• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1230-1232
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• 2009

본 논문에서는 공용 주파수 대역에서 IEEE 802.11 WLAN과 IEEE 802.16 WMAN과의 효율적인 공존을 위한 MAC 프로토콜을 제안한다. 제안한 프로토콜은 IEEE 802.11 WLAN과 IEEE 802.16 WMAN이 주파수를 공유하며 지리적으로 공존하는 환경을 가정하였다. IEEE 802.16 WMAN의 BS(Base station)와 SS(Subscriber station)의 통신에서 DL(Down Link)구간에서는 SS가 자신의 DL-burst에서 IEEE 802.11의 CTS를 보내 주변의 IEEE 802.11 디바이스들의 통신을 지연시킴으로써 IEEE 802.11 WLAN 및 IEEE 802.16 WMAN이 공존하면서도 충돌을 방지해 전송 효율을 높일 수 있다. 본 논문에서 제안하는 MAC 프로토콜의 동작에 대해 설명하고 시뮬레이션을 통해 기존 방법보다 향상된 성능을 유지함을 보인다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.314-321
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• 2016

Adapting the maintenance criteria of Seoul City pavement is not applicable for borough pavement due to differences between the pavement of Seoul city and the borough, such as priority of maintenance, traffic volume, thickness of pavement, and pavement deterioration rate by distresses. To develop an efficient and reasonable evaluation method of the Seocho borough pavement condition within a limited budget, this study suggested the borough pavement condition evaluation model based on the PMS (Pavement Management System) of Seoul Metropolitan SPI (Seoul Pavement Index). The SPI was modified to predict the remaining life and determine the proper maintenance method for the pavement in Seocho borough. This was suggested to reflect the rate of the designed performance life and field performance life of pavement as well as the pavement condition at the stage of the completion of construction. Primary variables, such as crack, rutting and IRI in the final model affect the overall performance life due to their even composition. Therefore, the suggested model considering the lowered criteria, design performance factor, and construction factor can be used for the more efficient maintenance of Seocho borough pavement.

• Clean Technology
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• v.23 no.4
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• pp.357-363
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• 2017

In this study, the supercritical carbon dioxide ($scCO_2$)/ n-butyl acetate (n-BA) co-solvent system was employed to remove an unexposed negative photoresist (PR) from the surface of a silicon wafer. In addition, the selectivity of the $scCO_2$/n-BA co-solvent system was confirmed for the unexposed and exposed negative PR. Optimum conditions for removal of the unexposed PR were obtained from various conditions such as pressure, temperature and n-BA ratio. The n-BA was highly soluble in $scCO_2$ without cloud point and phase separation in mostly experimental conditions. However, the $scCO_2$/n-BA co-solvent was phase separated at 100 bar, above $80^{\circ}C$. The unexposed and exposed PR was swelled in $scCO_2$ solvent at all experimental conditions. The complete removal of unexposed PR was achieved from the reaction condition of 160 bar, 10 min, $40^{\circ}C$ and 75 wt% n-BA in $scCO_2$, as measured by ellipsometry. The exposed photoresist showed high stability in the $scCO_2$/n-BA co-solvent system, which indicated that the $scCO_2$/n-BA co-solvent system has high selectivity for the PR removal in photo lithograph process. The $scCO_2$/n-BA co-solvent system not only prevent swelling of exposed PR, but also provide efficient and powful performance to removal unexposed PR.

• KNOM Review
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• v.22 no.2
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• pp.22-28
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• 2019

A Science DeMilitarized Zone (DMZ) is an optimized network technology tailored to research data nature. The Science DMZ guarantees end-to-end network performance by forming a closed research network without redundant networking and security devices for the authorized researchers. Data Transfer Node (DTN) is an essential component for the high performance and security of the Science DMZ, since only transfer functions of research data are allowed to the DTN without any security- and performance-threatening functions such as commercial internet service. Current Science DMZ requires per-user DTN server installation which turns out a scalability limitation of the networks in terms of management overhead, entry barrier of the user, and networks-wise CAPEX. In order to relax the aforementioned scalability issues, this paper suggests a centralized DTN design where end users in a group can share the centralized DTN. We evaluate the effectiveness of the suggested sharable DTN design by comparing CAPEX against to that of current design with respect to the diverse network load and the state-of-the-art computing machine.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.125-128
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• 2008

Studies for structure design has conducted in many research institutions. A basic concept of Performance-Based Design for structures was presented in seismic fields. Hereafter, Demand were defined to communicate owner's demand to designer by several research institution. Performance-Based Design is guaranteed by an accurate analysis from hazard affected to structures and from social, economical and environmental effects. It is essential to define Performance Level and Performance Objective to grasp accurate demand for structures. In this study, Performance Level and Performance Objective in ATC-40, FEMA-273 and Eurocode were defined to introduce Performance-Based Design.

