• Korean Journal of Remote Sensing
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• v.37 no.6_3
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• pp.1985-1999
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• 2021

The purpose of this study is to apply urban heat island reduction techniques(green roof, cool roof, and cool pavements using heat insulation paint or blocks) recommended by the Environmental Protection Agency (EPA) to our study area and determine their actual effects through a comparative analysis between land cover objects. To this end, the area of Mugye-ri, Jangyu-myeon, Gimhae, Gyeongsangnam-do was selected as a study area, and measurements were taken using a drone DJI Matrice 300 RTK, which was equipped with a thermal infrared sensor FLIR Vue Pro R and a visible spectrum sensor H20T 1/2.3" CMOS, 12 MP. A total of nine heat maps, land cover objects (711) as a control group, and heat island reduction technique-applied land covering objects (180) were extracted every 1 hour and 30 minutes from 7:15 am to 7:15 pm on July 27. After calculating the effect values for each of the 180 objects extracted, the effects of each technique were integrated. Through the analysis based on daytime hours, the effect of reducing heat islands was found to be 4.71℃ for cool roof; 3.40℃ for green roof; and 0.43℃ and -0.85℃ for cool pavements using heat insulation paint and blocks, respectively. Comparing the effect by time period, it was found that the heat island reduction effect of the techniques was highest at 13:00, which is near the culmination hour, on the imaging date. Between 13:00 and 14:30, the efficiency of temperature reduction changed, with -8.19℃ for cool roof, -5.56℃ for green roof, and -1.78℃ and -1.57℃ for cool pavements using heat insulation paint and blocks, respectively. This study was a case study that verified the effects of urban heat island reduction techniques through the use of high-resolution images taken with drones. In the future, it is considered that it will be possible to present case studies that directly utilize micro-satellites with high-precision spatial resolution.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.447-460
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• 2022

It is well known that satellite synthetic aperture radar interferometry (InSAR) has been widely used for the observation of surface displacement owing to earthquakes, volcanoes, and subsidence very precisely. In wetlands where vegetation exists on the surface of the water, it is possible to create a water level change map with high spatial resolution over a wide area using the InSAR technique. Currently, a number of imaging radar satellites are in operation, and most of them support a ScanSAR mode observation to gather information over a large area at once. The Cienaga Grande de Santa Marta (CGSM) wetland, located in northern Colombia, is a vast wetland developed along the Caribbean coast. The CGSM wetlands face serious environmental threats from human activities such as reclamation for agricultural uses and residential purposes as well as natural causes such as sea level rise owing to climate change. Various restoration and protection plans have been conducted to conserve these invaluable environments in recognition of the ecological importance of the CGSM wetlands. Monitoring of water level changes in wetland is very important resources to understand the hydrologic characteristics and the in-situ water level gauge stations are usually utilized to measure the water level. Although it can provide very good temporal resolution of water level information, it is limited to fully understand flow pattern owing to its very coarse spatial resolution. In this study, we evaluate the L-band ALOS-2 PALSAR-2 ScanSAR mode to observe the water level change over the wide wetland area using the radar interferometric technique. In order to assess the quality of the interferometric product in the aspect of spatial resolution and coherence, we also utilized ALOS-2 PALSAR-2 stripmap high-resolution mode observations.

• Journal of the Korean Orthopaedic Association
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• v.55 no.1
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• pp.38-45
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• 2020

Purpose: To examine the clinical and structural outcomes of an at least two-year follow-up of arthroscopic full-thickness rotator cuff repairs with a single-row or suture-bridge technique in patients more than 65 years of age. Materials and Methods: Patients diagnosed with a full-thickness rotator cuff tear who were more than 65 years of age, underwent arthroscopic rotator cuff repair after at least six months of conservative treatment, agreed to take a follow-up magnetic resonance imaging (MRI) six months postoperatively, and visited outpatient for at least two years were enrolled in this study. Clinical evaluations were done using The University of California Los Angeles score, Constant Shoulder Score, and visual analogue scale evaluated two years after the surgery. The structural integrity was analyzed using follow-up MRI. During surgery, a suture-bridge technique was used if the rotator cuff tendon could cover half of the footprint under constant tension. Otherwise, single-row repair was performed. Results: The samples were 158 cases, consisting of 93 single-repairs and 65 suture-bridge repairs. A preoperative comparison of the age distribution, fatty degeneration of supraspinatus and infraspinatus muscle, medial retraction of torn cuff tendon, and tear size between the two groups were not significant. The clinical scores were improved significantly in all cases. The distribution of the structural integrity by Sugaya classification were 49 cases in type 1 (31.0%), 62 cases in type 2 (39.2%), 30 cases in type 3 (19.0%), 11 cases in type 4 (7.0%), and six cases in type 5 (3.8%). The re-tear rate of the single-row group was 9.7% (nine out of 93 cases) and 12.3% (eight out of 65 cases) for the suture-bridge group. Conclusion: Satisfactory clinical and radiological outcomes were achieved after arthroscopic full-thickness rotator cuff repair in patients more than 65 years of age. Both single-row and suture-bridge techniques would be beneficial for the elderly.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.74-80
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• 2015

