• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.21-26
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• 2020

An autonomous driving system is based on the deep learning system built by big data which are obtained by various IoT sensors. The miniaturization and high performance of the IoT sensors are needed for diverse devices including the autonomous driving system. Specially, the miniaturization of the sensors leads to compel the miniaturization of the fixer structures. In the viewpoint of the miniaturization, metallic structure is a best solution to attach the small IoT sensors to the main body. However, it is hard to manufacture the small metallic structure with a conventional machining process or manufacturing cost greatly increases. As one of solutions for the problems, in this work, metallic FDM (Fused depositon modeling) based on metallic filament was proposed and the FDM process was investigated to fabricate the small metallic structure. Final part was obtained by the post-process that consists of debinding and sintering. In this work, the relationship between infill rate and the density of the part after the post-process was investigated. The investigation of the relationship is based on the fact that the infill rate and the density obtained from the post-processing is not same. It can be said that this work is a fundamental research to obtain the higher density of the printed part.

• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.573-586
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• 2012

Point clouds acquired by a LIDAR(Light Detection And Ranging, also LADAR) system often contain erroneous points called outliers seeming not to be on physical surfaces, which should be carefully detected and eliminated before further processing for applications. Particularly in case of LIDAR systems employing with a Gieger-mode array detector (GmFPA) of high sensitivity, the outlier ratio is significantly high, which makes existing algorithms often fail to detect the outliers from such a data set. In this paper, we propose a method to discriminate outliers from a point cloud with high outlier ratio acquired by a GmFPA LIDAR system. The underlying assumption of this method is that a meaningful targe surface occupy at least two adjacent pixels and the ranges from these pixels are similar. We applied the proposed method to simulated LIDAR data of different point density and outlier ratio and analyzed the performance according to different thresholds and data properties. Consequently, we found that the outlier detection probabilities are about 99% in most cases. We also confirmed that the proposed method is robust to data properties and less sensitive to the thresholds. The method will be effectively utilized for on-line realtime processing and post-processing of GmFPA LIDAR data.

• 재활복지
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• v.20 no.4
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• pp.203-228
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• 2016

The purpose of this study was to find out the recent trend of high-tech AAC intervention studies for individuals with disabilities. Electronic database searches were completed to identify studies published between 2009 and 2016. 46 studies were identified for inclusion in this review. The studies were classified as participants, research design, intervention settings, independent variables, dependent variables, communication skills by High-tech device, type of high-tech AAC device. Across these studies, intervention was provided to total of 126 participants. Most participants are aged 6-11 and the most common diagnosis was autistic spectrum disorder. Most common study designs were multiple probe design and multiple treatment design. The majority of studies implemented interventions in a special education school(classroom) setting. The majority of studies implemented interventions to compare the effect of high-tech and low-tech AAC device interventions. The majority of targeted behavioral outcomes were communication skills. Tablet PC was the most frequently used for intervention in both domestic and foreign studies. The most common softwares were 'My talky' in domestic studies and 'Proloquo2Go' in foreign studies. The synthesis of evidence describing views of users and providers and the implementation of high-tech AAC device can provide valuable data to inform intervention studies and functional outcome measures. Suggestions for the future research are discussed.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.291-297
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• 2015

As promising future energy source, hydrogen has been drawing much attention; however, it is easily leaked from the small gap in any storage container due to its find molecule size. In this study, Laser induced breakdown spectroscopy(LIBS) was used for hydrogen leak detection, and feasibility of the scheme was evaluated based on different way for plasma generation. Laser power of 295 mW was required for generating plasma on metal surface to measure hydrogen atomic emission while approximately 2.5 times higher laser power was needed for plasma formation directly in the hydrogen gas stream. It was shown that peak to base ratio increased linearly with increasing the concentration of hydrogen. It can be concluded that LIBS is a viable technique for hydrogen sensing when the concentration of hydrogen is less than 5%.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.130.2-130.2
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• 2010

