• 제어로봇시스템학회논문지
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• 제14권2호
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• pp.133-140
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• 2008

In this paper, a small and effective attitude estimation system for a humanoid robot was developed. Four small inertial sensors were packed and used for inertial measurements(3D accelerometer and three 1D gyroscopes.) An effective 3D pose estimation algorithm for low cost DSP using an extended Kalman filter was developed and evaluated. The 3D pose estimation algorithm has a very simple structure composed by 3 modules of a linear acceleration estimator, an external acceleration detector and an pseudo-accelerometer output estimator. The algorithm also has an effective switching structure based on probability and simple feedback loop for the extended Kalman filter. A special test equipment using linear motor for the testing of the 3D pose sensor was developed and the experimental results showed its very fast convergence to real values and effective responses. Popular DSP of TMS320F2812 was used to calculate robot's 3D attitude and translated acceleration, and the whole system were packed in a small size for humanoids robots. The output of the 3D sensors(pitch, roll, 3D linear acceleration, and 3D angular rate) can be transmitted to a humanoid robot at 200Hz frequency.

• 한국전자파학회논문지
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• 제9권3호
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• pp.386-398
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• 1998

본 논문에서는 군사용 레이다 장비에서 필수적인 연속검파 형태의 대수증폭기를 높은 다이나믹 레인지 및 낮은 대수 오차를 얻을 수 있도록 설계 제작하였다. 제작된 대수 증폭기는 하이브리드 형태로 구현되였으며,0.5l 1.5 GHz에서 dynamic range는 80 dB 이상, 대수오차는 $\pm$1.4 dB 이하, 잡음지수 5.5 dB 이하, 감도는 -76 d dBm, VSWR 2.0:1 이하의 특성을 나타내었다. 제작된 대수 증폭기는 기존의 MAlCOM사에서 제작된 대수 증폭기에 비해 다이나믹 레인지가 훨씬 높고 다른 특성면에서는 큰 차이가 없으므로, 크기 및 전력소모를 줄여서 레이다 시스템에 응용할 수 있을 것이다.

• 한국항행학회논문지
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• 제4권2호
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• pp.182-190
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• 2000

본 논문은 HAPS와 이동위성 시스템과의 간섭영향 분석으로서, HAPS 고도가 20km와 50km일 때의 C/I 값을 구해 간섭 보호비를 초과하는 시간율 및 초과지속시간에 대한 평가를 행하였다. 그 결과 HAPS가 Iridium 시스템에 미치는 간섭의 경우 최저 C/I 값은 HAPS 고도가 50km일 때 20.42dB, 20km일 때는 12.73dB로 낮아지고, 이와 반대인 Iridium 시스템이 HAPS에 미치는 간섭의 경우도 각각 13.94dB에서 10.42dB로 낮아짐을 알 수 있었다. HAPS 고도에 따른 간섭영향을 보면, 고도가 낮아질수록 강한 간섭을 주거나 받게 되며, C/I 최저값 또한 HAPS 고도에 따라 다른 시점에서 나타난다.

• Archives of Pharmacal Research
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• 제26권4호
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• pp.279-285
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• 2003

In our ongoing study to identity antioxidants from natural sources, the antioxidant activity of Nelumbo nucifera stamens was evaluated for their potential to scavenge stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, inhibit total reactive oxygen species (ROS) generation, in kidney homogenates using 2 ,7 -dichlorodihydrofluorescein diacetate (DCHF-DA), and scavenge authentic peroxynitrites ($ONOO^-$). A methanol (MeOH) extract of the stamens of N. nucifera showed strong antioxidant activity in the $ONOO^-$system, and marginal activity in the DPPH and total ROS systems, so were therefore fractionated with several organic solvents, such as dichloromethane ($CH_2 Cl_2$), ethyl acetate (EtOAc) and n-butanol (n-BuOH). The EtOAc soluble fraction, which exhibited strong antioxidant activity in all the model systems tested, was further purified by repeated silica gel and Sephadex LH-20 column chromatographies. Seven known flavonoids [kaempferol (1), kaempferol 3-Ο-$\beta$-D-glucuronopyranosyl methylester (2), kaempferol 3-Ο-$\beta$-D-glucopyranoside (3), kaempferol 3-Ο-$\beta$-D-galactopyranoside (4), myricetin 3 ,5 -dimethylether 3-Ο-$\beta$-D-glucopyranoside (5), kaempferol 3-Ο-$\alpha$-L-rhamnopyranosyl-(1$\rightarrow$6)-$\beta$-D-glucopyranoside (6) and kaempferol 3-Ο-$\beta$-D-glucuronopyranoside (7)], along with $\beta$-sitosterol glucopyranoside (8), were isolated. Compound 1 possessed good activities in all the model systems tested. Compounds 2 and 7 showed scavenging activities in the DPPH and $ONOO^-$ tests, while compounds 3 and 4 were only active in the $ONOO^-$ test. Conversely, compound 8 showed no activities in any of the model systems tested.

