• Journal of Radiation Protection and Research
• /
• v.36 no.1
• /
• pp.35-43
• /
• 2011

The PHENIX Experiment is the largest of the four experiments that have taken data at the Relativistic Heavy Ion Collider. PHENIX, the Pioneering High Energy Nuclear Interaction eXperiment, is designed specifically to measure direct probes of the collisions such as electrons, muons, and photons. The primary goal of PHENIX is to discover and study a new state of matter called the Quark-Gluon Plasma. Among many particles, muons coming from W-boson decay gives us key information to analyze the spin of proton. Resistive plate chambers are proposed as a suitable solution as a muon trigger because of their fast response and good time resolution, flexibility in signal readout, robustness and the relatively low cost of production. The RPC detectors for upgrade were assembled and their performances were evaluated. The procedure to make the detectors better was optimized and described in detail in this thesis. The code based on ROOT was written and by using this the performance of the detectors made was evaluated, and all of the modules for north muon arm met the criteria and installation at PHENIX completed in November 2009. As RPC detectors that we made showed fast response, capacity of covering wide area with a resonable price and good spatial resolution, this will give the opportunity for applications, such as diagnosis and customs inspection system.

• Journal of the Society of Naval Architects of Korea
• /
• v.58 no.4
• /
• pp.243-252
• /
• 2021

The present study aims to investigate the interaction of a wire-type turbulence stimulator and the laminar boundary layer on a flat plate by flow field measurement. For the towing tank tests, a one-dimensional Laser Doppler Velocimetry (LDV) attached on a two-axis traverse was used to measure the streamwise velocity component of the boundary layer flow in zero pressure gradient, disturbed by a turbulence stimulator. The wire diameter was 0.5 and 1.0 mm according to the recommended procedures and guidelines suggested by the International Towing Tank Conference. Turbulence development by the stimulator was identified by the skin friction coefficient, mean and Root Mean Square (RMS) of the streamwise velocity. The laminar boundary layer with the absence of the wire-type stimulator was similar to the Blasius solution and previous experimental results. By the stimulator, the mean and RMS of the streamwise velocity were increased near the wall, showing typical features of the fully developed turbulent boundary layer. The critical Reynolds number was reduced from 2.7×10⁵ to 1.0×10⁵ by the disturbances caused by the wire. As the wire diameter and the roughness Reynolds number (Rek) increased, the disturbances by the stimulator increased RMS of the streamwise velocity than turbulent boundary layer.

• Physical Therapy Rehabilitation Science
• /
• v.11 no.3
• /
• pp.311-320
• /
• 2022

Objective: To investigate the reliability and validity of static balance measurements using an acceleration sensor and a gyroscope sensor in smart phone inertial sensors. Design: Equivalent control group pretest-posttest. Methods: Subjects were forty five healthy adults aged twenty to fifty-years-old who had no disease that could affect the experiment. After pre-test, all participants wore a waist band with smart phone, and conducted six static balance measurements on the force plate twice for 35 seconds each. To investigate the test-retest reliability of both smart phone inertial sensors, we compared the intra-correlation coefficient (ICC 3, 1) between primary and secondary measurements with the calculated root mean scale-total data. To determine the validity of the two sensors, it was measured simultaneously with force plate, and the comparision was done by Pearson's correlation. Results: The test-retest reliability showed excellent correlation for acceleration sensor, and it also showed excellent to good correlation for gyroscope sensor(p<0.05). The concurrent validity of smartphone inertial sensors showed a mostly poor to fair correlation for tandem-stance and one-leg-stance (p<0.05) and unacceptable correlation for the other postures (p>0.05). The gyroscope sensor showed a fair correlation for most of the RMS-Total data, and the other data also showed poor to fair correlation (p<0.05). Conclusions: The result indicates that both acceleration sensor and gyroscope sensor has good reliability, and that compared to force plate, acceleration sensor has unacceptable or poor correlation, and gyroscope sensor has mostly fair correlation.

