• Medical Lasers
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• v.10 no.4
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• pp.229-237
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• 2021

Background and Objectives To assess the effectiveness of overnight orthokeratology (OK) in myopia using a new contact lens design over a one-month wearing period. Materials and Methods Participants were required to have myopia between -3.00 and -7.50D and astigmatism ≤ 2.00 D to participate in the study. The participants underwent OK with the White OK lens^® (Interojo, Pyungtek, Korea), which has a 6-curve lens design. Participants were assessed at weeks 1, 2, and 4 using slit-lamp bio-microscopy, and tested for refraction, uncorrected distance visual acuity, and corneal topography. Success was defined as achieving a Logarithm of the Minimum Angle of Resolution (logMAR) ≤ 0.1. Results A total of 46 eligible subjects with a mean age of 23.11 ± 7.89 years were recruited. Baseline logMAR was 1.18 ± 0.30 and a consistent decrease in logMAR was observed from week 1 to week 4. The success rate was 95.35% at week 4. The mean sphere significantly decreased from a mean pre-fitting value of -4.58 ± 1.28 D to a mean value of -0.65 ± 0.69 D at week 4 (p < 0.0001). Statistically significant corneal flattening was detected during keratometry at week 4. Conclusion Overnight OK with the White OK lens is effective for the correction of moderate and high myopia with astigmatism over a one-month wearing period.

• Korean Journal of Materials Research
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• v.33 no.2
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• pp.29-46
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• 2023

The electrochemical reduction of carbon dioxide (CO₂) to value-added products is a remarkable approach for mitigating CO₂ emissions caused by the excessive consumption of fossil fuels. However, achieving the electrocatalytic reduction of CO₂ still faces some bottlenecks, including the large overpotential, undesirable selectivity, and slow electron transfer kinetics. Various electrocatalysts including metals, metals oxides, alloys, and single-atom catalysts have been widely researched to suppress HER performance, reduce overpotential and enhance the selectivity of CO₂RR over the last few decades. Among them, single-atom catalysts (SACs) have attracted a great deal of interest because of their advantages over traditional electrocatalysts such as maximized atomic utilization, tunable coordination environments and unique electronic structures. Herein, we discuss the mechanisms involved in the electroreduction of CO₂ to carbon monoxide (CO) and the fundamental concepts related to electrocatalysis. Then, we present an overview of recent advances in the design of high-performance noble and non-noble singleatom catalysts for the CO₂ reduction reaction.

• Transactions of Materials Processing
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• v.7 no.3
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• pp.282-290
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• 1998

In bulk metal forming processes prediction of tool life is very important for saving production cost and achieving good material properties. Generally the service life of tools in metal forming process is limited to a large extent by wear, fracture and plastic deformation of tools. In case of hot and warm forging processes tool life depends on wear over 70%. In this study finite element analyses are con-ducted to warm and hot forging by adopting suggested wear model. By comparison of simulation and eal profile of die suggested wear model. By comparison of simulation and real profile of die suggested model is verified.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.26-29
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• 2004

S-PVA is a new technology which enables screen quality advantages over S-IPS and MVA, including high transmittance, >1000:1 contrast ratio, sub-10ms response time, and wide angle of view with no off-axis image inversion and undetectable gamma distortion. This new technology will be described in detail. This paper also addresses the other remaining performance issues facing LCD-TV, including Samsung's plans for addressing these challenges. For example, until recently, inter-gray response time and associated motion blur were significant issues for achieving LCD-TV images quality. Samsung has invented DCC-II technology to achieve sub-10ms response time, and this achievement is described herein. Other technology advancements, including next-generation color performance and ultra-low black performance and improvement of off axis image quality are also discussed in this paper.

