• Journal of Electrical Engineering and Technology
• /
• 제13권6호
• /
• pp.2456-2467
• /
• 2018

Wireless multimedia sensor networks (WMSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. The end-to-end delay is very critical metric for QoS guarantees in WMSNs. In WMSNs, due to the transmission errors incurred over wireless channels, it is difficult to obtain reliable delivery of data in conjunction with low end-to-end delay. In order to improve the end-to-end delay performance, the system has to drop few packets during network congestion. In this article, our proposal is based on optimization of end-to end delay for WMSNs. We optimize end-to-end delay constraint by assuming that each packet is allowed fixed number of retransmissions. To optimize the end-to-end delay, first, we compute the performance measures of the system, such as end-to-end delay and reliability for different network topologies (e.g., linear topology, tree topology) and against different choices of system parameters (e.g., data rate, number of nodes, number of retransmissions). Second, we study the impact of the end-to-end delay and packet delivery ratio on indoor and outdoor environments in WMSNs. All scenarios are simulated with multiple run-times by using network simulator-2 (NS-2) and results are evaluated and discussed.

• Journal of Communications and Networks
• /
• 제11권3호
• /
• pp.297-305
• /
• 2009

Multiprotocol label switching (MPLS) networks require dynamic flow admission control to guarantee end-to-end quality of service (QoS) for each Internet protocol (IP) traffic flow. In this paper, we propose to tackle the joint routing and admission control problem for the IP traffic flows in MPLS networks without rerouting already admitted flows. We propose two mathematical programming models for this problem. The first model includes end-to-end delay constraints and the second one, end-to-end packet loss constraints. These end-to-end QoS constraints are imposed not only for the new traffic flow, but also for all already admitted flows in the network. The objective function of both models is to minimize the end-to-end delay for the new flow. Numerical results show that considering end-to-end delay (or packet loss) constraints for all flows has a small impact on the flow blocking rate. Moreover, we reduces significantly the mean end-to-end delay (or the mean packet loss rate) and the proposed approach is able to make its decision within 250 msec.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
• /
• 한국정보과학회언어공학연구회 2018년도 제30회 한글 및 한국어 정보처리 학술대회
• /
• pp.453-458
• /
• 2018

본 논문은 한국어 자소를 인식 단위로 사용한 hybrid CTC-Attention 모델 기반 end-to-end speech recognition을 제안한다. End-to-end speech recognition은 기존에 사용된 DNN-HMM 기반 음향 모델과 N-gram 기반 언어 모델, WFST를 이용한 decoding network라는 여러 개의 모듈로 이루어진 과정을 하나의 DNN network를 통해 처리하는 방법을 말한다. 본 논문에서는 end-to-end 모델의 출력을 추정하기 위해 자소 단위의 출력구조를 사용한다. 자소 기반으로 네트워크를 구성하는 경우, 추정해야 하는 출력 파라미터의 개수가 11,172개에서 49개로 줄어들어 보다 효율적인 학습이 가능하다. 이를 구현하기 위해, end-to-end 학습에 주로 사용되는 DNN 네트워크 구조인 CTC와 Attention network 모델을 조합하여 end-to-end 모델을 구성하였다. 실험 결과, 음절 오류율 기준 10.05%의 성능을 보였다.

• 사물인터넷융복합논문지
• /
• 제9권1호
• /
• pp.65-70
• /
• 2023

본 논문에서는 비전 센서 기반 시스템의 차선 이탈과 신호등 오인식 등을 개선하기 위해 End to End 모델을 활용한 자율주행 시스템을 제안한다. End to End 학습은 다양한 환경 조건에 대해 확장을 할 수 있다. 비전 센서 기반 모형 자동차를 이용하여 주행 데이터를 수집한다. 수집한 데이터를 이용하여 기존의 데이터와 아웃레이어를 제거한 데이터로 구성한다. 입력 데이터인 카메라 이미지 데이터, 출력 데이터인 속도와 조향 데이터로 클래스를 구성하고 End to End 모델을 활용하여 데이터 학습을 수행하였다. 학습된 모델의 신뢰성을 확인했다. 모형 자동차에 학습한 End to End 모델을 적용하여 이미지 데이터로 조향각을 예측한다. 모형 자동차의 학습 결과, 아웃레이어를 제거한 모델이 기존 모델보다 향상된 것을 볼 수 있다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.747-752
• /
• 2004

Researches about scheduling of the distributed real-time systems have been proposed. However, they have some weak points, not scheduling both sporadic and periodic tasks and messages or being unable to guaranteeing the end-to-end constraints due to omitting precedence relations between sporadic tasks. So this paper proposes a new scheduling method for distributed real-time systems consisting of sporadic and periodic tasks with precedence relations and sporadic and periodic messages, guaranteeing end-to-end constraints. The proposed method is based on a binary search-based period assignment algorithm, an end-to-end laxity-based priority assignment algorithm, and three kinds of schedulability analysis, node, network, and end-to-end schedulability analysis. In addition, this paper describes the application model of sporadic tasks with precedence constraints in a distributed real-time system, shows that existing scheduling methods such as Rate Monotonic (RM) scheduling are not proper to be applied to the system having sporadic tasks with precedence constraints, and proposes an end-to-end laxity-based priority assignment algorithm.

