• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.8
• /
• pp.1521-1531
• /
• 2015

According to the service attributes, D2D communications establish 1-1, or 1-n channels and require the differentiated device discovery technology. This paper proposes a sector-based device discovery mechanism for 1-n D2D communication scenario in LTE-Advanced networks that a disaster happened. Our proposal is a mechanism that can extend the coverage in a disaster situation which a number of devices(survivors) need to be discovered in a short time. In the single cell environment, a larger discovery coverage can be obtained, and in the multi-cell, it is possible to mitigate the interference with adjacent links due to sector-based coverage control. Through a set of simulations, we have confirmed that our proposal has better performance in the number of devices discovered and the interference than the legacy broadcast device discover mechanism.

• Journal of Communications and Networks
• /
• v.18 no.3
• /
• pp.476-483
• /
• 2016

Super Wi-Fi is a Wi-Fi-like service exploiting TV white space (WS) which is expected to achieve larger coverage than today's Wi-Fi thanks to its superior propagation characteristics. Super Wi-Fi has been materialized as an international standard, IEEE 802.11af, targeting indoor and outdoor applications, and is undergoing worldwide field tests. This paper demonstrates the true potential of indoor Super Wi-Fi, by experimentally comparing the signal propagation characteristics of Super Wi-Fi and Wi-Fi in the same indoor environment. Specifically, we measured the wall and floor attenuation factors and the path-loss distribution at 770MHz, 2.401 GHz, and 5.540 GHz, and predicted the downlink capacity of Wi-Fi and Super Wi-Fi. The experimental results have revealed that TVWS signals can penetrate up to two floors above and below, whereas Wi-Fi signals experience significant path loss even through a single floor. It has been also shown that Super Wi-Fi mitigates shaded regions of Wi-Fi by providing almost-homogeneous data rates within its coverage, performs comparable to Wi-Fi utilizing less bandwidth, and always achieves better spectral efficiency than Wi-Fi. The observed phenomena imply that Super Wi-Fi is suitable for indoor applications and has the potential of extending horizontal and vertical coverage of today's Wi-Fi.

• Journal of Korean Vacuum Science & Technology
• /
• v.6 no.2
• /
• pp.79-83
• /
• 2002

As Ag does not form my silicide on Si surfaces, Ag wire is a candidate for self-assembled nanowire on the reconstructed and single-domain Si(5 5 12)-2 $\times$ 1. In the present study, various Ag coverages and post-annealing temperatures had been tested to fabricate a Ag nanowire with high aspect ratio. When Ag coverage was less than 0.03 ML and the post-annealing temperature was 500(C, Ag atoms preferentially adsorbed on the tetramer sites resulting in Ag wires with an inter-row spacing of ~5 nm. However, its aspect ratio is relatively small and its height is also not even. On the other hand, the Ag-posited surface completely loses its reconstruction even with the same annealing at 500 $\^{C}$ if the initial coverage exceeds 0.05 ML. But the additional subsequent annealing at 700$\^{C}$ and slow-cooling process recovers the well-ordered Ag chain with relatively high aspect ratio on the same tetramer sites. It can be understood that, in the double step annealing process, the lower temperature annealing is required for cohesion of adsorbed Ag atoms and the higher temperature annealing is for providing Ag atoms to the tetramer sites.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.230-230
• /
• 2012

Graphene have showed promising performance as electrodes of organic devices such as organic transistors, light-emitting diodes, and photovoltaic solar cells. In particular, among various organic materials of graphene-based organic devices, pentacene has been regarded as one of the promising organic material because of its high mobility, chemical stability. In the bottom-contact device configuration generally used as graphene based pentacene devices, the morphology of the organic semiconductors at the interface between a channel and electrode is crucial to efficient charge transport from the electrode to the channel. For the high quality morphology, understanding of initial stages of pentacene growth is essential. In this study, we investigate self-assembly of pentacene molecules on graphene formed on a 6H-SiC (0001) substrate by scanning tunneling microscopy. At sub-monolayer coverage, adsorption of pentacene molecules on epitaxial graphene is affected by $6{\times}6$ pattern originates from the underlying buffer layer. And the orientation of pentacene in the ordered structure is aligned with the zigzag direction of the edge structure of single layer graphene. As coverage increased, intermolecular interactions become stronger than molecule-substrate interaction. As a result, herringbone structures the consequence of higher intermolecular interaction are observed.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.32.2-32.2
• /
• 2010

The Korean Solar Radio Burst Locator (KSRBL) is a single dish radio spectrograph, which is designed to record the spectra of microwave (0.5 - 18 GHz) bursts with 1 MHz spectral resolution and 1 s time cadence, and locate their positions on the solar disk within 2 arcmin. It was installed at KASI in 2009 August, and operational thereafter. The antenna pointing coefficients were initially determined during the installation and refined later using a series of antenna pointing calibrations. The filter to prevent the radio frequency interference around 2 GHz was designed and is to be installed. After the installation, the full frequency coverage will be recovered from the temporarily restricted frequency coverage (5 - 14 GHz). Also an effort to solve a couple of minor problems for the full performance of the system is in progress.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.3
• /
• pp.395-399
• /
• 2002

