• Geophysics and Geophysical Exploration
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• v.25 no.4
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• pp.227-241
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• 2022

Full waveform inversion (FWI) in the field of seismic data processing is an inversion technique that is used to estimate the velocity model of the subsurface for oil and gas exploration. Recently, deep learning (DL) technology has been increasingly used for seismic data processing, and its combination with FWI has attracted remarkable research efforts. For example, DL-based data processing techniques have been utilized for preprocessing input data for FWI, enabling the direct implementation of FWI through DL technology. DL-based FWI can be divided into the following methods: pure data-based, physics-based neural network, encoder-decoder, reparameterized FWI, and physics-informed neural network. In this review, we describe the theory and characteristics of the methods by systematizing them in the order of advancements. In the early days of DL-based FWI, the DL model predicted the velocity model by preparing a large training data set to adopt faithfully the basic principles of data science and apply a pure data-based prediction model. The current research trend is to supplement the shortcomings of the pure data-based approach using the loss function consisting of seismic data or physical information from the wave equation itself in deep neural networks. Based on these developments, DL-based FWI has evolved to not require a large amount of learning data, alleviating the cycle-skipping problem, which is an intrinsic limitation of FWI, and reducing computation times dramatically. The value of DL-based FWI is expected to increase continually in the processing of seismic data.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.4
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• pp.45-53
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• 2015

In this paper, an approach of temporal certification system that can be easily added on current character-based certification system is newly introduced. This technique enhances the security of the password certification process by exploiting temporal information for each character's stroke timing, and using them as another feature of certification information, on top of character comparison process. There are three different temporal conditions: maximum, minimum and no-option. The maximum condition along with a time number (usually 0.2 second or less) means that the next key input should be punched within the time limit, while the minimum condition means the next key stroke should be typed after the time lapse specified. With no-option condition chosen, user can punch the password without any timing constraints. Prototype was developed and tested with four number password case. In comparison with 104 cases, this new approach increases the cases more than 10 digits, enhancing the security of the certification process. One big advantage of this new approach is that user can update his/her password only with different timing constraints, still keeping the same characters, that will enhance the security system management efficiency in a very simple way. Figures and pictures along with process flow are included for the validity of the idea.

• The Journal of Bigdata
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• v.6 no.2
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• pp.125-137
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• 2021

The number of CCTV installed in Korea is over 1.3 million, increasing by more than 15% annually. However, due to the limited budget compared to the installation demand, the infrastructure is composed of 500,000 pixel low-quality CCTV, and there is a limits on identification of objects in the video. Public CCTV has high utility in various fields such as crime prevention, traffic information collection (control), facility management, and fire prevention. Especially, since installed in high height, it works as its role in solving diverse crime and is in increasing trend. However, the current public CCTV field is operated with potential problems such as inability to identify due to environmental factors such as fog, snow, and rain, and the low-quality of collected images due to the installation of low-quality CCTV. Therefore, in this study, in order to remove the typical low-quality elements of public CCTV, the method of attenuating scattered light in the image caused by dust, water droplets, fog, etc and algorithm application method which uses deep-learning algorithm to improve input video into videos over quality over 4K are suggested.

• Korean Journal of Environmental Agriculture
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• v.41 no.4
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• pp.230-235
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• 2022

