• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제28권1호
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• pp.63-74
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• 2022

Purpose: The purpose of this study is to present an evacuation performance analysis model that can derive vulnerable evacuation spaces with considering the movement behavior as per the elderly groups in the event of a fire in a geriatric hospital. Methods: The evacuation characteristics of geriatric hospital users were investigated through the review of precedent studies. First, the occupant conditions and the evacuation scenario were set to analyze a study target hospital. Then, the evacuation simulation was carried out considering the group types and the density of each group. Finally, an evacuation performance analysis model according to the group type was presented based on the simulation results. Results: The results of this study are as follows: (1) The evacuation performance according to the group type is to be clarified through the suggested study model. (2) It is necessary to secure a ramp or an emergency elevator to distribute the evacuation personnel at the design stage because congestion occurs due to collisions between evacuees on the stairs and delays the evacuation time. (3) It is necessary to consider the evacuation stairs and openings of sufficient size by analyzing the frequency of congestion occurrence and the escape routes of occupants in advance to identify the space where the evacuation flow overlaps. Implications: It is expected that the study result is to be used as primary data for studies that consider the elderly and clustering evacuation behavior in the event of a fire in a geriatric hospital.

• 한국항행학회논문지
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• 제26권5호
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• pp.281-288
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• 2022

본 연구에서는 무게 약 1톤, 속도 약 100km/h에 달하는 멀티콥터 형 UAM(Urban Air Mobility)가 도심 지역에서 추락했을 때 발생할 수 있는 인명피해를 정량적으로 분석하였다. UAM 수요가 가장 많을 것으로 예상되는 서울지역의 인구밀도 및 건물 데이터 베이스를 기반으로 UAM 추락 시 충돌에 노출되는 인구를 도출하였고 멀티콥터 형 비행체가 제어 불가능한 상태에서의 무동력 추락을 고려하여 항력을 고려한 자유낙하 모델을 통해 UAM 추락 시 사고영향 반경을 계산하였다. 더불어, 사고영향 반경이 증가할 때 지상의 인명피해의 변화를 분석하였다. 최종적으로 서울지역에 대한 UAM 추락 시 지상 인명피해 맵을 생성하였고 서울의 대부분의 지역에서 UAM 추락 시 약 1~10명 내외의 인명피해가 발생할 수 있음을 확인하였다. 이를 통해 TLS (Target Level of Safety)를 만족하는 UAM의 고장률 요구사항을 분석하였다.

• 로봇학회논문지
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• 제16권3호
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• pp.250-259
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• 2021

Path planning is one of the important technologies for automated parking. It requires to plan a collision-free path considering the vehicle's kinematic constraints such as minimum turning radius or steering velocity. In a complex parking lot, Rapidly-exploring Random Tree^* (RRT^*) can be used for planning a parking path, and Reeds-Shepp or Hybrid Curvature can be applied as a tree-extension method to consider the vehicle's constraints. In this case, each of these methods may affect the computation time of planning the parking path, path-tracking error, and parking success rate. Therefore, in this study, we conduct comparative analysis of two tree-extension functions: Reeds-Shepp (RS) and Hybrid Curvature (HC), and show that HC is a more appropriate tree-extension function for parking path planning. The differences between the two functions are introduced, and their performances are compared by applying them with RRT^*. They are tested at various parking scenarios in simulation, and their advantages and disadvantages are discussed by computation time, cross-track error while tracking the path, parking success rate, and alignment error at the target parking spot. These results show that HC generates the parking path that an autonomous vehicle can track without collisions and HC allows the vehicle to park with lower alignment error than those of RS.

