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An experimental system was developed to evaluate the fuel injection parts of a gasoline direct injection engine. An AC motor and an inverter were used to rotate the camshaft in the engine cylinder head. A single plunger high-pressure fuel pump (HPFP) driven by a square cam at the end of the camshaft was used in the gasoline direct injection engine. The rotation position of the square cam was measured by a rotary encoder. The developed system allows control of the camshaft rotation speed, the HPFP pressure control valve (PCV) opening and closing timing, and the fuel injection duration, which are three important factors affecting the fuel rail pressure (FRP). It is confirmed that the fuel rail pressure can be made to vary wit different combinations of these three factors. By using the experimental system developed in this study, the fuel rail pressure can be effectively controlled in the range of 3 MPa to 20 MPa. The most influential factor for control of the fuel rail pressure was the HPFP PCV opening and closing timings. With the proposed using the experimental system, the rail pressure, fuel rail pressure wave characteristics, and the injector drive characteristics can all be assessed under various fuel injection conditions.

A new experimental system was developed to measure the cumulative injected fuel mass (CIFM) according to the driving time during the operation of a gasoline injector in an actual vehicle driving condition. An algorithm was developed to calculate the fuel injection timing and injection duration based on engine speed, crank position, and intake air mass data. The intake air mass and engine speed under the vehicle driving conditions were simulated using a computer. In this study, phase I of the FTP-75 mode was used as the vehicle driving mode. GT-Suite® was used as the computer simulation software. The engine part load data, an automatic transmission shift map, torque converter data and various vehicle specifications were used as input data for the GT-Suite® simulation. The computer simulation time interval is 0.05 seconds. An injector drive signal corresponding to the fuel injection amount and timing calculated by the developed algorithm was generated in a FPGA DAQ system. The drive signal from the FPGA DAQ is supplied to the base terminal of the transistor to switch the injector drive voltage source to control the fuel injection. The real-time measurement of the CIFM was done using load cells, dynamic strain amplifiers, and the FPGA DAQ system. The CIFM was measured at intervals of 0.05 seconds using an experimental apparatus developed when the vehicle was driven in the FTP-75 mode. A low-pass filter was used to remove the noise due to the impact force of the fuel jet on the load cell when measuring the CIFM. Twenty-eight repetitive measurements were conducted for an uncertainty analysis of the measurement data. A normal distribution was used as the error function. The deviation % distribution from the average CIFM value was evaluated at the 95 % confidence level. The deviation % from the average CIFM value was 3 % at 50 seconds after the start of phase I of the FTP-75 mode and converged to 0.2 % at 512 seconds.

A new impulse-type swirl meter that measures the swirl ratio (Rs) and flow coefficient (Cfmean) during an intake air process for the intake port of an engine cylinder head under unsteady flow conditions was developed. The camshaft of the cylinder head was directly rotated by a step motor, allowing the valve lift to be adjusted automatically with the camshaft profile in the newly developed swirl measurement system. The measurements of the swirl ratio and flow coefficient were automated using a FPGA-DAQ board and a computer. The rotational speeds of the camshaft were held constant at steps of 90, 120, 150, 180 and 210 rpm during the measurement. As the camshaft rotation speed increased, the values of Rs tended to decrease while those of Cfmean tended to increase, implying that Rs and Cfmean depend on the engine speed. These results should be considered in the design of an intake port. With the newly developed swirl measurement system, it is possible to measure Rs and Cfmean repeatedly in a very short time. The repetitive measurement results of Rs and Cfmean were statistically processed. Through an uncertainty analysis, the values of the upper and lower bounds of Rs and Cfmean can be calculated for each camshaft rotation speed.

The “2019 Automatic Speaker Verification Spoofing And Countermeasures Challenge” (ASVspoof) competition aimed to facilitate the design of highly accurate voice spoofing attack detection systems. the competition did not emphasize model complexity and latency requirements; such constraints are strict and integral in real-world deployment. Hence, most of the top performing solutions from the competition all used an ensemble approach, and combined multiple complex deep learning models to maximize detection accuracy - this kind of approach would sit uneasily with real-world deployment constraints. To design a lightweight system, we combined the notions of skip connection (from ResNet) and max feature map (from Light CNN), and evaluated the accuracy of the system using the ASVspoof 2019 dataset. With an optimized constant Q transform (CQT) feature, our single model achieved a replay attack detection equal error rate (EER) of 0.37% on the evaluation set, surpassing the top ensemble system from the competition that achieved an EER of 0.39%.

