Dohyung Kim

A Non-Cooperative User Authentication System in Robot Environments

For intelligent service robots, it is essential to recognize users in order to provide appropriate services to a correctly authenticated user. However, in robot environments in which users freely move around the robot, it is difficult to force users to cooperate for authentication as in traditional biometric security systems. This paper introduces a user authentication system that is designed to recognize users who are unconscious of a robot or of cameras. In the proposed system, biometrics and semi-biometrics are incorporated to cope with the limited applicability of traditional authentication techniques. Semi-biometrics indicates a set of features useful for discriminating persons, but only in the interested group of persons and in the interested frame of time. As a representative semi-biometric feature, body height and color characteristics of clothes are investigated. In particular, a novel method to measure body height with single camera is proposed. In addition, by incorporating tracking functionality, the system can maintain the user status information continuously, which is useful not only for recognition but also for finding a designated person.

Trace-driven HW/SW cosimulation using virtual synchronization technique

Poor performance of HW/SW cosimulation is mainly caused by synchronization requirement between component simulators. Virtual synchronization technique was proposed to remove the need of synchronization in cycle accurate cosimulation. But the previous execution-driven simulation based on virtual synchronization has limitations in the application area. In this paper, we propose a novel trace-driven HW/SW cosimulation using virtual synchronization technique. Through OS modeling and channel modeling, the proposed cosimulation technique could be applied more widely while improving the simulation performance further. Experiments with a DIVX player example prove the viability of the proposed technique.

Urinary phthalate metabolites among elementary school children of Korea: Sources, risks, and their association with oxidative stress marker

Phthalates have been used in a variety of consumer products and hence frequently been detected in humans. Children are susceptible to endocrine disrupting chemicals such as phthalates, but only limited information is available on the sources of exposure and potential adverse health effects among children. In this study, elementary school students (n=39, aged 9-12 years) were recruited in Seoul, and first void urine samples were collected twice in three-day intervals. Then six phthalate metabolites were analyzed by high performance liquid chromatography with triple quadrupole tandem mass spectrometry. In addition, malondialdehyde (MDA) as an oxidative stress marker was measured. A questionnaire was conducted and information on food consumption and the use of plastic packaging or storage materials was gathered. The concentrations of phthalate metabolites varied substantially by sampling time even within the same subject, but all target metabolites were detected in 100% of the samples with the highest geometric mean of 107 μg/g-creatinine for mono-n-butyl phthalate (MnBP). Urinary levels of mono-isobutyl phthalate (MiBP), and MnBP among Korean children were 8 and 3 times greater than those reported for US children, but those of monoethyl phthalate (MEP) were about 5 times lower than those of US children. Estimated phthalate intakes were generally in safe range, but in 3-8% of the participating children, the hazard quotients greater than one were noted. Urinary MDA concentrations were significantly associated with several metabolite levels after adjusting covariates in regression model. Consumption of dairy products or meat, and use of a plastic material were significantly associated with the DEHP metabolites or MnBP levels in multivariate model. The results of this study provide evidence of the association between phthalate exposure and oxidative stress especially among the early teenagers, and identified major sources that can be applied to development of management plan for phthalate exposure among children.

Fast and Accurate Cosimulation of MPSoC Using Trace-Driven Virtual Synchronization

As MPSoC has become an effective solution to ever-increasing design complexity of modern embedded systems, fast and accurate cosimulation of such systems is becoming a tough challenge. Cosimulation performance is in inverse proportion to the number of processor simulators in conventional cosimulation frameworks with lock-step synchronization schemes. To overcome this problem, we propose a novel time synchronization technique called trace-driven virtual synchronization. Having separate phases of event generation and event alignment in the cosimulation, time synchronization overhead is reduced to almost zero, boosting cosimulation speed while accuracy is almost preserved. In addition, this technique enables (1) a fast mixed level cosimulation where different abstraction level simulators are easily integrated communicating with traces and (2) a distributed parallel cosimulation where each simulator can run at its full speed without synchronizing with other simulator too frequently. We compared the performance and the accuracy with MaxSim, a well-known commercial System C simulation framework, and the proposed framework showed 11 times faster performance for H.263 decoder example, while the error was below 5%.

