• Asia pacific journal of information systems
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• v.18 no.3
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• pp.67-90
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• 2008

Prior to making choices among online products and services, consumers often search online product reviews written by other consumers. Online product reviews have great influences on consumer behavior because they are believed to be more reliable than information provided by sellers. However, ever-increasing lists of product reviews make it difficult for consumers to find the right information efficiently. A customized search mechanism is a method to provide personalized information which fits the user's requirements. This study examines effects of a customized search mechanism and perceived similarity between consumers and product reviewers on consumer behaviors. More specifically, we address the following research questions: (1) Can a customized search mechanism increase perceived similarity between product review authors and readers? (2) Are product reviews perceived as more credible when product reviews were written by the authors perceived similar to them? (3) Does credibility of product reviews have a positive impact on acceptance of product reviews? (4) Does acceptance of product reviews have an influence on purchase intention of the readers? To examine these research questions, a lab experiment with a between-subject factor (whether a customized search mechanism is provided or not) design was employed. In order to enhance mundane realism and increase generalizability of the findings, the experiment sites were built based on a real online store, cherrya.com (http://www.cherrya.com/). Sixty participants were drawn from a pool that consisted of undergraduate and graduate students in a large university. Participation was voluntary; all the participants received 5,000 won to encourage their motivation and involvement in the experiment tasks. In addition, 15 participants, who selected by a random draw, received 30,000 won to actually purchase the product that he or she decided to buy during the experiment. Of the 60 participants, 25 were male and 35 were female. In examining the homogeneity between the two groups, the results of t-tests revealed no significant difference in gender, age, academic years, online shopping experience, and Internet usage. To test our research model, we completed tests of the measurement models and the structural models using PLS Graph version 3.00. The analysis confirmed individual item reliability, internal consistency, and discriminant validity of measurements. The results show that participants feel more credible when product reviews were written by the authors perceived similar to them, credibility of product reviews have a positive impact on acceptance of product reviews, and acceptance of product reviews have an influence on purchase intention of the readers. However, a customized search mechanism did not increase perceived similarity between product review authors and readers. The results imply that there is an urgent need to develop a better customized search tool in order to increase perceived similarity between product review authors and readers.

• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.115-123
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• 2020

In this paper, we propose to evaluate the potential anti-inflammatory properties of root bark extract of Cudrania (C.) tricuspidata on lipopolysaccharide (LPS)-induced inflammation in macrophages of apolipoprotein E (ApoE) knockout (ApoE^-/-) mice, murine model of atherosclerosis. Atherosclerosis is a chronic vascular inflammatory disease. C. tricuspidata is a small tree of the Moraceae family and its extract has anti-inflammatory activities. However, its role in the progress of atherosclerosis is not yet clear. To determine anti-inflammatory effects of C. tricuspidata in atherogenesis, we applied LPS in peritoneal macrophages of ApoE^-/- mice and measured cell viability by CCK-8 and expression of pro-inflammatory cytokines by qRT-PCR following treatment with root bark extract of C. tricuspidata. Research data was expressed as differences between the cells treated with LPS and root bark extract and the cells treated with LPS alone (control) by a two-tailed non-parametric Mann-Whitney U-test using GraphPad Instat program. No cytotoxic effect was observed when the cells were treated with the extract at concentrations ≤ 100 ㎍/mL. The expression of inflammatory cytokines, including MCP-1, IL-1β, IFN-γ, TNF-α, and IL-6 were inhibited by the extract. These results indicated that the extract has an anti-inflammatory effect and therefore a possible role in the treatment of atherosclerosis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.3
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• pp.374-380
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• 2017

Image analysis and k-mean clustering were conducted to develop a grading system of dried sea cucumber (SC) based on rehydration rate. The SC images were obtained by taking pictures in a box under controlled light conditions. The region of interest was extracted to depict the shape of the SC in a 2D graph, and those 2D shapes were rendered to build a 3D model. The results from the image analysis provided the morphological features of the SC, including length, width, surface area, and volume, to obtain the parameters of the k-mean clustering weight. The k-mean clustering classified the SC samples into three different grades. Each SC sample was rehydrated at $30^{\circ}C$ for 40 h. During rehydration, the flux of each grade was analyzed. Our study demonstrates that the mass transfer rate of SC increased as the surface area increased, and the grade of SC was classified based on rehydration rate. This study suggests that the optimal rehydration process for SC can be achieved by applying a suitable grading system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5A
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• pp.307-315
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• 2012

