• 분석과학
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• 제20권1호
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• pp.10-16
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• 2007

생활폐기물 열분해-가스화-용융공정 2개 시설(A 및 B 시설)에 대하여 PCDDs/PCDFs 농도를 조사한 결과, A시설은 2차연소로후단, 보일러후단, 굴뚝에서 PCDDs/PCDFs의 농도는 각각 0.88, 2.29, 0.16 ng I-TEQ/$m^3$으로 나타났다. B시설에서 열분해-가스화-용융로후단, 굴뚝에서 PCDDs/PCDFs 농도는 각각 0.22, 0.05 ng I-TEQ/$m^3$로 나타났다. 두 시설 모두에서 고온의 연소로보다 냉각구간의 보일러에서 다이옥신의 재합성으로 인하여 농도가 증가되었다. 또한 A시설에서는 2, 3, 4, 7, 8-PeCDF, 2, 3, 4, 6, 7, 8-HxCDF, 1, 2, 3, 6, 7, 8-HxCDF 순서로 높은 농도를 나타냈으며, B시설은 2, 3, 4, 7, 8-PeCDF, 1, 2, 3, 7, 8-PeCDD, 2, 3, 4, 6, 7, 8-HxCDF 순서로 높게 나타났다.

• 한국가금학회지
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• 제21권2호
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• pp.73-82
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• 1994

A study was conducted to develop a new analytical method to quantitate chicken dietary fiber (CDF). Four types of grain diets and 2 types of forages were used. Three broiler chicks at eight weeks of age were used in the Latin square design to estirnate the in vivo digestibility. Six quantitative analytical methods (Southgate method, total dietary fiber or TDF, acid detergent fiber or ADF, neutral detergent fiber or NDF, crude fiber or CF) including CDF were compared in this study. ADF, NDF and CF contained the lowest amount of the unavailable carbohydrate(UC). The value of TDF was higher than the values of ADF, NDF and CF and lower than CDF and the Southgate method. The value of NDF showed the lower values than the CDF, Southgate fiber and TDF. The recovery rate of the fiber in the feces was high in the TDF, ADF, NDF and CF, while CDF and Southgate fiber showed lower recovery rates. TDF, NDF, ADF, or CF can replace chromium in the digestibility test, while the CDF and Southgate fiber can not replace chrorniurn. The digestibility of TDF, NDF, ADF and CF in the chicken showed negative values or values close to zero depending on the types of feed but the digestibility of CDF and Southgate fiber showed relatively high positive values.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제20권11호
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• pp.610-614
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• 2014

많은 과학 데이타처럼 화산재 확산 시뮬레이션 결과는 NetCDF 형식의 군집화된 희소행렬이다. 그리고 크기가 커서 저장과 전송에 많은 비용이 발생한다. 본 논문에서는 다차원 인덱스를 일차원으로 바꾸고 연속된 0을 그 시작점과 길이만을 기록하여 화산재 확산 시뮬레이션 데이터의 크기를 줄이는 방법을 제안한다. 이 방법은 기존의 ZIP 형식으로 압축한 것과 거의 같은 성능을 보이나 NetCDF의 구조는 손상하지 않는다. 제안된 방법에 의하면 데이터 크기가 줄어들어 저장공간의 효율이 높아지고 네트워크 전송시간이 줄어드는 효과를 기대할 수 있을 것이라 사료된다.

• Journal of KIEE
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• 제11권1호
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• pp.69-77
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• 2001

This paper describes an image processing algorithm capable of recognizing road lanes by using a CDF(cumulative distribution function). The CDF is designed for the model function of road lanes. Based on the assumptions that there are no abrupt changes in the direction and location of road lanes and that the intensity of lane boundaries differs from that of the background, we formulated the CDF, which accumulates the edge magnitude for edge directions. The CDF has distinctive peak points at the vicinity of lane directions due to the directional and the positional continuities of a lane. To obtain lane-related information a scatter diagram was constructed by collecting edge pixels, of which the direction corresponds to the peak point of the CDF, then the principal axis-based line fitting was performed for the scatter diagram. Noises can cause many similar features to appear and to disappear in an image. Therefore, to reduce the noise effect a recursive estimator of the CDF was introduced, and also to prevent false alarms or miss detection a scene understanding index (DUI) was formulated by the statistical parameters of the CDF. The proposed algorithm has been implemented in real time on video data obtained from a test vehicle driven on a typical highway.

