• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1102-1109
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• 1993

This paper describes the research and development of Walking Tractors and Tillage Implements for Phase I (1991-1992) . The project consists of : (1) the study and need for the development of the walking tractors for Thailand and other Southeast Asian countries ; (2) the comparison in the use of the walking tractors and their transmission systems that are made in Thailand and aborad : and (3) the design of future walking tractors for Asian farmers in developing countries. The design of the walking tractors is concentrated to provide the ease to farmers, especially the elderly and female which will play an important role in the future agriculture of Thailand due to the lack of manpower. In addition , the design of the walking tractors is also aiming for small-scale farmers, the majority that have limited land capital. The walking tractors consist of several components but the most important one is the " Transmission System" . Thus, the research is concentrated in the devel pment an design of the a new transmission system. The new machine , currently developed, is named after the Chulalongkron University as " Chular Walking Tractor " , model SPJS -60. The tractor uses a 6-7 horsepower diesel engine with three forward gears and one reverse gear. The tractor also uses the latest gearing technology so called planetary gearing system with steering clutches system that never been used in any earlier model. The advantages of the planetary gearing system are : (1) the final drive gear can be small, and can be designed to provide higher strength with less wearing resistance, (2) the system eliminates a shaft which is used in other systems, thus reduces the weight and the manufacturing cost . Furthermore, the Chular Walking Tractor has an additional power take off shaft that can be used or linked with other standard agricultural implements.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.445-453
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• 2020

The use of tugboats for the safe berthing/unberthing of ships is the most crucial factor in the safe and efficient operation of the harbor. However, the adequate number and size of tugboats that should be held based on the characteristics of the port have not been investigated in detail, which causes disputes between involved parties. Therefore, the suitable number of tugboats and the ratio of the tugboat horsepower were determined in this study using simulation techniques, with focus on Ulsan Port. First, the ship and tugboat-operating models were designed for simulation application. Next, the input variables defined in the model design were standardized in an inputtable form using ARENA software. In addition, the arrival and division process of the ship was designed and simulated as an ARENA model. Finally, the simulation results for six scenarios showed that an effective tugboat operation could be achieved when 42 tugboats were held at Ulsan Port.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.316-322
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• 2017

The primary objective of the current study is to develop outstanding hull form on resistance performance by using numerical analysis code. Model tests were conducted to assess the resistance performance of the developed hull form. The investigation of an existing vessel was performed for validating the actual ship design based on the drawing. The operating displacement and speed were mainly confirmed through investigation of the existing vessel. The resistance performance of the existing vessel was analyzed using numerical code. The developed vessel was derived through studies on wave improvement of the bow shoulder, the balance of displacement distribution, the modification of the frame shape, and the size and shape change of the center skeg. Based on the results of a computational fluid dynamics analysis, the resistance performance of the developed vessel showed an improvement of 15% over the existing vessel at a speed of 11 knots. Resistance tests were conducted to evaluate the performance of the existing vessel and the developed vessel in the towing tank. Finally, the effective horsepower of the developed vessel showed an improvement of 17% over the existing vessel.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.574-579
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• 2016

Grid systems used in previous studies were determined to be valid only if the length between the perpendiculars in a model ship was in the range of 6-8 m, and the maximum dynamic trim angle was smaller than $1^{\circ}$. The application of the grid system to a small fishing boat can create numerical instability because the dynamic trim of small boats is generally larger than $3^{\circ}$, and their Froude numbers are in the range of 0.3-0.8. In the present study, resistances of a small fishing boat were stably obtained by reducing the length between the center of buoyancy and the inlet boundary of the numerical domain, and by refining grid cells vertically in a region that would be swept by a free surface. The effective power of the small fishing boat was predicted based on the ITTC-1978 two-dimensional analysis. By using the results of previous towing tank tests, the coefficient of quasi-propulsive efficiency and the brake horsepower at a design draft were calculated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.347-355
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• 2016

In this study, a new designed propeller was applied on 24 ton class squid jigging vessel to reduce of fuel consumption. The selected squid jigging boat was under construction at the shipyard to determine the resistance of the hull through the model experiment. The propeller design was carried out by using the experimental data and ITTC procedures. Sea trials were performed by measuring the speed and the horsepower required by the condition of five power levels of engine load, namely 70%, 80%, 90%, MCR and maximum engine power. The speed and delivered horse power were compared between the conventional propeller and the new design propeller. Delivered horse power by installing the new propeller takes 90% engine load at start-up conducted by decreased 9.06%. The measuring speed is increased up to the 0.6 knots in the low-speed range to high range. This study showed that only the design and installation of a new propeller can improve the propulsion efficiency of the boats; furthermore, reduce fuel costs can be achieved at the same time by improving the increased cruising speed.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.1
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• pp.20-30
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• 1982

