• Journal of Biosystems Engineering
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• v.2 no.1
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• pp.33-48
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• 1977

Transporting agricultural products and the other material by the two-wheel-tractor (power-tiler)and trailer system may be one of its most widely used farming functions.The safety and hitching load for all the previaling performing conditions may be the general concern over the operation of the tiller-trailer system. In this study, a mathematical model to determine the static and dynamic forces excerting on the hitch point were developed . Based on the analysis of the model and the field measurements. the limiting hitching load and critical slope were analyzed. The results of the study are summarized as follows ; 1) The limit angle of slope land for the safety steering that two-wheel tractor-single axle trailer system was able to transport agricultural products was the direct angle (${\gamma}$) = 8 ; the cross angle$\beta$) 15 ; and it was decreased in accordance with the increase of carrying load ($W_4). 2) The critical velocity for safe operation in case of running on downward hill road was about 1.08m/sec. 3) The limiting carrying load for the safe steering was W$_4$=600kg. The degree of the safe steering for different braking methods was given in order as follows ; Simulataneous braking the tractor and trailer , braking the trailer only, and braking tractor only. 4) Among the three components of impact loads excerting on the hitch point, the component in the lateral direction ($P_{Vy}$) was near zero in spite of increase of hitching load ($W_4) , while the components in the other two mutually perpedicular directions ($P_{Vx}$ and ($P_{Vz}$) ) had larger values in horizontal plane than those in the slope lands. 5) Moment of forces on the lateral direction (M$y$) had the largest value among the three components of impact moment acting on the hitch point, however all the components were sharply increased in accordance with the increase of hitching loads ($W_4. Three components of the moment were the negative values.

• Water for future
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• v.29 no.2
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• pp.129-141
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• 1996

A procedure for computing total suspended sediment load is presented based on a single point-integrated sample, a power velocity distribution, and Laursen's sediment concentration distribution equation. The procedure was tested with field data from the Rio Grande River. Computed concentrations agreed well with depth-integrated measurements corrected for unmeasured load using nominal values of $\beta$, $\kappa$ and w. Even better agreement was obtained when site-specific data were used to define the x and z exponents of the velocity and concentration distributions. The difference between total suspended load computed using a single measurement and this procedure and conventional computations based on depthintegrated measurements is well within sampling error. There are major advantages in estimating total suspended load using a single time-integrated suspended-sediment point sample. Less field time is required; sampling costs are greatly reduced; and sampling can be more frequent and better timed to measure the changing sediment load. Single-point sampling makes automatic sampling procedures more feasible.

• Journal of Environmental Impact Assessment
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• v.18 no.5
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• pp.281-291
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• 2009

In Total Water Pollutant Load Management System of Korea, unit load approach based on land register data is currently used for the estimation of non-point pollutant load. However, a problem raised that land register data could not always reflect the actual land surface coverages which determine runoff characteristics of non-point pollution sources. As a way to overcome this, we tried to establish quantitative relationships between the aerial images (0.4m resolution) which reflect actual land surface coverages and the land registration maps according to the 19 major designated land-use categories in Kyeongan watershed. Analyses showed different relationships according to the land-use categories. Only a few land-use categories including forestry, road and river showed essentially identical and some categories such as orchard, parking lot and sport utility site showed no relationships at all between image data and land register data. Except for the two cases, all the other categories showed statistically significant linear relationships between image data and land register data. The analyses indicate that using high resolution aerial maps is a better way to estimate non-point pollutant load. If the aerial maps are not available, application of the linear relationships as conversion factors of land register data to image data could be an possible option to estimate non-point pollutant loads for the specific land-use categories in Kyeongan watershed.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.671-676
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• 2005

Spring is one of major suspension part of the light commercial vehicle (LCV). In the manufacturing process it is shot-peened to improve its fatigue strength. In this paper, residual stresses by shot peening were calculated through finite element analysis, and the effects of these residual stresses on fatigue strength of leaf spring were evaluated. Fatigue tests were performed with two kinds of specimens; one is actual leaf spring assembly, and the other is simulated 3-point bending specimen. Fatigue tests were performed under the loading condition that was measured on the proving ground. From the results, the maximum load-fatigue life relation of leaf spring was defined, and test results of 3 point bending specimen are in good agreement with those of leaf spring assembly. The effects of residual stresses by shot peening on fatigue strength of leaf spring is not large in the high load range, however, in the low load range, its effects were not negligible.

• Journal of the korean Society of Automotive Engineers
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• v.3 no.2
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• pp.18-26
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• 1981

The purpose of this paper is to study the possibility of practical use of gasoline-methanol mixed fuel as an alternative fuel of gasoline engines in the light of engine performances and harmful exhaust emissions as well as mixings and separations of the mixed fuels. When the methanol of 99.8% purity is mixed with super or regular gasoline available on the market today, the experimental results obtained without modifying carburetor in this study are as follows; 1.The separation ratio depends upon the gasoline-methanol mixing ratio only, regardless of fuel temperature and fuel additives for preventing separation of phase. 2.The critical absorption ratio is affected by the gasoline-methanol mixing ratio, its temperature and the quantity of fuel additives. 3.Concerning the distillation temperature, the initial point of all sorts of fuels is almost same,but 10% point and 35-60% point of mixed fuels are lower than those of gasoline only. 4.In case of throttle valve opening set, engine output using the mixed fuels is decreased compared to gasoline, but thermal efficiency is increased as a consequence of decreasing specific energy consumption. 5.In case of fixed load test, thermal efficiency is increased at low engine speed even under low part-load as well as under comparatively high part-load including full load. 6.CO and NOx emissions are reduced remarkably with the mixed fuels.

• Journal of Korean Association for Spatial Structures
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• v.4 no.3 s.13
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• pp.103-109
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• 2004

The lowest load when the equilibrium condition becomes to be unstable is defined as the buckling load. The primary objective of this paper is to be analyse stability boundaries for star dome under combined loads and is to investigate the iteration diagram under the independent loading parameter. In numerical procedure of the geometrically nonlinear problems, Arc Length Method and Newton-Raphson iteration method is used to find accurate critical point(bifurcation point and limit point). In this paper independent loading vector is combined as proportional value and star dome was used as numerical analysis model to find stability boundary among load parameters and many other models as multi-star dome and arch were studied. Through this study we can find the type of buckling mode and the value of buckling load.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.4
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• pp.161-167
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• 2000

This paper presents a new methodology that can evaluate transfer capability of composite power systems from the adequacy point of view in power system planning stages. First of all, to evaluate practical load supplying capability, nonlinear optimization problems of maximum load supplying capability(MLSC) and economic load supplying capability(ELSC) are formulated and solved by nonlinear primal-dual interior point method. Here, physical constraints considered in the optimization problems are the limits of bus voltage, line overloading, and real & reactive power generation. Also, an evaluation method of transfer capability is presented based on margins calculated by the MLSC and ELSC. Especially, to evaluate transfer capability flexibly, simple indices such as expected MLSC, transfer capability margin, and power not supplied are respectively proposed by considering (N-1) line outage probability. Numerical results on IEEE RTS 24, IEEE 118, and IEEE 300 bus system show that the proposed algorithm is effective and useful for power system planning stages.

• Journal of Applied Reliability
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• v.16 no.1
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• pp.26-31
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• 2016

Purpose: The purpose of this study was to investigate the effect of grinding process and thickness on the fracture strength of silicon die used for semiconductor substrate. Method: Silicon wafers with different thickness from $200{\mu}m$ to $50{\mu}m$ were prepared by chemical mechanical polishing (CMP) and dicing before grinding (DBG) process, respectively. Fracture load was measured by point load test for 50 silicon dies per each wafer. Results: Fracture strength at the center area was lower than that at the edge area of the wafer fabricated by DBG process, while random distribution of the fracture strength was observed for the CMPed wafer. Average fracture strength of DBGed specimens was higher than that of the CMPed ones for the same thickness of wafer. Conclusion: DBG process can be more helpful for lowering fracture probability during the semiconductor fabrication process than CMP process.

• Journal of Urban Science
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• v.10 no.1
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• pp.39-48
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• 2021

In this study, to evaluate the characteristics of the pollution in the major inflow tributaries and major environmental facilities in the watershed of Ara waterway, An inflow flow rate measurement and water quality analysis were conducted during dry and rainy seasons. In addition, the flow rate measurement, water quality analysis, and pollutant load at each monitoring point were compared and evaluated. Influx of BOD5, T-P and T-N into the tributaries of the ARA waterway watershed, excluding the Gulpo river watershed, during dry season were only 0.007%, 0.005% and 0.004% respectively of the incoming loads in the entire ARA waterway basin. In addition, it was confirmed that the discharge pollutant loads during rainfall event was about 440 times more for BOD5, about 545 times on T-P, and about 23 times on T-N in comparison to the pollutant loads during the dry days. When the Gulhyeon rubber dam was deflated, the discharged pollutant load during a rainfall was higher than the estimated load at the G7 monitoring point because the deposited pollutants from the upstream riverbed flowed down. Therefore, during a rainy season, it is necessary to manage the influx of high-load water pollutants from the overflow and deflation of the Gulhyun rubber dam as well as to find a strategy to reduce the pollutant loads in the Gulpo river watershed.

• Current Optics and Photonics
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• v.7 no.4
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• pp.337-344
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• 2023

Three-point bending is the main method for measuring the elastic modulus of a thin plate. Although various displacement transducers may be used to measure the bending, these are single-point measurements, and it is difficult to eliminate the error caused by eccentric load and shear force. Error-correction models for the elastic modulus of quartz glass using digital speckle interferometry are proposed for eccentric load and shear force. First, the positional misalignment between maximum deflection and load is analyzed, and the error caused by eccentric load is corrected. Then, the additional displacement caused by shear force at different positions of the quartz glass plate is explored. The effect of shear deformation is also corrected, by measuring two points. Since digital speckle interferometry has the advantage of full-field measurement, it can simultaneously obtain deflection data for multiple points to realize error correction. Experimental results are presented to demonstrate that the proposed model can effectively correct the measurement error of the elastic modulus.