• 대한기계학회논문집A
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• 제31권2호
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• pp.197-204
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• 2007

Fretting is a contact damage process that occurs between two contact surfaces. Fretting fatigue reduces fatigue strength of the material due to low amplitude oscillatory sliding and changes in the contact surfaces of strongly connected machine and structure such as bolt, key, pin, fixed rivet and connected shaft, which have relative slip of repeatedly extreme low frequency amplitude. In this research, the fretting fatigue behavior of 2024-T3511 and 7050-T7451 aluminum alloys used mainly in aircraft and automobile industry were experimentally estimated. Based on this experimental wort the following results were obtained: (1) A significant decrease of fatigue lift was observed in the fretting fatigue compared to the plain fatigue. The fatigue limit of 2024-T3511 aluminum alloy decreased about 59% while 7050-T7451 aluminum alloy decreased about 75%. (2) In 7050-T7451 specimen using ATSI4030 contact pad, crack was initiated more early stage than using 2024-T3511 contact pad. (3) In all specimens, oblique cracks were initiated at contact edge. (4) Tire tracks and rubbed scars were observed in the oblique crack region of fracture surface.

• 한국수자원학회논문집
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• 제38권1호
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• pp.49-57
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• 2005

본 연구에서는 홍천강, 미호천, 내성천을 평가 대상하천으로 선정하여, '하천의 생물서식처 복원을 위한 하천 자연도평가 : I. 평가방법의 제안'에 따라 하천자연도평가를 시행하였다. 하천자연도의 종합평가결과 홍천강은 2등급(평균 1.92), 미호천은 2등급(평균 1.43), 내성천은 2등급(평균 2.31)으로 평가되었다. 수질과 하천자연도평가의 상관관계를 비교ㆍ분석한 결과, 수질과 하천자연도 종합평가결과의 상관계수가 0.575로 상관성이 매우 작게 분석되어, 하천자연도평가가 수질평가와 다른 관점에서 하천의 생태계를 평가하는 지표로 활용이 가능한 것으로 분석되었다.는 지표로 활용이 가능한 것으로 분석되었다.

• 한국가구학회지
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• 제28권3호
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• pp.169-184
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• 2017

The purpose of this study is to understand the characteristics of the common people and the furniture they used and to investigate the general characteristics of traditional Korean culture in the late Chosun Dynasty in order to study the Characteristics of Bandagein Gyeongnam province. Local characteristics of the Bandaji were examined through comparing local style of Folk Houses Interior space composition and the utilization Bandaji of that space through the case study and literature review. Bandagein Gyeongnam province are classified as Tongyeong, Jinju, Miryang, Namhae, Yangsan, Gimhae. The height of Bandaji is relatively lower than in other provinces, the metal ornaments are simple, and the wood pattern is used to show simple and natural beauty. As a characteristic of metal decoration, Bandaji of Miryang have a lot of openwork decoration, Bandaji in Jinju have a cicada hinge and a decorative iron hook, Bandaji in Namhae have a peak of a lotus flowers shaped hinge and Ying-yang/ number pattern on openwork facet and Bandajji in Yangsan have a Violin hinge and Bandajji in Gimhae have emphasized ornamental features by using a rivet and lock made of tin and the cast iron.

• Steel and Composite Structures
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• 제31권5호
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• pp.453-467
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• 2019

Portal frame structures, made up of cold-formed steel trusses, are increasingly being used for lightweight building construction. A novel pin-jointed moment connector, called the Howick Rivet Connector (HRC), was developed and tested previously in T-joints and truss assemblage to determine its reliable strength, stiffness and moment resisting capacity. This paper presents an experimental study on the HRC, in moment resisting cold-formed steel trusses. The connection method is devised where intersecting truss members are confined by a gusset connected by HRCs to create a rigid moment connection. In total, three large scale experiments were conducted to determine the elastic capacity and cyclic behaviour of the gusseted truss moment connection comprising HRC connectors. Theoretical failure loads were also calculated and compared against the experimental failure loads. Results show that the HRCs work effectively at carrying high shear loads between the members of the truss, enabling rigid behaviour to be developed and giving elastic behaviour without tilting up to a defined yield point. An extended gusset connection has been proposed to maximize the moment carrying capacity in a truss knee connection using the HRCs, in which they are aligned around the perimeter of the gusset to maximize the moment capacity and to increase the stability of the truss knee joint.

• 한국군사과학기술학회지
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• 제25권4호
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• pp.401-411
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• 2022

As the role of high-value air assets(e.g., AWACS, JSTARS, Rivet Joint, E-2) becomes more critical in modern warfare, the air escort for these assets blocking attacks from any potential enemy fighter also becomes vital. Without the escort, the operations of the assets become restricted. However, such an escort is not always possible due to the limited flight time of the escort fighters. In this paper, we introduce an escort tactics for high-value air assets performed by the manned-unmanned teaming composed of a transport aircraft and UAVs(unmanned aerial vehicles). In this tactics, the transport aircraft plays the role of an aircraft carrier, which carries, launches, and retrieves the UAVs. The missions of UAVs in this tactics are to detect and engage enemy fighters. We also introduce the simulation result of this tactics to identify the UAVs' required capabilities and optimal maneuvering.

