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  • Author: Jae Won Lee x
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Brief communication (Original). Multimodal imaging fiducial markers for kinematic measurement of joint models


Background: Fiducial markers are objects placed in the field of view of an imaging system for use as a point of reference or a measure. There is no information regarding suitable markers for joint models.

Objectives: We compared the fiducial markers commonly used in X-ray, CT, and MRI imaging modalities.

Methods: The markers tested were plastic balls, ceramic balls, passive reflective balls, liquid-filled balls, and steel balls. The balls were scanned using X-ray, CT, and MRI systems. The scanned X-ray images were reviewed if it the markers are able to be expressed. The tomographic images of CT and MRI were converted into 3D ball models and then the reconstructed shapes and dimensions of the balls were examined. The dimensional accuracy of expression and reconstruction was calculated in terms of the mean and the standard deviation.

Results: There was no marker that can be expressed in all the imaging modalities. Alternatively, we propose a synthetic marker that is composed of a hard sphere and a fat tissue wrapping. The hard ball is for X-ray and CT imaging, while the fat tissue is for MRI imaging.

Conclusion: A synthetic marker composed of a hard sphere and a fat tissue wrapping can a multimodal fiducial marker.

Open access
Lightlike hypersurfaces of an indefinite Kaehler manifold of a quasi-constant curvature


We study lightlike hypersurfaces M of an indefinite Kaehler manifold of quasi-constant curvature subject to the condition that the characteristic vector field ζ of is tangent to M. First, we provide a new result for such a lightlike hypersurface. Next, we investigate such a lightlike hypersurface M of such that

(1) the screen distribution S(TM) is totally umbilical or

(2) M is screen conformal.

Open access
A study of the kinematic characteristic of a coupling device between the buffer system and the flexible pipe of a deep-seabed mining system


This paper concerns the kinematic characteristics of a coupling device in a deep-seabed mining system. This coupling device connects the buffer system and the flexible pipe. The motion of the buffer system, flexible pipe and mining robot are affected by the coupling device. So the coupling device should be considered as a major factor when this device is designed. Therefore, we find a stable kinematic device, and apply it to the design coupling device through this study. The kinematic characteristics of the coupling device are analyzed by multi-body dynamics simulation method, and finite element method. The dynamic analysis model was built in the commercial software DAFUL. The Fluid Structure Interaction (FSI) method is applied to build the deep-seabed environment. Hydrodynamic force and moment are applied in the dynamic model for the FSI method. The loads and deformation of flexible pipe are estimated for analysis results of the kinematic characteristics

Open access
Effects of high molecular weight poly-γ-glutamic acid on PIGS with porcine preproductive and respiratory syndrome virus (PRRSV) infection


Bacillus subtilis sups. chungkookjang produces a higher molecular mass poly-γ-glutamic acid (γ-PGA). Recently, previous studies have demonstrated immune stimulation and an antitumor effect of the high molecular mass γ-PGA using various mouse models although these effects have not been shown in other species of animals. Therefore, the current study was conducted to determine the effect of γ-PGA in pigs with and without PRRSV infection. PRRS-negative pigs were intramuscularly injected with 1, 3, or 5 ml of 20 mg/mll γ-PGA, and one group of pigs served as a non-treatment (NT) group. All groups treated with γ-PGA had significantly higher weight gains, and pigs treated with 5 ml of γ-PGA exhibited higher tumor necrosis factor (TNF)-α, interferon (IFN)-α and IFN-β expression levels compared with the NT group. According to the preliminary results, an animal challenge study was conducted with a highly virulent PRRSV strain, MN184, along with γ-PGA treatment at different time points. Pigs treated with γ-PGA had lower levels of viral loads in the sera and in lungs and gained significantly more weight (p<0.05) compared with the NT group after being challenged with MN184. Moreover, γ-PGA-treatment groups had higher levels of neutralizing antibodies and cytokines related to proinflammatory, humoral and cell-mediated responses than the control group after the PRRSV challenge. Therefore, it was concluded that γ-PGA induces higher levels of immune responses and increases resistance to PRRSV infection in pigs.

Open access
Performance Analysis of GPS/BDS Integrated Precise Positioning System Considering Visibility of Satellites


Research on precise positioning is being actively carried out to provide accurate position information for land transportation. The most significant problem when performing precise positioning in urban canyon is the degradation of performance due to the lack of visible satellites. Prior to open service of BDS, most of the studies on positioning were focused on using GPS/GLONASS integrated navigation system. Since BDS began open service, studies using GPS/BDS have been actively performed in the Asia-Pacific region as it became possible to acquire enough available BDS satellites. The average number of visible satellites in Korea is 9 for GPS and 14 for BDS. In this paper, we analyze the availability of precise positioning using BDS in urban canyon. To do this, we simulate the urban canyon environment by applying the mask to the azimuth and the elevation. We analyze the positioning accuracy using two simulation scenarios. From the results, it is shown that the accuracy of precise positioning in the case where the satellites in the east-west direction are blocked is lowered than that in the case where the satellites in the south-north direction are blocked for the same elevation mask angle. This result comes from the fact that the PDOP increases when the satellites are blocked in the east-west direction. Also, it can be confirmed that the GPS/BDS integrated positioning is available for the high mask angle while the GPS-only positioning is not possible continuously.

Open access
Optimal planning strategy among various arc arrangements for prostate stereotactic body radiotherapy with volumetric modulated arc therapy technique



The aim of this study was to determine the optimal strategy among various arc arrangements in prostate plans of stereotactic body radiotherapy with volumetric modulated arc therapy (SBRT-VMAT).

Patients and methods

To investigate how arc arrangements affect dosimetric and biological metrics, SBRT-VMAT plans for eighteen patients were generated with arrangements of single-full arc (1FA), single-partial arc (1PA), double-full arc (2FA), and double-partial arc (2PA). All plans were calculated by the Acuros XB calculation algorithm. Dosimetric and radiobiological metrics for target volumes and organs at risk (OARs) were evaluated from dosevolume histograms.


All plans were highly conformal (CI<1.05, CN=0.91) and homogeneous (HI=0.09-0.12) for target volumes. For OARs, there was no difference in the bladder dose, while there was a significant difference in the rectum and both femoral head doses. Plans using 1PA and 2PA showed a strong reduction to the mean rectum dose compared to plans using 1FA and 2FA. Contrastively, the D2% and mean dose in both femoral heads were always lower in plans using 1FA and 2FA. The average tumor control probability and normal tissue complication probability were comparable in plans using all arc arrangements.


The use of 1PA had a more effective delivery time and produced equivalent target coverage with better rectal sparing, although all plans using four arc arrangements showed generally similar for dosimetric and biological metrics. However, the D2% and mean dose in femoral heads increased slightly and remained within the tolerance. Therefore, this study suggests that the use of 1PA is an attractive choice for delivering prostate SBRT-VMAT.

Open access