• The Korean Journal of Ceramics
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• 제5권2호
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• pp.142-147
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• 1999

The interaction between commercial $Si_3N_4$ powder and two types of additives (nitrate and oxide additives) during the sintering of $Si_3N_4$ was investigated. The nitrates solution or oxide particles were added as a sintering additives. The surface of mixed powder was observed with FT-IR, TG, and HREM. DTA was used to characterize the reactivity of the powders. The formation of crystalline phases and phase transformation were analyzed by XRD. The adsorption of the additives on the surface of silicon nitride was confirmed in the nitrate salts. It was shown that the adsorption occurred by interaction between the amorphous $SiO_2$ layer on the $Si_3N_4$ surface and metal cations $(Al^{3++\; and \;Y^{3+})$ and anions $(NO_3\;^-\; or\; OH^-)$, resulting in a higher degree of homogeneous distribution of additives.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.991-996
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• 2022

Microstructures of monolithic high purity SiC and SiC with sintering additives after neutron irradiation to a fluence of 2.0-2.5 × 10²⁴ n/m² (E > 0.1 MeV) at 333-363 K and after post-irradiation annealing up to 1673 K were observed using a transmission electron microscopy. Results showed that no black spot defects or dislocation loops in SiC grains were found after the neutron irradiation for all of the specimens owing to the moderate fluence at low irradiation temperature. Thus, it is confirmed that these specimens were swelled mostly by the formation of point defects. Black spots and small dislocation loops were discovered only after the annealing process in PureBeta-SiC and CVD-SiC, where the swelling almost diminished. Anomalous-shaped YAG grains were found in SiC ceramics containing sintering additives. These grains contained dense black spots defects and might lose crystallinity after the neutron irradiation, while these defects may annihilate by recrystallization during annealing up to 1673 K. Amorphous grain boundary phase was also presented in this ceramic, and a large part of it was crystallized through post-irradiation annealing and could affect their recovery behavior.

• Industrial Engineering and Management Systems
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• 제6권1호
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• pp.64-71
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• 2007

J. Kennedy and R. Eberhart first introduced the concept called as Particle Swarm Optimization (PSO). They applied it to optimize continuous nonlinear functions and demonstrated the effectiveness of the algorithm. Since then a considerable number of researchers have attempted to apply this concept to a variety of optimization problems and obtained reasonable results. In PSO, individuals communicate and exchange simple information with each other. The information among individuals is communicated in the swarm and the information between individuals and their swarm is also shared. Finally, the swarm approaches the optimal behavior. It is reported that reasonable approximate solutions of various types of test functions are obtained by employing PSO. However, if more precise solutions are required, additional algorithms and/or hybrid algorithms would be necessary. For example, the heading vector of the swarm can be slightly adjusted under some conditions. In this paper, we propose a hybrid algorithm to obtain more precise solutions. In the algorithm, when a better solution in the swarm is found, the neighborhood of a certain distance from the solution is searched. Then, the algorithm returns to the original PSO search. By this hybrid method, we can obtain considerably better solutions in less iterations than by the standard PSO method.

• Archives of Plastic Surgery
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• 제45권3호
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• pp.271-274
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• 2018

The decision of which surgical approach to use for the treatment of a multifocal craniofacial abscess is still a controversial matter. A failure to control disease progress in the craniofacial region can potentially put the patient's life at risk. Therefore, understanding the various ways to approach the craniofacial region helps surgeons to obtain satisfactory results in such cases. In this report, we describe a patient who visited the emergency department with a large swelling in his right cheek. A blood test and computed tomography revealed odontogenic maxillary sinusitis. The patient developed sepsis due to a progressive multifocal abscess. An abscess was seen in the temporal muscle, infratemporal fossa, and interorbital region. To control this multifocal abscess, we used the facial dismasking flap (FDF) approach. After debridement using the FDF approach, we succeeded in obtaining sufficient drainage of the abscess, and the patient recovered from sepsis. The advantages of the FDF approach are that it provides a wide surgical field, extending from the parietal region to the mid-facial region, and that it leaves no aesthetically displeasing scars on the face. The FDF approach may be one of the best options to approach multifocal abscesses in the craniofacial region.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.380-383
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• 2003

In this paper, we propose a fuzzy group decision making method for multiple decision maker-multiple objective programming problems to obtain the agreeable solution. In the proposed method, considering the vague nature of human subjective judgement it is assumed that each of multiple decision makers has a fuzzy goal for each of his/her own objective functions. After eliciting the membership functions from the decision makers for their fuzzy goals, total M-Pareto optimal solution concept is defined in membership spaces in order to deal with multiple decision maker-multiple objective programming problems. For generating a candidate of the agreeable solution which is total M-Pareto optimal, the extended weighted minimax problem is formulated and solved for some weighting vector which is specified by the decision makers in their subjective manner, Given the total M-Pareto optimal solution, each of the derision makers must either be satisfied with the current values of the membership functions, or update his/her weighting vector, However, in general, it seems to be very difficult to find the agreeable solution with which all of the decision makers are satisfied perfectly because of the conflicts between their membership functions. In the proposed method, each of the decision makers is requested to estimate the degree of satisfaction for the candidate of the agreeable solution. Using the estimated values or satisfaction of each of the decision makers, the core concept is desnfied, which is a set of undominated candidates. The interactive algorithm is developed to obtain the agreeable solution which satisfies core conditions.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.78-84
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• 2004

To optimize movement of a multi-joint robot arm is known to be a difficult problem, because it is a kind of redundant system. Although the end-effector is set its position by each angle of the joints, the angle of each joint cannot be uniquely determined by the position of the end-effector. There exist the infinite number of different sets of joint angles which represent the same position of the end-effector. This paper describes how to manage the angle of each joint to move its end-effector preferably on an X-Y plane with obstacles in the end-effector’s reachable area, and how to optimize the movement of a multi-joint robot arm, evading obstacles. The definition of “preferable” movement depends upon a purpose of robot operation. First, we divide viewpoints of preference into two, 1) the standpoint of the end-effector, and 2) the standpoint of joints. Then, we define multiple objective functions, and formulate it into a multi-objective programming problem. Finally, we solve it using multi-purpose genetic algorithm, and obtain reasonable results. The method described here is possible to add appropriate objective function if necessary for the purpose.

