An Approach to the Market Analysis of KoreaSat Services

The field of marketing research in the satellite communication services is still in the early stage of its development. Particularly, in Korean domestic satellite service market, many theoretical and methodological opportunities now exist. In this paper we develop a model, which identifies target markets and promising application services in Korean satellite communication service market. One key contribution of this paper is a modeling approach to the assessment of market potential and priorities of the application services in each Korean industry. We define and estimate the degree of attractiveness for each segmented market which represents the market potential estimated by current usage of terrestrial services and each market segment's willingness to adopt satellite technology. Since all possible satellite application services are not equally important in the market, they should be differentiated in terms of the likelihood of success. We introduce another index prioritizing application services by tying together three important factors affecting Korean satellite service demand. Some marketing implications of model results are also discussed. Finally the findings of our model are compared with those of other similar studies.     

Highly stable optical add/drop multiplexer using polarization beam splitters and fiber Bragg gratings

We demonstrate a novel wavelength-division add/drop multiplexer employing fiber Bragg gratings and polarization beam splitters. The multiplexer is easy to fabricate without any special technique such as UV trimming, and yet shows very stable performance with less than 0.3-dB crosstalk power penalty in a 0.8-nm-spaced, 2.5-Gb/s-per-channel wavelength-division multiplexing (WDM) transmission system.     

A 3.3-V single power supply 16-Mb nonvolatile virtual DRAM using aNAND flash memory technology

A 3.3-V 16-Mb nonvolatile memory having operation virtually identical to DRAM with package pin compatibility has been developed. Read and write operations are fully DRAM compatible except for a longer RAS precharge time after write. Fast random access time of 63 ns with the NAND flash memory cell is achieved by using a hierarchical row decoder scheme and a unique folded bit-line architecture which also allows bit-by-bit program verify and inhibit operation. Fast page mode with a column address access time of 21 ns is achieved by sensing and latching 4 k cells simultaneously. To allow byte alterability, nonvolatile restore operation with self-contained erase is developed. Self-contained erase is word-line based, and increased cell disturb due to the word-line based erase is relaxed by adding a boosted bit-line scheme to a conventional self-boosting technique. The device is fabricated in a 0.5-μm triple-well, p-substrate CMOS process using two-metal and three-poly interconnect layers. A resulting die size is 86.6 mm², and the effective cell size including the overhead of string select transistors is 2.0 μm²     

Impact of the location area structure on the performance ofsignaling channels in wireless cellular networks

The authors consider connection-oriented wireless cellular networks such as IS-54, IS-95, GSM, and wireless ATM networks. These are connection-oriented digital networks which employ separate radio channels for the transmission of signaling information. A forward signaling channel is a common signaling channel assigned to carry the multiplexed stream of paging and channel-allocation packets from a base station to mobile stations. For wireless ATM networks, paging and virtual-circuit (VC) allocation packets are multiplexed across the forward signaling channels as part of the VC setup phase. A reverse signaling channel, which employs a contention-oriented medium access algorithm, is used by mobile stations to send channel-request and location-update packets. A location area is a region which includes a specified set of adjacent cells; it is used to track the location of mobile stations. Mobile units must reregister as they cross the boundary of a location area. The channel setup and paging response times are critical performance factors in the design of the signaling subsystem. A location area structure must be suitably selected to ensure that acceptable levels of such performance functions are achieved. A network which employs small location-areas will experience a high rate of location updates, while larger location areas lead to higher traffic intensities of paging messages. The authors overview a method for calculating the performance behavior of signaling messages. Subsequently the impact of the location area structure on the performance of the signaling system is investigated     

A symbolic reliability of multiple path required system with three states

The system reliability of a “j or more paths required system” can be obtained from the probability that there is no minimal path suffering a short-mode failure and there is at least one set of j separate paths not suffering an open-mode failure. In order to evaluate the system reliability, we use the method of generating the sum of disjoint products, which is widely used for two-state systems. Some rules and a procedure for the minimized reliability formula are presented.     

