• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.175-175
• /
• 1999

Circumventing problems lying in the conventional lithographic techniques, we devised a new method for the fabrication of nanometer scale metal wires inspired by the unique characteristics of carbon nanotubes (CNTs). Since carbon nanotubes could act as masks when CNT-coated thin Au/Ti layer on a SiO2 surface was physically etched by low energy argon ion bombardment 9ion milling), Au/Ti nano-wires were successfully formed just below the CNTs exactly duplicating their lateral shapes. Cross-sectional analysis by transmission electron microscopy revealed that the edge of the metal wire was very sharply developed indicating the great difference in the milling rates between the CNTs and the metal layer as well as the good directionality of the ion milling. We could easily find a few nanometer-wide Au/Ti wires among the wires of various width. After the formation of nano-wires, the CNTs could be pushed away from the metal nano-wire by atomic force microscopy, The lateral force for the removal of the CNTs are dependent upon the width and shape of the wires. Resistance of the metal nano-wires without the CNTs was also measured through the micro-contacts definted by electron beam lithography. since this CNT-based lithographic technique is, in principle, applicable to any kinds of materials, it can be very useful in exploring the fields of nano-science and technology, especially when it is combines with the CNT manipulation techniques.

• Journal of The Korean Astronomical Society
• /
• v.40 no.4
• /
• pp.133-135
• /
• 2007

A survey project of TRAO with the fifteen beam array receiver system is presented. A multibeam array receiver system has been purchased from FCRAO, and is being installed on TRAO 14m telescope. The target region of the survey is from ${\iota}=120^{\circ}{\sim}137^{\circ},\;b=-1^{\circ}{\sim}+ 1^{\circ}$, and velocity resolution would be 1 km/sec after smoothing from the original resolution of $0.64km\;s^{-1}$ in the transition of J = 1-0 of $^{13}CO$. The survey region is a part of the $^{12}CO$ Outer Galaxy Survey(OGS), and would be an extension of the Bell Laboratories $^{13}CO$ Galactic Plane Survey. By combining with the existing $^{12}CO$ database of the Outer Galaxy Survey, we will derive physical properties of identified molecular clouds and will conduct and statistical analysis of the Outer Galalxy molecular clouds. Reduction process and analysis methods will be introduced.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1697-1698
• /
• 2008

PLS(Pohang Light Source) is 2.5 Gev synchrotron radiation source in Pohang, Korea, which is under operation since 1995. The hardware and software of the old BPM(Beam Position Monitor) data acquisition system for the PLS storage ring was completely upgraded to increase its performance and stability. The new BPM data acquisition system is based on VME-based EPICS (Experimental Physics and Instrument Control System) IOC system. We used 16-bit resolution analog-to-digital conversion board to digitize analog BPM signals. We developed a data average software to average raw BPM data using reflective memory board. We also developed device drivers for VME I/O boards used, IOC database for PV's(Process Variables). The new BPM data acquisition system is currently running for routine operation with good performance and stability. In this paper, we present the hardware and software of the new BPM data acquisition system DTL water skid cooling system and Resonant Control Cooling.

• Smart Structures and Systems
• /
• v.3 no.4
• /
• pp.423-437
• /
• 2007

The empirical mode decomposition (EMD) method is well-known for its ability to decompose a multi-component signal into a set of intrinsic mode functions (IMFs). The method uses a sifting process in which local extrema of a signal are identified and followed by a spline fitting approximation for decomposition. This method provides an effective and robust approach for decomposing nonlinear and non-stationary signals. On the other hand, the IMF components do not automatically guarantee a well-defined physical meaning hence it is necessary to validate the IMF components carefully prior to any further processing and interpretation. In this paper, an attempt to use the EMD method to identify properties of nonlinear elastic multi-degree-of-freedom structures is explored. It is first shown that the IMF components of the displacement and velocity responses of a nonlinear elastic structure are numerically close to the nonlinear normal mode (NNM) responses obtained from two-dimensional invariant manifolds. The IMF components can then be used in the context of the NNM method to estimate the properties of the nonlinear elastic structure. A two-degree-of-freedom shear-beam building model is used as an example to illustrate the proposed technique. Numerical results show that combining the EMD and the NNM method provides a possible means for obtaining nonlinear properties in a structure.

• The Journal of the Acoustical Society of Korea
• /
• v.20 no.6
• /
• pp.46-50
• /
• 2001

This paper proposes a new recognition time reduction algorithm Score-Cache technique, which is applicable to the HMM-base speech recognition system. Score-Cache is a very unique technique that has no other performance degradation and still reduces a lot of search time. Other search reduction techniques have trade-offs with the recognition rate. This technique can be applied to the continuous speech recognition system as well as the isolated word speech recognition system. W9 can get high degree of recognition time reduction by only replacing the score calculating function, not changing my architecture of the system. This technique also can be used with other recognition time reduction algorithms which give more time reduction. We could get 54% of time reduction at best.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.10 no.1
• /
• pp.57-61
• /
• 1980

In dental roentgenograph it is of mutual benefit to the patient and the dentist to use the minimum amount of radiation capable of producing roentgenograms with maximum interprtive informations. Recent increases in the number of diagnostic x-ray examinations made in this country have caused attention to be paid to the quantity of radiation delivered to the population and operator. The purposes of this study was to assess the quality of dental x-ray units, the amount of films, the average processing procedures and the radiation protection methods in korea. The results were as following: 1. Most of radiation generating system were used in low voltage such as 60Kvp, 10㎃. 2. High sensitivity films such as 'D' group of Kodak or Rinn were mainly used and average 14.7 films used per weeks. 3. Some dentists practiced visual processing technic in simple dark room, and others used instant films. 4. 68.26% of patient held the film themselves, but 27.30% were assisted by dentists film holding. 5. In radiation protection method, 7.85% of dentists had protection equipments such as protective barrier, 2.73% wore protective apron, 27.9% made it a rules to avoid beam, and 7.51% used to maintain a distance from the radiation source.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1098-1102
• /
• 2003

Vacuum vessel of the KSTAR(Korea Superconducting Tokamak Advanced Research) tokamak is a fully welded structure with D-shaped cross-section. According to the requirements of the physics design, sixteen horizontal ports, sixteen slanted ports, sixteen baking and cooling ports, and twenty-four top and bottom vertical ports are designed for the diagnostics, plasma heating, vacuum pumping, and baking and cooling. Bellows on these ports are used for flexible components to absorb the relative displacement due to the vacuum vessel thermal expansion and the electromagnetic force between the vacuum vessel and the cryostat ports. Fatigue strength evaluation was performed to decide the dimension of the bellows. In order to assure the quality of the bellows, a prototype bellows for the neutral beam injection port has been fabricated and tested prior to main fabrication. It was conformed that the prototype bellows has sufficient fatigue strength and vacuum reliability in the expected load conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.251-254
• /
• 2001

In this paper, we analyzed the properties change of electric wire when the thermal stress was applied to NFR-8 and FR-PVC 600[V] wire. Messurement is made of the attenuation of a light beam by smoke accumulating with in a closed chamber due to nonflaming pyrolytic decomposition and flaming combustion. Results are expressed in terms of specific optical density which is derived from a geometrical factor and the measured optical density a measurement characteristic of the concentration of smoke. Referenced documents were ASTM E662 standard test method for specific Ds genalated by solid materials. The furnace control system shall maintain the required irradiance level under steady-state condition with the chamber door closed of $2.5{\pm}0.04[w/cm^{2}]$ for 20 min. According to the results of the smoke density analysis of NFR-8 and FR-PVC the highest decomposition flaming smoke density range of NFR-8 and FR-PVC were 25.2 to 37.5 and 51.1 respectively. Nonflaming smoke density range of NFR-8 and FR-PVC were 100.4 to 112.2 and 126.5 to 398.8. The amount of carbon monoxide generated was found to be much higher in FR-PVC decomposition than in NFR-8 due to incomplete combustion of FR-PVC which has high content of carbon in compound.

• Proceedings of the KOSOMBE Conference
• /
• v.1998 no.11
• /
• pp.74-75
• /
• 1998

The present study employs weak shock theory and bio-heat transfer function to predict the temperature rise due to nonlinear propagation of high amplitude ultrasound. The theory shows that, for the focused ultrasound which is assumed to have an gaussian beam profile and has the focal intensity of $1000W/cm^2$, the temperature rise of liver tissue exposed for 1 second to the energy lost during nonlinear propagation goes up to about $30^{\circ}C$. This indicate that it is necessary to consider the nonlinear propagation induced heating enhancement when setting exposure condition of high intensity focused ultrasound used for cancer thermotherapy.

• Journal of Korean Society of Steel Construction
• /
• v.15 no.5 s.66
• /
• pp.551-559
• /
• 2003

In steel frames, the analysis and design techniques are based on either idealized fixed or pinned connections. In this case, it has the advantage that the structural analysis and the design procedure were simplified, but there could be given different results of analysis between the real steel frame connections and the idealized fixed and pinned connection. This is because the real connections would be analyzed by semi-rigid, and have some transfer of moment and rotational constraint about the loads. In this study, structural analysis program with considered connections that have joint rigidity of fixed, pinned and semi-rigid, was developed. Then, the effects of joint rigidity on strength and displacement. in steel frames subjected to lateral forces and axial forces, were investigate, and the results were compared with those of the Midas Gen. w program.