• ETRI Journal
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• v.37 no.4
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• pp.824-832
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• 2015

Heart sounds are the main obstacle in lung sound analysis. To tackle this obstacle, we propose a diagnosis algorithm that uses singular spectrum analysis (SSA) and frequency features of heart and lung sounds. In particular, we introduce a frequency coefficient that shows the frequency difference between heart and lung sounds. The proposed algorithm is applied to a synthetic mixture of heart and lung sounds. The results show that heart sounds can be extracted successfully and localizations for the first and second heart sounds are remarkably performed. An error analysis of the localization results shows that the proposed algorithm has fewer errors compared to the SSA method, which is one of the most powerful methods in the localization of heart sounds. The presented algorithm is also applied in the cases of recorded respiratory sounds from the chest walls of five healthy subjects. The efficiency of the algorithm in extracting heart sounds from the recorded breathing sounds is verified with power spectral density evaluations and listening. Most studies have used only normal respiratory sounds, whereas we additionally use abnormal breathing sounds to validate the strength of our achievements.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.45-54
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• 1999

Non destructive test is applied to revise mechanical strength and assume material strength or defect of material, equipment and structure, instead of fracture test. Especially, ultrasonic test has the characteristics such as an excellent permeability high-sensitiveness to fine defect and an almost exact measurement for position, size and direction of inner defect which differ from other non destructive tests. In this study, the program is developed to evaluate optimal testing condition, to distinguish obstacle echo and defect position. This program on the basic of Ray-Tracing model shows generation and processing of ultrasonic pulse. The simulation is compared with testing in the 3 cases of an oblique angle transducer like $45^{\circ},\;60^{\circ}\;and\;70^{\circ}$. The test result for all conditions is well compared with simulation result when relative not is within $0.1{\sim}7.2%$. And the course of several echos is simply assumed through simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.593-596
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• 2011

본 논문에서는 안테나 주변 지형 및 장애물들이 전계강도에 미치는 영향을 알아보기 위하여 두가지 주변 지형을 고려한 전계강도 변화를 살펴보았다. 먼저 안테나 주변 지형의 봉우리 유무에 따른 전계강도 변화는 봉우리가 안테나로부터 200m 떨어진 지점에 높이가 40m, 너비가 30m, $60^{\circ}$의 경사를 갖는 지형이고, 다음으로 봉우리 높이에 따른 전계강도 변화는 경사가 $85^{\circ}$이고, 높이가 h 인 봉우리 지형을 갖는 형태로 구현방법으로는 MWS 시뮬레이터를 이용하여 구현하였다.

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.262-262
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• 1990

In order to check the effect of dislocation behavior on creep rate in 12% Chromium steel, 14 samples of different compositions were examined by creep rupture test, and subgrain sizes, distribution of dislocations and precipitates were checked. And, authors reviewed the behaviors of dislocations, the formation and growth of subgrains and precipitates during creep. The results are as the following: 1) Creep rates calculated by .epsilon. over dot = .rho.bv show 10-15% higher values than actual data measured. However, authors conclude that the density and velocity of dislocations together with subgrain size are important factors governing deformation during creep in 12% chromium steel. 2) The values of the strength of obstacles in the mobility of dislocations are more clearly depended on the effective stress in the range of $10{\pm}5kgf/mm^{2}$ and increase with the increase of temperature. 3) Creep rates decrease with the smaller sizes of subgrains formed and can result in the longer creep rupture lives(hours). The smaller subgrains can be made by forming shorter free gliding distances of dislocations with very fine precipitates formed in the matrix during creep by applying proper alloy design. 4) Dislocation mobility gets hindered by precipitates occurring, which are coarsened by the softening process governed by diffusion during long time creep.

