In this paper, we proposed and tested an indoor obstacle recognition and avoidance algorithm using vision and ultrasonic sensors for effective operation of drone with low-power. In this paper, the indoor flight of a drone is mainly composed of two algorithms. First, for the indoor flight of the drone, the vanishing point and the center point of the image were extracted through Hough transform of the input image of the vision sensor. The drone moves along the extracted vanishing point. Second, we set an area of interest so that the drone can avoid obstacles. The area of interest is a space where the drone can fly after recognizing an obstacle at a distance from the ultrasonic sensor. When an obstacle is recognized in the drone's area of ​​interest, the drone performs an obstacle avoidance action. To verify the algorithm proposed in this paper, a simple obstacle was installed in an indoor environment and the drone was flown. From the experimental results, the proposed algorithm confirmed the indoor flight and obstacle avoidance behavior of the drone according to the vanishing point.

PURPOSES : For vehicle-alone accidents with a high mortality rate, it is necessary to analyze the factors influencing the severity of roadside fixed-object traffic accidents. METHODS : A total of 313 roadside fixed obstacle traffic accidents, variables related to fixed obstacles, and variables related to road geometry were collected. The estimation model was constructed with data collected using an ordinal probit regression model. RESULTS : Piers, vertical slopes, and distances between roads and objects were the primary causes of increased accident severity. CONCLUSIONS : Countermeasures, such as object removal, relocation, clear zones, frangibles, breakaway poles, etc., are required for accident-prone or dangerous points.

Various underwater studies using underwater sonar sensors are actively in progress. However, unlike the ground, the underwater has a lot of noise. So it is difficult to accurately recognize the underwater environment. The final purpose of this study is to improve the efficiency of the underwater environment recognition using the underwater sonar sensor by developing a filtering algorithm that removes noise and expresses the object from the underwater sonar image captured by the underwater sonar sensor. To develop a filtering algorithm, convolutional calculations were used with three types of filters. This paper is about the case study that conducted to set the parameters of ‘Gabor Filter’ suitable for underwater sonar image during the design process of filtering algorithm. As a result, it was possible to find the most suitable ‘Gabor Filter’ parameters for underwater sonar images. And it showed high accuracy with a binary map of obstacles created by hand using the naked eye. Through this study, it can be utilized not only as a binary map of real-time obstacles, but also as an algorithm for generating object masks in underwater sonar images for deep learning.

The numerical analysis of two-dimensional transient flow around the obstacle with rotated square cross sections was carried out. The obtained velocity distributions for each time step and each rotation angle were imaged to provide data for CNN(convolutional neural network). Both classification and regression neural networks were used for prediction of rotation angle. As results The classification method incorrectly predicted the rotation angle in only 2 of the 470 images. The regression method predicted the rotation angle errors within except 2 out of 470 images. From these facts, it could be concluded that both methods can be sufficiently applicable to the flow analysis.

PURPOSES : The purpose of this study is to analyze the impact of the level of the light-environment and the driver's visual ability on the change in the driver's perception of a forward curved section at night. The study also aims to identify factors that should be considered to ensure safety while entering curved sections of a road at night. METHODS : Data collected from a virtual driving experiment, conducted by the Korean Institute of Construction Technology (2017), were used. Logistic regression was applied to analyze the effects of changes in the light-environment factors (road surface luminance and glare) and the driver’s visual ability on a driver's perception of the road. Additionally, analysis of the moderated effect of visual ability on light-environment factors indicated that the difference in drivers’ visual abilities impact the influence of light-environment factors on their perception. A driver's ability to perceive, as a response variable, was categorized into 'failure' and 'success' by comparing the perceived distance and minimum reaction sight distance. Covariates were also defined. Road surface luminance levels were categorized into 'unlit road surface luminance' (luminance ≤ 0.1 nt) and 'lit road surface luminance' (luminance > 0.1 nt), based on 0.1 nt, which is the typical level observed on unlit roads. The glare level was categorized as 'with glare' and 'without glare' based on whether the glare was from a high-beam caused by an oncoming vehicle or not. The driver's visual ability level was categorized into 'low visual ability' (age ≥ 50) and 'high visual ability' (age ≤ 49), considering that after the age of 50, the drive’s visual ability sharply declines. RESULTS : The level of road surface luminance, glare, and driver's visual ability were analyzed to be significant factors that impact the driver's ability to perceive curved road sections at night. A driver's perception was found to reduce when the road surface luminance is very low, owing to the lack of road lighting ('unlit road luminance'), when glare is caused by oncoming vehicles ('with glare'), and if the driver's visual ability level is low owing to an older age ('low visual ability'). The driver's ability to perceive a curved section is most affected by the road surface luminance level. The effect is reduced in the order of glare occurrence and the driver's visual ability level. The visual ability was analyzed as a factor that impacts the intensity of the effect of change of the light-environment on the change of the driver's ability to perceive the road. The ability to perceive a curved section deteriorates significantly in 'low visual ability' drivers, aged 50 and above, compared to drivers with 'high visual ability,' under the age of 49, when the light-environment conditions are adverse with regard to the driver’s perception (road surface luminance: 'lit road surface luminance'→'unlit road surface luminance,' glare: 'without glare'→'with glare'). CONCLUSIONS : Supplementation, in terms of road lighting standards that can lead to improvements in the level of light-environment, should be considered first, rather than the implementation of restrictions on the right of movement, such as restricting the passage of low visual ability or aging drivers who are disadvantageous in terms of gaining good perception of the road at night. When establishing alternatives so that safety on roads at night is improved, it is necessary to consider improving drivers' perception by expanding road lighting installation. The road lighting criteria should be modified such that the glare caused by oncoming traffic, which is an influential factor in the linear change in perception, and the level of light-environment thereof are improved.

