• Journal of Korean Society of Disaster and Security
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• v.12 no.3
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• pp.35-49
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• 2019

Currently in 2018, Korea has over 600 operating sewage disposal facilities. The law requires a sewage treatment plant to treat 500 tons or more of water per day, and a small-decentralized sewage treatment facility in a community to treat 50 tons or more to less than 500 tons of water per day. However, most facilities fulfill neither the quantity nor the quality requirements from the original design for such reasons as inflow of rainwater and ground water due to deterioration of pipelines and unauthorized input of wastewater in the pipelines. The research has selected 2 representative cases among the technical diagnosif sewage pipelines in many regions within the country to use it as the baseline of: hourly flowrate and BOD water quality analysis in both clear and rainy days, proper plant operation through inflow rate and ratio calculation, and diagnostic evaluation for deterioration of the pipelines and their accessary structures. This also suggests facilities that treats 500 tons or more of inflow per day to sample and analyze the water hourly for 24 hours once a week in both clear weather and rainy weather considering the influence of rainfall on a regular basis.

• Journal of Astronomy and Space Sciences
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• v.28 no.2
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• pp.123-132
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• 2011

It is generally believed that the occurrence of a magnetic storm depends upon the solar wind conditions, particularly the southward interplanetary magnetic field (IMF) component. To understand the relationship between solar wind parameters and magnetic storms, variations in magnetic field polarity and solar wind parameters during magnetic storms are examined. A total of 156 storms during the period of 1997~2003 are used. According to the interplanetary driver, magnetic storms are divided into three types, which are coronal mass ejection (CME)-driven storms, co-rotating interaction region (CIR)-driven storms, and complicated type storms. Complicated types were not included in this study. For this purpose, the manner in which the direction change of IMF $B_y$ and $B_z$ components (in geocentric solar magnetospheric coordinate system coordinate) during the main phase is related with the development of the storm is examined. The time-integrated solar wind parameters are compared with the time-integrated disturbance storm time (Dst) index during the main phase of each magnetic storm. The time lag with the storm size is also investigated. Some results are worth noting: CME-driven storms, under steady conditions of $B_z$ < 0, represent more than half of the storms in number. That is, it is found that the average number of storms for negative sign of IMF $B_z$ (T1~T4) is high, at 56.4%, 53.0%, and 63.7% in each storm category, respectively. However, for the CIR-driven storms, the percentage of moderate storms is only 29.2%, while the number of intense storms is more than half (60.0%) under the $B_z$ < 0 condition. It is found that the correlation is highest between the time-integrated IMF $B_z$ and the time-integrated Dst index for the CME-driven storms. On the other hand, for the CIR-driven storms, a high correlation is found, with the correlation coefficient being 0.93, between time-integrated Dst index and time-integrated solar wind speed, while a low correlation, 0.51, is found between timeintegrated $B_z$ and time-integrated Dst index. The relationship between storm size and time lag in terms of hours from $B_z$ minimum to Dst minimum values is investigated. For the CME-driven storms, time lag of 26% of moderate storms is one hour, whereas time lag of 33% of moderate storms is two hours for the CIR-driven storms. The average values of solar wind parameters for the CME and CIR-driven storms are also examined. The average values of ${\mid}Dst_{min}{\mid}$ and ${\mid}B_{zmin}{\mid}$ for the CME-driven storms are higher than those of CIR-driven storms, while the average value of temperature is lower.

• The Journal of Society for e-Business Studies
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• v.23 no.2
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• pp.83-96
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• 2018

Extracting keywords representing documents is very important because it can be used for automated services such as document search, classification, recommendation system as well as quickly transmitting document information. However, when extracting keywords based on the frequency of words appearing in a web site documents and graph algorithms based on the co-occurrence of words, the problem of containing various words that are not related to the topic potentially in the web page structure, There is a difficulty in extracting the semantic keyword due to the limit of the performance of the Korean tokenizer. In this paper, we propose a method to select candidate keywords based on semantic similarity, and solve the problem that semantic keyword can not be extracted and the accuracy of Korean tokenizer analysis is poor. Finally, we use the technique of extracting final semantic keywords through filtering process to remove inconsistent keywords. Experimental results through real web pages of small business show that the performance of the proposed method is improved by 34.52% over the statistical similarity based keyword selection technique. Therefore, it is confirmed that the performance of extracting keywords from documents is improved by considering semantic similarity between words and removing inconsistent keywords.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.10-17
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• 2015

