Background: Many trials have been conducted the methods and types of intervention of form rollers, but no research has been done yet that mixes the methods and types of intervention. Objectives: To analyze the effects of myofascial release on the improvement of range of motion (ROM), flexibility, pain pressure threshold, and balance. Design: Randomized controlled trial. Methods: All subjects measured ROM, flexibility, pressure pain threshold, and dynamic balance by pre-test. After pre-test, subjects were randomized that static-vibration foam rolling group (n=12), dynamic-vibration foam rolling group (n=12), general foam rolling group (n=12). For the intervention, 3 sets of 90 seconds were applied to each group, and rest time was set to 60 seconds between sets. In the post-test and follow-up test after 10 minutes, all three groups were measured the ROM, flexibility, pressure pain threshold, and dynamic balance. Results: The results of comparing ROM, flexibility, pressure pain thresholds, dynamic balance ability appeared higher significant difference in the prepost- 10 minutes follow up test in comparison between time in the intragroup (P<.001). As a result of comparing the change of pre-post-10 minutes follow up, static vibration foam rolling showed higher significant difference compared to control groups (P<.001). Conclusion: Through this study, when foam rolling is applied within the same intervention time, static foam rolling can be expected to have a better effect than the existing dynamic foam rolling as well as vibration foam roller can expect better effect than general foam rolling.

목적 : 본 연구에서는 조절자극량을 달리하여 주시방향과 주시각도변화에 따른 조절반응량을 측정하고자 한다. 방법 : 안과적 수술이나 질환이 없고 양안의 시력이 정시이며, 시기능의 차이가 나지 않는 성인 남녀 13명(22.40± 0.41세)을 대상으로 정면, 측방 10°, 측방 20°, 하방 10°, 하방 20°에 시표를 위치시켜 3 m, 1 m, 40 cm의 거리별로 개방형 자동안굴절검사기를 이용해 조절반응량을 연속적으로 측정하였다. 결과 : 모든 주시방향에서 주시거리가 짧아질수록 조절반응량은 증가하였다. 3 m를 제외한 1 m, 40 cm 에서 는 하방 20° 주시 시 각각 1.09±0.10, 2.04±0.11 D로 조절반응량이 가장 높게 나왔으며, 1 m 거리에서는 측면 20° 주시 시 0.44±0.05 D, 40 cm 거리에서는 측면 10° 주시 시 1.54±0.06 D로 가장 낮은 조절반응량을 나타내 어 통계적으로도 유의한 차이를 보였다(p＜0.050). 또한, 측방 시 10°, 20°를 제외한 모든 주시방향에서는 서로 유 의한 차이가 나타났으며(p＜0.050), 주시방향과 조절반응량은 서로 유의한 차이가 있었다(p＜0.050). 결론 : 본 연구의 결과로 동일한 조절자극량에 대해서도 주시방향과 주시각도에 따라 조절반응량 이 달라지는 것 을 알 수 있었다. 따라서 근거리 업무 시 주시물체의 위치를 눈높이 정면보다 하방으로 두면 더 선명 상을 얻을 수 있으므로 지속적인 근거리 업무에 따른 안정피로를 최소화 할 수 있을 것으로 사료된다.

PURPOSES : This study evaluated the effects of dynamic road marking (DRM) on the reduction in drivers’ workload under rainy conditions. Changes in workload in two cases were evaluated: only-lane marking and a combination of lane marking and DRM. METHODS : Rainy conditions were simulated by utilizing the full-scale road weather proving ground. Moreover, participants’ eye movements were used as the indicators for workload. RESULTS : Workload in case of the combination of lane marking and DRM was found to decrease by 44.6% compared to the case of onlylane marking, under the rain intensity of 15 mm/h. Moreover, workload decreased by 50.7% in case of the combination of lane marking and DRM compared to the only-lane marking case, under 30 mm/h rain intensity. CONCLUSIONS : This study validated the positive effects of the DRM in workload reduction under rainy conditions.

