• 대한음성학회:학술대회논문집
• /
• 대한음성학회 2007년도 한국음성과학회 공동학술대회 발표논문집
• /
• pp.127-130
• /
• 2007

The conventional feature recombination technique is very effective in the band-limited noise condition, but in broad-band noise condition, the conventional feature recombination technique does not produce notable performance improvement compared with the full-band system. To cope with this drawback, we introduce a new technique of sub-band likelihood computation in the feature recombination, and propose a new feature recombination method by using this sub-band likelihood computation. Furthermore, the reliable sub-band selection based on the signal-to-noise ratio is used to improve the performance of this proposed feature recombination. Experimental results shows that the average error reduction rate in various noise condition is more than 27% compared with the conventional full-band speaker identification system.

• 전자공학회논문지A
• /
• 제33A권4호
• /
• pp.98-105
• /
• 1996

The design method of 85 GHz-115 GHz band single side-band filter using the principle of martin-puplett inteferometer is described. It has been designed by this method and also manufactured and tested. From the test results, not only the ratio of image singal rejection of 19 dB is obtained, but also the theoretical and experimental results of center frequency of pass-band and rejection-band show the validity of the theory. This manufactured filter was installed on 100GHz band SiS (superconductor insulator superconductor ) receiver for observing cosmic radio waves and tested. We found that this filter can be used a single side-band as well as double side-band mode. The design method which is presented in this paper can be used a single side-band filter for a heterodyne type sub-milimeter wave receiver.

• 대한원격탐사학회지
• /
• 제27권5호
• /
• pp.613-623
• /
• 2011

본 연구에서는 Moderate Imaging Spectroradiometer(MODIS), Sea-viewing Wide Field-fo-view Sensor(SeaWiFS), Medium Resolution Imaging Spectrometer(MERIS) 등의 광역관측 위성영상을 이용한 해수나 연안수의 클로로필 농도 분석을 통해 가능성이 확인되었던 밴드 비를 이용한 비교적 간단한 추정 모델을 수체의 크기와 폭이 현저히 작고 탁도가 있는 하천에 대해 클로로필-a 농도값을 추정하고자 고해상도 위성영상에 Two-band 및 Three-band reflectance 모델을 적용하여 가능성을 파악하였다. 특히 RapidEye 영상을 이용하여 일반적으로 탁도가 있는 수체에 대해 Red와 NIR 영역을 활용하는 이들 모델에 Red-edge(RE) 밴드를 적용하였다. Red와 NIR을 이용한 Two-band Reflectance 모델은 계산식의 결정계수 $R^2$ 값이 0.38로 유의성 없는 결과를 나타내었다. 그러나 RapidEye의 Red-edge (RE) 파장 대를 이용한 Red-RE Two-band 모델과 Red-RE-NIR Three-band 모델을 이용한 계산식에 대해서는, 2차함수에 의한 Three-band 모델의 결과는 Red-RE Two-band 모델의 결과와 통계적인 값이 거의 유사하였고 Two-band와 3차함수에 의한 Three-band 모델 추정식은 각각 0.66, 0.73 의 $R^2$값을 나타내어 Red-edge 밴드의 적용 가능성을 보였고, 실측치와의 Root Mean Square Error (RMSE)는 24.8, 22.4 mg $m^{-3}$, Relative Percent Difference(RPD)는 각각 1.30, 1.29로 1.5 이하의 대략적인 추정(Approximate Prediction) 수준을 나타내었다. 고해상도 위성영상에 Red-RE-NIR Three-band 모델을 적용한 계산식을 이용해 대략적인 추정이지만 가장 유의한 수준의 클로로필-a 농도를 추정할 수 있었다. 영상에서 추정된 클로로필-a 분포를 비교하였을 때 3차함수에 의한 Three-band 모델 추정식이 Two-band 모델에 비해 낮은 값의 분포를 보였다. 향후 하천의 스펙트럼을 실측하여 파장별 부유물질, 유기물과의 상관성 및 클로로필 농도와의 간섭 정도를 시뮬레이션하여 보정식을 산출 적용한다면 탁도가 다소 높은 하천에서의 클로로필-a 농도 계산식의 정확도를 더욱 높일 수 있을 것으로 기대된다.

• 한국통신학회논문지
• /
• 제21권11호
• /
• pp.2932-2941
• /
• 1996

Conventional non-regenerative satellite repeaters do not provide anti-jamming capability enough to provide communications between small terminals in jamming environment. In this paper, we analyze the budget and system requirements for Ka-band satellite communication. For the analysis, we modeled and simulated the Ka-band satellite system based on downlink power limited repeater. Assuming that a spread spectrum is applied for anti-jamming purpose, we also analyzed a tolerable jammer-to-signal power ratio under strong up-link jamming in the bit rates of 2.4Kbps and 19.6Kbps.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
• /
• pp.443-446
• /
• 2002

In this paper, we present a new design method for a square iris polarizer to be used in dual-band (Ka-band; 20.8 ~21.2 ㎓, 30.6~31 ㎓) antenna feeds. Principles of operation of a square iris polarizer, its design concepts and methods are proposed. Based on proposed methods, a Ka- band polarizer with -35 dB return loss and 0.3 dB axial ratio is designed using the commercial software HFSS.

