• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.111-118
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• 2023

MXene, a two-dimensional transition metal carbide or nitride, has recently attracted much attention as a lightweight and flexible electromagnetic shielding material due to its high electrical conductivity, good mechanical strength and thermal stability. In particular, the Ti-based MXene, Ti₃C₂T_x and Ti₂CT_x are reported to have the best electrical conductivity and electromagnetic shielding properties in the vast MXene family. Therefore, in this study, Ti₃C₂T_x and Ti₂CT_x films were prepared by vacuum filtration using Ti₃C₂T_x and Ti₂CT_x dispersions synthesized by interlayer metal etching and centrifugation of Ti₃AlC₂ and Ti₂AlC. The electrical conductivity and electromagnetic shielding efficiency of the films were measured after heat treatment at high temperature. Then, X-ray diffraction and photoelectron spectroscopy were performed to analyze the structural changes of Ti₃C₂T_x and Ti₂CT_x films after heat treatment and their effects on electromagnetic shielding. Based on the results of this study, we propose an optimal structure for an ultra-thin, lightweight, and high performance MXene-based electromagnetic shielding film for future applications in small and wearable electronics.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.743-749
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• 2023

Breast ductal carcinoma in situ(DCIS) refers to cases in which breast epithelial cells have become malignant but are still limited to normal ducts, and has been increasing rapidly in recent years. In this case, a two-year follow-up revealed findings on mammography and ultrasonography that indicated a small mass classified as BI-RADS Category 3, However far from typical malignant tumor these findings were. In the second year of follow-up, a hypoechoic mass with an indistinct boundary of the right breast in the 6 o'clock direction, on mammography appeared to be about 2.1×1.3 cm in size, and biopsy diagnosed it as ductal carcinoma. Since ductal endothelial cancer has no characteristic clinical findings and can show positive clinical and imaging findings in the early stages, regular follow-up is considered important for early diagnosis, and detection of ductal endothelial cancer through mammography and ultrasound is important for improving the prognosis of all breast cancer patients. During the initial examination conducted four years ago, we reported cases of intra ductal cancer in which asymmetric shading, microcalcification, and branched mass, indicative of intra ductal cancer, were observed during follow-up. It is advisable to concurrently explore methods for reducing X-ray dosage to mitigate potential side effects of contrast medium.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.703-714
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• 2023

This research conducts a series of tests to investigate the setting retarding properties and strength development in cement pastes incorporating various types and dosages of sugar-based super retarding agents. Six such agents, including Sucrose, Sugar powder, Saccharin, Aspartame, Stevioside, and Mogroside, commercially available, were selected for evaluation. The study also examines the micro-structural properties of these cement pastes. The test mixtures were prepared using a 27.5% water-to-cement ratio and ordinary Portland cement. Micro-structural analyses were conducted using Scanning Electron Microscopy(SEM), X-Ray Diffraction(XRD), and Energy Dispersive Spectroscopy(EDS). The findings reveal that the incorporation of sucrose, sugar powder, and stevioside significantly retards the setting time. Particularly, adding 0.1% sucrose extended the setting time by approximately two-fold compared to the control(Plain) mixture. Most mixtures, barring those with sugar powder and stevioside, exhibited compressive strength comparable to the Plain mixture. Notably, with 0.2% sucrose, strength measurements were not feasible at 1 day, but at 3 days, the strength gains aligned with the Plain mixture. XRD, SEM, and EDS analyses confirmed the hydration delay(set retarding) of C3S due to sucrose, with further quantitative corroboration provided by EDS. SEM was used to verify the presence or absence of hydration products. The study concludes that sucrose, as a sugar-based retarder, offers effective set retarding capabilities and compressive strength development in concrete.

• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.1109-1115
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• 2022

Renal angiomyolipomas (AMLs) are typically solid tumors, but there have been few reports of a rare cystic variant of AML. AML with epithelial cysts, where the epithelial cyst has a cuboidal epithelial lining, account for the majority of them. Next, epithelioid AML (EAML) with cystic changes due to hemorrhage and necrosis, which is composed of epithelioid cells with abundant eosinophilic cytoplasm, have also been reported. These rare cystic types of AML can be mistaken for other cystic tumors, such as cystic renal cell carcinoma, in preoperative imaging. We report the imaging findings of a rare case of EAML with epithelial cysts.

• Korean Journal of Radiology
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• v.22 no.11
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• pp.1918-1928
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• 2021

Objective: With the recent development of various MRI-conditional cardiac implantable electronic devices (CIEDs), the accurate identification and characterization of CIEDs have become critical when performing MRI in patients with CIEDs. We aimed to develop and evaluate a deep learning-based algorithm (DLA) that performs the detection and characterization of parameters, including MRI safety, of CIEDs on chest radiograph (CR) in a single step and compare its performance with other related algorithms that were recently developed. Materials and Methods: We developed a DLA (X-ray CIED identification [XCID]) using 9912 CRs of 958 patients with 968 CIEDs comprising 26 model groups from 4 manufacturers obtained between 2014 and 2019 from one hospital. The performance of XCID was tested with an external dataset consisting of 2122 CRs obtained from a different hospital and compared with the performance of two other related algorithms recently reported, including PacemakerID (PID) and Pacemaker identification with neural networks (PPMnn). Results: The overall accuracies of XCID for the manufacturer classification, model group identification, and MRI safety characterization using the internal test dataset were 99.7% (992/995), 97.2% (967/995), and 98.9% (984/995), respectively. These were 95.8% (2033/2122), 85.4% (1813/2122), and 92.2% (1956/2122), respectively, with the external test dataset. In the comparative study, the accuracy for the manufacturer classification was 95.0% (152/160) for XCID and 91.3% for PPMnn (146/160), which was significantly higher than that for PID (80.0%,128/160; p < 0.001 for both). XCID demonstrated a higher accuracy (88.1%; 141/160) than PPMnn (80.0%; 128/160) in identifying model groups (p < 0.001). Conclusion: The remarkable and consistent performance of XCID suggests its applicability for detection, manufacturer and model identification, as well as MRI safety characterization of CIED on CRs. Further studies are warranted to guarantee the safe use of XCID in clinical practice.

• Journal of the Korean Chemical Society
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• v.37 no.2
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• pp.191-198
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• 1993

The crystal structures of $Cd_{6-}A$ evacuated at $2{\times}10^{-6}$ torr and $750^{\circ}C$ (a = 12.204(1) $\AA$) and dehydrated $Cd_{6-}A$ reacted with 0.1 torr of Cs vapor at $250^{\circ}C$ for 12 hours (a = 12.279(1) $\AA$) have been determined by single crystal X-ray diffraction techniques in the cubic space group Pm3m at $21(1)^{\circ}C.$ Their structures were refined to final error indices, $R_1=$ 0.081 and $R_2=$ 0.091 with 151 reflections and $R_1=$ 0.095 and $R_2=$ 0.089 with 82 reflections, respectively, for which I > $3\sigma(I).$ In vacuum dehydrated $Cd_{6-}A$, six $Cd^{2+}$ ions occupy threefold-axis positions near 6-ring, recessed 0.460(3) $\AA$ into the sodalite cavity from the (111) plane at O(3) : