• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.370-373
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• 2011

We investigated the effects of low temperature ($500^{\circ}C$) $O_2$ annealing on the characteristics of hafnium silicate ($HfSi_xO_y$) films deposited on a Si substrate by atomic layer deposition (ALD). We found that the post deposition annealing under oxidizing ambient causes the oxidation of residual Hf metal components, resulting in the improvement of electrical characteristics such as flat band voltage shift (${\Delta}V_{fb}$) by hysteresis without oxide capacitance reduction. We suggest that post deposition annealing under oxidizing ambient is necessary to improve the electrical characteristics of $HfSi_xO_y$ films deposited by ALD.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.28-32
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• 2016

In the previous study, it is proved by numerical simulation that the baffle shaped as the porous plate installed in the inlet chambers improves the redistribution of the flow injecting to the tube bundles. In the present study, numerical simulation has been performed to investigate the effects of the flow distributors on the thermal characteristics of the shell and tube heat exchangers. The flow fields have been analysed by the three-dimensional Navier-Stokes solvers including the thermal conditions on the shell sides. The numerical results showed that the presence of the baffles improves the redistribution of the heat transfer to the tube bundles though the overall performance drop slightly on the present flow conditions.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.59-67
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• 2013

The radiation characteristics of an E-plane linear array antenna composed of inductive loaded patch antennas (ILPAs) are investigated. The radiation characteristics of an ILP array antenna are significantly improved compared to those of a conventional array antenna because the mutual coupling of an ILP array antenna is very small. The patch length of a $5{\times}2$ ILPA for the enhancement of the radiation characteristics of a 5-element E-plane linear array antenna composed of ILPAs is presented.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.73-82
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• 2010

The purpose of this study is to understand motion characteristics of older drivers during reaching seat belt compared to young drivers and to provide design guidelines in order to reduce discomfort for the elderly. The whole body kinematics of each subject was captured using 12-camera motion analysis system. Subjective ratings on discomfort levels were obtained simultaneously using a questionnaire. This paper first presents the result of motion characteristics of elderly drivers' reach motion to seat belt. Compared to young drivers, older drivers performed seat belt reach motions less efficiently and moved slower due to mostly the movement error. Older drivers also made use of reduced joint range of motion in cervical left rotation, lumbar left rotation and right shoulder adduction, which can be explained by their reduced active range of motions (AROMs). To compensate for their reduced joint range of motion, older drivers rotated pelvis more.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.127-130
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• 2011

We investigated the effects of $O_2$ annealing (i.e., temperature and time) on the characteristics of hafnium silicate ($HfSi_xO_y$) films deposited on a Si substrate by atomic layer deposition process (ALD). We found that the post deposition annealing under oxidizing ambient causes the oxidation of residual Hf metal components, resulting in the improvement of electrical characteristics (e.g., hysteresis window and leakage current are decreased). In addition, we observed the annealing temperature is more important than the annealing time for post deposition annealing. Based on these observations, we suggest that post deposition annealing under oxidizing ambient is necessary to improve the electrical characteristics of $HfSi_xO_y$ films deposited by ALD. However, the annealing temperature has to be carefully controlled to minimize the regrowth of interfacial oxide, which degrades the value of equivalent oxide thickness.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.26-33
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• 2003

Recess is a geometrical configuration shape that the exit surface of an inner injector is located at a certain length inward from that of an outer injector. It is known to have the characteristics that it can augment mixing efficiency and flame stabilization through internal mixing of propellant in it. So, various experiments, such as backlit stroboscopic photography, phase Doppler particle analyzer(PDPA) and mechanical patternator, were performed at several recess lengths to grasp its effect on the spray characteristics of spray angle, breakup length, atomization and' mixing. Recess length was normalized to dimensionless recess number and two principal mechanisms of impingement and swirl recovery were introduced to explain its influence on the spray characteristics. The effect of recess on SMD doesn't appear significantly near the recess number where mixing efficiency attains to the maximum, whereas mass distribution and mixing efficiency are changed considerably. Thus, it can be inferred that a certain optimum recess number exists, where mixing efficiency becomes the maximum.

• Journal of Korean Elementary Science Education
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• v.27 no.2
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• pp.144-157
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• 2008

The purpose of this study was to analyse the influence of mother's characteristics on elementary school students' attitudes toward science. Elementary school students (N=667) and their mothers (N=681) were selected from three other regions, big city, small city, and country. Attitudes toward science and supports for scientific activities were measured by two kinds of instruments. The instrument for the measurement of attitudes toward science includes three scales: cognition about value of science, affection toward science & science learning, and cognitive participation in scientific activities. And the instrument to measure parents' support for scientific activities includes two scales: indirect support and direct support. This research showed that mothers' various characteristics resulted in a difference in students' attitudes toward science. And there were positive correlations between students' attitudes toward science and their mothers' attitudes toward science and support for scientific activities. Also mothers' attitudes toward science and support for scientific activities affected students' attitudes. Especially, mothers' personal interest in science and her mental and physical supports for children's scientific activities had a close relation with students' attitudes toward science.

• Journal of the Korean housing association
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• v.17 no.6
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• pp.9-18
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• 2006

The purpose of this study is to find out the selection of housing type and the characteristics of dwelling of foreign students' residence in order to provide some information for better housing plans for foreign students in Korea. To analyze characteristics of dwelling, a questionnaire survey was conducted with 171 students who study in the university located in seoul, Korea. The results are summarized as follows: Overseas students in Korea can get from their house to school within 30 minutes and they spend more than 9 hours a day at home on average. Housing is one of the most important factors for oversea students. For the dormitory group, they chose their houses based on fee, distance from the school, stability, etc. The lodging group, chose their houses based on fee, distance from school, and Korean culture experience. The Go-Si-Won group chose their houses based on fee, distance from the school, privacy and so on.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1025-1035
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• 2016

Luenberger observer (LO)-based sensorless multi-loop control of a converter requires an iterative trial-and-error design process, considering that many parameters should be determined, and loop gains are indirectly related to the closed-loop characteristics. Robust H∞ control adopts a compact sensorless controller. The algebraic Riccati equation (ARE)-based and linear matrix inequality (LMI)-based H∞ approaches need an exhaustive procedure, particularly for a low-order controller. Therefore, in this study, a novel robust H∞ synthesis approach is proposed to design a low-order sensorless controller for boost converters, which need not solve any ARE or LMI, and to parameterize the controller by an adjustable parameter behaving like a "knob" on the closed-loop characteristics. Simulation results show the straightforward closed-loop characteristics evaluation and better dynamic performance by the proposed H∞ approach, compared with the LO-based sensorless multi-loop control. Practical experiments on a digital processor confirmed the simulation results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.410-411
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• 2007

To investigate the ZnO LED which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF magnetron sputtering system. The p-type ZnO thin film, fabricated by means of the ampoule-tube method, was used to make the ZnO p-n junction, and its characteristics was analyzed. The ampoule-tube method was used to make the p-type ZnO based on the As diffusion, and the hall measurement was used to confirm that the p-type is formed. the current-voltage characteristics of the ZnO p-n junction were measured to confirm the rectification characteristics of a typical p-n junction and the low leakage voltage characteristics. Analysis of ZnO LED V-I curve will provide a very useful technology for producing the UV ZnO LED and ZnO-based devices.