• 제목/요약/키워드: taut

검색결과 72건 처리시간 0.02초

동수력학 해석 기반 부유식 해양 플랫폼의 동적 운동 및 계류력 산정 (Estimation of Dynamic Motions and Mooring Forces for Floating Type Offshore Platform Based on Hydrodynamic Analysis)

  • 차주환;문창일;송창용
    • 한국해양공학회지
    • /
    • 제26권2호
    • /
    • pp.48-57
    • /
    • 2012
  • This paper deals with numerical analyses in the context of estimations of hydrodynamic motions and dynamic loads for a floating type offshore platform using some exclusive simulation code such as code for the simulation of a floating type of offshore crane based on multi-body dynamics, along with the commercial code AQWA. Verifications of numerical models are carried out by comparing the RAO results from the simulation code. In the verification analyses, hydrodynamic motions are examined in the frequency domain for the floating type offshore platform according to the mooring lines. Both the hydrodynamic motions and dynamic loads are estimated for floating type offshore platforms equipped with the catenary type and taut mooring lines. A review and comparison are carried out for the numerically estimated results. The structural safety of the connection parts in an offshore structure such as a floating type offshore platform is one of the most important design criteria in view of fatigue life. The dynamic loads in the connecting area between a floating type offshore platform and its mooring lines are estimated in detail according to variations in the mechanical properties of the mooring lines. The dynamic tension load on the mooring lines is also estimated.

Is Extracorporeal Shock Wave Therapy Effective in the Treatment of Myofascial Pain Syndrome?

  • Kim, Jong-Ick;Lee, Hyo-Jin;Park, Hyung-Youl;Lee, Won-Hee;Kim, Yang-Soo
    • Clinics in Shoulder and Elbow
    • /
    • 제19권1호
    • /
    • pp.20-24
    • /
    • 2016
  • Background: Extracorporeal shock wave therapy (ESWT) is one of the treatment options used for patients with myofascial pain syndrome (MPS), although its effectiveness is controversial. The purpose of this study was to evaluate the effectiveness of ESWT in the treatment of MPS in terms of pain relief and functional improvements. Methods: We assessed 93 patients with MPS who underwent ESWT from March 2009 to July 2014. After exclusion of 25 patients with shoulder diseases, 68 patients were enrolled in the study. The mean follow-up period was 7.5 months (${\pm}4.2weeks$), and the average duration of symptoms was 5 months (range, 2-16 months). ESWT was applied to intramuscular taut bands and referred pain areas once a week for 3 weeks. Visual analog scale (VAS) pain scores and American Shoulder and Elbow Surgeons (ASES) scores were obtained at an initial assessment and at the 6-week, 3-month, and 6-month follow-up assessments. Results: VAS pain scores and ASES scores improved significantly after 3 sessions of ESWT (p<0.05). Both scores were improved, although not significantly, after 6 weeks (p>0.05). Conclusions: ESWT is an effective treatment option for patients with MPS.

A Study on the Dynamic Analysis of Mooring System During Hook-up Installation

  • Lee, Min Jun;Jo, Hyo Jae;Lee, Sung Wook;Hwang, Jea Hyuk;Kim, Jea Heui;Kim, Young Kyu;Baek, Dong Il
    • 한국해양공학회지
    • /
    • 제34권5호
    • /
    • pp.285-293
    • /
    • 2020
  • This study evaluated the Hook-up installation of an offshore site construction process, which is the final step in an offshore site installation process. During Hook-up installation, the offshore structure can have a detrimental effect on the work stability due to low-frequency motion. Moreover, economic costs can be incurred by the increase in available days of a tugboat. Therefore, this study developed a numerical analysis program to assess the dynamic behavior of mooring systems during hook-up installation to analyze the generally performed installation process and determine when the tugboat should be released. In this program, the behavior of an offshore structure was calculated using Cummin's time-domain motion equation, and the mooring system was calculated by Lumped mass method (LMM). In addition, a tugboat algorithm for hook-up installation was developed to apply the Hook-up procedure. The model used in the calculations was the barge type assuming FPSO (Floating production storage and off-loading) and has a taut mooring system connected to 16 mooring lines. The results of the simulation were verified by comparing with both MOSES, which is a commercial program, and a calculation method for restoring coefficient matrix, which was introduced by Patel and Lynch (1982). Finally, the offset of the structure according to the number of tugboats was calculated using the hook-up simulation, and the significant value was used to represent the calculation result.

