• International Journal of Advanced Culture Technology
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• v.3 no.2
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• pp.124-131
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• 2015

Computational fluid dynamics (CFD) has been employed for the Heat exchanger efficiency of a counter flow heat exchanger. The Heat exchanger efficiency has been assessed by considering the computed Nusselt number and flow friction characteristics in the double pipes heat exchanger equipped with two types twisted-tapes: (1) single clockwise direction and (2) alternate clockwise and counterclockwise direction. Cold and hot water are used as working fluids in shell and tube side, respectively. Hot and cold water inlet mass flow rates ranging are between 0.04 and 0.25 kg/s, and 0.166 kg/s, respectively. The inlet hot and cold water temperatures are 54 and $30^{\circ}C$, respectively. The results obtained from the tube with twisted-tapes insert are compared with plain tube. Nusselt number and friction factor obtained by CFD simulations were compared with correlations available in the literature. The numerical results were found in good agreement with the results reported in literature.

• The Journal of the Korean dental association
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• v.57 no.11
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• pp.654-663
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• 2019

This case report describes the management of a 30-year-old woman with hopeless mandibular first molars and right maxillary second premolar. The treatment plan included mandibular second and third molar protraction after extraction of mandibular first molars. Mini-implants were placed between roots of first and second premolar. Sliding mechanics with lever arm was used to prevent inclination of molars. A good functional occlusion was achieved in 38 months without clinically significant side effects. Most of the extraction space of mandibular first molar was closed by protraction of second and third molars. The skeletal Class II pattern was improved by counterclockwise rotation of mandible through reduction of wedge effect. Mandibular molar protraction with orthodontic mini-implants in adequate cases would be a great alternative to prosthetic implant and reduce the financial and surgical burden of patients.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.3 s.39
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• pp.155-169
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• 1990

The main purpose of this study is to suggest fundamental materials and a guideline for design through grouping of the users' use route patterns and analyzing determinants to choose those route patterns in urban parks. Study sites were Jungang, Dlseong, and Beomeo park, where located Taegu city-Key results obtained through a series of investigation were as follows : When Users come in and out urban parks, most orientations of their use routes were counterclockwise, and not in such cases, greatly affected by facilities arrangement. There were a large number of users in the main route placed the principal facilities. Users' use route patterns were grouped by their characteristics, which were circulation, semi-circulation, irregular, and piston type. And all the types except piston type can be subdivided into spoon and loope type. Factors analysis to the types produced five meaningful patterns of variables. Five factors were named as dimension of characteristics : Park composition factor, facilities use factor, users' personal factor, park use behavioral factor, routes choice factor.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.9
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• pp.50-58
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• 1992

A new algorithm for filling the interior of contours and labelling each filled region concurrently is presented. Filling is simply accomplished by inversion method. The labelling information in every scan lines is extracted directly from current direction of chain code so that the proposed algorithm needs less comparision and is more efficient. The contours are followed by two different directions, clockwise for the outer contour and counterclockwise for the inner contour to get filling and labelling information. This algorithm can be applied in case that contours are nested or regions are continous. Simulataneously the proposed algorithm can find the structure tree of object without additional post processing.

• Transactions on Electrical and Electronic Materials
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• v.13 no.3
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• pp.162-164
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• 2012

In this study, we fabricate Pt nanoparticle (NP)-embedded MOS capacitors at room temperature and investigate their memory characteristics. The Pt NPs are separated from each other and situated between the tunnel and control oxide layers. The average size and density of the Pt NPs are 4 nm and $3.2{\times}10^{12}cm^{-2}$, respectively. Counterclockwise hysteresis with a width of 3.3 V is observed in the high-frequency capacitance-voltage curve of the Pt NP-embedded MOS capacitor. Moreover, more than 93% of the charge remains even after $10^4$ s.

• Journal of The Korean Astronomical Society
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• v.54 no.5
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• pp.157-170
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• 2021

We investigate flow and magnetic structure of a solar prominence with a focus on how the magnetic field originally determined by subsurface dynamics gives rise to the structure. We perform a magnetohydrodynamic simulation that reproduces the self-consistent evolution of a flow and the magnetic field passing freely through the solar surface. By analyzing Lagrangian displacements of magnetized plasma elements, we demonstrate the flow structure that is naturally incorporated to the magnetic structure of the prominence formed via dynamic interaction between the flow and the magnetic field. Our results explain a diverging flow on a U-loop, a counterclockwise downdraft along a rotating field line, acceleration and deceleration of a downflow along an S-loop, and partial emergence of a W-loop, which may play key roles in determining structural properties of the prominence.

