• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.367-376
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• 2012

Crack sealing is a maintenance technique commonly used to prevent water and debris penetration and reduce future degradation in pavement. The conventional crack sealing operations are, however, dangerous, costly, and labor-intensive. Automating crack sealing will improve productivity and quality, and offer safety benefits by getting worker off the road. During the last two decades, several teleoperated and machine-vision assisted systems have been developed to automate the overall process of routing and sealing pavement cracks. However, the developed systems have not been commonly used in the construction sites because of the technical problems. Especially, the performance of end-effector, related to the productivity and quality improvement, is very important factor to improve the practical use of the developed systems. The main objective of this research is to develop an end-effector in automated pavement crack sealing machine and to analyze the technical feasibility of the developed end-effector.

• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.93-100
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• 1999

When providing MPEG-2 video service through the ATM network, the degradation of QoS caused by cell losses and cell errors occuring from ATM netwok was assessed by the end-users subjectively and then the relation between CLR, CER and subjective QoS of MPEG-2 video was analyzed. Cell losses and cell errors occuring from the ATM network were generated according to the normal and exponential distribution by NEM module. Video sources were divided into sports and drama by moving feature and were tested. The results of our experiments show that the excellent quality of subjective QoS grade 5 was achieved for a cell loss rate of $2{\times}10^{-7}$ and for a cell error rate of $2{\times}10^{-7}$ and the good quality of subjective QoS grade 4 was achieved for a cell loss rate of $2{\times}10^{-6}$ and for a cell error rate of $2{\times}10^{-6}$ When providing MPEC-2 video service through the ATM network, the results of our experiments will be used as valuable information to determine the network performance objectives for satisfying the QoS required by the end-users and to design the network.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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• pp.1-5
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• 1998

소프트 핸드오프는 공간 다이버서티 때문에 끊김없는 통화를 보장할 수는 있지만, 하나의 단말이 두개 이상의 셀에서 자원을 사용하므로 자원의 낭비를 초래하게 된다. 따라서 CDMA에서 소프트 핸드오프 방법을 이용할 때는 성능면에서 통화의 품질과 망 자원사이에 평형을 유지해야 한다. IS-95에서 명시된 소프트 핸드오프 진행 절차에 단말의 프로필 파라미터를 활용하는 새로운 소프트 핸드오프 알고리즘을 제시하고 이를 시뮬레이션을 통하여 성능을 분석한다. 단말이 호를 유지한 상태에서 셀의 경계점을 계속 왕복한다면 잦은 핸드오프가 발생하게 되고 활성 집합에는 항시 여러 기지국이 연결상태에서 또 다시 핸드오프를 요구할 확률은 지수적으로 감소한다. 또한, 단말이 호를 유지한 상태에서 핸드오프가 이루어진 경력을 안다면 활성 집합에 포함될 기지국의 수를 제한할 수 있으므로 자원의 낭비를 막을 수 있다. 이와 같이 단말의 프로필을 이용한 경우에 시뮬레이션 결과는 제안한 알고리즘이 IS-95보다 호의 블록킹 확률이 감소함을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3B
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• pp.204-211
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• 2012

Wireless Mesh Network (WMN) has drawn much attention due to wide service coverage with low system cost. However, WMN suffers from high bit error rate, which provides different link capacity among wireless mesh routers. The conventional routing metrics select the path based on link quality. The link with the best quality is preferred as the data transmission path, and they becomes the bottleneck links, which leads to network performance degradation. In this paper, we propose a routing metric that considers the available bandwidth and the number of nodes suffering congestion in the path. Through computer simulations, we verified that the proposed routing metric outperforms the existing routing metrics in terms of average transmission delay, packet loss, system throughput.