• 한국통신학회논문지
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• 제41권8호
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• pp.924-927
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• 2016

In this paper, we consider a cumulative distribution function (CDF)-based opportunistic scheduling for downlink transmission in a cellular network consisting of a base station and multiple mobile stations. We present a closed-form formula for the average starvation period of each mobile station (i.e., the length of the time interval between two successive scheduling points of a mobile station) over Markov time-varying channels. Based on our formula, we investigate the starvation period of the CDF-based scheduling for various system parameters.

• 한국물환경학회지
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• 제24권6호
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• pp.758-766
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• 2008

먹는물 처리 전후 다이옥신류의 동족체 패턴 및 제거율을 평가하기 위해서 42개의 일본 정수처리장에서 2년간 122개의 시료를 채취해 dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) 및 coplanar polychlorinated biphenyls (Co-PCBs)를 분석하였다. 다이옥신류의 평균 농도와 독성등가값 (toxic equivalent, TEQ)은 원수와 처리수에서 각각 60.24 pg/L (0.14 pg-WHO-TEQ/L), 4.15 pg/L (0.016 pg-WHO-TEQ/L)였다. 먹는물의 다이옥신류 기여 농도는 일일섭취량 (tolerable daily intake (TDI), 4 pg-TEQ/kg/day)의 0.016%이었다. 정수처리에 의한 다이옥신류의 평균 TEQ 제거율은 88% 이상이었다. 그러나 112개의 샘플에서 2, 3, 7, 8-TeCDF (tetrachlorodibenzofuran)의 농도는 17% 증가하였다. 따라서, 2, 3, 7, 8-TeCDF의 농도에 영향을 미치는 공정을 파악하기 위하여 고도정수처리 및 일반정수처리에서의 제거율을 조사하였다. 다이옥신 동족체(congener)인 TeCDF와 non-ortho-PCB는 고도처리 및 표준정수처리에서 염소소독처리 후 TEQ 농도가 증가함을 보여, 먹는물 중 2, 3, 7, 8-TeCDF 농도는 염소소독처리에 의해 상승한 것으로 밝혀졌다.

• 한국인터넷방송통신학회논문지
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• 제21권4호
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• pp.37-42
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• 2021

NOMA (Non-orthogonal multiple Access) 시스템은 스펙트럼의 효율이 높아서 차세대 이동통신 방식으로 주목을 받고 있지만, 여러 사용자가 동시에 채널을 엑세스 하는 다중 사용자 시스템이므로 사용자 스케쥴링이 필요하다. 대표적인 스케쥴링 방식으로 PF (Proportional fairness) 스케쥴링 방식과 CDF (Cumulative distribution function) 스케쥴링 방식이 있는데, PF 스케쥴링 방식은 셀 가장자리에 위치한 사용자는 전송기회를 갖기가 매우 어렵다. 그러므로 최근에는 사용자들의 위치와 무관하게 동일한 전송기회를 갖는 CDF 스케쥴링이 주목을 받고 있다. 본 논문에서는 상향 NOMA 시스템에 CDF 스케쥴링을 적용하였을 때 사용자의 채널 획득확률, 사용자 수에 따른 오수신율, 그리고 송신 가중치에 따른 시스템의 오수신율을 시뮬레이션을 통하여 구하였다. 시뮬레이션 결과 각각의 사용자들의 채널 획득 확률이 동일함을 확인하였고, 사용자의 수가 증가할수록 오수신율은 감소하였다. 그리고 셀 가장 자리에 있는 사용자의 송신 가중치를 증가하여도 시스템의 오수신율에 미치는 영향은 미미함을 알 수 있었다.

