• Fibers and Polymers
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• v.7 no.3
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• pp.305-309
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• 2006

This research studies the factors which influence the tensile strength of tire cords. Five yam samples are made by changing the spinning conditions and viscosity to get various physical properties. Different twisting methods are introduced and the yams are twisted under different processing conditions for each twisting process. With the experimental results, various analyses are performed to find the important factors in retaining strength after the twisting process. SEM and optical microscopic photographs are taken along with some measurements to assist the analysis.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.95-101
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• 2009

The generator for gas turbine power generation consists of the rotor which generates magnetic field, the winding coil which is the path for the field current and the wedge and retaining ring which prevents the radial movement of the coil. Relatively severe deformation was observed at the coil end section during the inspection of the generator for peaking-load operation, and the thermal-electricity and the centrifugal force were evaluated by the simple modeling of the windings to find the cause. But the simulation stress was not sufficient to induce the coil plastic deformation. The analysis result seems to be applicable to the base-load generators which runs continuously without shut down up to a year, but there had been more deformation than simulated for the generator which is started up and shut down frequently. The cause of the coil deformation was the restriction of the expansion and shrinkage. The restriction occurs when the winding coil shrinks, and the stress overwhelms the yield stress and cause the plastic deformation. The deformation is accumulated during the start-ups and shut-downs and the thermal growth occurs. The factors which induce the coil restriction during the expansion and shrinkage should be reduced to prevent the unallowable deformation. The resolutions are cutting off the field current earlier during the generator shut-down, modifying the coil end section to remove the stress concentration and making the insulation plate inserted between the coil end section and the retaining ring have the constant thickness.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.191-205
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• 2017

We use small-scale modelling to estimate the impact ofrce of debris flows on erosion control dams (ECD) and ring nets. The results indicate that the viscoelastic debris flows produced impact forces of 4.14, 3.66, 1.66 kN from the bottom to the top of the ECD. Ring net tests produced a similar trend with generally smaller impact forces (2.28, 1.95, and 1.49 kN). Numerical analysis showed that the weight of the ECD (e.g., concrete retaining walls) provided resistance against the debris flow, whereas deformation of the ring net by elastic-elongation and aggregate penetration reduced the impact force by up to 45% compared with that of the ECD.

• Journal of the Korean Geotechnical Society
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• v.36 no.1
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• pp.29-38
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• 2020

These days the circular cross section cofferdam has been frequently used for the earth retaining structures or cut off wall such as ventilating opening, intake tower in cofferdam, shaft for emergency. By the arching effect, the circular cross section type cofferdam has more advantage than a polygon cofferdam in terms of the structural forces and moment. This paper shows the proper approach to analyze the circular cross section cofferdam using 2D Finite Element Method (FEM) for the circular stiffener (ring beam) evaluation. Besides, the various shapes of cofferdam indluding circular cross section have modeled the 3D Finite Element Mothod (FEM). The circular cross section cofferdam shows the minimum reaction force compared with the other shapes of cofferdam.

• Journal of the Korea Furniture Society
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• v.18 no.4
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• pp.275-281
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• 2007

This study was carried out to know bending process property of bentwood by treatment methods such as microwave and ammonia solution treatment. Bentwood processing was operated on bending-jig form with 60mm and 100mm radius of curvature (ROC). The species was used to Korean red pine (Pinus densiflora). No significant difference was shown in bentwood processing method on ROC. In treatment method, ammonia solution treatment for bentwood was better in dimensional stability and working ability than that of microwave treatment. However, bentwood stress was reduced with ammonia solution treatment. Color of bentwood surface appearance has a dark tendency in ammonia solution treatment. But it seems to beautiful effect of apparent annual ring is rising esthetically by ammonia solution treatment. To utilize wood as a exterior material for living amenity, it has to be closely examined from various angles including surface property, degree of swelling and shrinkage, drying state, retaining strength, durability, safety, and insect damage.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.163-165
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• 2002

High-speed permanent magnet machines are currently being developed for a number of applocations including gas-turbine generator sets and machine tools. Due to the high peripheral speed of the rotor and the relatively high conductively of the magnets used, rotor eddy current loss can be substantial. On the basis of analytical and finite element method, this paper deals with an analytical method for calculating eddy current losses in the rotor with permanent magnet and retaining ring.

• Journal of Chest Surgery
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• v.55 no.2
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• pp.177-179
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• 2022

Barlow's disease with mitral annular calcification encompassing the subvalvular apparatus, including the valve leaflet and chordae, is extremely rare, and mitral valve repair in such cases is challenging. We report a case of a 60-year-old woman with mitral valve regurgitation that was successfully controlled by resecting the rough zone of P2 and calcifications on the excess leaflet regions and subvalvular apparatus, while retaining the calcification of P3 and implanting artificial chordae and an annuloplasty ring. Mitral valve repair for such cases requires an individualized and compounded surgical strategy for the technique to treat Barlow's disease and manage calcification to control mitral regurgitation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.643-649
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• 2011

For the development of butterfly valves used in liquefied natural gas (LNG) vessels, the seat tightness is one of the important factors to be taken into account in the valve-design process. An O-ring-type metal seal with a retaining ring showing good seat tightness at cryogenic temperatures has been widely used, despite the high manufacturing costs involved. As an alternative, a flexible solid metal seal offers not only sufficient tightness of the butterfly valve, meeting specification requirements, but also relatively low manufacturing costs. In this study, a design criterion to ensure the seat tightness of the butterfly valve using the flexible solid metal seal is proposed. The contact pressure can be calculated by the simulation of the frictional contact behavior between the surface of the metal seal and the valve disc. The geometry of the flexible solid metal seal is determined so that it satisfies the design criterion for sufficient seat tightness, and is verified by experiments according to BS6755 and BS6364.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1256-1261
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• 2015

Along with the increase of railway catenary system operation speed to 400 km/h, there have been growing demands for good quality current collection systems that satisfy quality standards as well as criteria for safe working. Retaining uniform elasticity tension of contact wires is essential in maintaining high quality contact between pantograph and OCL (Overhead Contact Line) of current collection systems in high speed railways. Therefore, the tension of contact wire must be kept within tight tolerance limits in both working conditions and adverse weather conditions of catenary system. In accordance with these conditions, this paper presents a real time monitoring system for the tensioning device of the newly installed catenary system on the special route of Honam high speed line for 400 km/h operation. For the verification of the true value of tension of contact wires, we have developed ring-type tensioning sensors which were installed on supporting points of mast which compose the catenary system. According to the field test performed on the Honam high speed line catenary system, variation of tension was measured accurately in real-time.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.184-191
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• 2003

New pyranone derivative, 2-((3E)-4(2H, 3H, -benzo[3, 4-d] 1, 3-dioxolan-5-yl)-2-oxo-but-3-enyloxy)-5-hydroxy-4H-pyran-4-one (Seletinoid $G^{TM}$), was designed as a novel retinoid on the assumption that the pyranone ring may mimic the carboxylic acid moiety in retinoid structure. The enolic hydroxy of pyranone at five position was easily deprotonated to form an enolate. The role of enolate was similar to that of carboxylic acid. To evaluate the value of Seletinoid G as an anti-aging ingredient, various tests were performed for example inhibitory effect for MMP-l expression, anti-oxidative activity, procollagen synthesis in hairless mouse and primary skin irritation. The result of this study suggested that our new synthetic retinoid could be used as a safe material for anti-aging cosmetics.