Vibration control of a stay cable with a rotary electromagnetic inertial mass damper

  • Wang, Zhi Hao;Xu, Yan Wei;Gao, Hui;Chen, Zheng Qing;Xu, Kai;Zhao, Shun Bo
    • Smart Structures and Systems
    • /
    • 제23권6호
    • /
    • pp.627-639
    • /
    • 2019
  • Passive control may not provide enough damping for a stay cable since the control devices are often restricted to a low location level. In order to enhance control performance of conventional passive dampers, a new type of damper integrated with a rotary electromagnetic damper providing variable damping force and a flywheel serving as an inertial mass, called the rotary electromagnetic inertial mass damper (REIMD), is presented for suppressing the cable vibrations in this paper. The mechanical model of the REIMD is theoretically derived according to generation mechanisms of the damping force and the inertial force, and further validated by performance tests. General dynamic characteristics of an idealized taut cable with a REIMD installed close to the cable end are theoretically investigated, and parametric analysis are then conducted to investigate the effects of inertial mass and damping coefficient on vibration control performance. Finally, vibration control tests on a scaled cable model with a REIMD are performed to further verify mitigation performance through the first two modal additional damping ratios of the cable. Both the theoretical and experimental results show that control performance of the cable with the REIMD are much better than those of conventional passive viscous dampers, which mainly attributes to the increment of the damper displacement due to the inertial mass induced negative stiffness effects of the REIMD. Moreover, it is concluded that both inertial mass and damping coefficient of an optimum REIMD will decrease with the increase of the mode order of the cable, and oversize inertial mass may lead to negative effect on the control performance.

Sag가 고려된 사장교 케이블의 진동저감을 위한 Movable Anchorage 시스템 (Movable Anchorage System for Mitigation of Cable Vibration in Cable-Stayed Bridges with Sag)

  • 황인호;박준형;이종세
    • 대한토목학회논문집
    • /
    • 제28권5A호
    • /
    • pp.657-664
    • /
    • 2008
  • 사장교 케이블은 구조적으로 휨강성과 감쇠력이 작아 풍우에 의해 쉽게 유해진동이 발생한다. 이러한 풍우진동을 저감시키기 위한 효과적인 방법으로 부가댐퍼를 장착하여 케이블의 감쇠력을 증가시키는 제어시스템이 널리 사용되어왔다. 그러나 사장교의 장대화로 인해 구조적으로나 미적으로 충분한 감쇠력을 제공할 수 있는 위치에 부가댐퍼를 장착하기 어렵게 되었다. 최근 본 저자는 사장교의 미관을 해치지 않으면서 기존의 제어시스템보다 효과적으로 케이블의 진동을 저감시킬 수 있는 새로운 개념의 사장교 케이블 진동 제어시스템을 제안하였다. 본 논문에서는 기존의 연구를 확장하여 새그(Sag)를 고려한 Movable anchorage 시스템을 제안하였으며, 수치해석을 통한 제어성능을 평가하였다. 수치해석의 결과 제안된 시스템은 새그를 고려하였을 때에도 고려하지 않은 경우와 마찬가지로 베어링장치의 강성이 작을수록 기존의 비감쇠 시스템이나 일반적인 수동제어시스템보다 훨씬 좋은 성능을 나타내었다. 제안된 시스템에 있어서 최적의 제어성능을 제공하기 위해서는 새그의 크기를 고려해서 최적의 감쇠계수를 결정해야 할 것으로 사료된다.

