• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.452-455
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• 2004

MSC (Multi-Spectral Camera) system is a remote sensing instrument to obtain high resolution ground image. EOS (Electro-Optic System) for MSC mainly consists of PMA (Primary Mirror Assembly), SMA (Secondary Mirror Assembly), HSTS (High Stability Telescope Structure) and DFPA (Detector Focal Plane Assembly). High performance of EOS makes it possible for MSC system to provide high resolution and high quality ground images. Temperature of the EOS needs to be controlled to be in a specific range in order not to have any thermal distortion which can cause performance degradation. It is controlled by full redundant CPU based electronics. The validity of thermistor readings can be checked because a few thermistors are installed on each control point on EOS. Various kinds of thermal control logics are used to prevent 'Single Point Failure'. Control logic has a few set of database in order not to be corrupted by SEU (Single Event Upset). Even though the thermal control logic is working automatically, it can also be monitored and controlled by ground-station operator. In this paper, various ways of thermal control logic for EOS in MSC will be presented, which include thermal control mode and logic, redundancy design and status monitoring and reporting scheme.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.158-163
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• 2009

In recent years, there has been increased interest in characterizing and extracting 3D information from 2D images for human tracking and identification. In this paper, we propose a single view-based framework for robust estimation of height and position. In the proposed method, 2D features of target object is back-projected into the 3D scene space where its coordinate system is given by a rectangular marker. Then the position and the height are estimated in the 3D space. In addition, geometric error caused by inaccurate projective mapping is corrected by using geometric constraints provided by the marker. The accuracy and the robustness of our technique are verified on the experimental results of several real video sequences from outdoor environments.

• Journal of the Korean Society of Visualization
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• v.2 no.1
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• pp.39-45
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• 2004

A time-resolved two-phase PIV system using a single camera has been developed, which introduces a method of image separation into respective phase images, and is applied to freely rising single bubble. Gas bubble, tracer particle and background have different gray intensity ranges on the same image frame when reflection and dispersion in the phase interface are intrinsically eliminated by optical filters and fluorescent particles. Further, the signals of the two phases do not interfere with each other. Gas phase velocities are obtained from the separated bubble image by applying the two-frame PTV. On the other hand, liquid phase velocities are obtained from the tracer particle image by applying the cross-correlation algorithm. As a result, the bubble rises rectilinearly just after it is released from an injector and then has a zigzag motion in the far field. From the trajectory of the bubble, it is found that the period of the zigzag motion is closely related to the vortex shedding although the wavelength of it varies along its movement.

• Journal of the Korean Society of Visualization
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• v.10 no.1
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• pp.21-26
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• 2012

Hydrophobic characteristics of high temperature metal surface were investigated by high-speed visualization of water droplet impact. An aluminum plate was used as the sample plate and the initial diameter of a water droplet was 2 mm. Transient behavior of a single droplet impinging on the surface with and without heating was captured by using a high speed camera running at 4,000 frames per second. The Leidenfrost phenomenon was demonstrated for the case of $300^{\circ}C$ surface temperature, however there was no rebounding of droplet on the cold plate due to hydrophilic nature. The experimental results show that the shape evolution of a droplet impinging on the surface varies with the Weber number, i.e. the ratio of impact inertia to capillary force. The overall water-repellent characteristics of the heated surface was very similar to that of the super hydrophobic surfaces.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1980-1992
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• 2006

Nucleate pool boiling experiments were performed using pure R11 for various surface angles under constant heat flux conditions during saturated pool boiling. A 1-mm-diameter circular heater with an artificial cavity in the center that was fabricated using a MEMS technique and a high-speed controller were used to maintain the constant heat flux. Bubble growth images were taken at 5000 frames per second using a high-speed CCD camera. The bubble geometry was obtained from the captured bubble images. The effects of the surface angle on the bubble growth behavior were analyzed for the initial and thermal growth regions using dimensional scales. The parameters that affected the bubble growth behavior were the bubble radius, bubble growth rate, sliding velocity, bubble shape, and advancing and receding contact angles. These phenomena require further analysis for various surface angles and the obtained constant heat flux data provide a good foundation for such future work.

