• Korean Journal of Food Science and Technology
• /
• v.34 no.6
• /
• pp.1002-1006
• /
• 2002

Germination method was used to screen the biological changes in soybean, kidney bean, and red bean caused by gamma irradiation. Beans were irradiated at 0.1, 0.3, 0.5, 0.7, and 1.0 kGy. Ten beans of each sample were placed on moistened cotton and germinated at $30{\circ}C$. The root lengths were measured daily for 5 days. Root lengths of all beans grew continuously for 5 days, but the growth rate of irradiated beans decreased significantly from fourth day. Unirradiated beans showed the highest growth rate during 5 days of germination. Gamma-irradiated beans could be screened by measuring the daily growth rate and root length during germination.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.839-841
• /
• 2015

본 연구에서는 비대칭 이중게이트 MOSFET의 채널길이와 채널두께의 비에 따른 드레인 유도 장벽 감소 현상의 변화에 대하여 분석하고자한다. 드레인 전압이 소스 측 전위장벽에 영향을 미칠 정도로 단채널을 갖는 MOSFET에서 발생하는 중요한 이차효과인 드레인 유도 장벽 감소는 문턱전압의 이동 등 트랜지스터 특성에 심각한 영향을 미친다. 드레인 유도 장벽 감소현상을 분석하기 위하여 포아송방정식으로부터 급수형태의 전위분포를 유도하였으며 차단전류가 $10^{-7}A/m$일 경우 비대칭 이중게이트 MOSFET의 상단게이트 전압을 문턱전압으로 정의하였다. 비대칭 이중게이트 MOSFET는 단채널효과를 감소시키면서 채널길이 및 채널두께를 초소형화할 수 있는 장점이 있으므로 본 연구에서는 채널길이와 두께 비에 따라 드레인 유도 장벽 감소를 관찰하였다. 결과적으로 드레인 유도 장벽 감소 현상은 단채널에서 크게 나타났으며 하단게이트 전압, 상하단 게이트 산화막 두께 그리고 채널도핑 농도 등에 따라 큰 영향을 받고 있다는 것을 알 수 있었다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.5
• /
• pp.1915-1933
• /
• 2013

In this study, the virtual fixed point analysis and 3D fully modeling analysis for bent pile structures are conducted by considering various influencing factors and the applicability of the virtual fixed point theory is discussed. Also, the optimized column-pile length ratio is analyzed for supplementing virtual fixed point design and examining a more exact behavior of bent pile structures by taking into account the major influencing parameters such as pile length, column and pile diameter, reinforcement ratio and soil conditions. To obtain the detailed information, the settlement and lateral deflection of the virtual fixed point theory are smaller than those of 3D fully modeling analysis. On the other hand, the virtual fixed point analysis overestimates the axial force and bending moment compared with 3D fully modeling analysis. It is shown that the virtual fixed point analysis cannot adequately predict the real behavior of bent pile structures. Therefore, it is necessary that 3D fully modeling analysis is considered for the exact design of bent pile structures. In this study, the emphasis is on quantifying an improved design method (optimized column-pile length ratio) of bent pile structures developed by considering the relation between the column-pile length ratio and allowable lateral deflection criteria. It can be effectively used to perform a more economical and improved design of bent pile structures.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.16 no.5
• /
• pp.1-11
• /
• 2012

In this paper, non-linear analysis was performed for Reinforced Concrete (RC) walls using different macroscopic models subjected to cyclic loading, and the analytical results were compared with previous experimental studies of RC walls. ASCE41-06 (American Society of Civil Engineers) specifies that the hysteresis behaviors of RC walls are different due to the aspect ratio of the walls. For a comparison between analytical and experimental results, a slender wall with an aspect ratio exceeding 3.0 and a squat wall with an aspect ratio of 1.0 were selected among previous research works. For the non-linear analysis, each test specimen was modeled using two different macroscopic methods: the first representing the flexural behavior of the RC wall, and the second considering the diagonal shear in the web of the wall. Through nonlinear analysis of the considered RC walls, the analytical difference of a slender wall was negligible due to the different macroscopic modeling methods. However, the squat wall was significantly affected by the considered components of the modeling method. For an accurate performance evaluation of the RC building with squat walls, it would be reasonable to use a macroscopic model considering diagonal shear.

• Journal of Korea Water Resources Association
• /
• v.48 no.11
• /
• pp.879-889
• /
• 2015

The pattern of headward erosion at tributary and the separation zone formation in a loosed bed at confluence according to the confluence angle, discharge ratio, and dredging depth ratio have been analyzed. The separation zone is defined the inside of zero velocity boundary at downstream of confluence. The limit of separation zone occurrence is presented with dredging depth ratio. The propagation length of knickpoint increases as the confluence angle, discharge ratio, and dredging depth ratio increase in general and its regression equation has been suggested. The length and width ratios of separation zone in a loosed bed increase as discharge ratio and confluence angle increase as well as in a fixed bed. The length ratio decreases and the width ratio increases as dredging depth ratio increases results in great increase of shape factor and backwater rise by the conveyance reduction at confluence. The regression equation of shape factor with confluence angle, discharge ratio, and dredging depth ratio has been suggested.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.97-100
• /
• 2005

