• 한국운동역학회지
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• 제23권1호
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• pp.63-76
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• 2013

The purpose of this study was to investigate the effects of knee joint muscle fatigue and overweight on the angular displacement and moments of the lower limb joints during landing. Written informed consent forms, which were approved by the human subject research and review committee at Dong-A University, were provided to all subjects. The subjects who participated in this study were divided into 2 groups: a normal weight group and an overweight group, consisting of 15 young women each. The knee joint muscle fatigue during landing was found to increase the dynamic stability by minimizing the movements of the coronal and horizontal planes and maintaining a more neutral position to protect the knee. The effect of body weight during landing was better in the normal weight group than in the overweight group, with the lower limbs performing their shock-absorbing function in an efficient manner through increased sagittal movement. Therefore, accumulated fatigue of knee joint muscles or overweight may be highly correlated with the increase in the incidence of injury during landing after jumping, descending stairs, and downhill walking.

• 한국강구조학회 논문집
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• 제27권1호
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• pp.53-61
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• 2015

인장이음은 고장력 볼트의 체결력과 모재 그리고 고장력 볼트의 내력을 직접적으로 활용하고, 볼트구멍의 가공수나 체결개소의 감소, 피로저항성 등에 있어 유리하며 때문에 역학적으로 매우 효율적인 연결이다. 이러한 인장이음은 교량의 거더와 가로보의 이음, 주탑의 수평이음, 보-기둥 연결부, 바닥판 단부 2차부재 연결부, 브라켓 등에 적용될 수 있다. 본 연구에서는 인장이음의 역학적 거동을 파악하기 위해서 T-인장이음에 대한 정적실험을 수행하였다. 시험변수는 고장력 볼트의 직경, 플렌지 두께 및 체결력 감소이며, 인장이음의 파괴양상과 내력, 플랜지 두께와 고장력 볼트의 직경의 영향, 체결력의 영향에 대해 분석하였다.

• Journal of Oral Medicine and Pain
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• 제19권2호
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• pp.193-203
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• 1994

The author performed this study for investigation of the magnitude of mandibular positional change caused by joint sound during mandibular opening and closing movement. There have been many studies stated mandibular border movement or other functional movement, and there also have been many studies reported clicking sound related to mandibular movement speed, trajectory and clinicl course of temporomandibular disorders(TMDs), but there have not been so many studies stated spatial mandibular position accompanied by joint sound. For this study 46 TM joint from the patients with TMDs were used and they were compared by character and occuring phase of the joint sound. Synchronized data which were amplitude and frequency of joint sound and amount of mandibular positional change were collected through sonopak and BioEGN rotate of Biopak system, respectively. Mandibular position was analyzed for translational and rotational movement change between before and after joint sound. The obtained data were processed with SAS program and summary of this paper were as follows : 1. Mean value of the amount of translational movement in whole joints were 6.0mm in vertical direction, 3.3mm in anteroposterior direction and 0.8mm in lateral direction between before and after joint sound. 2. Mean value of the amount of translational movement in clicking joinnts showed slightly increased tendency than in popping joints. 3. The amount of mandibular change in translational movement during closing phase were more than during opening phase. 4. The amount of mandibular rotational change in whole joints were $1.1^{\circ}$, 1.0mm in frontal plane and $0.9^{\circ}$, and 0.8mm in horizontal plane. 5. The amount of rotational movement were more in clicking joints than in popping joints and were more during closing phase than during opening phase, but statistically significance were showed only in frontal plane.