• Laser Solutions
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• v.8 no.1
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• pp.9-18
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• 2005

The laser direct writing method using a UV Argon-ion laser is studied for fabrication of waveguide. The laser direct writing system is constructed with a vision camera, a xy-stage, a motion controller and the delivery components of a laser beam. The UV Argon-ion laser has wavelength range of $333.6\~363.8$ nm. A photo-active UV curable polymer for a planar light-wave circuit(PLC) of single mode is used. This polymer is irradiated by Argon-ion laser and developed by a solvent after a post-baking. The optimum laser direct writing condition is obtained experimentally by changing various process parameters such as laser power, writing speed and focal length. The propagation and coupling loss of a optical waveguide was measured as 1dB/cm and 0.6dB/cm, respectively. Also, the minimum width of waveguide of $100{\mu}m$(ZPLW-207) is obtained. Finally, the waveguides of line, bend and branch type are successfully fabricated.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.105-113
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• 2000

In order to clarify the final process of oil consumption, the distribution and flow of oil through each ring were visualized by induced fluorescence method. Motoring and firing test were performed in a single cylinder research engine with transparent cylinder liner. The appropriate calibration techniques were used to solve the unstability of induced light intensity as well as to know the relation of the oil film thickness and output signal. Oil behavior was also observed at dynamic state by high speed CCD camera. By analyzing the oil film thickness converted from the photographed image, it was observed that the main route of oil transport through each ring is the end gap under the usual operating condition, low engine speed and low load condition. Oil film thickness is observed to be irregular and tend to move in a body horizontally at a given piston land. And it is also found that oil flows through oil ring gap so quickly that it can be observed in a single cycle, but it flows so slowly through top and 2nd compression rings that it takes quite a long time to detect the flow.

• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.145-150
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• 2008

This thesis explores the problem of reconstructing a three-dimensional(3D) scene given a set of images or image sequences of the scene. It describes efficient methods for the 3D reconstruction of static and dynamic scenes from stereo images, stereo image sequences, and images captured from multiple viewpoints. Novel methods for image-based and volumetric modelling approaches to 3D reconstruction are presented, with an emphasis on the development of efficient algorithm which produce high quality and accurate reconstructions. For image-based 3D reconstruction a novel energy minimisation scheme, Iterated Dynamic Programming, is presented for the efficient computation of strong local minima of discontinuity preserving energyy functions. Coupled with a novel morphological decomposition method and subregioning schemes for the efficient computation of a narrowband matching cost volume. the minimisation framework is applied to solve problems in stereo matching, stereo-temporal reconstruction, motion estimation, 2D image registration and 3D image registration. This thesis establishes Iterated Dynamic Programming as an efficient and effective energy minimisation scheme suitable for computer vision problems which involve finding correspondences across images. For 3D reconstruction from multiple view images with arbitrary camera placement, a novel volumetric modelling technique, Embedded Voxel Colouring, is presented that efficiently embeds all reconstructions of a 3D scene into a single output in a single scan of the volumetric space under exact visibility. An adaptive thresholding framework is also introduced for the computation of the optimal set of thresholds to obtain high quality 3D reconstructions. This thesis establishes the Embedded Voxel Colouring framework as a fast, efficient and effective method for 3D reconstruction from multiple view images.

• Journal of ILASS-Korea
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• v.20 no.4
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• pp.261-267
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• 2015

The main purpose of this study is to provide the information of soot generation of toluene fuel droplet. To achieve this, this paper provides the experimental results on the different initial diameter of toluene droplet combustion characteristics conducted under equivalent ambient pressure ($P_{amb}$) and oxygen concentration ($O_2$) conditions. Visualization of single fuel droplet was performed with high resolution CCD camera and visualization system. At the same time, ambient pressure ($P_{amb}$) and oxygen concentration ($O_2$) were maintained by ambient condition control system. Soot volume fraction ($f_v$) was analyzed and compared on the basis of intensity ratio ($I/I_0$) of background image. The result of soot generation was almost the same regardless of initial droplet diameter since thermophoretic flux is not much changed under the same ambient conditions. Soot standoff ratio (SSR) of 2 mm diameter showed unstable variation characteristics due to the short available measuring time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.234-238
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• 2014

Multichip packaging was achieved the best solution to significantly reduce thermal resistance at the same time, to increase luminance intensity in LEDs packaging application. For the packaging, thermal spreading resistance is an important parameter to get influence the total thermal performance of LEDs. In this study, silicon-based multichip light emitting diodes (LEDs) packaged module has been examined for thermal characteristics in several parameters. Compared to the general conventional single LED packaged chip module, multichip LED packaged module has many advantages of low cost, low density, small size, and low thermal resistance. This analyzed module is comprised of multichip LED array, which consists of 32 LED packaged chips with supplement power of 0.2 W at every single chip. To realize the extent of thermal distribution, the computer-aided design model of 6.4 W Si-based multichip LED module was designed and was performed by the simulation basis of actual fabrication flow. The impact of thermal distribution is analyzed in alternative ways both optimizing numbers of fins and the thickness of that heatsink. In addition, a thermal resistance model was designed and derived from analytical theory. The optimum simulation results satisfies the expectations of the design goal and the measurement of IR camera results. tart after striking space key 2 times.