• 한국강구조학회 논문집
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• 제14권3호
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• pp.463-470
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• 2002

TEC-BEAM System은 구조용 CT형강, PC 콘크리트 그리고 현장타설콘크리트 슬래브로 이루어진 합성보이다. 이 시스템은 단순보에 대한 휨 및 전단실험을 수행하였고 우수한 거동을 보였다. 그러나 현장적용을 위해서는 TEC-BEAM과 RC 기둥 강접합 상세개발이 필요하다. 이 접합부는 TEC-BEAM의 하부에 발생하는 힘을 기둥에 전달하기 위한 매캐니즘을 발생해야만 한다. 그래서 TEC-BEAM의 단면이 증대되어 TEC-BEAM 플랜지 하부로 철근이 배근되는 접합부를 개발하였다. 본 논문에서는 제안된 시스템의 구조적 성능 평가를 위해 2개의 실험체에 대하여 실험하였다. 실험변수는 철근의 정착길이 즉, 증대된 단면의 길이이며, 실험결과 제안된 시스템은 우수한 접합부를 구조 성능을 가지고 있음을 확인할 수 있다.

• Structural Engineering and Mechanics
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• 제18권5호
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• pp.645-669
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• 2004

In seismic analysis of moment-resisting frames, beam-column connections are often modeled with rigid joint zones. However, it has been demonstrated that, in ductile reinforced concrete (RC) moment-resisting frames designed based on current codes (to say nothing of older non-ductile frames), the joint zones are in fact not rigid, but rather undergo significant shear deformations that contribute greatly to global drift. Therefore, the "rigid joint" assumption may result in misinterpretation of the global performance characteristics of frames and could consequently lead to miscalculation of strength and ductility demands on constituent frame members. The primary objective of this paper is to propose a rational method for estimating the hysteretic joint shear behavior of RC connections and for incorporating this behavior into frame analysis. The authors tested four RC edge beam-column-slab connection subassemblies subjected to earthquake-type lateral loading; hysteretic joint shear behavior is investigated based on these tests and other laboratory tests reported in the literature. An analytical scheme employing the modified compression field theory (MCFT) is developed to approximate joint shear stress vs. joint shear strain response. A connection model capable of explicitly considering hysteretic joint shear behavior is then formulated for nonlinear structural analysis. In the model, a joint is represented by rigid elements located along the joint edges and nonlinear rotational springs embedded in one of the four hinges linking adjacent rigid elements. The connection model is able to well represent the experimental hysteretic joint shear behavior and overall load-displacement response of connection subassemblies.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.343-358
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• 2008

Piles of a bridge pier are connected with a column through a pile cap(footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. This difference causes a change of the design method. Connection methods between pile heads and the pile cap are divided into two groups ; rigid connections and hinge connections. KHBDC(Korea Highway Bridge Design Code) has specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However some specifications prescribe that conservative results through investigations for both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which have very good quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) are unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the very large diameter drilled shaft and the pile cap for Incheon Bridge which will the longest bridge in Korea were investigated through the full modeling for rigid connection conditions.

• 한국건축시공학회지
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• 제12권4호
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• pp.415-425
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• 2012

공동주택의 리모델링 수월성, 장수명화, 자원저감, 친환경 구조시스템 구현을 위하여 라멘구조인 그린프레임 공법이 개발되었다 그린프레임의 주요 구조부재인 합성 프리캐스트 콘크리트 기둥과 보는 접합부 철골과 콘크리트에 의한 접합으로 신속하고 정밀하게 설치할 수 있다. 그린프레임의 접합부는 그 형상에 따라 네 종류로 분류할 수 있으며, 각 종류에 따라 각기 접합 특성과 시공방법이 다르다. 현장상황에 적합한 기둥을 선택하기 위해서는 기둥 종류별 접합부 특성 비교 연구가 필요하다. 따라서 본 연구에서는 기둥 종류별 접합부의 공기, 원가, 품질, 안전성능 비교 분석하는 것을 목적으로 한다. 본 연구의 결과는 GF 공법의 설계단계에서 프로젝트 특성을 반영한 적정 합성 프리캐스트 콘크리트 기둥을 선정하는데 활용된다.

