본 연구의 목적은 해부학적 근거로 제작한 5가지의 EMS 요추 복압 벨트가 요추 안정화에 미치는 영향을 연구하는 것이다. 본 연구는 요방형근, 척추세움근, 내복사근, 외복사근, 대요근으로 총 5가지의 코어 근육을 선정하여 이에 맞는 근육 모양과 통증 유발점인 압통점을 고려해 전도성 원단으로 패턴을 설계하여 복압 벨트에 결합했다. 총 4가지 동작으로 실험을 진행하여 각각 다른 EMS복압 벨트가 요추 안정화에 미치는 영향을 알아보았다. 건강한 신체의 20대 남성 5명을 대상으로 진행하였고 선정 조건은 최근 3개월 동안 요통 과거력이 없고 사전 검사를 통해 제한되는 동작이 없고, 체간의 근력이 정상등급에 속한 대상이다. 실험 동작의 순서는 하지직거상 검사, 좌전굴, 체전굴, 배근력으로 다음 동작에 제한되지 않게 선정하였다. 동작 간의 휴식은 2분으로 진행하였고, EMS복압 벨트를 착용 후 실험을 진행할 때는 혈류량 증가와 근 활성화를 위해 전기자극을 10분씩 적용하고 진행하였다. 실험 결과의 통계는 비모수 검정으로 윌콕슨 검정과 프리드만 검정을 실시함으로 구체적인 차이를 분석하였다. 본 연구의 결과 5가지의 패턴 중 5,4,3,1,2 순으로 Type별 순위 결과를 확인할 수 있었으며 각 근육의 움직임과 연관성이 있는 실험 동작에 조금 더 유의미한 결과를 확인할 수 있었다. 본 연구의 결론은 해부학적 근거로 제작된 패턴으로 인해 각 근육에 각기 다른 모양으로 전기자극을 전달하였을 때 구분되는 효과를 확인할 수 있었으며 일반인 대상으로 일상생활이나 트레이닝에 있어 요추 안정화를 향상할 수 있을 것으로 기대된다.

Deep learning, which has recently shown excellent performance, has a problem that the amount of computation and required memory are large. Model compression is very useful because it saves memory and reduces storage size while maintaining model performance. Model compression methods reduce the number of edges by pruning weights that are deemed unnecessary in the calculation. Existing weight pruning methods using ADMM construct an optimization problem by a layer-by-layer addition of pre-defined removal-ratio constraints. Decomposing into two subproblems through the ADMM process, one can solve them through gradient descent and projection. However, the layer-by-layer removal ratios must be structurally specified, causing a sharp increase in training time due to a large number of parameters, and hardly feasible to use for large models that actually require weight pruning. Our proposed method performs weight pruning, producing similar performance, by setting a global removal ratio for the entire model without prior knowledge of structural characteristics in order to solve the shortcomings of the existing ADMM weight-pruning methods. To effectively avoid performance degradation, the method removes a relatively small number of previous layers in charge of feature extraction. Experiments show high-quality performance, not necessarily setting layer-by-layer removal ratios. Additionally, experiments increasing layers yield an insight for feature extraction in pruned layers. The experiment of the proposed method to the LeNet-5 model using MNIST data results in a higher compression ratio of 99.3% outperforming those of other existing algorithms. We also demonstrate the effectiveness of the proposed method in YOLOv4, an object detection model requiring substantial computation.

In this study, in order to manufacture STS 316L seamless pipes with 18mm, 25mm, and 42mm diameters that can be used for high pressure, we intend to make predictions through design and finite element analysis and produce real objects. It was measured to have the highest hardness value in the deformed part, and it is expected to be due to work hardening. It has been interpreted that plastic deformation does not occur up to 1,000bar for STS 316L seamless pipes with a diameter of 18mm and 25mm, but plastic deformation occurs at 900bar or more in STS 316L seamless pipes with a diameter of 42mm.

In this paper, the performance characteristics of a cryogenic refrigeration system used in fields such as HMR(Home Meal Replacement) that require ultra-low temperatures of -50℃ using natural refrigerants according to the recent enforcement of the Atmosphere Environment Conservation Act were investigated. For this purpose, a 2-stage compression refrigeration system using R744(CO2) and a cascade refrigeration system using R747/R404A and R747/R717(NH3) were applied. The COP(coefficients of performance) of each refrigeration system were compared according to changes in evaporation and condensation temperature, subcooled and superheated degree. Although the coefficient of performance of the 2-stage compression refrigeration system using R744 was superior to that of the cascade refrigeration system, 2-stage refrigeration system was considered that various problems should be solved in practical terms. In addition, the COP of R744/R717 for various operating conditions showed similar results to R744/R404A, so the possibility of alternativeness could be confirmed in the cascade refrigeration system.

