W Song

Publications (20)13.6 Total impact

• Article: SU-E-J-08: Dependence of Imaging Dose on Image Quality of Free-Breathing 3DCBCT of Moving Tumors.

  K Kauweloa, J Park, W Song
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  ABSTRACT: Purpose: To evaluate the impact on free-breathing CBCT (FBCBCT) image quality to properly visualize the motion range of moving tumors as a function of imaging dose. Methods: A multi-purpose body phantom (QUASAR) with a cylindrical cedar wood (density = 0.330g/cc), and an embedded 3-cm diameter Polystyrene sphere (density = 0.855g/cc) were used to simulate lung tumor motion. Varian Trilogy with OBI system was used to acquire CBCT images (high-dose mode: 125kVp, 80mA, 25ms/frame & low-dose mode: 110kVp, 20mA, 20ms/frame). As the FBCBCT projections were acquired, the sphere moved in accordance to 30 simulated sinusoidal patient breathing patterns using a programmable motion platform, which were given the parameters: inhalation-to-exhalation (I/E) ratio ranging from 1-0.2131, amplitudes of 1 and 3 cm, and periods 2, 4, and 6 seconds. Following the acquisition of FBCBCT images, the ITV contrast, defined as = (target pixel values inside the sphere - avg. pixel values in background)/(avg. pixel values in background), were calculated per image slice. Results: All parameters, I/E ratio, period, and amplitude did not seem to have much impact on the percentage change of the ITV contrast as a function of imaging dose. The percentage-change for all coronal images with a reduced ITV contrast when going from high-dose to low-dose was - 4.61 ± 3.04%, while the percentage-change for all coronal images with an ncreased ITV contrast when going from high-dose to low-dose, was 8.19 ± 3.61%. The overall percentage-change of all 30 coronal images was 5.21 ± 6.49%. Conclusions: We found that imaging dose did not have much impact on the visibility of the ITV volume, irrespective of the amplitude, I/E ratio, or period. Thus, it seems that low-dose FBCBCT may be just as suitable for clinical use while sparing a significant imaging dose to the patients.
  Medical Physics 06/2012; 39(6):3653. · 2.83 Impact Factor
• Article: TU-A-213CD-08: A Novel 2-Point Step Size Gradient Method for Regularized Total Variation Based CBCT Reconstructions.

  B Song, J Park, W Song
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  ABSTRACT: Purpose: To develop a novel, fast converging 2-point step size gradient method for CBCT reconstructions and show its clinical feasibility. Methods: The Barzilai-Borwein (BB) 2-point step size gradient method is getting recent attentions for accelerating Total Variation (TV) based CBCT reconstructions. In order to become truly viable for clinical applications, however, the iterative framework needs to ensure guaranteed convergence by carefully defining the cost function and the reconstruction algorithm. We propose a novel approach that combines an unconstrained BB (UBB) method and the gradient projection (GP) method enforcing non-negativity constraints. This way, the proposed GP-UBB algorithm inherits both the fast converging property of the UBB and the robust convergence property of GP. We applied this algorithm to both Shepp-Logan numerical phantom and a clinically-treated head-and-neck patient acquired from the TrueBeam system (Varian Medical Systems, Palo Alto, CA). Furthermore, we accelerated the reconstruction by implementing the algorithm on NVIDIA GTX 295 GPU card. Results: We first compared GPUBB with a recently proposed BB- based CBCT reconstruction method available in the literature and the well- known ASD-POCS algorithm using Shepp-Logan numerical phantom with 40 projections. As the iterations progress, GPUBB is found to converge much faster than the other two algorithms. Therefore, GPUBB commands superior image quality with less number of iterations. We then applied the algorithm to a clinically-treated head-and-neck patient. It was observed that, compared with the FDK algorithm with 364 projections, our GPUBB algorithm produces a visually equivalent quality CBCT image with only 120 projections, further supporting its practical value for realizing low-dose iterative CBCT reconstructions. Conclusions: By developing a novel, fast converging 2-step size gradient method for a CBCT reconstruction problem, we enhanced the clinical applicability of the compressive sensing based iterative reconstruction by guaranteeing convergence (i.e., consistent reconstructions) and accelerating the reconstruction speed (i.e., less number of iterations).
  Medical Physics 06/2012; 39(6):3892. · 2.83 Impact Factor
• Article: Sharp Reduction of Contact Resistivities by Effective Schottky Barrier Lowering With Silicides as Diffusion Sources

