• Smart Structures and Systems
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• 제23권5호
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• pp.449-466
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• 2019

Cable-stayed bridges are attractive due to their beauty, reducing material consumption, less harm to the environment and so on, in comparison with other kinds of bridges. As a massive structure with long period and low damping (0.3 to 2%) under many dynamic loads, these bridges are susceptible to fatigue, serviceability disorder, damage or even collapse. Tuned Mass Damper (TMD) is a suitable controlling system to reduce the vibrations and prevent the threats in such bridges. In this paper, Multi Tuned Mass Damper (MTMD) system is added to the Ahvaz cable stayed Bridge in Iran, to reduce its seismic vibrations. First, the bridge is modeled in SAP2000 followed with result verification. Dead and live loads and the moving loads have been assigned to the bridge. Then the finite element model is developed in OpenSees, with the goal of running a nonlinear time-history analysis. Three far-field and three near-field earthquake records are imposed to the model after scaling to the PGA of 0.25 g, 0.4 g, 0.55 g and 0.7 g. Two MTMD systems, passive and active, with the number of TMDs from 1 to 8, are placed in specific points of the main span of bridge, adding a total mass ratio of 1 to 10% to the bridge. The parameters of the TMDs are optimized using Genetic Algorithm (GA). Also, the optimum force for active control is achieved by Fuzzy Logic Control (FLC). The results showed that the maximum displacement of the center of the bridge main span reduced 33% and 48% respectively by adding passive and active MTMD systems. The RMS of displacement reduced 37% and 47%, the velocity 36% and 42% and also the base shear in pylons, 27% and 47%, respectively by adding passive and active systems, in the best cases.

• Integrative Medicine Research
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• 제3권2호
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• pp.60-66
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• 2014

Background: Medically unexplained symptoms (MUSs) are common in primary care. Atpresent, there are no proven, comprehensive treatments available in primary care forpatients with MUSs. However, MUS has parallels with "subhealth" or Mibyeong from tradi-tional East-Asian medicine, and thus, Mibyeong interventions could be effective in treatingMUS. Unfortunately, studies on Mibyeong and its intervention methods are relatively rare.Methods: We administered a web-based survey to 17,279 Korean medicine (KM) practitionersregistered with the Association of Korean Medicine. The response rate was 4.9% (n = 849).Based on the responses received, we assessed how much they agreed with concepts relatedto Mibyeong on a 7-point scale from "do not agree" to "strongly agree." Respondents werealso asked to indicate how frequently they encountered various subtypes and patterns ofMibyeong, and how frequently they use listed intervention methods.Results: Data from 818 respondents were analyzed after excluding those with no clinicalexperience. On average, respondents were male general practitioners aged between 30 yearsand 49 years, working or living in metropolitan areas such as Seoul, Incheon, and Gyeonggi-do. Responses did not differ by demographics. Respondents generally thought that Mibyeongreferred to subjective or borderline findings without certain disease, and that Mibyeong hasvarious subtypes and patterns. Subtypes included fatigue, pain, and digestion problems; pat-terns were either deficiencies (e.g., qi, blood, and yin deficiency) or stagnations (e.g., liver qidepression and qi stagnation). Decoction was the most frequently used type of interventionfor Mibyeong of all items listed, followed by acupuncture and moxibustion. Patient educa-tion was also recommended, suggesting healthy eating, promoting healthy environment,and exercise.Conclusion: We were able to provide preliminary results on KM practitioners' recognition ofand interventions for Mibyeong, but further research is needed to develop a detailed defi-nition of Mibyeong and its myriad subtypes and patterns, and evaluations of the efficacy ofMibyeong interventions.

• 산업융합연구
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• 제19권6호
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• pp.37-47
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• 2021

오늘날 이메일(E-mail), 스마트폰, SNS 등의 다양한 정보통신 매체는 정보공유 및 의사소통을 위한 필수품이다. 하지만 불법으로 수집한 개인정보와 보안에 취약한 기기를 활용하여 대량으로 불법 스팸을 보내거나, 사기에 이용하기 위한 악의적인 공격에 이용되고 있다. 불법스팸과 스미싱, 사기 메일(SCAM) 등은 기업과 사용자들에게 정신적 피로감 등의 사회적 비용뿐만 아니라 IT인프라 자원의 불필요한 소모와 경제적 손실 등 직간접적으로 많은 피해를 주고 있다. 스팸 관련 법제도가 마련되어 있지만 교묘히 회피하여 여전히 기승을 부리고 있고 피해자가 지속적으로 발생하고 있어 문제점이 없는지 검토가 필요하다. 불법스팸을 차단하고 이로 인한 사기 피해를 예방하기 위해 관련 제도를 개선하는데 기여하는 학술적 연구가 필요한 상황이다. 본 연구는 국내외 법제도와 스팸 관련 대응 활동과 문제점을 도출하고 정책적 개선 방안을 제안하였다.

