• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1741-1751
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• 2004

It is commonly requested that the steam generator tubes wall-thinned in excess of 40% should be plugged. However, the plugging criterion is known to be too conservative for some locations and types of defects and its application is limited to a single crack in spite of the fact that the occurrence of multiple through-wall cracks is more common in general. The objective of this research is to propose the optimum failure prediction models for two adjacent through-wall cracks in steam generator tubes. The conservatism of the present plugging criteria was reviewed using the existing failure prediction models for a single crack, and six new failure prediction models for multiple through-wall cracks have been introduced. Then, in order to determine the optimum ones among these new local or global failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two adjacent through-wall cracks in thin plate were carried out. Thereby, the reaction force model, plastic zone contact model and COD (Crack-Opening Displacement) base model were selected as the optimum ones for assessment of steam generator tubes with multiple through-wall cracks. The selected optimum failure prediction models, finally, were used to estimate the coalescence pressure of two adjacent through-wall cracks in steam generator tubes.

• Journal of Korea Port Economic Association
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• v.32 no.3
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• pp.139-154
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• 2016

The port incentive scheme currently implemented in various Korean ports is used as a marketing tool to increase price competitiveness. Typically, ports implement piecemeal imitation strategies to enhance their competitiveness, rather than a precisely designed system. A precise analysis of the effectiveness of a port's system and scheme redesign are lacking because budget allocation is done without input from customers and freight groups. This study models the incentives faced by ports using a linear programming model. We use the Gwangyang port as the base case. Our analysis of the Gwangyang port reveals that there are insufficient incentives implemented when a traditional qualitative analysis is used. We also identify any excess, deficiency, or absence of the incentive effect for each type of customer and freight group. We find the overall budget of the incentive scheme to be more rational when ports allocate funds to minimize port mileage, and allocate 61.77 percent and 38.23 percent of the budget on existing and new (or increased) cargo inventory, respectively. Future studies can build on our work by further considering basic inputs, and by adding a system to estimate the input data of our model to identify constraints and thus provide a more accurate incentive scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.41-46
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• 2018

In this research, numerical analysis was performed to determine the effects of hydrogen on biogas combustion for homogeneous charged compression ignition (HCCI) engines. The target engine specifications were a 2300cc displacement volume, 13:1 compression ratio, 15kW of electricity, and 1.2 bar boost pressure. The engine speed was fixed to 1800rpm. By varying the excess air ratio and hydrogen contents, the cylinder pressure, nitric oxide, and carbon dioxide were measured as a function of the hydrogen contents. According to preliminary studies related to the reaction mechanism for methane combustion and oxidation, a GRI 3.0 mechanism as the base mechanism was selected for HCCI combustion calculations describing the detailed reaction mechanism. By adding hydrogen, NO was increased while $CO_2$ was decreased. The cylinder pressure was also increased, having advanced timing for the maximum cylinder pressure and pressure rise region. Furthermore, lean operation limits were extended by adding hydrogen to the HCCI engine.

• Journal of Veterinary Science
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• v.25 no.3
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• pp.38.1-38.16
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• 2024

Importance: Deaths due to neonatal calf diarrhea are still one of the most critical problems of cattle breeding worldwide. Determining the parameters that can predict diarrhea-related deaths in calves is especially important in terms of prognosis and treatment strategies for the disease. Objective: The primary purpose of this study was to determine mortality rates and durations, survival status, and predictive prognosis parameters based on vital signs, hematology, and blood gas analyses in neonatal diarrheic calves. Methods: The hospital automation system retrospectively obtained data from 89 neonatal diarrheic calves. Results: It was found that 42.7% (38/89) of the calves brought with the complaint of diarrhea died during hospitalization or after discharge. Short-term and long-term fatalities were a median of 9.25 hours and a median of 51.50 hours, respectively. When the data obtained from this study is evaluated, body temperature (℃), pH, base excess (mmol/L), and sodium bicarbonate (mmol/L) parameters were found to be lower, and hemoglobin (g/dL), hematocrit (%), lactate (mmol/L), chloride (mmol/L), sodium (mmol/L) and anion gap (mmol/L) parameters were found to be higher in dead calves compared to survivors. Accordingly, hypothermia, metabolic acidosis, and dehydration findings were seen as clinical conditions that should be considered. Logistic regression analysis showed that lactate (odds ratio, 1.429) and CI^- (odds ratio, 1.232) concentration were significant risk factors associated with death in calves with diarrhea. Conclusions and Relevance: According to the findings obtained from this study, the determination of lactate and Cl^- levels can be used as an adjunctive supplementary test in distinguishing calves with diarrhea with a good prognosis.