BACKGROUND: Ammonia gas emitted from nitrogen fertilizers applied in agricultural land is an environmental pollutant that catalyzes the formation of fine particulate matter (PM2.5). A significant portion (12-18%) of nitrogen fertilizer input for crop cultivation is emitted to the atmosphere as ammonia gas, a loss form of nitrogen fertilizer in agricultural land. The widely practiced method for fertilizer use in agricultural fields involves spraying the fertilizers on the surface of farmlands and mixing those with the soils through such means as rotary work. To test the potential reduction of ammonia emission by nitrogen fertilizers from the soil surface, we have added N, P, and K at 2 g each to the glass greenhouse soil, and the ammonia emission was analyzed. METHODS AND RESULTS: The treatment consisted of non-fertilization, surface spray (conventional fertilization), and soil depth spray at 10, 15, 20, 25, and 30 cm. Ammonia was collected using a self-manufactured vertical wind tunnel chamber, and it was quantified by the indophenol-blue method. As a result of analyzing ammonia emission after fertilizer treatments by soil depth, ammonia was emitted by the surface spray treatment immediately after spraying the fertilizer in the paddy soil, with no ammonia emission occurring at a soil depth of 10 cm to 30 cm. In the upland soil, ammonia was emitted by the surface spray treatment after 2 days of treatment, and there was no ammonia emission at a soil depth of 15 cm to 30 cm. Lettuce and Chinese cabbage treated with fertilizer at depths of 20 cm and 30 cm showed increases of fresh weight and nutrient and potassium contents. CONCLUSION(S): In conclusion, rather than the current fertilization method of spraying and mixing the fertilizers on the soil surface, deep placement of the nitrogen fertilizer in the soil at 10 cm or more in paddy fields and 15 cm or more in upland fields was considered as a better fertilization method to reduce ammonia emission.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3C
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• pp.141-148
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• 2010

Electrical noises like self potential, burst noises and 60-Hz electrical noises are one of the causes to reduce reliability of electrical resistivity survey. Even the PDC-R (Pseudo DC resisitivity) technique, recently developed, is suffering from the problem of low reliability due to electrical noises. That is, both DC-based and AC-based resistivity technique is subject to reliability problem due to electrical noises embedded in urban geotechnical sites. In this research, a new technique to enhance reliability of the PDC-R technique by minimizing influence of electrical noises was proposed. In addition, an automated procedure was also proposed to facilitate data analysis and interpretation of PDC-R measurements. The proposed technique is composed of two steps: 1. to extract information only related with the input current by means of multiple-filter technique, and 2. to undertake a task to sort out signal information only to show stable and reliable characteristics. This automated procedure was verified by a synthetic harmonic wave including DC shift, burst random noises and 60-Hz electrical noises. Also the procedure was applied to site investigation at urban areas for proving its feasibility and accuracy.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.376-386
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• 2023

Due to climate changes, landslide hazards in the Republic of Korea (hereafter South Korea) continuously increase. To establish the effective landslide mitigation strategies, such as erosion control works, landslide hazard estimation in the long-term perspective should be proceeded considering the influence of climate changes. In this study, we examined the change in landslide-damaged areas in South Korea responding to climate change scenarios using the multivariate regression method. Data on landslide-damaged areas and rainfall from 1981-2010 were used as a training dataset. Sev en indices were deriv ed from rainfall data as the model's input data, corresponding to rainfall indices provided from two SSP scenarios for South Korea: SSP1-2.6 and SSP5-8.5. Prior to the multivariate regression analysis, we conducted the VIF test and the dimension analysis of regression model using PCA. Based on the result of PCA, we developed a regression model for landslide damaged area estimation with two principal components, which cov ered about 93% of total v ariance. With climate change scenarios, we simulated landslide-damaged areas in 2030-2100 using the regression model. As a result, the landslide-damaged area will be enlarged more than the double of current annual mean landslide damaged area of 1981-2010; It infers that landslide mitigation strategies should be reinforced considering the future climate condition.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.794-801
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• 2023

The high seas, covering the majority of the world's oceans, hold invaluable marine resources crucial for the growth of the marine bio-industry. The High seas bioresources program of South Korea is at the forefront of these global efforts. This study aims to gauge public awareness and quantify the project benefits, offering insights for future policy decisions. The results revealed that the estimated annual average willingness to pay (WTP) was 3,778.8 KRW, equating to approximately 81.54 billion KRW when extrapolated to the entire national population. The implications of the study are twofold: The project benefits, based on WTP, are substantial, amounting to approximately 81.5 billion KRW annually. This provides critical reference material for future policy formulation, given the considerable WTP in comparison to the current investment. Although interest in international sea marine biological resources is growing, public awareness remains relatively low. However, the project plays a crucial role in building essential databases for the marine bio-industry and securing international sea marine biological resources. Public interest and sustained support are pivotal, not only for this project but also for future policy implementation. Strategies to enhance public awareness are essential, and the study results offer valuable input for future policy decisions.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.1-13
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• 2024

