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Search Results: 1 - 10 of 29015 matches for " Ji Hyeok Yun "
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Perspective Projection Algorithm Enabling Mobile Device’s Indoor Positioning  [PDF]
Seo Woo Han, Yun Jung Lee, Ji Hyeok Yun, Chang Yong Han, Dae Ho Lee, Doug Young Suh
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.61017
Abstract:
In order to improve the user’s satisfaction with the augmented reality (AR) technology and the accuracy of the service, it is important to obtain the exact position of the user. Frequently used techniques for finding outdoors locations is the global positioning system (GPS), which is less accurate indoors. Therefore, an indoor position is measured by comparing the reception level about access point (AP) signal of wireless fidelity (Wi-Fi) or using bluetooth low energy (BLE) tags. However, Wi-Fi and Bluetooth require additional hardware installation. In this paper, the proposed method of estimating the user’s position uses an indoor image and indoor coordinate map without additional hardware installation. The indoor image has several feature points extracted from fixed objects. By matching the feature points with the feature points of the user image, we can obtain the position of the user on the Indoor map by obtaining six or more pixel coordinates from the user image and solving the solution using the perspective projection formula. The experimental results show that the user position can be obtained more accurately in the indoor environment by using only the software without additional hardware installation.
Effect of ablated hippocampal neurogenesis on the formation and extinction of contextual fear memory
Hyoung-Gon Ko, Deok-Jin Jang, Junehee Son, Chuljung Kwak, Jun-Hyeok Choi, Young-Hoon Ji, Yun-Sil Lee, Hyeon Son, Bong-Kiun Kaang
Molecular Brain , 2009, DOI: 10.1186/1756-6606-2-1
Abstract: Newborn neurons continuously incorporate into neuronal circuits during development. In the adult brain, neurogenesis occurs in the subgranular zone (SGZ) of the hippocampus and the subventricular zone (SVZ) of the lateral ventricle [1]. Newly generated neurons in the SVZ migrate to the olfactory bulb and play key roles in olfactory memory [2]. In the SGZ region, newly generated cells are differentiated into both neurons and glial cells, and the newborn neurons incorporate to the granule cell layer of the dentate gyrus [2]. A growing body of evidence supports the contribution of hippocampal newborn neurons to hippocampus-dependent memories [3-5]. It was reported that neurogenesis in the adult hippocampus is required for trace eyeblink conditioning [4]. Moreover, ablated neurogenesis impaired contextual fear conditioning, but did not impair cued fear conditioning, which is independent of the hippocampus [3,5]. These phenomena are well correlated with electrophysiological data showing reduced long-term potentiation (LTP) in the dentate gyrus owing to impaired hippocampal neurogenesis [3]. Therefore, many studies support the idea that hippocampal neurogenesis is involved in the acquisition or expression of hippocampus-dependent memories (Table 1) [3-8]. In contrast, some reports indicate that ablation of hippocampal neurogenesis has no effect on learning, even in hippocampus-dependent memory tasks such as the contextual fear memory task and the Morris water maze task (Table 1) [3-6,8,9].Recently, several reports have shown that the hippocampus is involved in the extinction of hippocampus-dependent memories [10,11]. Usually, extinction can be explained by two possible mechanisms. First, memory extinction is an active learning process [12]. Therefore, the expression of old memories can be inhibited by the increase of synaptic strength of inhibitory circuits, which can be regulated by other brain regions, including the prefrontal cortex. In case of extinction of cued fear
Development of ToSPACE for Pipe Wall Thinning Management in Nuclear Power Plants  [PDF]
Kyeong Mo Hwang, Hun Yun, Hyeok Ki Seo, Geun Young Lee, Kyung Woo Kim
World Journal of Nuclear Science and Technology (WJNST) , 2019, DOI: 10.4236/wjnst.2019.91001
Abstract: A number of piping components in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), cavitation, flashing, SPE (Solid Particle Erosion), LDIE (Liquid Droplet Impingement Erosion), etc. Those mechanisms may lead to thinning, leak, or rupture of the components. Due to the pipe ruptures caused by wall thinning in Surry unit 2 of USA in 1986 and in Mihama unit 3 of Japan in 1994, the pipe wall thinning management has emerged as one of the most important issues in nuclear power plants. To manage the pipe wall thinning in the secondary system, Korea has used a foreign program since 1996. As using the foreign country’s program for long term, it was necessary to improve from the perspective of the users. Accordingly, KEPCO-E & C has started to develop the 3D-based pipe wall thinning management program (ToSPACE, Total Solution for Piping And Component Engineering management) from eight years ago, and the development was successful. This paper describes the major functions included in ToSPACE program, such as 3D-based DB (Database) buildup, development of FAC and erosion evaluation theories, UT (Ultra-sonic Test) data reliability analysis, field connection with 3D, automatic establishment of long-term inspection plan, etc. ToSPACE program was developed to allow site engineers performing the selection of inspection quantity at each refueling outage, UT data reliability analysis, UT evaluation, determination of next inspection timing, identification of the inspecting and replacing components in 3D drawings, etc., to access easily.
