• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.79-82
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• 2008

모멘트 하중을 받는 I형 보의 탄성좌굴강도는 하중의 종류, 하중의 단면 내 작용위치, 그리고 구속조건 등과 같은 인자들에 의해 영향을 받는다. 대부분의 시방기준에서는 균일한 모멘트 조건에 대한 좌굴강도를 사용하고 있으며 비균일한 모멘트 효과를 고려하기 위하여 모멘트 구배 수정계수를 적용하고 있다. 본 논문에서는 SSRC 지침서의 방법을 일축대칭 I형 보에 적용할 수 있도록 개선된 모멘트 구배 수정계수를 제안하였다. 단면 내 임의의 높이에 작용하는 연직방향 하중에 대한 일축대칭 I형 보의 유한요소 좌굴해석을 실시하였으며 연직방향 하중은 지간 중앙에 작용하는 집중하중과 등분포 하중을 고려하였다.

• Computers and Concrete
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• 제16권2호
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• pp.191-207
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• 2015

It is generally accepted that, in the interest of safety, it is essential to provide a minimum level of flexural ductility, which will allow energy dissipation and moment redistribution as required. If one wishes to be uniformly conservative across all of the design variables, curvature ductility and moment redistribution factor should be calculated using a probabilistic method, as is the case for other design parameters in reinforced concrete mechanics. In this study, simple expressions are derived for the evaluation of curvature ductility and moment redistribution factor, based on the concept of demand and capacity rotation. Probabilistic models are then derived for both the curvature ductility and the moment redistribution factor, by means of central limit theorem and through taking advantage of the specific behaviour of moment redistribution factor as a function of curvature ductility and plastic hinge length. The Monte Carlo Simulation (MCS) method is used to check and verify the results of the proposed method. Although some minor simplifications are made in the proposed method, there is a very good agreement between the MCS and the proposed method. The proposed method could be used in any future probabilistic evaluation of curvature ductility and moment redistribution factors.

• 대한조선학회 특별논문집
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• 대한조선학회 2015년도 특별논문집
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• pp.74-78
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• 2015

When floating platform or drilling unit is located at operating station during its design life, it has to have the sufficient stability considering external environment. To evaluate whether offshore structure is complied with the required design criteria for intact stability, the factors which decrease the righting moment have to be considered. Wind heeling moment is one of main factors because the direction is opposite to the righting moment. According to 2009 MODU CODE (Code for the construction and equipment of Mobile Offshore Drilling Units, 2009), wind heeling moment derived from wind tunnel test on scale model of offshore structure enables to apply as alternative given formula and method in 2009 MODU CODE. However, there is no the specific method for applying data derived from wind tunnel test. Based on the following reasons, this paper presents that the calculation method of wind heeling moment utilizing non-dimensional coefficient relative to wind loads (wind forces and moments) and the comparison with each method applying an example.

• 대한토목학회논문집
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• 제41권6호
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• pp.617-625
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• 2021

본 연구에서는 국내 개량형 PSC거더(Prestressed Concrete Girder)의 연속화 방식의 문제점과 연속텐던(Continuous Tendon)의 휨모멘트(Bending Moment) 특성을 분석하였다. 이 결과들을 바탕으로 본 연구에서는 거더 연속부의 부모멘트(Negative Moment) 제어에 효과적인 연속텐던 모델을 제안하였다. 이 모델은 연속텐던의 정착단을 거더 하부로 최대한 내리고, 거더 하부로 배치되는 텐던 구간을 늘려, 거더 중앙부의 긴장력 모멘트가 감소하더라도 연속지점부의 긴장력 모멘트를 증가시키는 방법이다. 이러한 연속텐던 모델은 거더 중앙부보다 연속지점부에서 대응해야 할 설계모멘트가 큰 합성 전 연속화 공법에 적합한 성능을 발휘할 수 있다.

