• 대한기계학회논문집A
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• 제29권10호
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• pp.1298-1306
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• 2005

In this paper, Part II, we realized the Serpentine Laminating Micromirer (SLM) which was proposed in the accompanying paper, Part I, by means of the injection molding process in mass production. In the SLM, the higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms of splitting/recombination and chaotic advection by the successive arrangement of 'F'-shape mixing units in two layers. Mold inserts for the injection molding process of the SLM were fabricated by SU-8 photolithography and nickel electroplating. The SLM was realized by injection molding of COC (cyclic olefin copolymer) with the fabricated mold inserts and thermal bonding of two injection molded COC substrates. To compare the mixing performance, a T-type micromixer was also fabricated. Mixing performances of micromixers were experimentally characterized in terms of an average mixing color intensity of a pH indicator, phenolphthalein. Experimental results show that the SLM has much better mixing performance than the I-type micromixer and chaotic mixing was successfully achieved from the SLM over the wide range of Reynolds number (Re). The chaotic micromixer, SLM proposed in this study, could be easily integrated in Micro-Total-Analysis- System , Lab-on-a-Chip and so on.

• 한국화재소방학회논문지
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• 제25권6호
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• pp.51-57
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• 2011

본 연구는 국내 목조문화재의 화재에 대한 수계 자동소화시스템 중에 범용의 스프링클러 소화시스템에 대한 소화성능을 소화실험을 통하여 확인해 보았다. 목조문화재는 가연성의 재질로 구성되어 있어 화재에 취약하며, 방화의 경우 화재의 성상 초기부터 화원의 규모가 커질 수 있다. 본 실험에 적용된 스프링클러 헤드는 방사압 1 bar, 방수량 80 lpm의 사양을 지니고 있다. 소화실험의 유형은 화원의 규모별, 문화재 규모별로 각각 둘로 구분하여 소화성능을 실험하였다. 소화실험을 통해 확인된 사항은 천장이 높으면 소화 시간이 지연되는 결과가 발생하며, 화원의 규모가 2단위에서는 소화는 가능하였지만 소화가 지연되는 것으로 나타났다. 그 결과 천장이 높고, 화원의 규모가 2단위 이상이 되면 소화성능이 낮을 것으로 예측된다. 실제 목조문화재의 화재 성장 환경이 소화실험 모형보다 유리하다는 측면을 고려해야 한다. 그러므로 스프링클러 소화설비를 목조문화재에 적용 할 때에 헤드간 거리 헤드의 선정 등 충분한 검증이 요구된다.

• Clinical and Experimental Pediatrics
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• 제55권8호
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• pp.272-279
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• 2012

Purpose: The aim of this study was to develop an appropriate nursing information guideline according to corrected age, after investigating parents' concerns about the growth, development, and diseases of their premature infants after discharge from the neonatal intensive care unit (NICU). Methods: The parents of premature infants (birth weight, <2,500 g; gestational age, <37 weeks) who went to a neonatal follow-up clinic after NICU discharge at Seoul St. Mary's Hospital from January 2005 to December 2009, were asked with regard to their concerns about their infants through a questionnaire survey. The results of physical examinations, including body measurements and neurodevelopmental status at 4, 8, 12, and 18 months of corrected age, were retrospectively reviewed in 390 infants. Results: The most common parental concerns were developmental delay, poor growth, and feeding and nutritional problems. Parental concerns about developmental delay, growth failure in improvement in body weight and length, and overweightness were high in specificity but very low in sensitivity. After NICU discharge, 30% of premature infants experienced infectious diseases before 18 months of corrected age, the most common of which was respiratory tract infection. Conclusion: For guiding of premature infants in outpatient day clinics after NICU discharge, it is necessary to identify the parents' highest concerns, to educate them about the possibilities of growth and neurodevelopmental disabilities in their infants and to provide them with handouts containing guidelines on the management of infectious diseases, especially respiratory infections.

