• Steel and Composite Structures
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• v.49 no.6
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• pp.645-666
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• 2023

Due to the steadily declining supply of natural coarse aggregates, the concrete industry has shifted to substituting coarse aggregates generated from byproducts and industrial waste. Oil palm shell is a substantial waste product created during the production of palm oil (OPS). When considering the usage of OPSC, building engineers must consider its uniaxial compressive strength (UCS). Obtaining UCS is expensive and time-consuming, machine learning may help. This research established five innovative hybrid AI algorithms to predict UCS. Aquila optimizer (AO) is used with methods to discover optimum model parameters. Considered models are artificial neural network (AO - ANN), adaptive neuro-fuzzy inference system (AO - ANFIS), support vector regression (AO - SVR), random forest (AO - RF), and extreme gradient boosting (AO - XGB). To achieve this goal, a dataset of OPS-produced concrete specimens was compiled. The outputs depict that all five developed models have justifiable accuracy in UCS estimation process, showing the remarkable correlation between measured and estimated UCS and models' usefulness. All in all, findings depict that the proposed AO - XGB model performed more suitable than others in predicting UCS of OPSC (with R², RMSE, MAE, VAF and A_15-index at 0.9678, 1.4595, 1.1527, 97.6469, and 0.9077). The proposed model could be utilized in construction engineering to ensure enough mechanical workability of lightweight concrete and permit its safe usage for construction aims.

• Educational Technology International
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• v.10 no.2
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• pp.145-166
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• 2009

The purpose of this study was to investigate why advance organizers (AO) are effective in promoting comprehension and mental model formation in terms of cognitive load. Two experimental groups: a concept-map AO group and a key-word AO group and one control group were used. This study considered cognitive load in view of Baddeley's working memory model: central executive (CE), phonological loop (PL), and visuo-spatial sketch pad (VSSP). The present experiment directly examined cognitive load using dual task methodology. The results were as follows: central executive (CE) suppression task achievement for the concept map AO group was higher than the key word AO group and control group. Comprehension and mental model construction for the concept map AO group were higher than the other groups. These results indicated that the superiority of concept map AO owing to CE load decrement occurred with comprehension and mental model construction in learning. Thus, the available resources produced by CE load reduction may have been invested for comprehension and mental model construction of learning contents.

• Journal of Astronomy and Space Sciences
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• v.9 no.1
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• pp.41-51
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• 1992

Photoelectric observations of close binary stars, AO Cam and AW Cam, were made during the 1984 observing season with the 61cm reflector at the Sobaeksan Observatory. One time of primary minimum for AO Cam and three primary epochs for AW Cam were derived from the observations of these two systems. Times of minimum light of these two binaries collected from literature were analyzed with a least square fitting method. New improved light elements for AO Cam and AW Cam were determined. The orbital period of AO Cam had been constant from Octobar, 1980 (JD 244520) to February, 1985 (JD 2446107). However, one secondary time of minimum (JD 2447864.7879) of AO Cam published recently by Mullis and Faulkner(1991) shows large deviation of about 4.6 minutes ($0^d.0032$) from the one predicted by our new light elements. Future observations of times of minima for this system are needed to test this period change. The orbital period of AW Cam has been constant as P=$0^d.77134645$ for about sixty years from the early 1930's to the present.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.3
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• pp.96-101
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• 2013

Increased waist circumference has shown to be more strongly associated with cardiovascular disease risk factors. The purpose of this study is to investigate the association between exercise capacity and cardiovascular risk factors among obese types in adult men. The subjects of this study were a total fifty-four obese persons and obesity criteria is body mass index $(BMI){\geq}25kg/m^2$. Diagnostic criteria for obesity was defined as a waist circumference of ${\geq}90cm$. The BMI in the obese subjects, as judged by the presence or absence of abdominal obesity, were classified into two groups (non-AO: without abdominal obesity group, AO: with abdominal obesity group). AO presented lower total exercise time, metabolic equivalents (METs) than Non-AO. AO showed slow HRR (heart rate recovery) response. HRR was negative correlated with BMI, body fat mass, waist circumference. AO had a high heart rate and a low cardiac output in submaximal exercise stage 1~2. In conclusion, AO's (with abdominal obesity groups) total exercise time, METs and HRR are lower than Non-AO. HRR is related with BMI, body fat mass and waist circumference.

• Journal of Chest Surgery
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• v.21 no.5
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• pp.828-841
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• 1988

To predict the postoperative hemodynamic status of right ventricle preoperatively, a retrospective analysis was undertaken to determine the influence of pulmonary artery size on postoperative right ventricular pressure in 32 consecutive patients with tetralogy of Fallot who underwent total correction between July, 1987 to June, 1988 at the Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital. We have related the ratio of the postrepair peak systolic pressure in the right ventricle and the systemic systolic arterial pressure[PRV/Ao] to the preoperative cineangiographic measurement of pulmonary arterial tree, expressed as pulmonary artery index[PAI], the ratio of diameter of the right pulmonary artery to diameter of ascending aorta[r.PA/A.Ao], the ratio of right and left pulmonary artery to diameter of descending aorta[r.I.PA/D.Ao] There was tendency that the postrepair PRV/Ao seems to be related to the preoperative diameter of right and left pulmonary artery, but there were no statistically significant correlation with PAI, r.PA/A.Ao, r.l.PA/D. Ao to the ratio of the postoperative peak systolic right ventricular pressure and systemic systolic arterial pressure[PRV/Ao]. There was tendency to decrease the postoperative right ventricular pressure[PRV/Ao] about 11.2%[P < 0.025] within several hours than immediately after repair, but after then, there was no change of right ventricular pressure[PRV/Ao] significantly. There was good correlation of pressure change between the immediate and late postrepair right ventricular pressure[48 hour], and the derived linear regression line was; y=0.68534 0.1994[r=0.57294, P < 0.001]. There was no operative death due to residual high right ventricular pressure[PRV/Ao >0.75] related to hypoplastic pulmonary arterial development, thus we expect, for symptomatic patients even infants, that complete repair can be attempted when the pulmonary artery index[PAI] is over 108mm2/BSA, RPA/AAo is over 0.35, RPA LPA/D. Ao is over 1.36.

• Journal of the Korean Society of Systems Engineering
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• v.7 no.1
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• pp.1-7
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• 2011

This work describes a study on the Analysis of Alternatives (AoA) based defense decision making. Future battle-space is transformed into a System of Systems (SoS) concept which is accomplished missions and their functions through network based battle management systems under forming their grids of various sensors and shooters in a single theater. The acquisition process is, therefore, changing over from single system requirements to capabilities based acquisition of SoS. AoA help to justify the need for starting, stopping, or continuing an acquisition program. AoA identify potentially viable solutions and provide comparative cost, effectiveness, and risk assessments of each solution to a baseline. The decision making must consider not only cost-effectiveness, risk, and military worth, but also domestic policy, foreign policy, technological maturity of the solution, the environment, the budget, treaties, and a host of additional factors. In this point of view, this paper analyzes AoA template which are critical elements of the defense decision making. From results of this analysis of AoA template for Korean acquisition environment are presented.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.444-450
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• 2006

This study was carried out to compare the performance of two types of sequencing batch biofilm reactors (SBBRs), anoxic-oxic-anoxic-oxic $(AO)_2$ SBBR and anoxic-oxic-anoxic $A_2O$ SBBR, on the biological nutrient removal. The TOC removal efficiency in $A_2O$ SBBR was higher than that in $(AO)_2$ SBBR. At the 1st non-aeration period, the release of ${PO_4}^{3-}-P$ in $A_2O$ SBBR was higher than that in $(AO)_2$ SBBR because of the high TOC removal. At the 1st aeration-period, the nitrification was not completed in $(AO)_2$ SBBR, however, it was completed in $A_2O$ SBBR and the nitrification rate in $A_2O$ SBBR was higher than that in $(AO)_2$ SBBR. The release and uptake of ${PO_4}^{3-}-P$ in $A_2O$ SBBR was much higher than in $(AO)_2$ SBBR. Also, the profiles of DO and pH in reactors were used to monitor the biological nutrient removal in two SBBRs. The break point in DO and pH curves at the aeration period coincided with the end of nitrification.

• The Journal of Korean Medicine
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• v.30 no.5
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• pp.16-25
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• 2009

Objectives: This study was designed to analyze the results of body composition test by Oriental medical examination. The subjects were workers in the automobile manufacturing industry. Methods: The subjects consisted of 24,077 industrial workers who had received Oriental medical examination and completed questionnaires about drinking history and smoking history, during 9 months from March to November. They were categorized by sex, age, job class, drinking history and smoking history. The percentage of body fat(%BF) and abdominal obesity(AO) were measured by using bioelectrical impedance analysis (Jawon Medical, Seoul, Korea). We analyzed the relationship between sex, age, job class, drinking history, smoking history and %BF and AO using x$^2$-test of the SPSS Ver. 14.0. Results: Regarding the relationship between sex and %BF, AO, there was statistically significant difference as men had a significant higher level of %BF and AO than women. There was a positive correlation between age and both %BF and AO. Workers in their 40s especially showed a high level of AO. In job class, office workers and sales personnel were apt to have a higher level of %BF and AO than factory workers. %BF and AO of the drinker group showed a higher level than the non-drinker group. On the other hand, %BF and AO of the non-smoker group were higher than those of the smoker group. Conclusions: Companies should manage obesity closely and educate the workers to quit smoking for their health promotion. Furthermore, continuous health checkups need to be done systematically.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.861-867
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• 2000

The feasibility of simultaneous phosphorus and nitrogen removal by enhancing anoxic phosphorus uptake was investigated in a sequencing batch reactor (SBR). By introducing an anoxic phase into an anaerobic-aerobic SBR (AO SBR), significant amounts of denitrifying phosphorus accumulating organisms (DPAOs) which can utilize nitrate as electron acceptor could be accumulated in the reactor (anaerobic-aerobic- anoxic-aerobic SBR, $(AO)_2$ SBR). A direct comparison of phosphorus uptake rate under anaerobic and aerobic conditions showed that the fraction of DPAOs in P-removing sludge were increased from 10% in the AO SBR to 64% in $(AO)_2$ SBR. The $(AO)_2$ SBR showed stable phosphorus and nitrogen removal efficiency: average removal efficiencies of TOC, total nitrogen, and phosphorus were 92%, 88%, and 100%. respectively. Results of the $(AO)_2$ SBR operation and batch tests showed that nitrite (up to 10 mg-N/L) was not detrimental to anoxic phosphorus uptake and could serve as good electron acceptor like nitrate.

• Parasites, Hosts and Diseases
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• v.60 no.5
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• pp.345-352
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• 2022

Chitinase AO-801 is a hydrolase secreted by Arthrobotrys oligospora during nematode feeding, while its role remained elusive. This study analyzed the molecular characteristics of recombinant chitinase of Arthrobotrys oligospora (reAO-801). AO-801 belongs to the typical glycoside hydrolase 18 family with conserved chitinase sequence and tertiary structure of (α/β)₈ triose-phosphate isomerase (TIM) barrel. The molecular weight of reAO-801 was 42 kDa. reAO-801 effectively degraded colloidal and powdered chitin, egg lysate, and stage I larval lysate of Caenorhabditis elegans. The activity of reAO-801 reached its peak at 40℃ and pH values between 4-7. Enzyme activity was inhibited by Zn2⁺, Ca2⁺, and Fe3⁺, whereas Mg2⁺ and K⁺ potentiated its activity. In addition, urea, sodium dodecyl sulfate, and 2-mercaptoethanol significantly inhibited enzyme activity. reAO-801 showed complete nematicidal activity against C. elegans stage I larvae. reAO-801 broke down the C. elegans egg shells, causing them to die or die prematurely by hatching the eggs. It also invoked degradation of Haemonchus contortus eggs, resulting in apparent changes in the morphological structure. This study demonstrated the cytotoxic effect of reAO-801, which laid the foundation for further dissecting the mechanism of nematode infestation by A. oligospora.