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This paper proposes a simple $1^{\mathrm {st}}$ -order disturbance observer (DO)-based optimal control (DOBOC) strategy for surface-mounted permanent magnet synchronous motor (SPMSM) drives. A detailed comparative analysis of three reduced-order (i.e., $1^{\mathrm {st}}$ , $2^{\mathrm {nd}}$ , and $3^{\mathrm {rd}}$ ) DOs has been presented in terms of structural complexity along with transient and steady-state performances. A simple $1^{\mathrm {st}}$ -order DOBOC is proposed with a considerably simple and easy gain tuning procedure without any complex equation and time-consuming weighting matrices selection while ensuring a competitive control performance. Also, the stability of three DOBOCs is proven using the Lyapunov function, which has not been carried out in the previous studies. Furthermore, this paper provides a detailed procedure to systematically select the controller and observer gains of three reduced-order (i.e., $1^{\mathrm {st}}$ , $2^{\mathrm {nd}}$ , and $3^{\mathrm {rd}}$ ) DOBOC by experiment. Comparative experiments are performed to confirm the feasibility of the proposed $1^{\mathrm {st}}$ -order DOBOC using a prototype SPMSM test-bed with a TI TMS320F28335 DSP. Finally, verification results and comparative table are presented to compare the speed tracking performance (e.g., transient response, undershoot (US), steady-state error (SSE), and robustness to load torque disturbances) of three reduced-order DOBOC methods under speed and load torque step-changes.

This paper proposes a nonlinear disturbance observer (NDO)-based sliding mode speed controller (SMSC) to guarantee the superior control performance in terms of robustness, fast transient response, and small steady-state error for a surface-mounted permanent magnet synchronous motor (SPMSM) drive. Generally, the control performance of the SPMSM drives can be degraded by disturbances, so an NDO with a proper disturbance rejection capability is proposed to appropriately improve the tracking performance of the SMSC designed for the SPMSM drives. Unlike the linear disturbance observers (LDOs), the proposed NDO can efficiently estimate the lumped disturbance such as uncertainties parameters and unmodeled dynamics by using the nonlinear design function. The proposed NDO rejects the complex disturbances as well as self-regulates the observer gains to increase the convergence rate. The feasibility of the proposed NDO-based SMSC is verified by using a MATLAB/Simulink software program and a prototype SPMSM drive system with a TI TMS320F28335 digital signal processor (DSP). The comparative results with a conventional LDO-based SMSC are analyzed under load torque disturbances and model uncertainties to prove the excellent performance of the proposed NDO-based SMSC.

Modern people do not have much time to take care of their health due to heavy workloads. Therefore, we propose a smart mirror system, through which people can take exercises at home and get corrections for their movements. The users' motions are sent to the server using Raspberry Pi. Once the server receives the video, it sends the correct movements back to the user. Upon receiving the correct movements, the feedback, which is provided from the Guide video, the user can compare their movements to it. The users can correct their motions by following the correct motions provided from the Guide video. The incorrect motion is determined by the gap of the angle of the user's joints from the Guide video. This proposed Smart mirror system is assumed to contribute to people's health due to its ease of use and greater accessibility.

Nowadays, social inequality is an important social problem. Donations are one of the many ways to improve social inequality. Donation is largely divided into sponsorship by individuals such as corporations and public administration. In the individual sponsorship, it is common to donate to a donation organization and to support the aid recipients by donation organization. Many people are reluctant to support to this donation because of the lack of transparency. In addition, many donation organizations lack transparent and formal administration due to lack of working capital. Therefore, this paper proposes a method to enhance personal transparency by enhancing the transparency of donation organizations and protecting the privacy of sponsors using blockchain that is a Hyperledger fabric. And We implement a blockchain network for the proposed system.

