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.

방사선 치료중인 암환자의 임상적 특징과 정신과 장애의 관련성

김호찬,문창우,박시성,Kim, Ho-Chan,Moon, Chang-Woo,Park, Si-Sung 한국정신신체의학회 1999 정신신체의학 Vol.7 No.1

연구목적 : 암환자에서는 암의 임상적 특성이나, 치료방법에 따라 다양한 심리적인 문제들이 발생한다. 특히 방사선 치료는 다른 방법의 치료를 받는 환자들에서 볼 수 없는 다른 심리적 반응을 보이는 경우가 많으며, 정서적 고통과 갈등이 가중될 수 있다. 이에 저자들은 방사선 치료중인 암환자들에게는 어떠한 정신과 장애가 발생하는지 알아보고, 정신과 질환이 암과 관련된 다양한 임상적 특성과 어떠한 연관성을 지니는지 알아보고자 본 연구를 시행하였다. 방법 : 방사선 치료를 위해 치료방사선과에 입원한 암환자 47명을 대상으로 하여. DSM-IV 진단기준에 따라 정신과 장애를 평가하고, 환자들의 인구학적 자료, 암의 부위, 이환기간, 재발횟수 등의 임상적 특성, 암환자의 암에 대한 인지여부, 치료결과에 대한 기대 등의 요인과 정신과 장애의 관련성을 살펴보았다. 결과 : 1) 21 명(44.7%)의 환자가 정신과 장애를 가지고 있었다. 적응장애가 14명(66.7%)으로 가장 많았고, 다음은 5명(23.8%)의 환자에서 동반된 주요 우울장애였다. 2) 성별, 연령, 학력, 결혼상태, 종교 등의 인구학적 변인과 정선과적 장애와의 관련성은 통계적 유의성을 보이지 않았다. 3) 암의 부위별로는 골반부에 위치하는 암이 22명(46.8%)으로 가장 많았으며, 암의 부위, 이환기간과 정신과 장애와의 유의한 관련성은 없었다. 4) 암의 재발에 있어 재발의 증거가 없는 경우에 비해 재발한 경우 통계적으로 유의하게 정신과 장애의 이환율이 높았다. 5) 암의 인지여부와 정신과 장애는 통계적으로 유의한 연관은 없었다. 6) 치료결과에 대한 기대와 관련하여, 방사선 치료가 단지 보조적인 것으로 생각하는 군이 방사선치료에 의해 완치될 것으로 생각하는 군에 비해 통계적으로 유의하게 정신과 장애의 이환율이 높았다. Objects : Cancer patients receiving radiotherapy have many psychological problems. Those problems depend on clinical factors of cancer and the characteristics of patients. This study was designed to estimate the morbidity of psychiatric disorder and to investigate the relationship between psychiatric disorders and clinical variables. Methods : The subjects were 47 patients who had been treated by radiotherapy. Psychiatric disorder was diagnosed according to DSM-IV. The authors assessed the relation between psychiatric disorder and demographic features, clinical features of cancer such as site, duration, frequency of recurrence of cancer, and patients' awareness of disease and expectation of outcome of radiotherapy. Results : 21 patients(44.7%) had a psychiatric disorder. The most common psychiatric disorder were adjustment disorder(66.7%), and the next major depressive disorder(23.8%). There was a significant positive relationship between psychiatric disorder and recurrence of cancer, patients' expectation of poor outcome after radiotherapy. Psychiatric morbidity was significantly low in those who had no evidence of recurrence and who considered radiation treatment as curative. However, site and duration of cancer, patients' awareness about serious illness were not related with psychiatric disorder. Conclusion : Psychiatric disorders are common among cancer patients on radiotherapy. Further clinical attention and effective treatment of psychiatric complication in cancer patients are needed not only for reducing symptoms but for better adjustment.

