• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권11호
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• pp.2754-2768
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• 2013

Video fingerprints generated from global features are usually vulnerable against general geometric transformations. In this paper, a novel video fingerprinting algorithm is proposed, in which a new spatio-temporal gradient is designed to represent the spatial and temporal information for each frame, and a new partition scheme, based on concentric circle and rings, is developed to resist the attacks efficiently. The centroids of spatio-temporal gradient orientations (CSTGO) within the circle and rings are then calculated to generate a robust fingerprint. Our experiments with different attacks have demonstrated that the proposed approach outperforms the state-of-the-art methods in terms of robustness and discrimination.

• 한국재료학회지
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• 제23권8호
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• pp.453-461
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• 2013

Controlling the stick and slip motions of the contact lines in a confined geometry comprised of a spherical lens with a flat substrate is useful for manufacturing polymer ring patterns. We used a sphere on a flat geometry, by which we could control the interfaces of the solution, vapor and substrate. By this method, hundreds of concentric ring-pattern formations of a linear conjugated polymer, poly [2-methoxy-5-(2-thylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), were generated with excellent regularity over large areas after complete solvent evaporation. Subsequently, the MEH-PPV ring patterns played a role as a directed template to organize highly regular concentric rings of single-walled carbon nanotubes(SWCNTs); when a droplet of the SWCNT suspension in water was casted onto the prepared substrate, hydrophobic polymer patterns confined the water dispersed SWCNTs in between the hydrophilicized $SiO_2/Si$ substrate. As the solvent evaporated, SWCNT-rings were formed in between MEH-PPV rings with controlled density. Finally, we used a lift-off process to produce SWCNT patterns by the removal of a sacrificial polymer template with organic solvent. We also fabricated a field effect transistor using self-assembled SWCNT networks on a $SiO_2/Si$ substrate.

• Earthquakes and Structures
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• 제22권6호
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• pp.539-548
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• 2022

Steel plate shear walls (SPSWs) are one of the most important and widely used lateral load-bearing systems. The reason for this is easier execution than reinforced concrete (RC) shear walls, faster construction time, and lower final weight of the structure. However, the main drawback of SPSWs is premature buckling in low drift ratios, which affects the energy absorption capacity and global performance of the system. To address this problem, two groups of SPSWs under cyclic loading were investigated using the finite element method (FEM). In the first group, several series of circular rings have been used and in the second group, a new type of SPSW with concentric circular rings (CCRs) has been introduced. Numerous parameters include in yield stress of steel plate wall materials, steel panel thickness, and ring width were considered in nonlinear static analysis. At first, a three-dimensional (3D) numerical model was validated using three sets of laboratory SPSWs and the difference in results between numerical models and experimental specimens was less than 5% in all cases. The results of numerical models revealed that the full SPSW undergoes shear buckling at a drift ratio of 0.2% and its hysteresis behavior has a pinching in the middle part of load-drift ratio curve. Whereas, in the two categories of proposed SPSWs, the hysteresis behavior is complete and stable, and in most cases no capacity degradation of up to 6% drift ratio has been observed. Also, in most numerical models, the tangential stiffness remains almost constant in each cycle. Finally, for the innovative SPSW, a relationship was suggested to determine the shear capacity of the proposed steel wall relative to the wall slenderness coefficient.

• 한국동물학회지
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• 제16권1호
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• pp.43-53
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• 1973

年齡에 따른 미토콘드리아의 構造的變化를 調査하기 위하여 電子顯微鏡을 利用하여 배추흰나비, Pieris rapae L.의 飛筋을 觀察하였다. 미토콘드리아는 크리스타가 잘 발달되지 않은 A型과 크리스타가 복잡하게 발달된 B型의 두種類가 存在하였다. 羽化直後의 것에서는 A型과 B型미토콘드리아가 꼭같이 存在하였고 羽化後 10日 經過한 것에서는 B型미토콘드리아에 比하여 A型이 急速히 減少하였다. 羽化後 10日이 經過된 것의 筋細胞에서는 B型미토콘드리아가 年齡의 增加에 따른 微細構造的變化를 이르켰다. 이러한 老衰된 미토콘드리아의 微細構造的 變化像은 部分的으로 그 內膜이 髓　狀構造를 再形成하는 것으로 나타났는데 이것은 곧 年齡에 따른 退化를 意味한다. 髓　狀構造를 形成하는 것은 많은 同心圓體이며 이 同心圓體의 數와 크기는 年齡과 比例하면서 增加했다. 筋細胞의 細胞質에서 미토콘드리아 內로 侵入한 글리코겐 粒子는 同心圓體의 中央에서도 觀察되었다.

• 한국정보과학회논문지:정보통신
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• 제37권5호
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• pp.409-414
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• 2010

