• Journal of Digestive Cancer Research
• /
• 제10권2호
• /
• pp.92-98
• /
• 2022

Self-expandable metal stent (SEMS) is effective for biliary drainage, especially in pancreaticobiliary cancer. The mechanical properties, material, and design of SEMS are important in preventing recurrent biliary obstruction and complication. Radial and chronic expansion forces play roles in preventing stent migration and collapse. Complications, such as stent impaction, cholecystitis, and pancreatitis, were related to the axial force. The nickel-titanium alloy shows more flexibility, conformability, and optimal axial force compared to previously used stainless steel. Additionally, the stent structure affected the mechanical properties of SEMS. Therefore, understanding the mechanical properties, material, and design of SEMS will provide the best outcome for biliary drainage, as well as better SEMS development.

• Journal of Digestive Cancer Research
• /
• 제12권1호
• /
• pp.15-22
• /
• 2024

Malignant colorectal obstructions urgently require decompression therapy to prevent the severe risks of intestinal ischemia and bowel perforation. In managing malignant colonic strictures endoscopically, the use of self-expandable metal stents (SEMS) is the predominant approach. Colonic SEMs are primarily used in preoperative decompression therapy before curative surgery and palliative treatment in patients with advanced disease stages. Furthermore, the stenting process, which requires rigorous clinical supervision, can lead to complications. This review endeavors to concisely review the clinical considerations associated with the SEMS procedure, with a focus on its indications, technical aspects, and potential complications that may arise during the procedure.

• Journal of Chest Surgery
• /
• 제33권1호
• /
• pp.99-102
• /
• 2000

The usual treatment for aortic aneurysms is surgical replacement with a prosthetic graft; however the associated morbidity and mortality rates must be considered. Endovascular placement of self-expandable stent-graft is a safe noninvasive treatment that can be an alternative to the surgical repair, the postoperative course of the 2 cases of thoracoabdominal aortic aneurysms was uneventful and no complication has been associated with the stent-graft during the 17 months and 5 months follow-up studies,.

• 공업화학
• /
• 제27권3호
• /
• pp.270-275
• /
• 2016

길이가 다른 두 종류의 케나프 섬유(kenaf fiber, KF)가 적용된 고밀도폴리에틸렌(high density polyethylene, HDPE)/KF 복합체를 이축압출기를 이용하여 제조하였다. HDPE/KF 복합체의 발포를 위해 열팽창성 마이크로캡슐(thermal expandable microcapsule, EMC)이 이용되었다. 0.3과 3 mm 길이의 KF가 사용되었고, KF와 EMC의 함량은 각각 20 wt%와 5 wt%로 고정하였다. 화학처리된 KF의 FT-IR 결과 1700과 $1300cm^{-1}$ 근처에서의 피크 감소를 보여주는데, 이는 KF 성분 중 리그닌과 헤미셀룰로오스가 감소되기 때문으로 유추할 수 있다. 발포비중, 인장특성을 평가할 때 3 mm 섬유를 사용한 복합체의 물성이 양호하게 나타났지만, 섬유의 길이가 길수록 열분해에 의한 외관 불량 등의 문제가 발생할 수 있어 산업적 응용에 따라 적절한 섬유 길이의 선택이 요구된다. 화학 처리한 0.3 mm KF가 사용된 복합체의 인장강도가 소폭 증가하였다.

• Steel and Composite Structures
• /
• 제44권2호
• /
• pp.271-281
• /
• 2022

This study discusses challenges of running expandable profile liners (EPLs) to isolate trouble zones in directional section of a deep well, and summary the expandable profile liner technology (EPLT) field trial experience. Technically, the trial result reveals that it is feasible to apply the EPLT solving lost-circulation control problem and wellbore instability in the deep directional section. Propose schemes for optimizing the EPLT operation procedure to break through the existing bottleneck of EPLT in the deep directional section. Better-performing transition joints are developed to improve EPL string reliability in high borehole curvature section. High-performing and reliable expanders reduce the number of trips, offer excellent mechanical shaping efficiency, simplify the EPLT operation procedure. Application of the expansion and repair integrated tool could minimize the risk of insufficient expansion and increase the operational length of the EPL string. The new welding process and integrated automatic welding equipment improve the welding quality and EPL string structural integrity. These optimization schemes and recent new advancements in EPLT can bring significant economic benefits and promote the application of EPLT to meet future challenges.

