• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6B
• /
• pp.1165-1173
• /
• 1999

In order to support various multimedia communication services, a well balanced backbone network should be designed using recently advanced optical communication technologies. In this paper an optimal backbone network configuration design is presented fur Korean traffic environment. A new traffic model, Population-Distance-Gross Group Products(PDG) traffic model, is devised. In Korean network traffic environment, six regional centers are selected, link capacities between the regional centers are estimated from the PDG traffic model, and the overall network configuration is designed for the all-optical backbone network in Korea. A simulation study is carried out to verify the desired performance of the designed backbone network. Simulation results show that performance of the backbone network is well balanced to support various communication services in Korea in the 2000s.

• Journal of Korean Ophthalmic Optics Society
• /
• v.3 no.1
• /
• pp.9-13
• /
• 1998

Visual system of Korean Salamander(Hynobius leechi) was morphologically studied. Fertilized eggs in egg sacs were collected and were developed in sterile saline solution. Various sized larvae of 5-30mm in length were fixed. Specimens were paraffin sectioned and were observed under light microscope. In 5mm length larva, lens rudiment induced by optic cup was combined with sensory ectoderm. The shape of lens was changed as spherical in 12mm length larva, but the retinal layer did not differentiated into three layers. The differentiation of retinal layer was clear in 14-16mm length larva. The central region of lens fibers was degenerated. Iris and ciliary body were formed from the marginal zone of optic cup in 20mm length larva. Choroid was thicker in elder eye of 30mm length larva and cartilage developed at outer region of optic cup. The outer segment of photoreceptor cell layer grew longitudinally. Optic nerve was connected to the ventral part of brain through cartilage.

• Journal of the Korea Computer Industry Society
• /
• v.2 no.10
• /
• pp.1269-1284
• /
• 2001

The Secure Sockets Layer is a protocol for encryption TCP/IP traffic that provides confidentiality, authentication and data integrity. Also the SSL is intended to provide the widely applicable connection-oriented mechanism which is applicable for various application-layer, for Internet client/server communication security. SSL, designed by Netscape is supported by all clients' browsers and server supporting security services. Now the version of SSL is 3.0. The first official TLS vl.0 specification was released by IETF Transport Layer Security working group in January 1999. As the version of SSL has had upgraded, a lot of vulnerabilities were revealed. SSL and TLS generate the private key with parameters exchange method in handshake protocol, a lot of attacks may be caused on this exchange mechanism, also the same thing may be come about in record protocol. In this paper, we analyze SSL protocol, compare the difference between TLS and SSL protocol, and suggest what developers should pay attention to implementation.

• Proceedings of the Korea Contents Association Conference
• /
• 2007.11a
• /
• pp.586-588
• /
• 2007

The Moore's law states that the number of transistors on a chip doubles about every 18 months. And it was reported that the network speed has been doubled about every 9 months. This indicates that computing power and network is no longer the obstacles for the high performance applications requiring terabits networks. We believe that the application motivates the network and vice versa. This presentation will introduce the GLORIAD which is the first ring network connecting six countries around the world and provides scientists with advanced networking tools that improve a communications and data exchange. The GLORIAD trans-Pacific link started its service on August 1, 2005. Since then, there has been remarkable demonstrations were performed through major conferences like Supercomputing Conference. This paper will introduce the global collaborative works on demonstrations of VMT, high energy physics, SDSS and HD video transmission during SC'06 in Tampa, FL.

• Journal of Satellite, Information and Communications
• /
• v.12 no.1
• /
• pp.88-93
• /
• 2017

Policy maker inevitably faces two restraints once they attempt to accomplish $4^{th}$ Industrial Revolution through development of Industrial Internet of Things(i.e. IIoT). One is to construct physical network by substituting old equipment and infrastructure into smart equipment and the other is to connect the physical network into national telecommunications infrastructure. Australia, as she proceeds National Broadband Network programme, has assembled all medium of telecommunications to provide every Australian premises regardless to its physical location by creating wholes-sale only carrier, NBN co. At the same time, Australian government also provides its own IIoT policy; Co-development and New-Development projects. Meanwhile, NBN co. has launched its own two communication satellites in 2015 and 2016 to replace the old satellite communication services depended on the other companies' satellites. This article, in the end, analyses the role of satellite communication in $4^{th}$ industrial revolution with case study on Australian policy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.683-686
• /
• 2018

