• Earthquakes and Structures
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• v.25 no.6
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• pp.399-415
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• 2023

In this study, we investigate the use of a negative stiffness tuned inerter damper system to improve the performance of a base-isolated structure. The negative stiffness tuned inerter damper system consists of a tuned inerter damper connected in parallel with a negative stiffness element. To find the optimal parameters for the base-isolated structure with negative stiffness tuned inerter damper system, we develop an optimization method based on performance criteria. The objective of the optimization is to minimize the superstructure acceleration response ratio, while ensuring that the base displacement response ratio remains below a specified target value. We evaluate the proposed method by conducting numerical analyses on an eight-story building. The structure is modeled using both a simplified 3-degree-of-freedom system and a more detailed story-by-story shear-beam model. Lastly, a comparative analysis using time history analysis is performed to compare the performance of the base-isolated structure with negative stiffness tuned inerter damper system with that of the base-isolated structure and base-isolated structure with tuned inerter damper systems. The results obtained from the comparative analysis show that the negative stiffness tuned inerter damper system outperforms the tuned inerter damper system in reducing the dynamic seismic response of the base-isolated structure. Overall, this study demonstrates that the negative stiffness tuned inerter damper system can effectively enhance the performance of base-isolated structures, providing improved seismic response reduction compared to other systems.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.919-925
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• 2023

Modern drones are equipped with miniaturized mission equipment capable of performing various tasks such as surveillance and reconnaissance. Consequently, these mission equipment are exposed to disturbances like wind loads and motor rotations, which can lead to instability in the operation of the Electro-Optical Targeting System (EOTS). Specifically, simple step inputs for changing the line of sight in EOTS can cause abrupt changes in speed, inducing overshoot and potentially creating instability along with other disturbances. To address this, a velocity profile was designed so that the angular velocity moves in a trapezoidal shape when changing the EOTS line of sight. A Double-loop controller was designed to apply this profile as an input to the external loop receiving position feedback. The system's stability was then compared, and the velocity profile was optimized within a stable range by varying maximum speed and acceleration.

• Convergence Security Journal
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• v.23 no.5
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• pp.81-89
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• 2023

Kubernetes is a representative open-source software for container orchestration, playing a crucial role in monitoring and managing resources allocated to containers. As container environments become prevalent, security threats targeting containers continue to rise, with resource exhaustion attacks being a prominent example. These attacks involve distributing malicious crypto-mining software in containerized form to hijack computing resources, thereby affecting the operation of the host and other containers that share resources. Previous research has focused on detecting resource depletion attacks, so technology to respond when attacks occur is lacking. This paper proposes a reinforcement learning-based dynamic resource management framework for detecting and responding to resource exhaustion attacks and malicious containers running in Kubernetes environments. To achieve this, we define the environment's state, actions, and rewards from the perspective of responding to resource exhaustion attacks using reinforcement learning. It is expected that the proposed methodology will contribute to establishing a robust defense against resource exhaustion attacks in container environments

• Journal of Korean society of Dental Hygiene
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• v.11 no.1
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• pp.127-136
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• 2011

Objectives : The writer aimed to examine the dynamic aspect on damage and to be conducive to the swift cure according to right treatment to educate prevention of injury through surveying on the number of the damaged teeth given injury, tooth kind, type in damage, place and cause for being damaged, frequency by month and by time level, and location of the damaged tooth. Methods : Targeting 343 teeth of receiving injury in 201 patients who visited the department of pediatric dentistry, the department of preservation, and the oral and maxillofacial surgery in a dental hospital in Cheonan city from April 2007 to April 2009, by having the dental injury as the main reason, the following conclusions were obtained. Results : 1. Deciduous teeth were indicated to be the highest in imperfect luxation with 60.7%, and were indicated to be in order of crown fracture with 25.5%, root fracture with 12.4%, and perfect luxation with 1.4%. The permanent teeth were indicated to be the highest in crown with 58.1%, and were indicated to be in order of imperfect luxation with 27.3%, root fracture with 13.1%, and perfect luxation with 1.5%(p<0.001). 2. In case of deciduous teeth for a place with damage, the home was indicated to be the highest with 31.7%. The permanent teeth were indicated to be the highest(p<0.001) in the road and stairs with 40.4%. As to a cause for damage, both deciduous and permanent teeth were indicated to be the highest(p<0.001) in a cause for falling with 53.1% and 30.8%, respectively. 3. As for a treatment method, in case of deciduous teeth, the close observation was indicated to be the highest with 46.9%. In permanent teeth, the resin restoration was indicated to be the highest(p<0.001) with 22.2%. Dental injuries in deciduous teeth and permanent teeth are showing diverse aspects. Conclusions : It is important to arrange guidelines on cure of the damaged teeth by injury through continuing a dynamic research on these aspects. Also, the damage in deciduous teeth may have direct and indirect influence upon growth in successional permanent teeth. Thus, through careful treatment, the injury needs to be minimized. It is considered to be likely necessary for a right coping method when injury occurs, and above all, for enough prior education so that injury cannot occur.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.49-58
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• 2009

