• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.6 no.4
• /
• pp.262-266
• /
• 2013

In OFDM system, cyclic prefix (CP) is used to eliminate the inersymbol interference that is caused by the channel dispersion. However, a long CP reduces the data transmission rate. An alternative to a logn CP is the a time domain channel shortening filter at the receiver that shortens the effective channel, thus a short CP is used in spite of a long channel impulse response. In the paper, we compare a various channel shortening techniques; minimum shortened signal to noise ratio (MSSNR), minimum interblock interference (min-IBI), and minimum ISI (min-ISI).

• Korean Journal of Ecology and Environment
• /
• v.40 no.3
• /
• pp.403-411
• /
• 2007

The purpose of the study was to evaluate fish community, based on conventional at Shannon-Weaver diversity index (H'), and ecological health, based on the Index of Biological Integrity (IBI) using fish assemblage in the eight sites of Nakdong River during June${\sim}$August 1999. Total number of species sampled was 19 species, and two sensitive species of Zacco temminckii (51%) and Rhynchocypris oxycephalus (28%) dominated the fish community. Also, trophic guild analyses showed that insectivore was 87% of the total and omnivore was rare, indicating that the ecological health is well maintained in the system. The pattern of spatial variation in the diversity index(H') was very similar to patterns of the species number and individual number, whereas the pattern of H' was not matched with the tolerance and trophic guild data. The diversity index (H') showed highest (1.56) in Site 6 where the proportion of sensitive species and tolerant species was minimum and maximum, respectively, and where the insectivore and omnivore were minimum and maximum. In other words, the diversity index was not matched at all with the trophic and tolerant guilds, indicating that the conventional index did not reflect the ecological characteristics of fish community in the system. In the mean time, the ecological health (IBI) averaged 33.5 (n=8), indicating "good${\sim}$fair condition" and the IBI values matched with trophic and tolerance guilds. Maximum IBI occurred in Site 2 where the sensitive and msectivore species were nearly maximum, and the tolerant and omnivore species were almost minima, indicating that IBI values were closely associated with the ecological functions and health conditions. Overall data suggest that the conventional diversity index may not effective for a evaluation of fish community, and that in contrast the IBI approach may be a useful tool for diagnosis of stream community.

• Korean Journal of Environmental Biology
• /
• v.19 no.4
• /
• pp.261-269
• /
• 2001

The purpose of present study was to introduce a multimetric approach, so called the Index of Biological Integrity (IBI) as a tool for evaluations of water environments. We used 11 metric systems for the IBI to evaluate stream conditions, based on the fish community, and modified 5 original metric attributes suggested by Karr (1981). Overall IBI values in Kap Stream averaged 36 (n = 5) and ranged 17${\sim}$49, indicating a 'fair condition' according to the modified criteria of Karr (1981) and U.S. EPA (1993). However, there were distinct differences in the IBI values among 5 study sites. The IBI values at sites 1, 2, and 3 were 49, 45, and 41, which indicated 'good${\sim}$excellent', 'good', and 'fair' condition, respectively, while values at sites 4 and 5 were 17 and 29, which indicated 'very poor' and 'poor', respectively. The minimum IBI at site 4 was probably due to continuous inputs of wastewater from wastewater disposal plants. The condition at site 4 resulted in predominance of tolerant species (50%), omnivore species (50%), and high abnormalies (43%). In the mean time, the IBI value at site 5, located near 5km downstream from the site 4, increased compared to that of site 4, and this seemed to be a result of recovery of water quality as the polluted water goes downward. We believe that present bioassessment methodology of IBI applied in this study may be used as a key tool to set up specific goals for stream restoration plans and dentify recovery levels of lotic ecosystems after restoration activities(i.e., prevention of point-source pollutant input, restoration of physical habitats, construction of riparian vegetation) as well as a biological measure diagnosing current stream conditions.

