This study proposes an automated torch angle and position adjustment mechanism for three-dimensional curved-surface welding in shipbuilding. Designed to replace manual operations, the mechanism actively responds to the relative angle between the base plate and stiffener, enabling simultaneous control of torch orientation and positioning using a single power source. The system is integrated into a tracker consisting of a pinion-sector gear assembly for angle adjustment and a cam mechanism for position control. Dynamic simulations confirmed that the torch stably follows the stiffener angle across varying welding speeds, with smooth compensatory motion between the carriage and tracker. Furthermore, a motor-torque-based PID control was implemented, maintaining the torch angle error within 0.23° and the wire tip position error within 0.02 mm. These results verify that the proposed mechanism is highly effective for the automated welding of complex curved structures.

Background: The purpose of this study was to examine whether performing cervical stabilization exercises prior to smartphone use could positively influence postural alignment, pain, and cervical mobility in individuals with forward head posture (FHP). Objectives: To investigate the immediate effects of cervical stabilization exercises performed before smartphone use on craniovertebral angle (CVA), cranial rotation angle (CRA), pain, and cervical range of motion (CROM) in individuals with FHP. Design: A randomized controlled trial. Methods: Participants were randomly assigned into two groups: the control group (Con, n=15), which only vied smartphone videos, and the exercise group (Exp, n=15), which performed cervical stabilization exercises before smartphone viewing. All participants used a smartphone for 20 minutes and pre- and post-measurements included CVA, and CRA, CROM, and VAS for pain. Results: The results demonstrated that participants who performed cervical stabilization exercises showed increased CVA and decreased CRA, suggesting an improvement in forward head alignment following smartphone use. In contrast, the control group exhibited decreased CVA, increased CRA, and elevated neck pain scores after smartphone viewing. Additionally, the control group showed a reduction in right lateral flexion range of motion, whereas no significant CROM changes were observed in the Exp group. Between-group comparisons revealed significant differences in CVA, CRA, and VAS, supporting the immediate protective effects of exercise. Conclusion: These findings suggest that performing cervical stabilization exercises before smartphone use may help mitigate posture deterioration and pain induced by smartphone viewing. This indicates that pre-emptive cervical stabilization exercise could serve as an effective preventive strategy for individuals with FHP.

Background: Tensor fasciae latae (TFL) and iliotibial tract (ITB) tightness can pull the pelvis during hip lateral rotation (HLR), increasing pelvic rotation due to muscle tension. Among various tests, the HLR test in the prone position (HLRP) is a clinical evaluation tool for assessing lumbopelvic motion with lower-extremity movement. However, performing the HLRP may result in less compensatory motion and a relatively decreased pelvic rotation angle (PRA) because of a wide base of support. Moreover, there were no studies investigating PRA during an HLR test in the standing position (HLRS). Objects: This study aimed to compare the PRA in the horizontal plane during HLRS and the HLRP between individuals with and without TFL/ITB tightness. Methods: Thirty participants with (n = 15) and without (n = 15) TFL/ITB tightness as assessed by Ober’s test, were recruited. The PRA was measured during active HLRS and HLRP. Two-way mixed analysis of variance was used to identify significant differences in the PRA between groups and within positions. Results: When HLRP and HLRS were performed, the PRA in the horizontal plane occurred at 1.65° ± 0.98° and 7.68° ± 4.69°, respectively, in the TFL/ITB tightness group, and at 1.27° ± 1.07° and 2.37° ± 1.96°, respectively, in the control group. A significant interaction effect was identified between groups and positions on the PRA (p < 0.05). Individuals with TFL/ITB tightness had a significantly greater PRA during HLRS than those in the control group. The PRA during HLRS was significantly greater than that during HLRP in individuals with TFL/ITB tightness. Conclusion: These results suggest that TFL/ITB tightness contributes to increased PRA during HLRS compared with HLRP. Clinically, assessment of the PRA in the standing may provide a functional indicator of compensatory pelvic motion during hip rotation of 45°.