Deep neural networks (DNNs) computing has been rapidly moved from cloud to edge devices in many domains such as object recognition, natural language processing and video/image quality enhancement, etc. Neural network processing unit (NPU) leads a pervasive trend to accelerating neural network computation on edge devices. A NPU is a processor that is specialized for DNN algorithm computation. [4][5] Recently, a DNN based real-time video super resolution method which provides higher resolution video experience such as UHD from lower resolution input video, SD/HD/FHD etc.[2] However, it is difficult to apply DNN based super resolution because the algorithm consume high external memory bandwidth caused by huge input, intermediate and output data. In this paper, we describe our NPU architecture, called S-PIE (Samsung Perceptual Inference Engine) for super resolution application, and report our experience so far, including various components used for a verification framework of S-PIE.

ECD (Exact Cell Decomposition) based path planning is not applicable in curvilinear obstacles environment. Therefore, after the curvilinear obstacles are approximated to the polygons by using DP (Douglas-Peucker) algorithm, which is a polygon approximation algorithm, the ECD method is applied. However, there is a case of not including all the existing obstacles' area and ignoring the outer area, when it comes to the curvilinear obstacles, approximated to the polygons by using the DP algorithm. In this case, path planning of ECD method cannot guarantee the clearance. This paper proposes a CDP (Circumscribed DP) algorithm to solve this problem. The CDP algorithm has a disadvantage of having more inner area than the DP algorithm, but it can guarantee the clearance because of the fact the algorithm always has 0(%) of outer area (OA). In order to confirm this, the polygonal approximation of DP and CDP algorithms was compared in the same curvilinear obstacles and the result was as the following: When each e value is 0.05, 0.08, 0.11(m), each result of the inner area ratio (IA) was 2.45, 4.89, 7.19(%) by DP algorithm, 16.3, 18.39, 32.58(%) by CDP algorithm, and result of the outer area ratio (OA) was 0.7, 1.17, 1.54(%) by DP Algorithm, 0, 0, 0(%) by CDP Algorithm. Also, it can be confirmed that the CDP algorithm has always guaranteed for clearance.

3D packaging technology has been considered as one of the best candidates to improve the system performance by implementing high I/O density as well as providing shortest signal channel path with given package form factor. However, it is difficult to uniformly control the bonding thickness and the precisely align the bumps other than thermo compression (TC) bonding to enable 3D packaging. Moreover, high chip cost and possibly low productivity of TC bonding are main business reasons to prevent this attractive technology from prevailing the mass production environment. To address these well-known technical issues of TC bonding, non-conductive film are proposed for especially high vertical stack with small bump pitch and also minimum chip to chip distance required packages such as high bandwidth memory. In this article, we investigated key process parameters to understand how to optimize bonding process to ensure excellent joint quality for highly dense 3D packages products.

This paper presents a technique to achieve a high power density of a 1.8kW low output voltage, high current dc-dc converter for xEV application. Using a GaN-based transistor at 700kHz switching frequency, the size of the passive component can be greatly reduced. The concept of matrix planar transformer with flux cancellation is applied, resulting in a reduction of the transformer size. Topologies evaluation are performed to select the most suitable topology for achieving the size specification, and a phase-shift full-bridge converter with current-doubler rectifier is selected. A 5.63kW/L(92W/in3) power density is achieved. Simulation and experimental results from the proposed converter system prototype are provided.

Even though modern industry has been widely digitalized and automated, many printed matters aren't digitalized. And even printed matters are often scanned upside down. To check whether scanned matters is upside down or not, matters should be checked by human. This study will suggest an algorithm that checks scanned matter's direction automatically. With the help of Tesseract OCR engine and extract information of a scanned matter, it could be determined if it is scanned in right direction.

This paper deals with a novel method which can estimate the occurrence number of human chewing actions by the help of image processing technique. At first, the user's mouth is recognized by the help of Haar cascade classifiers for human face and mouth. And then, this mouth image is processed with our proposed algorithm which can counter the occurrence number of human chewing action and can also reset the counter by confirming the mouth openness for new meal consumption. The experimental results show that it can be applied to improve chewing habits for kids.

