• 한국정보처리학회논문지
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• 제5권5호
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• pp.1320-1332
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• 1998

본 논문은 동적인 초고속 통신망상에서 신뢰성 있는 그룹통신 플랫폼을 위한 가상위상 Multiph를 제안하고 메시지 전송 프리미티브와 동적인 그룹관리 프리미티브를 정의하였다. Multiph는 그래프와 같이 정점과 간선으로 구성된다. Mutiph의 정점은 프로세스 그룹을 의미한다. 간선은 각 정점들간의 연결로 프로세스 그룹간의 메시지 통로를 의미한다. 메시지를 송수신하는 프로세스가 여러개의 멀티캐스트 그룹에 중복된 경우에는 중복된 프로세스들을 중복이 없는 논리적 프로세스 그룹으로 구성한다. 이것을 메타그룹(meta-group)이라 한다. 메타그룹으로 형성된 멀티캐스트 그룹을 Multiph로 구성한다. Multiph는 하이퍼트리(hypertree)[2] 형태의 그래프 구조이다. Multiph는 동일한 그룹에 도착하는 메시지들에 대한 순서성(ordering)을 보장한다. 또한, Multiph는 다른 논리적 구조에서 메시지 전송의 효율을 저하시키는 추가 노드를 가지고 있지 않다. 그리고 프로세스의 가입과 탈퇴 등 그룹의 동적인 변화에 대하여도 처음 구성된 플랫폼의 구조를 새로 재구성하지 않는다.

• 한국통신학회논문지
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• 제21권4호
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• pp.926-938
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• 1996

In this paper, we proposed a new multicast algorithm which is efficiently applicable to overlapped process group environments where one process may be involved in several process groups. Unlike the esisting algorithms, the proposed one provides an efficient group communication mechanism by generating the processgroup information in two-level tree. Using this algorithm, we improved the shortcoming of the existing algorithms by reducing the overhead in passing through unnecessary processes for message ordering. We have provided the causal ordering method as well as the total ordering method in group communication environments. As a result, we allow one process to deliver message to other processes with a short delay time, and reduced the overhead required for the message ordering. Also, we logically proved the proposed causal ordering method, and compared the performance of the proposed algorithm with ones of other existing algorithms by computer simulation.

• 인터넷정보학회논문지
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• 제11권4호
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• pp.11-22
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• 2010

센서 네트워크와 같이 각 프로세스의 관심사에 따라 여러 개의 멀티캐스트 그룹들로 나누어질 수 있는 시스템에서 모든 프로세스들이 하나의 대규모 그룹에서 발생하는 모든 이벤트에 관심이 있다고 전제하는 경우, 각각의 프로세스에 대해 매우 높은 그룹 통신 프로토콜의 오버헤드를 발생시킬 수 있다. 특히, 센서 혹은 P2P 네트워크에서 그룹 통신의 멀티캐스트를 위해 가쉽 기반의 통신을 사용할 때, 메시지 전달 순서 보장과 중복 그룹에 대한 지원이 매우 필요한 속성인데, 이와 관련된 요구조건들을 만족하는 가쉽 통신 프로토콜 개발에 대한 연구가 거의 없다. 따라서, 본 논문에서는 지역 뷰와 서브그룹의 대표자에 기반하고 중복 그룹의 특성을 최대한 활용한 매우 확장적인 새로운 가쉽 기반 인과적 메시지 순서 보장 멀티캐스트 프로토콜을 제안한다. 본 논문의 프로토콜은 중복된 그룹 간의 메시지에 대한 상호 의존적 속성을 대표자들도 포함된 해당 그룹 내의 모든 멤버들에 의해 보장한다. 그리하여, 지역 뷰에만 의존하여 완전히 분산화된 방법으로 메시지 전달의 속성을 보장하는 확률적인 프로토콜보다 매우 엄격하고, 대표자 그룹의 계층적 멤버리스트로써 원자적 속성을 보장하는 가쉽 기반의 프로토콜과 비교하면 매우 확장적이다. 또한, 그룹의 멤버리스트를 포함한 모든 메시지는 가쉽 기반 통신을 사용함으로써 멀티캐스트 본래의 확장성을 향상시킬 수 있는 하이브리드한 방법이다.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1445-1450
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• 2002