• 한국운동역학회지
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• 제15권2호
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• pp.93-102
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• 2005

The purpose of this study was to examine the effect of step length on the joint moment. The subjects were 4 undergraduate and graduate students in their 20s with normal legs. The subjects were individually tested by the running timer at the walking speed of 0.67m/s, 134m/s, and 2.46m/s. The step length was regulated to -10% of normal, normal and +10% of normal step length using foot print. The walking performances of each subjects were filmed using a high speed video camera. The raw data were analyzed by LabVIEW Graphical Program and these data were analyzed by ANOVAs and Scheffe. The results of this study were as follows: The maximum dorsiflexion moment of the ankle joint increased as the step length increased only at the fast walking speed. Although there wasn't significant difference shown in the plantar flexion moment, regular pattern in the plantar flexion moment which increased as the step length increased was found. The first maximum extension moment of the knee joint increased only at the normal walking speed, but there appeared no significant difference in the maximum flexion and second extension moment. The maximum extension moment of the hip joint increased at the normal and fast walking speed. Although there wasn't significant difference, regular pattern in flexion moment which increased as the step length increased was found.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1097-1102
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• 2007

This paper describes the development of 6-axis force/moment sensor for an intelligent robot's foot. In order to walk on uneven terrain safely, the foot should perceive the applied forces Fx, Fy, Fz and moments Mx, My, Mz to itself. The applied forces and moments should be measured from a 6-axis force/moment sensor attached to a humanoid robot's foot(ankle). They in the published paper already have some disadvantage in the size of the sensor, the rated output and so on. The rated output of each component sensor (6-axis force/moment sensor) is very important to design the 6-axis force/moment sensor for precision measurement. Therefore, each sensor should be designed to be gotten similar the rated output under each rated load. So, the sensing elements of the 6-axis force/moment sensor should get lots of design variables. Also, the size of 6- axis force/moment sensor is very important for mounting to robot's foot. In this paper, a 6-axis force/moment sensor for perceiving forces and moments in a humanoid robot's foot was developed using many PPBs (parallel plate-beams). The structure of the sensor was newly modeled, and the sensing elements (plate-beams) of the sensor were designed using FEM (Finite Element Method) analysis. Then, the 6-axis force/moment sensor was fabricated by attaching strain-gages on the sensing elements, and the characteristic test of the developed sensor was carried out. The rated outputs from FEM analysis agree well with that from the characteristic test.

• 한국운동역학회지
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• 제30권1호
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• pp.1-6
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• 2020

Objective: The incidence rate of elbow ulnar collateral ligament injuries is dependent on the throwing speed or pitching type, especially in adolescent baseball players. However, mixed results have been reported due to a lack of controlled biomechanical analysis. Thus, the purpose of this study was to investigate the biomechanical analysis of the elbow in relation to throwing speed and pitching type. Method: Four overhead type high-school baseball players were recruited for this study. The participants were asked to throw balls with different types of pitch and speed. While the throwing speeds were measured, each pitching moment of the elbow was recorded. Descriptive statistics, frequency analysis, mean comparison analysis, and Pearson's correlation analysis were performed in order to examine differences in peak varus and valgus moment during pitching motion in the elbow in all throwing speed and pitching types. Results: There was no significant difference in physical characteristics, throwing speed, and momentum variability among all players. The mean varus moments were 44.38±1.55 Nm, 48.83±1.66 Nm, and 48.94±0.95 Nm, and the moment gaps between varus and valgus were 7.36±3.25 Nm, 7.44±2.02 Nm, and 7.36±2.62 Nm in fastball, curveball, and slider ball, respectively. The varus moment was higher in the curved and slider balls than in the fastballs, and there was no significant differences between the varus moments regarding the pitching type. However, the increase in valgus moment and decrease in moment gap according to throwing speed was significantly increased in the slider ball (r=0.718 and -0.591, respectively). Conclusion: The possibility of elbow injury caused by the valgus moment or moment gapincreases more rapidly in slider balls as the speed increases. Based on our results, appropriate pitching guidelines should be suggested to prevent ulnarligament injuries, especially in adolescent baseball players.