• Speech Sciences
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• v.9 no.1
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• pp.39-47
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• 2002

This paper proposes an effective method to remedy the acoustic modeling problem inherent in the usual log-normal Parallel Model Composition intended for achieving robust speech recognition. In particular, the Gaussian kernels under the prescribed log-normal PMC cannot sufficiently express the corrupted speech distributions. The proposed scheme corrects this deficiency by judiciously selecting the 'fairly' corrupted component and by re-estimating it as a mixture of two distributions using data-driven PMC. As a result, some components become merged while equal number of components split. The determination for splitting or merging is achieved by means of measuring the similarity of the corrupted speech model to those of the clean model and the noise model. The experimental results indicate that the suggested algorithm is effective in representing the corrupted speech distributions and attains consistent improvement over various SNR and noise cases.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.467-476
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• 2007

This work verifies the chaotic motion of a steer-by-wire vehicle dynamic system, and then elucidates an application of dither smoothing to control the chaos of a vehicle model. The largest Lyapunov exponent is estimated from the synchronization to identify periodic and chaotic motions. Then, a bifurcation diagram reveals complex nonlinear behaviors over a range of parameter values. Finally, a method for controlling a chaotic vehicle dynamic system is proposed. This method involves applying another external input, called a dither signal, to the system. The designed controller is demonstrated to work quite well for nonlinear systems in achieving robust stability and protecting the vehicle from slip or spin. Some simulation results are presented to establish the feasibility of the proposed method.

• Journal of Environmental Science International
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• v.4 no.3
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• pp.295-301
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• 1995

Continuous deodorization of malodorous sulfur compounds by Thiobaillus neapolitanusts R-10 immobilized onto a polypropylene pellet was studied using a column reactor at 30$^{\circ}$C. The maximum amounts of immobilized cells was 5.3 gall polypropylene with 5$\times$7.5mm in pellet size, and the amounts of immobilized cells in the higher part of the column was as twice as in the lower part. The optimum pH and temperature for removal of dimethyl sulfide were 6.0 and 30$^{\circ}$C, respectively. When 5-20 ${mu}ell$/l of hydrogen sulfide and methylmercaptan were employed 98% of removal efficiency were achieved. In contrast, lower concentrations of dimethyl sulfide and dimethyldisulfide should be supplied to meet satisfactory deodorization efficiency. The immobilized cell column was successfully operated for the deodorization of mixture of sulfur compounds over 15 days without significant loss of initial activity achieving high efficiency.

• Management Science and Financial Engineering
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• v.16 no.2
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• pp.53-65
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• 2010

Despite the overall success of neighbor-based CF methods, there are some fundamental questions about neighbor selection and prediction mechanism including arbitrary similarity, over-fitting interpolation weights, no trust consideration between neighbours, etc. This paper proposes a simple method to compute absolute interpolation weights based on similarity values. In order to supplement the method, two schemes are additionally devised for high-quality neighbour selection and trust metrics based on co-ratings. The former requires that one or more neighbour's similarity should be better than a pre-specified level which is higher than the minimum level. The latter gives higher trust to neighbours that have more co-ratings. Experimental results show that the proposed method outperforms the pure IBCF by about 8% improvement. Furthermore, it can be easily combined with other predictors for achieving better prediction quality.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1632-1636
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• 2007

Generally, fine high carbon steel wire is produced using a multi-pass drawing process with speeds over 1000 m/min. The productivity of the wire drawing mainly depends on achieving the highest drawing speed without breaking the wire. In the multi-pass drawing, as the final drawing speed increases, the temperature rises several hundred Celsius. High temperature of wire increases the brittleness and leads to breaks. The objective of this study is to design pass schedule and wire drawing machine for superhigh speed. In the drawing experiment, it was possible to increase the productivity through the increase in final speed from 1100 m/min to 2000 m/min.

• Korean Management Science Review
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• v.23 no.3
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• pp.209-224
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• 2006

The mobile communication technology would be one of the most appropriate means for achieving process innovation in the actual business area. This article performs a simulation study to examine the effect of introducing a mobile technology to the after-sales service and its logistics process. The performances of the two different systems, before and after introducing a mobile technology, are examined based on operational cost, operational efficiency, and customer service level using a discrete event simulation. The real-world data, extracted from a leading Korean electronics firm, was collected for this study. The results show that the TO-BE(after) model outperforms the AS-IS(before) model over all the performance indices. And the effects of introducing the mobile technology are more significant on the more tightly controlled inventory policy.