• 센서학회지
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• 제8권1호
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• pp.53-62
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• 1999

MEMS(Microelectromechanical System) 기술분야에서 폭넓게 사용하고 있는 폴리실리콘 박막을 이용하여 폴리실리콘 미소 공진 구조체를 제작하였다. 폴리실리콘 증착은 저압기상화학증착 장비를 사용하여 대칭적 두께로 박막을 적층하였고 폴리실리콘의 응력과 응력구배를 최소화시키기 위한 적층, 도핑 방법 및 열처리에 따른 특성을 분석하였다. 이를 위하여 브리지 빔과 캔티레바 테스트 패턴을 제작하여 기계적 응력 특성을 측정하였으며, 아울러 공정 조건별 개별 시료에 대한 물성을 XRD, SIMS등으로 분석하였다. 공진 구조체는 대칭적 증착 구조를 가지며, 최종적으로 $6.5{\mu}m$의 두께로 적층되었다. 제작된 평면형 공진 구조체의 진동특성은 직류 15V, 교류 0.05V의 구동전압, 1000mtorr 압력에서 공진 진폭이 $5{\mu}m$ Q값이 1270임을 보였으며, 개발된 마이크로 폴리실리콘 공진체는 마이크로 자이로 및 가속도 센서에 응용될 수 있다.

• 콘크리트학회논문집
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• 제13권2호
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• pp.184-191
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• 2001

최근 급속한 산업화 및 생활수준의 향상에 따라 폐유리의 발생량이 급격히 증대하고 있으며 이중 대부분은 재활용되지 못하고 최종처분 되고 있어 심각한 자원낭비 및 환경오염문제를 야기하고 있다. 따라서 본 연구에서는 국내에서 발생되고 있는 폐유리중 대표적인 갈색, 녹색, 무색 폐유리 및 이들을 혼합한 폐유리를 파쇄하여 콘크리트용 잔골재로서의 재활용 가능성을 분석하기 위한 기초적 실험연구를 수행하였다. 시험결과 슬럼프 및 다짐계수는 폐유리 잔골재의 입형이 모가나고 각이져 있고 상대적으로 유리입도가 잔골재보다 크기때문에 감소하였으며, 공기량은 폐유리 잔골재가 0.6mm이상의 입자를 많이 함유하고 있어 증가하는 것으로 나타났다. 또한 압축강도, 인장강도, 휨강도는 폐유리 잔골재의 혼입량이 많아질수록 감소하였으며, 적정 혼입률은 30% 이하가 바람직하고 유동성 확보를 위해서는 적정한 혼화제를 사용해야 한다는 결론을 얻을 수 있었다.

• 한국식품영양과학회지
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• 제38권6호
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• pp.750-756
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• 2009

기능성 소재로서의 버찌분말의 이용가능성을 알아보기 위해 버찌분말을 0, 3, 5, 7 및 10% 첨가한 머핀을 제조하여 품질특성을 조사하였다. 머핀의 물성은 버찌분말의 첨가에 따라 경도(hardness)는 증가하였고 검성(gumminess) 및 씹힘성(chewiness)은 감소하였다. 색도는 첨가량이 증가할수록 빵껍질(crust)과 빵속(crumb)에서 명도와 황색도가 감소하고 적색도는 증가하였다. 또한 버찌 분말의 농도가 증가함에 따라 항산화 활성이 증가하였다. 관능검사 결과 버찌분말첨가 머핀에서 색, 향, 맛, 부드러움, 촉촉함, 전체적인 기호도면에서 무첨가구에 비해 전반적으로 높게 평가되었으며, 전체적인 기호도는 5% 첨가구에서 가장 높은 점수를 나타내었다. 이러한 결과로 볼 때 머핀의 품질 및 관능 특성, 기능성을 고려한 버찌분말 첨가량은 5% 첨가구가 최적 조건일것으로 판단되었다.

