• Nuclear Engineering and Technology
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• 제30권6호
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• pp.496-506
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• 1998

This paper deals with the computational modeling of buoyancy-driven turbulent heat transfer involving spatially uniform volumetric heat sources in semicircular geometry. The Launder & Sharma low-Reynolds number k-$\varepsilon$ turbulence model without any modifications and the SIMPLER computational algorithm were used for the numerical modeling, which was incorporated into the new computer code CORE-TNC. This computer code was subsequently benchmarked with the Mini-ACOPO experimental data in the modified Rayleigh number range of 2$\times$10$^{13}$ $\times$10$^{14}$ . The general trends of the velocity and temperature fields were well predicted by the model used, and the calculated isotherm patterns were found to be very similiar to those observed in previous experimental investigations. The deviation between the Mini-ACOPO experimental data and the corresponding numerical results obtained with CORE-TNC for the average Nusselt number was less than 30% using fine grid in the near-wall region and the three-point difference formula for the wall temperature gradient. With isothermal pool boundaries, heat was convected predominantly to the upper and adjacent lateral surfaces, and the bottom surface received smaller heat fluxes.

• 조명전기설비학회논문지
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• 제20권1호
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• pp.27-33
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• 2006

건축 실내의 조명환경의 쾌적성을 평가하는 것은 주로 불쾌감을 유발하는 글레어의 정도를 인식하는 것이라 할 수 있다. 현재 국외에서 연구된 불쾌글레어를 평가하기 위한 실험식을 그대로 적용하기에는 글레어의 감각을 느끼는 정도가 인종에 따라 크게 다르게 나타나기 때문에 무리가 있다. 따라서 본 연구에서는 한국인의 시각적인 특성에 맞는 합리적인 불쾌글레어 평가를 위한 예측식을 작성하는 것을 최종목표로 하였으며 다음과 같이 4단계로 연구를 진행하였다. 첫째, 기존의 불쾌글레어 평가식에 대한 검토를 통해 실험변인들을 선정하였다. 둘째, 본 연구의 목적에 맞는 실험변인과 조건을 제어할 수 있는 실물대모형을 제작하였다. 셋째, 불쾌글레어 평가실험을 실시하였다. 최종적으로, 선행연구에서 서양인을 대상으로 제안된 UGR평가법과의 비교분석을 실시하였다. 연구의 결과를 요약하면, 1)불쾌글레어는 광원휘도, 배경휘도, 피험자와 시선의 위치 등에 크게 영향을 받는 것으로 나타났다. 2)실내 불쾌글레어 평가에서 광원과 피험자간의 거리보다 시야내에 글레어 광원이 위치하는 지의 여부가 더 중대한 영향을 미쳤다. 3)대표적인 불쾌글레어 평가시스템인 UGR과 비교 분석한 결과 다소 차이가 있는 것으로 나타났다. 이것은 한국인의 불쾌글레어감이 서양인과 차이가 있다는 것을 보여준다.

• Computers and Concrete
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• 제19권6호
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• pp.717-724
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• 2017

In this paper, four formulas are proposed via gene expression programming (GEP)-based models and regression analysis (RA) to predict the flexural strength ($f_s$) values of mortars containing different mineral admixtures that are ground granulated blast-furnace slag (GGBFS), silica fume (SF) and fly ash (FA) at different ages. Three formulas obtained from the GEP-I, GEP-II and GEP-III models are constituted to predict the $f_s$ values from the age of specimen, water-binder ratio and compressive strength. Besides, one formula obtained from the RA is constituted to predict the $f_s$ values from the compressive strength. To achieve these formulas in the GEP and RA models, 972 data of the experimental studies presented with mortar mixtures were gathered from the literatures. 734 data of the experimental studies are divided without pre-planned for these formulas achieved from the training and testing sets of GEP and RA models. Beside, these formulas are validated with 238 data of experimental studies un-employed in training and testing sets. The $f_s$ results obtained from the training, testing and validation sets of these formulas are compared with the results obtained from the experimental studies and the formulas given in the literature for concrete. These comparisons show that the results of the formulas obtained from the GEP and RA models appear to well compatible with the experimental results and find to be very credible according to the results of other formulas.

