• Proceedings of the KSME Conference
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• 2001.06d
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• pp.220-225
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• 2001

The plate heat exchanger is characterized. by low pressure drop and high heat transfer coefficient. The experimental study has been performed on the condensation heat transfer and pressure drop characteristics of the plate heat exchangers in this study. In the present study, a brazed type plate heat exchanger was investigated at a chevron angle of $45^{\circ},\;55^{\circ},\;and\;70^{\circ}$ with R410A. Condensation temperatures were varied from $20^{\circ}C\;and\;30^{\circ}C$, and mass flux was ranged from $13{\sim}34\;kg/m^{2}s$ with constant heat flux ($=5\;kw/m^{2}$). The heat transfer coefficient and pressure drop increased with the chevron angle. Average condensation heat transfer coefficients and pressure drops are decreased with increasing condensation tempeature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.17-18
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• 2012

Moisture condensation leading to defects that occur repeatedly in the winter, and recognize the same method, the problem of the other buildings in the same area again and again, a vicious cycle that occurs due to the temporary lack of systematic research and processing way of coping has been recurring. In this study, as warming progresses, more inside the air-conditioned summer season due to an increase in the ambient temperature of the condensation phenomenon to happen about summer wall condensation phenomena are expected to analyze the case of a building to prevent condensation and for insulation designs are proposed.

• Structural Engineering and Mechanics
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• v.61 no.6
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• pp.807-816
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• 2017

In this paper, we introduce an efficient new model reduction method, named the automated static condensation method, which is developed for the local analysis of large finite element models. The algebraic multilevel substructuring procedure is modified appropriately, and then applied to the original static condensation method. The retained substructure, which is the local finite element model to be analyzed, is defined, and then the remaining part of the global model is automatically partitioned into many omitted substructures in an algebraic perspective. For an efficient condensation procedure, a substructural tree diagram and substructural sets are established. Using these, the omitted substructures are sequentially condensed into the retained substructure to construct the reduced model. Using several large practical engineering problems, the performance of the proposed method is demonstrated in terms of its solution accuracy and computational efficiency, compared to the original static condensation method and the superelement technique.

• YAKHAK HOEJI
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• v.6 no.1
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• pp.5-7
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• 1962

Like the condensation reaction of general aldehyde, that of benzaldehyde with semicarbazide also depends upon the concentration of carbonium ion that is produced by hydrogen ion. The lower pH value is the facility of the formation of carbonium ion in the condensation reaction, while the reactivity of semicarbazide as a reactant is reduced. In this paper, therefore we want to find out the optimum pH value in the condensation reaction of benzaldehyde with semicarbazide. This optimum pH value was determined by using the simple paper-chromatographic method. According to the result of this experiment, the condensation reaction between benzaldehyde and semicarbazide reacts with its highest point at 3.5pH value. It seems clear that at this point the benzaldehyde acquires the most suitable amount of carbonium ion for the condensation reaction with semicarbazide, and the semicarbazide also has the optimum reactivity.

• KIEAE Journal
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• v.10 no.2
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• pp.57-62
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• 2010

In case of earth-covered storage, the condensation occurs on surface of wall and stores in summer with high humidity because of low temperature of constructional mass. Therefore, the preventive plans should be considered to protect stores from the damage by corrosion in earth-covered storages. This study aims to suggest the methods of forced ventilation by the air, to solve the problems of construction's surface condensation at the Magazine of igloo type which is similar to earth-covered storages. A fan was installed at the air outlet for exhaust gas to conduct forced ventilation. The surface and indoor temperature were measured, and then the influence of those on condensation was analyzed. The results of this research are follows; 1) Forced ventilation by a fan affects the rise in surface temperature of walls and stores. 2) The condensation on surface of walls and stores was reduced after operating a fan.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.14-22
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• 1998

The growth by steam condensation of an hygroscopic aerosol is investigated using the condensation rate model which has been derived from the mass and heat transfer equations. The present model accounts for both the solute and Kelvin effects. When the hygroscopicity is considered, condensation can occur on hygroscopic seed particles even under subsaturated steam conditions. This study focuses on the effect of hygroscopicity on the evolution of the particle size distribution and decay of the total aerosol concentration. It is found that hygroscopicity causes the particle size distribution to rapidly move upward even in a very short time, resulting in substantially higher decay of the total aerosol concentration than the case without considering hygroscopicity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.463-469
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• 1990

A rapid expansion of moist air of condensible gas through a supersonic nozzle gives rise to condensation of nonequilibrium and equilibrium processes. Because most of the effects of condensation on the flow are caused by process of nonequilibrium condensation, it is very important to know the onset. condition of nonequilibrium condensation. In the present study, the relation between the initial relative stagnation humidity and the onset Mach number, for the case of the similarity law suggested by Zierep and Lin. Furthermore, the present theoretical result number is compared with the experimental, numerical and other results.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.17 no.4
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• pp.267-278
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• 2013

We consider zero range processes with density dependent jump rates g given by $g=g(n,k)=g_1(n)g_2(k/n)$ with $g_1(x)=x^{-\alpha}$ and $$g_2(x)=\{^{x^{-\alpha}\;if\;a&lt;x}_{Mx^{-\alpha}\;if\;x{\leq}a}$$. (0.1) In this case, with 1/2 < a < 1 and ${\alpha}$ > 0, we show that non-complete condensation occurs with maximum cluster size an. More precisely, for any ${\epsilon}$ > 0, there exists $M^*$ > 0 such that, for any 0 < M ${\leq}M^*$, the maximum cluster size is between (a - ${\epsilon}$)n and (a + ${\epsilon}$)n for large n. This provides a simple example of non-complete condensation under perturbation of rates which are deep in the range of perfect condensation (e.g. ${\alpha}$ >> 1) and supports the instability of the condensation transition.

• Journal of the Korean Professional Engineers Association
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• v.44 no.4
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• pp.44-49
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• 2011

For the pleasant dwelling place, the most of apartments are designed with the increased green area ratio in ground space and the underground parking lot. However, the condensation in underground space has occasionally occurred due to the insufficient ventilation and insulation treatment. Despite reinforcement of the insulation treatment and mechanical ventilation for the preventing method of condensation. It seems difficult to expect preventing effects for the condensation without consideration of the thermal characteristic of structures. Furthermore, no fundamental measure has been established because maintenance work for these defects incurs a lot of costs and these defects could be occurred again. This study suggests a new method for preventing floor surface condensation through analyzing the reasons of condensation which occurred in the underground floor.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1255-1260
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• 2006

This present study analyzed temperature depreciation ratio of window inside surface by KS F 2295 'Procedure for determining fenestration product condensation resistance values'. it estimated window indoor surface condensation due to variable environmental condition. Performance of condensation resistance by using temperature depreciation ratio until applied Low-e and Ar glazing improved about 45% from 24 mm clear. Temperature depreciation ratio by KS F 2295 considers analytic index of window condensation due to variable boundary condition.