본 연구는 철도교 노후화에 따른 열차운행 중 신속 교체 및 재난·재해에 대한 급속 시공을 통하여 공기단축 및 시공성 확보로 국민의 사회적·경제적 피해를 최소화하고자 한다. 철도교 개량 등에서 필 수적인 8철도하로교 시공고도화 및 성능향상9을 위하여 신속 교체와 성능향상이 가능한 강합성 철도하 로교 설계·제작·시공 기술을 개발하고자 한다. 또한, 개발하고자 하는 강합성 하로교의 경우 철도교뿐 만 아니라 도로교에서 적용하고자 하며, 철도교는 상부구조가 단경간 형식으로 이루어지고 있어 철도 교 사용성 검토에 큰 문제가 없으나 도로교의 경우 바닥판 연속화를 고려 중에 있어, 이에 대한 온도 및 부모멘트 등 여러 문제점을 검토하였다. 상로교의 경우 다수의 거더에 의해 바닥판이 지지되므로 PS의 중요성이 부각될 수 없지만, 하로교의 바닥판은 양단 거더에 의한 고정지지이므로 RC구조 적용 이 어려워, 강합성 또는 PSC 공법을 일반적으로 적용한다. 기존 강합성 구조는 비용, 공기 측면에서 지양하고 PSC 구조의 가로보 및 바닥판과 강재 거더를 합성한 하로교를 개발하고자 한다.

PSC(Prestressed Concrete)거더 교량은 긴장재(강선)를 통하여 교량 양쪽에서 압축력을 추가하는 방 식으로 외부에 대한 저항력을 확보한다. PSC 거더 교량의 긴장 방식에 따라 콘크리트 타설 전(프리텐 션)과 타설 후(포스트텐션)로 구분할 수 있다. 반면에 프리텐션 긴장의 경우 강선이 구조물과 직접 결 합하는 방식이기 때문에 전용관 삽입 및 그라우트 채움 공정이 생략되어 하중이 비교적 가벼울 뿐만 아니라, 긴장재 부식 방지를 위한 유지관리에 매우 효율적이다. 그러나 프리텐션 긴장 방식은 별도의 긴장 시설이 필요하므로 주로 공장에서 제작되고, 건설 현장까지 이동이 필요하기 때문에 길이 (L=18m) 및 무게(W=30tonf)의 제한이 있다. 프리텐션 긴장 공법의 경우 별도의 반력대 및 긴장 시설 이 필요하여 주로 공장에서 제작하고 현장으로 이동 및 설치되고 있다. 도로를 이용한 이동이 필요하 기 때문에 거더의 경간 및 중량의 제한이 발생하게 된다. 따라서, 경간장 25 m 이상의 거더의 경우 포스트텐션을 통한 현장 제작이 주로 이루어 지고 있다. 본 연구에서는 별도의 시설없이 현장에서 프 리텐션 긴장이 가능한 PSC 거더 시공 공법을 제안하였다. 또한, 장경간 PSC 거더 제작을 위한 포스트 텐션 기반의 세그먼트 제작 공법을 제안하고, 그 성능을 검증하였다.

In recent automobile development, vehicle weight reduction has become a very important goal. Seat weight reduction is a large portion of vehicle weight reduction. In this study, a specimen tensile tests were conducted on the Almag material, which is an alloy of aluminum and magnesium, and also conducted on SAFH440, SAFH 590, SAFC780, and SAFH980, which are mild steel materials used in the seat frame. The tensile specimen tests were carried out in two speed; 2mm/s and 4mm/s, and the obtained stress to strain curve was converted to the analysis material card of true stress to true strain curve to be used in the seat structural analysis. The constructed analysis material card was used in the specimen tensile finite element analysis, and the analysis result was able to obtain the stress to strain curve similar to the test result.