사장교의 케이블 진동저감을 위한 수동 제어시스템 (Passive Control System for Mitigation of Cable Vibration in Cable-Stayed Bridges)

  • 황인호;이종세
    • 대한토목학회논문집
    • /
    • 제26권5A호
    • /
    • pp.881-885
    • /
    • 2006
  • 사장교 케이블은 구조적으로 휨강성과 감쇠력이 작아 풍우에 의해 쉽게 유해진동이 발생한다. 이러한 풍우진동을 저감시키기 위한 효과적인 방법으로 부가댐퍼를 장착하여 케이블의 감쇠력을 증가시키는 제어시스템이 널리 사용되어왔다. 그러나 사장교의 장대화로 인해 구조적으로나 미적으로 충분한 감쇠력을 제공할 수 있는 위치에 부가댐퍼를 장착하기 어렵게 되었다. 그러므로 본 논문은 사장교의 미관을 해치지 않으면서 기존의 제어시스템보다 효과적으로 케이블의 진동을 저감시킬 수 있는 새로운 개념의 제어시스템을 제안하였다. 제안된 시스템은 케이블 앵커리지에 적층고무베어링과 같은 유동이 가능한 장치와 내부댐퍼로 구성되었으며, 제어성능평가를 위해 해석모델을 개발하였다. 제안된 시스템의 제어성능 분석을 위해 수치해석을 수행하였으며 기존의 부가 댐퍼시스템과 진동 저감효과를 비교하였다. 제안된 제어시스템은 기존의 부가댐퍼 시스템 보다 효과적으로 진동을 저감시킬 수 있었으며 사장교 케이블의 풍우진동 저감을 위해 효과적인 시스템으로 사료된다.

Mooring chain fatigue analysis of a deep draft semi-submersible platform in central Gulf of Mexico

  • Jun Zou
    • Ocean Systems Engineering
    • /
    • 제14권2호
    • /
    • pp.171-210
    • /
    • 2024
  • This paper focuses on the rigorous and holistic fatigue analysis of mooring chains for a deep draft semi-submersible platform in the challenging environment of the central Gulf of Mexico (GoM). Known for severe hurricanes and strong loop/eddy currents, this region significantly impacts offshore structures and their mooring systems, necessitating robust designs capable of withstanding extreme wind, wave and current conditions. Wave scatter and current bin diagrams are utilized to assess the probabilistic distribution of waves and currents, crucial for calculating mooring chain fatigue. The study evaluates the effects of Vortex Induced Motion (VIM), Out-of-Plane-Bending (OPB), and In-Plane-Bending (IPB) on mooring fatigue, alongside extreme single events such as 100-year hurricanes and loop/eddy currents including ramp-up and ramp-down phases, to ensure resilient mooring design. A detailed case study of a deep draft semi-submersible platform with 16 semi-taut moorings in 2,500 meters of water depth in the central GoM provides insights into the relative contributions of wave scatter diagram, VIMs from current bin diagram, the combined stresses of OPB/IPB/TT and extreme single events. By comparing these factors, the study aims to enhance understanding and optimize mooring system design for safety, reliability, and cost-effectiveness in offshore operations within the central GoM. The paper addresses a research gap by proposing a holistic approach that integrates findings from various contributions to advance current practices in mooring design. It presents a comprehensive framework for fatigue analysis and design optimization of mooring systems in the central GoM, emphasizing the critical importance of considering environmental conditions, OPB/IPB moments, and extreme single events to ensure the safety and reliability of mooring systems for offshore platforms.

유한차분법을 이용한 저장력 예인케이블의 비선형 동적해석 (Nonlinear Dynamic Analysis on Low-Tension Towed Cable by Finite Difference Method)

