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Search Results: 1 - 10 of 44335 matches for " Yong Hee Kim "
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Differences of Heart Rate Variability during Sevoflurane Anesthesia in Children by Age  [PDF]
Yong-Hee Park, Chang-Hoon Koo, Jin-Tae Kim, Hee-Soo Kim, Hyo-Jin Byon
Open Journal of Anesthesiology (OJAnes) , 2012, DOI: 10.4236/ojanes.2012.23018
Abstract: Background: The child’s central nervous system develops with aging, and heart rate variability (HRV), which is con-trolled by the brain, differs from that of adults. We investigated changes in HRV during sevoflurane anesthesia in children. Methods: One 138 children aged from 2 - 12 years without major underlying problems were enrolled. During maintenance with 2 - 2.5 vol% sevoflurane anesthesia, electrocardiographic data were obtained and power spectral analysis, approximate entropy (ApEn) or Hurst exponent were analyzed and compared in three groups (age 2 - 5 years, 6 - 9 and 10 - 12 years of age). Results: The RR interval increased with aging, but low-frequency powers did not. High- frequency power was greater in the oldest children (P < 0.05), while ApEn and Hurst exponents were lower (P < 0.05). Conclusion: Change in HRV is one of the characteristics of development in children.
An Energy-Efficient MAC Protocol Employing Dynamic Threshold for Wireless Sensor Networks
Kyung Tae Kim,Hee Yong Youn
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/304329
Abstract: Energy efficiency is a critical issue for sensor network since the network lifetime depends on efficient management of the energy resource of sensor nodes. Particularly, designing energy efficient MAC protocol has a significant influence on the performance of wireless sensor network with regards to the energy. The existing MAC protocols developed for sensor network try to avoid energy waste during idle listening time by controlling the duty cycle of the transmission period. Since the traffic conditions are diverse, they may not always display improvements in energy consumption. In this paper we propose a new energy efficient MAC protocol called dynamic threshold MAC (DT-MAC), which employs a dynamic threshold for the buffer of each sensor node to maximize the energy efficiency regardless of specific network traffic condition. Here the packets are stored in the buffer, and then transmitted when the number of packets in the buffer exceeds the threshold dynamically decided according to the number of hops of the node from the source in the path of packet forwarding. The simulation results using OMNnet++ show that DT-MAC enables significant improvement in energy consumption compared to the existing MAC protocols. The proposed DT-MAC protocol also reduces the number of transmissions of control packets. 1. Introduction Recent advances in low power integrated circuit devices, microelectromechanical system (MEMS) technologies, and communications technologies have allowed wide deployment of low-cost,low-power sensors which can be effectively integrated to build wireless sensor networks (WSNs).In general, WSNs consists of tiny sensor nodes forming an ad hoc distributed sensing and data propagation network while collecting the information on the physical environment [1–3]. It has been revolted quickly,and now extensively used in both military and civilian applications, that is, from battlefield surveillance system to modern highway and industry monitoring system, from the emergency rescue system to forest fire detection system, from the very sophisticated earthquake detection system to target tracking and security management. Each sensor node of a WSN has four basic components: sensing unit, processing unit, radio unit, and power unit [4, 5]. It has the capability for sensing, simple computation, data processing, and communication with neighboring sensor nodes. With their capabilities for monitoring the surroundings, the network can provide a fine global picture of the target area through the integration of the data collected from many sensors each providing a
Effective Identification of Akt Interacting Proteins by Two-Step Chemical Crosslinking, Co-Immunoprecipitation and Mass Spectrometry
Bill X. Huang, Hee-Yong Kim
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061430
Abstract: Akt is a critical protein for cell survival and known to interact with various proteins. However, Akt binding partners that modulate or regulate Akt activation have not been fully elucidated. Identification of Akt-interacting proteins has been customarily achieved by co-immunoprecipitation combined with western blot and/or MS analysis. An intrinsic problem of the method is loss of interacting proteins during procedures to remove non-specific proteins. Moreover, antibody contamination often interferes with the detection of less abundant proteins. Here, we developed a novel two-step chemical crosslinking strategy to overcome these problems which resulted in a dramatic improvement in identifying Akt interacting partners. Akt antibody was first immobilized on protein A/G beads using disuccinimidyl suberate and allowed to bind to cellular Akt along with its interacting proteins. Subsequently, dithiobis[succinimidylpropionate], a cleavable crosslinker, was introduced to produce stable complexes between Akt and binding partners prior to the SDS-PAGE and nanoLC-MS/MS analysis. This approach enabled identification of ten Akt partners from cell lysates containing as low as 1.5 mg proteins, including two new potential Akt interacting partners. None of these but one protein was detectable without crosslinking procedures. The present method provides a sensitive and effective tool to probe Akt-interacting proteins. This strategy should also prove useful for other protein interactions, particularly those involving less abundant or weakly associating partners.
Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries
Nam Sang,Kim Yong,Shim Hee-Sang,Kim Jong
Nanoscale Research Letters , 2011,
Abstract: We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoO x ). The copper nanofibers (CuNFs) were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoO x thin-film (CoO x TF) electrodes, the CuNFs@CoO x electrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network. Consequently, the CuNFs@CoO x composite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries.
Depletion of Brain Docosahexaenoic Acid Impairs Recovery from Traumatic Brain Injury
Abhishek Desai, Karl Kevala, Hee-Yong Kim
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0086472
Abstract: Omega-3 fatty acids are crucial for proper development and function of the brain where docosahexaenoic acid (DHA), the primary omega-3 fatty acid in the brain, is retained avidly by the neuronal membranes. We investigated the effect of DHA depletion in the brain on the outcome of traumatic brain injury (TBI). Pregnant mice were put on an omega-3 fatty acid adequate or deficient diet from gestation day 14 and the pups were raised on the respective diets. Continuation of this dietary regime for three generations resulted in approximately 70% loss of DHA in the brain. Controlled cortical impact was delivered to both groups of mice to produce severe TBI and the functional recovery was compared. Compared to the omega-3 adequate mice, the DHA depleted mice exhibited significantly slower recovery from motor deficits evaluated by the rotarod and the beam walk tests. Furthermore, the DHA deficient mice showed greater anxiety-like behavior tested in the open field test as well as cognitive deficits evaluated by the novel object recognition test. The level of alpha spectrin II breakdown products, the markers of TBI, was significantly elevated in the deficient mouse cortices, indicating that the injury is greater in the deficient brains. This observation was further supported by the reduction of NeuN positive cells around the site of injury in the deficient mice, indicating exacerbated neuronal death after injury. These results suggest an important influence of the brain DHA status on TBI outcome.
Electrochemical Synthesis of CdSe Quantum Dot Array on Graphene Basal Plane using Mesoporous Silica Thin Film Templates
Yong-Tae Kim,Jung Hee Han,Byung Hee Hong,Young-Uk Kwon
Physics , 2010, DOI: 10.1002/adma.200902736
Abstract: We report on the synthesis of CdSe quantum dots on a graphene surface by an electrochemical deposition method. By using a mesoporous silica film formed on the graphene surface as a template and a potential equalizer between the edge/defect sites and the basal plane of the graphene, CdSe quantum dots can be grown on the basal plane into a regular hexagonal array.
