• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.176-179
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• 2011

국내에서는 방화구획을 설정하여 화재 확산 방지 및 재실자의 대피 시간을 확보하고 있다. 방화구획에 설치되는 방화문은 방화문의 내화시험방법(KS F 2268-1)에 따라 시험을 거쳐 성적서를 발급 받은 제품에 대해 설치하도록 의무화 하고 있다. 그러나 본 시험방법은 시험체 제작, 설치 및 의뢰시험비용 등 상당한 비용이 소요될 뿐 아니라 제작, 설치, 시험에 소요되는 시간 또한 길다. 축소실험장치는 목재방화문 개발 중 재료의 내화성능을 평가할 장치로 개발되었으며, 표준시간-가열 온도곡선을 상회하는 가열실험을 통해 재료의 내화성능 결과를 얻을 수 있다. 본 실험에서는 난연 또는 불연성능이 뛰어난 재료를 대상으로 실험하였으며, 그 결과 난연목재는 5분, 마그네슘보드와 내화 직물원단은 60분의 내화성능을 갖춘 것으로 확인되었다. 이 결과를 토대로 방화문의 내화시험방법과 상관성을 도출하여 목재방화문 개발의 지표로 활용 가능하게 되었다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.277-279
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• 2000

본 논문에서는 Mobile IP의 사용에 있어서 핸드오버 시 발생되는 성능 저하를 막기 위한 방안을 제시하였다. 이동 호스트의 이동에 의해 손실되는 패킷을 FA의 buffering과 forwarding을 통하여 방지하고 패킷의 forwarding 동안 송신 호스트를 persist mode로 만들어 놓음으로써 forwarding 되는 데이터를 중복 전송하지 않도록 하였다. 또한, forwarding 되는 패킷에 대한 ack 패킷을 이동 호스트로부터 송신 호스트로 보내어 TCP연결의 End-to-End 시멘틱을 유지할 수 있도록 하였다. 시뮬레이션 결과 제안된 방안이 기존의 방안 보다 우수한 성능을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.675-684
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• 2004

There have been several efforts to avoid unnecessary retransmission timeouts (RTOs), which is the main cause for TCP throughput degradation. Unnecessary RTOs can be classified into three groups according to their cause. RTOs due to multiple packet losses in the same window for TCP Reno, the most prevalent TCP version, can be avoided by TCP NewReno or using selective acknowledgement (SACK) option. RTOs occurring when a packet is lost in a window that is not large enough to trigger fast retransmit can be avoided by using the Limited Transmit algorithm. In this Paper, we comparatively analyze these schemes to cope with unnecessary RTOs by numerical analysis and simulations. On the basis of the results in this paper, TCP performance can be quantitatively predicted from the aspect of loss recovery probability. Considering that overall performance of TCP is largely dependent upon the loss recovery performance, the results shown in this paper are of great importance.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.6
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• pp.51-61
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• 2007

In this paper, Air-interface protocols of ISO 18000-6 Types and EPCglobal Classes applied to RFID system in UHF band are analyzed, and those anticollision algorithms are realized. Also, the each algorithm which improves the performance of standard protocol is proposed, and the performance is compared when clock period of link timing is a identical condition on $12.5{\mu}s$. As the result, when 500 tags exist simultaneously inside reader interrogation zone, the tag recognition performance of a standard protocol is better in preceding order of Class-1 Generation-1, Type B, Type A, Class-0 and Class-1 Generation-2. And also the performance of improved protocol is better in ascending order of Type B, Type A, Class-1 Generation-1, Class-0 and Class-1 Generation-2. Therefore, performance of tag recognition remarkably depends on the regulated clock period in the protocol and link timing between a reader and a tag.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.71-74
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• 2011

현대의 전술데이터링크는 전장인식에 대한 요구가 증대되어 복잡한 다중 전술데이터링크가 운용되는 추세이다. 동일 정보를 하나 이상의 경로를 통해 수신하거나 자신이 전송한 데이터를 다른 데이터링크의 중 계기를 통하여 수신하는 것을 데이터 루핑이라 하는데 루핑은 이중 표적 전시현상 또는 표적 점핑현상을 유발하고 처리기의 부하 증가로 인한 시간/자원적 낭비 등 전술데이터링크에 악영향을 미칠수 있다. 이러한 문제점을 해결하기 위해 이 논문에서는 루핑 방지 알고리즘를 제안하였고, 제안한 알고리즘이 전술 데이터링크상에서의 루핑 현상을 방지하고 효과적으로 동작할 수 있을지에 대한 성능 검증을 위하 실험을 실시하였고, 그 결과 루핑을 방지하는 것을 확인하였다.