• Structural Engineering and Mechanics
• /
• v.91 no.6
• /
• pp.643-656
• /
• 2024

The prediction of the moment rotation behavior of semi-rigid connections has been the subject of extensive research. However, to improve the accuracy of these predictions, there is a growing interest in employing machine learning algorithms. This paper investigates the effectiveness of using Multi-gene genetic programming (MGGP) to predict the moment-rotation behavior of flush-end plate connections compared to that of artificial neural networks (ANN) and previous studies. It aims to automate the process of determining the most suitable equations to accurately describe the behavior of these types of connections. Experimental data was used to train ANN and MGGP. The performance of the models was assessed by comparing the values of coefficient of determination (R²), maximum absolute error (MAE), and root-mean-square error (RMSE). The results showed that MGGP produced more accurate, reliable, and general predictions compared to ANN and previous studies with an R² exceeding 0.99, an RMSE of 6.97, and an MAE of 38.68, highlighting its advantages over other models. The use of MGGP can lead to better modeling and more precise predictions in structural design. Additionally, an experimentally-based regression analysis was conducted to obtain the rotational capacity of FECs. A new equation was proposed and compared to previous ones, showing significant improvement in accuracy with an R² score of 0.738, an RMSE of 0.014, and an MAE of 0.024.

• The korean journal of orthodontics
• /
• v.41 no.1
• /
• pp.6-15
• /
• 2011

Objective: The aim of this study was to evaluate the biomechanical aspects of peri-implant bone upon root contact of orthodontic microimplant. Methods: Axisymmetric finite element modeling scheme was used to analyze the compressive strength of the orthodontic microimplant (Absoanchor SH1312-7, Dentos Inc., Daegu, Korea) placed into inter-radicular bone covered by 1 mm thick cortical bone, with its apical tip contacting adjacent root surface. A stepwise analysis technique was adopted to simulate the response of peri-implant bone. Areas of the bone that were subject to higher stresses than the maximum compressive strength (in case of cancellous bone) or threshold stress of 54.8MPa, which was assumed to impair the physiological remodeling of cortical bone, were removed from the FE mesh in a stepwise manner. For comparison, a control model was analyzed which simulated normal orthodontic force of 5 N at the head of the microimplant. Results: Stresses in cancellous bone were high enough to cause mechanical failure across its entire thickness. Stresses in cortical bone were more likely to cause resorptive bone remodeling than mechanical failure. The overloaded zone, initially located at the lower part of cortical plate, proliferated upward in a positive feedback mode, unaffected by stress redistribution, until the whole thickness was engaged. Conclusions: Stresses induced around a microimplant by root contact may lead to a irreversible loss of microimplant stability.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.36 no.4
• /
• pp.154-160
• /
• 2014

Purpose: The efficiency of an anchor plate placed during orthognathic surgery via minimal presurgical orthodontic treatment was evaluated by analyzing the mandibular relapse rate and dental changes. Methods: The subjects included nine patients with Class III malocclusion who had bilateral sagittal split osteotomy at the Division of Oral and Maxillofacial Surgery, Department of Dentistry in Ajou University Hospital, after minimal presurgical orthodontic treatment. During orthognathic surgery, anchor plates were placed at both maxillary buttresses. The anchor plates were used to move maxillary teeth backward and for maximum anchorage of Class III elastics to minimize mandibular relapse during the postoperative orthodontic treatment. The lateral cephalometric X-ray was taken preoperatively (T0), postoperatively (T1), and one year after the surgery (T2). Seven measurements (distance from Pogonion to line Nasion-Nasion perpendicular [Pog-N Per.], angle of line B point-Nasion and Nasion-Sella [SNB], angle of line maxilla 1 root-maxilla 1 crown and Nasion-Sella [U1 to SN], distance from maxilla 1 crown to line A point-Nasion [U1 to NA], overbite, overjet, and interincisal angle) were taken. Measurements at T0 to T1 and T1 to T2 were compared and differences tested by standard statistical methods. Results: The mean skeletal change was posterior movement by $13.87{\pm}4.95mm$ based on pogonion from T0 to T1, and anterior movement by $1.54{\pm}2.18mm$ from T1 to T2, showing relapse of about 10.2%. There were significant changes from T0 to T1 for both Pog-N Per. and SNB (P<0.05). However, there were no statistically significant changes from T1 to T2 for both Pog-N Per. and SNB. U1 to NA that represents the anterior-posterior changes of maxillary incisor did not differ from T0 to T1, yet there was a significant change from T1 to T2 (P<0.05). Conclusion: This study found that the anchor plate minimizes mandibular relapse and moves the maxillary teeth backward during the postoperative orthodontic treatment. Thus, we conclude that the anchor plate is clinically very useful.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.36 no.2
• /
• pp.88-94
• /
• 2020

