• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.304-305
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• 2018

최근 Industrial-IoT(IIoT) 솔루션은 2016년 기준 최대 55%를 차지하였고, 기술 혁신과 다양한 신규 비즈니스 모델이 개발되고 있다. 본 논문에서는 IIoT 디바이스를 다양한 환경에서 적용하고, 손쉽게 센서를 추가/변경/삭제하기 위해 블록형 IIoT 디바이스 연동이 가능한 온톨로지 시스템을 구현한다. 제안된 시스템은 IIoT 디바이스, 블록형 모듈과 온톨로지 서버로 구성되어있다. IIoT 디바이스에 블록형 모듈이 연결되면 온톨로지 서버를 통해 적합한 드라이버를 설치하고, 펌웨어를 다운로드한다. 블록이 추가/변경/삭제되어도 자동으로 업데이트가 가능하다. 실험을 통해 서버의 정상 구동과 소프트웨어의 업데이트 및 다운로드가 정상적으로 구현되는 것을 확인하였다.

• Journal of Biosystems Engineering
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• 제41권1호
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• pp.21-33
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• 2016

Purpose: In order to ensure that vegetable seedlings (with a soil block around their roots) are planted in an upright orientation after metering in a vegetable transplanter, they need to be dropped freely from a certain height. The walk-behind hand-tractor-powered machines do not have sufficient space to drop the seedlings from that height. In the present work, a hopper-type planting device was developed for the walk-behind hand-tractor-powered vegetable transplanter to ensure that the soil block seedlings are planted in an upright orientation. Methods: Various dimensionless terms were developed based on the dimensional analysis approach, and their effect on the planting of soil block seedlings in an upright orientation (planting efficiency) was studied. The optimum design dimensions of the hopper-type planting device were identified by the Taguchi method of optimization. Results: The ratio of the height of free fall to the sliding distance of the seedling on the surface of the hopper had the highest influence on planting efficiency. The planting efficiency was highest for plants with a height $15{\pm}2cm$. The plant handling Froude number, in interaction with the design of the hopper-type planting device, also significantly affected the planting efficiency. Of the hopper design factors, the length of the slide of the seedlings on the surface of the hopper was most important, and induced sufficient velocity and rotation to cause the seedling to fall in an upright orientation. An evaluation of the performance of the planting device under actual field conditions revealed that the planting efficiency of the developed planting device was more than 97.5%. Conclusions: As the seedlings were fed to the metering device manually, an increase in planting rate increased missed plantings. The planting device can be adopted for any vegetable transplanter in which the seedlings are allowed to drop freely from the metering device.

• 한국기계가공학회지
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• 제15권3호
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• pp.52-57
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• 2016

A swash plate-type piston pump is a device used to discharge hydraulic fluid as the volume generated through the piston moves in the direction of the slope by adjusting the angle of its swash plate. In addition, the valve block internalized in the pump includes a flow path for intake from outside, a flow path for discharge, and a pilot conduit line to control discharge pressure and flux. In this study, a numerical analysis is conducted to improve the cracking of the valve block generated during process testing, and the developed pump is evaluated.

• International Journal of Aeronautical and Space Sciences
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• 제8권2호
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• pp.121-125
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• 2007

In late 1960's, engineers of the engine manufacturer experienced that the distortion of inlet flow of turbofan and turbojet engine could cause the surge in compressor and affect overall engine operational performance, which result in the deterioration of stability of the engine. In this study, block type of inlet distortion simulating device has been developed in order to investigate the effect of inlet distortion on the deterioration of overall engine operational performance. The inlet distortion simulating device was installed in front of engine inlet in order to simulate distortion of inlet flow. The degree of inlet distortion was measured by rakes installed upstream the inlet distortion simulating device and between the engine inlet and inlet distortion simulating device. Before applying the inlet distortion simulating device to real engine, preliminary tests were performed with a simulated engine in order to verify the degree of inlet distortion by the device. Preliminary inlet distortion tests were performed in Altitude Engine Test Facility(AETF) of Korea Aerospace Research Institute(KARI) and results showed that the inlet distortion simulating device could be used in simulating various inlet distortion cases.

• 한국지반신소재학회논문집
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• 제8권3호
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• pp.45-52
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• 2009

최근 국내에서는 시공성 및 경제성이 우수하고, 수려한 경관을 연출할 수 있는 보강토옹벽의 적용이 급증하고 있는 추세이다. 일반적으로 블록식 보강토옹벽 시공시 전면블록과 보강재 사이의 연결은 블록에 미리 형성시킨 돌기(전단키형 방식) 또는 플라스틱 핀(핀형 방식)을 이용하여 보강재를 블록에 정착시키는 방식으로 이루어지고 있다. 그러나 이와 같은 연결방식은 시공중 보강재에 부분적인 손상의 원인이 되며, 이로 인해 보강토옹벽의 안정성에 문제를 야기시킬 수 있다. 따라서 본 연구에서는 기존 연결방식의 문제점을 해결하고자, 안정성을 보다 높이고 경제성은 기존 방식과 유사한 I형 연결장치를 이용한 전면블록/지오그리드 보강재의 연결방법을 개발하였으며, 현장 적용을 위하여 연결강도 특성을 평가하였다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.312-312
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• 2006

Block copolymers with well-defined nanoscopic structures have recently gained much attention for their potential uses as functional nanostructures. Here, we show that nanoporous templates made from polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA) satisfy a novel design concept. At first, arrays of nanoscopic cylindrical microdomains oriented normal to the surface can easily be prepared. Then, we fabricated ultra high density arrays of conducting polymer as poly(pyrrole) (Ppy) and poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires with diameters of $25{\sim}40\;nm$ on the ITO glass by electropolymerization of the monomers inside nanoholes. These high density arrays of conducting polymer nanowires could be used as P-type materials for photovoltaic devices.

