• Structural Engineering and Mechanics
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• 제34권5호
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• pp.563-580
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• 2010

Composite beams using bolts to attach steel plates to the side faces of existing reinforced concrete (RC) coupling beams can enhance both their strength and deformability. The behavior of those composite beams differs substantially from the behavior of typical composite beams made up of steel beams and concrete slabs. The former are subjected to longitudinal, vertical and rotational slips, while the latter only involve longitudinal slip. In this study, a mixed analysis method was adopted to develop the fundamental equations for accurate prediction of the load-carrying capacity of steel plate strengthened RC coupling beams. Then, a rigid plastic analysis technique was used to cope with the full composite effect of the bolt group connections. Two theoretical models for the determination of the strength of medium-length plate strengthened coupling beams based on mixed analysis and rigid plastic methods are presented. The strength of the strengthened coupling beams is derived. The vertical and longitudinal slips of the steel plates and the shear strength of the anchor-bolt connection group is considered. The theoretical models are validated by the available experimental results presented in a companion paper. The strength of the specimens predicted from the mixed analysis model is found to be in good agreement with that from the experimental results.

• 항공우주시스템공학회지
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• 제15권4호
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• pp.11-20
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• 2021

The estimation of hovering flight time of multicopters using the battery power propulsion system is important for the development and design of the aircraft and its operation. For a given operational weight, the maximum possible battery weight can be decided using both a conventional energy density method and a new Peukert law. In the present study, the hovering flight time is predicted using both methods. The specific data of multicopters in the published literatures were employed for the computation of the hovering flight time. The results were validated with the measured data. The effect of figure of merit of propeller, battery discharging process on the hovering flight time was evaluated, Finally, the effect of the battery cell and package connection types on the hovering time was investigated. It was found that the combination of serial battery cell connections and parallel package connection is the bast in the endurance maximization aspect. As the cell number increases in a package, the hovering flight time is increased. There exists the max. battery ratio for the given takeoff gross weight.

• 융합보안논문지
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• 제13권2호
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• pp.155-163
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• 2013

Connection hijacking은 TCP 스트림을 자신의 머신을 거치게 리다이렉션 할 수 있는 TCP 프로토콜의 취약성을 이용한 적극적 공격 (Active Attack)이다. 리다이렉션을 통해 침입자는 SKEY와 같은 일회용 패스워드나 Kerberos와 같은 티켓 기반 인증 시스템에 의해 제공되는 보호 메커니즘을 우회할 수 있다. TCP 접속은 누군가 접속로 상에 TCP 패킷 스니퍼나 패킷 생성기를 가지고 있다면 대단히 취약하다. 스니퍼의 공격으로부터 방어하기 위하여 일회용 패스워드나 토큰 기반 인증과 같은 사용자 식별 스킴이 사용되어지고 있다. 이들은 안전하지 않은 네트워크상에서 스니핑으로부터 패스워드를 보호하지만 이러한 방법들은 데이터 스트림을 암호화하거나 사인하지 않는 한 적극적인 공격으로부터 여전히 취약하다. 많은 사람들이 적극적 공격은 대단히 어렵고 그만큼 위협도 적을 것이라고 생각하고 있지만 여기서는 이러한 환상을 깰 수 있도록 유닉스 호스트에 성공적으로 침입한 대단히 적극적 공격을 제시한다. 최근 이론적으로 알려진 이 취약점을 공격할 수 있는 도구가 인터넷 상에 공개되어 이에 대한 대책이 요구되고 있다. 본 논문에서는 무선네트워크 상에서 침입자탐지 분석기법에 대하여 제안한다.

• 한국실내디자인학회논문집
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• 제27권3호
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• pp.33-40
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• 2018

As the standard for the value of modern people's life increases, hotels make efforts for the users' qualitative and mental satisfaction. As an approach to hotel space design differentiated for new experiences for travelers, a design that reflects the placeness is needed so that people can experience the local culture and historical meaning of the place. Thus, this study divides the components of placeness into physical factors, socio-cultural factors, and semantic factors. As for methods for the design expression of placeness formation, physical factors are classified as the connection to surrounding environments, center, passage, and area. Socio-cultural factors are classified as cultural experiences in the place. Semantic factors are classified as symbolism and historicity. For a case analysis in this study, overseas four-star hotels or higher, where placeness stood out are analyzed, based on the above-extracted components of placeness. As a result of the analysis, the hotels in the cases showed an aspect of expression that emphasized semantic factors despite there were differences in the detailed expression method, depending on the designers. The expression of the place that reflected locality and temporality showed the connection of time, connecting the past with the present. In the future, only the design expression based on the historical and symbolic meanings of the place will be the experience that remains in the users' memories, very precisely.

• 한국전자통신학회논문지
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• 제13권6호
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• pp.1161-1168
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• 2018

2018년 4월 27일 역사적인 남북 정상의 판문점 선언을 통해 남과 북은 철도연결을 위한 실질적인 대책들을 마련해 나가기로 합의하였다. 상상이 현실이 되어 당장이라도 부산-유럽 간의 열차가 운행될 것처럼 연일 보도하고 있지만 남한에서 출발한 열차가 북한 철도로 직결 운행하고 대륙철도로 국경을 통과하는 운영노선은 지금까지 한국철도가 취급해보지 못한 미지의 영역으로 본격적인 운행을 위해 상당한 부분을 면밀히 검토해야 한다. 또한 철도교통은 타 교통수단과 달리 종합적인 네트워크 시스템으로 서로 다른 철도망의 직결운행을 위한 표준화와 기술적 조화가 매우 중요하다. 본 논문에서는 남북철도 연결대비 직결운행을 위해 철도 상호운용성에서 주도적인 역할을 하고 있는 유럽사례를 살펴보고, 이를 통하여 남북철도 직결운행을 위한 실질적인 상호운용성 확보에 대하여 고찰하였다.