Purpose Breast lymphoscintigraphy is an important technique to present for body surface precisely, which shows a lymph node metastasis of malignant tumors at an early stage and is performed before and after surgery in patients with breast cancer. In this study, we evaluated several methods of body outline imaging to present exact location of lesions, as well as compared respective exposure doses. Materials and Methods RANDO phantom and SYMBIA T-16 were used for obtaining imaging. A lesion and an injection site were created by inserting a point source of 0.11 MBq on the axillary sentinel lymph node and 37 MBq on the right breast, respectively. The first method for acquiring the image was used by drawing the body surface of phantom for 30 sec using $Na^{99m}TcO_4$ as a point source. The second, the image was acquired with $^{57}Co$ flood source for 30 seconds on the rear side and the left side of the phantom, the image as the third method was obtained using a syringe filled with 37 MBq of $Na^{99m}TcO_4$ in 10 ml of saline, and as the fourth, we used a photon energy and scatter energy of $^{99m}Tc$ emitting from phantom without any addition radiation exposure. Finally, the image was fused the scout image and the basal image of SPECT/CT using MATLAB$^{(R)}$ program. Anterior and lateral images were acquired for 3 min, and radiation exposure was measured by the personal exposure dosimeter. We conducted preference of 10 images from nuclear medicine doctors by the survey. Results TBR values of anterior and right image in the first to fifth method were 334.9 and 117.2 ($1^{st}$), 266.1 and 124.4 ($2^{nd}$), 117.4 and 99.6 ($3^{rd}$), 3.2 and 7.6 ($4^{th}$), and 565.6 and 141.8 ($5^{th}$). And also exposure doses of these method were 2, 2, 2, 0, and $30{\mu}Sv$, respectively. Among five methods, the fifth method showed the highest TBR value as well as exposure dose, where as the fourth method showed the lowest TBR value and exposure dose. As a result, the last method ($5^{th}$) is the best method and the fourth method is the worst method in this study. Conclusion Scout method of SPECT/CT can be useful that provides the best values of TBR and the best score of survey result. Even though personal exposure dose when patients take scout of SPECT/CT was higher than another scan, it was slight level comparison to 1 mSv as the dose limit to non-radiation workers. If the scout is possible to less than 80 kV, exposure dose can be reduced, and also useful lesion localization provided.

• Journal of Intelligence and Information Systems
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• v.25 no.1
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• pp.1-19
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• 2019

