• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.276-280
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• 2021

The oxygen transfer rate at the liquid surface of the reciprocally shaking vessel was studied. The required power of the reciprocally shaking vessel was not proportional to the shaking frequency, unlike the rotational shaking vessel, and the liquid level suddenly fluctuated greatly at a certain frequency as the flow pattern in the vessel was a left and right wave flow different from that of the rotational shaking that has a rotational flow. The effect of the shaking frequency on the required power in the reciprocally shaking vessel was very complex, such as less power required than the rotational shaking vessel when the shaking frequency is more than 3 s-1, but the required power for the range of the generated rotational flow in the reciprocally shaking vessel could be correlated with the equation that was reported for the rotational shaking vessel. The kLa (mass transfer capacity coefficient) in the reciprocally shaking vessel also increased in a complex pattern because the required power for shaking was not consumed in a simple pattern, unlike kLa in the rotational shaking vessel, which increases linearly with increasing frequency. The kLa of the reciprocally shaking vessel was larger than the kLa of the rotational shaking vessel, and as the kLa value increased, the difference between them increased sharply. As a result, the oxygen transfer rate in the reciprocal motion was greater than that of the rotational motion, and could be correlated with the required power per unit volume.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.27-33
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• 2019

The aviation industry has grown beyond the simple processing and assembling of aircraft parts and now designs and exports finished aircraft. In this study, the vertical CNC milling rotational speed and feed rate were parameters to investigate the life of tools according to their shape: (flat, round, and ball end mill) in the rough cutting of titanium. These tools are widely used in aircraft manufacturing and assembly. The purpose of this study is to measure the cutting temperature generated during the cutting process and calculate the rate of tool wear. This will be accomplished by measuring the tool weight before and after cutting the specimen and to compare it with the results of previous studies. Our study showed that the maximum cutting temperature increased as cutting time, tool rotational speed, and feed rate increased. The highest cutting temperatures were recorded for the ball, round, and flat end mill, respectively. Tool wear for the ball, round, and flat end mill increased as the speed and feed rate increased. The flat end mill exhibited the highest rate of wear from a minimum of 0.62% to a maximum of 2.88%.

• Journal of Biosystems Engineering
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• v.31 no.2 s.115
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• pp.108-114
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• 2006

This study was conducted to design and fabricate a controller for variable-rate application of granular fertilizer based on physical and chemical information, to analyze the performance of the controller and characteristics of a discharger. The result of the study are summarized as follows: 1. The charge ratios of discharger by accumulation heights of fertilizer in hopper were examined, and the variations in charge ratio were $72.58{\sim}93.33%$ and $63.14{\sim}94.42%$ for the fertilizers Super 21 and Sinsedae, respectively. The charge ratio also decreased as the rotational speed of discharger increased. 2. The coefficient of variation of discharge amount by rotational speed and discharge time of discharger were in the range of $2.94{\sim}11.23%$ and $2.82{\sim}10.80%$ for the fertilizer of Super 21 and Sinsedae. Except the rotational speed of 12 rpm, the coefficient of variation for discharge amount were relatively small with 4% more or less 3. In order to evaluate the rotational speed of discharger, the control signal in the range of $0{\sim}5V$ was subdivided into the 50 steps by 0.1V. The regression equation for the rotational speed of discharger was Y=55.984X-79.174(X: input voltage, V, Y: discharger speed, RPM) and the $R^2$ was 0.99. 4. In order to evaluate the performance of the controller for variable-rate application of granular fertilizer, settling time to unit step input was examined. The settling time varied from 0.8sec to 1.4 sec.

• Bulletin of the Korean Chemical Society
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• v.10 no.5
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• pp.430-433
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• 1989

Molecular reorientation of oblate symmetric top molecules in the presence of internal rotation is investigated and an analytic expression for the spin-rotational relaxation rate of a nucleus attached to the internal rotor is obtained as a function of the internal angular momentum correlation time. The overall reorientation of the symmetric top is treated by the anisotropic rotational diffusion and the internal rotation is assumed to undergo modified extended rotational diffusion. The result is compared with the previous work for the prolate symmetric top molecule and it is shown that both results reduce to the same expression in the spherical top limit.

