• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.250-255
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• 1993

A dual capillary column system is described for the simultaneous analysis of a given sample and measurement of retention index (RI) and area ratio (AR) values of each peak on two capillary columns of different polarity, DB-5 & DB-1701 from a single injection. Both capillary columns were connected to either a splitless injector or an on-column injector via a deactivated fused-silica capillary tubing of 1 m length and a 'Y' splitter. Both injection modes allowed to measure RI and AR values with high reproducibility (<0.01% RSD) and high accuracy (<10% RE), respectively with the exception that the trace and high boiling solutes required the on-column mode for the accurate quantification and AR comparison. When the dual capillary column system in on-column injection mode was applied to the blind samples containing organic acids, each acid was positively indentified by the combined computer RI library search-AR comparison.

• Journal of Chest Surgery
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• v.56 no.5
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• pp.362-366
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• 2023

The stomach has become the most commonly used site for grafts to replace the esophagus in esophageal cancer surgery because of its good blood supply and ability to enable single-reconstruction anastomosis. However, anastomotic failure is a serious complication after esophageal cancer surgery. Unlike anastomotic leakage due to local ischemia, gastric tube necrosis is a life-threatening condition with a high mortality rate. Gastric tube necrosis involves extensive ischemia due to a decreased blood supply, and an urgent operation is mandatory in most cases. Endoscopic vacuum therapy (EVT) has been used for anastomotic leakage after esophageal surgery. In recent years, it has been successfully used for more extensive disease, including large esophageal perforation as an indication for reoperation. Hence, we report a case of extensive gastric tube necrosis treated by EVT after an Ivor Lewis operation.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.1
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• pp.56-63
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• 2021

The feedwater ring is an assembly in steam generator internal piping, which distributes feedwater into the secondary side of the steam generator. It consists of an assembly of carbon steel piping, pipe fittings and J-nozzles which are inserted into the top of the feedwater ring and welded to the diameter of the ring. The feedwater ring at the attachment region of the J-nozzle may be susceptible to flow accelerated corrosion (FAC) due to flow turbulence which increases local fluid velocities. If a J-nozzle becomes a loose part, it can cause damage to tubing near the tube sheet. In this paper, the structural stress analysis for a wall thinned feedwater ring and integrity evaluations under assumed loading conditions are carried out in compliance with ASME B&PV SecIII, NB-3200.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1118-1124
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• 2023

Experimental study on the fluidelastic instability (FEI) of a curved tube bundle in single phase downward cross flow is investigated for the design qualification and analysis input preparation of helical coiled steam generator tubing. A 6×9 normal square curved tube array with equal and different vertical/horizontal pitch-to-diameter ratio was under-tested up to 6 m/s in term of gap flow velocity to measure the critical velocity for FEI. The critical velocity for FEI was measured at the turning point from the vibration amplitude plot along the gap flow velocity. Our test results were compared with straight tube results and published data in the design guideline. The applicability of the current design guidelines to a curved tube bundle is also assessed. We found that introducing frequency difference in a curved tube array increases the critical velocity for fluidelastic instability.

• Journal of Yeungnam Medical Science
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• v.40 no.2
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• pp.123-135
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• 2023

Advances in perinatal and pediatric intensive care and recent advances in mechanical ventilation during the last two decades have resulted in an exponential increase in the number of children undergoing home mechanical ventilation (HMV) treatment. Although its efficacy in chronic respiratory failure is well established, HMV in children is more complex than that in adults, and there are more considerations. This review outlines clinical considerations for HMV in children. The goal of HMV in children is not only to correct alveolar hypoventilation but also to maximize development as much as possible. The modes of ventilation and ventilator settings, including ventilation masks, tubing, circuits, humidification, and ventilator parameters, should be tailored to the patient's individual characteristics. To ensure effective HMV, education for the parent and caregiver is important. HMV continues to change the scope of treatment for chronic respiratory failure in children in that it decreases respiratory morbidity and prolongs life spans. Further studies on this topic with larger scale and systemic approach are required to ensure the better outcomes in this population.

