• 한국환경과학회지
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• 제32권7호
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• pp.483-492
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• 2023

In this study, the treatment of livestock wastewater using an aerobic granular sludge based sequencing batch reactor was investigated. The reactor operation was carried out by general injection and split injection methods. The average removal efficiency of organic matter after the adaptation period was 71.5 and 87.4%, respectively. Some untreated organic matter was attributed to recalcitrant organic matter. The average removal efficiency of total nitrogen was 65.6 and 88.4%, respectively. These results indicate that the denitrification reaction by split injection was carried out smoothly. As for the solids, the ratio of aerobic granular sludge/mixed liquor suspended solid can be determined as the main factor of the process operation, and the ratio increased gradually and finally reached 86.0%. Correspondingly, the sludge volume index (SVI) was also improved, reaching 54 mL/g at the end of operation, and it is believed that the application of a short settling time contributed to the improvement of settleability.

• 대한인간공학회지
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• 제32권6호
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• pp.535-540
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• 2013

Objective: The aim of this study is to evaluate the effectiveness and efficiency of causal links between various error causes in human error analysis. Background: As finding root causes of human error in safety-critical systems is often a cognitively demanding and time-consuming task, it is particularly necessary to develop a method for improving both the quality and efficiency of the task. Although a few methods such as CREAM have suggested causal linking between error causes as a means to enhance the quality and efficiency of human error analysis, no published research to date has evaluated the performance of the causal links. Method: The performance of the CREAM links between error causes were evaluated with 80 railway accident investigation reports from the UK. From each report, errorneous actions of operators were derived, and for each error, candidate causes were found by following the predefined links. Two measures, coverage and selectivity, were used to evaluate the effectiveness and efficiency of the links, respectively. Results: On average, 96% of error causes actually included in the accident reports were found by following the causal links, and among the total of 121 possible error causes, the number of error causes to be examined further was reduced to one-tenth on average. As an additional result of this work, frequent error causes and frequently used links are provided. Conclusion: This result implies that the predefined causal links between error causes can significantly reduce the time and effort required to find the multiple levels of error causes and their causal relations without losing the quality of the results. Application: The CREAM links can be applied to human error analysis in any industry with minor modifications.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1754-1759
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• 2022

The activity of gamma-ray emitting nuclides is calculated assuming that each gamma-ray is detected individually; thus, the magnitude of the coincidence summing signal must be considered during activity calculations. Here, the correction factor for the coincidence summing effect was calculated, and the detection efficiencies of two HPGe detectors were compared. The CANBERRA Inc. GC4018 high-purity Ge detector provided an estimate for the peak-to-total ratio using a point source to determine the coincidence summing correction factor. The ORTEC Inc. GEM60 high-purity Ge detector uses EFFTRAN in LVis to obtain the parameters of the detector and source model and the gamma-gamma and gamma-X match estimates, in order to determine the coincidence summing correction factor. Nuclide analyses, radioactivity comparisons, and analyses of reference material samples were performed utilizing certified reference materials to accurately determine the detection efficiencies. For both Co-60 and Y-88, the detection efficiency for a point source increased by an average of at least 12-13%, whereas the detection efficiency determined using LVis increased by an average of at least 13-15%. The calculated radioactivity values of the certified reference material and reference material samples were accurate to within 3% and 6% of the measured values, respectively.

• Environmental Engineering Research
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• 제25권1호
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• pp.71-79
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• 2020

This paper uses super-efficiency DEA model and Malmquist index to evaluate the carbon emission efficiency (CEE) values of the nine western provinces along the "Silk Road Economic Belt" for the period from 2000 to 2015, and analyses the influencing factors of the CEE. The major findings of this study are the following: (1) the overall CEE of the nine western provinces is not high, and there are significant inter-provincial differences in the CEE. Meanwhile, the provinces with higher levels of economic development generally have higher CEE. (2) The annual total factor productivity (TFP) of the nine western provinces, which is mainly determined by technological change, is greater than 1. Moreover, the total average growth rate of the TFP is 15.5%. (3) The CEE of the nine western provinces is not spatially dependent. In addition, the urbanization, openness, use of energy-saving technologies and research and development (R&D) investment have a significant positive impact on the CEE values, while the industrial structure, foreign direct investment, fixed asset investment, government expenditure levels and energy structure have a significant negative impact on the CEE. Among them, R&D investment is the primary factor in promoting the development of CEE, and the government expenditure has the greatest negative impact on the CEE.

