• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.35-42
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• 1998

Time marching algorithms applied to compressible Navier-Stokes equation have a convergence problem at low Mach number. It is mainly due to the eigenvalue stiffness and pressure singularity as Mach number approaches to zero. Among the several methods to overcome the shortcomings of time marching scheme, time derivative preconditioning method have been used successfully. In this numerical analysis, we adopted a preconditioner of K.H. Chen and developed a two-dimensional, axisymmetric Navier-Stokes program. The steady state driven cavity flow and backward facing step flow problems were computed to confirm the accuracy and the robustness of preconditioned algorithm for low Mach number flows. And the transonic and supersonic flows insice the JPL axisymmetric nozzle internal flow is exampled to investigate the effects of preconditioning at high Mach number flow regime. Test results showed excellent agreement with the experimental data.

• Journal of Korea Foundry Society
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• v.20 no.6
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• pp.368-376
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• 2000

Rheology forming technology has been accepted as a new method for fabricating near net shaped products with lightweight aluminum alloys. The rheology forming process consists of reheating process of billet, billet handling, filling into the die cavity and solidification of rheology formed part. The rheology forming experiments are performed with two different die temperatures ($T_d$ = $200^{\circ}C$, $300^{\circ}C$) and orifice gate type. The filling behavior and various defects of Al-Si materials with wear resistance (A357, A390 and ALTHIX 86S) fabricated in rheology forming process are evaluated in terms of alloying elements and surface non-uniformity. Finally, the methods to obtain the rheology formed products with high quality are described by solutions for avoiding the surface and internal defects.

• Design & Manufacturing
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• v.2 no.1
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• pp.21-26
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• 2008

In this research, jar die of cosmetic products which is difficult to produce variously was developed and can be obtain the productivity improvement by flexibility with two system which can control the die temperature. Flow analysis of jar was performed to find out the curvature radius of parts. In order to reduce thickness of jar, cycle time, deformation, uniform curvature of internal jar was maintained by rapid cooling. In external of dies, cooling channel, injection molding condition, die temperature control system were researched to make dies low temperature.

• Journal of Chest Surgery
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• v.36 no.1
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• pp.43-46
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• 2003

A 45-year-old man was referred with symptoms of cough and chest pain for 3 days and small amount of hemoptysis. He had no history of pulmonary tuberculosis. Chest CT showed 2 cystic lesions with air fluid level ill right lower lobe. We performed posterior basal segmentectomy and found 2 cysts with white long parasite in each cavity. We experienced a case of pulmonary sparganosis and report it with references.

• The Korean Journal of Nuclear Medicine
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• v.28 no.1
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• pp.153-156
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• 1994

Massive hydrothorax complicating continuous ambulatory peritoneal dialysis (CAPD) is relatively rare. A 67-year-old male and a 23-year-old female patients during CAPD presented massive pleural effusion. They have been performing peritoneal dialysis due to end-stage renal disease for 8 months and 2 weeks respectively. We injected $^{99m}Tc$-labelled radiopharmaceutiral (phytate and MAA, respectively) into peritoneal cavity with the dialysate. The anterior, posterior and right lateral images were obtained. The studies reveal visible radioactivity in the right chest indicating the communication between the peritoneal and the pleural space. After sclerotherapy with tetracycline, the same studies reveal no radioactivity in the right chest suggesting successful therapy. We think nuclear imaging is a simple and noninvasive method for the differential diagnosis of pleural effusion in patients during CAPD and the evaluation of therapy.

• The KSFM Journal of Fluid Machinery
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• v.7 no.4 s.25
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• pp.32-39
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• 2004

This study deals with the Benard Flow of Magnetic Fluids in a rectangular cavity which the ratio between height and width is 1 : 4 and the base side or left side is a heating face while other sides are to be cooling faces. When Magnetic field was equally impressed, considering the internal rotation of the elementary ferromagnetic particle, we found the following result from the numerical analysis of the GSMAC algorithm applied to the equation of the magnetic fluid. Benard flow is controlled by intensity and direction of magnetic fields, and critical point appears when especially magnetic field with a heating base and side area near H=-7000 and H=-10000 is applied.

• Transactions of Materials Processing
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• v.24 no.1
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• pp.20-27
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• 2015

Hot tensile tests were conducted at different temperatures ranging from $20^{\circ}C$ to $550^{\circ}C$ to evaluate the mechanical properties of Al5052 seamless tubes. Such tubes can provide the technological foundation for complex forming using hot air bulging. Hot air bulging is one of the recently developed hydroforming techniques and it has some limitations in terms of cycle times. The benefits of hot air bulging are weight and cost savings through part consolidation and reduced post-forming processes such as welding and piercing. In order to extend the forming limits of Al lightweight material hot air bulging was investigated. A heated tube was placed in a heated die and sealed at the ends by sealing cylinders. The heated tube was subsequently expanded against the die cavity wall by internal pressure using air medium. The results of the current study show that axial feeding speed and air pressure have an effect on the formability of Al tubes during air bulging at elevated temperatures.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.145-147
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• 2009

The benefits of hydroforming technology are known as weight and cost savings through part consolidation and reduced post-forming processes such as welding and piercing. Hydroforming technology has some weaknesses in terms of process cycle times. But, as the hydraulic system and process designs are continuously developed, the cycle time is also reduced to acceptable and competitive levels. Hot air bulging is one of recently developed hydroforming techniques. Hot air bulging in order to further extend the forming degrees of Al lightweight material is investigated. A heated tube is placed in a heated die and sealed at the ends by sealing cylinders. The tube is subsequently expanded against the die cavity wall by internal pressure provided by air medium. The result of this study shows that axial feeding speed and air pressure have an effect on formability of Al air bulging at elevated temperature.

• Advances in pediatric surgery
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• v.9 no.1
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• pp.52-56
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• 2003

A 10 year old boy was admitted with blunt abdominal trauma by bike handle injury. The patient was operated upon for a generalized peritonitis due to pancreaticoduodenal injury. On opening the peritoneal cavity. complete transection of distal end of common bile duct and. partial separation between pancreas head and second portion of duodenum were found. Ligation of the transected end of the common bile duct. T-tube choledochostomy, and external drainage were performed. A pseudocyst was found around the head portion of the pancreas on the 7th postoperative day with CT. An internal fistula had developed between the pseudocyst and ligated common bile duct. The pseudocyst was subsided after percutaneous drainage. In the case of the undetermined pancreatic injury, percutaneous external drainage can be effective in treating the traumatic pancreatic pseudocyst in a pediatric patient.

• Archives of Craniofacial Surgery
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• v.17 no.2
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• pp.45-50
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• 2016

Extensive surgical resection of the aerodigestive track can result in a large and complex defect of the oropharynx, which represents a significant reconstructive challenge for the plastic surgery. Development of microsurgical techniques has allowed for free flap reconstruction of oropharyngeal defects, with superior outcomes as well as decreases in postoperative complications. The reconstructive goals for oral and oropharyngeal defects are to restore the anatomy, to maintain continuity of the intraoral surface and oropharynx, to protect vital structures such as carotid arteries, to cover exposed portions of internal organs in preparation for adjuvant radiation, and to preserve complex functions of the oral cavity and oropharynx. Oral and oropharyngeal cancers should be treated with consideration of functional recovery. Multidisciplinary treatment strategies are necessary for maximizing disease control and preserving the natural form and function of the oropharynx.