• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.4
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• pp.612-625
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• 2018

This study designed 16 kinds of basic structure and 4 kinds of modified structure for impact protection pads with a spacer fabric shape. The pad is a structure in which hexagonal three-dimensional units, composed of a surface layer and a spacer layer, are interconnected. Designed pads were printed with flexible $NinjaFlex^{(R)}$ materials using a FDM 3D printer. The printed pads were evaluated for impact protection performance, compression properties and sensory properties. The evaluation of the impact protection performance indicated that basic structures better than CR foam material at 20cm height were DV1.5, DX1.5, DX1.0, DV1.0 and HV1.5. The evaluation of the compression properties for the five types, with good results in the impact protection performance, indicated that DV1.0, DX1.0, DV1.5, HV1.5 and DX1.5 showed good results, respectively. The sensory evaluation of DV1.0, DX1.0, and DV1.5, which with good results when considering both the impact protection performance and the compression performance, showed that DV1.0 were the best for surface, flexibility, compression and weight. Therefore, DV1.0 is shown to be the best structure for protection pads.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.69-78
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• 2009

DV-Hop algorithm is not accurate in estimating geographic location of nodes because the average size for one hop is calculated without considering of the positioning error. In this paper, a novel algorithm based on DV-Hop algorithm is proposed for the approach to estimating the average size of a hop by minimizing anchor's positioning error using Least Square Error with other anchors. Moreover, unknown nodes have their own average size for one hop to compensate for the location error of the unknown occurring as more than the minimum hop counts to the distance. Simulation results show that the proposed algorithm has more accuracy than DV-Hop has in positioning.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.79-81
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• 2016

무선 센서 네트워크 환경에서 사건을 탐지하거나 정보를 추적하는 등의 업무를 수행하기 위해 센서 노드가 있는 곳의 위치를 측정하는 문제는 매우 중요한 문제이다. DV-Hop 알고리즘은 위치를 알 수 없는 미지 노드들이 비콘 노드가 전송한 비콘과 홉거리 정보를 이용하여 센서 노드의 위치를 찾는 방법으로 거리 오차가 크다고 할 수 있다. 본 논문에서는 비콘 노드와 미지 노드 사이의 통신 반경 측정을 통하여 DV-Hop 알고리즘을 개선하고, MATLAB을 이용하여 개선 알고리즘의 성능을 평가하였다.

• Information and Communications Magazine
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• v.21 no.7
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• pp.37-48
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• 2004

Both the 1xEV-DV and HSDPA are advanced standards which can make high speed packet data services come true in mobile communications environment. Both specifications look similar in a point of allocating their radio access resources based on the real-time variation of wireless channels. This paper introduces BTS modems and channel cards for 1xEV-DV and HSDPA developed by LG Electronics, Inc.

• Communications of the Korean Mathematical Society
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• v.21 no.1
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• pp.65-74
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• 2006

In this paper, we will define the Bergman projection type operator Pr and find conditions on which the operator Pr is bound-ed on $L^p$(B, dv). By using the properties of the Bergman projection type operator Pr, we will show that if $f{\in}L_a^p$(B, dv), then $(1-{\parallel}{\omega}{\parallel}^2){\nabla}f(\omega){\cdot}z{\in}L^p(B,dv)$. We will also show that if $(1-{\parallel}{\omega}{\parallel}^2)\; \frac{{\nabla}f(\omega){\cdot}z}{},\;{\in}L^p{B,\;dv),\;then\;f{\in}L_a^p(B,\;dv)$.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.837-840
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• 2010

Wireless Sensor Networks have been proposed for several location-dependent applications. For such systems, the cost and limitations of the hardware on sensing nodes prevent the use of range-based localization schemes that depend on absolute point to point distance estimates. Because coarse accuracy is sufficient for most sensor network applications, solutions in range-free localization are being pursued as a cost-effective alternative to more expensive range-based approaches. In this paper, we proposed a Coefficient Allocated DV-Hop (CA DV-Hop) algorithm which reduces node's location error by awarding a credit value with respect to number of hops of each anchor to an unknown node. Simulation results have verified the high estimation accuracy with our approach which outperforms the classical DV-Hop.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.735-738
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• 2001