• Ocean Systems Engineering
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• v.14 no.2
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• pp.141-156
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• 2024

The turbine system converts the kinetic energy of water flow to electricity by rotating the rotor in a restricted waterway between the seabed and free surface. A turbine system's immersion depth and rotation direction are significantly critical in the turbine's performance along with the shape of the rotor. This study has investigated the hydrodynamic performance of the Savonius hydrokinetic turbine (SHT) according to the immersion depth and rotation direction using computational fluid dynamics (CFD) simulations. The instantaneous torque, torque coefficient, and power coefficients are calculated for the immersion ratios Z/D ranging [0.25, 3.0] and both clockwise (CW) and counterclockwise (CCW) rotations. A flow visualization around the rotor is shown to clarify the correlation between the turbine's performance and the flow field. The CFD simulations show that the CCW rotation produces a higher power at shallow immersion, while the CW rotation performs better at deeper immersion. The immersion ratio should be greater than the minimum of Z/D=1.0 to obtain the maximum power production regardless of the rotation direction.

• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.113-127
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• 1999

The purpose of this study is to investigate the stability of counterclockwise rotation of mandible by sagittal split ramus osteotomy to correct the skeletal Class III malocclusion with anterior open bite. Twenty five skeletal Class III open bite patients(mean age 20.6 years) who were treated by the sagittal split ramus osteotonues with rigid fixation were examined in this study. Cephalometric radiographs were taken for each Patients Preoperative(T1), ewly Postoperative(T2), and late postoperative Period(T3). Mean postoperative period was 8.0 months. Cephalometric analysis was done and data from T1, T2, and T3 were analyzed statistically by Paired t-test and Pearson correlation analysis. The following results were obtained. 1. Mandibular plane angle decreased $2.9^{\circ}$ and mandibular occlusal plane angle related to SN Plane decreased $2.7^{\circ}$ after orthognathic surgery(T2). At 6 months after orthognathic surgery(T3), mandibular plane angle increased $1.0^{\circ}$, but mandibular occlusal plane angle did not changed. 2. The amount of horizontal relapse long time after orthognathic surgery(T3) was 1.6 mm at B point and it was $22\%$ of the total posterior movements. There was no vertical relapse in the anterior facial height. 3. The related factor with horizontal relapse at late postoperative period was mandibular plane angle(p<0.01). The related factors with decreasing posterior facial height were amount of mandibular setback(p<0.01), increasing of mandibular ramus height(p<0.01), and decrease of the mandibular plane angle during operation(p<0.01). 4. There was no relationship between the amount of changes in mandibular occlusal plan angle during operation and the amount of relapse after surgery.

• The korean journal of orthodontics
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• v.22 no.3 s.38
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• pp.531-556
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• 1992

The majority of the commonly used protraction headgears for the protraction of small and/or retropositioned maxilla not allow a change in the point of force application or direction of the force delivery to attain predictable results because of the position of the upper and lower lips to avoid discomfort to the patient. The purpose of this study was to investigate the initial reaction of maxillofacial complex according to the change of force variables such as direction and point of force application with designing an antenna type-modified protraction head gear. A macerated human skull with well aligned upper teeth was used to experimental model and the investigation was done by double exposure holographic interferometry. Fringe patterns of each protraction conditions were compared and analized. The results were as follows. (Frontal view) 1. The Counterclockwise rotation of the maxilla was showed by parallel protraction to occlusal plane and the fringe was decreased in number as higher point of force application. 2. Generally, the number of fringe was increased in 500gm of protraction force than in 300gm. 3. When apply the protraction force to the maxilla with rapid palatal expansion, the direction of fringe patterns was differed from the protraction without expansion. 4. In most of cases, the counterclockwise rotation was decreased in case of the direction of the force is $20^{\circ}$ downward to occlusal plane compared to the parallel direction. 5. At the point of force application is 15mm above and the direction of force is 20 downward to occlusal plane , the translation of the maxillary complex was showed. (Lateral view) 6. The direction of fringe patterns of the facial bones were differed each other by the sutures, and showed almost parallel when apply the 300gm and 500gm of protraction force. 7. In case of rapid palatal expansion with protraction of the maxilla, the fringe patterns between the maxillary area and the area from the posterior of the maxillary first molar to the pterygomaxillary fissure were differed. In case without rapid palatal expansion, the changes of direction and point of the force application did not affect to the direction and the number of the fringe patterns.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.364-370
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• 2009

With time, the stable management of turbidity is becoming more important in the water treatment process. So optimization of flocculation is important for the improvement of the sedimentation efficiency. we evaluated the hydrodynamic behavior in the rotation direction (clock-wise, counterclock-wise) of the flocculator in the flocculation basin using Computational Fluid Dynamics (CFD). The results of the CFD simulation, in cases where flocculators rotate in a clockwise direction, a stronger flow is formed near the surface of the water where the rotating direction and current of flow correspond. The variance and standard deviation of the flux are about 8.5 and 2.9 respectively. In contrast, in the case of a counterclockwise direction, a stronger flow is formed near the bottom of the basin. The variance and standard deviation of the flux are about 5.3 and 2.3, respectively. The effluent flux is affected more by the third flocculator spin than the first and second flocculator spins. The third flocculator spinning in the counterclockwise direction is better for the uniform flow of the sedimentation basin than the third flocculator spinning in the clockwise direction