• 대한물리치료과학회지
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• 제31권2호
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• pp.1-14
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• 2024

Background: Many patients with chronic low back pain have reduced movement due to pain. For that reason, muscle strength weakens, which leads to pain again. The pain caused by such a vicious circle is not only caused by structural problems, but also by physical function, activity disorder, or psychological depression due to biopsychosocial approaches and pain neuroscience education was applied as an intervention to find out its effect. Therefore, this study was experimented with to find out the effects of pain neuroscience education on pain, physical function, activity disorder, and depression in patients with chronic low back pain. Design: Randomized control trial Method: The study subjects were 39 patients with chronic low back pain, and the study subjects were randomized through computers to the experimental group applying pain neuroscience education and the control group applying only general physical therapy and myofascial release techniques, and the experiment was conducted for 4 weeks. Pressure Pain Threshold , Schober test, Korean Roland-Morris Disability Questionnaire, Korean Oswestry Disability Index, and Korean Depression Screening Assessment were measured. Results: As a result of the study, there was no significant difference in pain neuroscience education compared to the group that applied only general physical therapy and myofascial release techniques in both lumbar pressure pain thresholds, Schober test, Korean Roland-Morris disability questionnaire, and Korean Oswestry disability questionnaire. However, the Korean Depression Screening Assessment which is the result of measuring depression, showed significant results(p<0.05). Conclusion: Therefore, it is believed that it can be a way to mediate the psychological part through pain neuroscience education for patients with chronic low back pain in the future.

• Structural Engineering and Mechanics
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• 제91권2호
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• pp.211-225
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• 2024

Soft bending actuators have gained significant interest in robotic applications due to their compliance and lightweight nature. Their compliance allows for safer and more natural interactions with humans or other objects, reducing the risk of injury or damage. However, the nonlinear behaviour of soft actuators presents challenges in accurately predicting their bending motion and force exertion. In this research, a new comprehensive study has been conducted by employing a developed 3D finite element model (FEM) to investigate the effect of geometrical and material parameters on the bending behaviour of a soft pneumatic actuator reinforced with Kevlar fibres. A series of experiments are designed to validate the FE model, and the FE model investigates the improvement of actuator performance. The material used for fabricating the actuator is RTV-2 silicone rubber. In this study, the Cauchy stress was expanded for hyperelastic models and the best model to express the stress-strain behaviour based on ASTM D412 Type C tensile test for this material has been obtained. The results show that the greatest bending angle was achieved for the semi-elliptical actuator made of RTV2 material with a pitch of 1.5 mm and second layer thickness of 1 mm. In comparison, the maximum response force was obtained for the semi-elliptical actuator made of RTV2 material with a pitch of 6 mm and a second layer thickness of 2 mm. Additionally, this research opens up new possibilities for development of safer and more efficient robotic systems that can interact seamlessly with humans and their environment.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2584-2594
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• 2024

A novel approach to incorporating oxide formers into ferritic ODS production has been developed using the co-precipitation technique. This method enables the tailored design of complex nano-oxides, integrated during Mechanical Alloying (MA) and precipitated during Spark Plasma Sintering (SPS) consolidation. Findings illustrate that co-precipitation effectively produces nano-powders with customised compositions, enriching Y, Ti, and Zr in the ferritic grade to condition subsequent oxide precipitation. While the addition of Y-Ti-Zr-O nano-oxides did not prevent the formation of Y-Al-O and Al-containing nano-oxides, these were refined thanks to the presence of well-dispersed Zr. Additionally, the Spark Plasma Sintering (SPS) parameters were optimised to tailor the bimodal grain size distribution of the ODS steels, aiming for favourable strength-to-ductility ratios. Comprehensive microstructural analyses were performed using SEM, EDS, EBSD, and TEM techniques, alongside mechanical assessments involving microtensile tests conducted at room temperature and small punch tests carried out at room temperature, 300 ℃, and 500 ℃. The outcomes yielded promising findings, showcasing similar or better performance with conventionally manufactured ODS steels. This reinforces the effectiveness and success of this innovative approach.

