Sargassum Fluitans 바이오매스에 의한 경금속과 수소이온의 치환반응

이학성(Hak Sung Lee),Bohumil Volesky(Bohumil Volesky) 한국화학공학회 1996 화학공학의이론과응용 Vol.2 No.1

Impact of postoperative complications on clinical and economic consequences in pancreatic surgery

Filip Čečka,Bohumil Jon,Eva Čermáková,Zdeněk Šubrt,Alexander Ferko 대한외과학회 2016 Annals of Surgical Treatment and Research(ASRT) Vol.90 No.1

Purpose: Patients who develop complications consume a disproportionately large share of available resources in surgery; therefore the attention of healthcare funders focuses on the economic impact of complications. The main objective of this work was to assess the clinical and economic impact of postoperative complications in pancreatic surgery, and furthermore to assess risk factors for increased costs. Methods: In all, 161 consecutive patients underwent pancreatic resection. The costs of the treatment were determined and analyzed. Results: The overall morbidity rate was 53.4%, and the in-hospital mortality rate was 3.7%. The median of costs for all patients without complication was 3,963 Euro, whereas the median of costs for patients with at least one complication was significantly increased at 10,670 Euro (P < 0.001). In multivariate analysis American Society of Anesthesiologists ≥ 3 (P = 0.006), multivisceral resection (P < 0.001) and any complication (P < 0.001) were independently associated with increased costs. Conclusion: Postoperative complications are associated with an increase in mortality, length of hospital stay, and hospital costs. The treatment costs increase with the severity of the postoperative complications. Those factors that are known to increase the treatment costs in pancreatic resection should be considered when planning patients for surgery

V4 between TTIP and OBOR

( Martin Riegl ),( Bohumil Dobos ),( Jan Becka ) 한국EU학회 2018 Asia-Pacific Journal of EU Studies Vol.16 No.1

The paper presents the geoeconomics and geopolitics of the two major trade proposals ― Transatlantic Trade and Investment Partnership and One Belt One Road ― from the Central European perspective. First, the Visegrad Group is presented as a loose, nevertheless significant, grouping of the four post-communist countries in Central Europe. Furthermore, it argues that both TTIP and OBOR are manifestations of the geopolitical strategies of respectively the US and the PRC. After examining the European trade strategy, the paper argues that the Visegrad 4 approach towards these proposals reflects the internal political strife rather than a coherent shift in the foreign policy orientation away from the pro- Western orientation. For the V4 countries, the economic and security ties to Western Europe and the US remain crucial, despite the growing pro-Eastern tendencies in a part of the population and political representation.

Impact of postoperative complications on clinical and economic consequences in pancreatic surgery

Filip ?e?ka,Bohumil Jon,Eva ?ermakova,Zden?k ?ubrt,Alexander Ferko 대한외과학회 2015 Annals of Surgical Treatment and Research Vol.90 No.1

Purpose: Patients who develop complications consume a disproportionately large share of available resources in surgery; therefore the attention of healthcare funders focuses on the economic impact of complications. The main objective of this work was to assess the clinical and economic impact of postoperative complications in pancreatic surgery, and furthermore to assess risk factors for increased costs. Methods: In all, 161 consecutive patients underwent pancreatic resection. The costs of the treatment were determined and analyzed. Results: The overall morbidity rate was 53.4%, and the in-hospital mortality rate was 3.7%. The median of costs for all patients without complication was 3,963 Euro, whereas the median of costs for patients with at least one complication was significantly increased at 10,670 Euro (P < 0.001). In multivariate analysis American Society of Anesthesiologists ≥ 3 (P = 0.006), multivisceral resection (P < 0.001) and any complication (P < 0.001) were independently associated with increased costs. Conclusion: Postoperative complications are associated with an increase in mortality, length of hospital stay, and hospital costs. The treatment costs increase with the severity of the postoperative complications. Those factors that are known to increase the treatment costs in pancreatic resection should be considered when planning patients for surgery.

