• 분석과학
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• 제14권1호
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• pp.64-71
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• 2001

본 논문에서는 검출한계에 대한 기본개념을 기초로 백그라운드 측정시간과 시료측정시간을 고려한 검출한계치 유도과정을 기술하였다. 환경시료 중 Pu의 MDA값 결정에 영향을 미치는 여러인자들 중에서 시료량, 백그라운드 측정시간 및 시료측정시간 변화에 따른 MDA 변동값을 계산하였다. 환경시료에 대한 저준위 방사능 동위원소 측정시 본 연구결과를 통해 도출된 백그라운드 및 시료 측정시간의 적절한 배분에 의한 MDA 계산은 환경방사능 측정결과에 대한 신뢰도 평가에 활용이 가능하다.

• 응용통계연구
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• 제25권3호
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• pp.389-401
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• 2012

This paper derives a benchmark dose(BMD) and its 95% lower confidence limit(BMDL) using a semi-parametric regression model for small lead based changes in attention-deficit hyperactivity disorder(ADHD) scores in the first wave of the Children's Health and Environment Research(CHEER) survey data, which have been regularly collected in South Korea since 2005. Ha et al. (2009) showed that the appearance of ADHD symptoms had a borderline trend of increasing with the blood lead concentration. Butdz-J${\o}$rgensen (EFSA, 2010a) derived the BMDL of lead corresponding to a benchmark region of 1 full intelligent quotient (IQ) score using the raw data in Lanphear et al. (2005, EHP). European Food Safety Authority (EFSA, 2010b) determined the BMDL of $1.2{\mu}g/dl$ as a reference point for the characterization of lead when assessing the risk of the intellectual deficit measured by IQ scores. Kim et al. (2011) indicated that an even lower BMDL could be obtained based on the ADHD score; however, the BMDLs depended heavily upon the model assumptions. We show in this paper that a semi-parametric approach resolves the model dependence of BMDLs.

• Nuclear Engineering and Technology
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• 제46권4호
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• pp.481-488
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• 2014

An analysis of the uncertainty quantification related to LBLOCA using the Monte-Carlo calculation has been performed and compared with the tolerance level determined by the Wilks' formula. The uncertainty range and distribution of each input parameter associated with the LOCA phenomena were determined based on previous PIRT results and documentation during the BEMUSE project. Calulations were conducted on 3,500 cases within a 2-week CPU time on a 14-PC cluster system. The Monte-Carlo exercise shows that the 95% upper limit PCT value can be obtained well, with a 95% confidence level using the Wilks' formula, although we have to endure a 5% risk of PCT under-prediction. The results also show that the statistical fluctuation of the limit value using Wilks' first-order is as large as the uncertainty value itself. It is therefore desirable to increase the order of the Wilks' formula to be higher than the second-order to estimate the reliable safety margin of the design features. It is also shown that, with its ever increasing computational capability, the Monte-Carlo method is accessible for a nuclear power plant safety analysis within a realistic time frame.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1995년도 한국우주과학회보 제4권2호
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• pp.30-30
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• 1995

We present the results of analysis on the X-ray observations of the binary X-ray pulsar Her X-I. made with ASCA/SIS on August 13-14. 1993. An eclipse transition from ingress to egress was fully covered by the observations. The main findings are as follows; (1) a model of power-law plus black-body is required to interpret the entire eclipse spectrum. and the black-body component appears at < 0.7 keV. (2) the power-law continuum which has photon index ${\alpha}\;=\;{0.84^{\;+0.14}}_{\;-0.19}$ is very similar to that of detected by Ginga/LAC (${\alpha}\;=\;0.80\;{\pm}\;0.04$), (3) the calculated eclipse flux of $2^{-10}\;keV.{\;}~{\;}1.8{\pm}10^{-11}{\;}ergs{\;}cm^{-2}s^{-1}$, is consistent with the Ginga observation carried out in the high intensity state ~2.0{\pm}10^{-11}{\;}ergs{\;}cm^{-2}s^{-1}$, (4) there is no significant absorption feature. and an upper limit of the aborption column $NH{\;}\leq{\;}3{\pm}10^{20}\;cm^{-2}$ is determined at the 90% confidence limit. Based on these results, we suggest that extended matter surrounding the binary system should be existed persistently with stable conditions, and scattering of the source continuum by the matter is responsible for the eclipse emission.ission.

