• Resources Recycling
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• v.29 no.1
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• pp.17-24
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• 2020

In this study, rare earth elements (REE) leaching from a refractory REE ore containing goethite as a major gangue mineral was conducted, introducing a two-stage method of chemical decomposition-acid leaching. At the chemical decomposition step, using one of alkaline agent, NaOH, the ore was decomposed, changing NaOH concentration from 20 to 50 wt% at 10% (w/w) of pulp density and the maximum temperature achieved without boiling at each NaOH concentration. With increasing NaOH concentration, light REE (Ce, La and Nd) and iron were concentrated in the solid phase which is the decomposed product, while aluminum (Al) and phosphorus (P) were removed to the liquid phase, and their concentrations in the solid phase were down to 0.96 and 0.17%, respectively. In addition, through XRD analysis, it was found that the crystallinity of goethite was considerably decreased. At the acid leaching step, the product decomposed by 50 wt% NaOH was leached at 3.0 M HCl and 80 ℃ for 3 hr, then the REE leaching efficiency was above 94% (Ce 80%), and the leaching efficiencies of Al and P were decreased to 12 and 0%, respectively. Therefore, in terms of both REE leaching efficiency and impurity removal, those decomposition and leaching conditions were chosen as optimum processing methods of the investigated material. In terms of REE leaching mechanism, because REE and iron leaching efficiencies showed the positive correlation each other, so it can be concluded that decreasing crystallinity of goethite affect the improvement of REE leaching.

• (The) Research of the performance art and culture
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• no.41
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• pp.219-255
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• 2020

This article was triggered by Victor H. Mair's book 'Painting and performance'. The book explained that Buddhist paintings are common in the area where Buddhism was spread, and there are also performances using them. And although it has nothing to do with Buddhism, it has been shown that this form of performance can be global. However, the problem was not 'Korea'. It was because there was no record or transmission of the corresponding performance soon. In this situation, the landing method of Samcheok stable temple was announced in 2018. On the one hand, the academic community is very pleased, but on the other hand, it is troubled. The worries are summed up as 'synchronic and diachronic universality'. Is the landing method inherited from the Samcheok stable temple a unique type of temple? Otherwise, it is a question of whether it has been passed down or is it universal at the national level. However, prior to this essential question, we do not yet know the full picture of the stable landing method. So this article was prepared to show the overall outline of the stable landing method. There is a 'picture' in common throughout the landing method, and understanding how to operate it in various ways is the first step in understanding the landing method. There are five repertoires (which are called main halls) that are considered important, and more than that. What these repertoires have in common is the narrative structure of a Buddhist character. In this narrative, the most important thing is the revised figure, and it was the earthly method to inform the contents of the revised figure in various ways. In the case of Byeonsangdo, which serves as a clue to the narrative, there was a problem that could not be seen in the evening without light, which required special design. It is the way of shadow play and Yeongdeung. In other words, there are three types of performances in the landing method. The first is the method of using reparation, and the second is the method of using shadow. The third is the way of eternity. This method is not a selection based on the contents of the repertoire, but a selection based on the performance environment. If there is light and you can see the picture, use reparation. However, in the evening, it was impossible to see it dark (when there was no electricity in the past). The use of the visual method as a tool in this method is to confirm the transition to a visual culture that is a step further from the level of culture. Moreover, unlike the epic narrative, the power of the implied image provided an opportunity for viewers to experience the mystery of Buddhism through emotional stimulation.

