitoring. However, the more expensive sensors are used, the higher the initial cost of operating the store and the higher the cost in many ways, and CCTV verification is difficult for managers to monitor around the clock and is limited in use. In this paper, we would like to propose an AI image processing fusion algorithm that can solve these sensors or human-dependent parts and detect customers who perform abnormal behaviors such as theft at low costs that can be used in unmanned stores and provide cloud-based notifications. In addition, this paper verifies the accuracy of each algorithm based on behavior pattern data collected from unmanned stores through motion capture using mediapipe, object detection using YOLO, and fusion algorithm and proves the performance of the convergence algorithm through various scenario designs.

• Journal of Environmental Health Sciences
• /
• 제50권2호
• /
• pp.93-101
• /
• 2024

Background: As pollutants caused by non-point sources flow into rivers, river water quality monitoring for fecal pollution is becoming increasingly important. Objectives: This study was conducted to investigate the distribution of microbial communities in the Yeongsangang River water system and sewage treatment plants in Gwangju and to evaluate their antibiotic resistance. Methods: In the experiment, samples were distributed to five selective media at each point and then cultured for 18 to 24 hours. When bacteria were observed, they were sub-cultured by size and shape and identified using MALDI-TOF MS equipment. When identification was completed, 17 types of antibiotic susceptibility tests were performed using VITEK II equipment, focusing on gram-negative dominant species among the identified strains. Results: During the study period, a total of 266 strains were isolated from 39 samples. Gram-positive bacteria were 37 strains in four genera, or 13.9% of the total, and Gram-negative bacteria were 229 strains in 23 genera, or 86.1% of the total. Antibiotic susceptibility testing of 23 strains, the major dominant species, showed that one strain (4.3%) was resistant to only one antibiotic, and two strains (8.7%) were 100% susceptible to the 17 antibiotics tested. The other 20 strains (87.0%) were multidrug resistant bacteria resistant to two or more antibiotics. There were various types of multidrug resistance. Among them, penicillin and cephalosporin series showed the highest resistance. Conclusions: Based on the results of this study, it was found that the bacterial community structure changed according to regional and environmental factors, and it was judged that continuous research such as genetic analysis of antibiotic-resistant bacteria present in natural rivers is necessary.

• Journal of Food Hygiene and Safety
• /
• 제39권3호
• /
• pp.231-238
• /
• 2024

Vibrio parahaemolyticus is a major seafood-borne pathogen commonly detected in marine environments. In Korea, V. parahaemolyticus-induced foodborne illnesses account for 7.5% of bacterial pathogen-related food poisonings. Moreover, the amount of antimicrobial agents used in aquatic cultures is continuously increasing. In this study, we isolated V. parahaemolyticus from seafood samples and performed antimicrobial susceptibility tests using the microbroth dilution method. Furthermore, using whole-genome sequencing, we identified antimicrobial resistance genes, virulence genes, and sequence types (STs). We could isolate V. parahaemolyticus from 47 (59.5%) of the 79 seafood samples we purchased from retail markets in Seoul and Chungcheong provinces. Antimicrobial susceptibility tests revealed that 2 and all of the 47 isolates were ampicillin-resistant (4.3%) and susceptible to all tested antimicrobial agents (100%), respectively. The genotype analysis revealed that all isolates carried beta-lactam-, tetracycline-, and chloramphenicol-associated antimicrobial resistance genes. However, we could detect fosfomycin resistance only in one isolate. Concerning the virulence genes, we detected T3SS1 and T3SS2-associated genes in all and one isolate, respectively. However, we could not detect the tdh and trh genes. Of the 47 isolates, 17 belonged to 15 different STs, including ST 658 with 3 isolates. The rest 30 isolates were identified as 25 new STs. The results of this study support the need for operating a continuous monitoring system to prevent foodborne illnesses and the spread of antimicrobial resistance genes in V. parahaemolyticus.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• 제38권1호
• /
• pp.142-151
• /
• 2020

This study is designed to deduce an implication for an effective implementation of the Special Act for Conservation, Management and Utilization of World Heritage in Korea which was legislated in February, 2020. To draw an implication, which is regarded as highly valuable for preparing for the implementation of the act, several case studies were performed focusing on four World Natural Heritage sites in Japan, and the result is as follows. First, it is enormously crucial for the central administration agencies and the local government to have a system through which they communicate one another regularly. All the target areas in Japan consist of three national parks and a prefectural park with natural monuments, and the national forest covers a tremendously large proportion of the areas. The Japanese central agencies including Ministry of the Environment, Forestry Agency and Agency for Cultural Affairs have communication with the local government through a system named Regional Liaison Committee in order to manage the sites effectively. Also, in the case of Japan, de facto administrating agencies involving non-profit organizations and the tourism association also participate in the regular conferences to communicate. Second, a specific committee consisting of academic advisers is strongly needed. In the case of Japan, Scientific Committee provides academic grounds for the management plan established by the members of Regional Liaison Committee, and an active system which allows the members to organize consultative committees and subcommittees has been established. Scientific Committee plays an important role in preventing the local government, which tends to manage the world natural heritage in more economically profitable ways, from damaging the environment of the site. The establishment of this type of committee is thought to be extremely desirable because the World Natural Heritage requires comprehensive and sustainable management plans on the ecosystem. Third, establishment of comprehensive management plan based on continuous monitoring on the environment and detailed action plan is exceedingly needed. To sum up, it is vital to establish a management plan considering environmental aspect, and detailed guidelines, which help execute the plan both properly and effectively, are required for systematic and sustainable management.

