• Fisheries and Aquatic Sciences
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• v.24 no.11
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• pp.360-369
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• 2021

Paralytic shellfish toxins (PSTs) and tetrodotoxin (TTX) are neurotoxins that display pharmacological activity that is similar to that of specific sodium channel blockers; they are the principle toxins involved in shellfish and puffer fish poisoning. In Korea, puffer fish is a very popular seafood, and several cases of accidental poisoning by TTX have been reported. Therefore, it is necessary to determine whether puffer fish poisoning incidents are caused by PSTs or by TTX. In this study, we used mouse bioassay (MBA) and liquid chromatograph-tandem mass spectrometry (LC-MS/MS) to determine the presence of PSTs and TTX in puffer fish from an area near Mireuk-do, Tong-Yeong on the southern coast of Korea from January through March, 2014. The toxicity of PSTs and TTX extracts prepared from three organs of each specimen was analyzed by MBA. Most of the extracts killed mice with typical signs of TTX and PSTs. The LC-MS/MS analysis of seven specimens of Takifugu pardalis and Takifugu niphobles, each divided into muscles, intestines, and liver, were examined for TTX. In T. pardalis, the TTX levels were within the range of 1.3-1.6 ㎍/g in the muscles, 18.8-49.8 ㎍/g in the intestines, and 23.3-96.8 ㎍/g in the liver. In T. niphobles, the TTX levels were within the range of 2.0-4.5 ㎍/g in the muscles, 23.9-71.5 ㎍/g in the intestines, and 28.1-114.8 ㎍/g in the liver. Additionally, the toxicity profile of the detected PSTs revealed that dcGTX3 was the major component in T. pardalis and T. niphobles. When PSTs were calculated as saxitoxin equivalents the levels were all less than 0.5 ㎍/g, which is below the permitted maximum standard of 0.8 ㎍/g. These findings indicate that the toxicity of T. pardalis and T. niphobles from the southern coast of Korea is due mainly to TTX and that PSTs do not exert an effect.

• Journal of Biomedical Engineering Research
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• v.42 no.6
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• pp.259-267
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• 2021

Recently, the market for personal health care and medical devices based on Bluetooth Low Energy(BLE) has grown rapidly. BLE is being used in various medical data communication devices based on low power consumption and universal compatibility. However, since data errors occurring in the transmission of medical data can lead to medical accidents, it is necessary to analyze the causes of errors and study methods to reduce data error. In this paper, the minimum communication speed to be used in medical devices was set to at least 800 byte/sec based on the wireless electrocardiography regulations of the Ministry of Food and Drug Safety. And the data loss rate was tested when data was transmitted at a speed higher than 800 byte/sec. The factors that cause communication data error were classified, and the relationship between each factor and the data error rate was analyzed through experiments. When there were two or more activated peripherals connected to the central, data error occurred due to channel hopping and bottleneck, and the data error rate increased in proportion to the communication distance and the number of activated peripherals. Through this experiment, when the BLE is used in a medical device that intermittently transmits biosignal data, the risk of a medical accident is predicted to be low if the number of peripherals is 3 or less. But, it was determined that BLE would not be suitable for the development of a biosignal measuring device that must be continuously transmitted in real time, such as an electrocardiogram.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.6
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• pp.155-163
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• 2022

In order to avoid the spread of Covid-19, outdoor activities are decreasing worldwide and the time spent at home is increasing. As physical activity declines, the number of people who feel bored, restless and immune deficient is increasing. As indoor life becomes more permanent, multiple approaches to home workout are becoming active. This paper examines how the Covid blue (boredom and social anxiety) produced in the no-touch era affects quality of life through the use of home training applications. Questionnaires were collected from Chinese people using a website dedicated to Chinese questionnaires, and finally 383 appropriate data were analyzed using SPSS24.0 and AMOS24.0. The research results showed that the actual experience of using home workout had a positive impact on quality of life. The higher the user's sense of social unease about being late in the untact, It was found that the higher the social anxiety perceived by users about the untact era, the higher the interactivity and exercise satisfaction with the home workout app. Home workout application can improve exercise satisfaction and quality of life, which are more positive effects beyond the result of resolving consumers' boredom. Therefore, it can be used as a channel for digital services.

