• Nuclear Engineering and Technology
• /
• v.48 no.3
• /
• pp.795-798
• /
• 2016

Transmission X-ray tubes based on carbon nanotube have attracted significant attention recently. In most of these tubes, tungsten is used as the target material. In this article, the well-known simulator Geant4 was used to obtain some of the tungsten target parameters. The optimal thickness for maximum production of usable X-rays when the target is exposed to electron beams of different energies was obtained. The linear variation of optimal thickness of the target for different electron energies was also obtained. The data obtained in this study can be used to design X-ray tubes. A beryllium window was considered for the X-ray tube. The X-ray energy spectra at the moment of production and after passing through the target and window for different electron energies in the 30-110 keV range were also obtained. The results obtained show that with a specific thickness, the target material itself can act as filter, which enables generation of X-rays with a limited energy.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.8
• /
• pp.1225-1238
• /
• 2004

The present study has been performed for obtaining the melting heat transfer enhancement characteristics of water mixture slurries of plural microcapsules having different diameters encapsulated with solid-liquid phase change material(PCM) flowing in a pipe heated under a constant wall heat flux condition. In the turbulent flow region, the friction factor of the present PCM slurry was to be lower than that of only water flow due to the drag reducing effect of the PCM slurry. The heat transfer coefficient of the PCM slurry flow in the pipe was increased by both effects of latent heat involved in phase change process and microconvection around plural microcapsules with different diameters. The experimental results revealed that the average heat transfer coefficient of the PCM slurry flow was about 2～2.8 times greater than that of a single phase of water.

• Proceedings of the KSME Conference
• /
• 2001.06a
• /
• pp.663-668
• /
• 2001

Strength evaluation was carried out for the cylinder liner of a low-speed marine engine. Calculation of temperature distribution, nonlinear structural analysis, material test, and fatigue strength evaluation are briefly introduced in this paper. Strengths of five liner models are compared, and the effect of materials experiencing different heat treatment is evaluated. Structural analysis including boundary and material non-linearities was performed for axisymmetric liner models. High cycle (fatigue limit) and low cycle (fatigue life) fatigue analyses are carried out. As results, localized high stress was occurred next to the mount line. Maximum stresses are varied significantly with respect to different liner models and different materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.206-209
• /
• 1994

This paper has been researched bondability of electronic devices, such as lead frame and thick film of Ag/Pd on an alumina substrate by different heat sources. To obtain the bonds with high quality, it is very important to control both the thermal distribution of the bonds and it stability, because electronics components is consist of different materials. Therefore, this paper clarifies not only heat mechanism of micro parallel gap resistance bonding method and pulse heat tip bonding method but also investigates selection of heat sources with micro-electronic materials for bonding. Finally, it is realzed fluxless bonding process with filler metal such as plating layers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.3
• /
• pp.215-222
• /
• 2001

Polyaniline-Camphorsulfonic Acid Emeraldine Salt(PANI-CSA ES) was prepared by doping Polyaniline Ermeralidine Base(PANI EB) with DL-10-Camphorsulfonic Acid(CSA). PANI-CSA ES was solved in an organic solvent by ultrasonification for different periods of time and its surface resistivity was measured. Several PANI-CSA ES solutions solved in different organic solvents were prepared and their surface resistivities were measured. Thermal stability of film casted with PANI-CAS ES solution in m-cresol was estimated by measuring its surface conductivity and the content of this moisture and organic solvents. PANI-CSA ES was blended with different polymeric binders to improve its physical properties and the surface resistivities of several kinds of PANI-CSA ES blends were measured as a function of the content of PANI-CSA ES. PANI-CSA ES polymerized by 1-step oxidative polymerization was prepared and its surface resistivity was measured.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.506-512
• /
• 1997

Ultrasonic knives have been successfully used for the surgery of many medical fields. However, the conventional ultrasonic knives for surgical operation cannot be controlled its resonant frequency. So if the material to cut has different characteristic impedance then different ultrasonic knife will be needed. Because the optimum driving frequency of ultrasonic knife is different by characteristic impedance of material. In this work, using a frequency variable ultrasonic transducer made of multi-layered PZT vibrator, a frequency controllable ultrasonic knife will be suggested. The design and computation principles will be also derived. For this work, firstly, the characteristics of this ultrasonic knife will be analyzed by transmission line model equivalent circuit, and the free admittance characteristics and vibrational velocity distributions will be obtained. Secondly, we will design and make the frequency controllable electrical oscillator for driving this ultrasonic knife.

• Smart Structures and Systems
• /
• v.6 no.8
• /
• pp.975-989
• /
• 2010

Based on the theory of piezo-elasticity, the paper obtains the exact solutions of functionally graded piezoelectric hollow cylinders with different piezoelectric parameter $g_{31}$. Two kinds of piezoelectric hollow cylinders are considered herein. One is a multi-layered cylinder with different parameter $g_{31}$ in different layers; the other is a continuously graded cylinder with arbitrarily variable $g_{31}$. By using the Airy stress function method with plane strain assumptions, the exact solutions of the mechanic and electrical components of both cylinders are obtained when they are subjected to external voltage (actuator) and pressure (sensor), simultaneously. Furthermore, good agreement is achieved between the theoretical and numerical results, and useful conclusions are given.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.506-507
• /
• 2008

Organic field-effect transistors (OFETs) are of interest for use in widely area electronic applications. We fabricated a copper phthalocyanine (CuPc) based field-effect transistor with different metal electrode. The CuPc FET made a top-contact type and the substrate temperature was room temperature. The source and drain electrodes were used an Au and Al materials. The CuPc thickness was 40nm, and the channel length was $50{\mu}m$, channel device was width was 3mm. We observed a typical current-voltage (I-V) characteristics in CuPc FET with different electrode materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.04b
• /
• pp.12-13
• /
• 2008

Organic field-effect transistors (OFETs) are of interest for use in widely area electronic applications. We fabricated a copper phthalocyanine (CuPc) based field-effect transistor with different metal electrode. The CuPc FET device was made a top-contact type and the substrate temperature was room temperature. The source and drain electrodes were used an Au and Al materials. The CuPc thickness was 40nm, and the channel length was $50{\mu}m$, channel width was 3mm. We observed a typical current-voltage (I-V) characteristics in CuPc FET with different electrode materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1988.10a
• /
• pp.95-97
• /
• 1988

The instability of MOS devices is mainly caused by the oxide charges, and as the need to develop the gate metal grows researches for various new metal gate have been performed, and in these researches, the difference work function existing between the metal and the semiconductor should be considered. Here int his paper, the device is made by the sputtering and the LPCVD method using pure Al, compound metal. poly-si, as a gate metal, the result of the research was shown that the work function difference from using different gate metals effects on the flatband voltage shift. This means we can infer that the threshold voltage adjustment is possible by using different gate metals and this whole mechanism makes the devices behavior more stable.