• Journal of Bio-Environment Control
• /
• 제29권2호
• /
• pp.141-152
• /
• 2020

The rapid on-site measurement of hydroponic nutrients allows for the more efficient use of crop fertilizers. This paper reports on the development of an embedded on-site system consisting of multiple ion-selective electrodes (ISEs) for the real-time measurement of the concentrations of macronutrients in hydroponic solutions. The system included a combination of PVC ISEs for the detection of NO₃, K, and Ca ions, a cobalt-electrode for the detection of H₂PO₄, a double-junction reference electrode, a solution container, and a sampling system consisting of pumps and valves. An Arduino Due board was used to collect data and to control the volume of the sample. Prior to the measurement of each sample, a two-point normalization method was employed to adjust the sensitivity followed by an offset to minimize potential drift that might occur during continuous measurement. The predictive capabilities of the NO₃ and K ISEs based on PVC membranes were satisfactory, producing results that were in close agreement with the results of standard analyzers (R² = 0.99). Though the Ca ISE fabricated with Ca ionophore II underestimated the Ca concentration by an average of 55%, the strong linear relationship (R² > 0.84) makes it possible for the embedded system to be used in hydroponic NO₃, K, and Ca sensing. The cobalt-rod-based phosphate electrodes exhibited a relatively high error of 24.7±9.26% in the phosphate concentration range of 45 to 155 mg/L compared to standard methods due to inconsistent signal readings between replicates, illustrating the need for further research on the signal conditioning of cobalt electrodes to improve their predictive ability in hydroponic P sensing.

• The Journal of Engineering Geology
• /
• 제28권2호
• /
• pp.133-160
• /
• 2018

$CO_2$ storage is a very important technology for reduction of greenhouse gas emissions and has been considered as almost the only viable and effective option for immediate large-scale $CO_2$ sequestration. Small-scale demonstration project for offshore $CO_2$ storage in the Pohang Basin is the transitional stage R&D program for technological preparation of large-scale $CO_2$ storage project in Korea. Through the extensive exploration research for prospective $CO_2$ storage sites, the offshore strata in the Pohang Basin was recommended for the storage formation of the small-scale demonstration project. The Pohang Offshore Storage Project launched at 2013, and has accomplished the technical demonstration and technological independence in a wide range of $CO_2$ storage technology, such as geophysical exploration, storage site characterization, storage design, offshore platform construction, injection-well drilling and completion, deployment of injection facility, operation of $CO_2$ injection, and $CO_2$ monitoring. The project successfully carried out $CO_2$ test injection in early 2017, and achieved its final goal for technical development and demonstration of $CO_2$ storage in Korea. The realization of $CO_2$ injection in this project is the measurable result and has been recorded as the first success in Korea. The Pohang Offshore Storage Project has a future plan for the continuous operation of $CO_2$ injection and completion of $CO_2$ monitoring system. The project has provided in-house technical and practical expertises, which will be a solid foundation for the commercial-scale $CO_2$ storage business in Korea. Additionally, the project will help to secure national technical competitiveness in growing international technology market for $CO_2$ storage.

• Journal of Korean Tunnelling and Underground Space Association
• /
• 제24권6호
• /
• pp.451-464
• /
• 2022

The high-level nuclear waste repository is a deep geological disposal system exposed to complex environmental conditions such as high temperature, radiation, and ground-water due to handling spent nuclear fuel. Continuous exposure can lead to cracking and deterioration of the structure over time. On the other hand, the high-level nuclear waste repository requires an ultra-long life expectancy. Thus long-term structural health monitoring is essential. Various sensors such as an accelerometer, earth pressure gauge, and displacement meter can be used to monitor the health of a structure, and a piezoelectric sensor is generally used. Therefore, it is necessary to develop a highly durable sensor based on the durability assessment of the piezoelectric sensor. This study designed an accelerated life test for durability assessment and life prediction of the piezoelectric sensor. Based on the literature review, the number of accelerated stress levels for a single stress factor, and the number of samples for each level were selected. The failure mode and mechanism of the piezoelectric sensor that can occur in the environmental conditions of the high-level waste repository were analyzed. In addition, two methods were proposed to investigate the maximum harsh condition for the temperature stress factor. The reliable operating limit of the piezoelectric sensor was derived, and a reasonable accelerated stress level was set for the accelerated life test. The suggested methods contain economical and practical ideas and can be widely used in designing accelerated life tests of piezoelectric sensors.