Recently, ultra high performance fiber reinforced concrete (UHPFRC) having over 180 MPa compressive strength and 10 MPa tensile strength has been developed in Korea. However, UHPFRC represents different material properties with normal concrete (NC) and conventional high performance concrete (HPC) such as a high early age autogenous shrinkage and a rapid dry on the surface, because it has a low water-binder ratio and high fineness admixtures without coarse aggregate. In this study, therefore, to propose suitable experimental methods and regulations, and to evaluate mechanical properties at a very early age for UHPFRC, setting, shrinkage and tensile tests were performed. From the setting test results, paraffin oil was an appropriate material to prevent drying effect on the surface, because if paraffin oil is applied on the surface, it can efficiently prevent the drying effect and does not disturb or catalyze the hydration of cement. From the ring-test results, it was defined that the shrinkage stress is generated at the time when the graph tendency of temperature and strain of inner steel ring is changed. By comparing with setting test result, the shrinkage stress was firstly occurred as the penetration resistance of 1.5 MPa was obtained, and it was about 0.6 and 2.1 hour faster than those of initial and final sets. So, the starting time of autogenous shrinkage measurement (time-zero) of UHPFRC was determined when the penetration resistance of 1.5 MPa was obtained. Finally, the tensile strength and elastic modulus of UHPFRC were measured from near initial setting time by using a very early age tensile test apparatus, and the prediction models for tensile strength and elastic modulus were proposed.

• Journal of the Korean School Mathematics Society
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• v.13 no.1
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• pp.23-43
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• 2010

This study is to investigate how much highschool students, who have learned functional concepts included in the Middle school math curriculum, understand chapters of the function, to analyze the types of errors which they made in solving the mathematical problems and to look for the proper instructional program to prevent or minimize those ones. On the basis of the result of the above examination, it suggests a classification model for teaching-learning methods and teaching material development The result of this study is as follows. First, Students didn't fully understand the fundamental concept of function and they had tendency to approach the mathematical problems relying on their memory. Second, students got accustomed to conventional math problems too much, so they couldn't distinguish new types of mathematical problems from them sometimes and did faulty reasoning in the problem solving process. Finally, it was very common for students to make errors on calculation and to make technical errors in recognizing mathematical symbols in the problem solving process. When students fully understood the mathematical concepts including a definition of function and learned procedural knowledge of them by themselves, they did not repeat the same errors. Also, explaining the functional concept with a graph related to the function did facilitate their understanding,

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.657-667
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• 2020

The Android framework allows apps to take full advantage of personal information through granting single permission, and does not determine whether the data being leaked is actual personal information. To solve these problems, we propose a tool with static/dynamic analysis. The tool analyzes the Source and Sink used by the target app, to provide users with information on what personal information it used. To achieve this, we extracted the Source and Sink through Control Flow Graph and make sure that it leaks the user's privacy when there is a Source-to-Sink flow. We also used the sensitive permission information provided by Google to obtain information from the sensitive API corresponding to Source and Sink. Finally, our dynamic analysis tool runs the app and hooks information from each sensitive API. In the hooked data, we got information about whether user's personal information is leaked through this app, and delivered to user. In this process, an automated Source/Sink classification model was applied to collect latest Source/Sink information, and the we categorized latest release version of Android(9.0) with 88.5% accuracy. We evaluated our tool on 2,802 APKs, and found 850 APKs that leak personal information.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.8
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• pp.55-64
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• 2017

In this paper, we propose and implement an IoT based mobile smart monitoring system in the view point of safety inspection for solar power generation. The main features and contributions of proposed system are as follows. First, the proposed system model can evaluate periodically in the view point of safety inspection the conditions of the system and structure of solar power generation. Second, the proposed system automatically re-processes the measurement data of the system and structure for solar power generation and save it into database. Third, using the re-processed and saved information, the proposed system can provide the monitoring information with webpage form to both administrator and owner of solar power generation system, thus they can measure and confirm directly in the view point of safety inspection the conditions of the solar generation structure without visiting those places. Fourth, the provided web pages for the monitoring of solar power generation can be accessed regardless of the system structures. The performance evaluations of the proposed system show that the proposed monitoring system can save efficiently the data received from the sensors installed in the structure of solar power generation into the data base in the collecting server. And the proposed system can support that both administrator and user of solar power generation system access webpage in real time without considering places by using mobile phone and desktop computer and obtain the information for the conditions of the system and structure of solar power generation with graph forms.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.11
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• pp.64-74
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• 1999

