• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.975-980
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• 2020

Cervical neural foraminal stenosis is a very common spinal disease that affects a relatively large number of people of all ages. However, since imaging methods that quantitatively provide neural foraminal stenosis are lacking, this study attempts to present quantitative measurement results by reconstructing 3D computed tomography images. Using a 3D reconstruction software, the surrounding bones were removed, including the spinous process, transverse process, and lamina of the cervical spine so that the neural foramen were well observed. Using Image J, a region of interest including the neural foramen area of the 3D image was set, and the number of pixels of the neural foramen area was measured. The neural foramen area was calculated by multiplying the number of measured pixels by the pixel size. In order to measure the widest area of the neural foramen, it was measured between 40-50 degrees in the opposite direction and 15-20 degrees toward the head. The measured cervical neural foramen area showed consistent measurement values. The largest measured area of the right neural foramen C5-6 was 12.21 ㎟, and after 2 years, the area was measured to be 9.95 ㎟, indicating that 18% stenosis had progressed. Since 3D reconstruction using axial CT scan images, no additional radiation exposure is required, and the area of stenosis can be objectively presented. In addition, it is good to explain to patients with neural stenosis while viewing 3D images, and it is considered a good method to be used in the evaluation of the progression of stenosis and post-operative evaluation.

• Journal of Cadastre & Land InformatiX
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• v.51 no.1
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• pp.23-38
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• 2021

In this paper, we analyzed the possibility of utilizing LX-PPS GNSS permanent stations whose antennas are installed on the building rooftop for the purpose of high-precision GNSS positioning services. We picked 15 pairs of adjacent GNSS permanent stations operated by LX-PPS and NGII, and then produced 3-year-long time series using the high-precision data processing software called GIPSY. Patterns and trends of position estimates were compared and analyzed. Horizontal and vertical deviations including the linear velocities coincide with the well-known crustal deformation rates of the Korean peninsula. We also observed almost the same annual or seasonal patterns from those nearby sites. After detrending the linear velocity, the amplitude and phase of annual signals almost perfectly match each other within the baseline length of 2 km. By subtracting seasonal signals, the RMS and standard deviations in LX-PPS PPGR with respect to NGII KANR are about 1, 2, and 5 mm in the north-south, east-west, and vertical directions, respectively. From this analysis it can be concluded that the rooftop-installed LX-PPS sites show similar level of stability and positioning performance comparable to those ground-mounted NGII stations.

• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.13-23
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• 2022

The ground-structure interaction of the bridge foundation has been pointed out as a major factor influencing the behavior of the bridge during earthquakes. In this study, the effect of characteristics of ground and bridge foundation on the earthquake vulnerability is investigated. From the pseudo-static analysis, it is confirmed that non-linearity becomes lesser and horizontal load becomes greater when surcharge is considered. It is also found that as the ground worsens and the size of foundation decreases, horizontal load reduces. To derive reasonable structural model for bridge foundation, fragility curve is obtained considering four conditions (fixed condition, equivalent linear condition, non-linear without surchage condition, non-linear with surcharge condition) and compared. Seismic analysis is performed on single pier with Opensees. From the earthquake vulnerability analysis, it is found that shallow foundation can be assumed as fixed condition. In conservative approach, stiffness of spring can be obtained based on Korean highway bridge design code for pile foundation which can consider the ground condition.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.5
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• pp.1-12
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• 2022

COVID-19 led to an increased need for mountainous urban parks in the city that can be enjoyed while moving rather than staying put. However, studies on the economic value of mountainous urban parks have been insufficient. As a result, this study investigates the economic value of Gyeyangsan, a mountainous urban park located in the city, by quantifying the value of natural resources provided to residents and analyzing the factors affecting these values. The results are summarized below. First, according to the economic value assessment of Gyeyangsan, the use value was 2,210 won per person or 4.42 billion won per year, and the preservation value was 6,182 won per household, or 129.37 billion won. Gyeyangsan's total assets value was assessed as 3.68 trillion won. Second, according to the estimates of the willingness to pay and the determinants for the use-value, the frequency of visits, age, and use satisfaction significantly impacted the intention to pay for the use-value. Third, according to the estimates of the willingness to pay and the determinants for the preservation value, the intention to revisit, volunteer participation, educational level, gender, and residence significantly influenced the intention to pay for the preservation value. According to the findings of this study, it will be possible to make crucial policy implications when setting a direction for future park management by presenting a practical policy plan for the maintenance of mountain parks in downtown areas and will broaden the scope of research.

