Isolated Dissection of Superior Mesenteric Artery: Study on the Treatment Guidelines

Purpose: Isolated superior mesenteric artery (SMA) dissection is a rare, but increasing vascular disorder. However, optimal treatment guidelines are not well established. The purpose of this study is to review a single institutional experience in the management of isolated SMA dissections and establish optimal treatment guidelines. Methods: Between November 2004 and August 2009, 26 patients were diagnosed with isolated SMA. dissection at Eulji University Hospital. Diagnosis was confirmed with CT scans in all patients. We retrospectively reviewed the medical records, imaging studies, and the early outcomes of the patients. Results: There were 22 (84.5%) men and 4 women. The mean age was 55.4 (39 similar to 74) years. The mean follow-up was 39.1 (4.1 similar to 53.3) months. In 15 patients, CT scans were performed for abdominal pain, and in the other 11 patients, the isolated SMA dissections were detected incidentally during workup for other causes. The radiographic findings included an intimal flap with a patent false lumen in 16 and intramural hematoma in 10. The dissection started at a mean of 22.3 (5 similar to 46) mm from the origin of the SMA with a mean length was 47.7 (1.0 similar to 150) mm. Treatments included expectant management in 13, anticoagulation in 6, stenting in 6 patients, and surgery in one case of bowel infarction. None required additional intervention. All patients remained asymptomatic during follow-up. Conclusion: Most patients with isolated SMA dissection were successfully managed medically. Surgical or percutaneous intervention should be reserved for those with evidence of bowel necrosis or mesenteric ischemia and failed cases to initial medical treatment. 단독성 상장간막동맥 박리는 온라인 의학저널 데이터베이스인 퍼브메드(PubMed)에서 isolated superior mesenteric artery dissection을 중심 단어(keyword)로 검색하면 현재까지 영어 의학저널에서 106예밖에 검색이 안될 정도로 드문 질환이다.(1) 발병원인, 병태생리나 치료 등에 대한 것들이 확실하게 정립되어있지 않다. 지금까지 제시된 치료 지침들은 문헌에 보고된 여러 논문을 검색하여 검토하고 분석 한 결과 수술적응증 유무, 증상, 내막편(intimal flap) 혹은 혈관 협착 유무, 협착의 길이 등에 따라 치료 지침을 제시한 것이었으며 이외에 전산화 단층촬영에 나타난 상장간막동맥 박리의 모양에 따른 치료 지침을 제시하기도 하였다.(2-4) 지금까지 보고된 치료 방법은 특별한 치료가 없는 기대요법(expectant management), 항응고제 투여, 혈관 내 치료 및 수술 등이 있으나 의미 있고 체계적인 치료 지침이 확립되지 않아 동맥의 해부학적 적정성, 환자의 동반질환이나 증상의 정도, 의사의 선호도 등에 따라 제각기 시행되고 있는 실정이다. 저자들은 본원에서 경험한 예를 분석하여 이에 대한 적 절한 치료 지침을 제시하고자 본 연구를 시행하였다.Gobble RM, 2009, J VASC SURG, V50, P1326, DOI 10.1016/j.jvs.2009.07.019Subhas G, 2009, ANN VASC SURG, V23, P788, DOI 10.1016/j.avsg.2008.12.006Morris JT, 2008, J VASC SURG, V47, P649, DOI 10.1016/j.jvs.2007.08.052Casella IB, 2008, J VASC SURG, V47, P197, DOI 10.1016/j.jvs.2007.07.051Sakamoto I, 2007, EUR J RADIOL, V64, P103, DOI 10.1016/j.ejrad.2007.05.027KIM HK, 2007, J KOREAN SOC VASC SU, V23, P159Picquet J, 2005, J VASC SURG, V42, P788, DOI 10.1016/j.jvs.2005.05.048Froment P, 2004, CARDIOVASC INTER RAD, V27, P529, DOI 10.1007/s00270-003-0158-yNagai T, 2004, INTERNAL MED, V43, P473Okada M, 2004, INTERNAL MED, V43, P451Kim JH, 2004, KOREAN J RADIOL, V5, P134Suzuki S, 2004, ABDOM IMAGING, V29, P153, DOI 10.1007/s00261-003-0110-2Leung DA, 2000, EUR RADIOL, V10, P1916Yasuhara H, 1998, J VASC SURG, V27, P776Nakamura K, 1997, SURG TODAY, V27, P272AMBO T, 1994, SURG TODAY, V24, P933SISTERON A, 1975, CHIRURGIE ARTERIOPAT, P197

Japans Industrial Adjustment and Changes in Employment Structure

The aim of this study is to examine the development mechanism of the Japanese economy and its structural characteristics by analizing the following issues: To which direction has the structure adjustment of Japanese industry been unfolded? By which primary factor are the employment promotion and the change of employment structure in the process of structure adjustment being realized? After early 1970s, Japanese industry has converted its industrial structure from the basic material industry, which is intensive to resource to the processing assembly industry, which is intensive to technology, by giving impetus to the rationalization centering on the outage management under diverse policy supports. Moreover, until the middle of 1980s, they have reinforced the production system of full range industrialization which is obstructive to import and dependent on export in almost all the industries. But, after 1985, they moved the stronghold for production to the foreign countries and increased the product import through foreign direct investment by reflecting the rapid Yen appreciation. Thus, this production system started to collapse with relatively fast speed. In spite of the advance of this so-called industrial hollow tendency, the employment production sectors became stable by the policy support about employment stability, the close cooperation system between labor and management. In the meantime, the service tendency of employment structure and the white collar tendency of job structure progressed rapidly by the expansion of service sectors based on the diversification of enterprice activities. This fact is suggesting that the proper intervention of government about the realm of market failure, the formation of close cooperation system between labor and management, and the business expansion toward new field etc. may advance the structure of employment and job highly, controlling the unemployment with adjustment cost to the minimum

