• Environmental Analysis Health and Toxicology
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• v.18 no.3
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• pp.209-217
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• 2003

To investigate the effects of low dosed microcystin -LR (MCLR) on the initial stage of subacute hepatotoxicity in vivo, male Sprague-Dawley rats after weanling were divided in four groups. The orally treated group (OG) was administered orally by 1 $\mu\textrm{g}$/kg B.W. at an interval of three days. The free group (FG) has taken the drinking water including 1 $\mu\textrm{g}$/L freely and the control group (CC) was only treated with 0.9％ saline solution All groups were treated for a period of 3 weeks. There was a significant correlation in body growth rate between OG and FC and especially, a deterioration of the growth of spleen was observed in the FG after 5 days. The protein levels were also decreased in OG and FG after 9 days. Level of total fat was increased to the 9th day but again decreased up to the initial level. High hemolysis of the isolated erythrocytes occurred only in OG. Activities of ${\gamma}$-G7 of 0G and FG were higher twice-fold than CG, but the values of OG were already higher at the first treatment day. No significant change in aspartate aminotransferase (AST) activity was shown in all groups, but the activity of alanine aminotransferase (ALT) was slightly increased at the beginning state. There were much similarities in the results of OG and FG. except the growth inhibition of spleen in FG. It may be concluded that long -term effects of the low doses of mycrocystins in animals including human being can lead to serious health problems, especially to liver and spleen.

• Composites Research
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• v.16 no.6
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• pp.33-40
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• 2003

The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.153-161
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• 2015

We propose a privacy-preserving location-based service (LBS) which supports top-k search service. The previous schemes hurt the privacy of either the user and the location of the objects because they are sent to the LBS server in a plaintext form. In the proposed method, by encrypting them with the fully-homomorphic encryption, we achieved the top-k search is possible while the information on them is not given to the LBS server. We performed a simulation on the proposed scheme with 16 locations where k is 3. The required time is 270 hours in a conventional desktop machine, which seems infeasible to be used in practice. However, as the progress of the hardware, the performance will be improved.

• Journal of the Korean Data and Information Science Society
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• v.24 no.1
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• pp.161-170
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• 2013

The FX (Foreign Exchange) is a form of exchange for the global decentralized trading of international currencies. The simple sense of Forex is simultaneous purchase and sale of the currency or the exchange of one country's currency for other countries'. We can find the consistent rules of trading by comparing the gradient boosting method and the decision trees methods. Methods such as time series analysis used for the prediction of financial markets have advantage of the long-term forecasting model. On the other hand, it is difficult to reflect the rapidly changing price fluctuations in the short term. Therefore, in this study, gradient boosting method and decision tree method are applied to analyze the short-term data in order to make the rules for the revenue structure of the FX market and evaluated the stability and the prediction of the model.

• Korean Journal of Social Welfare
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• v.61 no.2
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• pp.371-389
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• 2009

This study estimates the socioeconomic costs of missing children in Korea. The costs were classified as direct costs and indirect costs. The direct costs consisted of direct costs for searching for missing child such as making posters, transportation, and medical costs. The indirect costs were computed by the opportunity costs caused by child missing. The total costs that could be attributable to missing child were estimated to be about 570 million won per long-term missing child. This provides strong evidence that prevention of child missing is the most important and quick recovery after child is missing is the second most important. Missing child incurs substantial socioeconomic costs to the Korean society. Therefore, this study provides strong need for more interest from people who are indifferent to missing child issues and strong support for more government interventions to solve missing child problem in Korea. Further studies are needed to calculate socioeconomic costs of child missing more exactly.

• Journal of Convergence Society for SMB
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• v.3 no.2
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• pp.9-17
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• 2013

Android applications market has increased rapidly due to the popularity of smart phones. In order to high competitiveness in the application market should be high productivity, reduce cost. And short development cycle is required because of increased the android applications demand. Owing to develop applications in short time, the requirements analysis, design process are able to omitted. But in the case of reuse application at development phase, involved many problems because omit document or design. so target of this paper is android application source code that omit document or design. we propose architecture recovery techniques from android application source code by reverse engineering with identify functions are reused. We expect that increase productivity and reduce development cost, smooth maintain by proposed technique.

• Journal of Convergence for Information Technology
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• v.10 no.1
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• pp.93-98
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• 2020

The study aims to understand how indirect hallyu experiences in the Chinese market affect Korea's national brand image and willingness to purchase Korean goods from the perspective of "content consumption" and "recognition of Korea's." To that end, a total of 178 Chinese university students in the Beijing and Shanghai regions were analyzed. According to research and analysis, the perception of indirect hallyu experience has had a positive affection not only on the Korean national image but also on the willingness to purchase Korean products. Also, the halo effect came as Korea's national image had a positive effect on quite a lot of intentions to buy Korean merchandise. The recognition of South Korea can be enhanced by the spread of hallyu, which can be a decisive gauge of a favorable impression of the country in a short time.

• Journal of Digital Convergence
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• v.18 no.7
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• pp.223-228
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• 2020

The stock price reflects people's psychology, and factors affecting the entire stock market include economic growth rate, economic rate, interest rate, trade balance, exchange rate, and currency. The domestic stock market is heavily influenced by the stock index of the United States and neighboring countries on the previous day, and the representative stock indexes are the Dow index, NASDAQ, and S & P500. Recently, research on stock price analysis using stock news has been actively conducted, and research is underway to predict the future based on past time series data through artificial intelligence-based analysis. However, even if the stock market is hit for a short period of time by the forecasting system, the market will no longer move according to the short-term strategy, and it will have to change anew. Therefore, this model monitored Samsung Electronics' stock data and news information through text mining, and presented a predictable model by showing the analyzed results.

• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.90-96
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• 1983

The short period fermentation of the mushroom compost was studied as a method for the labor saving and mechanization of composting. Rice straw was crushed, watered and supplemented with organic nutrient sources. The straw-nutrient mixtures prepared were stacked and turned for short periods at the phase I and the phase II was carried out for 8 days. The total nitrogen of the short compost was lower than that of the conventional straw compost and it caused the yield decrease. The productivity of the short compost could be improved by the supplement of nurient sources. The effective nutrients were perilla meal and rice bran. Higher microflora of the rice straw-nutrient mixture during fermentation could shorten the composting period. For the short compost method the proper period of the phase I was 5 days.

• Water for future
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• v.27 no.3
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• pp.55-69
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• 1994

In order to enhance the short-term flood forecasting accuracy of the water level of the In-do Brdg., three statistical flood forecasting models are presented models are presented and the forecasting accuracies and stabilities of the models are studied. The presented statistical models are as follows: The multi-input model by the multi-regression analysis between the water level of the In-do Brdg. and the influence parameters(Model MM). The two-level multi parameter model according to the water level tendency(Model 2MP). Among the three models, the Model MM showed the lowest forecasting accuracy, the model 2MP showed the highest forecasting accuracy, although this model sometimes became unstable and diverged. The model MMP forecasted the flood less accurately than model 2MP, but it gave more stable forecasting results.