• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.35 no.3
• /
• pp.215-222
• /
• 2022

Artificial neuromorphic devices are considered the key component in realizing energy-efficient and brain-inspired computing systems. For the artificial neuromorphic devices, various material candidates and device architectures have been reported, including two-dimensional materials, metal-oxide semiconductors, organic semiconductors, and halide perovskite materials. In addition to conventional electrical neuromorphic devices, optoelectronic neuromorphic devices, which operate under a light stimulus, have received significant interest due to their potential advantages such as low power consumption, parallel processing, and high bandwidth. This article reviews the recent progress in optoelectronic neuromorphic devices using various active materials such as two-dimensional materials, metal-oxide semiconductors, organic semiconductors, and halide perovskites

• Korean Journal of Radiology
• /
• v.22 no.12
• /
• pp.2034-2051
• /
• 2021

Metabolic encephalopathy is a critical condition that can be challenging to diagnose. Imaging provides early clues to confirm clinical suspicions and plays an important role in the diagnosis, assessment of the response to therapy, and prognosis prediction. Diffusion-weighted imaging is a sensitive technique used to evaluate metabolic encephalopathy at an early stage. Metabolic encephalopathies often involve the deep regions of the gray matter because they have high energy requirements and are susceptible to metabolic disturbances. Understanding the imaging patterns of various metabolic encephalopathies can help narrow the differential diagnosis and improve the prognosis of patients by initiating proper treatment regimen early.

• BMB Reports
• /
• v.57 no.1
• /
• pp.19-29
• /
• 2024

Mitochondrial DNA (mtDNA), a multicopy genome found in mitochondria, is crucial for oxidative phosphorylation. Mutations in mtDNA can lead to severe mitochondrial dysfunction in tissues and organs with high energy demand. MtDNA mutations are closely associated with mitochondrial and age-related disease. To better understand the functional role of mtDNA and work toward developing therapeutics, it is essential to advance technology that is capable of manipulating the mitochondrial genome. This review discusses ongoing efforts in mitochondrial genome editing with mtDNA nucleases and base editors, including the tools, delivery strategies, and applications. Future advances in mitochondrial genome editing to address challenges regarding their efficiency and specificity can achieve the promise of therapeutic genome editing.

• The Korean Journal of Food And Nutrition
• /
• v.28 no.3
• /
• pp.404-414
• /
• 2015

Taurine is one of the most abundant free ${\beta}$-amino acids in the human body that accounts for 0.1% of the human body weight. It has a sulfonic acid group in place of the more common carboxylic acid group. Mollusks and meat are the major dietary source of taurine, and mother's milks also include high levels of this amino acid. The leukocytes, heart, muscle, retina, kidney, bone, and brain contain more taurine than other organs. Furthermore, taurine can be synthesized in the brain and liver from cysteine. There are no side effects of excessive taurine intake in humans; however, in case of taurine deficiency, retinal abnormalities, reduced plasma taurine concentration, and other abnormalities may occur. Taurine enters the cell via a cell membrane receptor. It is excreted in the urine (approximately 95%) and feces (approximately 5%). Taurine has a number of features and functions, including conjugation with bile acid, reduction of blood cholesterol and triglyceride levels, promotion of neuron cell differentiation and growth, antioxidant effects, maintenance of cell membrane stability, retinal development, energy generation, depressant effects, regulation of calcium level, muscle contraction and relaxation, bone formation, anti-inflammatory effects, anti-cancer and anti-atherogenic effects, and osmotic pressure control. However, the properties, functions, and effects of taurine require further studies in future.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.51.2-51.2
• /
• 2015

