• 한국농공학회지
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• 제38권5호
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• pp.74-84
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• 1996

Dynamic loading of structures often causes excursions of stresses well into the inelastic range and the influence of geometric changes on the dynamic response is also significant in many cases. Therefore, both material and geometric nonlinearity effects should be considered in case that a dynamic load acts on the structure. For developing a program to analyze the dynamic response of an axisymmetric shell in this study, the material nonlinearity effect on the dynamic response was formulated by the elasto-viscoplastic model highly corresponding to the real behavior of the material. Also, the geometrically nonlinear behavior is taken into account using a total Lagrangian coordinate system, and the equilibrium equation of motion was numerically solved by a central difference scheme. A complete finite element program has been developed and the results obtained by it are compared with those in the references 1 and 2. The results are in good agreement with each other. As a case study of its application, the developed program was applied to a dynamic response analysis of a nuclear reinforced concrete containment structure. The results obtained from the' numerical examples are summarized as follows : 1. The dynamic magnification factor of the displacement and the stress were unrelated with the concrete strength. 2. As shown by the results that the displacement dynamic magnification factor were form 1.7 to 2.3 and the stress dynamic magnification factor from 1.8 to 2.5, the dynamic magnification factor of stress were larger than that of displacement. 3. The dynamic magnification factor of stress on the exterior surface was larger than that on the interior surface of the structure.

• 한국정보처리학회논문지
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• 제6권4호
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• pp.1136-1142
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• 1999

통상 자동 검사 장치에 있어 대상체가 기준점에서 이동되거나, 크기가 일정한 배율로 확대 축소되거나, 회전되어있을 때에 대상체를 인식 판별하데 어려움이 존재한다. 본 논문에서는 이동, 배율, 회전에 무관한 검사 장치 구현을 위해 로그 적분 변환을 정의하고 그의 특성을 고찰하여 기존의 검사 방법과 비교한다. 로그 적분 변환의 주요한 특성인 배율과 회전에 무관하게 대상체를 인식할 수 있는 특성을 이용하므로 기존 시스템에서 회전 정보 추출을 위한 노력을 감쇄시킬 수 있다. 이동, 배율 및 회전된 물체의 불량 검사에 새로운 방법으로 로그 적분 변환의 적용을 제안하고 이에 따른 인식률 실험을 수행한다. 물론 기존 시스템에서는 배율과 회전에 무관한 조건을 동시에 만족시킬 수 없었다. 불량 검사 실험 결과에 있어 기존의 신경망을 이용한 기존 시스템에 비해 최적의 수준에는 도달하지는 못했지만 로그 적분 변환이 배율과 회전을 동시에 충족시킬 수 있는 변환으로서 사용 가능성을 얻을 수 있었다.

• Archives of Plastic Surgery
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• 제37권4호
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• pp.452-456
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• 2010

Purpose: The schwannoma is a benign peripheral nerve tumor arising from the Schwann cell of the nerve sheath. Only 2-8% of schwannomas arise in the hand and wrist. Misdiagnosis is frequent such as ganglion and neurofibroma. This article documents and clarifies the clinical features of schwannomas arising in the hand and wrist, and emphasizes importance of differential diagnosis and meticulous surgical extirpation under magnification. Methods: The author reviewed clinical features of 15 patients with pathologic final diagnosis of schwannoma developed in hand and wrist during the last 12 years from 1998 through 2009. The review included the sex, age of onset, duration, preoperative diagnosis, location, involved nerve, preoperative symptoms and. Postoperative sequelae after surgical extirpation of the lesion with magnification, or without magnification of the surgical fields. Results: The chief complaints were slow growing firm mass in all patients, and followed by pain in 40%, and paresthesia in 40% respectively. The lesions were developed solitarily in 14 patients (93%). The postoperative pathologic diagnosis and preoperative diagnosis were coincided with only in 6 patients (40%). Other preoperative diagnosis were soft tissue tumor in 4 patient (26.6%), and ganglion in 3 patients (20%), and neurofibroma in 2 patients (13%). In all patients who were undergone surgical excision under the fields of magnification, all symptoms were subsided without any sequelae. Meanwhile muscle weakness, paresthesia, hypoesthesia and /or accidental nerve resection developed after surgical excision with naked eye. Conclusion: Schwannoma in hand most commonly appears as a slow growing solitary mass with pain or paresthesia. The chance of preoperative misdiagnosis was 60% in this series. To provide good prognosis and less sequelae, careful and elaborate diagnostic efforts and meticulous surgical excision under the magnification are necessary in management of schwannoma.

• 대한방사선기술학회지:방사선기술과학
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• 제45권4호
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• pp.313-320
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• 2022

Both angiography and interventional procedures accompanied by angiography provide many diagnostic and therapeutic benefits to patients and are rapidly increasing. However, unlike general radiography or computed tomography using the same X-ray, the amount of radiation is quite high, but the dose range can vary considerably for each patient and operator. The high sensitivity of the lens to radiation during cerebral angiography and neurointervention is already well known, and although there are many related studies, it is insufficient to easily reduce radiation in diagnosis and treatment. In this situation, in particular, by adding three-dimensional rotational angiography (3D-RA) to the existing two-dimensional (2D) angiography, it is now possible to make an accurate diagnosis. However, since this 3D-RA acquires images through projection of more radiation than before, the exposure dose of the lens may be higher. Therefore, we tried to analyze whether the radiation dose of the lens can be reduced by moving the lens out of the field range by adjusting the table height and magnification ratio during the examination using 3D-RA. The surface dose was measured using a rando phantom and a radiophotoluminescent glass dosimeter (PLD) and the radiation dose was compared by adjusting the table height and magnification ratio based on the central point. As a result, it was found that the radiation dose of the lens decreased as the table height increased from the central point, that is, as the lens was out of the field of view. In conclusion, in 3D-RA, moving the table position of about 2 cm in height will make a significant contribution to the dose reduction of the lens, and it was confirmed that adjusting the magnification ratio can also reduce the surface dose of the lens.

