• Journal of Communications and Networks
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• 제11권1호
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• pp.26-35
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• 2009

In this paper, we investigate how to do resource allocation to guarantee a minimum user data rate at low signaling overhead in multi-cell orthogonal frequency division multiple access (OFDMA) wireless systems. We devise dynamic resource allocation (DRA) algorithms that can minimize the QoS violation ratio (i.e., the ratio of the number of users who fail to get the requested data rate to the total number of users in the overall network). We assume an OFDMA system that allows dynamic control of frequency reuse factor (FRF) of each sub-carrier. The proposed DRA algorithms determine the FRFs of the sub-carriers and allocate them to the users adaptively based on inter-cell interference and load distribution. In order to reduce the signaling overhead, we adopt a hierarchical resource allocation architecture which divides the resource allocation decision into the inter-cell coordinator (ICC) and the base station (BS) levels. We limit the information available at the ICC only to the load of each cell, that is, the total number of sub-carriers required for supporting the data rate requirement of all the users. We then present the DRA with limited coordination (DRA-LC) algorithm where the ICC performs load-adaptive inter-cell resource allocation with the limited information while the BS performs intra-cell resource allocation with full information about its own cell. For performance comparison, we design a centralized algorithm called DRA with full coordination (DRA-FC). Simulation results reveal that the DRA-LC algorithm can perform close to the DRA-FC algorithm at very low signaling overhead. In addition, it turns out to improve the QoS performance of the cell-boundary users, and achieve a better fairness among neighboring cells under non-uniform load distribution.

• 한국균학회지
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• 제33권2호
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• pp.81-85
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• 2005

1997년부터 2003년에 걸쳐 우리나라에서 수확된 보리, 율무, 옥수수, 수수, 벼에서 총 81개의 Penicillium 속균을 분리하였다. 분리된 Penicillium 속균의 배양적 형태적 특징을 이용하여 종을 동정한 결과 P. citrinum, P. chrysogenum, P cyclopium, P. oxalicum, P. polonicum, P. purpurogenum 그리고 P. viridicatum으로 동정되었다. 이 중에서 P. cyclopium, P. polonicum, P. purpurogenum은 국내에서 처음 보고되는 미기록종들이다.

• 한국수자원학회논문집
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• 제47권8호
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• pp.693-701
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• 2014

본 연구에서는 강우의 변동특성 분석에 있어 기존의 접근법인 지속기간별 강우량의 변화 분석을 통하여 얻는 데 한계가 있는 강우의 구조적 변동특성을 분석하기 위하여 추계학적 강우모형을 이용하였다. Neyman-Scott 구형펄스 모형(Neyman-Scott Rectangular Pulse Model, NSRPM)은 점 과정을 이용한 추계학적 강우생성 모형으로 시간단위 강우를 생성함으로써 수문학 분야에서 널리 쓰이고 있으며 강우특성과 관련한 5개의 매개변수로 구성되어있다. 각 매개변수는 물리적인 의미를 가지고 있으므로 서울지점의 1973~2011년 여름철 시강우자료를 이용하여 NSRPM의 매개변수를 추정하고 추정된 매개변수의 변화를 분석하여 강우의 구조적인 변화를 분석하고 기존연구와 비교 분석하였다.

• 한국ITS학회 논문지
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• 제18권6호
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• pp.137-154
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• 2019

본 연구에서는 중앙제어방식 긴급자동차 우선신호를 강북소방서 주변 1.782km 구간에 시험하고 그 효과를 분석하였다. 기존 연구를 검토하여 중앙제어방식과 현장제어방식에 대한 장단점을 비교하였고, 소방서 주변 도로 중 평균 통행속도가 높은 상위 지역 중 왕복 4차로에서 6차로에 해당되는 지역을 시험 대상 지역으로 선정하였다. 우선신호는 긴급자동차 속도로 교차로 도착 예정 시각을 산정, 녹색 신호를 연장하는 방식을 적용하였다. 우선신호 적용 효과는 긴급 자동차 GPS 궤적을 분석하여 속도와 이동시간으로 분석하였고, 주변 교통흐름에 미치는 영향은 긴급자동차 주행방향과 다른 방향의 대기행렬 길이조사를 통해 분석하였다. 시범사업 결과 긴급차량의 평균 통행시간이 41.81% 감소하였고 혼잡한 몇 개의 교차로를 제외한 대부분의 교차로에서의 지체 증가는 매우 적었다. 향후 Early Green과 전이과정에서 우선신호에 대한 보상방법에 대한 연구를 한다면 긴급자동차 우선신호 적용지역을 확대할 수 있을 것으로 기대된다.

