• The korean journal of orthodontics
• /
• v.24 no.3 s.46
• /
• pp.521-534
• /
• 1994

The purpose of this study was to compare the differences in measurements between cephalometric radiographs and digigraphs of Dolphin Imaging System. 26 Korean adult male and 24 adult female with normal occlusion were selected. For each subject lateral cephalogram was taken. Digitizing with Digigraph Work Station of Dolphin in System. was performed as well. 50 tracings and 50 digigraphs were analyzed with Yonsei, Ricketts, Burstone analyses. The comparable measurements between tracing group and digigraph group were statistically analyzed. The results were as follows: 1. 13 of 64 comparable measurements did not show any statistically significant difference (P>0.05) between tracing group and digigraph group. 2. Three of the measurements with FH plane as a reference plane did not show any statistically insignificant difference. All measurement with SN plane as a reference plane showed statistically significant difference(p<0.05). 3. The measurements which showhed no statistically significant difference were mostly short distance linear measurements while most of the angular measurements showed statistically significant difference(p<0.05).

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.42 no.4 s.334
• /
• pp.53-60
• /
• 2005

This work Proposes and describes an LCD backlight driver IC using a voltage feedback circuit which improves the brightness uniformity. The proposed circuit controls the brightness of a backlight by amplifying of sampling voltage at a lamp. To keep the uniformity of brightness, the circuit has a reference lamp. The output voltage of the reference lamp is supplied commonly to each lamp that reduces a resistance deviation of the lamps. As a result, the proposed circuit shows brightness uniformity improvement of about $40\%$ compared to the conventional ones.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.6
• /
• pp.440-443
• /
• 2010

We report a top-down approach based on atomic force microscopy (AFM) local anodic oxidation for the fabrication of the nano-pattern field effect transistors (FETs). AFM anodic oxidation is relatively a simple process in atmosphere at room temperature but it still can result in patterns with a high spatial resolution, and compatibility with conventional silicon CMOS process. In this work, we study nano-pattern FETs for various cross-bar distance value D, from ${\sim}0.5\;{\mu}m$ to $1\;{\mu}m$. We compare the optical characteristics of the patterned FETs and of the reference FETs based on both 2-dimensional simulation and experimental results for the wavelength from 100 nm to 900 nm. The simulated the drain current of the nano-patterned FETs shows significantly higher value incident the reference FETs from ${\sim}1.7\;{\times}\;10^{-6}A$ to ${\sim}2.3\;{\times}\;10^{-6}A$ in the infrared range. The fabricated surface texturing of photo-transistors may be applied for high-efficiency photovoltaic devices.

• Journal of the korean Society of Automotive Engineers
• /
• v.14 no.5
• /
• pp.95-106
• /
• 1992

Active control of acoustic noise is an application area of adaptive digital signal processing with increasingly interest along the last year. This work studies the implementation of the multichannel LMS filter and the application of this algorithm for the reduction of the noise inside a vechicle cabin using a number of 'secondary sources' drived by adaptive filtering of a reference noise source. Firstly, we propose the use of an adaptive method for the time-varient optimal convergence factor. Secondly, we propose the use of adaptive delayed inverse model to estimate the elastic-acoustic transfer function presented in vechicle cabin. The original, primary source is often periodic, with a known fundamental frequency. A suitably filtered reference signal can thus be used to drive the secondary sources. An algorithm is presented for adapting the coefficients of an FIR filter feeding such a secondary source in such a way as to minimize the output of a suitably placed microphone. In this algorithm, the coefficients of adaptive filter driving an array of secondary sources can be adapted to minimize the sum of the squares of the outputs of a number of error microphones. The multichannel LMS algorithm displays that such an algorithm is considered suitable to used for the global suppression of noise in vehicle cabin.

• Journal of Astronomy and Space Sciences
• /
• v.16 no.1
• /
• pp.41-52
• /
• 1999

Near-earth space is composed of plasmas which embed a number of plasma waves. Space plasmas consist of electrons and multi-ion that determine local wave propagation characteristics. In multi-ion plasmas, it is difficult to find out analytic solutions from the dispersion relation in general. In this work, we have developed a model with an arbitrary magnetic field and density as well as multi-ion plasmas. This model allows us to investigate how plasma waves behave when they propagate along realistic magnetic field lines, which are assumed by IGRF(International Geomagnetic Reference Field). The results are found to be useful for the analysis of the in situ observational data in space. For instance, if waves are assumed to propagate into the polar region, from the equatorial region, our model quantitatively show how polarization is altered along earth travel path.

• International Journal of Control, Automation, and Systems
• /
• v.1 no.2
• /
• pp.243-251
• /
• 2003

In this paper, a new model for mobile soccer robot, a type of linear system, is presented. A controller, consisting of two loops the one of which is the inner state feedback loop designed for stability and plant be well conditioned and the outer loop is a well-known PI controller designed for tracking the reference input, is suggested. Because the plant, the soccer robot, is parameter dependent, it requires the controller to be insensitive to the parameter variation. To achieve this objective, the pole-sensitivity as a pole-variation with respect to the parameter variation is defined and design algorithms for state-feedback controllers are suggested, consisting of two matrices one of which is for general pole-placement and other for parameter insensitive. This paper shows that the PI controller is equivalent to the state feedback and the cost function for reference tracking is equivalent to the LQ cost. By using these properties, we suggest a tuning procedure for the PI controller. We that the control algorithm in this paper, based on the linear system theory, is well work by simulation, and the LPD system modeling and control are more easy treatment for soccer robot.

