• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.2
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• pp.212-222
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• 1998

Heat transfer performance improvement by fin and groovs is studied for condensation of R-11 on integral-fin tubes. Eight tubes with trapczodially shaped integral-fins having fin density from 748 to 1654fpm(fin per meter) and 10, 30 grooves are tested. A plain tube having the same diameter as the finned tubes is also used for comparison. R-11 condensates at saturation state of 32 $^{\circ}C$ on the outside tube surface coded by inside water flow. All of test data are taken at steady state. The heat transfer loop is used for testing singe long tubes and cooling is pumped from a storage tank through filters and folwmeters to the horizontal test section where it is heated by steam condensing on the outside of the tubes. The pressure drop across the test section is measured by menas pressure gauge and manometer. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, overall heat transfer coefficients of finned tube are enhanced up to 1.6 ~ 3.7 times that of a plain tube at a constant Reynolds number. 2. Friction factors are up to 1.6 ~ 2.1 times those of plain tubes. 3. The constant pumping power ratio for the low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio. 4. A tube having a fin density of 1299fpm and 30 grooves has the best heat transfer performance.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.104-104
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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 is installed in the form of coolant block around vertical tube and the heat by primary condensation is transferred to the coolant water. The local temperatures are measured at 15 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 local heat transfer coefficient increases as the increase of inlet steam flow rate and decreases as the decrease 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 represented with the 165 sets of local heat transfer data. 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 the Korean Chemical Society
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• v.30 no.1
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• pp.90-100
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• 1986

Along with synthesizing a model oligodeoxyribonuclotide GpApApTpTpCp which had the EcoRI recognition site according to "Phosphotriester Method", reported methods for protecting functions, condensation, deprotection, purifying products, quantification and identification were evaluated and modified. It was realized that oligomers were efficiently synthesized by elongating by dimer unit per step of the condensation and the condensation yields were decreased with increased numbers of the residues. The problems of quantification/identification involved in the oligonucleotide synthesis using small amount of the reactants were solved by employing UV/IR spectrophotometry and hplc/tlc. It was also proved that a nucleotide having the exposed 5'-OH function was well synthesized by condensing a 5'-OH nucleotide and a phosphodiester nucleotide whose molar ratio was intendedly made to be 1 : 1.2 and then detritylating followed by washing with an aqueous solution of sodium bicarbonate. Spectrophotometric and chromatographic data of the nucleotides and their derivatives concerned in this synthetic work were prepared.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.611-617
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• 2008

Nowadays Plate Heat Exchanger (PHE) is widely used in different industries such as chemical, food and pharmaceutical process and refrigeration due to the efficient heat transfer performance, extreme compact design and efficient use of the construction material. In present study, discussed main conception of plate heat exchanger and applied in vacuum. PHE and aimed apply in the fresh water generator which installed in ship to desalinate seawater to fresh water use heat from engines. The experiment is proceeded to investigate the heat transfer between cold and hot fluid stream at different flow rate and supply temperature of hot fluid. Generated fresh water as outcome of the system. PHE is an important part of a condensing or evaporating system. One of common assumptions in basic heat exchanger design theory is that fluid is to be distributed uniformly at the inlet of each fluid side and throughout the core. However, in practice, flow mal-distribution is more common and can significantly reduce the heat exchanger performance. The flow and heat transfer are simulated by the k-$\varepsilon$ standard turbulence model. Moreover, the simulation contacted flow maldistribution in a PHE with 6 channels.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4180-4184
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• 2012

The target compounds 6-11a-e were synthesized by condensing 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones 5a-f with various aromatic carboxylic acids in the presence of phosphorous oxychloride. The structures of newly synthesized compounds were characterized by IR, $^1H$ NMR, $^{13}C$ NMR, elemental analysis and mass spectrometric studies. All the synthesized compounds were screened for their antibacterial activity. Almost all the tested compounds were potent against four different strains of bacteria when compared with that of reference drug ciprofloxacin. Compounds 6c, 6e, 8d, 9b, 9e, 11a and 11b showed nearly equal or lower MIC values than standard drug, against all four tested bacterial strains but rest of the compounds showed excellent antibacterial activities.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.3943-3949
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• 2012

A series of aromatic hydrazides 3a-j were prepared by refluxing esters 2a-j with hydrazine hydrate in methanol, which were prepared by the esterification of 1a-j. Acetohydrazides 3a-j upon treatment with carbon disulfide and methanolic potassium hydroxide yielded potassium dithiocarbazate salts 4a-j, which on refluxing with hydrazine hydrate yielded substituted 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones 5a-j. The target compounds 6a-j were synthesized by condensing furan-3-carboxylic acid in the presence of polyphosphoric acid under reflux. The structures of newly synthesized compounds were characterized by IR, $^1H$ NMR, $^{13}C$ NMR, elemental analysis and mass spectrometric studies. All the synthesized compounds were screened for their urease, acetylcholine esterase inhibition, antioxidant and alkaline phosphatase inhibition activity. Almost all of the compounds 6a-j showed good to excellent activities against urease and acetylcholine esterase more than the reference drugs. Compounds 6f and 6g were more potent scavenger of free radicals than the reference n-propyl gallate. Compound 6b and 6h showed excellent activities of alkaline phosphatase as compare to the reference $KH_2PO_4$.

