• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.129-137
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• 1999

The time of the onset of double-diffusive convection in time-dependent, nonlinear concentration fields is investigated theoretically. The initially quiescent horizontal fluid layer with a uniform temperature gradient experiences a sudden concentration change from below, but its stable thermal stratification affects concentration effects in such way to invoke convective motion. The related stability analysis, including Soret effect, is conducted on the basis of the propagation theory. Under the linear stability theory the concentration penetration depth is used as a length scaling factor, and the similarity transform for the linearized perturbation equations. The newlly obtained stability equations are solved numerically. The resulting critical time to mark the onset of regular cells are obtained as a function of the thermal Rayleigh number, the solute Rayleigh number, and the Soret effect coefficient. For a certain value of the Soret effect coefficient, the stable thermal gradient promote double-diffusive convective motion.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.9-19
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• 2001

contrasting monsoon between 1993 and 1994 produced an interannual difference in hydrology. Theoretical water residence time (TWRT) in monsoon 1993 averaged 27 d, which was>3 months shorter compared to the TWRT in monsoon 1994. A dominant physical process influencing thermal stratification, water movement, and mixing regime was an interflow current in 1993. During summer 1993, river water plunged to mid-lake (location 27 km) and passed through the 10${\sim}$20m stratum of the reservoir, resulting in an isolation of epilimnetic lake water from advected river water. The interflow disrupted thermal stratification and produced a meta-hypolimnetic warming of >4$^{\circ}C$ downlake, thereby increased a mixing depth (>13 m). In contrast, during monsoon 1994 density currents were not observed and strong thermal stratification occurred in the entire reservoir, resulting in > 2 fold greater thermal resistance (8.2${\times}10^{5}$ erg)compared to 1993 (4.0${\times}10^{5}$ erg). This reservoir was identified as a typical warm monomictic reservoir which showed one mixis during early winter. The timing of overturn, however, differed between the two years as a result of distinct contrast in TWRT and thermal regime; overturn in 1993 occured about one month earlier relative to that in 1994. Hypolimnetic warming was predictable in this system; the variation in discharge accounted (Y = 4.35-0.06X+0.10X$^{2}$, p<0.0001)for 98% of the interannual variation in hypolimnetic temperature. Overall data suggest that thermal stability, the timing of fall overturn, and water residence time in this system are primarily regulated by the intensity of monsoon.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.656-664
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• 2001

A theoretical analysis is performed to describe the qualitative behavior of transient buoyant flows in a vertical channel. Consideration is given to the case of a fluid with a pre-existing stratification. The fluid motion is generated by giving impulsive anti-symmetric step-changes in temperature at the vertical left ad right sidewalls. The qualitative character of the flow is shown to be classified in the Rayleigh number (Ra)-Prandtl number ($sigma$) diagram. The transitory approach to the steady state can be monotonic or oscillatory, depending on ($sigma$-1)$^2$$pi$$^4$ 4$sigma$$R_a$. The prominent characteristics of time-dependent flow are discussed for large $R_a$. The profiles of temperature and velocity in the transient phase are depicted, which disclose distinctive time scales of motion. The transient process is shown to be sensitive to the Prandtl number. The detailed evolutions of flow and temperature fields are illustrated for large $R_a$.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.552-557
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• 1998

Sampling schemes are intended for use in situations where stream-flow data are collected regularly, but concentration data are collected during only a limited number of time periods. Estimating water pollutant loading considering sampling intervals is presented, and for illustrative purposes the criterion is applied to the sampling station HS#3 of the Balan-reservoir watershed which is located at the southwest of Suwon. The stratification is employed uniformly for all sampling strategies in that the strata boundaries are defined using the actual distribution of flow values and the selected nonexceedence probabilities to minimize inaccuracy. Ratio estimator for SS, T-N, and T-P were used in order to calculate the water pollutant loading. A sampling scheme incorporating stratified sampling with real-time of the sampling characteristics is found to give the appropriate estimate of the mass load.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.511-525
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• 2014