• Journal of the Society of Disaster Information
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• v.10 no.1
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• pp.105-115
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• 2014

In this research, we developed video analytic algorithms to detect water-level automatically and a system for proactive alarming using intelligent CCTV cameras. We applied these algorithms and a system to test-beds and verified for practical use. We made camera-selection policies and operation plans to keep the detection accuracy high and to optimize the suitability for the ever-changing weather condition, while the environmental factors such as camera shaking and weather condition can affect to detection accuracy. The estimation result of algorithms showed 90% detection accuracy for all CCTV camera types. For water level detection, NIR camera performed great. NIR camera performed over 95% accuracy in day or night, suitable in natural weather condition such as shaking condition, fog, and low light, needs similar installment skills with common cameras, and spends only 15% high cost. As a result, we practically tested water level detection algorithms and operation system based on intelligent CCTV camera. Furthermore, we expect the positive evidences when it is applied for public use.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.499-511
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• 2022

In this study, a vertical drop test was carried out to identify the performance of flexible wire rope rockfall protection fence by 100 kJ rockfall energy according to ETAG 027. The flexible wire rope, which consists of wire rope and spring. is especially enhanced the elasticity and flexibility so that it can be longer elongated when the rope is impacted by rockfall compared to original wire rope, and that results longer increase of contact time between rockfall and wire rope and increase rockfall energy absorption capability and decreases rockfall impact force. The test results shows that the plastic deformation occurred in middle post and the final deflection of the middle post was 1.15 m, which is lower than 2.0 m determined by ETAG 027. This vertical test verified the flexible wire rope rockfall protection fence can successfully absorb 102.9 kJ rockfall energy.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.24-33
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• 2012

The present work has suggested the design methods of the bolt body for making the anti-releasing bolts and provided the changed properties of the bolt body after explosion. To prove this work, two models of the anti-releasing bolts, M10 and M20, are produced and the expansion properties of each model are experimentally obtained. This study verify that the expansion of the bolt body is reproducible and the expansion rate could be controlled by the combination of the design factors and the anti-releasing characteristics could be quantified. It also could provide the data that would be needed to make the bolts with the anti-releasing effect.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.49-60
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• 2009

In order to develop a new rockfall protection fence using high carbon steel wire rod (HSWR) material instead of the conventional wire rope material, the author has conducted the laboratory strength tests of both materials and their connections, and carried out evaluation of absorbing rockfall energy through the vertical field rockfall tests. The vertical filed rockfall tests showed that the new rockfall protection fence with 12 rows of the HSWR could absorb more rockfall energy than 50 kJ which stands for the typical design criteria. In addition, when the quantity of HSWR was increased up to the 16 rows, the capacity of absorbing energy was greatly improved. The new rockfall protection fence was successfully applied to the highway rock-cut slope. As a result of the filed application, its constructability was similar to the conventional fence, but its total image was improved as simple and clean. The total construction cost was saved up to 20% in comparison with the conventional one.

• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.69-75
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• 2014

Rock fall protection system installed against rock slope is one of the most conventional way to protect nearby infra structures. Despite of wide application of typical rectangular nets, virtually installed to protect rock slope face, several problems have also been pointed out up to date. Rectangular draped nets are vulnerable to a sudden external shock such as rock fall, because it doesn't have any systematical buffers or shock absorbers. Furthermore, it has been widely recognized from the some cases of rock fall accident in Korea that rock fall protection nets cause wide range of failure in the rock slope faces due to insufficient pullout bearing capacity of fixing parts. Therefore, in this study, we tried to make a consideration about the problems of existing standard rock fall protection nets in Korea, and develop a new type of hexagonal net with a shock absorber based on design rock fall energy. In this paper, laboratory and full scale test procedure is described to analysis the performance of newly developed hexagonal rock fall net, and the key results are presented and discussed.