In the present study, a new pattern recognition algorithm was proposed to size spray particles using the boundary curvature information. Conceptually, this algorithm has an advantage over the others because it can identify the particle size and shape simultaneously, and also can separate the overlapped particles more effectively. Curvature of a boundary was obtained from the change of the slopes of two neighboring segments at the corresponding part. The algorithm developed in this study was tested by using an artificially prepared image of a group of spherical particles which were either isolated or overlapped. Particle sizes obtained from the measured curvatures agreed well with the true values. By detecting abrupt changes of the curvature along the image boundary, the element particles could be separated out from their overlapped images successfully.

• Smart Structures and Systems
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• 제30권1호
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• pp.75-88
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• 2022

Engineering structures in operation essentially belong to time-varying or nonlinear structures and the resultant response signals are usually non-stationary. For such time-varying structures, it is of great importance to extract time-dependent dynamic parameters from non-stationary response signals, which benefits structural health monitoring, safety assessment and vibration control. However, various traditional signal processing methods are unable to extract the embedded meaningful information. As a newly developed technique, variational mode decomposition (VMD) shows its superiority on signal decomposition, however, it still suffers two main problems. The foremost problem is that the number of modal components is required to be defined in advance. Another problem needs to be addressed is that VMD cannot effectively separate non-stationary signals composed of closely spaced or overlapped modes. As such, a new method named generalized adaptive variational modal decomposition (GAVMD) is proposed. In this new method, the number of component signals is adaptively estimated by an index of mean frequency, while the generalized demodulation algorithm is introduced to yield a generalized VMD that can decompose mode overlapped signals successfully. After that, synchrosqueezing wavelet transform (SWT) is applied to extract instantaneous frequencies (IFs) of the decomposed mono-component signals. To verify the validity and accuracy of the proposed method, three numerical examples and a steel cable with time-varying tension force are investigated. The results demonstrate that the proposed GAVMD method can decompose the multi-component signal with overlapped modes well and its combination with SWT enables a successful IF extraction of each individual component.

• 한국의류학회지
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• 제42권6호
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• pp.1056-1068
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• 2018

This study investigates whether women's wear brands' sizing systems reflect the body size and shape of their target age customers. This study classified 17 women's wear brands into three target age groups (20-30s, 30-40s, and 40-50s) and surveyed their body sizing systems for jacket items. The distribution of bust circumference and hip circumference of brands' sizing systems were compared with the size distribution of women in the 7th SizeKorea data. The brands targeting 20-30s fully produced five sizes which are the highest coverage rate, but the brands targeting 30-40s produced three sizes, and the brands targeting 40-50s produced one size. Regarding the body types, 60.0% of 20-30s target brands and 42.9% of 30-40s target brands reflected N type which is the average body type of each age group. However, the rest of the brands, including all 40-50s target brands, reflected A type which covered small portions of women. For each age group, 6 sizes with 24.0-29.0% coverage rates were proposed. With regard to the 88-94 size, three age groups overlapped: the 82-91 size was overlapped between the 20-30s and the 30-40s groups along with the 85-91 and 88-91 sizes that overlapped between the 30-40s and 40-50s groups.

• Journal of Chest Surgery
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• 제10권1호
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• pp.7-17
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• 1977