A Numerical Model of the Temperature Field of the Cast and Solidified Ceramic Material

Frantisek Kavicka,Jana Dobrovska,Bohumil Sekanina,Karel Stransky,Josef Stetina 한국소성가공학회 2010 기타자료 Vol.2010 No.6

Corundo-baddeleyit material (CBM) ? EUCOR ? is a heat- and wear-resistant material even at extreme temperatures. This article introduces a numerical model of solidification and cooling of this material in a non-metallic mould. The model is capable of determining the total solidification time of the casting and also the place of the casting which solidifies last. Furthermore, it is possible to calculate the temperature gradient in any point and time, and also determine the local solidification time and the solidification interval of any point. The local solidification time is one of the input parameters for the cooperating model of chemical heterogeneity. This second model and its application on samples of EUCOR prove that the applied method of measurement of chemical heterogeneity provides detailed quantitative information on the material structure and makes it possible to analyse the solidification process. The analysis of this process entails statistical processing of the results of the measurements of the heterogeneity of the components of EUCOR and performs correlation of individual components during solidification. The crystallisation process seems to be very complicated, where the macro- and microscopic segregations differ significantly. The verification of both numerical models was conducted on a real cast 350 x 200 x 400 mm block.

미세조류의 이산화탄소 고정화에 미치는 이산화탄소 농도의 영향

박종문,윤영상,Volesky,Bohumil 한국화학공학회 1999 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.37 No.5

본 연구에서는 미세조류의 광합성능력을 이용하여 이산화탄소를 고정화하고자 할 때 문제점의 하나로 여겨지고 있는 고농도 이산화탄소에 대한 저해현상을 구체적으로 살펴보고자 하였다. 특히 이산화탄소의 전달계수를 구하여 미세조류가 성장하고 있는 동안 배지 내에서 용존 이산화탄소 농도의 변화를 정량적으로 이해하고자 하였으며, 용존 이산화탄소의 농도에 따른 고정화속도의 변화를 수식적으로 표현하였다. 먼저 공급되는 기체 중의 이산화탄소 부분압이 0.035%(v/v)일 경우 조류의 성장은 이산화탄소의 전달에 의하여 제한되었으며, 2%(v/v)이상에서는 제한현상은 극복될 수 있었고 용존 이산화탄소는 평형농도 부근에서 유지되었다. 그러나 혼합기체의 이산화탄소 부분압이 10%(v/v) 이상일 경우에는 용존 이산화탄소에 의하여 저해현상이 발견되었다. 이러한 저해현상을 정량적으로 기술하기 위하여 고정화속도를 용존 이산화탄소의 함수로 하는 경험식을 도입하였으며 이는 광생물반응기의 운전조건에 독립적인 것으로 폭넓은 활용이 가능할 것이다. 또한 고농도 이산화탄소에 의한 저해현상은 가역적임을 실험적으로 입증하였으며 이는 생물학적 이산화탄소 고정화 공정이 단기적인 고농도 이산화탄소에 의한 충격에 유연함을 보여주고 있다. 따라서 본 연구의 결과는 이산화탄소의 전달현상 및 농도에 따른 활성저해 현상을 이해하고 이를 수학적으로 기술함으로써 향후 광생물반응을 모델링하고 운전변수를 최적화하는데 기여할 수 있을 것으로 판단한다. Batch cultivation of Chlorella vulgaris was carried out under various CO₂concentrations in order to understand and describe mathematically the CO₂inhibition of microalgal CO₂fixation. The volumetric CO₂transfer coefficient from mixture gas to culture medium was estimated from the volumetric O₂transfer coefficient obtained experimentally. Using this transfer coefficient and aquatic equilibrium relationship between dissolved inorganic carbons, the behavior of dissolved CO₂was calculated during microalgal culture. When air containing 0.035%(v/v) CO₂was supplied into microalgal culture, the fixation rate was limited by CO₂transfer rate. However, the limitation was disappeared by supplying mixture gas containing above 2%(v/v) CO₂and the dissolved CO₂concentration was maintaind at the saturated value. In the range of CO₂partial pressure in the flue gases from thermal power stations and steel-making plants, the microalgal CO₂fixation rate was inhibited. The CO₂fixation rate was successfully formulated by a new empirical equation as a function of dissolved CO₂concentration, which could be useful for modeling and simulating the performance of photobioreaction with enriched CO₂. Also, it was found that the CO₂inhibition of microalgal CO₂fixation was reversible and that micoalgal CO₂fixation process could be stable against a shock of unusually high CO₂concentration.