This study aims to analyze the association between the center of mass(C.O.G) and ocular movement(E.O.G) according to the success and failure in the left turn motion on the balance beam, targeting three female gymnasts. When successful, the left-right C.O.G was moved to the left, which was a rotational direction until such time as the body rotated $180^{\circ}$, whereas there appeared to be a greater movement during failure; thus, it was shown to affect the maintenance of dynamic postural control. In case of the subsequent left-right turning motion of E.O.G, this matches the previous theory that the eyeball moves against the direction of rotation of the body. However, there was a difference at the time of movement, and a clear difference emerged in the success and failure in this study. Also, in the E.O.G in the up-down direction, a movement during failure showed a pattern of down direction in most cases; thus, it is deemed to affect the failure. Therefore, the kinetic postural control and E.O.G are supposed to affect the success and failure in a landing, which is the most importantly evaluated movement on the balance beam, in mutual association.

• Polymer(Korea)
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• v.30 no.6
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• pp.512-518
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• 2006

A biodegradable polymer poly((R) -3-hydroxybutyric acid) (PHB) was conjugated with a hydrophilic polymer poly(ethylene glycol) (PEG) by the ttansesterification reaction to form the amphiphilic block copolymer. PHB with low molecular weight ($3000{\sim}30000$) was appropriated for the drug delivery materials. High molecular weight PHB was hydrolyzed by an acid-catalyst to produce the low molecular weight one. Amphiphilic block copolymer was formed the self-assembled polymeric micelle system in the aqueous solution that the hydrophillic PEG was wraped the hydrophobic PHB. Generally, polymeric micelle forms the small particle between $10{\sim}200nm$. These polymeric micelle systems have been widely used for the drug delivery systems because they were biodegradable, biocompatible, non-toxic and patient compliant. The hydroxyl group of PEG was substituted with carboxyl group which has the reactivity to the ester group of PHB. Amphiphilic block copolymer was conjugated between PHB, and modified PEG at $176^{\circ}C$ which was higher than the melting point of PHB. Transesterification reaction was verified with DSC, FTIR, $^1H-NMR$. In the aqueous solution, critical micelle concentration (CMC) of the mPEG-co-PHB copolymer measured by the fluororescence scanning spectrometer was $5{\times}10^{-5}g/L$. The shape and size of the nanoparticle was taken by dynamic light scattering and atomic force microscopy. The size of the nanoparticle was about 130 nm and the shape was spherical. Our polymeric micelle system can be used as the passive targeting drug delivery system.

• The Korean Journal of Financial Management
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• v.25 no.3
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• pp.33-78
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• 2008

This paper empirically examines whether firms engage in a dynamic adjustment process toward target capital structure and, whether there is a target capital structure or mean reverting using the partial adjustment model while allowing for costly adjustment. Also we investigate the empirical determinants of optimal target capital structure in long term equilibrium. As a result, our empirical model captures at least several important features of capital structure behavior for Korean listed firms. First, Korean firms pursue target capital structure and also there is mean reverting phenomenon. Second, Non-Chaebol and small firm in adjustment speed is faster than Chaebol and large firm. Third, even capital market restricts the adjustment speed interestingly. Fourth, Korean firms have target behavior according to a degree of observed gap. Fifth, Korean firms close about one-fourth of the gap between their actual and target debt ratios within one year and thence targeting behavior explains far more of the observed changes in capital structure than market timing or pecking order considerations. Sixth, capital market is significant in determining optimal capital structure.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.2
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• pp.123-129
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• 2015

