• 로봇학회논문지
• /
• 제17권1호
• /
• 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.

• 한국도로학회논문집
• /
• 제17권5호
• /
• pp.47-56
• /
• 2015

PURPOSES: The purpose of this study is to estimate the impact of variable message signage (VMS) on traffic safety as a function of road curve radius using statistical methods. METHODS: In order to analyze the impact of VMS installations on traffic safety, travel speed, lateral distance, and geometric data relating to road curvature in each study area was acquired and analyzed for the impact of providing VMS information on driver performance and traffic safety using statistical methods including student t-test, Mann-Whitney test, and the Anderson-Darling test for estimating traffic safety hazard zone in each lane. RESULTS: As a result of analyzing driver performance characteristics before and after providing VMS information, it was determined that by providing VMS information, mean travel speed is deceased and vehicles are driven with increased precision, following the centerline in the first and second lanes. Also the results of analyzing traffic safety impacts of VMS indicate that traffic safety performance factors in the first lane of the Gapyeong section can, on average, increase in the left and right side of the lane by 19.22% and 68.98%, respectively, and in the case of the second lane, safety impacts, on average, can increase in both sides by 100%. For the Hongcheon section, traffic safety impacts in the first lane, on average, can increase along the left and right sides of the lane by 32.31% and 47.18%, and within the second lane, traffic safety can be increased along the left and right side of the lane by 10.97% and -0.01%, respectively. CONCLUSIONS: Based on the results of this study, the impact on traffic safety obtained by providing VMS information for road sections with smaller curve radii is greater than can be obtained for road sections with larger curve radii.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.786-790
• /
• 2006

Urban rail transit offers target performance and function because various lower part system such as rolling-stock, signal, power and trackis consisted as complex. In order to function properly an urban rail transit which is complicated system to work as safety and reliability, System must secure safety with structure, design, manufacture, install and verification and it is important to establish a safety standard follows it procedures, establish what step all it is important to operate. Safety standard of urban transit infrastructure is minimum standard necessary to secure safety of signal, power and track. Urban rail transit standard business leads to make many requirements. Recently, many types of equipment have applied to manage requirements and standards for system efficiently in part of universal, airline and car accordingly applied equipments use to manage a pursuit(Trace) between standard of system. Especially importance of management is emphasized more become more. Importance of standard management which usesa computing support tool recently in transit filed is embossed and is predicted to be more such forward. Therefore we propose the effective method of management with infrastructure system by constructed data-base system.

• 재활치료과학
• /
• 제10권2호
• /
• pp.141-150
• /
• 2021

목적 : 본 연구는 뇌졸중 환자에게 Cognitive Orientation to daily Occupational Performance(CO-OP) 중재법을 적용하여 작업수행의 질, 상지기능 및 실행기능에 영향을 주는지 확인하고자 하였다. 연구방법 : 연구대상은 재활치료를 받고 있는 입원, 외래 환자 중 발병한지 3개월 이상된 뇌졸중 환자 5명이었다. 연구는 단일집단 사전-사후 평가로 설계되었다. 중재는 1일 1회 30분간 주 5회로 총 20회기를 적용하였다. 중재활동은 환자가 선정한 중요도는 높지만 만족도와 수행도는 낮은 활동을 선정하여 진행하였다. 평가도구로는 수행의 질을 평가하는 Performance Quality Rating Scale(PQRS)과 Canadian Occupational Performance Measure(COPM), 실행기능을 알아보기 위한 Executive Function Performance Test for Koreans(EFPT-K), 상지기능을 알아보기 위한 Motor Activity Log(MAL)를 사용하였다. 중재 전·후를 비교할 수 있는 통계방법으로는 비모수 검정인 Wilcoxon's signed rank test를 사용하였다. 통계학적 유의수준은 p<0.05로 하였다. 결과 : 상지기능은 모든 항목에서 유의미한 변화를 나타냈으며 실행기능은 시작하기 항목을 제외한 준비하기, 순서정하기, 판단과 안전, 종결하기 전 항목에서 유의미한 변화를 나타냈다. 또한, 작업수행도 유의미한 차이를 보였다. 결론 : 만성 뇌졸중 환자를 중심으로 20회기의 CO-OP 중재를 통해 상지기능, 실행기능, 작업수행을 향상시켰다. 뇌졸중 환자의 작업수행뿐 아니라 세부적인 작업 요소 향상에 긍정적인 영향을 도출하였다.

• 한국ITS학회 논문지
• /
• 제18권5호
• /
• pp.34-48
• /
• 2019

본 연구는 우리나라 전체 도로 유형을 대상으로 빅데이터를 이용하여 안전성능함수(safety performance function, SPF)를 개발하고, 그것을 바탕으로 다양한 도로에 대한 안전등급을 평가함으로써 상대적으로 위험한 도로에 대한 대책을 수립할 수 있는 기초 정보를 제공하고자 하였다. 교통사고 자료를 국가표준 노드 및 링크 체계를 기반으로 전국의 도로에 매칭 하여 종속 변수로 활용하였으며, 독립변수로 링크 길이, 차로 수 등 기하구조 자료 및 한국교통연구원의 ViewT 교통량 자료, 그리고 사업용 차량에 장착된 운행기록계를 통한 위험운전행동 건수를 활용한 4개 시스템의 교통 빅데이터를 활용하여 연구를 진행하여 7개 도로 유형별 안전성능함수를 개발하고, 개발된 안전성능함수를 활용하여 도로유형별로 A, B, C, D 네 개의 안전등급을 평가하였다. 본 연구에서 사용한 방법론과 분석 결과를 토대로 우리나라의 위험도로를 선정하였다. 도출된 결과를 바탕으로 교통안전 개선사업의 대상을 선정하고 그에 따른 효과 등을 모니터링하고 계량화할 수 있을 것으로 기대된다.

