• 대한산업공학회지
• /
• 제18권2호
• /
• pp.11-22
• /
• 1992

Up to now, most researches on production automation have concentrated on local automation, e. g. CAD, CAM, robotics, etc. However, to achieve total automation it is required to link each local modules such as CAD, CAM into a unified and integrated system. One such missing link is between CAD and computer vision system. This thesis is an attempt to link the gap between CAD and computer vision system. In this paper, we propose algorithms that carry out edge detection, thinning and pruning from the image data of manufactured parts, which are obtained from video camera and then transmitted to computer. We also propose a feature extraction and surface determination algorithm which extract informations from the image data. The informations are compatible to IGES CAD data. In addition, we suggest a methodology to reduce search efforts for CAD data bases. The methodology is based on graph submatching algorithm in GEFG(Generalized Edge Face Graph) representation for each part.

• International Journal of Quality Innovation
• /
• 제8권1호
• /
• pp.1-14
• /
• 2007

The Six Sigma and Lean Production methodologies suggest that creating value for customers is the objective of a production process or an organisation. In the production context, "added value" dominates the discussion about the creation of value to customers. However, "added value" is often only defined conceptually or discussed at a strategic level, and the link between added value and customer value has not yet been well conceptualised. Therefore, the purpose of the paper is to develop a methodology to measure added value in order to complement the existing performance measures in Six Sigma and Lean Production by conceptualising the link between customer value and added value. The conceptual link "confirms" that quality, time, and costs are the elements of added value, which are transformed into a metric to express customer value. The implementation of the metric recommends the adoption of Lean (Six) Sigma and Lean Accounting (Activity Based Costing), which thus implies that "leanness" is an important "feature" of added value.

• 정보처리학회논문지B
• /
• 제13B권4호
• /
• pp.489-498
• /
• 2006

색인전문가에 의해 분류된 웹문서들을 통계적 자질 선택방법으로 자질을 추출하여 클라스터링을 해 보면, 자질 선택에 사용된 데이터셋에 따라 성능과 결과가 다르게 나타난다. 그 이유는 많은 웹 문서에서 문서의 내용과 관계없는 단어들을 많이 포함하고 있어 문서의 특정을 나타내는 단어들이 상대적으로 잘 두드러지지 않기 때문이다. 따라서 클러스터링 성능을 향상시키기 위해 이런 부적절한 자질들을 제거해 주어야 한다. 따라서 본 논문에서는 자질 선택에서 자질의 문서군별 자질값뿐만 아니라, 문서군별 자질값의 분포와 정도, 자질의 출현여부와 빈도를 고려한 자질 필터링 알고리즘을 제시한다. 알고리즘에는 (1) 단위 문서 내 자질 필터링 알고리즘(FFID : feature filtering algorithm in a document), (2) 전체 데이터셋 내 자질 필터링 알고리즘(FFIM : feature filtering algorithm in a document matrix), (3)FFID와 FFIM을 결합한 방법(HFF:a hybrid method combining both FFID and FFIM) 을 제시한다. 실험은 단어반도를 이용한 자질선택 방법, 문서간 동시-링크 정보의 자질확장, 그리고 위에서 제시한 3가지 자질 필터링 방법을 사용하여 클러스터링 했다. 실험 결과는 데이터셋에 따라 조금씩 차이가 나지만, FFID보다 FFIM의 성능이 좋았고, 또 FFID와 FFIM을 결합한 HFF 결과가 더 나은 성능을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권6호
• /
• pp.2801-2816
• /
• 2016

Owing to their low scalability, weak support on big data, insufficient data collaborative analysis and inadequate situational awareness, the traditional methods fail to meet the needs of the security data analysis. This paper proposes visualization methods to fuse the multi-source security data and grasp the network situation. Firstly, data sources are classified at their collection positions, with the objects of security data taken from three different layers. Secondly, the Heatmap is adopted to show host status; the Treemap is used to visualize Netflow logs; and the radial Node-link diagram is employed to express IPS logs. Finally, the Labeled Treemap is invented to make a fusion at data-level and the Time-series features are extracted to fuse data at feature-level. The comparative analyses with the prize-winning works prove this method enjoying substantial advantages for network analysts to facilitate data feature fusion, better understand network security situation with a unified, convenient and accurate mode.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권5호
• /
• pp.2484-2498
• /
• 2017

Various types of social media make the people share their personal experience in different ways. In some social networking sites. Some users post their reviews, some users can support these reviews with comments, and some users just rate the reviews as kind of support or not. Unfortunately, there is rare explicit negative comments towards other reviews. This means if there is a link between two users, it must be positive link. Apparently, the negative link is invisible in these social network. Or in other word, the negative links are redundant to positive links. In this work, we first discuss the feature extraction from social media data and propose new method to compute the distance between each pair of comments or reviews on social media. Then we investigate whether we can predict negative links via regression analysis when only positive links are manifested from social media data. In particular, we provide a principled way to mathematically incorporate multi-facet data in a novel framework, Constructing Negative Links, CsNL to predict negative links for discovering the hidden information. Additionally, we investigate the ways of solution to general negative link predication problems with CsNL and its extension. Experiments are performed on real-world data and results show that negative links is predictable with multi-facet of social media data by the proposed framework CsNL. Essentially, high prediction accuracy suggests that negative links are redundant to positive links. Further experiments are performed to evaluate coefficients on different kernels. The results show that user generated content dominates the prediction performance of CsNL.