• Steel and Composite Structures
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• 제52권3호
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• pp.377-390
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• 2024

Analyzing thermoelastic, elastoplastic, and residual stresses is pivotal for deepening our insights into material characteristics, particularly in the engineering of advanced materials like functionally graded materials (FGM). This research delves into these stress types within a thick-walled sphere composed of Al-SiC FGM, employing a detailed successive approximation method (SAM) to pinpoint stress distributions under varied loading scenarios. Our investigation centers on how the sphere's structure responds to different magnitudes of internal pressure. We discover that under various states-thermoelastic, elastoplastic, and residual-the radial stresses are adversely impacted, manifesting negative values due to the compressive nature induced by internal pressures. Notably, the occurrence of reverse yielding, observed at pressures above 410 MPa, merits attention due to its significant implications on the sphere's structural integrity and operational efficacy. Employing the SAM allows us to methodically explore the nuanced shifts in material properties across the sphere's thickness. This study not only highlights the critical behaviors of Al-SiC FGM spheres under stress but also emphasizes the need to consider reverse yielding phenomena to maintain safety and reliability in their application. We advocate for ongoing refinement of analytical techniques to further our understanding of stress behaviors in various FGM configurations, which could drive the optimized design and practical application of these innovative materials in diverse engineering fields.

• 유통과학연구
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• 제14권2호
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• pp.113-121
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• 2016

Purpose - The purpose of this study is to identify team commitment affecting employees' innovative activities and factors affecting team commitment including empowerment by leaders and job enrichment factors. In other words, so as to explain outcome variables of innovative activities, this study aims to emphasize employees' attachment roles towards their groups within nomological network, and identify the motives encouraging employees' innovative activities. The research purpose is significant due to the realistic situation of hotel industry. The reason why innovative activities are important can be found in recent changes of business environment. Also, unlike other various studies on precedence factors encouraging employees' innovative activities, this study classified those precedence factors into job and leader characteristics, and it emphasized the importance of team commitment as the process that job and leader characteristics are connected to innovative activities. Research design, data and methodology - The survey for this study was conducted during October 6^th ~ November 10^th in 2014 to the employees who are working in 5-star hotels in Korea. As for the selection of hotels and sampling method, convenience sampling method was used to the employees in 5-star hotels. Self-report method was used in the survey, judging that the employees' characteristics would be relatively homogeneous. 311 questionnaires were distributed in total, and 275 reponses were collected. After excluding the missing and unreliable responses, 245 questionnaires were used in the research. SPSS and AMOS programs were used for the analysis. Results - First, empowering leadership had positive effects on hotel employees' team commitment. It indicates that hotel employees are more committed to their team when their leaders set examples, provide information, and involve employees in decision-making process. Second, as a result of the relationship analysis in task diversity, task significance, task identity and team commitment, task diversity and task significance had significant effect on team commitment, while task identity had no significant effect on team commitment. It indicates that team commitment is enhanced when the employees can conduct diverse types of jobs and get more opportunities to talk with the guests. Also, the repetition for the same jobs in hotel rooms and the space for preparing food and beverage do not lead to team commitment, even though the employees fulfill their duties to the end. Third, hotel employees' team commitment has positive effect on their innovative activities. It indicates that employees voluntarily conduct innovative activities when they are attached to their team and identifies themselves with the team. Conclusions - There are theoretical and practical implications in this study. First, in terms of the theoretical perspective, this study proposes structural framework in team commitment, and it identifies the psychological mechanism in team commitment from the aspect of social exchange, which resulted in identification of precedence factors related to team commitment. In addition, this study presents new possibilities for relevant studies about team commitment by examining the effect on team commitment when the importance of innovative activities is emphasized in recent business environment.

• 콘크리트학회논문집
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• 제15권5호
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• pp.670-678
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• 2003

