• 대한산업공학회지
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• 제8권2호
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• pp.3-14
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• 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
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• 제42권4호
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• pp.468-479
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• 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%.

• 로봇학회논문지
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• 제17권1호
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• pp.76-85
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• 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.

• 반도체디스플레이기술학회지
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• 제20권1호
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• pp.48-53
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• 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.

• 한국항공우주학회지
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• 제44권10호
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• pp.895-903
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• 2016

우주용 영상센서의 비균일 출력특성 교정을 통한 영상품질향상을 목적으로 탑재교정장치가 요구된다. 탑재교정장치는 균일한 온도정보 제공을 위한 흑체를 비롯하여, 흑체로의 지향성 확보를 위하여 전개/수납 기능이 포함되는 교정 메커니즘으로 구성된다. 이 중, 교정 메커니즘은 궤도상에서 구동장치의 결함 발생 시 주광경로 확보를 위한 결함안전 기능이 요구된다. 추가적으로, 구동부에 대한 발사환경에서의 구조건전성 확보가 필수적이다. 본 논문에서는 단일장치로 발사환경 구속 및 결함안전 기능 구현이 가능한 전개수납형 교정 메커니즘을 제안하였다. 상기 제안한 메커니즘의 기능모델을 통한 동작 기능시험을 수행하여 설계의 유효성을 입증하였다.

• 한국항공우주학회지
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• 제39권7호
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• pp.682-687
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• 2011

일반적으로 탑재 교정을 위한 교정 반사경 구동장치는 교정임무 수행 시에는 주광경로 상의 전개위치로 반사경을 구동하며, 교정 후에는 주광경로와 이격된 수납위치로 반사경을 구동한다. 교정 반사경 구동장치의 결함 발생 시에는 반사경이 전개된 상태로 남아 주광경로를 차단하지 않도록 반사경을 강제 수납한다. 본 논문에서 제안한 결함 안전장치를 가지는 교정용 반사경 구동장치는 구동을 위한 스텝모터, 전개 및 수납 상태확인을 위한 마이크로 스위치, 베어링과 스프링의 기능을 동시에 갖는 피봇베어링 등으로 구성된다. 본 논문에서는 상기의 기능을 갖는 교정 반사경 구동장치 구현을 위한 구동장치 구성을 제안하였으며, 구성요소의 최적화 설계치를 도출하고 기능시험을 통해 결함안전 기능을 갖는 교정 반사경 구동장치의 유효성을 검증하였다.

• 한국정밀공학회지
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• 제17권5호
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• pp.137-144
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• 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.

• 유공압시스템학회논문집
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• 제8권3호
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• pp.1-7
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• 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.

• 한국유기농업학회지
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• 제5권1호
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• pp.45-66
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• 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.

• 한국항해항만학회지
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• 제27권2호
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• pp.103-109
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• 2003

충돌위험도의 정량적인 평가는 항해 충돌방지 전문가 시스템 개발에 있어서 중요한 역할을 한다. 이 연구에서는 기존의 충돌위험도 평가 방법을 분석하여 문제점을 비교 검토하였으며, 그 대안으로 Sech 함수를 이용한 충돌위험도 평가 방법을 새롭게 시도하였다. 이를 충돌위험도 평가에 적용하고 본선의 안전한 행동구간을 결정할 수 있는 방법을 제시하였다.