• 한국지반환경공학회 논문집
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• 제24권1호
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• pp.5-14
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• 2023

본 연구에서는 설계 대상인 현장타설말뚝기초에 대하여 상사율을 고려한 하중전이 대형토조 모형시험과 3차원 수치해석을 수행함으로써 현장타설말뚝 선단부와 주면부의 하중전이 특성을 분석하고 하중분담율을 산정하였다. 대형토조 모형시험 및 3차원 수치해석 결과에서 나타난 현장타설말뚝의 선형적 거동으로부터, 본 연구의 설계 조건에 대한 주면하중전이곡선은 Baquelin 등의 제안식, 선단하중전이곡선은 Baquelin 등의 제안식, 수평하중전이곡선은 Reese 등의 제안식이 적정한 것으로 확인되었다. 암반근입부에서 축하중은 시험값이 수치해석값보다 약간 크게 측정되었지만 암반 근입부에서 하중분담율은 연직하중이 증가함에 따라 평균적으로 약 27.8%의 분담율을 나타내었다. 연직재하 시에 말뚝두부의 침하량은 해석값이 시험값보다 약간 작게 평가되었으며, 모형시험 및 해석 최대 연직하중에서 말뚝두부의 최대 침하량은 시험치 10.6mm, 해석치 10.0mm 이고, 말뚝선단에서 최대 침하량은 시험치 2.0mm, 해석치 1.9mm로 나타났다. 수평재하 시에 기둥 두부(지표)와 말뚝 두부에서 수평변위는 시험값과 해석값이 비교적 잘 일치하는 것으로 나타났고, 모형토조시험 결과 최대 수평변위 38.0mm에서 측정된 수평하중은 24,713kN, 수치해석에서의 수평하중은 26,073kN으로 평가되었다.

• 열처리공학회지
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• 제13권1호
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• pp.10-15
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• 2000

Evaluation of long term stability of the Brinell standard hardness tester was carried out to secure its application as a national standard in Brinell hardness. Accuracy and repeatability in load application were tested through evaluating errors in hardness measurement of certified reference blocks. All of those requirements in KS as well as ISO specifications were satisfied by this standard hardness tester. In addition to this, long term stability test of automatic indentation measurement system was carried out. The scattering range was almost the same with its error range. To figure out an optimum test condition for better repeatability and long term stability, the effect of load variation, load application speed and time have been studied using orthogonal array experimental plan. It was found that the best combination is $30{\mu}m/s$ of load application speed and 25 seconds of load application time.

• 설비공학논문집
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• 제18권12호
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• pp.947-954
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• 2006

Building energy consumption according to the ventilation has been considered to be an important subject. The purpose of this study is to investigate the cooling and heating loads in a test space with a forced ventilating system. In the test space, on/off controlled air-conditioning and forced ventilating facility were operated between 8 : 30 to 21 : 00 during 4 days and some important data like temperatures and energy consumption were measured to obtain actual thermal loads. The simulation was carried out in a mode of temperature level control using a TRNSYS 15.3 with a precisely measured air change amount and performance data of air-conditioner. Heating load and cooling load including sensible and latent were compared between by experiment and by simulation. Both of thermal loads associated with ventilation show a close agreement within an engineering tolerance.

• 한국생산제조학회지
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• 제24권3호
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• pp.355-362
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• 2015

Test procedure for the design verification of wind turbine pitch and yaw bearings has been developed. Test items were selected to evaluate operational reliability of pitch and yaw bearings by considering loading and operational conditions, and by analyzing the design criteria of pitch and yaw bearings. The developed test items consisted of preliminary test, fatigue load test, extreme load test, low temperature environmental test and dismantling inspection after all the test were completed. Because it reflects the actual operational conditions of the pitch and yaw bearings, the developed test procedure has high reliability and can verify the basic design considerations in the international standard and guidelines.

• 농업과학연구
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• 제47권4호
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• pp.1123-1134
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• 2020

The goal of this study was to develop an accelerated life test for an implement working pump for an agricultural tractor. The field experiments were conducted to measure the load of an implement working pump during major agricultural operations such as plow tillage, rotary tillage, baler operations, and wrapping operations. The measurement system for an implement working pump load was constructed using a pressure sensor, the engine rotational speed, and the hitch pump displacement. The measured implement working pump load was calculated as an equivalent load for each agricultural operation using the Palmgren-Miner rule, which is a cumulative damage method. The equivalent load was calculated using the total load data and peak load data when the total data included the operation of an implement working. The annual usage time of the agricultural tractor was applied to develop two integrated equivalent loads. The acceleration factor was calculated to develop an accelerated life test and was calculated from the two integrated equivalent loads, the maximum pressure, and the flow rate conditions of the hitch pump. In Korea, the warranty life of a tractor is 2,736 hours, and the time required for the test to guarantee the operational life of tractors was calculated as 7,561 hours. The acceleration factors were calculated as 453.6 and 38.3, respectively, from the total load data and peak load data. The fatigue test time can be shortened by 16.7 and 197.4 hours according to the result of the acceleration factors.

