• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.126-132
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• 2014

PURPOSE. This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS. Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (${\alpha}$=0.05). RESULTS. The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION. The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.

• 품질경영학회지
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• 제51권4호
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• pp.633-642
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• 2023

Purpose: The variation of the internal diameters of gun barrel incurs a lot of reworks in gun barrel manufacturing process and the significant quality problem of gun barrel. And it is likely to stem from the current measurement system for the internal diameter of gun barrel and the related manufacturing process as well. The purpose of this study is to improve the gun barrel manufacturing process through improving measurement system. Methods: The improved measurement system using laser can measure the internal diameters of gun barrel more accurately, and the properly adjusted honing process reduces the variation of internal diameters of gun barrel. Results: Comparing the mean square error of internal diameters for 6 gun barrels measured before and after process improvement shows that the variation of gun barrel internal diameters was significantly reduced after the process improvement. Conclusion: The introduction of improved measurement system for the internal diameters of gun barrel and the adjustment of related honing process results in the reduction of reworks of gun barrels and their internal diameter variations.

• 열처리공학회지
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• 제6권4호
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• pp.243-248
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• 1993

A Circulating Fluidized-Bed (CFB) with an internal nozzle and a partition wall was proposed. The technique of fluidization is related to operations first used commercially in the fields of metallurgical and mechanical engineering such as the heat treatment of metals and power station combustors. In the modified CFB, an internal nozzle and a partition wall were additionally set in the main bed. This cold mode CFB apparatus made of acrylic resin; the main bed is 1,500mm high and 100mm in the inner diameter, the internal nozzle is 130mm high and 10mm in the inner diameter, and the partition wall is 7mm thick and 100mm in the diameter. Glass beads of $89{\mu}m$ in the mean diameter were employed as bed materials.

• Tuberculosis and Respiratory Diseases
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• 제81권2호
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• pp.123-131
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• 2018

Background: Chronic obstructive pulmonary disease (COPD) may cause changes in the shape of the thoracic cage by increasing lung volume and hyperinflation. This study investigated changes in thoracic cage dimensions and related factors in patients with COPD. Methods: We enrolled 85 patients with COPD (76 males, 9 females; mean age, $70.6{\pm}7.1years$) and 30 normal controls. Thoracic cage dimensions were measured using chest computed tomography at levels 3, 6, and 9 of the thoracic spine. We measured the maximal transverse diameter, mid-sagittal anteroposterior (AP) diameter, and maximal AP diameter of the right and left hemithorax. Results: The average AP diameter was significantly greater in patients with COPD compared with normal controls ($13.1{\pm}2.8cm$ vs. $12.2{\pm}1.13cm$, respectively; p=0.001). The ratio of AP/transverse diameter of the thoracic cage was also significantly greater in patients with COPD compared with normal controls ($0.66{\pm}0.061$ vs. $0.61{\pm}0.86$; p=0.002). In COPD patients, the AP diameter of the thoracic cage was positively correlated with body mass index (BMI) and 6-minute walk test distance (r=0.395, p<0.001 and r=0.238, p=0.028) and negatively correlated with increasing age (r=-0.231, p=0.034). Multiple regression analysis revealed independent correlation only between BMI and increased ratio of AP/transverse diameter of the thoracic cage (p<0.001). Conclusion: Patients with COPD exhibited an increased AP diameter of the thoracic cage compared with normal controls. BMI was associated with increased AP diameter in these patients.

• Tuberculosis and Respiratory Diseases
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• 제77권6호
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• pp.251-257
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• 2014

Background: Transbronchial lung biopsy (TBLB) is a valuable diagnostic tool for peripheral pulmonary lesions. The diagnostic yield of TBLB reportedly ranges from 41%-60%. Many studies demonstrated the various factors that influence the yield of TBLB, including size, location, and distance from the carina or pleura. However, no study has evaluated the effects of the bronchoscope diameter. We evaluated whether the bronchoscope diameter affected the diagnostic yield of TBLB. Methods: We reviewed records from 178 patients who underwent TBLB using bronchoscopes of two different diameters (5.7 mm, thick outer diameter, Olympus BF-200; 4.9 mm, thin, BF-260). The fluoroscopic guidance rates, yield of TBLB and flexible bronchoscopy (FB) were compared between the two groups. Additionally, we compared the results of the procedures with respect to diagnosis, distance from the pleura, and size of the lesion. Results: The results of fluoroscopic guidance, TBLB, and FB yield using thin diameter bronchoscope were significantly better than those obtained with a thick diameter bronchoscope (p=0.021, p=0.036, and p=0.010, respectively). Particularly, when the distance from the pleura was ${\leq}10mm$, success rates for fluoroscopic guidance and FB with thin bronchoscope were higher (p=0.013 and p=0.033, respectively), as compared to with thick bronchoscope. Conclusion: A thinner diameter bronchoscope increased the yield of bronchoscopy, and bronchial washing in conjunction with TBLB was useful in the diagnosis of peripheral pulmonary nodules.

