• Informatization Policy
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• v.27 no.2
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• pp.66-83
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• 2020

Local issues that occur in cities typically garner great attention from the public. While local governments strive to resolve these issues, it is often difficult to effectively eliminate them all, which leads to complaints. In tackling these issues, it is imperative for local governments to use big data to identify the nature of complaints, and proactively provide solutions. This study applies the LDA topic modeling technique to research and analyze trends and patterns in complaints filed online. To this end, 9,625 cases of online complaints submitted to the city of Busan from 2015 to 2017 were analyzed, and 20 topics were identified. From these topics, key topics were singled out, and through analysis of quarterly weighting trends, four "hot" topics(Bus stops, Taxi drivers, Praises, and Administrative handling) and four "cold" topics(CCTV installation, Bus routes, Park facilities including parking, and Festivities issues) were highlighted. The study conducted big data analysis for the identification of trends and patterns in civil affairs and makes an academic impact by encouraging follow-up research. Moreover, the text mining technique used for complaint analysis can be used for other projects requiring big data processing.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.2
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• pp.119-129
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• 2015

Benthic marine algal flora and community structure at Chuksan on the mid-east coast of Korea were investigated seasonally from July 2007 to May 2009. Ninety-eight seaweed species were identified, including 13 green, 23 brown and 62 red algal species. The number of species found ranged between 33 and 63 among seasons. Two green (Ulva australis and Codium arabicum), three brown (Dictyota dichotoma, Sargassum fusiforme and Sargassum yezoense), and eleven red algae (Corallina pilulifera, Lithophyllum okamurae, Pachymeniopsis elliptica, Grateloupia filicina, G. cornea, Hildenbrandia rubra, Chondrus ocellatus, Acrosorium polyneurum, Chondria crassicaulis, Polysiphonia morrowii and Symphyocladia latiuscula) were observed throughout the survey period. Average marine algal biomass was $629.68g\;dry\;wt\;m^{-2}$ and it ranged seasonally from 119.30 to $1,660.96g\;dry\;wt\;m^{-2}$. The vertical distribution of marine algae was characterized by Corallina pilulifera and Sargassum spp. in the intertidal zone; Sargassum spp. at 1 m depth; Sargassum spp. and melobesioidean algae at 5 m depth; and melobesioidean algae at 10 m depth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.1
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• pp.46-52
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• 2013

After an outbreak of viral disease in an aquafarm, release of virus (es) from infected fish into environmental seawater has been suspected. In the present study, we utilized a negatively charged membrane (HA type) as an efficient method for concentration and detection of fish pathogenic viruses, specifically, megalocytivirus and viral hemorrhagic septicemia virus (VHSV) present in field-collected seawater samples or inoculated into seawater artificially. Positively charged viruses adsorbed onto the negatively charged membrane and were eluted with 1 mM NaOH (pH 10.5) following rinsing with 0.5 mM $H_2SO_4$ (pH 3.0). Megalocytivirus and VHSV particles isolated using anegatively charged HA membrane from seawater inoculated with each virus at a concentration of 10 viral particles/mL were of sufficient quantity to show positive results in atwo-step PCR (or RT two-step PCR); however, despite it being negatively charged, a cellulose acetate (CA) membraneshowed negative results. In quantitative PCR, the detection limits of the HA membrane for megalocytivirus and VHSV in seawater were 1.20E+00 viral particles/mL and 1.22E+01 viralparticles/mL, respectively. The calculated mean recovery yields from 1 L seawater spiked with known concentrations of megalocytivirus and VHSV particles were 28.11% and 23.00%, respectively. The concentrate of a 1-L sample of culturing seawater from the aquatank of flounder suffering from VHSV showed clear positive results in PCR when isolated with an HA, but not a CA, membrane. Thus, viral isolation using an HA membrane is a practical and reliable method for detection of fish pathogenic viruses in seawater.