• Korean Journal of Veterinary Research
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• v.12 no.1
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• pp.25-35
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• 1972

The author used a dog preparation, in which either the left lung or the lower left lobe rebreathed continuously from a bag, to compare $CO_2$ and $O_2$ tensions in the rebreathed gas with those in blood entering or leaving the lung. In the 10 dogs studied, alveolar pressures for both gases were greater than in the blood; the "upstream" gradient (alveolar pulmonary arterial blood) exceeded the "downstream" gradient (alveolar-pulmonary venous blood) for both gases, but the difference was only significant for $CO_2$. The author attributed this effect to the production of $CO_2$ in lung tissue metabolism and its uptake by the blood. The difference in $CO_2$ tension between blood leaving and entering lung increased while the downstream gradient fell, an effect which was independant of the level of anesthesia. There was no evidence of a fall in base excess in blood passing through the lung, as would occur from the production of metabolic acids during anaerobic metabolism at the low levels found in the rebreathing lung in this preparation.

• Clinical and Experimental Pediatrics
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• v.48 no.6
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• pp.649-654
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• 2005

Purpose : The present study examined how changes in cerebral hemodynamics in newborn piglets with bilirubin infusion can be evaluated by near infrared sepctroscopy(NIRS). Methods : Seventeen newborn piglets were randomly divided into the following three experimental groups : six in the control group(CG); seven in the bilirubin infusion group(BG), and four in the bilirubin infusion with 7-nitroindazole group(NG). To achieve the concentration of bilirubin above 20 mg/dL, we injected a bolus of 40 mg/kg of bilirubin intravenously, followed by 30 mg/kg/hr of bilirubin continuous intravenous infusion. All groups were monitored with cerebral hemodynamics using near infrared spectroscopy(NIRS) and their brain cortexes were harvested and the activities of $Na^+$, $K^+$-ATPase, level of conjugated dienes, ATP and phosphocreatine(PCr) were determined biochemically. Results : No changes took place in CG. In BG and NG, base excess, pH, and MABP decreased, and lactate level in blood increased. Cerebral $Na^+$, $K^+$-ATPase activity and ATP, PCr level in BG significantly decreased and conjugated dienes increased compared to CG. These abnormalities observed in the BG were significantly improved in the NG. In continuous NIRS monitoring, [$HbO_2$], [HbT], and [HbD] in BG were significantlly decreased compared to CG. However these abnormalities between NG and CG were not significantly different. There were no significant differences in $ScO_2$ between the study groups. Conclusion : Our study suggests cerebral hemodynamic changes could be monitored by non-invasive NIRS in newborn piglets with bilirubin infusion.

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.25-38
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• 1996

To investigate the stability problem of irrigation-drainage channel excavation slope on soft ground, analyzed the behavior of the soft ground with excavation slope by the limit equilibrium method and the finite element method, and compared with field tests. The results of this study were summarized as follows; 1. When rapid drawdown the water level, the crack was occurred by the effect of the excess pore water pressure, and the pore water pressure was decreased slowly. 2. As the width of excavation was larger, the crack width was larger. And, excavated depth was deeper, the progressive failure was appeared. 3. When the soft ground excavation was small-scale, the minimum safety factor was more effected by cohesion(1.0, 1.5, 2.0, 2.5, 3.0) than excavated slope inclination(1:l, 1:1.5, 1:2). 4. As excavation was progressed, the settlement occurred on the top-slope due to plastic domain, and heaving was occurred at the bottom of excavation. 5. The maximum shear stress was appeared greatly as the base part of slope went down. Because of the increase of the maximum shear stress, tension area occurred and local failure possibility was increased. 6. As the excavation depth was increased, the maximum shear strain was appeared greatly at the base of slope and distribution pattern was concentrated beneath the middle of slope.