This study was conducted to investigate the occurrence of weed flora in pastures in Jeju island of Korea and to establish the basic data for controlling them occurred in the pastures. Weed flora was investigated twice, May and July on 2003. There were a total of 207 weed species including 49 families. Among them 67 species were annual, 39 species were biennial and 101 species were perennial. The compositions of major plant families, Asteraceae, Poaceae, Polygonaceae, Rosaceae, Fabaceae were 17, 15, 8, 7, 6%, respectively. Sixty-eight species of exotics were occurred, as well. Rumex obtusifolius was the highest in importance analysis and the followings were in order of Trifolium repens, Artemisia princeps, Plantago asiatica, Potentilla anemonefolia and Rumex acetosella etc. Among the exotic weeds, R. obtusifolius, T. repens, R. acetosella and C. holosteoides var. hallaisanense might be most problematic weeds species in pastures in Jeju island in the future. And at the boundary of some pastures and mountains Smilax china, Duchesnea indica, Rosa maximowicziana, etc. 17 shrub species were also occurred.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.4
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• pp.22-30
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• 2001

In this paper we propose three classification algorithms to classify breast tumors that occur in duct into Benign, DCIS(ductal carcinoma in situ) NOS(invasive ductal carcinoma) The general approach for a creating classifier is composed of 2 steps: feature extraction and classification Above all feature extraction for a good classifier is very significance, because the classification performance depends on the extracted features, Therefore in the feature extraction step, we extracted morphology features describing the size of nuclei and texture features The internal structures of the tumor are reflected from wavelet transformed images with 10$\times$ and 40$\times$ magnification. Pariticulary to find the correlation between correct classification rates and wavelet depths we applied 1, 2, 3 and 4-level wavelet transforms to the images and extracted texture feature from the transformed images The morphology features used are area, perimeter, width of X axis width of Y axis and circularity The texture features used are entropy energy contrast and homogeneity. In the classification step, we created three classifiers from each of extracted features using discriminant analysis The first classifier was made by morphology features. The second and the third classifiers were made by texture features of wavelet transformed images with 10$\times$ and 40$\times$ magnification. Finally we analyzed and compared the correct classification rate of the three classifiers. In this study, we found that the best classifier was made by texture features of 3-level wavelet transformed images.

• Asia pacific journal of information systems
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• v.23 no.2
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• pp.41-66
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• 2013

IS outsourcing has an important meaning to the Korean SME's (Small and Medium Enterprises) which want to use the IS Services. The objective of this research is to manage IT risks occurred during IS outsourcing project process. This study tries to identify these risks using real option methodology. In order to perform this objective, this study set up the research model which is composed of two main concepts. The first one is the risk factors occurred during IS outsourcing project process: User's Risks, Supplier's Risks and Transaction's Risks. All of these risks are based on Transaction Cost Theory. The second one is the intention to get (or buy) Real Options to manage the risks. In the research model, two types of real option are included: option to abandon (put option) and option to defer (call option). This study uses questionnaires and statistics methodology (PLS) to analyze the hypotheses proposed in the research model. Compared with prior studies, this study is different in two ways. First, this study restricts the range of IT risks. Prior researches of IT Risk management in MIS area cover various range of IT risks, but this study focuses on the Korean SME's IT outsourcing risks on the basis of Transaction Cost Theory. This study tests the relationship between the risks and real option types. Second, this study tries to test the moderating effect of user's risks and supplier's risks on the relationship between transaction's risks and real option types. In IT outsourcing research area, almost studies focus on the direct relationships between IT risks and outsourcing success. But in reality, the co-relationship among IT risks may occur. There are some findings according to the research analysis. First, risks related with user's risks have strong causal relationships with the intention to get option to abandon (put) and option to defer. But risks related with supplier's risks have causal relationships only with option to abandon (put). Second, user's risks and supplier's risks have no moderating effect on the relationship between transaction's risks and real option types. According to the research results, this research have some important and interesting implications on the IS outsourcing business area. First, this study identifies the effective types of real option to minimize the risks occurred during the IT outsourcing projects. So IS outsourcing service users can manage (or minimize) effectively the risks, which occurred during outsourcing projects, using real options. Second, real option gives benefits to suppliers and users at the same time (i.e., win-win strategies between IS outsourcing service providers and users). Vendors (:IS outsourcing service providers) can offer users the real options which can minimize the occurrence of risks in time. "IN TIME" means that before the IS outsourcing project starts, vendors can offer users the opportunity to buy real options in appropriate prices to manage the possibility of the risks of IS outsourcing project. And users also have chance to minimize the IT outsourcing risks occurred during the project process using real options.