Purpose: The purpose of this study was to analyze the sagittal root position of maxillary anterior teeth and report the frequency of each classification in Korean for immediate implant placement. Materials and Methods: A retrospective review of cone-beam computed tomography (cone-beam CT) images was conducted on 120 patients (60 male and 60 female) who fulfilled the inclusion criteria. After reorientation of the axis, cone-beam CT images were evaluated and the relationship of the sagittal root position (SRP) of the maxillary anterior teeth to its associated osseous housing was recorded. Class I, II, and III were classified respectively when the root was positioned on the labial, central, and palatal aspect of the alveolar bone. Class IV was the position that at least two thirds of the root is engaging both the labial and palatal cortical plates. Then, the angulation of the root axis and the alveolar bone axis was measured. Descriptive statistics and Kruskal-Wallis test were used to compare the angulation according to the root position and SRP class. Results: The frequency distribution of sagittal root position of maxillary anterior teeth indicated that 81.1%, 10.3%, 1.9%, and 6.7% were classified as Class I, II, III, and IV, respectively. The sagittal angulation at approximately 77.5% of central incisor, lateral incisor, and canine was < 20 degrees, but the angle at more than 42.7% of canine was ≥ 20 degrees. Within the class, the angulation was statistically significantly greater in Class I (16.19) compared to Class II (8.72) and Class III (9.93), and smaller in Class IV (3.79). Conclusion: Within the limitation of this study, a majority of the maxillary anterior roots were positioned close to the buccal cortical plate. However, some roots have very thin alveolar bone and sagittal angulation larger than 30 degrees. Therefore, cone-beam CT analyses of the sagittal root position and the sagittal angulation are recommended for the selection of the appropriate dental implant treatment approach.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.52 no.2
• /
• pp.213-219
• /
• 2007

It has been well established that aluminum (Al) inhibits root tip growth rapidly in acid soil. We report the correlation between Al induced growth inhibition and impaired $H^+-flux$ in mung bean (Vigna radiate L. cv. Kumsung). The root growth inhibition was dependent on Al concentration (0, 10, 25, 50, $100{\mu}M$) and exposure time (12 and 24 h). Using Hematoxylin staining, it was observed that the root damage was occurred preferentially in regions with high Al accumulation. Using the pH indicator, it was shown that the surface pH of root tip was strongly alkalized in the control whereas changed only slightly in the $50{\mu}M$ Al-treated root. The $H^+-ATPase$ activity of plasma membrane vesicles was inhibited by 56% in the Al-treated roots compared to control root. Decrease in the amount of the plasma membrane $H^+-ATPase$ (100 kDa) translation in the plant roots under Al stress was demonstrated by Western blot analysis. These results indicate that the dynamics of $H^+-flux$ across the root tip play an important role in root growth under Al stress.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.1
• /
• pp.73-80
• /
• 2006

In order to compute the radiated sound from a vibrating structure, the Rayleigh's integral equation has to be derived from the Helmholtz equation using Green's function. Generally, the surface velocity in the Rayleigh's integral equation uses the root mean square(rms) velocity. The calculation value is too large, because it's not considered cancelation. On the other hand. using the complex velocity, the sound pressure is calculated too small, because it considers that sound is perfectly canceled out. Therefore, this thesis proposes a correction factor(CF) which considers vibration modes and the method by which to calculate the radiating sound pressure. The theoretical results are compared with the experimental values, and the proposed method can be verified with confluence.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.4
• /
• pp.318-323
• /
• 2004

When a strong electric field is applied between a sharply curved electrode and a blunt surface, the corona may result in a gas movement in the electrode gap which is directed toward the blunt surface. That is called the corona wind. It enhances heat and mass transfer between the surface and the surrounding gas. Moreover such enhancement causes no noise or vibration, which can be applied in complex, isolated geometries, and allows simple control of surface temperatures. This paper examines the relationship between the corona wind and the relative humidity. The facility consists of high voltage power supply thin tungsten wire, plate electrode, multimeter, microammeter and flow meter. Gas velocity is a linear function of voltage, relative humidity and is proportional to the square root of the current. The maximum velocities for the positive and negative corona discharge are 1.9 m/s (2.74 CMM/m), 1.5 m/s(2.15 CMM/m), respectively.