• Journal of Chest Surgery
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• v.30 no.10
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• pp.991-1000
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• 1997

Closed thoracostomy with UWSD* which is the most utilized procedure in chest surgery applies general thoracic disorders, trauma and after-thoracic surgery. The University hospital was involved on operating 2341 cases of closed thoracostomy with UWSD except chest tubing after-thoracic surgery for a full six years from January, 1991 to December, 1996. The rate of men and women out of the total 2341 cases was 3.5 : 1, the distribution by age showed that men were 36.6 $\pm21.0$ years old, women were $47.0\pm20.2$ years old and so that the total were 40.0 $\pm$ 20.5 years old. As for indication, spontaneous, secondary and traumatic pneumothorax were the most common, in addition to hemothorax hemopneumothorax, hydrothorax, hydropneumothorax, empyema, chylothorax. The most indwelling period of chest tubing is between eight and fourteen days for 974 cases and the average is 13.7 $\pm$ 6.3 days, The average drainage amount immediately after thoracostomy was 537 $\pm$ 88m1, and in 694 cases(46.0%), the drain amount was 201 ~ 500 ml. The rate of right and left tubing was 52.4 47.6, in 2071 cases(88.5%), the thoracostomy was the first chance and 2210 cases(94.4%) were treated with a single tube drainage. Almost all the patients complained of tube site pain, besides tube site infection, intercostal neuralgia, loss of tube function by the pleural adhesion, intrathoracic infection, incomplete reexpansion of defective lung, hemorrhage caused by the rupture of a blood vessel, subcutaneous emphysema, lung parenchymal rupture, diaphragmatic and intraabdominal trauma, reexpansionary pulmonary edema of one side lung and cellulitis were relapsed. 84.6% of all patients recovered with only clo ed thoracostomy and the rest of patient needed additional some necessary managements and so on to have successful results. There were two deaths(0.1%), caused by reexpansionary pulmonary edema, the cellulitis were complicated by thoracostomy with UWSD on an empyema patients to come to death(due to sepsis). t UWSD = under water seal drainage

• The Korean Journal of Physiology
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• v.7 no.1
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• pp.23-31
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• 1973

Numerous factors concern with the absorption of substances through the membrane of the gastrointestinal tract. To simplify the experimental condition, present work has been restricted to observe the disappearance rate of substance from the intestinal loop which was made in the jejunum, 70 cm apart from the pylorus of the adult rabbit. The purpose of the study is to clarify the absorption of urea through the jejunal wall is solely attributable to the concentration difference between the luminal fluid and plasma, and to observe the effect of adding red pepper upon the rate of absorption. The rabbits were anesthetized with nembutal, 35mg/kg I.V. Jejunal loop was made by ligating at 2 spots, 70 cm and 80cm apart from the pylorus. After rinsing with normal saline solution through the polyethylene tubing inserted from the end of the loop, 8 ml of test solution was placed through the same tubing. The test solution contained 200 mg% of urea and 150mg% of polyethylene glycol(M.W. 4,000) in normal saline solution. Right after placing the test solution the first specimen was taken through the tubing, and successive samplings were performed at 5, 10, 20, and 30 minutes. Logarithm of the difference of urea concentration between the luminal fluid and plasma was plotted against time elapsed after the onset of the experiment. If straight line is revealed, it would verify the nature of transport mechanism as diffusion, obeying the Fick's principle. The concentration of polyethylene glycol (PEG) was also measured in order to examine the change in the volume. PEG was used as the marker substance because it is not absorbable in the intestinal tract. Consequently the concentration of PEG relates inversely to the volume of the loop. Instantaneous concentration of urea in the loop times the volume will give the amount of urea remaining in the luminal fluid. The change in the amount of any substance is directly relate to the volume of the compartment and differs from the change in the concentration which is independent of the volume. After completion of the experiment without red pepper, it was added in the test solution and was centrifuged after thorough mixing. Supernatant of the mixture was placed in the loop and similar sampling were performed with the same time intervals that of previous run in order to observe the effects of the red pepper on the passive transport of the water soluble small substance, urea. The results obtained were as follows: 1. Logarithm of the concentration difference of urea between the luminal fluid and plasma was diminished exponentially as time elapsed. The decay constant in the experiment without red pepper was 0.0563/min. By adding red pepper in the test solution as much as the concentration rose to 4,000 mg% and 8,000 mg%, the decay constants were lowered to 0.0493/min and to 0.0506/min, respectively. The time interval by which the concentration difference dropped to one half of the initial value was prolonged. Without red pepper the half concentration time was 13.30 minutes, and by adding extract of red pepper, 15.31 minutes and 15.71 minutes were revealed. 2. The profile of the diminishing rate of tile amount of urea was quite different from that of the concentration because of the change in the volume of the loop during the observed period. 3. By adding the extract of red pepper, it slowed down the rate of absorption of urea in the intestinal loop, suggesting an increase in the diffusional barrier. 4. Larger dosage of red pepper brought an increase in the secretion of intestinal fluid with concomitant expansion of the luminal volume, and the retardation of the absorption of urea was noticed. This effect was largely dependent on the sensitivity of the individual animal to the red pepper, extract. The amount of urea remained after 10 minutes interval was 55.5% of the initial amount in the experiment without red pepper. On the other hand it was not consistent after administration of red pepper, showing 50.6% and 66.5% of the initial figures by adding 400 mg and 800 mg of red pepper in the test solution, respectively. It was postulated that symptom of diarrhea often encountered by taking a hot (red pepper) food might be attributable to the increase of secretion and the retardation of absorption in the intestinal tract.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.740-745
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• 2015