Recent diesel engine has achieved high speed running comparable to that of gasoline engine as a speed improvement effort. Consequently, torsional vibration of high-speed diesel engine induced vibration nosise, reduced horsepower and the like. Viscous damper which is thought to be effective in curtailing the torsional vibration was studied over a wide range of speed. In this investigation, a water cooling, 4-cycle high-speed diesel engine(Msx. 3500 rpm)was used for the study. Theoretical analysis was made by assuming the engine to be an ideal equivalent system(length, moment of inertia) i. e. the multi-degree of freedom equivalent torsional vibration system with damper was analyzed. In the analysis, the inertia moment of suitable damper for this experiment was calculated by varying the relative damping coefficient of damper of engine for each damper. Furthermore, in the torsional vibration experiment, the torsional vibration amplitude of the crankshaft system was measured when the engine was equipped with dampers of different moments of inertia and also when the engine was equipped without dampers. The experimental results were compared with the analytical values and were found to be satisfied. The results of this investigation are summarized below; (1) It was found that for the engine equipped with dampers, the torsional vibration amplitude was reduced to about one third of those without dampers. (2) The optimum value of inertia moment of viscous damper for the engine was found to be about Id=1.05(kg.cm.s$^{2}$) (3) The optimum damping coefficient and the ratio of moment of inertia for the engine were found to be about Ca= 850(kg.cm.s), Rd=0.509, respectively (b1 dapmper).

• Journal of Digital Convergence
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• v.17 no.12
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• pp.203-210
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• 2019

Most cars today use electronic control to control the state of the engine to achieve optimum performance. This study developed a device for maintaining fault diagnosis and optimal vehicle status by displaying the engine information of a car on the screen in real time using can communication. This system displays information generated from the engine to the driver in real time such as engine intake and exhaust temperature, current battery voltage, tire pressure, RPM, DPF collection amount, torque, and horsepower through the OBD2 socket. You can check immediately. It can help you to drive safely by measuring tire pressure and displaying it on the screen, and it provides a mode to set the shift timing to suit your taste. In particular, in the case of diesel engine cars, the problems caused by smoke can adversely affect the performance and environmental pollution. Therefore, the system was developed to display the DPF collection amount on the system screen to prevent environmental pollution and to manage the vehicle efficiently.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.757-764
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• 2018

This paper describes the design and implementation of a 1hp class two-phase type BLDC fan motor used in an air conditioning system. The BLDC motor, which is implemented in this study, is not a commutator motor type with excellent lifetime and durability and is driven by two phase power source. The most important target specification of a motor used in an air conditioning system is that it has a high efficiency at the rated operating point. For this purpose, we designed the stator shape of the BLDC motor, the design of the rotor magnet, and the control circuit for driving. The BLDC motor has a structure where the motor part, the control part, and the power part are integrated. The finite element analysis was used to calculate the characteristics of the BLDC motors, and the conformity of the design results was confirmed by fabricating and testing the prototype model.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.6
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• pp.474-481
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• 2018

This paper is to compare by numerical analysis the flow characteristics and propulsion performance of stern with the shape change of K-duct, a pre-swirl duct developed by Korea Research Institute of Ships & Ocean Engineering (KRISO). First, the characteristics of the propeller and the resistance and self-propulsion before and after the attachment of the K-duct to the ship were verified and the validity of the calculation method was confirmed by comparing this result with the model test results. After that, resistance and self-propulsion calculations were performed by the same numerical method when the K-duct was changed into five different shapes. The efficiency of the other five cases was compared using the delivery horsepower in the model scale and the flow characteristics of the stern were analyzed as the velocity and pressure distributions in the area between the duct end and the propeller plane. For the computation, STAR-CCM +, a general-purpose flow analysis program, was used and the Reynolds Averaged Navier-Stokes (RANS) equations were applied. Rigid Body Motion (RBM) method was used for the propeller rotating motion and SST $k-{\omega}$ turbulence model was applied for the turbulence model. As a result, the tangential velocity of the propeller inflow changed according to the position angle change of the stator, and the pressure of the propeller hub and the cap changes. This regulated the propeller hub vortex. It was confirmed that the vortex of the portion where the fixed blade and the duct meet was reduced by blunt change.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.187-192
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• 2018

This thesis is about the study of inverter terminal boxes in a explosion proof type exhaust fan that can control wind volume and operating time. In Korea, there is no ventilator to adjust the amount of wind and operating time when working in poor conditions. The purpose of the project is to create a explosion terminal box that can control the operating time and wind speed of a suitable explosion ventilator in hazardous environments. The two explosion-proof switches allow the operation time to be driven 1 hour, 3 hours and continuous time, and the speed of the induction motor rotation was set in 3 stages at 2000 rpm, 2600 rpm and 3000 rpm to control the volume. The tested motor used a half-horsepower barrier three-phase induction motor and a full-bridge inverter to set the desired flow rate and operating time.