• Journal of Korean Neurosurgical Society
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• 제49권1호
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• pp.26-30
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• 2011

Objective: The primary objective of this study was to perform a retrospective evaluation of the radiological and pathological features influencing the formation of peritumoral brain edema (PTBE) in meningiomas. Methods: The magnetic resonance imaging (MRI) and pathology data for 86 patients with meningiomas, who underwent surgery at our institution between September 2003 and March 2009, were examined. We evaluated predictive factors related to peritumoral edema including gender, tumor volume, shape of tumor margin, presence of arachnoid plane, the signal intensity (SI) of the tumor in T2-weighted image (T2WI), the WHO histological classification (GI, GII/GIII) and the Ki-67 antigen labeling index (LI). The edema-tumor volume ratio was calculated as the edema index (EI) and was used to evaluate peritumoral edema. Results: Gender (p=0.809) and pathological finding (p=0.084) were not statistically significantly associated with peritumoral edema by univariate analysis. Tumor volume was not correlated with the volume of peritumoral edema. By univariate analysis, three radiological features, and one pathological finding, were associated with PTBE of statistical significance: shape of tumor margin (p=0.001), presence of arachnoid plane (p=0.001), high SI of tumor in T2WI (p=0.001), and Ki-67 antigen LI (p=0.049). These results suggest that irregular tumor margins, hyperintensity in T2WI, absence of arachnoid plane on the MRI, and high Ki-67 LI can be important predictive factors that influence the formation of peritumoral edema in meningiomas. By multivariate analysis, only SI of the tumor in T2WI was statistically significantly associated with peritumoral edema. Conclusion: Results of this study indicate that irregular tumor margin, hyperintensity in T2WI, absence of arachnoid plane on the MRI, and high Ki-67 LI may be important predictive factors influencing the formation of peritumoral edema in meningiomas.

• 한국멀티미디어학회논문지
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• 제6권3호
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• pp.419-428
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• 2003

어떤 물체 영역의 골격(skeleton)을 얻기 위해 세건화(thinning)하는 과정에서 잔가지(parasitic branch)가 발생하므로, 이러한 것을 효과적으로 제거하기 위한 여러 가지 연구가 이루어져 왔다. 이중에서 잔가지가 한 픽셀 두께의 가지로 나타나는 속성에 착안하여, 윤곽선 추적에 의한 대칭 경로(symmetric path)를 검출함으로써 잔가지를 제거하는 방법이 매우 효과적인 것을 알 수 있었다. 본 연구에서는, 이 방법을 영상 분할이나 연결 요소 추출 등에 의해 구해진 물체 영역의 윤곽선 부분에 나타나는 잡영가지 (noise branch)를 제거하는데 활용할 수 있도록 개선한 방법을 제안한다. 즉, 한 픽셀 두께의 잡영가지 뿐만 아니라, 부분적으로 두 픽셀 이상이 뭉쳐져 둥그스름한 덩어리(잡영블랍, noise blob)를 형성하고 있는 잡영가지도 제거할 수 있는 개선된 방법을 제안한다. 대칭 경로를 찾기 위해 4-8방향 윤곽선 추적 알고리즘을 이용하며, 잡영블랍이 포함된 경우에는 준대칭(quasi-symmetric) 경로를 정의하여 추출한다. 제안한 방법의 시간 복잡도는 윤곽선 픽셀수의 선형 함수로 표현되며, 사용자가 잡영블랍과 잡영가지의 크기를 임의로 설정하도록 하여 융통성있고 다양하게 잡영가지를 제거할 수 있도록 하였다. 실제 형상과 인위적 형상에 대한 실험을 통해 제안된 방법의 유용성을 확인할 수 있었다.

• Structural Engineering and Mechanics
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• 제34권6호
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• pp.719-738
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• 2010