The southwestern part of the East Sea is known to have a high primary productivity compared to those in the northern and eastern parts, which is attributed to nutrients supplies either by Tsushima Warm Current or by coastal upwelling. However, research on the biological pump in this area is limited. We developed machine learning models to estimate net community production (NCP), a measure of biological pump, with high spatial and time scales of 4 km and 8 days, respectively. The models were fed with the input parameters of sea surface temperature, chlorophyll-a, mixed layer depths, and photosynthetically active radiation and trained with observed NCP derived from high resolution measurements of surface O₂/Ar. The root mean square error between the predicted values by the best performing machine model and the observed NCP was 6 mmol O₂ m^-2 d^-1, corresponding to 15% of the average of observed NCP. The NCP in the central part of the Ulleung Basin was highest in March at 49 mmol O₂ m^-2 d^-1 and lowest in June and July at 18 mmol O₂ m^-2 d^-1. These seasonal variations were similar to the vertical nitrate flux based on the ³He gas exchange rate and to the particulate organic carbon flux estimated by the ²³⁴Th disequilibrium method. To expand this method, which produces NCP estimate for spring and summer, to autumn and winter, it is necessary to devise a way to correct bias in NCP by the entrainment of subsurface waters during the seasons.

• Journal of the Korean Home Economics Association
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• v.27 no.2
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• pp.163-185
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• 1989

Korean home economics education has around 100 years history. The main aims of home economics education up 1950 had not been changed, they were mainly for the improvement of household-skill to raise both standard of living and life quality as well as womanhood. After 1960's the standard of living drastically improved and the industrialization of Korean society was quite rapidly proceeded from simple to complex one. Because of these changes, I considered that the aims and the contents of home economics education should be reexamined and reshaped. This study motivated me that especially home economics major should be trained to be competent enough to work in industrialized society as much as the input to her college education. As industialization was made progress, family member's diverse role differentiation also occurred from past simple role such as house wife or girl's high school teacher among by home economics major. In this current societal change, most of the home economics major have wish to have opportunities obtaining new kinds of employment rather than obtaining merely teaching work. With this in mind I made a study on college level home economics education of the new adjustment to current and future industrialized Korean society. (1) The full number of officially admissible home economics major in 169 Korean colleges, 70 junior colleges, and one open university were as follows, 7139, 6080, and 230 respectively. The percentages of employed of employed numbers of them for the college and junior college graduates were 26.5 and 39.0 respectively. (2) The certificate qualifications issued to college home economics major are nutritionist (1st grade and 2nd grade), clothes and textilist, home economics teacher (2nd grade for high school) and kindergartener (2nd grade), The qualifications are certified after majoring each field from major departments of college of home economics by Ministrys of Labour and Education of the Korean government. The percentages of their employment are low as mentioned earlier. (3) To find out new employment opportunity for home economics graduates in home economist in business (henceforce/HEIB) status quo of consumer division for mational enterprise was surveyed. According to govermment decree of general law of consumer protection (1980), enterprise should organize bureau (offics, subdivision) on liability to consumer's complaint. Of 89.6% of the enterprise established th subdivision in which 96.2% of employee was male (3.8% was female). Of the employee college graduate and high school graduate were 93.2% and 6.8% respectively. On the employee's major acadmic backgroud (%), economics and business administration, engineering and low-political science were 39.5, 26.2 and 11.2 respectively. (4) To study on the relation between home economics and home economist in business, the aspect of historical development of HEIB, group of HEIB employing enterprise and their nature of business were tried to find out as well as perception and evaluation by enterprise on HEIB. (a) In the united States of America employed home economics major to enterprise was organized autonomously HEIB subdivision within American Home Economics Association since 1920's and the membership of HEIB was 3,000 of the AHEA membership 50,000. (b) In Japan the Japanese founder HEIB had three times the bilateral congress with the U.S.HEIB and had 10th anniversary celebration in 1988. Japanese HEIB member are not necessary to be home economics graduates but should have certificate as consumer adviser effected by the Minister of Trade and Industry. Japanese subdivision of consumer affaire within Japanese enterprise employ the consumer adviser with the certificate. Because of this different system from the United Sates, Japanese HEIB call their title "HEEB" instead of HEIB. The Japanese consumer adviser certificate system had initiated since 1980 and it belongs to 2nd level national qualification certificate. Currently active membership of Japanese "HEEB" association had increased from 115 (in 1979) to 319 in 1988. (5) For the opening of the future new employment of home economics graduates to enterprise and qualification required for the HEIB by national enterprise in Korea, I studied on the courses which seem to be important and required by employee in the field of HEEB in the United States of America and preliminary curriculum for home economics related major student aimning to be the future "HEEB" by Japanese HEEB study group of Japanese Association of Home Economics. It is suggested that it is very important and urgent to realize as home economics educator to have common deep concern and endeavors on opening new employment for our home economics major student1), we should try to publicize strongly and let enterprise and consumer protection board realize that employee in the subdivision of consumer protection should be the one who well experienced home economics major graduates2), we, home economics educator, should try to develop actively new curriculum in line of the suggestion made earlier for our future home economics major student of open broadly their future employment opportunities3), we, home economics educators, should try to have consensus on whether we should have support from government in terms of receiving national qualification certificate on consumer pretection or not4), and I would appreciate if the Korean Home Economics Association and Korean Home Management Society paydeep and positive concern on this matter.