  Zhen Zhang, F. Pagette, C. D'Emic, B. Yang, C. Lavoie, Y. Zhu, M. Hopstaken, S. Maurer, C. Murray, M. Guillorn, [......], W. Song, V. Chhabra, G. Zuo, K.-L. Lee, A. Ozcan, J. Silverman, Q. Ouyang, D.-G. Park, W. Haensch, P.M. Solomon
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  ABSTRACT: An extremely low contact resistivity of 6-7 × 10^-9 Ω·cm² between Ni_0.9Pt_0.1Si and heavily doped Si is achieved through Schottky barrier engineering by dopant segregation. In this scheme, the implantation of B or As is performed into silicide followed by a low-temperature drive-in anneal. Reduction of effective Schottky barrier height is manifested in the elimination of nonlinearities in IV characteristics.
  IEEE Electron Device Letters 08/2010; · 2.85 Impact Factor
• Conference Proceeding: Development of a broadband shot noise measurement system at low-temperature for noise thermometry

  J. Park, M. Rehman, J.S. Choi, Z.G. Khim, S.W. Ryu, W. Song, Y. Chong
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  ABSTRACT: We report our experimental setup for the shot noise thermometry system at KRISS. Precision RF measurement setup in the frequency range of about 1 GHz has been installed in a He-3 refrigerator, which can be cooled down to 300 mK. The shot noise of Al-AlOx-Al tunnel junction, fabricated by two angle- evaporation technique, was measured and compared with theoretical curve. The inferred temperature from the noise curve agrees well with the measured temperature.
  Precision Electromagnetic Measurements (CPEM), 2010 Conference on; 07/2010
• Conference Proceeding: An Analytic Model of Atomic Service for Services Descriptions

  D. Chen, S. Han, M. Munro, A. Soomro, W. Song
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  ABSTRACT: The key question with Service Science is to be how to formulate a theoretic foundation for service description, service discovery and service composition in the context of basic service system development and the building of service architecture. However, the current research and development in the field of Service Science assumes that the mapping between the service requesters' requirements and the formal and executable services provided by the service providers (or developers) is straightforward, without a clear view of unbalance or even semantic conflict between a requirement very likely in NL and a service as a programming module. In this paper, we attempt to address this issue by proposing an analytic model of atomic service for service composition based on our initial analysis of service structures and manipulations.
  Service Sciences (ICSS), 2010 International Conference on; 06/2010
• Source

  Available from: toronto.edu

  Conference Proceeding: Negative-resistance read and write schemes for STT-MRAM in 0.13µm CMOS

  D. Halupka, S. Huda, W. Song, A. Sheikholeslami, K. Tsunoda, C. Yoshida, M. Aoki
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  ABSTRACT: We present a negative-resistance read scheme and write scheme for spin-torque-transfer (STT) MRAM. A negative resistance shunting an STT-MRAM cell performs a non-destructive read operation, and saves power during write compared with the conventional scheme. Measurements show an 8 ns non-destructive read-access time and an average write power savings of 10.5% for a 16 kb STTMRAM fabricated in 0.13 μm CMOS using a CoFeB/MgO/CoFeB MTJ.
  Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2010 IEEE International; 03/2010
• Article: Fast method for precoding and decoding of distributive multi-input multi-output channels in relay-based decode-and-forward cooperative wireless networks