• Child Health Nursing Research
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• 제26권3호
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• pp.376-384
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• 2020

Purpose: This study aimed to determine the influence of a breastfeeding coaching program (BCP) for mothers of late preterm infants (LPIs) on the breastfeeding rate and neonatal morbidity within 1 month after discharge. Methods: This was a non-randomized quasi-experimental study with a time series design. The participants were 40 LPIs and their mothers who were hospitalized in a neonatal intensive care unit at a university hospital. Nineteen LPIs were assigned to the control group, and 21 to the experimental group. The mothers of the LPIs in the experimental group received the BCP once on the discharge day and then once a week for 1 month. Neonatal morbidity was defined as an outpatient department or emergency room visit due to an LPI's health problem. Results: The breastfeeding rate in the experimental group was significantly higher than in the control group at the fourth week after discharge (χ²=7.17, p=.028). Five and two LPIs in the control group and the experimental group, respectively, visited a hospital due to neonatal jaundice. Neonatal morbidity was not significantly different between the two groups (χ²=1.95, p=.164). Conclusion: The BCP was useful for improving the breastfeeding rates of LPIs and may have potential to reduce neonatal morbidity.

• Mass Spectrometry Letters
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• 제10권3호
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• pp.93-101
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• 2019

Algorithms and software for predicting tandem mass spectra have been developed in recent years. In this work, we explore how distinct in silico $MS^2$ spectra are predicted for isomers, i.e. compounds having the same formula and similar molecular structures, to differentiate between them. We used the CFM-ID 2.0/3.0 predictor with regard to (a) test compounds, whose experimental mass spectra had been randomly sampled from the MassBank of North America (MoNA) collection, and to (b) the most widespread isomers of test compounds searched in the PubChem database. In the first validation test, in silico mass spectra constitute a reference library, and library searches are performed for test experimental spectra of "unknowns". The searches led to the true positive rate (TPR) of ($46-48{\pm}10$)%. In the second test, in silico and experimental spectra were interchanged and this resulted in a TPR of ($58{\pm}10$)%. There were no significant differences between results obtained with different metrics of spectral similarity and predictor versions. In a comparison of test compounds vs. their isomers, a statistically significant correlation between mass spectral data and structural features was observed. The TPR values obtained should be regarded as reasonable results for predicting tandem mass spectra of related chemical structures.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.42-45
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• 2001

The characteristics of smart skin for wireless LAN system under compression load are investigated. The smart skin structure is composed of 3 layers of face material and 2 layers of core material. Theoretical formula for determining buckling load is derived by Rayleigh-Ritz method and compared with experimental result. The maximum length of specimen that buckling does not occur is determined by only face material. In the experiment, if load supporting capability and the antenna property such as radiation pattern and reflection coefficient were examined.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1161-1166
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• 2001

Fatigue behavior of reinforced concrete(RC) elements has been experimentally and analytical investigated. Fatigue behavior influenced by longitudinal reinforcement ratio, strength of concrete and load ratio $P_{u}$/ $P_{o}$. The purpose of these studies is to propose an empirical formula for fatigue behavior on basis of experimental results. Also an analytical method to predict the crack propagation of RC beams has been developed based on the relationships between bond stress and slip.

• 한국항해학회지
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• 제21권2호
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• pp.69-75
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• 1997

A modern electric system located at a certain distance from the discharge may respond with unexpected sensitivity, when an electrostatic discharge (ESD) phenomenon occurs heteronomously between metallic objects. For analyzing the transient electromagnetic fields caused by ESD, two resistance formulas - Toepler and Rompe-Weizel -are introduced. The experimental result given by Wilson-Ma are used to compare which of these resistance formulas is proper.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.569-572
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• 1999

In this paper we present a color image segmentation algorithm based on statistical models. A novel deterministic annealing Expectation Maximization(EM) formula is derived to estimate the parameters of the Gaussian Mixture Model(GMM) which represents the multi-colored objects statistically. The experimental results show that the proposed deterministic annealing EM is a global optimal solution for the ML parameter estimation and the image field is segmented efficiently by using the parameter estimates.

• 전자공학회논문지D
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• 제34D권12호
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• pp.1-7
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• 1997

Serious troubles may occur in electromagnetic equipments due to electrostatic discharge (ESD). The number of the damaging incidents are significantly increasing with the increased use of integrated semiconductor elements with loer operation pwoer. In order to examine the phenomena theoretically, this paper anlyzes properties of the transient electromagnetic fields rdiated by ESD. A new model is presented using the Rompe-weizel formula for the spark resistance. The numerical results of ESD fields are compared with the experimental data that were given by wilson-Ma.