• 한국항공우주학회지
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• 제40권12호
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• pp.1040-1047
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• 2012

본 논문에서는 소형 고정익기의 고장 발생시기와 부품 교체시기를 예측하여 유지보수 비용을 절감하고 정비 효율을 높이기 위하여 ANPSD와 PCA, 그리고 GC 방법을 이용하여 조종면의 고장에 대하여 이를 검출하고 위치와 정도를 분리하는 알고리즘을 제안하였다. 이때 ANPSD는 주파수 영역에서의 진동 분석을, PCA는 ANPSD의 중요 정보 추출을, GC는 고장 검출 및 분리 시의 오류 최소화를 위하여 사용되었다. 또한 모형 항공기에 가속도 센서를 부착하여 정상인 경우와 힌지 고장이 발생한 경우에 대하여 실제로 측정한 결과에 이와 같은 알고리즘을 적용한 결과 해당 알고리즘이 고장을 검출하고 분리하는 데에 적합함을 보였으며 제안된 알고리즘을 적용할 경우에 발생 가능한 문제들에 대하여 이를 완화할 수 있는 대응책을 함께 제시하였다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.179-179
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• 1998

We previously reported the hepato-protective effect of butanol soluble fraction of methanolic extract of Carthamus tinctorius L. Semen on carbon tetrachloride induced hepatotoxicity. In this study, the active component from the butanol soluble fraction was isolated by column chromatographic separation using Silica gel and Sephadex LH -20 and identified by spectroscopic methods such as Mass, $^1$H - NMR and $\^$13/C-NMR. The hepato-protective effect of the isolated active component on the CCl$_4$-induced liver damaged rats has been evaluated by performing blood chemical analysis and biotransformational enzyme analysis.

• Journal of the Korean Wood Science and Technology
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• 제32권1호
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• pp.9-16
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• 2004

본 연구는 폐지로부터 용액화물을 제조하고, 제조된 용액화물의 성분 분리 및 성상분석을 통해 용액화물의 효율적인 이용방안을 위한 기초자료 제공에 그 연구 목적이 있다. 폐지의 액화에 있어 건식해리된 폐지보다 습식해리된 폐지의 액화가 비교적 용이하였으며, 이러한 이유는 습식해리된 폐지의 약품 침투가 비교적 용이하기 때문으로 판단된다. 폐지의 최적 액화조건은 폐지 1 g에 대해 크레졸 2 ㎖, 물 4 ㎖, 인산 0.5 ㎖로 첨가하여 190℃에서 60분간 액화 시킨 조건이 가장 우수하였다. 폐지 액화물 중 리그닌은 용제인 크레졸 층으로, 탄수화물은 수층으로 용해되어 각각 분리되며, 두 성분의 분리·회수는 비교적 용이하였다. 액화 폐지 중의 리그닌은 80% 이상 회수되었고, 회수된 리그닌의 분자량은 1,000 정도의 저분자량을 나타냈었다.

• Structural Engineering and Mechanics
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• 제43권4호
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• pp.475-502
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• 2012

In this paper, the seismic analysis modeling technologies for sodium-cooled fast reactor (SFR) are presented with detailed descriptions for each structure, system and component (SSC) model. The complicated reactor system of pool type SFR, which is composed of the reactor vessel, internal structures, intermediate heat exchangers, primary pumps, core assemblies, and core support structures, is mathematically described with simple stick models which can represent fundamental frequencies of SSC. To do this, detailed finite element analyses were carried out to identify fundamental beam frequencies with consideration of fluid added mass effects caused by primary sodium coolant contained in the reactor vessel. The calculation of fluid added masses is performed by detailed finite element analyses using FAMD computer program and the results are discussed in terms of the ways to be considered in a seismic modeling. Based on the results of seismic time history analyses for both seismic isolation and non-isolation design, the functional requirements for relative deflections are discussed, and the design floor response spectra are proposed that can be used for subsystem seismic design.

• Structural Engineering and Mechanics
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• 제26권5호
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• pp.517-544
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• 2007

This study shows a fuzzy tuning scheme to fuzzy sliding mode controller (FSMC) for seismic isolation of earthquake-excited structures. The sliding surface can rotate in the phase plane in such a direction that the seismic isolation can be improved. Since ideal sliding mode control requires very fast switch on the input, which can not be provided by real actuators, some modifications to the conventional sliding-mode controller have been proposed based on fuzzy logic. A superior control performance has been obtained with FSMC to deal with problems of uncertainty, imprecision and time delay. Furthermore, using the fuzzy moving sliding surface, the excellent system response is obtained if comparing with the conventional sliding mode controller (SMC), as well as reducing chattering effect. For simulation validation of the proposed seismic response control, 16-floor tall building has been considered. Simulations for six different seismic events, Elcentro (1940), Hyogoken (1995), Northridge (1994), Takochi-oki (1968), the east-west acceleration component of D$\ddot{u}$zce and Bolu records of 1999 D$\ddot{u}$zce-Bolu earthquake in Turkey, have been performed for assessing the effectiveness of the proposed control approach. Then, the simulations have been presented with figures and tables. As a result, the performance of the proposed controller has been quite remarkable, compared with that of conventional SMC.