Virtual synchronization technique with OS modeling for fast and time-accurate cosimulation

Hardware/software cosimulation is the key process to shorten the design turn around time. We have proposed a novel technique, called virtual synchronization, for fast and time accurate cosimulation that involves interacting component simulators. We further extend the virtual synchronization technique with OS modeling for the case where multiple software tasks are executed under the supervision of a real-time operating system. The OS modeler models the RTOS overheads of context switching and tick interrupt handling as well as preemption behavior. While maintaining the timing accuracy to an acceptable level below a few percent, we could reduce the simulation time drastically compared with existing conservative approach by removing the need of time synchronization between simulators. It is confirmed with a preliminary experiment with a multimedia example that consists of four real-life tasks.

Fast Group Verification System for Intelligent Robot Service

The intelligent robot service is a promising area and based on many researches such as navigation, hardware control, image processing, and pattern recognition. The intelligent service robot provides the personalized service to a user without the help of a user. In case of the home robot service, the robot providing intelligent services needs a fast verification process which knows whether the user is a family member or non-family member to provide the differentiated services to each group member. In this paper, we develop the fast group verification system for providing intelligent robot services. The proposed system consists of face detection part, preprocessing and feature extraction part, and group verification part. Experimental results show that the proposed system achieves better accuracy and faster computational time than other well known methods and our system is suitable for the intelligent home robot service .

Fast and Time-Accurate Cosimulation with OS Scheduler Modeling

Hardware/Software cosimulation is the key process to shorten the design turn around time. We have proposed a novel technique, called virtual synchronization, for fast and time accurate cosimulation that involves component simulators running concurrently and interacting with each other. In this paper, we further extend the virtual synchronization technique with OS modeling for the case where multiple software tasks are executed under the supervision of a real-time operating system. The OS modeler models the RTOS overheads of context switching and tick interrupt handling as well as preemption behavior. While maintaining the timing accuracy to an acceptable level below a few percents, we could reduce the simulation time drastically compared with existent conservative approaches by removing the need of time synchronization between simulators. It is confirmed with a preliminary experiment on a multimedia example that consists of four real-life tasks.

Static analysis and automatic code synthesis of flexible FSM model

To describe complex control modules, the following four features are requested for extended FSM models: concurrency, compositionality, static analyzability, and automatic code synthesis capability. In our codesign environment we use a new FSM extension called flexible FSM model. It extends the expression capabilities by concurrency, hierarchy, and state variable while it maintains formal property. Because of formality and the structured nature of fFSM model, we can apply a static analysis method to find ambiguous behavior and synthesize software/hardware automatically, which is the main focus of this paper. We expect that the proposed technique can be applied to other compositional FSM extensions.

Combined data-driven and event-driven scheduling technique for fast distributed cosimulation

Fast distributed cosimulation is a challenging problem for embedded system design. The main theme of this paper is to increase the simulation speed by reducing the frequency of intersimulator communications, reducing the active duration of simulators, and utilizing the parallelism of component simulators. Those enhancements are accomplished by a proposed virtual synchronization technique, which combines event-driven and data-driven simulation methods. Experimental results show that the proposed technique can boost the cosimulation speed significantly compared with previous conservative approaches.

Virtual synchronization for fast distributed cosimulation of dataflow task graphs

Fast distributed cosimulation is a challenging problem for the embedded system design. The main theme of this paper is to increase simulation speed by reducing the frequency of inter-simulator communications, reducing the active duration of simulators and utilizing the parallelism of component simulators, which is accomplished by combining event-driven and data-driven simulation methods. The proposed technique is applicable when the simulated tasks follow dataflow execution semantics. Experimental results show that the proposed technique can boost the cosimulation speed significantly compared with the previous conservative approaches.