• YAKHAK HOEJI
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• v.18 no.2
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• pp.125-132
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• 1974

The by-products which were occured in the synthesis of 5-ethyl-5-phenyl barbituric acid were isolated by column chromatography combined with gas-liquid chromatography and were identified by elemental analysis, ir, nmr and mass spectroscopy ; major by-products were ethyl${\alpha}$-phenylbutyrate and ${\alpha}$-phenylbutyramide. The alkoxide which was known to be a condensation agent not only accelerated the condensation but also did the decarboxylation. And the entity concenrned with the condensation with diethyl ethylphenylmalonate was not urea but N-monosodium urea.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.2
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• pp.163-167
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• 2003

Ozone is strong and useful oxidizing gas for the fabrication of oxidation thin films. In order to obtain high quality thin film, the ozone concentration must be increased. An ozone condensation system is evaluated in the viewpoint of an ozone supplier for oxidation thin film growth. Ozone is condensed by the adsorption method and ozone concentration reaches 8.5 mol% by 2.5 h after the beginning of the ozone condensation is negligible if the condensed ozone is transferred between the ozone condensation system and the film growth chamber within a few minutes. CuO peak which is the result of the obtained Cu-films using condensed ozone appears by XRD patterns.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1999.04a
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• pp.14-14
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• 1999

• Journal of the Korean Institute of Gas
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• v.12 no.1
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• pp.48-53
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• 2008

The condensation heat transfer coefficients of R-22 and R-410A in a small diameter tube were investigated. The main components of the refrigerant loop consist of a receiver, a variable-speed pump, a mass flowmeter, an evaporator (preheater), and a condenser (test section). The test section consists of smooth, horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The refrigerant mass fluxes varied from 450 to $1050\;kg/(m^2s)$ and the average inlet and outlet qualities were 0.05 and 0.95. The main results were summarized as follows : the condensation heat transfer coefficient also increases with increasing mass flux and quality. The condensation heat transfer coefficient of R-410A was slightly higher than that of R-22. Most of correlations proposed in the large diameter tube showed significant deviations with experimental data except for the ranges of low quality and low mass flux.

• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.486-497
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• 1999

The local heat transfer coefficient is experimentally investigated for the reflux condensation in a countercurrent flow between the steam-air mixture and the condensate, A single vertical tube has a geometry which is a length of 2.4m, inner diameter of 16.56mm and outer diameter of 19.05mm and is made of stainless steel. Air is used as a noncondensible gas. The secondary side has a shape of annulus around vertical tube and the lost heat by primary condensation is transferred to the coolant water. The local temperatures are measured at 11 locations in the vertical direction and each location has 3 measurement points in the radial direction, which are installed at the tube center, at the outer wall and at the coolant side. In three different pressures, the 27 sets of data are obtained in the range of inlet steam flow rate 1.348∼3.282kg/hr, of inlet air mass fraction 11.8∼55.0%. The investigation of the flooding is preceded to find the upper limit of the reflux condensation. Onset of flooding is lower than that of Wallis' correlation. The local heat transfer coefficient increases as the increase of inlet steam flow rate and decreases as the increase of inlet air mass fraction. As an increase of the system pressure, the active condensing region is contracted and the heat transfer capability in this region is magnified. The empirical correlation is developed by 165 data of the local heat transfer. As a result, the Jacob number and film Reynolds number are dominant parameters to govern the local heat transfer coefficient. The rms error is 17.7% between the results by the experiment and by the correlation.

• Journal of Powder Materials
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• v.11 no.6 s.47
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• pp.515-521
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• 2004

Fe(C) nanocapsules were prepared by the chemical vapor condensation(CVC) process using the pyrolysis of iron pentacarbonyl $(Fe(CO)_5)$. Their characterizations were studied by means of X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The long-chained Fe(C) nanocapsules hav-ing the mean size of under 70 nm could be obtained below $1100^{\circ}C$ in different gas flow rates. The particle size of the powders was increased with increasing decomposition temperature, but it was decreased with increasing CO gas flow rate. The Fe powders produced at $500^{\circ}C$ consisted of three layers of ${\alpha}$-Fe/$Fe_3C$/amorphous phases, but it had two phase core-shell structure which consited of $Fe_3C$ phase of core and graphite of shell at $1100^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.60-72
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• 2001

This paper presents the user-interactive productivity analysis model based on material balance as well as deliverability equations equipped with EOS model to perform a productivity analysis for Gorae V structure, Donghae-1 gas field. This model is designed to be able to analyse the productivity in the case of reservoir contacting with the aquifer. Also, in order to investigate the effect of condensation on productions, condensation phenomenon is considered as an apparent skin effect in the computation of bottomhole pressure from average reservoir pressure. By utilizing the developed model, we investigate the productivity analysis for B2 layer of Garae V structure with the various production cases in volumetric and non­volumetric reservoirs that contact with aquifer. From the results in the case of 5500 MMSCF/year of production and reservoir-aquifer contacting angle 270$^{\circ}C$ with aquifer size of 10 times greater than reservoir, B2 layer could maintain peak production rate even after 8.5 years of production by considering the bottomhole pressure which is estimated above the operating pressure of 1298 psia. It is also found that condensate will be formed after 1100 days of production and existed throughout the reservoir at 1270 days. Note that the computed reservoir pressure of B2 layer is maintained sufficiently high enough for production due to the water influx into the reservoir, and skin effect caused by condensation is not significant.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.225-230
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• 2013

Cryopump removes gas molecules by condensation and adsorption. Therefore, cryo-surface temperature and corresponding vapor pressure influence directly the pumping performance. If the surface temperature of any part is neither low nor high, there occurs the desorption of gas molecules condensed or adsorbed, and the emitted molecules can be captured again, which leads to a time-consuming and fluctuating change of the pressure. Though every gas can show such a pressure instability at a specified temperature range, the instability generated in a sputter system using Ar as a working gas and operating with a cryopump is especially undesirable. In this paper the cause of the argon instability is analyzed and corrective is provided through the measurement of the Ar recovery time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.590-593
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• 2003

Ozone is a strong and useful oxidizing gas for the fabrication of oxide thin films. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Crone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure. We found the decomposition in the ozone concentration negligible if the condensed ozone is transferred from the ozone condensation system to the film growth chamber within a few minutes.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.618-630
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• 1999

An analytical model that includes the steam condensation effect has been derived and a parametric study has been performed. In addition, a series of experiments were performed and a total of 34 experimental data for the onset of CCFL in nearly horizontal countercurrent two-phase How have been obtained for various flow rates of water. Comparisons of the present CCFL data with slug formation models show that the agreement between the present as well as the existing model and the data is about the same. However, the deviation between the Taitel and Dukler's model predictions and the data is the largest when if j$_{f}$<0.04 m/s. A parametric study of the effect of the steam condensation using the present model shows that, when all local conditions are similar, the model predicted local gas velocities that cause the onset of flooding are slightly lower when condensation occurred. Based on the visual observation and the evaluation of the present work, it has been concluded that the criterion derived for the onset of slug flow can be directly used to predict the onset of inner flooding in nearly horizontal two-phase flow within the experimental ranges of the present work.