• 방송공학회논문지
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• 제26권4호
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• pp.356-367
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• 2021

최근 사물인터넷 및 인공지능 기술의 발전에 따라 제조, 스마트시티 등 다양한 분야에서 실시간으로 데이터를 수집하고 분석하여 현실세계 문제에 대한 최적화를 수행하는 연구 및 적용사례가 증가하고 있다. 대표적으로 현실세계를 디지털화한 가상세계와 양방향으로 실시간 동기화를 지원하는 디지털 트윈 기술이 주목받고 있다. 본 논문에서는 디지털 트윈을 정의하고 사물인터넷 국제표준인 oneM2M 기반의 IoT 플랫폼을 활용하여 현실사물과 가상세계의 예측결과를 실시간으로 연결하는 디지털 트윈 플랫폼의 프로토타입을 제안한다. 또한, 제안된 프로토타입을 적용하여 물체의 충돌을 사전에 예측하여 사고를 예방할 수 있는 응용서비스를 구현한다. 응용서비스에서는 사전 정의한 테스트 케이스 수행을 통해 제안한 디지털 트윈 프로토타입이 크레인의 동작을 사전 예측하여 충돌 위험을 감지하고 이를 기반으로 최적 제어를 수행할 수 있으며 실제 환경에 응용 가능함을 보였다.

• Clinical and Experimental Pediatrics
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• 제65권4호
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• pp.194-200
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• 2022

Background: Injury is the leading cause of death or disability in children and adolescents. Rates of deaths from injuries have recently declined, but studies of the occurrence of nonfatal injuries are lacking. Purpose: This study aimed to investigate nonfatal injuries in children and adolescents younger than 20 years based on data from the Korean National Health and Nutrition Survey, 2007-2018. Methods: A questionnaire survey was conducted to determine whether children and adolescents had experienced an injury requiring a hospital visit in the previous year. We investigated each injury's risk factors and characteristics. Results: Of a total of 21,598 children and adolescents, 1,748 (weighted percentage, 8.1%) experienced one or more injuries in the previous year. There was no yearly difference in the proportion of injuries experienced. Among the male subjects, 10.0% had an injury experience; among the female participants, 6.1% had an injury experience (P<0.001). The highest rate was 9.0% in children aged 1-4 years. In multivariate logistic regression analysis, male sex; having an urban residence; having restricted activity due to visual, hearing, or developmental impairment; and attention deficit/hyperactivity disorder were significant risk factors for injury experience. The characteristics of up to 3 injuries per patient were investigated, and 1,951 injuries were analyzed. Falls and slips accounted for 34.9%, collisions for 34.1%, and motor vehicle accidents for 11.3% of the total injuries. Ninety-six percent of injuries were unintentional, 20% caused school absences, and 10% required hospitalization. Conclusion: Among Korean children and adolescents, 8.1% experienced injuries at least once a year with no significant differences in incidence over the past 12 years. Greater attention and effort to prevent injuries are needed.

• 한국정보통신학회논문지
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• 제26권2호
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• pp.251-257
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• 2022

자율주행 차량은 ICT 기술의 도움으로, 운전자의 개입 없이 운행되는 차량을 의미하며 스마트 차량의 한 종류이다. 차량 안전 통신 기술(V2X)이 적용된 차량은 다양한 센서 혹은 타 차량/인프라에서 감지된 정보를 이용하여 운전자의 잠재적 위험 상황을 스마트 차량 스스로가 확실하고 빠르게 예측하도록 하여 보다 안정한 자율주행이 가능하도록 하는데 기여한다. 본 논문에서는 이러한 V2X 통신 기술 중 차량 대 차량 통신(V2V) 모사 통신 기술을 이용하여 자율주행 차량의 충돌 방지 활용 시나리오를 제시하고자 한다. V2V 모사 통신 기반 차량 충돌방지 시스템을 구현하였고 이를 이용하여 제시한 충돌 방지 활용 시나리오를 시연하였다. 제시된 충돌 방지 활용 시나리오는 현재에도 개발/적용을 위해 노력 중인 V2V 통신 기술의 하나의 응용 사례로 고려될 수 있을 것이다.

• 한국항공우주학회지
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• 제50권11호
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• pp.763-770
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• 2022