• Structural Engineering and Mechanics
• /
• v.52 no.4
• /
• pp.701-721
• /
• 2014

In the assessment of existing RC buildings, the reliable appraisal of the compressive strength of in-situ concrete is a fundamental step. Unfortunately, the data that can be obtained by the available testing methods are typically affected by a high level of uncertainty. Moreover, in order to derive indications about the degradation and ageing of the materials by on site tests, it is necessary to have the proper terms of comparison, that is to say, to know the reference data measured during the construction phases, that are often unavailable when the building is old. In the cases when such a comparison can be done, the in situ strength values typically turn out to be lower than the reference strength values (tests performed on taken samples during the construction). At this point, it is crucial to discern and quantify the specific effect induced by different factors: ageing of the materials; poor quality of the placement, consolidation or cure of the concrete during the construction phases; damage due to drilling. This paper presents a procedure for correlating the destructive compressive tests and non-destructive tests (ultrasonic pulse velocity tests) with the data documenting the compressive strength tested during the construction phases. The research work is aimed at identifying the factors that induce the difference between the in-situ strength and cubes taken from the concrete casting, and providing, so, useful information for the assessment procedure of the building.

• Journal of the Korean Chemical Society
• /
• v.7 no.1
• /
• pp.58-64
• /
• 1963

Authors propose a new technique using polyethylene film instead of sodium chloride window as a cell material. Nujol mulls, liquids and aqueous solutions are sandwitched between two pieces of polyethylene film which are held between cardboards. Ordinary lead or stainless steel spacers could be used if exact cell thickness is desired. A more elaborate cell can be assembled by injecting samples between two pieces of polyethylene film which are placed between sodium chloride windows of ordinary demountable liquid cell. The absorption bands due to polyethylene and Nujol are compensated by placing the polyethylene film of suitable thickness in the reference beam. The absorption bands due to solvents such as water can also be compensated by the polyethylene film cell sandwitched solvent of suitable thickness in the reference beam. This method would be a simple new technique. Especially this technique may offer a new helpful way for the investigation of the state of substances in aqueous system. Using this technique, authors have observed the appearance of an absorption bands at 3.2 micron, in the spectrum of phenol in aqueous solution, that is absent in the spectrum of phenol in benzene solution. The same absorption band also has been observed in the spectra of aqueous formaldehyde solution and aqueous polyvinyl alcohol solution, where the absorption bands due to polyethylene and water are compensated. Although it may be regarded that this absorption band is related to the intermolecular interaction between water and the solute having OH group, that is hydrogen bonding. The exact assignment of this absorption band is out of this work.

• International Commerce and Information Review
• /
• v.9 no.2
• /
• pp.327-350
• /
• 2007

A single window platform must be successfully established by implementing CDM/UCR in WCO and UNeDocs in UN/CEFACT, which is part of the framework of standards for secure and facilitate global trade. Core success factors in single window platform for international trade depend on political innovative capacity, advanced leadership of high ranking officials and departments in charge, effective collaborations between the ministries and offices concerned which are supported by supreme executives, self-controlled coordinations between users, convenience and access availability to users, promotion and marketing, identification on predictive impediments, financial raising and revenue model payable, communication's strategy, valid legal basis etc. To settle a stable ubiquitous e-trade platform, firstly, procedures and practices of customs clearance which different from one another mutually must be standardized globally. Secondly, the international standard electronic data exchanges must be introduced to facilitate and simplify customs clearing procedures by holding administrative informations in common between public institutions. thirdly, cooperative work model must be accepted with enhancing outsourcing business between reference groups (export-import firms and IT service providers).

• International Journal of Fluid Machinery and Systems
• /
• v.7 no.3
• /
• pp.86-93
• /
• 2014

This paper describes performance enhancement of a regenerative blower used for a 20 kW fuel cell system. Two design variables, bending angle of an impeller and blade thickness of an impeller tip, which are used to define an impeller shape, are introduced to enhance the blower performance. Internal flow of the regenerative blower has been analyzed with three-dimensional Navier-Stokes equations to obtain the blower performance. General analysis code, CFX, is introduced in the present work. SST turbulence model is employed to estimate the eddy viscosity. Throughout the numerical analysis, it is found that the thickness of impeller tip is effective to increase the blower efficiency in the present blower. Pressure is successfully increased up to 2.8% compared to the reference blower at the design flow condition. And efficiency is also enhanced up to 2.98 % compared to the reference one. It is noted that low velocity region disturbs to make strong recirculation flow inside the blade passages, thus increases local pressure loss. Detailed flow field inside the regenerative blower is also analyzed and compared.