• Journal of the Korean Geographical Society
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• v.48 no.3
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• pp.336-347
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• 2013

This paper presents an evaluation of stream restoration projects in Seoul with a focus on dissolved oxygen. Five test sites across four streams were measured for dissolved oxygen (DO) in late May to early June in 2012 and compared against a set of minimum and maximum thresholds. Only one test site, Hwarang-cheon, showed measurements below 6 mg/l DO. Towards the upper limit, the Hwarangcheon site was the only tested stream which was not at risk of DO supersaturation. The Danghyeon-cheon site had the highest probability of supersaturation, with DO saturation exceeding 130% expected 86.5% of the time. When measured every hour during daytime, DO levels showed diurnal variations, peaking in the afternoon. However, they showed inconsistent results along transects of the streams. Overall, the streams are rich in DO. To maintain the streams in good standing, nutrient loading should be addressed to prevent potential algal bloom induced hypoxic events down the line.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1311-1319
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• 1990

For the purpose of preventing the flow undulation in the cascade of steam turbine, the blades are made into a constant expansion rate in static pressure. And the flow in those cascades is transonic or supersonic in the range of 0.7-2.0 in Mach number. As a consequence, an oblique shock wave, known as inner or outer edge shock wave, arises in the flow of cascades. Especially when the steam in cascades is in a state of high wetness, nonequilibrium condensation and condensation shock wave occur, and they give rise to an interference with oblique shock wave. In the present study the case of expansion of moist air through a supersonic nozzle of constant expansion rate, which behaves similar to that of wet steam, was adopted. The effect of nonequilibrium condensation on the oblique shock wave generated by placing the wedge into the supersonic part of the nozzle was investigated. Furthermore, the relationship between nonequilibrium condensation zone and incident point of the oblique shock wave, oblique shock wave angle, the variations of angles of incident and reflected shock waves due to the variation of initial stagnation supersaturation and the relationship between the height of Mach stem and initial stagnation supersaturation are discussed.

• Resources Recycling
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• v.24 no.4
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• pp.22-31
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• 2015

From results obtained by adjusting experimental variables based on the kinetic, the nucleation rate for formation of precipitated calcium carbonate (PCC) was investigated. Formation behavior of PCC was investigated for various concentrations of NaOH solution and $Na_2CO_3$ addition methods in the $Ca(OH)_2$ slurry. The range of nucleation rate was investigated for dissolution rates of major ion concentrations, $Ca^{2+}$ and $CO{_3}^{2-}$. In case of high concentration of major ions, vaterite and calcite were synthesized. The high nucleation rate was achieved for lower either $Ca^{2+}$ or $CO{_3}^{2-}$ ion concentration, calcite was mainly synthesized and when concentration of major ions was low, aragonite was synthesized. Furthermore, the formation of calcite was decreased with increasing concentration of NaOH. homogeneous aragonite could be obtained by addition 5 M NaOH. Therefore, in this study, specific shape of polymorphs could be prepared through controlling supersaturation.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.1-5
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• 1997

The growth mechanism of AMT(Ammonium Meta-Tungstate) crystal was interpreted as two-step model. The contribution of the diffusion step increased with the increase of temperature, crystal size, and supersaturation. The crystal size distribution from a batch cooling crystallizer was predicted by the numerical solution of a mathematical model which uses the kinetics of nucleation and crystal growth. Temperature control of a batch crystallizer was studied using Learning control algorithm. The purity of AMT crystal producted in this investigation was above 99.99%.

• Journal of the Mineralogical Society of Korea
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• v.9 no.2
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• pp.64-70
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• 1996

Early weathering products of anorthosite were investigated by using scanning electron microscopy in order to trace the development of halloysite particles and aggregates. Tiny short tubes or spheres precipitate on the plagioclase surface in the initial stage of weathering and form the compact globular aggregates. With continued growth, several globules are coalesced into wrinkled halloysite aggregates, and short tubes or spheres in globules grow into long tubes forming sheaf-like aggregates. Particle shape of halloysite varies with changing supersaturation degree of weathering solution, and determines the morphology of halloysite aggregates.