To investigate the effect of gas dispersing carbon nanotubes (CNTs) and hot pressing method on the transparency and the conductivity of thin films, the free arc was used to disperse the CNTs in a high dispersion rate, and the dispersed CNTs were rapidly pressed into the surface of the PET film by hot pressing to obtain electrical conductivity. The relationship between the light transmission and sheet resistance of the film was studied by changing the deposition time and the presence or absence of electrostatic adsorption. It was found that the CNTs modified film still retains good electrical conductivity (sheet resistance up to 6 × 104 Ω, light transmittance 69%) through the cleaning of surfactants and ultrasonic waves, which proves that hot pressing is a simple physical method to achieve effective combination of CNTs and films.

본 논문은 철계형상기억합금(Fe-SMA) 나선철근을 이용한 기둥의 횡구속 효과를 평가한 실험적 연구를 보고한다. 실험을 위해 사전변형 4%의 5mm × 5mm의 Fe-SMA 나선철근으로 구속된 150mm × 150mm ×300mm의 원형 실험체가 제작되었다. 실험변수는 Fe-SMA 나선철근의 피치(0mm, 80mm, 60mm, 40mm), Fe-SMA 나선철근의 활성화 유무(활성화, 비활성화)를 고려하였다. Fe-SMA 나선철근 활성화를 위해 소성로를 사용하여 목표온도 140℃까지 가열하였다. 실험체의 온도가 상온에 도달한 후 만능재료시험기를 이용하여 1축 압축실험을 실시하였다. 실험결과를 통해 Fe-SMA 나선철근을 활성화하여 능동적 횡구속압이 작용된 실험체의 최대응력과 최대응력 발현 시의 변형률은 활성화하지 않은 실험체에 비해 크게 증가하는 것으로 나타났다. 또한, 나선철근 피치의 감소로 인해 능동적 구속압이 증가함에 따라 최대응력과 연성지수가 크게 증가하는 것으로 나타났다. 특히 보강 간격이 40mm인 활성화된 나선철근으로 구속된 실험체는 최대하중 도달 후 하중이 유지 및 증가하는 변형경화가 발생하는 것으로 나타났다.

Purpose: This study compares the chest compression quality, and the willingness and confidence to perform cardiopulmonary resuscitation (CPR) before and after education between the compression only CPR (COCPR) group and the standard CPR (STCPR) group using manikins. Method: This study employs a randomized controlled trial design. A total of 219 and 214 individuals were randomly assigned to the COCPR and STCPR groups, respectively. Both groups were asked to perform CPR for 2 min before and after education. The willingness and confidence to perform CPR were surveyed through a questionnaire. Results: Before education, the STCPR group had a significantly higher mean chest compression depth and accuracy than the COCPR group for the entire 2 min. After education, the STCPR group had a significantly higher mean chest compression depth for 2 min and higher compression accuracy for late 1 min than the COCPR group. However, no significant difference in the willingness and confidence to perform CPR according to the compression method was evident. Conclusion: Repeated training is required to maintain chest compression quality. CPR education improves willingness and confidence to perform CPR.

The wind turbine blades should be designed to possess a high stiffness and should be fabricated with a light and high strength material because they serve under extreme combination of lift and drag forces, converting kinetic energy of wind into shaft work. The goal of this study is to understand the basic knowledge required to curtail the process time consumed during the construction of small wind turbine blades using carbon fiber reinforced polymer (CFRP) prepeg composites. The configuration of turbine rotor was determined using the QBlade freeware program. The fluid dynamics module simulated the loads exerted by the wind of a specific speed, and the stress analysis module predicted the distributions of equivalent von Mises stress for representing the blade structures. It was suggested to modify the shape of test specimen from ASTM D638 to decrease the variance in measured tensile strengths. Then, a series of experiments were performed to confirm that the bladder compression molded CFRP prepreg can provide sufficient strength to small wind turbine blades and decrease the cure time simultaneously.

The high-temperature properties of mild steels were studied by comparing the test results of Kwon and the yield strength, tangent modulus predicted by the design provisions of ASCE and Eurocode(EC3). The column strengths for steel members at high temperatures were determined by the elastic and inelastic buckling strengths according to elevated temperatures. The material properties at high temperatures should be used in the strength evaluations of high temperature members. The buckling strengths obtained from the AISC, EC3 and approximate formula proposed by Takagi et al. were compared with ones calculated by the material nonlinear analysis using the EC3 material model. The newly simplified formulas for yield stress, tangent modulus, proportional limit and buckling strength which were proposed through a comparative study of the material properties and buckling strengths. The buckling strengths of proposed formulas were approximately equivalent to ones obtained from the formulas of Takagi et al. within 4% . They were corresponded to the lower bound values among the buckling strengths calculated by the design formulas and inelastic buckling analysis.

In this technology development, we have developed an automation system after developing a material rotation mixing process so that the manual process of sound absorbing materials can be supplied in quantities. After setting up 5kgf supply of the fused acoustic material, the setting value of 5kg was automatically supplied to the molded frame to reach the quantification supply. In the process of producing noise goods between floors, the automatic compression system was developed, which was a manual operation of three persons, and the production of one person was allowed, and the production of 200 sound absorbers per day, It has improved to 450. Quantitative supply unit was developed to reach 50.7mm for target 50±3mm based on the sound absorption product thickness indication, reducing the defect rate to less.

The BX composite beam is designed to have the same cross-section regardless of the size of the momentum, which is a disadvantage of the existing steel structure. Combination of the H-beam end compressive material and the H-section steel tensile reinforcement according to the moment size in a single span, It is possible to say that it is an excellent synthesis which increases the performance. When underground and overhead structures are constructed, it is possible to reduce the bending, increase lateral stiffness, reduce construction cost, and simplify joints. The seamability of the joining part is a simple steel composite beam because of the decrease of the beam damping at the center of the beam and the use of the end plate of the new end compressing material. In the case of structures with long span structure and high load, it is advantageous to reduce the material cost by designing large steel which is high in price at less than medium steel.

Background: Uncontrolled lumbopelvic movement leads to asymmetric symptoms and causes pain in the lumbar and pelvic regions. So many patients have uncontrolled lumbopelvic movement. Passive support devices are used for unstable lumbopelvic patient. So, we need to understand that influence of passive support on lumbopelvic stability. It is important to examine that using the pelvic belt on abdominal muscle activity, pelvic rotation and pelvic tilt. Objects: This study observed abdominal muscle activity, pelvic rotation and tilt angles were compared during active straight leg raise (ASLR) with and without pelvic compression belt. Methods: Sixteen healthy women were participated in this study. ASRL with and without pelvic compression belt was performed for 5 sec, until their leg touched the target bar that was set 20 ㎝ above the base. Surface electromyography was recorded from rectus abdominis (RA), internal oblique abdominis (IO), and external oblique abdominis (EO) bilaterally. And pelvic rotation and tilt angles were measured by motion capture system. Results: There were significantly less activities of left EO (p=.042), right EO (p=.031), left IO (p=.039), right IO (p=.019), left RA (p=.044), and right RA (p=.042) and a greater right pelvic rotation angle (p=.008) and anterior pelvic tilt angle (p<.001) during ASLR with pelvic compression belt. Conclusion: These results showed that abdominal activity was reduced while the right pelvic rotation angle and anterior pelvic tilt angle were increased during ASLR with a pelvic compression belt. In other words, although pelvic compression belt could support abdominal muscle activity, it would be difficult to control pelvic movement. So pelvic belt would not be useful for controlled ASLR.

Background: Lumbopelvic stability is highly important for exercise therapy for patients with low back pain and shoulder dysfunction. It can be attained using a pelvic compression belt. Previous studies showed that external pelvic compression (EPC) enhances form closure by reducing sacroiliac joint laxity and selectively strengthens force closure and motor control by reducing the compensatory activity of the stabilizer. In addition, when the pelvic compression belt was placed directly on the anterior superior iliac spine, the laxity of the sacroiliac cephalic joint could be significantly reduced. Objects: This study aimed to compare the effects of EPC on lumbopelvic and shoulder muscle surface electromyography (EMG) activities during push-up plus (PUP) and deadlift (DL) exercise, trunk extensor strength during DL exercise. Methods: Thirty-eight subjects (21 men and 17 women) volunteered to participate in this study. The subjects were instructed to perform PUP and DL with and without the EPC. EMG data were collect from serratus anterior (SA), pectoralis major (PM), erector spinae (ES), and multifidus (MF). Trunk extensor strength were tested in DL exercise. The data were collected during 3 repetitions of all exercise and the mean of root mean square was used for analysis. Results: The EMG activities of the SA and PM were significantly increased in PUP with pelvic compression as compared with PUP without pelvic compression (p<.05). In DL exercise, a significant improvement in trunk extensor strength was observed during DL exercise with pelvic compression (p<.05). Conclusion: The results of this study indicate that lumbopelvic stabilization reinforced with external pelvic compression may be propitious to strengthen PUP in more-active SA and PM muscles. Applying EPC can improve the trunk extensor strength during DL exercise. Our study shows that EPC was beneficial to improve the PUP and DL exercise efficiency.