Recently, at-home workouts, which allows people to exercise easily and comfortably at home without going to the gym, has been in the spotlight. Accordingly, a lot of household equipment is produced, but weight exercise equipment is limited in use at home because of its heavy weight or volume. Therefore, this paper proposes a new form of exercise equipment that can be used at home by transforming the exercise equipment used in the fitness center. The proposed mechanism replaces the weight part of the strength exercise device, which is the key to weight control, with an electric motor. Three major muscle exercise instruments (long pull machine, curl cable machine, and let down machine) were analyzed by dynamic analysis using a multipurpose dynamic program (DAFUL). This shows that the proposed equipment can perform various sports. Therefore, the proposed mechanism is expected to be applicable at home, and this study is expected to be rapidly mass-produced by emphasizing practicality.

The cast iron pipe protection of submarine cables has a bump in the connection, so the guide device for checking the position and location of the submarine cable must pass through the curved surface. Since the connection is present at a regular intervals, impact loads are periodically applied, affecting the durability of the guide device. In this study, the design was changed to improve the durability of guide device links. And for the analysis of the durability for link of guide device, the flexible dynamic analysis of the guide device was performed using MSC.Adams, and the dynamic stress acting on the link was calculated using MSR(Modal Stress Recovery) method. As a result, the dynamic stress is reduced by 17.9%~31.1%. In addition, durability was calculated for the initial model and the improved model. As a result, the durability of the new model was improved more than 200 % better than to the initial model.

본 연구는 저출산·고령사회기본계획의 개요와 자체평가에 대한 문제점을 지적하고, 그 해답을 찾기 위한 기초자료로써 낮은 출산율과 높은 고 령화율 등 우리나라와 유사한 경험을 이미 겪고 있는 일본의 저출산고령 사회에 대응 방책, 특히 아베(安倍)정권 이후의 저출산·고령사회정책(일명, 일본 1억총활약 플랜)에 초점을 맞추어 고찰한 후, 그 시사점을 제시 하고자 하였다. 그 연구결과는 다음 세 가지로 요약할 수 있겠으며, 이를 차기(次期)(제4차) 또는 차차기(次次期)(제5차) 계획수립시의 개선방안으 로 제언한다. 첫째, 국가적 차원의 미래청사진(국가비전)의 제시가 필요 하다. 둘째, 명확하고 냉정한 실태파악이 필요하다. 셋째, 단순하고 단기적인 대응책이 아닌 다차원적이고 실현가능한 수치를 제시할 필요가 있 다.

This paper examined the dynamic instability of a shallow arch according to the response characteristics when nearing critical loads. The frequency changing feathers of the time-domain increasing the loads are analyzed using Fast Fourier Transformation (FFT), while the response signal around the critical loads are analyzed using Hilbert-Huang Transformation (HHT). This study reveals that the models with an arch shape of h = 3 or higher exhibit buckling, which is very sensitive to the asymmetric initial conditions. Also, the critical buckling load increases as the shape increases, with its feather varying depending on the asymmetric initial conditions. Decomposition results show the decrease in predominant frequency before the threshold as the load increases, and the predominant period doubles at the critical level. In the vicinity of the critical level, sections rapidly manifest the displacement increase, with the changes in Instantaneous Frequency (IF) and Instant Energy (IE) becoming apparent.

In this paper, the dynamic snapping of the 3-free-nodes spatial truss model was studied. A governing equation was derived considering geometric nonlinearity, and a model with various conditions was analyzed using the fourth order Runge-Kutta method. The dynamic buckling phenomenon was observed in consideration of sensitive changes to the force mode and the initial condition. In addition, the critical load level was analyzed. According to the results of the study, the level of critical buckling load elevated when the shape parameter was high. Parallelly, the same result was caused by the damping term. The sensitive asymmetrical changes showed complex orbits in the phase space, and the critical load level was also becoming lowly. In addition, as the value of damping constant was high, the level of critical load also increases. In particular, the larger the damping constant, the faster it converges to the equilibrium point, and the occurrence of snapping was suppressed.

