• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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• pp.180-190
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• 2005

The PSA cycle was performed for the separation of binary gas mixture $H_2/Ar$ (80%/20%) using the six-step two-bed process. Adsorption equilibrium contains a LRC model for equilibrium adsorption isotherms and a LDF model for mass transfer. Aspen ADSIM, simulator was applied to predict the separation performance. The effect of cycle parameters such as feed rate, adsorption pressure and P/F ratio on the separation of hydrogen has been studied in experiment and simulation. In the results, maximize the recovery of hydrogen as a high purity was 13LPM feed flowrate, 120sec adsorption time, 11atm adsorption pressure and 0.1 P/F ratio in a cyclic steady-state come out since 10th cycle.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.6
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• pp.119-130
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• 2019

Although a well-established line of research has addressed the funding decision, the activities of investee startups to receive funding have been overlooked because prior research has been conduced from investor's point of view. In addition, funding does not result from one off decisions but from decision process with many stages. Moreover, the emphasis placed on specific investment criteria varies by different stages during the process. Therefore, understanding the initial funding of startups requires to analyze the strategic behaviors of startups throughout the entire funding decision process from first meeting with investors to funding success. This study investigates the initial funding process of startups, and the analysis is based on a case study of LetinAR one of the successful startups founded by students in South Korea. This study investigates how early start-ups were able to receive funding from startup's point of view, and the analysis is based on a case study of LetinAR, an augmented reality(AR) startup using Pin mirror technology. By adding "legitimacy building" stage that had not been addressed previously, we divided funding process into four stages: 1) legitimacy building, 2) familiarization, 3) screening, and 4) bargaining phase. We did not only analyze major criteria, but also strategic activities of startup at each stage. This study makes a contribution by helping us understand complicated process of funding and the successful strategic behavior of investor backed startups.

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.05a
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• pp.144-144
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• 1993

• Communications for Statistical Applications and Methods
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• v.3 no.2
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• pp.77-83
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• 1996

This paper is concerned with an estimation problem for the AR(1) process $Y_t, t=0, {\pm}1, {\cdots}$with time carying autoregressive coefficient, where coefficient itself is also stochastic process. Attention is directed to the problem of finding a consistent estimator of ${\Phi}$, the mean level of autoregressive coefficient. The asymptotic distribution of the resulting consistent estimator of ${\Phi}$, is them discussed. We do not assume any time series model for the time varying autoregressive coefficient.

• The Journal of Korean Physical Therapy
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• v.31 no.3
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• pp.141-146
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• 2019

Purpose: To investigate the effect of an augmented reality (AR) system on muscle strength and function level of the paretic lower limb and the balance ability in the early rehabilitation program of acute stroke patients. Methods: The participants (30 or fewer days after stroke) were randomly assigned to receive intervention with an early rehabilitation program using an AR system (n=1) or an early rehabilitation program consisting of functional electrical stimulation and tilt table use (n=1). Patients in both subjects received interventions 4-5 times a week for 3 weeks. Results: In the paretic limb muscle strength, AR subject was increased from 15 to 39.6 Nm and Control subject was increased from 5 to 30.2 Nm. The paretic limb function of AR subject motor function was increased from 8 to 28 score and Control subject motor function was increased from 6 to 14 score. But sensory function was very little difference between the two subjects (AR subject: from 4 to 10 score, Control subject: from 3 to 10 score). In the balance ability, AR subject had more difference after intervention than control subject (AR subject: 33 score, Control subject: 22 score). Conclusion: The early rehabilitation program using the AR system showed a slightly higher improvement in the motor function of the paretic lower limb and balance ability measurement than the general early rehabilitation program. The AR system, which can provide more active, task-oriented, and motivational environment, may provide a meaningful environment for the initial rehabilitation process after stroke.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.8
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• pp.1939-1951
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• 1994