Autonomous vehicles are the 4th industrial revolution that utilizes artificial intelligence(AI) and superconducting technology, and is a world-wide investment and research project. However, a Uber vehicle under test in Arizona, USA, was accidentally killed by pedestrians crossing the road in the dark night, and accidents occurred when the Tesla vehicle was exposedto the backlightof the sun. These problems were caused by misunderstandings and choice about sensors mounted on autonomous vehicles due to bad weather such as snow, rain, and sunlight. In this paper, we analyze the composition of the autonomous vehicle and the cause of the accident, and consider the criteria that should be judged in case of emergency in which human accidents may occur. This paper analyzes the composition of autonomous vehicles and causes of accidents, and considers the criteria that should be choice in an emergency where an accident may occur.

• Korean Chemical Engineering Research
• /
• v.44 no.3
• /
• pp.254-258
• /
• 2006

Zeolites with excellent adsorption capacity of volatile organic compounds were attached onto inorganic fibers which were the raw materials of honeycomb-type adsorbers. The amounts of zeolite particles attached onto the fibers considerably increased by treating them with hydrochloric acid, sulfuric acid, or hydrofluoric acid. Various functional groups such as chloropropyl, aminopropyl and epoxy groups of silane compounds, and amine groups of polyethylenimine were employed as covalent linkage materials between the fibers and zeolite particles. The state of the fibers coated with zeolite particles was examined by scanning electron microscopy, and the amounts of zeolite particles bound to the fibers were estimated from their BET surface areas. The largest amount was obtained when polyethylenimine was employed as a linkage material. Polyethylenimine was the most effective for attaching zeolite particles onto the inorganic fibers among various linkers employed.

• Korean Journal of Optics and Photonics
• /
• v.19 no.2
• /
• pp.122-126
• /
• 2008

Dual backlight unit incorporating a single light source integrated with a beam splitting reflector was demonstrated, providing a surface light beam for both the keypad and the display section simultaneously. The reflector was realized by aligning a groove substrate with a matching cover, and a light guiding module comprising a stack of light guide panels and prism/diffuser sheets was attached to both sides of the reflector. A light emanating from the light source-placed in the middle of the substrate-undergoes a series of reflections through the reflector to reach the input of the light guiding module. Then it is transformed into a surface light beam, which is used to irradiate the keypad and display sections simultaneously. As for the accomplished dual surface light sources, the measured average luminance and the spatial luminance uniformity were respectively about $420\;cd/m^2$ and 69% for the keypad section, and $640\;cd/m^2$ and 79% for the display section.

• Journal of IKEEE
• /
• v.21 no.2
• /
• pp.105-114
• /
• 2017

This paper proposes a design method of an LCL-filter for grid-tied three-level inverter systems. The demand for three-phase PWM inverters in applications such as wind or solar power generation systems has been increase in recent years. To reduce harmonic components caused by switching operation, such inverters are connected to the grid via an LCL filter. Although there are research results for designing LCL-filter, the modulation method should be fully considered to make the filter perform desired cancellation ability with minimized size. This paper presents the design methodology for an LCL-filter that is optimized for SVM switching operations. The simulation and experimental results verify the validity of the LCL-filter designed with proposed method in this paper.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.11
• /
• pp.1689-1700
• /
• 1993

WDM(Wavelength Division Multiplexing) based-on fixed wavelengths is a new means of utilizing the bandwidth of optical fibers. In this Paper, an improved virtual topology called "(a, $\beta$,${\gamma}$) ShuffleNet " is introdced for designing large-scale WDM switches. The proposed one is an architecture created by vertically stacking x planes of a ($\beta$,${\gamma}$) ShuffleNet in parallel via $\beta$r nodes called "bridge nodes" so that N-by-N(N=(x*$\beta$${\gamma}$*${\gamma}$) switching is achieved based on the self-routing algorithm for each ($\beta$,${\gamma}$) ShuffleNet. With the topological parallelism, in contrast to the conventional virtual topologies, the diameter of 2${\gamma}$ hops can be fixed and high utilization and performance are provided while N increases. Such a scalability characteristic allows to design a growable broadband switch. As for the delay, we show that the traffic locality, due to the topological feature. result in low delay characteristics.lay characteristics.