• 대한기계학회논문집A
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• 제24권8호
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• pp.2065-2073
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• 2000

In this paper, we present a wall climbing robot whose gate pattern takes after those of specialized climbing animals such as spiders. Characteristic features of the biological locomotion are partly realized in the design of the mechanism. The robot has two legs and a trunk. Each one-dof leg with suction pads is driven by a motor which employs a closed loop linkage mechanism, and the trunk with suction pads steers the whole body of the robot using a motor. By generating adequate trajectories of the leg and simultaneously alternating the suction pattern between the legs and the trunk, we can achieve the spider like motion. The proposed idea is implemented in a robot and some tests are performed to evaluate its performance.

• KSBB Journal
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• 제31권2호
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• pp.91-99
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• 2016

Tea is an aqueous infusion of dried leaves of the plant Camellia sinensis L. and is the second most widely consumed beverage around the world after water. Aroma compounds of tea differ largely depending on the manufacturing process, even from the same categories of different origins. The flavor of tea can be divided into two categories: taste (non-volatile compounds) and aroma (volatile compounds). In the present study, we review the formation mechanism of main aromas generated from carotenoids, lipids, glycosides as precursors, and Maillard reaction during the tea manufacturing process, with biological and chemical mechanisms.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2008년도 Proceedings of the Convention
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• pp.49-52
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• 2008

Parkinson's disease is characterized by motor disturbances and dopaminergic neurodegeneration. parkin and PINK1, two most critical Parkinson's disease-associated genes, have been intensively studied to address the underlying molecular pathogenesis of the disease, but our understanding still remains unclear. Through generation and characterization of Drosophila mutants for PINK1, we show that PINK1 is required for mitochondrial integrity and function in both indirect flight muscles and dopaminergic neurons. Surprisingly, we find that PINK1 mutants share striking phenotypic similarities with parkin mutants. Indeed, transgenic expression of parkin dramatically ameliorates all PINK1 loss-of-function phenotypes, but not vice versa, implicating that Parkin acts downstream of PINK1 in maintaining mitochondrial integrity and function in both muscles and dopaminergic neurons. With the establishment of the PINK1-Parkin pathway, we are trying to further investigate the detailed molecular relationship between PINK1 and Parkin using both mammalian dopaminergic neuronal cells for biochemical analysis and Drosophila model animal for genetic analysis. We believe that elucidating the molecular function of Parkinson's disease-associated genes will be of big help for the ultimate understanding of the pathogenic mechanism of this disease and also for the development of effective drugs for Parkinson's disease.

• Food Science and Biotechnology
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• 제16권6호
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• pp.954-957
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• 2007

Gelation mechanism of xanthan-carob mixture (X/C) was investigated based on thermorheological behavior. Three X/C ratios (1:3, 1:1, and 3:1) were studied. Small amplitude oscillatory shear tests were performed to measure linear viscoelastic behavior during gelation. Temperature sweep ($-1^{\circ}C/min$) experiments were conducted. Using a non-isothermal kinetic model, activation energy (Ea) during gelation was calculated. At 1% total concentration, the Ea for xanthan fraction (${\phi}_x$)=0.25, 0.5, and 0.75 were 178, 159, and 123 kJ/mol, respectively. However, a discontinuity was observed in the activation energy plots. Based on this, two gelation mechanisms were presumed-association of xanthan and carob molecules and aggregation of polymer strands. The association process is the primary mechanism to form 3-D networks in the initial stage of gelation and the aggregation of polymer strands played a major role in the later stage.

• 대한의용생체공학회:의공학회지
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• 제34권1호
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• pp.40-45
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• 2013

The conventional simulators used the expensive commercial artificial heart with a limited performance, and focused on replicating the heart function. The arterial pressure is the key factor of the cardiovascular disease. The purpose of this study is to develop a simulator focused on the pressure wave. The simulator is composed of a step motor, slider-crank mechanism, piston-cylinder, two check valves, a elastic tube, and two reservoirs. With the changes of design parameters, the functions of the simulator were evaluated. The simulator shows the good agreement of the characteristics of the cardiovascular system.

