Search

The decoration of graphene quantum dots enhances the NO2 gas sensing performance of SnO2 nanodomes by utilizing both electrical and chemical sensitization effects, leading to an impressive reduction in the theoretical detection limit.

Photo(electro)catalysis methods have drawn significant attention for efficient, energy-saving, and environmental-friendly organic contaminant degradation in wastewater. However, conventional oxide-based powder photocatalysts are limited to UV-light absorption and are unfavorable in the subsequent postseparation process. In this paper, a large-area crystalline-semiconductor nitride membrane with a distinct nanoporous surface is fabricated, which can be scaled up to a full wafer and easily retrieved after photodegradation. The unique nanoporous surface enhances broadband light absorption, provides abundant reactive sites, and promotes the dye-molecule reaction with adsorbed hydroxyl radicals on the surface. The superior electric contact between the nickel bottom layer and nitride membrane facilitates swift charge carrier transportation. In laboratory tests, the nanostructure membrane can degrade 93% of the dye in 6 h under illumination with a small applied bias (0.5 V vs Ag/AgCl). Furthermore, a 2 inch diameter wafer-scale membrane is deployed in a rooftop test under natural sunlight. The membrane operates stably for seven cycles (over 50 h) with an outstanding dye degradation efficiency (92%) and satisfied average total organic carbon removal rate (≈50%) in each cycle. This demonstration thus opens the pathway toward the production of nanostructured semiconductor layers for large-scale and practical wastewater treatment using natural sunlight.

A BaMoO4:[Er3+]/[Yb3+] up-conversion (UC) phosphor was synthesized by co-precipitation and calcination of the precursor at 800 °C. The main peak (112) for the synthesized phosphor was strongly detected in the XRD pattern and had a tetragonal structure. The doping of rare-earth ions affected the crystal lattice by shifting the main peak, decreasing the lattice constant, and shifting the position of the Raman signal. The synthesized upconverted phosphor exhibited strong green signals at 530 and 553 nm and weak red signals at 657 nm when excited at 980 nm. The green light emission intensity of the UC phosphor increased as the pump power of the laser increased due to the two-photon effect. The synthesized upconverted phosphor was prepared as a pellet and flexible composite. Thermal quenching led to a decrease in luminescence intensity as the temperature increased, which means that the phosphor can be applied to optical temperature sensing.

Our world is quickly moving towards the fourth industrial revolution including mobile, big data, AI, IoT, cloud computing, VR, etc. Recently, South Korea has been emphasizing convergence education to university. Thus, university has begun doing convergence education on their own by linking major subjects and liberal arts courses or linking different departments. In this paper, we analyzed learners’ satisfaction for operating convergence education effectively to increase education satisfaction and developed convergence curriculum and convergence skills required by society. for this study, a satisfaction survey is conducted for students majoring in engineering colleges. And the students’ experiences are collected through interviews and questionnaires for suggesting improved the convergence curriculum operation. We also did interviews and asked students about the meaning convergence education had for them, the impressions they had after taking the classes, and any opinions for further improvements. As a result of the analysis of student's satisfaction and satisfaction of convergence curriculum, it was analyzed as “approximately satisfied” with 3.6. Additionally, the correlation between student satisfaction and convergence curriculum satisfaction was analyzed, and the correlation coefficient showed a significant correlation with 0.732. In other words, it can be seen that students with high-student satisfaction are also highly satisfied with the convergence curriculum. Based on the result of the research and the student’s opinions, we would like to suggest that there should be subject development that is connected to careers or job searching for senior students, and additional research of practical educational methods are also needed.

We report the highly sensitive and selective downsized gas sensors for the IoT application. Sensing areas of Pt-interdigitated electrodes (IDEs) were varied to investigate the relation between sensing materials and electrodes. In2O3 nanocolumns were deposited on the pre-patterned Pt IDEs using glancing angle deposition (GLAD). The effect of the interface resistance between electrodes and sensing materials, and the intergrain resistance between nanocolumns is analyzed by linear regression at different sensing area and incident angle of GLAD. In2O3 (angle: 85°, sensing area: 0.3 mm × 0.3 mm) nanocolumns with double Schottky barriers show the highest response and selectivity with fast response time of 10 s to VOCs among the samples fabricated in this study. The analysis reveals that the intrinsic response of In2O3 (angle: 85°, sensing area: 0.3 mm × 0.3 mm) nanocolumns are dominantly affected by intergrain resistance, resulting in a high response. Our demonstration for the fundamental aspect of downsizing gas sensor makes an important contribution to the chemical sensor field with broad interest.