배타적경제수역의 난파물 제거에 관한 연안국의 개입권한과 절차, 비용회수 등에 관하여 규정한「난파물제거협약」이 채택되어 국제적으로 발효되면서 각 연안국은 자국의 실정을 감안하여 난파물 처리규정을 국내법으로 수용 하였다. 우리나라의 경우에도 「해사안전법」을 개정하여 영해뿐만 아니라, 배타적 경제수역의 난파물, 즉, 항행장애물까지 처리할 수 있는 근거를 추가적으로 마련하여 국제규범에 따른 해양관할권을 적극적으로 행사하려는 노력을 하고 있다. 그런데 항행장애물 제거와 관련된 현행 국내법규와 해역관할청의 대응역량은 몇가지 실행상 문제점을 가지고 있다. 예컨대, 항행장애물 제거역량을 적절하게 반영하지 않은 채 해역관리청에 업무가 위임되어 있는 것과 방치폐선, 해양표류물, 침몰선박 등 항행장애물 유사용어 및 제거규정을 규정한 다수의 법규들이 병존하면서 주관부서간 업무혼선이 야기되고 있는 것이다. 따라서 현행 항행장애물 처리제도의 문제점에 대한 개선방안으로 관련 법제의 적절한 정비와 주관부서의 현실적 구난능력을 감안한 업무조정이 필요하다. 구체적으로는 해사안전법 관련규정을 개정하여 구난능력을 갖춘 전문 민간기관·단체에 업무를 위탁하고, 중장기적으로 구조와 구난을 통합하여 일원화하는 방향으로 관련 법제를 정비할 필요가 있다.

There are many researches about UGV mechanism regarding uneven terrains such as mud, sand, gravel, and vertical obstacle. This paper introduces a mobile mechanism to overcome the vertical obstacle for the UGV. Moreover, this paper proposes an asymmetric mechanism of wheels to overcome obstacle. Major system geometry parameters such as will be determined under certain constraints. Several mobile mechanisms will be compared with the proposed system.

The study aimed to compare the effect of the treadmill walking training combined with obstacle-crossing (TWT-OC) and treadmill walking training (TWT) on the walking function of patients with chronic stroke. 29 subjects volunteered to participate in this study; they were randomly assigned to either TWT-OC group (15 subjects) or TWT group (14 subjects). Subjects from the TWT-OC group underwent a treadmill walking combined with obstacles-crossing for 30 minutes daily, three days a week for four weeks, whereas subjects from the TWT group received only a treadmill walking. The 10 m walk test (10MWT), 6-min walk test (6MWT), berg balance scale (BBS), timed up and go test (TUG), activities-specific balance confidence-Korean version (ABC-K), and walking ability questionnaire (WAQ) were measured before and after the 4-week training. The TWT-OC group showed significantly better functional mobility of walking and balance measured by 6MWT (p<.01), BBS (p<.01), and TUG scores (p<.05) when compared with those of the TWT group. Further, within-group comparison showed significant improvement in all variables (p<.01) except for 10MWT. These findings suggest that the TWT-OC and TWT may be helpful for improving the walking function of patients with chronic stroke, and the TWT-OC has probably more favorable outcomes for chronic stroke, however, further trials with wider range of subjects are warranted for generalization and clinical relevance.