• Progress in Medical Physics
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• v.12 no.2
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• pp.103-112
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• 2001

Purpose: The purpose of this study was to investigate the current status of performing nuclear medicine quality control in korea and to test selected protocols of quality control of nuclear medicine counting system and gamma camera. Materials and Methods: Fifty three hospitals were included to investigate the current status of nuclear medicine quality control in korea. The precision of dose calibrator and thyroid uptake system was measured with Tc-99m 35.52 MBq for 2 minuets and Tc-99m 5.14 MBq for 10 sec every one minute, respectively. The sensitivity of CeraSPECT$^{TM}$ with low energy high resolution parallel hole collimator was measured using two cylindrical phantoms with 15 cm in diameter and 12 cm and 30 cm in heights containing Tc-99m. The correction factor for sensitivity of CeraSPECT$^{TM}$ was calculated using phantom data. The system planar sensitivity, uniformity, count rate and spatial resolution were measured for Varicam gamma camera with low energy high resolution parallel hole collimator using 140 keV centered 20% energy window, 256$\times$256 or 512$\times$512 matrix sizes. Results: The quality control of dose calibrator and well counter were showed poor performance status. On the other hand, The quality control of gamma camera and other systems were showed relatively good performance status. The results of precision of dose calibrator and thyroid uptake system was $\pm$1.4%(<$\pm$5%) and chi^2=29.7(>16.92), respectively. It showed that the sensitivity of CeraSPECT$^{TM}$ was higher in center slices compared with the edge slices. After correction of nonuniform sensitivities for patient data, it showed better results compare with prior to correction. System planar sensitivity of Varicam gamma camera was 4.39 CPM/MBq. The observed count rate at 20% loss was 102,407 counts/sec (head 1), 113,427 counts/sec (head 2), when input count rate was 81,926 counts/sec (head 1), 90,741 counts/sec (head 2). The spatial resolution without scatter medium were 8.16 mm of FWHM and 14.85 mm of FWTM. The spatial resolution with scatter medium were 8.87 mm of FWHM and 18.87 mm of FWTM. Conclusion: It is necessary to understand the importance of quality control and to perform quality control of nuclear medicine devices.vices.