• Structural Engineering and Mechanics
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• 제69권2호
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• pp.221-230
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• 2019

In this paper, shear behavior of non-persistent joint surrounded in concrete and gypsum layers has been investigated using experimental test and numerical simulation. Two types of mixture were prepared for this study. The first type consists of water and gypsum that were mixed with a ratio of water/gypsum of 0.6. The second type of mixture, water, sand and cement were mixed with a ratio of 27%, 33% and 40% by weight. Shear behavior of a non-persistent joint embedded in these specimens is studied. Physical models consisting of two edge concrete layers with dimensions of 160 mm by 130 mm by 60 mm and one internal gypsum layer with the dimension of 16 mm by 13 mm by 6 mm were made. Two horizontal edge joints were embedded in concrete beams and one angled joint was created in gypsum layer. Several analyses with joints with angles of $0^{\circ}$, $30^{\circ}$, and $60^{\circ}$ degree were conducted. The central fault places in 3 different positions. Along the edge joints, 1.5 cm vertically far from the edge joint face and 3 cm vertically far from the edge joint face. All samples were tested in compression using a universal loading machine and the shear load was induced because of the specimen geometry. Concurrent with the experiments, the extended finite element method (XFEM) was employed to analyze the fracture processes occurring in a non-persistent joint embedded in concrete and gypsum layers using Abaqus, a finite element software platform. The failure pattern of non-persistent cracks (faults) was found to be affected mostly by the central crack and its configuration and the shear strength was found to be related to the failure pattern. Comparison between experimental and corresponding numerical results showed a great agreement. XFEM was found as a capable tool for investigating the fracturing mechanism of rock specimens with non-persistent joint.

• 대한치과보철학회지
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• 제31권4호
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• pp.468-481
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• 1993

The Purpose of this study was to analyze the stresses and displacements of various post and core. The Finite element models of central incisors were divided into seven types according to the various amount of remaining tooth structures. $10kgf/mm^2$ force was applied respectively as follows : 1) Horizontal on the labial surface 2) $26^{\circ}$ diagonal direction on the lingual surface. Material property, geometry, and load condition of each model were inputted to the two dimensional ANSYS 4.4A finite element program : stresses and displacements were analyzed. Results were follows : 1. In the case of $130^{\circ}$ shoulder post and core, Maximum tensile and shear stresses were observed in the crown margin. 2. Maximum shear stress was about 29% reduced by contrabevel. 3. In the case of 1mm axial tooth structure, Maximum tensile stress observed in the dentin. 4. In the case of but joint of cervix, Maximum stress concentration was observed in the dentin by the inclined and horizontal force. 5. Horizontal force produced the extraordinary high stresses in dentin and supporting structures. 6. The amount of remaining tooth structure affected the level of stress significantly and it determined the location of stress concentration.

• 한국정밀공학회지
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• 제18권8호
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• pp.71-78
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• 2001

In GMA(Gas Metal Arc)Welding, the weld size that is a locally melted area of a workpiece is one of the most important considerations in determining the strength of a welded structure. Variations in the weld power and the welding heat flux may affect the weld pool formation and ultimately the size of the weld. Therefore, an accurate prediction of the weld size requires a precise analysis of the weld thermal cycle. In this study, a model which can estimate the weld bead geometry and a method for thermal analysis, including the model, are suggested. In order to analyze the weld bead geometry, a mathematical model was developed with transformed coordinates to apply to the horizontal fillet joints. A heat flow analysis was performed with a two dimensional finite element model that was adopted for computing the base metal melting zone. The reliability of the proposed model and the thermal analysis was evaluated through experiments, and the results showed that the proposed model was very effective for predicting the weld bead shape and good correspondence in melting zone of the base metal.

• Geomechanics and Engineering
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• 제11권4호
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• pp.457-469
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• 2016

Steep rock slope with water-filled tension crack will happen to overturn around the toe of the slope under seismic loading. This failure type is completely different from the common toppling failure occurring in anti-dipping layered rock mass slopes with steeply dipping discontinuities. This paper presents an analytical approach to determine the seismic factor of safety against overturning for an intact rock mass slope with water-filled tension crack considering horizontal and vertical seismic coefficients. This solution is a generalized explicit expression and is derived using the moment equilibrium approach. A numerical program based on discontinuous deformation analysis (DDA) is adopted to validate the analytical results. The parametric study is carried out to adequately investigate the effect of horizontal and vertical seismic coefficients on the overall stability against overturning for a saturated rock slope under two water pressure modes. The analytical results show that vertically upward seismic inertia force or/and second water pressure distribution mode will remarkably decrease the slope stability against overturning. Finally, several representative design charts of slopes also are presented for the practical application.