In the absence of concrete support plans for extra curriculum programs since the PRIME project has started, the College of Engineering has established regular courses to efficiently operate design programs. It links and operates creative-design curriculum by level: IT-engineering for freshman, basic creative design for sophomore, major creative design for junior, and integrated capstone design for senior. This study aims to find efficient operation and improvement plan for creative-design courses through the questionnaire survey and focused group interview (FGI) on the satisfaction of creative-design courses and the composition of the curriculum for students taking project-oriented creative-design courses. To this end, a survey and group interviews were conducted for 176 students taking creative-design courses, and the survey results and group interview results were analysed. As a result of the analysis, the absolute evaluation method was preferred, and a curriculum that could be done consequently rather than a short-term project. Satisfaction with the creative-design courses was higher in the upper grades than in the lower grades. In addition, when satisfaction for the creative-design courses is high, it showed positive recognition of the satisfaction for the curriculum of creative-design courses. In this paper, I propose four suggestions for efficient operation and improvement for creative-design courses; different goal-setting of creative-design courses at each level, an appropriate form of feedback, the fairness of team setting and evaluation methods, and the grade linkage for creative-design courses. Keywords— Engineering Curriculum; PBL; Higher Education; FGI; Survey.

Despite the growth of IoT technology and related markets, aspect of the IoT security in the IoT field is not handled correctly due to several factors such as indiscreet participation in the market, poor optimization for the various specifications. In this paper, an embedded anomaly packet detection system using machine learning technology for an IoT environment is proposed and evaluated. The suggesting system is composed of two main devices—the packet collection device and the packet analysis device. The packet collection device collects network packets from the IoT devices that are connected to the system. The packet analysis device detects anomalies from the packet data by using the machine learning model. Detected anomalies, which are mostly considered as intrusions such as new or bypassing HTTP attacks as well as existing attacks, are responded in real-time. For conformity assessment in a real-time environment, TPR, FPR, accuracy, and detection speed was measured, and the measured values of the target embedded board are 100%, 0.56%, 99.5, and 2.4 to 13.4 seconds, respectively. The results of TPR, FPR, and accuracy indicate the model itself has an excellent ability to discriminate between anomalies, but it is challenging to apply it to an embedded system in terms of detection speed. Future studies need to apply anomaly detection models that are more suitable for embedded devices and unique hardware accelerators for computing artificial neural networks.

Recently, apartment designs are tend to be changed from the standard pattern by many causes and the beam-column structures are getting popular instead of wall structure system. Therefore, for the effective use of planed space the heights of apartment are tend to be higher and higher. According to Korea Building Code, earthquake resistance designs or seismic design for those high rise apartments must be more attentive and accurate, especially, dynamic periods of structures must be exactly measured, because those are very important for equivalent static analysis. The important subject of this study is to investigate the safety factors and seismic performance for natural period of high rise buildings by comparing the natural periods getting from ambient vibration method with those of Korea Building Code.

