• 대한방사선치료학회지
• /
• 제33권
• /
• pp.109-116
• /
• 2021

목 적: 본 연구는 표면유도환자셋업(Surface-Guided Patient Setup, SGPS)을 활용한 Markerless환자(피부에 표시를 시행하지 않은 환자)와 레이저기반환자셋업(Laser-Based Patient Setup, LBPS)을 활용한 Marker환자(피부에 표시를 시행한 환자)를 영상유도방사선치료(Image Guided Radiotherapy, IGRT)로 시행했을 때 환자 위치 정확도를 비교하여 SGPS의 유용성을 평가하는데 목적이 있다. 대상 및 방법: 3개의 카메라를 이용한 광학 표면 스캐닝시스템을 사용하여 SGPS로 초기 셋업한 Markerless 환자와 환자 피부에 그려진 Marker와 레이저를 정렬하는 LBPS로 초기 셋업한 Marker환자의 IGRT시 위치 오차를 비교하였다. SGPS,LBPS 모두 각각 전립선암 환자 20명, 뇌정위적방사선수술(Stereotactic Radiation Surgery, SRS) 환자 10명을 대상으로 시행하였고 SGPS의 경우는 추가로 유방암 환자 60명을 대상으로 시행하였다. 모두 CBCT 또는 OBI를 사용하여 IGRT를 시행하였다. 자동위치교정시스템(Auto-Matching System)을 이용하여 6방향(6 Degree Of Freedom, 6 DoF)의 위치 오차를 획득하였고 치료계획시스템에서 Offline-Review를 이용하여 비교, 분석하였다. 결 과 : 전립선암환자의 SGPS와 LBPS의 RMS(Root Mean Square) 차이는 Vrt -0.02cm, Log -0.02cm, Lat -0.01cm, Pit -0.01°, Rol -0.01°, Rtn -0.01°이였고 SRS 환자는 Vrt 0.02cm, Log -0.05cm, Lat 0.00cm, Pit -0.30°, Rol -0.15°, Rtn -0.33°으로 두 부위 모두 큰 차이가 없었다. 유방암환자의 IGRT기준 RMS는 Vrt 0.26, Log 0.21, Lat 0.15, Pit 0.81, Rol 0.49, Rtn 0.59으로 나타났다. 결 론 : 본 연구의 결과 LBPS 대비 SGPS의 위치 오차 값은 전립선암 환자와 SRS 환자의 경우 큰 차이를 보이지 않았다. 추가로 실시한 SGPS의 유방암 환자의 경우에도 IGRT기준으로 위치 오차 값이 크지 않았다. 따라서 환자 피부 표시를 필요로 하지 않는 큰 장점을 가진 SGPS로 LBPS를 대체하기에 유용할 것으로 사료된다.

• 한국ITS학회 논문지
• /
• 제18권1호
• /
• pp.43-55
• /
• 2019

스마트폰 기반 길안내 애플리케이션은 일상생활에서 매우 유용하다. 또한 비용 효율적이고 사용자 친화적인 내비게이션은 많은 고객을 유치할 수 있다. 하지만 스마트폰을 사용하여 지하철 역사와 같은 지하공간에서 정확한 내비게이션을 제공하는 것은 여전히 어려운 과제이다. 방문객이 지하공간에서 필요할 때마다 언제 어디서나 스마트 폰으로 길 안내를 제공받을 수 있다면 더 편리한 모빌리티 서비스를 제공할 수 있다. 본 연구는 지하철을 이용하는 고객에게 출입구에서 열차 플랫폼까지의 길 안내 시스템을 개발하고 있다. 경로탐색은 새로 제안한 QR 마커와 증강현실(AR)을 적용하여 스마트폰의 광학적 툴로 위치정보를 파악하여 경로안내 정보를 실내 지도 없이 제공하는 비용 효율적인 스마트 폰 알고리즘에 해당한다. 또한 이 알고리즘은 교통약자들에게 별도의 Barrier Free 경로로 안내하는 모듈도 제공하고 있다.

• Nuclear Engineering and Technology
• /
• 제43권2호
• /
• pp.133-140
• /
• 2011

In this paper, a deformation measurement technology for nuclear fuel rods is proposed. The deformation measurement system includes a high-definition CMOS image sensor, a lens, a semiconductor laser line beam marker, and optical and mechanical accessories. The basic idea of the proposed deformation measurement system is to illuminate the outer surface of a fuel rod with a collimated laser line beam at an angle of 45 degrees or higher. For this method, it is assumed that a nuclear fuel rod and the optical axis of the image sensor for observing the rod are vertically composed. The relative motion of the fuel rod in the horizontal direction causes the illuminated laser line beam to move vertically along the surface of the fuel rod. The resulting change of the laser line beam position on the surface of the fuel rod is imaged as a parabolic beam in the high-definition CMOS image sensor. An ellipse model is then extracted from the parabolic beam pattern. The center coordinates of the ellipse model are taken as the feature of the deformed fuel rod. The vertical offset of the feature point of the nuclear fuel rod is derived based on the displacement of the offset in the horizontal direction. Based on the experimental results for a nuclear fuel rod sample with a formation of surface crud, an inspection resolution of 50 ${\mu}m$ is achieved using the proposed method. In terms of the degree of precision, this inspection resolution is an improvement of more than 300% from a 150 ${\mu}m$ resolution, which is the conventional measurement criteria required for the deformation of neutron irradiated fuel rods.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제11권2호
• /
• pp.679-687
• /
• 2019