• 수면정신생리
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• 제23권1호
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• pp.5-9
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• 2016

Previous research has identified the biological, psychological, and social factors that confer an elevated risk for suicide. Evidence suggests that sleep disturbances are one of the risk factors that predict an increased risk for suicidal behaviors. Both sleep disorders and general sleep complaints are linked to higher levels of suicidal ideation and depression, as well as increased rates of suicide and suicide attempts. The causal mechanism of this association is not clear. For example, it is not known if insomnia is an independent phenomenon that if interrupted could prevent the emergence of a mental disorder, or if insomnia is a symptom of another developing illness. Hypofrontality, HPA dysfunction, and an impaired serotonergic system are potential mechanisms underlying the association of sleep disturbances and suicidal behavior. Future research is necessary to examine the specific mechanism of this association between sleep and suicide, which may lead to an effective intervention and diminished suicide risk.

• 대한불안의학회지
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• 제7권1호
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• pp.3-8
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• 2011

Cognitive models of panic disorder have emphasized cognitive distortions' roles in the maintenance and treatment of panic disorder (PD). However, the patient's difficulty with identifying and managing emotional experiences might contribute to an enduring vulnerability to panic attacks. Numerous researchers, employing emotion processing paradigms and neuroimaging techniques, have investigated the empirical evidence for poor emotion processing in PD. For years, researchers considered that abnormal emotion processing in PD might reflect a dysfunction of the frontal-temporal-limbic circuits. Although neuropsychological studies have not provided consistent results regarding this model, a few studies have tried to find the biological basis of dysfunctional emotion processing in PD. In this article, we examine the possibility of dysregulation of emotion processing in PD. Specifically we discuss the neural basis of emotion processing and the manner in which such neurocognitive impairments may help clarify PD's core symptoms.

• BMB Reports
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• 제54권6호
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• pp.285-294
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• 2021

The lymphatic vasculature plays important role in regulating fluid homeostasis, intestinal lipid absorption, and immune surveillance in humans. Malfunction of lymphatic vasculature leads to several human diseases. Understanding the fundamental mechanism in lymphatic vascular development not only expand our knowledge, but also provide a new therapeutic insight. Recently, Hippo-YAP/TAZ signaling pathway, a key mechanism of organ size and tissue homeostasis, has emerged as a critical player that regulate lymphatic specification, sprouting, and maturation. In this review, we discuss the mechanistic regulation and pathophysiological significant of Hippo pathway in lymphatic vascular development.

• Animal Bioscience
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• 제34권3_spc호
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• pp.345-353
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• 2021

Phytobiotics, also known as phytochemicals or phytogenics, have a wide variety of biological activities and have recently emerged as alternatives to synthetic antibiotic growth promoters. Numerous studies have reported the growth-promoting effects of phytobiotics in chickens, but their precise mechanism of action is yet to be elucidated. Phytobiotics are traditionally known for their antioxidant activity. However, extensive investigations have shown that these compounds also have anti-inflammatory, antimicrobial, and transcription-modulating effects. Phytobiotics are non-nutritive constituents, and their bioavailability is low. Nonetheless, their beneficial effects have been observed in several tissues or organs. The health benefits of the ingestion of phytobiotics are attributed to their antioxidant activity. However, several studies have revealed that not all these benefits could be explained by the antioxidant effects alone. In this review, I focused on the bioavailability of phytobiotics and the possible mechanisms underlying their overall effects on intestinal barrier functions, inflammatory status, gut microbiota, systemic inflammation, and metabolism, rather than the specific effects of each compound. I also discuss the possible mechanisms by which phytobiotics contribute to growth promotion in chickens.

• Molecules and Cells
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• 제26권2호
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• pp.200-205
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• 2008

The mitogen-activated protein kinase (MAPK) signaling pathway is activated in response to extracellular stimuli and regulates various activities in eukaryotic cells. Following exposure to stimuli, MAPK is known to be activated via dual phosphorylation at a conserved TxY motif in the activation loop; both threonine and tyrosine residues are phosphorylated by an upstream kinase. However, the mechanism underlying dual phosphorylation is not clearly understood. In the budding yeast Saccharomyces cerevisiae, the Hog1 MAPK mediates the high-osmolarity glycerol (HOG) signaling pathway. Tandem mass spectrometry and phosphospecific immunoblotting were performed to quantitatively monitor the dynamic changes occurring in the phosphorylation status of the TxY motif of Hog1 on exposure to osmotic stress. The results of our study suggest that the tyrosine residue is preferentially and dynamically phosphorylated following stimulation, and this in turn leads to the dual phosphorylation. The tyrosine residue was hyperphosphorylated in the absence of a threonine residue; this result suggests that the threonine residue is critical for the control of signaling noise and adaptation to osmotic stress.