• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.111-120
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• 2021

A tractor is an agricultural machine that performs farm work, such as cultivation, soil preparation, loading, bailing, and transporting, through attached working implements. Farm work must be carried out on time per the growing season of crops. As a result, the reliability of a tractor's transmission is vital. Ideally, the transmission's design should reflect the actual load during agricultural work; however, configuring such a measurement system is time- and cost-intensive. The design and analysis of a transmission are, therefore, mainly performed by empirical methods. In this study, a tractor with a measurement system was used to measure the actual working load in the field. Its hydro-mechanical transmission was then analyzed using the measured load. It was found that the velocity factor, load distribution factor, lubrication factor, roughness factor, relative notch sensitivity factor, and life factor affect the gear strength of the transmission. Also, loading conditions have a significant influence on the reliability of the transmission. It is believed that transmission reliability can be enhanced by analyzing the actual load on the transmission, as performed in this study.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.687-696
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• 2005

Safety diagnosis was conducted to evaluate the long-term stability evaluation of power transmission tower of which deformation of the upper structural elements occurred. To assess the cause of the structural deformation, field investigation including BIPS, down-hole test, concrete pile coring and finite element analysis were carried out. From these studies, the major cause of deformation was found due to the heavily fractured layer and weathered soil topography at the pile tip area. The cement-milk grouting method was proposed to reinforce these weak zone around the pile tip area. Also, the increase of cross-section and stiffness for steel members of upper tower structures was suggested. Instrumental monitoring was proposed as well to verify reinforcing effect.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1843-1846
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• 1997

This paper describes the fault reducing effects of the 154 kV transmission tower by auxiliary grounding from the top of the tower to ground. The grounding surge impedance of the auxiliary grounding system is calculated by CDEGS(:Current Distribution Electromagnetic Interference Grounding and Soil Structure Analysis), and the critical lightning back flashover current and arcing horn dynamic characteristics are simulated by EMTP/TACS(:Electromagnetic Transient Program/Transient Analysis of Control Systems). The calculated results of total LFOR(Lightning Flashover Rate) shows that the LFOR can be reduced from 5.2(count/100km. year) to 3.4 by auxiliary grounding on the 154 kV transmission tower with one ground wire shielding system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1166-1170
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• 2004

The leakage currents of transmission insulator were investigated as a function of environmental conditions, such as temperature, humidity, and rainfall. The insulators were artificially contaminated with insoluble yellow soil and kaolin which helped salt to stick on the surface of insulator. The insulators contaminated with the grade of B, C, and D were installed in the KoChang Testing Center. The leakage currents were measured and compared with non-contaminated insulators. The results indicated that the most important factor affecting leakage current was humidity. After heavy rain, the artificially contaminated salt was dissolved, resulting in similar characteristics between with and without contamination

• The Plant Pathology Journal
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• v.17 no.6
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• pp.387.1-387
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• 2001

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.455-457
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• 2001

Grounding resistance is the basic performance indicator of grounding electrodes and the resistance has been calculated by simple equations, which is based on the assumption of uniform soil model. In this paper, tower grounding resistance is calculated assuming horizontally 2 layered soil model using finite element analysis method. A simple grouding design graph has been resulted from the calculation results.

• The Plant Pathology Journal
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• v.17 no.5
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• pp.243-248
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• 2001

Two Tobamoviruses, Cucumber green mottle mosaic virus (CGMMV) and Zucchini green mottle mosaic virus (ZGMMV), occurred in Korea in 463 ha in 1998, 33.9 ha in 1999, and 44.2 ha in 2000. CGMMV was detected in watermelon, cucumber, oriental melon, and melon, whereas ZGMMV was mainly detected in zucchini squash. Thirty-six CGMMV isolates wee classified into three types by analysis of single strand cDNA conformational polymorphism (SSCP) of the coat protein gene. In a comparison of serological relationships among CGMMV, ZGMMV, and Kyuri green mottle mosaic virus (KGMMV), the three tobamoviruses specifically reacted with each homologous antibody in the double-antibody sandwich enzyme-linked immunosorbent assay and rapid imunofilter paper assay (RIPA), although ZGMMV and KGMMV were slightly biologcially similar. In a survey of the three tobamoviruses in cucurbitgrowing field in Korea by RIPA, CGMMV and ZGMMV were detected but KGMMV was not found in commercially growing cucurbit crops so far. Seed contamination ratio of CGMMV in bottle gourd seeds tested was 84%, while seed trasmission ratio from the virus-contaminated seeds was 2.0%. Soil transmission ratio was 0-3.5% in fields naturally infested with CGMMV or ZGMMV. Control measures of the virus diseases are roguing and sanitation. These suggest that it is important to rogue the first infected crops, which include the seed and soil, especially early in the season. This may be practicable to control the diseases because CGMMV and ZGMMV have a narrow host range restricted to cucurbitaceous crops.

• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.287-293
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• 2018

Amorphous silica ($SiO_2$) silt grains were found in some soils of Korean Peninsula. Scanning electron microscopy of polished section of soils revealed ellipsoidal amorphous $SiO_2$ grains with numerous submicron pores concentrated in the interior. Their amorphous structure was confirmed by lattice imaging and electron diffraction under transmission electron microscope. Amorphous $SiO_2$ grains were not found in the eolian sediment of the Chinese loess plateau. Although the origin of the amorphous $SiO_2$ grain is uncertain, they are likely either phytolith or weathering product of volcanic ash. The amorphous $SiO_2$ silt grains are not useful as a tracer of long-range transport mineral dust in soils.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.639-645
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• 2011

Wheel-loader is a construction vehicle for uploading soil or sand into truck and transportation of materials, which requires large driving power and high rotational speed. To improve the working efficiency, the operator has to shift gears and control levers for bucket & boom simultaneously. Therefore, the automatic transmission has been introduced to enhance operator's convenience and enable effective operation. To develop the automatic transmission for the wheel-loader, technologies such as gears and a clutch-pack design and shift algorithm are required for improvement of shift quality. In this paper, the shift algorithm for the wheel-loader was developed and its shift pattern was analyzed. As the shift control is affected by the pressure profile for the clutch control, the shift quality depending on the pressure profile has been evaluated using experiment and simulation model analysis.

• Journal of the Korean Society for Railway
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• v.14 no.1
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• pp.39-48
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• 2011

The paper describes four practical cases of railway structure concerning a three-dimensional numerical approach to analyse dynamic soil-structure interaction(SSI)of railway tracks on layered soil under transient load in the time domain. The SSI-Model has been implemented in TDAPIII accounting for nonlinear properties of the track and soil. The approach can be also be used to calculate vibration propagation in the soil and its effect on nearby buildings and structure. The Method is applied to analyse the dynamic response of railway tracks due to a moving wheel set. Finally some sample are given in order to reduce the vibration at the point of emission, at the transmission path and the structure itself.