• Journal of Korea Water Resources Association
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• 제55권4호
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• pp.301-308
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• 2022

Algae is an indispensable primary producer in the ecosystem by supplying energy to consumers in the aquatic ecosystem, and is largely divided into green algae, blue-green algae, and diatoms. In the case of blue-green algae, the water temperature rises, which occurs in the summer and overgrows, which is the main cause of the algae bloom. Recently, the change in the occurrence time and frequency of the algae bloom is increasing due to climate change. Existing algae survey methods are performed by collecting water and measuring through sensors, and time, cost and manpower are limited. In order to overcome the limitations of these existing monitoring methods, research has been conducted to perform remote monitoring using spectroscopic devices such as multispectral and hyperspectral using satellite image, UAV, etc. In this study, we tried to confirm the possibility of species classification of remote monitoring through laboratory-scale experiments through algal culture and river water collection. In order to acquire hyperspectral images, a hyperspectral sensor capable of analyzing at 400-1000 nm was used. In order to extract the spectral characteristics of the collected river water for classification of algae species, filtration was performed using a GF/C filter to prepare a sample and images were collected. Radiation correction and base removal of the collected images were performed, and spectral information for each sample was extracted and analyzed through the process of extracting spectral information of algae to identify and compare and analyze the spectral characteristics of algae, and remote sensing based on hyperspectral images in rivers and lakes. We tried to review the applicability of monitoring.

• Korean Journal of Environmental Agriculture
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• 제38권4호
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• pp.338-351
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• 2019

BACKGROUND: To investigate distribution and seasonal variation of concentration and flux of pesticides in Han river basin, water samples were examined at 24 sites in 2012 and 2014. METHODS AND RESULTS: Water samples were collected four times per year and subjected to liquid-liquid partition extraction followed by GC-ECD/NPD analysis. Of fifteen pesticides detected, iprobenfos, diazinon, isoprothiolane, endosulfan sulfate and oxadiazon were detected in a higher frequency, while fenoxanil, carbofuran, fenitrothion, butachlor and metolachlor were only detected in a sample. Pesticides with high occurrences, iprobenfos, diazinon, isoprothiolane, endosulfan sulfate and oxadiazon were detected in residue level of 0.01-0.46, 0.01-0.24, 0.03-0.85, 0.02-0.06 and 0.05-0.24 ㎍/L, respectively. Carbofuran and acetanilide herbicides were found at lower frequencies, but their concentrations were one order of magnitude higher than those of the others. CONCLUSION: Discharge of pesticides in downstream area were mainly contributed from rice farming and suburban horticulture, while pesticide occurrences in upstream area, such as Donggang river basin were caused by highland agriculture for cabbage and potato production. Despite the influx of pesticides from tributaries through intensive agriculture areas, pesticide concentration in the main stream water was low due to the dilution effect from the upstream. Therefore, the water quality was considered to be good at the most downstream, the effluent of Paldang dam.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제31권6_1호
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• pp.471-481
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• 2013

Recently, the frequency of debris flow disaster has increased, which is one of the natural disasters during extremely heavy rainfall condition. This paper described the analysis method about deposition characteristics of debris flow using topographic characteristics of debris flow path. First, we observed topographic changes by differencing high- resolution LiDAR DEMs acquired before and after the occurrence of debris flow event. We assumed that deposition on outside of debris flow path was generated by movements due to the inertia of debris flows. Then, we analyzed three topographic characteristics of debris flow path: slope in flow direction, transition angle of flow path, and the net efficiency(L/H) of debris flows defined by the ratio of transport length(L) and elevation difference(H). We applied this method to Umyeon Mountain debris flow event in July 2011. The results showed that deposition on outside of debris flow path due to the inertia of debris flows was significantly related to the transition angle of debris flow path. Also, we figured out that there were more frequent such depositions in locations where the ratio of 'transition angle / (L/H)' is over 8.

• The Journal of Korean Society for School & Community Health Education
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• 제13권2호
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• pp.93-105
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• 2012

This study aimed to provide the fundamental resources for developing an effective safety education program. We analyzed the condition of school accidents and safety awareness, and the condition of school safety education and the factors related to safety education. Ultimately, this study can lead the following studies to develop the safety education program realistically, which can effectively change the safety behaviors of Korean students. Methods: We carried out a questionnaire survey that was targeted at the schools - three elementary, three middle, and three high schools - located in Chung-nam, from April 1, 2012 to May 2, 2012. Totally, the questionnaires of 578 students were fully filled out. The design of this study is a descriptive research. Results: 1. 64.5% of elementary school students, 33% of middle school students and 32% of high school students had experienced more than one safety accident. The frequency of occurrence was the highest in playgrounds for elementary and middle school students, and in stairs for high school students. The most safety accidents occurred during lunch time and at recess in elementary and middle school, and at recess in high school. Further, most of the students who had experienced the safety accidents had been treated in infirmary (school nurse's office) for elementary school students, and in a hospital for middle and high school students. 2. There was statistical significance in the safety consciousness for students in elementary school (18.09 points), middle school (17.68 points), and high school (17.26 points), on a twenty-point scale. (F=3.754, p=0.024). 3. Comparing the factors related to school safety education with safety consciousness, students in elementary school that gave an answer of the usefulness of safety education showed a high standard in the safety consciousness level. (F=12.347, p=0.002) For the need of safety education, the students in the elementary school and high school that expressed the necessity of safety education showed a high standard in the safety consciousness level. Conclusions: Accordingly, it is true that there are the differences at safety awareness among elementary middle high school students. This study is meaningful enough in that it provides the fundamental resources for developing the effective safety education methods for the subjects.

