• Proceedings of the KSME Conference
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• 2002.08a
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• pp.411-414
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• 2002

The CHFG(Critical Heat Flux in Cap) test results have been evaluated to quantify the critical powers in hemispherical narrow gaps and Park's correlation has been verified. For verification of the Park's correlation, the critical powers in hemispherical narrow gaps have been measured using water at a pressure of 0.1-0.3 WPa for the hemispherical gap thickness of 1.0mm, and the heated top diameter of 238mm The measured critical powers were compared with Park's and Monde's correlation. As a results, the Park's correlation was most accurate of other correlations, however, estimated the critical powers somewhat larger than measured ones. So, it was suggested that the diameter factor in Park's correlation should be revised.

• TTA Journal
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• s.97
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• pp.166-171
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• 2005

한국정보통신기술협회(TTA)에서 제공하고 있는 상호운용성시험(ION: Interoperability ON!)은 각 기술분야에 대해 서로 다른 회사 제품들간 상호운용성을 시험하는 행사로서 2004년 12월 7일부터 9일까지 3일 동안 IEEE802.11a+g 듀얼밴드 고속무선랜 AP(Access Point)와 카드에 대한 ION을 실시하였다. 이번 ION에서는 상호운용성과 더불어 WPA(Wi-Fi Protected Access)보안, 그리고 무선랜 제품의 RF(Radio Frequency) 적합성, AP의 성능 및 안정성에 대하여 시험하였다. 총 6개의 국내업체가 참가한 가운데 TTA 기준장비와의 상호운용성 시험, 참가업체간 상호운용성 시험을 실시하여 국내업체의 802.11a+g 듀얼모드 장비 기술수준 향상 및 앞으로 진행될 무선랜 RF 및 성능에 대한 TTA 인증 안 검토에도 많은 도움을 얻을 수 있었다.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.3
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• pp.176-187
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• 2013

Message replay, malicious Access Point (AP) associations and Denial of Service (DoS) attacks are the major threats in Wireless LANs. These threats are possible due to a lack of proper authentication and insecure message communications between wireless devices. Current wireless authentication & key exchange (AKE) schemes and security protocols (WEP, WPA and IEEE 802.11i) are not sufficient against these threats. This paper presents a novel Secure WLAN Authentication Scheme (SWAS). The scheme introduces the delegation concept of mobile authentication in WLANs, and provides mutual authentication to all parties (Wireless Station, Access Point and Authentication Server). The messages involved in the process serve both authentication and key refreshing purposes. The scheme enhances the security by protecting the messages through cryptographic techniques and reduces the DoS impact. The results showed that cryptographic techniques do not result in extra latencies in authentication. The scheme also reduces the communication cost and network overhead.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.93-98
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• 2015

This study focuses on simulation technology in the injection molding process for plastic optic lenses. The CAE program 3D TIMON was used to predict retardation, flow patterns and warpage deformation. The results were compared to the results of optic lenses as measured using the WPA-100 retardation measurement device with injection molding CAE for retardation predictions. According to the analysis and measured results, the distributions of retardation between the CAE results and the measurement results were similar. It was also confirmed that varying the injection speed had an effect on the injection pressure, warpage deformation and retardation distribution. As the injection speed increases, the injection pressure also increases and warpage deformation decreases. However, as the injection speed increases, the retardation distribution deteriorates.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.1
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• pp.38-44
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• 2021

Wi-Fi provides some low-power connection solutions that other Bluetooth cannot provide, and at the same time brings many benefits. First, there is a potentially higher data rate: it can reach 230mbps. Wi-Fi coverage is also wider than competitors, and its operating frequency is also 5GHz, which is much less congested than 2.4GHz. Finally, it also supports IP networks, which is important if you want to send data to the cloud without complexity. The 802.11ac standard of the previous generation still accounts for most shipments (80.9%) and revenue (76.2%). However, there is a limit to accepting IoT devices that will continue to increase significantly in the future. To solve this problem, the new Wi-Fi 6 standard is expected to be the solution (IEEE 802.11ax) which is quickly becoming the main driving force of the wireless local area network (WLAN) market. According to IDC market research analysts, in the first quarter of 2020, independent access points (APs) supported by Wi-Fi 6 accounted for 11.8% of shipments, but 21.8% of revenue. In this paper, we have compared and analyzed the IoT connectivity, QoS, and security requirements of devices using Wi-Fi 6 network.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.3
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• pp.57-65
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• 2018

The study is conducted to establish the National Protected Areas Integrated System(NPAIS) which includes National Protected Areas(NPAs) and other conservation measures in terms of effective ways for biodiversity conservation. Additionally, it is carried out to evaluate progress toward quantitative expansion goals in Aichi biodiversity Target 11. The NPAIS consists of NPAs and other effective area-based conservation measures(OECMs). There are two different types of OECMs. OECMs type I, including water-source protection Areas(WPA), riparian zones(RZ), fishery-resource protection zones (FPZ), and urban natural park zones(UNPZ), is a potential protected area which is recommended to be incorporated into the NPAs for effective management. OECMs type II means development restriction zones(DRZ), natural recreation forests(NRF), and buffer zones for Korea national arboretum(BKNA). As a result of evaluating the quantitative expansion goals of the NPAIS, terrestrial and inland water protected areas exceed 17% of the quantitative goal in Aichi biodiversity Target 11. The larger the area of individual OECMs and the lower the degree of overlap with NPAs, the higher the contribution of them to the terrestrial and inland water protected areas. DRZ contributes to enlarge more than 3% of quantitative expansion. And RZ and NRF contribute more than 1%. The marine protected areas are expanded by $1,425km^2$ through FPZ, but the expanded area is very small as comparing with the total marine area. It adds only 0.321% to the quantitative expansion. The rest of OECMs also has very poor quantitative expansion contributions in the marine area. Consequently, the NPAIS is effective for quantitative expansion of land areas, but not for marine areas.