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Search Results: 1 - 10 of 32956 matches for " Young Wan Kim "
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Eye Movements Provide Inhibitory Inputs to the Occipito-Temporal Region  [PDF]
Yul-Wan Sung, Hiroshi Tsubokawa, Young-Bo Kim, Seiji Ogawa
Open Journal of Medical Imaging (OJMI) , 2012, DOI: 10.4236/ojmi.2012.23015
Abstract: Eye movements play an important role in attention and visual processing. However, the manner in which eye move-ments are involved in object processing is not clear. The aim of this study is to examine the effects of eye movements on object-processing areas in the occipito-temporal region. Eye movements are always accompanied by visual perception; therefore, the effects of eye movements on object-processing areas in which visual object information is sent via eye movements instead of via retinal inputs of visual images must be measured. For this purpose, response to an eye- drawing stimulation in subjects who drew pictures of faces or buildings by their moving eyes under closed-eye condi-tions was measured by functional magnetic resonance imaging. Functional areas in the occipito-temporal region showed negative responses to the eye-drawing stimulation, and the pattern of negative activation maps in the region was almost the same as that of positive activation maps observed after visual image stimulation. Responses in cate-gory-selective area showed category dependency to the eye-drawing stimulation. This suggests that eye movements provide inhibitory inputs to the object-processing areas in the occipito-temporal region, and these inputs may modulate visual inputs to these areas coming through the retina in the visual perception process.
A Low-Loss Patch Ltcc BPF for 60 GHz System-on-Package (Sop) Applications
Young Chul Lee;Tae Wan Kim
PIER Letters , 2009, DOI: 10.2528/PIERL09110903
Abstract: In this paper, a three-dimensional (3-D) low-loss and wideband BPF based on lowtemperature co-fired ceramic (LTCC) has been presented for 60 GHz wireless communication applications. Via pads in the vertical via transitions are designed as an additional resonator for lowloss and wide-bandwidth of the BPF. The proposed BPF has been designed by investigating its characteristics as a function of dimensions of the resonators such as a single-mode patch and via pads and also a length of feed lines are optimized for effective coupling. The designed BPF was fabricated in a 6-layer LTCC dielectric. The fabricated BPF shows a centre frequency (fc) of 61.46 GHz and a 3dB bandwidth of 10.5% from 58.2 to 64.7 GHz (6.47 GHz). An insertion loss of -2.88 dB at fc and return losses below -10 dB are achieved. Its whole size is 4.72 × 1.7 × 0.684 mm.
Quantum electrodynamic Aharonov-Bohm effect of charge qubit
Young-Wan Kim,Kicheon Kang
Physics , 2015,
Abstract: We predict that a charge under the influence of a quantum electrodynamic potential exhibits a force-free Aharonov-Bohm effect. The specific system considered in this study is a superconducting charge qubit nonlocally interacting with a cavity electromagnetic field. We find that this nonlocal interaction gives rise to remarkable quantum electrodynamic phenomena such as vacuum Rabi splitting and oscillation, and Lamb shift, under the condition that the qubit is located in an electromagnetic-field-free region. Our result can be verified in a realistic experimental setup, and provides a new approach of investigating the Aharonov-Bohm effect combined with quantum electrodynamics.
Biomass and Community Structure of Epilithic Biofilm on the Yellow and East Coasts of Korea  [PDF]
Bo Yeon Kim, Seo Kyoung Park, Jin Suk Heo, Han Gil Choi, Young Sik Kim, Ki Wan Nam
Open Journal of Marine Science (OJMS) , 2014, DOI: 10.4236/ojms.2014.44026
Abstract: Spatial biomass variation and community structure of epilithic biofilms were examined using cell counts, chlorophyll a extraction, and remote-sensing techniques. Samples were collected at two levels of wave exposure along the Yellow and East Coasts of Korea in December 2010. Cyanobacteria were dominant, occupying about 88% of biofilm, irrespective of wave exposure levels. The cyanobacteria species, Aphanotece spp. was abundant in the Yellow Coast location and Lyngbya spp. was abundant in the East coast location. The representative diatoms were Navicula spp. and Achnanthes spp. on the rocky shores of all study sites. Average Normalized Difference Vegetation Index (NDVI) was significantly greater in the Yellow Coast (mean 0.46) than that in the East Coast (mean 0.21); a similar pattern was observed in Vegetation Index (VI). Chlorophyll a content was three times greater on the Yellow Coast (20.50 μg/cm2) than that on the East Coast (8.21 μg/cm2), and it was greater at the Gosapo and Bangpo shore sites than that at the Gyeokpo site, on the Yellow Coast. However, chlorophyll a contents were not different between 23.33 and 17.66 μg/cm2 at exposed- and sheltered-shores of Yellow Coast, and were 9.62 μg/cm2 and 6.80 μg/cm2 on the East Coast. Vegetation indices were positively correlated with chlorophyll a contents. In conclusion, biofilm of Korean upper rocky shore was mainly composed of cyanobacteria and biofilm biomass that differed between the Yellow and East Coast.