Understanding interfacial phenomena has been one of the main research issues not only in semiconductors but only in life sciences. I have been trying to meet the atomic scale surface and interface analysis challenges from semiconductor industries and furthermore to extend the application scope to biomedical areas. Optical imaing has been most widely and successfully used for biomedical imaging but complementary ion beam imaging techniques based on mass spectrometry and ion scattering can provide more detailed molecular specific and nanoscale information In this presentation, I will review the 27 years history of medium energy ion scattering (MEIS) development at KRISS and DGIST for nanoanalysis. A electrostatic MEIS system constructed at KRISS after the FOM, Netherland design had been successfully applied for the gate oxide analysis and quantitative surface analysis. Recenlty, we developed time-of-flight (TOF) MEIS system, for the first time in the world. With TOF-MEIS, we reported quantitative compositional profiling with single atomic layer resolution for 0.5~3 nm CdSe/ZnS conjugated QDs and ultra shallow junctions and FINFET's of As implanted Si. With this new TOF-MEIS nano analysis technique, details of nano-structured materials could be measured quantitatively. Progresses in TOF-MEIS analysis in various nano & bio technology will be discussed. For last 10 years, I have been trying to develop multimodal nanobio imaging techniques for cardiovascular and brain tissues. Firstly, in atherosclerotic plaque imaging, using, coherent anti-stokes raman scattering (CARS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) multimodal analysis showed that increased cholesterol palmitate may contribute to the formation of a necrotic core by increasing cell death. Secondly, surface plasmon resonance imaging ellipsometry (SPRIE) was developed for cell biointerface imaging of cell adhesion, migration, and infiltration dynamics for HUVEC, CASMC, and T cells. Thirdly, we developed an ambient mass spectrometric imaging system for live cells and tissues. Preliminary results on mouse brain hippocampus and hypotahlamus will be presented. In conclusions, multimodal optical and mass spectrometric imaging privides overall structural and morphological information with complementary molecular specific information, which can be a useful methodology for biomedical studies. Future challenges in optical and mass spectrometric imaging for new biomedical applications will be discussed.

• The Journal of the Korea Contents Association
• /
• v.9 no.11
• /
• pp.289-296
• /
• 2009

In this study, I presented power control unit with potential use in the magnetic stimulation of biological systems. The effect of the magnetic stimulation depends on the geometry and orientation of the induced electric field as well as on the current pulse waveform delivered by the stimulator coil. TMS is achieved from the outside of the head using pulses of electromagnetic field that induce an electric field in the brain. There are numerous possibities in the applications TMS, such as diagnosis and therapy through the brain stimulation. These factors are very important to define the equipment requirements and characteristics in that the topology of the power supply and the size and geometry of the coil. The proposed solution is the generation of current pulses with variable amplitude and duration, according to a user defined input. Another solution is the topology that uses elements to store and transfer energy from the power source to the load. In addition to proposed topology, an adequate control strategy and right set of the power circuit parameters made possible to obtain unipolar waves and bipolar waves.

• The Korea Journal of Herbology
• /
• v.26 no.4
• /
• pp.67-74
• /
• 2011

Objectives : The purpose of the study is to determine the neuroprotective effects of the water extract of Angelicae Acutilobae Radix(AA) on ischemia reperfusion-induced apoptosis in SK-N-SH human brain neuronal cells. Methods: SK-N-SH cells were treated with different concentrations of AA water extract (0.1, 0.2, 0.5 and 1.0 mg/ml) for 2 hr and then stimulated with Dulbecco's phosphate-buffered saline containing CI-DPBS: 3mM sodium azide and 10 mM 2-deoxy-D-glucose for 45 min, reperfused with growth medium, and incubated for 24 h. Cell viability was determined by WST-1 assay, and ATP/ADP levels were measured by ADP/ATP ratio assay kit. The levels of caspase-3 protein were determined by Western blot and apoptotic body was observed by Hoechst 33258 staining. Results : AA extract significantly inhibited decreasing the cell viability in ischemia-induced SK-N-SH cells. AA also increased the ratio of ADP/ATP in ischemia-induced neuronal cells and decreased the expression levels of apoptotic protein, caspase-3 and apoptotic DNA damage. Conclusions : Our results suggest that AA extract has a neuroprotective property via suppressing the apoptosis and increasing the energy levels in neuronal cells, suggesting that AA extract may has a therapeutic potential in the treatment of ischemic brain injury.

