• Korean Journal of Bronchoesophagology
• /
• v.5 no.2
• /
• pp.182-190
• /
• 1999

OBJECTIVES : To determine the results of posterior cricoid split with costal cartilage graft in the treatment of moderate and severe subglottic stenosis in adults, and to assess the effect of T-tube as a stent in this surgery. PATIENTS AND METHODS : Four adults with moderate and severe subglottic stenosis who underwent posterior cricoid split with costal cartilage graft from 1994 to 1995. Three patients were male and one was female. All of the patients had acquired subglottic stenosis, 2 of whom had a bilateral vocal folds paralysis. The surgical procedure we used included a cricoid lamina split with costal cartilage grafting and T-tube stenting. Arytenoidectomy was a added in 2 patients with bilateral vocal folds paralysis. RESULTS : Three of the 4 patients underwent decannulation, and 1 is still undergoing treatment. 3 patients who underwent decannulation demonstrated marked improvement in their symptoms of airway obstruction and good postoperative voice quality. CONCLUSIONS : The posterior cricoidotomy lumen augmentation with costal cartilage grafting is a safe and effective technique for the treatment of moderate and severe subglottic stenosis in adults and T-tube is a good alternative stenting material for this procedure.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.18 no.1
• /
• pp.20-31
• /
• 2008

A respirator is useful to protect a worker from the harmful gases and vapors in the workplace, and the evaluation of respirator cartridge service life is important for the worker's health and safety. The performance of cartridge is effected by several factors such as concentration of gas and vapor, humidity, temperature, adsorbents and cartridge packing density. Adsorption model was applied to both sampling tube and respirator cartridge to predict the service life for organic vapors. The variables of the adsorption model were measured from the experiment with the sampling tube, and it was used to predict the service life of respirator cartridge. In the experiment, we used carbon tetrachloride as a organic vapor and activated carbon take out respirator cartridge as activated carbon. As a result, it was possible to predict the service life of respirator cartridge and predicted service life was quite correct. Breakthrough time decreased with increase of CCl4 concentration. In case of sampling tube, adsorbed amount of CCl4 was larger than respirator cartridge due to linear velocity. Also, rate constant of sampling tube was larger than respirator cartridge, because of, effect of flow rate, packing density. In the prediction of service life of respirator cartridge by using sampling tube, the time required for 50% contaminant breakthrough(${\tau}$) is more effective than the rate constant(k').

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.12
• /
• pp.1140-1145
• /
• 2008

In conventional cutting system of Heat-Shrink-Tube, workers operate cutting system after considering about length and quantity of heat-shrink-tube. So, not only work time and production cost is increased but also material is wasted because the data that workers have to consider is so much. In this paper, an effective cutting system of heat-shrink-tube was developed to reduce production cost, work time and waste of material. The cutting system consists of a supervisory computer installed inside a control room, a on-site computer installed on the work area, and a PLC system. In the developed system, a supervisory computer send work order to the on-site computer using LAN and the on-site computer operates the cutting system of the heatshrink-tube after it makes an array production order. Also, the on-site computer reports information to the supervisory computer when an accident happened.

• Biomedical Science Letters
• /
• v.13 no.4
• /
• pp.319-324
• /
• 2007

One-tube nested polymerase chain reaction (PCR) was evaluated for its efficacy in detecting Mycobacterium leprae in biopsy samples from leprosy patients. Primers were derived from the M leprae-specific element (RLEP) sequences which yield a 230 bp fragment. The specificity and the sensitivity of the one-tube nested PCR were compared with those of single PCR for detecting M leprae. The results showed that the one-tube nested PCR was about 100 times more sensitive than that of the single indicating the one-tube nested primer sets developed in this study can be an effective screening tool for the detection of M leprae in clinical diagnostic laboratories.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.5
• /
• pp.637-645
• /
• 2009

The main purpose of this study lies on the improvement of micro dilution tunnel based on the typical porous tube type chamber. The characteristics of flow and temperature fields for steady state has been obtained by numerical analysis using FLUENT. Three different geometrical variations of the porous tube; a) increase of thickness at center, b) step increase of thickness at center and downstream, c) tapered increase of thickness, have been proposed. Accordingly results are obtained and compared in terms of penetration velocity and velocity ratio to therrmophoretic velocity for improvement against particulate deposition inside the tube. The penetration velocity and velocity ratio distributions in the upstream portion and portion of impinging of dilution air are apparently shown to be improved for the case of the step and tapered change of porous tube. The tapered change of tube thickness addition are shown to be the most effective among three geometrical changes. In addition, the considerable improvement against deposition are shown that its thickness should be at least 2mm.

