• Journal of Oral Medicine and Pain
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• v.24 no.2
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• pp.207-217
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• 1999

This study was performed to investigate the effects of clutch adaptation on the mandibular rotational torque movement in normal people. 69 dental students were selected for the study. Their mean age were 23.6 years and they did not present any signs and symptoms of temporomandibular disorders. $BioEGN^{(R)}$ with $Rotate^{(R)}$ program was used to observe and record the amount of mandibular rotational torque on protrusion, on right excursion, on left excursion, and on comfortable wide opening movement. The natural tooth contact movement and the movement with clutch were performed in the above four each mandibular movement. Clutch was made by the method used in $Pantronic^{(R)}$ clutch fabrication. Distance of slant frontal which was translatory trajectory in frontal plane and degree of rotational torque in horizontal and in frontal plane were recorded. The data obtained were processed with SPSSWIN program and the results were as follows : 1. Distance of slant frontal in each mandibular movement generally increased with clutch. 2. Degree of rotational torque in horizontal and in frontal plane on protrusion and on lateral excursions did not increase with clutch, but the degree on wide opening increased with clutch. 3. Degree of rotational torque in horizontal plane on protrusion and on lateral excursions did not show any difference between right and left side, but the degree in frontal plane on protrusion and on lateral excursions showed significant difference between right and left side. 4. Total amount of rotational torque from right and left sides on protrusion and lateral excursions were not increased with clutch, but the degree on wide opening movement was increased with clutch. And in this case, degree in horizontal plane was larger than that in frontal plane. 5. Correlation between total amount of rotational torque in horizontal plane and that in frontal plane were highly significant on protrusion and on lateral excursions with or without clutch, but the significant correlation on wide opening without clutch became not significant with clutch.

• Structural Engineering and Mechanics
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• v.31 no.6
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• pp.679-696
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• 2009

The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann's series. In order to implement this approach, the special recurrent relations for half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading (degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.

• Structural Engineering and Mechanics
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• v.84 no.5
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• pp.675-684
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• 2022

The conventional single-degree-of-freedom (SDOF) system is appropriate for dynamic response analysis of paneltype structures without an opening. However, the typical building structures usually have four-sided fixed walls having an opening. Therefore, it may induce a considerable error when dynamic responses are estimated based on the conventional SDOF system, since the SDOF system cannot consider the effect of an opening during the SDOF analysis. For this reason, this study proposes a new SDOF system to consider the effect of an opening by adjusting its load-mass factor. The load-mass factor can be modified based on the assumption that the behaviors of the four-sided fixed wall with an opening is very similar to the behaviors of the same size wall without an opening, when the uniformly distributed blast loaded area is identical. In order to confirm a feasibility of the proposed SDOF system, a series of numerical simulations were carried out for the four-sided fixed reinforced concrete (RC) wall under a blast load. The dynamic responses estimated from the proposed SDOF system and the conventional SDOF system were compared with the dynamic responses evaluated from the finite element (FE) analysis. Especially, for the maximum dynamic responses except for 50% opening case, the proposed SDOF system had about 1.1% to 25.7% normalized errors while the conventional SDOF system had about 4.1% to 49.1% normalized errors.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.3
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• pp.125-132
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• 2015

Objectives: The purpose of this study was to clarify which findings in magnetic resonance imaging (MRI) are good predicators of pain and mouth opening limitation in patients with temporomandibular joint (TMJ) internal derangement (ID). Materials and Methods: Clinical examinations for pain and mouth opening limitation were conducted for suspected TMJ ID. MRI scans were taken within a week of clinical examinations. On the oblique-sagittal plane image, readings were obtained in terms of the functional aspect of disc position, degree of displacement, disc deformity, joint effusion, and osteoarthrosis. Multiple logistic regression analyses were conducted to identify the predictors of pain and mouth opening limitation. Results: A total of 48 patients (96 TMJs) were studied, including 39 female patients and 9 male patients whose ages ranged from 10 to 65 years. The resultant data showed significant correlations between pain and the MR imaging of the degree of disc displacement (P<0.05). The probability of there being pain in moderate to significant cases was 9.69 times higher than in normal cases. No significant correlation was found between mouth opening limitation and MRI findings. Conclusion: We identified a significant correlation between clinical symptoms and MRI findings of ID. The degree of anterior disc displacement may be useful for predicting pain in patients with TMJ ID.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1674-1685
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• 2022

The ball valve is an important device in the pipeline transportation system of nuclear power plants. Its operational stability and safety directly affect the normal working of nuclear power plants. In this study, the transient numerical simulation of the opening and closing process of a ball valve was conducted on the basis of the flow interruption capability experiment of the ball valve by using the moving mesh method and inlet and outlet variable boundary conditions. The flow rate and pressure difference with time of the opening and closing process of the ball valve were studied. The internal flow characteristics of the ball valve under different relative openings were analyzed in conjunction with the typical back-step flow structure. Results show that the transient numerical results agree well with the experimental results. The internal flow characteristics of the ball valve are similar at the same opening during opening and closing process. At small opening, the spool and outlet channels easily form a back-step flow structure. The disappearance and generation of backflow vortices during opening and closing occur at 85% opening and 75% opening, respectively. With the decrease in opening degree, the difference in vortex core area in the flow channel of the ball valve spool in the opening and closing process gradually appears. The research results provide some reference value for the design and optimization of ball valves.