• 산업경영시스템학회지
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• 제43권4호
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• pp.161-167
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• 2020

In the process of cutting large aircraft parts, the tool may be abnormally worn or damaged due to various factors such as mechanical vibration, disturbances such as chips, and physical properties of the workpiece, which may result in deterioration of the surface quality of the workpiece. Because workpieces used for large aircrafts parts are expensive and require strict processing quality, a maintenance plan is required to minimize the deterioration of the workpiece quality that can be caused by unexpected abnormalities of the tool and take maintenance measures at an earlier stage that does not adversely affect the machining. In this paper, we propose a method to indirectly monitor the tool condition that can affect the machining quality of large aircraft parts through real-time monitoring of the current signal applied to the spindle motor during machining by comparing whether the monitored current shows an abnormal pattern during actual machining by using this as a reference pattern. First, 30 types of tools are used for machining large aircraft parts, and three tools with relatively frequent breakages among these tools were selected as monitoring targets by reflecting the opinions of processing experts in the field. Second, when creating the CNC machining program, the M code, which is a CNC auxiliary function, is inserted at the starting and ending positions of the tool to be monitored using the editing tool, so that monitoring start and end times can be notified. Third, the monitoring program was run with the M code signal notified from the CNC controller by using the DAQ (Data Acquisition) device, and the machine learning algorithms for detecting abnormality of the current signal received in real time could be used to determine whether there was an abnormality. Fourth, through the implementation of the prototype system, the feasibility of the method proposed in this paper was shown and verified through an actual example.

• 한국조리학회지
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• 제18권1호
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• pp.54-64
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• 2012

이 연구의 목적은 익힌 자색고구마를 떡에 활용하여 향미와 질감이 향상되고 소비자의 기호에 맞는 기능성 설기떡을 제조, 개발하고자 하는데 있다. 설기떡에 익힌 자색고구마의 함량을 0, 10, 20, 30, 40% 첨가하여 수분함량, 색도, 텍스처, 관능검사를 실시하였다. 수분함량은 40.83% - 44.91% 이었다. 익힌 자색고구마의 첨가량이 증가할수록 명도와 황색도는 감소하였고, 적색도는 증가하였다. 익힌 자색고구마의 첨가량이 증가할수록 경도, 부착성, 탄력성, 검성은 유의적으로 차이를 보이지 않았고, 씹힘성만 유의적인 차이를 보였다. 관능검사 결과 색, 냄새, 맛, 촉촉함은 익힌 자색고구마의 첨가량이 증가할수록 유의적으로 높아졌다. 설기떡에 40% 익힌 자색고구마를 첨가한 것이 종합적인 기호도가 가장 높았고, 저장기간에 따른 경도 변화도 적었다.

• Journal of Biosystems Engineering
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• 제35권4호
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• pp.244-249
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• 2010

This study was conducted to define the optimal Lycium chinense miller washing method for developing the Lycium chinense cleaner and we analyzed the Lycium chinense miller washing characteristics for removing pesticides and microorganism according to washing methods; habitual washing method, air bubble washing method and nozzle spray washing method. The results were summarized as follows; 1. In case of measuring physical properties according to the varieties, maximum yield strength of Hokwang was 2.562 kgf, minimum yield strength of Hokwang was 0.269 kgf and average yield strength was about 1 kgf. 2. In case of measuring change of bacteria according to washing methods, the number of bacteria of non-washing method was more than the number of bacteria of habitual washing method or mechanical washing method and the number of nozzle spray washing method was least. 3. Ahjoksiseuteurobin of 0.218 ppm was detected in the untreated sample, 0.051 ppm was detected in the habitual washing method, 0.047 ppm was detected in the air bubble washing method and 0.034 ppm was detected in nozzle spray washing method. Every amount detected were less than 2 ppm that is reference value and the detected amount was least in case of nozzle spay cleaning method. Cypermethrin of 0.772 ppm was detected in the non-cleaned sample, 0.089ppm was detected in habitual washing method, 0.26 ppm was detected in the air bubble washing method and 0.292 ppm was detected in the nozzle spray washing method. Every detected amount of Cypermethrin were less than 5 ppm that is reference value and the detected amount was least in case of habitual washing method.

• 복합신소재구조학회 논문집
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• 제5권1호
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• pp.1-8
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• 2014

Pultruded glass fiber reinforced polymeric plastic (PFRP) and FRP member manufactured by sheet molding compound (SMC) have superior mechanical and physical properties compared with those of conventional structural materials. Since FRP has an excellent corrosion-resistance and high specific strength and stiffness, the FRP material may be highly appreciated for the development of floating-type photovoltaic (PV) power generation system. In this paper, advanced floating PV generation system made of PFRP and SMC is designed. In the design, it includes tracking solar altitude by tilting photovoltaic arrays and tracking solar azimuth by spinning structures. Moreover, the results of the finite element analysis (FEA) are presented to confirm stability of entire structure under the external loads. Additionally, installation procedure and mooring systems in the Hap-Cheon Dam are discussed and the measurement of strain under the actual circumstances is conducted for assuring stability of actually installed structures. Finally, by comparison with allowable stress, appropriate safety of structure is confirmed to operate the system.