  M.H. Lee, M.M. Matalgah, W. Song
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  ABSTRACT: It is well-known that the performance of the relay-based decode-and-forward (DF) cooperative networks outperforms the performance of the amplify-and-forward cooperative networks. However, this performance improvement is accomplished at the expense of adding more signal processing complexity (precoding/decoding) at each relay node. In this study, the authors tackle this signal processing complexity issue by proposing a Jacket-based fast method for reducing the precoding/decoding complexity in terms of time computation. Jacket transforms have shown to find applications in signal processing and coding theory. Jacket transforms are defined to be n × n matrices A =( a _jk) over a field F with the property AA ^¿= nI _n, where A ^¿ is the transpose matrix of the element-wise inverse of A , that is, A ^¿=( a _kj ^-1), which generalise Hadamard transforms and centre weighted Hadamard transforms. In particular, exploiting the Jacket transform properties, the authors propose a new eigenvalue decomposition (EVD) method with application in precoding and decoding of distributive multi-input multi-output channels in relay-based DF cooperative wireless networks in which the transmission is based on using single-symbol decodable space-time block codes. The authors show that the proposed Jacket-based method of EVD has significant reduction in its computational time as compared to the conventional-based EVD method. Performance in terms of computational time reduction is evaluated quantitatively through mathematical analysis and numerical results.
  IET Communications 02/2010; · 0.83 Impact Factor
• Conference Proceeding: Matchmaking Using Natural Language Descriptions: Linking Customers with Enterprise Service Descriptions

  J. Geldart, W. Song, Yang Li
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  ABSTRACT: A novel architecture is presented for the matching of Web-services based on the extraction of interpretation graphs from natural language text. The graphs of candidate services are compared to that of the query using a numerical node-node similarity calculation based on the structure of the graphs. The similarity score of their best alignment with the query may then be used to rank the candidates.
  Computer Software and Applications Conference, 2009. COMPSAC '09. 33rd Annual IEEE International; 08/2009
• Article: Improvements to seamless vertical handover between mobile WiMAX and 3GPP UTRAN through the evolved packet core

  W. Song, Jong-Moon Chung, Daeyoung Lee, Chaegwon Lim, Sungho Choi, Taesun Yeoum
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  ABSTRACT: Recent mobile devices are integrated with multiple network interfaces. Users want their devices connected to the network anytime anywhere. It is highly feasible for a user to change connection to another network for users that leave the service area of its current serving network, where handover needs to be executed seamlessly such that ongoing service sessions are not interrupted. The handover operation not only requires switching the interfaces within a device but also involves seamless reconfiguration of the supporting networks. In this article, an improved IP-based vertical handover technology for mobile WiMAX , 3GPP legacy systems (i.e., Global System for Mobile communications and Universal Mobile Telecommunications System), and 3G Long Term Evolution is presented, which is based on existing optimized handover techniques between mobile WiMAX and 3GPP accesses. Formerly proposed 3GPP WiMAX optimized VHO solutions introduced new elements, such as the forward attachment function and access network discovery and selection function. The ANDSF supports the discovery of target access, and the FAF provides the functionality that authenticates the UE before the execution of VHO. However, the previous technique has limitations that result in data loss and abnormal disconnection to the source access. This article provides a solution by introducing an additional network element called the data forwarding function (DFF) that eliminates the data loss during VHO execution. In addition, the DFF resolves the problem of abrupt disconnection to the source network. The simulation results show that the proposed VHO technique is effective in minimizing data loss during VHO execution between mobile WiMAX and 3GPP networks. As the proposed solution of this article is an IP based handover solution, it can be similarly applied to other communication networks.
  IEEE Communications Magazine 05/2009; · 3.79 Impact Factor
• Conference Proceeding: A Web of Active Knowledge