본 연구의 목적은 12주간의 리포머 필라테스가 50대 여성의 Q각과 등속성 근기능에 미치는 영 향을 규명하는 것이다. 필라테스 운동 경험이 없는 28명을 모집하여 운동집단 14명과 통제집단 14명으로 무작위 배정하였으나, 집단별로 1명의 탈락자가 발생하여 총 26명의 데이터를 최종분석하였다. 운동집단의 대상자는 1회당 45~55분의 리포머 필라테스를 주2회 빈도로 실시하였으며, 통제집단은 특별한 처치 없이 평소 생활습관을 유지하도록 하였다. Q각과 요부, 슬관절, 그리고 족관절의 등속성 근기능을 측정한 뒤, 반 복이원변량분석을 실시하여 두 집단 간, 두 시기간에 비교하였다. 본 연구에서 얻은 결과는 다음과 같다. 1) Q각과 관련하여, 모든 변인에서 통계적으로 유의한 변화가 나타나지 않았다. 2) 요부 등속성 근기능과 관련하여, 운동집단의 굴근지구력이 유의하게 증가되었다. 3) 슬관절 등속성 근기능과 관련하여, 모든 변인 에서 통계적으로 유의한 변화가 나타나지 않았다. 4) 족관절 등속성 근기능과 관련하여, 모든 변인에서 통 계적으로 유의한 변화가 나타나지 않았다. 위와 같은 결과를 정리하면, 12주간의 리포머 필라테스가 50대 여성의 Q각과 대부분의 등속성 근기능을 개선시킬 수 없었다고 결론지을 수도 있지만, 많은 변인에서 통 제집단에 비하여 운동집단의 큰 사전-사후 변화량이 보고되었고, 본 연구에서 사용한 통계기법의 특성상 현장적인 의미에서 긍정적인 변화가 나타났어도 통계적으로는 유의한 변화가 나타나지 않는 경우가 있기 때문에 이와 같은 결과를 부정적으로만 평가하기는 어려울 것으로 사료된다. 따라서 후속 연구에서는 더 많은 표본수와 세분화된 근기능 검사를 통하여 본 연구의 결과를 추가 분석할 필요가 있다.

To reduce the transient pressure oscillations (hunting) in pilot valves used in control systems of nuclear power plants, this study investigates the effect of orifice angle design using computational fluid dynamics (CFD). A conical orifice geometry with a base radius of 1.25 mm and a length of 1 mm was modeled with varying angles (10°, 20°, and 30°). The models were analyzed using transient flow simulation in ANSYS CFX, applying a k-ω turbulence model to accurately capture near-wall flow characteristics. The results showed that larger orifice angles led to reduced pressure hunting, improving system stability. Additionally, velocity and pressure distributions demonstrated smoother flow and smaller fluctuations at higher orifice angles. The findings indicate that optimizing orifice angle is an effective strategy to suppress pressure hunting in pilot valve systems.

소프트 로보틱스는 기존의 강체 시스템에 비해 향상된 유연성, 적응성, 그리고 안전성을 제공하며, 이는 특히 인간과의 상호작용이 나 비정형 환경에서의 응용에 적합하다. 소프트 로봇을 위한 다양한 구동 메커니즘 중 형상기억합금(SMA)-섬유 액추에이터는 경량 성, 저소음 작동, 높은 에너지 밀도 등의 장점으로 유망한 솔루션으로 부상하고 있다. 본 연구에서는 P-루프 형태로 구성된 SMA 기반 섬유 액추에이터를 사용하여 제작된 소프트 니트 그리퍼의 구동 성능 및 굽힘 거동을 해석하였다. 그리퍼의 변형 거동을 모델링하고 예측하기 위해 ABAQUS 환경에서 등가 유닛 셀(EUC) 모델을 활용하여 소프트 니트 그리퍼와 EUC 모델 간의 굽힘 성능을 분석 및 비 교하였다. 해당 모델은 전기 자극에 따른 형상기억 효과로 인한 대변형을 시뮬레이션하기 위해 기하학적 비선형성을 포함하였다. 분 석에는 P-루프 구조에서 나타나는 굽힘 거동이 포함하였으며, 이는 효과적인 파지 및 조작을 위해 중요한 요소이다. 실험적 검증은 다 양한 전압을 그리퍼에 인가하고, 그에 따른 굽힘 각도를 측정함으로써 수행하였다. 실험 결과, 인가 전압이 증가함에 따라 굽힘 각도 도 유의미하게 증가하였으며, 최대 180°까지의 변형이 관찰되어 액추에이터의 우수한 성능을 입증하였다. EUC 모델을 기반으로 한 수치 해석 결과는 최대 굽힘 각도에서 단 5%의 오차 범위를 보이며 실험 결과와 매우 근접한 양상을 나타내어, 제안된 모델링 접근법 의 정확성과 신뢰성을 확인하였다. 본 연구는 EUC 모델이 SMA-섬유 기반 소프트 그리퍼의 구동 거동을 효과적으로 예측할 수 있음 을 보여주었으며, 차세대 소프트 액추에이터의 설계 및 성능 향상을 위한 중요한 통찰을 제공하였다. 또한, 형상에 밀착되며 유연한 작동이 요구되는 현대 소프트 로보틱스 및 생체의료 응용 분야에서 SMA-섬유 복합재의 활용 가능성을 확인하였다.