$^{64}Cu$-labeled diacetyl-bis($N^4$-methylthiosemicarbazone) is a promising agent for internal radiation therapy and imaging of hypoxic tissues. In the study, we confirmed hypoxia regions in VX2 tumor implanted rabbits with injection $^{64}Cu$-ATSM and $^{18}F$-FDG using positron emission tomography (PET)/computed tomography (CT). PET images with $^{18}F$-FDG and $^{64}Cu$-ATSM were obtained for 40 min by dynamic scan and additional delayed PET images of $^{64}Cu$-ATSM the acquired up to 48 hours. Correlation between intratumoral $O_2$ level and $^{64}Cu$-ATSM PET image was analyzed. $^{64}Cu$-ATSM and $^{18}F$-FDG were intravenously co-injected and the tumor was dissected and cut into slices for a dual-tracer autoradiographic analysis. In the PET imaging, $^{64}Cu$-ATSM in VX2 tumors displayed a specific uptake in hypoxic region for48 h. The uptake pattern of $^{64}Cu$-ATSM in VX2 tumor at 24 and 48 h did not match to the $^{18}F$-FDG. Through ROI analysis, in the early phase (dynamic scan), $^{18}F$-FDG has positive correlation with $^{64}Cu$-ATSM but late phase (24 and 48 h) of the $^{64}Cu$-ATSM showed negative correlation with $^{18}F$-FDG. High uptake of $^{64}Cu$-ATSM in hypoxic region was responded with significant decrease of oxygen pressure, which confirmed by $^{64}Cu$-ATSM PET imaging and autoradiographic analysis. In conclusion, $^{64}Cu$-ATSM can utilize for specific targeting of hypoxic region in tumor, and discrimination between necrotic- and viable hypoxic tissue.

• Journal of Life Science
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• v.33 no.8
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• pp.651-662
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• 2023

Peroxisomes, known as microbodies, are a class of morphologically similar subcellular organelles commonly found in most eukaryotic cells. They are 0.2~1.8 ㎛ in diameter and are bound by a single membrane. The matrix is usually finely granular, but occasionally crystalline or fibrillary inclusions are observed. They characteristically contain hydrogen peroxide (H₂O₂) generating oxidases and contain the enzyme catalase, thus confining the metabolism of the poisonous H₂O₂ within these organelles. Therefore, the eukaryotic organelles are greatly dynamic both in morphology and metabolism. Plant peroxisomes, in particular, are associated with numerous metabolic processes, including β-oxidation, the glyoxylate cycle and photorespiration. Furthermore, plant peroxisomes are involved in development, along with responses to stresses such as the synthesis of important phytohormones of auxins, salicylic acid and jasmonic acids. In the past few decades substantial progress has been made in the study of peroxisome biogenesis in eukaryotic organisms, mainly in animals and yeasts. Advancement of sophisticated techniques in molecular biology and widening of the range of genomic applications have led to the identification of most peroxisomal genes and proteins (peroxins, PEXs). Furthermore, recent applications of proteome study have produced fundamental information on biogenesis in plant peroxisomes, together with improving our understanding of peroxisomal protein targeting, regulation, and degradation. Nonetheless, despite this progress in peroxisome development, much remains to be explained about how peroxisomes originate from the endoplasmic reticulum (ER), then assemble and divide. Peroxisomes perform dynamic roles in many phases of plant development, and in this review, we focus on the latest progress in furthering our understanding of plant peroxisome functions, biogenesis, and dynamics.

• Korean Journal of Construction Engineering and Management
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• v.9 no.1
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• pp.187-198
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• 2008

There are usually plenty of material inventories in a construction site. More inventories can meet unexpected demands, and also they may have an economical advantage by avoiding a probable escalation of raw material costs. On the other hand, these inventories also cause negative aspects to increase costs for storing redundant inventory as well as decreasing construction productivity. Therefore, a proper method of deciding an optimal level of material inventories while considering dynamic variations of resources under uncertainty is very crucial for the economical efficiency of construction projects. This research presents a stochastic modelling method for construction operations, particularly targeting a work process involving on-site fabrication of raw materials like iron-rebar process (delivery, cut and assembly, and placement). To develop the model, we apply the concept of factory physics to depict the overall components of a system. Then, an optimal inventory management model is devised to support purchase decisions where users can make timely actions on how much to order and when to buy raw materials. Also, optimal time lag, which minimizes the storage time for pre-assembled materials, is obtained. To verify this method, a real case is applied to elicit an optimal amount of inventory and time lag. It is found that average values as well as variability of inventory level decreased significantly so as to minimize economic costs related to inventory management under uncertain project condition.