• Journal of Intelligence and Information Systems
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• v.28 no.1
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• pp.1-28
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• 2022

In recent years, many Internet giants have begun providing their own content services, which attract online users by offering personalized services based on artificial intelligence technologies. This study investigates the role of two firms' content services within the firms' online service network. We examine the role of Naver Webtoon, which can be characterized as a professional-generated content, within Naver's service portfolio, and that of Google YouTube, which can be characterized as a user-generated content, within Google's service portfolio. Using survey data on viewers' use of the two services, we analyze a valued directed service network, where a node denotes an online service and a relationship between two nodes denotes a sequential use of two services. We found that both Webtoon and YouTube show higher out-degree centrality than in-degree centrality, which implies these content services are more likely to be starting services rather than arriving services within the firms' interactive network. The gap between the out-degree and in-degree centrality of YouTube is much smaller than that of Webtoon. The high centrality of YouTube, a user-generated content service, within the Google service network shows that YouTube's initial role of providing specific-content videos (e.g., entertainment) has expanded into a general search service for users.

• Journal of the Korean Orthopaedic Association
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• v.52 no.1
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• pp.65-72
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• 2017

Purpose: The purpose of this study was to evaluate the radiologic features of juxtafacet cyst and determine the correlation between these features and clinical outcome. Materials and Methods: We analyzed a total of 23 patients. The degree of facet joint degeneration was classified using the Fujiwara method. The facet joint angles were measured with an magnetic resonance imaging to determine whether there was a difference between the cystic lesion that was occupied and the cystic lesion that was not occupied. Disc degeneration was measured by the Pfirrmann classification method. The clinical result was evaluated using the Oswestry disability index score and visual analogue scale. Results: The L4-5 level of juxtafacet cyst was mostly affected, as found in previous studies. Facet joint arthritis was more severe within the side with the cystic lesion. Significant correlation was found between disc degeneration and juxtafacet joint cyst. All patients underwent wide decompression and fusion. Clinical result was excellent. No patients had signs of recurrence during the follow-up periods. Conclusion: Juxtafacet cyst has a significant correlation with facet joint degeneration. Therefore, aggressive surgical treatment-not just simple cyst excision-should be considered as the treatment option for juxtafacet cyst associated with degenerative lumbar disease.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.295-301
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• 2008

Bathymetric data collected using a multi-beam echo sounder during marine scientific survey is essential for geologic and oceanographic research works. Accurate measurment of sound velocity profile(SVP) in water-column is important for bathymetric data processing. SVP can vary at different locations during the survey undertaken for wide areas. In addition, an observational error can occur when different equipments(Sound Velocity Profiler, Conductivity Temperature Depth, eXpendable BathyThermograph) are used for measuring SVP at the same water column. In this study, we used an MB-system software to show changes in bathymetry caused by variation of SVP. The analyses showed that the sound velocity(SV) changes due to the depth and thickness of thermocline had more significant effects on the resulting bathymetric data than those of surface mixed layer. The observational errors between SVP measuring instruments did not cause much differneces in the processed bathymetric data. Bathymetric survey line is better to be established to the direction that the change of temperature can be minimize to reduce the variation of SVP during the data acquisition along the survey line.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.83-95
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• 2018