전달경로분석을 적용한 함정용탑재장비의 고체음 예측에 관한 연구

In general, structure borne noise(SBN) causes various vibration problems in machinery and structures. SBN is vibration or noise generated at the receiving point due to source induced vibration or noise transmitted through transfer path. In case of naval shipboard equipment, it must meet higher standards than equipment manufactured by general production process. This is to ensure stability and reliability of the ship and the equipment, and also to ensure airtightness of underwater radiation noise. Thus, the double mounting systems are often used and in this case, according to MIL-STD--740-2, the measuring position of SBN is at the upper surface of the base frame, and must meet the acceptance criteria. In general, for double mounting system the mounting equipment and the base frame are modeled as rigid bodies, and the type of mount, the installation location, and the size and weight of the base frame are designed as rigid mode of the low frequency band. The required frequency range of SBN of MIL-STD-740-2 is up to 10kHz, and SBN is highly affected in this range by flexible mode of the base frame. Therefore, SBN prediction should done in different point of view. In order to predict the SBN of the base frame using forced vibration analysis, it is necessary to analytically calculate or measure the frequency response function(FRF) and the excitation force of the base frame. First, for directly measuring the FRF method, it is difficult to excite up to 10kHz, which is the standard of MIL-STD-740-2. Therefore, finite element analysis(FEA) is used to obtain FRF up to 10 kHz. In order to obtain a high-precision FRF by FEA, detailed data of the entire system, such as the dynamic characteristics of the on-board equipment, base frame, and upper and lower mounts, and accurate excitation force must be provided. However, detailed data on ship payload equipment is difficult to obtain due to the military secrets. Therefore, there is a need for a practical method of calculating FEA without detailed data of the upper elements of the base frame. Because the SBN of the base frame is up to high frequency, it is expected that the flexible mode of the base frame will have much influence. It is also expected that the dynamic characteristics of the upper elements of upper mounts to have little effect on the base frame. This study proposes a method to obtain the FRF only for the base frame, ignoring the upper elements of base frame. Also, this study confirms the validity of analysis method by comparing measured FRF of the base frame with and without the upper elements. As a result, the FRF of the base frame with or without upper elements marginally differs in the low-frequency region of the rigid body mode, and the difference in high-frequency region of the flexible body mode is negligible. Therefore, for SBN analysis, even if the upper elements of the base frame are ignored and only the base frame is analyzed, it is judged that SBN can be predicted without having significant differences compared to the analysis results that consider upper element. Second, it is a method for calculating the excitation force acting from the upper mount to the base frame. The transfer path analysis(TPA) is a method of calculating the excitation force by expressing the relationship between the force of the source and the vibration of the receiver. This is especially useful when the actual vibration mechanism is too complex to be modeled or measured directly. Using the measured SBN according to MIL-STD-740-2 and the calculated FRF of base frame by FEA, the excitation force transmitted from the upper mount to the base frame is calculated using matrix inversion method of TPA. Then the SBN is calculated by applying the excitation force obtained by TPA with the FRF of base frame calculated by FEA. By comparing and reviewing the measured SBN and calculated SBN, the validity of the method of calculating the excitation force by the TPA is confirmed. Also, it is confirmed that the predicted SBN satisfy the MIL-STD-740-2 standard only by changing the shape of the base frame without changing the excitation force or the mount dynamic characteristics. In the future, to improve the accuracy of calculation through reliable modeling and excitation force calculation for various models, it is necessary to measure FRF and predict SBN for various types of naval shipboard equipment. Based on this principle, continuous research on optimal design of base frame for SBN is required.제1장 서 론 1 1.1 연구의 배경 1 1.2 연구의 목적 및 내용 5 1.3 논문의 구성 9 제2장 구조물의 고체음 예측 이론 10 2.1 유연체(다자유도계)의 주파수응답함수 11 2.2 전달경로 분석에 의한 기진력 계산법 17 2.2.1 직접 기진력 측정법 19 2.2.2 마운트 강성법 19 2.2.3 행렬반전기법 21 2.3 기진력을 적용한 고체음 예측법 28 제3장 베이스프레임의 주파수응답함수 계산 29 3.1 베이스프레임 상부요소 배제 가능성 검토 30 3.1.1 상부요소 제거 전·후의 주파수응답함수 측정 33 3.1.2 상부요소 제거 전·후의 실험모드해석 결과 37 3.1.3 베이스프레임의 상부요소 배제 가능성 검토결과 53 3.2 베이스프레임의 주파수응답함수 유한요소해석 55 제4장 베이스프레임에 작용하는 기진력 계산 67 4.1 베이스프레임의 고체음 측정 68 4.2 전달경로 분석을 이용한 기진력 계산 77 4.3 베이스프레임의 고체음 계산 및 검토 89 제5장 구조변경 베이스프레임에 대한 고체음 예측 98 5.1 구조변경 모델들에 대한 주파수응답함수 유한요소해석 99 5.2 구조변경 모델들에 대한 고체음 예측 107 5.3 구조변경 모델들에 대한 고체음 검토 123 제6장 결 론 132 참 고 문 헌 135Docto

CNC SHOP FLOOR 조업지원용 다능형 CAM(POSCAM) 시스템 개발

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