• 대한토목학회논문집
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• 제40권4호
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• pp.393-400
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• 2020

헬리컬 파일의 수직 및 수평 거동은 헬릭스의 개수, 직경, 피치, 위치등의 변수에 영향을 받는다. 본 연구에서는 헬리컬 파일의 헬릭스 개수를 3개로 고정하고, 헬릭스의 위치, 직경, 피치를 변화시켜 가며 수직 및 수평 거동을 분석하였다, 특히, 헬릭스는 일반적으로 나선형의 입체적인 구조를 가지기 때문에, 헬리컬 파일 상부에 작용하는 수평하중방향이 헬리컬 파일의 수평 거동에 미치는 영향을 분석하였다. 이를 위하여 축소모형의 헬리컬 파일을 이용하여 실내모형실험을 수행하였으며, 이 결과를 같은 모델의 수치해석 결과와 비교하여 두 결과의 타당성을 확보하였다. 이후, 수치해석적으로 다양한 헬리컬 파일 형상을 가정하여 수직 및 수평 거동을 분석하였다. 결과적으로, 가정한 환경에 대해서는 헬릭스의 위치와 피치의 간격보다는 헬릭스의 직경이 수직 및 수평 지지력에 가장 큰 영향을 미치는 것으로 확인되었다.

• 대한기계학회논문집A
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• 제40권8호
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• pp.743-750
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• 2016

트랙롤러는 건설기계의 무한궤도 메카니즘에 장착되어 차량에 가해지는 하중을 지지하는 역할을 하는 핵심부품이다. 건설기계의 작업환경은 매우 가혹하며, 이러한 환경에 노출된 트랙롤러는 반복되는 주행충격으로 누유 및 파손 등의 고장을 발생하게 된다. 트랙롤러의 고장이 발생하면 건설기계 차량의 주행에 큰 영향을 미치게 되므로, 트랙롤러 생산업체에서는 자체시험을 수행하여 제품의 성능을 확인하고 있다. 하지만 현재 트랙롤러 대부분의 시험은 수직하중을 가한 상태의 시험만을 수행하고 있다. 이는 트랙롤러가 장착된 건설기계의 선회주행시 발생되고 있는 수평방향에서 가해지는 하중을 고려하지 않은 시험평가로 실제 주행조건을 재현하지 못하는 문제점이 있다. 따라서 본 논문에서는 트랙롤러에 가해지는 수직 및 수평방향 하중 크기와 이를 고려한 시험조건을 정립하였다. 또한 수평방향 하중이 트랙롤러의 고장에 미치는 영향에 대한 해석과 시험의 결과를 제시하였다.

• 한국지반공학회논문집
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• 제23권10호
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• pp.163-174
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• 2007

큰 선행하중을 가할 수 있는 새로운 선행하중 시스템을 개발하였으며, 이를 적용하여 근접굴착 시 기존 터널의 안정성을 확보하는 방안을 연구하였다. 흙막이 벽체의 수평변위가 거의 생기지 않도록 설계축력 이상의 선행하중을 가하였다. 이를 위해 선행하중을 가하지 않는 경우와 선행하중을 가하는 경우에 대해 축소율 1/10인 실 대형 시험을 실시하였다. 수치해석은 선행하중을 가하지 않는 경우와, 선행하중을 설계축력의 50%와 100%를 가하는 경우, 흙막이 벽체 변위를 거의 발생시키지 않는 크기의 선행하중을 가하는 경우에 대해 유한요소법(FEM) 프로그램인 PLAXIS를 사용하여 수행하였다. 그 결과 선행하중을 설계축력 이상으로 적용시켜 흙막이 벽체변위를 억제시켰을 때 벽체 배면 지반에 있는 터널의 안정성이 크게 향상되는 것을 확인할 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.505-510
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• 2007

Greenhouses should be heated during nights and co Id days in order to fit growth conditions in greenhouses. Ground source heat pump(GSHP) or geothermal heat pump system(GHPs) is recognized to be outstanding heating and cooling system. Horizontal GSHP system is typically less expensive than vertical GSHP system but requires wide ground area to bury ground heat exchanger (GHE). In this study, a horizontal GSHP system with thermal storage tank was installed in greenhouse and investigated as performance characteristics. In the daytime, heating load of greenhouse is very small or needless because solar radiation increases inner air temperature. The results of study showed that the heating coefficient of performance of the heat pump($COP_h$) was 2.9 and the overall heating coefficient of performance of the system($COP_{sys}$) was 2.4. Heating energy cost was saved 76% using the horizontal GSHP system with thermal storage tank.

