• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.449-455
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• 2015

In this study we propose a new photonic crystal fiber (PCF) design that simultaneously offers broadband single-mode operation, high birefringence, and large normal dispersion in the optical-communication wavelength regime. The waveguide is based on a hybrid square-lattice PCF (HS-PCF) that has circular air holes of two different diameters alternating in the cladding, plus a pure silica defect at the center. The optical properties of the guided modes are analyzed numerically by the finite-element method (FEM) with a perfectly matched layer as the boundary condition. The optimized HS-PCF has a dispersion coefficient of $-601.67\;ps\;nm^{-1}\;km^{-1}$ and a high birefringence of $1.025{\times}10^{-2}$ at $1.55{\mu}m$. In addition, over the S+C+L+U wavelength bands the proposed HS-PCF with ultraflat birefringence with a slope on the order of $10^{-5}$.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.503-507
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• 2005

Microstructure and wear behavior of A1203-based nanocomposites with Cu and Ni-Co dispersions were investigated. $Al_2O_3/Cu$ and $Al_2O_3/Ni-Co$ nanocomposites were fabricated by hydrogen reduction and sintering method using metal oxide and metal nitrates. The nanocomposites showed increased mechanical properties compared with monolithic $Al_2O_3$. In particular, high toughness and hardness were measured for the $Al_2O_3/Ni-Co$ nanocomposite consolidated by spark plasma sintering. A minimum value of wear coefficient comparable to the monolithic $Al_2O_3$ was obtained for $Al_2O_3/Ni-Co$ nanocomposite. Wear behavior is discussed in terms of microstructure and mechanical properties of nanocomposites

• Journal of Sasang Constitutional Medicine
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• v.24 no.3
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• pp.42-49
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• 2012

Objectives This study aimed to assessing the performance of Sasang constitutional analysis Tool (SCAT) for Chinese as one of method to diagnose Sasang Constitution and evaluating the possibility of applying SCAT to foreign people. Methods This cross-sectional study was approved by IRB (Independent Review Board) at J Hospital in Yanbian. Informed consent to take part in the study was obtained from each of the participants. The performance of SCAT was assessed through Kappa coefficient and the concordance rate between SCAT and expert diagnosis. Results The concordance rate between SCAT and expert was 61.1% in total and the Kappa was 0.408. When the constitutional probability increased, the concordance rate and Kappa showed a increasing tendency. The concordance rate of Chosun race was 62.1% and others 60.7%. Conclusions SCAT, as Sasang constitutional diagnostic supporting system, may help the expert to diagnose Sasang constitution in Yanbian region.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1246-1249
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• 1994

Thin amorphous film of $a-Se_{75}Ge_{25}$ acts as a positive resist in ion beam lithography. Previously, we reported the optical characteristics of amorphous $Se_{75}Ge_{25}$ thin film by the low-energy ion beam exposure and presented analytically calculated values such as ion range, ion concentration and ion transmission coefficient, etc. As the calculated results of analytical calculation, the energy loss per unit distance by $Ga^+$ ion is about $10^3[keV/{\mu}m]$ and nearly constant for all energy range. Especially, the projected range and struggling for 80 [KeV] $Ga^+$ ion energy are 0.0425[${\mu}m$] and 0.020[${\mu}m$], respectively. Hear, we present the results of Monte-Carlo computer simulation of Ga ion scattering, exposure and development in $a-Se_{75}Ge_{25}$ resist film for focused ion beam(FIB) lithography. Monte-Carlo method is based on the simulation of individual particles through their successive collisions with resist atoms. By the summation of the scattering events occurring in a large number N(N>10000) of simulated trajectories within the resist, the distribution for the range parameters is obtained. Also, the deposited energy density and the development pattern by a Gaussian or a rectangular ion beam exposure can be obtained.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.383-384
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• 2016

The Special Needs Education Assessment Tool (SNEAT) were verified of reliability and validity. However, the reliability and validity has been verified is only Okinawa Prefecture, the national data has not been analyzed. Therefore, this study aimed to verify the reliability and construct validity of SNEAT in Miyagi Prefecture as part of the national survey. SNEAT using 55 children collected from the classes on independent activities of daily living for children with disabilities in Miyagi Prefecture between November and December 2015. Survey data were collected in a longitudinal prospective cohort study. The reliability of SNEAT was verified via the internal consistency method; the coefficient of Cronbach's ${\alpha}$ were over 0.7. The validity of SNEAT was also verified via the latent growth curve model. SNEAT is valid based on its goodness-of-fit values obtained using the latent growth curve model, where the values of comparative fit index (0.997), tucker-lewis index (0.996) and root mean square error of approximation (0.025) were within the goodness-of-fit range. These results indicate that SNEAT has high reliability and construct validity.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.481-489
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• 2020