• Korean Journal of Remote Sensing
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• v.36 no.3
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• pp.449-460
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• 2020

Super-resolution is a technique used to reconstruct an image with low-resolution into that of high-resolution. Recently, deep-learning based super resolution has become the mainstream, and applications of these methods are widely used in the remote sensing field. In this paper, we propose a super-resolution method based on the deep back-projection network model to improve the satellite image resolution by the factor of four. In the process, we customized the loss function with the edge loss to result in a more detailed feature of the boundary of each object and to improve the stability of the model training using generative adversarial network based on Wasserstein distance loss. Also, we have applied the detail preserving image down-scaling method to enhance the naturalness of the training output. Finally, by including the modified-residual learning with a panchromatic feature in the final step of the training process. Our proposed method is able to reconstruct fine features and high frequency information. Comparing the results of our method with that of the others, we propose that the super-resolution method improves the sharpness and the clarity of WorldView-3 and KOMPSAT-2 images.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.197-201
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• 2008

Conceptual cost estimates for domestic highway projects have generally been conducted using governmental unit-price references. Inaccuracies in governmental unit-price data has repeatedly addressed in the Korean construction industry which often lead to poor decision making and cost management practices. Thus, needs for developing a better way of conceptual cost estimating has been widely recognized. This research is considered as the first step in developing such model using real-world cost data based on actual construction activities. The data analyzed in this paper includes 41 P.S.C (Prestressed Concrete) Box bridges which broke into 4 categories based on construction methods such as I.L.M(Incremental Launching Method), M.S.S(Movable Scaffolding System), F.S.M(Full Staging Method), and F.C.M(Free Cantilever Method). Actual design documents; including actual cost estimating documents, drawings and specifications were carefully reviewed to effectively break down cost structures for PSC girder bridges. Among more than 40 cost categories for each P.S.C girder bridge type, 7 of them were identified which accounted for more than 95% of total construction cost (ILM: 99.47%, MSS: 99.22%, FSM: 98.18%, and FCM: 98.12%). In order to validate the clustering of cost categories, the variation of each cost category has been investigated which resulted in between -1.16 % and 0.59%.

• Restorative Dentistry and Endodontics
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• v.31 no.1
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• pp.30-35
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• 2006

To evaluate the change of working length with various instrumentation techniques in curved canals, working length and canal curvature were determined before and after canal instrumentation in buccal or mesial canals of extracted human molars. Stainless steel K-files ($MANI^{(R)}$, Matsutani Seisakusho Co. Takanezawa, Japan), nickel-titanium K-files (Naviflex $NT^{TM}$, Brassier, Savannah, USA) , $ProFile^{(R)}$, and ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland) were used to prepare the canals with crown-down technique. In two hand instrumentation groups coronal flaring was made with Gates Glidden burs. Apical canals were instrumented until apical diameter had attained a size of 30. Positional relation between the tooth apex and the $\#10$ K-file tip was examined by using AutoCAD 2000 (Autodesk Corp., San Rafael. CA, USA) under a stereomicroscope before and after coronal flaring, and after apical instrumentation. Degree of canal curvature was also measured with Schneider's method in radiographs. Data of working length and canal curvature changes were statistically analyzed with one-way ANOVA and Tukey's studentized range test. Working length and canal curvature were decreased significantly in each step in all instrumentation groups. Coronal flaring using Cates Glidden burs in hand instrument groups and whole canal instrumentation using stainless steel hand K-files caused significantly more working length change than in ProFile instrumentation group (p<0.05). The result of this study demonstrates that all of the above kinds of instrumentation in curved canals cause reduction of working length and canal curvature at each instrumentation steps, and hand instrumentation causes more working length change than ProFile.

• Journal of The Korean Association For Science Education
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• v.35 no.1
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• pp.121-130
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• 2015

Identifying students' achievement level and reflecting it on educational policy making or instructional improvement by analyzing the results of nationwide standardized assessment is an integral part of accountability in education. On the basis of this premise, we analyzed the characteristics of National Assessment of Educational Achievement (NAEA) items for middle school science subject conducted from 2010 to 2013 by using the option response rate distribution curve, the fittest graph estimated from the response rate of correct/incorrect options by achievement score. Furthermore, we classified the type of option response rate curve in terms of correct and incorrect options. Results of the analysis of option response curve showed that five types of correct option response curve (S-shaped, J-shaped, straight-shaped, F-shaped, and step-shaped) and 4 types of incorrect option response curve (down-slope, flat, mound, and up-slope) were identified. The most common type of items was the combination of S-shaped correct option response curve and down-slope incorrect option response curve, which are considered as appropriate items to discriminate the students according to achievement level. Moreover, correct option response was found to be correlated with incorrect option response. Based on the results, we also discussed some implications on teaching-learning method and classroom assessment in science education.