• 문화기술의 융합
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• 제8권3호
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• pp.265-270
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• 2022

본 연구는 콘크리트 궤도용 탄성레일체결장치(System 300-1)의 손상취약부에 관한 실험 및 해석적 연구이다. 콘크리트 궤도에서 탄성레일체결장치는 열차주행 시 레일과 침목을 결속하는 핵심 궤도구성품이다. 레일체결장치 구성품 중 방진패드와 텐션 클램프(Tension Clamp)는 압축력과 부상력에 대응하며 상시 변형이 발생되는 피로부재이다. 본 연구에서는 동일구간의 운행선에서 6년, 11년, 16년 동안 사용된 탄성레일체결장치를 채취하여 사용년수에 따른 텐션 클램프의 잔류변형 특성을 분석하였다. 또한 수치해석을 바탕으로 주요 구성품별 거동메커니즘을 분석하고 손상취약부를 도출하였다. 본 연구에서 수행한 수치해석을 통해 체결력 도입부터 외력 작용에 따른 텐션 클램프 각부의 응력(변형율)을 분석하여 텐션 클램프의 손상취약부를 도출하였다.

• Korean Journal of Acupuncture
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• 제40권2호
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• pp.44-53
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• 2023

Objectives : This study was conducted to reveal the relationship between multiple factors of traditional Korean Medicine diagnosis and consider the further probabilities of treating people with physical and mental problems not defined as diseases, which is called 'Mibyeong' in traditional Korean Medicine. Methods : 40 healthy participants were included in the observational clinical trial. The participants were asked to complete health questionnaires (e.g. State-Trait Anxiety Inventory, Pittsburgh Sleep Quality Index, Stress Response Inventory) and they went through a traditional diagnosis process, including four stages of diagnosis (looking, listening/smelling, inquiring, and pulse taking), by a Korean Medicine doctor. Both the Korean Medicine doctor and an artery tonometry device performed the pulse diagnosis. Results : Although all participants were healthy people with no history of disease, more than half of participants had a problem related with severe level of fatigue (n=19), sleep disturbance (n=26) and stress (n=27) status according to the related questionnaires. Participants diagnosed with phlegm syndrome by the Korean Medicine doctor showed significantly greater score in phlegm pattern questionnaires than participants who were not. However, there was little agreement between the doctor's pulse diagnosis and radial artery tonometry results. Conclusions : We conducted a pulse diagnosis and measured health-related information along with the traditional Korean Medicine diagnose procedure, including four stages of diagnosis, and we found a linkage between diagnosis of phlegm and the phlegm pattern questionnaire score. The results suggest that a number of healthy participants, with no disease diagnosed, have Mibyoung symptoms which need further clinical management. Thus, we suggest that Mibyoung management programs based on qualified diagnosis tools and traditional Korean medicine diagnosis procedures be developed, and that future research using various diagnostic tools be carried out on a large population.

• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.214-225
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• 2023

Piezoelectric actuators, which utilize piezoelectric crystals or ceramics, are commonly used in precision positioning applications, offering high-speed response and precise control. However, the use of low-performance ceramics and expensive single crystals is limiting their versatile use in the actuator market, necessitating the development of both high-performance and cost-effective piezoelectric materials capable of delivering higher forces and displacements. The use of textured Pb (lead)-based piezoelectric ceramics formed by so-called templated grain growth method has been identified as a promising strategy to address the performance and cost issue. This review article provides insights into recent advances in texturing Pb-based piezoelectric ceramics for improved performance in actuation applications. We discussed the relevant issues in detail focusing on current challenges and emerging trends in the textured piezoelectric ceramics for their reliability and performance in actuator applications. We discussed in detail focusing on current challenges and emerging trends of textured piezoelectric ceramics for their reliability and performance in actuator applications. In conclusion, the article provides an outlook on the future direction of textured piezoelectric ceramics in actuator applications, highlighting the potential for further success in this field.