The aim of this paper concerns with the nonlinear analysis of cable-stayed bridges including the vibration effect of cable stays. Two models for the cable stay system are built up in the study. One is the OECS (one element cable system) model in which one single element per cable stay is used and the other is MECS (multi-elements cable system) model, where multi-elements per cable stay are used. A finite element computation procedure has been set up for the nonlinear analysis of such kind of structures. For shape finding of the cable-stayed bridge with MECS model, an efficient computation procedure is presented by using the two-loop iteration method (equilibrium iteration and shape iteration) with help of the catenary function method to discretize each single cable stay. After the convergent initial shape of the bridge is found, further analysis can then be performed. The structural behaviors of cable-stayed bridges influenced by the cable lateral motion will be examined here detailedly, such as the static deflection, the natural frequencies and modes, and the dynamic responses induced by seismic loading. The results show that the MECS model offers the real shape of cable stays in the initial shape, and all the natural frequencies and modes of the bridge including global modes and local modes. The global mode of the bridge consists of coupled girder, tower and cable stays motion and is a coupled mode, while the local mode exhibits only the motion of cable stays and is uncoupled with girder and tower. The OECS model can only offers global mode of tower and girder without any motion of cable stays, because each cable stay is represented by a single straight cable (or truss) element. In the nonlinear seismic analysis, only the MECS model can offer the lateral displacement response of cable stays and the axial force variation in cable stays. The responses of towers and girders of the bridge determined by both OECS- and MECS-models have no great difference.

• 한국측량학회지
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• 제29권6호
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• pp.593-599
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• 2011

지리정보에 대한 사용자의 활용도가 높아지면서 더 새롭고 고품질인 지리정보 자료에 대한 요구 역시 함께 증가하고 있다. 새로운 콘텐츠를 제작하는데 있어 기 구축된 자료간의 융합을 통한 방법은 기존의 자료들이 가진 장점만을 취하여 새로운 지리정보 콘텐츠를 생성할 수 있다는 점에서 효율적이다. 그러나, 서로 다른 자료를 융합하면 위치편차와 형상불일치가 나타나는데 이는 이종의 자료가 가진 정보의 정확도는 그대로 유지한 채 자료 간 불일치되는 부분을 개선하는 합성 기술로 해결이 가능하다. 본 연구에서는 선행연구를 통해 위치편차가 최소화된 도로지도와 항공사진간에 형상불일치를 제거하는 것을 목적으로 하여 항공사진에서 도로 후보 영상을 생성한 후 이를 도로일 가능성으로 표현한 그래프를 제작하였다. 여기서 도로일 가능성이 높은 것만을 추출하여 합성 시 형상불일치를 제거할 수 있었다.

• 대한물리의학회지
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• 제2권2호
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• pp.125-134
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• 2007

Purpose : This study is to determine effects of cane-shape which influenced on the change of muscle activation, gait component in hemiplegic patients caused by cerebrovascular accident. Methods : Twenty one stroke patients using T-shape cane(TCG) and twenty one stroke patients using I-shape cane(ICG) participated in this study. Surface electromyography(SEMG) of erector spinae, transvers abdominis, tibialis anterior, soleus of both side were measured during walking without cane and walking with cane. Results : The activation of tibialis anterior was significantly increased in affected side of ICG. The activation of tibialis anterior was significantly decreased in affected side of TCG. The activation of soleus was significantly increased in affected side of ICG. The activation of soleus was significantly decreased in affected side of TCG. The activation of erector spinae was significantly increased in nonaffected side of ICG and TCG. The activation of transvers abdominis was significantly increased in nonaffected side of ICG and TCG. Conclusion : From the finding of this study, it was suggested that I-shape cane increase weight bearing of affected side in hemiplegic patient. Therefore, I-shape cane can be applied to improve gait asymmetry of hemiplegic patients.

• 제어로봇시스템학회논문지
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• 제9권11호
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• pp.925-936
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• 2003

The manipulability analysis of the parallel-type rolling mill proposed in Hong et al. [1] is re-visited. The parallel rolling mill uses two Stewart platforms in opposite direction for the generation of 6 degree-of-freedom motions of each roll. The objective of this new parallel rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of rolls, and tension of the strip. New forward/inverse kinematics problems, in contrast with [1], are formulated. The forward kinematics problem is defined as the problem of finding the roll-gap and the pair-crossing angle of two work rolls for given lengths of twelve legs. On the other hand, the inverse kinematics problem is defined as the problem of finding the lengths of twelve legs when the roll-gap, the pair-crossing angle, and the position and orientation of one work roll are given. The method of manipulability analysis used in this paper follows the spirit of [1]. But, because the rolling force and moment exerted from both upper and lower rolls have been included in the manipulability analysis, more accurate results than the use of a single platform can be achieved. Two. kinematic parameters, the radius of the base and the angle between two neighboring joints, are optimally designed by maximizing the global manipulability measure in the entire workspace.