• Clinical Endoscopy
• /
• 제55권3호
• /
• pp.434-442
• /
• 2022

Background/Aims: Covered self-expandable metallic stents (CMSs) are widely used for malignant distal biliary obstructions (MDBOs) caused by pancreatic carcinoma. This study compared the efficacy and safety of the laser-cut-type and braided-type CMSs. Methods: To palliate MDBOs caused by pancreatic carcinoma, the laser-cut-type CMSs was used from April 2014 to March 2017, and the braided-type CMSs was used from April 2017 to March 2019. The tested self-expandable metallic stents were equipped with different anti-migration systems. Results: In total, 47 patients received CMSs for MDBOs (24 laser-cut type, 23 braided-type). The time to recurrent biliary obstruction (TRBO) was significantly longer in the braided-type CMSs (p=0.0008), and the median time to stent dysfunction or patient death was 141 and 265 days in the laser-cut-type CMSs and braided-type CMSs, respectively (p=0.0023). Stent migration was the major cause of stent dysfunction in both groups, which occurred in 37.5% of the laser-cut-type CMSs and 13.0% of the braided-type CMSs. There were no differences in the survival duration between the groups. Conclusions: The TRBO was significantly longer for the braided-type CMSs with an anti-migration system than for the laser-cut-type. Stent migration tended to be less frequent with the braided-type CMSs than with the laser-cut-type CMSs.

• 한국가구학회지
• /
• 제27권4호
• /
• pp.392-398
• /
• 2016

Wood-plastic composites (WPCs) composed of mainly wood flour and thermoplastics have attracted considerable attentions due to advantages of cost effectiveness, high durability, and microbial resistance. However, relatively poor fire resistance of WPCs from low thermal stability of wood and plastics prevents further uses. This study investigated the effect of expandable graphite (EG) and aluminium hydroxide (AH)/magnesium hydroxide (MH) on the properties of WPCs. The combined incorporation of both EG and metal hydroxide (i.e., AH or MH) into formulations leads to higher flexural modulus of filled composites compared to neat PP and WPC. In thermal properties, EG played an important role in improving thermal stability of filled composites by suppressing thermal decompositions of wood and PP. Moreover, EG showed better water absorption features. From this research, it can be said that EG and metal hydroxides have potentials as effective reinforcement, flame retardant, and moisture barrier.

• 대한기계학회논문집A
• /
• 제28권7호
• /
• pp.915-922
• /
• 2004

A stent is small tube-like structure expanded into stenotic arteries to restore blood flow. The stent expansion behaviors define the effectiveness of the surgical operation. In this paper, finite-element method was employed to analyze expansion behaviors and fatigue life of a typical diamond-shaped balloon-expandable stent. Beyond safety considerations, this type of analysis provides mechanical properties that are often difficult to obtain by experiments. Mechanical properties of the stent expansion pressure, radial recoil, longitudinal recoil and foreshortening were simulated using commercial FEM code, ANSYS and fatigue life were estimated using NISAII ENDURE. The FEM results showed that the pressures necessary to expand the stent up to a diameter of 3mm, 4mm and 5mm were 0.75MPa, 0.82MPa and 0.97MPa. The fatigue lifes according to expansion diameter were 114${\times}$10$^{7}$cycles, 714${\times}$$^{6}$cycles and 163${\times}$10$^{6}$cycles. As a result, a finite element model used in this study can simulate expansion behaviors of stents and should be useful to design new stents or analyze actual stents.

• 한국실내디자인학회논문집
• /
• 제17권2호
• /
• pp.30-38
• /
• 2008

It has been stated that the outer skin of an architecture should be related to and express the interior programs. It was rather moral issue than practicality. In contemporary urban cities, this nicely-linked relationship between exterior and interior has become much more complex and, in many cases, is no more valid. It tends that contemporary architectural skin is somehow separately developed and has its own logic to be independent from what is inside. This research focuses on these sort of logical design process to make unique image of skin in which conceptual thinking, spatialization and materialization are mixed together. More specifically this study articulates' expandable patternization process' based on the notion that it has a crucial role to systematically construct an image of skin. Expandable patternization has a couple of stages to complete an architectural skin. The first element is a single unit and the second is organization or arrangement of units based on a logical process. Lastly, the third is spatialization after relating the skin to the interior programs as well as environmental surroundings. It is found that, although, in most related projects, the architect or designer has followed his or her own preference or design tendencies, many skin projects has based the given unique characteristics from the beginning. This study concludes that skin design is not just an image making, but has an important role to amalgamate various aspects of an architectural projects: programs, concept of architect, environment, structure as well as image.

• 한국염색가공학회지
• /
• 제31권3호
• /
• pp.187-194
• /
• 2019

Blowing film was prepared using polyester elastomer with thermally expandable microcapsule to investigate the optimum blowing properties and the film making process. Physical properties including specific gravity, blowing efficiency, foaming shape, tensile strength and elongation of polyester film were tested by varying the process condition of temperature and revolution per minutes of the extruder. The lowest specific gravity of 0.709 can be achieved with excellent foaming cells at $210^{\circ}C$ and 50 RPM conditions. The highest tensile strength and elongation was shown at $210^{\circ}C$, 100 RPM and $230^{\circ}C$, 25 RPM conditions. However, most of the prepared polyester films showed over $1kg_f/mm^2$ of tensile strength which is reasonable value to use in film applications.