• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1217-1233
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• 2018

Following a surge of interest in multi-unit risk in the last few years, many recent studies have suggested methods for multi-unit probabilistic safety assessment (MUPSA) and addressed several related aspects. Most of the existing studies though focused on two-unit nuclear power plant (NPP) sites or used rather simplified probabilistic safety assessment (PSA) models to demonstrate the proposed approaches. When considering an NPP site with three or more units, some approaches are inapplicable or yield very conservative results. Since the number of such sites is increasing, there is a strong need to develop and validate practical approaches to the related MUPSA. This article provides several detailed approaches that are applicable to multi-unit Level 1 PSA for sites with up to six or more reactor units. To validate the approaches, a multi-unit Level 1 PSA model is developed and the site core damage frequency is estimated for each of four representative multi-unit initiators, as well as for the case of a simultaneous occurrence of independent single-unit initiators in multiple units. For this purpose, an NPP site with six identical OPR-1000 units is considered, with full-scale Level 1 PSA models for a specific OPR-1000 plant used as the base single-unit models.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권1호
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• pp.112-117
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• 2016

This paper presents a half-rate current-integrating DFE receiver with sub-unit interval (sub-UI) inter-symbol interference (ISI) cancellation. By having a single additional DFE tap in each data path, the proposed DFE receiver can minimize BER degradation due to input pattern dependency and feedback tap latency problems in conventional current-integrating DFE receivers. The proposed DFE receiver was designed and fabricated in a 45 nm CMOS process, whose measurement results indicated that the BER bathtub width is increased from 0.235 UI to 0.315 UI (34% improvement) at $10^{-12}$ BER level.

• 경제분석
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• 제27권3호
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• pp.61-96
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• 2021

본 연구는 지역소득의 불균형 요인을 분석하기 위해 지역의 단위소득당 소비지출에 의한 소득유발효과와 지역 간 단위소득에 의한 소득상호의존도를 측정하였는데, 이를 위해 16개 광역자치단체의 지역별 임금소득 및 소비 구조가 반영된 2005년과 2015년 지역산업 연관표를 이용하였다. 분석 결과를 정리하면 다음과 같다. 먼저, 지역별 단위소득당 소비지출에 의한 소득유발효과가 전반적으로 낮아졌는데 자기지역보다 타지역의 소득유발효과 하락이 주요인이었다. 다음으로 각 지역의 단위소득 발생에 의한 지역소득의 상호의존도도 대부분 지역에서 낮아졌는데, 이 역시 타지역으로의 소득전이 하락이 주요인이었다. 한편, 한국 경제에서 차지하는 비중이 큰 서울과 경기는 단위소득당 소비지출에 의한 소득유발효과가 타지역보다 낮지만 자기지역은 물론 타지역의 소비에 의해 발생한 소득유발효과를 가장 많이 차지하고 타지역으로부터의 소득전이를 가장 많이 흡수하였다. 이는 소비구조에서 서비스가 차지하는 비중이 높고 경기는 물론 특히 서울의 산업구조 서비스화 진전과 임금소득 비중이 높은 데 주로 기인하였다. 이러한 결과를 소득의 상호의존도 측면에서 보면 서울과 경기는 타지역의 소득에 의존하는 정도가 높은 것을 의미한다고 할 수 있다. 특히 경기는 고기술 제조업 제품의 해외수출을 주도하는 지역이라 대외 요인도 소득유발에 기여하지만, 서울의 경우 서비스를 기반으로 국내 상호연관구조를 이용한 소득흡수가 높다는 측면에서 본다면 국내 타지역의 경제 상황에 민감한 소득 창출 구조를 갖고 있다는 점을 지적할 수 있을 것이다. 지역 간 소득유발효과와 소득전이가 전반적으로 하락하고 서울과 경기로의 집중이 지속되고 있는 가운데 지역불균형을 구조적 측면에서 완화하기 위해서는 지역의 산업정책은 서울이나 경기의 구조를 벤치마킹하는 것보다는 각 지역 특화산업의 비교우위를 강화하여 지역 간 상호연계성 제고가 필요하다고 하겠다.

• Journal of Biosystems Engineering
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• 제33권5호
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• pp.362-369
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• 2008

There is developing interest in precision agriculture in Korea, despite the fact that typical Korean fields are less than 1 ha in size. Describing within-field variability in typical Korean production settings is a fundamental first step toward determining the size of management zones and the inter-relationships between limiting factors, for establishment of site-specific management strategies. Measurements of rice (Oriza Sativa L) yield, chlorophyll content, and soil properties were obtained in a small (100-m by 30-m) Korean rice paddy field. Yield data were manually collected on 10-m by 5-m grids (180 samples with 3 samples in each of 60 grid cells) and chlorophyll content was measured using a Minolta SPAD 502 in 2-m by 2-m grids. Soil samples were collected at 275 points to compare results from sampling at different scales. Ten soil properties important for rice production in Korea were determined through laboratory analyses. Variogram analysis and point kriging with and without median polishing were conducted to determine the variability of the measured parameters. Influence of variogram model selection and other parameters on the interpretation of the data was investigated. For many of the data, maximum values were greater than double the minimum values, indicating considerable spatial variability in the small paddy field, and large-scale spatial trends were present. When variograms were fit to the original data, the limits of spatial dependency for rice yield and SP AD reading were 11.5 m and 6.5 m, respectively, and after detrending the limits were reduced to 7.4 m and 3.9 m. The range of spatial dependency for soil properties was variable, with several having ranges as short as 2 m and others having ranges greater than 30 m. Kriged maps of the variables clearly showed the presence of both large-scale (trend) variability and small-scale variability in this small field where it would be reasonable to expect uniformity. These findings indicate the potential for applying the principles and technology of precision agriculture for Korean paddy fields. Additional research is needed to confirm the results with data from other fields and crops.d similar tendency with the result for the frequency less than 20 Hz, but the width of change was reduced highly.