• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.1-6
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• 2002

How is the flow in a rotating impeller. About 35 years have passed since one experimentalist rotating with the impeller. of a huge centrifugal blower made the flow measurements using a hot-wire anemometer (Fowler 1968). Optical measurement methods have great advantages over the intrusive methods especially for the flow measurement in a rotating impeller. One is the optical flow visualization (FV) technique (Senoo, et al., 1968) and the other is the application of laser velocimetry (LV) (Hah and Krain, 1990). Particle image velocimetries (PIVs) combine major features of both FV and LV, and are very attractive due to the feasibility of simultaneous and multi-points measurements (Hayami and Aramaki, 1999). A high-pressure-ratio transonic centrifugal compressor with a low-solidity cascade diffuser was tested in a closed loop with HFC134a gas at 18,000rpm (Hayami, 2000). Two kinds of measurement techniques by image processing were applied to visualize a flow in the compressor. One is a velocity field measurement at the inducer of the impeller using a PIV and the other is a pressure field measurement on the side wall of the cascade diffuser using a pressure sensitive paint (PSP) measurement technique. The PIV was successfully applied for visualization of an unsteady behavior of a shock wave based on the instantaneous velocity field measurement (Hayami, et al., 2002b) as well as a phase-averaged velocity vector field with a shock wave over one blade pitch (Hayami, et al., 2002a. b). A violent change in pressure was successfully visualized using a PSP measurement during a surge condition even though there are still some problems to be overcome (Hayami, et al., 2002c). Both PIV and PSP results are discussed in comparison with those of laser-2-focus (L2F) velocimetry and those of semiconductor pressure sensors. Experimental fluid dynamics (EFDs) are still growing up more and more both in hardware and in software. On the other hand, computational fluid dynamics (CFDs) are very attractive to understand the details of flow. A secondary flow on the side wall of the cascade diffuser was visualized based either steady or unsteady CFD calculations (Bonaiuti, et al.,2002). EFD and CFD methods will be combined to a hybrid method being complementary to each other. Measurement techniques by image processing as well as CFD calculations give a huge amount of data. Then, data mining technique will become more important to understand the flow mechanism both for EFD and CFD.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.11
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• pp.393-402
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• 2014

We have experienced an explosive increase of the IoT(Internet of Things) technology based devices including smart phones and the wireless communications. Also the growing power consumption in IEEE 802.11 WLANs(Wireless LANs) driven by these dramatic increases in not only mobile users and but also wireless APs(Access Points). To reduce the power consumption, this paper proposes a wireless AP power saving algorithm, which minimizes the transmission power without decrease the transmission and carrier sense ranges. A wireless AP which is use in our algorithm checks its own original coverage periodically for whether there is a new STA(Station) or not when its transmission power is decreased. Moreover, if there are no signaling message to connect the wireless AP, it changes its operation mode Wake-up to sleep. A Result shows that the proposed AP algorithm can reduce the total power consumption of the wireless AP approximated 18% and 35% compared to the conventional wireless AP with and without the existing power saving algorithm, respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.422-427
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• 2010

Korean Game industry, especially MMORPG(Massively Multiplayer Online Game) has been rapidly expanding in these days. But As game industry is growing, lots of online game security incidents have also been increasing and getting prevailing. One of the most critical security incidents is 'Game Bots', which are programs to play MMORPG instead of human players. If player let the game bots play for them, they can get a lot of benefic game elements (experience points, items, etc.) without any effort, and it is considered unfair to other players. Plenty of game companies try to prevent bots, but it does not work well. In this paper, we propose a behavior pattern model for detecting bots. We analyzed behaviors of human players as well as bots and identified six game features to build the model to differentiate game bots from human players. Based on these features, we made a Naive Bayesian classifier to reasoning the game bot or not. To evaluated our method, we used 10 game bot data and 6 human Player data. As a result, we classify Game bot and human player with 88% accuracy.