This paper presents the autonomous swimming technology developed for an Autonomous Underwater Vehicle (AUV) operating in the underwater jacket structure environment. To prevent the position divergence of the inertial navigation system constructed for the primary navigation solution for the vehicle, we've developed kinds of marker-recognition based underwater localization methods using both of optical and acoustic cameras. However, these two methods all require the artificial markers to be located near to the cameras mounted on the vehicle. Therefore, in the case of the vehicle far away from the structure where the markers are usually mounted on, we may need alternative position-aiding solution to guarantee the navigation accuracy. For this purpose, we develop a sonar image processing based underwater localization method using a Forward Looking Sonar (FLS) mounted in front of the vehicle. The primary purpose of this FLS is to detect the obstacles in front of the vehicle. According to the detected obstacle(s), we apply an Occupancy Grid Map (OGM) based path planning algorithm to derive an obstacle collision-free reference path. Experimental studies are carried out in the water tank and also in the Pohang Yeongilman port sea environment to demonstrate the effectiveness of the proposed autonomous swimming technology.

• ETRI Journal
• /
• 제33권4호
• /
• pp.569-579
• /
• 2011

This paper presents a novel approach for human activity recognition (HAR) using the joint angles from a 3D model of a human body. Unlike conventional approaches in which the joint angles are computed from inverse kinematic analysis of the optical marker positions captured with multiple cameras, our approach utilizes the body joint angles estimated directly from time-series activity images acquired with a single stereo camera by co-registering a 3D body model to the stereo information. The estimated joint-angle features are then mapped into codewords to generate discrete symbols for a hidden Markov model (HMM) of each activity. With these symbols, each activity is trained through the HMM, and later, all the trained HMMs are used for activity recognition. The performance of our joint-angle-based HAR has been compared to that of a conventional binary and depth silhouette-based HAR, producing significantly better results in the recognition rate, especially for the activities that are not discernible with the conventional approaches.

• 한국정밀공학회지
• /
• 제29권7호
• /
• pp.723-729
• /
• 2012

Spring-like leg models have been employed to explain various dynamic characteristics in human walking. However, this leg stiffness model has limitations to represent complex motion of actual human gait, especially the behaviors of each lower limb joint. The purpose of this research was to determine changes of total leg stiffness and lower limb joint stiffness with gait speed in knee osteoarthritis. Joint stiffness defined as the ratio of the joint torque change to the angular displacement change. Eight subjects with knee osteoarthritis participated to this study. The subject walked on a 12 m long and 1 m wide walkway with three sets of four different randomly ordered gait speeds, ranging from their self-selected speed to maximum speed. Kinetic and kinematic data were measured using three force plates and an optical marker system, respectively. Joint torques of lower limb joints calculated by a multi-segment inverse dynamics model. Total leg and each lower limb joint had constant stiffness during single support phase. The leg and hip joint stiffness increased with gait speed. The correlation between knee joint angles and torques had significant changed by the degree of severity of knee osteoarthritis.

• 한국콘텐츠학회:학술대회논문집
• /
• 한국콘텐츠학회 2006년도 추계 종합학술대회 논문집
• /
• pp.831-835
• /
• 2006

모션캡쳐는 사람이나 동물, 생물, 기계 등과 같은 물체의 움직임을 컴퓨터가 사용 가능한 형태로 기록하는 것을 말한다. 모션캡쳐시스템의 장점으로 기존의 키 프레임 방식으로는 영상표현이 어려운 인간이나 동물의 사실적인 움직임, 큰 스케일, 많은 경제적 부담이 소요되는 부분 등에 도입되어 새로운 표현 가능성을 보여주고 있어 디지털 엔터테인먼트 영역에서 게임을 중심으로 영화, TV, 광고, 다큐멘터리, 뮤직비디오 등 점차 그 활용 빈도가 증가하고 있다. 그러나 이와 같은 장점에도 불구하고 모션캡쳐를 활용한 디지털 영상표현에 있어서 많은 사전준비 작업, 마커의 부착, 모션데이터의 보정, 모션리타겟팅, 모션캡쳐 전문인력 부족 등의 문제점이 대두되고 있다. 이에 본 논문에서는 모션캡쳐를 활용한 영상제작 사례를 통하여 제작 공정상 나타나는 문제점과 그 해결방안을 모색함으로써 보다 효과적인 모션캡쳐 디지털 영상제작의 방향을 제안하고자 한다.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
• /
• pp.7-7
• /
• 2000