• 소성∙가공
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• 제22권2호
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• pp.67-73
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• 2013

The deformation characteristics and microstructure changes in a round copper pipe under biaxial compression was studied using a horizontal compression die. The change of material properties, punch load and deformation behavior were monitored using various compressive deformation rates in the range of 0.5mm/min.~450mm/min. The strains, either tensile or compressive, were estimated from Vickers microhardness test results. The punch load and deformation characteristics of the round copper pipes were found to change greatly at a deformation rate of about 200mm/min. The punch load decreased with increasing compressive deformation rate. The results of numerical simulations agreed well with what was expected from the final microstructure and the hardness profile estimated from the final deformation strains.

• 상하수도학회지
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• 제26권1호
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• pp.13-20
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• 2012

In this paper, we present the result of an investigation pertaining to the pipe stiffness of buried flexible pipes. Pipe stiffness (PS) formula for the parallel plate loading condition is derived based on the elasticity theory. Vertical and horizontal displacements are also derived. Vertical deflection is always larger than the horizontal deflection because some of energy due to overburden load is stored in the pipe but the difference is negligibly small. In the study, mechanical properties of the flexible pipes produced in the domestic manufacturer are tested and the results are reported in this paper. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is less than 14% although there are significant variations in the mechanical properties of the pipe material. Therefore, it was found that the finite element analysis can be used to predict the pipe stiffness instead of conducting parallel plate loading test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.401-406
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• 2013

This paper presents experimental evaluation of IRE (isolation roller bearing) seismic isolation device. From the combination of base isolation on the IRE system displacement response spectrum and acceleration response spectrum, the compressive strength and the coefficient of friction experiments. Also the IRE system is evaluated by environment test according to KS standards. Both the resonance and seismic experiments using a combination of the IRE and Natural Rubber Bearing (NRB) are performed in order to analyze the seismic isolation of the IRE system dynamic characteristics. For the given load and exciting frequency, the resonant frequency becomes lower, but the resonant magnification remains to be same. However, it is shown that when we consider the IRE only, the vibration on the table with the horizontal movement and the independent horizontal displacement due to the rolling motion of the plate and roller are significantly reduced. This result verifies that the proposed optimal design method of the IRE system is very effective.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.620-627
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• 2009

Shaking table test was carried out to obtain dynamic characteristics of TLCDs with uniform and non-uniform sections for both horizontal and vertical tubes. The input to the table is harmonic acceleration with constant magnitude. The output is horizontal dynamic force which is measured by load cell installed below the TLCD. Transfer functions are experimentally obtained using the ratio of input and output. Natural frequency, the most important design factor, is compared to that by theoretical equation for TLCDs with five different water levels. System identification process is performed for experimentally obtained transfer functions to find the dynamic characteristics of head loss coefficient and effective mass of TLCDs. It is found that their magnitudes are larger for a TLCD with non-uniform section than with uniform section and natural frequencies are close to theoretical ones.

• 한국산업융합학회 논문집
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• 제21권5호
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• pp.219-225
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• 2018

In this paper, for the testing of tensile strength of dead-end clamp used in transmission line, resulting values were estimated by designing and producing the horizontal version of widely-used vertical tensile tester. Tensile strength test of dead-end clamp for transmission line is essential for quality test of products. Moreover, tensile tester is an equipment that requires high level of reliability which needs to be examined through sampling tests commensurate with total inspection. Frames of tensile tester were made up of H-beams so that it can endure more than 20 [tons] of load capability and the test was implemented for 60[seconds] applying five types of tension. In consequence, the tester could withstand up to 21,600[kg] of weight as well as all types of tension. This newly developed horizontal tensile tester can be utilized in figuring out properties of various materials by estimating tensile strength of materials such as metal, rubber and fiber.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.969-978
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• 2010

In this study, a laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use alternative material of sand in soft ground is performed. The vertical and horizontal coefficient of permeability of the recycled aggregates and crushed stone showed largely 1.2~4.0 times and 3.0~3.3 times greater than sand, respectively. Therefore, it showed enough to be an alternative material to the sand which had been being used as the vertical and horizontal drainage material before. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. When water level drops suddenly, the pore water pressure of the recycled aggregate and crushed aggregate is reduced to nearly zero. Therefore, it was applicable to the field because discharge capacity was similarity to that of sand. The settlement in crushed aggregates and recycled aggregate decreases gradually with the load increase. When water level drops suddenly, earth pressure in all drains materials was evaluated the equivalent drainage capacity similarity to sand because it show approaching the nearly zero.