Artificial intelligence (AI) is one of the main driving forces leading the Fourth Industrial Revolution. The technologies associated with AI have already shown superior abilities that are equal to or better than people in many fields including image and speech recognition. Particularly, many efforts have been actively given to identify the current technology trends and analyze development directions of it, because AI technologies can be utilized in a wide range of fields including medical, financial, manufacturing, service, and education fields. Major platforms that can develop complex AI algorithms for learning, reasoning, and recognition have been open to the public as open source projects. As a result, technologies and services that utilize them have increased rapidly. It has been confirmed as one of the major reasons for the fast development of AI technologies. Additionally, the spread of the technology is greatly in debt to open source software, developed by major global companies, supporting natural language recognition, speech recognition, and image recognition. Therefore, this study aimed to identify the practical trend of AI technology development by analyzing OSS projects associated with AI, which have been developed by the online collaboration of many parties. This study searched and collected a list of major projects related to AI, which were generated from 2000 to July 2018 on Github. This study confirmed the development trends of major technologies in detail by applying text mining technique targeting topic information, which indicates the characteristics of the collected projects and technical fields. The results of the analysis showed that the number of software development projects by year was less than 100 projects per year until 2013. However, it increased to 229 projects in 2014 and 597 projects in 2015. Particularly, the number of open source projects related to AI increased rapidly in 2016 (2,559 OSS projects). It was confirmed that the number of projects initiated in 2017 was 14,213, which is almost four-folds of the number of total projects generated from 2009 to 2016 (3,555 projects). The number of projects initiated from Jan to Jul 2018 was 8,737. The development trend of AI-related technologies was evaluated by dividing the study period into three phases. The appearance frequency of topics indicate the technology trends of AI-related OSS projects. The results showed that the natural language processing technology has continued to be at the top in all years. It implied that OSS had been developed continuously. Until 2015, Python, C ++, and Java, programming languages, were listed as the top ten frequently appeared topics. However, after 2016, programming languages other than Python disappeared from the top ten topics. Instead of them, platforms supporting the development of AI algorithms, such as TensorFlow and Keras, are showing high appearance frequency. Additionally, reinforcement learning algorithms and convolutional neural networks, which have been used in various fields, were frequently appeared topics. The results of topic network analysis showed that the most important topics of degree centrality were similar to those of appearance frequency. The main difference was that visualization and medical imaging topics were found at the top of the list, although they were not in the top of the list from 2009 to 2012. The results indicated that OSS was developed in the medical field in order to utilize the AI technology. Moreover, although the computer vision was in the top 10 of the appearance frequency list from 2013 to 2015, they were not in the top 10 of the degree centrality. The topics at the top of the degree centrality list were similar to those at the top of the appearance frequency list. It was found that the ranks of the composite neural network and reinforcement learning were changed slightly. The trend of technology development was examined using the appearance frequency of topics and degree centrality. The results showed that machine learning revealed the highest frequency and the highest degree centrality in all years. Moreover, it is noteworthy that, although the deep learning topic showed a low frequency and a low degree centrality between 2009 and 2012, their ranks abruptly increased between 2013 and 2015. It was confirmed that in recent years both technologies had high appearance frequency and degree centrality. TensorFlow first appeared during the phase of 2013-2015, and the appearance frequency and degree centrality of it soared between 2016 and 2018 to be at the top of the lists after deep learning, python. Computer vision and reinforcement learning did not show an abrupt increase or decrease, and they had relatively low appearance frequency and degree centrality compared with the above-mentioned topics. Based on these analysis results, it is possible to identify the fields in which AI technologies are actively developed. The results of this study can be used as a baseline dataset for more empirical analysis on future technology trends that can be converged.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.27 no.2
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• pp.27-47
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• 1997

The purpose of this study was to evaluate the accuracy and usefulness of spiral tomography through the comparison and analysis of SCANORA cross-sectional tomographs and DentaScan computed tomographic images of dry mandibles taken by a SCANORA spiral tomographic machine and a computed tomographic machine. Thirty-one dry mandibles with full or partial edentulous areas were used. To evaluate the possible effect of location in the edentulous area, it was divided into 4 regions of Me (region of mental foramen), MI (the midportion between Me and M2), M2 (the midportion between mental foramen and mandibular foramen) and S (the midportion of the mandibular symphysis). A ZPC column (sized 4 mm x 5 mm) was seated on the edentulous regions of Me, MI, M2 and S using the acrylic stent. Then SCANORA spiral tomography and computed tomography were taken on the edentulous regions which contained the ZPC column. The ZPC columns and cross-sectional images of the mandible were measured in the radiographs by three observers and the differences between the two imaging modalities were analysed. The results were as follows: 1. In comparing the actual measurements of the ZPC column and measurements in the radiographs, the mean error of the DentaScan computed tomography was 0.07 mm in vertical direction and -0.06 mm in horiwntal direction, while the mean error of the SCANORA spiral tomography was 0.06 mm in vertical direction and -0.12 mm in horizontal direction. There was a significant difference between the two radiographic techniques in the horizontal measurement of the ZPC column of the symphysis region (p<0.05). But there was no significant difference in the measurements of other regions (p>0.05). 2. In measurements of the distance from the alveolar crest to the inferior border of the mandible (H), and of the distance from the alveolar crest to the superior border of the mandibular canal (Y), there was no significant difference between the two radiographic techniques (p>0.05). 3. In measurements of the distance from the lingual border of the mandible to the buccal border of the mandible (W), and of the distance from the lingual border of the mandible to the lingual border of the mandibular canal (X), there was a significant difference between the two radiographic techniques in measurements of the midportion between the mental foramen and the mandibular foramen (M2) (p<0.05). But there were no significant differences in measurements of the other regions of symphysis (S), mental foramen (Me), the first one-fourth portion between the mental foramen and the mandibular foramen (M1) (p>0.05). 4. Considering the mean range of measurements between observers, the measurements of SCANORA spiral tomography showed higher value than those of DentaScan computed tomography, except in measurements of symphysis (S). 5. On the detectability of the mandibular canal, there was no significant difference between the two radiographic techniques (p>0.05). In conclusion, SCANORA spiral tomography demonstrated a higher interobserver variance than that of DentaScan computed tomography for implant site measurements in the posterior edentulous area of the mandible. These differences were mainly the result of difficulty in the detection of the border of the mandible in SCANORA spiral tomography. But considering the cost and the radiation exposure, SCANORA spiral tomography can be said to be a relatively good radiographic technique for implant site measurement.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.3
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• pp.243-248
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• 2009