• 한국안전학회지
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• 제36권3호
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• pp.66-73
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• 2021

This report documents the results of an at-power internal events Level 1 Probabilistic Safety Assessment (PSA) for a Korea research reactor (KRR). The aim of the study is to determine the accident sequences, construct an internal level 1 PSA model, and estimate the core damage frequency (CDF). The accident quantification is performed using the AIMS-PSA software version 1.2c along with a fault tree reliability evaluation expert (FTREX) quantification engine. The KRR PSA model is quantified using a cut-off value of 1.0E-15/yr to eliminate the non-effective minimal cut sets (MCSs). The final result indicates a point estimate of 4.55E-06/yr for the overall CDF attributable to internal initiating events in the core damage state for the KRR. Loss of Electric Power (LOEP) is the predominant contributor to the total CDF via a single initiating event (3.68E-6/yr), providing 80.9% of the CDF. The second largest contributor is the beam tube loss of coolant accident (LOCA), which accounts for 9.9% (4.49E-07/yr) of the CDF.

• 한국안전학회지
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• 제35권3호
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• pp.86-95
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• 2020

This paper describes the work and the results of the final Probabilistic Safety Assessment (PSA) for the Jordan Research and Training Reactor (JRTR). This final PSA was undertaken to assess the level of safety for the design of a research reactor and to evaluate whether it is probabilistically safe to operate and reliable to use. The scope of the PSA described here is a Level 1 PSA, which addresses the risks associated with core damage. After reviewing the documents and its conceptual design, nine typical initiating events were selected regarding internal events during the normal operation of the reactor. AIMS-PSA (Version 1.2c) was used for the accident quantification, and FTREX was used as the quantification engine. 1.0E-15/yr of the cutoff value was used to deliminate the non-effective Minimal Cut Sets (MCSs) when quantifying the JRTR PSA model. As a result, the final result indicates a point estimate of 2.02E-07/yr for the overall Core Damage Frequency (CDF) attributable to internal initiating events in the core damage state for the JRTR. A Loss of Primary Cooling System Flow (LOPCS) is the dominant contributor to the total CDF by a single initiating event (9.96E-08/yr), and provides 49.4% of the CDF. General Transients (GTRNs) are the second largest contributor, and provide 32.9% (6.65E-08/yr) of the CDF.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2092-2098
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• 2024

Probabilistic safety assessment (PSA) plays a critical role in ensuring the safe operation of nuclear power plants. In PSA, event trees are developed to identify accident sequences that could lead to core damage. These event trees are then transformed into a core-damage fault tree, wherein the accident sequences are represented by usual and complemented logic gates representing failed and successful operations of safety systems, respectively. The core damage frequency (CDF) is estimated by calculating the minimal cut sets (MCSs) of the core-damage fault tree. Delete-term approximation (DTA) is commonly employed to approximately solve MCSs representing accident sequence logics from noncoherent core-damage fault trees. However, DTA can lead to an overestimation of CDF, particularly when fault trees contain many nonrare events. To address this issue, the present study introduces a new zero-suppressed ternary decision diagram (ZTDD) algorithm that averts the CDF overestimation caused by DTA. This ZTDD algorithm can optionally calculate MCSs with DTA or prime implicants (PIs) without any approximation from the core-damage fault tree. By calculating PIs, accurate CDF can be calculated. The present study provides a comprehensive explanation of the ZTDD structure, formula of the ZTDD algorithm, ZTDD minimization, probability calculation from ZTDD, strength of the ZTDD algorithm, and ZTDD application results. Results reveal that the ZTDD algorithm is a powerful tool that can quickly and accurately calculate CDF and drastically improve the safety of nuclear power plants.