• Journal of Korea Trade
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• v.24 no.7
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• pp.1-28
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• 2020

Purpose - This paper empirically investigates the predictors and main determinants of consumers' ratings of mobile applications in the Google Play Store. Using a linear and nonlinear model comparison to identify the function of users' review, in determining application rating across countries, this study estimates the direct effects of users' reviews on the application rating. In addition, extending our modelling into a sentimental analysis, this paper also aims to explore the effects of review polarity and subjectivity on the application rating, followed by an examination of the moderating effect of user reviews on the polarity-rating and subjectivity-rating relationships. Design/methodology - Our empirical model considers nonlinear association as well as linear causality between features and targets. This study employs competing theoretical frameworks - multiple regression, decision-tree and neural network models - to identify the predictors and main determinants of app ratings, using data from the Google Play Store. Using a cross-validation method, our analysis investigates the direct and moderating effects of predictors and main determinants of application ratings in a global app market. Findings - The main findings of this study can be summarized as follows: the number of user's review is positively associated with the ratings of a given app and it positively moderates the polarity-rating relationship. Applying the review polarity measured by a sentimental analysis to the modelling, it was found that the polarity is not significantly associated with the rating. This result best applies to the function of both positive and negative reviews in playing a word-of-mouth role, as well as serving as a channel for communication, leading to product innovation. Originality/value - Applying a proxy measured by binomial figures, previous studies have predominantly focused on positive and negative sentiment in examining the determinants of app ratings, assuming that they are significantly associated. Given the constraints to measurement of sentiment in current research, this paper employs sentimental analysis to measure the real integer for users' polarity and subjectivity. This paper also seeks to compare the suitability of three distinct models - linear regression, decision-tree and neural network models. Although a comparison between methodologies has long been considered important to the empirical approach, it has hitherto been underexplored in studies on the app market.

• Journal of Korea Water Resources Association
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• v.54 no.7
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• pp.495-507
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• 2021

With the recent industrial development, accidental pollution in riverine environments has frequently occurred. It is thus necessary to simulate pollutant transport and dispersion using water quality models for predicting pollutant residence times. In this study, we conducted a field experiment in a meandering reach of the Sum River, South Korea, to validate the field applicability and prediction accuracy of RAMS+ (River Analysis and Modeling System+), which is a two-dimensional (2D) stream flow/water quality analysis program. As a result of the simulation, the flow analysis model HDM-2Di and the water quality analysis model CTM-2D-TX accurately simulated the 2D flow characteristics, and transport and mixing behaviors of the pollutant tracer, respectively. In particular, CTM-2D-TX adequately reproduced the elongation of the pollutant cloud, caused by the storage effect associated with local low-velocity zones. Furthermore, the transport model effectively simulated the secondary flow-driven lateral mixing at the meander bend via 2D dispersion coefficients. We calculated the residence time for the critical concentration, and it was elucidated that the calculated residence times are spatially heterogeneous, even in the channel-width direction. The findings of this study suggest that the 2D water quality model could be the accidental pollution analysis tool more efficient and accurate than one-dimensional models, which cannot produce the 2D information such as the 2D residence time distribution.

• Korean Association of Arts Management
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• no.57
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• pp.59-84
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• 2021

This study examined the structure of YouTube video network and the factors for the diffusion of Chinese creator's videos through the case of famous Chinese creator Fengtimo. There is few interest to the diffusion of Chinese contents among Korean researchers, while they have been studied the consumption of Hallyu(Korean wave) contents overseas. Using the data that YouTube Data API offers, this study analysed the video network that the comments of which are same users with NodeXL tools and the regression model with JASP tools. The study found that there are three groups of the YouTube channels of that network. They are domestic official accounts of Fengtimo, foreign officail accounts of Fengtimo and individual creators' accounts. The official accounts share the videos of Fengtimo's songs and entertainment contents for the fans, where the individual creators share their own meme videos(UGC). The significant factors for the diffusion in the YouTube video network are comments, likes, out-degree, dislikes, in-degree and betweenness centrality. There are significant difference between official channel and indivisual groups on the views. And degree and betweenness centrality have mediating effect. It is necessary to conduct more research on that subject with many other cases if we want to get to know the generalized explanation.