In recent years, Intelligent Assistant services have come out to respond to user requests or to perform certain functions. These services get the request input from users with natural ways such as voice or text. However, the biggest hurdle of this approach is that it is very difficult for users to know the scope of the service (feature or knowledge) and therefore it is difficult to deliver the right request. If the Intelligent Assistant suggests the proper features based on user's context or preference with users based on the natural language or voices, it could make users be familiar with Intelligent Assistant therefore it could make Intelligent Assistants be very widely used. In this paper, we proposed the architecture to make the user's interaction guide for the Intelligent Assistant. We used the plan recognition of the task network to make the candidates of the actions/answers based on the user's context. After making the candidates we used the filters to filtering the candidates and scored the candidates. Finally, we used the NLG/TTS to make the natural sentences to give the guide to the users. As a result, even without the user's request, we could give the guide utterance to the user.

Gamma-imaging system is of great interest to monitor the contamination of radioactive substances in a wide range of areas at nuclear power plants. The purpose of this study was to develop a compact gamma camera capable of detecting and imaging the radioactive sources present in contaminated area. The prototype of compact gamma camera with 73 × 99 mm2 FOV was composed of pinhole collimator, SiPM based detector and dedicated electronics. Flood image and energy spectrum were acquired to evaluate the performance of the prototype gamma camera. Energy linearity of the system was measured with 57Co, 133Ba, 54Mn, 22Na and 152Eu point sources. Spatial resolution and sensitivity of the prototype gamma camera were also measured. Each crystal pixel was clearly identified in the acquired flood histogram, average energy resolution of 384 crystals was 18.5 ± 1.5%. Adjusted R-squared value of linear fitting for ADC values was 0.99 in the range of 122 keV to 1408 keV. Spatial resolution and sensitivity were 12.4 mm and 753 cps/MBq at a distance of 1000 mm from the collimator. Preliminary experimental results showed its capability of use at nuclear power plants confronting radioactive sources emitting wide energy range of radiations.

Laser Range finder (LRF) is one of the promising sensors for mobile robot indoor navigation since it can give plentiful information by high accuracy, high resolution and high speed. But, many indoor environments have various kinds of transparent obstacles such as glass and they may lead to many noises when LRF is applied. Sometimes, these noises result in wrong positioning of obstacles and thereafter wrong action of the robot. Therefore, many other applications use not only LRF but also additional sonar-like sensors to cope with this problem. And, the use of these additional sensors makes the whole system to be more complex and more expensive. In this paper, a method to LRF noise filtering for transparent obstacle is addressed from the insight that human sensing mechanism uses the fusion of more data with different view directions or different measurement locations. And, the effectiveness of the proposed algorithm is evaluated by the real robot experiment.

A MR compatible PET insert has been developed in our group employing SiPM and a charge signal transmission method that transmits the charge signal of SiPM to subsequent electronics through 4 m long cables. The previously developed PET/MRI system, however, had several limitations, such as the instability of PET performance due to temperature variations inside PET gantry and the degradation of SNR in the MR image due to the inserted PET. The purpose of this study was to optimize the design of PET/MRI system to maintain a stable temperature inside the PET gantry and to minimize mutual interference between PET and MRI. The PET insert was composed of 9 PET detector blocks that were arranged in a circle around the subject with 390 mm diameter and 60 mm axial FOV. Each PET detector block was composed of a 4 × 8 array of detector modules consisted of 4 × 4 array of SiPM and 4 × 4 array of LYSO. The PET detectors were cooled using a water chiller system to compensate temperature fluctuations caused by eddy currents. PET analog electronics were enclosed in an aluminum box and located 50 cm apart from the MR bore. The FPGA-embedded DAQ and power supply were installed at outside MR room. PET performance was measured inside and outside MRI using spin echo and gradient echo sequences. MRI performance was evaluated with and without the PET insert. Human brain imaging was also acquired to evaluate the performance of simultaneous PET and MR imaging. No significant degradation of the PET performance caused by MR was observed when the PET was operated under various MR imaging sequences. The homogeneities and SNRs of MR images obtained with and without the PET insert installed inside the MR bore were similar and changed by only 1% and 3%, respectively. High quality simultaneous PET and MR images of human brain were successfully acquired. Experimental results indicate that simultaneous PET and MR imaging is feasible without considerable mutual interference between PET and MRI by employing the PET/MRI proposed in this study.