• 지질공학
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• 제10권3호
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• pp.263-272
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• 2000

본 연구의 목적은 GlS와 수문모형(HIS)을 이용하여 오원천 유역에서 강우와 유출량의 관계를 산정하기 위함이다. 본 연구에서 유역인자와 지형인자는 GIS를 이용하여 DEM으로부터 추출하였으며, 그 외의 자료들은 1:50,000 지형도를 이용하여 추출하였다. 수문모형에서 이용되는 변수인 유역면적(A), 유로연장, SCS CN 값 등은 대상유역에서 GIS을 이용하여 추출하였으며, 추출된 변수들을 수문모형에 적용하여 강우-유출량의 관계를 모의하는데 이용하였다. 그리고 계산된 유출량과 관측 유량을 이용하여 매개변수를 최적화하였다. 그리고 모의된 매개변수를 토대로 수문모형에 적용하여 강우-유출량 관계를 확정하였다. 그 결과 수문모형은 강우-유출량의 관계를 성공적으로 모의하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2672-2678
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• 2011

철도차량의 차체 구조는 초기의 전(全) 목제에서 강제 후레임과 목제 차체의 조합, 리벳으로 결합한 전(全)강제차체, 전(全) 용접결합의 모노코크(monocoque)차체로 변천해 왔다. 구체의 재료 또한 Mild Steel이 많이 사용되어 왔으나, 가볍고 내식성이 우수한 경량 스테인레스 구체와 알루미늄 구체의 적용 비율이 급격히 높아지고 있다. 구조적으로는 종래의 골조와 외판으로 구성된 싱글 스킨 구조인 SSD (Sheet_Stringer Design)에서, 알루미늄 구체와 같이 대형 중공압출형재로 구성된 전(全)더블스킨 구조인 AED(All Extrusion Design)가 실용화되고 있다. 종래의 알루미늄 차체는 소형 압출재로 제작되어 용접에 의한 열영향을 받는 범위가 매우 크고 매우 취약한 특성 때문에 나타나는 용접결합 부분의 강성 저하가 많은 문제점을 일으켰다. 본 연구에서는 확장형 알루미늄 압출형재를 사용하여 부재 수를 감소시킴으로서 용접 공수를 줄이고 결합부의 용접 집중을 최소화 하여 품질 및 차체 강성을 향상 시킬 수 있는 방안을 제시하였다.

• Journal of Welding and Joining
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• 제34권1호
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• pp.21-25
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• 2016

The automotive vehicle is made through the following processes such as press shop, welding shop, paint shop, and general assembly. Among them, the most important process to determine the quality of the car body is the welding process. Generally, more than 400 pressed panels are welded to make BIW (Body In White) by using the RSW (Resistance Spot Welding) and GMAW (Gas Metal Arc Welding). Recently, as the needs of light-weight material due to the $CO_2$ emission issue and fuel efficiency, new joining technologies for aluminum, CFRP (Carbon Fiber Reinforced Plastic) and etc. are needed. Aluminum parts are assembled by the spot welding, clinching, and SPR (Self Piercing Rivet) and friction stir welding process. Structural adhesive boning is another main joining method for light-weight materials. For example, one piece aluminum shock absorber housing part is made by die casting process and is assembled with conventional steel part by SPR and adhesive bond. Another way to reduce the amount of the car body weight is to use AHSS (Advanced High Strength Steel) panel including hot stamping boron alloyed steel. As the new materials are introduced to car body joining, productivity and quality have become more critical. Productivity improvement technology and adaptive welding control are essential technology for the future manufacturing environment.

• 한국실내디자인학회논문집
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• 제24권6호
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• pp.145-153
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• 2015

For this research with the objects of spaces in two department stores which can be referred to as representative facility of commercial space, observation test has carried out to estimate how much visitors rivet their eyes to the display of shops. In addition, to find out what effect the difference among the department types has on the selective attention to space element, the observation time was applied as a medium for estimation. The followings are the result from analyzing the observation frequency and the observation intensity feature of each section where the characteristics of design could be found at attention. First, both images of A and B had concentrative dominant-observation at left shops. In case of Image A, Customers began to observe the right shops very attentively after 25 seconds, and with Image B, the attentive observation at right and left took place alternatively after 35 seconds. In other words, regardless of the characteristics of shop displays, the left shops were observed first while in case of the observation after the early and middle time-frame the characteristics of shops were found to have effects on observation. Second, the normal observation showed some difference among attention sections over time while on the whole both images of A and B had the same highly attentive observation at the middle space. Accordingly, it could be concluded that the middle space was playing a faithful role as background for commercial spaces. Third, the ignorant observation, which is the opposite to the attentive observation, was found different between the images of A and B. When the ignorant observation is considered to have intentionality, it will be possible to set up the display which may attract the attention aggressively by the process of figuring out the characteristics of ignored shops.

• 비파괴검사학회지
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• 제21권2호
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• pp.163-168
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• 2001

접착제와 리벳으로 접합된 항공기 판재의 접합부는 접합 불량, 크랙, 피로 결함이나 부식등에 의해 손상되고 열화될 수 있으며 이런 결함을 전 영역에 걸쳐서 신속하고도 신뢰성 있게 검사하는 것은 항공기 안전을 위해 매우 중요하다. 본 연구에서는 이를 위해 항공기용 알루미늄 판재의 랩 스플라이스 접합 연결부의 접합 품질을 비접촉 방식으로 수행할 수 있는 초음파 비파괴 평가법을 제안한다. 여기서는 레이저를 이용해 램파를 발생시키고 비접촉식 트랜스듀서 (공기정합 용량형 트랜스듀서)를 이용해 피치-캐치 방식으로 검사한다. 레이저 소스로는 Q-스위치된 Nd:YAG 레이저가 이용되며 배열 형태의 직선 슬릿을 갖는 마스크를 이용해 특정 모드의 램파를 발생시켜 이용하였다. 접합부의 한 쪽에서 발생된 레이저 여기 초음파는 판을 따라 전파하여 접합부를 지나 반대편에서 수신되고 수신된 신호의 특성과 접합부의 품질과의 관련성을 조사하였다.