High-entropy alloys (HEAs) are characterized by having five or more main elements and forming simple solids without forming intermetallic compounds, owing to the high entropy effect. HEAs with these characteristics are being researched as structural materials for extreme environments. Conventional refractory alloys have excellent hightemperature strength and stability; however, problems occur when they are used extensively in a high-temperature environment, leading to reduced fatigue properties due to oxidation or a limited service life. In contrast, refractory entropy alloys, which provide refractory properties to entropy alloys, can address these issues and improve the hightemperature stability of the alloy through phase control when designed based on existing refractory alloy elements. Refractory high-entropy alloys require sufficient milling time while in the process of mechanical alloying because of the brittleness of the added elements. Consequently, the high-energy milling process must be optimized because of the possibility of contamination of the alloyed powder during prolonged milling. In this study, we investigated the hightemperature oxidation behavior of refractory high-entropy alloys while optimizing the milling time.

이 연구 논문은 기후 변화에 대한 전 세계적인 우려와 온실 가스 배출 감소를 위한 필수적인 요구에 대응하여 마 이크로기공 고분자(PIM-1)의 이용을 탐구한 것이다. 연구는 PIM-1 막을 이산화탄소(CO2) 가스 분리 막으로 사용하는 현대적 인 소재로서의 응용에 집중하고 있다. 연구는 PIM-1 막의 합성, 분자량 제어, 그리고 제각각의 특성 분석 기술을 통해 포괄적 인 통찰을 제공하며, 이러한 특성 분석 기술을 통해 PIM-1의 고유한 교차결합 및 강성 구조에서 비롯된 내재적 다공성이 특 히 이산화탄소의 선택적 투과에 활용되고 있다. 논문은 PIM-1의 가교된 구조로부터 비롯된 내재적 다공성이 특히 이산화탄 소의 선택적 투과에 활용되고 있다. 논문은 PIM-1의 튜닝 가능한 화학적 특성을 강조하며, 가스 분리 막의 맞춤 및 최적화를 가능케 하는 특성에 대한 이해를 제시하고 있다. 분자량을 통제함으로써 고분자량(H-PIM-1) 막은 낮은 분자량 대비 더 뛰어 난 CO2 투과성과 선택성을 나타내며, 이를 통해 PIM-1 막의 특성을 조절하는 데 분자량의 중요성을 강조하고 있다. 연구 결 과는 PIM-1 막 특성을 조절하는 데 분자량이 중요한 역할을 하는 것을 강조하며, 이는 기후 변화의 긴급한 글로벌 도전에 대 응하기 위한 효율적이고 선택적인 CO2 포집을 위한 차세대 막 기술의 발전에 기여하고 있다.

In this study, the elastic properties of aluminium nanocomposite representative volumetric element (RVE) reinforced with GNP have been analysed. Pure aluminium is lightweight and has low strength which is not suitable for various aerospace applications. Adding graphene to aluminium gives a highly strengthened nano-matrix. A 3D multiscale finite element (FE) representative volumetric element (RVE) has been developed to estimate the mechanical behaviour of GNP-reinforced aluminium graphene nanocomposite (AGNC). The factors influencing the behaviour of AGNC have been investigated with different weight fractions (wt%), sizes and orientations of GNP. The Young’s modulus of AGNC is enhanced by increasing the wt% of GNP and reducing the size of GNP in the aluminium matrix. The Young’s modulus of AGNC with 1% wt% has been enhanced two times and yield strength by five times than pure Al matrix. In the case of different sizes of GNP, the strength of 15-nm-diameter GNP AGNC enhanced two times and medium-sized GNP, i.e. 30 nm has shown a great combination of strength and ductility. After that different orientations have also influenced the mechanical properties and enhancement shown in layered orientation compared to different angles of GNP.

Background: A decrease in physical activity has been observed due to the global pandemic, resulting in the onset and progression of musculoskeletal disorders as chronic diseases. Objectives: This study aimed to assess the difference in the degree of contraction of the lower limb muscles between the existing vertical vibration method and a new cross-vibration method. Design: Randomized controlled trial. Methods: The exercise program using whole-body vibration equipment was conducted for 12 sessions, 25 min per session, three times per week for 4 weeks. Results: The changes over time showed a significant difference in cross-alternating vibrations (P<.05), except for the lateral gastrocnemius and tibialis anterior, with no significant difference in sonic vertical vibration (P>.05). The interaction between time and group was significant for all muscles (P<.05), except for the biceps femoris, with differences between before the program and at 2 and 4 weeks after the program revealed in the post-hoc analysis. Conclusion: Future studies should further evaluate the use of CAV exercise devices as auxiliary equipment in exercise by assessing different groups and variations in intensity.