  J. Geldart, S. Cummins, W. Song
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  ABSTRACT: This paper outlines a new model for the Web inspired by recent research into cognitive science. It is argued that the trend towards decentralisation requires a change from a typical client-server meta-model to one based on the idea of communicating information systems. It is further argued that to accomplish this, one must accept the idea of information as dynamic and embodied. The meta-model described is then applied to a typical existing information systems based on the Semantic Web 'wedding cake'.
  Semantics, Knowledge and Grid, 2008. SKG '08. Fourth International Conference on; 01/2009
• Conference Proceeding: Structured NL Representation for Bridging the Knowledge Gap in Semantic Web Services

  J. Geldart, W. Song
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  ABSTRACT: The traditional "publish-find-bind" architecture for Web services paid little attention to the problem of communication and knowledge sharing between the service providers and the service consumers. This problem is very important because, in order to discover required services effectively and efficiently, the consumers need to know more about the published services. We should consider how customers represent their requirements and how service providers represent their services, and hence to bridge the knowledge gap between the service providers and the service consumers. This paper investigates the use of structured description and representation of natural language in the matchmaking of web-services with customer requirements. A semantic framework for the representation of such descriptions is motivated based upon the limitations of current approaches. A matchmaking algorithm is given along with a concrete example of how the matchmaking process may be applied.
  e-Business Engineering, 2008. ICEBE '08. IEEE International Conference on; 11/2008
• Conference Proceeding: Setup of shot noise measurement in a tunnel junction for noise thermometry

  W. Song, Y. Chong, K.-T. Kim
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  ABSTRACT: We report our development of a low-temperature shot noise measurement set-up for noise thermometry. We have constructed an experimental set-up for measuring shot noise in the frequency range of 700-1000 MHz. We have fabricated metallic tunnel-junction devices consisting of Al-AlO_x-Al by two angle-evaporation method. The current-voltage characteristic of the tunnel junction showed an ohmic behavior up to bias voltage of ~3k_BT/e at room temperature. Also, the characteristics of RF components including RF amplifiers, circulators, directional couplers were investigated.
  Precision Electromagnetic Measurements Digest, 2008. CPEM 2008. Conference on; 07/2008
• Conference Proceeding: Evolutionary Recognition of Corridor and Turning using Adaptive Model with 3D Structure

  H. Liu, Z. Zhang, W. Song, Y. Mae, M. Minami, A. Seiji
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  ABSTRACT: The paper describes a new method for recognizing corridors for autonomous mobile robot. The method detects the edge markers of a corridor based on the genetic-algorithm (GA) and 3D model-based matching. The edge markers with distinct color are generally located at the bottom of the walls for human visual recognition. To recognize the edge markers and the branch of corridor stably and precisely, a set of 3D models of the corridor which change its model length in 3D space is utilized to adapt the variation of the appearance of the markers. The experimental results show the method is effective for real-time recognition of corridor and its branch
  SICE-ICASE, 2006. International Joint Conference; 11/2006
• Conference Proceeding: Evolutionary Head Pose Measurement by Improved Stereo Model Matching

  W. Song, M. Minami, Y. Mae
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  ABSTRACT: This paper presents a method to estimate the 3D pose of a human's head using two images input from two stereo cameras. The proposed method utilizes an evolutionary search technique of 1-Step genetic algorithm (1-Step GA) being improved to adapt for the real-time recognition in dynamic images and a fitness evaluation based on a matching stereo model. Here, the head position and orientation are detected simultaneously using the brightness distribution and color information of the input images. Moreover, the facial features, eyebrows and eyes, are also recognized to increase the robustness of head pose measurement. An improved robust recognition for mobile robot has been proposed which is very effective to remove the influence of the camera motion
  SICE-ICASE, 2006. International Joint Conference; 11/2006
• Conference Proceeding: Calculating the Dispersion Diagram using the Nonorthogonal FDTD Method

