Development of Real Monitoring of Algal Toxins using Multi Functionalized Auto Sampler with Online LC/HRMS

Jaewon Choi,Wonseok Choi,Yuns Kim,Ilhwan Choi,Yongyeon Kim,Wonkyung Lee,Moondon Choi,Jongsu Park 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

Unfolding the Structure of Practical Knowledge of an Expert Physical Education Teacher

( Wonseok Choi ) 한국체육학회 2016 국제스포츠과학 학술대회 Vol.2016 No.1

Purpose: To define the professional knowledge base used in practice, the purpose of this study was to reveal the structure of practical knowledge of an expert physical education(PE) teacher. Practical knowledge proposed by Elbaz(1983) was used as both theoretical and analytical framework. Method: A qualitative case study design was used to examine and describe in depth certain features of the teaching process within the context of teaching expertise. The participating teacher was a female PE specialist in A metropolitan city and she is in her twenty-seventh year of teaching. She met a list of criteria typically associated with expert teachers. Data collection included observations and interviews. Data analysis involved description, analysis, interpretation process suggested by Wolcott(1994). Result: Findings revealed three images of her PE class: (a) everyone is the star, (b) PE should be interesting, (c) PE teacher is not a coach. Three images were supported by several principles(6) and rules(16), most of which were directly connected to teacher’s behavior or language while teaching in certain situation. Relationships among the images, principles, and rules showed hierarchical patterns and complex structures that were embedded in the teacher’s knowledge and teaching practice. Conclusion: Instead of focusing on physical activity and skill development in PE, the teacher in current study emphasized affective values such as character education, respect for each other, cooperation, and more. All she wanted to achieve in her gym was the students to love sports and PE, not because they were skilled performer, but because they fully internalized the value of participating sports and PE. However, follow up studies should be conducted to examine the individuality of practical knowledge of expert PE teachers.

Reduced Antibody Responses to the Pandemic (H1N1) 2009 Vaccine after Recent Seasonal Influenza Vaccination

Choi, Yoon Seok,Baek, Yun Hee,Kang, Wonseok,Nam, Seung Joo,Lee, Jino,You, Sooseong,Chang, Dong-Yeop,Youn, Jong-Chan,Choi, Young Ki,Shin, Eui-Cheol American Society for Microbiology 2011 Clinical and vaccine immunology Vol.18 No.9

<B>ABSTRACT</B><P>The vaccination program against the 2009 pandemic H1N1 influenza virus (2009 H1N1) provided a unique opportunity to determine if immune responses to the 2009 H1N1 vaccine were affected by a recent, prior vaccination against seasonal influenza virus. In the present study, we studied the immune responses to the 2009 H1N1 vaccine in subjects who either received the seasonal influenza virus vaccination within the prior 3 months or did not. Following 2009 H1N1 vaccination, subjects previously given a seasonal influenza virus vaccination exhibited significantly lower antibody responses, as determined by hemagglutination inhibition assay, than subjects who had not received the seasonal influenza virus vaccination. This result is compatible with the phenomenon of “original antigenic sin,” by which previous influenza virus vaccination hampers induction of immunity against a new variant. Our finding should be taken into account for future vaccination programs against pandemic influenza virus outbreaks.</P>

