• Wind and Structures
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• v.27 no.1
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• pp.11-27
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• 2018

The straight-cone steel cooling tower is a novel type of structure, which has a distinct aerodynamic distribution on the internal surface of the tower cylinder compared with conventional hyperbolic concrete cooling towers. Especially in the extreme weather conditions of strong wind and heavy rain, heavy rain also has a direct impact on aerodynamic force on the internal surface and changes the turbulence effect of pulsating wind, but existing studies mainly focus on the impact effect brought by wind-driven rain to structure surface. In addition, for the indirect air cooled cooling tower, different additional ventilation rate of shutters produces a considerable interference to air movement inside the tower and also to the action mechanism of loads. To solve the problem, a straight-cone steel cooling towerstanding 189 m high and currently being constructed is taken as the research object in this study. The algorithm for two-way coupling between wind and rain is adopted. Simulation of wind field and raindrops is performed with continuous phase and discrete phase models, respectively, under the general principles of computational fluid dynamics (CFD). Firstly, the rule of influence of 9 combinations of wind sped and rainfall intensity on flow field mechanism, the volume of wind-driven rain, additional action force of raindrops and equivalent internal pressure coefficient of the tower cylinder is analyzed. On this basis, the internal pressures of the cooling tower under the most unfavorable working condition are compared between four ventilation rates of shutters (0%, 15%, 30% and 100%). The results show that the 3D effect of equivalent internal pressure coefficient is the most significant when considering two-way coupling between wind and rain. Additional load imposed by raindrops on the internal surface of the tower accounts for an extremely small proportion of total wind load, the maximum being only 0.245%. This occurs under the combination of 20 m/s wind velocity and 200 mm/h rainfall intensity. Ventilation rate of shutters not only changes the air movement inside the tower, but also affects the accumulated amount and distribution of raindrops on the internal surface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.627-631
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• 2007

The factors affecting on sludge sedimentation are reported as F/M ratio, ingredient, composition of influent substrate, dissolved oxygen concentration, temperature, pH, filamentous bacteria and SRT. Aeration tank applying Bacillus sp. has an important role for maintaining the dominant microorganism species to make steady progress for spore growth affecting sedimentation. This research aims to investigate the affecting factor for the sedimentation in B3 system and RABC system with aeration tank applying tapered aeration. Extracellular polymeric substances(EPS), protein and carbohydrate can be produced for the extreme condition, that is down to 0.2 mg/L of dissolved oxygen in the aeration tank. This research found out the relation between the sedimentation and the EPS production, especially the ratio of protein/carbohydrate. The spore of Bacillus sp. was formed at the low DO then microorganisms produced EPS. The results showed that the production of EPS was 109.95 mgEPS/gSS at 1.6 mg/L of DO, however it was 131.77 mgEPS/gSS at 0.5 mg/L of DO. The sedimentation was affected by protein content in EPS and the ratio of protein and carbohydrate. The settleability of sludge was not affected by the ratio of protein/carbohydrate in B3 process, meanwhile settleability was affected by the ratio of it in RABC process, respectively.

• Journal of Food Hygiene and Safety
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• v.31 no.4
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• pp.294-298
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• 2016

Natural products are attractive as the source of new drug development. Especially, numerous unknown marine bioresources are an object of attention because the ocean occupies three fourth of the earth. Survival of marine bioresources in extreme environment may induce the production of biological active compounds. As previous study, we examined over 40 specimens of marine sponges collected from Micronesia and screened their anti-proliferative activities in various cancer cell lines. Among them, we investigated Coscinoderma sp.'s activity and mechanism in human colon carcinoma HCT116 and RKO cells. Furthermore, we also used the p53-knockout of HCT116 cells and the p53 loss of RKO cells for elucidating the role of p53. Coscinoderma sp. inhibited cellular viability independently of the p53 status. Therefore, we compared the expression level of cell death-related proteins by Coscinoderma sp. in HCT16 and in HCT116 p53KO cells. Coscinoderma sp. increased p53 level and NOXA levels and induced apoptosis under the condition of p53 existence. On the other hand, Coscinoderma sp. increased p21 and mTOR levels in HCT116 p53KO cells. These results suggest that Coscinoderma sp. induced anti-proliferation effect through different pathway depending on p53 status.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.135-142
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• 2015

Floating offshore structures should be designed by considering the most extreme environmental loadings which may be encountered in their design life. The most severe loading on a wave-offshore wind hybrid power generation system is wave loads. The principal parameters of wave loads are wave length, wave height and wave direction. The wave loads have different effects on the structural behavior characteristic depending on the combination of wave parameters. Therefore, the process of investigation for critical loads based on the individual wave loading parameter is need. Namely, the equivalent design wave should be derived by finding the wave condition which generates the maximum stress in entire wave conditions. Through a series of analysis, an equivalent regular wave height can be obtained which generates the same amount of the hydrodynamic loads as calculated in the response analysis. The aim of this study is the determination of equivalent design wave regarding to characteristic global hydrodynamic responses for wave-offshore wind hybrid power generation system. It will be utilized in the global structural response analysis subjected to selected design waves and this study also includes an application of global structural analysis.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1095-1099
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• 2008

In this study, we investigated that hydrate formation and phase behavior of the $THF+H_2$ binary clathrate hydrates. In order to confirm the binary clathrate hydrate formation we employed the Raman and NMR spectroscopies that are known to be quite powerful tools, particularly for examining the cage occupancy pattern of guest molecules. In addition, we traced the P-T profiles from clathrate hydrate formation and dissociation process, which made it possible for the resulting phase equilibrium boundary to be clearly established. In the binary clathrate hydrate matrix we further identified that the relatively large THF molecules can only occupy the large $5^{12}6^4$ cavities, while the small $H_2$ molecules are entrapped in the empty $5^{12}$ cavities in structure-II, making the hydrate to be stable above 273 K even at relatively low pressure condition. Considering that pure $H_2$ hydrate can be produced at the extreme pressures higher that 1,000 bar, we can conclude that the water-soluble second guest inclusion induces $H_2$ storage and transportation to be readily achievable under much milder conditions.