A high $T_c$ SQUID system is developed for the application to biological immunoassay. In this application, magnetic nanoparticles are used as magnetic markers to perform immunoassay, i.e., to detect binding reaction between an antigen and its antibody. The antibody is labeled with ${\gamma}-Fe_2O_3\;(or\;Fe_3O_4)$ nanoparticles, and the binding reaction can be magnetically detected by measuring the magnetic field from the nanoparticles. Design and set up of the system is described. The system consists of (1) SQUID magnetometer or gradiometer made of 30-deg. bicrystal junctions, (2) field and compensation coils to apply the magnetic field of about 1 mT, (3) special Dewar to realize a 2 mm-distance between the SQUID and the sample, (4) two layers of cylindrical shielding to reduce the extemal magnetic noise to about 1/100, and (5) an electric slider to move the sample with a speed of 10 mm/sec. The sensitivity of the system is studied in terms of detectable magnetic flux. For the measurement bandwidth from 0.2 Hz to 10 Hz, minimum-detectable amplitude of the magnetic flux is $0.8\;m\;{\Phi}_o$ and $0.25\;m{\Phi}_o$ for the magnetometer and the gradiometer, respectively, when the magnetic field of 1 mT is applied. The difference between them is due to the residual environmental noise, and the applied magnetic field does not increase the system noise. The corresponding weight of the magnetic markers is 1 ng and 310 pg, respectively. An experiment is also conducted to measure antigen-antibody reaction with the present system. It is shown that the sensitivity of the present system is 10 times better than that of the conventional method using an optical marker. A one order of magnitude improvement of sensitivity will be realized by the sophistication of the present system.

• The Korean Journal of Physiology and Pharmacology
• /
• 제13권5호
• /
• pp.337-341
• /
• 2009

Signal transducer and activator of transcription 4 (STAT4), a STAT family member, mediates interleukin 12 (IL12) signal transduction. IL12 is known to be related to calorie-restricted status. In the central nervous system, IL12 also enhances the production of nitric oxide (NO), which regulates food intake. In this study, the expression of neuronal NO synthase (Nos1), which is also related to food intake, was investigated in the hypothalamic areas of Stat4 knockout (KO) mice using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry, a marker for neurons expressing Nos1 enzyme. Western blots were also performed to evaluate Nos1 and Fos expression. Wild-type Balb/c (WT group, n=10 male) and Stat4 KO mice (Stat4 KO group, n=8 male) were used. The body weight and daily food intake in the WT group were $22.4{\pm}0.3$ and 4.4 g per day, while those in the Stat4 KO group were $18.7{\pm}0.4$ and 1.8 g per day, respectively. Stat4 mice had lower body weight and food intake than Balb/c mice. Optical intensities of NADPH-d-positive neurons in the paraventricular nucleus (PVN) and lateral hypothalamic area (LHA) of the Stat4 KO group were significantly higher than those of the WT group. Western blotting analysis revealed that the hypothalamic Nos1 and Fos expression of the Stat4 KO group was up-regulated, compared to that in the WT group. These results suggest that Stat4 may be related to the regulation of food intake and expression of Nosl in the hypothalamus.

• Investigative Magnetic Resonance Imaging
• /
• 제16권1호
• /
• pp.55-66
• /
• 2012

목적 : 자기공명영상(MRI) 획득시 피험자의 머리 움직임은 영상의 품질에 영향을 줄 수 있다. 영상 왜곡의 발생 원인이 되는 피험자의 움직임을 감지하기 위한 3차원 광학 추적 시스템을 제작하였다. 대상 및 방법 : 시스템은 두 대의 CCD 카메라 및 적외선 조명, 구형 반사 마커, 프레임 그래버(frame grabber)와 데스크탑 컴퓨터로 구성되었다. 두 대의 카메라를 이용하여 마커의 움직임을 관측하는 스테레오 비전 시스템을 제작하고, 카메라의 내부/외부 매개변수를 측정하는 캘리브레이션(calibration)과 측정된 매개변수를 이용하여 3차원 움직임 정보를 계산하는 삼각측량(triangulation)기법을 적용하였다. 캘리브레이션 보드와 피험자용 안경을 제작하여 움직임 추적의 정확도와 실제 MRI 영상 촬영 동안의 움직임 검출의 유효성을 평가하였다. 결과 : 반사 마커가 부착된 안경을 쓴 피험자들이 MRI 영상 촬영 동안 머리를 규칙적으로 움직였을 때, 시스템은 MRI의 고자장 환경 내에서도 영상에 영향을 주지 않고 피험자들의 움직임을 잘 감지했다. 결론 : 제작한 스테레오 비전 시스템은피험자의 머리 움직임을 잘 감지하였고, 실시간 알림 기능을 통해 피험자의 움직임을 중지할 수 있도록 알려줌으로써 MRI 영상에 영향을 주는 것을 최소화할 수 있다.