  • 박한일;정동호
    • 대한조선학회논문집
    • /
    • 제39권1호
    • /
    • pp.28-37
    • /
    • 2002
  • 본 연구에서는 저장력 예인케이블의 비선형 동적거동을 수치적으로 해석하였다. 고장력 케이블해석에서는 흔히 무시되는 굽힘강성의 효과가 저장력 케이블에서는 중요한 역할을 하므로 본 연구에서는 이를 고려하였다. 또한 저장력 케이블에서는 대변위가 발생하기 쉬우므로 기하학적인 비선형 및 유체 비선형 효과가 크므로 이를 고려하였다. 저장력 예인케이블에 대한 3차원 비선형 운동방정식을 수립하고 유한차분법을 적용하여 이산화 시켰다. 시간적분에 있어서 안정적인 해를 얻을 수 있는 음해법(implicit method)을 적용하였으며 비선형 해를 구하기 위하여 Newton-Raphson 반복법을 사용하였다. 케이블과 같이 양단경계조건을 갖고 대각선 주변 성분만 있는 행렬식을 계산하는 경우에는 Gauss-Jordan 방법 등과 같이 일반적인 방법 보다 블록삼중대각행렬 풀이법이 계산시간을 상당히 줄일 수 있음을 알 수 있었다. 몇 가지 예제해석을 수행하였으며 실해역 실험결과에 의해 이미 검증되어 있는 케이블 해석프로그램인 WHOI Cable 프로그램의 해석결과와 비교 검토한 결과 서로 잘 일치함을 알 수 있었다.

뚜렛 장애(Tourett's disorder) 환자(患者) 1례(例)에 대한 증례보고(症例報告) (A clinical report of a patient with Tourett's disorder)

  • 성우용;이승현;손지형;한승혜;정효창
    • 동의신경정신과학회지
    • /
    • 제14권2호
    • /
    • pp.213-218
    • /
    • 2003
  • 틱의 치료에 있어서 양방적으로는 일과성 틱 장애가 아닌 만성 틱장애, 뚜렛 장애의 경우에는 약물치료가 대개 시행된다. 주로 사용되는 약물은 도파민 수용체 길항제이거나 이에 반응하지 않는 경우 클로니딘, 구안파신 등의 성인의 고혈압 치료에 쓰이는 약물을 쓰기도 하고, 또는 항우울제를 쓰기도 한다고 한다. 본 증례의 환자는 처음 양방정신과 방문 후 상기 처방 등을 투여받았으나 부작용(자꾸 정신이 몽롱해지고, 잠이와서 일상생활이 불가능해지는 문제)으로 한방치료를 원한 경우였다. 처음 내원했을 때의 상태는 불그스름한 얼굴, 심한 현맥, 근긴장 및 계속해서 틱증상을 보이는 양상 등을 보였고 운동틱의 정도가 매우 심하여 간주근(肝主筋)의 원칙에 의하여 간양화풍(肝陽化風)의 기전으로 환자의 상태를 변증할 수 있었기에 억간산(抑肝散)을 투여하기로 하였고 아울러 복진상(腹診上) 좌측제부동계항진(左側臍部動悸亢進)이 보여 간열(肝熱)로 신경(神經)이 흥분하여 위장애(胃障碍)가 나타나서 생기는 위내정수(胃內停水)의 소견을 보였기 때문에 진피(陳皮), 반하(半夏)를 가(加)하여 투여하였다. 아울러 YGTSS를 시행한 바 환자가 내원 초기(2003년 6월 9일) 에 시행한 YGTSS의 점수는 30점이었고, 어느 정도 증상의 호전을 보여 폐약(閉藥)을 원했던 시기(2002년 7월 24일)의 YGTSS에서는 11점으로 증상의 상당한 호전을 보였으며 약을 중지한 이후에도 지속적으로 증상의 호전이 되었다 하면서 다시 내원한 2003년 9월 22일에는 약 20분동안의 상담시간동안 거의 틱증상의 발현을 볼 수 없었다. 2003년 10월 20일 마지막으로 시행한 YGTSS의 점수는 3점으로 거의 완치에 가까운 결과를 보여주고 있다. 이는 억간산(抑肝散) 가(加) 진피(陳皮) 반하(半夏)의 처방을 투여함으로서 환자의 간열(肝熱)을 지속적으로 내려주었고, 아울러 상담을 통하여 원만한 가족관계를 유지할 수 있도록 도와주어 환자에게 자꾸 간기(肝氣)의 항진(亢進)을 야기시키는 원인인 가정불화를 어느정도 완화시켜 주었기 때문이라고 사료된다. 지금까지 만성 틱장애나 뚜렛 장애에 대하여는 양 한방적으로 뚜렷한 효과를 보이는 증례를 많이 발견할 수 없는 현실에서 본 증례는 상기 질환에 대한 한방치료의 가능성을 보여주는 예라고 판단되어 보고하는 바이다.