본 연구의 목적은 Y-Balance Test(YBT)를 통하여 무게부하 증가가 동적 균형에 미치는 영향을 알아보고자 하였다. 연구의 대상자는 20-30대 남녀 성인 18명(연령: 23.17±1.72 years, 신장: 172.46 ±9.84 cm, 체중: 73.39±11.44 kg 다리길이: 88.89±5.69 cm)이 실험에 참여하였다. 동적 균형 측정을 위하여 YBT를 통하여 도달거리와 종합점수, COP 변인들을 측정하여 결과를 도출하였다. 연구결과로 YBT 시 후내측과 후외측 도달거리, 종합점수에서 무게부하일 때 동적 균형이 향상되었다. COP 결과로, 전방 도달 동안 전후진폭, 좌우 COP속도, COP 면적은 오른발에서 무게부하 시 동적 균형이 향상되었지 만, 후내측 도달 동안 차이가 없었고, 후외측 도달 동안 좌우진폭은 왼발에서, 전후 COP속도는 왼발, 좌우 COP속도와 COP속도는 좌우발에서, COP 면적은 좌우발의 무게부하 시 동적 균형이 향상되었다.

This study developed and evaluated a load cell-based automatic weighing system for the automated harvesting of laver (Porphyra tenera) in seaweed aquaculture. The current manual harvesting process was compared with the load cell-based automated system, and quantitative measurements of time, distance, and weight were conducted. The results demonstrated that the load cell-based system reduced the unloading time and increased the throughput compared to the manual method. In addition, statistical analysis confirmed that there was no significant difference from the mean in the weight measurement obtained using the load cell-based system. Based on these findings, the load cell-based automatic weighing system holds potential for efficient production and transactions in laver cultivation, contributing to cost reduction and improving the quality of life for aquaculture workers.

Background: The weakness of the gluteus medius (GM) is associated with various musculoskeletal disorders. The increasing GM activity without synergistic dominance should be considered when prescribing pelvic drop exercise (PD). Isometric hip extension or flexion of the non-weight bearing leg using thera-band at the ankle during PD may influence hip abductor activities. Objects: To determine how isometric hip extension or flexion of the non-weight bearing leg using thera-band at the ankle during PD influences the activities of three subdivisions of GM (anterior, GMa; middle, GMm; posterior, GMp), tensor fasciae latae (TFL), contralateral quadratus lumborum (QL), and GMp/TFL, GMm/QL activity ratios in patients with GM weakness. Methods: Twenty-three patients with GM weakness were recruited. Three types of PD were performed: PD, PD with an isometric hip extension of the non-weight bearing leg (PDE), and PD with an isometric hip flexion of the non-weight bearing leg (PDF). Surface electromyography (SEMG) was used to measure hip abductor activities. One-way repeated-measures analysis of variance was used to assess the statistical significance of muscle activities and muscle activity ratios. Results: GMa, GMm, and GMp activities were significantly greater during PDF than during PD and PDE (p < 0.001, p = 0.001; p = 0.001, p = 0.005; p = 0.004, p = 0.004; respectively). TFL activity was significantly greater during PDE than during PD and PDF (p < 0.001, p < 0.001, respectively). QL activity was significantly greater during PDF than during PD (p = 0.003). GMp/TFL activity ratio was significantly lower during PDE than during PD and PDF (p = 0.001, p = 0.001, respectively). There were no significant differences in the GMm/QL activity ratio. Conclusion: PDF may be an effective exercise to increase the activities of all three GM subdivisions while minimizing the TFL activity in patients with GM weakness.

Background: In order to improve the daily life of stroke patients, it is necessary to restore walking performance. Improving gait performance is one of the main goals for stroke rehabilitation. Objectives: To investigate the change in gait parameters through evaluation of one stroke patient before, during, and after wearing the weight vest. Design: A case study. Methods: This study is an ABA study design. In principle, one assessment per day (A1) was measured three times without wearing the weight vest. Intervention assessment (B) was performed 6 times while wearing the weight vest. The second baseline evaluation (A2) was measured three times with the weight vest removed again. Results: The gait speed was increased when the weight vest was removed than when the weight vest was worn. Also, gait symmetry increased when wearing the weight vest. Conclusion: Wearing the weight vest can reduce the gait asymmetry in stroke patients and increase the gait speed after wearing the weight vest.

