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Search Results: 1 - 10 of 46608 matches for " Jeong Weon Wu "
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Continuous Spatial Tuning of Laser Emissions in a Full Visible Spectral Range
Mi-Yun Jeong,Jeong Weon Wu
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12032007
Abstract: In order to achieve a continuous tuning of laser emission, the authors designed and fabricated three types of cholesteric liquid crystal cells with pitch gradient, a wedge cell with positive slope, a wedge cell with negative slope, and a parallel cell. The length of the cholesteric liquid crystal pitch could be elongated up to 10 nm, allowing the lasing behavior of continuous or discontinuous spatial tuning determined by the boundary conditions of the cholesteric liquid crystal cell. In the wedge cell with positive slope, the authors demonstrated a continuous spatial laser tuning in the near full visible spectral range, with a tuning resolution less than 1 nm by pumping with only a single 355 nm laser beam. This continuous tuning behavior is due to the fact that the concentration of pitch gradient matches the fixed helical pitch determined by the cell thickness. This characteristic continuous spatial laser tuning could be confirmed again by pumping with a 532 nm laser beam, over 90 nm in the visible spectral range. The scheme of the spatial laser tuning in the wedge cell bearing a pitch gradient enabled a route to designing small-sized optical devices that allow for a wide tunability of single-mode laser emissions.
Tripmultiplet-state dynamics of manganese(III) porphyrin fabricated into PVC film
Jeong-Hyon Ha,Weon-Sik Chae,Jahan Kim
Journal of Analytical Science & Technology , 2011,
Abstract: Luminescence lifetimes of anion complexes of manganese(III) porphyrins incorporated in the PVC polymer film were investigated by the time-correlated single photon counting (TCSPC) method. The tripquintet state lifetimes (tens of picoseconds) which had been measured in the solution phase were reduced to the hundreds of picoseconds regime in the polymer solid phase when the internal motions of porphyrin moieties are restricted by the PVC polymer matrix. The main effects of bulkier anion ligation on photophysical properties were the increment of effective void volume. The increase of lifetime constants in the stiff polymer matrix was largest in case of the smallest anion ligation due to the restriction of internal motion induced by local polymer structure having the smaller void volume.
Preliminary Study for Dosimetric Characteristics of 3D-printed Materials with Megavoltage Photons
Seonghoon Jeong,Myonggeun yoon,Weon Kuu Chung,Dong Wook Kim
Physics , 2015,
Abstract: In these days, 3D-printer is on the rise in various fields including radiation therapy. This preliminary study aimed to estimate the dose characteristics of the 3D-printer materials which could be used as the compensator or immobilizer in radiation treatment. The cubes which have 5cm length and different densities as 50%, 75% and 100% were printed by 3D-printer. A planning CT scans for cubes were performed using a CT simulator (Brilliance CT, Philips Medical System, Netherlands). Dose distributions behind the cube were calculated when 6MV photon beam passed through cube. The dose response for 3D-printed cube, air and water were measured by using EBT3 film and 2D array detector. When results of air case were normalized to 100, dose calculated by TPS and measured dose of 50% and 75% cube were 96~99. Measured and calculated doses of water and 100% cube were 82~84. HU values of 50%, 75% and 100% were -910, -860 and -10, respectively. From these results, 3D-printer in radiotherapy could be used for medical purpose accurately.