• 대한토목학회논문집
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• 제28권1D호
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• pp.45-55
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• 2008

아스팔트 혼합물의 거동을 정확하게 예측하기 위하여 점탄소성 연속체 손상모형(이하 점탄소성 모형)을 개발하였다. 본 논문에서는 인장조건에서 점탄소성 모형의 개발과 4가지 혼합물(일반 밀입도, SBS, CR-TB, Terpolymer)을 이용한 모형의 검증과정을 다루고 있다. 모형 개발을 위해서 실내시험으로 측정한 아스팔트 혼합물의 전체 응답을 점탄성과 점소성 성분으로 구분하여 분석하였다. 점탄성 연속체 손상모형으로는 미세균열이 지배적인 상태에서 아스팔트 혼합물의 시간 의존적 거동을 해석하고, 고온 혹은 저속 하중 조건에서 발생한 영구변형(시간 종속과 비종속 성분을 모두 포함)은 점소성 모형으로 해석하였다. 변형률 분해 원리에 근거하여 각각의 모형을 통합하여 점탄소성 연속체 손상모형(VEPCD)을 개발하였다. 모형의 변수 결정을 위해서 직접인장시험을 수행하고 각각의 혼합물에 대한 선형 점탄성은 동탄성계수와 시간-온도 전이계수 그리고 위상각의 주곡선으로 정의하였다. 개발된 점탄소성 모형의 예측 성능을 평가하기 위하여 두 종류의 실내시험 실시하고 그 결과를 분석하였다 : 1) 단일 변형률 인장 시험, 2) 임의 하중조건을 모사한 피로 시험.

• 대한토목학회논문집
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• 제28권3D호
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• pp.399-405
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• 2008

포장궤도는 기존선의 유지보수 노력을 절감하기 위하여 개발되고 있다. 이 중 베이스플레이트 저탄성패드는 궤도 전체의 지지강성을 결정하는 구성품으로서 궤도의 응력-변위특성, 동적응답, 피로특성 등에 가장 큰 영향을 미친다. 따라서 저탄성패드의 적용은 궤도전체의 내구성과 안정성에 미치는 영향이 크다고 할 수 있다. 본 논문에서는 저탄성패드의 적용으로 인하여 획득되는 효과 중 노반에 전달되는 열차하중의 저감에 대한 연구를 수행하였다. 이를 위하여 패드스프링계수별 정적해석과 실물반복재하시험을 수행하고 그 결과를 비교 분석하여 저탄성패드의 하중 전달특성을 파악하였으며 전달하중 저감효과를 검토하였다.

• 대한통합의학회지
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• 제11권4호
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• pp.189-198
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• 2023

Purpose: This study aims to investigate the preferences of hot spring users regarding the utilization of Asan's hot springs after the COVID-19 pandemic. Methods: A survey was conducted on 340 hot spring users visiting hot spring resorts in the Onyang, Dogo, and Asan hot spring districts. The survey was conducted twice from November 5th to November 7th, 2021, and from May 25th to 26th, 2022. The survey included general questions, such as the frequency of hot spring usage, the purpose of visits, and the intention for future visits. Specific questions were related to Asan hot springs, focusing on the reasons for choosing Asan, its perceived advantages, and improvement suggestions. Results: The survey revealed that the average number of visits to hot springs was less than five in the past five years, and the main reason for visiting was to recover from fatigue. A percentage of respondents said they would use hot springs more often when the COVID-19 pandemic ends. When asked about their reasons for visiting Asan hot springs, responses varied by age. However, across all groups, the majority considered "good water" as an advantage of Asan hot springs, while improvements to "hot spring facilities" was the highest response among all age groups. Thus, despite the decline in the number of customers due to COVID-19, the overall perception of hot springs remains positive. This suggests a promising future for the hot spring industry, with the potential for a return to pre-pandemic usage levels. Conclusion: These results provide valuable foundational data for informing policy development aimed at revitalizing the hot spring industry in the post-COVID-19 era.

• Structural Engineering and Mechanics
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• 제90권1호
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• pp.27-40
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• 2024

The prediction of VIV amplitude is essential for the design and fatigue life estimation of steel tubes in tubular transmission towers. Limited to costly and time-consuming traditional experimental and computational fluid dynamics (CFD) methods, a machine learning (ML)-based method is proposed to efficiently predict the VIV amplitude of steel tubes in transmission towers. Firstly, by introducing the first-order mode shape to the two-dimensional CFD method, a simplified response analysis method (SRAM) is presented to calculate the VIV amplitude of steel tubes in transmission towers, which enables to build a dataset for training ML models. Then, by taking mass ratio M^*, damping ratio ξ, and reduced velocity U^* as the input variables, a Kriging-based prediction method (KPM) is further proposed to estimate the VIV amplitude of steel tubes in transmission towers by combining the SRAM with the Kriging-based ML model. Finally, the feasibility and effectiveness of the proposed methods are demonstrated by using three full-scale steel tubes with C-shaped, Cross-shaped, and Flange-plate joints, respectively. The results show that the SRAM can reasonably calculate the VIV amplitude, in which the relative errors of VIV maximum amplitude in three examples are less than 6%. Meanwhile, the KPM can well predict the VIV amplitude of steel tubes in transmission towers within the studied range of M^*, ξ and U^*. Particularly, the KPM presents an excellent capability in estimating the VIV maximum amplitude by using the reduced damping parameter S_G.