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.

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.

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.

Background: With the growing interest in the health of companion dogs, their average lifespan has increased, leading to an increase in the proportion of elderly dogs. As elderly dogs are vulnerable to various diseases, there is a need for alternatives to predict the risk of major diseases in senior dogs, prevent them in advance, and manage their health effectively. Therefore, this study was conducted to identify candidate genes and single nucleotide polymorphisms (SNPs) influencing primary angle-closure glaucoma, a major disease in elderly dogs, using the Axiom Canine HD Array and establishing foundational data. Methods: Samples from 95 dogs of 26 breeds from South Korea were analyzed using an SNP chip. Ultimately, two SNPs were selected. To assess the impact of non-synonymous SNP (nsSNPs), functional analysis of candidate genes, Hazard Assessment, and protein structure prediction were conducted. Sequencing for SNP validation involved samples from 95 dogs of ten breeds with reported domestic and international glaucoma cases. Results: The candidate gene TNS1 was associated with the integrin signaling pathway. The selected nsSNP was found to cause a mutation at the ninth position of the amino acid sequence, changing serine to leucine and resulting in alterations to the overall protein structure. Sequencing analysis results for SNP validation revealed differences in frequency among breeds. Conclusions: The identified SNP markers are potential risk prediction tools. Utilizing genotype frequency data by breed and individual could aid in disease management and contribute to advancements in the medical industry.

The results of the measurements using an optical surface roughness meter are shown according to the angle changes of 0, 0.5, 1, 1.5, 2, and 3°. Through the experiment, it can be seen that the measurement value is 3.140 at 0°, 3.148 at 0.5°, 3.140 at 1°, 3.151 at 1.5°, 5.078 at 2°, and 4.790 at 3° setting. In addition, the test statistic (P) value is 0.000, which is smaller than the significance level of 0.005, so it was confirmed through the experiment that a measurement error occurs according to the angle change when measuring the surface roughness.

친환경적인 전기자동차, 전기 추진 선박, 하이브리드 자동차, 전철 등의 구성 요소 중 기존 파워 디바이스에서 사용 중인 실리 콘(Si)을 실리콘 카바이드(SiC, silicon carbide)로 대체하려는 연구가 진행 중이다. 고품질의 SiC 결정 성장을 시키기 위해 다양한 방법 중 상 부 종자 용액 성장(top seeded solution growth, TSSG)법이 큰 주목을 받고 있다. 그러나 SiC 결정 성장 시, 느린 성장 속도뿐만 아니라 많은 결함을 갖는 문제를 갖고 있다. 그래서 본 연구에서는 SiC 단결정을 성장 시키는 TSSG법의 개선을 위한 기초 연구를 진행하였다. 기존에 많이 사용되는 Si, Si0.6Cr0.4 용융 물질와 탄소 도가니와 관계를 가열 온도에 따른 접촉각과 자연 냉각 후 시료의 단면의 차이점을 통해 비 교 분석하였다. 젖음성 분석 시험 장비를 이용하여 탄소 도가니로 쓰이는 카본판 위에 Si과 Si0.6Cr0.4를 놓고 가열 및 용융 시키며 접촉각의 변화를 측정하였고, 가열 종료 후 자연 냉각된 시료의 단면을 관찰하였다. 결과적으로 1800 ℃에서 Si, Si0.6Cr0.4와 탄소판 간의 접촉각이 10°정도 차이를 나타냈다. 단면 관찰에서는 Si의 경우, 탄소판 안으로 스며든 후 굳은 모습을 확인할 수 있었다. 반면, Si0.6Cr0.4의 경우는 탄 소판 안으로 스며든 범위가 훨씬 더 적게 나타냈다. 본 연구의 결과는 TSSG법을 활용한 SiC 단결정 성장을 위한 연구의 기초 자료로 활용 될 것으로 기대된다.

Background: Core muscles provide important dynamic stabilization of the lumbar spine. The twist sit-up can simultaneously stimulate the external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) muscles. Objectives: The purpose of this study is to investigate the impact of knee angles during twist sit-up exercises and determine the most efficient knee angle for performing this exercise. Design: Cross-sectional study. Methods: The study recruited 30 students from S University regardless of gender. The subjects performed a total of 10 twist sit-ups at five different knee angles (0, 40, 65, 90, and 105 degrees), divided between the ipsilateral and contralateral sides. The thickness of abdominal muscles (EO, IO, and TrA), was measured using ultrasonography on rest position and full contraction position for each angle of knee flexion and compared between angles. Results: There were significant differences in the ipsilateral EO, IO, and TrA muscle thickness at different knee flexion angles (P<0.5). There was a significant difference in the thickness of EO between 0 and 105 degrees and between 40 and 105 degrees (P<0.5), a significant difference in the thickness of IO between 0 and 105 degrees (P<0.5), and a significant difference in the thickness of TrA between 0 and 105 degrees, 40 and 90 degrees, and 65 and 90 degrees (P<0.5). Conclusion: In conclusion, the muscles involved in axial rotation i.e., EO and IO, maximally contract at a knee flexion angle of 105 degrees. Therefore, this may be the most optimal angle to perform twist sit-ups.

Background: Thoracic kyphosis is a condition characterized by an excessive curvature of the thoracic spine, often leading to decreased trunk range of motion and various health complications. Objectives: This study aimed to investigate the effects of a rolling corrector on trunk range of motion (ROM) and thoracic kyphosis angle in individuals with thoracic kyphosis. Design: A randomized controlled trial. Methods: Thirty participants with a thoracic kyphosis angle of 40 degrees or more were randomly assigned to either the rolling corrector group (RCG) or the control group (CG). The RCG used the rolling corrector for 30 minutes per session, five times a week for two weeks, while the CG received no intervention. Trunk ROM and thoracic kyphosis angle were measured before and after the intervention. Results: The RCG showed significant improvements in trunk flexion, extension, lateral flexion, and rotation ROM, as well as in the thoracic kyphosis angle, in within-group comparisons (P<.05). The CG did not exhibit significant changes in any of these variables (P<.05). Significant differences between the RCG and CG were observed in trunk ROM and thoracic kyphosis angle (P<.05). Conclusion: The rolling corrector was effective in improving trunk ROM and reducing the thoracic kyphosis angle in individuals with thoracic kyphosis. These findings suggest that the rolling corrector may be a beneficial intervention for managing thoracic kyphosis.