This study introduces a new tool breakage detecting technology comprised of an unsupervised neural network combined with adaptive time series autoregressive(AR) model where parameters are estimated recursively at each sampling instant using a parameter adaptation algorithm based on an RLS(Recursive Least Square). Experiment indicates that AR parameters are good features for tool breakage, therefore it can be detected by tracking the evolution of the AR parameters during milling process. an ART 2(Adaptive Resonance Theory 2) neural network is used for clustering of tool states using these parameters and the network is capable of self organizing without supervised learning. This system operates successfully under the wide range of cutting conditions without a priori knowledge of the process, with fast monitoring time.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.138-146
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• 2012

This paper studies the effect of information quality level and customer demand on performance measures in a supply chain. The information quality level compares 2 types, the information levels of a customer demand and a lead time. The customer demand process follows a general auto-correlated AR(1) process without seasonality. In the AR(1) process, ${\sigma}$ indicates the degree of demand fluctuation and ${\rho}$ means the trend of customer demand. ANOVA tests using a 5% significance level are performed in SPSS to examine significant performance changes among various cases.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.12
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• pp.69-76
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• 1993

The statistical methodology using RSM (response surface method) was used too ptimize the deposition conditions of selective CVD tungsten process for improving the deposition rate and the adhesion property. Temperature, flow rate of SiH$_4$ and WF$_6$ and H$_2$ and Ar carrier gases were chosen for the deposition variables and process characteristics due to carrier gas were intensively investigated. It was observed that temperature was the main factor influencingthe deposition rate in the case of H$_2$ carrier gas while the reactant ratio, $SiH_{4}/WF_{6}$, had the principal effect on the deposition rate in the case of Ar carrier gas. The increased deposition rate and the good adhesion to Si were obtained under Ar carrier gas compared to H$_2$ carrier gas. The optimum conditions for deposition rate and antipeeling property were found to be the temperature range of 300~32$0^{\circ}C$ and the reactant ratio, $SiH_{4}/WF_{6}$, of 0.5~0.6.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.3
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• pp.15-20
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• 2007

Low temperature processed ZnO-TFTs on glass below $270^{\circ}C$ for plastic substrate applications were fabricated and their electrical properties were investigated. Films in ZnO-TFTs with bottom gate configuration were made by RF magnetron sputtering system except for $SiO_2$ gate oxide deposited by ICP-CVD. ZnO channel films were grown on glass with various Ar and $O_2$ flow ratios. All of the fabricated ZnO-TFTs showed perfectly the enhancement mode operation, a high optical transmittance of above 80% in visible ranges of the spectrum. In the ZnO-TFTs with pure Ar process, the field effect mobility, threshold voltage, and on/off ratio were measured to be $1.2\;cm^2/Vs$, 8.5 V, and $5{\times}10^5$, respectively. These characteristic values are much higher than those of the ZnO-TFTs of which ZnO channel layers were processed with additional $O_2$ gas. In addition, ZnO-TFT with pure Af process showed smaller swing voltage of 1.86v/decade compared to those with $Ar+O_2$ process.

• Journal of Korea Foundry Society
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• v.32 no.6
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• pp.276-283
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• 2012

This study presents the results on the changes of crucible thermal conductivity and inflow of Ar, and constructed the mathematical model about heat transfer into furnace. As process variables, simulation model was designated thermal conductivity of crucible to $0.5W{\cdot}m^{-1}{\cdot}K^{-1}$, $1W{\cdot}m^{-1}{\cdot}K^{-1}$, $2W{\cdot}m^{-1}{\cdot}K^{-1}$, $4W{\cdot}m^{-1}{\cdot}K^{-1}$, and inflow rate of Ar to 15 L/min, 30 L/min, 60 L/min. Initial condition and boundary condition were set respectively in two terms of process. Each initial conditions were set up by the preceding simulation of heat and fluid flow. The primary goal is the application of unidirectional growth of Si ingot using the result. In the result of the change of heat conductivity of crucible, the higher thermal conductivity of crucible shows the shorter solidification time and the bigger temperature difference. And the flow patterns are changed with the inflow rate of Ar. Finally, we found that the lower crucible's thermal conductivity, the better crucible is at polycrystalline Si ingot growth. But in case of Ar inflow, it is hard to say about good condition. This data will be evaluated as useful reference used in allied study or process variable control of production facilities.