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Predicting movie audience with stacked generalization by combining machine learning algorithms
Park, Junghoon,Lim, Changwon The Korean Statistical Society 2021 Communications for statistical applications and me Vol.28 No.3
The Korea film industry has matured and the number of movie-watching per capita has reached the highest level in the world. Since then, movie industry growth rate is decreasing and even the total sales of movies per year slightly decreased in 2018. The number of moviegoers is the first factor of sales in movie industry and also an important factor influencing additional sales. Thus it is important to predict the number of movie audiences. In this study, we predict the cumulative number of audiences of films using stacking, an ensemble method. Stacking is a kind of ensemble method that combines all the algorithms used in the prediction. We use box office data from Korea Film Council and web comment data from Daum Movie (www.movie.daum.net). This paper describes the process of collecting and preprocessing of explanatory variables and explains regression models used in stacking. Final stacking model outperforms in the prediction of test set in terms of RMSE.
Park, Junghoon,Ju, Je-Beck,Choi, Wonchang,Kim, Sang-Ok Elsevier 2019 Journal of alloys and compounds Vol.773 No.-
<P><B>Abstract</B></P> <P>Rational design and synthesis of advanced electrode materials are considered essential for realizing high-performance lithium-ion batteries for the fast-growing electric vehicle and energy storage applications. Herein, a novel and robust core-shell structured ZnO-based composite (denoted as ZnO@C) is prepared via the controlled growth of zeolitic imidazolate frameworks (ZIF–8) on the surface of ZnO nanoparticles followed by thermal treatment under nitrogen atmosphere, and is utilized as a lithium-ion battery anode. The microstructural characterization of the ZnO@C composite reveals that ZnO particles are well-embedded within a highly conductive nitrogen-doped carbon nanolayer. The obtained ZnO@C composite exhibits a high specific capacity of 798 mA h g<SUP>−1</SUP> with an initial charge/discharge efficiency of 81%, good long-term cyclability of over 300 cycles at a high current density of 1 A g<SUP>−1</SUP>, and enhanced rate capability up to 2 A g<SUP>−1</SUP> with a LiF-rich solid electrolyte interphase (SEI) formed in the presence of the fluoroethylene carbonate additive. These results suggest that the combination of the multifunctional ZIF–8-derived carbon coating and the use of electrolyte additive as a SEI modifier significantly improves the lithium storage performance of high-capacity metal oxide anodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnO@C composite was synthesized via growth and thermal decomposition of ZIF–8. </LI> <LI> ZIF–8-derived carbon coating leads to volume-change mitigation and high conductivity. </LI> <LI> LiF-rich SEI film formed by FEC provides enhanced interfacial/structural stability. </LI> <LI> This composite demonstrates better lithium storage performance than pure ZnO. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Qualitative Stability Analysis of Soft Hand Exoskeleton Based on Tendon-driven Mechanism
Junghoon Park,Pilwon Heo,Jung Kim,나영진 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.11
There exist several hand exoskeletons systems that provide assistive force to the user for strength enhancement or rehabilitation. However, the lack of stability analyses for such systems has made it difficult to ensure that these systems can apply assistance forces corresponding to the user’s intended motion. In this study, a tendon-driven soft hand exoskeleton was developed to provide assistive grip force, and the qualitative stability condition of the system was investigated during system operation. The proposed exoskeleton assisted the middle finger, index finger, and thumb, based on the fingertip force estimated using a previously developed fingertip force sensor. This system applies a flexion force for the middle and index fingers, as well as flexion and abduction forces for the thumb. Because the stability of the system is important during the operation of the system, we qualitatively analyzed the stability condition of the system based on the modified form of the generalized unstructured model comprising the user’s finger, exoskeleton, and external environment. An experimental verification of the stability criterion was performed to determine the approximate range of the stably applicable assistance gain. This study is the first to quantify the stability of fingertip sensor-based assistive power being applied to the hand.
Design of an Extensive Emergency Rescue Service for Electric Vehicles
Junghoon Lee,Hyobin Kim,Gyung-Leen Park 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.10
This paper designs and develops an emergency rescue service for electric vehicles (EVs), which may suffer from the battery depletion during their trips. After building relevant data models on both chargers and EVs, our design defines the interaction among three parties of EV drivers, the rescue server, and rescue vehicles to responsively process the dispatch request and systematically meet the user requirement. Particularly, a comprehensive mobile application is developed on the Android operating system to help users to promptly send a rescue request to the server and monitor the request processing status. This user interface allows EV drivers to automatically specify their locations and necessary personal information as well as to view the distribution of emergency vehicles through user-friendly maps. Our design is scalable for a large number of emergency vehicles and rescue requests, accelerating the wide deployment of EVs in our daily lives. Moreover, the rescue system design can collaborate with an EV tracking system and charge reservation agents to create a more sophisticated EV information service.
Mechanotransduction of cardiomyocytes interacting with a thin membrane transducer
Park, Jungyul,Kim, Il Chaek,Cha, Jaemin,Park, Sukho,Lee, Junghoon,Kim, Byungkyu IOP 2007 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.17 No.6
<P>A novel platform is developed to study the mechanotransduction of cardiomyocytes. After the cardiomyocytes are seeded on 10 ?m thin, dome-shaped membranes with different sizes, their morphology and beating frequency are monitored. While the cells seeded on a larger membrane (800 ?m ? 800 ?m) grow normally, cells on a smaller membrane (200 ?m ? 200 ?m) grow in isolated groups, showing a lumped morphology. The beating frequency of the cells on the smaller membrane was faster than on the larger membrane. This intriguing phenomenon may be explained by the mechanical stress determined by the area of the membrane that affects the opening of ion channels.</P>
Identification and Molecular Characterization of HOS15-interacting Proteins in Arabidopsis thaliana
Junghoon Park;Chae Jin Lim,Irfan Ullah Khan;Masood Jan;Haris Ali Khan;Hee Jin Park,Yan Guo,Dae-Jin Yun 한국식물학회 2018 Journal of Plant Biology Vol.61 No.5
Chromatin modification is a key mechanism ofgene expression in eukaryotes, and involve interactionsamong several proteins. Recently, we reported that HOS15,a cullin-based E3 ligase receptor, is involved in chromatinremodeling, and regulates gene expression and cold tolerance inArabidopsis thaliana. To identify the protein complexes thatfunction in conjunction with HOS15, we performed FLAGtagaffinity purification using transgenic Arabidopsis plantsexpressing HOS15-FLAG, and isolated HOS15-interactingproteins. To identify these proteins, matrix-assisted laserdesorption ionization time-of-flight (MALDI-TOF) massspectrometry (MS) analysis was conducted, and 16 proteinswere identified. Database searches revealed that these proteinswere histone variants, histone deacetylases, mRNA splicingregulators, a protein kinase, and proteins of unknownfunction. The ability of these proteins binding to HOS15 wasconfirmed using yeast two-hybrid, co-immunoprecipitation(Co-IP), and luciferase complementation imaging (LCI)assays. Our data suggest that specific interactions betweenHOS15 and those proteins involve in chromatin remodelingand RNA processing regulates plant development and abioticstress in Arabidopsis.