• Ecology and Resilient Infrastructure
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• 제7권3호
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• pp.145-159
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• 2020

Wetlands are vulnerable to biological invasion by alien species, because they function as sinks that accumulate excess water, sediments, nutrients, and other contaminants from the surrounding watersheds by disturbance. In this study, to understand the status and characteristics of the alien plants based on the type of wetlands, we classified 24 ecologically outstanding wetlands and analyzed the status of alien flora. A total of 130 alien plants were found in the wetlands, accounting for 11% of the total plant species. Among them, the Asteraceae species was the most diverse, with 40 species. Erigeron annuus and Oenothera ordorata had the highest frequency of occurrence. The species richness of alien plants in the riverine and lacustrine wetlands (average: 30 species) was higher than that in the mountainous palustrine wetlands (average: 10 species). The same results were found in the naturalization index, urbanization index, and ratio of annuals and biennials, which indicate the degree of artificial interference. In the cluster analysis, the riverine and lacustrine wetlands were combined, and only the mountainous palustrine wetlands were separated. The number of alien plants is remarkably low in the mountainous palustrine wetlands, and it is considered to be the influence of Erigeron strigosus, Symphytum officinale, and Bilderdykia convolvulus, not found in the other types of wetlands. In particular, invasive alien plants such as Aster pilosus, Ambrosia trifida, Sicyos angulatus, Ambrosia artemisiifolia var. elatior were found intensively in the riverine wetlands. Therefore, it is considered that a methodical management is urgently required considering the dispersal of alien plants in the riverine and lacustrine wetlands with high artificial interference.

• Journal of the Korean BIBLIA Society for library and Information Science
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• 제30권3호
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• pp.93-110
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• 2019

This study surveyed 129 librarians of public libraries in the northwestern region of Seoul to identify harmful factors under the assumption that the work and environmental factors of them would burden their musculoskeletal system and influence their work satisfaction. The results of this study showed that the musculoskeletal symptoms in the shoulder, one of the general items, were more frequently observed in women than in men. Secondly, the musculoskeletal symptoms in the arms and elbows, one of the working environment characteristics, were most frequently reported when they worked more than one year and less than three years. The musculoskeletal symptoms in the waist were influenced by the operation method; the librarians of public libraries entrusted to the Office of Education or a local government showed symptoms more frequently. The musculoskeletal symptoms in the neck were affected by working hours; librarians working in the day shift showed neck symptoms more frequently than those working in the night shift. Thirdly, when the characteristics of the work environment were examined, the musculoskeletal symptoms in the hands, wrists, and fingers were highly frequent under all characteristics of the work environment, the musculoskeletal symptoms in the waist were highly frequent under all characteristics of the work environment except for work satisfaction, and the musculoskeletal symptoms in the legs and feet were highly frequent according to the proficiency, work intensity, and physical burden. Fourthly, this study evaluated the differences in musculoskeletal symptoms according to the work satisfaction of individuals. The results revealed that the occurrence frequency of musculoskeletal symptoms for all body parts decreased as work satisfaction increased. Therefore, it will be necessary for the main body of public library operation to improve the work and working environments and enhance the work satisfaction of individuals by reducing the physical burden of the librarian of public libraries through adjusting the work intensity in order for the health of the librarian of public libraries.

• Therapeutic Science for Rehabilitation
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• 제11권2호
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• pp.25-37
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• 2022

Objective : Through the bibliographic analysis method, the flow of research is grasped from a macroscopic point of view and the connection system of key words is conducted. The purpose of this is to provide basic data for conducting research on aging anxiety and lifestyle. Methods : Among the bibliographic analysis methods, a citation analysis method that identifies the association based on the number of citations and a simultaneous appearance word analysis method that identifies the association based on the number of keywords appeared was used. VOSviewer was used to cluster and chart the analyzed information. Results : The frequency of occurrence of papers by year showed a gradual increase until 2017 and a rapid increase from 2018. In the field of research paper study, research was most actively conducted in the field of psychiatry. In the citation analysis, the United States, Australia, and the United Kingdom showed high correlation with each other, and as a result of conducting simultaneous word analysis on major keywords, words with high association with aging anxiety were found to be depression. Conclusion : This study is meaningful in that it grasped the flow of aging anxiety and lifestyle research from a macroscopic point of view using a bibliographic analysis method. Based on this, it is expected to understand the importance of lifestyle from the preventive point of view of aging and to be used as basic data for intervention and related education.