우리는 페이딩 환경에서 비동기 블록 수신 CPFSK에 적용되는 TCM의 성능을 분석하였다. 여기서 비동기 블록 수신기는 N개의 심볼을 하나의 블록으로 취급하여 비동기 복조를 수행한다. 일반적으로 이러한 블록 수신 방식은 관찰 블록의 길이가 길어질수록 더 좋은 성능을 나타낸다. 그러나 페이딩의 응집 시간이 수신기의 관찰 블록 길이 보다 작아지면, 블록 수신기의 오류 성능은 매우 나빠지게 된다. 본 논문에서는 페이딩의 응집 시간이 수신기의 관찰 블록 시간 NT(여기서, T는 심볼 시간)보다 큰 환경을 저속 페이딩 환경 이라고 하고, 그렇지 않은 환경을 고속 페이딩 환경이라고 정의하여, 각각의 환경에서 시스템의 성능을 분석하였다. 그 결과 고속 페이딩 환경에서 비동기 블록 수신기의 사용은 오류 층(error floor) 현상을 초래한다는 사실을 알 수 있었다. 따라서 고속 페이딩 환경에서는 수신기의 관찰 블록 길이를 짧게 하는 것이 더 좋다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.8
• /
• pp.645-651
• /
• 2015

The objective of this study is to experimentally investigate the effect of design parameter on the mass ratio of a central-driven ejector. The design parameters are the primary nozzle area and distance ratios, diffuser exit-area ratio and mixing-tube length ratio. The experimental setup was an open-loop continuous circulation system which has a movable nozzle ejector, an electric motor-pump, a water tank, a control panel and high-speed camera unit. We calculated the mass ratio using the measured primary and suction-flow rates with the experimental parameter of primary water-flow rate or pressure. The results showed that the mass ratio increased with the primary nozzle distance ratio and mixing tube length ratio, while the mass ratio decreased with the primary nozzle-area ratio and diffuser exit-area ratio.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.9-13
• /
• 2017

본 연구에서는 실내실험을 통하여 보의 경사변화에 따른 흐름특성과 보 상류에서 유사의 퇴적과정을 정량적으로 분석하고, 보 하류에서 세굴 및 지형변화 과정을 분석하였다. 보의 설치각도가 커질수록 보에 의항 굴절되는 유선의 각도가 증가하며, 하류에서 수충부가 형성되고 사수역의 크기가 증가한다. 즉, 보의 길이 대 수로 폭의 비로 정의되는 무차원 수로폭이 증가할수록 무차원 유효길이는 감소하였다. 보 상류에서는 보에 의하여 형성된 배수의 영향이 끝나는 지점에서 delta가 형성되며, 보 하류에서는 흐름이 집중되어 보 직하류 하상은 세굴되고 반대쪽에서는 이동성이 없는 교호사주가 형성되었다. 또한 충부에서는 깊게 세굴되었으며, 보의 설치 각도가 커질수록 수충부가 집중되면서 깊게 세굴되고, 세굴범위는 좁게 나타났다. 무차원 하상고가 증가할수록 유속과 delta의 이동속도의 비인 무차원 속도는 감소하며, 무차원 보의 길이가 증가함에 따라, 무차원 사주의 파장이 감소하였다. 무차원 보의 길이가 증가함에 따라 보에 의하여 굴절되는 흐름의 각이 크므로, 흐름이 집중되어 하상이 깊게 세굴되고 무차원 사주의 파고가 증가하였다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.6
• /
• pp.127-134
• /
• 2011

It has been reported that the length parameter of high strength bolts results in the variance in tensile loads. The required turn of nut for each length is specified in AISC RCSC specification. There is no specific regulation datum about the bolt length in the two national codes and specifications in Korea. Therefore this study focused on evaluating influence of the clamping torque subjected to length parameter of high strength bolts. Two types of high strength bolt specimens were manufactured and tested; High Strength Hexagon bolt specified in ASTM A490 and Torque Shear Bolt in KS B 2819. The length parameter ranged from 60mm(3d) to 140mm(7d). The torque, turn of nut, and the clamping force were analyzed to review whether length parameter affects on the required tensile strength. To evaluate the effects of the length parameter on the torque and turn of nut for the required strength and clamping force, statistical analysis was also carried out.

• Journal of Food Hygiene and Safety
• /
• v.16 no.1
• /
• pp.76-81
• /
• 2001

The germination test was used to detect biological changes in irradiated rice and glutenous rice at low doses. Grains were irradiated at below 0.5 kGy, husked and placed on distilled water moistend filter paper in a covered petri-dish. A germination test of 20 grains was carried out at room temperature for 5 days. The shoots and roots of non-irradiated rices grew well in comparison with those of irradiated rices above 0.3 kGy. The roots of rices were more sensitive to irradiation than the shoots, and the growth of roots was significantly decreased with the increasing doses. In glutinous rices, the growth of shoots and roots was retarded by irradiation at 0.2 kGy or more after 3rd days. We concluded that if the shoot or root length is 10 mm or longer within 5 day, the rices and glutinous rices are identified as non-irradiated.