• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
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• pp.133-140
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• 1999

In this paper, we propose a method of image-based three-dimensional modeling for realistic facial expression. In the proposed method, real human facial images are used to deform a generic three-dimensional mesh model and the deformed model is animated to generate facial expression animation. First, we take several pictures of the same person from several view angles. Then we project a three-dimensional face model onto the plane of each facial image and match the projected model with each image. The results are combined to generate a deformed three-dimensional model. We use the feature-based image metamorphosis to match the projected models with images. We then create a synthetic image from the two-dimensional images of a specific person's face. This synthetic image is texture-mapped to the cylindrical projection of the three-dimensional model. We also propose a muscle-based animation technique to generate realistic facial expression animations. This method facilitates the control of the animation. lastly, we show the animation results of the six represenative facial expressions.

• Annals of Surgical Treatment and Research
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• 제95권6호
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• pp.340-344
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• 2018

Purpose: Traumatic lumbar hernia is rare, thus making diagnosis and proper treatment challenging. Accordingly, we aimed to investigate the clinical manifestations and proper management strategies of traumatic lumbar hernias. Methods: The medical records of patients with traumatic lumbar hernia treated at Gachon University Gil Hospital from March 2006 to February 2015, were retrospectively reviewed. Results: We included 5 men and 4 women (mean age, 55 years; range, 23-71 years). In 8 patients, most injuries were caused by motor vehicle collisions, including those wherein a pedestrian was struck (5 cases of car accidents, 2 falls, and 1 involving penetrating materials); in 1 patient, the probable cause was severe cough. Eight patients underwent hernia repair surgery (5 open and 3 laparoscopic), and a prosthetic mesh was used in 7 patients. Hernia repairs were elective in 7 patients; emergency hernia repair was performed with right hemicolectomy in 1 patient. No severe complication or recurrence was observed. Only 2 patients had mild complications, such as postoperative seroma. Conclusion: Traumatic lumbar hernia is a relatively rare injury of the posteriolateral abdominal wall. Lumbar hernia should be suspected in patients with high-energy injuries of the torso, and all such patients should undergo abdominopelvic computed tomography. After diagnosis, hernia repair can be electively performed without complications in most cases.

• 대한조선학회논문집
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• 제60권5호
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• pp.296-304
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• 2023

Cavitation tests for a waterjet propulsor of an amphibious vehicle are carried out in the Large Cavitation Tunnel. Waterjet pump performances and cavitation characteristics including thrust breakdown performances are investigated in the tests. In addition, cavitation characteristics for waterjet propulsors working inside the intake are calculated by using a commercial CFD code, Star-CCM+. Sliding mesh is implemented to a rotating impeller and the k-epsilon turbulence model is chosen. Cavitation bubble growth and collapse are estimated using the Schnerr-Sauer cavitation model based on Rayleigh-Plasset equation. Calculated results agree fairly well with experimental results. The re-design of the waterjet propulsor is performed to enhance waterjet cavitating performances and calculated results show that waterjet thrust breakdown characteristics are significantly improved.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1566-1573
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• 2014

Although most algae cultivation systems are operated in suspended culture, an attached growth system can offer several advantages over suspended systems. Algal cultivation becomes light-limited as the microalgal concentration increases in the suspended system; on the other hand, sunlight penetrates deeper and stronger in attached systems owing to the more transparent water. Such higher availability of sunlight makes it possible to operate a raceway pond deeper than usual, resulting in a higher areal productivity. The attached system achieved 2.8-times higher biomass productivity and total lipid productivity of $9.1g\;m^{-2}day^{-1}$ and $1.9g\;m^{-2}day^{-1}$, respectively, than the suspended system. Biomass productivity can be further increased by optimization of the culture conditions. Moreover, algal biomass harvesting and dewatering were made simpler and cheaper in attached systems, because mesh-type substrates with attached microalgae were easily removed from the culture and the remaining treated wastewater could be discharged directly. When the algal biomass was dewatered using natural sunlight, the palmitic acid (C16:0) content increased by 16% compared with the freeze-drying method. There was no great difference in other fatty acid composition. Therefore, the attached system for algal cultivation is a promising cultivation system for mass biodiesel production.

• 핵의학기술
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• 제19권1호
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• pp.51-56
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• 2015

Purpose As medical radiation exposures on patients are being social issues an interest in a relief of radiation exposures on patients is increasing. Further, there are many cases where some patients among who are getting PET/CT tests choose to get implanted with metal artifacts in their bodies. This study is to find out effects of presence or absence of metal artifacts when dose change or CT attenuation correction for the relief of radiation exposures are applied using phantoms through changes in standard uptake value (SUV). Materials and Methods GE company's Discovery 710 machine was used for PET/CT test equipments. We used NEMA IEC body phantoms. We also used screw and mesh cage made of titanium which are used in real clinical processes for the metal artifacts. Two experiments were conducted: One is to test and measure repeatedly about SUV about differences in CT attenuation corrections according to dose changes and another is to do the same procedure for SUV about the presence and absence of the metal artifacts. We injected $^{18}F-FDG$ into NEMA IEC body phantoms with a TBR ratio of 4:1 and then put the metal material into the transformation phantoms. Once a scanning for the metal artifacts was done we eliminated the metal artifacts and went on non-metal artifacts. For the each two experiments, we scanned repeatedly with CT kVp (140, 120, 100, 80) and mA (120, 80, 40, 20, 10) for an experimental condition. For PET, we reconstructed each with standard AC (STD) technique and quantitation achieved cnsistently QAC) technique among CT attenuation correction methods. We conducted a comparative analysis on measured average values and variations which were measured through repeated measure of SUV of region 1, 2, 3 spheres for each conditions of non-metal /metal scan. Results For each kVp, 120, 80, 40 (mA) of non/metal (screw, mesh cage) showed low frequency of fluctuation rates of above 2%. In 20, 10 mA above 2% of fluctuation rates appeared in high frequency. Also, when we compared the fluctuation rates of STD and QAC techniques in non/metal (screw, mesh cage) tests QAC technique showed about 1-10% of differences for each conditions compared to STD technique. In addition, metal types did not have significant effects on fluctuation rates. Conclusion We confirmed that SUV fluctuation rates for both STD and QAC techniques increase as dosage is lower. We also found that the SUV of PET data was maintained steadily in a low dosage for QAC technique when compared with STD technique. Hence, when the low dosage is used for the relief of radiation exposures on patients QAC technique may be exploited helpfully and this could be applied in the same way for patients with metal artifacts implanted in their bodies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.392-392
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• 2011