무선 센서 네트워크에서 센서노드의 지리적인 위치를 요구하는 응용들이 현저하게 증가하고 있다. 최근 다양한 위치 측위 알고리즘들이 제안 되었지만, 대부분의 알고리즘은 특정한 하드웨어로 얻은 RSSI와 LQI 측정치를 기반으로 위치를 추정하고 있다. 본 논문에서는 이러한 추가적인 정보를 이용하지 않아도 기존 연구와 근사한 측정 결과를 얻을 수 있는 '가중 다중 링을 이용한 측위' 알고리즘 WMRL(Weighted Multiple Rings Localization)을 제안한다. 고정노드(anchor nodes)들이 배치되어 있으며, 각 고정노드는 주기적으로 서로 다른 신호 세기의 비콘(beacon) 신호를 송출한다고 가정한다. 그러면, 비콘 신호는 공간상에 링을 형성하게 되며, 파워 레벨의 세기에 따라 다수의 동심원을 형성하는 동시에 링 간에 교차영역을 생성한다. 본 논문에서는 효율적인 측위 계산을 위해 각 링의 거리 비율에 따른 가중치 모텔을 제안한다. 또한, 센서노드는 수신이 가능한 고정노드로부터 가장 가까운 링을 발견할 수 있으며, 이를 활용하여 센서노드는 자신의 위치를 고정노드 좌표의 가중 합으로 구한다. 제안된 알고리즘은 분산적으로 위치를 계산할 수 있으며, 추가적인 하드웨어를 요구하지 않는다. 추가적으로, 비 신뢰적인 RSSI 및 LQI에 의존하지 않고, 각 링 간의 거리 비율로 측위가 가능한 것이 특정이다. 그럼에도 불구하고, WMRL은 시뮬레이션 결과 2개의 링, 즉 2개의 파워 레벨로 구성하였을 경우에는 기존의 centroid 방식보다 평균 측위 에러가 2배 감소하였고, 3개의 링을 구성하였을 경우에는 WCL(Weighted Centroid Localization)과 대등한 측위 결과를 보였다.

• 대한기관식도과학회지
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• 제10권2호
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• pp.63-67
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• 2004

Tracheomalacia can be a life threatening upper air way obstructive disease in an infant and vascular rings can be also a major rare cause of tracheoesophageal obstruction. These two rare entities can be combined in one patient because the vascular ring can cause secondary tracheomalacia during development of fetus. The diagnosis of this combination and adequate surgical correction is occasionally difficult. This is a report of an infant who had not diagnosed tracheomalacia associated with vascular ring until 5 months of age because of the prolonged tracheal intubation. The rigid bronchoscopic examination performed under impression of tracheomalacia revealed a concentric tracheal collapse, an unusual bronchoscopic findings of tracheomalacia, which raised a suspicion of the tracheal compression by vascular rings. The 3-D reconstructive DT aortography clearly demonstrated the double aortic arch. The patient was treated surgically by simple division of the left aortic arch and aortopexy with good result. The vascular ring such as double aortic arch should be considered during the diagnosis of tracheomalacia in infants. If the tracheomalacia is associated with vascular ring, simultaneous surgical correction should be performed.

• 한국정밀공학회지
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• 제29권3호
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• pp.324-333
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• 2012

The conventional medium and large caliber gun, in general, utilize the hydro-pneumatic recoil mechanism to control the firing impulse and to return to the battery position. However, this kind of mechanism may cause the problems like the leakages and the property changes in oil and gas due to the temperature variations between low and high temperatures. Accordingly, the friction spring mechanism has recently been researched as an alternative system. The friction spring mechanism consists of a set of closed inner and outer rings with the concentric tapered contact surfaces assembled in the columnar form, and can only be used under the compression load. When the spring column is axially loaded, the tapered surfaces become overlapped, causing the outer rings to expand while the inner rings are being contracted in diameter allowing an axial displacement. Because of friction between tapered contact surfaces, much higher spring stiffness is obtained on the stroke at the increase in load than the stroke at the decrease. In this paper, the dynamic equations regarding the friction spring system and the design approach have been investigated. It is also tried for a dynamic model representing the recoil motion and the friction spring forces. And the model has been proved from firing test using a gun system with friction springs. All the results show that the recoil mechanism using friction springs can substitute for the classic hydro-pneumatic recoil system.

• 식물병연구
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• 제21권4호
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• pp.330-333
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• 2015

In June 2013, we collected leaf spot disease samples of Datura metel from Gangneung, Gangwon Province, Korea. The symptoms observed were small circular to oval dark brown spots with irregular in shape or remained circular with concentric rings. We isolated the pathogen from infected leaves and cultured the fungus on potato dextrose agar. We examined the fungus morphologically and confirmed its pathogenicity according to Koch's postulates. The results of morphological examinations, pathogenicity tests, and the rDNA sequences of the internal transcribed spacer regions (ITS1 and ITS4), glycerol-3-phosphate dehydrogenase (G3PDH) and the RNA polymerase II second largest subunit (RPB2) gene sequence revealed that the causal agent was Alternaria tenuissima. To the best of our knowledge, this is the first report of leaf spot of D. metel caused by A. tenuissima in Korea as well as worldwide.

• Journal of information and communication convergence engineering
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• 제8권5호
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• pp.484-488
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• 2010

In this paper, we present a novel tunable microstrip bandpass filter based on split ring resonators (SRRs). The varactors are reverse-biased semiconductor diode, and are connected between the concentric rings of the SRR. An individual varactor loaded SRR based bandpass tunable filter module is analyzed. Then a second order tunable filter with 7% fractional bandwidth and a tuning range from 2.75 to 2.86 GHz is assembled from basic filter modules. The simulator HFSS (V10) is used to design the tunable filter and to simulate. The results show good characteristics is created.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.267-271
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• 1987

The test cell for preventing the edge effect reducing the intrinsic breakdown strength of polypropylene film and measuring the intrinsic breakdown strength of the film was developed. The new approach was to develope an electrode system with an edge region which is carefully graded over an extended distance. The new test arrangement employed a central circular electrode at high voltage and a set of nine concentric surrounding rings each controlled in potential by external grading resistors to be at decreasing potentials from that at the center in 10% increments. Two different size structures using the same basic principle were tried and were both found to be successful. The test electrodes were manufactured using standard printed circuit technology and were chosen to be copper on high dielectric constant GIO board.