• Journal of Korean Institute of Industrial Engineers
• /
• v.8 no.2
• /
• pp.3-14
• /
• 1982

The purpose of this study is to establish the function of a sub-system for System Alternatives Feasibility Estimation (SAFE) in R & D Project Planning Phase (RDPPL). It is the fundamental function of the RDPPL/SAFE that selected an optimal planning system alternative of all, considered at RDPPL/SAS, by logical means in view of feasibility. In this paper, improving the function of RDPPL/SAFE, mathmatical models in order to quantify methods determining and integrating the feasibility funtion in each terminal system with a multi-stage process are examined.

• ETRI Journal
• /
• v.42 no.4
• /
• pp.468-479
• /
• 2020

The proposed AI processor architecture has high throughput for accelerating the neural network and reduces the external memory bandwidth required for processing the neural network. For achieving high throughput, the proposed super thread core (STC) includes 128 × 128 nano cores operating at the clock frequency of 1.2 GHz. The function-safe architecture is proposed for a fault-tolerance system such as an electronics system for autonomous cars. The general-purpose processor (GPP) core is integrated with STC for controlling the STC and processing the AI algorithm. It has a self-recovering cache and dynamic lockstep function. The function-safe design has proved the fault performance has ASIL D of ISO26262 standard fault tolerance levels. Therefore, the entire AI processor is fabricated via the 28-nm CMOS process as a prototype chip. Its peak computing performance is 40 TFLOPS at 1.2 GHz with the supply voltage of 1.1 V. The measured energy efficiency is 1.3 TOPS/W. A GPP for control with a function-safe design can have ISO26262 ASIL-D with the single-point fault-tolerance rate of 99.64%.

• The Journal of Korea Robotics Society
• /
• v.17 no.1
• /
• pp.76-85
• /
• 2022

One of the most fundamental challenges when designing controllers for dynamic systems is the adjustment of controller parameters. Usually the system model is used to get the initial controller, but eventually the controller parameters must be manually adjusted in the real system to achieve the best performance. To avoid this manual tuning step, data-driven methods such as machine learning were used. Recently, reinforcement learning became one alternative of this problem to be considered as an agent learns policies in large state space with trial-and-error Markov Decision Process (MDP) which is widely used in the field of robotics. However, on initial training step, as an agent tries to explore to the new state space with random action and acts directly on the controller parameters in real systems, MDP can lead the system safety-critical system failures. Therefore, the issue of 'safe exploration' became important. In this paper we meet 'safe exploration' condition with Control Barrier Function (CBF) which converts direct constraints on the state space to the implicit constraint of the control inputs. Given an initial low-performance controller, it automatically optimizes the parameters of the control law while ensuring safety by the CBF so that the agent can learn how to predict and control unknown and often stochastic environments. Simulation results on a quadrotor UAV indicate that the proposed method can safely optimize controller parameters quickly and automatically.

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.1
• /
• pp.48-53
• /
• 2021

The purpose of this study is to establish a crime prevention system through the Crime Prevention Through Environmental Design (CPTED). The research method went through the double diamond process and discovered the user's needs through the persona analysis. The most representative features are the functions that informs users of the safe and optimal route, checks the presence of streetlights or cctvs in real time to update them, and allows people with similar routs to return home together. It is a function to help safe return home with the help of an autonomous method, and a self-defense function to protect themselves. Therefore, the application presented in this study was intended to be of great help when actually returning home by adding these new functions. In particular, we help users to return home most safely by recommending the best safe route. Through the persona analysis, research method which we had chosen, the needs of users were discovered and implemented in a design that reflected those needs and requirements.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.10
• /
• pp.895-903
• /
• 2016

Spaceborne imaging sensors require periodic calibrations using an on-board calibration device for an image quality of observation satellites. The on-board calibration device consists of a blackbody to provide uniform radiance temperatures and calibration mechanism with a function of stow and deploy to target the blackbody during the calibration. Among these devices, the calibration mechanism is required to implement a fail-safe function to prevent blocking of the main optical path when the mechanism stops at a certain position during on-orbit calibration. In addition, structural safety of the mechanical driving part of the mechanism within the launch environment must be guaranteed. In this study, we proposed a deploy/stow-type calibration mechanism that provides launch-lock and fail-safe function. The effectiveness of the functionality of the proposed mechanism was validated through functional test using engineering model.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.7
• /
• pp.682-687
• /
• 2011

