• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.568-571
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• 2004

This paper presents an efficient 5-axis roughing method for centrifugal impeller. The efficient roughing is minimization of cutting time through minimizing tool tilting & rotating motions. Roughing tool path plan consists of the three steps. First, machining areas are divided into sub cutting regions using ruling lines. The biggest tool diameter is, then, determined for each region. Finally, tool paths are generated after fixing the tilting and rotating axis of 5-axis machine. Experimental results showed that the proposed roughing plan considering the divided machining regions is more efficient than the conventional methods.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.60-68
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• 2007

This paper presents an efficient 5-axis roughing method for centrifugal impeller. The efficient roughing is minimization of cutting time through minimizing tool tilting and rotating motions. To minimized cutting time, machining area is divided into sub-cutting regions using control points on hub curves and shroud curves of blade used to design and analyze centrifugal impeller. For sub-cutting regions, diameters of cutting tools are determined as big as possible. Then, tool paths are generated with the tilting axis and rotating axis of 5-axis machine limited and fixed, which can give more efficient machining speed and machining stability than the conventional methods. Experimental results show that the proposed method is more efficient than the conventional methods to mill with the only one cutting tool without dividing area and the previous methods to mill with simultaneous 5-axis processing with dividing area.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.215.1-215
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• 2003

Bacillus polymyxa No. 26이 생산하는 생전분 당화형 $\beta$-amylase를 쌀가루 반죽시 첨가하여 45$^{\circ}C$에 5시간 둔 후 증자하여 제조한 절편을 4$^{\circ}C$ 저온실에 40시간 동안 저장하면서 기계적 검사와 관능검사에 의하여 물성과 맛을 측정하고 효소 무 첨가의 경우와 비교하여 노화억제 효과를 조사하였다. 기계적 검사시 효소 무 첨가구의 경우는 40시간까지도 굳지 않아 노화되지 않았으며, 경도, 점착성, 씹힘성에서도 큰 차이를 보였다. 관능검사시에도 경도, 촉촉함성, 단맛에 있어서 효소 첨가효과가 크게 나타났으며 떡의 제조 시 효소의 이용으로 설탕첨가를 생략할 수 있고 소화성과 맛을 좋게하므로서 품질을 향상시킬 수 있었다.

• Journal of Korea Multimedia Society
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• v.24 no.1
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• pp.1-12
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• 2021

In this paper, we present a new architecture for semantic segmentation. Semantic segmentation aims at a pixel-wise classification which is important to fully understand images. Previous semantic segmentation networks use features of multi-layers in the encoder to predict final results. However, they do not contain various receptive fields in the multi-layers features, which easily lead to inaccurate results for boundaries between different classes and small objects. To solve this problem, we propose a multi-path feature fusion module that allows for features of each layers to contain various receptive fields by use of a set of dilated convolutions with different dilatation rates. Various experiments demonstrate that our method outperforms previous methods in terms of mean intersection over unit (mIoU).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.56-65
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• 2002

This paper proposes a novel transmit diversity technique, namely symbol split orthogonal transmit diversity (SS-OTD). In this technique, full path diversity and temporal diversity are achieved by combining orthogonal transmit diversity technique (OTD) technique with the symbol splitting method proposed by Meyer. Its performances is simulated for fundamental channels associated with the forward link of the IS-2000 system, and then compared with those of OTD and space-time spreading (STS). Our proposed method offers a 0.5-7.7dB performance improvement over OTD under various simulation environments and its performance is similar to STS. Moreover, compares with that of STS, the peak-to-average power ratio (PAR) of transmitted signals in SS-OTD is reduced by a maximal 1.35dB, which decreases the complexity of base station RF devices, such as power amplifiers. Thus, SS-OTD is comparable to STS in performance and superior to STS in the cost and efficiency of base station RF devices.

• School Mathematics
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• v.14 no.2
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• pp.191-212
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• 2012

In the field of arithmetic in mathematics education, there has been lack of fine-grained investigations addressing the relationship between students' construction of division knowledge with fractional quantities and their whole number division knowledge. This study, through the analysis of part of collected data from a year-long teaching experiment, presents a possible constructive itinerary as to how a student could modify her unit-segmenting scheme to deal with various fraction measurement division situations: 1) unit-segmenting scheme with a remainder, 2) fractional unit-segmenting scheme. Thus, this study provides a clue for curing a fragmentary approach to teaching whole number division and fraction division and preventing students' fragmentary understanding of the same arithmetical operation in different number systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1395-1404
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• 2000

In this paper, we propose a heuristic wavelength routing algorithm for IP datagrams in WDM (Wavelength-Division Multiplexing) networks which operates in a distributed manner, while most previous works have focused centralized algorithms. We first present an efficient construction method for a loose virtual topology with a connectivity property, which reserves a few wavelength to cope with dynamic traffic demands properly. This connectivity property assures that data from any source node could reach any destination node by hopping one or multiple lightpaths. We then develop a high-speed distributed wavelength routing algorithm adaptive to dynamic traffic demands by using such a loose virtual topology and derive the general bounds on average utilization in the distributed wavelength routing algorithms. Finally, we show that the performance of the proposed algorithms is better than that of the FSP(Fixed Shortest-Path) wavelength routing algorithms through simulation using the NSFNET[1] and a dynamic hot-spot traffic model, and that the algorithms is a good candidate in distributed WDM networks in terms of the blocking performance, the control traffic overhead, and the computation complexity.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.263-268
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• 1995

A study was undertaken to compare degradation patterns of carbofuran in soils between submerged and upland moisture conditions [$3-^{14}C$]Carbofuran was treated in each soils at the rate of 1.0 mg/kg (87.8 kBq $^{14}C/50g$ soil) and the time-course analysis for distribution of radioactivity and degradation products were conducted. Differences in the pathway and rate of carbofuran degradation in soils were observed between submerged and upland moisture conditiona major degradation being hydrolysis at 7-C position and oxidation at 3-C position, respectively. Carbofuran showed less persistence in soils of higher moisture contents A significant portion, $24{\sim}39%$ of the total radioactivity, resided in soils as nonextractable residues at 60 days after treatment The nonextractable radioactivity was mainly located in soil organic matter, fulvic acid, humic acid and humin factions Gel filtration chromatography confirmed the incorporation of carbofuran and its degradation products into the organic matter.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.339-346
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• 2000

Medical image is analyzed to get an anatomical information for diagnostics. Segmentation must be preceded to recognize and determine the lesion more accurately. In this paper, we propose automatic segmentation algorithm for MR brain images using T1-weighted, T2-weighted and PD images complementarily. The proposed segmentation algorithm is first, extracts cerebrum images from 3 input images using cerebrum mask which is made from PD image. And next, find 3D clusters corresponded to cerebrum tissues using scale filtering and 3D clustering in 3D space which is consisted of T1, T2, and PD axis. Cerebrum images are segmented using FCM algorithm with its initial centroid as the 3D cluster's centroid. The proposed algorithm improved segmentation results using accurate cluster centroid as initial value of FCM algorithm and also can get better segmentation results using multi spectral analysis than single spectral analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.589-595
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• 2011

This paper proposes an improved multi-stage timing offset estimation scheme for orthogonal frequency division multiplexing (OFDM) systems in multipath fading channel environment. The conventional multi-stage timing offset estimation scheme is very sensitive to the random multipath components. By exploiting the sample standard deviation of the cross-correlation values, the proposed scheme achieves a robustness to the random multipath components. Simulation results demonstrate that the proposed scheme has a higher correct estimation probability and has a better mean square error (MSE) performance than the conventional scheme in multipath fading channels.