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Design of a mobile video streaming system using adaptive spatial resolution control
Heejung Lee,Yonghee Lee,Jonghun Lee,Dongeun Lee,Heonshik Shin IEEE 2009 IEEE TRANSACTIONS ON CONSUMER ELECTRONICS - Vol.55 No.3
<P>An efficient mobile video streaming system needs to cope with unstable network bandwidth and limited battery life. We propose a novel streaming system which jointly considers picture quality, bit-rate and energy consumption. Reducing the spatial resolution of a video stream adaptively proves to be more efficient in terms of picture quality and energy consumption than conventional rate control using only adjustment of quantization parameter. We apply the same scheme to scalable coding for large-scale mobile video streaming. This extends the adaptation of an SVC stream to lower bit-rates, while maintaining temporal stability. Our approach has been shown to improve picture quality by approximately 0.5 dB in low bit-rate conditions, and also reduces energy consumption by more than 50% compared to conventional video streaming.</P>
Lee, Han Bit,Kim, Young Won,Yoon, Jonghun,Lee, Nak Kyu,Park, Suk-Hee Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.4
<P>We developed a skin-conformal flexible sensor in which three-dimensional (3D) free-form elastomeric sheets were harmoniously integrated with a piezoelectric nanofiber mat. The elastomeric sheets were produced by polydimethylsiloxane (PDMS) molding via using a 3D printed mold assembly, which was adaptively designed from 3D scanned skin surface geometry. The mold assembly, fabricated using a multi-material 3D printer, was composed of a pair of upper/lower mold parts and an interconnecting hinge, with material properties are characterized by different flexibilities. As a result of appropriate deformabilites of the upper mold part and hinge, the skin-conformal PDMS structures were successfully sandwich molded and demolded with good repeatability. An electrospun poly(vinylidene fluoride trifluoroethylene) nanofiber mat was prepared as the piezoelectric active layer and integrated with the 3D elastomeric parts. We confirmed that the highly responsive sensing performances of the 3D integrated sensor were identical to those of a flat sensor in terms of sensitivity and the linearity of the input–output relationship. The close 3D conformal skin contact of the flexible sensor enabled discernable perception of various scales of physical stimuli, such as tactile force and even minute skin deformation caused by the tester’s pulse. Collectively from the 3D scanning design to the practical application, our achievements can potentially meet the needs of tailored human interfaces in the field of wearable devices and human-like robots.</P>
Extremely Rare CT and MRI Findings of Peritoneal Leiomyoma Mimicking Hepatic Mass: A Case Report
Jonghun Woo,Seo-Youn Choi,Hee Kyung Kim,Ji Eun Lee,Min Hee Lee,Sanghyeok Lim 대한영상의학회 2023 대한영상의학회지 Vol.84 No.4
Leiomyoma is a common benign tumor from smooth muscle cells, mostly in the uterus. Peritoneal leiomyomas (PLs) are extremely rare and mostly reported as disseminated peritoneal leiomyomatosis. However, to the best of out knowledge, radiologic findings of isolated PL are not reported in English literature. Herein, we introduce the radiologic findings of PL mimicking hepatic mass in a 34-year-old female. CT showed a mass with curvilinear heterogeneous enhancement at the liver’s peripheral area. On MRI, the mass showed gradual and heterogeneous enhancement on gadoxetic acid-enhanced MRI and diffusion restriction. The radiologic diagnosis was a benign hepatic tumor, such as degenerated hemangioma, adenoma, and inflammatory myofibroblastic tumor; however, the mass was diagnosed as PL pathologically.
Lee Jonghun,Kim Byung Chul,유원선,Han Ik Seung 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1
In this study, hull dimensions of an FPSO were optimized to maximize its operability at Brazil field. In contrast with the previous works which have used simplified models to evaluate some indicators related to stability and hydrodynamic performances of FPSOs for its own optimal design, we developed a generic hull and compartment modeler and sophisticated stability and hydrodynamic calculation modules. With the aid of the developed tools, the hull optimization was performed with initial dimensions of an FPSO originally designed for west Africa field. The optimization results indicated the relative importance of hydrodynamic performances compared with stability performances for the FPSO hull dimensioning by showing that there were 3 active constraints related to them, which were the natural periods of heave and roll and the maximum pitch angle under 1-year return period waves at full load condition. To the author's knowledge, this study is the first attempt to combine altogether the hull and compartment modeling and full set of stability and hydrodynamic calculations precisely to optimize an FPSO's hull dimensions within 30 min. Also, it is worthwhile to mention that the developed methods are generic enough to be applied to all types of ship-shaped offshore platforms.
Lee, Junghun,Lee, Sungjin,Kim, Jonghun,Song, Doosam,Jeong, Hakgeun Elsevier 2017 Energy and buildings Vol.149 No.-
<P><B>Abstract</B></P> <P>Simulations are widely used to calculate the thermal environment and energy consumption of buildings. The results of these simulations are affected by weather data, thus making the selection of appropriate weather data essential. Typical weather data are used to analyze a building’s thermal performance, but this is not appropriate for analyzing the performance of an actual building controlled by a building energy management system, which responds to real-time weather conditions. Such a building needs short-term weather forecast data to calculate the energy consumption. However, an evaluation of the validity of weather forecast data has not been performed. This study quantitatively analyzes the validation of real-time weather forecast data. A middleware platform was developed to combine weather forecast data and the EnergyPlus software using Grasshopper software. In addition, weather forecast data and actual weather data were compared to evaluate the forecast validation and a predictive control method using weather forecast data was devised. The application of real-time control was found to reduce the electricity costs incurred for cooling by 10% relative to there being no control, and by 2% relative to fixed temperature control.</P>