• Journal of Biosystems Engineering
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• 제18권3호
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• pp.220-229
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• 1993

A dimensional analysis was carried out to investigate if model agricultural radial tire can predict the tractive performance of prototype tires. Experimental data was analyzed to prove the results of dimensional analysis. The results was summerized as follows ; 1. When the model and prototype tires are tested under the same soil conditions, inflation pressure, slip and dynamic load, traction coefficient ratio between two tires depend on the geometry of two tires. 2. According to the regression analysis of the experimental data, traction equation parameters of the prototype tires can be predicted from the that of model tire 3. Predicted traction coefficient of prototype tire, calculated from the traction equation paramters, showed good correlation with that of experimental results. Thus it was possible to predict net and gross traction of prototype tire from the model traction equation parameters.

• Journal of Biosystems Engineering
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• 제14권2호
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• pp.67-79
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• 1989

This study was conducted to investigate the applicability of true model theory for pull prediction in a powered lugged wheel-soil system and to examine the possibility of using principles of similitude in investigating the dimensions of soil parameters pertinent to a powered lugged wheel-soil system concerning the pull prediction. The following conclusions were derived from the study; 1) The pull of prototype wheels proved to be predicted by those of the model wheels for the range of the dynamic weight tested. The pull curves of models and prototype were respectively very similar in the shape. From this basic knowledge, it was enabled to apply the similitude theory to the performance prediction of the true model. 2) A conditional equation which can be used for the prediction of pull of prototype by model test was derived as follows. $n_f=n_1^{-b}$ where $n_f$ : force scale = $w/w_m$ $n_1$ : length scale = ${\ell}/{\ell}_m$ b : exponent on the length dimension of the soil property ${\alpha}$ The range of the numerical value of b, which was determined by the least square method, was found to be -2.0~-2.6. 3) Considering a relatively wide variation of b values in the pull prediction, b is considered to be a function of many variales. Thus it was concluded that there are several soil properties which are pertinent to the powered lugged-wheel-soil system concerning the pull prediction, and these soil properties may have the different effects on the pull of model and protytype wheels, to give the different dimension on the soil parameters.

• Journal of Biosystems Engineering
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• 제14권3호
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• pp.158-167
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• 1989

This study was conducted to investigate the applicability of true model theory in a powered lugged wheel-soil system and to examine the possibility of using principles of similitude in investigating the dimensions of soil parameters pertinent to a powered lugged wheel-soil system concerning the sinkage prediction. The following conclusions were derived from the study; 1) The sinkage of prototype wheels proved to be predicted by those of the model wheels for the range of the dynamic weight tested. 2) A conditional equation which can be used for the prediction of sinkage of prototype by model test was derived as $n_f=n{_\ell}{^{-b}}$. The range of the numerical value of b, which is the exponent on the length dimension of the soil property ${\alpha}$, was found to be -1.48~-2.54. 3) Considering a relatively wide variation of b values, it was concluded that there are several soil properties which are pertinent to the powered lugged-wheel soil system concerning the sinkage prediction.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.912-921
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• 2009

Pulse-discharge technology (PDT) is an innovative technology which uses enormous energy developed by electric discharge for a very instant moment of time. Lately, it has been applied to make expanded sections at the ends of piles and anchors. The expanded section is formed by the deformation of bore-hole induced by shockwave energy developed in filling material by the pulse discharge. In this study, considering the phenomenon of pulse-discharge as an underwater explosion, finite element analyses were carried out to model the shockwave development by pulse discharge. The simulation technique was verified by comparing results with underwater discharge test results.

• 산업기술연구
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• 제20권B호
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• pp.95-103
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• 2000

A model trains must have similitude with its original model not only in shape but also in motion. Motion characteristics of a model train under considerations are maximum velocity in straight and circular tracks and stopping distance. Equations of motions are derived to obtain maximum speed and stopping distance based on the Newton's Second Law and the energy principal. To accurately predict traction and resistance force between wheel and rail. wheel slip, or creepage, is taken into consideration. To verify the equations of motion, various experiments have been carried out including measurement of gear efficiency, location of mass center, rolling resistance force, traction force, slip, maximum velocity and stopping distance. This paper addresses how the experiments are setup and carried out in detail. Also the results of experiments are compared with the analytical prediction, which showed good agreements with each other.