내구성은 콘크리트 구조물의 안전성과 경제성에 직접적으로 연관되므로 매우 중요한 사항 인데, 최근 들어 콘크리트의 내구성에 사회적, 공학적 관심이 집중되면서 이에 대한 다양한 연구가 진행되고 있다. 콘크리트의 염해나 탄산화, 동결융해 등의 열화요인은 독립적이 아닌 복합적인 형태로 작용하게 되는데, 이러한 열화현상을 저감하는 한 방편으로 사용하는 플라 이 애쉬는 콘크리트 혼화재 중에서 사용빈도가 매우 높다. 또한 플라이 애쉬는 유동성 증진 을 통한 내구성의 향상과, 수화열 저감을 통한 균열감소 및 장기강도 증진 등의 효과가 있으 며, 시멘트를 대체하여 결합재로서 경제적인 효과를 유발하는 장점도 가지고 있다. 그러나 플라이 애쉬는 그 품질의 편차가 크고, 경우에 따라서 미연 탄소분에 의한 AE제 흡착 등으로 인하여 콘크리트의 내구성 및 강도를 저하시킬 수 있는 요소를 내포하고 있으므로 사용 시 주의가 필요하다. 본 연구에서는 다양한 치환율의 플라이 애쉬를 혼입한 콘크리트를 경화 전 후에 특성실험을 한 다음, 그 결과를 분석·고찰함으로써 열화를 저감하고, 내구성을 갖는 콘 크리트를 제조하기 위하여 혼화재 및 결합재로서의 적용성 및 타당성을 검증하고자 한다. 내구성 열화 탄산화 다양한 치환율 결합재 c 2014 Koea Society of Diaster Information All rights reserved 플라이애쉬 치환율을 고려한 콘크리트의 내구성에 관한 연구 A Study on the Concrete Durability by Fly Ash Replacement Ratio Dongbaek Kim, Kwangjae, Lee a Department of Civil, Safety&Environmental Engineering, Hnakyeong National University, 67 Seokjung dong, Kyeonggi 456-749, Republic of Korea b Department of Civil, Safety&Environmental Engineering, Hnakyeong National University, 67 Seokjung dong, Kyeonggi 456-749, Republic of Korea a Corresponding author. Tel. 82-10-2355-5143. Fax. 82-31-678-4674. Email. dbkim@hknu.ac.kr 1 Tel. 82-10-2355-5143. Email. dbkim@hknu.ac.kr 2 Tel. 82-10-2247-3470. Email. kjlee@hknu.ac.kr ARTICLE HISTORY Recieved Nov. 17, 2014 Revised Nov. 17, 2014 Accepted Dec. 01, 2014 Journal of Korea Society of Disaster Information Vol.10 No.4 ❙ pp. 566 571 Available online at www.sodi.or.kr 1976-2208 c 2014 Korea Society of Disaster Information All rights reserved. http://dx.doi.org/10.15683/kosdi.2014.10.4.566 D.B. Kim et al. Journal of Korea Society of Diaster Information Vol.10, No.4, pp.566 571, 2014

Handheld pointing devices are increasingly in demand in digital TV market to provide intuitive human-device interfaces (HDIs). HDIs with directional buttons, joysticks, and trackballs are not very intuitive owing to their limited motions. To overcome this problem, cameras, gyroscopes, or ultrasonic sensors have been incorporated into HDIs at the expense of higher power consumption. In this paper, a low-power intuitive pointing device is presented. The transmitter of the proposed device consists of a microcontroller, two infrared light-emitting diodes, and optical components. The receiver comprises a photodiode module and a motion estimation block. The proposed device reduces power consumption by 71.3% and 23.6% as compared with the conventional camera- and gyroscope-based HDIs, respectively. Test results and performance evaluations are presented for validation.

In this paper we present a system that enables the user to interact with large display system even without touching the screen. With two infrared sensitive cameras mounted on the bottom left and bottom right of the display system pointing upwards, the user fingertip position on the selected region of interest of each camera view is found using vertical intensity profile of the background subtracted image. The position of the finger in two images of left and right camera is mapped to the display screen coordinate by using pre-determined matrices, which are calculated by interpolating samples of user finger position on the images taken by pointing finger over some known coordinate position of the display system. The screen is then manipulated according to the calculated position and depth of the fingertip with respect to the display system. Experimental results demonstrate an efficient, robust and stable human computer interaction.

We present a surveillance camera architecture using a one-bit motion detection algorithm for portable applications. The conventional surveillance system requires too many components and is too complicated for portable applications. In this paper, we propose a simple surveillance camera architecture with a motion detector that can detect changes of an object within its surroundings for low-power and low-cost applications. The proposed motion-detection algorithm uses one-bit images which are selected using a binary search algorithm that is decided by varying the reference voltage. We verify all the functions of the motion detector through the use of a user interface program on an FPGA board. Experimental results are also presented1.

This paper proposes a low-complexity mobile display digital interface (MDDI) architecture. We implement and verify the proposed MDDI-host architecture on a system-on-chip (SoC) platform with a 32-bit RISC CPU and a FPGA module. As a result of verification, the gate count of the MDDI host is reduced by about 50 % compared to that of the conventional parallel interface. And the bandwidth per pin of the MDDI host is 3 times more than that of a conventional parallel interface. Furthermore, the MDDI host that we implement includes the advanced high-performance bus (AHB) interface. Therefore, the proposed MDDI architecture is suitable for SoC platforms .

A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique is used to make the highly porous structure such as nanocolumns (NCs) of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO2, WO3 and In2O3 NCs) is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides) (PVC) decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C), the resistances of the metal-oxide NCs are abruptly changed and SnO2 NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p-type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C). The response time of SnO2 NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection.