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Search Results: 1 - 10 of 55368 matches for " Yong Jin Park "
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The Citizen as Issue Specialists in a Changing Media Environment
S. Mo Jang,Yong Jin Park
Future Internet , 2013, DOI: 10.3390/fi5040568
Abstract: Although recent research suggests that the selective nature of new media helps foster issue specialists, little empirical evidence has been documented, mostly due to theoretical and methodological limitations. Extending the concept of issue publics, the present study proposes a method to estimate the degree to which an individual is a specialist- or a generalist-type citizen. Applying the method to the 2008 American National Election Studies data, the study reveals various characteristics of specialists and generalists. The results indicate that specialist-type citizens are positively associated with online news use, but negatively associated with conventional news media, such as television, newspaper, and radio. The implications of the growth of specialists as well as the validity of the proposed method are discussed.
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.
A Radio-Aware Routing Algorithm for Reliable Directed Diffusion in Lossy Wireless Sensor Networks
Yong-Pyo Kim,Euihyun Jung,Yong-Jin Park
Sensors , 2009, DOI: 10.3390/s91008047
Abstract: In Wireless Sensor Networks (WSNs), transmission errors occur frequently due to node failure, battery discharge, contention or interference by objects. Although Directed Diffusion has been considered as a prominent data-centric routing algorithm, it has some weaknesses due to unexpected network errors. In order to address these problems, we proposed a radio-aware routing algorithm to improve the reliability of Directed Diffusion in lossy WSNs. The proposed algorithm is aware of the network status based on the radio information from MAC and PHY layers using a cross-layer design. The cross-layer design can be used to get detailed information about current status of wireless network such as a link quality or transmission errors of communication links. The radio information indicating variant network conditions and link quality was used to determine an alternative route that provides reliable data transmission under lossy WSNs. According to the simulation result, the radio-aware reliable routing algorithm showed better performance in both grid and random topologies with various error rates. The proposed solution suggested the possibility of providing a reliable transmission method for QoS requests in lossy WSNs based on the radio-awareness. The energy and mobility issues will be addressed in the future work.
TinyONet: A Cache-Based Sensor Network Bridge Enabling Sensing Data Reusability and Customized Wireless Sensor Network Services
Eui-Hyun Jung,Yong-Jin Park
Sensors , 2008, DOI: 10.3390/s8127930
Abstract: In recent years, a few protocol bridge research projects have been announced to enable a seamless integration of Wireless Sensor Networks (WSNs) with the TCP/IP network. These studies have ensured the transparent end-to-end communication between two network sides in the node-centric manner. Researchers expect this integration will trigger the development of various application domains. However, prior research projects have not fully explored some essential features for WSNs, especially the reusability of sensing data and the data-centric communication. To resolve these issues, we suggested a new protocol bridge system named TinyONet. In TinyONet, virtual sensors play roles as virtual counterparts of physical sensors and they dynamically group to make a functional entity, Slice. Instead of direct interaction with individual physical sensors, each sensor application uses its own WSN service provided by Slices. If a new kind of service is required in TinyONet, the corresponding function can be dynamically added at runtime. Beside the data-centric communication, it also supports the node-centric communication and the synchronous access. In order to show the effectiveness of the system, we implemented TinyONet on an embedded Linux machine and evaluated it with several experimental scenarios.
Stable Isolation of Phycocyanin from Spirulina platensis Associated with High-Pressure Extraction Process
Yong Chang Seo,Woo Seok Choi,Jong Ho Park,Jin Oh Park,Kyung-Hwan Jung,Hyeon Yong Lee
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14011778
Abstract: A method for stably purifying a functional dye, phycocyanin from Spirulina platensis was developed by a hexane extraction process combined with high pressure. This was necessary because this dye is known to be very unstable during normal extraction processes. The purification yield of this method was estimated as 10.2%, whose value is 3%–5% higher than is the case from another conventional separation method using phosphate buffer. The isolated phycocyanin from this process also showed the highest purity of 0.909 based on absorbance of 2.104 at 280 nm and 1.912 at 620 nm. Two subunits of phycocyanin namely α-phycocyanin (18.4 kDa) and β-phycocyanin (21.3 kDa) were found to remain from the original mixtures after being extracted, based on SDS-PAGE analysis, clearly demonstrating that this process can stably extract phycocyanin and is not affected by extraction solvent, temperature, etc. The stability of the extracted phycocyanin was also confirmed by comparing its DPPH (α,α-diphenyl-β-picrylhydrazyl) scavenging activity, showing 83% removal of oxygen free radicals. This activity was about 15% higher than that of commercially available standard phycocyanin, which implies that the combined extraction method can yield relatively intact chromoprotein through absence of degradation. The results were achieved because the low temperature and high pressure extraction effectively disrupted the cell membrane of Spirulina platensis and degraded less the polypeptide subunits of phycocyanin (which is a temperature/pH-sensitive chromoprotein) as well as increasing the extraction yield.
Load-Measuring Pot Bearing with Built-In Load Cell —Part II: Fatigue Performance and Experimental Temperature Correction  [PDF]
Jeong-Rae Cho, Young Jin Kim, Jong-Won Kwark, Sung Yong Park, Won Jong Chin, Byung-Suk Kim
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.511108

This paper presents the results of fatigue performance tests performed up to 10 million cycles on a load-measuring pot bearing with built-in load cell to verify its field applicability and proposes an empirical temperature correction formula. In Part I of this work, various measurement performances of the load-measuring pot bearing were evaluated through static and dynamic loading tests. Bridge bearings are subjected to the effect of fatigue caused by the repeated application of moving loads and exposed to harsh site conditions including cold and hot weathers differently to laboratory conditions. Accordingly, the durability of the load-measuring pot bearing with built-in load cell shall be secured and the environmental effects like temperature shall be minimized for its application on field. This study conducted fatigue tests up to 10 million cycles on a load-measuring pot bearing with the capacity of 1000 kN to examine eventual degradation of the measurement accuracy with respect to the number of fatigue loading cycles. In addition, the experimental temperature correction procedure is proposed to obtain the temperature correction formula enabling to correct the effect of temperature on the load measurement.

Load-Measuring Pot Bearing with Built-In Load Cell —Part I: Design and Performance  [PDF]
Jeong-Rae Cho, Young Jin Kim, Jong-Won Kwark, Sung Yong Park, Won Jong Chin, Byung-Suk Kim
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.511104

This paper presents the underlying principle and the results of various performance evaluations for a load-measuring pot bearing with built-in load cell. The pot bearing composed of a pot made of steel in which an elastomer disk is inserted is a bearing supporting larger loads than the elastomeric bearing and accommodating rotational movement. Owing to a Poisson’s ratio close to 0.5, elastomer withstands hydrostatic pressure when confined in a rigid body. Accounting for this principle, the vertical load applied on the pot bearing can be obtained by converting the pressure acting on the elastomer. Therefore, a load-measuring pot bearing is developed in this study by embedding a load cell exhibiting remarkable durability in the base plate of the bearing. The details for the insertion of the load cell in the base plate of the pot were improved through finite element analysis to secure sufficient measurement accuracy. The evaluation of the static performance of the pot bearing applying these improved details verified that the bearing exhibited sufficient accuracy for the intended measurement purpose. The dynamic performance evaluation results indicated that accurate measurement of the dynamic load was also achieved without time lag.

Induction of Heme Oxygenase-1 Inhibits Cell Death in Crotonaldehyde-Stimulated HepG2 Cells via the PKC-δ -p38 -Nrf2 Pathway
Seung Eun Lee, Hana Yang, Seong Il Jeong, Young-Ho Jin, Cheung-Seog Park, Yong Seek Park
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0041676
Abstract: Background Crotonaldehyde, an alpha, beta-unsaturated aldehyde present in cigarette smoke, is an environmental pollutant and a product of lipid peroxidation. It also produces adverse effects to humans and is considered as a risk factor for various diseases. Heme oxygenase-1 (HO-1) plays important roles in protecting cells against oxidative stress as a prime cellular defense mechanism. However, HO-1 may be associated with cell proliferation and resistance to apoptosis in cancer cells. The aim of this study was to examine the effects of HO-1 induction on cell survival in crotonaldehyde-stimulated human hepatocellular carcinoma (HepG2) cells. Methods To investigate the signaling pathway involved in crotonaldehyde-induced HO-1 expression, we compared levels of inhibition efficiency of specific inhibitors and specific small interfering RNAs (siRNAs) of several kinases. The cell-cycle and cell death was measured by FACS and terminal dUTP nick-end labeling (TUNEL) staining. Results Treatment with crotonaldehyde caused a significant increase in nuclear translocation of NF-E2 related factor (Nrf2). Treatment with inhibitors of the protein kinase C-δ (PKC-δ) and p38 pathways resulted in obvious blockage of crotonaldehyde-induced HO-1 expression. Furthermore, treatment with HO-1 siRNA and the specific HO-1 inhibitor zinc-protoporphyrin produced an increase in the G0/G1 phase of the cell cycle in crotonaldehyde-stimulated HepG2 cells. Conclusions Taken together, the results support an anti-apoptotic role for HO-1 in crotonaldehyde-stimulated human hepatocellular carcinoma cells and provide a mechanism by which induction of HO-1 expression via PKC-δ–p38 MAPK–Nrf2 pathway may promote tumor resistance to oxidative stress.
Progesterone produces antinociceptive and neuroprotective effects in rats with microinjected lysophosphatidic acid in the trigeminal nerve root
Min Kim, Hea Shin, Kyoung Won, Kui Yang, Jin Ju, Yoon Park, Jae Park, Yong Bae, Dong Ahn
Molecular Pain , 2012, DOI: 10.1186/1744-8069-8-16
Abstract: Under anesthesia, the Sprague-Dawley rats were mounted onto a stereotaxic frame and 3 μL of lysophosphatidic acid (LPA, 1 nmol) was injected into the trigeminal nerve root to produce demyelination. This treatment decreased the air-puff thresholds, persisted until postoperative day 130, and then returned to the preoperative levels 160 days after LPA injection. The LPA-treated rats also showed a significant hyper-responsiveness to pin-prick stimulation. We further investigated the antinociceptive and neuroprotective effects of progesterone in rats undergoing demyelination of the trigeminal nerve root. Progesterone (8, 16 mg/kg/day) was administered subcutaneously, beginning on the operative day, for five consecutive days in the LPA-treated rats. Treatment with progesterone produced significant early anti-allodynic effects and delayed prolonged anti-allodynic effects. The expression of protein zero (P0) and peripheral myelin protein 22 (PMP22) were significantly down-regulated in the trigeminal nerve root on postoperative day 5 following LPA injection. This down-regulation of the P0 and PMP22 levels was blocked by progesterone treatment.These results suggest that progesterone produces antinociceptive effects through neuroprotective action in animals with LPA-induced trigeminal neuropathic pain. Moreover, progesterone has potential utility as a novel therapy for trigeminal neuropathic pain relief at an appropriate managed dose and is therefore a possible future treatment strategy for improving the recovery from injury.Progesterone is a female gonadal steroid hormone synthesized in the ovary that exerts a wide range of actions against its target tissues including the uterus, mammary glands and brain. There is however abundant evidence now that progesterone has functions that go beyond its role as a female sex hormone. Exogenous progesterone and its derivates have been shown to be a successful treatment for rat models of traumatic brain injury and stroke [1-4], and periph
A Rapid Colorimetric Loop-Mediated Isothermal Amplification Assay for the Detection of Lawsonia intracellularis in Pigs
Nag-Jin Choi,Byoung-Yong Park,Chul Park,Young-Jun Kim,Ho-Seong Cho
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.4258.4262
Abstract: A colorimetric Loop-mediated isothermal Amplification (LAMP) assay with hydroxy naphthol blue was designed for the detection of Lawsonia (L.) intracellularis which is an important pathogenic bacteria that causes animal diseases. A set of six primers was designed to target the aspartate ammonia-lyase (aspA) gene. Serial 10 fold dilutions of cultured L. intracellularis and spiked feces were used for LAMP optimization. The lower limit of the linear range of the assay in L. intracellularis was 101 L. intracellularis which is ten times more sensitive than conventional PCR. Based on testing in 210 porcine fecal samples using LAMP and conventional PCR, the agreement quotients between LAMP and conventional PCR was 0.92. These results suggest that colorimetric LAMP is a simple method for L. intracellularis detection in porcine fecal samples.
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