• Journal of Sensor Science and Technology
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• v.33 no.4
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• pp.224-229
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• 2024

Quantum dot light-emitting diodes (QD-LEDs) are emerging as next-generation displays owing to their high color purity, wide color gamut, and solution processability. Enhancing the efficiency of QD-LEDs involves preventing non-radiative recombination mechanisms, such as Auger and interfacial recombination. Generally, ZnO serves as the electron transport layer, which is known for its higher mobility compared to that of organic semiconductors and can lead to excessive electron injection. Some of the injected electrons pass through the quantum dot emissive layer and undergo non-radiative recombination near or within the organic hole transport layer (HTL), resulting in HTL degradation. Therefore, the implementation of electron blocking layers (EBLs) is essential; however, studies on all-solution-processed inverted InP QD-LEDs are limited. In this study, poly(9-vinylcarbazole) (PVK) is introduced as an EBL to mitigate HTL degradation and enhance the emission efficiency of inverted InP QD-LEDs. Using a single-carrier device, PVK was confirmed to effectively inhibit electron overflow into the HTL, even at extremely low thicknesses. The optimization of the PVK thickness also ensured minimal disruption of the hole-injection properties. Consequently, a 1.5-fold increase in the maximum luminance was achieved in the all-solution-processed inverted InP QD-LEDs with the EBL.

• Journal of Korean Society for Quality Management
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• v.52 no.2
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• pp.377-394
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• 2024

Purpose: To derive the optimal conditions for the Rubber based colloidal suspension manufacturing process, which made using a stirrer, to apply the mixture design method. Methods: We used two process component and one process variable Mixture design to derive the optimal conditions for the process. The response variables were selected for rotational viscometer measures which can represent Rubber based colloidal suspension quality. The input variables were selected as the values of rubber-organic solvent expressed in proportions as process components and stirring amount as a process variable which are controllable factors in the process. Results: Based on the results of the experiment, rubber and organic solvent and the interaction between stirring amount and rubber and the interaction between stirring amount and rubber and organic solvent were significant. Reproducibility of the regression model was confirmed by the observation that the values obtained from the reproducibility experiment fell within the confidence interval. Additionally, the model predictions were found to be in close agreement with the field measurements. Conclusion: In this study, a regression model was developed to predict the viscosity change of colloidal suspensions based on the proportion of rubber based colloidal suspension. The developed regression model can lead to improved product quality.

• Toxicological Research
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• v.33 no.1
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• pp.43-48
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• 2017

With ultraviolet and visible light exposure, some pharmaceutical substances applied systemically or topically may cause phototoxic skin irritation. The major factor in phototoxicity is the generation of reactive oxygen species (ROS) such as singlet oxygen and superoxide anion that cause oxidative damage to DNA, lipids and proteins. Thus, measuring the generation of ROS can predict the phototoxic potential of a given substance indirectly. For this reason, a standard ROS assay (ROS assay) was developed and validated and provides an alternative method for phototoxicity evaluation. However, negative substances are over-predicted by the assay. Except for ultraviolet A (UVA), other UV ranges are not a major factor in causing phototoxicity and may lead to incorrect labeling of some non-phototoxic substances as being phototoxic in the ROS assay when using a solar simulator. A UVA stimulator is also widely used to evaluate phototoxicity in various test substances. Consequently, we identified the applicability of a UVA simulator to the ROS assay for photoreactivity. In this study, we tested 60 pharmaceutical substances including 50 phototoxins and 10 non-phototoxins to predict their phototoxic potential via the ROS assay with a UVA simulator. Following the ROS protocol, all test substances were dissolved in dimethyl sulfoxide or sodium phosphate buffer. The final concentration of the test solutions in the reaction mixture was 20 to $200{\mu}M$. The exposure was with $2.0{\sim}2.2mW/cm^2$ irradiance and optimization for a relevant dose of UVA was performed. The generation of ROS was compared before and after UVA exposure and was measured by a microplate spectrophotometer. Sensitivity and specificity values were 85.7% and 100.0% respectively, and the accuracy was 88.1%. From this analysis, the ROS assay with a UVA simulator is suitable for testing the photoreactivity and estimating the phototoxic potential of various test pharmaceutical substances.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.104-111
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• 2016

Recently, the quantities of chemical material are increasing in chemical industries. At that time, release accident is increasing due to aging of equipment, mechanical failure, human error, etc. and industrial complexes found community properties in a specific area. For that matter, chemical release accident can lead to hight probability of large disaster. There is a need to analyze the boundaries optimal sensor placement calculated by selecting release scenarios through release condition and wether condition in a chemical process for release detection and response. This paper is to investigate chlorine release accident scenarios using COMSOL. Through accident scenarios, a numerical calculation is studied to determine optimized sensor placement with weight of detection probability, detection time and concentration. In addition, validity of sensor placement is improved by robustness analysis about unpredicted accident scenarios. Therefore, this verifies our studies can be effectively applicable on any process. As mention above, the result of this study can help to place mobile sensor, to track gas release based concentration data.

• Journal of Broadcast Engineering
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• v.21 no.6
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• pp.957-964
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• 2016

Acquisition of reliable depth maps is a critical requirement in many applications such as 3D videos and free-viewpoint TV. Depth information can be obtained from the object directly using physical sensors, such as infrared ray (IR) sensors. Recently, Time-of-Flight (ToF) range camera including KINECT depth camera became popular alternatives for dense depth sensing. Although ToF cameras can capture depth information for object in real time, but are noisy and subject to low resolutions. Recently, filter-based depth up-sampling algorithms such as joint bilateral upsampling (JBU) and noise-aware filter for depth up-sampling (NAFDU) have been proposed to get high quality depth information. However, these methods often lead to texture copying in the upsampled depth map. To overcome this limitation, we formulate a convex optimization problem using higher order regularization for depth map upsampling. We decrease the texture copying problem of the upsampled depth map by using edge weighting term that chosen by the edge information. Experimental results have shown that our scheme produced more reliable depth maps compared with previous methods.

• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.135-146
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• 2004

For improving the effectiveness of travel information, some rational paths are needed to provide them to users driving in real road network. To meet it, k-shortest path algorithms have been used in general. Although the k-shortest path algorithm can provide several alternative paths, it has inherent limit of heavy overlapping among derived paths, which nay lead to incorrect travel information to the users. In case of considering the network consisting of several turn prohibitions popularly adopted in real world network, it makes difficult for the traditional network optimization technique to deal with. Banned and penalized turns are not described appropriately for in the standard node/link method of network definition with intersections represented by nodes only. Such problem could be solved by expansion technique adding extra links and nodes to the network for describing turn penalties, but this method could not apply to large networks as well as dynamic case due to its overwhelming additional works. This paper proposes a link-based shortest path algorithm for the travel information in real road network where exists turn prohibitions. It enables to provide efficient alternative paths under consideration of overlaps among paths. The algorithm builds each path based on the degree of overlapping between each path and stops building new path when the degree of overlapping ratio exceeds its criterion. Because proposed algorithm builds the shortest path based on the link-end cost instead or node cost and constructs path between origin and destination by link connection, the network expansion does not require. Thus it is possible to save the time or network modification and of computer running. Some numerical examples are used for test of the model proposed in the paper.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.535-542
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• 2016

As one of the most cost-effective methods for surface emission measurements, flux chamber method has been used worldwide. It can be classified into two types: SFC (with slope method) and DFC (with steady-state method). SFC (static flux chamber) type needs only simple equipment and is easy to handle. However, the value of flux might vary with SFC method, because it assumes that the change of concentration in chamber is linear with time. Although more specific equipments are required for DFC (dynamic flux chamber) method, it can lead to a constant result without any ambiguity. We made a self-designed DFC using a small and compact kit, which recorded good sample homogeneity (RSD < 5%) and recovery ( > 90%). Relative expanded measurement uncertainty of this improved DFC method was 7.37%, which mainly came from uncontrolled sweep air. The study shows that the improved DFC method can be used to collect highly reliable emission data from large landfill area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.437-447
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• 2017

In current, there has not been the evaluation model for the optimum design of the multi-utility tunnel by considering urban type and size, the function of surrounding road and feasibility analyses with respect to construction method, and arrangement of accommodation facilities inside multi-utility tunnel. Thus, in this study, we developed the evaluation model for the optimum design of the multi-utility tunnel before and after the decision of the multi-utility tunnel installation. In this paper, we have selected the Deming cycle which is used in various fields among several decision methods for optimizing the design. For the purpose of reflecting the various factors in the design of the multi-utility tunnel, 11 higher indicators were set up to lead to more detailed approaches. In addition, based on the "Plan-Do-Check-Action (PDCA)" circulation method, we can realize the installation of the multi-utility tunnel and design more efficiently through the first phase for conception and the second phase for optimization, and develop the program for the evaluation model accordingly.

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.316-329
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• 2008

Recently the increased attention pays on the processing of multiple, relatively low quantity, high value-added products resulted in adoption of batch process in the chemical process industry such as pharmaceuticals, polymers, bio-chemicals and foods. As there are more possibilities of the improvement of operations in batch process than continuous processes, a lot of effort has been made to enhance the productivity and operability of batch processes. But the chemical process industry faces a range of uncertainties factors such as demands for products, prices of product, lead time for the supply of raw materials and in the production, and the distribution of product. And global competition has made it imperative for the process industries to manage their supply chains optimally. Supply chain management aims to integrate plants with their supplier and customers so that they can be managed as a single entity and coordinate all input/output flows (of materials, information) so that products are produced and distributed in the right quantities, to the right locations, and at the right time.The objective of this study is to solve the purchase, distribution, production planning and scheduling problem, which minimizes the total costs of production, inventory, and transportation under uncertainty. And development of SCM model in chemical industry including batch mode operations. Through that, the enterprise can respond to uncertainty. Also integrated process optimal planning and scheduling model for manufacturing supply chain. The result shows that, the advantage of supply chain integration are quality matters seen by customers and suppliers, order schedules, flexibility, cost reduction, and increase in sales and profits. Also, an integration of supply chain (production and distribution system) generates significant savings by trading off the costs associated with the whole, rather than minimizing supply chain costs separately.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.3
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• pp.17-25
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• 2012

Wire bonding process in making semiconductor needs the most precise control and Critical To Quality(CTQ). Thus, it is regarded to be the most essential step in packaging process. In this process, pure gold wire is used to connect the chip and PCB(substrate or lead frame). However, the price of gold has been skyrocketing continuously for a long period of time and is expected to further increase in the near future. This phenomenon situates us in an unfavorable condition amidst the competitive environment. To avoid this situation, many semiconductor material making companies developed new types of wires: Au.Ag wire is one material followed by many others. This study is aimed to optimize the parameter in wire bonding with the use of 6sigma and QFD(Quality Function Deployment). 6sigma process is a good means to not only solve the problem, but to increase productivity. In order to find the key factor, we focused on VOB(Voice of Business) and VOC(Voice of Customer). The main factors from VOB, VOC are called CTQ. However, there were times when these main factors were far from offering us the correct answer, thus making the situation more difficult to handle. This study shows that QFD aids in deciding which of the accurate factors to undertake. Normally QFD is used in designing and developing products. 6sigma process is held more effective when it used with QFD.