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Wonseok Yang,Yonadan Choi,Sungyeol Choi 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
Radioactive wastes, including used nuclear fuel and decommissioning wastes, have been treated using molten salts. Electrochemical sensors are one of the options for in-situ process monitoring using molten salts. However, in order to use electrochemical sensors in molten salt, the surface area must be known. This is because the surface area affects the current of the electrode. Previous studies have used a variety of methods to determine the electrode surface area in molten salts. One method of calculating the electrode surface area is to use the reduction current peak difference between electrodes with known length differences. The method is based on the reduction peak and has the benefit of providing long-term in-situ monitoring of surfaces immersed in molten salt. A number of assumptions have been made regarding this method, including that there is no mass transport by migration or convection; the reaction is reversible and limited by diffusion; the chemical activity of the deposit should be unity; and species should follow linear diffusion. For the purpose of overcoming these limitations, a variety of machine learning algorithms were applied to different voltammogram datasets in order to calculate the surface area. Voltammogram datasets were collected from multiarray electrodes, comprising a multiarray holder, two tungsten rods (1 mm diameter) working electrodes, a quasi-reference electrode, and a counter electrode. The multiarray electrode holder was connected to the auto vertical translator, which uses a servo motor, for changing the height of the rod in the molten salts. To make big and diverse data for training machine learning models, various concentrations of corrosion products (Cr, Fe) and fission products (Eu, Sm) in NaCl-MgCl2 eutectic salts were used as electrolyte; electrolyte temperatures were 500, 525, 550, 575, and 600°C. This study will demonstrate the potential of utilizing machine learning based electrochemical in situ monitoring in molten salt processing.
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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.
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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.
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Development of binomial sampling plan for Bemisia tabaci in paprika greenhouses
Wonseok Choi,Taechul Park,Junyeong Park,Ji-hun Kim,Ho-jeong Choi,Jung-Joon Park 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10
The density of sweetpotato whitefly, Bemisia tabaci, on greenhouse paprika (Capsicum annuum var. angulosum) were determined by counts of the number of B. tabaci per leaflet in Jinju, Gyeungsangnamdo during 2014. Binomial sampling plans were developed based on the relationship between the mean density per leaf (m) and the proportion of leaf infested with less than T B. tabaci per leaf (PT), according to empirical model (ln(m) = α + β(ln(-ln(1-PT))). T was defined as tally threshold, and set to 1, 2, 3, 4, 5 (adults) and 1, 3, 5, 7 (pupae) per leaf in this study. Increasing sample size, regardless of tally threshold, had little effects on the precision of the binomial sampling plan. Increasing sample size had little effect on the precision of the estimated mean regardless of tally thresholds. T=1 was chosen as the best tally threshold for estimating densities of B. tabaci adults based on the precision on the model and T=3 was best tally thresholds in B. tabaci pupae. Using the results obtained in the greenhouse, simulated validation of the developed sampling plan by RVSP (Resampling Validation for Sampling Plan) indicated the suitable results.
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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.
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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>
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Wonseok choi,Junho Yoon,Jung-Joon Park 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.10
Chemical control is the indispensable part of insect pest management. However, due to overuse of pesticides, the emergence of resistance to pests and environmental pollution problems are appeared. In order to solve these problems, the need of integrated pest management (IPM) has emerged. The IPM means that the pest density should be controlled and maintained to avoid any economic loss, also to minimize any side effects to the human beings and environment using appropriate control methods. In order to do successful IPM, sampling plan should be prepared. Sampling plan consists of monitoring, density estimation and decision making of target insect pests in certain crop field including the knowledge of spatial distribution. Tabaco whitefly, Bemisia tabaci, and Western flower thrips, Frankliniella occidentalis, are serious insect pests in paprika greenhouses. We selected two paprika greenhouses with different sizes (12,000 m2 and 4,000 m2). Insect pests monitoring was evaluated from January 24, 2014 to June 27, 2014. Two monitoring methods are used to develop sampling plans, one is visual survey for B. tabaci population, and the other is using sticky trap for F. occidentalis population, respectively. We calculated spatial distribution using Taylor’s Power Law (TPL). In visual survey results, TPL showed that adults and pupae of B. tabaci were aggregated in paprika greenhouses. And in trap survey results, F. occidentalis was also aggregated with different scale of the slope of TPL equation. In density estimation, the more density of insect pests, the less samples were required. Moreover, the more accuracy, the more samples were required for stop sampling in greenhouses. We selected hypothetic action threshold of 0.3 and 5 for decision making. As a result, if the action threshold is increased, the maximum sample number is decreased
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