다수의 드론이 운용되는 환경에서 경로점이 겹칠 때 충돌이 발생할 수 있으며 이를 대비한 충돌 회피는 필수적이다. 다수의 드론이 여러 임무를 수행하는 경우 드론의 경로가 복잡하고 충돌 예상점이 너무 많아 경로계획 단계에서 충돌을 회피하는 경로를 생성하는 방법을 사용하는 것은 적합하지 않다. 본 논문에서는 일반적으로 사용하는 경로 생성 알고리즘을 통해 경로를 생성하고, 그 경로에서 속도 프로파일 최적화를 이용한 충돌 회피 방법을 제안한다. 드론의 경로 간 충돌 예상점에서 드론 사이의 안전거리를 고려하였고, 경로 구간에 속도 프로파일을 할당하도록 설계하였다. 최적화 문제는 드론 간 거리에 대한 식을 비행시간을 변수로 두어 정의하였다. 선형화와 컨벡스화를 통해 구속 조건을 구성하고, 다수 드론 운용 환경에서 SQP(Sequential Quadratic Programming)알고리즘과 컨벡스 최적화 기법의 연산시간을 비교하였다. 마지막으로 20대 드론 운용 환경에서 컨벡스 최적화를 수행한 결과가 본 연구에서 제시한 다수 드론 운용에 적합한지 확인하였다.

• 한국기계가공학회지
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• 제21권4호
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• pp.114-130
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• 2022

The purpose of this study was to investigate the possibility of increasing the efficiency of disaster relief rescue operations through collaboration among multiple aerial and ground robots. The robots create 2.5D maps, which are merged into a 2.5D map. The 2.5D map can be handled by a low-specification controller of an aerial robot and is suitable for ground robot navigation. For localization of the aerial robot, a six-degree-of-freedom pose recognition method using VIO was applied. To build a 2.5D map, an image conversion technique was employed. In addition, to merge 2.5D maps, an image similarity calculation technique based on the features on a wall was used. Localization and navigation were performed using a ground robot to evaluate the reliability of the 2.5D map. As a result, it was possible to estimate the location with an average and standard error of less than 0.3 m for the place where the 2.5D map was normally built, and there were only four collisions for the obstacle with the smallest volume. Based on the 2.5D map building and map merging system for the aerial robot used in this study, it is expected that disaster response work efficiency can be improved by combining the advantages of heterogeneous robots.

• 수산해양기술연구
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• 제58권3호
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• pp.230-240
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• 2022

In general, a high tension on the anchor and chain is placed when a ship at anchor is subjected to heavy weather. Mariners have to pay attention to whether dragging anchor occurs to keep the safety of the ship at anchorage since it is difficult to maintain the stable motion of ship and it causes collisions with other ships nearby. In this paper, the ship motion against the external forces was shown to obtain the fundamental data about characteristic of holding power due to nature of seabed at anchor, so practical trials were carried out in rocky area and muddy area using a trial ship around coastal area of South Korea. In muddy seabed, holding power showed reasonable tension values depending on the distance from anchor position of continuing swing motions of a ship corresponding to wind force. Meanwhile in rocky seabed, tension values on the chain appeared very high occasionally regardless of the distance from the anchor position and seemed to exceed its holding power to be the breaking strain of the chain although weather was not in a severe condition. Therefore, some of the cables laid on the seabed were presumed to be caught in a crack on the rock. It is assumed that even a small amount of external force may cause the chain to break in a moment in rocky seabed. Additionally, wind and current forces had a somewhat contradictory effect on holding power of the ship between them.

• Journal of Medicine and Life Science
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• 제19권1호
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• pp.8-13
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• 2022

Jeju is the largest island in Korea and one of its key tourist attractions. As the number of foreign tourists steadily increases, so does the number of injuries incurred there. Accordingly, this study aimed to describe and compare the characteristics of injuries suffered by foreign tourists versus those of domestic tourists. As a cross-sectional study of a retrospective medical record survey, the study was conducted with reference to the Jeju Injury Surveillance System from the 11-year period of January 2008 to December 2018. The following factors were investigated: demographic data, mechanism of injury, place of occurrence, activity when injured, patient outcome, and mortality. A total of 92,095 injured Jeju Island visitors was recorded during this time, a number that included 88,050 Koreans and 4,045 foreigners. The gender ratio showed similar patterns between the two groups and there were no significant age differences. In both groups, the most common mechanism of injury was collisions/cuts. Also, more foreigners experienced falls than Koreans. Regarding the location, Koreans had the most road accidents, while foreigners were most likely to be injured at outdoor locations, such as seas and rivers. Furthermore, more foreigners experienced severe injuries requiring hospitalization. Notably, this study showed the differences in injury between foreign and Korean tourists visiting Jeju Island and its findings lend support to targeted safety promotion programs.