• 대한간호학회지
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• 제43권3호
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• pp.431-441
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• 2013

Purpose: The study was done to explore meanings and essence of the experience in South Korea of men defectors from North Korea. Methods: Data were collected from March, 2011 to May, 2012, through in-depth interviews with ten men defectors. Data analysis was conducted using the process of hermeneutic phenomenological reflection. Results: Eight essential themes were extracted; 'buoyant expectation for a new life', 'feeling guilty about family left behind in North Korea', 'inability to become acclimatized due to communication difficulties', 'inability to socialize with South Koreans due to different lifestyles', 'finding strength through trustworthy acquaintances', 'continuing reconciliation with oneself while trying to assimilate into South Korean culture', 'self-realization of one's original self', and 'continuing to feel out the possibility of a future in South Korea'. Conclusion: The findings indicate that North Korean men who defect to South Korea shape their identity through three phases: forming self-image during escape from North Korea, trying to become accustomed to South Korean society, and finding their own identity by self-realization of their original self. Eventually, the whole process enables them to recover their identity, to feel a sense of belonging, and to discover possibilities for a better future.

• 한국컴퓨터정보학회논문지
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• 제23권4호
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• pp.57-64
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• 2018

In this paper, we propose the automatic detection method for individual region separation using panorama image. Finding areas that contain individual teeth is one of the most important tasks in automating 3D models through individual tooth separation. In the conventional method, the maxillary and mandibular teeth regions are separated using a straight line or a specific CT slide, and the tooth regions are separated using a straight line in the vertical direction. In the conventional method, since the teeth are arranged in a curved shape, there is a problem that each tooth region is incorrectly detected in order to generate an accurate tooth region. This is a major obstacle to automating the creation of individual tooth models. In this study, we propose a method to find the correct tooth curve by using the jawbone curve which is very similar to the tooth curve in order to overcome the problem of finding the area containing the existing tooth. We have proposed a new method to accurately set individual tooth regions using the feature that individual teeth are arranged in a direction similar to the normal direction of the tooth alignment curve. In the proposed method, the maxillary and mandibular teeth can be more precisely separated than the conventional method, and the area including the individual teeth can be accurately set. Experiments using real dental CT images demonstrate the superiority of the proposed method.

• 한국컴퓨터정보학회논문지
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• 제24권6호
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• pp.57-65
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• 2019

In this paper, we study on finding the rail space in elevators by analyzing each image captured with CCD camera. We propose a method that applies one-dimensional matched filter to the pixels of a selected search space in the vertical line at a horizontal position and decides the position with the thickness of the space being represented by a black thick line in captured images. The pattern similarity representing how strongly the associated image pixels resemble with the thick line is defined and calculated with respect to each position along the vertical line of pixels. The position and thickness of the line are decided from the point having the maximum in pattern similarity graph. In the experiments of the proposed method under different illuminational conditions, it is observed that all the pattern similarity graphs show similar shape around door area independent of the conditions and the method can effectively detect the rail space if the rails are illuminated with even weak light. The method can be used for real-time embedded systems because of its simple algorithm, in which it is implemented in simple structure of program with small amount of operations in comparison with the conventional approaches using Canny edge detection and Hough transform.

• 대한조선학회논문집
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• 제54권1호
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• pp.18-25
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• 2017

This study deals with numerically comparing performance according to rudder shape called 'Twisted rudder and Wavy twisted rudder'. In comparison with conventional rudder, rudder with wavy shape has showed a better performance at high angles of attack($30^{\circ}{\sim}40^{\circ}$) due to delaying stall. But most of study concerned with wavy shape had been performed in uniform flow condition. In order to identify the characteristics behind a rotating propeller, the present study numerically carries out an analysis of resistance and self-propulsion for KCS with twisted rudder and wavy twisted rudder. The turbulence closure model, Realizable $k-{\epsilon}$, is employed to simulate three-dimensional unsteady incompressible viscous turbulent and separation flow around the rudder. The simulation of self-propulsion analysis is performed in two step, because of finding optimization case of wavy shape. The first step presents there are little difference between twisted rudder and case of H_0.65 wavy twisted rudder in delivered power. So two kind of rudders are employed from first step to compare lift-to-drag ratio and torque at high angles of attack. Consequently, the wavy twisted rudder is presented as a possible way of delaying stall, allowing a rudder to have a better performance containing superior lift-to-drag ratio and torque than twisted rudder at high angles of attack. Also, as we indicate the flow visualization, check the quantity of separation flow around the rudder.