• Journal of Digital Convergence
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• v.13 no.8
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• pp.369-374
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• 2015

In this study, by combining a unique purpose and additional aspects of ultrasonic transmission media, a development potential on a new ultrasonic transmission media was sought. The rheological characteristics and the manufacturing cost for each manufactured formulation were compared and analysed with ready-made. An ultrasonic transmission media is to have different functional characteristics according to the following formulation, it was the best in rheological value, low viscosity emulsion with the oil gel. Polymer hydro gel is can be manufactured at low cost compared to other formulations. Emulsion which shows a sharp viscosity difference according to the components of oil and water had a big difference in manufacturing cost. This study can be utilized as the fundamental data on the ultrasound transmission media equipped with expertise in various areas of ultrasound.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.345-348
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• 2008

The computer-aided performance simulation can reduce periods for development of products and cut down on the cost comparing with former trial-and-error procedures. This study has developed a simulation program for a vehicle thermal management system integrating an engine cooling system and an air conditioning system considering interactions and arrangement of air side heat exchangers such as power steering oil cooler, air-cooled transmission oil cooler, condenser, and radiator. The program may be also used for the system performance analysis according to the configuration of the engine coolant side heat exchangers such as water-cooled transmission oil cooler, EGR cooler, and heater core. Experiments utilizing an environmental wind tunnel has been conducted to assess the performance of the system according to the arrangement of air side heat exchangers. Some modification of the coolant loop layout can enhance the heat core performance up to 7% according to the results of the simulations.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.196-201
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• 2001

Electro-Rheological(ER) fluids change their apparent viscosity according to the electric field strength. Therefore, there are many practical applications using the ER fluids. ER effect on the dispersive system of polarizable fine powder/dielectric oil has been investigated. The electrical and rheological properties of starch based ER fluid were reported. Yield stress of the fluids were measured on the couette cell type rheometer as a function of electric fields, particle concetrations, and temperatures. The electric field is applied by high voltage DC power supply, The outer cup is connected to positive electrode(+) and the bob becomes ground(-). And the temperatures the viscosity(or shear stress) versus shear rates were measured. In this experiment shear rates were increased from 0 to 200s$^{-1}$ in 2 minutes. This thesis presents Bingham properties of ER fluids subjected to temperature variations. The temperature dependence of the viscosity was determined for ER fluids consisting of 35 weight % starch particles in automatic transmission oil.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.638-642
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• 2003

This paper presents a parameter design of an Electrorheological(ER) panel for noise reduction using Taguchi method. Taguchi method is a robust design method that determines control parameters in the presence of noise effect. Host structure thickness, spacer thickness, base oil viscosity and the weight ratio of ER particles are chosen for the control factors. A test setup in an SAE J1400 facility is used to analyze the sound transmission loss. The sensitivity of each factor with signal-to-noise(S/N) ratio and analysis of variance are investigated. The analysis results show that the weight ratio of ER particle and base oil viscosity of the ER fluid mostly affects the noise reduction in the presence of electric field. Based on the Taguchi method, an optimal configuration was designed and comparison is made with experimental result fer the verification.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1322-1331
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• 2004

This paper presents studies on the design of water hydraulic system and components to replace oil with tap-water as the pressure transmission medium in hydraulic systems. In order to improve the performance of water hydraulic system, the thermal and hydraulic properties of tap-water are first investigated. Based on these characteristics, the design parameters, such as the clearances of the moving parts, the cross-sectional area of pipes and relative roughness, are proposed so that the performance of water hydraulic system is the same as that of oil. In addition, the operating ranges, which show the possibility of using water hydraulic system, are examined.

• Current Applied Physics
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• v.18 no.11
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• pp.1218-1224
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• 2018

Pressure-dependent structural and morphological changes of two amphibole minerals, tremolite and actinolite, were investigated up to 7.0 GPa using synchrotron X-ray powder diffraction underthree different pressure transmission media (PTM): water (W), $CO_2$ and silicone oil (SI). The elastic response of tremolite and actinolite are found to be dependent on the PTM used. When using water (W) as PTM, tremolite and actinolite show normal volume contractions with bulk moduli of 74(1) and 78(1) GPa, respectively. When using $CO_2$ as PTM, we observe the formation of calcite from tremolite above 3.8(1) GPa, whereas actinolite did not show any carbonation reaction. Under silicone oil PTM, we observe modulated volume contraction behaviors in both samples, compared to water and $CO_2$ PTM, with bulk moduli in the order of 90(1) and 94(4) GPa for tremolite and actinolite, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.1
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• pp.83-90
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• 2014

In this paper, we address the problem of designing and implementing an oil pump control system driven by a brushless DC (BLDC) motor. The proposed oil pump plays the role of providing fuel to the engine clutch and transmission of hybrid vehicles. Main consideration is given to enhancing response feature and accuracy of the oil pump by simplifying the controller that is driven by a BLDC motor under PWM voltage control, which is a standard control method for BLDC motors. The proposed control scheme also helps to increase efficiency and reliability of the oil pump system. To validate the performance of the proposed system, we conduct experiments on BLDC motor speed control and oil pump operations.

• Journal of Korean Society for Quality Management
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• v.51 no.2
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• pp.297-313
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• 2023

Purpose: The purpose of this study is to investigate the causes of shifting errors reported in military tracked vehicles and to improve related quality to prevent recurrence. Methods: A systematic disassembly and inspection of the transmission is carried out and an experimental simulation is conducted to reproduce the shifting error phenomenon. Electrical characteristic tests are subsequently performed and microscopic observation is also carried out on the disassembled connector parts such as pins and fractured surfaces. Results: Oil contamination and swelling deformation are observed in the connector to the vehicle due to oil leakage of its counterpart connector to the transmission. This causes electrical contact failure between both connectors in the fastened state, and it is found that shifting error of the tracked vehicle could occur subsequently. To prevent the recurrence of this phenomenon, comprehensive quality improvement is conducted including product improvement of the wiring harness assembly and strengthening activities for quality control and preventive maintenance. Conclusion: This study is expected to be helpful as a prior case study for cause analysis and recurrence prevention in the event of similar cases in the future.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1731-1733
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• 1997

The first 150lkV underground transmission line of Korea was installed between Danginri and Yongsan substation in 1974. Since then, the underground transmission lines of about 720 circuit-km had been installed up to 1995. As the national economy has been enlarged and the population of city has been rapidly increased, the demand of an electric power has been very increased. Therefore the first 345kV long-length transmission line of Korea was installed between Mikyum and Sungdong substation on Jan., 1997. This paper describes the design of the 345kV oil-filled cable and its accessories, the design of the system, the methods of installation, field tests, and the future trends of the underground transmission line in Korea.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.273-279
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• 2000

Until recently performance requirements for automatic transmission fluids have continued to change to reflect the design changes of automatic transmission. The major purpose for these design changes is to improve the fuel economy and easy driving. To meet recent performance requirements fur automatic transmission the needs for special base oils Bike API Group III and IV base oils become larger. In this paper to evaluate the effects of base oils on performance of automatic transmission fluids formulated with API Group I,II,III and IV and Dexron III and Hereon Type additive package, Brookfield viscosity, oxidation test, SAE No.2 friction test and seal compatibility test were examined. From the test we knew that the use of Croup III and IV base oils in ATF has several benefits in low temperature viscosity, oxidation stability and SAE No.2 friction characteristics.