• Journal of KIISE:Software and Applications
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• v.36 no.8
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• pp.616-622
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• 2009

Thanks to Dynamic Capacitance Control (DCC) technique, response time of an LCD display has greatly improved. However, DCC requires hi-speed memory for the real-time writing/reading of an image of a previous frame, which results in increases in hardware overhead and cost. In this paper, we propose Modified Exponential Golomb (MEG) coding, a low-complex high-speed image compression method, which can remarkably reduce memory requirement for DCC. We also propose a pixel-wise DCC switching technique to prevent a compression error from affecting the quality of a final image on LCD. In our experiment, the degradation in visual quality was not noticeable when we cut the DCC memory size of 1080i HD data by 1/3.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.314-320
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• 2001

In this paper, the properties of an expansive agent (CaO-CaS $O_4$) for dry shrinkage compensation were investigated by a series of experimental program, which might be used at On-Dol heating system as mortar type. The expansion principle of the CaO-CaS $O_4$ was mainly verified. As a result of this study, the correlation between the content of the expansive agent and the compressive strength was obtained in the form of exponential function(Y = A $e^{-x}$), showing that as the content of expansive agent increased as the expansion performance with the compressive strength increased by only a certain amount. Also, as a results of the analysis of a correlation between the expansive performance and the chemical properties which generally accompanied a part of quality management in manufacturing the expensive cement, the expansive performance was relative to only the contents of the F-CaO among chemical properties(Blaine, +44$\mu\textrm{m}$R, F-CaO, S $O_3$,L.O.I). And it was clarified that the results were relative to the second order function, showing that if the contents of the F-CaO increased the expansive performance Increased.d.

• Journal of Korean Society of Transportation
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• v.27 no.2
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• pp.47-56
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• 2009

Effective detection and correction of outliers of raw traffic data collected from the field is of keen interest because reliable traffic information is highly dependent on the quality of raw data. Global positioning system (GPS) based traffic surveillance systems are capable of producing individual vehicle speeds that are invaluable for various traffic management and information strategies. This study proposed a locally weighted regression (LWR) based filtering method for individual vehicle speed data. An important feature of this study was to propose a technique to generate synthetic outliers for more systematic evaluation of the proposed method. It was identified by performance evaluations that the proposed LWR-based method outperformed an exponential smoothing. The proposed method is expected to be effectively utilized for filtering out raw individual vehicle speed data.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.3
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• pp.109-114
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• 2021

GAN(Generative Adversarial Network) is an image generation model, which is composed of a generator network and a discriminator network, and generates an image similar to a real image. Since the image generated by the GAN should be similar to the actual image, a loss function is used to minimize the loss error of the generated image. However, there is a problem that the loss function of GAN degrades the quality of the image by making the learning to generate the image unstable. To solve this problem, this paper analyzes GAN-related studies and proposes an edge GAN(eGAN) using edge detection. As a result of the experiment, the eGAN model has improved performance over the existing GAN model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.2 s.3
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• pp.1-12
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• 2003

DAB(Digital audio broadcasting) is a next generation radio broadcasting system which provides CD quality audio, various data services and superior reception ability when moving. Also, it can show traffic informations and news literally or graphically. In this paper, we design and fabricate the DAB tuner for ITS service that follows Eureka-147 and ETSI 300 401 specifications. This small-sized tuner can be adopted to mny electronic equipments such as a Hi-Fi audio, DVD player, car audio system etc.. The overall performance of the tuner depends on a phase noise of VCO and the sensitivity of the receiving system is influenced by LNA, image rejection filter and channel selection filter. All our measurement results satisfy the specification for a DAB system with the return loss of 9dB, the noise figure of 6dB for both Band 111 and L-band and the sensitivity of -97dBm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.74-80
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• 2021

This study investigated the process quality level of a K5 gas mask, which recently acquired its operational capability, through statistical process analysis for the mass production stages and their lots. The tensile adhesion strength was the only operating requirement in the manufacturing process of the K5 gas mask. For this purpose, the results of tensile adhesion strength between the lens and facial rubber during the initial and second mass production stages were analyzed using conventional statistical and statistical process analysis methods. The conventional statistical results indicated that the second mass production stage was better than the initial mass production stage. In cases of a control chart and process capability of tensile adhesion strength, the process quality level was also improved by following the mass production stages. The improvement was caused by process stabilization and work skill elevation. These results and methods are expected to be conducted and utilized in the third mass production stage. Moreover, quality improvement of K5 gas mask mass production can be achieved using the Lean 6 sigma procedure, MDAIC (Define, Measure, Analyze, Improve, Control).