• 핵의학기술
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• 제18권1호
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• pp.94-97
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• 2014

PET/CT 영상에서 표준섭취계수(Standardized uptake value, SUV)는 간단한 반정량적인 방법으로 정상 조직과 종양 조직의 섭취 비를 측정하여 임상에서 육안적인 평가와 함께 유용하게 사용되고 있지만 많은 변수들로 인해 SUV에 영향을 주게 된다. 그 중 혈관 삽입기구나, 주사 부위의 잔여 방사능과 그 위치에 따라서 영향을 평가해 보고자 한다. GE Discovery 600 (GE Healthcare, MI, USA)과 NEMA IEC Body Phantom을 사용하였다. $^{18}F-FDG$ 5.7 kBq/mL를 물과 함께 phantom에 채웠고, 22 mm 직경의 구에 7.4, 14.8, 22.2, 29.6, 37, 55.5 MBq로 변화하여 SFOV에 포함, 불포함 그리고 끝단에 걸쳐진 조건으로 시뮬레이션 하였다. 획득된 영상에 관심영역을 설정하여 SUV에 미치는 영향을 비교 평가하였다. SFOV 포함 여부에 따라 구분한 3 그룹에서 방사능량에 상관없이 SFOV에 포함되지 않은 것이 가장 높은 SUV를 나타내었으며, 끝단에 걸친 것, 포함된 순으로 SUV의 변화가 있었다. 이중 구의 방사능량이 7.4 MBq의 경우 SFOV에 포함과 끝단에 걸친 위치의 경우 평균 SUV는 0.780, 0.840로 나왔으며 SFOV 밖에 위치 할 경우 0.896이 나왔다. 22.2 MBq과 55.5 MBq의 SUV는 동일한 순서대로 0.600, 0.700, 0.728, 0.372, 0.460, 0.508로 나왔으며, 구의 잔여방사능량에 따라 최소 10.4% 최대 62.8% 차이를 보였다. 본 연구를 통해 혈관삽입기구에 잔여 방사능이 많이 남아 있을수록 SUV를 과소평가하였다. 또한 SFOV에 포함여부에 따라서도 SUV의 변화가 있었으며, 포함되지 않았을 때 가장 적은 차이를 알 수 있었다. 추후에 혈관 삽입 기구 내 잔여 방사능과 환자의 혈관외 누출에 따른 방사능을 측정 할 수 있다면 임상에 더욱 도움이 되리라 사료된다.

• Journal of International Society for Simulation Surgery
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• 제1권1호
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• pp.13-15
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• 2014

Nowadays, with advanced 3D printing techniques, the custom-made implant can be manufactured for the patient. Especially in skull reconstruction, it is difficult to design the implant due to complicated geometry. In large defect, an autograft is inappropriate to cover the defect due to donor morbidity. We present the process of manufacturing the 3D custom-made implant for skull reconstruction. There was one patient with skull defect repaired using custom-made 3D titanium implant in the plastic and reconstructive surgery department. The patient had defect of the left parieto-temporal area after craniectomy due to traumatic subdural hematoma. Custom-made 3D titanium implants were manufactured by Medyssey Co., Ltd. using 3D CT data, Mimics software and an EBM (Electron Beam Melting) machine. The engineer and surgeon reviewed several different designs and simulated a mock surgery on 3D skull model. During the operation, the custom-made implant was fit to the defect properly without dead space. The operative site healed without any specific complications. In skull reconstruction, autograft has been the treatment of choice. However, it is not always available and depends on the size of defect and donor morbidity. As 3D printing technique has been advanced, it is useful to manufacture custom-made implant for skull reconstruction.