SIMULTANEOUS functional and anatomical imaging using PET-MR system has been reported to be useful in preclinical research to investigate various in vivo biological processes [1-3]. The purpose of this study was to develop a MR compatible small animal PET insert and to evaluate the performance of the developed PET and the influence of the PET on MRI performance.

Despite the rapid growth of green vehicle markets in recent years, its components including control units are still very expensive compared to those on the gasoline/diesel powered vehicle. In order to reduce costs and save more space on the vehicle, integration technology is required to develop. This paper proposes the development progress and optimization of integrated Power Control Unit of Hybrid/Electric vehicle.

This paper illustrates the implementation of a speech-to-speech translation humanoid robot in the domain of medical care. At this stage, the proposed system is a one-way translation that is designed to help English speaking patients describe their symptoms to Korean doctors or nurses. A humanoid robot is useful because it can be extended to reach out to people in need first and may substitute the role of human workers, unlike laptops or tablets. The system consists of three main parts - speech recognition, English-Korean translation, and Korean speech generation. It utilizes CMU Sphinx-4 as a speech recognition tool. English-Korean translation in this system is based on the rule-based translation. The success rate of the translation shows reliable results from an experiment with a closed scenario.

A positron emission tomography (PET) detector for neuro-imaging is required to have high signal-to-noise ratio (SNR) as well as high spatial resolution. Time-of-flight (TOF) information can improve SNR of PET by localizing a positron annihilation point. The purpose of this study is to develop a TOF detector for brain PET having spatial resolution ≤ 2 mm and CTR ≤ 330 ps.

Although GAPD has been reported to provide good performance as a PET photosensor, it has significant temperature-dependent gain variations causing the drifting of photo-peaks and hence deteriorating the detection sensitivity. Therefore, it is necessary to develop a realtime photo-peak searching method to ensure to apply proper energy window and to sustain uniform sensitivity. This study presented a new realtime photo-peak search method implemented on FPGA. The method used detected gamma-ray energy information to search photo-peak without calculation of direction and step size. The direction was determinated by acquiring a gamma-ray count that has energy within a search range nearby a searching point, and the step size was fixed. The method used two searching points, valley point and peak point, which could be stored in a few registers in FPGA. The performance was evaluated with the simulated energy spectrum and the experimental data acquired with LYSO-MPPC detector. The photo-peak searching error was 3.1±5.5 keV with the simulated energy spectrum with 11% energy resolution, 7.0±7.1 keV with the experimental data. The proposed method successfully found the photo-peak in both the simulation and the experimental study. It is expected that the method could be a powerful realtime searching method to implement on digital circuit for radiation counting system. Since the performance of the searching method depended on searching step size, energy detection range and initial searching point, additional experimental study for the optimization of the parameter will be performed.

We developed MR insertable small animal PET utilizing high resolution event positioning circuit and charge signal transmission approach. A further study will be performed to improve PET image quality by applying correction algorithms and to evaluate the performance of small animal PET mounted inside the MR bore to simultaneously acquire hybrid PET/MR images.

In this paper, an ASK (amplitude shift keying) modulator with DGS (defected ground structure) is proposed for 900-MHz RFID (radio frequency identification) system. Proposed variable DGS resonator with a varactor diode will be able to adjust the resonance frequency to achieve the ASK modulation. The variable resonance characteristics can be obtained by controlling capacitance of varactor diode, placed on the defected ground. In order to clarify corresponding method, we manufactured RFID system board using variable DGS resonator and measured corresponding performance. As almost 93% of extracted data from modulation index characteristic is satisfied with both EPC class-1 Gen2 Type-B and Type-C standard protocols, we obtained stable tag response of RFID system.

