• Journal of Astronomy and Space Sciences
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• 제20권2호
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• pp.153-162
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• 2003

인공우주물체의 추적 및 관측을 위해 LX-200 12인치 망원경시스템을 도입하여 시스템의 구동부(모터, 모터드라이버, 모션컨트롤러)를 응답특성이 빠르고 능동제어가 가능한 것으로 개선하였다. 또한, PC를 이용하여 대상물의 실시간 궤적정보를 계산하여 모터 드라이버 내의 PID 제어기에 신호를 제공하였고, 명령신호 제어주기도 20ms까지 줄였다. 그 결과, 가대의 구동속도는 $18^{circ}/sec$로 향상되고 상용시스템보다 응답속도가 빠르며 대상물의 이미지 관측시 flipping 현상을 최소화하는 시스템을 개발하였다.

• 한국멀티미디어학회논문지
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• 제11권1호
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• pp.88-95
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• 2008

본 논문에서는 이진공간분할(BSP), 잠재적가시공간(PVS) 알고리즘을 이용한 효과적인 실내렌더링 방법을 제시한다. 제안된 방식은 BSP 알고리즘과 PVS 기법을 동시에 이용하여 BSP 영역번호를 나누는 과정에서 BSP 영역에 오브젝트를 추가로 포함시킴으로써 오브젝트를 효과적으로 출력시킨다. 또한, 플레이어 위치를 중심으로 PVS를 검사하여 필요한 부분만 출력시킨다. 실험 결과로 부터 제안된 기법은 BSP와 PVS를 경계영역뿐만 아니라 오브젝트도 같이 처리함으로써 렌더링 속도가 향상됨을 보인다.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제4권12호
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• pp.585-588
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• 2015

사물이 실제로 움직이는 속도와 다양한 위치를 정확하게 인식하여 정확하게 3차원 영상정보로 표현하는 기술개발 시도는 무선센서를 활용하여 다양한 분야에서 응용할 수 있다. 3차원 위치 및 속도센서를 조합하여 이동 물체의 위치를 추적하는 시도는 동작의 정확성과 교정을 목적으로 하는 스포츠, 건강관리 분야 등에서 동영상 디스플레이 및 분석 기술과 접목하여 다양한 분석 정보를 제공할 수 있는 특징을 가지고 있다. 본 논문에서는 9축-센서로부터 수집되는 정보를 데이터베이스로 구축하고 이를 웹과 앱의 3차원 공간에서 모니터링할 수 있는 3D 모션 디스플레이를 개발하였다.

• 로봇학회논문지
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• 제14권4호
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• pp.357-362
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• 2019

This paper proposes a model and train method that can real-time detect objects and distances estimation based on a monocular camera by applying deep learning. It used YOLOv2 model which is applied to autonomous or robot due to the fast image processing speed. We have changed and learned the loss function so that the YOLOv2 model can detect objects and distances at the same time. The YOLOv2 loss function added a term for learning bounding box values x, y, w, h, and distance values z as 클래스ification losses. In addition, the learning was carried out by multiplying the distance term with parameters for the balance of learning. we trained the model location, recognition by camera and distance data measured by lidar so that we enable the model to estimate distance and objects from a monocular camera, even when the vehicle is going up or down hill. To evaluate the performance of object detection and distance estimation, MAP (Mean Average Precision) and Adjust R square were used and performance was compared with previous research papers. In addition, we compared the original YOLOv2 model FPS (Frame Per Second) for speed measurement with FPS of our model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.164-164
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• 2000

This paper proposes a moving window technique that extracts lanes and vehicles using the images captured by a CCD camera equipped inside an automobile in real time. For the purpose, first of all the optimal size of moving window is determined based upon speed of the vehicle, road curvature, and camera parameters. Within the moving windows that are dynamically changing, lanes and vehicles are extracted, and the vehicles within the driving lanes are classified as obstacles. Assuming highway driving, there are two sorts of image-objects within the driving lanes: one is ground mark to show the limit speed or some information for driving, and the other is the vehicle as an obstacle. Using characteristics of three-dimension objects, a neural network can be trained to distinguish the vehicle from ground mark. When it is recognized as an obstacle, the distance from the camera to the front vehicle can be calculated with the aids of database that keeps the models of automobiles on the highway. The correctness of this measurement is verified through the experiments comparing with the radar and laser sensor data.

