• Journal of Cardiovascular Imaging
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• v.31 no.4
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• pp.180-187
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• 2023

BACKGROUND: Two-dimensional (2D) transesophageal echocardiography (TEE) is commonly used for assessing patients undergoing transcatheter atrial septal defect (ASD) device closure. 3D TEE, albeit providing high resolution en-face images of ASD, is used in only a fraction of cases. We aimed to perform a comparative analysis between 3D and 2D TEE assessment for ASD device planning. METHODS: This was a prospective, observational study conducted over a period of one year. Patients deemed suitable for device closure underwent 2D and 3D TEE at baseline. Defect characteristics, assessed separately in both modalities, were compared. Using regression analysis, we aimed to derive an equation for predicting device size using 3D TEE parameters. RESULTS: Thirty patients were included in the study, majority being females (83%). The mean age of the study population was 40.5 ± 12.05 years. Chest pain, dyspnea and palpitations were the common presenting complaints. All patients had suitable rims on 2D TEE. A good agreement was noted between 2D and 3D TEE for measured ASD diameters. 3D TEE showed that majority of defects were circular in shape (60%). The final device size used had high degree of correlation with 3D defect area and circumference. An equation was devised to predict device size using 3D defect area and circumference. The mean device size obtained from the equation was similar to the actual device size used in the study population (p = 0.31). CONCLUSIONS: Device sizing based on 3D TEE parameters alone is equally effective for transcatheter ASD closure as compared to 2D TEE.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.298-307
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• 2006

TEE Forming process for HDPE(High Density PolyEthylen) pipe has been analyzed by using rigid plastic finite element code, DEFORM-3D. TEE of HDPE pipes is necessary to connect main pipe with branch pipe and change the flow direction of hot water. A HDPE pipe is used as a insulator to maintain the temperature of hot water A butt welding process through TEE forming for a HDPE pipe is a updated process improving the strength of welding part compared to conventional extrusion welding process. The Experiment of Hot and Cold Forming have been performed. The design parameters such as a initial hole shape have been obtained through rigid-plastic finite element analysis, which is applied to the actual manufacturing process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.2
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• pp.71-77
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• 1982

This poper proposes the method of the balanced-mixer realization in the X-Band frequency range by the MIC coplanar magic-tee. This magic-tee is composed with microstrip and slot, as suggested by Ronde. The characteristics of balancing and isolation in this magic-tee is more preferable to those of the rat-race or hybrid ring in the wide frequency range. So, experimentally in this paper the characteristics of the MIC balanced-mixed are obtained with the VSWR less than 1, 2(in Local and Signal Arms) and the Conversion Loss, 6 dB in that frequency range, when the mixer is designed in the 3rd order (in E-arm) and 2nd order(in H-arm) Chebyshev matching networks, and with two symmetrical Schottkey Barrier Diodes.

• Broadcasting and Media Magazine
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• v.26 no.4
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• pp.40-47
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• 2021

디지털 트윈, 메타버스 등의 시대적 흐름에 대응하기 위해, 1)실사와 같은 실감성을 갖추고, 2)데이터 취득이 용이하며, 3)가벼운 데이터 저장 및 활용이 가능한 실내 공간 모델링의 필요성이 증대되고 있다. 본 기고에서는 상기 세 가지 조건을 만족하는 TeeVR이라는 기술에 대해 소개하고, 기술의 혁신을 가능하게 한 "구조 기반 접근법"에 대해 소개한다. 마지막으로 아파트에서 전시홀에 이르는 scalable한 적용 예시와 웹(web)이나 스마트 폰과 같은 제한된 환경에서도 사용자 만족도가 높은 다양한 응용 예시를 설명한다.

• Journal of Cardiovascular Imaging
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• v.31 no.1
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• pp.18-23
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• 2023

BACKGROUND: Three-dimensional (3D) transesophageal echocardiogram (TEE) is the gold standard for the diagnosis of degenerative mitral regurgitation (dMR) and preoperative planning for transcatheter mitral valve repair (TMVr). TEE is an invasive modality requiring anesthesia and esophageal intubation. The severe acute respiratory syndrome coronavirus 2 pandemic has limited the number of elective invasive procedures. Multi-detector computed tomographic angiography (MDCT) provides high-resolution images and 3D reconstructions to assess complex mitral anatomy. We hypothesized that MDCT would reveal similar information to TEE relevant to TMVr, thus deferring the need for a preoperative TEE in certain situations like during a pandemic. METHODS: We retrospectively analyzed data on patients who underwent or were evaluated for TMVr for dMR with preoperative MDCT and TEE between 2017 and 2019. Two TEE and 2 MDCT readers, blinded to patient outcome, analyzed: leaflet pathology (flail, degenerative, mixed), leaflet location, mitral valve area (MVA), flail width/gap, anterior-posterior (AP) and commissural diameters, posterior leaflet length, leaflet thickness, presence of mitral valve cleft and degree of mitral annular calcification (MAC). RESULTS: A total of 22 (out of 87) patients had preoperative MDCT. MDCT correctly identified the leaflet pathology in 77% (17/22), flail leaflet in 91% (10/11), MAC degree in 91% (10/11) and the dysfunctional leaflet location in 95% (21/22) of patients. There were no differences in the measurements for MVA, flail width, commissural or AP diameter, posterior leaflet length, and leaflet thickness. MDCT overestimated the measurements of flail gap. CONCLUSIONS: For preoperative TMVr planning, MDCT provided similar measurements to TEE in our study.