• Korean Journal of Animal Reproduction
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• v.16 no.3
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• pp.261-267
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• 1992

The reproductive performance of SPF ICR mice under single paired mating were examined to get reproductive background data and to establish single paired rotational mating system. The results obtained were as follows : average litter size was 15.4$\pm$2.0 heads ; average weaning rate was 95.7$\pm$4.9% ; sex ratio(male/female) was 1.09$\pm$0.26 ; aveage delivery interval was 23.0$\pm$2.4 days. It was given the largest litter size at the age of 121~150 days and in 2nd~4th parities, but at the age of under 90 days and in 1st parity weaning rate and delivery interval were higher and shorter than those of the other ages and parities, respectively. In sex ratio, the number of male litters was slightly increased from that of female litters. The weaning rate of litters from dams which nuresed 12 litters was the highest among those of different litter sizes, and it was decreased dependent upon increment of litter size. There were no difference among 4 groups for reproductive performance, therefore the present study could have important sources for animal breeders who produce mice using the single paired rotational mating system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.93-98
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• 2008

We investigated the effect of process temperature on removal rate and non-uniformity based on single head kinematics in oxide CMP. Generally, it has been known that the temperature profile directly transfers to the non~uniformity of removal rate on the wafer, which has similar tendency with the sliding distance of wafer. Experimental results show that platen velocity is a dominant factor in removal rate as well as average temperature. However, the non-uniformity does not coincide between process temperature and removal rate, due to slurry accumulation and low deviation of temperature. Resultantly, the removal rate is strongly dependent on the rotational speed of platen, and its non -uniformity is controlled by the rotational speed of polishing head. It means lower WIWNU (With-in-wafer-non-uniformity) can be achieved in the region of higher head speed.

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.47-51
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• 1991

Spin-lattice relaxation of methyl protons in 2,6-dichlorotoluene and N-methyl phthalimide, each dissolved in CDCl$_3$, has been studied at 34$^{\circ}$C and the contribution from spin-rotation interaction to the relaxation process has been separated from that due to dipole-dipole interactions among methyl protons. The results show that the spin-rotational contributions to the initial rate of relaxation in 2,6-dichlorotoluene and N-methyl phthalimide amount to 18 and 31%, respectively, of the total relaxation rate at 34$^{\circ}$C. The method of separating the spin-rotational contribution from that of dipolar interactions adopted in this paper is based on the well known fact that in an A$_3$ spin system such as methyl protons in liquid phase dipolar relaxation mechanism gives non-exponential decay of the z-component of total magnetization of protons while the random field fluctuation such as spin-rotational mechanism causes exponential decay.

• Publications of The Korean Astronomical Society
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• v.20 no.1 s.24
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• pp.7-10
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• 2005

We have calculated 2448 interstellar cloud models to investigate the formation and destruction of high rotational level $H_2$ according to the combinations of five physical conditions: the input UV intensity, the $H_2$ column density, cloud temperature, total density, and the $H_2$ formation rate efficiency. The models include the populations of all the accessible states of $H_2$ with the rotational quantum number J < 16 as a function of depth through the model clouds, and assume that the abundance of $H_2$ is in a steady state governed primarily by the rate of formation on the grain surfaces and the rates of destruction by spontaneous fluorescent dissociation following absorption in the Lyman and Werner band systems. The high rotational levels J = 4 and J = 5 are both populated by direct formation into these levels of newly created molecules, and by pumping from J = 0 and J = 1, respectively The model results show that the high rotational level ratio N(4)/N(0) is proportional to the incident UV intensity, and is inversely proportional to the $H_2$ molecular fraction, as predicted in theory.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.2
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• pp.78-85
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• 2002

We introduce a rotational decision-directed joint algorithm of blind equalization coupled with carrier recovery for 32-QAM demodulation with high symbol rate. The proposed carrier recovery, which we call a rotational decision-directed carrier recovery(RDDCR), removes the residual phase difference by rotating the decision boundary for the kth received symbol by the frequency detector output of the (k-1)th received symbol. Since the RDDCR includes the function of PLL loop filter by rotating the decision boundary, it gives a simpler demodulator structure. The rotational decision-directed blind equalization(RDDBE) with the rotated decision boundary based on the Stop-and-Go Algorithm(SGA) operated during tracking the frequency offset by the RDDCR and removes intersymbol interference due to multipaths and channel noise. Test results show that symbol error rate of $10^{-3}$ is obtained before the forward error correction when SNR equals 15dB with 150KHz of carrier frequency offset and two multipaths, which is the channel condition for 32-QAM receiver.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.2
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• pp.36-41
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• 2011

Analysis of two-dimensional flow in an involute gear pump has been done by using FLUENT. Analysis extended to the turbulent flow includes the mass flow rate with functions of pressure difference between inlet and outlet, rotational velocities of involute gear, and clearances between tip of gear and housing. In general mass flow rate decreases with decreasing rotational velocity, and with increasing clearance and pressure difference. The flow rate efficiency of gear pump, which is defined with the theoretical flow rate, has been presented in terms of the above parameters.