• 한국정보통신학회논문지
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• 제21권6호
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• pp.1100-1105
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• 2017

본 논문에서는 셀룰러 통신과 D2D (device-to-device)통신이 같은 주파수를 통해 이루어지는 이기종 네트워크(heterogenous network)에서 셀룰러 망의 보안통신을 돕기 위한 D2D 통신 디바이스의 전력제어 기법을 제안하고 성능을 살펴본다. 기존의 보안통신이 고려되지 않은 이기종 네트워크에서는 D2D통신 신호가 간섭으로 작용하여 셀룰러 통신 성능에 악영향을 미쳤으나 도청자를 고려한 보안통신에서는 D2D통신 신호가 도청자의 신호수신을 방해하여 보안 전송률 성능 향상에 도움이 될 수 있다. 본 연구에서는 셀룰러 망의 보안통신 요구치를 만족시키며 D2D 통신 전송률을 극대화 시킬 수 있는 새로운 전력제어 기법을 제안하고 최적화 문제를 통해 최적 송신 전력의 closed-form 표현을 도출하였다. 또한 시뮬레이션을 통해 제안기법의 성능 특성을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권12호
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• pp.4946-4960
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• 2020

In a device-to-device (D2D) underlaid cellular network, there exist two types of co-channel interference. One type is inter-layer interference caused by spectrum reuse between D2D transmitters and cellular users (CUEs). Another type is intra-layer interference caused by spectrum sharing among D2D pairs. To mitigate the inter-layer interference, we first derive the interference limited area (ILA) to protect the coverage probability of cellular users by modeling D2D users' location as a Poisson point process, where a D2D transmitter is allowed to reuse the spectrum of the CUE only if the D2D transmitter is outside the ILA of the CUE. To coordinate the intra-layer interference, the spectrum sharing criterion of D2D pairs is derived based on the (signal-to-interference ratio) SIR requirement of D2D communication. Based on this criterion, D2D pairs are allowed to share the spectrum when one D2D pair is far from another sufficiently. Furthermore, to maximize the energy efficiency of the system, a resource allocation scheme is proposed according to weighted graph coloring theory and the proposed ILA restriction. Simulation results show that our proposed scheme provides significant performance gains over the conventional scheme and the random allocation scheme.

• 한국산업정보학회논문지
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• 제1권1호
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• pp.119-233
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• 1996

본 논문에서는 게이트의 길이가 0.25$\mu\textrm{m}$dlsGaAs HEMT(High Electron Mobility Transistor)를 이용하여 11.7GHz-12.2GHz 대역 위성통신용 수신기를 설계하였다. 설계된 수신기의 전체이득은 38dB 이상, 잡음지수 1.8dB 이하, 입출력단의 반사손실은 -10dB 이하를 보였다. 수신기는 저잡음증폭기(LNA), 중간주파수증폭기(IFA) , 믹서(Mixer), 국부발진기(LO) 로 구성되어 있으며 LO 주파수와 IF 주파수는 각각 10.75GHz 와 0.95GHz-1.45GHz이고 칩의 크기는 1.7mm $\times$2.5mm이다.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 1996년도 추계 학술 발표회 발표논문집
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• pp.184-195
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• 1996

본 논문에서는 게이트의 길이가 0.25um인 GaAs HEMT를 이용하여 11.7GHz -12.2GHz 대역 위성통신용 수신기를 설계하였다. 설계된 수신기의 전체이득은 38dB 이상, 잡음지수 1.8dB 이하, 입출력단의 반사손실은 -10dB 이하를 보였다. 수신기는 저잡음증폭기(LNA), 중간주파수증폭기(IFA) , 믹서, 국부발진기(LO) 로 구성되어 있으며 LO 주파수와 IF 주파수는 각각 10.75GHz 와 0.95GHz-1.45GHz이고 칩의 크기는 1.7mm $\times$2.5mm이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.376-381
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• 1992

This paper presents an expert system for the segmentation of a 2.5-D image. The results of two segmentation approaches, edge-based and region-based, are combined to produce a consistent and reliable segmentation. Rich information embedded in the 2.5-D image is utilized to obtain a view independent surface patch description of the image, which can facilitate object recognition considerably.

• Journal of Positioning, Navigation, and Timing
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• 제4권3호
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• pp.115-122
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• 2015

Global Positioning System (GPS) is used in various fields such as communications systems, transportation systems, e-commerce, power plant systems, and up to various military weapons systems recently. However, GPS receiver is vulnerable to jamming signals as the GPS signals come from the satellites located at approximately 20,000 km above the earth. For this reason, various anti-jamming techniques have been developed for military application systems especially and it is also required for commercial application systems nowadays. In this paper, we proposed a dual-channel Global Navigation Satellite System (GNSS) RF ASIC for digital pre-correlation anti-jam technique. It not only covers all GNSS frequency bands, but is integrated low-gain/attenuation mode in low-noise amplifier (LNA) without influencing in/out matching and 14-bit analogdigital converter (ADC) to have a high dynamic range. With the aid of digital processing, jamming to signal ratio is improved to 77 dB from 42 dB with proposed receiver. RF ASIC for anti-jam is fabricated on a 0.18-μm complementary metal-oxide semiconductor (CMOS) technology and consumes 1.16 W with 2.1 V (low-dropout; LDO) power supply. And the performance is evaluated by a kind of test hardware using the designed RF ASIC.