• Journal of Computational Design and Engineering
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• 제3권4호
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• pp.363-369
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• 2016

Cyber Physical System (CPS) and Internet of Things (IoT) are hot objects of interest as an extension of the embedded system. These interactive products and systems contain Mobile Devices which are most popular and used most frequently. Also these have been widely used from the control of the Nuclear Power Control System (NPCS) to IoT Home Service. Information & Communication Technology (ICT) topics of trend fused-complex current Information Technology (IT) and Communication Technology (CT) are closely linked to real space and virtual space. This immediately means the arrival of the ultra-connected society. It refers to a society in which various objects surrounding the human innovation and change in the social sector are expected through the connection between the data which are to be generated. In addition, studies of Tool-kit for the design of such systems are also actively pursued. However, only increased cooperation and information sharing between the physical object consists of a variety of machinery and equipment. We have taken into consideration a number of design variables of the high barriers to entry about the product. In this study, It has been developed a Web-based collaboration framework which can be a flexible connection between macroscopically virtual environment and the physical environment. This framework is able to verifiy and manage physical environments. Also it can resolve the bottlenecks encountered during the base expansion and development process of IoT (Internet of Things) environment.

• 한국주조공학회지
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• 제35권4호
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• pp.80-87
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• 2015

The Al die casting process has been widely used in the manufacturing of automotive parts when the process requires near-net shape casting and a high productive rate. However, porosity arises in the casting process, and this hampers the wider use of this method for the creation of high-durability automotive components. The porosity can be controlled by the shot condition, but, it is critical to set the shot condition in the sleeve, and it remains difficult to optimize the shot condition to avoid air entrapment efficiently. In this study, the 4.5 mm, 2.0 mm plate die castings were fabricated under various shot conditions, such as plunger velocities of 0.7 m/s ~ 3.0 m/s and fast shot set points of the cavity of -25%, 0%, 25%, and 50%. The mold filling behavior of Al melts in the cavity was analyzed by a numerical method. Also, according to the shot conditions, the results of numerical analyses were compared to those of die-casting experiments. The porosity levels of the plate castings were analyzed by X-ray CT images and by density and microstructural analyses. The effects of the porosity on the mechanical properties were analyzed by tensile tests and hardness tests. The simulation results are in good general agreements with the die-casting experimental results. When plunger velocity and fast shot set point are 1.0 m/s and cavity 25% position, castings had optimum condition for good mechanical properties and a low level of porosity.

• 한국산업융합학회 논문집
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• 제24권5호
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• pp.589-596
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• 2021

In this study, the optimum gating system was designed, and the two zinc alloy worm gears were manufactured in single process by applying a symmetrical gating system with 2 runners. The SRG ratio is set to 1 : 0.9 : 0.6, and the cross-sectional shapes such as sprue, runner and gate are designed. In order to determine whether the design of the gating system is appropriate, casting analysis was carried out. It takes 4.380 s to charge the casting 100%, 0.55 to 0.6 m/s at the gates and solidification begins after the casting is fully charged. The amount of air entrapment is 2% in the left gear and 6% in the right gear. Hot spots occurred in the center hole of the gear, and pores were found to occur around the upper part of the hole. Therefore, the design of the casting method is suitable for worm gears. CT analysis showed that all parts of worm gear were distributed with fine pores and some coarse pores were distributed around the central hole of worm gear. The yield strength and tensile strength were 220 MPa, 285 MPa, and the elongation rate was 8%. Vickers hardness is 82 HV.

• 한국음향학회지
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• 제23권4호
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• pp.268-273
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• 2004

본 연구에서는 원호의 내부벽면에 1열로 배열된 어레이 트랜스듀서를 이용한 반사-투과형 생체진단용 역산란 초음파 단층화상법을 제안하였다. 제안된 방법에서는 대상 물체의 배면에 반사판을 배치하여 경면효과를 이용하였고, 유한 대역을 갖는 펄스파를 송신파로 사용하여 다중 주파수 성분을 이용함으로써 데이터 관측 범위를 줄일 수 있었다. 제안된 방법의 성능 평가를 위하여 컴퓨터 시뮬레이션을 이용한 모의 생체 조직에 대한 유효성을 검토한 격과, 트랜스듀서군의 송수신 각도 범위가 30도로 극히 좁은 범위로 제한되었음에도 불구하고 정량적인 화상재현이 가능함을 확인할 수 있다.