• Clinical and Experimental Pediatrics
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• 제63권1호
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• pp.20-24
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• 2020

Background: Predicting the prognosis of patients admitted to the pediatric intensive care unit (PICU) is very important in determining further management and resource allocation. The prognostication of critically ill children can be challenging; hence, accurate methods for predicting outcomes are needed. Purpose: To evaluate the role of microalbuminuria at admission as a prognostic marker in comparison to standard Pediatric Risk of Mortality (PRISM) and Pediatric Logistic Organ Dysfunction (PELOD) mortality scores in children admitted to the PICU. Methods: This cross-sectional study was conducted from January 2015 to October 2016. Eighty-four patients aged 1 month to 18 years admitted to the PICU of teaching hospitals for more than 24 hours were enrolled by convenience sampling method. Microalbuminuria was estimated by spot urinary albumin-creatinine ratio. PRISM and PELOD scores were calculated using an online calculator. Outcome measures were PICU length of stay, inotrope usage, multiorgan dysfunction, and survival. ACR was compared with mortality scores for predicting survival. Results: Microalbuminuria was present in 79.8% with a median value of 85 mg/g (interquartile range, 41.5-254 mg/g). A positive correlation was found between albumin-creatinine ratio and PICU length of stay (P=0.013, r=0.271). Albumin-creatinine ratio was significantly associated with organ dysfunction (P=0.004) and need for inotropes (P=0.006). Eight deaths were observed in the PICU. The area under the curve for mortality for albumin-creatinine ratio (0.822) was comparable to that for PRISM (0.928) and PELOD (0.877). Albumin-creatinine ratio >109 mg/g predicted mortality with a sensitivity of 87.5% and specificity of 63.2%. Conclusion: Microalbuminuria is a good predictor of PICU outcomes comparable with mortality scores.

• Environmental Engineering Research
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• 제22권2호
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• pp.203-209
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• 2017

Innovations in the biofiltration process can provide effective solutions to overcome crucial water pollution problems. The elimination of pollutants is a result of the combined effects of biological oxidation, adsorption and filtration processes. This research aims to evaluate the performance of quartz sand biofiltration for removing total suspended solids, turbidity, color, organic matter, and ammonium from polluted river water and develop an empirical model for designing quartz sand biofilters for the treatment of polluted river water. Experiments were conducted using two biofilter units filled with quartz sand as filter media. A set of experiments were performed to evaluate the effect of hydraulic retention time on biofilter performance in removing water contaminants. The kinetics of organic matter removal were also determined to describe the performance of the biofilter. The results show that biofiltration can significantly remove river water pollutants. Removal efficiency depends on the applied hydraulic retention time. At a hydraulic retention time of two hours, removal efficiencies of total organics, ammonium and total suspended solids were up to 78%, 82%, and 91%, respectively. A model for designing quartz sand biofiltration has been developed from the experimental data.

• Restorative Dentistry and Endodontics
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• 제38권2호
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• pp.65-72
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• 2013

Objectives: To evaluate the inhibitory effect of ursolic acid (UA)-containing composites on Streptococcus mutans (S. mutans) biofilm. Materials and Methods: Composite resins with five different concentrations (0.04, 0.1, 0.2, 0.5, and 1.0 wt%) of UA (U6753, Sigma Aldrich) were prepared, and their flexural strengths were measured according to ISO 4049. To evaluate the effect of carbohydrate source on biofilm formation, either glucose or sucrose was used as a nutrient source, and to investigate the effect of saliva treatment, the specimen were treated with either unstimulated whole saliva or phosphate-buffered saline (PBS). For biofilm assay, composite disks were transferred to S. mutans suspension and incubated for 24 hr. Afterwards, the specimens were rinsed with PBS and sonicated. The colony forming units (CFU) of the disrupted biofilm cultures were enumerated. For growth inhibition test, the composites were placed on a polystyrene well cluster, and S. mutans suspension was inoculated. The optical density at 600 nm ($OD_{600}$) was recorded by Infinite F200 pro apparatus (TECAN). One-way ANOVA and two-way ANOVA followed by Bonferroni correction were used for the data analyses. Results: The flexural strength values did not show significant difference at any concentration (p > 0.01). In biofilm assay, the CFU score decreased as the concentration of UA increased. The influence of saliva pretreatment was conflicting. The sucrose groups exhibited higher CFU score than glucose group (p < 0.05). In bacterial growth inhibition test, all experimental groups containing UA resulted in complete inhibition. Conclusions: Within the limitations of the experiments, UA included in the composite showed inhibitory effect on S. mutans biofilm formation and growth.

• 접착 및 계면
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• 제20권4호
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• pp.155-161
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• 2019

공액분자 나노구조체 계면에서의 전하이동 이방성을 이해하는 것은 유기전계효과트랜지스터(OFET)에서 구조-물성 상관관계를 규명하는데 중요하다. 본 연구에서는 대표적인 코페이셜 적층구조를 가진 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) 유기반도체 단결정과 산화물 계면에서 전하이동도 이방성을 연구하였다. 용매치환공정을 이용해 유기단결정을 산화실리콘 절연체 표면에 성장시키고 유기단결정/산화물 계면에서 전하이동을 유도할 수 있도록 OFET 소자를 완성하였다. TIPS-pentacene OFET에서 최고/최저 전하이동도 이방성은 5.2로 관찰되었다. TIPS-pentacene의 전하이동을 담당하는 공액부의 최인접부와의 상호작용을 분석한 결과, HOMO 준위 커플링과 전하의 호핑 궤도가 전하이동도 이방성에 기여하는 것으로 밝혀졌다. HOMO 준위 커플링에 기반한 전하이동도 이방성의 정량적 예측은 실험결과와 유사하게 나타났다.

