• 핵의학기술
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• 제13권3호
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• pp.189-192
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• 2009

목적 : 자동분주기의 fixed probe pipetting system 은 검체 분주시 probe 내외부의 잔여물이 다음 pipetting cycle로 이월되어 처음 측정치가 차기 측정치의 결과에 영향을 미치는 이월오염(carryover contamination)을 발생시킬 수 있다. 이번 연구는 본원에 도입된 TECAN 사의 Freedom Evo 100 자동 분주기의 $\alpha$-fetoprotein (AFP)과 carcinoembryonic antigen (CEA) 검사 시 검체간 이월오염 발생을 확인하였다. 방법 : reference 가 되는 오염이 안 된 저농도 검체를 연속분주한다. 그런 후 고농도 검체를 분주한 다음 오염이 예상되는 저농도 검체를 연속 3회 분주하는 과정을 교대로 반복한다. 오염이 안 된 저농도 검체와 오염이 예상되는 저농도 검체값의 각 평균값을 서로 비교하여보고 각 저농도 검체값이 최소 검출 농도 이하인지 확인하고 만약 저농도 검체값간의 평균값이 차이가 있다면 그 차이가 1 ppm 이하의 carryover target 농도값 이하인지 확인한다. 결과 : AFP 약 650,000 IU/mL와 CEA 약 65,000 ng/mL의 고농도 검체에서는 오염이 안 된 저농도 검체값과 오염이 예상되는 저농도 검체값의 평균값 모두 각 검사의 최소 검출 농도값 이하로 이월오염이 나타나지 않았다. 결론 : 이번 연구에서 사용한 AFP와 CEA의 고농도 검체에서는 이월오염이 나타나지 않았지만 검사자는 검사결과 보고시 고농도 검체가 다음 환자 검사결과의 안정성에 영향을 줄 수 있음을 주시하고 이월오염을 확인하기위해 주기적인 장비관리와 이월오염 측정을 시행하여야한다.

• 핵의학기술
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• 제13권3호
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• pp.181-184
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• 2009

목적 : 자동 분주기 (TECAN)의 fixed tip 사용 시 충분한 세척에도 불구하고 고농도 검체 뒤에 연이은 검체가 영향을 받는 carryover 현상이 발생되는 경우가 있다. 이는 검사결과가 위 양성으로 나타날 수 있는 위험성이 있으므로 이상유무 판단을 위해 잦은 재검을 실시해야 하는 번거로움이 있다. 따라서 본 연구는 경제성이 높은 fixed tip을 사용하면서 carryover를 방지할 수 있는 방법을 개선하고자 한다. 실험재료 및 방법 : 자동분주기(Tecan)를 이용하여 HBs Ag, HBs Ab, HBc Ab(IgG) 검사를 대상으로 실행하였으며, fixed tip 방식의 분주시스템으로 일반 환자의 검체 분주 후에 생리식염수를 분주 할 수 있도록 배치하였다. 세척 단계는 0.25mol/L NaOH용액을 이용하였으며, 생리식염수의 검사결과 cpm을 측정하여 carryover의 발생 유무를 확인하였다. 또한 3가지 검사를 0.25 mol/L NaOH 용액이 검사에 미치는 영향을 분석하였다. 결과 : 생리식염수 결과는 100% 음성결과를 보였으며, 0.25 mol/L NaOH를 세척액으로 사용한 fixed tip에서 검체분주 시 환자 혈청은 HBc Ab (IgG)검사에서 cut-off zone (cut-off${\pm}$10%)을 제외한 모든 결과에서 기존 외래보고 결과와 동일한 값을 얻었다. 결론 : 생리식염수 검사결과 100% 음성을 보인 것은 실험에서 사용한 세척액으로 fixed tip을 세척하는 방법이 carryover를 방지할 수 있고, 이로 인해 발생하는 위양성을 방지할 수 있었다. 또한, 환자 검체의 결과 값이 기존 보고 결과와 일치함으로 0.25 mol/L NaOH 용액이 간염 검사결과에 영향을 끼치지 않음을 확인하였다. 따라서 본 실험에서 실시한 방법이 disposable tip보다 상대적으로 경제적인 fixed tip을 사용하면서도 carryover가 없는 정확한 결과를 얻을 수 있는 효과적인 방안임을 알 수 있다.

• Journal of the Korean Statistical Society
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• 제35권3호
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• pp.239-250
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• 2006

A $2{\times}2$ crossover design including carryover effect is considered for assessment of population bioequivalence of two drug formulations in a Bayesian framework. In classical analysis, it is complex to deal with the carryover effect since the estimate of the drug effect is biased in the presence of a carryover effect. The proposed method in this article uses uninformative priors and vague proper priors for objectiveness of priors and the posterior probability distribution of the parameters of interest is derived with given priors. The posterior probabilities of the hypotheses for assessing population bioequivalence are evaluated based on a Markov chain Monte Carlo simulation method. An example with real data set is given for illustration.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.219-230
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• 2015

It is difficult to make plans about the production schedule and volume of seasonal products due to the huge uncertainty in the prediction of their demands, which is why the amounts of carryover seasonal products increase after the peak season. Traditional models fail to meet the important requirements of production and stock plans related to the enhanced efficiency of logistics system due to the reduced value of carryover products by the disposal based on large discounts and deterioration, which poses considerable difficulties with actual problem solving. This study examined the stages of product storage from the specialized factory warehouses during a low season through the stores and the warehouses of local distribution centers during a high season to stock disposal and carryover product warehouses after a high season. The study developed a model for logistics rationalization plans to minimize carryover products by advance selling new products by subscription during a low season in anticipation of high season demands, increasing the accuracy of demands prediction, and making stable production plans, as well as demonstrated its excellence through numerical analysis.