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.112-120
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• 1990

In order to check the effect of dislocation behavior on creep rate in 12% Chromium steel, 14 samples of different compositions were examined by creep rupture test, and subgrain sizes, distribution of dislocations and precipitates were checked. And, authors reviewed the behaviors of dislocations, the formation and growth of subgrains and precipitates during creep. The results are as the following: 1) Creep rates calculated by .epsilon. over dot = .rho.bv show 10-15% higher values than actual data measured. However, authors conclude that the density and velocity of dislocations together with subgrain size are important factors governing deformation during creep in 12% chromium steel. 2) The values of the strength of obstacles in the mobility of dislocations are more clearly depended on the effective stress in the range of $10{\pm}5kgf/mm^{2}$ and increase with the increase of temperature. 3) Creep rates decrease with the smaller sizes of subgrains formed and can result in the longer creep rupture lives(hours). The smaller subgrains can be made by forming shorter free gliding distances of dislocations with very fine precipitates formed in the matrix during creep by applying proper alloy design. 4) Dislocation mobility gets hindered by precipitates occurring, which are coarsened by the softening process governed by diffusion during long time creep.

• Asian Journal for Public Opinion Research
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• v.10 no.2
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• pp.102-122
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• 2022

From 2018 to 2020, the United States has repeatedly imposed sanctions on the Chinese company Huawei, which has triggered strong nationalist sentiments on the Chinese Internet. This paper is a qualitative content analysis of Zhihu netizens' views on US sanctions against Huawei to explore how anti-Western centrism influences young people's narratives. The results showed that they believe the Huawei matter is a deliberate hegemonic act by the United States because it fears the decline of its own technological status. Moreover, it is direct evidence that the United States is deliberately destroying China's economic development environment to slow down China's rise, as well as a typical manifestation of the injustice of the liberal international order. A further analysis revealed that their narrative logic is obviously influenced by the following aspects: 1) The mentality of national glory derived from comprehensive national strength leads them to believe that U.S. sanctions against Huawei are an obstacle to China's rise. 2) National humiliation leads them to view U.S. sanctions as a constant insult to China. 3) China's superiority created by China's comprehensive national strength and its scientific and technological achievements in recent years has boosted its confidence to challenge the West's absolute progress. This study examines the impact of anti-Western centrism on Chinese nationalist sentiment and offers a bottom-level perspective on the debate over the crisis of the liberal order.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.954-960
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• 2009

In this paper, Indoor Positioning System based on Wi-Fi system which is one of the key technology in LBS(Location Based Service) is proposed. The proposed system estimates distance between MS(Mobile Station) and AP(Access Point) using RSSI(Received Signal Strength Indicator). RSSI is affected by outlier that originate from indoor environment complexity and obstacle. In this paper, we introduce a Robust outlier Extended Kalman Filter that can ignore, real-time outlier in the observations. To demonstrate performance of proposed indoor positioning system, we used a PDA as the MS.

• Transactions of Materials Processing
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• v.6 no.3
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• pp.213-220
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• 1997

The microstructure of the inconel 690 alloy was varied by the solution treatment and the thermal treatment. The specimens having different microstructures were examined in order to understand the strengthening mechanism of the inconel 690. The level of supersaturation of carbon in the solid solution was increased by applying a longer solution treatment at 115$0^{\circ}C$. As increased carbon content in the solid solution, more carbides precipitated during the thermal treatment at $700^{\circ}C$. Since the carbides played a role of obstacle on the movement of dislocations, a higher tensile strength was obtained in the sample having a large number of carbider. The accumulation of dislocations at the grain boundary carbides caused the development of intergranular fracture which led to a lower elongation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2298-2306
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• 2014

In this paper, we propose an open loop power control algorithm to control transmission power of the On-The-Move(OTM) Satcom terminal in GEO satellite communication environment. The proposed algorithm identifies the current channel state restricted by an obstacle or an antenna depointing loss based on the received beacon signal strength. On the basis of the determined signal attenuation causes, the OTM Satcom terminal turns off the RF output when an antenna tracking is failed. If the OTM Satcom terminal experiences a channel blockage by an obstacle, the terminal spreads the transmit data to increase data reception probability. To evaluate the performance of the proposed algorithm, we compare an adjacent satellite interference level and an outage probability. The results show the performance of the proposed algorithm is better than that of the conventional algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.12
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• pp.1073-1078
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• 2012

This paper deals with the trajectory planning of multi agent robots using complex potential theory for robot soccer. The complex potential theory is introduced, then the circle theorem is used to avoid obstacles, and the vortex pair is used to make precise kicking direction of robot. Various situations of robot soccer are simulated and the effect of vortex strength and the speed of robots are discussed and the better way to avoid obstacles and to kick the precise direction is found. The feasibilities of complex potential theory to apply for the multi agent robots are successful.