• Proceedings of the KSME Conference
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• 2002.08a
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• pp.659-662
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• 2002

The present paper presents the experimental results for pressure drop in inclined tube bundles located in a rectangular duct. Measurements are made for pressure drop in triangular and rotated triangular tube arrays having P/d ratio of 1.6 and inclination angles of 30,45,60 and 90 degrees. The Reynolds number based on the free stream velocity and tube diameter ranges from $8{\times}10^2\;to\;6.3{\times}10^{4}$. The experimental results show that the magnitude of dimensionless pressure drop decreases significantly when the inclined angle is less than 45 degree. The measured data are compared with two existing correlations available in the literatures. The ESDU correlation agrees well with the present data far the triangular arrays. But some discrepancies are observed for the rotated triangular arrays when the inclined angles are 30 and 45 degrees. The Idel'chik correlation generally agrees well with the measured data for the rotated triangular arrays except for the inclined angle of 30 degree. The Idel'chik correlation needs modification for the triangular arrays. The modified Idel'chik correlation agrees well with the measured data within $10{\%}$. It is found that the present measured data can be applied to the evaluation and modification of previous correlations.

• Imaging Science in Dentistry
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• v.41 no.3
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• pp.95-100
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• 2011

Purpose : The purpose of this study was to compare asymmetric mandibular prognathism individuals with symmetric mandibular prognathism individuals using a new alternate spherical coordinate system. Materials and Methods : This study consisted of 47 computed tomographic images of patients with mandibular prognathism. The patients were classified into symmetric and asymmetric groups. Mandibular and ramal lines were analyzed using an alternate spherical coordinate system. The length as well as midsagittal and coronal inclination angle of the lines was obtained. The bilateral differences of the spherical coordinates of the facial lines were statistically analyzed in the groups. Results : There were significant differences between the groups in bilateral difference of the length and midsagittal inclination angle of the lines (p<0.05). The bilateral difference of the length and midsagittal inclination angle of the lines has significant correlation with chin deviation (p<0.05). Conclusion : The new alternate spherical coordinate system was able to effectively evaluate facial lines. The bilateral difference of lengths and midsagittal inclination of the facial lines might contribute to the facial asymmetry in mandibular prognathism individuals.

• Nuclear Engineering and Technology
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• v.45 no.7
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• pp.911-920
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• 2013

Experimental studies on both subcooled and saturated pool boiling of water were performed to obtain local heat transfer coefficients on a $3^{\circ}$ inclined tube of 50.8 mm diameter at atmospheric pressure. The local values were determined at every $45^{\circ}$ from the very bottom to the uppermost of the tube periphery. The maximum and minimum local coefficients were observed at the azimuthal angles of $0^{\circ}$ and $180^{\circ}$, respectively, in saturated water. The locations of the maxima and the minima were dependent on the inclination angle of the tube as well as the degree of subcooling. The major heat transfer mechanisms were considered to be liquid agitation generated by the sliding bubbles and the creation of big size bubbles through bubble coalescence. As a way of quantifying the heat transfer coefficients, an empirical correlation was suggested.

• Journal of the Korean GEO-environmental Society
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• v.19 no.2
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• pp.13-21
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• 2018

The magnitude and distribution of earth pressure on the excavation wall in jointed rock mass were examined by considering different wall permeability conditions as well as rock types and joint inclination angles. The study was numerically extended based on a physical model test (Son & Park, 2014), considering rock-structure interactions with the discrete element method, which can consider various characteristics of rock joints. This study focused on the effect of the permeability condition of excavation wall on the earth pressure in jointed rock masses under a groundwater condition, which is important but has not been studied previously. The study results showed that the earth pressure was highly influenced by wall permeability as well as rock type and joint condition. Earth pressure resulted from the study was also compared with Peck's earth pressure in soil ground, and the comparison clearly showed that the earth pressure in jointed rock mass can be greatly different from that in soil ground.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.139-144
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• 2003

Augmentation of CHF by ultrasonic vibration in water pool is experimentally investigated under pool boiling condition. The experiments are carried out using copper coated plates and distilled water. Measurements of CHF on flat plate heated surface were made with and without ultrasonic wave and with variations in inclined angle of the surface and water subcooling. Experimental apparatus consists of a bath, power supply, test section, ultrasonic generator, and data acquisition system. The measurements show that ultrasonic wave enhances CHF and its extent is dependent upon inclination angle as well as water subcooling. The rate of increase in CHF increases with an increase in water subcooling while it decreases with an increase in inclination angle. Visual observation shows that the cause of CHF augmentation is closely related with the dynamic behavior of bubble generation and departure in acoustic field.

• Knee surgery & related research
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• v.30 no.4
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• pp.311-318
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• 2018

Purpose: The purpose of this study was to evaluate changes in the coronal alignment of the knee and ankle joints after open wedge high tibial osteotomy (OWHTO) to determine factors related to the recurrence (R) of the varus deformity by serial analysis. Materials and Methods: Sixty-four OWHTOs were enrolled in this study. The weight bearing line (WBL) ratio, joint line convergence angle (JLCA), knee joint inclination, mechanical axis-tibial plateau angle, talar inclination (TI), and distal tibia articular angle (DTAA) were serially assessed. Serial correlation analysis between all parameters was performed. Patients were divided into R group and no recurrence (NR) group according to the WBL ratio (55%) at postoperative one year. Results: The preoperative WBL ratio showed significantly negative correlation with serial changes of JLCA, TI, and DTAA (p<0.05). The JLCA, TI, and DTAA as well as WBL ratio showed a significantly larger degree of varus alignment in the R group than in NR group at postoperative 6 weeks and 1 year after OWHTO (p<0.05). Conclusions: Sufficient correction of the WBL and restoration of the JLCA during OWHTO are essential to prevention of the R of varus deformity after the surgery because they are the only modifiable factors during surgery. Level of Evidence: IV, Case series.