Planck cold clumps in the $λ$ Orionis complex: I. Discovery of an extremely young Class 0 protostellar object and a proto-brown dwarf candidate in a bright rimmed clump PGCC G192.32-11.88
Tie Liu,Qizhou Zhang,Kee-Tae Kim,Yuefang Wu,Chang Won Lee,Jeong-Eun Lee,Kenichi Tatematsu,Minho Choi,Mika Juvela,Mark Thompson,Paul F. Goldsmith,Sheng-yuan Liu,Hirano Naomi,Patrick Koch,Christian Henkel,Patricio Sanhueza,JinHua He,Alana Rivera-Ingraham,Ke Wang,Maria R. Cunningham,Ya-Wen Tang,Shih-Ping Lai,Jinghua Yuan,Di Li,Gary Fuller,Miju Kang,Quang Nguyen Luong,Hauyu Baobab Liu,Isabelle Ristorcelli,Ji Yang,Ye Xu,Tomoya Hirota,Diego Mardones,Sheng-Li Qin,Huei-Ru Chen,Woojin Kwon,FanYi Meng,Huawei Zhang,Mi-Ryang Kim,Hee-Weon Yi
Physics , 2015,
Abstract: We are performing a series of observations with ground-based telescopes toward Planck Galactic cold clumps (PGCCs) in the $\lambda$ Orionis complex in order to systematically investigate the effects of stellar feedback. In the particular case of PGCC G192.32-11.88, we discovered an extremely young Class 0 protostellar object (G192N) and a proto-brown dwarf candidate (G192S). G192N and G192S are located in a gravitationally bound bright-rimmed clump. The velocity and temperature gradients seen in line emission of CO isotopologues indicate that PGCC G192.32-11.88 is externally heated and compressed. G192N probably has the lowest bolometric luminosity ($\sim0.8$ L$_{\sun}$) and accretion rate (6.3$\times10^{-7}$ M$_{\sun}$~yr$^{-1}$) when compared with other young Class 0 sources (e.g. PACS Bright Red sources (PBRs)) in the Orion complex. It has slightly larger internal luminosity ($0.21\pm0.01$ L$_{\sun}$) and outflow velocity ($\sim$14 km~s$^{-1}$) than the predictions of first hydrostatic cores (FHSCs). G192N might be among the youngest Class 0 sources, which are slightly more evolved than a FHSC. Considering its low internal luminosity ($0.08\pm0.01$ L$_{\odot}$) and accretion rate (2.8$\times10^{-8}$ M$_{\sun}$~yr$^{-1}$), G192S is an ideal proto-brown dwarf candidate. The star formation efficiency ($\sim$0.3\%-0.4\%) and core formation efficiency ($\sim$1\%) in PGCC G192.32-11.88 are significantly smaller than in other giant molecular clouds or filaments, indicating that the star formation therein is greatly suppressed due to stellar feedback.
Full sequence analysis and characterization of the South Korean Norovirus GII-4 variant CUK-3
Jeong-Woong Park, Sung-Geun Lee, Young-Min Lee, Weon-Hwa Jheong, Sangryeol Ryu, Soon-Young Paik
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-167
Abstract: In recognition of the necessity for tracking and monitoring of genetic diversity, a norovirus variant among the most prevalent genotype GII-4, Norovirus Hu/GII-4/CUK-3/2008/KR (CUK-3), was isolated from stool samples and analyzed on the level of whole genome sequence. Whole genome sequence analysis revealed three ORF composites of the whole genome, ORF1 (5100 bp), ORF2 (1623 bp), and ORF3 (807 bp). Each genetic relationship of CUK-3 variant analysis located the ORF1 (5,100 bp) in Cluster I, ORF2 (1623 bp) in Cluster I (2006b), ORF3 (807 bp) in Cluster I, and the whole genome sequence (about 5.1 kb) in Cluster I in the phylogenetic tree. And the phylogenetic analyses showed the same location of CUK-3 strain with the GII-4/2006b cluster in the phylogenetic tree.In This study, a first concerning the full-length sequence of a NoV variant in South Korea is meaningful in that it can be used not only as a full-length NoV variant sequence standard for future comparison studies, but also as useful material for the public health field by enabling the diagnosis, vaccine development, and prediction of new emerging variants.Noroviruses (NoVs) are the most important viruses that cause nonbacterial acute gastroenteritis in humans. In addition to increased susceptibility, the elderly are at increased risk for more severe disease and death, as are the very young and the immunocompromised [1,2]. They are small, and non-enveloped viruses which and belong to the family Caliciviridae, genus Norovirus. Noroviruses have a single positive-strand NoV RNA genome of about 7.6 kb in size. Three open reading frames (ORFs) have been identified in the NoV genomes. ORF1 encodes a polyprotein that is cleaved into six non-structural (NS) proteins, which carry amino acid sequence motifs conserved in NTPase, protease and RNA-dependent RNA polymerase (RdRp) [3,4]. ORF2 encodes a major structural protein, Viral Protein (VP1), which consist of two domains-the shell domain (S) and the protruding arm (P) t
Die Casting Mold Design of the Thin-walled Aluminum Case by Computational Solidification Simulation

Young-Chan Kim,Chang-Seog Kang,Jae-Ik Cho,Chang-Yeol Jeong,Se-Weon Choi,Sung-Kil Hong,

材料科学技术学报 , 2008,
Abstract: Recently, demand for the lightweight alloy in electric/electronic housings has been greatly increased. However, among the lightweight alloys, aluminum alloy thin-walled die casting is problematic because it is quite difficult to achieve sufficient fluidity and feedability to fill the thin cavity as the wall thickness becomes less than 1 mm. Therefore, in this study, thin-walled die casting of aluminum (Al-Si-Cu alloy: ALDC 12) in size of notebook computer housing and thickness of 0.8 mm was investigated by solidification simulation (MAGMA soft) and actual casting experiment (Buhler Evolution B 53D). Three different types of gating design, finger, tangential and split type with 6 vertical runners, were simulated and the results showed that sound thin-walled die casting was possible with tangential and split type gating design because those gates allowed aluminum melt to flow into the thin cavity uniformly and split type gating system was preferable gating design comparing to tangential type gating system at the point of view of soundness of casting and distortion generated after solidification. Also, the solidification simulation agreed well with the actual die-casting and the casting showed no casting defects and distortion.
