• 자동차안전학회지
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• 제12권3호
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• pp.43-51
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• 2020

Currently, the second level of the six stages of self-driving technology, as defined by SAE, is commercialized, and the third level is preparing for commercialization. The purpose of ACC is to be evaluated as a system useful for preventing and preventing accidents by minimizing driver fatigue through longitudinal speed control and relative distance control of the vehicle. In this regard, for the study of safety assessment methods in the practical environment of ACC. Distance measurement method using monocular camera and data acquisition equipment such as DGPS are utilized. Based on the evaluation scenario considering the domestic road environment proposed by the preceding study, the relative distance obtained from equipment such as DPGS and the relative distance using a monocular camera in the actual test is verified by comparing and analyzing the safety assessment. The comparison by scenario results showed a minimum error rate of 3.83% in Scenario 1 and a maximum of 14.61% in Scenario 6. The cause of the maximum error is that the lane recognition is not accurate in the camera image and irregular operation conditions such as rushing in or exiting the surrounding area from the walkway. It is expected that safety evaluation using a monocular camera will be possible for other ADAS systems in the future.

• 한국산업융합학회 논문집
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• 제20권4호
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• pp.313-323
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• 2017

As vehicles become more intelligent this is focused on ways to enhance safety and convenience for both drivers and passengers. In particular, x-by-wire systems that replace rigid mechanical components with dynamically configurable electronic elements are being developed to expand intelligent functions, such as adaptive cruise control or lane departure warning system. Because the malfunction of safety-related modules controlling critical functions, such as brakes, throttle, and steering in x-by-wire systems, can cause injury or death, safety and reliability are the most critical issue for automotive vendors and parts manufacturers. In an effort to develop better and effective brake-by-wire system, this paper presents EMB system by using the low speed electric vehicle, which is not required large braking force, with motor controller. In addition, we design performance evaluation system of EMB with 1/4 low speed electric vehicle model and suggested EMB is evaluated through the performance evaluation system.

• 자동차안전학회지
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• 제9권2호
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• pp.6-12
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• 2017

An autonomous driving system based on a precise digital map is developed. The system is implemented to the Hyundai's Tucsan fuel cell car, which has a camera, smart cruise control (SCC) and Blind spot detection (BSD) radars, 4-Layer LiDARs, and a standard GPS module. The precise digital map has various information such as lanes, speed bumps, crosswalks and land marks, etc. They can be distinguished as lane-level. The system fuses sensed data around the vehicle for localization and estimates the vehicle's location in the precise map. Objects around the vehicle are detected by the sensor fusion system. Collision threat assessment is performed by detecting dangerous vehicles on the precise map. When an obstacle is on the driving path, the system estimates time to collision and slow down the speed. The vehicle has driven autonomously in the Hyundai-Kia Namyang Research Center.

• 대한치과기공학회지
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• 제37권3호
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• pp.169-178
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• 2015

Purpose: This study was to investigate usage satisfaction of multi type handpiece with equipped air-jet function Methods: The subjects of this study through the survey was conducted for fifty-nine dental technicians in Daegu and Gyeongsangbukdo from the May 7 to 19, after the June 23 to July 4 2014. The survey was about the function and quality through user testing environment by cutting zirconia specimens using appliance for zirconia. The collected date was analyzed by the statistical program SPSS Win Ver 19.0 for the satisfaction of handpiece and control system. To test for significance on each item, p<0.05 had been decided a standard. General characteristics and relationship between the handpiece and control system was performed correlation analysis. Results: The results of this study is as follows. 35 dental technicians had 1~2 years career in zirconia part as the highest 59.3%, 95% of subjects expected that the prospects for the zirconia material have bright prospects. The satisfaction of multi type handpiece and control system design and function showed a significant difference. Subjects satisfied with the design and function of the multi type showed negative correlation with those of Standard. The satisfaction of multi type handpiece showed 3.37 points of air jet, 3.05 points of noise level, 2.69 points of water flow rate, and 1.98 points of cruise function. Sample differences in all parameters showed a statistically higher difference. Conclusion: High-speed cutting mechanism of multi-type is recommended working with zirconia materials and the multi-type unit combined handpiece motor, air-turbine and air-gun will be expected the increase of user due to the high satisfaction of air jet.