A new clock skew optimization for clock routing using link-edge insertion is proposed in this paper. It satisfies the given skew bound and prevent the total wire length from increasing. As the clock skew is the major constraint for high speed synchronous ICs, it must be minimized in order to obtain high performance. But clock skew minimization can increase total wire length, therefore clock routing is performed within the given skew bound which can not induce the malfunction. Clock routing under the specified skew bound can decrease total wire length Not only total wire length and delay time minimization algorithm using merging point relocation method but also clock skew reduction algorithm using link-edge insertion technique between two nodes whose delay difference is large is proposed. The proposed algorithm construct a new clock routing topology which is generalized graph model while previous methods uses only tree-structured routing topology. A new cost function is designed in order to select two nodes which constitute link-edge. Using this cost function, delay difference or clock skew is reduced by connecting two nodes whose delay difference is large and distance difference is short. Furthermore, routing topology construction and wire sizing algorithm is developed to reduce clock delay. The proposed algorithm is implemented in C programming language. From the experimental results, we can get the delay reduction under the given skew bound.

• Journal of Korean Society of Forest Science
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• v.90 no.3
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• pp.331-337
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• 2001

This study was performed to develope stem analysis program(Stemwin1.0) which can be used in PC with MS-Windows operating system. Stemwin1.0 uses width of annual tree ring measured with 1/100mm unit, and calculate increments of several growth factors such as DBH, height and volume with various methods. Mean DBH can be calculated by arithmetic and quadratic mean methods. Height can be estimated by parallel line, line extending and height curve methods. Volume can be estimated by Huber, Smalian, and Spline functions. Not only Total growth, Mean Annual Increment(MAI) and Current Annual Increment(CAI) of growth factors, but also merchantable volume and height, form factor, growth rate, and merchantable volume rate are automatically calculated. Stemwin1.0 can also output accurate stem taper curve with various scale, and prepare stem taper data(diameter at different disk heights) for statistical analysis for deriving stem taper model. Stemwin1.0 can export output data and graph to Excel for more compatible use of it.

• Toxicological Research
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• v.34 no.3
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• pp.221-229
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• 2018

Tenofovir nanoparticles are novel therapeutic intervention in human immunodeficiency virus (HIV) infection reaching the virus in their sanctuary sites. However, there has been no systemic toxicity testing of this formulation despite global concerns on the safety of nano drugs. Therefore, this study was designed to investigate the toxicity of Tenofovir nanoparticle (NTDF) on the liver and kidney using an animal model. Fifteen adult male Sprague-Dawley (SD) rats maintained at the animal house of the biomedical resources unit of the University of KwaZulu-Natal were weighed and divided into three groups. Control animals (A) were administered with normal saline (NS). The therapeutic doses of Tenofovir (TDF) and nanoparticles of Tenofovir (NTDF) were administered to group B and C and observed for signs of stress for four weeks after which animals were weighed and sacrificed. Liver and kidney were removed and fixed in formal saline, processed and stained using H/E, PAS and MT stains for light microscopy. Serum was obtained for renal function test (RFT) and liver function test (LFT). Cellular measurements and capturing were done using ImageJ and Leica software 2.0. Data were analysed using graph pad 6, p values < 0.05 were significant. We observed no signs of behavioural toxicity and no mortality during this study, however, in the kidneys, we reported mild morphological perturbations widening of Bowman's space, and vacuolations in glomerulus and tubules of TDF and NTDF animals. Also, there was a significant elevation of glycogen deposition in NTDF and TDF animals when compared with control. In the liver, there were mild histological changes with widening of sinusoidal spaces, vacuolations in hepatocytes and elevation of glycogen deposition in TDF and NTDF administered animals. In addition to this, there were no significant differences in stereological measurements and cell count, LFT, RFT, weight changes and organo-somatic index between treatment groups and control. In conclusion, NTDF and TDF in therapeutic doses can lead to mild hepatic and renal histological damage. Further studies are needed to understand the precise genetic mechanism.