• Journal of Veterinary Clinics
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• v.8 no.1
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• pp.71-80
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• 1991

Clinical signs, serum chemical values and histological findings of hepatic tissue after partial and complete obstruction of common bile duct in Korean goats were investigated. Abnormal clinical signs were not observed in partial obstruction of common bile duct, but in complete obstruction clinical signs such as jaundice, urine color change, were observed. Serum total bilirubin, total cholesterol, aspartate aminotransferase, sorbitol dehydrogenase, gamma glutamyltranspeptidase, and total protein values increased on the 1-4th day and then gradually decreased to normal level in partial obstruction. However, they tend to increase persistently by the 24th day in complete obstruction of common bileduct. Histologic features of hepatic tissue in partial obstruction were not changed as compared with normal hepatic tissue. On the other hand, in complete obstruction of common bite duct there were moderate bile duct proliferation in a portal area, rupture of bile canaliculi, phagocytosis of bile pigment by Kupffer cells, periportal fibrosis, intrahepatic bile stasis and hepatic cell necrosis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.386-395
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• 2005

With the development of a living standard, the importance of indoor air conditioning system in all kinds of buildings and vehicles has increased. A lot of researches on energy losses in a duct and various kinds of flow pattern in branches or junctions have been carried out over many years, because the primary object of a duct system used in HVAC is to provide equal flow rate in the interior of each room by minimizing pressure drop. In this study, to get equal flow distribution in each branch, a blockage is applied to the rectangular duct system. The flow analysis for flow distribution of a rectangular duct with two branches was performed by CFD. By using SIMPLE algorithm and finite volume method, flow analysis is performed in the case of 3-D, incompressible, turbulent flow. Also, the standard $k-{\varepsilon}$ model and wall function method were used for analysis of turbulent fluid flow. The distribution diagrams of static pressure, velocity vector, turbulent energy and kinetic energy in accordance with variation of Reynolds number and blockages location in a rectangular duct show that flow distribution at duct outlets is improved by a blockage. In this rectangular duct system, mean velocity and flow rate distribution in two branch outlets are nearly constant regardless of variation of Reynolds number, and a flow pattern of the internal duct has a same tendency as well.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.6
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• pp.474-481
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• 2018

This paper is to compare by numerical analysis the flow characteristics and propulsion performance of stern with the shape change of K-duct, a pre-swirl duct developed by Korea Research Institute of Ships & Ocean Engineering (KRISO). First, the characteristics of the propeller and the resistance and self-propulsion before and after the attachment of the K-duct to the ship were verified and the validity of the calculation method was confirmed by comparing this result with the model test results. After that, resistance and self-propulsion calculations were performed by the same numerical method when the K-duct was changed into five different shapes. The efficiency of the other five cases was compared using the delivery horsepower in the model scale and the flow characteristics of the stern were analyzed as the velocity and pressure distributions in the area between the duct end and the propeller plane. For the computation, STAR-CCM +, a general-purpose flow analysis program, was used and the Reynolds Averaged Navier-Stokes (RANS) equations were applied. Rigid Body Motion (RBM) method was used for the propeller rotating motion and SST $k-{\omega}$ turbulence model was applied for the turbulence model. As a result, the tangential velocity of the propeller inflow changed according to the position angle change of the stator, and the pressure of the propeller hub and the cap changes. This regulated the propeller hub vortex. It was confirmed that the vortex of the portion where the fixed blade and the duct meet was reduced by blunt change.

• Fire Science and Engineering
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• v.24 no.2
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• pp.97-105
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• 2010

The smoke control systems using pressure differentials are already well known as the most reliable method to prevent the smoke infiltration into the emergency stairs or safe spaces. However, it is true that many problems are domestically pointed out due to the insufficient understanding and technology on the smoke control systems using pressure differentials. In this regard, this work analyzed the effect of major factors for smoke control system using pressure differentials such as a duct area, opening area of air supply damper, improvement on open vestibules, stack effect and location of air supply. In conclusion, adequate pressure differentials can not be maintained in small duct because the smaller duct area have the large friction loss. Especially, It is confirmed that the major factor for deterioration of smoke control system performance is stack effect that makes pressure differentials smaller in the lower floors.

• International Journal of Fluid Machinery and Systems
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• v.6 no.2
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• pp.56-74
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• 2013

Stall stagnations in the system of axial-flow compressors and ducts occur in transition from deep surge conditions to decayed or converged stall conditions. The present study is concerned with the boundaries between the deep surges and the stagnation stalls on the basis of analytical results by a code on surge transients analysis and simulation. The fundamental acoustical-geometrical stagnation boundaries were made clear from examinations of the results on a variety of duct configurations coupled with a nine-stage compressor and a single stage fan. The boundary was found to be formed by three parts, i.e., B- and A-boundaries, and an intermediate zone. The B-boundary occurs for the suction-duct having a length of about a quarter of the wave-length of the first resonance in the case of very short and fat plenum-type delivery duct. On the other hand, the A-boundary occurs for the long and narrow duct-type delivery flow-path having a length about a fifth of the wavelength and relatively small sectional area in the case of short and narrow suction ducts. In addition to this, the reduced surge-cycle frequencies with respect to the duct lengths are observed to have respective limiting values at the stagnation boundaries. The reduced frequency for the B-boundary is related with a limiting value of the Greitzer's B parameter. The tendency and the characteristic features of the related flow behaviors in the neighborhood of the boundaries were also made clearer.