The space borne X-band 2-axis gimbal antenna needs frequency re-uses techniques by dual circular polarization for the very high data transmission. The gimbal antenna consists of 2-axis driving mechanism, high efficient horn antenna, very low loss non-contact type RF transmission line of coaxial type rotary joint. This paper designed high efficient horn antenna and very low loss non-contact type RF transmission line of coaxial type rotary joint and 2-axis driving mechanism.

In this paper, we proposed a novel SCR (Silicon Controlled Rectifier)-based ESD (Electrostatic Discharge) protection circuit for I/O and power clamp. HHVSCR (High Holding Voltage SCR) has a high holding voltage and low trigger voltage characteristics than conventional SCR. And advanced HHVSCR is proposed for high voltage application. These characteristics enable to have latch-up immunity under normal operating conditions as well as superior full chip ESD protection. Proposed ESD protection circuits are verified and compared by TCAD simulation. As a result of simulation, holding voltage increases with different design parameters. The holding voltage of HHVSCR changes from 3V to 4.83V. On the other hands, the holding voltage of Advanced HHVSCR changes from 4.61V to 8.75V. The trigger voltage of HHVSCR has about 8~9V whereas Advanced HHVSCR varies from 27.3V to 32.7V due to different breakdown occurrence.

The purpose of this study was to develop a dual-modality PET/MRI with insertable PET for simultaneous imaging of human brain. The PET insert consisted of 18 detector blocks arranged in a ring of 390 mm diameter with 60 mm axial FOV. Each detector block was composed of 4 × 4 matrix of detector modules, each of which consisted of a 4 × 4 array LYSO coupled to a 4 × 4 GAPD array. The PET gantry was shielded with gold-plated conductive fabric tapes with thickness of 0.1 mm. The charge signals of PET detector transferred via 4 m long flat cables were fed into the position decoder circuit. The flat cables were shielded with a mesh-type aluminum sheet with 0.24 mm thickness. The position decoder circuit and FPGA-embedded DAQ modules were enclosed in an aluminum box with 10 mm thickness and located at the rear of the MR bore inside MRI room. A 3-T human MRI system with a Larmor frequency of 123.7 MHz and bore inner diameter of 60 cm was used for PET/MRI hybrid system. A custom-made radio frequency (RF) coil with inner diameter of 25 cm was fabricated. The PET was positioned between gradient and the RF coils. PET performance was measured outside and inside MRI scanner with spin echo, turbo spin echo and gradient echo sequences. SNR and of MR phantom image were also measured with and without PET insert. The stability of developed PET insert was evaluated and simultaneous PET and MR images of brain phantom were acquired. No significant degradation of the PET performance caused by MR was observed when the PET was operated with various MR imaging sequences. Uniformity and SNR of MR phantom image were degraded about 1% and 7% by the PET insert, respectively. The change of gain of PET detector was

The improvement of sensitivity in neuro-PET is crucial because it can reduce the scan time and/or the radiation dose. In this study, we proposed a novel PET detector design that combined conical shape detector with cylindrical one (conical PET) to obtain high sensitivity. The sensitivity as a function of the oblique angle and the ratio of the conical to cylindrical portion was estimated to optimize the design of conical PET using Monte Carlo simulation tool, GATE v6.2. An axial sensitivity and misplacement rate by penetration of γ rays were also estimated to evaluate the performance of the conical PET. The sensitivity was improved by 36% at the center of axial FOV. This value was similar to the analytically calculated value. The misplacement rate of conical PET was about 5% higher than the conventional PET. The results of this study demonstrated the conical detector proposed in this study could provide subsequent improvement in sensitivity which could allow to design high sensitivity PET for brain imaging.