• KSBB Journal
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• v.19 no.3
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• pp.215-220
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• 2004

A variety of solid bases such as inorganic bases, basic anion exchange resins, and resin-bound bases were tested as a catalyst for racemization of (S)-naproxen 2,2,2-trifluoroethyl thioester in isooctane at 45$^{\circ}C$. Among the various bases, DIAIOM WA30, which is a weakly basic anion exchange resin with a tertiary amine based on a highly porous type styrene-divinylbenzene copolymer, showed the highest catalytic activity. The second-order interconversion constant of DIAION WA30 was 8.6${\times}$10$\^$-4/ mM$\^$-1/h$\^$-1/ and about 3 times higher than that of trioctylamine under the same conditions. The rate of DIAION WA30-catalyzed racemization decreased with increasing an amount of water added to the reaction medium. Lipase-catalyzed kinetic resolution of racemic naproxen 2,2,2-trifluoroethyl thioester was successfully carried out under in situ racemization of substrate with DIAION WA30 in isooctane at 45$^{\circ}C$. More than 60% conversion and 99% enantiomeric excess for the desired (S)-naproxen product were obtained. Furthermore, such a solid base catalyst could be easily separated and reused in contrast to trioctylamine.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.3
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• pp.304-311
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• 2014

In this study, to apply hydrogen energy to ship engine and to generate effective hydrogen production, we investigated the effects of high temperature $H_2SO_4$ feed rate and cooling water rate to pump parts with fixed frequency needed to reciprocate motion and a simulation was conducted at each condition. In the fixed frequency and cooling water inlet flow rate of 0.5 Hz and 3.9 kg/s, we changed the high temperature $H_2SO_4$ flow rate to 47.46 kg/s (it is 105 % of 45.2 kg/s), 49.72 kg/s (110 %), and 51.98 kg/s (115 %). Also, at 0.5 Hz and 45.2 kg/s of frequency and high temperature $H_2SO_4$ flow, the thermal hydraulic analysis was performed at the condition of 95 % (3.705 kg/s), 90 % (3.51 kg/s), and 85 % (3.315 kg/s). In overall simulation cases, the physical properties of materials are more influential to the temperature increase in the pump part rather than the changes on the feed rate of high temperature $H_2SO_4$ and cooling water. A continuous operation of pump was also capable even if the excess feed of high temperature $H_2SO_4$ of about 15 % or the less feed of cooling water of about 15 % were performed, respectively. When the increasing feed of high temperature $H_2SO_4$ of up to 5 %, 10 %, and 15 % were compared with base flow (45.2 kg/s), the deviation of time period rose to a certain temperature and ranged from 0 to 4.5 s in the same position (same material). In case of cooling water, the deviation of time period rose to a certain temperature and ranged from 0 to 5.9 s according to the decreasing feed changes of cooling water at 5 %, 10 %, and 15 % compared to a base flow (3.9 kg/s). Finally, the additional researches related to the two different materials (Teflon and STS for Pitch and End-plate), which are concerned about the effects of temperature changes to the parts contacting different materials, are needed, and we have a plan to conduct a follow-up study.

• Journal of Yeungnam Medical Science
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• v.6 no.1
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• pp.121-131
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• 1989

The temperature-corrected values of blood gas analysis were compared to uncorrected values in 40 cases of open heart surgery under moderate hypothermic cardiopulmonary bypass. The results were as follows. 1. The corrected value of pH was significantly higher than uncorrected value, and it's relationship was ${\Delta}pH=-0.015$ ${\Delta}Temp+0.005$(r=0.81, P<(0.01). 2. The corrected value of $PCO_2$ was lower than uncorrected value, and it's relationship was ${\Delta}PCO_2=1.11$ ${\Delta}Temp+1.81$(r=0.50, P<0.01). 3. The corrected value of $PO_2$ was lower than uncorrected value, and it' s relationship was ${\Delta}PO_2=5.21$ ${\Delta}Temp-1.45$(r=0.32, P<0.01). But there was no clinical significance. 4. The corrected values of $HCO_{3^-}$, base excess, $CO_2$ content and oxygen saturation were similar with uncorrected values. In summery, the values of pH and $PCO_2$were significantly changed by temperature-correction. Because of the neutral point of water (pH=pOH) rises as temperature falls and it change in parallel with the changes in blood pH, a corrected pH of 7.4, $PaCO_2$ of 40mmHg during deep hypothermia would reflect a profound respiratory acidosis. Therefore, the use of the uncorrected value at $37^{\circ}C$ is more preferable and valid means of assessing acid-base management regardless of actual patient temperature.