• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.65-70
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• 2001

We consider a hyper-redundant system that consists of many uniform units. The hyper-redundant system has many degrees of freedom and it can accomplish various tasks. Applysing the reinforcement learning to the hyper-redundant system is very attractive because it is possible to acquire various behaviors for various tasks automatically. In this paper we present a new reinforcement learning algorithm "Q-learning with propagation of motion". The algorithm is designed for the multi-agent systems that have strong connections. The proposed algorithm needs only one small Q-table even for a large scale system. So using the proposed algorithm, it is possible for the hyper-redundant system to learn the effective behavior. In this algorithm, only one leader agent learns the own behavior using its local information and the motion of the leader is propagated to another agents with time delay. The reward of the leader agent is given by using the whole system information. And the effective behavior of the leader is learned and the effective behavior of the system is acquired. We apply the proposed algorithm to a snake-like hyper-redundant robot. The necessary condition of the system to be Markov decision process is discussed. And the computer simulation of learning the locomotion is demonstrated. From the simulation results we find that the task of the locomotion of the robot to the desired point is learned and the winding motion is acquired. We can conclude that our proposed system and our analysis of the condition, that the system is Markov decision process, is valid.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.174-180
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• 2002

A virtual reality technology for multipurpose numerical simulation is developed to reproduce and investigate a variety of ocean environmental problems in a 3D-Numerical Wave Tank. The governing equations for solving incompressible fluid motion are Navier-Stokes equation and continuity equation, and the Marker-Density function technique is adopted to implement the fully-nonlinear free-surface kinematic condition. The marine environmental situations, i.e. waves, currents, wind, etc., are reproduced by use of multi-segmented wavemaker on the basis of the so-called "snake-principle". In this paper, some numerical reproduction techniques for regular and irregular waves, multi-directional waves, Bull's-eye wave, wave-current, and solitary wave are presented, and a model test in motion with large amplitude of roll angle is conducted in the developed 3D-NWT, using a overlaid grid system.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.4
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• pp.266-277
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• 2023

In this study, fundamental research is conducted for the generation technique and analysis of multi-directional irregular waves in the Deep Ocean Engineering Basin (DOEB). A three-dimensional boundary element method-based numerical tank is implemented to perform wave generation simulations, and directional spectrum estimation is carried out using the results of simulations. The wave generation technique of the Snake type wave maker, generating multi-directional irregular waves, is implemented using the Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) algorithms. The wave generation technique is validated by comparing the wave spectrum from simulations and experiments. A Maximum Likelihood Method (MLM) based estimation code is developed for estimating the directional wave spectra. The multi-directional irregular waves are tested in the DOEB and the numerical tank, and directional wave spectra obtained from two methodologies are estimated and compared. A correction procedure for the directional distribution of multi-directional waves is established, and the possibility of correcting the directional spreading function using the numerical tank is validated.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.451-454
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• 2001

본 논문에서는 그룹화 블록스네이크와 영상분할을 이용하여 다차선을 검출하고 컬러 정보를 기반으로 차량 후면에 위치하는 미등과 브레이크등을 인식, 저속 주행환경에서의 다차선 및 전방차량을 인식하는 알고리즘을 제안하였다. 제안한 알고리즘에서는 기울기 값과 명암도 값으로 기초 블록을 얻은 뒤, 차선의 가능성이 큰 블록을 탐색하여 영상분할을 시행한다. 영상 분할에서 잡음 블록들을 제거하여 차선일 가능성이 가장 높은 블록들만을 검출하고, 그룹화 블록스네이크를 이용하여 차선을 검출하도록 하였다. 또한 전방 차량인식을 위해 미등과 브레이크등의 컬러 특징을 이용하여 후보 영역을 분할한 후, 미등과 브레이크등의 패턴의 기하학적 특징과 위치적 특징을 이용하여 한 쌍의 미등 혹은 브레이크등을 탐지하도록 하였다. 탐지된 양쪽 등의 위치정보를 이용하여 전방차량의 위치를 측정 할 수 있다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.4
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• pp.167-175
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• 2006