• The Plant Pathology Journal
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• 제24권1호
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• pp.46-51
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• 2008

With the goal of achieving better integrated pest management for hot pepper, a disease-forecasting system was compared to a conventional disease-control method. Experimental field plots were established at Asan, Chungnam, in 2005 to 2006, and hourly temperature and leaf wetness were measured and used as model inputs. One treatment group received applications of a protective fungicide, dithianon, every 7 days, whereas another received a curative fungicide, dimethomorph, when the model-determined infection risk (IR) exceeded a value of 3. In the unsprayed plot, fruits showed 18.9% (2005) and 14.0% (2006) anthracnose infection. Fruits sprayed with dithianon at 7-day intervals had 4.7% (2005) and 15.4% (2006) infection. The receiving model-advised sprays of dimethomorph had 9.4% (2005) and 10.9% (2006) anthracnose infection. Differences in the anthracnose levels between the conventional and model-advised treatments were not statistically significant. The efficacy of 10 (2005) and 8 (2006) applications of calendar-based sprays was same as that of three (2005 and 2006) sprays based on the disease-forecast system. In addition, we found much higher the IRs with the leaf wetness sensor from the field plots comparing without leaf wetness sensor from the weather station at Asan within 10km away. Since the wetness-periods were critical to forecast anthracnose in the model, the measurement of wetness-period in commercial fields must be refined to improve the anthracnose-forecast model.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2011년도 제43차 동계학술발표논문집 19권1호
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• pp.109-110
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• 2011

현대의 도시철도차량 시스템은 복잡하고 첨단화 되어 있으며, 상호 인터페이스 체계를 구축하고 있는 차량 유지보수시스템의 체계적인 종합관리가 필요하다. 본 연구는 무선 전송 장치를 이용하여 전동차 정보 자동 수집 장치를 도입 적용한 사례에 대한 분석 결과이다. 무선 전송 장치는 차량기지로 입고한 전동차 열차종합제어장치에 수집된 각종 정보를 무선 통신으로 데이터를 전송함으로써 유지보수 비용절감과 데이터 전송의 신뢰성 향상 효과가 있으며 이러한 무선 전송 장치를 도입 적용하여 기존의 열차정보수집 방법을 개선한 운용 사례를 제시한다.

• The Plant Pathology Journal
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• 제19권3호
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• pp.171-176
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• 2003

The complete nucleotide sequences of the genomic RNAs of Soybean mosaic virus strains GS (SMV-G5) and G7H (SMV-G7H) were determined and compared with sequences of other SMV strains. Each viral RNA was determined to be 9588 nucleotides in length excluding the poly (A) tail and contained an open reading frame to encode a polyprotein subsequently processed into up to ten proteins by proteolytic cleavage. Com-parison of the amino acid sequences with those of other SMV strains showed high percentage of amino acid sequence homology with the same genome organization. The nucleotide and the deduced amino acid sequences between SMV-G5 and SMV-G7H were greater than 99% identity. When compared with those of other SMV strains in a phylogenetic analysis of the nucleotide and deduced amino acid sequences, they formed a distinct virus clade showing over 97％ amino acid identity, but were more distantly related to the other potyvirus (44.1-69.6% identity). Interestingly, SMV G7H strain caused a severe mosaic or necrosis symptom in soybean cultivars including Jinpum-1, Jinpum-2, and Sodam, whereas, no symptom was observed in SMV-G5 inoculation. Complete nucleotide sequences of these strains will give clues for determining symptom determinant(s) in future research.