This study aims to validate the feasibility of using LiDAR reflectivity data to quantitatively estimate the retroreflectivity of road lane markings. The goal is to establish the optimal scanning conditions considering the channel position, angle of incidence, and vehicle speed for an accurate and consistent retroreflectivity assessment in mobile environments. Fifteen standard lane marking samples with known retroreflectivity values were scanned using an OS1-128 LiDAR sensor under controlled field conditions. A two-phase experiment was conducted: (1) a speed-based test to assess the influence of vehicle velocity (20-80 km/h) on LiDAR reflectivity measurements, and (2) a channel–angle–distance test using a static testbed to analyze the relationship between retroreflectivity, LiDAR channel position (that is, the angle of incidence), and measurement distance. Ground truth retroreflectivity values were obtained using a high-precision handheld retroreflectometer. Reflectivity measurements showed a strong correlation with standard retroreflectivity values, particularly at scanning angle between 100-115° and distances of 4.9-5.6 m. The coefficient of determination (R2) exceeded 0.97 across optimal conditions. Speedrelated tests confirmed that the LiDAR-based reflectivity remained stable with a minimal RMSE (< 5), even under high-speed driving scenarios. LiDAR sensors provided reliable and contactless estimates of pavement marking retroreflectivity when the channel angle and scanning distance were appropriately selected. The findings demonstrated that channel-specific calibration and incidence angle correction significantly improved the measurement accuracy. This suggests a practical path forward for automated large-scale retroreflectivity monitoring in road asset management systems.

Background: Previous systematic reviews and meta-analyses have suggested core stabilization exercise as a conservative treatment approach for scoliosis. Objectives: To investigate the effects of sling exercise and unilateral core exercise on the angle, balance ability, and muscle tone in individuals with scoliosis. Design: Randomized controlled trial. Methods: Twenty-one students in their twenties with mild scoliosis were recruited as participants and randomly assigned to one of three groups: a sling exercise group (n=7), a unilateral core exercise group (n=6), and a combined sling and unilateral core exercise group (n=6). Two participants dropped out during the study. Each group performed its designated exercise program individually, three times per week for five weeks. Measurements of scoliosis angle, balance, and muscle tone were taken before and after the intervention. Results: The sling exercise intervention significantly reduced the scoliosis angle (P<.05) and significantly increased muscle tone on the convex side (P<.05). In the combined sling and unilateral core exercise group, a significant improvement in static balance ability was observed (P<.05). Conclusion: Among the core stabilization exercises applied to scoliosis, sling exercise may be considered a potential intervention for mild scoliosis.

Background: Rounded Shoulder Posture (RSP) and Forward Head Posture (FHP) often result from prolonged digital device use, leading to muscle imbalance, pain, and functional limits. Growing demand for postural correction highlights the need for effective exercise approaches. Objectives: This study compared strengthening, self-stretching, and mixed exercises on acromion height, craniovertebral angle, and muscle tone in adults with FHP and RSP. Design: Randomized controlled pretest-post test trial over four weeks. Methods: Thirty university students (acromion height ≥2.5 cm, craniovertebral angle ≤53°) were randomly assigned to strengthening (n=6), self-stretching (n=9), or mixed exercise (n=9) groups. Participants exercised three times weekly for four weeks. Pre- and post-tests measured acromion height, craniovertebral angle, and muscle tone of the pectoralis major, upper trapezius, and sternocleidomastoid using MyotonPro®. Data were analyzed with Wilcoxon signed ranks, Kruskal-Wallis, and repeated measures ANOVA (P<.05). Results: All groups significantly improved acromion height and craniovertebral angle (P<.05) without intergroup differences. Significant tone change appeared only in the upper trapezius (P<.05), with the mixed group showing the largest improvement. Conclusion: All exercises improved posture in adults with FHP and RSP. Mixed exercise yielded the greatest reduction in upper trapezius tone, suggesting a multimodal approach may be most effective.

