Five novel miniature bipolar radiofrequency (RF) electrode tips with distinct tip geometries (spherical, flat, square, and 45° angled) were developed to enable high-precision tissue ablation. Performance was evaluated on saline-soaked tissue, ex vivo bovine liver, and porcine muscle under consistent RF power settings. All designs produced highly localized lesions only a few millimeters across, confirming precise ablation with minimal damage to surrounding tissue. Tip geometry influenced ablation efficiency: a 45° angled tip created ~5 mm lesions at lower power (highest efficiency), whereas an ultra-fine 1.0 mm tip produced ~1 mm lesions but required higher power. These results indicate that the new bipolar RF electrodes achieve precise, localized tissue ablation with minimal surrounding tissue damage and show promise for precise lesion removal in minimally invasive surgery.

Background: Chronic nonspecific low back pain (CNLBP) is a common musculoskeletal condition among middle-aged adults, often causing physical limitations and reduced quality of life. Transcutaneous electrical nerve stimulation (TENS) is a widely used non-pharmacological method for pain relief and muscle modulation. Objectives: To compare the effects of two high-frequency, high-intensity TENS protocols on pain, muscle tone, and stiffness in individuals with CNLBP. Design: Single-blinded, randomized controlled trial. Methods: Twenty-eight individuals with CNLBP were randomly assigned to an experimental group (EG) or control group (CG). Both received 60 Hz, highintensity TENS twice weekly for four weeks. Pain equivalent current (PEC), visual analogue scale (VAS), pain degree (PD), muscle tone (Hz), and stiffness (N/m) were measured pre- and post-intervention by a blinded assessor. Results: The EG showed significant improvements in all outcomes (P<.05), while the CG showed significant change only in VAS scores. Between-group analysis showed greater reductions in pain and muscle-related variables in the EG. Conclusion: The EG protocol, with individualized intensity adjustments and targeted stimulation sites, was more effective than the CG protocol in improving pain, muscle tone, and stiffness in adults with CNLBP.

Magnetic nanoparticles in nanofluid have a unique ability in that they can be influenced by an external magnetic field, making them a promising heat-exchanging fluid to meet the demands of highly efficient thermal systems. The parametric impact of the magnetic field (static and time-varying) on the heat exchanging rate of Fe3O4 nanoparticles and water-based ferrofluid was investigated in this study. The experimental setup for generating a variable frequency magnetic field and analyzing the thermal behavior of ferrofluid is presented. Temperature data was obtained as heat is transferred from heated water to the ferrofluid used as a coolant. An enhancement of the heat transfer of the magnetic nanofluid was observed when varying the magnetic field frequency, through experimental analysis. The concentration of Fe3O4 nanoparticles in the ferrofluid was varied (0.5 wt%, 1 wt%)to study the impact of nanoparticle loading on heat transfer. An alternative approach for controlling the heat exchange rate in thermal systems is proposed, utilizing the magnetic tunability of the ferrofluid.

Background: Ankle flexibility is important for maintaining proper biomechanical function. Static stretching is used to improve flexibility with minimal risk; however, its effects are often temporary. Transfer of energy capacitive and resistive (TECAR) therapy has the potential to enhance muscle flexibility and circulation through deep heat applications. However, comparative studies evaluating the effectiveness of TECAR therapy and static stretching are lacking. Objects: This study aimed to compare the effects of static stretching therapy (ST) and combined TECAR and static stretching therapy (T-ST) in subjects with gastrocnemius muscle (GCM) tightness. Methods: Twenty-seven participants with bilateral GCM tightness were enrolled. To administer the ST and T-ST, which were each applied to both legs, the participants stood for 15 minutes on a wedge with a 0°–15° incline, with both feet on the wedge during ST and with TECAR therapy in resistive energy transfer mode applied to only one side of the GCM during T-ST. Muscle stiffness (MyotonPRO), dorsiflexion range of motion (DF-ROM), peak torque, and pennation angle (PA) of the GCM were measured before and after the intervention. Normality was confirmed using the Shapiro–Wilk test. Differences between the ST and T-ST leg conditions and between pre- and post-intervention changes in the legs were analyzed using paired t-tests. Results: There were no significant differences in any of the measured variables between the legs before the intervention. ST and T-ST legs showed significant improvements in all measured variables after the intervention (p < 0.05). T-ST legs demonstrated a significantly greater increase in DF and a greater decrease in PA than ST legs (p < 0.05). Conclusion: T-ST outperformed ST in reducing PA and increasing DF-ROM by promoting deep tissue relaxation and stimulating metabolic activity. This may lead to reduced pain and greater flexibility compared to ST. Maintaining an optimal PA ensures efficient force transmission during exercise, as evidenced by the observed increase in peak torque.

Conventional bipolar electrodes (typically with round or flat tips) deliver radiofrequency energy in a broad, continuous manner. Their larger tip size and simple shape cause the applied energy to disperse over a wide area, making precise lesion control difficult and often leading to collateral tissue damage. As a result of these design limitations, traditional electrodes exhibit lower energy efficiency and tend to create lesions that unintentionally extend beyond the target area, with excessive thermal spread to surrounding tissues. In contrast, the five newly developed bipolar electrode designs concentrate energy delivery more effectively and provide improved control over lesion size and shape. These novel electrodes demonstrated higher energy efficiency, produced well-confined lesions, and minimized thermal injury to adjacent tissues, thereby overcoming the major drawbacks of conventional designs.