Electrical Resistance Tomography의 영상복원 기법의 비교

김호찬,부창진,이윤준,Kim, Ho-Chan,Boo, Chang-Jin,Lee, Yoon-Joon 한국조명전기설비학회 2005 조명·전기설비학회논문지 Vol.19 No.3

Electrical resistance tomography(ERT)는 적절하게 설계된 전류를 대지 지하에 주입하여 이에 따른 인가전압을 대지 경계에서 측정한 후 이를 근거로 ERT의 영상복원 알고리즘에서 대지 지하의 대지저항률 분포를 얻고 대지 지하에 뭍힌 물체를 크기와 위치, 그리고 저항률에 대한 특성을 파악할 수 있는 기술이다. 본 논문에서는 ERT의 영상복원 기법으로 Gauss-Newton, TLS와 SIRT 방법들을 살펴본다. 컴퓨터 시뮬레이션을 통해 TLS 방법을 이용한 ERT 영상복원의 성능이 Gauss-Newton와 SIRT방법에 의해 얻어진 결과보다 향상되는 것을 보이도록 한다. Electrical resistance tomography(ERT) maps resistivity values of the soil subsurface and characterizes buried objects. The characterization includes location, size and resistivity of buried objects. In this paper, Gauss-Newton, truncated least squares(TLS) and simultaneous iterative reconstruction technique(SIRT) methods are presented for the solution of the ERT image reconstruction. Computer simulations show that the spatial resolution of the reconstructed images by the TLS approach is improved as compared to those obtained by the Gauss-Newton and SIRT method.

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.

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.

불안정한 시스템을 대상으로 닫힌 형태의 그래미언을 사용한 MBR 방법

金豪贊(Ho-Chan Kim),崔悰鎬(Chong-Ho Choi),吳尙綠(Sang-Rok Oh),金光培(Kwang-Bae Kim) 대한전기학회 1995 전기학회논문지 Vol.44 No.9

파킨슨 증상을 보이는 치매

김호찬(Ho Chan Kim),김성환(Seong Hwan Kim) 대한노인정신의학회 2007 노인정신의학 Vol.11 No.2

Parkinson's disease (PD) is a extrapyramidal movement disorder characterized by rigidity and bradykinesia. PD is one of the most common neurodegenerative disorders, affecting 1% of the population over the age of 60. Dementia is common and affects 40% of patients with PD during the course of the disease, the risk for the development of dementia being 6 times higher than in age-matched general population. In addition to motor abnormalities, there are several non-motor signs and symptoms that may create a considerable burden for patients and caregivers. Parkinsonism is a major feature of several dementing diseases. The parkinsonian disorders with dementia are Parkinson's disease dementia (PDD), parkinsonian-plus syndromes, sepcific heredodegenerative diseases, and secondary parkinsonisms. The parkinsonian-plus syndromes are neurodegenerative disorders charaterized by parkinsonism and at least one other nonparkinsonian neurological manfestation. This brief review concentrates on those disorders in which cognitive impairment/dementia and parkinsonism coexist:Parkinson's disease dementia, progressive supranuclear palsy, and corticobasal degeneration. The clinical and neuropsychological similarities and differences in these disorders are compared and contrasted along with Alzheimer's disease, Parkinson's disease, and dementia of Lewy bodies, highlighting the features critical for identifying the correct diagnosis.

분산형 제품개발 시스템의 구축을 위한 SOAP의 활용

김호찬(Ho-Chan Kim),안대건(Dae-Keon Ahn),이석희(Seok-Hee Lee) 한국자동차공학회 2003 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-

Better understanding and sharing information are getting important to manage interdisciplinary product development team in a globally-distributed company. This study propose a solution to implement RPD(Rapid Product Development) system, focusing on rapid production process, for better understanding between development team members in different place and easy sharing of product information. The system developed by this research shows that SOAP(Simple Object Access Protocol) operates in distributed environment more efficiently than other RPC(Remote Procedure Call) techniques and it does not respond sensitively to firewall. And SOAP is an excellent RPC and messaging technique to exchange structured data. Procedures developed with use of SOAP are worked together with web, and users can use remote services as an application program in their computer.

풍력발전시스템에서의 LQG 제어에 관한 연구

김호찬(Ho-Chan Kim) 대한전기학회 1999 대한전기학회 학술대회 논문집 Vol.1999 No.7

시뮬레이티드 어닐링을 이용한 전기임피던스단층촬영법의 영상복원

金豪贊(Ho-Chan Kim),夫唱眞(Chang-Jin Boo),李潤俊(Yoon-Joon Lee) 대한전기학회 2003 전기학회논문지 D Vol.52 No.2