최근 폐기물 재활용에 대한 관심이 지대해 지기 시작하면서 많은 연구가 진행 중에 있다. 그 중 석탄회의 재활용 연구로는 시멘트 대체제로 및 고온소성법을 이용한 인공골재 개발등의 연구가 진행되었으나, 경제성에 있어서 부적합하였다. 본 연구에서는 비소성 고형화 기술을 사용하여 석탄회를 재활용한 건설재료의 토목, 건축 구조분야에 실용화하기 위한 기초자료를 제시하고자 한다. 재령에 따른 압축강도의 회귀분석을 하였고, 압축강도와 할선탄성계수를 구하였다. 그리고 Lineweaver와 Burk 방법을 적용하여 건조수축의 회귀분석을 실시하여 제안식을 도출하였다. 연구결과, 석탄회 경화체의 압축강도는 구조용 부재로 사용가능 한 수준이었으며 건조수축은 중용열 시멘트 모르터와 유사하였다. 또한, Bottom ash의 첨가가 석탄회 경화체 내부에서 골재의 역할을 수행하는 것으로 나타났다. 건조수축 양상을 중량감소율 측정결과와 종합하면 Bottom ash 치환율과 공시체 내부의 수분감소가 건조수축의 지배적인 요인임을 파악할 수 있었다. 또한 압축강도로부터 탄성계수를 추정하는 제안식은 본 연구에서의 압축강도 범위에서는 매우 높은 신뢰도를 보였다. 또한 Lineweaver와 Burk 방법으로 도출한 건조수축 추정 제안식도 매우 높은 신뢰도를 보였다.

• 산경연구논집
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• 제10권3호
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• pp.73-83
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• 2019

Purpose - This study is to clarify the structural relationship between the direct supervisor and organizational commitment and organizational citizenship behavior through mediation of the Leader-member exchange (LMX) in the hospital organization, and to confirm the mediating effect of the LMX. Through this study, we will provide basic data on the aspects of HR to enhance organizational immersion and organizational civic behavior in hospital organizations, and present suggestions on academic contribution and effective organizational operation measures. Research design, data, and methodology - This study is to investigate the relationship between authentic leadership and OC and OCB of the organization member, which is proposed to secure more active and high competitiveness in the recent changing medical environment, with multi-regression and B&K(1986) method. For this purpose, 653 employees of senior hospitals in Seoul and Kyeong-In area were surveyed using structured questionnaires. Each questionnaire was composed of 7-point scale, and each hypothesis was testified by multiple leaner regression and by BK method for testifying mediator effect. Result - As a result of the analysis, it was found that the male and non-medical staff had higher recognition level than the medical staff in the LMX, organizational commitment and organizational citizenship behavior. In the senior management or more than 5 years' experience group, organizational commitment and organizational citizenship behavior were recognized higher than the group of subordinate managers. Second, authentic leadership has a positive influence on LMX, organizational commitment and organizational citizenship behavior, and LMX has a significant positive impact on organizational commitment and organizational citizenship behavior. In addition, as a result of analyzing LMX mediating effect in the relationship of authentic leadership and organizational effectiveness by BK method, LMX had partial mediating effects between authentic leadership and organizational citizenship behavior, and between authentic leadership and organizational commitment. Conclusion - Results of the study confirmed that all the members of the hospital organization that were lacking served as positive factors for the relationships of authentic leadership and LMX, and authentic leadership and organizational effectiveness. It is expected that the hospital organization will be able to suggest such as the organizational approach to expect high organizational effectiveness centering on authentic leadership ability as psychological capital.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1995년도 특별강연 및 추계학술발표 개요집
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• pp.3-20
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• 1995

Development of Real-Time Quality Evaluation of Friction Welding by Acousitc Emission : Report 1 ABSTRACT : According as the friction welding has been increasingly applied in manufacturing various machine components because of its significant economic and technical advantages, one of the important concerns is the reliable quality monitoring method for a good weld quality with both joint strength and toughness in the process of its production. However no reliable nondestructive test method is available at present to determine the weld quality particularly in process of production. So this paper presents an experimental examination and quantitative analysis for the real-time evaluation of friction weld quality by acoustic emission, as a new approach which attempts finally to develop an on-line quality monitoring system design for friction welds using AE techniques. As one of the important results, it was confirmed, through this study, that AE techniques can be reliably applied to evaluating the friction weld qualify with 100% joint strength, as the cumulative AE counts occurring during welding period were quantitatively correlated with reliability at 95% confidence level to the joint strength of welds. Real-Time Evaluation of Automatic Production Quality Control for Friction Welding Machine : Report 2 Abstract : Both in-process quality control and high reliability of the weld is one of the major concerns in applying friction welding to the economical and qualified mass-production. No reliable nondestructive monitoring method is available at present to determine the real-time evaluation of automatic production quality control for friction welding machine. This paper, so that, presents the experimental examinations and statistical quantitative analysis of the correlation between the initial cumulative counts of acoustic emission(AE) occurring during plastic deformation period of the welding and the tensile strength of the welded joints as well as the various welding variables, as a new approach which attempts finally to develop an on-line (or real-time) quality monitoring system and a program for the process of real-time friction welding quality evaluation by initial AE cumulative counts. As one of the important results, it was well confirmed that the initial AE cumulative counts were quantitatively and cubically correlated with reliability of 95% confidence level to the joint strength of the welds, bar-to-bar (SCM4 to SUM31, SCM4 to SUM24L) and that an AE technique using initial AE counts can be reliably applied to real-time strength evaluation of the welded joints, and that such a program of the system was well developed resulting in practical possibility of real-time quality control more than 100% joint efficiency showing good weld with no micro-structural defects.

