• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.6 s.237
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• pp.696-702
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• 2005

The effect of incidence angle on the endwall heat (mass) transfer characteristics within a turbine rotor cascade passage has been investigated by employing the naphthalene sublimation technique. The experiments are carried out at the Reynolds number of $2.78{\times}10^5$ for two incidence angles of -5 and 5 dog. The result shows that the incidence angle has a considerable influence on the transport phenomena over the endwall. The positive incidence angle tends to promote development of the pressure-side leg of a leading-edge horseshoe vortex. The endwall thermal load is augmented by 7.5 percents at i = -5 deg but is reduced by 2.5 percents at i = 5 deg, in comparison with that at the design condition.

• Korean Journal of Pharmacognosy
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• v.27 no.2
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• pp.111-116
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• 1996

The components were isolated from the root of Astragalus membranaceus and their structures were characterized as 3,4-methylenedioxypyrrolealdehyde, $7-O-{\beta}-D-glucopyranosyl$ 7, 3'-dihydroxy-4'-methoxy isoflavone and a naphthalene derivative on the basis of spectral and physical methods. $7-O-{\beta}-D-glucopyranosyl$ 7, 3'-dihydroxy-4'-methoxy isoflavone and the naphthalene compound showed protective effect on $CC_{l4}-induced$ cytotoxicity in primary cultured rat hepatocytes.

• Journal of the Korean Chemical Society
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• v.16 no.3
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• pp.142-148
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• 1972

The intermolecular orbital theory was applied to the Diels-Alder reaction of naphthalene, phenanthrene and 1,2-benzanthracene with maleic anhydride. The expected positions of thermal addition in the alternant bydrocarbons were in agreement with experiment. It was also possible to explain the relative proportions of two isomeric adducts with the calculated stabilization energies. Comparison of the results with paralocalization energies of Brown gave agood linear correlation.

• Journal of the Korean Chemical Society
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• v.34 no.4
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• pp.325-330
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• 1990

The solubilities of caffeine in supercritical ammonia were measured at various temperatures and pressures to represent the relationship between the solubility and the density of ammonia at desired temperature and pressure by means of a simple equation. Using the equation, the interaction virial coefficient between ammonia and caffeine has been determined to give the parameters of Lennard-Jones potential function for the system. Furthermore, there are comparisons and discussions of the interaction virial coefficients and Lennard-Jones potential functions determined by the same techniques from the solubility data of naphthalene in supercritical ammonia and of caffeine and naphthalene in supercritical carbon dioxide from existing data sources others.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.339-342
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• 2003

This study is intended to investigate the influence of chemical admixture on bleeding of concrete. According to the results, the amount of bleeding with elapse of time does not make much difference in the case of naphthalene type water reducing agent(RN), Naphthalene type high performance water reducing agent(HN) and Melamine type high performance water reducing agent(HM), but it is largest in the case of Polycarbonic acid type high performance water reducing agent(HP). Bleeding speed also is highest in the case of HP in comparison with other chemical admixture. This prove that high performance water reducing agent like HP has little effect on fluidity of concrete, but influences the amount of bleeding more greatly, instead. As properties of hardened concrete, compressive strength makes no difference in the case of RN, HN and HM, but on the other hand, it increases in the case of HP due to a decrease of air content and the large amount of bleeding.

• Advances in concrete construction
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• v.2 no.4
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• pp.301-308
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• 2014

The present research work is on the effect of sawdust ash (SDA) on the mechanical strengths of self compacting concrete (SCC) using naphthalene sulfonate (NS) as a plasticizer. Experiments on compressive, flexural and splitting tensile strengths are conducted and the data analyzed using the Minitab 15 software. The results showed that SDA can defer the reaction of cement hydration and prolong the setting times of cement paste. This was very much pronounced on the flexural and splitting tensile strengths at 90 days of curing which are 36 % and 33 % higher than the control strengths, respectively. The study has proposed strength relations of mortar compressive strength with the flexural and splitting tensile strengths and these are, 5 and 7 times respectively. The flexural strength is 1.5 times that of the splitting tensile. Finally, linear models were developed on these relationships.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.973-982
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• 1997

Effect of vortex generator on the heat transfer enhancement of electronic chips is investigated using naphthalene sublimation technique. Experiments are performed for a single chip and chip arrays, and shape of vortex generator, position of vortex generator, stream wise chip spacing and air velocity are varied. Local and average heat transfer coefficients are measured on the top surface of simulated electronic chips, and compared with those obtained without vortex generator. In case of a single chip, heat transfer augmentation is seen only on the upstream portion of chip surface, while heat transfer enhancement is found on the whole surface for chip arrays. Rectangular wing type vortex generator is found to be more effective than delta wing.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.119-124
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• 2000

The heat transfer characteristics of confined turbulent slot jet impingement on the flat plate with square rods(turbulence promoter) have been experimentally investigated. The effects of jet Reynolds number (Re=3900, 5800, 7800, 9700), dimensionless slot-to-plate distance(H/B=4, 6, 8) clearance(c) between square rods and the plate, and the length(d) of a side of the square rod were examined. Measurement or heat transfer rate were conducted using naphthalene sublimation technique. When square rods were inserted over the heat transfer surface, heat transfer rate was slightly increased in the wall jet region.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.61-66
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• 2003

Fouling is very serious problem in heat exchanger because it rapidly deteriorates the performance of heat exchanger. Cross-flow heat exchanger with vortex generators is developed, which enhance heat transfer and reduce fouling. In the present heat exchanger, shell and baffle are removed from the conventional shell-and-tube heat exchanger. The naphthalene sublimation technique is employed to measure the local heat transfer coefficients. The experiments are performed for single circular tube, staggered array tube bank and in-line array tube bank with and without vortex generators. Local and average Nusselt numbers of single tube and tube bank with vortex generator are investigated and compared to those of without vortex generator.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.408-413
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• 2003

Naphthalene sublimation technique is used to investigate the average and local heat transfer from the circular rod, and to determine the average and local heat transfer from the circular rod with and without square wing type mixing vane in axial flow. The experiments are performed for a circular rod and flat plate with and without mixing vane in wind tunnel. In comparison with flat plate and circular rod in axial flow, averaged Nusselts number is increased 2 times as the increase of Reynolds number with mixing vane. Longitudinal vortex induced by square wing type has the stronger vortex strength, so square wing type vortex generator shows an effect further in downstream.