• Journal of Forest and Environmental Science
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• v.17 no.1
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• pp.62-73
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• 2001

This study was conducted to predict the tractive resistance for tree length logs being skidded by ground based logging machine. The mathematical models for predicting the tractive resistance of tree length log have been developed. The tractive resistance is expressed as a function of log weight, skidding coefficient, and ground gradient. The skidding coefficients for four species of Korean pine, Japanese larch, mongolian oak, and cork oak were determined under laboratory condition using universal testing machine and small soil bin, Three different tractive resistance models were applied to four species and compared with each other. The ratios (T/Wt) of skidding-line tensions to the skidding log weight increased linearly with increment in ground gradient. Semi-ground skidding generally required smaller tensions than ground skidding under given condition. Results of this study can be utilized as basic information for logging machine selection and power requirement of skidding winch.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06a
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• pp.203-208
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• 1996

• Journal of Biosystems Engineering
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• v.22 no.2
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• pp.117-126
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• 1997

A series of soil bin experiment was carried out on sandy loam to investigate if it is possible to predict implement draft by some analog tool. Chisel configuration resembling a cone penetrometer section was used as an analog tool. The angle of cone was 30 degree. Three types of tillage implement, or oriental janggi, moldboard plow and chisel plow were chosen for this study. Experimental tillage speed was 0.22, 0.33, 0.49 m/s ad tillage depth was 8, 12, 16cm. For the experimental tillage speed range, the increase of tillage speed did not affect the tillage draft for the three types of implement and analog tool, but as the tillage depth increased, tillage draft of the three types of implement and analog tool increased linearly. The linear relationship was found between the tillage draft of analog tool and that of three types of tillage implement for the experimental tillage depth and speed range with high value of $R^2$ Thus it was concluded from the above results that an analog tool can be used to predict the tillage draft of oriental janggi, moldboard plow and chisel plow. But more experiment for various soil types and theoretical verification are needed for more generallization.

• The korean journal of orthodontics
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• v.36 no.4
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• pp.308-320
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• 2006

Rapid canine retraction, first introduced by Liou, is a distraction osteogenesis applied to the periodontal ligament tissue. Rapid tooth movement was facilitated by establishing minimal bony resistance on the distal surface of the canine by socket preparation and by osteogenesis on the mesial side in response to the periodontal distraction. Since undesired buccal tipping or extrusion of the canine during retraction tends to occur, it is crucial to maintain the firm path of movement and the axis of the canine during retraction. In order to improve the predictability of the canine movement, lingually extended distraction screws with heavy labial guiding wires were designed. Prefabricated plastic canine models for the estimation of socket depth and miniscrew implants for anchorage reinforcement were also devised. Applying these devices to a female patient with Class II anterior protrusion, the whole treatment was effectively finished in 13 months. Loss of vitality or periodontal problems did not occur throughout treatment, and stable occlusion was maintained during 10 months of retention. This case report demonstrates that a predictable rapid canine retraction can be achieved through the use of this modified technique.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.3
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• pp.257-265
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• 2016

In this study, an optimal design for motor-driven track type traveling system applied into high clearance working machineries in orchard is proposed. Tractive performance and hill climbing ability were predicted and evaluated for the optimal motor traveling system by taking into account of soil characteristics in orchard utilizing the high clearance working machineries. Design criteria for tractive performance were based on the traction force calculated from tractive effort subtracted by motion resistance, while hill climbing ability had its design criteria that fulfill the climbing 20% slope ground at a speed of 3km/h. Based on the evaluation results of traction and climbing ability, two DC48V, 4500rpm, 1.6kW AC motors were independently applied to both left and right side of orbits; each motor is designed to transmit power on driving sprocket of track type traveling system via 50:1 reduction gear ratio. The motor-driven track type traveling system developed in the study found to have 396 kgf of tractive force, which is 12.5% higher than climbing resistance at orchard soil having 20% slope ground (352 kgf), demonstrating sufficient tractive performance and hill climbing ability.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.299-305
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• 2019

This study was initiated to solve the difficulties of aged and female workers in agriculture society due to aging and demise of young people. In the case of the conventional elevated lift, the risk of exposure to uneven road or work environment, not the difficulty of professional qualification and operation, and the risk of exposure to the uneven road or working environment, were also studied based on previous researches so that women could easily and efficiently perform productive agriculture. First, the simulation was carried out through the prediction model of traction performance using the object of agricultural forklift, and the soil of the Kimhae city in Gyeongnam (34.125kPa, internal friction angle 35.294deg, external friction angle 13.620deg, Adhesion force 5.750 kPa, average cone index 0-15 cm cl, 1001.8 kPa). In the case of the forklift for simulation, the driving force and the kinetic resistance prediction modeling of the agricultural electric forklift are modeled. Based on this model, the motor control drive adopts the 1232E model, which is a drive dedicated to AC motor, and divides the two drivers into master and slave And the model for the simulation was designed to control motor drive, hydraulic drive, and various outputs on the main PCB. The simulation model is undergoing continuous simulation, modification and supplementation. Based on this research, we will continue research for development of safer and more efficient agricultural electric forklift.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1374-1376
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• 2000

In this paper, sample coils for stator form-wound winding of traction motor were tested by the accelerative thermal degradation, which composed of heat, vibration, moisture and overvoltage applying. Reliability and expected life were evaluated on the insulation system for 200 class traction motor. After aging of 10 cycles, insulation resistance and PI properties were investigated as diagnosis tests in the range of $20{\sim}160^{\circ}C$. Analysis of polarization properties was performed on the base of do current-time change.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.182-185
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• 2011

본 논문에서는 국내 고속철도 차량 즉, 경부고속철도를 운행하는 KTX, KTX산천 그리고 현재 개발중인 HEMU400x을 대상으로 운행속도 및 운행패턴에 따른 열차 소비전력을 분석하였다. 이를 위해, 선로조건을 고려한 차량의 운전속도 조건과 운행시간,소비전력 등을 예측하기 위한 TPS(Train Performance Simulation)프로그램을 이용하였다. 열차운행 시뮬레이션을 수행하기 위해선 차량, 선로, 속도의 기본 데이터를 필요로 한다. 차량에 대한 데이터는 차량의 최고속도, 제동성능, 견인력 등의 기본 성능과 열차편성에 따른 중량, 길이, 동력차량형식, 열차주행저항등에 대한 제원을 요한다. 선로데이터는 운행시간 예측을 대상으로 하는 선로에 대한 거리별 구배 및 선형, 정거장 위치 및 정차시간에 대한 데이터이다. 속도조건은 구배 및 곡선에 대한 선로제한속도로, 선로데이터와 연계하여 각 선로위치별 차량의 제한속도로 이용된다. 본 논문에서는 경부고속철도 구간에서 운행하는 고속차량 3가지를 대상으로 증속에 따른 전력소모량을 비교하였다.