• Journal of the Korean Chemical Society
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• v.5 no.1
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• pp.38-41
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• 1961

By varying groups on biologically active molecules, it is possible to produce analogues which sometimes inhibit the action of the parent compound. Such is true of taurine(${\beta}$-amino-ethane sulfonic acid)as an analogue of ${\beta}$-alanine and of pantoyl taurine for pantothenic acid. It seemed possible that the sulfonic acid analogues of amino acids built into peptides might possibly produce inhibition of the parent peptide. Tauryl-L-histidine was selected to prepare as an analogue of carnosine(${\beta}$-alanyl-L-histidine). There were several reasons for this choice. Camosine causes a slight contraction of isolated uterine muscle and inhibition of this action can be easily tested. Also, taurine, being a ${\beta}$-amino sulfonic acid, is much more stable than the ${\beta}$-amino sulfonic acids. Phthalyl tauryl-L-histidine methyl ester was prepared by condensing phthalyl tauryl chloride with histidine methyl ester in chloroform. The yields were quite low possibly due to reaction between the acid chloride and the imidazole of histidine. Approximately 50 per cent yield of crude amorphous product was obtained, but upon purification by crystallization they yielded only 25 percent of a pure product. The methyl ester was removed by acid hydrolysis to prevent partial cleavage of the phthalyl group. Crystalline tauryl histidine was then obtained from this acid by removal of the phthalyl group by hydrazinolysis. Tests for inhibition were carried out by comparing the action of camosine on isolated uterine muscle before and after tauryl histidine had been added to the bath surrounding the muscle strip. Only in very high relative concentrations of tauryl histidine was there any demonstrable inhibition.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.42-47
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• 2012

In this paper, alternative natural refrigerant R290(Propane), R600(Butane), R717(Ammonia), R1270(Propylene) for freon refrigerant R22 were used working fluids for 2-stage compression and 1-stage expansion refrigeration system. The operating parameters considered in this study included evaporation temperature, condensation temperature, subcooling degree, superheating degree, mass flow rate ratio of inter-cooler. The main results were summarized as follows : The COP of 2-stage compression and 1-stage expansion refrigeration system increases with the increasing subcooling degree and mass flow rate ration of inter-cooler, but decreases with the increasing evaporating temperature, condensing temperature and superheating degree. Therefore, subcooling degree, mass flow rate ratio of inter-cooler of 2-stage compression and 1-stage expansion refrigeration system using natural refrigerants have an effect on COP of this system. The COP of natural refrigerants was higher than the COP of freon R22 in this study, so points to be considered are the security, the attached facilities for natural refrigerants than COP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5430-5437
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• 2011

The objective of this study is to investigate the cooling performances of the electrical air-conditioning system using electric driven scroll compressor for zero emission passenger vehicles. This air conditioner with air source was used R-134a as a refrigerant and installed in a real zero emission passenger vehicle for tests under various driving conditions. The cooling performance of the electrical air conditioner was affected by driving velocities and conditions of the tested vehicle. The condensing rate of the condenser during driving is better than that of the idle condition. The average cool down temperature in the cabin room decreased on average $5.2^{\circ}C$ with the increase of the outdoor temperature from $20.0^{\circ}C$ to $30.0^{\circ}C$. In addition, the cooling performances were sufficient for cooling loads of the tested passenger car under tested conditions.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.217-222
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• 2014

In order to improve the heat efficiency of the general residential boiler, we performed an experiment of condensation heat transfer to air pre-heating exchanger adhered to the condensing boiler. In this study, surface roughness was imposed on the surface of stainless steel by etching. And in order to evaluate the heat transfer performance on each plate, the counter flow heat exchanger fabricated with polycarbonate in used. As a result, on etching treated plate's overall heat transfer coefficient is higher than the original plate. And etching treated plate during 60 seconds with etchant is the to average 15% compared to bare stainless steel. And we studied the heat transfer enhancement factor through the analysis of surface characteristics using AFM.