• 한국안전학회지
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• 제24권1호
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• pp.69-77
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• 2009

This paper reports the aging driver traffic accident severity modeling results. For the modeling, Poisson regression approach is applied using the data set obtained from the Korea Transportation Safety Authority's simulator-based driver aptitude test results. The test items include the estimations of moving objects' speed and stopping distance, drivers' multi-task capability, and kinetic depth perception and so on. The resulting model with the response variable of equivalent property damage only(EPDO) indicated that EPDO is significantly influenced by moving objects' speed estimation and drivers' multi-task capabilities. More interestingly, a comparison with the younger driver model revealed that the degradation of such capabilities may result in severer crashes for older drivers as suggested by the higher estimated parameters for the older driver model.

• 한국정보처리학회논문지
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• 제7권6호
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• pp.1746-1752
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• 2000

In this paper, a cache mechanism is proposed to improve the speed of query processing in distributed director database systems. To decrease search time of requested objects and query processing time. query requests and results about objects in a remote site are stored in the cache of a local site. Cache system architecture is designed according to the classified information. Cache schema are designed for each cache information. Operational algorithms are developed for meta data cache which has meta data tree. This tree improves the speed of query processing by reducing the scope of search space. Finally, performance evaluation is performed by comparing the proposed cache mechanism with X500.

• 한국분말재료학회지
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• 제24권3호
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• pp.202-209
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• 2017

A cold-work tool steel powder is used to fabricate 3-dimensional objects by selective laser melting using a high-pressure gas atomization process. The spherical powder particles form continuous carbide networks among the austenite matrix and its decomposition products. The carbides comprise Nb-rich MC and Mo-rich $M_2C$. In the SLM process, the process parameters such as the laser power (90 W), layer thickness ($25{\mu}m$), and hatch spacing ($80{\mu}m$) are kept fixed, while the scan speed is changed from 50 mm/s to 4000 mm/s. At a low scan speed of 50 mm/s, spherical cavities develop due to over melting, while they are substantially reduced on increasing the speed to 2000 mm/s. The carbide network spacing decreases with increasing speed. At an excessively high speed of 4000 mm/s, long and irregularly shaped cavities are developed due to incomplete melting. The influence of the scan pattern is examined, for which $1{\times}1 mm^2$ blocks constituting a processing layer are irradiated in a random sequence. This island-type pattern exhibits the same effect as that of a low scan speed. Post processing of an object using hot isostatic pressing leads to a great reduction in the porosity but causes coarsening of the microstructure.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제2권1호
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• pp.131-139
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• 1998

With the rapid development of communication technology and widespread uses of internet service, utilization of internet-based medical information systems which transmitts moving pictures of medical objects is becoming a common practice. The internet-based medical information service prvovides richer information than conventional services such as touch-tone telephone, personal computers e-mails, or pagers, because "a picture is worth a thousand words". However, the systems passively transmits moving pictures of the medical objects to the users, and thus the system cannot intelligently adjust itself to provide better service. As the tradeoff exists between transmission speed and quality of the image, there is a need that moving pictures be analyzed to adjust the trnasmission speed and image quality. When very little difference between consecutive images are detected, the system can automatically increase the size of the image files, thus enhancing the quality of image. In contrast, the system should increase the number of images to send more pictorial information by sacrificing the quality of each individual image, when a significant difference is detected. In this paper an adaptive filtering technique is introduced which adjusts the quality of image and transmission speed according to a clinical situation in hospital.

• 한국게임학회 논문지
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• 제17권4호
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• pp.55-62
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• 2017

본 연구에서는 HMD(Head Mounted Display)를 가지고 Walk-through의 이동시뮬레이션에 대한 평가를 실시하였다. 구체적으로는 VR공간 주변에 배치된 오브젝트 밀집정도(밀도)의 변화가 심리적 이동거리, 이동속도, 이동시간에 어떠한 영향을 미치는지 알아보았다. 연구결과 첫째, 실험 조건 (저밀도, 중밀도, 고밀도)에 있어 조건간의 차이는 모두 유의미하였다. 둘째, 주변 오브젝트의 밀도가 높아질수록 이동시간, 이동속도, 이동거리가 기본조건과 비교하여 평균점이 높게 나타났다. 셋째, 주변의 오브젝트가 VR공간의 이동시뮬레이션에 있어 시간, 속도, 거리의 감각을 향상 시키는 것을 확인하였다.