일반적으로 전기 패널은 용접이나 앵커링을 통해 기초에 설치된다. 콘크리트 기초-앵커 시스템에서 고려해야 할 열화 요인에 는 콘크리트 기초의 균열이 포함된다. 콘크리트 균열은 전기 패널의 앵커에 영향을 미치는 열화 현상 중 하나로 간주될 수 있다. 또한 독립반 및 열반된 전기 패널의 동적 특성은 상당히 다를 수 있다. 그러나 많은 연구자들이 하나의 전기 캐비닛 시편으로 진동대실험을 수행하였다. 따라서 열반 구성을 고려하여 동적 특성을 평가할 필요가 있다. 본 연구에서는 0.5 mm 및 1.0 mm 균열 폭을 고려하여 콘크리트 기초-앵커 시스템을 설계하였다. 콘크리트 기초-앵커 시스템을 진동대에 고정하고 1∼3개의 열반으로 구성된 단순화된 캐비 닛 모델을 설치하였다. 열반 수와 콘크리트 균열을 매개변수로 고려하여 진동대에 의한 공진주파수 검색 실험을 수행했으며 각 실험편 의 공진 주파수를 비교하였다.

Background: Stroke patients commonly experience functional declines in balance and gait due to decreased muscle strength and coordination issues caused by brain damage. Through repetitive training, robot-assisted gait training (RAGT) can aid in promoting neuroplasticity in stroke patients and help them acquire effective gait patterns. Additionally, convalescent rehabilitation hospitals help to ensure rapid recovery through intensive rehabilitation training. Objects: This study investigated the effects of RAGT frequency on gait and balance recovery in stroke patients in convalescent rehabilitation hospitals, providing data to optimize rehabilitation efficiency, enhance functional recovery, and support the development of personalized strategies to ensure safer and more rapid returns to daily life. Methods: This study compared the frequency of RAGT by analyzing a group receiving two units of RAGT per day for 5 days per week with a group receiving two units of RAGT per week as part of a comprehensive rehabilitation program, totaling 16 units daily, in a convalescent rehabilitation hospital. Results: In the 10-minute walking test, statistical significance was observed both within and between groups, whereas the Functional Ambulation Category, Fugl-Meyer Assessment–lower extremities, Berg Balance Scale, and timed up-and-go tests showed significance only within groups. Conclusion: End-effector RAGT and traditional gait training significantly improve gait ability, balance, and lower limb function in stroke patients.

The multi-local resonance metamaterial is based on the local resonance mechanism of resonators, effectively blocking wave propagation within multiple resonant frequency ranges, a phenomenon known as band gaps. In practical applications for vibration reduction, the goal is to achieve wide-band vibration attenuation at low frequencies. Therefore, this study aims to improve the vibration reduction performance of multi-local resonance metamaterials by lowering the band gap frequency and expanding the band gap width. To achieve this, an objective function was formulated in the optimization problem, considering both the frequency and width of the band gap, with the geometric shapes of the multiple local resonators selected as design variables. The Sequential Quadratic Programming (SQP) technique was employed for optimization. The results confirmed that the band gap was generated at lower frequencies and that the band gap width was expanded.

This study compared and analyzed fish communities and mortality rates based on different survey methods (mesh size and retrieval frequency) of stationary nets, which are actively used in freshwater fish surveys in Korea, and proposed an appropriate survey method. Field surveys were conducted on the mainstream of the Nakdong River from May to June 2022 through a total of 10 times of fyke net surveys. The number of species and individuals collected varied significantly depending on the mesh size of the net (5 mm vs. 15 mm) (P<0.001), and larger species with an average total length of over 9 cm were mainly collected in the 15 mm mesh. However, the number of species (P=0.684) and individuals (P=0.100) collected did not show statistically significant differences depending on retrieval frequency (once/24 hours vs. twice/24 hours). In contrast, the mortality rate of fish differed based on all survey methods (mesh size, P<0.001; retrieval frequency, P<0.05), with mortality decreasing as the mesh size increased and retrieval frequency increased. Fyke nets are one of the standard fishing gears used in freshwater fish research in Korea, and to ensure species diversity, it is recommended to maintain the current standard mesh size of 5 mm. However, reducing the current 48-hour deployment time or increasing the retrieval frequency could lower the mortality rate. Furthermore, future research should focus on the differences in fish communities based on the combination of fishing gears commonly used in Korea to improve fish survey methodologies suitable for domestic freshwater environments.

This study aims to analyze the natural frequency characteristics of multi-cracked extensible beams. The model and governing equations of the multi-cracked beam were derived using Hamilton's principle while considering crack energy. The eigenmode functions were obtained through eigenvalue analysis by applying the patching conditions of the cracks, and the equations for the discretized cracked beam were formulated and solved. The displacement responses from nonlinear system analysis were used to calculate frequencies via Fast Fourier Transform (FFT), and the frequency characteristics were systematically analyzed with respect to the number of cracks, crack depth, and cross-sectional loss. Additionally, the natural frequencies and orthonormal bases of the linear system were derived by exploring the solutions of the characteristic equation reflecting the cracks. Numerical analyses showed that the natural frequency of a cracked extensible beam was higher than that of a cracked EB beam. However, as the number or depth of cracks increased, the natural frequency gradually decreased. Notably, in extensible beams with large deflections, the dynamic changes caused by cracks demonstrated results that could not be obtained through the EB beam model.

The performance of various types of silencers used to reduce the micropressure waves radiated from ventilation holes and inclined shafts, which are being studied as measures to reduce micropressure waves in railway tunnels, was evaluated to find an effective silencer. In order to find the optimal silencer, the magnitude and frequency characteristics of the pressure waves emitted from the inclined shaft were analyzed to find an excellent silencer. The evaluation showed that the model with a porous cylinder and a small diameter outer tube was the simplest but performed the best.