한전 전력연구원에서는 2009년 12월부터 125 kW급 용융탄산염 연료전지 발전시스템의 성능평가를 위한 운전이 진행되고 있다. 현재 진행 중인 "250 kW급 열병합 용융탄산염 연료전지 Proto Type개발" 과제의 최종시작품인 250 kW급 발전시스템은 125 kW급 MCFC 스택 2기로 설계되어, 125 kW급 시스템의 시험운전은 매우 중요한 기술적 성과가 될 것이다. 현재 125 kW급 MCFC 스택은 10,000 $cm^2$의 유효전극면적을 갖는 단위전지들로 구성되었으며, 적층 스택의 온도 및 농도분포의 최적화를 위해 내부 매니폴드 및 Co-flow Type 열교환기 기반의 분리판을 개발 적용하였다. 연료극의 전극 구성은 Ni-Al alloy로, 공기극의 전극 구성은 Lithiated-NiO로 이루어졌다. 그리고 매트릭스는 ${\alpha}-LiAlO_2$로 제작되었고, 전해질은 Li과 K Carbonate가 68 : 32 비율로 섞인 용융염을 사용하였다. 본 125 kW급 용융탄산염 연료전지 시스템의 운전평가는 고적층 스택의 온도 및 농도 분포를 확인하고, 최적화된 스택 운전 조건을 도출하는 것을 그 목적으로 하고 있다. 125kW급 스택 1기의 규모의 주변기기 시스템은 외부개질기, 촉매연소기, 이젝터, 고온순환 블로어 및 공기블로어 등으로 이루어져 있다. 고온형 연료전지 시스템에서 연료극과 공기극의 균일한 온도 및 압력 확보는 매우 중요하며, 이를 위하여 외부개질기 및 촉매연소기 연동을 통한 온도편차를 최소화하고, 기존 고온용 순환 블로어 대신 이젝터를 개발 도입하여 압력균형을 조절하였다. 125kW급 MCFC 시스템은 2009년 12월부터 전처리 운전을 시작하여 2010년 1월 말부터 PCS로 전기를 생산하고 있다. 평균전압 0.83V에서 100kW의 출력을 기록하였으며, 피크부하 120 kW, 누적출력량 30 MWh를 초과달성하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.721-728
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• 2009

Equal/unequal 4-way power divider suitable for satellite communication using SIW technology is presented in this paper. The control of positions of guiding posts provides equal or unequal power division ratios by maintaining the width of the SIW unchanged. In addition, the detailed descriptions for the proposed power divider include the general characteristics of radial waveguide, feeding part using coaxial cable, simple SIW structure, power-guiding posts, and transition for measurement. The comparison between the simulated and measured data shows a good agreement at a center frequency of 10 GHz. The measured input impedance bandwidths for equal and unequal power divisions are about 2.1 GHz and 3 GHz under the condition of less than VSWR 2:1, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.337-343
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• 2020

The third phase of NASA's 3D-Printed Habitat Challenge (part of a NASA's Centennial Challenges Program competition) required entrants to build a one-third-scale space exploration habitat (10 ㎡) using 3D-printing technology. This study addresses a proposed habitat (diameter: 3 m, height: 2 m) in accordance with the competition rules. The study focus is to find the most appropriate binder when KOHLS-1 was mixed for extruding and stacking as 3D printing feedstock using pellets, and to build a prototype structure as required by the competition. Unlike previous studies, this study was based around the binders and construction method, not around axis transfer velocity, flow rate, and heater temperature.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.65-71
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• 2016

Quantum-dot cellular automata (QCA) consists of nano-scale cells and demands very low power consumption so that it is one of the alternative technologies that can overcome the limits of scaling CMOS technologies. Typical BCD-EXCESS 3 code converters using QCA have not considered the scalability so that the architectures are not suitable for a large scale circuit design. Thus, we design a BCD-EXCESS 3 code converter with scalability using QCADesigner and verify the effectiveness by simulation. Our structure have reduced 32 gates and 7% of garbage space rate compare with typical URG BCD-EXCESS 3 code converter. Also, 1 clock is only needed for circuit expansion of our structure though typical QCA BCD-EXCESS 3 code converter demands 7 clocks.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.893-898
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• 2014

A direct pulsed laser process for welding and networking silver nanowires was developed. The welded nanowire network demonstrated modified electrical properties in a transparent substance. In particular, the welding points on the nanowires were investigated to measure the resistance at the connections. The level of networking in nanowires was explored with respect to various laser pulse widths and average power densities. In particular, the influence of laser beam density was investigated in detail. Selective laser treatment can be advantageous in imparting customized local property changes in transparent conducting materials. Various applications of the process are also discussed in this paper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.827-832
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• 2013

In this study, curve responsiveness was assessed based on the lateral force and running safety was evaluated based on the wheel unloading ratio and derailment coefficient, which is the ratio of the wheel load and the lateral force. The evaluation of the curving performance and running safety of the new high-power electric locomotive showed that the derailment coefficient appeared higher when the wheel-set was set to the front of the train instead of being placed backward, and the maximum value of the derailment coefficient was recorded as 0.572 on the Gyeongbu line. Furthermore, the lateral force increased in curved sections, and it appeared to be proportional to the curve radius. Meanwhile, a maximum axis lateral force of 77.6 kN was recorded on the Taebaek line, and the wheel unloading ratio was 47.6% on the Yeongdong line. Finally, the running safety at the maximum speed as well as the through-curve performance of the curve radius satisfied the required standards.