• 천문학논총
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• 제32권1호
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• pp.185-187
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• 2017

Combining the AKARI Point Source Catalog and the 37-month Monitor of All-sky X-ray Image (MAXI) catalog, the infrared and X-ray properties of nearby active galactic nuclei were investigated. The 37-month MAXI catalog tabulates 100 nearby Seyfert galaxies, 73 of which are categorized into Seyfert I galaxies. Among these Seyfert galaxies, 69 ones were found to have an AKARI infrared counterpart. For the Seyfert I galaxies in this sample, a well-known correlation was found between the infrared and X-ray luminosities. However, the observed X-ray luminosity of the Seyfert II galaxies tends to be lower for the infrared luminosity than the Seyfert I galaxies. This suggests that the X-ray absorption is significant in the Seyfert II galaxies. The Seyfert II galaxies seem to have a bimodal distribution of the IR color between $18{\mu}m$ and $90{\mu}m$. Especially, a large fraction of the Seyfert II galaxies exhibits a redder IR color than the Seyfert I galaxies. A possible origin of the redder IR color is briefly discussed, in relation to the star formation activity in the host galaxy, and to the X-ray absorption.

• Asian-Australasian Journal of Animal Sciences
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• 제3권1호
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• pp.7-13
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• 1990

Nutritional status of cattle in Java in Indonesia was investigated by evaluating P, Ca, Mg, K and Na concentrations in forage and plasma inorganic phosphorus (Pi), Ca and Mg, hematocrit and hemoglobin concentrations of cattle during both rainy and dry seasons in 1988. Investigations were conducted at Jonggol (West Java), Malang (East Java) and Majokerto (East Java). Low P content in forage averaging 0.11% on a dry matter basis, high Ca:P ratio in forage in the rainy season (7.7:1) and low plasma Pi concentrations averaging 4.71 mg/dl were observed in Jonggol. In all three places, Ca content in forages was higher than the requirement according to the NRC standard and plasma Ca concentrations were above the critical level. During the rainy season forty percent of cattle in Malang and Mahokerto showed plasma Mg concentrations below 2mg/dl in spite of normal Mg and K content in forage. Forage samples from each place showed a wide variety in Na content, and Na content of two thirds of forage samples was lower than the requirement according to the NRC standard. Hematocrit and hemoglobin concentrations in Malang and Majokerto showed higher values than the normal range.

• Asian-Australasian Journal of Animal Sciences
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• 제7권4호
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• pp.467-470
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• 1994

Effects of animo acids infusion into the abomasum on plasma growth hormone (GH) concentration were investigated using three wethers of 54 kg of average body weight. Wethers were infused with either 3.25 mmol/kg BW/day of sodium chloride solution (control), 3 mmol/kg BW/day of alanine (Ala), or 3 mmol/kg BW/day of aspartic acid (Asp) continuously for five days through an abomasum cathether in a $3{\times}3$ Latin square desing. On the day of starting infusion (day 0) and day 4 blood samples were collected from a jugular vein every fifteen minutes for six hours after feeding, and their GH concentrations were measured. Blood samples were also collected immediately before starting infusion (day 0), and before feeding of day 1, day 2 and day 4, and their plasma free amino acid concentrations were measured. In the animals infused with Ala, plasma free Ala concentration was increased by Ala infusion and it continued for four days. Plasma GH concentration of these animals increased on day 0, but this phenomenon disappeared on day 4. In the animals infused with Asp, the increase in plasma Asp concentration was observed only on day 1. Plasma GH concentration of these animals was not affected by Asp infusion. These results suggest that continuous Ala infusion stimulates GH secretion for a short period, but the effect would not last long, and that continuous Asp infusion does not affect plasma GH concentration.

• Asian-Australasian Journal of Animal Sciences
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• 제3권2호
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• pp.125-133
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• 1990

The effect of dietary protein-energy restriction (PER) on the growth of long bone were examined in sheep during growing period and then following a cycle of reproduction. Three months-old female sheep were offered protein-energy restricted feed for 6 months (growing period), thereafter changed to normal nutritional conditions for 8 months (reproduction period). A half of animals in each group took pregnancy, parturition and lactation. The nutritional restriction reduced the growth in bone diameter more than that in bone length. Compensatory growth resulting from the removal of the nutritional restraint strongly occurred in bone diameter, especially the bone cortical width, as compared to bone longitudinal growth. A cycle of reproduction severely decreased the growth in the bone cortical width relative to that in the bone width, and little effect was found on the growth in bone length and bone mass. The depression of bone development by pregnancy and lactation tended to exhibit severer in animals having received normal nutrition than in those having received PER. Bone mineral density was not affected by the nutritional restriction. A cycle of reproduction had an adverse effect on the mineral density between in animals having received normal nutrition and in those having received PER.