In a PET detector using pixelated scintillator, a 511 keV annihilation photon incident on a pixel might deposit part of its energy and could be almost simultaneously detected in several adjacent pixels. These inter-crystal scattered events are typically considered invalid events in PET if their energies are not within the energy window. The purpose of this study is to develop a new position decoder circuit (PDC) capable of multiplexing a number of channels and recovering the inter-crystal scattered events to improve the sensitivity of the PET detector consisting of Geiger-mode avalanche photodiode (GAPD) arrays. The PET detector module consisted of a 4 × 4 array of LYSO crystals and a 4 × 4 array of 3 × 3 mm2 GAPDs. The output signals from 2 detector modules were transmitted to the PDC which amplified the signals, selected the two fastest amplified signals among 32 signals and output their digital addresses and analog pulses. The PDC outputs were fed into a data acquisition system and arrival time, energy and address of the outputs were estimated and stored in list mode format. The recovery of inter-crystal scattered events was carried out by using the energy and time criteria in post-processing. The average energy resolution of a detector module at 511 keV was 17.1 ± 1.1% and 17.8 ± 1.3% before and after the recovery of inter-crystal scattered events, respectively. The increase in photopeak counts ranged from 5.3% to 26.7% depending on the pixel and source positions. The results of this study show that the new PDC design is useful to increase the sensitivity of PET detector through the recovery of inter-crystal scattered events while maintaining its high channel reduction ratio.

The hybrid PET and MRI which could provide information on functional and structural images was required to improve the mutual compatibility. The purpose of this study is to propose a new electromagnetic shielding material; Au plated conductive fabric (Au PCF) tape, and evaluated shielding effectiveness of Au PCF tape and Cu foil for insertable PET in hybrid PET/MRI. The PET consisted of 18 detector blocks arranged in a ring of 390 mm diameter and 60 mm axial FOV. Each detector block was constituted of 4 × 4 matrix of detector module, each of which consisted of a 4 × 4 array LSO coupled to a 4 × 4 GAPD array. The PET gantry was positioned in center of two 3T Human MRIs and shielded with Au PCF tape or Cu foil. The PET readout electronics were enclosed in an aluminum shielding box behind MRI. RF head coil was also shielded with Au PCF tape or Cu foil to improve shielding effects. The MR image of cylindrical water phantom was acquired to evaluate MR image homogeneity and signal-to-noise ratio (SNR) with various MR sequences. The homogeneity of MR Images was similar without and with PET gantry shielded with Au PCF tape and Cu foil. SNRs measured without and with PET gantry shielded with Au PCF tape have small differences (

A Geiger-mode avalanche photodiode (GAPD) is actively studied silicon-based photo-detector that is a promising photo-sensor for PET because of various advantages, such as gain, compact size, fast response and magnetic field insensitivity. Previously, we have developed a brain PET employing GAPD-based PET detector block, charge signal transmission method via 4 m long cable, high density position decoder circuit (PDC) and digital signal processing with FPGA-embedded ADC boards. The purpose of this study was to evaluate the performance of the developed brain PET system. The PET consists of 18 detector blocks, each of which comprises 4 × 4 GAPDs and 4 × 4 LYSO arrays. The output signals of PET detector block were amplified by preamplifier circuits and then transferred to the PDC. The PDC was used to identify the one valid channel among 256 channels of PET detector blocks and to output digital address analog pulse corresponding to the valid channel. Three FPGA-embedded DAQ boards were used to digitize analog output signals of the PDCs. The gain uniformity, spatial resolution, sensitivity, stability and count rate performance were measured. Tomographic image of 3D Hoffman brain phantom was also acquired to evaluate imaging capability of the PET. Normalized average photo-peak positions of PET detector block were 1.0 ± 0.14 without the gain correction and 1.0 ± 0.03 with the gain correction. Spatial resolution and sensitivity in the center of field of view were 3.1 mm and 0.8%, respectively. The average scatter fraction was 0.4 with lower energy threshold of 350 keV. The maximum true count rate and maximum NECR were measured 43.3 kcps and 6.5 kcps at an activity concentration of 16.7 kBq/ml and 5.5 kBq/ml, respectively. Activity distribution patterns between white and gray matter in the Hoffman brain phantom were well imaged. These results demonstrate that the developed GAPD based brain PET system is useful for high quality brain PET imaging.

