• Journal of the Korean Wood Science and Technology
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• 제34권2호
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• pp.58-67
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• 2006

The relationship between acoustic property and coating hardness of musical instruments was investigated using a sound level meter and a pendulum hardness tester. Urethane topcoat, oil stain, natural oil varnish, and UV-curable epoxy acrylate coatings were applied on four different substrates: Paulownia coreana, Pinus koraiensis, Castanea crenata var. dulcis and Pinus densiflora. The influence of the coating type on the acoustic properties was stronger than that of the substrate. In the case of an oil stain formed with tacky coating layer, the sound pressure level (SPL) and surface hardness decreased with increasing of coating thickness. In the other coatings, SPL decreased and hardness increased as the coating layer thickened. However, SPL began to increase again at coating thickness above $100{\mu}m$.

• Culinary science and hospitality research
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• 제10권4호
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• pp.190-200
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• 2004

This study was carried out to investigate the effects of intake of whangseoke-jeot with chitosan on the hematological changes. Twelve male students were divided into two groups and have been dieted for 3 days with whangseoke-jeot supplemented with/without 10% of chitosan(50,000 dalton) into seasoning. In order to decrease fishy smell and increase palatable taste effectively, minced ginger, garlic and onion as well as oil and roasted powder of perilla were included into the seasonings. Blood pressure was monitored everyday and serum was prepared following blood collection before and after 3 day diet. Chitosan was shown to decrease systolic pressure and total serum protein. On the other hand, albumin was decreased in the control group. It is noteworthy that seasoned whangseoke-jeot including perilla oil and powder seemed to decrease creatinine and total cholesterol and increase HDL. In conclusion, chitosan and perilla oil and powder might be proposed as good additives into whangseoke-jeot to relieve its highly salty effects on diet.

• Transactions of The Korea Fluid Power Systems Society
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• 제1권2호
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• pp.8-14
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• 2004

Abstract: In the oil hydraulic piston pumps the clearance between the valve plate and cylinder block plays an important role for volumetric and overall efficiency. Thus, adequate lubricational fluid film is needed for the interface. In this study, fluid film thickness is measured by a gap sensor and a slip ring under operational conditions to observe the behavior of the lubrication mechanism in detail. To investigate the effect according to the valve plate types in view of the fluid film, three different types were designed. Leakage flow rate and shaft torque were also measured to clarify the effect according to the valve plate types. A broad range of experiments were conducted to provide reasonable data on the effect of fluid film. In this experiments two main parameters were found, of which the one is the discharge pressure and the other is valve plate geometry. As a result, we found that the spherical valve plate could get more stable fluid film thickness, maintain good efficiency for high pressure range than the other types.

• Journal of ILASS-Korea
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• 제3권4호
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• pp.8-15
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• 1998

The spray characteristics of emulsified fuel of W/O type has been experimentally investigated. The mixture of light oil and water by using ultrasonic energy adding system is used as the emulsified fuel. The SMD of sprayed droplet of emulsified fuel is measured by using the particle size analyzer. Major parameters of the present experimental study are the volume fraction of water in emulsified fuel, $0\sim30%$ by 5%, injection pressure, $10kg_f/cm^2\sim18kg_f/cm^2$ by $2kg_f/cm^2$, and the measurement distance, $10\sim100mm$, between injection nozzle tip and analyzer beam. Compared with light oil, the SMD of emulsified fuel is larger gradually by increasing the volume fraction of water in emulsified fuel, heightening injection pressure and increasing the spray distance. Also, In considering the fact that the pattern of drop size distribution of emulsified fuel is alike that of light oil, the real time spray in coincidence with making emulsified fuel by adding ultrasonic energy can stabilize spray pattern without modificating the injection system used by now.

• Membrane and Water Treatment
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• 제5권3호
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• pp.207-219
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• 2014

Fouling is one of the critical factors associated with the application of membrane technology in treating palm oil mill effluent (POME), due to the presence of high concentration of solid organic matter, oil, and grease. In order to overcome this, chemical cleaning is needed to enhance the effectiveness of membranes for filtration. The potential use of sodium hydroxide (NaOH), sodium chloride (NaCl), hydrochloric acid (HCl), ethylenediaminetetraacetic acid (EDTA), and ultrapure water (UPW) as cleaning agents have been investigated in this study. It was found that sodium hydroxide is the most powerful cleaning agent, the optimum conditions that apply are as follows: 3% for the concentration of NaOH, $45^{\circ}C$ for temperature solution, 5 bar operating pressure, and solution pH 11.64. Overall, flux recovery reached 99.5%. SEM images demonstrated that the membrane surface after cleaning demonstrated similar performance to fresh membranes. This is indicative of the fact that NaOH solution is capable of removing almost all of the foulants from PES membranes.