• Informatization Policy
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• v.22 no.4
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• pp.22-44
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• 2015

With the growing interest being reflected in the FinTech industry, much attention has been paid to mobile easy payment services as well. In the era of mobile commerce, the core advantage of using mobile easy payment services(simplifying complex payment procedures and thus facilitating user convenience and reducing the chance of giving up payment) are being more emphasized. Mobile easy payment service market not only includes mobile easy payment service providers but also users, non-users, affiliates, banks, and credit card companies as main stakeholders. Exploring those stakeholders is thus important to thoroughly understand such market. However, extant literature on mobile easy payment services mostly focuses on examining adoption intention of users or non-users. This study, an exploratory research based on interviews, thus aims to extract driving as well as inhibiting factors of mobile easy payment service use from six different perspectives (i.e., social platform, bank, credit card company, affiliate, user, and non-user) and analyze a sequence of cause and effect for each factor. For this, the causal loop diagram was developed to deduce key issues and propose an alternative. Theoretical and practical implications of this study will also be discussed.

• Journal of agricultural medicine and community health
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• v.34 no.3
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• pp.368-374
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• 2009

Objectives: A group consisted of 32 Korean rural people had been travelled to Cambodia and Vietnam. During their travel for 7 days, first diarrheal case had occurred on 3rd day of travel and overall 8 people had diarrhea during travel. So we investigated the case for determination of the cause and route of infection. Methods: We interviewed all 32 people by visiting or telephone and took 23 stool samples from them, which are examined by Gyeungsangbuk-do Government Public Institute of Health & Environment in Korea. We interviewed travel agency for travel route and schedule. Results: The attack rate was 25.0% (8 cases) among 32 people. Of them, 3 cases were microbiologically confirmed to have the infection of Shigella flexneri (Serotype 3a). The result of this epidemiological investigation showed that the infection of shigellosis was happened in foreign countries. We assumed the water from Angkor-Watt was contaminated by S. flexneri. We could not able to test environmental specimens because of the infection is thought to be occurred in foreign countries. Conclusions: Most common infectious diseases from foreign countries are transmitted by water or food. Travellers to foreign countries must take caution for communicable diseases and must do report and get appropriate treatment when symptoms developed after travel.

• Korean journal of communication and information
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• v.50
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• pp.50-72
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• 2010

The purpose of this study was to investigate representation of media on Korean controversial historical incidents and its myth and ideology. Especially the authors paid attention to the MBC-TV Documentary which had dealt with many controversial issues in Korean society. Those issues had never been dealt by other Korean media before it began to do. Three episodes about the South-North Korea related issues were selected as main object of this study and were analyzed with various semiotic research methods, especially, paradigmatic analytical method, narrative analytic method and mythical analytic method. As a main result of this study, it was found that the Documentary tended to represent such controversial historical issues very differently from the previous representations of old newspapers'. Th e old newspapers tried to establish old myths; that is, 'myth of national crisis', 'myth of anti-communism', 'myth of scapegoat of college students', 'myth of intelligent agency's monopoly', 'myth of social stablization', etc, while the documentary changed to build up new myths; that is, 'myth of humanities', 'myth of peaceful unification', 'myth of freedom and democracy', 'myth of human rights, etc.' In short, it was concluded that the documentary was able to change some previous myths and ideologies through its changing representations.

• Korean journal of applied entomology
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• v.51 no.2
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• pp.131-140
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• 2012

The hawthorn spider mite, Tetranychus viennensis, is a pest of apples and a quarantine pest from some countries that import apples from Korea. A controlled atmosphere and temperature treatment system (CATTS) was developed as an alternative disinfestation method to methyl bromide fumigation treatment, and has been applied to control various insects and other arthropod pests on fruits. We applied CATTS to disinfect T. viennensis under conditions that were previously developed to control the peach fruit moth, Carposina sasakii. First, T. viennensis was sampled from Japanese apricot, Prunus mume, and identified by its morphological characters. In addition, both cytochrome oxidase I (COI) and internal transcribed spacer (ITS) sequences supported the morphological identification. Second, the heat-tolerant developmental stage was determined in T. viennensis. When a $46^{\circ}C$ heat treatment was applied to egg, nymph, and adult stages of T. viennensis, adults were the most tolerant stage. Third, when heat temperature was used along with 1% $O_2$ and 15% $CO_2$, the mites showed a significant increase in susceptibility to the heat treatment. Finally, CATTS at $46^{\circ}C$ with 15% $CO_2$ and 1% $O_2$ for 30 min resulted in 100% mortality of all T. viennensis development stages. These results indicated that CATTS isapplicable to disinfest T. viennensis in post-harvest apples.