Purpose : After planning the Respiratory Gated Radiotherapy for Lung cancer, the movement and volume change of sparing normal structures nearby target are not often considered during dose evaluation. This study carried out 4-D dose evaluation which reflects the movement of normal structures at certain phase of Respiratory Gated Radiotherapy, by using Deformable Image Registration that is well used for Adaptive Radiotherapy. Moreover, the study discussed the need of analysis and established some recommendations, regarding the normal structures's movement and volume change due to Patient's breathing pattern during evaluation of treatment plans. Materials and methods : The subjects were taken from 10 lung cancer patients who received Respiratory Gated Radiotherapy. Using Eclipse(Ver 13.6 Varian, USA), the structures seen in the top phase of CT image was equally set via Propagation or Segmentation Wizard menu, and the structure's movement and volume were analyzed by Center-to Center method. Also, image from each phase and the dose distribution were deformed into top phase CT image, for 4-dimensional dose evaluation, via VELOCITY Program. Also, Using $QUASAR^{TM}$ Phantom(Modus Medical Devices) and $GAFCHROMIC^{TM}$ EBT3 Film(Ashland, USA), verification carried out 4-D dose distribution for 4-D gamma pass rate. Result : The movement of the Inspiration and expiration phase was the most significant in axial direction of right lung, as $0.989{\pm}0.34cm$, and was the least significant in lateral direction of spinal cord, as -0.001 cm. The volume of right lung showed the greatest rate of change as 33.5 %. The maximal and minimal difference in PTV Conformity Index and Homogeneity Index between 3-dimensional dose evaluation and 4-dimensional dose evaluation, was 0.076, 0.021 and 0.011, 0.0 respectfully. The difference of 0.0045~2.76 % was determined in normal structures, using 4-D dose evaluation. 4-D gamma pass rate of every patients passed reference of 95 % gamma pass rate. Conclusion : PTV Conformity Index was more significant in all patients using 4-D dose evaluation, but no significant difference was observed between two dose evaluations for Homogeneity Index. 4-D dose distribution was shown more homogeneous dose compared to 3D dose distribution, by considering the movement from breathing which helps to fill out the PTV margin area. There was difference of 0.004~2.76 % in 4D evaluation of normal structure, and there was significant difference between two evaluation methods in all normal structures, except spinal cord. This study shows that normal structures could be underestimated by 3-D dose evaluation. Therefore, 4-D dose evaluation with Deformable Image Registration will be considered when the dose change is expected in normal structures due to patient's breathing pattern. 4-D dose evaluation with Deformable Image Registration is considered to be a more realistic dose evaluation method by reflecting the movement of normal structures from patient's breathing pattern.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.1
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• pp.42-46
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• 2016

Purpose Mammography is the most widely used scan for the early diagnosis since it is possible to observe the anatomy of the breast. however, The sensitivity is markedly reduced in high-risk patients with dense breast. Molecular Breast Imaging (MBI) sacn is possible to get the high resolution functional imaging, and This new neclear medicine technique get the more improved diagnostic information through It is useful for confirmation of tumor's location in dense breast. The purpose of this study is to evaluate the usefulness of MBI for tumor diagnosis in patients with dense breast. Materials and Methods We investigated 10 patients female breast cancer with dense breast type who had visited the hospital from September 1st to Octorber 10th, 2015. The patients underwent both MBI and Mammography. MBI (Discovery 750B; General Electric Healthcare, USA) scan was 99mTc-MIBI injected with 20 mCi on the opposite side of the arm with the lesions, after 20 minutes, gained bilateral breast CC (CranioCaudal), MLO (Medio Lateral Oblique) View. Mammography was also conducted in the same posture. MBI and Mammography images were compared to evaluate the sensitivity and specificity of each case utilizing both image and two images in blind tests. Results The results of the blind test for breast cancer showed that the sensitivity of Mammography, MBI scan was 63%, 89%, respectively, and that their specificity was 38%, 87%, respectively. Using both the Mammography and MBI scan was Sensitivity 92%, specificity 90%. Conclusion This research has found that, The tumor of dense tissue that can not easily distinguishable in Mammography is possible to more accurate diagnosis since It is easy to visually evaluation. But MBI sacn has difficulty imaging microcalcificatons, If used in conjunction with mammography it is thought to give provide more diagnostic information.

• Progress in Medical Physics
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• v.22 no.1
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• pp.35-41
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• 2011

For overall system test, hidden-target test have been used using film which leads to inherent analysis error. The purpose of our study is to quantify this error and to propose gel dosimeter based verification technique for 3-dimensional target point error. The phantom was made for simulation of human head and this has ability to equip 10 gel-dosimeter. $BANGkit^{TM}$ which we are able to manufacture whenever it is needed as well as to easily change the container with different shapes was used as a gel dosimeter. The 10 targets were divided into two groups based on shapes of areas with a planned 50% isodose line. All treatment and analysis was performed three times using Novalis and $BrainSCAN^{TM}$. The target point error is $0.77{\pm}0.15mm$ for 10 targets and directional target point error in each direction is $0.54{\pm}0.23mm$, $0.37{\pm}0.08mm$, $0.33{\pm}0.10mm$ in AP (anterior-posterior), LAT (lateral), and VERT (vertical) direction, respectively. The result of less than 1 mm shows that the treatment was performed through each precise step in treatment procedure. In conclusion, the 3-dimensional target point verification technique can be one of the techniques for overall system test.