• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.69-75
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• 2014

Rock fall protection system installed against rock slope is one of the most conventional way to protect nearby infra structures. Despite of wide application of typical rectangular nets, virtually installed to protect rock slope face, several problems have also been pointed out up to date. Rectangular draped nets are vulnerable to a sudden external shock such as rock fall, because it doesn't have any systematical buffers or shock absorbers. Furthermore, it has been widely recognized from the some cases of rock fall accident in Korea that rock fall protection nets cause wide range of failure in the rock slope faces due to insufficient pullout bearing capacity of fixing parts. Therefore, in this study, we tried to make a consideration about the problems of existing standard rock fall protection nets in Korea, and develop a new type of hexagonal net with a shock absorber based on design rock fall energy. In this paper, laboratory and full scale test procedure is described to analysis the performance of newly developed hexagonal rock fall net, and the key results are presented and discussed.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.35-45
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• 2013

The concrete-filled tube column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. It suggests that pipe should be produced by welding two sides together where two shapes are joined after a channel is pre-welded onto the three sides in order to form an internal diaphragm. The upper diaphragm of the connection used the horizontal plate and the lower diaphragm used the Vertical plate. This research performed 6 monotonic tension experiments describing the connection upside and downside in order to evaluate the structural capability of the offered connection. And the cyclic loading experiment was performed about 2 T-Type column to beam connections. As to the experimental result edge cutting geometry, there was no big effect. An increase in the number of holes of the plate ultimate strength was increased by 5% and The thickness of the plate increases, the maximum strength was increased by 4%. T-Type connections until it reaches the plastic moment showed a stable behavior.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.296-304
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• 1995

환경시험의 일부인 진동시험은 그 결과를 가지고 장비가 실제 운용하기 전에 진동에 대한 내구성이 있는가를 판단할 수 있는 단 하나의 방법이다. 이런 진동시험을 성공적으로 이끌어 정확한 결론에 도달하기 위해서는 아래 두 가지 문제에 대한 해결이 필수적이라고 생각한다. 첫번째는 '실제 상황을 정확히 반영할 수 있는 진동시험수준의 결정이다.' 진동시험수준이 적절하지 못하면 전체적으로나 부분적으로 과대진동시험(Overtest)을 실시하거나, 과소진동시험(Undertest)을 실시할 수 밖에 없고, 이에 따른 결과도 신뢰도가 떨어진다. 예를 들어, 과대진동시험으로 시험장비가 고장나거나, 과소진동시험으로 시험장비에 이상이 없다고 해서 실제 상황에서 이 장비가 진동에 대하여 만족할 만한 내구성을 갖는다고 누구도 말할 수 없기 때문이다. 두번째는 '정해진 진동시험수준을 진동시험기로부터 시험장비에 얼마나 정확히 전달할 수 있는가?'라는 문제이다. 실제로 원하는 진동시험수준을 한치의 오차없이 정확히 시험장비에 가하는 것은 거의 불가능하다. 특히 시험장비가 대형화 되면 될수록 문제는 더 심각하다. 결론적으로 위에 지적한 두가지 문제의 해결이 성공적인 진동시험의 열쇠이며, 또한 시험결과에 대한 신뢰성을 보장받을 수 있는 길이기 때문이다. 이번 논문에서 다루고자 하는 것은 두번째 문제인 진동시험수준의 정확한 전달을 위하여 진동시험기와 시험장비 사이를 연결해 주는 진동시험치구(Test Fixture) 개발에 관한 것이다. 실제 개발한 치구는 미군사규격(Military-Standard)과 보잉사 규격(Boeing specification) 그리고 샌디아사 규격(Sandia Corporation Standard)에 근거하여 분류하는 분류기준표에서 치구 중 가장 큰 부류(500 pounds 이상)에 속는 것으로, 현재 우리나라에서 보유하고 있는 것 중에 용량이 가장 큰 진동시험기에서 진동시험을 준비하고 있는, 체계에 전원을 공급하는 대형장비의 치구이다. 또한 실 진동시험을 실시하기 전의 모달시험과 예비시험 그리고 실 시험결과를 기술하므로써 제작된 치구의 실험적 평가를 하고자 한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.217-222
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• 2002

본 연구에서는 가연성 폐기물을 이용한 시설원예 난방에너지 공급시스템 개발을 위하여 대형 온실 난방이나 RPC 시설에 이용할 수 있는 왕겨와 중유 겸용연소 시스템에서 중유의 연소 및 성능 특성을 분석하고자 하였다. 중요 인자로는 분사노즐의 크기(2.0, 2.25, 2.5, 3.0 GPH)와 진공압력(375, 500, 625, 750 Pa)을 설정하였으며 이에 대한 결과를 요약하면 다음과 같다. 1.진공압력 500Pa조건에서 연료 공급율이 증가할수록 연소실 벽체 열교환기 효율은 감소하고 폐열회수 열교환기와 사이클론 열교환기의 효율이 증가하였으며, 노즐 2.5GPH에서 진공압력이 커질수록 연소실 하부의 온도가 감소하였고 연소실 상부에서는 비슷한 경향을 보였다. 2, 연소온도특성, 열효율, 배기가스 성분분석 등의 결과로 볼 때 최적의 연소 조건은 노즐 2.5GPH는 진공압력 375Pa, 노즐3.0GPH는 진공압력 500Pa과 625Pa 사이로 판단되었다. 3. 배연가스내의 대기오염 성분은 모든 실험처리에서 CO 함량은 거의 없고 SO$_2$와 NO$_{x}$의 함량 또한 일반 보일러 허용기준을 만족하는 것으로 나타났다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.889-900
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• 2013

