역공학에서의 Delaunay 삼각형 분할에 의한 STL 파일 생성

김호찬,허성민,이석희 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.5

Estimation of kernel function using the measured apparent earth resistivity

김호찬,부창진,강민제 한국인터넷방송통신학회 2020 Journal of Advanced Smart Convergence Vol.9 No.3

In this paper, we propose a method to derive the kernel function directly from the measured apparent earth resistivity. At this time, the kernel function is obtained through the process of solving a nonlinear system. Nonlinear systems with many variables are difficult to solve. This paper also introduces a method for converting nonlinear derived systems to linear systems. The kernel function is a function of the depth and resistance of the Earth's layer. Being able to derive an accurate kernel function means that we can estimate the earth parameters i.e. layer depth and resistivity. We also use various Earth models as simulation examples to validate the proposed method.

SPSA를 이용한 전기 임피던스 단층촬영법의 영상복원

김호찬,부창진,이윤준 제주대학교 공과대학 첨단기술연구소 2002 尖端技術硏究所論文集 Vol.13 No.2

Electrical impedance tomograpy(EIT) determines the resistivity distribution inside an inhomogeneous target by means of voltage and current measurements conducted at the target boundary. In this paper, a simultaneous perturbation stochastic approximation(SPSA) approach is proposed for the solution of the EIT image reconstruction. Results of numerical experiments of EIT solved by the SPSA approach are presented and compared to that obtained by the modified Newton-Raphson(mNR) method.

부품방향의 선정을 통한 광조형물의 후가공면적 최소화

김호찬,이석희,Kim, Ho-Chan,Lee, Seok-Hee 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11

The surfaces of prototypes become rough due to the stair-stepping which is the inevitable phenomenon in the Rapid Prototypes are not used only for the verification of feature. The grinding, coating, or the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. The solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. the solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the regions for post-processing. the factors to cause the surface roughness and their effects are analyzed through the experiments. Software modules are developed to predict the surface roughness of each face in the prototyping with the result. An experimental compensation method is developed to apply the modules to various RP equipments, materials and build styles. The build direction is searched with use of genetic algorithm to maximize the total areas of the surface of which roughness is better than the user-defined value.

정신분열병의 급성기 및 관해기에서의 신경인지 결손에 관한 연구

김호찬,김철권,박내권,최병무 大韓神經精神醫學會 2001 신경정신의학 Vol.40 No.5

연구목적 : 본 연구는 정신분열병 환자에게서 보이는 다양한 신경인지 결손이 병의 증상 때문인지 아니면 질병 자체의 취약성 때문인지를 알아보기 위한 것이다. 방 법 : 42명의 정신분열병 환자를 대상으로 정신증적 증상이 심한 급성기와 증상이 호전된 관해기에 고난도 지속수행검사(Continuous Performance Test)를 이용한 지속적 주의력, 정보 감지능력검사(Span apprehension Task)를 이용한 초기 시각 정보처리능력, 위스콘신 카드분류검사(Wisconsin Card Sorting Test)를 이용한 통합능력, 숫자 주의력(Digit Span)을 이용한 주의집중력, 그리고 레이 청각 언어성 학습검사(Rey Auitory Verbal Learning Test)를 이용한 언어성 기억 및 학습 등을 반복 측정하여 그 결과를 정상 대조군과 비교하였다. 정상 대조군은 환자군과 성별, 나이, 학력 등에 유의한 차이가 없고 정신과적 병력이 없는 일반인 35명으로 하였다. 결 과 : 지속적 주의력, 초기 시각 정보처리능력, 통합능력, 언어성 기억 및 학습 등에서 정신분열병 환자군은 정상 대조군에 비하여 급성기와 관해기 모두에서 대부분 유의한 결손을 보였다. 그러나 주의집중력에서는 급성기때 환자군은 정상 대조군에 비하여 거꾸로 따라 외우기에서는 유의한 수행저하를 보였지만 관해기때는 두군간에 바로 따라 외우기와 거꾸로 따라 외우기 모두에서 유의한 차이를 보이지 않았다. 지속적 주의력, 초기 시각 정보처리능력, 통합능력, 언어성 기억 및 학습에서 정신분열병 환자군은 급성기와 관해기 간에 모두 유의한 변화를 보이지 않았다. 그러나 주의 집중력에서 환자군은 급성기에 비하여 관해기때 바로 따라 외우기와 거꾸로 따라 외우기 모두 유의한 향상을 보였다. 결 론 : 난이도가 높은 과제에 대한 주의력 또는 정보처리 능력은 안정적 취약지표일 가능성이 높다. 위스콘신 카드분류검사를 통해 알 수 있는 통합능력에서의 결손은 증상 또는 삽화지표가 아닐 가능성이 높지만, 그렇다고 단정적으로 안정적 취약지표라고 결론짓기는 어렵다. 숫자 주의력의 경우에는 바로 따라 외우기와 거꾸로 따라 외우기의 작용기전이 다를 가능성이 있으며, 바로 따라 외우기는 삽화지표일 가능성이 높은 반면 거꾸로 따라 외우기는 증상의 영향을 부분적으로 받는 중재적 취약지표일 가능성이 높다. 언어성 기억 및 학습 결손에서는 일부 형태의 기억이 증상과는 무관한 안정적 취약지표일 가능성이 높다. Objectives : The purpose of this study is to examine whether the neurocognitive deficits of schizophrenia may be associated with certain features of symptomatology or a stable vulnerability of disease itself. Method : The 42 schizophrenic patients and 35 matched normal controls with sex, age, and education level were examined for their sustained attention, sensory register, executive function, concentration and attention, and verbal memory and learning in the acute and remitted stages of schizophrenia using Degraded Stimulus Continuous Performance Test, Span Apprehension Task, Wisconsin Card Sorting Test, Digit Span, and Rey Auditory Verbal Learning Test, respectively. Results : The schizophrenic patients showed significant deficits in the sustained attention, sensory register, executive function, and verbal memory and learning compared with the normal controls in both acute and remitted stages of schizophrenia. Regarding the concentration and attention, the schizophrenic patients showed significant deficits in the backward digit span compared with the normal controls during acute stages, bet there was no difference between two groups in the forward and backward digit span during remitted stages. No difference was evident in the sustained attention, sensory register, executive function, and verbal memory and learning between acute and remitted stages of schizophrenia. But the forward and backward digit span of schizophrenic patients showed significant improvement in the remitted stages compared with acute stages. Conclusions : The sustained attention and sensory register deficit in the visual information processing associated with schizophrenia, detected by high-processing-load version of the Degraded Stimulus Continuous Performance Test and span Apprehension Task, are highly possible to be stable vulnerability indicators. Executive functioning deficit in the schizophrenic patients detected by Wisconsin Card Sorting Test is not likely to be dependent on symptoms, so it is difficult to conclude that it is a stable vulnerability indicators of schizophrenia. In the digit span task, the forward digit span is more likely to be a episodic indicator but the backward digit span is likely to be a mediating vulnerability indicator. And the forward and backward digit span tasks seem to be tap different cognitive abilities that are differentially associated with the diathesis for schizophrenia. Some forms of the verbal memory and learning deficits associated with schizophrenia appear to be a stable vulnerability indicators.