• 한국해양공학회지
• /
• 제4권2호
• /
• pp.100-111
• /
• 1990

In this paper, fatigue tests were carried out at stress test levels of 461 MPa, 441 MPa, and 431 MPa by using smooth specimen of$2_{1/4}$ Cr-1 Mo steel with the stress ratio(R) of 0.05. The initiation, growth and coalescense process of the major cracks and sub-cracks among the fatigue cracks on the smooth specimen are investigated and measured under each stress level at a constant cycle ratio by the replica technique with optical microscope. Some of the important results are as follows: In spite of the difference of stress levels, the major crack data gather into a small band in the curve of surface crack length and crack depth against cycle ratio N/Nf. The sub-crack data, however, deviate from the band of the major crack. The growth rates, da/dN, of major and sub-crack plotted against the stress intensity factor range, ${\Delta}K$, have the tendency to be compressed on a relatively small band. But it is more effective to predict fatigue life through major cracks. The propagation behavior of surface microcracks on the smooth specimens coincides with that of the specimen having an artificial small surface defect or through crack.

• Journal of Yeungnam Medical Science
• /
• 제3권1호
• /
• pp.41-48
• /
• 1986

사람의 적혈구막으로부터 Band 3를 분리정제하고 이를 liposome 내로 도입시켜 그 결과를 관찰하였다. 적혈구를 약알칼리 저장액으로 용혈시켜 막을 분리한 후, 저이온강도 용액으로 처리하여 Band 4를 추출하였다. Triton X-100 추출액에 p-chloromercuribenzoate를 가하고 sucrose density gradient ultracentrifugation후 fractionation하여 Band 3를 정제하였다. phosphatidyl L-serine과 cholesterol을 1 : 1 molar ratio로 섞고 진공회전 증발기를 사용하여 chloroform을 제거한 후 Triton X-100을 제거한 Band 3용액을 가하고 sonication함으로 liposome(reverse-phase evaporation vesicle)을 만들면서 Band 3를 도입 시켰다 Band 3의 분리정제 및 liposome에 도입되었음은 sodium dodecyl sulfate-polyacrylamide gel 전기영 동 후 coomassie brilliant blue 염색으로 확인할 수 있었다.

• 한국군사과학기술학회지
• /
• 제21권1호
• /
• pp.115-123
• /
• 2018

In this paper, we consider the applicability of time-hopping(TH) systems for anti-jamming(AJ) communication. We first briefly summarize fundamentals of TH systems and several common jamming scenarios that have been considered in the literature. We then analyze the AJ performance of TH systems under those common jamming environments. From our simulation results, we reveal that among narrow band, partial band, broadband, and sweep jamming, partial band and sweep jamming are the best ones from jammer perspective. For the partial band jamming case, we show that the most effective bandwidth ratio and location are 50 % and 2.5-3.5 Ghz, respectively. For the sweep jamming case, we illustrate that the AJ performance of the TH system is enhanced when the sweep duration approaches to the bit duration. In addition, we pointed out that the most efficient jamming bandwidth ratio is 1/2. Finally, our results show that the TH-BPSK system greatly outperforms the TH-PPM counterpart.

• Journal of Communications and Networks
• /
• 제10권1호
• /
• pp.71-78
• /
• 2008

We propose a sub-band spreading technique for adaptive modulation (AM) in orthogonal frequency division multiplexing (OFDM) systems in order to reduce signaling overheads and to average frequency selective fading channels causing different signal-to-noise ratio (SNR) values for subcarriers in each subband. The conventional sub-band based AM schemes can also reduce signaling overheads and complexity for allocating a resource per sub-band at a time. However, they may suffer from the channel variation in a sub-band when the sub-band size is larger than the channel coherence bandwidth (BW). The sub-band spreading at the transmitter enables the received symbols in each sub-band to have an identical reliability even in a frequency selective fading channel. We rigorously analyze the averaged SNR value at the receiver of the sub-band spreading system and the analyzed average SNR in a sub-band is used for an adaptation criterion. The proposed AM scheme outperforms the conventional sub-band based OFDM scheme without spreading, and it can yield better throughput performance than the conventional subcarrier based AM schemes when we consider the signaling overheads.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 C
• /
• pp.1860-1862
• /
• 2004

It is widely known that the ultra high frequency (UHF) method that detects the electromagnetic wave of the PD pulses in the gas insulated space is one of the most competitive methods for its high sensitivity. From the above point of view, this paper describes the characteristics of GIS PD signals measured with ultra wide band (UWB) GIS PD detecting system in which PD signals are detected into the dual UHF band. The UWB PD detection system consists of the UWB UHF coupler, the UWB low noise amplifier (LNA) and the oscilloscope. The dual bands for PD signals are 0.5-2GHz(full band) and 1-2GHz(high band). As results, it was found that the partial discharges of each defect have their own characteristic pattern and the ratio of High band to Full band increases with gas pressure.