Optimal surgical extent of lateral and central neck dissection for papillary thyroid carcinoma located in one lobe with clinical lateral lymph node metastasis
Keum Hyo Sub,Ji Yong Bae,Kim Jong Min,Jeong Jin Hyeok
World Journal of Surgical Oncology , 2012, DOI: 10.1186/1477-7819-10-221
Abstract: Background The indications and extent of cervical lymph node dissection in papillary thyroid carcinoma (PTC) are still being debated. The aim of this study was to analyze the patterns of cervical lymph node metastasis in the lateral and central compartment and related factors and suggest the optimal extent of lateral and central neck dissection for PTC patients with clinical lateral lymph node metastasis. Methods We retrospectively analyzed 72 patients with unilateral PTC who underwent therapeutic lateral neck dissections with concomitant total thyroidectomy and central neck dissection between January 2001 and December 2009. Results The 72 patients underwent 79 sides of therapeutic lateral neck dissection. The most frequent metastatic level in the ipsilateral lateral compartment was level IV (75.0%), followed by level III (69.4%), level II (56.9%) and level V (20.8%). Multiple level metastases were common (77.8%) and were correlated with tumor size (≥ 10 mm). The central compartment lymph node metastasis rate was 87.5%, including 26.4% of contralateral central compartment metastases. Conclusion In PTC patients with clinical lateral lymph node metastasis, the optimal extent of lateral and central neck dissection should include levels II, III, IV and V as well as the bilateral central compartment.
Intracranial hemorrhage and cerebellar infarction caused by acupuncture
Heo Jae-Hyeok,Bae Myoung-Hoon,Lee Su-Ji
Neurology India , 2011,
Abstract:
Transverse Beam Dynamics including Aberration Effects in the Thermal Wave Model using a Functional Method
Ji-ho Jang,Yong-sub Cho,Hyeok-jung Kwon
Physics , 2009, DOI: 10.1016/j.nima.2010.09.077
Abstract: We studied the transverse beam dynamics including aberration effects of sextupole and octupole perturbations in a thermal wave model. A functional integration method was used to calculate the first-order perturbation effects. We found that the model successfully explains a PARMILA simulation results for proton beams without space-charge effects in a FODO lattice.
Investigation of the transverse beam dynamics in the thermal wave model with a functional method
Ji-ho Jang,Yong-sub Cho,Hyeok-jung Kwon
Physics , 2006, DOI: 10.1016/j.physleta.2007.02.017
Abstract: We investigated the transverse beam dynamics in a thermal wave model by using a functional method. It can describe the beam optical elements separately with a kernel for a component. The method can be applied to general quadrupole magnets beyond a thin lens approximation as well as drift spaces. We found that the model can successfully describe the PARMILA simulation result through an FODO lattice structure for the Gaussian input beam without space charge effects.
Cross-Layer Explicit Link Status Notification to Improve TCP Performance in Wireless Networks
Yun Ji-Hoon
EURASIP Journal on Wireless Communications and Networking , 2009,
Abstract: To alleviate the performance degradation of conventional TCP in wireless networks, many schemes have been proposed so far. One category of such schemes is the Explicit Loss Notification (ELN) scheme in which TCP senders are notified of wireless losses so as to avoid congestion control against those losses. Thus the key design factor of the ELN scheme is how to detect wireless losses accurately and rapidly. This paper proposes a new ELN scheme, in which wireless losses are detected by monitoring the operation of the wireless link layer. By exploiting such cross-layer design, the proposed scheme can detect wireless losses without additional transmission over the wireless link and thus achieves accurate detection with minimum delay. The proposed scheme additionally sends new information, that is, Explicit Retransmission Start Notification, in order to prevent spurious timeouts of the TCP senders. Furthermore, in order to handle packet reordering and avoid successive shrinking of a congestion window due to multiple packet drops, a new TCP modification is proposed. Through intensive simulations, it is demonstrated that the proposed scheme outperforms the other ELN schemes, and yields the throughput performance of more than 400% of TCP-Reno and 150% of Snoop in the considered environments.
Cross-Layer Explicit Link Status Notification to Improve TCP Performance in Wireless Networks
Ji-Hoon Yun
EURASIP Journal on Wireless Communications and Networking , 2009, DOI: 10.1155/2009/617818
Abstract: To alleviate the performance degradation of conventional TCP in wireless networks, many schemes have been proposed so far. One category of such schemes is the Explicit Loss Notification (ELN) scheme in which TCP senders are notified of wireless losses so as to avoid congestion control against those losses. Thus the key design factor of the ELN scheme is how to detect wireless losses accurately and rapidly. This paper proposes a new ELN scheme, in which wireless losses are detected by monitoring the operation of the wireless link layer. By exploiting such cross-layer design, the proposed scheme can detect wireless losses without additional transmission over the wireless link and thus achieves accurate detection with minimum delay. The proposed scheme additionally sends new information, that is, Explicit Retransmission Start Notification, in order to prevent spurious timeouts of the TCP senders. Furthermore, in order to handle packet reordering and avoid successive shrinking of a congestion window due to multiple packet drops, a new TCP modification is proposed. Through intensive simulations, it is demonstrated that the proposed scheme outperforms the other ELN schemes, and yields the throughput performance of more than 400% of TCP-Reno and 150% of Snoop in the considered environments.
Powerful Efficacy of GCSB-5 Treatment for Improving Fatigue and Motor Function in Multiple Sclerosis (MS): A Randomized Double Blind, Place-bo-Controlled Study  [PDF]
Ji Yun Shin
Open Access Library PrePrints (OALib PrePrints) , 2016, DOI: 10.4236/oalib.preprints.1200150
Abstract:
Multiple Sclerosis (MS) is the most common disability in young adults that requires early symptomatic treatment to prevent long-term disability. Among young adults, MS is the most common central nerv-ous system (CNS) chronic inflammatory illness that is characterized by demyelination in the CNS. However, current disease-modifying treatments are not sufficiently effective for preventing the variety of symptoms during the course of disease.
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