• Journal of Nutrition and Health
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• v.31 no.1
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• pp.46-61
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• 1998

This study was carried out to evaluate the effects of vitamin D nutritional status on bone mineral density of adults (21-49 years). To attain the aim, we measured bone mineral density (BMD) of the subjects at distal radius by single-photon absorptiometry (SPA). Serum level of 25-hydroxyvitamin D(25-(OH)D) , known to be the best indicator of indicator of vitamin D status in humans was analyzed . The factors affecting this vitamin D level were also investigated in autumn in 122 young adults. Serum level of 25-(OH)D was measured by high pressure liquid chromatography(HPLC) and biochemical variables, general health status, time spent outdoors, and dietary intakes of the subjects. BMD of the male subjects was significantly greater than that of female subjects. Weight, activity and total energy expediture (TEE) showed a positive correlation with distal BMD. The mean level of serum 25-(OH)D was 24.4$\pm$11.0 ng./ml and by sex, 26.0$\pm$6.8ng/ml for males and 23.3$\pm$12.3ng/ml for females , the level was significantly higher in male (p<0.01). there was significant correlation between BMD at distal-radius and s-25(OH)D levels (p<0.001). The serum level fo parathyroid hormone (PTH) showed a negative correlation with BMD(p<0.05), with the more obvious correlation in females. Vitamin D intake was estimated to be 3.75$\pm$2.19ug/day in average. Among the nutrients studied, protein ,fat, calcium , and vitamin D intake were positively correlated with distal BMD. When food frequencies were concerned , milk and dairy products showed a significant positive correlation with the BMD level, and driedfoods, eggs , fats and oils, and cereals also showed a positive correlation. Time spent outdoors was estimated to be about 70 minutes in average and positively correlated with the distal BMD level(p<0.01). During the day, the specific time between 12 :00pm and 2:00pm showed the most significant correlation with BMD (p<0.001). Multiple regression analysis with the variables showed that distal BMD could be fit 31.9% by the time spent outdoors a day, intake of Ca and vitamin D, and TEE. The standardized estimates were 0.344 for vitamin D intake, 0.284 for Ca intake 0.179 for the time spent outdoors a day and 0.273 for TEE. For males, s-25*OH)D level, TEE and time spent outdoors during a day showed a significant correlation. For females, intake of Ca and vitamin D could fit about 27.1% of the distal BMD.

• Journal of Cardiovascular Imaging
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• v.31 no.4
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• pp.188-190
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• 2023

• Environmental Analysis Health and Toxicology
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• v.15 no.3
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• pp.107-113
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• 2000

Chlorophenoxy acids are one of the most useful classes of chlorinated herbicides. Specially 2, 4-D and 2, 4, 5-T were known to endocrine distruptors. In this study, these pesticides in water samples were extracted by liquid-liquid extration at acidic conditions and then derivatization of acidic group was carried out various esterifications using by CH$_3$I/Acetone -K$_2$CO$_3$, H$_2$SO$_4$/MeOH or TFAA/TFE. That result, Sensitivities of TFE derivatized 2, 4-D and 2, 4, 5-T are prior to the others. The recoveries of 2, 4-D and 2, 4, 5-T were 98% and 82% respectively using diethyl ether as an extracting solvent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.506-511
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• 2002

In this paper, waveguide-based power combiner using conventional slotline-to-microstrip transition was proposed at Ka-band. The proposed 2-way and 4-way power combiner consist of waveguide-to-slotline transition, two or four slotline-to-microstrip transitions, and impedance matching networks. Their structures were simulated and optimized by 3-D FEM simulation. The 2-way power combiner showed a very low back-to-back insertion loss of 1.0 dB and return loss better than 15 dB from 25.7 GHz to 29.8 GHz except the resonant frequency. The 2-way power combining approach was extended to 4-way power combining using slotline tee junction. The 4-way power combiner showed the similar performance to that of 2-way power combiner with 2 GHz smaller bandwidth.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.3
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• pp.36-44
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• 1980

A new coplanar Magic Tee has been formed, The H_arm Is made to have a parallel connection on the plane by using a microstrip and the I_arm is serially coupled by a cavity on the circuit mount and also by a gap formed on the microstrip ground plane. Open and shorted stubs are made to have maximum coupling at the gap of the I-arm, and 2 to 1 impedance matching trinsformers in the I and H-arms are designed to obtain 2nd order Chevyshev characteristics. The impedance matching characteristic on each arm is satisfactory : with VSWR less than 1.25, and the isolation between I and H arms less than -40 dB. These results are in good agreement with theoretical prediction.