• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.791-796
• /
• 2011

In order to understand long range wave propagation in railway tracks, it is required to identify how far vibrations can travel along a rail. To answer this question, the attenuation characteristics of the main propagating waves are required as a function of distance. In this work, it is identified which wave types predominantly propagate on various regions of the rail cross-section. Then decay rates of propagating waves in railway tracks are investigated for frequencies up to 80 kHz. A numerical method called the Wavenumber Finite Element (WFE) method is utilized to predict dispersion curves and decay rates for a rail on a continuous foundation. In order to validate the simulated results, measurements have been performed on a test track and an operational railway track. The measured results are compared with the output of the simulations and good agreements are found between them.

• Food Engineering Progress
• /
• v.13 no.3
• /
• pp.176-182
• /
• 2009

This study was carried out to analyse the physicochemical characteristics of soybean pastes with the sword beans and general soybean pastes. There was no difference in contents of general component (moisture contents, crude ash, crude fiber, crude fat) among the soybean pastes, but contents of crude protein was higher in J1, J2 compared to the others. Amylase activity was higher in J3, J4 adding the rice, and protease activity was higher in J1, J2 that has higher soybean contents than the others. Reducing sugar contents was higher in J3, J4 that has high amlyase activity with value of 8.53${\pm}$0.45% and 8.36${\pm}$1.05%, and amino-type nitrogen contents was higher in commercial soybean paste K5, K6 than other soybean pastes with value of 668.34${\pm}$4.11 mg% and 642.64${\pm}$2.05 mg% respectively.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.991-993
• /
• 1997

This paper presents a novel modeling methodology for STATCON and relevant controller using EMTP. It also provides with an idea for suppressing numerical oscillation that usually occur at switching operation by incorporating resistor component of STATCON into system modeling. Some simulation results validate propriety of methodology the proposed for modeling of system and suppressing numerical oscillation.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.464-466
• /
• 2007

H-Bridge Multi-Level (HBML) 고압인버터는 저압의 반도체 소자를 사용하는 단상 H-Bridge 인버터로 구성 된 셀을 직렬로 연결함으로써 정현파에 가까운 고전압을 얻을 수 있고, 입 출력 고조파가 낮아서 필터가 필요 없는 토폴로지로 산업분야에서 사용이 확대되고 있다. 본 논문은 HBML 고압인버터의 마스터 제어기와 셀 제어기의 통신 하드웨어를 병렬로 구성하여서 하나의 전압지령 값과 Angle 값으로 셀에서 PWM을 구현 할 수 있는 분산제어 방식을 제안한다. 이 방식에서 셀 제어기가 전압, 전류, 주파수, 보호기능, 통신감시 정보 등 셀 제어의 대부분을 담당함으로써 마스터 제어기의 부담을 줄이고, 따라서 신호선의 개수를 줄일 수 있다. 또 통신하드웨어의 종단에 마스터 제어기를 연결만 하면 마스터제어기의 2중화가 가능하므로 사용하고 있던 마스터 제어기의 고장 발생 시에 대체하여 사용할 수 있으므로 시스템의 안정성 향상에 도움을 준다. 선간전압 33레벨로 구성된 HBML 고압인버터 시험을 통해 제안된 방식의 타당성과 신뢰성을 검증한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2004.07a
• /
• pp.168-168
• /
• 2004

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.13 no.4
• /
• pp.653-659
• /
• 1989

Elastic-plastic fracture toughness J$_{IC}$ can be used as an effective design criterion in elastic plastic fracture mechanics. In the J$_{IC}$ test methods approved by ASTM and JSME, there are discrepancies such as the definition of J$_{IC}$, the slope of the blunting line, curve fitting method and the measurement of crack extension etc. The objective of this paper is to evaluate the effect of these discrepancies on the determination of J$_{IC}$ values. Fracture toughness tests were performed on A516, SA508 and SCM415 steels, and test results were analyzed according to ASTM E 813-81, ASTM E 813-87 and JSME S 001-1981. Results showed significant differences depending on the analysis methods. Therefore, a conversion equation between two ASTM methods was proposed, and the conversion error was within acceptable range(less then 8.5%)en 8.5%)

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.54-59
• /
• 2004

In this paper probabilistic fracture mechanics(PFM) approach is employed to evaluate the integrity of CANDU Zr-2.5Nb pressure tubes. Modified failure assessment diagram(Jr-FAD), plastic collapse, and critical crack length(CCL) approach are used for evaluating failure probability of the tubes. Jr-FAD was extended from the Kr-FAD because fracture of pressure tubes occurs in brittle manner due to hydrogen embrittlement of material by deuterium fluence. For developing the probabilistic integrity evaluation module, AECL procedures and fracture toughness parameters of EPRI were used.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.96-101
• /
• 2004

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal embrittlement at the reactor operating temperature. The objective of this study is to summarize the method of estimating ferrite content, Charpy impact energy and J-R curve and to evaluate the thermal embrittlement of the cast austenitic stainless steel piping used in the domestic nuclear power plants. The result of evaluation, two domestic nuclear power plants used CF-8M and CF-8A material has adequate fracture toughness after saturation.

• Applied Chemistry for Engineering
• /
• v.31 no.2
• /
• pp.164-171
• /
• 2020

Adsorption characteristics of reactive red 120 (RR 120) dye by a coal-based granular activated carbon (CGAC) from an aqueous solution were investigated using the amount of activated carbon, pH, initial concentration, contact time and temperature as adsorption variables. Isotherm equilibrium relationship showed that Langmuir's equation fits better than that of Freundlich's equation. The adsorption mechanism was considered to be superior to the adsorption of monolayer with uniform energy distribution. From the evaluated Langmuir separation coefficients (R_L = 0.181~0.644), it was found that this adsorption process belongs to an effective treatment area (R_L = 0~1). The adsorption energy determined by Temkin's equation and Dubinin-Radushkevich's equation was E = 15.31~7.12 J/mol and B = 0.223~0.365 kJ/mol, respectively. The adsorption process showed the physical adsorption (E < 20 J/mol and B < 8 kJ/mol). The adsorption kinetics followed the pseudo first order model. The adsorption reaction of RR 120 dye on CGAC was found to increase spontaneously with increasing the temperature because the free energy change decreased with increasing the temperature. The enthalpy change (12.747 kJ/mol) indicated an endothermic reaction. The isosteric heat of adsorption (△H_x = 9.78~24.21 kJ/mol) for the adsorption reaction of RR 120 by CGAC was revealed to be the physical adsorption (△H_x < 80 kJ/mol).

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.1063-1065
• /
• 1996

As PLC has become central to today's FA environment, the importance of developing and providing special-module of PLC such as Analog-module, PID-module, Temperature Control-module has increased. In this paper introduces the Temperature Control-module which is developed by LGIS R&D lab. and presents the availability of PLC-control system with Temperature Control-module.