Thermal NaCl-MgCl2 Salt Purification for Reducing Reactor Vessel Corrosion

Wonseok Lee,Wonseok Yang,Jihun Kim,Hyeongbin Kim,Sungyeol Choi 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Molten chloride salts are promising candidates as a coolant for Molten Salt Reactors (MSRs) because of their low cost, high specific heat transfer, and thermal energy storage capacity. The NaCl- MgCl2 eutectic salts have enormous latent heat (430 kJ/kg) and financial advantage over other types of molten chloride salt. Despite the promise of the NaCl-MgCl2 eutectic salt, problems associated with structural material corrosion in the MSR system remain. The hygroscopicity of NaCl-MgCl2 and high MSRs operating temperature accelerate corrosion within structural alloys. Especially, MgCl2 reacts with H2O in the eutectic salt to produce HCl and Cl2, which are known to further exacerbate corrosion by the chlorination of structural materials. Therefore, several studies have worked to purify impurities associated with MgCl2, such as H2O. Thermal salt purification of NaCl-MgCl2 eutectic salt is one method that reduces HCl and Cl2 gas generation. However, MgO and MgOHCl are generated as the byproduct of thermal purification through a reaction between MgCl2 and H2O. The corrosion behavior of MgO within structural alloys after thermal treatment is not well known. This paper demonstrates corrosion behavior within structural alloy after thermal treatment at various temperature profiles of the NaCl-MgCl2 eutectic salt. According to the temperature range, MgCl2·H2O are separated at 100~200°C, and MgOHCl and HCl begin to occur at 240°C or higher. Finally, MgOHCl produces MgO and HCl at 500°C or higher temperatures. After thermal treatments, the H2O, MgOHCl, and MgO content were measured by Thermo Gravimetric Analyzer (TGA) to evaluate significant products causing corrosion. The structural materials were analyzed by the Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS) and using the mass change method to observe the type of localized corrosion, the corrosion rate, and the corrosion layer thickness. This study is possible in that it can reduce economic costs by reducing the essential use of expensive, high-purity molten salts because it is related to a substantial financial cost problem considering the amount of molten salt used in industrial sites.

Blockchain-based IoT Authentication techniques for DDoS Attacks

Wonseok Choi(최원석),Sungsoo Kim(김성수) 한국컴퓨터정보학회 2019 韓國컴퓨터情報學會論文誌 Vol.24 No.7

In the IoT(Internet of Things) environment, various devices are utilized and applied for different sites. But attackers can access easy to IoT systems, and try to operate DDoS(Distributed Denial-of-Service) attacks. In this paper, Sensor nodes, Cluster heads, and Gateways operates lightweight mutual authentication each others. Since authenticated sensor nodes and cluster heads only send transactions to Gateways, proposed techniques prevent DDoS attacks. In addition, the blockchain system contains secure keys to decrypt data from sensor nodes. Therefore, attackers can not decrypt the data even if the data is eavesdropped.

Classifying Arm Movement with Embedded System and Machine Learning

Wonseok Choi,Jungsub Oh,Heesu Kim,Jaehyun Kim 한국지능시스템학회 2017 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.17 No.2

This paper presents a method to classify the arm movements into 8 categories for the sensor data acquired from a micro-electro-mechenial sensor. The method uses the attribute weighted KNN (AWKNN) which is a kind of machine learning algorithm. The measurement system consists of gyroscopes and an accelerometer, attached to a human arm to measure arm movement. The system has been implemented with field-programmable gate array. The sensor data are pre-processed and handed over the AWKNN-based machine learning classifier to classify the sensed arm movements into 8 classes. The training data sets have been collected from the group of men and women who had exercised the predefined arm movements. The developed arm movement recognition system has achieved the accuracy higher than 90% in the experiments.

Soft Combining for Cooperative Spectrum Sensing over Fast-Fading Channels

Wonseok Choi,Moon-Gun Song,Jaeha Ahn,Gi-Hong Im IEEE 2014 IEEE communications letters Vol.18 No.2

<P>We propose soft combining methods for cooperative spectrum sensing in cognitive radio networks over fast-fading channels. In fast-fading environment, it is difficult to obtain the exact probability distribution of the total received energy during an observation period. Therefore, we apply the mixture of gamma (MoG) approximation to obtain the distribution function of the total received energy. By exploiting the approximated distribution, we derive a soft combining method that reduces the probability of missed detection for a given probability of false alarm based on the Neyman-Pearson criterion. In addition, we propose a simplified soft combining method by using the dominant component of the MoG distribution. Simulation results show that the proposed combining methods outperform the conventional methods based on the central limit theorem, the equal gain combining, and the SNR weighted combining.</P>

Development of sampling plans for Bemisia tabaci in paprika greenhouses

Wonseok Choi,Jung-Joon Park 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.04