• Archives of Plastic Surgery
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• v.32 no.2
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• pp.255-258
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• 2005

The nasopalatine duct cyst, known as the incisive canal cyst, is the most common nonodontogenic cyst in the maxillofacial area. It is believed to arise from epithelial remnants of the embryonic nasopalatine duct. Nasopalatine duct cysts are most often detected in patients between forties and sixties. The trauma, bacterial infection, or mucous retention has been suggested as etiological factors. The cysts often present as asymptomatic swelling of the palate but can present with painful swelling or drainage. Radiologic findings include a well demarcated cystic structure in a round, ovoid or heart shape presenting with a well-defined bone defect in the anterior midline of the palate between and posterior to the central incisors. Most of them are less than 2cm in size. On MRI, the cyst is identified as a high-intensity, well-marginated lesion, which indicates that it contains proteinaceous material. We experienced a case of a 61-year-old female patient who had a $2.3{\times}2.6{\times}1.7cm$ sized nasopalatine duct cyst. The bony defect after a surgical extirpation was restored with hydroxyapatite. So we report a good results with some reviews of the literatures.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.18 no.3
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• pp.180-186
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• 2015

Purpose: Bile duct dilatation is a relatively common sonographic finding; nevertheless, its clinical significance in children is controversial because little research has been done in the area. Therefore, we investigated the natural course and clinical significance of biliary duct dilatation in children. Methods: We performed a retrospective study of 181 children (range, 1-day-old to 17-year-old) in whom dilatation of the intrahepatic duct and/or common hepatic duct and/or common bile duct was detected by abdominal ultrasonography at the Severance Children's Hospital between November 2005 and March 2014. We reviewed and analyzed laboratory test results, clinical manifestations, and clinical course in these patients. Results: Pediatric patients (n=181) were enrolled in the study and divided into two groups. The first group included 59 subjects, without definitive cause of bile duct dilatation, who did not require treatment; the second group included 122 subjects, with definitive cause of bile duct dilatation or underlying biliary disease, who did require treatment. In the first group, 24 patients (40.7%) showed spontaneous resolution of bile duct dilatation, 20 patients (33.9%) showed no change, and 15 patients (25.4%) were lost to follow-up. In the second group, 31 patients were diagnosed with choledochal cysts, and 91 patients presented with biliary tract dilatations due to secondary causes, such as gallbladder or liver disease, post-operative complications, or malignancy. Conclusion: Biliary dilatation in pediatric patients without symptoms, and without laboratory and other sonographic abnormalities, showed a benign clinical course. No pathologic conditions were noted on follow-up ultrasonography.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.2
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• pp.82-90
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• 2003

The work presented here is a design and an implementation of PID control system to regulate a supply duct outlet air temperature in PEM (Personal Environment Module). In PEM, the air is heated to the required temperature while it flows through the supply duct without any mixing chamber. This makes the control of air temperature in PEM difficult. A simulation is done first to understand the relationship between a temperature distribution in working area, flow rate and the outlet air temperature of PEM. Then a linear dynamic model of heating process in PEM is derived. P, PD and PID type control systems, to provide the rapid response without overshoot and saturation in heater command voltage, are designed using a linear model obtained. Experimentally obtained data shows that the control system satisfies the design criteria and works properly in controlling the supply duct outlet air temperature.

• Journal of computational fluids engineering
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• v.2 no.2
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• pp.44-50
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• 1997

Accurate simulation of jet plume exhausting into the open space as well as onto the opposing wall is of interest both numerically and physically; the latter, from a system designer's point of view. In the current work, Navier-Stokes computation is undertaken to capture the flow pattern of a supersonic jet impinging onto a rectangular duct which deflects the vertical jet horizontally. Of particular interest are the flow structure in the jet exhaust area, pressure pattern and the magnitude of pressure force at the bottom wall. Usefulness of present characteristic boundary condition applied at the exiting plane of the duct is demonstrated by capturing such complex flow structures for different lengths of the deflection duct.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.1
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• pp.48-55
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• 2010

The purpose of this paper was to address the methodology of the air flow measurement using duct mach number that was considered area-weighed average obtained by total, static pressure and temperature measured at engine inlet duct. Without installing boundary rake, the prediction of air flow measurement was discussed. Actual air flow measurement and pressure value using pressure loss through inlet seal were described to improve the reliability and operability of altitude engine test facility.