• 해양안보
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• 제1권1호
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• pp.241-271
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• 2020

극초음속 미사일은 전 세계에서 가장 많은 관심을 받는 군사기술이다. 러시아, 중국, 미국이 주도하고 있고 다른 나라 역시 경쟁적으로 동참하고 있다. 극초음속 미사일은 탄도미사일과 순항미사일의 장점을 모두 혼합한 미사일로 기존 방어체계로는 요격이 쉽지 않다. 해군은 기술군으로 과학기술 발전은 해양전략에 많은 영향을 미쳐왔다. 해양전략의 핵심은 해양통제다. 이는 점령보다 해양의 사용권리에 대한 문제이며 확보는 수단이고 행사하는 것이 그 목적이다. 극초음속 미사일은 해양통제의 확보 면에서 제한요인으로 작용한다. 극초음속 미사일의 빠른 속력과 강력한 파괴력은 요격이 어려울 뿐만 아니라 단 한발에도 손상통제가 의미없는 수준의 피해가 발생한다. 이로 인해 해양거부능력이 지리적, 질적으로 향상됨에 따라 해양통제 달성이 어려워 질 것이다. 극초음속 미사일은 해양력투사/방어, 해상교통로 공격/방어라는 해양통제 행사면에서는 각각 기회요인과 제한요인으로 동시에 작용한다.

• 한국항공우주학회지
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• 제50권1호
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• pp.59-66
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• 2022

도심의 교통체증 문제를 해결하기 위해 eVTOL(Electric Vertical Take-Off and Landing) 항공기를 이용한 도심항공교통(UAM) 개념이 등장하여, 많은 국내외 기간들의 연구가 진행되고 있다. 하지만 도심 위를 필연적으로 비행하게 되는 eVTOL 기체가 차세대 교통수단으로 자리 잡기 위해서는 안전성의 확립이 필수적이다. 추락 시 위험도는 항공 안전과 관련된 대표적인 요소이며, 위험도 분석을 위해서는 돌발 상황으로 인한 기체의 추락 및 충돌 지점 예측이 필요하다. 고정익 모드로 운항하는 비행체의 경우 자세 혹은 방향을 결정하는 데 조종면이 큰 역할을 차지한다. 따라서 본 연구에서는 eVTOL 기체의 추락 시 위험도를 분석하기 위해 추진 시스템이 고장 난 기체의 조종면 각도에 따른 추락 지점의 분포를 추정하는 방법을 제시한다. 여기서, 성능과 형상이 공개된 eVTOL 기체를 대상으로 분석한 데이터를 사용하였다. 또한, 초기 조건에 따른 추락 지점의 분포와 확률을 계산하여 추락할 확률이 높은 구간을 도출하였으며, 추락 순간의 속도를 계산하였다.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.631-640
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• 2016

A dual-mode power management for a hybrid-electric UAV with a cruise power of 200W is proposed and empirically verified. The subject vehicle is a low-speed long-endurance UAV powered by a solar cell, a fuel cell, and a battery pack, which operate in the same voltage bounds. These power sources of different operational characteristics can be managed in two different methods: passive management and active management. This study proposes a new power management system named PMS2, which employs a bypass circuit to control the individual power sources. The PMS2 normally operates in active mode, and the bypass circuit converts the system into passive mode when necessary. The output characteristics of the hybrid system with the PMS2 are investigated under simulated failures in the power sources and the conversion of the power management methods. The investigation also provides quantitative comparisons of efficiencies of the system under the two distinct power management modes. In the case of the solar cell, the efficiency difference between the active and the passive management is shown to be 0.34% when the SOC of the battery is between 25-65%. However, if the SOC is out of this given range, i.e. when the SOC is at 90%, using active management displays an improved efficiency of 6.9%. In the case of the fuel cell, the efficiency of 55% is shown for both active and passive managements, indicating negligible differences.