• 한국항행학회논문지
• /
• 제15권2호
• /
• pp.248-255
• /
• 2011

분산 보상 구조가 광 위상 공액기 (OPC; optical phase conjugator)를 갖는 960 Gbps의 파장 분할 다중 (WDM; wavelength division multiplexed) 시스템에 미치는 영향을 컴퓨터 시뮬레이션을 통해 살펴보았다. 본 연구에서 고려한 분산 보상 구조는 전통적인 one-end 구조와 bi-end 구조이다. one-end 구조와 bi-end 구조는 하나의 단일 모드 광섬유 (SMF; single mode fiber) 중계 간격마다 축적된 분산량을 줄여주기 위하여 각각 하나의 분산 보상 광섬유 (DCF; dispersion compensating fiber)와 두 개의 DCF를 사용하여 만들어진다. 전체 잉여 분산 (NRD; net residual dispersion)이 최적화되면 중계 거리 당 잉여 분산 (RDPS; residual dispersion per span)이 400 ps/nm인 WDM 시스템에서 bi-end 구조와 one-end 구조는 거의 동일한 성능을 나타내는 것을 확인하였다.

• Journal of Biosystems Engineering
• /
• 제29권3호
• /
• pp.281-286
• /
• 2004

The end-effector is the one of the important factors on development of the cucumber robot to harvester a cucumber. Three end-effectors were designed the single blade end-effector with one blade, the double blade end-effector with two blades and the triple blade end-effector with three blades. Performance tests of the end-effector, the fully integrated system, were conducted to determine the cutting rate by using two different kinds of cucumber. The success rates of cucumber cutting ratio of single end-effector, double end-effector and triple end-effector in laboratory. were 61.7%, 95%, 86.7%, respectively. The cutting rate of single blade or double blade was a little difference with respect to the different diameters of cucumber stem. However, the success cutting rate of the end-effector with triple blade was 61.7% under 29mm diameter of a grabbing stem section. The triple end-effector was not suitable for harvesting a cucumber, but was considered to be suitable for harvesting a grape, an apple and a tomato. The success rate of cucumber cutting ratio of triple end-effectors in greenhouse was 84%. The failure cutting rate was 16% which are due to abnormal shape of cucumber fruit.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제53권7호
• /
• pp.501-508
• /
• 2004

In this paper, a coordinated scheduling algorithm is proposed to reduce end-to-end delay in distributed control of systems. For the algorithm, the analysis of practical end-to-end delay in the worst case is performed priory with considering implementation of the systems. The end-to-end delay is composed of the delay caused by multi-task scheduling of operating systems, the delay caused by network communications, and the delay caused by asynchronous timing between operating systems and network communications. Through some simulation tests based on CAN(Controller Area Network), the proposed worst case end-to-end delay analysis is validated. Through the simulation tests, it is also shown that a real-time distributed control system designed to existing worst case delay cannot guarantee end-to-end time constraints. With the analysis, a coordinated scheduling algorithm is proposed here. The coordinated scheduling algorithm is focused on the reduction of the delay caused by asynchronous timing between operating systems and network communications. Online deadline assignment strategy is proposed for the scheduling. The performance enhancement of the distributed control systems by the scheduling algorithm is shown through simulation tests.

• 한국공작기계학회논문집
• /
• 제11권6호
• /
• pp.1-9
• /
• 2002

This study describes the geometric characteristics and the 5-axis machining method in order to make end mill cutter coming with insert tips. End mill geometry is consisted of flute part and insert tip part. Flute part modeled by using ruled surfaces with constant helix angle, and insert tip part modeled by rectangular planes containing tapped hole of specified direction in its center. In this study, the modeled insert tip part considered both of a radial rake angle and a axial rake angle, because they were important cutting conditions. In order to machining the virtual end mill defined from geometric characteristics, we programmed a special software to machining the end mill considered in this study. This software can generate NC-codes about following processes, end milling or ball end milling of flute part end milling of rectangular plane, centering of hole, drilling of hole, and tapping of hole. Ant sampled end mills were modeled and machined on 5-axis CNC machining center with two index tables. Since machined end mills were very agreeable to designed end mills, we saw that the method proposed in this study can be very useful for manufacturing of end mill body with insert tip.

• 한국의류학회지
• /
• 제29권11호
• /
• pp.1381-1388
• /
• 2005

The purpose of this study was to identify features of masstiege high-end products by comparing to original old high-end products. For this purpose, the differences in values between each consumer groups divided by preferred products types (high-end products, original old high-end products) were examined. This study was executed by consumer survey and 279 female data were used in analysis. The results are as follows. First, the value factors pursued on high-end products were constructed by factor analysis and the factors consisted of 4 elements; conspicuous, aesthetic, durable, conformity. Next, the differences in value elements between masstiege high-end products and original old high-end products were identified by t-test. The consumers preferring original old high-end products pursued conspicuous features significantly more and the consumers preferring masstiege high-end products considered aspects of aesthetic and conformity elements as more important. And according to kinds of preferring high-end product, demographic characteristics were different. The consumers who were of high age, high education and high income and married consumers preferred original old high-end products, whereas the consumers who were of low age, low education and low income and unmarried consumers preferred masstiege high-end products. Finally, marketing strategies for masstiege brand were suggested on the base of the results.