• Journal of IKEEE
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• v.13 no.2
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• pp.208-215
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• 2009

The high efficiency power management IC(PMIC) with DT-CMOS(Dynamic Threshold voltage MOSFET) switching device for portable application is proposed in this paper. Because portable applications need high output voltages and low output voltage, Boost converter and Buck converter are embedded in One-chip. PMIC is controlled with PWM control method in order to have high power efficiency at high current level. DTMOS with low on-resistance is designed to decrease conduction loss. Boost converter and Buck converter, are based on Voltage-mode PWM control circuits and low on-resistance switching device, achieved the high efficiency near 92.1% and 95%, respectively, at 100mA output current. And Step-down DC-DC converter in stand-by mode below 1mA is designed with LDO in order to achive high efficiency.

• Journal of The Korean Society of Integrative Medicine
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• v.1 no.1
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• pp.61-68
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• 2013

Purpose : The purpose of this study is to evaluate the stability and balance of the body, mobility complex exercise group and a student group for FMS tests to compare the differences between the two groups to identify its purpose. Method : The subjects of this study FMS measuring D University Physical Therapy, a student enrolled patients (7:7), and 7 patients total of 14 patients was conducted, compound exercise group weekly stretching 10 minutes, the 24 members who have run a complex exercise, 10 minutes of cool down stretching, 20-minute aerobic exercise were included in the study. Result : The results of this study, according to 1) Deep squat, Inline lunge, Trunk Stability Push-up there was significant difference(p<0.05), compound exercise group came out significantly higher. 2) Hurdle Step, Shoulder Mobility Reaching, Active Straight-leg Raise, Rotary stability in measured target these women flexibility because the test items that did not show a significant difference(p>0.05), the two groups averaged compared to the other items were higher. Complex exercise group, a statistically significant difference was overall average. Conclusion : FMS can not be resolved because of a compensatory mechanism to identify disparities and unbalanced movement patterns can help. Therefore, if the FMS and other tests conducted by splicing, will be utilized more profitably, and you will be able to suggest ways that can have a positive impact injury prevention is added to the side to expand the scope of the physical therapist.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.9
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• pp.1-7
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• 2008

This paper proposes 3.3V input and 1.8V output voltage mode step-down DC-DC buck converter for wireless mobile system which is designed in a standard 0.35$\mu$m CMOS process. The proposed capacitor multiplier method can minimize error amplifier compensation block size by 30%. It allows the compensation block of DC-DC converter be easily integrated on a chip. Also, we improve efficiency to 3% using low power buffer. Measurement result shows that the circuit has less than 1.17% output ripple voltage and maximum 83.9% power efficiency.

• Journal of Mechanical Science and Technology
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• v.19 no.4
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• pp.1001-1005
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• 2005

This paper evaluates the performance of ventilation for the removal of indoor pollutants as a function of ventilation rate and the number of occupants in a test room and school classroom. An experimental apparatus consists of a test room, a tracer gas supply system, a gas detector, and a fan for ventilation air supply with a controller. The ventilation performance is evaluated in a step-down method based on ASTM Standard E741-83 using $CO_{2}$ gas as a tracer gas in the test room of 35 $m^{3}.$ For the ventilation air flow rate of 1.0 ACH, a recommended ventilation flow rate of Korea school standard for acceptable indoor air quality in the case of one person, CO_{2}$ gas concentration decreases up to $55{\%}$ within 50 minutes without occupancy and increases up to $75{\%}$ in the case of one occupant. Also indoor air quality at the school classroom is investigated experimentally.