• 안보군사학연구
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• 통권5호
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• pp.173-202
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• 2007

After successful nuclear tests Pakistan launched a more severe surprise attack toward India than before. It is highly possible that North Korea will adopt this Pakistan military strategy if it is armed with nuclear weapons. The North Korean forces armed, with nuclear bombs could make double its war capability through strengthening aggressive force structure and come into effect on blocking reinforcement of the US forces at the initial phase of war time. Therefore we may regard that Pyongyang's nuclear arming is a major one of various factors which increase possibility of waging a conventional warfare or a nuclear war. North Korea's high self-confidence after nuclear arming will heighten tension on the Korean Peninsula via aggressive military threat or terror toward South Korea, and endeavor to accomplish its political purpose via low-intensity conflicts. For instance, nuclear arming of the Pyongyang regime enforces the North Korean forces to invade the Northern Limit Line(NLL), provoke naval battles at the West Sea, and occupy one or two among the Five Islands at the West Sea. In that case, the South Korean forces will be faced with a serious dilemma. In order to recapture the islands, Seoul should be ready for escalating a war. However it is hard to imagine that South Korea fights with North Korea armed with nuclear weapons. This paper concludes that the Pyongyang regime after nuclear arming strongly tends to occupy superiority of military strategy and wage military provocations on the Korean Peninsula.

• 응용통계연구
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• 제27권4호
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• pp.645-653
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• 2014

p-값은 관측 표본과 관측 결과보다 심하게 대안가설의 방향으로 영가설을 이탈하는 표본들이 영가설 하에서 갖는 확률이다. p-값이 일정 ${\alpha}$(= 0:05)보다 작게 나타나면 연구자는 대안가설이 지지된 것으로 본다. 그런 경우라고 하더라도 그의 가설이 향후 연구에서 번복될 수 있는데 그 이유는 p-값이 표본에 따라 변동하는 통계량이기 때문이다. Boos와 Stefanski (2011)는 붓스트랩 방법으로 p-값의 예측분포를 구할 수 있음을 보였다. 그들은 그 분포의 상위 10-20% 분위수가 ${\alpha}$보다 작은가를 확인할 필요가 있음을 강조한다. 만약 그렇지 않은 경우에는 "지지"된 가설의 재현성이 문제될 수 있기 때문이다. 가설검정에서 일정 수준의 재현율을 확보하기 위해서는 표본의 증대가 요구된다. 이 연구는 k배 확대 붓스트랩 표본추출(boosted bootstrap sampling)로써 필요한 표본크기를 계산할 수 있음을 두 표본의 비교와 다중선형회귀의 수치 예에서 보인다. k 값을 정하기 위해서는 몇 차례 시행착오를 해야 하지만 계산적 부담은 크지 않다. 95% 신뢰구간은 독립적인 표본들로부터 같은 방식으로 산출되는 구간이 미지의 모수를 포함할 확률이 95%가 되도록 설정된다. 이 연구는 한 관측표본으로부터 얻어진 95% 신뢰구간 내 개별 점이 미래 연구의 신뢰구간에도 포함될 것인지 그 재현성을 붓스트랩 재표본들에서 평가한다. 이 연구는 개별 점에서 산출한 신뢰구간 재현율을 그래프로 보인다.

• 한국식품조리과학회지
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• 제31권2호
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• pp.112-117
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• 2015

The analytical method for ethyl carbamate (EC) in maesil (Prunus mume) extract was developed with deuterium-labeled ethyl carbamate as an internal standard. Samples were neutralized with an addition of 1 N sodium hydroxide solution, followed by a solid phase extraction with a Chem Elut cartridge. A standard curve exhibited a good linearity with correlation coefficient of 0.9991. The limit of detection (LOD) and limit of quantification (LOQ) were 2.91 ng/g and 8.83 ng/g, respectively. The recovery rate of EC ranged from 91.40% to 120.90%. The precision never exceeded 12.57% (intra-day) and 11.03% (inter-day). Samples were comprised of 24 home-made and 7 commercially-available maesil extracts. Eight home-made samples contained EC at levels between 3.39 and 75.76 ng/g. Three commercially-available samples had EC at levels between 11.67 and 20.16 ng/g. Average daily intakes of EC from maesil extracts for consumers were 0.23 g/kg of body weight. Based on a benchmark dose confidence limit ($BMDL_{10}$) of 0.25 mg/kg of body weight/day, the margin of exposure (MOE) of EC in maesil extract for consumers was 94,150, which is not of concern. Considering that a daily intake of maesil extract has been increasing, further studies on the formation of EC in maesil extract is needed.

