Background: Core stability exercises are widely applied in rehabilitation and training programs, but evidence regarding the effects of activation strategies and surface conditions on abdominal muscle recruitment during plank exercise remains inconsistent. Objects: This study aimed to investigate how different activation strategies (hollowing vs. bracing) and surface conditions (stable vs. unstable) influence selective activation of abdominal muscles during the plank exercise. Methods: Thirty-six healthy male adults in their 20s participated. Ultrasound imaging was used to measure the relative thickness of the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) under four randomized conditions: stable-hollowing, stable-bracing, unstable-hollowing, and unstable-bracing. Relative thickness was calculated as [(contraction – rest) ÷ rest] × 100. Data were analyzed using three-way repeated-measures ANOVA with Bonferroni comparison. Results: No significant three-way interaction was found (p = 0.840). However, a significant muscle × surface interaction indicated that TrA thickness increased more on a stable surface (p < 0.05), while IO and EO showed no difference. A significant muscle × strategy interaction revealed that hollowing induced greater relative thickness in all muscles, particularly in TrA, compared with bracing (p < 0.001). No significant strategy × surface interaction was observed (p = 0.512). Conclusion: Abdominal hollowing and a stable surface independently enhanced TrA thickness during plank exercise. These findings suggest that stable-surface plank exercise with hollowing is an effective strategy for selectively recruiting deep abdominal muscles, providing practical implications for clinical and sports settings. These findings may be specific to anklesling– induced instability and may not extend to other types of unstable surfaces.

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.

최근 폭염·폭우 등 극한기후의 증가와 공항 포장의 고하중·고타이어압 하중 조건으로 인해 조기 열화 및 파손 위험이 커지는 상황에 서 본 연구는 국내 포장 입도의 공항 에어사이드 표층 적용 가능성을 평가하고 국내 실정에 맞는 품질관리 및 적용 기준 마련을 목적 으로 수행되었다. 이를 위해 국내 바인더 3종(PG 64-22, 76-22, 82-22)에 대해 DSR, BBR, MSCR 시험을 실시하여 고온 소성변형 저 항성과 개질 바인더 적용 적합성을 검토하고, FAA Gradation 1, 2와 국내 입도(WC-2, WC-4, WC-5, SMA-13 mm)를 사용한 혼합 물을 제작하여 동탄성계수(E*), 함부르크 휠트래킹(HWTT), 수분저항성(TSR), 피로균열 저항성 등 주요 역학적 성능을 평가하였다. 그 결과, 국내 WC 및 SMA 혼합물은 FAA 입도 혼합물과 비교해 동등하거나 일부 항목에서 상회하는 성능을 나타내어 공항 포장용 재료로서의 적용 가능성을 확인하였다. 향후 철저한 플랜트 관리, 적정 배합설계, 공인시험 기반 품질관리 체계가 확보된다면, 국내 재 료 수급 및 생산 여건을 반영한 합리적인 공항 아스팔트 포장 품질관리 기준 수립의 기초자료로 활용될 수 있을 것으로 판단된다.

최근 기후 조건의 변동성이 커지면서 포장 표층의 성능 저하가 더 자주 관찰되고 있으며, 공항 에어사이드 구간에서는 이러한 손상 이 곧바로 운항 위험으로 이어질 수 있다. 국내 공항 아스팔트 표층은 통상 FAA 혼합물 입도 체계를 바탕으로 설계·시공되어 왔지만, 국내 골재 수급과 생산 환경을 고려하면 국내 포장 입도를 공항 표층 재료로 활용할 수 있는지에 대한 검토가 필요하다. 본 연구에서 는 FAA 입도와 국내 혼합물의 입도 및 실험 물성(동탄성계수 등)을 비교하고, 이를 FAARFIELD 입력에 반영하여 표층 재료 변경이 설계수명에 미치는 영향을 확인하였다. 분석에는 A·B 공항의 최근 5년 항공기 교통량 자료를 사용하였으며, 표층 효과를 분리하기 위 해 표층 두께와 기층 이하 조건은 동일하게 유지한 채 표층 물성만 교체하여 설계수명 결과를 비교하였다. 그 결과, 국내외 입도 적용 에 따른 요구 두께 차이는 대체로 크지 않았고, 일부 조건에서는 국내 혼합물 적용 시 표층 두께가 더 얇게 산정되어 경제적 대안 가 능성을 확인하였다. 다만 본 연구는 동탄성계수 중심의 구조적 비교에 초점을 두었으므로, 러팅·수분민감(박리), 시공 품질(공극·다짐), 기후 및 운용 조건(제동·가속 구간 특성) 등을 함께 고려한 추가 검토가 뒤따를 필요가 있다.

