• Journal of computational fluids engineering
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• v.17 no.3
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• pp.39-44
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• 2012

In this study, a longitudinal pitch effect on in-line tube bank heat transfer has been analyzed numerically. To verify the accuracy of the solver model and boundary conditions, global Nusselt number(Nu) and pressure drop across the 2 row tube bank are compared with the existing experimental correlations under 500 ~ 2,000 Reynolds number(Re) range. By changing transverse pitch($S_T$) or longitudinal pitch($S_L$) separately in tube bank, we're trying to identify the each effect on heat transfer. We found that the effect of transverse pitch can be accounted for Reynolds number evaluated with maximum velocity($V_{max}$) at the smallest flow area similar to most existing correlations. Variation of the longitudinal pitch($S_L$) has a greater impact on the heat transfer compared to the transverse pitch($S_T$). Overall Nusselt number increases with larger longitudinal pitch($S_L$), however individual Nusselt number of the tube row has significant difference after the first row.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.4
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• pp.335-340
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• 2007

A new correlation between the Nusselt number based on modified heat transfer coefficient and Reynold number based on droplet-flow-rate was developed for the experimental data. The modified heat transfer coefficient was defined as ratio of wall heat flux to droplet subcooling. In the previous reports, the local heat flux of spray cooling in the film boiling region was experimentally investigated for the water spray region of $D_{max} = 0.0007{\sim}0.03m^3/(m^2s)$ . In the region near the stagnation point of spray flow, a new heat transfer correlation is recommended which shows good predictions for the water spray region of $D_x{\le}0.01m^3/(m^2s)$.

• Solar Energy
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• v.15 no.3
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• pp.105-117
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• 1995

Heat transfer coefficients on a single spiral coil tube in the furan foundry sand fluidized bed have been investigated. Heat transfer coefficients(ho) to an immersed single spiral coil tube were measured in the bed. The bed diameter was 0.21 m. The following quantities were varied: (l)bed temperature, (2)mean particle diameter, (3) fluidization rate, (4)the ratio of heated coil tube pitch to diameter(p/Do), and (5)the ratio of heated coil tube pitch to mean particle diameter(p/dp). In addition, the experimental values of maximum Nusselts number were compared with the values of maximum Nusselts number predicted by the existing correlations. The values of heat transfer coefficient increase with the increase in bed temperature and fluidization rate, but decrease with increase in particle diameter. An empirical formulus of maximum Nusselts number which is applicable in the furan foundry sand fluidization bed is as follows: $$Nu_{max}=1.01\;Re^{0.48}Prg^{0.4}(p/dp)^{0.28}(p/Do)^{0.05}$$.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.285-290
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• 2000

The present study was conducted to determine flooding heat transfer limitation of a two-phase closed thermosyphon using PFC as working fluid. The variables such as pipe inner diameter, working fluid property, operating temperature were examined by way of analytic method. Comparison of experimental data on flooding heat transfer limitation shows a fairly good agreement with the analytic results. An expression fur flooding maximum heat transfer rate was formulated as a function of Bond number and saturation pressure and written as follows ; $Q_{max} =0.989{\cdot}P_s^{0.286}{\cdot}Bo^{1.74}$.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.274-281
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• 1982

Ultraviolet spectrophotometric investigation have been carried out on the systems of pentamethylbenzene and hexamethylbenzene with iodine and iodine monochloride in carbon tetrachloride. The results reveal the formation of the one to one molecular complexes. The equilibrium constants were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperature. Thermodynamic parameters for the formation of the charge transfer complexes were calculated from these values. These results indicate that the complex formed between polymethylbenzene and iodine monochloride is more stable than that in the case of iodine. This may be a measure of their relative acidities toward polymethylbenzene, which is explained in terms of the relative electronegativities of halogen atoms. These results combined with previous studies of this series indicated that ${\lambda}_{max}$ shift to red with the increasing number of methyl groups on benezene ring and that the relative stabilities of these complexes increase in the order, Benzene < Toluene < Xylene < Durene < Mesitylene < Pentamethylbenzene < Hexamethylbenzene. The reason for the order found is thus additionally discussed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.1 s.6
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• pp.1-13
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• 2005

For integrated transit networks operated with diverse transit modes, it is difficult to find related literatures on the provision of multiple travel time routes information. This study proposes a methodology on how to select K number of least time transit routes in the integrated transit network with two modes, bus and subway. In the Proposed method, three constraints usually (will be) encountered for decision by users-(1) service time constraints of travel modes, (2) maximum payment fare constraints under the integrated distance based fare system, and (3) maximum number of transfer constraints - are taken into consideration in the searched routes. The experimental studies shows that the proposed method properly provides K number of least time routes. In addition, it somehow proves that by combinatorially considering three constraints the proposed method can be evaluated as to enlarge the quality as well as the diversity of route information demanded by users.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.4
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• pp.329-337
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• 1981