• 기계와재료
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• v.25 no.3
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• pp.130-136
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• 2013

철도차량용 제동장치 성능시험기는 제륜자의 마찰계수, 마모량, 열반점 등의 물리적 성질을 실차와 유사한 환경조건에서 시험을 수행함으로써 제륜자의 연구개발 및 성능평가의 목적으로 활용한다. 제륜자는 차량의 운동에너지를 열에너지로 변환한다. 성능시험기는 철도차량의 주행 운동에너지에 해당하는 관성질량으로부터 회전 운동에너지에 해당하는 관성모멘트를 조성하여야 한다. 공용 시험기에서 각종 철도차량에 대한 관성모멘트를 기계적 관성모멘트인 플라이휠로 모의하기에는 용량도 크고 구조가 복합하여 현실적으로 한계가 있다. 본 연구에서는 기계적 관성모멘트의 한계를 극복하고자 전기적 관성모멘트를 부가적으로 활용하는 기법을 제시하고 이를 적용한 시험기를 소개하고자 한다. 이러한 연구는 시험기의 외형적인 크기를 줄이고 또한 각종 철도차량에서 요구하는 정량적인 관성질량의 모의가 가능하리라고 사료된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.623-631
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• 2018

In this study, the degree of deterioration of concrete was investigated in the laboratory under conditions of carbonation and freeze-thaw cycling, which are the major causes of the deterioration of its performance. In this test, the carbonated concrete was subjected to combined freeze-thaw deterioration tests for up to 300 cycles, and its dynamic elastic modulus and compressive strength were measured. The evaluation of the effect of the water-binder ratio on normal concrete subjected to combined carbonization and freezing-thawing showed that its resistibility against such combined deterioration decreased more rapidly in the concrete with a water-binder ratio of 55 % compared with that having a water-binder ratio of 35 %. In the case where the concrete was blended with a mineral admixture consisting of fly ash and blast furnace slag at the same water-binder ratio, it showed an increase of its resistibility against combined deterioration.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1833-1839
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• 2017

Korea Railway is enhancing the railway wireless communication system from VHF and TRS which have been used for 100 years to LTE-R starting with Ministry of Science and ICT's allocation of Integrated Public Network Frequency on December 2014. LTE-R has advantages on technology performance, also on ease of evolution based on standardization compared to existing technologies. However there are few problems that need to be solved to provide stable railway wireless services in the future. Due to national spectrum policy, LTE-R has frequency interference with Integrated Public Networks (PS-LTE, LTE-M ) and UHD-TV which was commercialized in 2017. This paper introduces performance changes caused by interferences which were founded from the test bed in Wonju~Gangneung LTE-R project and the result of RAN-Sharing. In addition, this paper suggests the standard for LTE-R cell planning in the case of sharing the Integrated Public Network Frequency by analyzing the changes of designed link-budget factor based on the test result.

• Land and Housing Review
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• v.13 no.4
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• pp.125-134
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• 2022

Reclaimed aggregates through waste asphalt are produced and utilized for waste resource utilization. This study conducts quality tests and performance evaluations for mixtures with Rejuvenator applied to reclaimed asphalt concrete. Through quality testing and performance evaluation, the study investigates whether there is any problem in using reclaimed asphalt concrete by replacing general hox mix asphalt. As a result, the values of ordinary hot mix asphalt are similar to those of reclaimed asphalt, suggesting that the substitution does not create critical engineering issues. Using reclaimed asphalt concrete has the advantages of increasing economic efficiency and utilizing waste resources.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.2
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• pp.67-80
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• 2022

Recently, many laundry home appliances have been released with Internet of Things (IoT) functions, but there are few quality evaluation tests for IoT functions. In particular, since IoT test items are not prepared for laundry home appliances applied with IoT functions, it is difficult to find the cause even if defects occur, and test institutions are limited in selecting test items related to IoT and conducting proper performance tests. In this paper, we design a test item framework that separates IoT test items into commonality and variability to identify product defects and causes for laundry home appliances with IoT features among products in the field of home appliances. Through the proposed research, manufacturers and test institutions can test the proper performance of laundry products with IoT functions, which can improve the completeness of the products and ensure reliability.