• Journal of Korean Society for Atmospheric Environment
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• 제18권E4호
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• pp.181-190
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• 2002

A novel portable device for the direct measurement of alveolar breath carbon monoxide (CO) was developed. The major components of the device include a mouthpiece, non-rebreathing two-way valve, Teflon tube, and CO dosimeter. An alveolar CO measurement can be completed within 1.5 min when using the proposed device and measurement protocol. Measurements could be read to the nearest 0.1 ppm. Humidity did not influence the CO measurements taken by the CO dosimeter, plus there were no problems associated with the recovery and carryover of CO through the device. The criterion for significance in statistical analyses was p< 0.05. The average recovery was 103 and 99% for recovery and carryover experiments, respectively. Test results using the proposed alveolar CO measurement system reflected a good reproducibility. This reproducibility was also supported by the finding that the relative standard deviations (RSDs) of the data sets were less than 7％ for the loss experiment and less than 8% for the carryover experiment. Consequently, it would appear that the proposed device can be effectively applied to measure CO levels found in breath, thereby overcoming several disadvantages associated with the conventional bag and adsorbent tube sampling methods.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권2호
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• pp.83-88
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• 2005

This study investigates the air leakage and heat transfer characteristics of a commercially available rotary-type air-to-air heat exchanger with a fiber polyester matrix. Crossover leakage between the exhaust and supply air is measured using a tracer gas method for various ventilation rates and rotational speeds of the wheel. A correlation equation for the leakage is obtained by summing up pressure leakage and carryover leakage. The pressure leakage is observed to be a function of ventilation rate only, and the carryover leakage is found to be a linear function of wheel speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiency by taking into account the leakage ratio. The heat recovery efficiency decreases, as the ventilation rate increases. As the wheel speed increases, however, the efficiency increases initially but reaches a constant value for the speeds over 10rpm.

• 설비공학논문집
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• 제16권12호
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• pp.1197-1203
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• 2004

This study investigates the air leakage and heat transfer characteristics of a rotary-type air-to-air heat exchanger with a fiber polyester matrix. The leakage airflow rate is measured using a tracer gas method for various ventilation rates and rotational speeds of the matrix wheel. A correlation equation for air leakage is obtained by combining the pressure leakage and the carryover leakage. The pressure leakage is observed to be a function of ventilation airflow rate only, and the carryover leakage is found to be a linear function of rotational speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiencies by taking into account the air leakage ratio. As the ventilation rate increases, the heat recovery efficiency decreases. As the rotational speed of the matrix increases, the efficiency increases initially but reaches a constant value for the rotational speeds over 10 rpm.

• 한국경영과학회지
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• 제34권2호
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• pp.91-100
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• 2009

"How does advertising affect sales?" is the fundamental issue of modern advertising research. There is an interesting issue for estimating carryover effects of advertising on sales, and the aggregated data biases exist in the duration of advertising effect. This research suggests an extended model of Koyck Model which is employed for micro-data (Koyck 1954) to estimate aggregated advertising data, and empirically shows the aggregated data bias. Our developed model with the aggregated level of actual advertising data is more appropriate than the basic Koyck model for micro-data. The result figures out that it is important to consider the disaggregated data level in the analysis of dynamic effects of adverting such as carryover effects.

• Communications for Statistical Applications and Methods
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• 제7권2호
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• pp.541-548
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• 2000

Various statistical methods for assessment of equivalence in average bioavailabilities have been developed under the assumption that the intra-subject variabilities for the test and reference formulations are the same. Without the assumption, assessing the equivalence in average bioavailabilites does not imply that the two formulations are therapeutically equivalent and exchangeable. The most commonly used test procedure for equality of variabilites in 2$\times$2 crossover experiment is the so called Pitman-Morgan's adjusted F test based on the model without carryover effects (Chow and Liu(1992)). In this paper, a Bayesian method based on the Intrinsic Bayes Factor is proposed, which can be applied to the model with carryover effects.

• 음성과학
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• 제7권3호
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• pp.11-19
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• 2000

The present electropalatographic study reports the production of the allophones. i.e., [l] and [r], of Korean tap /r/ and their coarticulatory characteristics in /$C{\'{a}}r#g$/ and /$C{\'{a}}r#i$/ sequences. The finding that tap /r/ involves a complete oral closure with less lingual contact, i.e., apico-frontalveolar coupling. than lateralized /r/ which involves apico-bladealveolar coupling and tongue dorsum lowering for adequate airflow through either side and/or both of the tongue body suggests that the two allophones of the tap /r/ have different lingual gestures. Moreover. in comparison with the tap. the lateral exerts longer lingual contacts. The mean ratio between them is 3.7. In the sequences /Car#g/. the two adjacent antagonistic segments (i.e., /r/ and /g/) show mutual coarticulation effects taking on features of adjacent segment. but either of them is precisely constrained without blocking the formation of involved major lingual gestures for the other segment. In sequences /Car#i/ occurs anticipatory V-to-C coarticulation but not vocalic carryover effects. In both sequences. the allophones reveal insignificant wordinitial consonantal carryover coarticulatory effects and insignificant speaker-specific lingual contacts.