Purpose: Rehabilitation of the edentulous posterior maxilla with dental implants often poses difficulty because of insufficient bone volume caused by pneumatization of the maxillary sinus and by crestal bone resorption. Sinus grafting technique was developed to increase the vertical height to overcome this problem. The present study was designed to evaluate the sinus floor augmentation with anorganic bovine bone (Bio-$cera^{TM}$) using histomorphometric and clinical measures. Patients and methods: Thirteen patients were involved in this study and underwent total 14 sinus lift procedures. Residual bone height was ${\geq}2mm$ and ${\leq}6mm$. Lateral window approach was used, with grafting using Bio-$cera^{TM}$ only(n=1) or mixed with autogenous bone from ramus and/or maxillary tuberosity(n=13). After 6 months of healing, implant sites were created with 3mm diameter trephine and biopsies taken for histomorphometric analysis. The parameters assessed were area fraction of new bone, graft material and connective tissue. Immediate and 6 months after grafting surgery, and 6 months after implantation, computed tomography (CT) was taken and the sinus graft was evaluated morphometric analysis. After implant installation at the grafted area, the clinical outcome was checked. Results: Histomorphometry was done in ten patients.Bio-$cera^{TM}$ particles were surrounded by newly formed bone. The graft particles and newly formed bone were surrounded by connective tissue including small capillaries in some fields. Imaging processing revealed $24.86{\pm}7.59%$ of new bone, $38.20{\pm}13.19%$ connective tissue, and $36.92{\pm}14.51%$ of remaining Bio-$cera^{TM}$ particles. All grafted sites received an implant, and in all cases sufficient bone height was achieved to install implants. The increase in ridge height was about $15.9{\pm}1.8mm$ immediately after operation (from 13mm to 19mm). After 6 months operation, ridge height was reduced about $11.5{\pm}13.5%$. After implant installation, average marginal bone loss after 6 months was $0.3{\pm}0.15mm$. Conclusion: Bio-$cera^{TM}$ showed new bone formation similar with Bio-$Oss^{(R)}$ histomorphometrically and appeared to be an effective bone substitute in maxillary sinus augmentation procedure with the residual bone height from 2 to 6mm.

• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.146-153
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• 1999

Purpose : To evaluate the proton MR spectroscopy (MRS) findings of early and late ischemic infarcts and to compare these MRS findings with clinical symptoms. Materials and Methods : We obtained MRs spectra of 28 consecutive patients with early ischemic infarct (15 me, 13 women) between 2-10 (mean 6.2) days after stroke onset. Follow-up MRS was carried out between 20-32 (mean 25) days in 12 patients. The MRs spectra were acquired at 1.5T MR unit using single voxel technique with PRESS sequence, TR of 2000ms, TE of 288 (144)ms, and voxel size of 2cm x 2cm x 2cm in the three areas; an infarct lesion, the brain parenchyma adjacent to the lesion, and contralateral normal brain parenchyma. The NAA/creatine, choline/creatine, and lactate/creatine ratios were calculated in each spectrum. The spectra of MRS were compared with clinical symptoms. Results : In early infarct, decreased NAA/creatine ratio (n=22) and increased lactate/creatine ratio (n=25) were found in the infarct lesion. Choline/creastine ratio was within normal range (n=25). On follow-up MRS in late stage, NAA/creatine ratio in the infarct lesion decreased further (n=5), did not change (n=6), or increased (n=1). Lactate/creatine ratio became less elevated (n=10), or did not changed (n=2). Choline/creatine ratio had a trend for increase. The decreased NAA/creatine and increased lactate/creatine ratios were correlated well with the severity of symptoms, respectively. Conclusion : Decreased NAA/creatine and increased lactate/creatine ratios were common MRS findings characteristic in early ischemic infarct and correlated well with clinical severity. On follow-up MRS in late stage, NAA/creatine ratio decreased further or did not change, and lactate/creatine ratio became less elevated.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.1
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• pp.33-39
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• 2006

