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Search Results: 1 - 10 of 27403 matches for " Sung Heum Lee "
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Usability Testing for Developing Effective Interactive Multimedia Software: Concepts, Dimensions, and Procedures
Sung Heum Lee
Educational Technology & Society , 1999,
Abstract: Usability testing is a dynamic process that can be used throughout the process of developing interactive multimedia software. The purpose of usability testing is to find problems and make recommendations to improve the utility of a product during its design and development. For developing effective interactive multimedia software, dimensions of usability testing were classified into the general categories of: learnability; performance effectiveness; flexibility; error tolerance and system integrity; and user satisfaction. In the process of usability testing, evaluation experts consider the nature of users and tasks, tradeoffs supported by the iterative design paradigm, and real world constraints to effectively evaluate and improve interactive multimedia software. Different methods address different purposes and involve a combination of user and usability testing, however, usability practitioners follow the seven general procedures of usability testing for effective multimedia development. As the knowledge about usability testing grows, evaluation experts will be able to choose more effective and efficient methods and techniques that are appropriate to their goals.
Nanoscale manipulation of the Mott insulating state coupled to charge order in 1T-TaS2
Doohee Cho,Sangmo Cheon,Ki-Seok Kim,Sung-Hoon Lee,Yong-Heum Cho,Sang-Wook Cheong,Han Woong Yeom
Physics , 2015,
Abstract: Quantum states of strongly correlated electrons are of prime importance to understand exotic properties of condensed matter systems and the controllability over those states promises unique electronic devices such as a Mott memory. As a recent example, a ultrafast switching device was demonstrated using the transition between the correlated Mott insulating state and a hidden-order metallic state of a layered transition metal dichalcogenides 1T-TaS2. However, the origin of the hidden metallic state was not clear and only the macroscopic switching by laser pulse and carrier injection was reported. Here, we demonstrate the nanoscale manipulation of the Mott insulating state of 1T-TaS2. The electron pulse from a scanning tunneling microscope switches the insulating phase locally into a metallic phase which is textured with irregular domain walls in the charge density wave (CDW) order inherent to this Mott state. The metallic state is a novel correlated phase near the Mott criticality with a coherent feature at the Fermi energy, which is induced by the moderate reduction of electron correlation due to the decoherence in CDW. This work paves the avenue toward novel nanoscale electronic devices based on correlated electrons.
Small sphincterotomy combined with endoscopic papillary large balloon dilation versus sphincterotomy
Hyun Gun Kim, Young Koog Cheon, Young Deok Cho, Jong Ho Moon, Do Hyun Park, Tae Hoon Lee, Hyun Jong Choi, Sang-Heum Park, Joon Seong Lee, Moon Sung Lee
World Journal of Gastroenterology , 2009,
Abstract: AIM: To compare small sphincterotomy combined with endoscopic papillary large balloon dilation (SES + ELBD) and endoscopic sphincterotomy (EST) for large bile duct stones.METHODS: We compared prospectively SES + ELBD (group A, n = 27) with conventional EST (group B, n = 28) for the treatment of large bile duct stones (≥ 15 mm). When the stone could not be removed with a normal basket, mechanical lithotripsy was performed. We compared the rates of complete stone removal with one session and application of mechanical lithotripsy.RESULTS: No significant differences were observed in the mean largest stone size (A: 20.8 mm, B: 21.3 mm), bile duct diameter (A: 21.4 mm, B: 20.5 mm), number of stones (A: 2.2, B: 2.3), or procedure time (A: 18 min, B: 19 min) between the two groups. The rates of complete stone removal with one session was 85% in group A and 86% in group B (P = 0.473). Mechanical lithotripsy was required for stone removal in nine of 27 patients (33%) in group A and nine of 28 patients (32%, P = 0.527) in group B.CONCLUSION: SES + ELBD did not show significant benefits compared to conventional EST, especially for the removal of large (≥ 15 mm) bile duct stones.
Semiconducting Polymer Photodetectors with Electron and Hole Blocking Layers: High Detectivity in the Near-Infrared
Xiong Gong,Ming-Hong Tong,Sung Heum Park,Michelle Liu,Alex Jen,Alan J. Heeger
Sensors , 2010, DOI: 10.3390/s100706488
Abstract: Sensing from the ultraviolet-visible to the infrared is critical for a variety of industrial and scientific applications. Photodetectors with broad spectral response, from 300 nm to 1,100 nm, were fabricated using a narrow-band gap semiconducting polymer blended with a fullerene derivative. By using both an electron-blocking layer and a hole-blocking layer, the polymer photodetectors, operating at room temperature, exhibited calculated detectivities greater than 1013 cm Hz1/2/W over entire spectral range with linear dynamic range approximately 130 dB. The performance is comparable to or even better than Si photodetectors.