We present verification and debugging of highly optimized executable code that is generated from C source code to run on CGRA (Coarse-Grained Reconfigurable Array). To generate the executable code, the CGRA compiler uses software pipelining technique that maps instructions in a loop body to multiple FUs (functional units) of CGRA for concurrent execution. Often, the programmer chooses to use aggressive optimization as a way to obtain highly performing executable code. For example, the programmer may turn off memory dependence check in order to suppress false dependence that would otherwise result in overly conservative, therefore poorly performing, executable code. A trouble is that it is not easy to verify correctness of the resulting executable code. In this paper, we propose a method to verify CGRA executable code and to detect memory dependence violation if there occurs such violation and to provide source code position where the violation occurs. We use the behavior of VLIW code as a reference and compare it with the behavior of CGRA code. In order to guide the comparison, compiler-generated mapping table information is used.

We have reported the usefulness of a channel reduction circuit, called "position decoder circuit (PDC)" generating the digital address and analog pulse of an interacted channel among many PET detector outputs. However, in a previous study, we focused on the design of a POC dedicated to a GAPD-based PET detector with a fast scintillator. The goal of this study was to develop a PDC that could be generally utilized to the various PET detector modules having different physical properties. A PDC, based on two-stage (32:1 and 8:1) channel reduction architecture, was designed. The PDC consisted of: (1) GAPD bias voltage and signal gain adjustment circuits to correct the non-homogeneity and different characteristics of the input signals; (2) a low level discrimination circuit, to reject noise or scatter signals; (3) an analog signal delay and switch circuits to output an analog pulse corresponding to the interacted channel; and (4) a FPGA circuit to identify a valid channel and providing a digital address. Two different types of PET detector modules, LYSO-GAPD (high light output and fast decay time) and BGO-GAPD (low light output and slow decay time), were constructed to evaluate the functionality of the developed PDC. The developed PDC successfully identified the interacted channel. Channel address/analog pulse output signals were generated after 34 nsf 98 ns for LYSO-GAPD and 50 nsf 98 ns for BGO-GAPD compared with input signals, respectively. Measured energy and coincidence timing resolutions for LYSO-GAPD were 18.5% and 2.9 ns, respectively, and for BGO-GAPD, 20% and 7.8 ns, respectively. A hot-rod phantom image of the proof-of-principle PET system consisting of 8 pairs of PET detector modules was successfully acquired. Experimental results indicate that the PDC developed in this study is useful to identify a valid channel among a large number of readout channels of the PET detectors with different physical properties.

There has been great interest in the development of combined PET/MR, a useful tool for both functional and anatomic imaging. We have developed a proof-of-principle MR compatible PET, employing a design concept that uses GAPD arrays as a PET photo-sensor and charge signal transmission method for human brain imaging. The purpose of this study was to design the 2nd version of brain PET with an extended axial field-of-view (FOV) and to evaluate its initial performance. The PET consisted of 18 detector blocks arranged in a ring of 390 mm diameter with 60 mm axial FOV. Each detector block was composed of a 4 × 4 matrix of detector module, each of which consisted of a 4 × 4 array L YSO coupled to a 4-side tileable 4 × 4 GAPD array. The PET gantry was shielded with gold-plated conductive fabric tapes with a thickness of 0.1 mm. PET signals were fed into the position decoder circuit (PDC) generating the digital address and analog pulse of the one interacted channel among the 256 output channels of the detector block, using a 4 m long flat cable. Commercial DAQ modules were used to digitize analog output signals of the PDCs and to store the data in list mode format. The flat cable was shielded with a mesh-type aluminum sheet, which had a thickness of 0.24 mm. All electronics were enclosed in an aluminum box, which had a thickness of 10 mm, located outside the MR bore. Average energy and timing resolutions of the developed PET measured outside the MR room were 18.1±3.2% (n=4,608) and 3.6 ns, respectively. The sensitivity and spatial resolution were 1.2% and 3.1 mm at the center of the field of view, respectively. No significant degradations of PET performance and the uniformity of MR image were observed. Simultaneous PET and MR images of hot-rod phantom and cat brain were successfully acquired. Experimental results indicate that the high performance compact and lightweight PET insert for hybrid PET-MRI can be developed using GAPD arrays and charge signal transmission method.