• Journal of dental hygiene science
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• v.12 no.6
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• pp.583-590
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• 2012

The purpose of this study was to investigate effect of the economic stress and state-trait anxiety on the periodontal disease in order to prevent the occurrence and progression of periodontal disease. Date were collected from total of 326 subjects in their forties and fifties by using questionnaire and examination of periodontal states during the period from February to November 2011. Results were analyzed by using frequency, t-test, ANOVA and Multiple regression of SPSS ver. 19.0. 1. The economic stress were significant statistically to the higher, medium and low of gingival index (p<0.01). 2. The state-trait anxiety were significant statistically to the higher, medium and low of gingival index (p<0.001), of the pocket depth (p<0.05), of the clinical attachment loss (p<0.05). 3. The gingival index were investigate effect of the higher the economic stress ($\beta$=0.052, p<0.01), the higher the state-trait anxiety ($\beta$=0.052, p<0.01). As a result, this study suggests that the dental clinic institute needs to let the patients with the periodontal disease know about the effects of economic stress and state-trait anxiety. They also necessarily need to implement education program including stress management, economic stress, and state-trait anxiety improvement in order to prevent periodontal disease and to take charge.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.223-228
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• 2019

This study analyzes the propagation of the path losses between Jeju-do and Jin-do transceivers located in the coastal areas of Korea using the Advanced Refractive Prediction System(AREPS) simulation software based on the actual coastal weather database. The simulated data is used to construct a duct map according to the altitude and thickness of the trap. The duct map is then divided into several regions depending on the altitude parameters of Tx and Rx, which can be used to effectively estimate the abnormal wave propagation characteristics due to duct occurrence in the Jeju-do coastal area. To validate the proposed duct map, two representative atmospheric index samples of the weather database in May 2018 are selected, and the simulated path losses using these atmospheric indices are compared with the measured data. The simulated path losses for abnormal conditions at the Rx point at Jeju-do are 167.7 dB and 192.3 dB, respectively, which are in good agreement with the measured data of 164.4 dB and 194.9 dB, respectively.

• Journal of Korea Water Resources Association
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• v.54 no.6
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• pp.443-452
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• 2021

The authors obtained the discrete hedging rule for a reservoir's water supply operation by applying mixed-integer programming to save more water by earlier rationing of water supply for a drought period. The 'water supply adjustment guide' is the current operational method applied to the multipurpose reservoirs, and it was derived by a simulation method. Applying the two rules to the Hapcheon multipurpose dam's reservoir simulations with the inflow record from 2003 to 2018, the water supply deficit occurred for the long drought from 2015 to 2018. Especially, the no water supply or intermittent water supply persisted for the second half of 2017. The water supply adjustment guide had the 'normal water supply recovery threshold on storage,' which resulted in the water supply being unavailable in July 2017; then, the water supply suspension occurred until January 2018, when the reservoir storage was greater than the normal water supply recovery threshold. Despite the storage increasing due to the inflow of water into the reservoir, the suspension occurrence needs to be improved in practice. The current water supply adjustment guide and the discrete hedging rule for a reservoir's water supply operation are useful and realistic as the reservoir operation guide, which shows the concept of reducing water supply during the drought phase as scientific figures. However, to improve the reservoir simulation results, which do not provide any or intermittent water for several months, it is necessary to increase the current water supply reduction for drought phases.

• Journal of Korea Society of Waste Management
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• v.35 no.8
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• pp.744-753
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• 2018

The Stockholm Convention, which was adopted in Sweden in 2001 to protect human health and the environment, includes regulations for Persistent Organic Pollutant Rotors such as toxic and bioaccumulatives. Currently, there are 28 types of materials. This prohibits and limits the production, use, and manufacture of products. Korea is a member of the Convention, and it is necessary to prepare management and treatment plans to address the POP trends. Thus, we experimentally investigate whether the environmentally stable incineration is achieved when the sample is thermally treated using the Lab-scale (1 kg/hr). The target samples is pesticides in liquid phase and solid phase. In this study, organic chlorinated pesticides and their thermal characteristics were analyzed. We calculated the theoretical air volume based on the element analysis results. Because the interior of the reactor is small, more than 10 times of the air ratio was injected. The retention time was set to at least 4 seconds using a margin. The incineration temperature was $850^{\circ}C$ and $1100^{\circ}C$. Thus, we experimentally investigated whether the environmentally stable incineration was achieved when the sample was thermally treated using the Lab-scale (1 kg/hr). We analyzed five types of exhaust gas; the 02 concentration was high, but the CO amount decreased. Complete combustion is difficult because of the small size of the furnace due to the nature of Lab-scale. The organic chlorine-containing pesticide had an average decomposition rate of 99.9935%. Considering the decomposition rates of organic chlorine-containing pesticide in this study, the incineration treatment at over 2 ton/hour, which is typical for a conventional incinerator, is possible. Considering the occurrence of dioxins and unintentional persistent organic pollutants, it can operate at more than $1,100^{\circ}C$.