The study examines the role of facilitating conditions and user habits in the use of technology in Online Learning Platform (OLP) in Indonesia. The adoption of online learning, persistence, and learning results in online platforms is essential for ensuring that education technology is implemented and gets as much value as possible. People who use technology and systems will embrace new technologies even more. This quantitative study is based on a survey of 254 respondents, who were active users of the technology, and considers the facilitating conditions and user habits variables. Two research hypotheses were tested using the Partial Least Square-Structural Equation Modeling method. Cronbach's Alpha, path coefficient, AVE, R-square, T-test were applied. The results showed that the factors significantly influence the Online Learning Platform technology behavioral intention. This impact is primarily associated with the availability of the resources required to use OLP technology. The availability of these resources includes supporting infrastructures such as widespread Internet access, easy access to mobile devices, and file sizes that affect access speed. The findings of this study suggest that it is necessary to introduce and increase the availability of resources for using OLP technology, and familiarize people with the technology features.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.11
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• pp.705-710
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• 2011

Fault detection has to be proceeded by steady state filtering to get rid of transient effect associated with thermal capacity. Coefficient of variance (COV), ratio of standard deviation devided by moving average, was employed as steady-state filter. Engine speed and refrigerant pressures were selected as parameters representing system dynamics. The filtered values were registered as members of steady-state DB. They were found to show good functional relationship with ambient temperature. The relationship was fitted with a second order polynomial and the distribution bounds of the data around the fitted curve were expressed by visual inspection because of varying average and random data interval. Fault data were compared with the steady-state data obtained during normal operation. The fault data were easily isolated from the fault-free one. To make such isolation reliable, tests to construct good DB should be designed in a systematic way.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.10
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• pp.940-946
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• 2012

This paper proposes a method to predict maximum traction for unmanned robots on rough terrain in order to improve traversability. For a traction prediction, we use a friction-slip model based on modified Brixius model derived empirically in terramechanics which is a function of mobility number $B_n$ and slip ratio S. A friction-slip model includes characteristics of various rough terrains where robots are operated such as soil, sandy soil and grass-covered soil. Using a friction-slip model, we build a prediction model for terrain parameters on which we can know maximum static friction and optimal slip with respect to mobility number $B_n$. In this paper, Mobility number $B_n$ is estimated by modified Willoughby Sinkage model which is a function of sinkage z and slip ratio S. Therefore, if sinkage z and slip ratio are measured once by sensors such as a laser sensor and a velocity sensor, then mobility number $B_n$ is estimated and maximum traction is predicted through a prediction model for terrain parameters. Estimation results for maximum traction are shown on simulation using MATLAB. Prediction Performance for maximum traction of various terrains is evaluated as high accuracy by analyzing estimation errors.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.141-146
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• 2015

In order to classify and analyze variously compounded sound and voice signal from FPGA microphone, there are numerous systems to detect abnormality signal, however, they have a lot of problems to implement the abnormality signal detection efficiently and effectively. Therefore, we proposed a method that implements classifying the signal effectively and outputting the detection efficiently based on the algorithm applied FIFO structure (First-in First-out) by using microphone sensor which able to input the sound signal, and statistical variance and coefficient of variation (CV). The result showed 96.3% detection when the experiment was performed more than 100 times with the proposed algorithm applied system.

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.101-105
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• 1965

Spectrophotometric method for the determination of Co(Ⅱ) is developed based on the fact that Co(Ⅱ) forms a stable red complex with 7-nitroso-8-hydroxyquinoline-5-sulfonate at pH 4. 5. The absorbance is measured at 528$m{\mu}$, $25^{\circ}C$. Beer's law is followed in the concentration range of 0. 3 to 6. 0 p.p.m. of Co(Ⅱ) and molar extinction coefficient of the complex was $1.1{\times}10^4$. Of the diverse ions checked, Fe(Ⅱ), Fe(Ⅲ), Cu(Ⅱ), Mn(Ⅱ), Hg(Ⅰ), CN-, EDTA interfere. The composition of the complex is found to be 3:1 ligand to metal species by mole ratio and continuous variation methods.