With the emergence of the Smart phone, people can use Online Social Network Services ubiquitously, leading to a significant increase of the number of participants in online social networks. Under these circumstances, online users will require an intelligent and intuitive social relationship management system such as the ontology-driven browsing method. In this paper, to build a user-centered semantic social network and to represent entities and relationships with ontology to improve retrieval performance of the semantic social network, we will design our ontology extended from FOAF, RELATIONSHIP and propose a new method to compute closeness among friends using resources on social networks. Furthermore, we evaluate our ontology-driven browsing on via implementing a prototype system.

Recently, to overcome energy problems in networks, Low Power Idle(LPI) scheme was standardized by IEEE 802.3az Task Force Group in Sep. 30, 2010. However, most researches related LPI were focused on LAN such as Ethernet. In this paper, we evaluate performances of core router with LPI to analyze energy saving effect on OBS network. To do this, core router architecture with LPI which reduces energy consumption is proposed. The proposed architecture is comprised of control part of line card, a switch controller, BCP switch in Switching Control Unit(SCU), data transmission part of line card and burst switch fabric in switch block. In order to perform the LPI in core router, Sleep/wake controller controls line card from active to sleep state or vice versa depending on sleep/awake decision in traffic processer. The power consumption comparison and simulation results show that proposed architecture consume more energy about 1.3 times than conventional packet router. However, OBS core router with LPI can reduce energy consumption up to maximum 60 % at low offered load.

Recently, Ethernet Passive Optical Network (EPON) with sleep mode has been actively investigated to improve energy conservation in the broadband access network. EPON with cyclic sleep mode transmits up/downstream traffic at the same time and put into the sleep mode at idle time in Optical Network Unit (ONU). However, QoS requirement can be violated by the cyclic sleep mode. In this paper, we propose novel bandwidth allocation algorithm to maximize energy efficiency while satisfying QoS requirement. The main idea is to consider up/downstream traffic in order to determine suitable scheduling transmission period on Optical Line Terminal (OLT). To do this, it allocates bandwidth according to request from ONU, usually. However, when downstream traffic in OLT buffer exceeds predefined threshold, the proposed algorithm compares threshold to bandwidth request from ONU for reducing OLT traffic queuing delay. So, our proposed algorithm can satisfy both energy saving and QoS requirement. In order to evaluate the proposed algorithm, we perform simulation in terms of total and average sleep time of ONU, queuing delay of downstream traffic in OLT buffer.

The Low Power Idle (LPI) has been proposed by IEEE 802.3az Task Force to reduce energy consumption of network devices. Recently, many researches about the LPI have been progressing to maximize the sleep time and improve the performance of energy saving. However, most researches have not considered the effect of transition which causes additional energy consumption. The transition is a serious factor, which affect the performance of energy saving and QoS. Therefore, in this paper, we propose novel algorithms, called Wake Transition Decision(WTD) algorithms to reduce unnecessary transition in an OBS edge router with LPI. The Fixed Time based WTD algorithm(FT-WTD) reduces transition by waiting certain time before sleep transition. The Burst Length based WTD algorithm(BL-WTD) controls the unnecessary transition by keeping the active state of Tx module in an OBS edge router when burst length exceeds certain threshold. Simulation results show that not only approximately 30% of energy consumption can be decreased compared with exist LPI approach but also packet delay is kept within acceptable level by proposed algorithm.