• 한국통신학회논문지
• /
• 제36권9A호
• /
• pp.801-808
• /
• 2011

본 논문은 무선랜 메쉬 네트워크 링크 품질 측정 정확성 향상을 위한 MBAP(Multi-rate Broadcast Active Probing) 방법을 제안한다. 라우팅을 위한 척도로 홉수를 주로 사용하는 MANET과 달리 메쉬 네트워크는 ETX, ETT 등의 링크 품질 기반의 척도를 주로 사용한다. ETX. ETT 등의 측정을 위해 기존 연구들에서는 단일 전송률 브로트캐스트 기반의 측정 방법을 사용한다. 하지만 이 방법은 다양한 전송률을 가질 수 있는 무선랜 링크의 품질을 제대로 반영하지 못하며 이는 적절하지 못한 경로 선택으로 귀결될 수 있다. MBAP는 다양한 전송률의 브로드캐스트를 사용함으로써 우선 링크 품질 측정의 정확성을 향상시켰다. 우리는 MBAP를 리눅스 기반의 링크계층에서 구현하였으며 실험을 통해 그 효용성을 검증하였다.

• 한국정보과학회논문지:정보통신
• /
• 제36권5호
• /
• pp.456-469
• /
• 2009

본 논문에서 ECOT(Estimated Channel Occupancy Time)이라는 새로운 무선 링크 성능 지표를 제시하며, 이를 기반으로 멀티 홉 무선 메쉬 네트워크 환경에서 종간간 높은 수율을 얻고자 한다. ECOT의 핵심적인 특징은 다양한 형태의 IEEE 802.11 MAC(Medium Access Control) 환경에서 적용이 가능하다는 점이다. 우리는 802.11 DCF(Distributed Coordination Function), 802.11e EDCA(Enhanced Distributed Channel Access) with BACK(Block Acknowledgement), 802.11n A-MPDU(Aggregate MAC Protocol Data Unit)와 같은 다양한 형태의 링크 계층 구조를 고려하며, 이와 같은 다양한 환경에서 제안하는 ECOT이 기 제안된 다른 성능 지표 방법론과 비교하여 높은 종단간 수율 성능(이득: $8.5{\sim}354.4%$)을 보여줄 수 있다는 것을 확인하였다.

• Journal of Electrical Engineering and Technology
• /
• 제6권2호
• /
• pp.215-225
• /
• 2011

In this paper, a buck DC-DC bridge converter is used as a power factor correction (PFC) converter for feeding a voltage source inverter (VSI) based permanent magnet brushless DC motor (PMBLDCM) drive. The front end of the PFC converter is a diode bridge rectifier (DBR) fed from single phase AC mains. The PMBLDCM is used to drive the compressor of an air conditioner through a three-phase voltage source inverter (VSI) fed from a variable voltage DC link. The speed of the air conditioner is controlled to conserve energy using a new concept of voltage control at a DC link proportional to the desired speed of the PMBLDC motor. Therefore, VSI operates only as an electronic commutator of the PMBLDCM. The current of the PMBLDCM is controlled by setting the reference voltage at the DC link as a ramp. The proposed PMBLDCM drive with voltage control-based PFC converter was designed and modeled. The performance is simulated in Matlab-Simulink environment for an air conditioner compressor load driven through a 3.75 kW, 1500 rpm PMBLDC motor. To validate the effectiveness of the proposed speed control scheme, the evaluation results demonstrate improved efficiency of the complete drive with the PFC feature in a wide range of speed and input AC voltage.

• 한국통신학회논문지
• /
• 제22권5호
• /
• pp.1075-1082
• /
• 1997

In this paper, we propose a channel assignment scheme for reducing call blocking rate in a base station(BS) of DS-CDMA cellular systems. The proposed scheme can e applied to the case where the capacity of reverse radio link is enough, but not are the available traffic channels performing the digital modulation and demodulation functions between a mobile station and the base station. The proposed scheme takes advantage of the feature of soft handoff in which a mobile station keeps its communication link even if one of the two communication links is released. The scheme estimates the mean and variance of the received power level measured at the base station before assigning a traffic channel for a new call request. The BS makes decision based on the estimated balues whether the new call request will be accepted or not. If it is decided that the capacity of reverse radio link is enough, but all traffic channels are not available, then the BS increases the soft handoff parameter T_DROP to release the traffic channels of mobile stations loactedin soft handoff area. The BS assigns the released traffic channel to anew call or a handoff call. The performance of the proposed channel assignment scheme is evaluated by computer simulation. The results show that the call blocking rate for new calls and handoff calls is reduced.

• 전자공학회논문지S
• /
• 제34S권7호
• /
• pp.48-55
• /
• 1997

An adaptive output feedback controller is designed for tracking control of an n-link robot manipulator with unknown load. High-gain obwserver that is used to estimate joint velocities is designed to avoide the restriction of the allowable variation range of unknown parmeters as well as improve the state estimation error. We saturate the control inut outside a domain of interest and use an adaptive law with a parameter projection feature to guarantee boundedness of all the trajectories in the closed-loop system. Simulation resutls on a 2-link manipulator illustrate that when the speed of the high-gain observer is sufficiently high, the proposed controller recovers the performance under state feedback control.