• 한국도로학회논문집
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• 제17권3호
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• pp.49-58
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• 2015

PURPOSES : The use of environmentally friendly construction methods has been recently encouraged to reduce fuel consumption and the effects of global warming. For this purpose, the roller compacted concrete pavement (RCCP) construction method has been developed. RCCP is more environmentally friendly and economically efficient than general concrete by reducing the amount of CO2 generated through the application of a smaller amount of cement. RCCP has a number of advantages such as an easy construction method, low cost, high structural hydration performance, and aggregate interlocking. However, mix design standards and construction guidelines of RCCP are required for domestic application. In addition, a study on aggregate selection, which has an effect on the characteristics of RCCP, is necessary owing to a limited number of researches. Thus, the aggregate effect on the performance of RCCP in securing the required strength and workability was evaluated in consideration of domestic construction. METHODS : Sand and coarse aggregates of both 19mm and 13mm in maximum size were used in this study. Four types of aggregate gradations (s/a = 30%, 58%, and 70% for the sand and coarse aggregate of 19mm in maximum size, and s/a = 50% for a combination of the three types of aggregates) were set up to investigate the effects of the PCA band on the RCC characteristics. The conditions of s/a = 30% and 70% were evaluated to check the gradation effect outside of the recommended band. The conditions of s/a = 58% and 50% were used because they are the optimum combination of the two and three types of aggregates, respectively. RCCP gradation band was suggested gradation with a proper construction method of RCCP by synthetically comparing and analyzing the correlation of optimum water content, maximum dry density, and strength of requirements through its consistency and compaction test. RESULTS : The lower and upper limit lines are insufficient to secure a relatively strong development and workability compared to an aggregate gradation in the RCCP gradation band region. On the other hand, the line in the RCCP gradation band and the 0.45 power curve in the RCCP gradation band region were satisfactory, ensuring the required strength and workability. CONCLUSIONS : The suitable aggregate gradation on RCCP process should meet the RCCP gradation band area; however, fine particles passing through a #60 sieve do not need to be within the recommended gradation band because the influence of this region on such fine particles is small.

• 콘크리트학회논문집
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• 제29권1호
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• pp.23-32
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• 2017

대심도 복층터널 구조물에서 중간슬래브 구조에 적용되는 형식중 하나인 프리캐스트 구조에서는 차량 진행 방향으로 이음이 발생한다. 따라서, 이 이음부를 일체로 거동하게 하는 것이 중요하다. 이 연구에서 제안하는 대심도 복층터널 중간슬래브는 터널의 공간 활용을 극대화 하기 위하여 프리스트레스를 도입한 보 형식의 구조체로, 'PS 이음방식'과 '볼트체결방식'에 대한 이음방법을 개발하였다. 또한, 두 가지 이음방식을 적용한 중간슬래브의 구조성능을 평가하기 위해서 실물모형 구조실험을 수행하였으며, Contact 모델을 적용한 FEM 해석을 통해서 구조적인 안정성을 검증하였다. 이음방식을 적용한 복층터널 중간슬래브의 정적재하실험 결과 매우 안정적인 거동을 보였으며, 균열 및 처짐에 있어 도로교설계기준(2011)을 만족하여 사용성에도 문제가 없다고 판단되었다. FEM 해석에 따른 중간슬래브의 거동은 실험과 비교하여 강성이 미소하게 크게 나타났으나 전체적인 거동이 거의 유사하게 나타났다. 따라서 이 연구에서 개발한 이음방법을 적용한 중간슬래브를 시공함에 있어 구조적으로 문제가 없을 것으로 판단된다.