• 한국지리정보학회지
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• 제20권4호
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• pp.15-23
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• 2017

국토부에서 추진하는 지적도면의 세계측지계변환사업이 면적 위치 등의 미세한 차이로 지적공부에 반영하지 못하고 있다. 경계점좌표등록지역을 세계측지계로 좌표변환 시 경계점좌표를 법정좌표단위로 변경해야 한다. 그런데 좌표단위의 변경 시 나타나는 미세한 면적변화가 기존 지적공부에 등록된 면적과 일치하지 않은 현상이 발생한다. 본 연구에서는 이러한 문제점을 해결하고자 지적재조사에서 사용하는 수동적 경계미세조정방식을 응용하여 다수의 필지들을 일괄적으로 조정할 수 있는 방식을 개발하였다. 조정구간 범위와 면적조건을 고려해야 하는 필지 수에 따라 전수1, 전수2+1, 구간1, 구간2+1 등의 방식으로 구분하였다. 각 방식의 비교를 위해 SW를 개발하여 실험대상 지역을 분석한 결과 위치 정확성측면에서는 전수2+1, 시간적 효율성은 구간2+1 방식이 적합한 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1704-1710
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• 2010

The structure of a 2D grid-like copper(II) complex [Cu$(NCO)_2$(pyz)](pyz=pyrazine) (1) consists of 1D chains of Cu-pyz units connected by double end-on (EO) cyanato bridges. Each Cu(II) ion has a distorted octahedral coordination, completed by the four EO cyanato and two pyrazine ligands. Magnetic interactions through EO cyanato and pyrazine bridges in 1 are discussed on the basis of DFT broken-symmetry calculations at the B3LYP level. For model dicopper(II) complexes I (bridged by cyanato) and II (bridged by pyrazine), electronic structure calculations reproduce very well the experimental couplings for the S = 1/2 ferromagnetic and antiferromagnetic exchange-coupled 2D system: the calculated exchange parameters J are +1.25 $cm^{-1}$ and -3.07 $cm^{-1}$ for I and II, respectively. The $\sigma$ orbital interactions between the Cu $x^2-y^2$ magnetic orbitals and the nitrogen lone-pair orbitals of pyrazine are analyzed from the viewpoint of through-bond interaction. The energy splitting of 0.106 eV between two SOMOs indicates that the superexchange interaction should be antiferromagnetic in II. On the other hand, there are no bridging orbitals that efficiently connect the two copper(II) magnetic orbitals in I because the HOMOs of the basal-apical NCO bridge do not play a role in the formation of overlap interaction pathway. The energy separation in the pair of SOMOs of I is calculated to be very small (0.054 eV). This result is consistent with the occurrence of weakly ferromagnetic properties in I.

• 한국초등과학교육학회지:초등과학교육
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• 제39권3호
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• pp.449-463
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• 2020

This study was to analysis teaching strategies, types of inquiry activities and the relationship between science concepts and inquiry activities presented in science textbooks. As a result of the study, first, the inquiry-based teaching strategies presented in science textbooks were experiment, simulation, demonstration, and field study. Second, there were 53 inquiry activities presented in 8 units related to the earth science area of science textbooks, and the types of inquiry activities were experimental observation (EO) 18, mock activity (SA) 20, investigation discussion and presentation (IP). It was analyzed as 12, data interpretation (ID) 2, and express (EX) 1 piece. Third, the relationship between inquiry activities and science concepts presented in science textbooks was analyzed. As a result of the analysis, out of a total of 42 inquiry activities, 21 inquiry activities corresponded to EA (explicit activities), in which the result of inquiry activities was directly and explicitly linked to science concepts. And IA (implicit activities), which is an implicit inquiry activity in which science concepts must be inferred using the results of inquiry activities, were analyzed as 21. In particular, IA (implicit activities), which is an implicit inquiry activity, can be said to be the result of reflecting the characteristics of earth science areas where many simulated activities (SA) are used. This is considered to be a matter to be considered in the process of developing various elementary science textbooks in the future.