• ETRI Journal
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• 제39권3호
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• pp.301-309
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• 2017

In this paper, we propose a parallelization method for a High Efficiency Video Coding (HEVC) deblocking filter with transform unit (TU) split information. HEVC employs a deblocking filter to boost perceptual quality and coding efficiency. The deblocking filter was designed for data-level parallelism. In this paper, we demonstrate a method of distributing equal workloads to all cores or threads by anticipating the deblocking filter complexity based on the coding unit depth and TU split information. We determined that the average time saving of our proposed deblocking filter parallelization method has a speed-up factor that is 2% better than that of the uniformly distributed parallel deblocking filter, and 6% better than that of coding tree unit row distribution parallelism. In addition, we determined that the speed-up factor of our proposed deblocking filter parallelization method, in terms of percentage run-time, is up to 3.1 compared to the run-time of the HEVC test model 12.0 deblocking filter with a sequential implementation.

• 응용통계연구
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• 제14권1호
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• pp.59-70
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• 2001

이면교배 실험은 식물이나 동물의 교배를 통해 자식계통의 유전적인 성질을 조사하는데 중용한 역할을 한다. 이면교배에 관한 기존의 연구에서는 p개의 자식계통은 하나의 집합에 속하는 것으로 간주하였다. 이와 달리 새로 육성된 자식계통의 유전적 성질을 평가하고자 하는 경우에는, p개의 자식계통이 각각 p$_1$과 p$_2$개의 자식계통을 갖는 두 개의 집합으로 분리되는 형태의 교배실험을 사용한다(단, p=p$_1$+p$_2$). 이에 본 연구에서는 자식계통이 두 집단으로 분리된 경우에 대해서 Kempthorne의 합동식을 이용하여 두 군간 교배에 대한 블록디자인을 설계하고, 이에 대한 평균효율인자를 계산하는 방법을 제안하고자 한다.

• 한국광학회지
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• 제16권2호
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• pp.143-145
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• 2005

본 논문은 5.12-Tb/s(128 채널 ${\times} 43 Gb/s$) WDM 신호의 200 km 전송실험에 관한 것이다. 본 실험에서는 Medium Dispersion Fiber를 사용하여 0.8-(bits/s)/Hz의 스펙트럼 효율을 구현하였다. 전송 후 측정된 평균 Q-factor값은 15.2 dB이었다.

• 전력전자학회논문지
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• 제2권3호
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• pp.26-36
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• 1997

본 논문에서는 저용량의 응용 분야에 적합한 half-bridge 컨버터를 기반으로 하는 단상 AC/DC 컨버터를 제안한다. 제안된 컨버터는 고역률, 저하모닉 왜곡의 특성이 있으며 좋은 출력 레귤레이션 특성을 가지고 있다. 그리고 asymmetrical 제어를 통해 소프트 스위칭을 함으로써 스위칭 손실을 줄였으며 출력단의 정류손실을 줄이기 위해서 synchronous rectifier를 적용하였다. 또한 본 컨버터를 체계적으로 설계하기 위해 평균화법을 통한 모델링을 수행하여 설계식을 도출하였다. 이 설계식을 통하여 프로토타입 컨버터를 설계하여 실험한 결과 제안된 컨버터는 IEC555-2 규제를 만족하였고 정격에서 효율은 약 85%를 얻었다.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.67-73
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• 1998

본 연구에서는 기존의 정류회로가 포함하고 있는 고조파 발생과 역률저하문제를 개선하기 위한 방안으로 BPFC(Boost Power Factor Collection)방식을 사용하였다. 이 BPFC는 고역률올 구현하기 위해 가장 널리 쓰이는 방식중의 하나로서 입력전압과 거의 동둥한 지속적인 인덕터 전류를 정현파에 가까운 형태로 제어할 수 있다는 장점을 가지고 있다. 또한 BPFC는 제어방식에 의해 크게 달라질 수 었다. 본 논문에서는 순간모드선택 피크 전류제어방식과 PWM 평균전류 재어방식을 이용한 고역률 저고조파를 갖는 정류회로를 구성하여 각각에 대하여 비교분석하였다.

• 수산경영론집
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• 제43권2호
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• pp.67-77
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• 2012

Based on the survey on aquaculture management status in Nohwa-eup, Bogil-myeon, Wando-eup in Wando region, this study aimed to estimate productive efficiencies of abalone aquaculture production using a stochastic frontier approach (SFA) and to find out their determinants. In the analysis, a Cobb-Douglas production function with an inefficiency term that follows an halfnormal distribution was assumed for the estimation of productive efficiencies. Then, based on the outcomes of productive efficiencies, determinants of productive efficiency were investigated using a tobit regression model. Results showed that the average inefficiency was estimated to be 10% and the production size would be a statistically significant variable for the production. In addition, it was shown that the cage installing method would be an important factor affecting to the level of productive efficiency.