• The Journal of Engineering Geology
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• 제7권2호
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• pp.113-126
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• 1997

Electrical resistivity methods of dipole - dipole array profiling and Schiumberger array sounding were tested on a segment of the Woraksan granitic batholith for the research into the imaging of irregular attitudes of fracture zones in the crystaaline rock in terms of processing and interpretation schemes. By the dipole - dipole array method, inhomogeneities such as small scale of fracture zones were properly delineated down at some depth even within hard rock environment. Fracture zones were interpreted to be at the boundaries between the high amplitude zone and very low amplitude zone in the resistivity plot and they were also successfully outlined in two - dimensional layer and pseudo - three - dimensional volume constructed by the incorporation of vertical sounding data. The surface location of the fracture zones was correlated by the zero - crossing point in the VLF(very low frequency) electromagnetic data. Pseudo - three - dimensional attitudes of fracture zones were efficiently illuminated by optimum projection angle. The mean of bulk resistivity for the Woraksan granite and the near fracture zones is estimated to be approximately of 4,000 ohm - m which is much higher than the value of 700 ohm - m for the Rwachunri limesilicate environment. This difference is due to both the rock type, i.e., biotite granite vs limesilicate, and the occurrence of secondary openings of fold and fault associated with the intrusion of granite. In this study statistical analyses on the resistivity color plot were performed in terms of three representative statistical moments, i.e., standard deviation, skewness, and kurtosis. The fracture zones in the standard deviation plot were characterized by the higher value, compared to the value of homogeneous portion. The upper boundary of the high resistivity zone was also successfully delineated in the skewness and kurtosis plots.

• Journal of the Institute of Electronics Engineers of Korea SC
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• 제42권3호
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• pp.47-52
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• 2005

Obstructive Sleep Apnea (OSA) is a representative symptom of sleep disorder caused by the obstruction of upper airway. Because OSA causes not only excessive daytime sleepiness and fatigue, hypertension and arrhythmia but also cardiac arrest and sudden death during sleep in the severe case, it is very important to detect the occurrence and the frequency of OSA. OSA is usually diagnosed through the laboratory-based Polysomnography (PSG) which is uncomfortable and expensive. Therefore researches to improve the disadvantages of PSG are needed and studies for the detection of OSA using only one or two parameters are being made as alternatives to PSG. In this paper, we developed an algorithm for the detection of OSA based on Heart Rate Variability (HRV). The proposed method is applied to the ECG data sets provided from PhysioNet which consist of learning set and training set. We extracted features for the detection of OSA such as average and standard deviation of 1 minute R-R interval, power spectrum of R-R interval and S-peak amplitude from data sets. These features are applied to the input of neural network. As a result, we obtained sensitivity of $89.66\%$ and specificity of $95.25\%$. It shows that the features suggested in this study are useful to detect OSA.

• Journal of the Korea Safety Management & Science
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• 제22권3호
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• pp.23-29
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• 2020

As the duty to report and investigate major elevator failures has expanded due to the total amendment of the Elevator Safety Management Act in 2018, more important information on major elevator failures that have been partially identified has been collected. As of 2019, the number of elevators in Korea exceeded 700,000, making it the eighth-class elevator powerhouse in the world, but there is a trend of increasing casualties due to accidents and breakdowns. An Seung-gang-gi is a term that encompasses an elevator that moves vertically and an escalator that moves horizontally. It is an important means of transportation for most citizens that are encountered almost every day in daily life, and it is also necessary as a means of transportation that enables the construction of skyscrapers. And it seems that its importance will never diminish in the future. Major elevator failures are the main cause of dispatch when accumulating the number of 119 dispatches, and the frequency of occurrence is high. It's a shame. According to Heinrich's Law, 300 minor signs and danger phenomena precede, 29 minor accidents and 1 major accident. Accidents caused by elevators are increasing every year due to the increase in the number of installations, and the damage is threatening the valuable lives and property of users and workers in related fields due to fatal risks such as death and serious injury. Elevator safety management can achieve its purpose only when it is managed with the usual interests, awareness of safety, and full efforts of the users, workers, and the government concerned. This study was analyzed based on 2019 data notified to the Korea Elevator Safety Agency on major breakdowns improved after the revision of the Elevator Safety Management Act in 2018, and a total of 8,256 data were analyzed using the SPSS 21 version, a statistical analysis tool, to analyze the correlation with technical statistics. Proceeded. Through the analysis, it was possible to obtain preventive safety management data to prevent serious elevator safety accidents from occurring, and to derive meaningful implications that related safety management and maintenance can be effectively operated to prevent serious failures. In addition, through this analysis, we expect the development of related industries and legal and institutional improvement.