• 한국전문물리치료학회지
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• 제15권2호
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• pp.64-72
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• 2008

The purpose of this study was to determine the differences in joint moment in the intact limb of uni-transfemoral amputees and to identify the implications of knee osteoarthritis. As an experimental method, three-dimensional gait analysis was performed on 10 uni-transfemoral amputees and 10 healthy males. Kinematics and kinetics at the hip, knee, and ankle joint were calculated. As a statistical method, independent t-tests were conducted to perform a comparison between the transfemoral amputee group and the control group. The results showed that the external knee adduction moment increased in the transfemoral amputee group (.22 Nm/kg) compared with that of the control group (.13 Nm/kg) at terminal stance (p=.008). External knee flexion moment also increased in the transfemoral amputee group (.24 Nm/kg) but this difference was not statistically significant. External hip flexion moment increased in the transfemoral amputee group (1.35 Nm/kg) compared with that of the control group (.45 Nm/kg) at initial stance, and external hip extension moment decreased in the transfemoral amputee group (-.26 Nm/kg) compared with that of the control group (-.76 Nm/kg) at terminal stance. Although external ankle plantarflexion moment of the transfemoral amputee group increased, it was not found to be statistically significant. The results suggest that the intact limb joint moment of the uni-transfemoral amputees during walking can be different from that of healthy subjects. In conclusion, it was found that there is a link between the increase of external knee adduction moment and the prevalence of knee osteoarthritis in uni-transfemoral amputees. This result is expected to provide some objective data for rehabilitation programs related to knee osteoarthritis in transfemoral amputees.

• 한국지진공학회논문집
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• 제15권1호
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• pp.11-18
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• 2011

현재 국내 철골 모멘트골조 접합부는 대부분 공장제작으로 품질관리가 잘 이루어져 연성능력이 상당한 수준이다. 문헌에 의하면 국내 접합부는 미국 철강협회에서 철골 중간모멘트골조에 대해 제시한 성능 기준을 충분히 만족하고 있다. 그런데 이전 설계기준인 KBC2005에서는 철골모멘트골조에 연성모멘트골조 하나만을 제공하였으나 현 KBC2009 기준은 보통, 중간, 특수모멘트골조로 다양하게 제공하고 있다. 여기서 국내 접합부 형식을 그대로 사용했을 때 어떤 시스템이 적합한지 조사할 필요성이 있다. 따라서 본 연구에서는 KBC2005의 연성모멘트골조와 KBC2009의 중간모멘트골조의 거동을 비교하여 국내에 적합한 설계 방법을 찾고자 하였다. 연구 결과 기존 연성모멘트골조의 설계 계수를 따르더라도 성능목표를 충분히 만족하는 것으로 나타났다.

• 한국운동역학회지
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• 제26권4호
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• pp.369-375
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• 2016

Objective: The purpose of this study was to investigate the possibility of injuries and the types of movement related to damage by body parts, and to prepare for prevention of injuries and development of a training program. Method: For this study, the experiment was conducted according to levels of 60 percentages (ST) and 85 percentages (MA) and 10 subjects from the Korean elite national weightlifting team were included. Furthermore, we analyzed joint moment and muscle activation pattern with three-dimensional video analysis. Ground reaction force and EMG analyses were performed to measure the factors related to injuries and motion. Results: Knee reinjuries such as anterior cruciate ligament damage caused by deterioration of the control ability for the forward movement function of the tibia based on the movement of the biceps femoris when the rectus femoris is activated with the powerful last-pull movement. In particular, athletes with previous or current injuries should perceive a careful contiguity of the ratio of the biceps femoris to the rectus femoris. This shows that athletes can exert five times greater force than the injury threshold in contrast to the inversion moment of the ankle, which is actively performed for a powerful last pull motion and is positively considered in terms of intentional motion. It is activated by excessive adduction and internal rotation moment to avoid excessive abduction and external rotation of the knee at lockout motion. It is an injury risk to muscles and ligaments, causing large adduction moment and internal rotation moment at the knee. Adduction moment in the elbow joint increased to higher than the injury threshold at ST (60% level) in the lockout phase. Hence, all athletes are indicated to be at a high risk of injury of the elbow adductor muscle. Lockout motion is similar to the "high five" posture, and repetitive training in this motion increases the likelihood of injuries because of occurrence of strong internal rotation and adduction of the shoulder. Training volume of lockout motion has to be considered when developing a training program. Conclusion: The important factors related to injury at snatch include B/R rate, muscles to activate the adduction moment and internal rotation moment at the elbow joint in the lockout phase, and muscles to activate the internal rotation moment at the shoulder joint in the lockout phase.