Background: For performing various movements well, cooperation between the muscles around the scapula and shoulder has been emphasized. Taping has been widely used clinically as a helpful adjunct to other physiotherapy methods for shoulder pathology and dysfunction treatment. Previous studies have evaluated the effect of taping techniques using dynamic tapes on shoulder function and pain. However, no study investigated the electromyographic (EMG) changes in the shoulder muscles. Objects: This study aimed to investigate the effect of the upper limb offload taping technique using a dynamic tape on EMG activities of the upper trapezius (UT), lower trapezius, serratus anterior (SA), and middle deltoid (MD) muscles during scaption plane elevation. Methods: A total of 26 healthy subjects (19.85 ± 6.40 years, male = 20) volunteered to participate in this study. The subjects were instructed to perform scaption elevation with and without dynamic taping on the shoulder. Shoulder elevation strength tests were performed at 100%, 75%, 50%, and 25%, for the maximal isometric contraction force. Results: There were statistically significant interaction effects between the taping application and shoulder scaption elevation force in EMG activities in the UT (p < 0.05) and MD (p < 0.05). EMG activities in the UT showed significant increases in 50%RVC (reference voluntary contraction, p < 0.05) and 25%RVC (p < 0.01). Furthermore, the EMG activity of the SA significantly increased in 50%RVC (p < 0.01) and 25%RVC (p < 0.01) after dynamic taping. For the MD, the EMG activity level significantly decreased in 100%RVC (p < 0.05). Conclusion: These results indicated that upper limb offload dynamic taping application affects the muscle activities of some shoulder muscles depending on different scaption elevation strength levels. Therefore, we suggest that the upper limb offload dynamic taping can be applied to the shoulders when patients need middle deltoid inhibition or upper trapezius facilitation, such as patients with shoulder impingement syndrome.

In fisheries, the importance of designing efficient fish cages is being emphasized as aquaculture has become more production than capture fishing. Particularly, the gravity cage system is one of the popular fish cage system in Korea. Currently, gravity cages of various shapes and sizes are being widely designed and installed in offshore and inland seas. The cage is subject to external forces, such as currents and waves, and the shape of the structure and tension on the ropes changes according to these external forces. Thus, it is important to accurately calculate these dynamic behavior, including the external forces and tension on the structure during the design stage. In this study, three types of cage systems with an equal internal volume of 8000 m3 were analyzed using mass-spring models and their behavior was interpreted through simulations. These simulations were used to analyze the behavior and tension of the ropes in response to currents and waves to aid in the selection of individual cage sizes for a given total volume. The numerical calculation results indicate that depending on the flow rate, the most resistant system is System 1, which has eight strays, and System 2 and System 3 have 69.4% and 54.8% of the resistance of System 1. Further, total resistance increased as the number of cages increased for all flow rates.

The purpose of this study is to investigate the distribution patterns of displacement and acceleration fields in a nonlinear soil ground based on the interaction of high-speed train, wheel, rail, and ground. For this purpose, a high-speed train in motion was modeled as the actual wheel, and the vertical contact of wheel and rail and the lateral contact, caused by meandering motion, were simulated; this simulation was based on the moving mass analysis. The soil ground part was given the nonlinear behavior of the upper ground part by using the modified the Drucker– Prager model, and the changes in displacement and acceleration were compared with the behavior of the elastic and inelastic grounds. Using this analysis, the displacement and acceleration ranges close to the actual ground behavior were addressed. Additionally, the von-Mises stress and equivalent plastic strain at the ground were examined. Further, the equivalent plastic and total volumetric strains at each failure surface were examined. The variation in stresses, such as vertical stress, transverse pressure, and longitudinal restraint pressure of wheel-rail contact, with the time history was investigated using moving mass. In the case of nonlinear ground model, the displacement difference obtained based on the train travel is not large when compared to that of the elastic ground model, while the acceleration is caused to generate a large decrease.

Background: The alignment of the neck and shoulder is important in people with forward head posture. However, previous studies have mainly conducted fragmentary studies on the neck and shoulders, and studies on the combined movement of the neck and shoulders are incomplete. Objective: To investigate the effects of 6 week dynamic exercise program using Thera-band on craniovertebral angle (CVA) in adults with forward head posture. Design: Quasi-experimental study. Methods: The study was conducted on 24 adults with forward head posture and experimented with neck and shoulder exercises and divided them into groups of neck exercises, shoulder exercises, and neck and shoulder exercises to measure CVA values before and after the experiment. The neck exercise program included flexion and extension muscles of the neck and shoulder exercises included dynamic exercise of the upper extremities such as the trapezius muscles and serratus anterior muscle. The CVA results were measured using PA200. Results: Following the interventions, neck exercise group showed significant improvement in CVA (P<.05), but shoulder exercise group and combined exercise group did not show any significant results (P>.05). However, both groups showed some positive results. Significant differences were seen in the comparisons between the three groups (P<.05), and the results of the posthoc test showed significant differences in neck exercise group and shoulder exercise, neck exercise and combine exercise group. Conclusion: This study suggested that the Thera-band neck exercise is beneficial for foward head posture patients and is expected to be used in clinical trials.