In a large scale of excavation for the foundation of large-sized structures and underground structures, a considerable amount of earth pressure can occur. Steel beams that have been used to form a temporary structure to support earth pressure may be less economical and less efficient in resisting the high earth pressure. To cope with this problem, PCT(Precast Concrete Truss) system has been devised and investigated both experimentally and analytically. A proper connection method between the concrete truss members was proposed to accommodate fast assembly and disassembly. Full-scale test of PCT system was performed to verify the load-carrying capacity of the PCT system including the connections. The test results were compared with those of structural analysis. The test specimen which corresponds to PCT strut attained the ultimate load without buckling, but the detail of connector members needs to be improved. It is expected that precast concrete truss members can be efficiently incorporated into a temporary structure for deep and large excavation by replacing conventional steel beams.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.483-492
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• 2007

Pre-Engineering Building (PEB) system is one of the most economical structural systems. Tapered members can resist a maximum stress at a single location, whereas stresses of the rest of the members are considerably low. This results in appreciable savings both in terms of materials and construction costs. However, it was appreciated that special consideration would be required for certain aspects of this structural form. In particular, because of their slenderness, webs would buckle laterally and torsionally under the combined action of excessive axial, bending and shear forces. In this study, a total of four large-scale rafters with simple ends were tested. The main parameters were the width-thickness ratio of the web, the stiffener, and the flange brace. The purpose of this experiment is to evaluate the structural stability and to offer back-data on PEB design.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.267-274
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• 2004

The objective of this study is to evaluate tensile load transmission capacity of H-shaped beam about design load by stud connector. The basic test of stud connecter was conducted and two specimens of full-scale size were tested under monotonic tensile loading condition. The parameter of tests is the size of the H-shaped beams. The results show that tensile load transmission capacity of H-shape beam about design load by stud connectors is excellent observing to the design code of steel structures of Architectural Institute of Korea.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.247-255
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• 2004

An experimental program was undertaken to develop seismic retrofit methods of existing steel moment connections with floor slab for improved seismic performance. Five full-scale composite specimens were tested under cyclic loading. Conventional through-diaphragm connections [please check this; no search results were found for through-diaphragm connections] composed of square-tube column and H-beam were retrofitted by adding either a bottom-flange dogbone (RBS) or an improved welded horizontal stiffener at the beam bottom flange. The effectiveness of the proposed retrofit connections schemes was evaluated. The specimen retrofitted using the RBS concept at the bottom flange showed poor connection ductility. In contrast. specimens with the proposed horizontal stiffener details exhibited improved connection ductility.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.1-9
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• 2009

When a rock slope is excavated adjacent to a existing tunnel, the behavior of the existing tunnel in the jointed rock masses is greatly influenced by the joint conditions and slope status. In this study, the effects of joint dip and slope angle close to a tunnel are investigated through a large scale model using a biaxial test equipment ($3.1\;m\;{\times}\;3.1\;m\;{\times}\;0.50\;m$ (width $\times$ height $\times$ length)). The jointed rock masses were built by concrete blocks. The diameter of the modeled tunnel is 0.6 m and the dip angles of joint vary in the range of $0-90^{\circ}$. In addition, the excavated slope angle varies within $30{\sim}90^{\circ}$. Deformational behaviors of the tunnel were analyzed in consideration of joint dip and slope angle. With increase of the joint dip and slope angle, the magnitude of tunnel distortion and the moment of tunnel lining were increased. Rock mass displacement in horizontal was also dependent on the joint dip and the excavated slope angle, which indicated the optimal slope reinforcement for a specific rock mass conditions.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.252-260
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• 2015

Ballasted track on an asphalt roadbed can be beneficial for its various effects such as (i) decreasing of roadbed thickness by dispersing train load; (ii) prevention of both strength reduction and weakening in roadbed system by preventing rainwater penetration; and (iii) reducing maintenance cost by preventing roadbed mud-pumping and frostbite. With these beneficial effects, ballasted track on asphalt roadbed has been widely used in Europe and Japan, and relevant research for applying such ballasted track on asphalt roadbed systems in Korea is ongoing. In this study, full-scale static and dynamic train load tests were performed to compare the performance of ballasted track on asphalt roadbed and ballasted track. The optimum thickness levels of asphalt and reinforced roadbeds, corresponding to the design criteria for reinforced roadbed of high-speed railway, was estimated using the FEM program ABAQUS. Test results show that the earth pressure on reinforced roadbed of ballasted track on the asphalt roadbed was relatively low compared with that of simple ballasted track. The elastic and plastic displacements of simple ballasted track on the asphalt roadbed were also lower than those of ballasted track. These test results may indicate that the use of ballasted track on asphalt roadbed is an advantageous system in view of long-term maintenance.