• 대한치과보철학회지
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• 제41권4호
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• pp.393-404
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• 2003

Statement of problem. Higher incidence of prosthetic complications such as screw loosening, screw fracture has been reported for posterior single tooth implant. So, there is ongoing research regarding stability of implant-abutment interface. One of those research is increasing the implant diameter and prosthetic table width to improve joint stability. In another part of this research, internal conical type implant-abutment interface was developed and reported joint strength is higher than traditional external hex interface. Purpose. The purpose of this study is to compare stress distribution in single molar implant between external hex butt joint implant and internal conical joint implant when increasing the implant diameter and prosthetic table width : 4mm diameter, 5mm diameter, 5mm diameter/6mm prosthetic table width. Material and method. Non-linear finite element models were created and the 3-dimensional finite element analysis was performed to see the distribution of stress when 300N static loading was applied to model at $0^{\circ},\;15^{\circ},\;30^{\circ}$ off-axis angle. Results. The following results were obtained : 1. Internal conical joint showed lower tensile stress value than that of external hex butt joint. 2. When off-axis loading was applied, internal conical joint showed more effective stress distribution than external hex butt joint. 3. External hex butt joint showed lower tensile stress value when the implant diameter was increased. 4. Internal conical joint showed lower tensile stress value than external hex butt joint when the implant diameter was increased. 5. Both of these joint mechanism showed lower tensile stress value when the prosthetic table width was increased. Conclusion. Internal conical joint showed more effective stress distribution than external hex joint. Increasing implant diameter showed more effective stress distribution than increasing prosthetic table width.

• 동력기계공학회지
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• 제20권5호
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• pp.78-85
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• 2016

This paper considers the influence of internal heat exchangers to the efficiency of a refrigerating system using R170. These liquid-gas heat exchangers(internal or suction-line heat exchangers) can, in some cases, yield improved system performance while in other cases they degrade system performance. A steady state mathematical model is used to analysis the performance characteristics of refrigeration system with internal heat exchanger. The influence of operating conditions, such as the mass flowrate of R170, inner diameter tube and length of internal heat exchanger, to optimal dimensions of the heat exchanger is also analyzed in the paper. The main results were summarized as follows : the mass flowrate of R170, inner diameter tube and length of internal heat exchanger, and effectiveness have an effect on the cooling capacity, compressor work and RCI(Relative Capacity Index) of this system. Exception for the effect of inner diameter, the RCI of R170 with respect to refrigerant mass flowrate, the length and effectiveness of internal heat exchanger is about 2.1~3.3% higher than that of R13 at the same experimental conditions. With a thorough grasp of these effect, it is necessary to design the R170 compression refrigeration cycle using internal heat exchanger.

• Archives of Plastic Surgery
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• 제36권1호
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• pp.24-28
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• 2009

Purpose: As a recipient vessel, internal mammary vessels have many advantages for microvascular reconstruction of the breast. But the approach is time consuming and results in large morbidities. However, the perforating branches of the internal mammary vessels can be used to minimize such demerits. The purpose of this cadaver study is to clarify the location and diameter of the perforating branches of internal mammary vessels and to prove they are safe and reliable recipient vessels. Methods: We studied 11 formalin - fixed cadavers and dissected their anterior chests bilaterally. The chests were exposed using midline presternal incisions. We dissected and found all perforators at subfascial planes under loupe magnification. The number, external diameter, and the distance from the midline were measured. Result: The mean external diameter of the arterial perforators was 1.32 mm and the mean external diameter of the venous perforators was 1.48 mm. The largest arterial and venous perforators were most frequently found in the second intercostal space. The mean distance from the midline to the perforator was evaluated; the artery averaged 1.95 cm and the vein averaged 2.08 cm. Conclusion: This study will be helpful when using the internal mammary perforating vessels as a recipient vessel during breast reconstruction.

• 한국기계가공학회지
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• 제19권6호
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• pp.49-54
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• 2020

The purpose of this study is to investigate the effects of the change in the spindle speed and the feed rate on the diameter change of a hole using a boring cutter for the internal boring process of AL6061-T4 alloys. The experimental results are quantitatively analyzed by applying the factor analysis and the response surface analysis of the experimental design method. The tendency of the diameter change according to the change in the spindle speed and feed level is also evaluated. During the internal boring process of AL6061-T4 alloys, the main factor affecting the diameter change is the spindle speed in which the diameter decreases as the number of revolutions increases. In addition, the diameter tends to increase as the feed is increased; however, as the number of spindle revolutions increases, the influence of the feed decreases.

• 동력기계공학회지
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• 제18권4호
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• pp.36-42
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• 2014

This paper considers the influence of internal heat exchangers on the efficiency of a refrigerating system using R-1270. These internal heat exchangers(liquid-gas or suction-line heat exchangers) can, in some cases, yield improved system performance while in other cases they degrade system performance. A steady state mathematical model is used to analysis the performance characteristics of refrigeration system with internal heat exchanger. The influence of operating conditions, such as the mass flowrate of R-1270, inner diameter tube and length of internal heat exchanger, to optimal dimensions of the heat exchanger is also analyzed. The main results were summarized as follows : the mass flowrate of R-1270, inner diameter tube and length of internal heat exchanger, and effectiveness have the influences on the cooling capacity, compressor work and RCI(Relative Capacity Index) of this system. With a thorough grasp of it is possible to design the R-1270 compression refrigeration cycle using internal heat exchanger.