Development of a Fatigue Experiment for the Stiffener-to-deck Plate Connection in Orthotropic Steel Decks

Wim Nagy,Benjin Wang,Bohumil Culek,Philippe Van Bogaert,Hans De Backer 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4

Orthotropic Steel Decks (OSDs) are widely used in long span steel bridges since they are extremely light weighted and very efficient for resisting localized traffic loads. As this type of bridge deck consists of a complex network of longitudinal and transverse stiffeners, it is very sensitive to fatigue. Moreover, there is a lack of understanding concerning the actual fatigue behaviour. Therefore, a small-scale fatigue test has been designed for which the stresses would correspond with actual OSDs. Taking into account the possibilities available in laboratory conditions, the stress distribution at the considered weld does not perfectly match when using only one longitudinal stiffener. Nevertheless, relevant test data was obtained showing the dominance of weld toe cracks. In addition, beach marks are added during the tests. As a result, more information became available about the crack propagation. This information is very helpful when using fatigue assessment tools such as fracture mechanics.

Evaluation of Aluminum and Copper Biosorption in Two-Metal System using Algal Biosorbent

Lee, Hak-Sung,Volesky, Bohumil The Korean Environmental Sciences Society 1998 Environmental sciences Vol.2 No.2

Biomass of non-living brown seaweed Sargassun fluitans pretreated with NaOH is capable of taking up more than $10\%$ $(q_{max}$ : 3.85 mmol/g for Al and 1.48 mmol/g for Cu) of its dry weight in the Al and Cu at pH of 4.5. However, the maximum Al and Cu uptakes calculated from Langmuir isotherm were 1.58 mmol/g for Al and 1.35 mmol/g for Cu at pH 3.5. Equilibrium batch sorption study was performed using two-metal system containing Al and Cu. The mathematical model of the two-metal sorption system enabled quantitative estimation of one-metal biosorption inhibition due to the influence of a second metal. NaOH-treated S. fluitans contained 2.19 mmol $(43\;wt.\%)$ carboxyl groups per gram of biomass. A modified form of Langmuir, which assumes binding of Cu as $Cu^{2+}$ and Al as $Al(OH)_2^+,$ was used to model the experimental data. This result agrees with the one of mono-valent sorption for Al in single-metal system. The modified Langmuir model gives the following affinity correlated coefficients: 0.196 for Cu and 6.820 for Ah at pH 4.5, and 2.904 for Cu and 3.131 for Al at pH 3.5. The interference of Al in Cu biosorptive uptake was assessed by `cutting' the three dimensional uptake isotherm surfaces at constant second-metal final concentrations. Equimolar final equilibrium concentrations of Cu and Al of 1 mM at pH 4.5 give Cu and hi uptakes reduced by $82.5\%\;and\;5.4\%,$ respectively. However, these values at pH 3.5 were $55\%\;(Cu)\;and\;31\%$ (Al).

Numerical Optimization of the Method of Cooling of a Massive Casting of Ductile Cast-Iron

Jana Dobrovska,Frantisek Kavicka,Karel Stransky,Bohumil Sekanina,Josef Stetina 한국소성가공학회 2010 기타자료 Vol.2010 No.6

The numerical models of the temperature field of solidifying castings, according to various authors, have been observing two main goals ? directed solidification as the basic assumption for the healthiness of a casting and the optimization of the technology while maintaining the optimal product properties. The achievement of these goals is conditioned by the ability to analyze and, successively, to control the effect of the deciding factors, which either characterize the process or accompany it. An original application of ANSYS simulated the forming of the temperature field of a massive casting from ductile cast-iron during the application various methods of its cooling using steel chills. The numerical model managed to optimize more than one method of cooling but, in addition to that, provided serious results for the successive model of structural and chemical heterogeneity, and so it also contributes to influencing the pouring structure. The file containing the acquired results from both models, as well as from their organic unification, brings new and, simultaneously, remarkable findings of causal relationships between the structural and chemical heterogeneity (i.e. between the sizes of the spheroids of graphite, the cells, density of the spheroids of graphite, etc.) and the local solidification time in any point of the casting. The determined relations therefore enable the prediction of the face density of the spheroids of graphite in dependence on the local solidification time. The calculated temperature field of a two-ton 500x500x1000 mm casting of ductile cast-iron with various methods of cooling has successfully been compared with temperatures obtained experimentally. The casting was cast in sand mould. The calculated model of the kinetics of the temperature field of the casting was verified during casting with temperature measurements in selected points.This has created a tool for the optimization of the structure with an even distribution of the spheroids of graphite in such a way so as to minimize the occurrence of degenerated shapes of graphite, which happens to be one of the conditions for achieving good mechanical properties of castings of ductile cast-iron.

조류배양을 통한 이산화탄소 및 암모니아의 동시처리

윤영상(Yeong-Sang Yun),박종문(Jong Moon Park),Bohumil Volesky 한국생물공학회 1999 KSBB Journal Vol.14 No.3