• Journal of the Korean Vacuum Society
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• v.14 no.4
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• pp.207-214
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• 2005

This paper presents a channel structure for promising high performance pseudomorphic high electron mobility transistor(pHEMT) switching device for design and fabricating of microwave control circuits, such as switches, phase shifters, attenuators, limiters, for application in personal mobile communication systems. Using the designed epitaxial channel layer structure and ETRI's $0.5\mu$m pHEMT switch process, single pole double throw (SPDT) Tx/Rx monolithic microwave integrated circuit (MMIC) switch was fabricated for 2.4 GHz and 5 GHz band wireless local area network (WLAN) systems. The SPDT switch exhibits a low insertion loss of 0.849 dB, high isolation of 32.638 dB, return loss of 11.006 dB, power transfer capability of 25dBm, and 3rd order intercept point of 42dBm at frequency of 5.8GHz and control voltage of 0/-3V These performances are enough for an application to 5 GHz band WLAN systems.

• Journal of IKEEE
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• v.23 no.1
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• pp.280-288
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• 2019

In the CR-enabled MANET, routing paths can be easily destroyed due to node mobility and channel unavailability (due to the emergence of the PU of a channel), resulting in significant overhead to maintain/recover the routing path. In this paper, network caching is actively used for route maintenance, taking into account the properties of the CR. In the proposed scheme, even if a node detects that a path becomes unavailable, it does not generate control messages to establish an alternative path. Instead, the node stores the packets in its local cache and 1) waits for a certain amount of time for the PU to disappear; 2) waits for a little longer while overhearing messages from other flow; 3) after that, the node applies local route recovery process or delay tolerant forwarding strategy. According to the simulation study using the OPNET simulator, it is shown that the proposed scheme successfully reduces the amount of control messages for path recovery and the service latency for the time-sensitive traffic by 13.8% and 45.4%, respectively, compared to the existing scheme. Nevertheless, the delivery ratio of the time-insensitive traffic is improved 14.5% in the proposed scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.291-298
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• 2021

In this study, the future of countermobility capability is presented by analyzing the status of the countermobility obstacles focusing on the history of landmines and munitions. The conventional landmine was forbidden globally by the CCW and Ottawa Treaty because it caused civilian damage after the war. Because the inhumanity of those mines had been acknowledged, shatterable mines with a self-destruct (SD) function and M93 "HORNET" anti-tank munition with enhanced sensors have been fielded. In 2016, the Obama administration announced a policy that banned all antipersonnel landmines, leaving a considerable gap in the countermobility capability. To deal with these problems, the developments of "SAVO" and the SLEP program of Volcano mines were conducted. In the sense of a long-term approach, the countermobility obstacles, including mines, were chosen as fundamental forces for Multi-Domain Operations and were improved to Terrain Shaping Obstacles (TSO). TSO has improved sensors and mobility kill capabilities and features an enhanced remote control over each munition on the battlefield through a network established with satellite communication. The combined arms countermobility might be fully capable until 2050 if the TSO program can be completed successfully.

• The Journal of Korean Philosophical History
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• no.29
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• pp.179-202
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• 2010

In addition to the emphasis on filial piety ethics in everyday life, filial piety obtained a further significance in Confucianism which had the strong sense of ancestor worship. This paper focuses on filial piety as a mechanism of continuity within Confucianism and points out that it owed its development to its connection to agricultural culture. The sedentary life with less mobility forged a relative intimacy among people and filial piety was the actual expression of that kind of intimate affection. Yet, filial piety in Confucianism created a unique culture in terms that it not only stipulated material and emotional support for parents but also expected one's piety to the further ancestors through a memorial service and made its connection to the infinite posterity through sons. From the perspective of Confucianism that established filial piety at the turning point from life to death, the self existing in present was not an isolated self anymore. Yet, one can see another characteristic of Confucianism from that filial piety, based on blood bonds, could move beyond paternalism to broaden itself. It could be expanded to the care for strangers. The aged experience and wisdom through agricultural life begot the insight that the nature made its infinite connections with everything through circulation. As a stone thrown in a pond would enlarge its boundary by drawing larger and larger concentric circles, this thought enabled people to enlarge their affection to their parents to universal humanity. In this enlarged network, though it was natural to make distinctions between the closer and the farther, Confucianism sought to overcome it by establishing oneself upright. Confucianism emphasized the moral cultivation with its filial piety concept that contained the diachronic thought penetrating life and death and the broadened perspective relating everything around. In Confucianism, filial piety provided an important medium in forming a moral subject that penetrated life and death and related self and others. Inherent in it is the Confucius thought of continuity that searched for a paragon of a moral human being regardless of time and space.