• 한국소음진동공학회논문집
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• 제16권11호
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• pp.1165-1171
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• 2006

This paper presents a new type of jetting dispenser for the integrated circuit (IC) fabrication and surface mount technology The proposed system is featured by the piezoelectric actuator and hydraulic magnification device. After describing structural component of the dispensing mechanism and its operation principle, both the fluid modeling and the hydraulic magnification modeling are undertaken with a lumped-parameter method based on the analogy of the fluid system and mechanical system. A mathematical governing equation is then derived by integrating the fluid model with the mechanical model of the driving piston and piezoelectric actuator. Subsequently, in order to achieve a desired dispensing amount, control algorithm adjusting duty cycle of the driving voltage is synthesized and control responses are presented in time domain.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.428-433
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• 2006

This paper presents a new type of jetting dispenser for the integrated circuit(IC) fabrication and surface mount technology. The proposed system is featured by the piezoelectric actuator and hydraulic magnification device. After describing structural component of the dispensing mechanism and its operation principle, both the fluid modeling and the hydraulic magnification modeling are undertaken with a lumped-parameter method based on the analogy of the fluid system and mechanical system. A mathematical governing equation is then derived by integrating the fluid model with the mechanical model of the driving piston and piezoelectric actuator. Subsequently, in order to achieve a desired dispensing amount, control algorithm adjusting duty cycle of the driving voltage is synthesized and control responses are presented in time domain.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.173-176
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• 2005

This study look into the mechanisms of growth and magnification in the cracks and delamination on the beams repaired with CFS. The experimental parameters was a loading type, loading speed and pre-crack. In the experiments, it was confirmed that the failure of beams began with development and propagation of the delamination in the below the loading point due to magnification of cracks, but it was not concerned with loading type, loading speed and pre-cracks. Particularly, in the case of beams having the pre-cracks, growth of crack concentrated at the special crack below the loading point and led to failure of the beam by delamination due to magnification of crack.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1402-1404
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• 2000

The electrified railway has various power supply schemes. Although the identical trains are operated in same condition and the impedance of track are equal, the genealogy impedance of track is changed according to composition method of feeding scheme. So, the harmonic current flowing into the railway substation are greatly unlike. For simulation of harmonic magnification flowing into the railway substation according to feeding scheme, we propose 6-port network analysis method based on 4-port network, find 6-port equivalent model of each circuit component, and compare and investigate harmonic magnification in the case of parallel post and normal feeding scheme.

• 치과방사선
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• 제9권1호
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• pp.19-23
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• 1979

A study was made primarily to investigate vertical and horizontal distortion of the image at the apical region of the dental roots in orthopantomographs. The subjects consisted of two dry skulls with radiopaque materials attached to root surface. Measuring of the width and length of each predetermined point at 23 teeth was performed in dry skulls and radiographic films. The results obtained were as follows; 1. There was overall magnification of image in the vertical dimension. And anterior portion had greater magnification rate than posterior portion, while lower anterior portion had less magnification rate than upper anterior portion. 2. There was reduction of the image in the horizontal dimension of the teeth, because of the position relation between dry skull and image layer of the orthopantomograph. 3. There was a significant difference in distortion rate between the oposite teeth. 4. Cervical portion of the tooth had more decreased rate of horizontal distortion than apical portion.

• 한국방사선학회논문지
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• 제17권1호
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• pp.167-173
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• 2023

일반 X-선 검사는 간단하고 많은 정보를 얻을 수 있어 가장 기본이 되는 검사방법이며 획득된 영상에서는 인체 해부학적 구조와 시간 경과에 따른 질병의 변화 정보를 쉽게 획득할 수 있다. 그럼에도 불구하고 영상이 확대되는 단점으로 인하여 병변의 크기와 형태가 왜곡되어 나타나기 때문에 현재 X-선 영상의 깊이 있는 관찰은 이루어지지 않고 있다. 본 연구에서는 후전촬영(PA)과 측방향촬영(LAT) 영상을 획득하고 각각의 영상에서 암 시료가 위치하는 거리를 측정하여 암 시료의 확대율을 계산하고 측정한 암 시료 길이에 보정한다. 암 시료의 길이와 두께에 따른 확대율 보정 값을 전산화단층촬영장치(Computed Tomography, CT)로 획득된 영상 및 실제 제작한 암 시료 크기와 각각 비교하였다. 기존의 확대율은 검출기에서 암의 거리를 측정하여 계산할 수 있었으나 본 연구에서는 획득된 PA와 LAT 영상을 이용하여 확대율을 계산하였다. 6 mm 암 시료를 PA와 LAT 영상을 획득하여 확대율을 구한 후 보정한 결과 길이는 5.9 mm, 두께는 6.1mm로 실제와 비슷한 값이 측정되었으며 영상을 이용한 확대율 계산이 가능하다는 것을 알 수 있었다. X-선 영상만으로도 병변의 확대율을 손쉽게 보정하여 정확한 길이 측정이 가능하고 이는 영상 판독 및 정확한 진단에 유용한 정보를 제공할 것이다.