• Transactions of Materials Processing
• /
• v.23 no.5
• /
• pp.317-322
• /
• 2014

Bursting during tube hydroforming is preceded by localized necking. The retardation of the initiation of necking is a means to enhance hydroformability. Since high strain gradients occur at the necking sites, a decrease in local strain gradients is an effective way to retard the initiation of necking. In the current study, the expansion at potential necking sites was intentionally restricted in order to reduce the strain gradient at potential necking sites. From the strain distribution obtained from FEM, it is possible to determine strain concentrated zones, which are the potential necking sites. Prior to the hydroforming of a trailing arm, an incompressible material(such as lead) is attached to the tube where the strain-concentrated zone would contact the die. Due to the incompressibility of lead, the tube expansion is locally restricted, and the resultant strain extends to adjacent regions of the tube during hydroforming. After the first stage of hydroforming, the lead is removed from the tube, and the hydroforming continues to the final targeted shape without any local restriction. This method was successfully used to fabricate a complex shaped automotive trailing arm that had previously failed during traditional hydroforming fabrication.

• Steel and Composite Structures
• /
• v.29 no.5
• /
• pp.659-667
• /
• 2018

This paper deals with the experimental study on strength the strength and deformation characteristics of short circular Concrete Filled Steel Tube (CFST) columns. Effect of vertical stiffeners on the behavior of the column is studied under axial compressive loading. Intermittently welded vertical stiffeners are used to strengthen the tubes. Stiffeners are attached to the inner surface of tube by welding through pre drilled holes on the tube. The variable of the study is the spacing of the weld between stiffeners and circular tube. A total of 5 specimens with different weld spacing (60 mm, 75 mm, 100 mm, 150 mm and 350 mm) were prepared and tested. Short CFST columns of height 350 mm, outer tube diameter of 165 mm and thickness of 4.5 mm were used in the study. Concrete of cube compressive strength $41N/mm^2$ and steel tubes with yield strength $310N/mm^2$ are adopted. The test results indicate that the strength and deformation of the circular CFST column is found to be significantly influenced by the weld spacing. The ultimate axial load carrying capacity was found to increase by 11% when the spacing of weld is reduced from 350 mm to 60 mm. The vertical stiffeners are found to effective in enhancing the initial stiffness and ductility of CFST columns. The prediction models were developed for strength and deformation of CFST columns. The prediction is found to be in good agreement with the corresponding test data.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.05a
• /
• pp.30-35
• /
• 2004

Several roll motion reduction devices are reviewed and suggested for the application in FPSO. The firstly suggested solution is the shape of the bilge. The next is a bilge keel. The last suggestion is the ART (anti-rolling tank). Typical U-tube type ART is designed for a FPSO and examined extensively by model experiment. The model section was made of transparent acryl. Free decay test, forced oscillation test and wave test were carried out at a two-dimensional wave flume. U-tube type ART is effective only when the natural periods of ART and ship are same. Therefore, the divided U-tube type ART with split plate is suggested for the reduction of the roll motion of a FPSO over the wide range of the roll period.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.102-105
• /
• 2001

The spring back taking place after the coiling process of steam generator tube leads to the dimensional inaccuracy. In order to reduce the spring back, tension force was applied to the one end of the tube during forming. In this work, parametric study using FEM was performed to find the appropriate magnitude of tension force. The force that induces minimum suing back was found by simultaneously taking account of suing back amount, cross-sectional ovality, and thickness of the tube wall after deformation. In addition, stress relieving by heat treatment was also simulated as an alternative to the former method. The latter was found to be more effective under the given constraints.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.828-833
• /
• 2001

In this study, an analysis tool to assess the susceptibility of steam generator tubes due to the flow-induced vibration was developed. The fluid-elastic instability analysis of the U-tube bundle for CE-type steam generator was accomplished. The effective mass distribution along the U-tube was obtained to calculate the natural frequency and dynamic mode shape. Finally, stability ratios for selected tubes are obtained.