• Geomechanics and Engineering
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• v.20 no.5
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• pp.461-474
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• 2020

Analysing the incompatible deformation and damage evolution around the tunnels in mixed strata is significant for evaluating the tunnel stability, as well as the interaction between the support system and the surrounding rock mass. To investigate this issue, confined compression tests were conducted on upper-soft and lower-hard strata specimens containing a circular hole using a rock testing system, the physical mechanical properties were then investigated. Then, the incompatible deformation and failure modes of the specimens were analysed based on the digital speckle correlation method (DSCM) and Acoustic Emission (AE) data. Finally, numerical simulations were conducted to explore the damage evolution of the mixed strata. The results indicate that at low inclination angles, the deformation and v-shaped notches inside the hole are controlled by the structure plane. Progressive spalling failure occurs at the sidewalls along the structure plane in soft rock. But the transmission of the loading force between the soft rock and hard rock are different in local. At high inclination angles, v-shaped notches are approximately perpendicular to the structure plane, and the soft and hard rock bear common loads. Incompatible deformation between the soft rock and hard rock controls the failure process. At inclination angles of 0°, 30° and 90°, incompatible deformations are closely related to rock damage. At 60°, incompatible deformations and rock damage are discordant due that the soft rock and hard rock alternately bears the major loads during the failure process. The failure trend and modes of the numerical results agree very well with those observed in the experimental results. As the inclination angles increase, the proportion of the shear or tensile damage exhibits a nonlinear increase or decrease, suggesting that the inclination angle of mixed strata may promote shear damage and restrain tensile damage.

• Journal of the Korean GEO-environmental Society
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• v.16 no.2
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• pp.33-43
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• 2015

This paper investigated the magnitude and distribution of earth pressure on the support system in jointed rock mass by considering different earth pressure coefficients, rock types and joint inclination angles. The study mainly focused on the effect of the earth pressure coefficients on the earth pressure. Based on a physical model test (Son & Park, 2014), extended studies were conducted considering rock-structure interactions based on the discrete element method, which can consider the joints characteristics of rock mass. The results showed that the earth pressure was highly influenced by the earth pressure coefficients as well as the rock type and joint inclination angles. The effects of the earth pressure coefficients increased when the rock suffered more weathering and has no joint slide. The test results were also compared with Peck's earth pressure for soil ground, and clearly showed that the earth pressure in jointed rock mass can be greatly different from that in soil ground. This study indicated the earth pressure coefficients considering the rock types and joint inclination angles are important parameters influencing the magnitude and distribution of earth pressure, which should be considered when designing the support systems in jointed rock mass.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.6
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• pp.539-546
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• 2014

This paper describes an ultra-precision electronic clinometer, which is based on the capacitive-based fluid type, for detection of small inclination angles. The main parts of the clinometer low-noise electronics are two capacitance measurement circuits for converting the capacitances of the capacitors of the clinometer into voltages, and a differential amplifier for obtaining the difference of the capacitances, which is proportional to the input inclination angle. A 16 bit analog to digital (AD) converter is also embedded into the same circuit board, whose output is sent to a PC via RS-232C, for achieving a small noise level down to tens of ${\mu}v$. A compensation method, which is referred to as the delay time method for shortening the stabilization time of the sensor was also discussed. Experimental results have shown the possibility of achieving a measurement resolution of $0.0001^{\circ}$ as well as the quick measurement with the delay time method.

• Journal of Korean Foot and Ankle Society
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• v.8 no.1
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• pp.101-106
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• 2004

Purpose: To determine the efficacy of the SDBBA (Subtalar distraction bone block arthrodesis) procedure on patients with late complication of intra-articular calcaneal fractures including subtalar joint arthritis and anterior ankle impingement syndrome. Materials and Methods: Five cases in which the SDBBA procedure was implemented were followed for more than one year. All five patients were male with an average age of 56. Clinically, the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and the pain score were assessed. Radiographically, the talocalcaneal height and the talar inclination angle were determined. Results: All five patients achieved subtalar joint fusion. The average pre-operative AOFAS score was 22.8 scores (range, 8-32 scores). At last follow-up, these scores improved to an average of 72.4 scores (range, 64-82 scores). The average pre-operative pain score was 8.2 scores (range, 7-10 scores). At last follow-up, these scores improved to an average of 13.2 (range, 12-15 scores). The average pre-operative talocalcaneal height was 72.8 mm (range, 70-77 mm), average post-operative talocalcaneal height improved to 79.8 mm (range, 78-84 mm). At final follow-up, these measurement was slightly decreased to average 78.6 mm (range, 74-83 mm). The average pre-operative talar inclination angle was 13.2 degrees (range, 12-15 degrees), average post-operative talar inclination angle improvedto 19.2 degrees (range, 15-24 degrees). At final follow-up, these measurement was slightly decreased to average 18.6 degrees (range, 12-24 degrees). Four patients achieved successful outcomes. One patient developed a wound infection with subsequent sural neuropathy as well as collapse of the bone graft. Conclusion: This study shows that the SDBBA procedure successfully restores the talocalcaneal height and tibio-talar relationship. This procedure is useful in surgically managed patients with talo-calcaneal height loss and anterior ankle impingement syndrome due to the late complications of calcaneal intra-articular fractures.