  • PDF

유영국(劉永國)의 초기 구성주의: <랩소디>(1937)에 나타난 유토피아니즘 (Yoo Young-kuk's Early Constructivism: Utopianism in (1937))

  • 유영아
    • 미술이론과 현장
    • /
    • 제9호
    • /
    • pp.93-121
    • /
    • 2010
  • This study is about Yoo Young-kuk's early works which show constructivism, especially focus on his debut painting, for the 7th Dokuritsu Bijutsu Kyokai(獨立美術協會, the Independent Fine Arts Association) in Tokyo in 1937. The work was painted 2 years after he had started his study in Japan in 1935. It was the first painting that applied Constructivism. played an important role for Constructivism to be a leading art in his abstraction. After this picture, Yoo was soon devoted to the principles of Constructivism-- Faktura(material), Tektonika (tectonics), Tekhnika(technique), space, construction-- in his painterly reliefs. This article examined why Yoo concentrated on Constructivism for , what the characteristics were, and what influences were on other works from 1935 to 1949. In addition, I investigated in which period was painted and how Constructivism was spread in 1930s and early 1940s in chapter 2. I scrutinized Rhapsody in chapter 3. When Yoo created Japan was under the Fifteen Years War(1931-1945), and a major discourse was the Japanese Spirit at that time. It was connected with construction of an ideal nation which the Japanese ultra-national fascism pursued. This ideological pursuit was intended to unite the Japanese people for total war system and to restore a national dignity which had been fallen down due to Manchurian Incident(1931). Thus, on the hand, Kokusai Bunka Shinkokai(國際文化振興, The Society for International Cultural Relations) and the Nippon Kosaku Bunka Renmei(日本工作文化連盟, Japanese Werkbund) were supported financially by the Japanese government. On the other hand, the government enacted regulations to opposing parties which would distract Japanese people's unification. As for the Japanese art world, the merge of art groups was carried out through remodeling of Teikoku Bijutsuin(帝國美術院, The Imperial Fine Arts Academy) in 1935. This brought out continuous dispute and disorder. Young artists who felt difficulty of entering an entry of Imperial Fine Arts Exhibition repeatedly grouped and disbanded for small art groups to build their standing, which they pursued Surrealism and Abstract art. Among them Constructivism was considered as the latest trend and was popular in craft, design, architecture as well as fine arts. In the year before he painted , Avant-garde theatres including Constructivism theatre were introduced in a feature article of September, 1936 in Atelier, which was dealing with mainly avant-garde arts. Books related with Constructivism were translated into Japanese, and Gestaltung Education had become active since the publication of A Compendium of Gestaltung Education("構成敎育大系"(1934)), Salvador Dali(1904-1989) was also introduced, so Surrealism was drawn more attention by young artists. reflected popular trends. Yoo analyzed the Japanese avant-gardists' archaic taste in the Independent Art Association that he submitted his painting to. And then he entitled 'Rhapsody' which derives from Ancient Greek's epic poetry and deliberately set up images in a scene. In chapter 3, I examined a theme which was planned carefully by sorting favorite images from the Japanese Surrealism. was a result that Yoo Young-kuk observed objectively the phenomenon that young artists dreamt of Utopia or longed for Nostalgia passively and lethargically under wars. And then he otherized himself from that circumstance. First of all, for he used the typical icons of Japanese Surrealism such as the horizon, flowing clouds, and vast plain that were considered stereotypes of Arcadia. He, however distinguished himself form those Japanese Surrealists. He made his own vision about Utopia by referring Lyubov Popova(1889-1924)'s stage design. His objective point of view was expressed by positive and dynamic images of structure and human's actions. Constructivism which was attempted in had an effect on other early constructive works, and the principles of Constructivism were sought hard in reliefs, paintings, and photos.

  • PDF