• 한국재료학회지
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• 제24권5호
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• pp.236-242
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• 2014

Fabrication of reaction-bonded $Al_2O_3$ (RBAO) ceramics using Al-Zn-Mg alloy powder was studied in order to improve traditional RBAO ceramic processing using Al powder. The influence on reaction-bonding and microstructure, as well as on physical and mechanical properties, of the particulate characteristics of the $Al_2O_3$-Al alloy powder mixtures after milling, was revealed. Variation of the particulate characteristics of this $Al_2O_3$-Al alloy powder mixture with milling time was reported previously. To start, the $Al_2O_3$-Al alloy powder mixture was milled, reaction-bonded, post-sintered, and characterized. During reaction-bonding of the $Al_2O_3$-Al alloy powder mixture compacts, oxidation of the Al alloy took place in two stages, that is, there was solid- and liquid-state oxidation of the Al alloy. The solid-state oxidation exhibited strong dependence on the density of surface defects on the Al-alloy particles formed during milling. Higher milling efficiency resulted in less participation of the Al alloy in reaction-bonding. This was because of its consumption by chemical reactions during milling, and subsequent powder handling, and could be rather harmful in the case of over-milling. In contrast to very little dependence of oxidation of the Al alloy on its particle size after milling, the relative density, microstructure, and flexural strength were strongly dependent on particle size after milling (i.e., on milling efficiency). The relative density and 4-point flexural strength of the RBAO ceramics in this study were ~98% and ~365 MPa, respectively, after post-sintering at $1,600^{\circ}C$.

• Elastomers and Composites
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• 제54권1호
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• pp.54-60
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• 2019

The rapid development of the automobile industry is an important factor that led to the dramatic development of synthetic rubber. The tread part of tire that comes in direct contact with the road surface is related to the service life of the tire. Rubber compounds used in tire treads are often blended with SBR (styrene-butadiene rubber) and BR (butadiene rubber) to satisfy physical property requirements. However, when two or more kinds of rubber are blended, phase separation and silica dispersion problems may occur due to non-uniform mixing of the rubber. Therefore, in this study, we synthesized an SBR copolymer with the same composition as that of a typical SBR/BR blend compound by controlling butadiene content during ESBR (emulsion styrene-butadiene rubber) synthesis. Subsequently, silica filled compounds were manufactured using the synthesized ESBR, and their mechanical properties, dynamic viscoelasticity, and crosslinking density were compared with those of the SBR/BR blended compound. When the content of butadiene was increased in the silica filled compound, the cure rate accelerated due to an increased number of allylic positions, which typically exhibit higher reactivity. However, the T-2 compound with increased butadiene content by synthesis less likely to show an increase in crosslink density due to poor silica dispersion. In addition, the T-3 compound containing high cis BR content showed high crosslink density due to its monosulfide crosslinking structure. Because of the phase separation, SBR/BR blend compounds were easily broken and showed similar $M_{100%}$ and $M_{300%}$ values as those of other compounds despite their high crosslink density. However, the developed blend showed excellent abrasion resistance due to the high cis-1,4 butadiene content and low rolling resistance due to the high crosslink density.

• 콘크리트학회논문집
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• 제19권6호
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• pp.727-734
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• 2007

철근과 fiber-reinforced polymer (FRP)의 물리적, 역학적 특성의 차이 및 슬래브 상부 보강재의 기둥 인접부 집중 배근, 그리고 기둥 인접부 슬래브에 강섬유 콘크리트 (SFRC)의 타설 등에 따른 2방향 슬래브의 펀칭 전단 거동에 대한 효과를 평가하였다. 펀칭 전단강도, 강성, 연성, 변형률 분포 그리고 균열 제어 성능 등을 파악하였다. 실험 결과 기둥 인접부의 슬래브에 집중 배근을 하거나 SFRC를 타설하는 것은 glass fiber-reinforced polymer (GFRP) 바로 보강된 슬래브의 펀칭 전단 거동을 향상시켰다. 기둥 인접 구역에 집중 배근된 슬래브의 실험 결과를 다양한 설계기준과 타 연구자에 의해 제안된 예측식과 비교하였으며, 집중 배근으로 인한 이점을 예측식에 반영할 수 있도록 집중 배근된 슬래브의 철근비를 산정하는 합리적인 방법도 제안하였다.