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

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.

Spatial synchrony analysis for the convergence of the distributionmodel of the pests and crop

Wonseok Choi,Kijong Cho,Jung-Joon Park 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10

Local distribution of insect pest population should be changed in near future as well as their host based on climate change scenario. Although well defined insect geographical distribution model is developed and projected its potential establishment in Korea, it has defectiveness without geographical matching of its host, because, in agriculture, insect pest damage is related by host-insect synchrony in time and space. In this study, the possible geographical distributions of two insect species, Corposina sasakii (native species) and light brown apple moth, Epiphyas postvittana (possible invasive species), were estimated by CLIMEX simulation under RCP8.5 climate change scenario. Projected farm land suitability of apple trees was obtained from open website of Fruit Research Division, NIHHS, RDA. All the potential geographical distribution maps were overlapped then the spatial synchrony were analyzed by SADIE (spatial analysis with distance indices) , which allows improved interpretation of the spatial synchrony.

Multifunctional Nanodroplets Encapsulating Naphthalocyanine and Perfluorohexane for Bimodal Image-Guided Therapy

Choi, Hyunsik,Choi, Wonseok,Kim, Jeesu,Kong, Won Ho,Kim, Ki Su,Kim, Chulhong,Hahn, Sei Kwang American Chemical Society 2019 Biomacromolecules Vol.20 No.10

<P>Although nanocarriers containing perfluorocarbon (PFC) have been widely investigated as an ultrasound (US) imaging agent and a high intensity focused ultrasound (HIFU) agent, these carriers have suffered from low stability and biocompatibility limiting their further biomedical applications. Here, we developed surface cross-linked polymer nanodroplets as a HIFU therapeutic agent guided by bimodal photoacoustic (PA) and US imaging. Pluronic F127 was reacted with 4-nitrophenyl chloroformate (NPC) and mixed with naphthalocyanine (Nc) in dichloromethane, which was added into the aqueous solution of amine-functionalized six-arm-branched poly(ethylene glycol) (PEG) to form an oil-in-water emulsion for the cross-linking reaction between the terminal NPC of Pluronic F127 and the primary amine of six-arm PEG. The resulting solution was sonicated with liquid perfluorohexane (PFH) to prepare PEG cross-linked Pluronic F127 nanoparticles encapsulating Nc and PFH (Nc/PFH@PCPN). Nc/PFH@PCPN appeared to be stable without any coalescence or vaporization in the physiological condition. Upon the application of HIFU, Nc/PFH@PCPN was vaporized and showed increased US intensity for 180 min. The Nc dye in the nanodroplets enabled the stable encapsulation of PFH and the bimodal US/PA imaging. In vivo PA/US image-guided HIFU ablation therapy confirmed that the nanodroplets increased the cavitation effect, induced necrosis and apoptosis of tumor cells, and reduced tumor growth significantly for 12 days. Taken together, the multifunctional Nc/PFH@PCPN was successfully developed as a new platform for PA/US image-guided HIFU therapy.</P> [FIG OMISSION]</BR>

Robust Localization of Unmanned Surface Vehicle Using DDQN-AM

Wonseok Choi,Hosun Kang,Jangmyung Lee 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.5

A robust localization algorithm has been proposed for an Unmanned Surface Vehicle (USV) using DDQN-AM (Double Deep Q-Network with Action Memory). Inertial Navigation System (INS) and Global Positioning System (GPS) are used for collecting location information and for controlling the USV with DDQN-AM algorithm. Conventional probability-based filters such as Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF) are suitable for estimating behaviors of nonlinear systems and have been widely applied for localizing various kinds of nonlinear vehicles. However, the algorithms diverge or linearization position error increases in localizing USVs that are required to follow a desired trajectory accurately under high wave and wind conditions. Also, computational complexity is very high, which causes the instability of the vehicle system. To address these problems, DDQN with Adam optimization for error back propagation have been adopted in this research. However, if learning is performed using the training data set of the current time (current state, reward, action) in the replay buffer of DDQN, the learning performance (accuracy for states and running time) may deteriorate and learning load may occur. therefore, to improve the learning performance of DDQN, DDQN-AM has been newly proposed by adding AM in this research. To verify the effectiveness and to show the superior learning performance of the proposed DDQN-AM against the conventional approaches, a simulation using Matlab and field experiments with a prototype USV have been performed at the seashore. As a result, the position error of DDQN-AM was improved by 57.6% compared to the existing approach, and the average running time was also shortened by 1 minute, 30 seconds.

Analyst Forecast Dispersion, Trading Volume, and Stock Return

Wonseok Choi,Kenton Hoyem,Jung-Wook Kim 서울대학교 경제연구소 2009 Seoul journal of economics Vol.22 No.2

We examine the relationship between opinion divergence among analysts, trading volume, and stock returns around earnings announcements. We find that the positive relation between volume and subsequent returns is stronger among stocks with lower dispersion in analysts' earnings estimates. We show that the high-volume stocks with low opinion divergence also have good past performance, suggesting that the selling pressure from investors with disposition effect may be the cause for the positive volumereturn relationship.

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.

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.

Development of Sampling Plans for Bemisia tabaci and Frankliniella occidentalis in Paprika Greenhouses

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

Temporal trends of the prevalence and incidence of atrial fibrillation and stroke among Asian patients with hypertrophic cardiomyopathy: A nationwide population-based study

Choi, You-Jung,Choi, Eue-Keun,Han, Kyung-Do,Jung, Jin-Hyung,Park, Jiesuck,Lee, Euijae,Choe, Wonseok,Lee, So-Ryoung,Cha, Myung-Jin,Lim, Woo-Hyun,Oh, Seil Elsevier 2018 INTERNATIONAL JOURNAL OF CARDIOLOGY Vol.273 No.-

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Atrial fibrillation (AF) and stroke are common in hypertrophic cardiomyopathy (HCM). We aimed to determine the prevalence and incidence of AF and stroke in patients with HCM during a 10-year period.</P> <P><B>Methods</B></P> <P>Using the Korean National Health Insurance Services database, we identified patients diagnosed with HCM from the entire Korean population between 2005 and 2015. The annual prevalence and incidence of AF and stroke in HCM patients were estimated.</P> <P><B>Results</B></P> <P>The prevalence of AF in HCM patients has gradually increased to 1.6-fold from 13.4% in 2005 to 20.9% in 2015. The incidence of AF ranged from 4.1 to 5.5%, a similar trend was observed for each year in HCM patients. The prevalence of stroke in HCM patients was approximately 10%, while that in HCM patients with AF was about 20%. During 8741 person-years, AF-related stroke occurred in 257 subjects among 2309 HCM patients with new-onset AF. The overall incidence rate of AF-associated stroke was 2.94 per 100 person-years. In subgroup analysis, the incidence rate of AF-associated stroke was 1.49 per 100 person-years in the under 45 year-old group and 1.48 per 100 person-years in the group with CHA<SUB>2</SUB>DS<SUB>2</SUB>­VASc score of 0 or 1 point in HCM patients.</P> <P><B>Conclusions</B></P> <P>The prevalence of AF in HCM patients gradually increased over 10 years. The annual risk of AF-associated stroke in HCM was over 1% even in younger patients and those with CHA<SUB>2</SUB>DS<SUB>2</SUB>­VASc score of 0 or 1 point, which provide evidence to support the prevention of stroke in HCM patients with AF.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This is the first largest nationwide study on hypertrophic cardiomyopathy (HCM), a rare myocardial disease in Korea. </LI> <LI> The prevalence of AF in HCM patients gradually increases to 1.6-fold from 13.4% in 2005 to 20.9% in 2015. </LI> <LI> The annual incidence of AF in HMC patients was about 5%, and higher in female and the elderly. </LI> <LI> The prevalence of stroke in HCM patients with AF was about 20%, which were more than twice that in overall HCM patients. </LI> <LI> The risk of AF-related stroke in HCM patients was >1% per person-year even in younger patients or low CHA<SUB>2</SUB>DS<SUB>2</SUB>­VAS<SUB>C</SUB> score. </LI> </UL> </P>