• Clinical and Experimental Pediatrics
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• v.53 no.2
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• pp.167-172
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• 2010

Purpose : With improved survival of extremely low birth weight infants (ELBWI), there is an increase in the incidence of necrotizing enterocolitis (NEC) requiring laparotomy, and the risk of morbidity and mortality in these ELBWI is increased. Thus, we determined the prognostic factors in ELBWI who underwent laparotomy for NEC. Methods : We retrospectively reviewed the medical records of 35 ELBWI who underwent laparotomy for NEC from January 2001 to December 2008 at Samsung Medical Center. Results : Of 480 ELBWI, 35 required laparotomy for NEC; the mortality rate was 20% (Alive group n=28, Dead group n=7). The values of preoperative score for neonatal acute physiology-II (P =0.022) and fraction of inspired oxygen (P <0.001) were significantly higher in the dead group and values of base excess (P =0.004) were significantly lower in the dead group. Values of preoperative heart rate, respiration rate, mean blood pressure, pH, $CO_2$, and potassium ion were not significantly different between the study groups. Intraoperative fluid volume was significantly higher in the alive group than in the dead group (P =0.045). Postoperative infusion rate was significantly lower in the alive group than in the dead group (P =0.022). Conclusion : Good preoperative condition, more intraoperative fluid infusion, and stable postoperative hemodynamic condition were factors associated with favorable prognosis of laparotomy for NEC in ELBWI.

• Archives of Plastic Surgery
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• v.32 no.2
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• pp.183-188
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• 2005

Defect on the temporal area caused by, surgical ablation of a tumor or an infection should be reconstructed immediately to prevent potentially life-threatening complications such as meningitis and cerebrospinal fluid leakage. The defect on the temporal area usually presents as a typical 'cone-shape'. Successful reconstruction requires sufficient volume of well-vascularized soft tissue to cover the exposed bone and dura. From 1994 through 2003, the authors applied rectus abdominis free flap for the reconstruction of the temporal defect from 1994 through 2003. There were 10 patients with a mean age of 52.1 years. Of these 10 patients, external auditory canal cancer was present in four patients, temporal bone cancer in two, parotid gland cancer in one and three patients were reconstructed after debridement of infection(destructive chronic otitis media). All the free flaps survived, and flap-related complications did not occur. Compared to a local flap, the rectus abdominis free flap can provide sufficient volume of well-vascularized tissue to cover the large defect and can be well-tolerated during an adjuvant radiation therapy. The long and flat muscle can be easily molded to fit in to the 'cone-shape' temporal defect without dead space. It is also preferred because of the low donor site morbidity, a large skin island and an excellent vascular pedicle. Two-team approach without position change is possible. In conclusion, the authors think that rectus abdominis free flap should be considered as one of the most useful method for the reconstruction of a cone-shaped temporal defect.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.1
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• pp.29-34
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• 2008

The aim of the study was to investigate the effect of dietary fish oil supplementation on the semen characteristics of the Markhoz buck. Sixteen bucks were randomly allocated into 4 groups and received four different diets: unsupplemented control diet, supplemented with fish oil at 2.50% dry matter (DM), supplemented with fish oil (2.50% DM) and vitamin E (0.30 g/kg DM), and supplemented with vitamin E (0.30 g/kg DM). All experimental diets were formulated according to AFRC (1998). Semen was collected at 14 d intervals from June 17, 2006 to September 2, 2006. Semen characteristics were evaluated. Significant effects (p<0.05) of the week (sampling time) were observed for all parameters except semen volume. Also a significant effect (p<0.05) of dietary treatment was observed for all parameters except for percent sperm with normal morphologies and semen volume. Fish oil supplementation with excess vitamin E had a significant effect (p<0.05) on total number and sperm density, motility and progressive motility, percentage viability and dead sperm. The interaction between fish oil feeding and sampling time was significant (p<0.05) for all of the parameters. The bucks that received fish oil in association with vitamin E, effect fish oil showed the greatest improvement in semen characteristics compared with the other groups (p<0.05). This study showed that fish oil supplementation with vitamin E may have a beneficial effect on the semen quality and fertility of Markhoz bucks.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1356-1364
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• 1990

This paper deals with the preliminary design conditions of Stirling Engines based on an adiabatic analysis with regenerator effectiveness. The investigation of thermal regeneration process results that the definition of effectiveness proposed by Urieli et al. is appropriate for the present model. Then, it is applied to the already existing approximate analytic solution for the adiabatic model in order to optimize thermal efficiency as well as work parameter. Results show that thermal efficiency is less sensitive to the variation in design parameters than work. Phase angle for the maximum work is also the most efficient at high values of the effectiveness. Swept volume ratio should be chosen with care. The optimum value of dead volume ratio is at least less than the maximum efficiency condition. The feasible design range in compression ratio lies between the maximum efficiency condition and the structural limit of Stilring Engines, where the higher its value, the better. Changes in the temperature ratio do not alter the design conditions. Working fluids with the specific heat ratio 1.67 are more efficient that those with 1.4.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1197-1205
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• 1988

An analytical method to predict qualitative performance characteristics of the Stirling Engines in the preliminary design stages is investigated. Both the expansion and the compression cylinder are treated as adiabatic and piston motions are approximated as saw-toothed waves. Basic equations which were originally proposed by Finkelstein consist of mass conservation and energy balances for each adiabatic cylinder. The approximation on piston motions and physical conditions make it possible to divide an engine cycle into four fundamental processes. In each process, first, pressure can be expressed as a function of the crank angle by solving a nonlinear first order ordinary differential equation and other thermodynamic variables are determined in turn. Application of the cyclic steady condition to the whole processes can complete a cycle. Also, further analysis results in analytic expressions for cyclic work and heat transfer in terms of the engine parameters and thermodynamic variables at boundary points. The results are expected useful as a quick reference for the engine performances. Finally, the present method can be applied to the other adiabatic analyses on the Stirling Engines with piece wise linear piston motions, if mass variations are predictable.