• Journal of Ecology and Environment
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• v.48 no.1
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• pp.32-48
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• 2024

Background: Longitudinal connectivity in river systems strongly affects biological components related to ecosystem functioning, thereby playing an important role in shaping local biodiversity and ecosystem health. Environmental DNA (eDNA)-based metabarcoding has an advantage of enabling to sensitively diagnose the presence/absence of species, becoming an efficient/effective approach for studying the community structure of ecosystems. However, little attention has been paid to eDNA-based biomonitoring for river systems, particularly for assessing the river longitudinal connectivity. In this study, by using eDNA we analyzed and compared species diversity and composition among artificial barriers to assess the longitudinal connectivity of the fish community along down-, mid- and upstream in the Hotancheon from the Geum River basin. Moreover, we investigated temporal variation in eDNA fish community structure and species diversity according to season. Results: The results of species detected between eDNA and conventional surveys revealed higher sensitivity for eDNA and 61% of species (23/38) detected in both methods. The results showed that eDNA-based fish community structure differs from down-, mid- and upstream, and species diversity decreased from down to upstream regardless of season. We found that there was generally higher species diversity at the study sites in spring (a total number of species across the sites [n] = 29) than in autumn (n = 27). Nonmetric multidimensional scaling and heatmap analyses further suggest that there was a tendency for community clusters to form in the down-, mid- and upstream, and seasonal variation in the community structure also existed for the sites. Dominant species in the Hotancheon was Rhynchocypris oxycephalus (26.07%) regardless of season, and subdominant species was Nipponocypris koreanus (16.50%) in spring and Odontobutis platycephala (15.73%) in autumn. Artificial barriers appeared to negatively affect the connectivity of some fish species of high mobility. Conclusions: This study attempts to establish a biological monitoring system by highlighting the versatility and power of eDNA metabarcoding in monitoring native fish community and further evaluating the longitudinal connectivity of river ecosystems. The results of this study suggest that eDNA can be applied to identify fish community structure and species diversity in river systems, although some shortcomings remain still need to be resolved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.4
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• pp.527-536
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• 2022

The purpose of this study is to predict changing traffic environments and related economic effects by reflecting the changed KTDB and socio-economic indicators pertaining to Mulgeum station, a general railway stop, when it is confirmed as a KTX stop. To analyze the data of this study, socioeconomic indicators and the general status of transportation facility operations were investigated with reference to related statistical data, centered on the country overall and on Yangsan city in particular. In addition, we investigated and referenced the railroad facility construction plan and train operation plan, which are national high-level plans related to land development and transportation network construction. Currently, there are only ITX trains (4 times/day) and Mugunghwa trains (29 times/day) that stop at Mulgeum station in Yangsan, meaning that passengers cannot use KTX trains in the Yangsan area. In particular, the need for a KTX stop at Mulgeum station has been continuously raised because train users in the Yangsan area have inconvenient transportation in that they must travel 40 minutes to Ulsan station or 30 minutes to Gupo station to use the KTX. As a result of analyzing railroad transportation demand that will change in the future as the KTX stop at Mulgeum station is confirmed, the number of passengers boarding and arriving at Mulgeum station is predicted to be 1,674 passengers/day by 2025. In addition, the numbers of train passengers that are converted from Ulsan and Gupo stations due to the stop at Mulgeum station are predicted to be 594 passengers/day boarding and 562 passengers/day arriving by 2025. In the future, if Yangsan citizens use the KTX Mulgeum station, the access time to Mulgeum station can be shortened to 22 minutes from 65 minutes, and it is predicted that the inconvenience of transferring between railroads will be resolved, with the waiting time for transfers reduced by up to a maximum of 40 minutes. Therefore, the economic effect of creating a KTX stop at Mulgeum station was analyzed to be B/C=1.823 when general railroad operating costs are not taken into account and B/C=2.127 when general railroad operating costs are considered. In conclusion, when using KTX trains to visit the Seoul Metropolitan Area, it takes 2 hours and 43 minutes to use Mulgeum station without using Ulsan station or Gupo station, which is considered to be very effective for reducing travel times and improving the economic feasibility of this development; it is also expected that Yangsan city will be able to improve accessibility and mobility to the Seoul Metropolitan Area by breaking free from the disgrace of being a remote location given its link to KTX in the future.