• 대한임베디드공학회논문지
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• 제13권5호
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• pp.235-243
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• 2018

NAND flash memory has been widely used for embedded systems as storage device and the flash memory file systems such as JFFS2, YAFFS/YAFFS2 have been adopted by these embedded systems. The flash memory file systems provide the high performance and overcome the limitations of flash memory. However, these file systems don't solve the slow mount time problem when a sudden power failure happens. In this paper, we proposed a flash memory management method for enhancing the recovery performance. The proposed method manages the flash memory block type and stores the block type information at recovery image block. When file operations are occurred, our method stores the file information at the metadata block before and after the file operation. When mounting the flash memory, our method only scans the recovery image blocks and metadata blocks. The proposed method reduces the mount time by seeking the metadata block locations fast by using the recovery image blocks. We implemented the proposed method and evaluation results show that our method reduces the mount time 13 ~ 46 % compared with YAFFS2.

• 대한방사선기술학회지:방사선기술과학
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• 제40권1호
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• pp.49-55
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• 2017

의료기관 내 핵의학 종사자는 방사성동위원소 취급 시 사용하는 선원의 종류, 방사능량, 차폐기구의 사용 여부에 따라 종사자 개인별로 광범위한 피폭선량을 나타낼 수 있다. 이에 본 연구에서는 몬테카를로 기법을 기반으로 한 모의실험을 통해 진단용 방사선원 취급 시 종사자의 장기별 선량평가와 L-block 차폐기구 사용에 따른 선량감소효과를 분석하였다. 그 결과, 방사선원의 취급 위치에 근접할수록 높은 장기선량 분포를 나타내었고, ICRP 조직가중치에 따라 유효선량 분포가 상이한 양상을 보였다. 또한 L-block 두께에 따른 선량감소효과는 차폐두께 증가에 따라 지수함수 분포로 감소되는 경향을 나타내었으며, 방사선원별 선량감소효과는 방출하는 감마선 에너지에 비례하여 낮은 차폐효과를 보였다.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.27-35
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• 2021

NAND flash memory-based SSD needs an internal software, Flash Translation Layer(FTL) to provide traditional block device interface to the host because of its physical constraints, such as erase-before-write and large erase block. However, because useful host-side information cannot be delivered to FTL through the narrow block device interface, SSDs suffer from a variety of problems such as increasing garbage collection overhead, large tail-latency, and unpredictable I/O latency. Otherwise, the new type of SSD, open-channel SSD exposes the internal structure of SSD to the host so that underlying NAND flash memory can be managed directly by the host-level FTL. Especially, I/O data classification by using host-side information can achieve the reduction of garbage collection overhead. In this paper, we propose a new scheme to reduce garbage collection overhead of open-channel SSD by separating the journal from other file data for the journaling filesystem. Because journal has different lifespan with other file data, the Write Amplification Factor (WAF) caused by garbage collection can be reduced. The proposed scheme is implemented by modifying the host-level FTL of Linux and evaluated with both Fio and Filebench. According to the experiment results, the proposed scheme improves I/O performance by 46%~50% while reducing the WAF of open-channel SSDs by more than 33% compared to the previous one.

• Korean Circulation Journal
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• 제53권3호
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• pp.134-150
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• 2023

Ventricular septal defects (VSDs) are the most common kind of congenital heart disease and, if indicated, surgical closure has been accepted as a gold-standard treatment. However, as less-invasive methods are preferred, percutaneous device closure has been developed. After the first VSD closure was performed percutaneously by Lock in 1988, both techniques and devices have developed consistently. A perventricular approach for closure of muscular VSD in small patients and the closure of perimembranous VSD using off-label devices are key remarkable developments. Even though the Amplatzer membranous VSD occluder (Abbott) could not be approved for use due to the high complete atrioventricular conduction block rate, other new devices have shown good results for closure of perimembranous VSDs. However, the transcatheter technique is slightly complicated to perform, and concerns about conduction problems after VSD closure with devices remain. There have been a few reports demonstrating successful closure of subarterial-type VSDs with Amplatzer devices, but long-term issues involving aortic valve damage have not been explored yet. In conclusion, transcatheter VSD closure should be accepted as being as effective and safe as surgery but should only be performed by experienced persons and in specialized institutes because the procedure is complex and requires different techniques. To avoid serious complications, identifying appropriate patient candidates for device closure before the procedure is very important.