Background: A weight-bearing jacket during treadmill gait training is being used for rehabilitation in stroke patients. However, the effect on various gait parameters has not been confirmed. Objectives: The purpose of this study was to investigate the comparison of exercise intensity through speed increase and weight-bearing jacket during treadmill gait training to restore gait ability in stroke patients. Design: Randomized controlled trials. Methods: This study recruited 24 stroke patients. The subjects were randomly assigned to the experimental group (wearing a weight-bearing jacket during treadmill gait training, n=12) and the control group (speed increase during treadmill gait training, n=12). Gait measurement device (G-walk) was used to measure the gait parameters of the subjects. Results: Both the experimental group and control group showed a significant increase in cadence, gait speed, stride length, and gait symmetry index post intervention (P<.05). In comparison between the two groups, the experimental group showed a significant increase in the gait symmetry index post the intervention than the control group (P<.05). Conclusion: Through this study, it was found that wearing a weight-bearing jacket was a more effective method for improving the gait symmetry index than increasing speed during treadmill gait training in stroke patients.

Recently 3d printer industry has two demands. first is color 3d printing. second is mass production using 3d printer that has large bed. According to previous studies, 3D printed objects have different weights depending on filament colors. 3D printed tensile specimens with filaments of various colors were checked to see they had the same weight. If so, we wanted to see it was statistically significant. As a result, we found that the weight of 3D printed objects was statistically significantly different depending on the filament color. The average weight of 3d printed objects is: Black(8.63g), Blue(8.58g), Yellow(8.53g), White(8.48g), Natural(8.46g), Green (8.45g), Red(8.42g).

In this paper, the mechanical properties according to the rCF weight percent(10, 20, 30, 40, 50wt%) of the rCFRP specimen were evaluated and analyzed. First, to prepare rCFRP specimens, pellets were prepared according to the type of weight percent, and rCFRP tensile specimens according to ASTM D638 were prepared using an injection molding machine. Tensile tests were performed on each of 10 specimens according to weight percent conditions, and tensile strength and modulus of elasticity were calculated. For a detailed analysis of the correlation between the internal structure of the specimen and the mechanical properties, the weight percent to the constituent materials of the rCFRP specimen was calculated using mCT and used for the analysis of mechanical properties. For a more detailed analysis, a detailed analysis of the mechanical properties of rCFRP was performed through the fracture surface analysis of the specimen using FE-SEM.

Thermal protection systems (TPS) are a group of materials that are indispensable for protecting spacecraft from the aerodynamic heating occurring during entry into an atmosphere. Among candidate materials for TPS, ceramic insulation materials are usually considered for reusable TPS. In this study, ceramic insulation materials, such as alumina enhanced thermal barrier (AETB), are fabricated via typical ceramic processing from ceramic fiber and additives. Mixtures of silica and alumina fibers are used as raw materials, with the addition of B4C to bind fibers together. Reaction-cured glass is also added on top of AETB to induce water-proof functionality or high emissivity. Some issues, such as the elimination of clumps in the AETB, and processing difficulties in the production of reusable surface insulation are reported as well.

Many manufacturers applying third party logistics (3PLs) have some challenges to increase their logistics efficiency. This study introduces an effort to estimate the weight of the delivery trucks provided by 3PL providers, which allows the manufacturer to package and load products in trailers in advance to reduce delivery time. The accuracy of the weigh estimation is more important due to the total weight regulation. This study uses not only the data from the company but also many general prediction variables such as weather, oil prices and population of destinations. In addition, operational statistics variables are developed to indicate the availabilities of the trucks in a specific weight category for each 3PL provider. The prediction model using XGBoost regressor and permutation feature importance method provides highly acceptable performance with MAPE of 2.785% and shows the effectiveness of the developed operational statistics variables.