• 한국정밀공학회지
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• 제28권1호
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• pp.80-88
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• 2011

The dental high-speed air turbine handpiece is one of the most popular devices that have been widely used as the main means of cutting tooth structure and restorative material in dentistry. In consideration of usage and marketability of the dental handpiece, it is obviously worthy of investigating it. The goal of this paper is to establish the relationship between the air turbine speed and the supply route inside the handpiece. To do this, the Computational Fluid Dynamics(CFD) tool, Fine$^{TM}$/Turbo is used and the optimal supply route position is suggested from the simulation results. In addition, as an attempt for domestic product, the reverse engineering process of a high speed dental handpiece by 3D X-Ray CT equipment and wire cutting is presented for the Mark II model in NSK. In doing so, the 3D modeling of the handpiece parts is carried out with CATIA V5, and the interference between parts is examined. Finally, the result of performance test for the prototype produced in this research is presented.

• 한국멀티미디어학회논문지
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• 제23권3호
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• pp.468-475
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• 2020

In this paper, we proposed a three-dimensional visualization system for medical images in augmented reality based on deep learning. In the proposed system, the artificial neural network model performed fully automatic segmentation of the region of lung and pulmonary nodule from chest CT images. After applying the three-dimensional volume rendering method to the segmented images, it was visualized in augmented reality devices. As a result of the experiment, when nodules were present in the region of lung, it could be easily distinguished with the naked eye. Also, the location and shape of the lesions were intuitively confirmed. The evaluation was accomplished by comparing automated segmentation results of the test dataset to the manual segmented image. Through the evaluation of the segmentation model, we obtained the region of lung DSC (Dice Similarity Coefficient) of 98.77%, precision of 98.45%, recall of 99.10%. And the region of pulmonary nodule DSC of 91.88%, precision of 93.05%, recall of 90.94%. If this proposed system will be applied in medical fields such as medical practice and medical education, it is expected that it can contribute to custom organ modeling, lesion analysis, and surgical education and training of patients.

• Asian Pacific Journal of Cancer Prevention
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• 제17권11호
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• pp.4935-4937
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• 2016

Objective: To compare dosimetric parameters of 3 dimensional conformal radiotherapy (3 DCRT) and intensity modulated radiotherapy (IMRT) in terms of target coverage and doses to organs at risk (OAR) in the management of rectal carcinoma. Methods: In this prospective study, conducted between August 2014 and March 2016, all patients underwent CT simulation along with a bladder protocol and target contouring according to the Radiation Therapy Oncology Group (RTOG) guidelines. Two plans were made for each patient (3 DCRT and IMRT) for comparison of target coverage and OAR. Result: A total of 43 patients were recruited into this study. While there were no significant differences in mean Planning Target Volume (PTV) D95% and mean PTV D98% between 3 DCRT and IMRT, mean PTV D2% and mean PTV D50% were significantly higher in 3 DCRT plans. Compared to IMRT, 3 DCRT resulted in significantly higher volumes of hot spots, lower volumes of cold spots, and higher doses to the entire OAR. Conclusion: This study demonstrated that IMRT achieves superior normal tissue avoidance (bladder and bowel) compared to 3 DCRT, with comparable target dose coverage.

• 한국CDE학회논문집
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• 제16권5호
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• pp.315-322
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• 2011

The goal of total knee replacement (TKR) surgery is to replace patient's knee joint with artificial implants in order to restore normal knee joint functions. Since mismatched knee implants often cause a critical balancing problem and short durability, designing a well-fitted implant to a patient's knee joint is essential to improve surgical outcomes. We developed a software system that three-dimensionally (3D) simulates TKR surgery based upon 3D knee models reconstructed from computed tomography (CT) imaging. The main task of the system was to extract precise 3D anatomical parameters of a patient's knee that were directly used to determine a custom fit implant and to virtually perform TKR surgery. The virtual surgery was simulated by amputating a 3D knee model and positioning the determined implant components on the amputated knee. The test result shows that it is applicable to derive surgical parameters, determine individualized implant components, rehearse the whole surgical procedure, and train medical staff or students for actual TKR surgery. The feasibility and verification of the proposed system is described with examples.