Goal of this study is estimating of validity of calculated vertical diffusion coefficient for Masan bay is semi-enclosed bay by using eco-hydrodynamic model that is used to analysis of physical structure of coastal waters and calculates the vertical diffusion coefficient. physical structure of coastal waters is calculated by EFDC model, vertical diffusion coefficient calculated as the density gradient is bigger, the vertical diffusion coefficient as density gradient is increases, the vertical diffusion coefficient is decreased. Validity of vertical diffusion coefficient estimated by reproducibility of concentration of dissolved oxygen that calculated in ecosystem model is constructed by Stella program. The Results of model in 2008~2009 were $R^2$ value of 2008 is 0.529~0.700 and $R^2$ value is 0.542~0.791. This results were similar to observed data and simulated to hypoxia at that time. The 'vertical diffusion coefficient' represents stratification and physical stable of a water body, and will be useful for prediction of Hypoxia outbreak.

• Korean Journal of Plant Resources
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• v.35 no.1
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• pp.36-43
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• 2022

This research was conducted to develop a seed propagation protocol for the use of Broussonetia kazinoki Siebold ex Siebold & Zucc, which native to East Asia. Light and temperature conditions, GA₃ treatment, and low-temperature stratification were performed to evaluate the germination characteristics. The germination percentage at 4, 15/6, 20/10 and 25/15℃ was 0, 42. 5, 44. 4 and 91.7%, respectively. Thus, the optimal germination temperature of the B. kazinoki seeds was 25/15℃. Although germination was delayed by relatively low temperature conditions, GA3 treatment allowed for increased germination rates even under the low temperature conditions. Cold stratification reduced time to germination. Relatively low germination percentages at 20/10℃ and 15/6℃ indicated that the seeds had been under the state of conditional dormancy. Through this study, B. kazinoki seeds have conditional dormancy because they can be germinated through GA₃ treatment even under relatively low temperature conditions and it is judged that it will support the commercial propagation practice in the future.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.3
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• pp.231-239
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• 1999

In oral and maxillofacial surgery, there are many cases requiring the graft of epidermal tissues such as maxillectomy, and vestibuloplasty. There have been so many challenges for the culture of the epidermal tissue. Observing the ultrastructure of the cultured human oral kertinocytes, we could compare this findings with that of in vivo ones. With that, we could find the differencies and similarities between cultured cells and in vivo ones, and evaluate the clinical applications of cultured tissue. Human gingiva was obtained and the specimen was explanted on 24-well plate. Two types of culture media were used in this culture system. One was for the growth of the keratinocytes (Media I), and the other was for the stratification (Media II). Media I had special ingredients for the epidermal growth. Those were 0.5% dimethyl sulfoxide (DMSO), 30ng/ml of epidermal growth factor (EGF), 30ng/ml of cholera toxin, and $5{\mu}g/ml$ of transferrin. We cultured the oral keratinocytes for 3 weeks, and at that time the cultured keratinocytes were processed to prepare the specimen for the TEM study. The results were as follows.; 1. In the phase contrast micrograph, epidermal outgrowth firstly appeared on the 3rd day after explantation, and the growing keratinocytes were activley mitotic, and had polygonal shape and increased N/C ratio. 2. In the phase contrast micrograph, the outer most cells exhibited areas where broad cytoplasmic processes extended out onto the culture subtratum(fan-like appaearance). 3. In the TEM micrographs, the cultured keratinocytes showed stratification. The cells were in elongated form, and there were no morphologic differencies among the layers usually found in the in vivo gingiva. 4. Most of cellular organelles underwent lysis, and keratohyaline granules were seen. Tonofibrils were dispersed in the cytoplasm. 5. The cells were interconnected by desmosomes, and their frequency of distribution was considered to be lower than that of in vivo keratinocytes. 6. We could conclude the cultured oral keratinocytes exhibited signs of terminal differentiation.

