• Journal of the Korean institute of surface engineering
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• v.28 no.2
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• pp.92-100
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• 1995

To increase the capacity of positive electrode materials for matching the high capacity negative electrode materials in alkaline rechargeable batteries, high-density nickel hydroxide powders were made through a continuous process from nickel sulfate reacted with ammonia and sodium hydroxidc. The effect of operating conditions on structure, shape, size distribution, apparent density and tap density of powders were investigated. Crystal structure of nickel hydroxide powder was hcp according to Bravais Lattice. The increase of mean residence time promoted the growth of (101) plane. The shape of powder was nearly spherical. Their size was in the range of $2~50\mu\textrm{m}$. The size distribution of the powders prepared was narrower than that of commercially obtained nickel hydroxide. Apparent density and tap density were 1.6~1.7g/cc and 2.0~2.1g/cc, respectively.

• Journal of Mechanical Science and Technology
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• v.14 no.12
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• pp.1421-1428
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• 2000

The characteristics of heat transfer and pressure drop for fully developed turbulent flow in a tube with circumferential fins and circular were experimentally studied. The various spacing and sizes of circumferential fins and circular disks were selected as design parameters, while the effects of these parameters on heat transfer enhancement and pressure drop were investigated. In order to quantify the effect of heat transfer enhancement and the increase of pressure drop due to the fins and disks in a tube, the Nusselt numbers and the friction factors for various configurations and operating conditions were compared to those for a corresponding smooth tube. The results showed that the heat transfer rate was significantly enhanced by increasing the height of circumferential fins and decreasing the pitch of circumferential fins. On the other hand, the influence of the disk size and the fin-disk spacing were not significant. Based on the experimental results, a correlation for estimating the Nusselt number was suggested.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.8-15
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• 2007

In an effort to develop control strategies for the wet-end of paper machines, dynamic models for retention and formation processes have been developed. The retention process, including headbox total and filler consistencies, white water total and filler consistencies, the basis weight and the ash content of paper, can be modeled from first-principles (mass balances). To include the effect of wet-end chemistry variables, first-pass retention was included as a parameter dependent on operating conditions. In addition, dynamics of formation was simulated by developing an empirical model of formation and coupling with the dynamic models for the retention process. A series of experiments were performed using a pilot paper machine. The experimental results and the model predictions showed relatively good agreement.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.266-271
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• 2021

A commercial PbO₂ electrode was adopted as the anode for the electrochemical degradation of the real textile effluent with the initial COD of 56.0 mg L^-1 and the stainless steel plate as the cathode. The effect of the initial pH, the electrolyte flow rate and the cell voltage on the COD, the current efficiency and the energy consumption were investigated without the addition of NaCl or Na₂SO₄. The experimental results illustrated that the PbO₂ electrode can reduce the COD of the textile effluent from 56.0 mg L^-1 to 26.0 mg L^-1 with the current efficiency of 86.1% and the energy consumption of 17.5 kWh kg^-1 (per kilogram of degraded COD) under the optimal operating conditions. Therefore PbO₂ electrode as the anode was promising to further electrochemically degrade the real textile effluent.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1661-1667
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• 2004

An experimental study is performed on atomization characteristics and stable operating conditions for the injection of high viscous waste vegetable oil using an effervescent atomizer with 2 aerator tubes. Consideration is given to the effects of ALR and liquid viscosity on the velocity and mean diameter of the injected droplet. It is found that (i) as ALR increases, the axial velocity of the droplet is increased, while half-velocity width and SMD are decreased regardless of the change in liquid viscosities, (ii) the rate of fine drop distribution occupied in the total spray field is increased with an increase in ALR, and (iii) the effect of viscosity on the atomization characteristics is minor. Consequently, it is expected that the effervescent atomizer will exhibit an excellent atomization performance at the high ALR condition, regardless of liquid viscosities.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.11a
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• pp.209-216
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• 2003

There are two kinds of controllers in a continuous process system. One is for tension control of a moving web and the other for lateral motion control. The inter-connection between tension and lateral behaivior of web has not yet been considered in the analysis of web dynamics and designing of control stragagies. But the effect of tension variation on the lateral motion of a moving web is observed in the most manufacturing systems. In this paper, experimental studies was carried out to find out the inter-correlation between tension and lateral motion of a web using a 3-span web transport system which consists of two displacement type guiders. As a result, it was found that there are typical operating conditions that tension and lateral motion are correlated each other.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.1
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• pp.59-70
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• 1991

Rupture of lubricant film, thermal characteristics, and variation of viscosity are very important factors to evaluate the performance of journal bearing. Variation of external conditions, load or rotational speed, largely influence these facters. For example, if rotational speed increases lubricant bulk temperature increases and viscosity drops. In this paper the effect of rotational speed variation on the characteristics of lubricant film in a journal bearing is investigated by experiment and theoretical analysis. It has been measured number of lubricant film rupture and lubricant bulk temperature form journal bearing which have been established at the various operating speed of shaft. The range of speed variation is from 900rpm to 2100rpm. Theoretical analysis has been carried out for rupture of lubricant film and thermal characteristics, and these results are compared with experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.244-249
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• 1997

Internal and external heat sources will cause to deform to machine elements in the contact joint of structure,which results in the change of contact pressure distribution different from initial assembly. Heat induced variations of contact pressure will change the static and dynamic properties such as contact stiffness,damping as well as contact heat conduction in the structure. In order to design and control the intelligent machine tool operating in variant conditions more sophisticatedly, the good prediction for the changes of prescribed propeties are strongly required especially in the contact elements adjacent to the rotational or linear bearing This paper presents some computational and experimental results in regard to static and dynamic characteristics of the press-fitted bush and shaft assembly which is a model of the bearing innerrace and shaft assembly. In the condition of heat generation on the outer surface of the bush,the effects of changes in the negative clearance and the heat flux on pressure distribution and dynamic properties are investigated. Results of this study show that the edge effect of the bush and the initial clearance have effects on the transient dynamic characteristics significantiy.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.81-88
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• 1999

In order to understand the relationship between the phase angle of piston ring and oil consumption was measured by analyzing $CO_2$concentration in exhaust gas. The use of hydrogen fuel not gasoline makes this possible because all of the carbon component in exhaust gas can be assumed to be produced from oil. As a result of experiment, it is known that the oil consumption varies periodically and a specific location of ring end gap was found at each peak of oil consumption. Therefore, it was found that the oil consumption was not constant even at the same operating conditions and this is because the relative locations of top and 2'nd ring end gap change arbitrarily.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.14-26
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• 1998

This paper deals with approximate analytical solutions for the two-region one-dimensional model describing the charging process of stratified thermal storage tanks at variable inlet temperature with momentum-induced mixing. An arbitrarily increasing inlet temperature is decomposed into inherent step changes and intervals of continuous change. Each continuous interval is approximated as a finite number of piecewise linear functions, which admits an analytical solution for perfectly mixed region. Using the Laplace transform, the temperature profiles in plug flow region with both the semi-infinite and adiabatic ends are successfully derived in terms of well-defined functions. The effect of end condition on the solution proves to be negligible under the practical operating conditions. For a Quadratic variation of inlet temperature, the approximate solution employing a moderate number of pieces agrees excellently with the exact solution.