• 농업과학연구
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• 제12권1호
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• pp.108-117
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• 1985

파종기(播種機)의 복토장치(覆土裝置) open auger의 토양이송과정(土壤移送過程)을 이론적(理論的)으로 분석(分析)하여 이송효율(移送效率)을 산출(算出)할 수 있는 이론적(理論的)인 동력효율식(動力效率式)을 유도(誘導)하고, open auger의 회전속도(回轉速度)의 적정범위(適定範圍), 그러고 auger 내(內)에서 토양(土壤)의 축방향(軸方向) 토립자(土粒子) 이송속도(移送速度)를 구명(究明)하였다. Open auger의 특성(特性)의 이론적(理論的)인 분석(分析)과 분석응용(分析應用)의 결과(結果)는 다음과 같다. 1. 동력효율(動力效率)의 예측식(豫測式)은 다음과 같다. ${\eta}_p={\frac{P_n}{P_g}}=({\frac{{\omega}_s}{{\omega}_a}}){\cdot}tan{\gamma}{\cdot}{\frac{mg}{F_mcos{\alpha}+F_scos{\gamma}}}$ 2. 보다 적은 동력(動力)으로 소정(所定)의 폭(幅)까지 토양이송(土壤移送)이 원활(圓滑)히 이루어질 수 있는 open auger의 회전속도(回轉速度)의 적정범위(適定範圍)는 다음과 같다. $$\frac{4d(L_a-L_i){\cdot}V_w}{{\pi}(D_o^2-D_s^2)r{\cdot}{\frac{{\omega}_s}{{\omega}_a}}{\cdot}tan{\gamma}}{{\leq_-}}{\omega}_a{{\leq_-}}({\frac{{\omega}_a}{{\omega}_s}}){\sqrt{\frac{g}{r}}}$$ 3. Auger 내(內)에서 토양(土壤)의 축방향(軸方向) 이송속도(移送速度)는 다음식(式)으로 구할 수 있다. $V_h=({\frac{{\omega}_s}{{\omega}_s}})V_a{\cdot}tan{\gamma}$ 4. Auger의 회전속도(回轉速度)는 다른 여러 인자(因子)들보다 동력효율(動力效率)에 가장 크게 영향(影響)을 미치는 것으로 나타났다.

• 한국지반환경공학회 논문집
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• 제24권7호
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• pp.5-14
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• 2023

최근 국내·외에서 지진이 자주 발생하고 있다. 이러한 지진은 다양한 형태의 자연적 피해와 물리적 피해의 원인이 된다. 특히, 지반이 액체와 같은 거동을 보이는 액상화는 구조물에 큰 피해를 발생시킨다. 이에 다양한 액상화 피해 저감 공법들이 연구 및 개발되고 있다. 이에 본 연구에서는 시트파일 공법을 이용하여 기존 구조물에 적용 가능한 지진 시 액상화 피해 저감 공법에 대해 연구하였다. 1-G 진동대 실험을 수행하였고 주문진 표준사로 지반을 조성하였다. 상사 법칙을 적용하여 2층 규모의 모형 구조물을 제작하였고, 입력파는 가속도 수준 0.6g와 주파수 10Hz의 정현파를 적용하였다. 다양한 근입비에 따른 구조물 피해 저감 효과를 분석하였다. 연구 결과, 시트파일 공법을 적용하여 지반을 보강하였을 때의 구조물 침하가 지반 보강을 하지 않았을 때보다 약 71% 정도 감소하였으며, 최소 침하량을 보인 근입비는 "1"이었다. 그리고 근입비가 증가할수록 시트파일로 인해 지반 내 간극수압의 소산이 지연되는 경향을 보였다. 이러한 결과를 바탕으로 근입비에 따른 구조물 침하와의 관계를 그래프와 관계식으로 제안하였다. 본 연구 결과는 향후 기존 구조물에 적용 가능한 시트파일 공법을 개발하는데 있어 기초자료로 사용될 수 있을 것으로 기대된다.