• Toxicological Research
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• v.35 no.1
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• pp.45-63
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• 2019

In view of the growing industrial use of Bacterial cellulose (BC), and taking into account that it might become airborne and be inhaled after industrial processing, assessing its potential pulmonary toxic effects assumes high relevance. In this work, the murine model was used to assess the effects of exposure to respirable BC nanofibrils (nBC), obtained by disintegration of BC produced by Komagataeibacter hansenii. Murine bone marrow-derived macrophages ($BMM{\Phi}$) were treated with different doses of nBC (0.02 and 0.2 mg/mL, respectively 1 and $10{\mu}g$ of fibrils) in absence or presence of 0.2% Carboxymethyl Cellulose (nBCMC). Furthermore, mice were instilled intratracheally with nBC or nBCMC at different concentrations and at different time-points and analyzed up to 6 months after treatments. Microcrystaline $Avicel-plus^{(R)}$ CM 2159, a plant-derived cellulose, was used for comparison. Markers of cellular damage (lactate dehydrogenase release and total protein) and oxidative stress (hydrogen peroxidase, reduced glutathione, lipid peroxidation and glutathione peroxidase activity) as well presence of inflammatory cells were evaluated in brochoalveolar lavage (BAL) fluids. Histological analysis of lungs, heart and liver tissues was also performed. BAL analysis showed that exposure to nBCMC or CMC did not induce major alterations in the assessed markers of cell damage, oxidative stress or inflammatory cell numbers in BAL fluid over time, even following cumulative treatments. $Avicel-plus^{(R)}$ CM 2159 significantly increased LDH release, detected 3 months after 4 weekly administrations. However, histological results revealed a chronic inflammatory response and tissue alterations, being hypertrophy of pulmonary arteries (observed 3 months after nBCMC treatment) of particular concern. These histological alterations remained after 6 months in animals treated with nBC, possibly due to foreign body reaction and the organism's inability to remove the fibers. Overall, despite being a safe and biocompatible biomaterial, BC-derived nanofibrils inhalation may lead to lung pathology and pose significant health risks.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.2
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• pp.127-134
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• 2019

With the advancement of IT technology, the amount of data generated has been growing exponentially every year. As an alternative to this, research on distributed systems and in-memory based big data processing schemes has been actively underway. The processing power of traditional big data processing schemes enables big data to be processed as fast as the number of nodes and memory capacity increases. However, the increase in the number of nodes inevitably raises the frequency of failures in a big data infrastructure environment, and infrastructure management points and infrastructure operating costs also increase accordingly. In addition, the increase in memory capacity raises infrastructure costs for a node configuration. Therefore, this paper proposes an in-memory-based hybrid big data processing scheme for improve the big data processing rate. The proposed scheme reduces the number of nodes compared to traditional big data processing schemes based on distributed systems by adding a combiner step to a distributed system processing scheme and applying an in-memory based processing technology at that step. It decreases the big data processing time by approximately 22%. In the future, realistic performance evaluation in a big data infrastructure environment consisting of more nodes will be required for practical verification of the proposed scheme.

• Communications of Mathematical Education
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• v.35 no.2
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• pp.137-152
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• 2021

Qualitative research has become a growing area of interest among the Korean educational researchers for the last two decades. As a consequence, the number of studies based on qualitative methods has rapidly increased while the quality of qualitative research has not gained much credit among scholars in Korea. This study explores to current practice of qualitative approaches in mathematics education-related studies. With this in mind, this study also seeks ways to improve the validity and trustworthiness of qualitative approaches, and to present implications for the practical practice of qualitative approaches in mathematics education. To this end, a general trend was investigated by conducting a basic analysis of 13 papers that used qualitative approaches and published in Communications of Mathematical Education from 2019 to 2020. Of the 13 papers. Through the basic analysis, 6 out of 13 papers were selected as the object of qualitative text analysis. The result of this qualitative text analysis discusses issues related to the validity and trustworthiness of qualitative research in a detailed manner. In conclusion, based on the results of this qualitative text analysis, this study suggests several key points to keep in mind when applying qualitative approaches in the field of mathematics education in the future.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.65-75
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• 2022

Livestock industry in Korea has been growing rapidly and has reached 23 trillion Korean won in 2021. This study focuses on broiler, which is one of the largest sectors in livestock industry. As the effects of climate change get more serious, primary industry such as livestock industry is fragile to climate change since it directly interacts with nature. Therefore, maintaining suitable rearing environment is important. One of the most frequently used ventilation type for controlling the rearing environment of broiler house, tunnel ventilation, causes frequent air velocity fluctuation which makes maintaining the rearing environment important. By measuring the air temperature, relative humidity and air velocity in various points inside the broiler house, the internal thermal environment uniformity was analyzed according to length, width and zone. The experimental house was found to have dead zone with high air temperature, relative humidity and low air velocity near the end of the inlet and at the end of the broiler house. By using heat stress index to analyze quantitatively, zone with highest heat stress index was found to increase by 7.55% compared to the lowest zone. As a result, to maintain uniform rearing environment inside the broiler house, different factors must be measured and analyzed and used to operate the environmental control facilities.