• KCI Concrete Journal
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• 제14권2호
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• pp.61-68
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• 2002

An experimental investigation on the flexural fatigue behavior of a RC bridge slab retrofitted with Carbon Fiber Sheet (CFS) is presented. The test slab was almost identical to the slab of a highway viaduct in terms of the amount of reinforcement, quality of concrete and thickness of the slab, which was 18cm. Repeated load corresponding to 3.0, 4.5 or 6.0 times of the design load was applied to the test slab. Normal type and high-elastic modulus type of CFS were used for strengthening. The test slabs were loaded in dry or wet condition. Two different types of an-choring system were adapted. Some of the test slabs were damaged by the repeated load and retrofitted by CFS, then loaded again to see the improvement of the fatigue life. Infrared Thermography was also performed to investigate the debonding condition of CFS. From the test results, Carbon Fiber Sheet can be applied to the RC bridge slabs as a feasible retrofitting material.

• International Journal of Railway
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• 제8권1호
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• pp.1-4
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• 2015

An accurate measurement of the train-track interaction forces is important for track performance evaluation. In the field calibration test as a wheel load measurement process, the calibration system creates a different boundary condition in comparison with that in the train wheel passage. This study aims to evaluate a reliability of the field calibration test in the process of wheel load measurement. Finite element models were developed to compare the deformed shapes, bending moment and shear force profiles on the rail section. The analysis results revealed that the deformed shapes and their associated bending moment profiles on the rail are significantly different in two numerical simulations of the calibration test and the train wheel load passage. However, the shear stress profile on the rail section of the strain gauge installation in the field was almost identical, which may imply that the current calibration test is sufficiently reliable.

• Geomechanics and Engineering
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• 제7권2호
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• pp.201-212
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• 2014

Due to the sea-crossing bridge span is generally large and main pier pile foundations are located in deep water and carry large vertical load, sea-crossing bridge main pier pile foundations bearing mechanism and load deformation characteristics are still vague. Authors studied the vertical bearing properties of sea-crossing bridge main pier pile foundations through pilot load tests. Large tonnage load test of Qingdao Bay Bridge main pier pile program is designed by using per-stressed technique to optimize the design of anchor pile reaction beam system. Test results show that the design is feasible and effective. This method can directly test bearing capacity of main pier pile foundations, and analysis bearing behaviors from test results of sensors which embedded in the pile. Through test study the vertical bearing properties of main pier pile foundation and compared with the generally short pile, author summarized the main pier pile foundations vertical bearing capacity and the main problem of design and construction which need to pay attention, and provide a reliable basis and experience for sea-crossing bridge main pier pile foundations design and construction.

• 대한기계학회논문집A
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• 제25권3호
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• pp.478-485
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• 2001

A dynamic load simulator(DLS) which can reproduce on-ground the aerodynamic hinge moment of control surface is an essential rig for the performance and stability test of aircraft actuation system. By setting up load actuator as counter acting with the control surface driving actuator and designing an appropriate force control system for load actuator, DLS can be mechanized. Obtaining an accurate mathematical model for the DLS is the first step to successfully design an aerodynamic load replicati on system. Two theoretical models are presented and tested for their validities with the experimental results, which turns out to be not successful. An alternative way of using system identification approaches in investigated to develop a good nominal model for DLS dynamics, and suitable uncertainty bounds for this nominal model are proposed with the consideration of experimental results.

• 재활복지공학회논문지
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• 제6권1호
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• pp.51-58
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• 2012

본 연구에서는 근전도 신호를 기반으로 하여 환자의 재활 운동 시 발생하는 근 피로도의 변화에 따른 능동형 운동 부하 제어 시스템을 개발하였다. 본 능동형 부하 제어 시스템에 적합한 근 파라미터를 선정하기 위해 건강한 남성 12명을 대상으로 사전 실험을 수행하여 근전도 신호를 획득하였다. 또한 선정된 근 파라미터를 이용한 능동형 운동 부하 제어 시스템을 평가하기 위하여 근 골격계 질환이 없는 건강한 남성 10명을 대상으로 실험을 수행하였다. IEMG(Integrated electromyogram) 변화에 따른 운동 부하 변화를 관찰하여 개발된 능동형 부하 제어 시스템의 유용성 및 정확성을 확인하였으며, 개인의 주관적 피로도를 나타내는 운동자각도(rating of perceived exertion)를 활용하여 근 피로도와의 상관관계를 분석하였다. 따라서 본 연구에서 제안한 능동형 운동 부하 제어 시스템은 재활 운동 수행 시 환자 개개인에 적합한 초기 부하 및 운동량 조절에 유용할 것으로 사료된다.