• The Korea Journal of Herbology
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• v.28 no.4
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• pp.63-69
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• 2013

Objectives : The purpose of present study was to investigate the vasorelaxant activities and mechanisms of action of the ethanol extract of P. yedoensis leaf (PYL) on isolated rat aortic rings. Methods : Dried P. yedoensis leaves were extracted 3 times with 100% ethanol for 3 h in a reflux apparatus. Isolated rat aortic rings were suspended in organ chambers containing 10 ml Krebs-Henseleit (K-H) solution. The rings were maintained at $37^{\circ}C$ and aerated with a mixture of 95% $O_2$ and 5% $CO_2$. Changes in their tension were recorded via isometric transducers connected to a data acquisition system. Results : PYL relaxed the contraction of aortic rings induced by phenylephrine (PE, 1 ${\mu}M$) or KCl (60 mM) in a concentration dependent manner. However, the vasorelaxant effects of PYL on endothelium-denuded aortic rings were lower than endothelium-intact aortic rings. And the vasorelaxant effects of PYL on endothelium-intact aortic rings were reduced by pre-treatment with $N{\omega}$-Nitro-L-arginine methyl ester (10 ${\mu}M$), methylene blue (10 ${\mu}M$), 1-H-[1,2,4]-oxadiazolo-[4,3-${\alpha}$]-quinoxalin-1-one (10 ${\mu}M$), tetraethylammonium (5 mM). In addition, PYL inhibited the contraction induced by extracellular $Ca^{2+}$ in endothelium-denuded aortic rings pre-contracted by PE or KCl in $Ca^{2+}$-free K-H solution. Conclusions : These results suggest that PYL exerts its vasorelaxant effects via the activation of Nitric Oxide (NO) formation by means of L-arginine and NO-cGMP pathways and via the blockage of receptor operated calcium channels, voltage dependent calcium channels and calcium-activated potassium channels.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.297-306
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• 2022

AtoN is an acronym for aids to navigation that indicate the position or direction of navigable areas and obstructions. AtoN should be arranged in consideration of unfamiliar navigator's convenience when it is indicated as the limits of navigable areas. Several narrow channels exist on the SW coast of Korea owing to the geographical effect, and the lateral or cardinal marks by the IALA maritime buoyage system are arranged along the narrow channels. This is an actual case study that analyzed the AtoN's role for safety navigation after changes in the maritime traffic environment owing to aquarfarm's development on narrow channels in the Korean SW coast. The analysis results of 5 narrow channels indicated that certain marks did not function properly as lateral or cardinal marks owing to the aquarfarm's location on navigable areas. Therefore, the following were suggested to improve AtoN on narrow channels: changing the position of marks, installing aquafarm's marks, and expressing the aquafarm's position on the nautical chart.

• 지역과문화
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• v.7 no.2
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• pp.155-172
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• 2020

This study analyzed the factors to customer attitude on the goods and service introduced in UGC(User Generated Contents) and explored the difference between Korean and Chinese customers. For the first research question, the hypothetical factors were selected through literature review, the area of which are media consumption, social media and effect of advertising. In this study examined 4 independent variables: information, reliability, BJ attractiveness and customer innovation. Methodologies are confirmatory factor analysis, correlation analysis and multi regression. Result showed that reliability, BJ attractiveness and customer innovation are statistically significant. According to the β value, the biggest one is customer innovation, the second one is BJ attractiveness and the third one is reliability. The influence of information on customer attitude is not statistically significant. The result is well-aligned with the prior studies. The information factor's influence, however, is disputable because some prior studies shows that it is not significant when the research samples are recently developed channel such as mobile or social media commerce platforms. It is necessary to identify the root causes why the information factor is not significant in some research cases. For the second research question, this study used independent t-test between Korean and Chinese customers. The result shows that the difference in reliability, BJ attractiveness and attitude are stastically significant, and the ratings of Chinese customers are higher. This result caused by the difference of media commerce environment between Korea and China. Information and customer innovation didn't show significant difference.

• Journal of Intelligence and Information Systems
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• v.28 no.3
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• pp.119-137
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• 2022

Recent recommendation system studies apply various deep learning models to represent user and item interactions better. One of the noteworthy studies is ONCF(Outer product-based Neural Collaborative Filtering) which builds a two-dimensional interaction map via outer product and employs CNN (Convolutional Neural Networks) to learn high-order correlations from the map. However, ONCF has limitations in recommendation performance due to the problems with CNN and the absence of side information. ONCF using CNN has an inductive bias problem that causes poor performances for data with a distribution that does not appear in the training data. This paper proposes to employ a Vision Transformer (ViT) instead of the vanilla CNN used in ONCF. The reason is that ViT showed better results than state-of-the-art CNN in many image classification cases. In addition, we propose a new architecture to reflect side information that ONCF did not consider. Unlike previous studies that reflect side information in a neural network using simple input combination methods, this study uses an independent auxiliary classifier to reflect side information more effectively in the recommender system. ONCF used a single latent vector for user and item, but in this study, a channel is constructed using multiple vectors to enable the model to learn more diverse expressions and to obtain an ensemble effect. The experiments showed our deep learning model improved performance in recommendation compared to ONCF.