• Steel and Composite Structures
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• 제34권3호
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• pp.441-452
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• 2020

Within the French CIFRE research project COMINO, an innovative type of composite beam was developed for buildings that need fire resistance with no additional supports in construction stage. The developed solution is composed of a steel U-shaped beam acting as a formwork in construction stage for a reinforced concrete part that provides the fire resistance. In the exploitation stage, the steel and the reinforced concrete are acting together as a composite beam. This paper presents the investigation made on the load bearing capacity of this new developed steel-concrete composite section. A full-scale test has been carried out at the Laboratory of Structural Engineering of the University of Luxembourg. The paper presents the configuration of the specimen, the fabrication process and the obtained test results. The beam behaved compositely and exhibited high ductility and bending resistance. The shear connection in the tension zone was effective. The beam failed by a separation between the slab and the beam at high deformations, excessive shear forces conducted to a failure of the stirrups in this zone. The test results are then compared with good agreement to analytical methods of design based on EN 1994 and design guidelines are given.

• Steel and Composite Structures
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• 제42권6호
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• pp.791-804
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• 2022

As a type of semi-rigid connection, the top and seat angle connections are popular in current structures owing to their good cyclic performance and simple erection. However, their stiffness and load bearing capacity are relatively insufficient. This study proposes two strengthening methods to further increase the stiffness and strength of bolted-angle joints while maintaining satisfactory energy dissipation capacity (EDC) and ductility. Cyclic loading tests were conducted on six joint specimens with different strengthened angle components. Based on the test results, the influence of the following important factors on the cyclic behavior of steel joint specimens was investigated: the position of the rib stiffeners (edge rib stiffeners and middle rib stiffener), steel strength grade of rib stiffeners (Q345 and Q690), and additional stiffeners or not. In addition, the finite element models of these specimens were built and validated through a comparison of experimental and numerical results. The stiffness and bearing capacity of the bolted-angle joints could be improved significantly by utilizing the novel strengthened joints proposed in this study. Moreover, this can be achieved with almost no increase in the amount of steel required, and the EDC of this joint could also satisfy the requirements of seismic codes from various countries.

• Journal of Information Processing Systems
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• 제17권6호
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• pp.1115-1126
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• 2021

Plant disease is one of the most irritating problems for agriculture growers. Thus, timely detection of plant diseases is of high importance to practical value, and corresponding measures can be taken at the early stage of plant diseases. Therefore, numerous researchers have made unremitting efforts in plant disease identification. However, this problem was not solved effectively until the development of artificial intelligence and big data technologies, especially the wide application of deep learning models in different fields. Since the symptoms of plant diseases mainly appear visually on leaves, computer vision and machine learning technologies are effective and rapid methods for identifying various kinds of plant diseases. As one of the fruits with the highest nutritional value, apple production directly affects the quality of life, and it is important to prevent disease intrusion in advance for yield and taste. In this study, an improved deep residual network is proposed for apple leaf disease identification in a novel way, a global residual connection is added to the original residual network, and the local residual connection architecture is optimized. Including that 1,977 apple leaf disease images with three categories that are collected in this study, experimental results show that the proposed method has achieved 98.74% top-1 accuracy on the test set, outperforming the existing state-of-the-art models in apple leaf disease identification tasks, and proving the effectiveness of the proposed method.

• 한국학교보건학회지
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• 제28권2호
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• pp.67-78
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• 2015

The purpose of the study was to present a model of WHO Health Promoting School easily applicable to small-sized schools in rural areas. Methods: The study analyzed data of 11 small-sized schools in rural areas selected from 85 health promoting schools, an initiative led by the Ministry of Education from 2012 to 2014. Results: Through the analysis, the study found out the operation process of health promoting schools consists of five stages: system development, needs survey & survey on current status, school health policy development, program development & execution, and evaluation. In addition, the study was able to discover three key factors in operating health promoting schools: connection with curriculum, connection with community, and consensus among members. While it turned out the schools were following operation manuals faithfully, the biggest problem with operation was that the stages of needs survey, priority setting, and core task development were not closely coordinated. Conclusion: Although the model suggested in the study fails to reflect the characteristics of small-sized schools in rural areas, it is close to a universal model which could serve as a guideline when regular schools adopt the system of health promoting schools.

• 천문학회보
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• 제43권2호
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• pp.37.2-37.2
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• 2018

We present the results from a spectroscopic survey of the nearby galaxy cluster Abell 2107 at z=0.04 that has been known as a rotating cluster. By combining 978 new redshifts from the MMT/Hectospec observations with the data in the literature, we construct a large sample of 1968 galaxies with measured redshifts at R<60', which results in high (80%) and spatially uniform completeness at $m_{r,Petro,0}<19.1$. We use this sample to study the global rotation of the cluster and its connection to the large-scale structures in the universe. We first apply the caustic method to the sample and identify 285 member galaxies in Abell 2107 at R<60'. We then measure the rotation amplitude and the position angle of rotation axis. The member galaxies show strong global rotation at R<20' ($V/{\sigma}{\sim}0.60-0.70$) with a significance of >3.8 ${\sigma}$, which is confirmed by two independent methods. The rotation becomes weaker in outer regions. We find at least four filamentary structures at $R<30h^{-1}Mpc$ smoothly connected to the cluster galaxies, which can suggest that the global rotation of the cluster is induced by the inflow of galaxies from the surrounding large-scale structures in the universe.