• Journal of the Korean Institute of Gas
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• v.20 no.2
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• pp.35-42
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• 2016

Formamide is a colorless fluid with ammonia odor, and irritable when inhaled. It has $LD_{50}$ value of > 5,577 mg/kg in rats for acute oral toxicity and NOAEL of 113 mg/kg/day for target organ (liver) of whole body toxicity. It is also known as reproductive toxicant (1B) and TWA(Time Weighted Average) for it is 10 ppm. Workplace measurements of work places dealing with formamide showed the ppm of all 25 samples was very lower than WEL. However, the exposure concentration can change, depending on workplace condition such as the intensity of work, operating local ventilation system, and wearing protection equipment (Respirators). Therefore, considering it with the risk of whole body toxicity and reproductive toxicity, exposure quantity of each imaginary scenario was calculated at 5.16, 1.72, and $0.43mg/m^3$. The average value was calculated at 0.02-0.58, 0.02-0.66 at 90 percent of cumulative distribution, 0.02-0.69 at 95 percent of cumulative distribution. Therefore, it was generally evaluated to be safe because all values were below 1. However, caution is required to prevent health hazard because it has hepatotoxicity and reproductive toxicity and risk of a high level momentary exposure, depending on the condition of workplace.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.438-443
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• 2007

This study was done to investigate perchlorate contamination in Nakdong river. The perchlorate was detected in Nakdong river and ranged from ND to $82.1{\mu}g/L$. The highest concentration was observed in Wheguan. The perchlorate concentration was decreased with the down stream of Nakdong river. Three different virgin activated carbons made of each coal(Calgon), coconut(Samchully) and wood(Picabiol) based activated carbon(AC) were tested for an adsorption performance of perchlorate in a continuous adsorption column. Breakthrough behavior was investigated that the breakthrough points of coal, coconut and wood based AC as 2,300 bed volumn(BV), 719 BV and 288 BV respectively. Adsorption capacity(X/M) of real, coconut and wood based AC was observed. The experimental results of adsorption capacity showed that coal based AC was highest$(768.2{\mu}g/g)$, coconut based AC was intermediate$(299{\mu}g/g)$ and wood based AC was lowest$(99.2{\mu}g/g)$. Moreover, carbon usage rates(CURs) for coal, coconut and wood based AC had been shown as 0.71 g/day, 2.16 g/day and 3.45 g/day respectively. The constant characteristic of the system, k of coal, coconut and wood based ACs were found to be 307.2, 102.5 and 94.2, respectively.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.188-192
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• 2014

Until now, there has been much efforts for the development of polycyclic molecules as high energy materials because of their high density and potential energy. However, there were only a few reports on the development of highly N-substituted polycyclic compounds due to difficulties of the synthesis. We have designed pentaazapropellanes as new high energy materials and we have recently reported unsubstituted 3,7,9,11-tetraoxo-2,4,6,8,10-pentaaza[3.3.3]propellane (TOPAP) 2 as a new skeleton for high energy materials. Herein, the nitration of TOPAP 2 was reported for the first time. Thus, 2,6-dinitro-3,7,9,11-ttraoxo-2,4,6,8,10-pentaaza[3.3.3]propellane (2,6-DNTOPAP) 5C, which is a new nitro derivative of TOPAP 2, was obtained up to 82% yield by the reaction of $NO_2BF_4$ and anhydrous $HNO_3$. The structure of 5C was determined by spectroscopic analysis.