• 대한치과의사협회지
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• 제56권11호
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• pp.605-614
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• 2018

PURPOSE. The purpose of this study is to determine the efficacy of the DENTIS submerged-type implant with an internal hex connection and to build corresponding abutment-selection criteria. MATERIAL AND METHODS. A total of 204 patients received submerged implant fixtures with an internal hex connection at the Dong-A University Hospital Dental clinic in Busan from January 2013 and May 2016. Three specific abutments, UCLA abutments, customized abutments, ready-made abutments, were randomly selected. Implant success was defined as the basis of the International Congress of Oral Implantologists(ICOI, 2007) criteria. The relationship between the implant success rate and the abutment factor was analyzed using the Kruskal-Wallis test(P<.05). RESULTS. A total of 508 implants were placed in 204 patients. After a mean observation period of 38.6 months, 493 out of 508 implants were in normal function, yielding an overall success rate of 97.05%. A total of 15 implants failed: 10 in the maxillary molar area, 4 in the mandibular molar area, and 1 in the mandibular incisal area. All of the implant failures occurred in a single-implant prosthesis, especially high in the maxillary molar area. The Kruskal-Wallis analysis showed that abutment selection has no significant correlation with implant failure(P>.05). CONCLUSION. DENTIS submerged implants with an internal hex connection showed predictable results with a success rate of 97.05%. It is no influence on the success rate in the selection of submerged implant abutment with an internal hex connection.

• 대한건축학회논문집:구조계
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• 제35권4호
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• pp.135-146
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• 2019

Deep beam has high section modules compared with shallow beam of the same weight. However, deep beam has low rotational capacity and high possibility of brittle failure so it is not possible to apply deep beams with a long span to intermediate moment frames, which should exhibit a ductility of 0.02rad of a story drift angle of steel moment frames. Accordingly, KBC and AISC limit the beam depth for intermediate and special moment frame to 750mm and 920mm respectively. The purpose of this paper is to improve the seismic performance of intermediate moment frame with 1200mm depth beam. In order to enhance vulnerability of plastic deformation capacity of deeper beam, Multi-Reduced Taper Beam(MRTB) shape that thickness of beam flange is reinforced and at the same time some part of the beam flange width is weakened are proposed. Based on concept of multiple plastic hinge, MRTB is intended to satisfy the rotation requirement for intermediate moment frame by dividing total story drift into each hinge and to prevent the collapse of the main members by inducing local buckling and fracture at the plastic hinge location far away from connection. The seismic performance of MRTB is evaluated by cyclic load test with conventional connections type WUF-W, RBS and Haunch. Some of the proposed MRTB connection satisfies connection requirements for intermediate moment frame and shows improved the seismic performance compared to conventional connections.

• 한국습지학회지
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• 제18권4호
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• pp.331-341
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• 2016

본 연구에서는 둠벙의 수서곤충군집과 식물 군집에 영향을 주는 수환경 특성을 확인하고자 민통선에 존재하는 5개 유형 16개 둠벙을 선택하여 물의 화학적 특성과 둠벙과 주변 환경과의 연결 특성을 조사하였다. 둠벙의 유형으로는 괸물, 괸물-물흐름, 샘통, 괸물-샘통 그리고 물흐름-샘통형을 사용하였다. 연중 이온의 농도 변화는 괸물형 둠벙에서 가장 작았고 샘통형 둠벙에서 가장 컸다. 음이온 농도가 가장 높은 곳은 괸물형 둠벙이었으며, 양이온 농도가 가장 높은 곳은 물흐름-샘통형 둠벙이었다. 연구 장소에서 발견된 식물은 228종이었으며, 이중 습지 식물이 63종이었다. 수서곤충은 95종이 발견되었다. 확인된 희귀식물은 6종이었고, 희귀수서곤충은 4종이었다. 괸물-샘통형 둠벙에서 종풍부도가 가장 높았다. 둠벙의 크기와 종풍부도는 상관관계가 없었으며, 다변량 통계를 통해 분석한 결과 둠벙 유형별로 생물군집에서 차이가 나는 것으로 나타났다. 본 연구를 통해 둠벙에서 수환경 변화와 주변 환경과 둠벙의 연결성이 생물군집에 영향을 주는 것으로 확인되었으며, 둠벙은 담수생태계로서 이질성을 높여 농업지역의 생물다양성을 높이는데 기여함을 확인하였다.

• 천문학회보
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• 제33권1호
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• pp.28.1-28.1
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• 2008

• East Asian mathematical journal
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• 제19권2호
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• pp.261-271
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• 2003

We deal with two metrics of Randers type, which are characterized by the solution of certain differential equations respectively. Furthermore, we will give the condition for a Finsler space with such a metric to be a locally Minkowski space or a conformally flat space, respectively.

• 천문학회보
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• 제34권1호
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• pp.149.1-149.1
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• 2009