• 한국정보기술학회논문지
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• 제16권11호
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• pp.133-144
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• 2018

철도 시스템의 안전성 표준인 IEC 62278은 위험원 분석을 통해서 철도 시스템이 가질 수 있는 위험원을 예방하거나 또는 제어하도록 요구한다. 만약 위험원 분석이 충분하지 않으면 사고가 발생할 가능성이 높기 때문에, 위험원 분석을 보다 철저히 수행할 필요가 있다. 본 논문에서는 기존의 신뢰성 기반 방법과 시스템 이론적 방법을 상호 결합한 하이브리드 위험원 분석을 제안한다. 제안하는 방법은 기존 위험원 방법을 상호 보완하는 것으로서, 시스템 구성 요소의 고장으로 인한 위험원과 구성 요소들 간의 상호작용으로 인해 발생되는 제어 위험원을 함께 분석한다. 열차간의 속도를 자동 제어하는 다중 적응형 순항 제어 장치의 안전 보호 시스템 개발에 적용한 결과, 기존 방법들 보다 안전 요구사항을 더 많이 추출하여, 위험원으로부터 시스템을 보호함을 확인하였다.

• 한국항공운항학회지
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• 제15권4호
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• pp.9-16
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• 2007

Tilt rotor aircraft can take off and land vertically and cruise faster than any other helicopter. A scaled flight demonstration model of a tilt rotor aircraft has been developed by KARI. Because the flight characteristics of tilt rotor are not well known, the developed scaled model would be helpful to evaluate flight control algorithm of a full scale aircraft. The tethered hover test has been performed in order to improve hover flight characteristics of tilt rotor aircraft prior to flight test of the small scaled model. During the tethered hover test, the performance of rotor speed governor, rate SAS (Stability Augmentation System) and control surface mixers have been evaluated. We expect that the results of real flight hover test would be quite same as tethered hover test. Therefore the tethered hover test results will reduce the risk of flight test properly by fixing some of hidden problems which might occur during the flight test. This paper presents the results of tethered hover test in detail and shows how it could be final ground test before flight test. The control mixer gain and rate SAS feedback gains were modified in order to get higher controllability and stability during the tethered hover flight. The rotor governor showed that it could keep rotor RPM constant with very small deviation even during severe pilot collective input change. The tethered hover test results gave pilot and engineers confirmation and experience about the scheduled flight test.

• 자동차안전학회지
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• 제10권2호
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• pp.20-28
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• 2018

Currently, sharp increase of car is on the rise as a serious social problem due to loss of lives from car accident and environmental pollution. There is a study on ITS (Intelligent Transportation System) to seek coping measures. As for the commercialization of ITS, we aim for occupancy of world market through ASV (Advanced Safety Vehicle) related system development and international standardization. However, the domestic environment is very insufficient. Core factor technologies of ITS are Adaptive Cruise Control, Lane Keeping Assist System, Forward Collision Warning System, AEB (Autonomous Emergency Braking) system etc. These technologies are applied to cars to support driving of a driver. AEB system is stop the car automatically based on the result decided by the relative speed and distance with obstacle detected through sensor attached on car rather than depending on the driver. The purpose of AEB system is to measure the distance and speed of car and to prevent accident. Thus, AEB will be a system useful for prevention of accident by decreasing car accident along with the development of automobile technology. This study suggests a scenario to suggest a test evaluation method that accords with domestic environment and active response of international standard regarding the test evaluation method of AEB. Also, by setting the goal with function for distance, it suggests theoretic model according to the result. And the study aims to verify the theoretic evaluation standard per proposed scenario using car which is installed with AEB device through field car driving test on test road. It will be useful to utilize the suggested scenario and theoretical model when conducting AEB test evaluation.