A system capable of measuring the time-resolved fuel injection rate of an injector with a varying current pattern supplied to the injector was constructed. The control of the driving of a common rail diesel injector is achieved by controlling the current waveform supplied to the injector. In order to control various current waveforms flowing in the common rail injector, 80 V of power supplied to the injector was switched using a negative-positive-negative (NPN) 2N3055 transistor. The transistor-transistor logic (TTL) switching signal supplied to the base terminal of the NPN 2N3055 transistor was generated from the capture compare PWM (CCP) terminal of a microcontroller. The PWM signal generated from the CCP pin creates five patterns of waveforms by combining the peak-and-hold conditions. In the first part of the 1ms injection period, the duty ratio is 100 %, while the remaining part has a waveform with a greatly reduced duty ratio. The duty ratio used in this study was 10 % or 30 %. The time-resolved pressure wave caused by fuel injection in the Bosch method was repeatedly measured. For an uncertainty analysis, 39 repetitive measurements were taken per fuel injection condition. The rail pressures used in this study were 80, 110 and 140 MPa. With five pick-and-hold current waves supplied to the injector under a rail pressure condition, the time-resolved pressure waves caused by the fuel injection tended to be almost equal during the peak duration, whereas those during the hold duration differed. The duration of the pressure wave caused by the fuel injection is prolonged at a high hold current. When the common rail pressure is high, the slope of the pressure wave in the pick interval is steeper. A parameter that can effectively evaluate the optimal current control pattern for lower power consumption and thermal dissipation of the injector solenoid is also presented.

A gasoline injector rig which can measure cumulative injected fuel mass under a vehicle driving condition was developed.The measurement system consists of an engine control unit (ECU), data acquisition (DAQ) and injected fuel collection sys-tem using loadcells. By supplying reconstructed sensor signals which simulate the real vehicle’s sensor signals to the ECU,the ECU drives injectors as if they were driven in the vehicle. The vehicle’s performance was computer simulated by usingGT-Suite ® software based on both engine part load performance and automatic transmission shift map. Throttle valve position,engine and vehicle speed, air mass flow rate et al. were computer simulated. The used vehicle driving pattern for the sim-ulation was FTP-75 mode. For reconstructing the real vehicle sensor signals which are correspondent to the GT-Suite ® sim-ulated vehicle’s performance, the DAQ systems were used. The injected fuel was collected with mess cylinders. The collectedfuel mass in the mess cylinder with elapsed time after starting FTP-75 driving mode was measured using loadcells. Thedeveloped method shows highly improved performance in fast timing and accuracy of the cumulative injected fuel mass mea-surement under the vehicle driven condition.

The security of ARM TrustZone relies on the idea of splitting system-on-chip hardware and software into two worlds, namely normal world and secure world. In this paper, we report cross-world covert channels, which exploit the world-shared cache in the TrustZone architecture. We design a Prime+Count technique that only cares about how many cache sets or lines have been occupied. The coarser-grained approach significantly reduces the noise introduced by the pseudo-random replacement policy and world switching. Using our Prime+Count technique, we build covert channels in single-core and cross-core scenarios in the TrustZone architecture. Our results demonstrate that Prime+Count is an effective technique for enabling cross-world covert channels on ARM TrustZone.

The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100°C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100°C.

