• 한국전기전자재료학회논문지
• /
• 제19권3호
• /
• pp.287-291
• /
• 2006

This paper describes mechanical and electric properties of ACSR $410\;mm^2$ conductor from many of older overhead conductor. Samples of conductors itemized two division according to operation sector, green area, salt and pollution area. Samples of conductors operated various environment conditions have undergone laboratory metallurigical investigation and tensile strength torsional ductility and electrical performance. The steel core were found to have retained their original properties to a large degree in both tensile strength and the number of turns to failure. On the other hand the aluminum conductor showed reductions in tensile strength. To determine the remaining useful life of aged conductor, an unacceptable deterioration level has to established for each diagnostic procedure.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1996년도 추계학술대회 논문집
• /
• pp.1044-1047
• /
• 1996

This paper presents durability characteristics of electrorheological(ER) fluids which undergo a reversible phase change depending upon the imposition of electric fields. The field-dependent Bingham properties are subjected to be altered from long time use of the ER fluid. The level of the changed properties depends upon employed device and test conditions. A piston-rod system which has same mechanism as ER dampers is adopted in this study and tested by increasing operation cycle up to 1 million. Bingham properties of initial and us ER fluids are tested and compared. In addition, these ER fluids are applied to ER damper in order to evaluate damping force performance.

• 한국생산제조학회지
• /
• 제25권5호
• /
• pp.380-385
• /
• 2016

Railway tracks are repeatedly overstressed and damaged owing to increase in passing tonnage and numerous contact cycles between wheels of train and rails. In order to ensure safe train operation, heat-treated rails are used in addition to regular inspection and maintenance of these rails. Normal rails were treated using ultrasonic nanocrystal surface modification (UNSM) to strengthen the surface of rails. A few changes in surface properties were detected with respect to hardness and compressive residual stress after UNSM treatment. Wear and rolling contact fatigue tests were performed using rails whose surfaces were hardened by UNSM and heat-treated rails. The amount of wear and fatigue life cycles were measured to estimate the effect of UNSM on the rail material. The material of the surfacehardened rail showed improved wear and rolling contact fatigue properties.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.78-83
• /
• 2001

It's required mechanical properties of in-service facilities to maintain safety operation in power plants as well as chemical plants. In this study the four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method at $630^{\circ}C$. Ultrasonic tests, tensile tests, $K_{IC}$ tests and hardness tests were performed in order to evaluate the degree of degradation of the material. The mechanical properties were decreased as degraded, but the attenuation coefficient and the harmonic generation level of a ultrasonic signal were increased. Expecially the nonlinear parameter of the signal is sensitive and will be a good parameter to evaluate the material degradation.

• 한국진공학회지
• /
• 제11권2호
• /
• pp.103-107
• /
• 2002

Metal/ferroelectric/semiconductor field effect transistors(MFSFET′s) with various gate electrodes, that are aluminum, platinum and poly-Si, using rapid thermal annealed $LiNbO_3$/Si(100) structures were fabricated and the properties of the FET′s have been discussed. The drain current of the "on" state of FET with Pt electrode was more than 3 orders of magnitude larger than the "off" state current at the same "read" gate voltage of 1.5 V, which means the memory operation of the MFSFET. A write voltage as low as about $\pm$4 V, which is applicable to low power integrated circuits, was used for polarization reversal. The retention properties of the FET using Al electrode were quite good up to about $10^3$ s and using Pt electrode remained almost the same value of its initial value over 2 days at room temperature.

• 한국화재소방학회논문지
• /
• 제24권3호
• /
• pp.66-71
• /
• 2010

화학공정에서의 안전하고 최적화된 조작과 내재되어 있는 화재 및 폭발 위험성 평가를 위해서 연소 특성치를 알아야 한다. 폭발한계는 가연성물질의 화재 및 폭발위험성을 결정하는데 주요한 특성치 가운데 하나이다. 본 연구에서, 에스테르류의 폭발하한계와 상한계에 대해 연소열을 이용하여 예측하였다. 제시된 예측식에 의한 예측값은 문헌값과 적은 오차범위에서 일치하였다. 제시된 방법론을 사용하여 다른 가연성 에스테르류의 폭발한계 예측이 가능해졌다.

• Elastomers and Composites
• /
• 제51권4호
• /
• pp.280-285
• /
• 2016

The purpose of this study is to get optimum design and operation conditions of the heating rubber roller for laminating process. The cause of performance degradation of heating rubber roller is delamination of rubber on metal tube, rubber aging due to high temperature. We measured the material properties of thermal expansion, thermal conductivity, specific heat and density and analyzed thermal distributions of rubber layer using finite element method. As a result of heat/flow analysis, the density distribution of heating coil must shorten the stabilization time by reducing the temperature deviation on the length direction at the temperature rising section after increasing the density of the area contacting with the laminate film at the center part which is an opposite of the current composition while enabling to maintain the temperature of heater to be consistent while maintaining the temperature deviation to be low when heat loss is created. Finally, we determined optimum heating method of heating rubber roller.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1988년도 추계학술대회 논문집
• /
• pp.47-49
• /
• 1988

This paper discusses dynamic properties of bubble garnet thin films. The dynamic properties considered are Gilbert damping parameters, saturation velocity, and wall mobility. The parameters are evaluated to facilitate the search for desirable garnet thin film compositions. Given bubble diameter and Q-value, the computer prints out all compositions which meet the desired requirements. The computer model determines magnetization, anisotropy, damping, velocity, mobility among others from the film compositions. The computer modeling program is described by an algorithm detailing its operation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
• /
• pp.609-612
• /
• 1999

Organic electroluminescent(EL) devices have received a great deal of attention due to their potential application as full-color displays. They are attractive because of their capability of multicolor emission, ease of fabrication, and operation at a low driving voltage. In this study, single and multiple quantum-well structures consisting of Eu(TTA)$_3$(bpy) complex well layer sandwiched between triphenyldiamine derivative (TPD) layers were fabricated and their photoluminescent electroluminescent characteristics were also investigated. Sharp emission at 616 nm has been observed from the Eu complex in multilayer, single and multiple quantum-well structures. Details on the explanation of electrical properties of these structures will be discussed.

• 선박안전
• /
• 통권24호
• /
• pp.4-20
• /
• 2008

Stainless steel 304 or stainless steel 630 types using propeller shaft of a small ship or a FRP fishing boat generally restrain localization corrosion and abrasion damage occurrence to shaft bearing or grand packing contact. In general, the residual stress which remains after welding or heat treatment in material can cause the stress concentration or localization corrosion. In case of small ship, stainless steel such as STS304 has long been used for propeller shaft. Meanwhile, crew of small ship tend to reuse damaged propeller shaft after repair by welding and performing heat treatment to save cost. However, it was found that reused propeller shaft by repair often caused troubles in ship's operation. In this study, the basic guideline for maintenance and treatment of propeller shaft are investigated. From the results of investigation, remarkable deterioration of the material properties and corrosion resistance on the welded work part was observed.