• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.145-146
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• 2007

Dye-Sensitized Solar Cell Solar cells(DSSC) were appeared for overcoming global environmental problems and lack of fossil fuel problems. And it is one of study field that is getting into the spotlight lately because manufacturing method is more simple and inexpensive than existing silicon solar cells. Oxide semiconductor is used for adsorption of dye and electron transfer in DSSC study, and $TiO_2$ is used most usually. Overall light conversion efficiency is changed by several elements such as $TiO_2$ particle size and structure, pore size and shape. In this study, we report the solar cell performance of titania$(TiO_2)$ film electrodes with various particle sizes. $TiO_2$ particle size was 16 nm, 25 nm, and mixture of 16nm and 25 nm, and manufactured using Doctor blade method. When applied each $TiO_2$ film to DSSC, the best efficiency was found at 16nm of $TiO_2$ particle. 16nm of $TiO_2$ particle has the highest efficiency compared to the others, because particles with smaller diameters would adsorb more dye due to larger surface area. And in case of the mixture of 16nm and 25 nm, the surface area was smaller than expected. It is estimated that double layer is adsorbed a large amount of chemisorbed dye and improved light scattering leading due to efficiency concentration light than mono layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.281.1-281.1
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• 2016

Transition metal dichalcogenides (TMDCs) are promising layered structure materials for next-generation nano electronic devices. Many investigation on the FET device using TMDCs channel material have been performed with some integrated approach. To use TMDCs for channel material of top-gate thin film transistor(TFT), the study on high-k dielectrics on TMDCs is necessary. However, uniform growth of atomic-layer-deposited high-k dielectric film on TMDCs is difficult, owing to the lack of dangling bonds and functional groups on TMDC's basal plane. We demonstrate the effect of remote oxygen plasma pretreatment of large area synthesized few-layer MoSe2 on the growth behavior of Al2O3, which were formed by atomic layer deposition (ALD) using tri-methylaluminum (TMA) metal precursors with water oxidant. We investigated uniformity of Al2O3 by Atomic force microscopy (AFM) and Scanning electron microscopy (SEM). Raman features of MoSe2 with remote plasma pretreatment time were obtained to confirm physical plasma damage. In addition, X-ray photoelectron spectroscopy (XPS) was measured to investigate the reaction between MoSe2 and oxygen atom after the remote O2 plasma pretreatment. Finally, we have uniform Al2O3 thin film on the MoSe2 by remote O2 plasma pretreatment before ALD. This study can provide interfacial engineering process to decrease the leakage current and to improve mobility of top-gate TFT much higher.

• Journal of the Korean Dietetic Association
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• v.17 no.4
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• pp.403-415
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• 2011

The present study was performed to evaluate the job training needs of school nutrition teachers in order to enhance their specialty. Three hundred and forty questionnaires were distributed to school nutrition teachers working at primary and high schools in the Gyeongbuk area while 45 were distributed to professors during 2010~2011. Three hundred and two questionnaires from school nutrition teachers and 33 from professors were returned and analyzed. The rate of teachers practicing nutrition education was 54%, and the educational content was obtained mainly from the internet. The top three problems the teachers encountered were 'lack of standardized educational materials', 'inexperience of teaching', and 'insufficiency of expert knowledge'. The teachers recognized 'training program' as the best solution. However, the job training program operated immediately after teachers were appointed scored only 3.03 out of 5.00. Important contents of the training program ranked highly by the teachers were 'development of education materials', 'nutrition counseling', and 'teaching method'. The professors included 'expert knowledge' in their top three contents. Both the teachers and professors agreed to increase the frequency of 'practice' in training methods. Other factors the teachers considered to be important were high quality, diversity, ability of the instructor, training cycle, and the institution in charge. From these results, it can be concluded that efficient job training programs are needed for school nutrition teachers according to the importance of the education contents and training methods. It is therefore suggested that a cooperation committee be composed of an educator, educatee, and related personal in a local education office in order to operate the program.