• Korean Journal of Plant Resources
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• v.27 no.3
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• pp.263-270
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• 2014

Loranthus tanakae (Franch. & Sav.) is an endangered species of mistletoe, distributed in Korean peninsula. The objective of our research is to determine the effect of storage duration and conditions [air flow (AF) and air tight (AT)] at different temperatures for survivability and germination of mistletoe seeds, and also to monitor the effect of seed scarification on germination in vitro. The result revealed that the seeds stored in natural conditions (no stratification) showed highest survival rate of 100% and retained up to 93.3% even after two months of storage in natural conditions and showed higher germination percentage (90%) compare to after ripened seeds. However, the seed stored at $0^{\circ}C$ decreased the germination percentage (ranged from 63 to 73%). Therefore, it can be confirmed that mistletoe does not need after ripened treatment to promote germination. Our research also showed that the storage of L. tanaka seeds in freezing temperatures of $-20^{\circ}C$ and in room temperature for long time either in AT or AF conditions caused the loss of survival and germination rate. On the other hand, the chemical scarification (0.01N HCl incubation for 12 hrs. at $38^{\circ}C$) method was proven more effective to enhance germination percentage of L. tanakae. Regarding the temperature regime, $22^{\circ}C$ showed early germination of mistletoe seeds in vitro.

• Biomedical Science Letters
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• v.22 no.1
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• pp.9-17
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• 2016

Unfortunately, the five-year survival rate of lung cancer is relatively low compared with other cancers. Therefore, better predictors are need for prognosis, therapeutic strategy, risk stratification and predicting long-term mortality of lung cancer. Recently, increasing data suggest that Glasgow Prognostic Score (GPS) and procalcitonin levels are useful predictor cancer prognosis. In this study, we retrospectively investigated the correlation of GPS or procalcitonin to clinical variables in patients with pretreatment lung cancer. In 135 patients with pretreatment lung cancer, GPS, procalcitonin, demographic characteristics, hematological, coagulation, biochemical, inflammatory and cardiac markers were measured. Monocyte, eosinophil, basophil, neutrophil to lymphocyte ratio, red cell distribution width (RDW), platelet to lymphocyte ratio, mean platelet volume to platecrit ratio, D-dimer and prothrombin time (PT) levels were higher, whereas mean platelet volume was lower than their normal ranges. Glucose and sodium levels were low, whereas gamma glutamyl transferase (GGT), total bilirubin, creatinine and inorganic phosphorus concentrations were increase compared their normal ranges. Procalcitonin, high sensitivity C-reactive protein and troponin-I concentrations were elevated compared with their normal ranges. GPS had significantly positive or negative relations to cancer stage, hematological, coagulation, biochemical, inflammatory and troponin-I. Based on the data, we suggest that GPS may be a potent and useful predictor for prognosis, therapeutic strategy, risk stratification and predicting long-term mortality of lung cancer.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1514-1524
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• 2019

Hydrogen-steam gas mixture may be injected into containment with flow regime varying both spatially and transiently due to wall effect and pressure difference between primary loop and containment in severe accidents induced by loss of coolant accident. Preliminary CFD analysis is conducted to gain information about the helium flow regime transition process from jet to buoyancy plume for forthcoming experimental study. Physical models of impinging jet and wall condensation are validated using separated effect experimental data, firstly. Then helium transportation is analyzed with the effect of jet momentum, buoyancy and wall cooling discussed. Result shows that helium distribution is totally dominated by impinging jet in the beginning, high concentration appears near gas source and wall where jet momentum is strong. With the jet weakening, stable light gas layer without recirculating eddy is established by buoyancy. Transient reversed helium distribution appears due to natural convection resulted from wall cooling, which delays the stratification. It is necessary to concern about hydrogen accumulation in lower space under the containment external cooling strategy. From the perspective of experiment design, measurement point should be set at the height of connecting pipe and near the wall for stratification stability criterion and impinging jet modelling validation.