• Clean Technology
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• v.24 no.4
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• pp.348-356
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• 2018

The adsorption equilibria of oxygen, nitrogen and argon on carbonaceous adsorbent with slit-shaped and randomly etched graphite (REG) pores were calculated by molecular simulation method. Reliable models of adsorbents and adsorbates for adsorption equilibria are important for the correct design of industrial adsorptive separation processes. At the smallest physical pore of $5.6{\AA}$, only oxygen molecules were accommodated at the center of the slit-shaped pore, and from $5.9{\AA}$ nitrogen and argon molecules could be accommodated in the pores. Slit pores showed higher adsorption capacity compared with REG pores with same averaged reenterance pore size due to dead volume and inaccessible volume in defected pores. And it was shown the adsorption capacities of oxygen and argon was same in larger pore size. From calculated adsorption isotherms at 298 K it showed that the adsorption capacity ratio of oxygen to nitrogen is increased as pressure is increased.

• Journal of Biomedical Engineering Research
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• v.43 no.6
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• pp.434-440
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• 2022

Liver transplantation is a critical used treatment method for patients with end-stage liver disease. The number of cases of living donor liver transplantation is increasing due to the imbalance in needs and supplies for brain-dead organ donation. As a result, the importance of the accuracy of the donor's suitability evaluation is also increasing rapidly. To measure the donor's liver volume accurately is the most important, that is absolutely necessary for the recipient's postoperative progress and the donor's safety. Therefore, we propose liver segmentation in abdominal CT images from pre-operation, POD 7, and POD 63 with a two-dimensional U-Net. In addition, we introduce an algorithm to measure the volume of the segmented liver and measure the hepatectomy rate and regeneration rate of pre-operation, POD 7, and POD 63. The performance for the learning model shows the best results in the images from pre-operation. Each dataset from pre-operation, POD 7, and POD 63 has the DSC of 94.55 ± 9.24%, 88.40 ± 18.01%, and 90.64 ± 14.35%. The mean of the measured liver volumes by trained model are 1423.44 ± 270.17 ml in pre-operation, 842.99 ± 190.95 ml in POD 7, and 1048.32 ± 201.02 ml in POD 63. The donor's hepatectomy rate is an average of 39.68 ± 13.06%, and the regeneration rate in POD 63 is an average of 14.78 ± 14.07%.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.47-55
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• 1989

High frequency ventilation (HFV) is a new ventilatory technique that uses very small tidal volume(less than the anatomic dead space) and high frequency, and classified 4 distinct types according to frequency and mode of gas delivery. The mechanism of gas transport of high frequency oscillation ventilation(HFOV) is somewhat different to other types of HFV. To evaluate the determinants of $PaCO_2$ in HFOV, a study was done with a HFOV on 9 cats, and the results are : 1) $PaCO_2$ was not correlated with frequency at the constant stroke volume(6 voltage) and bias flow (6L/minutes). 2) $PaCO_2$ was correlated with stroke volume but not with bias flow under the constant frequency(15Hz/min) and bias flow(3 to 6L/min). From above results, the main determinant of $PaCO_2$ on artificial ventilation with HFOV was stroke volume, but further study between flow, the site of delivery to the airway and humidification of bias flow and $CO_2$ elimination is required in future research.

• Korean Journal of Environmental Agriculture
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• v.24 no.1
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• pp.6-11
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• 2005

A prototype surface flow constructed wetland was built in the upstream area of reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, a tracer test using rhodamine-WT was performed to investigate the flow characteristics and to quantify the observed hydraulic residence time (HRT) for a high-lying cell in the Banwol wetland of the Sihwa constructed wetland. The tracer test indicated that even if flow was mainly observed in the open water area of the Banwol wetland, water flowed continuously in the vegetative area and there was no dead zone. The calculated HRT (51.3 hrs), calculated by dividing the wetland volume by the wetland inflow, exceeded the observed HRT (38.7 hrs), since the short-circuiting of flux resulting from irregular topography and vegetation was not reflected in the calculated HRT. The exit tracer concentration curves were reproduced well by both the plug flow with dispersion and tanks-in-series models, indicating that the performance of the Banwol wetland can be estimated accurately using these models.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.3
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• pp.307-313
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• 2020

The 3.9 liter diesel engine with a mechanical fuel injection system was converted to di-methyl ether (DME) engine and performance optimized. In order to switch to the DME engine, the plunger of the high pressure fuel pump was replaced and the diameter of the injector nozzle was increased. Through this, the disadvantage of DME having low calorific value per volume can be compensated. To optimize the performance, the number of injector nozzle holes, injector opening pressure, and fuel injection timing were changed. As a result, the optimum number of injector nozzle holes was 5, the injector opening pressure was from 15 MPa to 18 MPa, and the injection timing was 15 crank angle degree before top dead center (CAD BTDC). The power was at the same level as the base diesel engine and nitrogen oxides (NOx) emissions could be reduced.