This study examines the impact of Propeller blade pitch angle mismatch on Noise, thrust, and vibration in light aircraft. Tests were conducted using a simulator with one blade set at increased pitch angles (10°, 12°, 14°) compared to the standard 8°. Results showed that mismatches increased vibration (above 0.26 IPS), Noise levels, and caused operational issues such as fuel leakage and backfire. While thrust initially increased with pitch, it dropped at 14° due to fuel flow instability. These results highlight the need for strict pitch alignment tolerances to ensure optimal performance and safety in aircraft maintenance and operation.

Aircraft Noise is a sound that humans do not want. In this study, based on the Rotax 914 engine used in Korea, the Propeller blade angle was changed by 1 degree for the 3-leaf “K company” Propeller and the 3-leaf “G” wooden Propeller, and the engine RPM was changed to examine the Noise and thrust changes. The purpose of this study is to check whether Noise and thrust loss are the least at the engine's maximum RPM, and to propose an aircraft operation plan in the noisy aerodrome area based on the values. This research further seeks to identify optimal propeller configurations that balance acoustic performance and thrust efficiency. The results are expected to aid in formulating guidelines for quieter flight operations near populated areas.

최근 쌍추진기를 장착한 여객선의 도입이 증가하고 있다. 쌍추진 여객선은 독립적인 추진기와 방향타 조작을 통해 뛰어난 조 종 성능을 발휘하나, 일반적인 단축선에 비해 과도한 횡경사(heel angle)를 유발할 수 있으며, 이는 여객의 보행 안전에 직접적인 영향을 미 친다. 본 연구는 쌍추진 여객선의 횡경사각이 여객의 보행 안전에 미치는 영향을 분석하는 것을 목적으로 한다. 모형선 실험과 실선 시운 전 자료를 바탕으로 GM별, 선속별 횡경사각을 계산하였으며, 한국인 성인 남녀의 신체 계측 자료와 Motion-Induced Interruptions(MII) 이론 을 적용하여 보행 중 전도 임계각(tipping angle)을 산정하였다. 연구 결과, GM이 작고 고속으로 큰 타각을 사용해 회두할 경우, 사람의 전 도 임계각을 초과하는 횡경사가 발생할 수 있음을 확인하였다. 또한 실증 보행 실험을 통해, 선체 기울기가 20° 이상일 때 보행 곤란, 30° 이상일 때 보행 불가를 확인하였다. 이 결과를 바탕으로, 고속 기동 중 타각 제한, 최소 GM 기준, 횡경사 발생 시 여객 이동 제한에 대한 안전 기준 마련의 필요성을 제안하였다.

Background: The progressive digitalization of contemporary life, coupled with prolonged sedentary behavior, has contributed to the widespread occurrence of forward head posture (FHP) in the general population. Among the various exercise interventions aimed at correcting FHP, stretching exercises and proprioceptive training have garnered significant attention. Objectives: To investigate the effects of stretching exercises and proprioceptive training on craniovertebral angle (CVA), an indicator of forward head posture (FHP), and on the muscle tone of the suboccipital muscles. Design: Randomized controlled trial. Methods: Thirty participants were randomly assigned to either the stretching exercise group (n=15) or the proprioceptive training group (n=15), and each group underwent intervention three times per week for six weeks. CVA and muscle tone of the suboccipital muscles were measured before and after the six-week intervention, and the results were statistically analyzed for comparison. Results: Both groups showed a significant increase in CVA after the intervention (P<.05), with no significant difference between the groups. The muscle tone of the suboccipital muscles did not show statistically significant changes either within or between the groups. Conclusion: Six weeks of stretching exercise and proprioceptive training both resulted in a significant increase in CVA, demonstrating that both interventions are effective in improving FHP. However, neither intervention produced significant changes in the muscle tone of the suboccipital muscles.