  W. Song, Y. Hao, C.G. Parini
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  ABSTRACT: This paper presents a nonorthogonal finite-difference time-domain (NFDTD) modelling of photonic bandgap (PBG) structures. The NFDTD method discretises the curved structures in a conformal way. As a result, when the curved elements or oblique surfaces are involved in the EBG structure, the NFDTD scheme requires much fewer cells compared with the conventional Yee's scheme. Consequently the requirement of the computer memory and the computation time can be reduced.
  Metamaterials for Microwave and (Sub) Millimetrewave Applications: Electromagnetic Bandgap and Double Negative Design, Structures, Devices and Experimental Validation, 2006. The Institution of Engineering and Technology Seminar on; 10/2006
• Article: Numerical modeling of on-body radio propagation channel

  Y Hao, A Alomainy, W Song, CG Parini, P Hall, Y Nechayev, C Constantinou
  IEEE AP-S International Symposium, Washington, DC, USA. 01/2005;
• Conference Proceeding: 3D position/orientation measurement using model-based matching method and GA: proposal of calculation method and evaluation

  W. Song, T. Natsume, M. Minami
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  ABSTRACT: This paper presents a vision-related technique for 3D position/orientation measurement. The proposed method utilizes the genetic algorithm (GA) and unprocessed grayscale image input from stereo-vision, in order to perform recognition of a target being imaged with known target object shape. In fact here, the problem to recognize the target shape and simultaneous detection of the position/orientation, is converted to an optimistic problem of a model-based evaluation function, named as surface-strips model-based fitness function that consists in the computation of the brightness difference between an internal surface and a contour-strips. In order to evaluate the proposed 3D recognition method, experiments by a robot manipulator equipped with two hand-eye cameras have been conducted to recognize a ball on a turning table. The results show its effectiveness of this method for real-time visual servoing by manipulator.
  SICE 2004 Annual Conference; 09/2004
• Article: Transmission line fault location for phase-to-earth fault using one-terminal data

  Q. Zhang, Y. Zhang, W. Song, Y. Yu
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  ABSTRACT: An accurate algorithm for the fault location of a single phase-to-earth fault on a two-parallel power transmission line is presented. The faulted phase circuit and the zero-sequence circuit of the two-parallel line are used as a fault location model, in which the source impedance of the remote end is not involved. The algorithm effectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. It embodies an accurate fault location by measuring only local data and is used in a procedure that provides the automatic determination of faulted types and phases, rather than requiring an engineer to specify them. Simulation results have demonstrated the validity of the algorithm under the condition of a phase-to-earth fault
  IEE Proceedings - Generation Transmission and Distribution 04/1999; · 0.48 Impact Factor
• Conference Proceeding: Fabrication of high efficiency CdTe thin film solar cells using electrodeposition

  W. Song, D. Mao, Y. Zhu, J. Tang, J.U. Trefny
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  ABSTRACT: The influences of CdTe and CdS film thicknesses and CdS pre-treatment on CdTe solar cell performances were investigated. The CdTe film thickness was varied from 2.2 to 5.3 μm. The CdS film thickness was varied from 700 Å to 2500 Å. The highest efficiencies were obtained with a CdTe thickness of 3.4 μm and a CdS thickness of 1500 Å. An increase of 2.7 mA/cm² in J_sc was observed as a result of CdCl₂ treatment of CdS, resulting from an improved spectral response in the wavelength range of 500-600 nm. CdCl₂ treatment of CdS affects CdTe-CdS interdiffusion and leads to differences in optical transmission of CdS films. X-ray diffraction studies indicated the full conversion of CdS into CdS_1-yTe_y ternary phase for films prepared with as-deposited CdS and very low concentration of CdS_1-yTe _y for films prepared with CdCl₂-treated CdS
  Photovoltaic Specialists Conference, 1996., Conference Record of the Twenty Fifth IEEE; 06/1996
• Article: Protective effects of isovolumic hemodilution and Danshen solutin on ischemic reperfused myocardium

  L. Wang, Y. Zhang, W. Song, B. Wang
  Biorheology 01/1995; 32(2):275-275. · 1.93 Impact Factor