• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.400-403
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• 2008

For the effective manufacture of doubly curved metal plates, a line array roll set (LARS) process is proposed. The suggested process utilizes a pair of upper and lower symmetric roll assemblies. In the process, the initial plate is progressed into the final shape in a stepwise or pathwise manner according to the basic principle of the incremental forming process. The deformation proceeds simultaneously in the longitudinal and transverse directions. Moreover, there is a close correlation between the deformation in the longitudinal direction and that in the transverse direction of the plates. Therefore, the finally formed shape in the incremental forming process is strongly dependent upon process conditions, such as the forming path and the forming increment. The manufacturing of arbitrary doubly curved plates with various curvatures is not an easy task because of such complicated behaviors of the plate; thus, the forming schedules for the desired shape should be carefully and accurately designed. In this study, several experiments with the LARS system were carried out for the fundamental investigation on process design for manufacturing of doubly curved plates.

• Clinical Endoscopy
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• v.56 no.6
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• pp.812-816
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• 2023

We report a rare case of gastric cancer presenting with a gastrocolic fistula during ramucirumab and paclitaxel combination therapy that was successfully managed with colonic stenting. A 75-year-old man was admitted to our hospital with the chief complaint of melena. Esophagogastroduodenoscopy revealed a large ulcerated tumor in the lower stomach, judged by laparoscopy as unresectable (sT4bN1M0). After four cycles of first-line chemotherapy with S-1 plus oxaliplatin, the patient showed disease progression, and second-line therapy with ramucirumab and paclitaxel was started. At the end of the third cycle, the patient had gastric antral stenosis, which necessitated the placement of a gastroduodenal stent. When the patient complained of diarrhea 10 days later, esophagogastroduodenoscopy revealed a fistula between the greater curvature of the stomach and the transverse colon. The fistula was covered by double colonic stenting, with a covered metal stent placed within an uncovered metal stent, after which leakage from the stomach to the colon stopped.

• Korean Journal of Optics and Photonics
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• v.27 no.5
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• pp.174-180
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• 2016

A tunable optical delay line is designed, fabricated, and characterized. The tunable delay line consists of four polymer-ring add/drop filters with delay waveguides between adjacent ones. The polymer waveguide is a buried structure, designed to be square with core width and height of $1.8{\mu}m$. The refractive indices of the core and cladding polymer are 1.48 and 1.37 respectively. The large index difference and small cross section of the waveguide enable us to realize a compact device using a small radius of curvature. Four pairs of electrodes are evaporated above the add/drop filters to provide heating currents for thermal tuning. In measurements we can identify variable time delays of 110, 225, and 330 ps in proportion to the number of delay lines.

• Water for future
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• v.18 no.1
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• pp.57-65
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• 1985

In recent years, an increment of river engineering activities and more intensive use of flood plain, the river geomorphology has attracted considerable attention owing to an extensive land reclamation. One of the important problems is the maintenance of river meanders and almost all natural rivers exhibit the tendency to be a meander. A statistical analysis is applied to typifying their shapes and the meander characteristics are analyzed by channel model of line generalization algorithm in this study. This method is applied to Han River System. The results show that the variance of curvature is a better index to describe the meander intensity and the kurtosis is a good index to characterize the total lengh of the straight sections for a given reach. The channel model of line generalization algorithm gives good results in analysis of meander characteristics.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.51-56
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• 2010

A numerical simulation is carried out to investigate the effect of flow rate variation and performance characteristics of double-suction centrifugal pump. Two types of pump which have different impeller inlet breadth and curvature of the shroud line consist of six blades impeller and shroud ring. Finite-volume method with structured mesh and $k-\omega$ Shear Stress Transport turbulence model was used to guaranty more accurate prediction of turbulent flow in the pump impeller. Total head, power and overall efficiency were calculated to obtain performance characteristics of two types of pump according to the variation of flow rate. From the results, impeller having smooth curve along the shroud line obtained good performance. The lower flow rate, the more circulation region, flow unsteadiness and complicate flow pattern are observed. Complicated internal flow phenomena through impellers such as flow separation, pressure loss, flow unsteadiness and performance are investigated and discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.1961-1970
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• 2002