• The Korea Journal of Herbology
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• v.28 no.1
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• pp.59-64
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• 2013

Objectives : Methicillin-Resistant Staphylococcus aureus (MRSA) is a cephalosporin and beta-lactam antibiotic-resistant strains. In most cases, that is spread from infected patients and infection rates are growing increasingly. Thus, accordingly, increased resistance to antibiotics is causing serious problems in the world. Therefore, there is a need to develop alternative antimicrobial drugs for the treatment of infections diseases. Methods : The antibacterial activities of Sinhyowoldosan were evaluated against 3 strains of Methicillin-resistant staphylococcus aureus(MRSA) and 1 standard Methicillin-susceptible S. aureus (MSSA) strain by using the disc diffusion method, minimal inhibitory concentrations (MICs) assay, colorimetric assay using MTT test, checkerboard dilution test and time-kill assay was performed under dark. Results : The MIC (minimum inhibitory concentration) of Sinhyowoldosan water extract against S. aureus strains ranged from 500 to 2,000 ${\mu}g/mL$, so we have confirmed it on a strong antibacterial effect. Also, the combinations of Sinhyowoldosan water extract and conventional antibiotics exhibited improved inhibition of MRSA with synergy effect. We suggest that Sinhyowoldosan water extract against MRSA have antibacterial activity, it has potential as alternatives to antibiotic agent. the combination test was used, Triton X-100 (TX) and DCCD for measurement of membrane permeability and inhibitor of ATPase. As a result, antimicrobial activity of SH is affected by the cell membrane were assessed. Conclusion : We suggest that the Sinhyowoldosan water extract lead the treatment of bacterial infection to solve the resistance and remaining side-effect problems that are the major weak points of traditional antibiotics.

• The Mathematical Education
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• v.62 no.2
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• pp.211-236
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• 2023

The purpose of this study is to derive implications of preservice mathematics teacher education in Korea by analyzing the case of edTPA used in the preservice teacher training process in the United States. Recently, there has been a growing interest in promoting professional competencies considering not only the cognitive dimension related to knowledge development of preservice mathematics teachers but also the situational dimension considering reality in the classroom. The edTPA in the United States is a performance-based assessment based on lessons conducted by preservice teachers at school. This study analyzes the professional competencies required of preservice mathematics teachers by analyzing handbooks that described the case of edTPA in which preservice mathematics teachers in the United States participate. The edTPA includes planning, instruction, and assessment tasks, and continuous tasks are performed in connection with classes. Thus, the analysis is conducted on the points of linkage between the description of evaluation items and criteria in the planning, instruction, and assessment tasks, as well as the professional competencies required from that linkage. As a result of analyzing the edTPA handbooks, the professional competencies required of preservice mathematics teachers in the edTPA assessment were the competency to focus on and implement specific mathematics lessons, the competency to reflectively understand the implementation and assessment of specific mathematics lessons, and the competency to make a progressive determination of students' achievement related to their learning and their uses of language and representations. The results of this analysis can be used as constructs for competencies that can be assessed in the preservice in the organization of the preservice mathematics teacher curriculum and practice training semester system in Korea.

• Journal of Intelligence and Information Systems
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• v.29 no.3
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• pp.401-418
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• 2023

Recently, the socio-economic interest in Large Language Models (LLMs) has been growing due to the emergence of ChatGPT. As a type of generative AI, LLMs have reached the level of script creation. In this regard, it is important to address the issue of discrimination (sexism, racism, religious discrimination, ageism, etc.) in the performing arts in general or in specific performing arts works or organizations in a large language model that will be widely used by the general public and professionals. However, there has not yet been a full-scale investigation and discussion on the issue of discrimination in the performing arts in large-scale language models. Therefore, the purpose of this study is to textually analyze the perceptions of discrimination issues in the performing arts from LMMs and to derive implications for the performing arts field and the development of LMMs. First, BBQ (Bias Benchmark for QA) questions and measures for nine discrimination issues were used to measure the sensitivity to discrimination of the giant language models, and the answers derived from the representative giant language models were verified by performing arts experts to see if there were any parts of the giant language models' misperceptions, and then the giant language models' perceptions of the ethics of discriminatory views in the performing arts field were analyzed through the content analysis method. As a result of the analysis, implications for the performing arts field and points to be noted in the development of large-scale linguistic models were derived and discussed.