• Coupled systems mechanics
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• 제8권2호
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• pp.129-146
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• 2019

The main goal of this work is to develop a numerical simulator to study an isothermal single-phase two-component flow in a naturally fractured oil reservoir, taking into account advection and diffusion effects. We use the Peng-Robinson equation of state with a volume translation to evaluate the properties of the components, and the discretization of the governing partial differential equations is carried out using the Finite Difference Method, along with implicit and first-order upwind schemes. This process leads to a coupled non-linear algebraic system for the unknowns pressure and molar fractions. After a linearization and the use of an operator splitting, the Conjugate Gradient and Bi-conjugated Gradient Stabilized methods are then used to solve two algebraic subsystems, one for the pressure and another for the molar fraction. We studied the effects of fractures in both the flow field and mass transport, as well as in computing time, and the results show that the fractures affect, as expected, the flow creating a thin preferential path for the mass transport.

• Journal of the Korean Society for Precision Engineering
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• 제11권1호
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• pp.123-128
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• 1994

A high speed spindle system for machine tools can be used to reduce the machining time, to improve the machining accuracy, to perform the machining of light metals and hard materials, and to unite the cutting and grinding processes. In this study, a high speed spindle system is developed by applying the oil-air lubrication method, angular contact ball bearings, injection nozzles with dual orifices, cooling jacket and so on. And an air cooling experiment for evaluating the performance of the spindle system is carried out. Especially, in ofder to establish the air cooling conditions related to the development of a high speed spindle system, the effects of cooling air pressure, oil supply rate, air supply rate and rotational spindle speed are studied and discussed on the bearing temperature rise and frictional torque. Also the effects of cooling air pressure, rotational spindle speed and spindle system structure is investigated on the bearing temperature distribution. The experiment on the test model reveals the usefulness of the air cooling method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제23권2호
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• pp.72-79
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• 1987

In this paper, an investigation of the property of blended fuel oil, combustion characteristics and engine performance was made, in case blended fuel oil(light oil+heavy oil) was used in a home-made precombustion diesel engine for small-sized fishing boat. The results may be summarized as follows: 1. The specific gravity was linearly increased in accordance with the increase in heavy oil ratio in blended fuel oil, and the relationship between viscosity and temperature was coincided with the formula of Walther-ASTM, and the CCAI, the ignition quality index, was increased nearly as a straight line of the gradient 1.0. 2. The ignition delay was slightly increased below 810 of CCAI(blending ratio to be 60% of heavy oil), but remarkably increased above 810 of CCAI. Therefore, it was considered that the practicable value of CCAI, ignition quality of blended fuel oil, was more than 810. 3. The maximum combustion pressure was increased until blending ratio of heavy oil was raised up to 40%. On the contrary, it came to be decreased at that ratio, with smoke emissions remarkably increasing above 60%. Therefore, it was found in this experiment that the best practicable limit of heavy oil blending ratio was around 50% for saving fuel costs with least smoke emissions.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제23권2호
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• pp.26-26
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• 1987

In this paper, an investigation of the property of blended fuel oil, combustion characteristics and engine performance was made, in case blended fuel oil(light oil+heavy oil) was used in a home-made precombustion diesel engine for small-sized fishing boat. The results may be summarized as follows: 1. The specific gravity was linearly increased in accordance with the increase in heavy oil ratio in blended fuel oil, and the relationship between viscosity and temperature was coincided with the formula of Walther-ASTM, and the CCAI, the ignition quality index, was increased nearly as a straight line of the gradient 1.0. 2. The ignition delay was slightly increased below 810 of CCAI(blending ratio to be 60% of heavy oil), but remarkably increased above 810 of CCAI. Therefore, it was considered that the practicable value of CCAI, ignition quality of blended fuel oil, was more than 810. 3. The maximum combustion pressure was increased until blending ratio of heavy oil was raised up to 40%. On the contrary, it came to be decreased at that ratio, with smoke emissions remarkably increasing above 60%. Therefore, it was found in this experiment that the best practicable limit of heavy oil blending ratio was around 50% for saving fuel costs with least smoke emissions.

• Tribology and Lubricants
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• 제22권3호
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• pp.131-136
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• 2006

Cylinder bore wear may not be a problem in most current automotive engines. However, a small change in cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each pare0s wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of cylinder bore diameter are obtained from three engines before and after engine durability test. The calculated wear data of cylinder bore diameter are turn out to be twice of the lower bound of averaged test values at TDC and the lower bound at BDC.