• ETRI Journal
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• v.29 no.1
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• pp.116-119
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• 2007

In this letter, we design a collision resolution protocol for optical burst switching ring networks to avoid burst collision. We define the offset time condition for no burst transmission collision and manage the free time list of nodes for no burst reception collision. In order to improve the throughput, we use a fiber delay line, void-filling, and void-compression. This protocol does not require any additional procedures for bandwidth reservation such as centralized assignment of bandwidth, lightpath setup of WDM ring networks, or token capturing for the burst transmission. The simulation results show that the proposed protocol can achieve high throughput while saving 70% of wavelengths when compared to round robin with random selection, round robin with persistent, and round robin with non-persistent with only destination delay.

• ETRI Journal
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• v.25 no.3
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• pp.195-202
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• 2003

This paper proposes a new LDMOSFET structure with a trenched sinker for high-power RF amplifiers. Using a low-temperature, deep-trench technology, we succeeded in drastically shrinking the sinker area to one-third the size of the conventional diffusion-type structure. The RF performance of the proposed device with a channel width of 5 mm showed a small signal gain of 16.5 dB and a maximum peak power of 32 dBm with a power-added efficiency of 25% at 2 GHz. Furthermore, the trench sinker, which was applied to the guard ring to suppress coupling between inductors, showed an excellent blocking performance below -40 dB at a frequency of up to 20 GHz. These results confirm that the proposed trenched sinker should be an effective technology both as a compact sinker for RF power devices and as a guard ring against coupling.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.170-173
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• 2001

The design for cold extrusion dies is very important because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, two assumptions were proposed. First assumption was selected by yielding strength dependent on the to hoop stress of each ring in dies. Second assumption is that the maximum inner pressure is determined when yielding occurs in one ring of dies. To obtain the maximum inner pressure the flexible tolerance method was applied. A comparison of design values between the proposed method and the conventional method has been discussed.

• Fashion & Textile Research Journal
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• v.15 no.4
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• pp.606-612
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• 2013

This paper investigates the physical properties of organic cotton staple yarns manufactured by ring and siro spinning methods as well as analyzes the physical properties of fabric specimens knitted with staple yarns made by these two methods. The breaking stress and evenness of organic ring staple yarns showed the same level for the Japanese specimens as the control yarns; in addition, the same coefficient for the friction of the manufactured yarns and Japanese specimens was also shown. These results makes it possible to manufacture organic staple ring yarns from organic cotton fibers. The tenacity and breaking strain of siro staple yarns were higher than ring staple yarns. The evenness and friction coefficient of siro staple yarns were lower than the ring staple yarns; in addition, hairiness and the number of siro staple yarns was significantly lower than the ring staple yarns. The dimensional stabilities of knitted fabrics by 20 Ne and 30 Ne siro staple yarns were superior to ring staple yarns. The color fastnesses of washing, perspiration and abrasion of knitted fabrics by two spinning methods showed the same level as the 4.5 grade; however, the light fastness of knitted fabric by siro staple yarns was superior to ring staple yarns. It was shown that the siro spinning method (using eco-friendly organic cotton fibers) was applicable to a high sensible knitted garment that overcame drawbacks of organic fibers related to shrinkable properties after washing and low color fastness to light.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.613-617
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• 2001

The test items like as endurance, air leakage and oil endurance test is requested for reliability evaluation about O-ring which is a kind of core machinery accessories of semi-conduct manufacturing equipment. For verification of these, we design and manufactured a test system for endurance, air leakage and oil endurance of O-ring for semi-conduct manufacturing equipment, and also performed the test for two kinds of O-ring, as it were Viton and Kalretz. The characteristics of this test equipment consist in realization of the test conditions of semi-conduct manufacturing equipment and satisfying the test method. The test conditions are cut gas, vacuum grade, temperature and revolution numbers in the endurance test system, vacuum grade and temperature in the air leakage test system, temperature and time in the oil endurance test system. The separating test results for wearing which is an oil endurance test item, the wearing index of domestic produced Viton O-ring is higher than foreign product by 2%, wearing rate of Kalretz O-ring better than Viton O-ring by 17%, and particles existed in various place. The test result of air leakage which is measured through the RGA sensor used Helium, the vacuum grade was $10^-3$Torr. And the test result of oil endurance, the volume change rate was 7~15%. Hereafter, we intend to analysis the reliability test evaluation and to utilize for domestic manufacturing companies by establishing data base and developing reliability softwares.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2382-2392
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• 2014