Natural convection within inclined high aspect-ratio rectangular cavity was analysed by using finite element method. For a cavity of sapect-ratio 20, the flow patterns of secondary vortices and the heat transfer characteristics on the wall were obtained with the variation of tilt angle as well as Ra and Pr. The observation on the governing equations shows that the increase of Ra/Pr and the existence of nonzero tilt angle make the flow pattern more complicated and so it becomes difficult to obtain converging solution. The max. value of Ra/Pr attained in this study was 3x10$\^$4/at 0$\^$0/ tilt angle and 1.1x10$\^$4/ at 45.deg. tilt angle for aspect ratio 20and Pr=0.7. Finally an empirical formula for Nusselt number which can accout for the effect of tilt angle is obtained for laminar flow regime.

• Journal of Plant Biology
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• v.37 no.3
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• pp.333-341
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• 1994

Effective plant regeneration from immature cotyledons of soybean [Glycine max (L.) Merr.] cultivars was achieved via somatic embryogenesis. Somatic embryogenesis was performed with the cotyledons of immature embryos 14-20 d after flowering. Immature cotyledons of cv. Whangkeum were placed abaxial or adaxial side down on modified MS medium containing 20mg/L 2,4-D. The greatest number of somatic embryos, 1.2 per cotyledon, was produced from those of 4.0-4.9 mm in length which had been placed abaxial side down. Among cvs. Pecking, Whangkeum and Baekwoon, Pecking had the highest embryo induction efficiency with 4.3 somatic embryos per cotyledon in 20mg/L 2,4-D treatment and with 1.0 embryo per cotyledon in 8mg/L NAA treatment. Germinable globular somatic embryos were induced with the highest efficiency, 27.6%, in 20mg/L 2,4-D and were proliferated efficiently on liquid medium containing 10mg/L 2,4-D. The globular somatic embryos developed into germinable mature somatic embryos on medium containing 10 $\mu$M CoCl2, 9% sucrose, and 0.5% activated charcoal. These mature somatic embryos germinated on hormone-free mediu. After transfer to the soil, regenerated plants with seeds were obtained.

• ETRI Journal
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• v.46 no.2
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• pp.290-306
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• 2024

To treat the novel COronaVIrus Disease (COVID), comparatively fewer medicines have been approved. Due to the global pandemic status of COVID, several medicines are being developed to treat patients. The modern COVID medicines development process has various challenges, including predicting and detecting hazardous COVID medicine responses. Moreover, correctly predicting harmful COVID medicine reactions is essential for health safety. Significant developments in computational models in medicine development can make it possible to identify adverse COVID medicine reactions. Since the beginning of the COVID pandemic, there has been significant demand for developing COVID medicines. Therefore, this paper presents the transferlearning methodology and a multilabel convolutional neural network for COVID (MLCNN-COV) medicines development model to identify negative responses of COVID medicines. For analysis, a framework is proposed with five multilabel transfer-learning models, namely, MobileNetv2, ResNet50, VGG19, DenseNet201, and Inceptionv3, and an MLCNN-COV model is designed with an image augmentation (IA) technique and validated through experiments on the image of three-dimensional chemical conformer of 17 number of COVID medicines. The RGB color channel is utilized to represent the feature of the image, and image features are extracted by employing the Convolution2D and MaxPooling2D layer. The findings of the current MLCNN-COV are promising, and it can identify individual adverse reactions of medicines, with the accuracy ranging from 88.24% to 100%, which outperformed the transfer-learning model's performance. It shows that three-dimensional conformers adequately identify negative COVID medicine responses.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.596-603
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• 2004

This paper proposes an expert system based on the pattern recognition method which can enhance the accuracy and effectiveness of real-time bus reconfiguration strategy for the transfer of faulted load when a main transformer fault occurs in the automated substation. The minimum distance classification method is adopted as the pattern recognition method of expert system. The training pattern set is designed MTr by MTr to minimize the searching time for target load pattern which is similar to the real-time load pattern. But the control pattern set, which is required to determine the corresponding bus reconfiguration strategy to these trained load pattern set is designed as one table by considering the efficiency of knowledge base design because its size is small. The training load pattern generator based on load level and the training load pattern generator based on load profile are designed, which are can reduce the size of each training pattern set from max L/sup (m+f)/ to the size of effective level. Here, L is the number of load level, m and f are the number of main transformers and the number of feeders. The one reduces the number of trained load pattern by setting the sawmiller patterns to a same pattern, the other reduces by considering only load pattern while the given period. And control pattern generator based on exhaustive search method with breadth-limit is designed, which generates the corresponding bus reconfiguration strategy to these trained load pattern set. The inference engine of the expert system and the substation database and knowledge base is implemented in MFC function of Visual C++ Finally, the performance and effectiveness of the proposed expert system is verified by comparing the best-first search solution and pattern recognition solution based on diversity event simulations for typical distribution substation.