네비게이션을 이용한 비밸브 기능저하의 원인 규명과 치료 1예

김호찬,조용태,김지선 대한이비인후과학회 부산,울산,경남 지부회 2018 임상이비인후과 Vol.29 No.2

Nasal valve compromise (NVC) is a distinct cause of symptomatic nasal obstruction, yet there are several ambiguities surrounding the diagnosis and management of this disease. Understanding of nasal valve anatomy with critical assessment of the site of obstruction is essential to effective nasal valve management. Technique selection should be individualized to the type of valve dysfunction. This case report presents a 56 year old man with nasal valve dysfunction due to narrow middle vault, concave lower lateral cartilage and swollen septal body which was diagnosed by various techniques including navigation system and treated by spreader graft, alar batten graft and reduction of septal body.

선형 SISO 시스템의 공분산 배치이론에 관한 연구

김호찬 濟州大學校 工科大學 産業技術硏究所 1998 尖端技術硏究所論文集 Vol.9 No.1

In this paper, an alternate method for state-covariance assignment for SISO(single input single output) linear systems is proposed. This method is based on the inverse solution of the Lyapunov matrix equation and the resulting formulas are similar in structure to the formulas for pole placement. Further, the set of all assignable covariance matrices to a SISO linear system is also characterized.

시뮬레이티드 어닐링을 이용한 전기임픽던스단층촬영법의 영상복원

김호찬,부창진,이윤준,Kim Ho-Chan,Boo Chang-Jin,Lee Yoon-Joon 대한전기학회 2003 전기학회논문지 D Vol.52 No.2

In electrical impedance tomography(EIT), various image reconstruction algorithms have been used in order to compute the internal resistivity distribution of the unknown object with its electric potential data at the boundary. Mathematically the EIT image reconstruction algorithm is a nonlinear ill-posed inverse problem. This paper presents a simulated annealing technique as a statistical reconstruction algorithm for the solution of the static EIT inverse problem. Computer simulations with the 32 channels synthetic data show that the spatial resolution of reconstructed images by the proposed scheme is improved as compared to that of the mNR algorithm or genetic algorithm at the expense of increased computational burden.

Multi-Jet Modeling 3차원 프린트를 위한 표면거칠기와 제작시간의 저감을 위한 모델 분할제작

김호찬,이인탁,이경창,이석,이석희,Kim, Ho-Chan,Lee, In-Tak,Lee, Kyung-Chang,Lee, Suk,Lee, Seok-Hee 대한기계학회 2003 大韓機械學會論文集A Vol.27 No.5

3D printers are widely used to verify the designs in the early stage of product development, and are required to have short build time. However, the build time is still too long for a quick design review for engineers. This research focuses on how to split the prototype in order to reduce the build time and improve surface roughness. In order to verify the feasibility of prototype splitting, the build time and the roughness have been experimentally measured for various parts and build orientations. Based on the experimental results an expert system was developed for splitting the original CAD mod el by using an efficient splitting method. It can recommend a splitting plane based on build time, surface roughness and the number of divided parts. It is shown that the model splitting reduces the build time significantly and improves surface quality wit bout rough surfaces where the support was removed.

특수관계자와의 주식매매시의 시부인에 관한 소고

김호찬 경희대학교 경영행정대학원 세무관리학과 학생회 1972 慶稅論叢 Vol.1 No.-