Seismic responses due to the dynamic coupling between a primary structure and secondary system connected to a structure are analyzed in this study. The seismic responses are compared based on dynamic coupling criteria and according to the error level in the natural frequency, with the recent criteria being reliant on the error level in the spectral displacement response. The acceleration responses and relative displacement responses of a primary structure and a secondary system for a coupled model and two different decoupled models of two degrees-of-freedom system are calculated by means of the time integration method. Errors in seismic responses of the uncoupled models are reduced with the recent criteria. As the natural frequency of the secondary system increases, error in the natural frequency decreases, but seismic responses of uncoupled models can be underestimated compared to that of coupled model. Results in this paper can help determine dynamic coupling and predict uncoupled models’ response conservatism.

This paper deals with the dynamic control of redundant robot manipulator. Traditionally, the kinematic control schemes for redundant robot manipulator were developed from the point of speed and used under the assumption that the dynamic control of manipulator is perfect. However, in reality, the precise control of redundant robot manipulator is very difficult due to their dynamics. Therefore, the kinematic controllers for redundant robot manipulator were employed in the acceleration dimension and may be combined with the computed torque method to achieve the accurate control performance. But their control performance is limited by the accuracy of the manipulator parameters such as the link mass, length, moment of inertia and varying payload. Hence in this paper, the proportional and derivative control gains of the computed torque controller are optimized by the genetic algorithm on the typical payloads, and the neural network is applied to obtain the proper control gains for arbitrary loads. The simulation results show that the proposed control method has better performance than the conventional control method for redundant robot manipulator.

In this study, system modeling and dynamic analysis of crane are conducted. Especially, among many different kinds of a crane system, the issues on crane operating problems installed on the vessel are considered. As well known, marine systems including cranes are exposed to various disturbances such as vessel motions, hydrodynamic forces, wave and wind attack, etc. In order to analysis the system dynamic with environmental conditions, the authors derived the nonlinear dynamic model of offshore crane and derived a linear model which is used for designing the control system. Using the obtained nonlinear and linear models, simulations were conducted to evaluate the usefulness of the obtained models. By simulation and result evaluation, the usefulness of the linear model, which presents the dynamics, is effectively verified.

Background: Flat-footed persons with collapsed medial longitudinal arch lose flexibility after skeletal maturity, resulting in several deformities and soft tissue injuries. Although arch support taping is usually applied in the clinic to support the collapsed arch, research on the use of different types of tape for more efficient arch support in flat-footed persons is lacking. Objects: The purpose of this study was to examine three conditions (barefoot, kinesio tape, and dynamic tape) and compare their effects on static and dynamic balance in persons with asymptomatic flexible flatfoot. Methods: Twenty-two subjects (9 females and 13 males) with asymptomatic flexible flatfoot participated in this study. The subjects performed the Y-balance test to measure the composite reach score. The subjects also performed a 30-second standing test to measure the center of pressure (COP) path length and a walking test to measure anteroposterior and lateral variability using the Zebris FDM system. One-way repeated-measures analysis of variance compared the three conditions applied to the subjects’ feet for each balance variable. Results: The composite reach score significantly increased following the application of dynamic tape compared with barefoot and that of kinesio tape compared with barefoot. There was no significant difference in the COP path length during standing among the three conditions. Anteroposterior and lateral variability during walking significantly with dynamic tape application compared with barefoot. Conclusion: The results of this study suggest that, in persons with asymptomatic flexible flatfoot, application of kinesio tape and dynamic tape may be effective in increasing the composite reach score in Y-balance test, whereas application of dynamic tape may be effective in reducing anteroposterior and lateral variability during walking.