• Journal of the Korean Geographical Society
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• v.46 no.3
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• pp.277-290
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• 2011

Changes of the characteristics in summer rainfall in the Republic of Korea by the regime shift and their causes were examined by analyzing long-term observational data. There has been an abrupt increase in rainfall variability since 1998, which was mainly due to the enhanced rainfall during August~September, although the gradual increase was also detected in June~July. In June~July, the enhanced rainfall developed as a band type covering the whole East Asia while in August~September, it is only found over the Republic of Korea with the greatest increase of 130 mm over Seoul and Gyeonggi area. The two intensified anticyclonic anomalies over the north-northwest/east of the Republic of Korea resulted in producing northerlies/southeasterlies, transporting cold/warm-wet air flows, respectively. The center of the convergence zone from the two separate systems located in the Republic of Korea, leading to a favorable condition for the development of the extreme rainfall. The enhanced barotropic anticyclonic anomalies also affected in warming the sea surface temperature anomalies covering from the eastern coast of East Asia to North Pacific Ocean, which in turn leaded to enhance warm air transporting back to the Republic of Korea.

• Journal of Korea Water Resources Association
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• v.39 no.12 s.173
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• pp.1043-1056
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• 2006

Our ultimate purpose is to investigate the potential change in regional surface climate due to the global warming and to produce higher quality regional surface climate information over the Korean peninsula for comprehensive impact assessment. Toward this purpose, we carried out two 30-year long experiments, one for present day conditions (covering the period 1971-2000) and one for near future climate conditions (covering the period 2021-2050) with a regional climate model (RegCM3) using a one-way double-nested system. In order to obtain the confidence in a future climate projection, we first verify the model basic performance of how the reference simulation is realistic in comparison with a fairly dense observation network. We then examine the possible future changes in mean climate state as well as in the frequency and intensity of extreme climate events to be derived by difference between climate condition as a baseline and future simulated climate states with increased greenhouse gas. Emphasis in this study is placed on the high-resolution spatial/temporal aspects of the climate change scenarios under different climate settings over Korea generated by complex topography and coastlines that are relevant on a regional scale.

• Journal of the Korea Institute of Building Construction
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• v.15 no.4
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• pp.367-373
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• 2015

In this study, fundamental properties of cement were reviewed to apply high fineness cement at low temperature environment. The classified high fineness cement has large proportion of particles below $10{\mu}m$ which affects early hydration: an overall reaction of cement hydration faster. As a result of using high fineness cement, setting time of concrete was reduced and compressive strength was higher than OPC at all ages. Especially, compressive strength was more than double its value compared with OPC after three days curing in low temperature. Faster reaction and higher heat of hydration was verified by calorimetry early and maximum heat of hydration was analyzed by adiabatic temperature raising test. The analysis of this study confirmed that high fineness cement can be suitable to be used in low temperature environment.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.51-64
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• 2002

To investigate long-period wave responses in Sokcho Harbor and Cheongcho lagoon, field measurements were made for long-and short-period waves and current velocities using a Directional Waverider, a ultrasonic-type wave gauge, four pressure-type wave gauges, and a current meter. From the data analysis, it was found that the Helmholtz resonant periods of Sokcho Harbor and Cheongcho lagoon are about 13.6 and 54.5 minutes, respectively, and the dominant period of wave induced current in the passage between Sokcho Harbor and Cheongcho lagoon is about 55.2 minutes which depends on Helmholtz resonant condition of the Cheongcho lagoon. It was also found that the energy level of the far-infra-gravity waves during storm conditions is very high compared with that during calm sea conditions. To investigate relationships between far-infra-gravity waves and short-period waves at offshore station, regression analyses were carried out especially for 1) heights, 2) periods, 3) direction and height, 4) height and period between short-and far-infra-gravity waves, respectively. The results showed that the long-period wave height is highly correlated with the short-period wave height. However, no special trend was found for the other relations. In the future far-infra-gravity wave heights on return period around Sokcho Harbor region can be suggested by using extreme value analyses of long term measured data.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.38-48
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• 1980

To evaluate Rhizobium meliloti BALSAC, a strain selected from Canada as an acid tolerant one, and ordinary lucerne inoculant in acid condition, lucerne (Medicago sativa L. cv. Wairau) was inoculated and/or pelleted in the laboratory, and grown for two months in an acid soil (Lismore silt loam, pH 5.4) with three levels of lime in the, glasshouse. The results of controlled (noninoculated), nitrogen fertilized, laboratorial and commercial inoculated seeds were compared to give the following conclusions: 1. There was no significant difference in the top and root dry matter yields between two Rhizobium strains. However, Balsac inoculant showed higher single nodule dry matter weight and relatively higher number of larger nodules than the ordinary inoculant. 2. Lime application increased dry matter yields of plants and nodules, and the number of nodules per pot and the increase of nodules on the lateral roots in both inoculants. Lime application also caused an evenly distribution of nodules on the root by showing an increase of nodules mainly on the lateral roots. 3. Fertilizer nitrogen without inoculant slightly increased the nodulation percentage, the nodule dry matter weight per nodule and the relative proportion of larger nodules. 4. Commercially inoculated and pelleted seed showed less consistent results. 5. Relatively larger variations in measuring nodule characteristics was discussed and concluded that extreme cares should be given to reduce the variation.