This study aimed to evaluate factors related to the ability of ambulatory patients with cerebral palsy (CP) to walk over vertical and horizontal obstacles. Twenty patients with spastic CP who were able to walk independently for at least 10 m with or without walking devices were recruited for the study. Participants were required to walk over small obstacles (1, 4, and 8 cm in height or width; total of 6 conditions). A 'fail' was recorded when either the lower limbs or the walking device contacted the obstacle. Linear regression analyses were used to determine the effects of age, sex, walking devices, eyeglasses, subtype (hemiplegia or diplegia), ankle foot orthoses, functional level, and score of body mass index on the ability of obstacle crossing. Fifteen participants (75%) failed to adequately clear the foot or walking device over obstacles in at least 1 condition. The chance of failure in crossing vertical obstacle was affected by the use of ankle foot orthoses, eyeglasses, gender, and CP subtype (p<.05). The failure rate crossing horizontal obstacle was affected by CP subtype. These findings suggest that rehabilitation procedures should (1) consider the clinical characteristics of patients in order to prepare them to be more independent while performing daily activities, and (2) incorporate environmental conditions that patients encounter at home and in the community.

This research is to develop a street-walking aid for the visually impaired, which detects front direction obstacles within 2 meters and inform the user with sound and vibration as well. This way it keeps the visually impaired from such obstacles. This aid also identifies 10 different colors quite correctly so that the visually impaired could apply it when he or she tries to match the color of his or her clothes, or he or she wants to know the color of things he or she would buy. This aid has additional function of identifying the brightness level around the user. It provides also various ergonomic design features such as optimized centroid design for minimal fatigue of hands even after long use, ideal position of back button for easy and convenient grip, easy and compact recharge, raised letters on all buttons, the usefulness of main body itself without attached white cane, non-slip hand grip, high-performance ultrasonic sensors, and wrist strap.

해안 지역은 해수의 운동에너지의 대부분은 해안에서 소산되며 이 과정에서 해안의 토사 등이 유실된다. 수면에 돌출된 방파제에 비해 수중구조물은 해수의 유통을 가능하게 하고 해안선을 따라 해수순환을 가능케 한다. 이 연구에서는 해안 침식을 방지 기능을 갖는 수중구조물을 하부틈새를 갖는 수중장애물로 형상화 하고 후방의 흐름특성을 규명하였다. 실험은 Re =1.2×104 조건에서 2프레임 입자영상유속계를 이용하여 속도장을 계측하여 고찰하였다. 측정된 시간평균 속도분포를 분석한 결과 유선의 곡률 효과가 현저히 나타났으며 전단층 주위 유체의 유입 등의 영향으로 박리 전단층 내에서 커다란 와구조가 연속적으로 발생하였다. 또한 하부틈새의 크기가 증가할수록 재순환 영역의 중심이 후류로 이동하고 재순환영역의 강도도 약해지는 결과를 보였다.

2차원 평면에 원형 장애물들이 주어져 있을 때, 주어진 시작점과 끝점을 잇는 최단 경로를 구하는 문제를 다룬다. 이 때, 원형 장애물들은 서로 교차하지 않으며, 반지름이 각기 다르다고 가정한다. 최단 경로를 효율적으로 구하기 위해서, 본 논문에서는 두 가지의 필터를 제안한다. 첫 번째는 타원 필터이고, 두 번째는 컨벡스-헐 필터이다. 장애물들을 피하면서 주어진 두 점을 연결하는 최단 경로를 구하기 위해서는, 주어진 2차원 공간을 탐색하여야 하는데, 위의 두 필터는 최단 경로와 만나지 않게 되는 원형 장애물들을 미리 걸러냄으로써, 탐색 공간을 효율적으로 줄여준다. 또한 보로노이 다이어그램을 이용하면, 장애물들 간의 인접 정보를 효과적으로 활용할 수 있다. 필터링을 한 후에는 다익스트라 알고리즘을 이용하여 최단 거리를 구한다.

본 연구의 목적은 이중과업 방법론(dual task methology)을 사용해서 젊은 사람과 노인을 대상으로 독립된 두 사건(two separate concurrent events)을 동시에 수행하는데 요구되는 주의력에 대한 분석과 노인에서의 특징적 차이를 찾는 것이다. 본 실험은 대상자가 힘판(force plate) 위에서 장애물(10cm) 보행시에 경피자극(cutaneous stimulation)에 대하여 마이크로 스위치(micro-switch)를

본 연구의 목적은 장애물 높이에 따른 상지 팔운동 제한이 스텝안정화(stabilization step)에 영향을 주는지 알아보기 위하여 실시하였다. 연구대상자는 대학생 남자 14명, 여자 16명으로 총 30명이였으며, 평균 연령은 21.5세이었다. 스텝 안정화는 FASTEX(functional activity System for testing and exercise, Cybex Division of Lumex, Inc., USA)를 이용하여 측정하였다.