A driving vehicle performance which is driven by FTP-75 mode was simulated by computer. Throttle valve position,engine speed, air mass flow rate, fuel consumption et al. were computer simulated. A set of engine part load performancedata, automatic transmission shift map and vehicle specifications were used for the computer simulation. Throttle valve posi-tion, engine speed, air mass flow rate et al. measured for evaluating the computer simulation results by driving the vehiclewith FTP-75 mode on a chassis dynamometer. GT-Power ® software was used for the computer simulation of the driving vehi-cle performance. Experimental fuel consumption rate was measured by using an ECU HILS fuel injection system. The exper-imental data and simulation results were compared. The computer simulation of the driving vehicle performance predicts themeasured data well comparatively. 1. 서론 차량의 주행 성능 시험을 하지 않고도 컴퓨터 시뮬레이션으로 예측하는 연구가 활발히 진행되고 있다. 엔진의 흡배기 유동은1차원 유동 시뮬레이션으로 잘 예측할수 있다. 엔진 내의 연소 과정을 포함하는 성능 예측은3차원 컴퓨터 시뮬레이션을 (3-6)통해 예측하는 연구가 활발히 이루어지고 있다. 최근에는 흡배기과정은 1차원으로실린더 내의 연소 과정은 3차원으로 하여 통합 컴퓨터시뮬레이션 하는 연구도 (1,2)활발히 이루어지고 있다 . 차량ECU(engine control unit)와 관련된 성능 시험의경우 차량을 직접 운전하면서 이루어져야 하기 때문에시험에 많은 비용과 시간이 소요된다. ECU와 관련된차량 성능 시험에도 차량 시험을 직접 하지 않고 컴퓨터와 DAQ 보드를 도입한 ECU HILS(hard ware in theloop simulation) 적용하는 연구도 활발히 이루어지고 있다 . 차량이 특정 운전 모드로 운전할 때 가솔린 인젝터의 연료 분사량을 측정할 수 있는 ECU HILS 시스템이 (7)개발된 바가 있다 . 이 시스템은 실제 차량을 주행하지 않고도 DAQ보드와 컴퓨터로 차량에 입력된 실제센서 신호와 동일 전압 신호를 생성하여 ECU에 입력시켜 줌으로써 ECU가 인젝터를 구동하도록 하였다.한편 엔진 성능의 부분 부하 실험 데이터 및 차량 제원을 입력 데이터로 사용하여 차량의 주행 성능을 컴퓨터 시뮬레이션 하는 연구도 활발히 진행되고 있다.

Smoke emissions from light duty diesel vehicles were measured using light extinction method with the free acceleration test mode. The smoke emissions for each measurement cycle of the free acceleration method showed large variations according to driver`s pedal pushing pattern. The smoke values for each measurement cycle initially increased and reach a peak value. Integration of the smoke emissions with time for each measurement cycle was performed to get a representative smoke value which was obtained by averaging the integrated results. Two kinds of integration time range were used. One is range over the whole measurement cycle of the free acceleration method. The other is only the acceleration range in the measurement cycle. Overall, variation of the representative smoke values obtained by the integration method was reduced comparing to the traditional representative smoke value which was obtained from a peak smoke value over the measurement cycle. Ten vehicles of the same model with 2.5 liter diesel engines, and seven vehicles of the same model with 2.7 liter diesel engines, were tested using the free acceleration test method.

A diesel spray tip penetration was simulated with CFD by varying the compression ratio from the conventional compression ratio of a diesel engine, 18:1, to an ultra-high compression ratio of 100:1. The gas densities of the spray chambers for the compression ratios of 18:1 and 100:1 were 17.97 and 74.8 kg/m 3 , respectively. The spray tip penetration was CFD simulated by adopting both the ‘Gas jet spray model’, and ‘Normal gas jet profile model with breakup length formula’ (NGJBL model) into the KIVA-3V code. The spray tip penetration was CFD simulated for various spray patterns, such as single injection, pilot injection and split injection. The CFD simulation of the spray tip penetration with an 18:1 compression ratio was compared with a previous study with identical experimental conditions and showed that the ‘Gas jet spray model’ over predicted. The CFD simulation results with the ‘KIVA-3V Standard spray model’ and the NGJBL model were generally in good agreement with the experimental data. The spray tip penetration was CFD simulated with the NGJBL model with step-by-step increased compression ratio. The spray tip penetration rapidly decreased for the range of compression ratio of 18:1–45:1 as the compression ratio increases and the spray tip penetration did not change much with increasing the compression ratios in the range of 60:1–100:1. The CFD simulation results of the spray tip penetration, with respect to varying compression ratios, were generally in agreement with previous experimental studies.