This paper presents a method to segment semiconductor wafer ID on poor quality images. The method is based on multiple templates and normalized gray-level correlation (NGC) method. If the lighting condition is not so good and hence, we can not control the image quality, target image to be inspected presents poor quality ID and it is not easy to identify and then recognize the ID characters. Conventional several method to segment the interesting ID regions fails on the bad quality images. In this paper, we propose a multiple template method, which uses combinational relation of multiple templates from model templates to match several characters of the inspection images. To find out the optimal solution of multiple template model in ID regions, we introduce newly-developed snake algorithm. Experimental results using images from real FA environment are presented.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.939-942
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• 2000

본 논문에서는 블록 스네이크와 영상 분한을 이용한 차선 검출 알고리즘을 제안한다. 제안한 알고리즘에서는 기울기값과 명암도값으로 차선이 존재 할 가능성이 가장 높은 기초 블록을 얻고, 기초블록으로부터 차선일 가능성이 높은 블록을 탐색하여 영상 분할을 수행한다. 영상 분할에서 일정한 기울기와 명암도를 가지는 잡음 블록들을 제거하여 차선일 가능성이 가장 높은 블록들만이 검출되고, 그룹 블록 스네이크를 이용하여 잡음이 제거된 차선을 효과적으로 검출하는 방법을 제시한다.

• Tuberculosis and Respiratory Diseases
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• v.83 no.3
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• pp.201-210
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• 2020

Background: North Korea is one of the 30 countries with the highest tuberculosis (TB) and drug-resistant TB burdened. To understand the medical issues and research trends associated with TB in North Korea, we performed a comprehensive review of articles related to clinical and laboratory research on TB published in North Korean medical journals. Methods: We reviewed all types of TB-related articles published in nine North Korean medical journals (Yebang ŭihak: Preventive medicine; Koryo ŭihak: Korea Medicine; Chosŏn ŭihak: Chosun Medicine; Naekwa: Internal Medicine; Soa, sanbuinkwa: Pediatrics, Obstetrics, and Gynecology, Surgery; Ŭihak: Medicine; Kich'o ŭihak: Basic Medicine; and Chosŏn yakhak: Chosun Pharmacy). We classified the articles according to the type and field of study and analyzed the data qualitatively to gain insights. Results: We reviewed 106 articles (one- or two-page length) written in Korean, including reviews (n=43), original articles (n=52), and case reports (n=8). They were classified as follows: articles on diagnosis (n=52, 49%) and treatment (n=39, 37%). None of the studies investigated the commercialized molecular diagnosis systems such as Xpert MTB/RIF. Directly Observed Treatment, Short-course was reported as the basic treatment approach. Furthermore, six studies used Korean traditional medicines for treating TB, with one of them containing snake venom. Conclusion: The articles were not sufficiently detailed. Original articles on the treatment of multi-drug resistant TB were not found, and those on latent tuberculosis infection and nontuberculous mycobacteria were limited. To understand the current medical issues associated with TB in North Korea, articles from these nine journals were not sufficient.

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.266-274
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• 2009

An abdominal aortic aneurysm occurs most commonly in older individuals (between 65 and 75), and more in men and smokers. The most important complication of an abdominal aortic aneurysm is rupture, which is most often a fatal event. An abdominal aortic aneurysm weakens the walls of the blood vessel, leaving it vulnerable to bursting open, or rupturing, and spilling large amounts of blood into the abdominal cavity. surface modeling is very useful to surgery for quantitative analysis of abdominal aortic aneurysm. the 3D representation and surface modeling an abdominal aortic aneurysm structure taken from Multi Detector Computed Tomography. The construction of the 3D model is generally carried out by staking the contours obtained from 2D segmentation of each CT slice, so the quality of the 3D model strongly defends on the precision of segmentation process. In this work we present deformable model algorithm. deformable model is an energy-minimizing spline guided by external constraint force. External force which we call Gradient Vector Flow, is computed as a diffusion of a gradient vectors of gray level or binary edge map derived from the image. Finally, we have used snakes successfully for abdominal aortic aneurysm segmentation the performance of snake was visually and quantitatively validated by experts.