• 항공우주시스템공학회지
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• 제10권3호
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• pp.15-22
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• 2016

The on-board appendages of satellites with mechanical moving parts such as the fly-wheel, the control-moment gyro, the cryocooler, and the gimbal-type directional antenna can generate an undesirable micro-vibration disturbance, which is one of the main causes of the image-quality degradation that affects high-resolution observation satellites. Consequently, the isolation of the micro-vibration issue has always been considered as salient, and the micro-vibration is therefore the focus of this study wherein a complex system that can provide the dual functions of a guaranteed vibration-isolation performance and electrical energy harvesting is proposed. The vibration-isolation and energy-harvesting performances of the complex system are predicted through a numerical analysis based on the characteristics that are obtained from component-level tests. In addition, the effectiveness of the complex system that is proposed in this study is verified through an assembly-level functional-performance test.

• 환경영향평가
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• 제23권3호
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• pp.169-176
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• 2014

The purpose of this study is to estimate the vibration reduction effect of the borehole which is controlled the vibration propagation in the ground. For this study, we measured the vibration velocity before and after the borehole installation. The results are as follows: The peak particle velocity(PPV) and peak vector sum(PVS) was reduced by the borehole. And also, the deviation of vibration velocity before and after the borehole installation showed large values in longitudinal and vertical component depending on the receive distance, and increased depending on the size of vibration energy. Finally, the vibration isolation efficiency was 25~35 percentage at 1.5m receive distance, and was 4~14 percentage at 3.0m receive distance. It was found that the vibration isolation efficiency was good in small vibration energy, but was not good at long receive distance.

• Journal of Advanced Marine Engineering and Technology
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• 제31권8호
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• pp.970-974
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• 2007

A mixer is a key component in the wireless communication systems. In this paper, we design a mixer which is used in a frequency modulated continuous wave(FMCW) radar system. The frequency sweep range of the radar is from 10 GHz to 11 GHz. The transmitted and received signals of the FMCW radar are applied to LO and RF ports of the mixer, respectively, but the frequency difference between the two signals, which is called "a beat frequency" is under a few KHz and depending on the distance to target. Thus the isolation between the LO and RF ports is very important factor to design this mixer. In this paper we propose a single balanced resistive mixer using GaAs MESFET for this application. We first design a single-ended type resistive mixer using a simulation tool, then design a balanced type to increase the LO-to-RF isolation of the mixer. We fabricated the mixer on the substrate of dielectric constant 10 and thickness 0.635 mm. The measured results show that the isolation and conversion loss of the mixer over the frequency band is 20dB and 10.5dB, respectively. The LO input power for operating the proposed mixer is +3dBm, which is lower than a general conventional mixer's LO power. The 1 dB compression point is 6dBm.

• 한국추진공학회지
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• 제20권4호
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• pp.87-93
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• 2016

직접 연결식(DC) 고도모의 엔진시험 수행 시, 공기 흡입 덕트와 항공용 엔진 사이에 래버린스 씰이 설치된다. 래버린스 씰은 이 둘을 기계적으로 격리시킴으로써 주추력 및 측추력을 보다 정확하게 측정할 수 있도록 돕는다. 하지만 덕트 내부 공급공기에 높은 수직 온도구배가 발생할 경우, 래버린스 씰의 격리가 파괴되어버린다. 본 논문에서는 이러한 접촉 문제를 해결하기 위한 노력의 일환으로 래버린스 씰 온도 제어장치를 제작/설치하였다. 본 장치를 실제 항공용 엔진시험에 적용한 결과, 높은 수직 온도구배가 생성되어도 래버린스 씰의 격리가 잘 유지되는 것을 확인할 수 있었다.

• 한국식품영양학회지
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• 제24권1호
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• pp.94-100
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• 2011

This study identified the formula of the antioxidant substance separated from the ethyl acetate and the butanol extract and tested the antioxidant properties with the electron donating ability(EDA). Each phase with the fractionated methanol extract from mulberry leaf was screened in advance for the antioxidant substance with EDA. As the result, activity appeared in the ethyl acetate and butanol phase and the antioxidant component was separated. As the consequence, 2 components from the ethyl acetate phase and 1 from the butanol phase were separated, among which the structures of the components from ethyl acetate were determined by wogonin and linarin, whereas the structure of the component from the butanol phase was determined by pectolinarin. In the screening of antioxidant activity by the scavenging effect of the DPPH radical, the wogonin and linarin components from ethyl acetate phase showed more powerful antioxidant property than the component from butanol. The results from this study indicate that the chemical compound separated from the ethyl acetate extract has more powerful antioxidant property than the one separated from the butanol extract. The components separated from the ethyl acetate extract were wogonin and linarin, which are flavonoids, whereas the component from butanol was pectolinarin. Therefore, this study suggested that the feasibility of mulberry leaf as a functional food additive and its value as a natural antioxidant is very high.