• Proceedings of the ESK Conference
• /
• 1997.10a
• /
• pp.313-319
• /
• 1997

There is currently a focus on usability of interactive computer software. Previous research in software ergonomics has indicated the importance of evaluating the usability of software user interfaces. Software developers, interface designers or human foctors engineers often confront the task of comparative evaluation among systems, versions or interface designs. This study presents a structured model for comparative evaluation of user interface designs using usability criteria and measures. The proposed model consists of twomain phases : the prescreening phase ad the evaluation phase. The first phase involves expert judgment-based approach with qualitative criteria. The prescreening phase uses absolute measurement analytic hierarchy process to filter possible altermative interfaces to a reasonable subset. The second phase involves user-based approach such as usability testing, with quantitative criteria. The objective of the evaluation phase is to evaluate a subset of altermatives using objective measures. A set of criteria and measures for evaluating the usability of computer software designs is presented. The proposed model provides practitioners with a structured approach to select the best interface based on usability criteria and measures.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.1
• /
• pp.77-82
• /
• 2010

An analytical method for robust design of the multi-loop proportional-integral (PI) controller is proposed for various types of multi-delay processes. On the basis of the direct synthesis and generalized IMC-PID approach, the analytical tuning rules of the multi-loop PI controller are firstly derived for achieving the desired closed-loop response, and the structured singular value synthesis is then utilized for the tradeoffs between the robust stability and performance by adjusting only one design parameter (i.e., the closed-loop time constant). To verify the superiority of the proposed method, the simulation studies have been conducted on a wide variety of multivariable processes. The multi-loop PI controller designed by the proposed method shows a fast, well-balanced and robust response with the minimum integral absolute error (IAE) in compared with other renowned methods.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.4
• /
• pp.18-26
• /
• 1996

In this paper we propose a new dual structured tap selection algorithm for voice echo canceller in digital cellular communication system, investigating adaptive filtering algorithms for echo cancellation in long distance telephony or mobile communication system. The proposed algorithm has a two-stage processing structure that after a dispersive region in an impulse response of an echo path is found out, the tap coefficients of a short length filter are adjusted adaptively for the region, because the impuse response has a very little portion of the dispersion. Simulation results show that the proposed algorithm with 256 taps gives a performance of convergence speed superior to both full-tap normalized least mean with 256 taps gives a performance of convergence speed superior to both full-tap normalized least mean square (NLMS) and a scrub taps waiting in a queue (STWQ) algorithms by about eighty per cent, also to a tap selection algorithm by about twenty per cent. And the resutls diplay that if the more tap coefficients are used due to a long delayed dispersive zone, the proposed algorithm produces the better performance.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.18 no.1
• /
• pp.1-4
• /
• 2008

The growth of composite-structured Nd:$GdVO_4$ single crystal rods by the double die EFG method is reported. Two crucibles are combined with an outer and inner die for ascending of different melt. The composite-structured Nd:$GdVO_4$ single crystal rods with a length of 50 mm and an outer diameter of 5 mm including of inner Nd-doped core region with diameter 3 mm were grown successfully. Nd distribution in the, radial direction has graded profile from result of EPMA. Absorption coefficient in the core region at 808 nm was $42cm^{-1}$. Finally, we demonstrated the laser oscillation using our composite crystal and 2-W output was obtained.

• Journal of Periodontal and Implant Science
• /
• v.45 no.1
• /
• pp.2-7
• /
• 2015

A fundamental problem in analyzing complex multilevel-structured periodontal data is the violation of independency among the observations, which is an assumption in traditional statistical models (e.g., analysis of variance and ordinary least squares regression). In many cases, aggregation (i.e., mean or sum scores) has been employed to overcome this problem. However, the aggregation approach still exhibits certain limitations, such as a loss of power and detailed information, no cross-level relationship analysis, and the potential for creating an ecological fallacy. In order to handle multilevel-structured data appropriately, mixed effects models have been introduced and employed in dental research using periodontal data. The use of mixed effects models might account for the potential bias due to the violation of the independency assumption as well as provide accurate estimates.

• Journal of the Korean Home Economics Association
• /
• v.33 no.3
• /
• pp.101-112
• /
• 1995

This study examines a multivariate model of the effect of life events and transitions, intrafamily strain, marital adjustment, and appraisal on family well-being across the family system types. Data from 356 families were analysed SAS program. The result show that life events had no direct on family well-being but they intensified intrafamily strain. Family strain, in turn, negatively affected marital adjustment in flexible-connected families and structured-seperated families and perceived well-being in flexible-seperared, flexible-connected and structured-seperated families. marital adjustment were positively related to well-being in flexible-connected families. In flexible-connected families, marital adjustment seems to buffer the effect of intrafamily stain on well-being. The result also suggested that a combination of cohesion and adaptability level may explain differencies in the family's response to de4mands.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.30B no.11
• /
• pp.93-101
• /
• 1993

The transfer function of vector-controlled induction motor is represented along with both unstructured and structured uncertainty such as the error of rotor time constant and current ripple. The low-pass-filter behavior of a magnetizing inductance gets rid of unstructured uncertainty in the transfer function. The robust controller to compensate variation of the transfer function is designed using simple P-I linear controllers. The coefficients of speed PI controller are determined from an overshoot and a rising time of system and the coefficients of model-following PI controller are obtained using the solution of Riccati equation of LQR control in the state space equation of the error system. Experimental results with the DSP-based model-following robust controller are shown a good robustness against the structured uncertainty of the motor.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.5
• /
• pp.1009-1011
• /
• 2009

Nano-structured conducting polypyrroles were synthesized in the ionic liquids (ILs) based on 1-alkyl-3-methylimidazolium family with tetrachloroferrate as an anion ($C_n\;mim\;[FeCl_4]\;with\;n\;=\;4,\;8,\;and\;12$). The polypyrrole nanostructures synthesized in ILs were formed as spherical shapes. For ionic liquids with alkyl side chain length $C_4,\;C_4\;mim\;[FeCl_4]$, the size of particles was ranged around 60-nm with a relatively narrow size distribution. As the length of alkyl chain increases, the particle sizes become larger and their distributions become wider. The self-assembled local structures in the solvent ionic liquids are likely to serve as templates of highly organized nano-structured polymers. The length of the alkyl chain in ionic liquids seems to affect these local structures.

• Journal of the Korean housing association
• /
• v.15 no.1
• /
• pp.141-152
• /
• 2004

Most elderly victims of senile dementia in Korea are cared for at home. This creates hardship for their families. Recent research suggests that the physical environment can affect the treatment of dementia. In light of these findings, a prudent approach to the design of the housing environment of family with dementia sufferers is advisable. This study aims to determine the design factors that need to be considered for the housing environment of dementia, particularly for those suffering from Alzheimer's or Cerebrovascular dementia. For this study, and in-depth qualitative investigation method was employed. Principal caregivers were interviewed using various investigative tools, including objective measures, structured and non-structured questionnaires. The investigation results suggest that the need for housing environment improvement varies with the severity and type of dementia. The housing needs in this study, is expected to promote a focus on improved design management for the environment and housing of dementia and their families. The results also suggest the establishment of a welfare policy for senile dementia victims and their families.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.552-554
• /
• 2005

This paper deals with a simple structured voltage disturbance generator for power quality improving devices. The proposed generator can be applied to the performance test of custom power devices. Voltage sag, swell, outage, unbalance and phase jump after outage are provided by the generator. The improving phase jump operating principle of the generator is described and analysed. The usefulness of the generator is verified through simulation.