• Environmental Engineering Research
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• v.11 no.2
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• pp.63-76
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• 2006

Multivariate analysis and batch monitoring on a pilot-scale sequencing batch reactor (SBR) are described for integrated wastewater treatment management system, where a batchwise multiway independent component analysis method (MICA) are used to extract meaningful hidden information from non-Gaussian wastewater treatment data. Three-way batch data of SBR are unfolded batch-wisely, and then a non-Gaussian multivariate monitoring method is used to capture the non-Gaussian characteristics of normal batches in biological wastewater treatment plant. It is successfully applied to an 80L SBR for biological wastewater treatment, which is characterized by a variety of error sources with non-Gaussian characteristics. The batchwise multivariate monitoring results of a pilot-scale SBR for integrated wastewater treatment management system showed more powerful monitoring performance on a WWTP application than the conventional method since it can extract non-Gaussian source signals which are independent and cross-correlation of variables.

• Journal of Computing Science and Engineering
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• v.9 no.2
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• pp.83-97
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• 2015

IEEE 802.15.4 is a global standard designed for emerging applications in low-rate wireless personal area networks (LR-WPANs). The standard provides beneficial features, such as a beacon-enabled mode and guaranteed time slots for realtime data delivery. However, how to optimally operate those features is still an open issue. For the optimal operation of the features, this paper proposes a holistic optimization method that jointly optimizes three cross-related problems: cluster-tree construction, nodes' power configuration, and duty-cycle scheduling. Our holistic optimization method provides a solution for those problems so that all the real-time packets can be delivered within their deadlines in the most energy-efficient way. Our simulation study shows that compared to existing methods, our holistic optimization can guarantee the on-time delivery of all real-time packets while significantly saving energy, consequently, significantly increasing the lifetime of the network. Furthermore, we show that our holistic optimization can be extended to take advantage of the spatial reuse of a radio frequency resource among long distance nodes and, hence, significantly increase the entire network capacity.

• Journal of the Korean housing association
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• v.17 no.5
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• pp.147-157
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• 2006

A study on Composing Unit Spaces of Apartment Houses according to the Differentiation in Lifestyle by survey on preferences. The purpose of this study is to propose composition models of unit spaces for 85m2 net area apartment houses by lifestyle types. This study set up a hypothesis that there is a critical divergence of preferences in composition types of unit spaces according to lifestyle. To prove the hypothesis, investigation on variable floor plans of apartments to extract spatial composition types of units and questionnaire survey on lifestyleand preferences for composition types were implemented. To extract several factors regarding, characteristics of lifestyle, factor analysis, was implemented for each variable. Cluster analysis was conducted to cluster interviewees by similarity of lifestyle. To identify and define how each factor reacts, ANOVA and cross tabulation analysis between factors and clusters were used. The type of spatial composition was analyzed by plane characteristic, spatial relation and spatial usability on the basis of apartment plate type. As a result, lifestyle was divided into three types: reasonable lifestyle, trend-seeking lifestyle and conservative lifestyle. As, the result of investigating characteristics for the type of spatial composition according to the type of lifestyle, preferred types and main districts were different. Therefore, the hypothesis was proved.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.43.4-44
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• 2016

The presence of multiple stellar populations is now well established in most globular clusters (GCs) in the Milky Way. The origin of this phenomenon, however, is yet to be understood. In this respect, the study of NGC 2808, an intriguing GC which hosts subpopulations with extreme helium abundances, would help to resolve this problem. In order to investigate chemical abundance patterns among different subpopulations in this GC, we have performed low-resolution spectroscopy for the red-giant-branch (RGB) stars and measured CN & CH bands, and Ca line strength. We have identified at least three subpopulations from the CN abundance distribution. This GC shows CN-CH anti-correlation following the general trend among "normal" GCs. In addition, we have cross-matched our results with the high-resolution data in literature, and found a tight correlation between CN strength and sodium abundance. However, CN is anticorrelated with oxygen abundance, as expected from the well known N(&Na)-O anticorrelation. In this talk, we will discuss the implication of these results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.912-917
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• 2007

Many electrochemical power devices such as solid state batteries and solid oxide fuel cell have been studied and developed for solving energy and environmental problems. An amperometric gas sensor usually generates sensing signal of electric current along the proportion of the concentration of target gas under the condition of limiting current. For narrow variations of gas concentration, the amperometric gas sensor can show higher precision than a potentiometric gas sensor does. In additional, cross sensitivities to interfering gases can possibly be mitigated by choosing applied voltage and electrode materials properly. In order to improve the sensitivity to $NO_2$, the device was attached with Au reference electrode to form the amperometric gas sensor device with three electrodes. With the fixed bias voltage being applied between the sensing and counter electrodes, the current between the sensing and reference electrodes was measured as a sensing signal. The response to $NO_2$ gas was obviously enhanced and suppressed with a positive bias, respectively, while the reverse current occurred with a negative bias. The way to enhance the sensitivity of $NO_2$ gas sensor was thus realized. It was shown that the response to $NO_2$ gas could be enhanced sensitivity by changing the bias voltage.

• Journal of Korean Critical Care Nursing
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• v.13 no.3
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• pp.11-23
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• 2020

Purpose : This study examined factors influencing the attitudes towards nurse-led defibrillation in the emergency department (ED) and intensive care unit (ICU). Methods : This was a cross-sectional study. A total of 212 nurses in the ED and ICU from three general hospitals responded to the survey. Data were collected between September and October 2015 using structured questionnaires. Independent t-test, Mann-Whitney U test, one-way analysis of variance (ANOVA), Pearson's correlation coefficient, and hierarchical multiple regression were used to analyze factors affecting nurses' attitudes towards nurse-led defibrillation. Results : The mean score of nurses' attitudes towards nurse-led defibrillation was 61.37 of a possible 91. Hierarchical multiple regression showed that nurses' attitudes towards nurse-led defibrillation were significantly affected by their experiences regarding cardiopulmonary resuscitation (p=.003), knowledge regarding electrocardiogram interpretation and defibrillation (p=.007), and tenure in ED or ICU (p=.043). Conclusion : Results indicate that employers should set policies to support nurses in maintaining their careers in the ED or ICU and conduct systematic educational programs for them. This will increase nurses' confidence in performing defibrillation, which will lead to early defibrillation during in-hospital cardiac arrest. Consequently, it can be a strategy to increase the survival rate of cardiac arrest patients.

• Korean journal of food and cookery science
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• v.28 no.6
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• pp.721-729
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• 2012

This paper aimed to investigate the influence of consumer lifestyle on consumer selection of bakery cafe attributes. Data were collected through a self-administered questionnaire by 403 random consumers between the ages 20s and 30s in several bakery cafes in Seoul and Gyonggi area. Different methods of statistical analysis had been used such as frequency analysis, factor analysis, k-means clustering analysis, cross tabulation, one way ANOVA and Duncan's multiple range test with SPSS for Window 13.0 package. First, when analyzing the 16 questions of comsumer lifestyles, four factors were extracted: 'dining out-oriented factor', 'achievement-oriented factor', 'brand-oriented factor', and 'health-oriented factor'. Second, the respondents were divided into three groups by k-means cluster analysis: no interest group, dining-out & value oriented group, and health-brand oriented group. Third, consumer's bakery cafe attributes were categorized into five factors including 'food', 'convenience and image', 'store promotion', 'positive dining experience', and 'menu & merchandises'. Finally when analyzing the differences in the selection of bakery cafe attributes according to consumer's lifestyles, it showed a significant differences.

• Journal of Korean society of Dental Hygiene
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• v.16 no.5
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• pp.701-708
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• 2016

Objectives: The purpose of the study was to examine the level and relationship of incivility through clinical experience and major satisfaction in dental hygiene students. Methods: A self-reported questionnaire was completed by 357 dental hygiene students in six universities from November 1 to December 1, 2015. The questionnaire by five point Likert scale consisted of general characteristics of the subjects (6 items), incivility (20 items), and major satisfaction (6 items). Incivility was divided into three factors of staff, doctors, and patients & visitors. Data were analyzed with descriptive statistics of variables, multiple response cross analysis, independent t-test, one way ANOVA, and Pearson's correlation coefficient analysis. Results: The mean of incivility and major satisfaction was 2.23 and 3.29, respectively. The incivility of staff, doctors, and patients & visitors showed negative correlations with major satisfaction. Conclusions: The incivility through clinical experience is associated with major satisfaction negative. These results suggest that we need to develop remedy such as positive attitude dealing with incivility and implementing similar environment education during clinical training at school and dealing with stress.

• Phonetics and Speech Sciences
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• v.1 no.3
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• pp.117-122
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• 2009

A variety of cross-linguistic studies has documented that the acoustic properties of speech addressed to young children include exaggeration of pitch contours and acoustically salient features of phonetic units. It has been suggested that phonetic modifications of child-directed speech facilitate young children's learning of speech sounds by providing detailed phonetic information about the target word. While there are several studies reporting vowel modifications in speech to infants (i.e., hyper-articulated vowels), there has been little research about consonant modifications in speech to young children (except for VOT). The present study examines acoustic properties of Korean stops in Korean mothers' speech to their children (seven children aged 27 to 38 months). Korean tense, lax, and aspirated stops are all voiceless in word-initial position, and are perceptually differentiated by several acoustic parameters including VOT, $f_0$ of the following vowel, and the amplitude difference of the first and second harmonics at the voice onset of the following vowel. This study compares values of these parameters in Korean child-directed speech to those in adult-directed speech from same speakers. Conclusions focus on the acoustic properties of Korean stops in child-directed speech and how they are modified to help Korean young children learn the three-way phonetic contrast.

• Smart Structures and Systems
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• v.16 no.3
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• pp.555-577
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• 2015

In the work at hand, the development of a morphing flap, actuated through shape memory alloy load bearing elements, is described. Moving from aerodynamic specifications, prescribing the morphed shape enhancing the aerodynamic efficiency of the flap, a suitable actuation architecture was identified, able to affect the curvature. Each rib of the flap was split into three elastic elements, namely "cells", connected each others in serial way and providing the bending stiffness to the structure. The edges of each cell are linked to SMA elements, whose contraction induces rotation onto the cell itself with an increase of the local curvature of the flap airfoil. The cells are made of two metallic plates crossing each others to form a characteristic "X" configuration; a good flexibility and an acceptable stress concentration level was obtained non connecting the plates onto the crossing zone. After identifying the main design parameters of the structure (i.e. plates relative angle, thickness and depth, SMA length, cross section and connections to the cell) an optimization was performed, with the scope of enhancing the achievable rotation of the cell, its ability in absorbing the external aerodynamic loads and, at the same time, containing the stress level and the weight. The conceptual scheme of the architecture was then reinterpreted in view of a practical realization of the prototype. Implementation issues (SMA - cells connection and cells relative rotation to compensate the impressed inflection assuring the SMA pre-load) were considered. Through a detailed FE model the prototype morphing performance were investigated in presence of the most severe load conditions.