• Imaging Science in Dentistry
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• v.46 no.1
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• pp.9-16
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• 2016

Purpose: To evaluate the upper airway dimensions of obstructive sleep apnea (OSA) and control subjects using a cone-beam computed tomography (CBCT) unit commonly applied in clinical practice in order to assess airway dimensions in the same fashion as that routinely employed in a clinical setting. Materials and Methods: This was a retrospective analysis utilizing existing CBCT scans to evaluate the dimensions of the upper airway in OSA and control subjects. The CBCT data of sixteen OSA and sixteen control subjects were compared. The average area, average volume, total volume, and total length of the upper airway were computed. Width and anterior-posterior (AP) measurements were obtained on the smallest axial slice. Results: OSA subjects had a significantly smaller average airway area, average airway volume, total airway volume, and mean airway width. OSA subjects had a significantly larger airway length measurement. The mean A-P distance was not significantly different between groups. Conclusion: OSA subjects have a smaller upper airway compared to controls with the exception of airway length. The lack of a significant difference in the mean A-P distance may indicate that patient position during imaging (upright vs. supine) can affect this measurement. Comparison of this study with a future prospective study design will allow for validation of these results.

• Economic and Environmental Geology
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• v.29 no.5
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• pp.575-587
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• 1996

The purpose of this study is to develop geostatistical methods for selection of prospective areas of polymetallic nodule deposits in KODOS (Korea Deep Ocean Study) area of the North-East Pacific Ocean. In this study $110{\times}165$ grid system was used, and each node represents the center of an estimated block of $1km{\times}1km$. The ordinary kriging was applied to SeaBeam2000 data in order to evaluate the bathymetry. A structural analysis (variogram) of the bathymetry data was carried out for constructing digital terrain model (DTM) and the maximum slopes of the bathymetry were calculated by DTM data. The above method can be used to solve the problem that is resulted from the lack of theory of a change of support model for the maximum slope of the bathymetry. The ordinary kriging and the indicator kriging were used to evaluate the nodule abundance, and the different two kriging methods were compared to evaluate the accuracy for the estimation of the nodule abundance. It has been shown that indicator kriging was better estimation tool than the ordinary kriging. The overlay map is presented for the selection of potentially minable sites by combining the two indicator maps of the nodule abundance and the maximum slope of bathymetry. This overlay map could be utilized to establish follow-up survey and to investigate the potentially minable sites in the KODOS area.

• Journal of Environmental Science International
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• v.18 no.9
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• pp.961-970
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• 2009

This paper has attempted to improve the quality of urban environment in terms of the management of urban green tract and suggest a way of coexistence between human and nature by proposing a plan to establish green network using an urban green zone based on 'linear concept' instead of point and plane concepts. The results have turned out as follows: 1. According to current status of forest functions, forest recreation area has reached 39.6%, satisfying citizens' needs. However, the space for living environment is just about 20% with a lack of a green zone. Therefore, it's been necessary to establish green network using roadside trees and take advantage of them as sustainable living space along with existing green tract. 2. With forest in the suburbs and Geumhogang which is the tributary to the Nakdonggang, Sincheon (stream) flows through the downtown. It connects mountains including Waryongsan from the south to the north around Duryu Park and Dalseong Park. Therefore, the water system that passes through Palgongsan (Mt.) and Biseulsan (Mt.) would make it possible to connect with the parks in the downtown. 3. According to this paper, it appears that it's necessary to establish green network through roof or wall greening by focusing on the existing green tract in the urban parks and suburbs and taking advantage of roadside trees and water system.

• Journal of The Korean Association of Information Education
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• v.18 no.2
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• pp.285-294
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• 2014

Recently, research using robots as a learning tool has increasingly been conducted in K-12 education area. It has been known that hands-on robots give positive educational effect not only on science and mathematics, but on STEAM activity, and help improve the abilities necessary in the 21 century, such as critical thinking, creativity, communication skills, and team work. Despite many research achievements, there is still few research on robot based curriculum to improve the instrumental application of robots in the primary and secondary education fields. In other words, there is a lack of studies of systematic educational contents, educational methods and educational evaluation to increase the instrumental application according to schools and class years. Therefore, this study analyzed domestic and foreign robot based curriculums and relevant cases to develop 'robot' related educational programs in primary school and middle school, suggested the achievement objectives in the robot area as a sub category of the computer science curriculum which will be revised, and proposed teaching-learning method and evaluation method.