• 로봇학회논문지
• /
• 제18권4호
• /
• pp.403-408
• /
• 2023

In this paper, we introduce the results of the development of a care robot for the safe lifting and transportation of bedridden patients with difficulty moving by themselves, especially, in medical facilities. The purpose of the developed patient transfer robot is to improve the convenience of care givers and enhance the safety and comfort of care recipients by facilitating patient lifting and patient transfer tasks by applying robot technology. In order to implement the lifting function, a hoist was designed and developed, and a sway control and rollover warning system were included in the hoist module as product differentiators. In addition, in terms of implementing the transfer function, an omnidirectional movement mechanism to improve operability in confined spaces and an active safety system to prevent collisions were developed. The function of the developed patient transfer robot was verified through performance evaluation by an authorized testing agency.

• 대한토목학회논문집
• /
• 제35권2호
• /
• pp.397-405
• /
• 2015

과거 고속도로는 이동성 중심의 기능을 주로 담당하였으나, 삶의 질 향상과 의식 수준의 향상에 따라 '빠른 고속도로'에서 '안전한 고속도로'로 고속도로 기능의 패러다임이 변화하고 있다. 고속도로 교통사고는 2012년 기준 3,550건이 발생하였으며, 371명이 교통사고로 사망한 것으로 집계되었고, 치사율은 일반국도의 약 2배에 달하는 것으로 보고되고 있다. 본 연구에서는 고속도로 주요 6개 노선을 대상으로 교통사고건수와 교통량 기반의 사고예측모형(안전성능함수)을 개발하였다. 안전성능함수는 각 노선별로 도로의 선형 및 규모 등이 달라 정확하게 각 노선을 예측하는데 어려움이 있을 것으로 판단되어, 6개 노선의 통합 안전성능함수를 구축하고, 각 노선별로 교통사고를 보정할 수 있는 계수를 산출하였다. 본 연구의 결과는 향후 교통사고 예방을 위한 노선별 교통안전 전략수립의 기초자료로 활용함으로써 보다 안전한 고속도로 관리에 기여할 것으로 판단된다. 향후에는 각 노선별 특성에 따른 그룹별 통합모형을 통한 노선별 보정계수를 산출하여 신뢰성 있는 사고 예측값을 제시하는 연구가 수행되어야 할 것이다.

• 대한한의학회지
• /
• 제44권1호
• /
• pp.128-128
• /
• 2023

Objectives: This research aimed to develop a guideline for evaluating safety and performance of electronic warm-acupuncture apparatus. With the development of medical devices like electronic warm-acupuncture apparatus with improved performance, convenience and safety measures compared to traditional warm-acupuncture needling, safety and performance guideline is a necessity. Methods: By referring to existing standards and guidelines of other electronic devices for Korean medicine with heating function, guideline for safety and performance assessment of electronic warm-acupuncture apparatus was drafted Results: The guideline, presents explanation for adequate temperature and settings of the apparatus, and safety measurements providing against thermal runaway situations along with guidelines for the manual. Guideline for detailed test method for the performance of the apparatus such as accuracy of temperature increase and the timer, and safety unit was also provided. The test items and suggested test methods for the requirements of biological, electrical and electromagnetic safety were referred to Korean approval documents of ministry of Food and Drug Safety. Conclusion: We proposed the relevant items to verify performance and safety of warm-acupuncture apparatus to assure patient safety and improve the quality of currently developing devices for application in clinical field.

• 한국터널지하공간학회 논문집
• /
• 제24권2호
• /
• pp.183-192
• /
• 2022

터널구조물의 기능 및 성능저하는 도로의 기능상실 등을 유발할 수 있으므로 초기 손상이 심화된 손상으로 진전되지 않도록 선제적 유지관리가 필요하다. 이에 관련 법령에 따라 정기적인 점검/진단이 시행되고 있으나, 점검/진단, 보수/보강 계획 수립 및 실시 등 일련의 과정을 충분히 반영하지 못하고 있다. 따라서 본 연구에서는 도로터널 1,728개소에 대해 시행한 5,540건의 정밀안전점검, 정밀안전진단 사례에 대한 조사/분석을 통하여 합리적인 유지관리 개선 방안을 제시하였다.

• 한국수소및신에너지학회논문집
• /
• 제27권6호
• /
• pp.670-676
• /
• 2016

Hydrogen town in Republic of Korea was established in 2013. Hydrogen as a byproduct produced by various processes of factories is used in hydrogen town facilities. As cell performance is affected by contaminations in fuel gas, various standards about impurities of fuel have been determined by many countries. This study shows performance degradation of single cell with impurities concentrations. Traces of carbon monoxide (CO) and hydrogen sulfide ($H_2S$)can cause considerable cell performance losses. For comparing the performances by poisoning of CO, acceleration test, I-V curve, constant current are performed. Both the CO and $H_2S$ poisoning rate are a function of their concentration. With the higher concentrations the higher poisoning rates are observed. And, it was confirmed that, oxidation behavior and side reaction generation are not affected. Under the lower $H_2S$ concentration condition, the poisoning rate is much higher than that of CO because of its different adsorption intensity. It can be possible that the result of this study can be used for enacting regulation as a baseline data.