Pavement surface texture plays an essential role in skid resistance, tire–pavement interaction, and wet-weather driving safety. Conventional evaluations of pavement texture are primarily based on two-dimensional (2D) profile measurements, such as Mean Texture Depth (MTD) and Mean Profile Depth (MPD), which cannot fully represent the complex three-dimensional (3D) characteristics of pavement surfaces. As a result, the relationship between surface texture and wet pavement friction is often insufficiently described. Recent advances in high-resolution optical scanning enable detailed acquisition of surface topography and provide opportunities for more accurate texture quantification. This study proposes a comprehensive framework for characterizing micro- and macro-surface textures using high-resolution 3D scanning combined with both 2D and 3D analytical methods. Dense point-cloud data were collected from concrete pavement surfaces, and multiple longitudinal and transverse profiles were extracted. Fast Fourier Transform (FFT)-based filtering was applied to separate micro- and macro-texture components, and representative texture parameters were calculated from both profile-based and surface-based analyses. Wet pavement friction was evaluated using the British Pendulum Number (BPN), and statistical relationships between texture parameters and friction were examined. The results demonstrate that the proposed approach effectively captures multi-scale texture features and provides improved correlation with wet friction compared with traditional 2D methods. The developed methodology offers a practical basis for texture-based friction evaluation and pavement safety assessment.

The FOPLP method, which uses a square metal carrier to arrange semiconductor chips, offers significantly superior productivity and efficiency compared to conventional processes. However, metal carriers are prone to warping, dents and scratches due to thermal deformation, making surface inspection and correction work essential. Therefore, this study designed and fabricated a gantry guide capable of mounting an indicator and a vision module to effectively inspect the metal carrier surface and improve quality, then evaluated its performance. In the experiment, the gantry system’s performance was verified by evaluating its repeatability precision, and the vision module ensured data reliability through precision at four different magnifications.

Background: Plank exercises are widely used for core stabilization, but the effects of applying instability to different support surfaces on trunk muscle activation remain unclear. Objectives: This study aimed to investigate the effect of support surface instability on the electromyographic activity of trunk muscles including the rectus abdominis, internal oblique and transversus abdominis, multifidus, and longissimus during the plank exercise. Design: This study is quasi-experimental design. Methods: Thirty healthy university students performed plank exercises under four conditions: stable surface, unstable elbows, unstable feet, and unstable both. Muscle activity was measured using wireless EMG. Data were analyzed using one-way repeated measures ANOVA and Scheffé post hoc tests. Results: The rectus abdominis showed a statistically significant increase in muscle activation when both elbows and feet were placed on an unstable surface compared with the stable condition (P<.05). Conclusions: Unstable support surfaces during planks significantly enhance rectus abdominis activation, increasing global muscle recruitment for postural control. Conversely, stable surfaces may be preferable for training deep stabilizers without excessive superficial muscle dominance.

원격운항자는 자율운항선박의 안전 운항에 대한 책임이 있는 사람으로 위급한 상황에 개입하여 원격조종을 수행하는 역할을 수행한다. 기존의 유인선 항해 환경에서는 단일 선박에 선장, 당직사관, 당직 조타수 등의 선교 인력이 동시에 승선하고 있어, 미숙한 선 박조종을 수행할 때에도 이를 지원이 가능한 조직으로 구성된다. 다수의 선박을 동시에 관리하는 원격운항자는 각 선박에 대한 조종 특 성에 대응이 필요하고, 위급한 상황에서만 상대적으로 짧은 시간 동안 개입해야 함에도 단일 선박에만 집중할 수 없는 방식으로서, 긴급 한 선박 조종에 대한 조직적 지원을 제공받기 어려울 것으로 예상된다. 본 연구에서는 원격운항자의 선박조종을 지원하기 위한 선박 조 종 행동 예측 모델 개발을 위한 기초연구로서, 숫자가 아닌 패턴을 활용한 행동 예측 방법을 제안한다. 제안하는 방법론은 선박 조종 데 이터를 패턴화하는 과정, 행동 패턴을 자기회귀 모델에 학습하여, 실제 선박에서의 개인의 조종 습관에 기반한 선박 조종 행동 예측 방법 을 제안하고, 원격운항자의 선박별 선박 조종을 지원하기 위한 선박 조종 행동 예측 모델 활용의 구체적인 예시를 제공한다. 검증된 패턴 을 활용한 행동 예측 방법은 원격운항자의 조종 특성 적응을 지원하는 모델의 개발에 활용될 수 있을 것으로 기대한다.

This study optimized the extraction of β-carotene and antioxidant compounds from orange-fleshed sweet potato (Ipomoea batatas L.) using response surface methodology (RSM) with ethyl lactate as a green solvent. A central composite design (CCD) was utilized to evaluate how the solvent-to-sample ratio, temperature, and extraction time affected efficiency. The regression model was statistically significant (Adj. R2=0.67), revealing that the solvent-to-sample ratio was the most influential factor, while temperature and time had relatively minor effects. The optimal conditions identified were a ratio of 12 mL/g, a temperature of 35°C, and an extraction time of 30 minutes, which resulted in a yield of 27 mg/100g of β-carotene, along with high levels of polyphenols, flavonoids, and strong antioxidant activities as measured by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline- 6-sulfonic acid)) assays. Validation experiments demonstrated a close alignment between predicted and experimental values, confirming the model's robustness. These findings indicate that ethyl lactate effectively extracts not only carotenoids but also a wide range of antioxidants, underscoring its potential as a sustainable solvent for developing functional food ingredients.

본 연구에서는 셀루로오스 나노섬유(CNF) 첨가와 (3-아미노프로필)트라이에톡시실란(APTES)로 표면 처리한 CNF가 시멘트 모르타르 복합체에 미치는 영향을 분석하였다. 일반 시료, 비개질 CNF, APTES 개질 CNF, 그리고 APTES 용액만 첨가한 경우 등 네 가지 조건을 주요 변수로 하여 시험을 진행하였다. 최적 성능은 CNF 0.3 wt%와 APTES 3 vol% 처리 시 나타났으며, 이 조건에서 압축강도와 휨강도가 가장 높게 나타났다. SME, XRD, FT-IR 분석 결과, 처리된 CNF가 수화 생성물과 균일하게 분산되고 화학적으로 결합함을 확인할 수 있었다. 이러한 결과를 통해 ATPES 처리로 CNF의 보강 효과가 시멘트 복합체의 역학적 성능을 크게 향상시킴을 확인할 수 있었다. 따라서 CNF 0.3 wt%와 APTES 3 vol%의 혼입 비율이 시멘트 복합체의 기계적 성능을 향상시키는 가장 효과적인 최적 배합비로 확인되었다.

Pavement friction under wet conditions is a critical factor affecting driving safety and is determined significantly by water-film thickness (WFT). Although current road geometric design standards incorporate wet-pavement friction coefficients as design parameters, they do not adequately account for the effects of WFT. This study estimates the variation in the coefficient of friction caused by changes in the WFT and applies the results to the calculation of stopping sight distance (SSD) and radius of curvature (RC), which are essential elements in road geometry design. Through this approach, the study identifies the limitations of current standards and proposes potential improvements. WFT was estimated using the Gallaway model, which was previously verified through comparative analysis and experimental validation. The model incorporates key influencing factors such as rainfall intensity, pavement slope, drainage path length, and mean texture depth. Based on the estimated WFT, the longitudinal and lateral friction coefficients were calculated using Gallaway’s SN and Lamm’s models, respectively. Using these friction values, the SSD and RC were evaluated under various pavement and environmental conditions. Furthermore, comparisons with existing design guidelines were performed to assess whether the predicted values satisfy the standards under different conditions. Additionally, areas requiring improvement were identified. The analysis confirmed that WFT increases with rainfall intensity and drainage path length, whereas it decreases as the pavement slope, mean texture depth, and tread depth increase. An increase in the WFT significantly reduces the friction coefficient, which consequently increases the SSD and required RC. In particular, under conditions such as heavy rainfall, worn treads, long drainage paths, and shallow surface textures, the calculated SSD and RC typically exceed the minimum requirements of current road-design standards. By contrast, ensuring sufficient surface texture effectively maintains friction performance and mitigates increases in the SSD and RC. The findings of this study suggest that current road-design standards—based on dry or vaguely defined wet conditions—may not sufficiently address the effects of WFT on pavement friction. A quantitative, WFT-based approach is required for more realistic friction estimations. To enhance safety in rainy conditions, road designs should incorporate structural and material improvements, such as optimizing pavement slopes, reducing the drainage path length, maintaining adequate surface texture and tread depth, and adopting high-performance surfacing materials. Additionally, dynamic speed-management systems during rainfall and preventive maintenance for sections with inferior drainage should be considered to improve driving safety under wet weather conditions.

생태계에서 인산염은 중요한 영양물질이지만, 일정 농도 이상일 경우 부영양화의 원인이 된다. 본 연구는 수중 인산염의 제거효율 향상을 위해 Cu(Ⅱ)용액을 이용하여 분말활성탄의 표면개질을 진행하였으며, 회분식 실험을 통해 인산염의 흡착 특성을 분석하였다. SEM 분석을 통해 PAC-Cu 표면에 구리 기반의 결정을 보았고, 용출실험 결과 구리가 정량적으로 24 mg/g 용출된 것을 제시하였다. BET 분석결과 개질 후 비표면적과 기공 부피가 각각 7.53%, 8.66%로 유사하게 감소하였다. 제거 효율 실험에서 PAC-Cu는 PAC대비, 중성인 pH조건에서 최대 3.46배 높은 인산염 흡착능을 보였다. pH 실험에서 PAC의 경우 pH 6에서 최대 효율을 나타내고 있으나, PAC-Cu는 넓은 pH 범위(pH 5~8)에서 일정한 제거효율을 보였다. 등온흡착 모델링 결과, Langmuir와 Sip모델 적용했을 때 최대흡착량은 각각 52.3 mg/g과 126 mg/g으로 PAC의 9.48 mg/g과 31.6 mg/g보다 높은 값을 나타내고 있다. 반응속도실험의 경우, PAC-Cu와 PAC모두에서 30분 이내에서 모두 평형에 도달하였으나, PAC-Cu가 PFO 및 PSO 모델 적용시 높은 k값을 가진다.

Poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) is a promising ferroelectric polymer for flexible electronics and energy-harvesting devices, owing to its high piezoelectric coefficient and mechanical flexibility. Here, we report that electrohydrodynamic instability induces the formation of closely packed nanostructures on PVDF-TrFE thin film. Intriguingly, the strong electric field used in the fabrication process drives the polymeric fluid of PVDF-TrFE upwards to form the surface structures, facilitating molecular dipole alignment and crystalline ordering. This effect contributes to improved crystal alignment, as confirmed by enhanced X-ray diffraction and Raman characteristic peaks. The nanostructured PVDF-TrFE films exhibit enhanced dielectric properties including permittivity, dielectric loss, and ferroelectric polarization. Notably, P-E loop measurements showed a larger remnant polarization and higher saturation polarization in the nanostructured PVDF-TrFE films, indicating improved ferroelectric behavior. Our results suggest that the electrohydrodynamic instability provides a simple but effective route to simultaneously tailor the surface morphology, crystalline phase, and electrical performance of PVDF-TrFE films.

하이드로겔은 친수성 고분자 네트워크로 높은 수분 함량과 생체적합성을 가지며, 조직 공학, 약물 전달 등 다양한 바이오 응용 분야에서 활용되고 있다. 그러나 하이드로겔의 친수성 표면은 약물 방출 속도를 지속적이고 정밀하게 제어하는 데 한계로 작용할 수 있다. 이러한 문제를 극복하기 위해, 약물의 방출 제어가 가능한 표면 개질 기술의 개발이 요구된다. 이 에 본 연구에서는, 표면 개질 기술의 모델 연구로써, poly(2-hydroxyethyl methacrylate) (PHEMA) 하이드로겔 표면의 알코올 기(-OH)를 octyltrichlorosilane (OTS)와 반응시켜 소수성 표면으로 개질하였다. 이러한 접근법은 하이드로겔의 기계적 특성과 같은 벌크 성질을 유지하면서도, 약물의 방출 속도 등에 영향을 주는 표면 특성을 제어할 수 있다. 나아가, 약물 전달뿐 아니 라 조직공학 지지체 및 바이오센서와 같은 생체 소재 개발을 위한 기반 기술로 확장 가능할 것으로 기대된다.

Electrospun nanofibers have emerged as transformative materials due to their unparalleled surface-to-volume ratios, tunable porosity, and excellent mechanical flexibility, making them suitable for energy storage, catalysis, biomedicine, and environmental remediation. However, their inherent surface limitations—poor chemical stability, insufficient active sites, and limited functionality—restrict their full potential. Chemical vapor deposition (CVD) has risen as a game-changing postsynthesis modification strategy, enabling atomic-scale precision in surface engineering. This is also impactful for carbonbased nanofibers, where surface inertness limits their electrochemical performance. This review critically examines advanced CVD techniques, including atomic layer deposition (ALD), plasma-enhanced CVD (PECVD), and initiated CVD (iCVD), which enable the formation of conformal coatings, hierarchical functionalization, carbon nanotube integration, and interfacial optimization of as-spun nanofibers. We highlight breakthroughs in hydrophobicity, catalytic activity, biocompatibility, and energy storage performance, with applications ranging from oil–water separation to nerve gas detoxification, pH-responsive drug delivery, and high-capacity carbon-composite lithium-ion batteries. By dissecting deposition mechanisms, material innovations, and emerging applications, this work highlights the synergy between as-spun nanofibers and the exploitation of CVD techniques in designing versatile materials. Furthermore, advancements hinge on computational modeling, novel precursors, including carbon-rich sources, and scalable processes to bridge lab-scale innovations with industrial deployment are desired. This comprehensive analysis provides a guiding framework for researchers utilizing CVD techniques as a postmodification tool to develop nanofiber-based solutions addressing global challenges in sustainability, healthcare, and energy.