• Journal of Climate Change Research
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• v.7 no.3
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• pp.325-334
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• 2016

We projected the distribution of Hedera rhombea, an evergreen broad-leaved climbing plant, under current climate conditions and predicted its future distributions under global warming. Inaddition, weexplained model uncertainty by employing 9 single Species Distribution model (SDM)s to model the distribution of Hedera rhombea. 9 single SDMs were constructed with 736 presence/absence data and 3 temperature and 3 precipitation data. Uncertainty of each SDM was assessed with TSS (Ture Skill Statistics) and AUC (the Area under the curve) value of ROC (receiver operating characteristic) analyses. To reduce model uncertainty, we combined 9 single SDMs weighted by TSS and resulted in an ensemble forecast, a TSS weighted ensemble. We predicted future distributions of Hedera rhombea under future climate conditions for the period of 2050 (2040~2060), which were estimated with HadGEM2-AO. RF (Random Forest), GBM (Generalized Boosted Model) and TSS weighted ensemble model showed higher prediction accuracies (AUC > 0.95, TSS > 0.80) than other SDMs. Based on the projections of TSS weighted ensemble, potential habitats under current climate conditions showed a discrepancy with actual habitats, especially in the northern distribution limit. The observed northern boundary of Hedera rhombea is Ulsan in the eastern Korean Peninsula, but the projected limit was eastern coast of Gangwon province. Geomorphological conditions and the dispersal limitations mediated by birds, the lack of bird habitats at eastern coast of Gangwon Province, account for such discrepancy. In general, potential habitats of Hedera rhombea expanded under future climate conditions, but the extent of expansions depend on RCP scenarios. Potential Habitat of Hedera rhombea expanded into Jeolla-inland area under RCP 4.5, and into Chungnam and Wonsan under RCP 8.5. Our results would be fundamental information for understanding the potential effects of climate change on the distribution of Hedera rhombea.

• KIPS Transactions on Software and Data Engineering
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• v.9 no.1
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• pp.33-38
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• 2020

This paper proposes a technique for counting construction materials by analyzing an image acquired by a Drone. The proposed technique use drone log which includes drone and camera information, RCNN for predicting construction material type, dummy area and Photogrammetry for counting the number of construction material. The existing research has large error ranges for predicting construction material detection and material dummy area, because of a lack of training data. To reduce the error ranges and improve prediction stability, this paper increases the training data with a method of data augmentation, but only uses rotated training data for data augmentation to prevent overfitting of the training model. For the quantity calculation, we use a drone log containing drones and camera information such as Yaw and FOV, RCNN model to find the pile of building materials in the image and to predict the type. And we synthesize all the information and apply it to the formula suggested in the paper to calculate the actual quantity of material pile. The superiority of the proposed method is demonstrated through experiments.

• Tunnel and Underground Space
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• v.19 no.3
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• pp.213-225
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• 2009

The purpose of the study is to evaluate the effects of chemical weathering on the granite and orthogneiss in Wonju area based on accelerated artificial chemical weathering. The rock samples were scrutinized the variation of index properties and ion exchanges caused by artificial chemical weathering which was implemented with leaching test for 170 days using double soxhlet extractor. The differential weathering and decrease of p wave velocity were obtained by weathering process without significant changes of porosity. In case of granite samples, the uniaxial compression strength was reduced by 20% and 16% for the F-grade and SW-grade, respectively. For MW-grade granite, however, was not able to examine the effect of strength reduction due to lack of sample number. Also, for orthogneiss, it is difficult to compare the values of uniaxial compressive strength between before and after the test because of its strong anisotropy.