En bloc Extended Total Thymectomy and Extrapleural Pneumonectomy in Masaoka stage IVA Thymomas
Hee Yang, Yoo Yoon, Hong Kim, Yong Choi, Kwhanmien Kim, Young Shim, Jungho Han, Jhingook Kim
Journal of Cardiothoracic Surgery , 2011, DOI: 10.1186/1749-8090-6-28
Abstract: From 1994 to 2009, five patients initially diagnosed with pleural dissemination and two patients with recurrent tumors in the pleura and lungs after a total thymectomy, were identified. Seven patients had an extrapleural pneumonectomy performed. For the first operation, five patients underwent additional en bloc extended total thymectomy.Two recurrent cases were identified 55.2 and 12.3 months after first operation. Two patients had WHO type B1-B2 tumors, two had B2, two had B2-B3, and one had a B3 tumor. The mean hospital stay was 15.3 days (range: 7-29). There was no operative mortality. Four patients had neoadjuvant chemotherapy and five were treated with adjuvant chemotherapy. The median survival was 30.6 months and the Kaplan-Meier 2-year survival was 100% (95% confidence interval: 24.6-36.6 months). One patient, who did not receive induction chemotherapy, had distant metastases after surgery.En bloc extended total thymectomy and extrapleural pneumonectomy can be safely performed on selected patients with stage IVA thymomas and is expected to achieve complete local control. Although the treatment strategy has yet to be standardized, complete resection with appropriate systemic therapy may improve survival in otherwise fatal disease.The prognosis of locally advanced thymomas within the thoracic cavity (Masaoka stage IVA) is poor [1-3]; there is no reliable treatment strategy established to date [4,5]. All three common therapeutic modalities (surgery, chemotherapy and radiation) can be used for the treatment of locally advanced thymoma [6,7]. However, the combination of these modalities has not been standardized.Complete local control is the mainstay of treatment for a thymoma; this is because thymomas rarely metastasize to distant organs. For stage IVA thymomas, the tumor has not yet spread to extrathoracic organs and is still locally advanced. This stage allows for complete eradication. However, in miliary or confluent pleural disseminated thymomas, complete re
Up-regulated expression of l-caldesmon associated with malignancy of colorectal cancer
Kim Kyung-Hee,Yeo Seung-Gu,Kim Won Ki,Kim Dae Yong
BMC Cancer , 2012, DOI: 10.1186/1471-2407-12-601
Abstract: Background Caldesmon (CaD), a major actin-associated protein, is found in smooth muscle and non-muscle cells. Smooth muscle caldesmon, h-CaD, is a multifunctional protein, and non-muscle cell caldesmon, l-CaD, plays a role in cytoskeletal architecture and dynamics. h-CaD is thought to be an useful marker for smooth muscle tumors, but the role(s) of l-CaD has not been examined in tumors. Methods Primary colon cancer and liver metastasis tissues were obtained from colon cancer patients. Prior to chemoradiotherapy (CRT), normal and cancerous tissues were obtained from rectal cancer patients. Whole-tissue protein extracts were analyzed by 2-DE-based proteomics. Expression and phosphorylation level of main cellular signaling proteins were determined by western blot analysis. Cell proliferation after CaD siRNA transfection was monitored by MTT assay. Results The expression level of l-CaD was significantly increased in primary colon cancer and liver metastasis tissues compared to the level in the corresponding normal tissues. In cancerous tissues obtained from the patients showing poor response to CRT (Dworak grade 4), the expression of l-CaD was increased compared to that of good response group (Dworak grade 1). In line with, l-CaD positive human colon cancer cell lines were more resistant to 5-fluorouracil (5-FU) and radiation treatment compared to l-CaD negative cell lines. Artificial suppression of l-CaD increased susceptibility of colon cancer cells to 5-FU, and caused an increase of p21 and c-PARP, and a decrease of NF-kB and p-mTOR expression. Conclusion Up-regulated expression of l-CaD may have a role for increasing metastatic property and decreasing CRT susceptibility in colorectal cancer cells.
Finite Element Analysis with Paraxial & Viscous Boundary Conditions for Elastic Wave Propagation  [PDF]
Hee Seok Kim
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.412107
Abstract: In this study, two studies are performed. One is to apply paraxial boundary conditions which are local boundary conditions based on paraxial approximations of the one-way wave equations to finite element analysis. To do this, a penalty functional is proposed and the existence and uniqueness of the extremum of the proposed functional is demonstrated. The other is to improve the capacity of viscous boundary conditions using dashpots. To do this, customary viscous boundary conditions are modified to maximize the efficiency according to angles of incidence and materials. For the numerical analysis of elasticity with paraxial boundary conditions and the modified viscous boundary conditions, the coding of the finite element models is implemented, and the efficiency of those boundary conditions is investigated.
Journal of Building Construction and Planning Research: A New Platform for Building Researchers  [PDF]
Gwang-Hee Kim
Journal of Building Construction and Planning Research (JBCPR) , 2013, DOI: 10.4236/jbcpr.2013.12004
Abstract: Journal of Building Construction and Planning Research: A New Platform for Building Researchers
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