Synthesis and Characterization of Carbon Nitride Films for Micro Humidity Sensors
Sung Pil Lee
Sensors , 2008, DOI: 10.3390/s8031508
Abstract: Nano-structured carbon nitride (CNx) films were synthesized by a reactive RFmagnetron sputtering system with a DC bias under various deposition conditions, and theirphysical and electrical properties were investigated with a view to using them for microhumidity sensors. The FTIR spectra of the deposited films showed a C=N stretching bandin the range of 1600~1700 ㎝-1, depending on the amount of nitrogen incorporation. Thecarbon nitride films deposited on the Si substrate had a nano-structured surfacemorphology with a grain size of about 20 nm, and their deposition rate was 1.5 μm/hr. Thesynthesized films had a high electrical resistivity in the range of 108 to 109 ω·cm,depending on the deposition conditions. The micro humidity sensors showed a goodlinearity and low hysteresis between 5 ~ 95 %RH.
Current implications of cyclophilins in human cancers
Jinhwa Lee, Sung Kim
Journal of Experimental & Clinical Cancer Research , 2010, DOI: 10.1186/1756-9966-29-97
Abstract: Cyclophilins (Cyps) were initially identified as biological receptors for the immunosuppressive drug cyclosporine A (CsA) approximately 25 years ago. Later, they were shown to have peptidyl-prolyl cis-trans isomerase (PPIase) enzymatic activity which catalyzes cis-trans isomerization of peptide bonds preceding proline [1-6]. Cyps also possess chaperone activities. These two functions allow Cyps to be involved in proper folding of proteins in combination with other proteins. Although CsA is an effective inhibitor of Cyps, immunosuppressive activity of CsA is not the result of inhibition of the Cyps' activities. Rather, the Cyp-CsA complex accidentally inhibits calcineurin activity and thereby suppresses T-cell proliferation by interfering with downstream signal transduction [7].Cyps are highly conserved from E. coli to humans throughout evolution. A total of 16 Cyp isoforms have been found in humans [8], but 7 major human Cyp isoforms, namely hCypA, hCypB, hCypC, hCypD, hCypE, hCyp40, and hCypNK [9], have been well characterized. They play diverse roles by localizing through unique domains for particular cellular compartments including the cytosol, endoplasmic reticulum (ER), mitochondria and nucleus. The clinical importance of Cyps has been implicated in diverse pathological conditions including HIV [10], hepatitis B and C viral infection, atherosclerosis [11,12], ER stress-related diseases such as diabetes, and neurodegenerative diseases. Cyps are also involved in normal cellular functions of muscle differentiation, detoxification of reactive oxygen species (ROS) [13], and immune response [14]. Their novel and unfamiliar nuclease activity similar to apoptotic endonucleases suggests a potential role in apoptotic DNA degradation. Overall roles of Cyps may encompass far more than already defined functions such as protein folding.CypA overexpression in diverse types of cancer has been recently reported by many research groups. Subsequently, overexpression of other Cyps
R-parity violating U(1)'-extended supersymmetric standard model
Lee, Hye-Sung
High Energy Physics - Phenomenology , 2008, DOI: 10.1142/S0217732308029939
Abstract: Supersymmetry is one of the best motivated new physics scenarios. To build a realistic supersymmetric standard model, however, a companion symmetry is necessary to address various issues. While R-parity is a popular candidate that can address the proton and dark matter issues simultaneously, it is not the only option for such a property. We review how a TeV scale U(1)' gauge symmetry can replace the R-parity. Discrete symmetries of the U(1)' can make the model still viable and attractive with distinguishable phenomenology. For instance, with a residual discrete symmetry of the U(1)', Z6 = B3 x U2, the proton can be protected by the baryon triality (B3) and a hidden sector dark matter candidate can be protected by the U-parity (U2).
Lightest U-parity Particle (LUP): a hidden sector dark matter candidate
Lee, Hye-Sung
High Energy Physics - Phenomenology , 2008, DOI: 10.1063/1.3052030
Abstract: We introduce a new dark matter candidate, the lightest U-parity particle (LUP). We suggest it as a good dark matter candidate especially in the R-parity violating supersymmetric model.
Dileptons and four leptons at Z' resonance in the early stage of the LHC
Lee, Hye-Sung
High Energy Physics - Phenomenology , 2008, DOI: 10.1016/j.physletb.2009.02.058
Abstract: The LHC era just began. The first discovery at the LHC experiment would be arguably a new resonance pole at TeV scale, if it exists. While the discovery of the Z' would be exciting by itself, it may also suggest what other new physics signals should be looked for while the LHC experiment is still at its early stage. We argue that the four lepton resonance at the Z' pole is a well-motivated and promising signal especially in supersymmetry framework, which can serve as a supersymmetry search scheme even in the early stage of the LHC experiment.
Suppression of Gate Oxide Degradation for MOS Devices Using Deuterium Ion Implantation Method
Jae-Sung Lee
Transactions on Electrical and Electronic Materials , 2012,
Abstract: This paper introduces a new method regarding deuterium incorporation in the gate dielectric including deuteriumimplantation and post-annealing at the back-end-of-the process line. The control device and the deuterium furnaceannealeddevice were also prepared for comparison with the implanted device. It was observed that deuteriumimplantation at a light dose of 1×1012 - 1×1014/cm2 at 30 keV reduced hot-carrier injection (HCI) degradation andnegative bias temperature instability (NBTI) within our device structure due to the reduction in oxide charge andinterface trap. Deuterium implantation provides a possible solution to enhance the bulk and interface reliabilities ofthe gate oxide under the electrical stress.
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