Calibration mirror mechanism has been widely used for on-board calibration with black body. The calibration mirror is deployed to reflect the radiation energy from the black body to the image sensor for calibrating the sensor system. After the calibration, the calibration mirror is stowed not to hide a main optical path. It also has a fail-safe function which can stow the mirror by just removing the input power of motor when the calibration mirror is stopped at certain position during the calibration. In the present work, the operation concept, design, torque analysis and functional test results of the calibration mirror mechanism with the aforementioned function have been introduced and investigated.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.5
• /
• pp.137-144
• /
• 2000

In this paper, a longitudinal control of the lead vehicle for a platoon in IVHS Regulation Layer is proposed. The backstepping method has been used for the controller design. This method has an advantage in that its stability need not be proven since the controller is designed based on the Lyapunov Function. The control object is that the lead vehicle tracks a reference velocity and maintains a safe distance between the inter-platoons while the followers are keeping the speed of the lead vehicle of a platoon. The coordinate of system is transformed to a new coordinate system for its convenience to design controller. The new coordinate system is composed of error and new error variable. The error is the difference between the safe distance and the actual distance of inter-platoons. A new error variable is the difference between the velocity of vehicle and the estimated state of a system operated by the virtual input. The Lyapunov function is obtained based on the variables of new coordinate system. In the computer simulation, several cases have been studied such as when the lead vehicle is tracking the optimal speed. or a lead vehicle of the following platoon tracks the velocity of the previous platoon while maintaining a safe distance. Also a nonlinear engine time constant case has been investigated. All the simulation results show that the designed controller satisfies the control object sufficiently.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.8 no.3
• /
• pp.1-7
• /
• 2011

As the technologies of electronic device have advanced these days, most of mechanical systems are designed with electronic control unit to take advantage of control parameter adaption to operating conditions and firmware flexibilities as well. On-board diagnosis, which detects the system malfunction and identifies potential source of error with its own diagnostic criteria, and fail-safe that can switch the mode of operation in view of recognized error characteristics enables easy maintenance and troubleshooting as well as system protection. This paper dealt with the development of diagnosis and fail-safe function for proportional flow control valve. All type of errors related to valve control system components are investigated and assigned to a specific hexadecimal codes. Cumulative error detection algorithm is applied in order for the sensitivity and reliability to be appropriate. Embedded simulator which runs simultaneously with system program provides the virtual error simulation environment for expeditious development of error detection algorithm. The diagnosis function was verified both with solenoid valve and embedded simulator test and it will enhance the valve control system monitoring function.

• Korean Journal of Organic Agriculture
• /
• v.5 no.1
• /
• pp.45-66
• /
• 1996

In Korea there is still no basic standard for organic agriculture and organic farmers in Korea do not follow the minimum requirements of IFOAM basic standard Most of them just practice the organic agriculture applying organic fertilizer, commercial seed without legume, rotation and green manure. But they believe this system is a absolutely environmental friendly agricultural system and it produce a safe agricultural product since they are not aware of the basic standard of organic agriculture at all. The overuse of organic fertilizer by some organic farmer have caused some severe problems risk for nitrate and phosphate leaching. In soil profile showed the potential risk for nitrate and phosphate leaching. In the paper, it is discussed on the environmental friendly function and the safe vegetable production by european organic agriculture which keeps the internationally recognized basic standards of organic agriculture. Therefore it is strongly recommended that korean organic farmer have to follow the IFOAM it is strongly in order to practice the environmental agriculture and produce the safe food. And it is also necessary to introduce to Korea the basic standard of organic agriculture which coincides with IFOAM's and Codex of FAO/WHO immediately if they really want to practice an organic agriculture in the country.

• Journal of Navigation and Port Research
• /
• v.27 no.2
• /
• pp.103-109
• /
• 2003

Evaluating the risk of collision quantitatively plays a key role in developing the expert system of navigation and collision avoidance. This study analysed the existing methods of appraising the collision risk, examined the problem that are intrinsic to them, and developed a new approach to its evaluation by using the sech function as an alternative to them. This paper applied the new method in appraising the collision risk and suggested how to decide the safe range of ownship's action.