Design of Korean Standard Modular Buoy Body Using Polyethylene Polymer Material for Ship Safety  [PDF]
Young Whan Park, Tae Wan Kim, Jae Sub Kwak, In Kwan Kim, Ji Eon Park, Kyong Ho Ha
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.41011
Abstract:

Buoy is the structure which is floated on sea surface in order to indicate the presenting obstacle such as reef and shallow sea and to show the direction of sea route to ship during sailing. Generally, the conventional material of buoy is steel and it has some problems. Firstly this steel light buoy has safety risk in case of collision between ship and steel buoy. Secondly steel buoy revealed high corrosion environment of salted water and oxide and corrosion of steel can lead to marine pollution. Thirdly it needs too much maintain cost because of its heavy weight. In this study, in order to overcome these problems we changed the buoy material from conventional steel body to polyethylene body. Polymer buoy body was designed with module type part and it can reduce total weight up to 43.12%. To evaluate the strength of that part, the structure analysis simulation was carried out with respect to stress, displacement, and strain. Maximum stress was 1.667 × 107 N/m2 and it was 25% of yielding stress of base material. Maximum displacement and strain were 3.164 mm and 0.00433353 and they are too small value and in safe range with comparing to total length of body. The stability of polymer buoy body was compared with conventional buoy with respect to center of gravity, center of buoyancy, metacenter, oscillation period, and tilt angle by wind, tidal current, and wave. Every value was improved comparing conventional one and we can get more stable buoy. Therefore the new polymer buoy body could prove its safety and stability.

Quantitative Measurement of Elasticity of the Appendix Using Shear Wave Elastography in Patients with Suspected Acute Appendicitis
Seung-Whan Cha, Ik Yong Kim, Young Wan Kim
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0101292
Abstract: Introduction Shear wave elastography (SWE) has not been studied for diagnosing appendicitis. We postulated that an inflamed appendix would become stiffer than a normal appendix. We evaluated the elastic modulus values (EMV) by SWE in healthy volunteers, patients without appendicitis, and patients with appendicitis. We also evaluated diagnostic ability of SWE for differentiating an inflamed from a normal appendix in patients with suspected appendicitis. Materials and Methods Forty-one patients with clinically suspected acute appendicitis and 11 healthy volunteers were prospectively enrolled. Gray-scale ultrasonography (US), SWE and multi-slice computed tomography (CT) were performed. The EMV was measured in the anterior, medial, and posterior appendiceal wall using SWE, and the highest value (kPa) was recorded. Results Patients were classified into appendicitis (n = 30) and no appendicitis groups (n = 11). One case of a negative appendectomy was detected. The median EMV was significantly higher in the appendicitis group (25.0 kPa) compared to that in the no appendicitis group (10.4 kPa) or in the healthy controls (8.3 kPa) (p<0.001). Among SWE and other US and CT features, CT was superior to any conventional gray-scale US feature or SWE. Either the CT diameter criterion or combined three CT features predicted true positive in 30 and true negative in 11 cases and yielded 100% sensitivity and 100% specificity. An EMV of 12.5 kPa for the stiffest region of the appendix predicted true positive in 28, true negative in 11, and false negative in two cases. The EMV (≥12.5 kPa) yielded 93% sensitivity and 100% specificity. Conclusion Our results suggest that EMV by SWE helps distinguish an inflamed from a normal appendix. Given that SWE has high specificity, quantitative measurement of the elasticity of the appendix may provide complementary information, in addition to morphologic features on gray-scale US, in the diagnosis of appendicitis.
Entropy of a charged black hole in two dimensions without cutoff
Wontae Kim,Yong-Wan Kim,Young-Jai Park
Physics , 2007, DOI: 10.1103/PhysRevD.75.127501
Abstract: By introducing the generalized uncertainty principle (GUP) on quantum density states, we newly obtain a consistent entropy of a scalar field on the (1+1)-dimensional Maxwell-dilaton background without an artificial cutoff in contrast to the results of the brick wall model, which depend on the choice of the Hawking temperature for the extremal case.
Symplectic Quantization of the CP$^1$ Model with the Chern-Simons Term
Yong-Wan Kim,Young-Jai Park,Yongduk Kim
Physics , 1995,
Abstract: The symplectic formalism is fully employed to study the gauge-invariant CP$^1$ model with the Chern-Simons term. We consistently accommodate the CP$^1$ constraint at the Lagrangian level according to this formalism.
Entropy of 2+1 de Sitter space with the GUP
Wontae Kim,Yong-Wan Kim,Young-Jai Park
Physics , 2006,
Abstract: By introducing the generalized uncertainty principle (GUP) on the quantum state density, we calculate the statistical entropy of a scalar field on the background of (2+1)-dimensional de Sitter space without artificial cutoff. The desired entropy proportional to the horizon perimeter is obtained.
Entropy of the Randall-Sundrum brane world with the generalized uncertainty principle
Wontae Kim,Yong-Wan Kim,Young-Jai Park
Physics , 2006, DOI: 10.1103/PhysRevD.74.104001
Abstract: By introducing the generalized uncertainty principle, we calculate the entropy of the bulk scalar field on the Randall-Sundrum brane background without any cutoff. We obtain the entropy of the massive scalar field proportional to the horizon area. Here, we observe that the mass contribution to the entropy exists in contrast to all previous results, which is independent of the mass of the scalar field, of the usual black hole cases with the generalized uncertainty principle.
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