• 한국환경농학회지
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• 제41권3호
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• pp.153-157
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• 2022

BACKGROUND: The residue dissipation pattern of pesticides for agricultural products during the pre-harvest period after the final application is important to prevent the maximum residue limit (MRL) violations in domestic and export markets. The MRL violations of carbendazim are observed more often in chamnamul by pesticide residue management surveys by the Ministry of Food and Drug Safety. The residue level at the pre-harvest interval (PHI) and the residue dissipation constant from the critical good agricultural practice (cGAP) trials could be estimated to meet the MRL and pose a health risk to consumers. METHODS AND RESULTS: Chamnamuls were harvested at 0, 1, 3, 5, 7, 10, and 14 days after application of carbendazim in accordance with critical GAP. The residue analysis in chamnanul was performed by HPLC-DAD with the C₁₈ column. The limit of quantitation of carbendazim was 0.04 mg/kg, and the recoveries were 74.4 - 95.8% at the two spiked levels (LOQ and 10LOQ) of carbendazim. The dissipation rates in chamnamul were calculated from the residues at the sampling days by statistical method at a 95% confidence level. The biological half-lives of residual carbendazim in the field trials 1 and 2 were 4.9 and 4.4 days, respectively. CONCLUSION(S): In this dissipation study, the residue concentrations at the recommended PHI were higher than the established MRL in Korea. Therefore, the MRL is proposed based on the residue data sets from the trials conducted at the same cGAP and the dietary exposure assessment.

• 분석과학
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• 제35권6호
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• pp.267-273
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• 2022

본 연구에서는 어묵의 유통기한을 소비기한으로 변경하기 위해 품질평가를 진행하였다. 제품 품질 평가를 위해 보관 조건은 5, 10, 15 ℃로 설정하고 pH, 산가, 휘발성염기질소, 세균수, 대장균군 등 5가지 항목에 대한 실험을 진행하였다. 실험결과 어묵의 품질유지한계기간은 5 ℃에서 43일, 10 ℃에서 30일, 15 ℃에서 7일이었다. 품질평가에 사용된 5가지 시험항목 중 품질한계지표가 있는 항목은 산가, 세균수, 대장균군이었다. 그리고 3가지 보관조건에서 품질유지한계기간을 결정하는 지표는 세균수였다. 본 실험에 사용된 어묵의 유통기한은 10일이나 품질평가를 통해 10 ℃에서의 소비기한은 28.5일로, 품질유지한계기간인 30일에 안전계수 0.95를 곱한 값이다. 그러나 본 연구는 1개 업체의 어묵 1품목에 대한 품질평가를 수행하였기에, 본 연구에서 설정한 품질유지한계기간 및 소비기한을 보편적으로 사용하기에는 무리가 있다. 유통기한을 소비기한으로 변경하기 위해서는 다양한 제품에 대한 광범위한 품질 연구가 필요하다. 이 제도가 잘 갖춰진다면 올바른 음식물 섭취를 통해 음식물폐기물을 줄이는 데 도움이 될 수 있고, 소비자들은 안심하고 식품을 섭취할 수 있다.

• 대한인간공학회지
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• 제27권2호
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• pp.9-14
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• 2008

Coherence can be used to evaluate the functional cortical connections between the motor cortex and muscle. This study is to find coherence between EEG (electroencephalogram) and EMG (electromyogram) evoked by movement of a hand. Seven healthy participants were asked to perform thirty repetitive movement of right hand for ten seconds with rest for ten seconds. Specific feature of EEG components has been extracted by ICA (independent component analysis) and coherence between EEG and EMG was analyzed from data measured EEG in five local areas around central part of head and EMG in flexer carpri radialis muscle during grabbing movement. Coherence between EEG and EMG was successfully obtained at 0.025 confidence limit during hand movement and showed significant difference between rest and movement at 13-18Hz.