Purpose: To determine appropriate sampling frequency and time of multiple blood sampling dual exponential method with $^{99m}Tc$-DTPA for calculating glomerular filtration rate (GFR). Materials & Methods: Thirty four patients were included in this study. Three mCi of $^{99m}Tc$-DTPA was intravenously injected and blood sampling at 9 different times, 5ml each, were done. Using the radioactivity of serum, measured by gamma counter, the GFR was calculated using dual exponential method and corrected with the body surface area. Using spontaneously chosen 2 data points of serum radioactivity, 15 collections of 2-sample GFR were calculated. And 10 collections of 3-sample GFR and 12 collections of 4-sample GFR were also calculated. Using the 9-sample GFR as a reference value, degree of agreement was analyzed with Kendall's $\tau$ correlation coefficients, mean difference and standard deviation. Results: Although some of the 2-sample GFR showed high correlation coefficient, over or underestimation had evolved as the renal function change. The 10-120-240 min 3-sample GFR showed a high correlation coefficient (${\tau}=0.93$), minimal difference ($Mean{\pm}SD=-1.784{\pm}3.972$), and no over or underestimation as the renal function changed. The 4-sample GFR showed no better accuracy than the 3-sample GFR. Conclusions: In the wide spectrum of renal function, the 10-120-240 min 3-sample GFC could be the best choice for estimating the patients' renal function.

• Journal of radiological science and technology
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• v.15 no.1
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• pp.65-78
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• 1992

Routine chest radiography is generally imaged by high voltage technique but some radiological technologists use low voltage for imaging. High voltage is usually said between $120\;kV{\sim}140\;kV$. Some RTs like using heavy filtration but others seldom like using it. However which is better for use calcium tungustate film screen system or ortho system and high contrast film or wide latitude c-type film for the exculusive use of chest radiography. We could not make a decision which is ideal method for use. In my opinion any method is not always exellent for chest radiography. In my experiments that I had at Kaken hospital in Japan last year I expect to keep the balance between image quality and diagnostic range and to reduce radiation dose for patients. My experiments are as follows. 1. We have looked into system characteristics(speed and contrast) in accordance with kVp($80{\sim}140$) and added filter($no{\sim}1/16\;VL$) in three screen film systems(BX3+CRONEX4, SRO750+MGH, SRO750+MGL). 2. We have looked into skin dose and film dose with same D=1.8 lung field density in accordance with kVp($80{\sim}140$) and added filter($no{\sim}1/16\;VL$) in three screen film systems. 3. We have compared with the evaluation between correlation of physical image quality(MTF) and optical diagnostic capability. Result are follows. 1. Speed of BX3+CRONEX4 became higher in accodance with kVp and thickness of filter but speed of ortho system was not as like regular system. Thicker filter diminished the speed over 100 kV range in SRO750+MGL. In case of SRO750+MGH speed of 1/16VL filter was looked into lower than speed of 1/4VL filter. Sensitivity of ortho system depends on tube voltage and added filter. 2. Skin dose has been detected $225\;{\mu}Gy{\sim}66\;{\mu}Gy$ in BX3+CRONEX4 from 80 kV, no filter to 140 kV, 1/16VL filter. SRO750+MGH could reduce the patient dose $1/2{\sim}1/3$ level in comparison to that of BX3+CRONEX4. 3. The higher kV was the worse MTF became the thicker filter was the worse MTF became too. MTF of BX3+CRONEX4 was detected better than MTF of SRO750+MGH but SRO750+MGH's optical detectability of small lesion in lung field came out better than that of BX3+CRONEX4. Conclusion Recently routine chest radiography is generally imaged by high voltage but it seems to be there are some questions in using of film screen combination. In high voltage chest radiography the subject contrast will come down that means latitude become wider. In this case if we select the low contrast film screen system(C or L type) the film contrast will fall down extremly and detectability of small lesion will be deteriorated. Wide latitude C, L type film has a merit of high detectability on mediastinum. Furthermore high contrast film screen system has the advantage to keep the high contrast in low density region as like mediastinum and heart shadow. Therefore in low subject contrast high voltage chest radiography we would rather choose the high contrast film screen system(H type) I think. From a view point of patient dose detectability of mediastinum and lung field. The optimum technical facter was found out 120 kV, 1/16VL filter : BX3+CRONEX4, 140 kV, 1/4VL filter : SRO750+MGH, 100 kV, 1/4VL filter : SRO750+MGL.