• Journal of Power System Engineering
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• v.20 no.1
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• pp.5-10
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• 2016

Swing check valve is opened when the flow direction is forward, when the flow is reversed, the valve is automatically closed by back pressure. In this study, the internal flow field analysis of the valve was conducted by Fluent. The working fluid used in the study, using liquefied methane $-165^{\circ}C$ (CH4) and velocity field, pressure field, pressure drop coefficient were simulated by varying separately the opening divergence into four intervals from 0 to 100%. The approximate research result are as follow : When the opening divergence is smaller, it appears high pressure on the upstream side, this value is relaxed when the opening divergence is large. Flow rate coefficient of the valve shows a larger value as the degree of opening becomes larger, confirming that the check valve used in the study is in the effective flow rate counting range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.12
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• pp.1588-1595
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• 2000

Natural convection heat transfer in an enclosure with an opening in the right veritcal wall and a heat source at the bottom surface is investigated using a holographic interferometric technique. The effects of the opening length, divider length attached to the top wall, and heater temperature on the temperature distribution are examined. The opening length as well as the divider length greatly affects the degree of inflow and outflow of air. In the case of small opening length, the opening doesnt affect much the upward warm air flow resulting in the symmetric temperature distribution .The upward flow in hindered by the divider resulting in the decrease of heat transfer from the heater region to the upper region. The longest divider shows the highest temperature in the lower region of enclosure. In the case of large opening length, the inward cold flow moves the upward flow to the left direction. Among the cases of different divider length, the case of H(sub)d=0.25H shows the highest temperature in the lower region of enclosure.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.3
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• pp.43-47
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• 2015

Purpose : The aim of this study was to report a follow-up study on the prognosis following the arthrocentsis for the painful temporomandibular dysfunction not responsible to the conservative splint therapies. Arthrocentsis of TMJ is a simple precedure that can be performed in the out-patient clinic under the local anesthesia without any reported complications. Method : Seventy patients had been followed after the arthrocentsis for over 6 months. Maximum mouth opening, TMJ pain, TMJ noise, and their changes by time were examined and compared statistically. The effectiveness of the treatment was evaluated in terms of the postoperative range of maximal mouth opening (MMO) and the degree of postoperative pain score. Predictors which was analyzed were age, duration of painful locking, MMO, the degree of pain, preoperative clicking and the amounts of irrigation fluid. Result : The result of this study were as follow; 1) Mouth opening was improved from 32.6 mm to 42.4 mm in the maximum inter-incisal distance. 2) TMJ pain was decreased in 45.7%. 3) TMJ clicking and noise disappeared in 60.0%, but recurred in 40.0%. Conclusion : Amounts of irrigated solution recovered to normal MMO and the appeareance of perioperative clkicking may be predictors of the successful results of arthrocenetesis of ADD without reduction of TMJ.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.9
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• pp.699-703
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• 2012

The performance of the typical VAV dampers; blade type, venturi type and blade-orifice type, for the circular duct, is obtained by measuring the volume flow rate as a function of the opening degree. The performance features are discussed by comparing the volume flow rate of each damper. It is shown that the blade-orifice type damper, recently developed, is excellent in its linearity of the performance and that it is worse than the blade type but much better than the venturi type in its flow resistance.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.393-397
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• 2013

관내의 유량을 제어하는 볼 밸브(ball valve)는 개폐각도(opening degree)가 커짐에 따라 출구에서 유속이 증가하고 밸브(valve)의 입 출구 간 압력강하(pressure drop)가 증가한다. 출구에서의 압력이 작동유체의 포화증기압보다 낮아질 때 공동현상(cavitation)이 발생한다. 관내에서의 공동현상은 배관시스템의 진동 및 소음, 부식 등에 있어서 악영향을 미칠 수 있으므로 설계에 매우 중요한 요소이다. 버터플라이 밸브를 비롯한 다른 밸브에서는 공동현상감소에 대한 연구가 많이 이루어졌다. 이에 본 연구에서는 볼 밸브 내 유동 특성(characteristic of flow)과 볼 밸브의 입출구간 압력강하를 줄이는 연구를 수행하였다. 개폐 각도와 그에 따른 압력강하와의 관계를 Edison_전산열유체를 사용하여 분석하고 공동현상을 감소시킨 볼 밸브의 설계를 제시 하였다.