Carbon nanotubes (CNT) emitter has widely become an attractive mechanism that draws growing interests for cold cathode field emission.$^{1,2}$ CNT yarns have demonstrated its potential as excellent field emitters.$^3$ Extensive simulations were carried out in designing a CNT yarn-based cathode assembly. The focal spot size dependence on the anode surface of the geometric parameters such as axial distance of the electrostatic focus lens from the cathode and the applied bias voltages at the cathode, grid mesh and electrostatic focus lens were studied. The detailed computer simulations using Opera 3D electromagnetic software$^4$ had revealed that a remarkable size of focal spot under a focusing lens triode type set-up design was achieved. The result of this optimization simulation would then be applied for the construction of the CNT yarn based micro-focus x-ray tube with its field emission characteristics evaluated.

• 지구물리와물리탐사
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• 제14권1호
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• pp.88-97
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• 2011

최적화된 4진트리 격자화 기법을 이용한 중력변화율 탐사의 지형 효과 계산 방법을 제시하고자 한다. 제시하고자 하는 방법은 항공탐사의 자료처리를 위하여 지형 자료에 최적화된 빠르고 정확한 지형효과 계산법이다. 각 지점에서의 지형효과 계산에 이용되는 지표 고도 자료는 자동적으로 원하는 정밀도를 제공할 수 있는 최대 크기로 격자화 되어 최대 해상도 자료를 이용하는 방법에 비하여 빠른 계산이 가능하다. 이러한 최적화된 격자 크기는 각 지점에서의 거리와 지표의 고도 변화를 고려하여 구성된다 새로운 접근 방법을 검증하기 위하여 수치모델링과 현장자료에 적용하였다. 현장 자료에 적용한 결과 최적 4 진트리 기법은 최고 해상도 자료를 모두 이용한 방법과 비교하여 중력 변화율 자료에서 1EU(E$\"{o}$tv$\"{o}$s unit)의 정밀도를 유지하면서 계산양은 1/351로 줄일 수 있었다. 또한, 중력탐사 결과의 지형보정에 이용한 결과 모든 DEM자료를 이용한 계산에 비하여 310배나 빠른 계산이 가능하였다.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.117-125
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• 2014

The temperature distribution of steady state rolling tires with detailed tread blocks is numerically predicted using the three dimensional full patterned tire model. A three dimensional periodic patterned tire model is constructed by copying 1-sector mesh in the circumferential direction. Using the static tire contact analysis, the strain cycles during one revolution are approximated with the strains at Guassian points of the elements which are sector-wise repeated within the same circular ring of elements, by neglecting the tire rolling effect. Based upon the multi-axial fatigue theory, the maximum principal strain is used to represent the combined effect of six strain components on the hysteretic loss. In the following, the deformation due to the inflation and vertical load is calculated using ABAQUS. Then heat generation rate in each element is calculated using an in-house code. Lastly, temperature distribution is calculated using ABAQUS again. Through the numerical experiments, the validity of the proposed prediction method is examined by comparing with the experiment and the temperature distribution of a patterned tire model is compared with those of the main-grooved simple tire model.

• 한국세라믹학회지
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• 제47권6호
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• pp.515-523
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• 2010

Porous SiC candle filter preforms were fabricated by extrusion and ramming process. To fabricate SiC candle filter preform, commercially available F180 mesh ($85\;{\mu}m$) $\alpha$-SiC powder and $44\;{\mu}m$ mullite, $CaCO_3$ powder were used as the starting materials. The candle type preforms were fabricated by vacuum extrusion and ramming process, and sintered at $1400^{\circ}C$ 2 h in air atmosphere. Corrosion test of the sintered candle filter specimens as forming method was performed at $600^{\circ}C$ for 2,400 h in simulated IGCC syngas atmosphere. The effect of forming method on mechanical properties, pore distribution, microstructure and crystalline phase was investigated.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1674-1685
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• 2022

The ball valve is an important device in the pipeline transportation system of nuclear power plants. Its operational stability and safety directly affect the normal working of nuclear power plants. In this study, the transient numerical simulation of the opening and closing process of a ball valve was conducted on the basis of the flow interruption capability experiment of the ball valve by using the moving mesh method and inlet and outlet variable boundary conditions. The flow rate and pressure difference with time of the opening and closing process of the ball valve were studied. The internal flow characteristics of the ball valve under different relative openings were analyzed in conjunction with the typical back-step flow structure. Results show that the transient numerical results agree well with the experimental results. The internal flow characteristics of the ball valve are similar at the same opening during opening and closing process. At small opening, the spool and outlet channels easily form a back-step flow structure. The disappearance and generation of backflow vortices during opening and closing occur at 85% opening and 75% opening, respectively. With the decrease in opening degree, the difference in vortex core area in the flow channel of the ball valve spool in the opening and closing process gradually appears. The research results provide some reference value for the design and optimization of ball valves.