Background: Foam roller exercise is widely used for myofascial release and improving joint range of motion. Objectives: This study aimed to identify the most effective session of thoracic foam roller exercise by examining changes in thoracic kyphosis angle (TKA) and trunk active range of motion (AROM) in healthy males in their 20s. Design: Single-group design. Methods: The study analyzed changes in TKA and trunk AROM across sessions following the application of a thoracic foam roller exercise for 45 seconds per session over three sessions in 16 healthy males in their 20s. Results: Compared to pre-test values, TKA significantly decreased and trunk AROM significantly increased after thoracic foam roller exercise (P<0.01). Post hoc analysis showed a significant decrease in TKA in session 3 compared to session 1 (P<0.01). Trunk AROM (flexion, left lateral flexion, right lateral flexion) showed significant changes in sessions 2 and 3 compared to session 1 (P<0.01). Right rotation significantly improved in session 3 compared to session 1 (P<0.01). Conclusions: For managing thoracic vertebral alignment in healthy males in their 20s, three sessions of thoracic foam roller exercise per day are recommended. For improving trunk AROM management, two sessions per day be sufficient.

Aerial work platforms (AWPs) are specialized vehicles designed for tasks at elevated heights, and are widely used in various environments such as construction sites, road maintenance, and high-altitude operations. In this study, computational fluid dynamics (CFD) analysis was conducted to investigate the airflow field, drag force, and torque characteristics around an AWP. The simulation results showed that the overall airflow velocity decreased as it passed over the vehicle and boom, while it increased locally between the vehicle and the boom, and beneath the work platform. The drag force and torque acting on each component were highly sensitive to changes in boom angle due to variations in airflow. As the boom angle increased, the drag force increased by approximately 20 times, and the torque by up to 108 times. These findings provide fundamental data for establishing design criteria to enhance the structural stability and aerodynamic performance of aerial work platforms.

Background: With the increase of seated work, interest in forward head posture (FHP) has grown. Prolonged computer tasks with FHP have been considered a factor that increases the stiffness and tone of the upper trapezius (UT) muscle. Traditionally, many studies have measured the craniovertebral angle (CVA) in standing positions to assess FHP, making it difficult to determine whether the CVA measured in a habitual working posture correlates with the stiffness and tone of the UT muscle in office workers. Objects: This study aimed to investigate the relationship among CVA, UT muscle stiffness, and tone in both habitual working and standing postures among asymptomatic office workers. Methods: Forty asymptomatic office workers participated in the study. CVA was measured in both habitual working and standing postures. Stiffness and tone of the UT muscle were assessed after a 10-minute computer task. Pearson’s correlation coefficient was used to investigate the relationship between CVA and stiffness and tone of the UT muscle. Results: No significant correlations were found between CVA in standing posture and the stiffness and tone of the UT muscle. However, moderate negative correlations were observed between CVA measured in the habitual working posture and both the stiffness (dominant: r = –0.490, non-dominant r = –0.465) and tone (dominant: r = –0.501, non-dominant r = –0.446) of the UT muscle. Conclusion: This study highlights that decreased CVA in habitual working posture is associated with increased stiffness and tone of the UT muscle in asymptomatic office workers. Therefore, measuring CVA in the habitual working posture should be considered when evaluating stiffness and tone of the UT muscle.

In this study, the effect of underwater hydrofoils was analyzed through model tests on a motor boat with a total length of approximately 8.5 m and a maximum speed of 25 knots(approximately 12.9 m/s). The degree of hull sinkage and resistance performance according to the size and angle of attack of the foils with the same cross sectional shape were analyzed and the required horsepower was estimated. Through this study, it was confirmed that the area and angle of attack of the foils had a great effect on hull sinkage and that a rapid decrease in resistance and change in required horsepower occurred depending on the degree of hull sinkage.

Background: Stroke patients often exhibit excessive kyphosis of the spine and a forward head posture (FHP), which negatively impacts their daily activities. These postural abnormalities not only negatively affect functional movement but also exacerbate musculoskeletal problems. Objectives: This study was conducted to determine the effect of backward walking on FHP in stroke patients. Design: Single-case experimental design (A-B-A’ design). Methods: The study was conducted over a total of 8 weeks, comprising 24 sessions: 3 baseline sessions (A), 18 intervention sessions (B), and 3 regression baseline sessions (A'). No backward walking intervention was performed during baseline (A) and regression baseline (A’). To determine changes in FHP, the craniovertebral angle (CVA) was measured at all sessions. Results: The CVA increased in the intervention (B) and regression baseline (A’) compared to the baseline (A). Conclusion: Backward walking was effective in improving FHP, and the effect was maintained after intervention (B) in patients with stroke. Therefore, backward walking was effective in improving the postural alignment of stroke patients.