디지털 캠코더에서 이용하는 영상 압축 방식인 DV 부호화방식은 DCT와 가변장 부호화 방식을 이용한다. DV 방식은 하드웨어 복잡도가 낮은 반면 압축된 비트 율이 약 26Mbps로 높은 편이다. 따라서 스튜디오에서 낮은 복잡도로 영상을 부호화 한 후 VOD 시스템에서 이용하기 위하여 MPEG-2로 변환부호화 할 필요가 있다. 이때의 두 압축방식이 DCT를 이용하므로, DCT영역에서 변환부호화 하면 중간과정을 줄일 수 있어서 계산상의 복잡도를 줄일 수 있다. 본 논문에서는 DV방식에서 MPEG-2의 인트라로 변환부호화시, DV방식의 4:1:1 색차포맷을 MPEG-2의 4:2:2 색차 포맷으로 변환할 때 변환영역에 있는 데이터에 미리 계산된 행렬을 곱하여 병렬처리가 가능하게 설계하였다. 또한 MPEG-2 율제어는 중요한 서브 블록의 분산을 완전히 DCT영역에서 계산하여 하드웨어 복잡도를 줄였다. 색차포맷변환부 하드웨어 구현을 위하여 VHDL로 코딩한 후 FPGA-EXPRESS(synopsys), ALTERA MAX-PLUS II를 사용하여 모의실험을 하였다. 각 모듈별로 기능을 검증한 후, FPGA EXPRESS(synopsys)를 사용하여 합성 및 검증을 하였다.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.773-780
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• 2004

In this paper, we measured the transmission characteristics of a MPEG2 and a DV that are typical stream-type traffics on the very high speed network and carried out the subjective evaluation of end users for these stream-types. In the subjective evaluation of these stream-type data, video quality evaluation is based on ITU-R BT.500-1 and audio qualify evaluation is based on ITU-R BS.1116-1. Also experiment method to acquire the subjective evaluation of end users is selected the 5 grades method of DSCQS. Under the same condition, in case of MPEG2, the evaluation grade of the video and the audio duality becomes deteriorated at the load rate of $54\%$ that network traffic increases rapidly. In case of DV the evaluation grade of video duality began decrease, but the degree of the change was slower than MPEG2 at the same load rate. Moreover the subjective evaluation grade of end users was superior to load rate $70\%$ in case of DV audio quality, traffic and QoS control that consider the subjective evaluation of end user is required. Conclusively, in case of MPEG2, we can perform traffic control that only use the actual measurement values on the network. However in case of DV, we can perform traffic control that the actual measurement values on the network and the subjective evaluation of end users are considered at the same time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.215-236
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• 2017

Obtaining accurate location information is important in practical applications of wireless sensor networks (WSNs). The distance vector hop (DV-Hop) is a frequently-used range-free localization algorithm in WSNs, but it has low localization accuracy. Moreover, despite various improvements to DV-Hop-based localization algorithms, maintaining a balance between high localization accuracy and good stability and convergence is still a challenge. To overcome these shortcomings, we proposed an improved DV-Hop localization algorithm based on the bat algorithm (IBDV-Hop) for WSNs. The IBDV-Hop algorithm incorporates optimization methods that enhance the accuracy of the average hop distance and fitness function. We also introduce a nonlinear dynamic inertial weight strategy to extend the global search scope and increase the local search accuracy. Moreover, we develop an updated solutions strategy that avoids premature convergence by the IBDV-Hop algorithm. Both theoretical analysis and simulation results show that the IBDV-Hop algorithm achieves higher localization accuracy than the original DV-Hop algorithm and other improved algorithms. The IBDV-Hop algorithm also exhibits good stability, search capability and convergence, and it requires little additional time complexity and energy consumption.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.427-429
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• 2011

임베디드 시스템의 성능이 향상됨에 따라, 이러한 시스템에서의 소모전력을 줄이기위해 다양한 분야에서 연구되어왔다. 그 중에서도, DVS는 마이크로 프로세서의 소모전력을 줄이기 위한 가장 효율적인 기술 중 하나이다. 하지만 DVS는 하드웨어 특성상 오버헤드가 존재하며, 대부분의 연구에서는 이러한 오버헤드를 고려하지 않고 진행되었다. 본 연구는 시스템의 워크로드를 요구 주파수 관점에서 해석하여 매 단위 시간마다 요구 주파수 간의 관계를 확률 모델을 적용하여 해석하고자 했다.