In this paper, a new data frame structure for wavelength routing in optical ring access network(ORAN) is designed and the functions of each field in the frame are defined. In addition, the IP packet transmission to the network layer corresponding to the newly proposed structure of the protocol stack is newly presented. Tha data transmission protocol design techniques of ORAN was proposed. IP packet and broadcasting packet transmission within the sub-network, and the IP packet transmission to other sub-network was shown through the process illustration. In the process, the encapsulation and framing process of the wavelength information to routing has been described in detail. And each step takes place in a packet transfer process is demonstrated. A ring type optical access network protocol is not yet research field. ORAN data transfer protocol to send/receive module structure of a subscriber node and a control node of the two rings which analyzed the results are shown. The high-speed Internet solution is proposed that by using wavelength routing the packet transport protocol for ORAN is designed.

• Composites Research
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• v.23 no.3
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• pp.37-42
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• 2010

The fiber material properties, elastic constant and strength, are the most important factors among the various material properties for the design of composite pressure vessel, because of it's dominant influence on the performance of composite pressure vessel. That is, the deformation and burst pressure of pressure vessel highly affected by the fiber material properties. Therefore, the establishment of test method for exact fiber material properties is a priority item to design a composite pressure vessel. However, the fiber material properties in filament wound pressure vessel is very sensitive on various processing variables (equipment, operator and environmental condition etc..) and size effect, so that it isn't possible to measure exact fiber material properties from existing test methods. The hydro-burst test with full scale pressure vessel is a best method to obtain fiber material properties, but it requires a enormous cost. Thus, this paper suggests a newly developed test method, hoop ring test, that is capable of pressure testing with ring specimens extracted from real composite pressure vessel. The fiber material properties from hoop ring test method showed good agreement with the results of hydro-burst test with full scale composite pressure vessels.

• Tribology and Lubricants
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• v.23 no.5
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• pp.201-206
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• 2007

The bent-axis type piston pump which is driven by the piston rod works on the way that the piston rod drives the cylinder block, so the taper angle of the piston rod and the swivel angle between the cylinder block and the shaft are very important design factors. If the above factors cannot satisfy the conditions of optimum design, the friction loss between the cylinder bore and the piston increases, and the pump can even fail to work under conditions of severe friction and wear. Since the piston reciprocates in the cylinder bore with high velocity, and at the same time it rotates on its own axis and revolves on the center of the cylinder block, the decrease of the volume efficiency generated on account of the leakage between the cylinder bore and the piston. Therefore, to prevent this case, the piston ring is designed at the end of the piston, and the friction characteristics between the piston ring and the cylinder bore are in need of research due to its great influence on the performance of piston pump. Thus, in this paper, the elastic hydraulic oil's lubrication analyses of the film thickness, the pressure distribution, and the friction force, and so on, have been performed, and the lubrication characteristics between the piston ring and the cylinder bore are explored by the results of the numerical analysis, and it is contributed to realize the higher efficiency and the more advanced performance of the bent-axis type piston pump.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.27-35
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• 1999

A radius of ring resonator is determined by the resonant frequency. Resonant frequencies of resonators with the circumference which is integer times of wave length are not same the expected. In this paper, we suggest the design method of a ring resonator with coupling gap, which has the resonant frequency of desire. The equation which can make reduction of the radius of the resonators depending on the gap space is derived by the method of transmission line analysis. The criterion is suggested to determine the radius of the resonator in accordance with relative permittivity. A ring resonator by the proposed method is as small as one-third of basic ring in size and it has the resonant frequency of desire. T-type coupling line is designed to obtain large attenuation of $S_{11}$ at pass-band. These coupling line capacitances are very lower than the gap capacitances, it does not affect the resonant frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.268-275
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• 2014

In this paper, a dual-band circular ring monopole antenna with stub and ground slot for WLAN(Wireless Local Area Networks)/WiMAX(World interoperability for Microwave Access) applications. The proposed antenna is based on a planar monopole design, and composed of one circular ring of radiating patch, cross strip in circular ring, modified feed line, and two rectangular slot in the ground plane for triple-band operation. To obtain the optimized parameters, we used the simulator, Ansoft's High Frequency Structure Simulator(HFSS) and found the parameters that greatly effect antenna characteristics. Using the obtained parameters, the antenna is fabricated. The numerical and experiment results demonstrated that the proposed antenna satisfied the -10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. And characteristics of gain and radiation patterns are determined for WLAN/WiMAX application.