Fixed Point Implementation of the QCELP Speech Coder

The Qualcomm code excited linear prediction (QCELP) speech coder was adopted to increase the capacity of the CDMA Mobile System (CMS). In this paper, we implemented the QCELP speech coding algorithm by using TMS320C50 fixed point DSP chip. Also the fixed point simulation was done with C language. The computation complexity of QCELP on TMS320C50 was about 33 MIPS and program size was 10k words and data memory was 4k words. In the normal call test on the CMS, where mobile to mobile call test was done in the bypass mode without double vocoding, mean opinion score for the speech quality was 3.11.     

A Temperature‐Controllable Microelectrode and Its Application to Protein Immobilization

This letter presents a smart integrated microfluidic device which can be applied to actively immobilize proteins on demand. The active component in the device is a temperature‐controllable microelectrode array with a smart polymer film, poly(N‐isopropylacrylamide) (PNIPAAm) which can be thermally switched between hydrophilic and hydrophobic states. It is integrated into a micro hot diaphragm having an integrated micro heater and temperature sensors on a 2‐micrometer‐thick silicon oxide/silicon nitride/silicon oxide (O/N/O) template. Only 36 mW is required to heat the large template area of 2 mm×16 mm to 40°C within 1 second. To relay the stimulus‐response activity to the microelectrode surface, the interface is modified with a smart polymer. For a model biomolecular affinity test, an anti‐6‐(2, 4‐dinitrophenyl) aminohexanoic acid (DNP) antibody protein immobilization on the microelectrodes is demonstrated by fluorescence patterns.     

Few‐Layered WS2 Nanoplates Confined in Co,N‐Doped Hollow Carbon Nanocages: Abundant WS2 Edges for Highly Sensitive Gas Sensors

Edges of 2D transition metal dichalcogenides (TMDs) are well known as highly reactive sites, thus researchers have attempted to maximize the edge site density of 2D TMDs. In this work, metal‐organic framework (MOF) templates are introduced to synthesize few‐layered WS₂ nanoplates (a lateral dimension of ≈10 nm) confined in Co, N‐doped hollow carbon nanocages (WS₂_Co‐N‐HCNCs), for highly sensitive NO₂ gas sensors. WS₂ precursors are assembled in the surface cavity of Co‐based zeolite imidazole framework (ZIF‐67) and subsequent pyrolysis produced WS₂_Co‐N‐HCNCs. During the pyrolysis, the carbonized ZIF‐67 are doped by Co and N elements, and the growth of WS₂ is effectively suppressed, creating few‐layered WS₂ nanoplates functionalized Co‐N‐HCNCs. The WS₂_Co‐N‐HCNCs exhibit outstanding NO₂ sensing characteristics at room temperature, in terms of response (48.2% to 5 ppm), selectivity, response and recovery speed, and detection limit (100 ppb). These results are attributed to the enhanced adsorption and desorption kinetics of NO₂ on abundant WS₂ edges, confined in the gas permeable HCNCs. This work opens up an efficient way for the facile synthesis of edge abundant few‐layered TMDs combined with porous carbon matrix via MOF templating route, for applications relying on highly active sites.     

Analyzing the Boundary Thermal Resistance of Epitaxially Grown Fe<Subscript>2</Subscript>VAl/W Layers by Picosecond Time-Domain Thermoreflectance

To gain deep insight into the mechanism of phonon scattering at grain boundaries, we investigated the boundary thermal resistance by using picosecond pulsed-laser time-domain thermoreflectance for epitaxially grown W/Fe₂VAl/W films. By using radio-frequency magnetron sputtering, we prepared a series of the three-layer films whose Fe₂VAl thickness ranged from 1 nm to 37 nm. The fine oscillation of reflectivity associated with the top W layer clearly appeared in synchrotron x-ray reflectivity measurements, indicating a less obvious mixture of elements at the boundary. The areal heat diffusion time, obtained from the time-domain thermoreflectance signal in the rear-heating front-detection configuration, reduced rapidly in samples whose Fe₂VAl layer was thinner than 15 nm. The ～ 10% mismatch in lattice constant between Fe₂VAl and W naturally produced the randomly distributed lattice stress near the boundary, causing an effective increase of boundary thermal resistance in the thick samples, but the stress became homogeneous in the thinner layers, which reduced the scattering probability of phonons.