This study investigated the effect of different collection methods on physical properties of pectin hydrogels in microfluidic synthetic approach. The pectin hydrogels were simply produced by the incorporation of calcium ions dissolved in continuous mineral oil. Then, different collection methods, pipetting, tubing, and settling, for harvesting pectin hydrogels were applied. The settling method showed most uniform and monodispersed hydrogels. In the case of settling, a coefficient of variation was 3.46 which was lower than pipetting method (18.60) and tubing method (14.76). Under the settling method, we could control the size of hydrogels, ranging from $30{\mu}m$ to $180{\mu}m$, by simple manipulation of the viscosity of pectin and volumetric flow rate of dispersed and continuous phase. Finally, according to the characteristics of simple encapsulation of biological materials, we envision that the pectin hydrogels can be applied to drug delivery, food, and biocompatible materials.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.183-183
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• 2017

In the early part of rice growth, root volume primarily limits the amount of plant-accessible nitrogen (N). Therefore, knowledge of the root development is important for modeling N uptake of rice. The timing when the volume of rhizosphere cover the whole soil is also important to carry out timely top dressing. However, information about initial root expansion and associated N uptake is limited due to intrinsic technical difficulties in assessing below-ground processes. Some studies, however, showed a close relationship between below-ground root and above-ground leaf development, suggesting a possibility that above-ground attributes could serve as surrogates for the root processes. In this study, we investigated the relationship between below-ground and above-ground development of rice. Field experiments were conducted where we cultivated Koshihikari (a leading cultivar in Japan) for four different cropping schedules in 2012. In 2016, Gimbozu (HEG4) and three flowering time mutant lines of Gimbozu (X61 (se13), HS276 (ef7), DMG9 (se13, ef7)) were examined for a single season. Experiments were performed with three replications in a completely randomized design. We monitored ammonium-N concentration ([NH4+-N]) in soil solution by repeatedly taking samples from a porous tubing (10-cm long) vertically inserted at the most distant point from surrounding rice hills. Samples were taken in triplicate (= triplicate tubes) and every three days from transplanting in each experimental unit. For above-ground attributes, leaf area index (LAI) was measured in 2012, whereas soil coverage ratio was estimated by image processing in 2016. Results showed that [NH4+-N] increased gradually after transplanting and then rapidly decreased from a certain day. This distinct drop in [NH4+-N] informed us the timing at which the rice root system reached the point of porous tubing and thus essentially covered the whole soil volume. The LAI at the dropping point was about 0.43 regardless of the cropping schedules in 2012 experiment. In 2016, the coverage ratio at the N dropping point was within the range of 0.12 to 0.19 for four genotypes having different growth durations. In addition, the coverage ratios at seven weeks after the transplanting showed a good correspondence to LAI across the four genotypes. We therefore conclude that both LAI and coverage ratio may serve as robust indicators for root development and might be useful to estimate the timing when the root system fully cover the soil volume. Results obtained here will also contribute to develop models that can predict not only above-ground canopy development but also associated below-ground processes.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.480-507
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• 2019

This paper aims at optimizing the auxiliary ventilation system in large-opening limestone mines with unducted fans. An extensive CFD and also site study were carried out for optimization at the blind entries. The fan location, operating mode, and layout are the parameters for optimization. Since the jet stream discharged from the auxiliary fan is flowing faster than 15 m/s in most of the cases, the stream collides with floor, sides or roof and even with the jet stream generated from the other fan placed upstream. Then, it is likely to lose a large portion of its inertial force and then its ventilation efficiency drops considerably. Therefore, the optimal fan installation interval is defined in this study as an interval that maximizes the uninterrupted flowing distance of the jet stream, while the cross-sectional installation location can be optimized to minimize the energy loss due to possible collision with the entry sides. Consequently, the optimization of the fan location will improve ventilation efficiency and subsequently the energy cost. A number of different three-dimensional computational domains representing a full-scale underground space were developed for the CFD study. The velocity profiles and the CO concentrations were studied to design and optimize the auxiliary ventilation system without duct and at the same time mine site experiments were carried out for comparison purposes. The ultimate goal is to optimize the auxiliary ventilation system without tubing to provide a reliable, low-cost and efficient solution to maintain the clean and safe work environment in local large-opening underground limestone mines.