Thin-Wall Aluminum Die-Casting Technology for Development of Notebook Computer Housing

Chang-Seog Kang,Jae-Ik Cho,Chang-Yeol Jeong,Se-Weon Choi,Young-Chan Kim,

材料科学技术学报 , 2008,
Abstract: Silicon-based aluminum casting alloys are known to be one of the most widely used alloy systems mainly due to their superior casting characteristics and unique combination of mechanical and physical properties.However, manufacturing of thin-walled aluminum die-casting components, less than 1.0 mm in thickness, is generally known to be very difficult task to achieve aluminum casting alloys with high fluidity. Therefore, in this study, the optimal die-casting conditions for producing 297 mm×210 mm×0.7 mm thin-walled aluminum component was examined experimentally by using 2 different gating systems, tangential and split type, and vent design. Furthermore, computational solidification simulation was also conducted. The results showed that split type gating system was preferable gating design than tangential type gating system at the point of view of soundness of casting and distortion generated after solidification. It was also found that proper vent design was one of the most important factors for producing thin-wall casting components because it was important for the fulfillment of the thin-wall cavity and the minimization of the casting distortion.
Predicting human lifespan limits  [PDF]
Byung Mook Weon, Jung Ho Je
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.29120
Abstract: Recent discoveries show steady improvements in life expectancy during modern decades. Does this support that humans continue to live longer in future? We recently put forward the maximum survival tendency, as found in survival curves of industrialized countries, which is described by extended Weibull model with agedependent stretched exponent. The maximum survival ten dency suggests that human survival dynamics may possess its intrinsic limit, beyond which survival is inevitably forbidden. Based on such tendency, we develop the model and explore the patterns in the maximum lifespan limits from industrialized countries during recent three decades. This analysis strategy is simple and useful to interpret the complicated human survival dynamics.
Predicting human lifespan limits  [PDF]
Byung Mook Weon,Jung Ho Je
Natural Science (NS) , 2010, DOI: 10.4236/ns.2009.29120
Abstract: Recent discoveries show steady improvements in life expectancy during modern decades. Does this support that humans continue to live longer in future? We recently put forward the maximum survival tendency, as found in survival curves of industrialized countries, which is described by extended Weibull model with agedependent stretched exponent. The maximum survival ten dency suggests that human survival dynamics may possess its intrinsic limit, beyond which survival is inevitably forbidden. Based on such tendency, we develop the model and explore the patterns in the maximum lifespan limits from industrialized countries during recent three decades. This analysis strategy is simple and useful to interpret the complicated human survival dynamics.
Quantum mechanics emerges from information theory applied to causal horizons
Jae-Weon Lee
Physics , 2010, DOI: 10.1007/s10701-010-9514-3
Abstract: It is suggested that quantum mechanics is not fundamental but emerges from classical information theory applied to causal horizons. The path integral quantization and quantum randomness can be derived by considering information loss of fields or particles crossing Rindler horizons for accelerating observers. This implies that information is one of the fundamental roots of all physical phenomena. The connection between this theory and Verlinde's entropic gravity theory is also investigated.
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