The voltammetric behavior of spontaneously adsorbing Mo layers on Pt(111) and Pt(100) electrodes has been studied to estimate the number of electrons involved in the electrochemical processes of spontaneously adsorbed Mo and the number of the bloc ked Pt sites for hydrogen adsorption. On Pt(111) and Pt(100) surfaces, the spontaneously adsorbed Mo layers showed redox peaks at 0.10 V and 0.15 V, respectively, and continuous current-potential waves in the conventional hydrogen region. Since the potential range of the Mo redox processes on both surfaces overlapped partially with the potential range of hydrogen adsorption, the variation in the ratio of the total charge of Mo and H ($Q_H$ +$Q_{MO}$) to the hydrogen charge of clean Pt electrode ($Q_H^0$) was analyzed. From the analysis, six electrons were estimated to be involved in the electrochemical processes of the spontaneously adsorbed Mo, and four Pt sites for hydrogen adsorption were calculated to be blocked by one adsorbed Mo atom. Based on these figures and the pH dependence of the Mo redox processes, we have proposed an electrochemical equation for the spontaneously adsorbed Mo. This electrochemical equation led us to conclude that the saturation coverage of the spontaneously adsorbed Mo is 0.25. The coverage of Mo less than 0.25, however, could not be determined voltammetrically due to the convolution of the charges of Mo and H.

• Health Policy and Management
• /
• v.10 no.1
• /
• pp.57-94
• /
• 2000

Korea's social health insurance system was introduced in 1977, which has made a universal coverage possibly by July 1989. Korean government had pursued a single objective for the last decade to put the whole population under the coverage of medical security, and the objective was achieved within 12 years. The rapid accomplishment is primarily due to such factors as limited benefits, high copayment rate, low contributions as well as rapid economic growth. There are several sources of pressure for the implementation of social health insurance such as health professional group, labor unions, politicians, international organizations etc.. However it is important to look at the feasibility of social health insurance. Among other things, it is necessary to identify the administrative infrastructure of insurance system and to assess income for source of fund. As many developed countries, Korea began to apply health insurance to the employees of the large firms, and the expansion based on employment status. Thus the several funds system was inevitable according to the gradual expansion strategy. However many persons had criticized several funds system in respect with equity and efficiency aspects. In the short history of the Korean health insurance, whether one fund or sever or funds had been the most controversial issue. In Febrary 1999, the National Assembly passed the act of one fund system. From July 2000 separate funds will be unifed under new health insurance scheme. In this study we will analyze the policy making process on implementation, expansion and integration of health insurance system of Korea. And also analyse problems related to policy making.

• Genomics & Informatics
• /
• v.12 no.2
• /
• pp.50-57
• /
• 2014

We present a new next-generation sequencing-based method to identify somatic mutations of lung cancer. It is a comprehensive mutation profiling protocol to detect somatic mutations in 30 genes found frequently in lung adenocarcinoma. The total length of the target regions is 107 kb, and a capture assay was designed to cover 99% of it. This method exhibited about 97% mean coverage at $30{\times}$ sequencing depth and 42% average specificity when sequencing of more than 3.25 Gb was carried out for the normal sample. We discovered 513 variations from targeted exome sequencing of lung cancer cells, which is 3.9-fold higher than in the normal sample. The variations in cancer cells included previously reported somatic mutations in the COSMIC database, such as variations in TP53, KRAS, and STK11 of sample H-23 and in EGFR of sample H-1650, especially with more than $1,000{\times}$ coverage. Among the somatic mutations, up to 91% of single nucleotide polymorphisms from the two cancer samples were validated by DNA microarray-based genotyping. Our results demonstrated the feasibility of high-throughput mutation profiling with lung adenocarcinoma samples, and the profiling method can be used as a robust and effective protocol for somatic variant screening.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.7
• /
• pp.86-94
• /
• 1998

The rosette-scan seeker is a device mounted on the infrared guided missile. It offers the positions and iamges of target to missiles servo system by scanning a space about target in rosette pattern with a single detector. An instantaneous field of view (IFOV), which is a diameter of a detector moving along the path of the rosette pattern, has the property that its smaller size provide the less interference of background signals and detector noise. If its size is too small to voer the total field of view (TFOV), however, it produces the invisible regions in the TFOV. In this case, the invisible regions cause the performance of the seeker to deteriorate. For full scan-coverage, it is necessary to design the small IFOV without the invisible regions in the TFOV, as possible. In this paper, we propose the new method of designing the smaller IFOV than the conventional method and verify full coverage of the scanned region. By comparing the nose equivalent flux density (NEFD) of the proposed method with the that of the conventional one, we confirm that the former is better than the latter in terms of performance.

• Health Policy and Management
• /
• v.7 no.2
• /
• pp.109-146
• /
• 1997

This study explores the feasibility of activating private health insurance in Korea. The rationale for expanding private supplementary health insurance can be found in many cases of health care reforms in the European countries. Private health insurance can not only relieve the financial distress of the government health insurance programs but also offer the medical institutions incentives to improve the quality of medical care. In Korea there is no supplementary health insurance that reimburses for various kinds of diseases based on a well designed fee schedule. Recently, the cancer insurance is the best seller in the health related insurance market. As observed in the U. S. case, the cancer insurance which pays the predetermined amount (indemnity coverage) regardless of the medical charges incurred to the patient is limited in its coverage for the insured. To provide better protection against catastrophic diseases, the government should give insurance companies incentives to develop health insurance products that cover multiple diseases rather than a single disease. Consumers can hardly understand and compare complex insurance products. To resolve the information asymmetries, the government should publish a consumer report that compare various health insurance products in a user friendly way. In the long run, insurance companies will plan to sell health insurance products that charge risk related premium only when insurers accumulate the underwriting know-hows, the government shares data on various health statistics including claims and demographics, and risk pool for high risk patients is well established and subsidized by the government.