The increasing frequency of post-tracheostomy stenosis parallels the increase in the incidence of tracheostomy. The development of stenosis of trachea following the operation of tracheal tumor or tracheostomy is a very serious complication. The continuing need for an adequate tracheal substitute has not been answered, despite the necessities of excision and reconstruction of the trachea to keep for effective ventilation. Experimental tracheal reconstuction, with a prosthesis of heavy Marlex mesh and pericardium, _ vas performed in twelve dogs. Five to six tracheal ring circumferential defects were created and were bridged with heavy Marlex mesh fashioned into a tube of suitable diameter. Group A: A prepared cylinder of Marlex mesh was anastomosed outside the cut ends of the trachea. Group B: The external surface of the prepared cylinder of Marlex mesh was completely covered with suitably sized patch of pericardium and overlapped all margin of the Marlex mesh by 2 to 3 mm in each direction. Group C: The internal surface of the prepared cylinder of Marlex mesh was covered with suitably sized patch of pericardium and overlapped all margin of the Marlex mesh by 2 to 3 mm in each direction. The results of this exepriment were as follow: 1. In group A and B, the graft was well bridged with new granulation and fibrous tissue, and the lumen of trachea kept good patency for effective ventilation.. The interstices of Marlex became uniformly infiltrated with young well vasculated connective tissue. Epithelization has not yet occurred at 4 weeks in each group, but there were evidences of new growing mucosa at grafted site in 6 weeks. The remainder of the prosthesis was completely covered with glistening epithelium and the underlying fibrous tissue became more matured with little inflammation. These findings were more striking in group B than group A. 2. In group C, the covered pericardium was necrotized with stenosis of the lumen of grafted site due to poor blood supply.

• Journal of Positioning, Navigation, and Timing
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• 제12권3호
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• pp.245-255
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• 2023

Time comparison techniques are necessary for generating and keeping Coordinated Universal Time (UTC) and distributing standard time clocks. Global Navigation Satellite System (GNSS) Common View, GNSS All-in-View, Two-Way Satellite Time and Frequency Transfer (TWSTFT), Very Long Baseline Interferometry (VLBI), optical fiber, and Network Time Protocol (NTP) based methods have been used for time comparison. In these methods, GNSS based time comparison techniques are widely used for time synchronization in critical national infrastructures and in common areas of application such as finance, military, and wireless communication. However, GNSS-based time comparison techniques are vulnerable to jamming or interference environments and it is difficult to respond to GNSS signal disconnection according to the international situation. In response, in this paper, Code-Division Multiple Access (CDMA) based All-to-All TWSTFT operation method is proposed. A software-based simulation platform also was designed for performance analysis in multi-TWSTFT signal environments. Furthermore, code and carrier measurement jitters were calculated in multi-signal environments using the designed simulation platform. By using the technique proposed in this paper, it is anticipated that the TWSTFT-based time comparison method will be used in various fields and satisfy high-performance requirements such as those of a GNSS master station and power plant network reference station.

• Investigative Magnetic Resonance Imaging
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• 제11권1호
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• pp.33-38
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• 2007

목적: 반얼굴 연축 환자에서 새로운 삼차원 중첩 자기공명 혈관 조영술 기법(3-D overlapped reconstruction MR angiographic technique, 3-D ORMRA) 을 기존의 MRA 원천영상과 비교하여 그 유용성을 알아보고자 하였다. 대상 및 방법: 수술로 반얼굴 연축이 증명된 총 27명을 대상으로 하였다. 모든 환자에서 전향적으로 기존의 MRA 원천영상과 3-D fast imaging employing steady state acquisition (FIESTA) 영상을 얻었다. 이 후 작업대 (workstation)에서 3-D MRA 영상을 만들고 GE A/W 4.2 add/sub software를 이용하여 이를 FIESTA영상과 겹쳐 3-D ORMRA영상을 얻었다. 그리고 나서 기존의 MRA 원천영상과 3-D ORMRA영상에서 각 각 얼굴신경의 신경근출구부와 병적 압박혈관 사이의 관계를 분석하였다. 결과: 기존의 MRA원천영상에서는 27명중 25명의 환자에서 얼굴 신경근출구부에서의 병적 압박혈관을 구별 할 수 있었고, 3-D ORMRA영상에서는 모든 환자에서 병적 압박혈관을 구별 할 수 있었으며, 이는 수술소견과 일치하였다. 무엇보다 3-D ORMRA영상에서 얼굴 신경근출구부와 병적 압박혈관 사이의 공간적인 관계를 좀 더 분명하게 볼 수 있었다. 결론: 3-D ORMRA 기법은 기존의 MRA 영상기법과 비교하여, 반얼굴 연축 환자에서 매우 유용하고 더 정확한 정보를 주는 방법이다.