A fixed-precision level sampling plan was developed for Bemisia tabaci in paprika greenhouses. A sampling plan consisted spatial distribution analysis, sampling stop line and decision making in order to establish B. tabaci control in paprika greenhouses. Sampling was conducted in two independent greenhouses at same time (GH 1, GH 2). The GH 1 and 2 were surveyed every week for 22 consecutive weeks, sampling locations of each greenhouse were 19 for GH 1, 9 for GH 2, respectively. The plants in the both greenhouse were divided top (200cm from the ground), middle (100cm from the ground), bottom (50cm from the ground) and observed B.tabaci’s adults and B.tabaci’s pupae in three paprika leaves at each position and recorded separately. GH 2 data was used to validate of fixed-precision sampling plan which developed by GH 1 data. In this study, spatial distribution analysis was evaluated using Taylor’s power law with the pooled data of the top and bottom (B.tabaci’s adults), the middle and bottom (B.tabaci’s pupae) in a 1-leaf sampling unit. Decision making is evaluated by maximum & minimum of action threshold according to the condition from several reference, and the value decided by the price of the plants. Using the results obtained in greenhouse, result simulated validation of developed sampling plan by RVSP(Resampling Validation for Sampling Plan) was showed reasonable precision level.

The Protective Effect of Roseburia faecis Against Repeated Water Avoidance Stress-induced Irritable Bowel Syndrome in a Wister Rat Model

Choi Soo In,Kim Nayoung,Nam Ryoung Hee,Jang Jae Young,Kim Eun Hye,Ha SungChan,Ha SungChan,Lee Wonseok,Choi HyeLim,Kim Yeon-Ran,Seok Yeong-Jae,Shin Cheol Min,Lee Dong Ho 대한암예방학회 2023 Journal of cancer prevention Vol.28 No.3

Roseburia faecis, a butyrate-producing, gram-positive anaerobic bacterium, was evaluated for its usefulness against repeated water avoidance stress (WAS)-induced irritable bowel syndrome (IBS) in a rat model, and the underlying mechanism was explored. We divided the subjects into three groups: one without stress exposure, another subjected to daily 1-hour WAS for 10 days, and a third exposed to the same WAS regimen while also receiving two different R. faecis strains (BBH024 or R22-12-24) via oral gavage for the same 10-day duration. Fecal pellet output (FPO), a toluidine blue assay for mast cell infiltration, and fecal microbiota analyses were conducted using 16S rRNA metagenomic sequencing. Predictive functional profiling of microbial communities in metabolism was also conducted. FPO and colonic mucosal mast cell counts were significantly higher in the WAS group than in the control group (male, P = 0.004; female, P = 0.027). The administration of both BBH024 (male, P = 0.015; female, P = 0.022) and R22-12-24 (male, P = 0.003; female, P = 0.040) significantly reduced FPO. Submucosal mast cell infiltration in the colon showed a similar pattern in males. In case of fecal microbiota, the WAS with R. faecis group showed increased abundance of the Roseburia genus compared to WAS alone. Moreover, the expression of a gene encoding a D-methionine transport system substrate-binding protein was significantly elevated in the WAS with R. faecis group compared to that in the WAS (male, P = 0.028; female, P = 0.025) group. These results indicate that R. faecis is a useful probiotic for treating IBS and colonic microinflammation

Potential geographical distribution model for overwintering population using CLIMEX – case study with Carposina sasakii

Wonseok Choi,Dong-Soon Kim,Kijong Cho,Jung-Joon Park 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.04

The establishment of insect population in certain region is affected by three major characteristics, the host spectrum, the phenological plasticity and the overwintering strategy. The geographical distribution of insect population is directly affected by their successful establishment in local environment, thus, in case of development of potential geographical distribution models, three major characteristics should be considered carefully. In this study, we developed geographical distribution model using CLIMEX system with well-known insect species, Carposina sasakii. Its geographical distribution is limited to northeast Asia including Korea, Japan, China and the Soviet Far East. C. sasakii overwinters as a full-grown larva within spherical and compactly woven larval-cocoons in the soil. We calculated Diapause Index (DI) then incorporated DI into CLIMEX system to simulate Ecoclimatic Index (EI), which stands for ability of establishment in a certain area for further studies of geographical distribution of insect populations which have overwintering strategy in their life history.