• Korean Journal of Ecology and Environment
• /
• v.40 no.4
• /
• pp.527-536
• /
• 2007

In this study, we applied 10-metric health assessment model, based on the Index of Biological Integrity (IBI) during 2006 in the Changwon Stream, which is located in the Changwon city, Gyeongnam province, S. Korea, and then compared with water quality data. The Index of Biological Integrity (IBI) in the Changwon Stream varied from 18 to 38 in the watershed depending on the sampling location and averaged 30.3 (n=6) during the study. Analysis of tolerance guilds showed that the proportion of sensitive species was 13%, but tolerant and intermediate species were 34% and 53%, respectively. Qualitative Habitat Evaluation Index (QHEI) averaged 43.3 (range: 65-104, n=6) indicating non-supporting condition, based on the criteria of U.S. EPA (1993). Values of QHEI showed a typical longitudinal decreases from the headwater reach to the downstream location, except for Site 1 with a low QHEI value by artificial habitat by concrete construction. Minimum QHEI was found in Site 4 where fish diversity was minimal. Conductivity increased continuously along the gradients and especially showed abrupt increases in the downstream sites along with turbidity. Stream ecosystem health of IBI matched to the values of QHEI except for S6. Low IBI values in the sites 4 and 5 was considered to be a result of combined effects of chemical pollutions and habitat degradations. Our results support the hypotheses of Plafkin et ai. (1989) that physical habitat quality directly influences the trophic structure and species richness, and is closely associated with IBI values.

• Korean Journal of Environmental Biology
• /
• v.31 no.2
• /
• pp.96-104
• /
• 2013

The objectives of this study were to analyze chemical the water quality related to the fish community and to evaluate the ecosystem health based on the faunal composition and guild structure in 2007 in Baekma River. Mean concentrations of biological oxygen demand (BOD) and chemical oxygen demand (COD) were 2.8 and $4.0mg\;L^{-1}$, respectively and total nitrogen (TN) and total phosphorus (TP) were $5.0mg\;L^{-1}$ and $158{\mu}g\;L^{-1}$, which is indicating that the river is in an eutrophic state. Especially, organic pollution and eutrophication occurred in the downstream reach of Baekma River. A total of 19 fish species were collected during the study and the most dominant species was Opsariichthys uncirostris amurensis accounted 48% of the total abundances. The proportion of sensitive species was low (2.3%), compared with that of tolerant species (71.8%). These results suggest that tolerant species and the biotic quality of the fish community was severely degraded. According to the multi-metric model, the Index of Biological Integrity (IBI), the mean model value of the fish community in Baekma River was estimated as 14.8 indicating a "poor" condition. The minimum values of the IBI were observed in the downstreams, and this was mainly attributed to chemical pollutions of nutrients (N, P) and organic matters.

• Progress in Superconductivity and Cryogenics
• /
• v.16 no.2
• /
• pp.1-6
• /
• 2014

The five-year national project in Japan for R&D of coated conductors and applications, named as the Materials and Power Applications of Coated Conductors (M-PACC) project, was finished at the end of FY2013. The project consists of four sub-themes as cable, transformer, SMES and coated conductors. In the theme of coated conductors, the fabrication process had been developed to satisfy the requirements from the applications such as in-field $I_c$ performance, low AC loss in the long tapes etc. Through the project, the remarkable progress was achieved as follows; a high in-field minimum $I_c$ value over 54A/cm-width under 3T at 77K was realized in a 200m long EuBCO tape with artificial pinning centers of $BaHfO_3$ by the pulsed laser deposition (PLD) technique on the IBAD template. On the other hand, the AC loss reduction was confirmed in the tapes fabricated by both PLD and the metal organic deposition (MOD) techniques by scribing 100m tapes into 10-filamments. Additionally, the mechanism of the delamination phenomenon was systematically investigated and the strength was improved by eliminating the origins of the weak points in the films. Through the development, all targeted goals were accomplished and the several results were appreciated as a world champion data.