A laser scanner is widely used fur a device fur acquiring point data in reverse engineering. It is more efficient to generate a surface automatically from the line-typed data than scattered data of points clouds. In the case of a compound model, it is hard to represent all the scanned data into one surface maintaining its original line characteristics. In this paper, a method is presented to generate a surface by the segmentation of measured point data. After forming triangular net, the segmentation is done by the user input such as the angle between triangles, the number of facets to be considered as small segment, and the angle for combining small segment. B-spline fitting is implemented to the point data in each segment. The surface generation through segmentation shows a reliable result when it is applied to the models with curvature deviation regions. An useful algorithm for surface reconstruction is developed and verified by applying an practical model and shows a good tools fur reverse engineering in design modification.

• Water for future
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• v.15 no.1
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• pp.33-42
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• 1982

In recent years owing to extensive land reclamation, increased river engineering activites and morer intense flood plain use, river geomorphology has attracted considerable attention. One of outstanding problems has been maintenance of river meanders and nearly all natural river exhibit the tendency to meander. Often the meander geometry was fitted in to various idealized model. COnsequently, both the selection of data and the methods to determine the geometric parameters were highly subject to individual preferences. This study applied statistical analysis in tipifying their shape and analysised meander characteristics by channel model of line generalization algorithm. This method is applied to Geum river system. The results show that the variance of curvature is a better index to describe the meander intensity and the kurtosis is a good index to characterize the total length of the straight sections for a given reach. The results also show that channel model of line generalization algorithm is a good model in analysis of meander characterisitics.

• Journal of Korean Association for Spatial Structures
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• v.6 no.1 s.19
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• pp.117-127
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• 2006

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cooing pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cooing pattern generation using geodesic line, and investigate the result of example's cooing pattern in detail.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.181-188
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• 2024

With the development of precision facility technology, the importance of four-axis CNC precision processing technology is increasing. However, due to complex shape processing, it is difficult to operate the system. This paper compared precision control and efficiency by manufacturing a four-axis control structure to solve this problem and implementing Bresenham's Line Algorithm and Runspeed Algorithm without using commercial programs. When Runspeed was applied, there was an error improvement of about 12.03% and curvature accuracy improvement compared to Bresenham. It was confirmed that precise processing was possible to a three-dimensional structure by driving a rotary shaft A motor.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.1
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• pp.113-124
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• 2009

Objectives : The aim of this study was to observe the effect of Bong Chuna manual therapy(BCMT) and acupuncture on the Turtle Neck Syndrome(TNS) by the changes of radiological findings and symptoms. Methods : Total twenty-eight patients diagnosed as TNS were evaluated. Twenty patients in experimental group were treated by the combination of BCMT and acupuncture, eight patients in control group were treated by acupuncture only. We measured VAS(Visual analogue scale) as pain intensity and Neck Pain and Disability Scale(NDI) at pre- and post-treatment. Also the four line Cobb's method and Jochumsen method were assessed for evaluating the radiographical changes, additionally we used 'two line method'. Results : VAS score showed statistically significant reduction in pain intensity in both experimental group and control group after 8 weeks treatment, $-44.05{\pm}14.91$ vs $-23.75{\pm}14.08$ respectively. Also NDI score presented $-11.40{\pm}8.63$ reduction in experimental group, and it was significant statistically, however not in control group, $-8.63{\pm}9.84$ reduction after 8weeks treatment. In radiological findings, the four line Cobb's method, Jochumsen method and two line method were reduced after 8weeks treatment, $-9.30{\pm}10.33$, $-0.65{\pm}1.72$ and $-14.35{\pm}5.68$ in experimental group respectively, $-0.75{\pm}1.91$, $-0.25{\pm}0.71$ and $0.38{\pm}2.20$ in control group respectively. However they were statistical significance only in the four line Cobb's method and two line method in both group. Conclusions : Combination treatment of CMT and acupuncture showed better effect on pain reduction, VAS score and the correction of neck anteversion than acupuncture only in TNS. Two line method seems valuable for evaluating the improvement of radiographical changes in TNS.