• Structural Engineering and Mechanics
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• 제59권4호
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• pp.653-669
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• 2016

Recent earthquakes worldwide show that a significant portion of the earthquake shaking happens in the vertical direction. This phenomenon has raised significant interests to consider the vertical ground motion during the seismic design and assessment of the structures. Strong vertical ground motions can alter the axial forces in the columns, which might affect the shear capacity of reinforced concrete (RC) members. This is particularly important for non-ductile RC frames, which are very vulnerable to earthquake-induced collapse. This paper presents the detailed nonlinear dynamic analysis to quantify the collapse risk of non-ductile RC frame structures with varying heights. An array of non-ductile RC frame architype buildings located in Los Angeles, California were designed according to the 1967 uniform building code. The seismic responses of the architype buildings subjected to concurrent horizontal and vertical ground motions were analyzed. A comprehensive array of ground motions was selected from the PEER NGA-WEST2 and Iran Strong Motions Network database. Detailed nonlinear dynamic analyses were performed to quantify the collapse fragility curves and collapse margin ratios (CMRs) of the architype buildings. The results show that the vertical ground motions have significant impact on both the local and global responses of non-ductile RC moment frames. Hence, it is crucial to include the combined vertical and horizontal shaking during the seismic design and assessment of non-ductile RC moment frames.

• 한국운동역학회지
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• 제13권1호
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• pp.51-62
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• 2003

This study was attempted to kinematical characteristics of the El-grip swing with 1turn to el-grip in elite horizontal bar for the purpose of improving performance. The subjects were three males who were 2002 Busan Asian Games in men's team. The three dimensional motion analysis with DLT method was executed using three video cameras of analyzing the actual competition situation. In point of analyzing the actual competition situation, it is expected that gymnastics and coaches have the effective informations, and the following conclusion had resulted. 1. In case of release, It is impotant to make fast horizontal velocity of CM, high vertical position of CM, large hip and shoulder angle. Also It should be performed release motion of trunk rotation angle(+). 2. During LHR the action should be made at higher position than the CM and the shoulder joint is moving within $127{\pm}16.82$. It is important to make large lunk rotation angle. 3. During Hop, the RHR motion should be done in high position with short time and fast twisting action and to reduce the vertical speed is important.

• 한국산학기술학회논문지
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• 제17권4호
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• pp.400-413
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• 2016

80 MPa급 고강도 콘크리트가 강거더의 압축 플랜지로 대체하는 아중합성 거더의 경우, 플랜지와 케이싱 및 케이싱과 바닥판 2개의 접합부 계면이 형성되는데 각 계면의 수평 전단 저항능력은 구조물의 안전성에 있어 중요한 요소이다. 본 연구는 계면 상세를 달리한 6개의 실험체를 도로교설계기준(한계상태설계법)에 따라 설계 및 제작하여 이중합성 보의 휨 파괴 대비 수평 전단에 대한 구조 성능 실험을 수행하였다. 실험체의 주요변수로 스터드 전단연결재의 저항계수, 바닥판 콘크리트 및 철근의 재료저항계수, 콘크리트 인장강도에 따른 부착계수, 케이싱 콘크리트의 표면 상태 그리고 수평전단철근의 간격을 고려하였다. 실험 결과, 강재 상부 플랜지와 고강도 케이싱의 계면이 고강도 케이싱과 바닥판 계면 보다 결합성이 큰 것으로 나타났다. 그리고 고강도 케이싱과 바닥판 계면에서는 케이싱 표면에 요철 또는 거칠기를 주는 것 보다 보수적으로 수평전단철근을 배근하는 것이 소성영역까지 합성 거동을 유지하는 것으로 나타났다.