• Bulletin of the Korean Chemical Society
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• v.1 no.1
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• pp.26-28
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• 1980

The surface tensions, the chemical potentials and the densities of various liquids such as argon, nitrogen, helium, ammonia, and water are calculated using the significant structure theory of liquids. And using these calculated values, the critical supersaturation ratios and the radii of the above materials are determind according to the classical Becker-Doring and the revised Lothe-Pound theories. The results are compared with the experimental values and well agreed with the available experimental data.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.09a
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• pp.55-63
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• 1998

The growing conditions of barium nitrate Ba(NO3)2 single crystals by aqueous solution method have been studied. Supersaturation of Ba(NO3)2 was 0.7% at 32.0$^{\circ}C$ and about 3% 34.0$^{\circ}C$. The obtained single crystals have three kind of morphology; the tertrahedron, the cube and rarely dodecahedron face. The faces of obtained crystals have been identified by X-ray diffractometer.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.974-978
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• 1998

The kinetics of crystal growth and nucleation in dependence on the supersaturation of an aqueous solution of 3-nitro-1,2,4-triazol-5-one(NTO) were evaluated on the draft tube-baffle(DTB) crystallizer operated batchwise. The crystal growth rate is proportional to the supersaturation to the 2.9 power, and the nucleation rate to the 4.2 power. The uncleation behavior for NTO-water system in DTB crystallizer was grasped according to Mersmann's criteria. The nucleation in this crystallizer was found to act with heterogeneous nucleation and surface uncleation simultaneously. Simplified relation was derived for calculation of mean crystal size of product crystals from the batch cooling crystallizer. The obtained relation was verified by a set of experiments.

• Korean Journal of Materials Research
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• v.13 no.5
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• pp.328-332
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• 2003

Characteristics of $TiO_2$nanoparticles controlled by precursor flow rate and reaction temperature in chemical vapor condensation process were interpreted in the view of decisive reaction factors, i.e. supersaturation ratio, concentration of vapor molecule, collision frequency and rate, and residence time, which directly affect the particle size and size distribution in CVC reactor. As results, the increases of precursor flow rate and reaction temperature induced the increase in the average sizes of $TiO_2$ nanoparticles in CVC reactor by acceleration of coagulation growth due to the increase of collision between $TiO_2$vapor molecules and particles. The effects of reaction factors on the characteristics of$TiO_2$nanoparticles were discussed with considering particle formation process in CVC reactor under given process parameters.

• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.44-52
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• 1997

Nephrolithiasis is the most common disorder of the urinary tract in hospitalized patients, more frequently increased in 30~50 years of age, more common in males than in females, prior right stone to left side, and than upper ureteral stone is found in cultural country, while lower ureteral stone is increased in uncultural country. Stone components are classified as calcium oxalate, calcium phosphate, magnesium ammonium phosphate, uric acid, cystine, and their mixed stone, respectively. According to the pathophysiology of urinary stones, supersaturation/crystalization of inorganic salt concentration in urine, organic matrix, inhibitor deficiency, and epitaxy theory could be based on the stone formation. Not only hypercalciuria, hyperparathyroidism, hyperoxaluria, hyperuricosuria, and cystinuria, but also renal tubular acidosis, hypervitaminosis D, and peptic ulcer, are significantly associated with nephrolithiasis. In this study upper ureteral stone component were analyzed with chemical analysis, infrared spectrum, and image analyzer from K43 patient wit erosive gastritis. As the results, mixed stone of calcium oxalate dihydrate and calcium phosphate apatite was identified, the values of clinical test in blood and urine maintained normal revels. The relapsing urinary stone from K43 have no correlation between factors for stone formation reported early, also have no evidence for risk from erosive gastritis.