• Asian-Australasian Journal of Animal Sciences
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• 제18권5호
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• pp.643-648
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• 2005

Near infrared reflectance spectroscopy (NIRS) has become increasingly used as a rapid, accurate method of evaluating some chemical constituents in cereal grains and forages. If samples could be analyzed without drying and grinding, then sample preparation time and costs may be reduced. This study was conducted to develop robust NIRS equations to predict fermentation quality of corn (Zea mays) silage and to select acceptable sample preparation methods for prediction of fermentation products in corn silage by NIRS. Prior to analysis, samples (n = 112) were either oven-dried and ground (OD), frozen in liquid nitrogen and ground (LN) and intact fresh (IF). Samples were scanned from 400 to 2,500 nm with an NIRS 6,500 monochromator. The samples were divided into calibration and validation sets. The spectral data were regressed on a range of dry matter (DM), pH and short chain organic acids using modified multivariate partial least squares (MPLS) analysis that used first and second order derivatives. All chemical analyses were conducted with fresh samples. From these treatments, calibration equations were developed successfully for concentrations of all constituents except butyric acid. Prediction accuracy, represented by standard error of prediction (SEP) and $R^2_{v}$ (variance accounted for in validation set), was slightly better with the LN treatment ($R^2$ 0.75-0.90) than for OD ($R^2$ 0.43-0.81) or IF ($R^2$ 0.62-0.79) treatments. Fermentation characteristics could be successfully predicted by NIRS analysis either with dry or fresh silage. Although statistical results for the OD and IF treatments were the lower than those of LN treatment, intact fresh (IF) treatment may be acceptable when processing is costly or when possible component alterations are expected.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.2985-2991
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• 2013

경부고속철도 2단계 구간에 도입된 열차무선시스템은 TETRA 기반으로 851MHz 대의 주파수를 사용하고 있다. 이와 같은 열차무선시스템에서 운행중인 차량과 지상과의 끊임없는 정보송수신을 위하여 전파 경로손실을 감안한 기지국 설계가 필수적이다. 본논문에서는 고속철도 선로에서의 측정데이터를 토대로, 열차무선의 전파 경로손실을 정량적으로 분석하였다. 열차무선 기지국 설계에서는 자유공간 전파 경로손실모델 및 Okumura-Hata모델이 사용되고 있는데, 이 모델들에 의한 예측치는 현장측정치보다 10dB 이상 작거나 20dB 이상 크게 나타남에 따라 고속철도 열차무선의 경로손실 예측에는 적합하지 않은 것으로 나타났다. 측정결과를 log-distance 경로손실모델에 적용하여 회귀분석을 수행한 결과 경로손실지수는 2.8~3.2의 범위로 나타났으며, 이 결과는 향후 고속철도 열차무선에서의 전파경로손실 예측에 적용할 수 있다.

• 대기
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• 제20권3호
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• pp.343-353
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• 2010

A regional wind network with complex surface conditions must be designed with sufficient space and time resolution to resolve the local circulations. In this study, the spatial variations of the wind field observed in the Seoul and Jeju regional networks were evaluated in terms of annual, seasons, and months to assess the spatial homogeneity of wind fields within the regional networks. The coherency of the wind field as a function of separation distance between stations indicated that significant coherency was sometimes not captured by the network, as inferred by low correlations between adjacent stations. A meso-velocity scale was defined in terms of the spatial variability of the wind within the network. This problem is predictably most significant with weak winds, dull prevailing wind, clear skies and significant topography. The relatively small correlations between stations imply that the wind at a given point cannot be estimated by interpolating winds from the nearest stations. For the Seoul and Jeju regional network, the meso-velocity scale has typically a same order of magnitude as the speed of the network averaged wind, revealing the large spatial variability of the Jeju network station imply topography and weather. Significant scatter in the relationship between spatial variability of the wind field and the wind speed is thought to be related to thermally-generated flows. The magnitude of the mesovelocity scale was significantly different along separation distance between stations, wind speed, intensity of prevailing wind, clear and cloudy conditions, topography. Resultant wind vectors indicate much different flow patterns along condition of contributing factors. As a result, the careful considerations on contributing factors such as prevailing wind in season, weather, and complex surface conditions with topography and land/sea contrast are required to assess the spatial variations of wind field on a regional network. The results in the spatial variation from the mesovelocity scale are useful to represent the characteristics of regional wind speed including lower surface conditions over the grid scale of large scale atmospheric model.