• Korean journal of applied entomology
• /
• v.31 no.4
• /
• pp.329-337
• /
• 1992

Studies were carried out to investigate changes of lipid and carbohydrate contents in the hemolymph of the Oriental tobacco budworm(Helicoverpa assulta (Guenee» adults during flight and hormonal effects on mobilization of energy sources in the hemolymph. During a few minutes after flight, both sexes showed a rapid increase in lipid content and the high level was maintained for about 2 hours. But carbohydrate content in the hemolymph during flight showed almost no change but a slight increase seen during the first 10 min of flight in males only. Synthetic adipokinetic(Lom-AKH- n), hypertrehalosemic(Bld-HrTH) hormones and brain/ corpora cardiaca extract of H. assulta adult elevated lipid and carbohydrate contents in hemolymph and the effect was much more pronounced for lipid. These results suggested that lipid is a main fuel for flight activity and lipid mobilization is under the hormonal control. And this study showed that both adipokinetic and hypertrehalosemic factors may exist in H. assulta and these factors may have similar structures to those of Mas-AKH, Hez-HrTH, Lom-AKH- n or Pea-HrTH.

• Molecules and Cells
• /
• v.37 no.11
• /
• pp.767-776
• /
• 2014

Alzheimer's disease (AD) is clinically characterized with progressive memory loss and cognitive decline. Synaptic dysfunction is an early pathological feature that occurs prior to neurodegeneration and memory dysfunction. Mounting evidence suggests that aggregation of amyloid-${\alpha}$ ($A{\alpha}$) and hyperphosphorylated tau leads to synaptic deficits and neurodegeneration, thereby to memory loss. Among the established genetic risk factors for AD, the ${\varepsilon}4$ allele of apolipoprotein E (APOE) is the strongest genetic risk factor. We and others previously demonstrated that apoE regulates $A{\alpha}$ aggregation and clearance in an isoform-dependent manner. While the effect of apoE on $A{\alpha}$ may explain how apoE isoforms differentially affect AD pathogenesis, there are also other underexplored pathogenic mechanisms. They include differential effects of apoE on cerebral energy metabolism, neuroinflammation, neurovascular function, neurogenesis, and synaptic plasticity. ApoE is a major carrier of cholesterols that are required for neuronal activity and injury repair in the brain. Although there are a few conflicting findings and the underlying mechanism is still unclear, several lines of studies demonstrated that apoE4 leads to synaptic deficits and impairment in long-term potentiation, memory and cognition. In this review, we summarize current understanding of apoE function in the brain, with a particular emphasis on its role in synaptic plasticity and the underlying cellular and molecular mechanisms, involving low-density lipoprotein receptor-related protein 1 (LRP1), syndecan, and LRP8/ApoER2.

• Journal of Yeungnam Medical Science
• /
• v.12 no.2
• /
• pp.331-338
• /
• 1995

Laserthermia is a new method of local hyperthermia using fiber optic guided probe with computer controlled Nd-YAG laser system. We used a synthetic sapphire probe and allowed irradiation with contolled low power laser energy (less than 5W), in different thermal condition (temprature: 38.5~50 degrees C) for 10 minutes, in the normal brain tissue of 18 rabbits. In results, the histological changes of brain tissue was variable (myelin condensation, chromatin condensation, nuclear waving and palisading, RBC discoloration, cell necrosis) in microscopic findings after laser irradiation, but changing area was not occured proportionally in thermal condition level. Cell necrosis appears to over 44.5 degrees C and the distance was about 1.25 mm. This study, using computer controlled laserthermia system for interstitial local hyperthermia, may offer many advantages in the experimental treatment and clinical management of tumor. Minimizing normal tissue damage is now being developed.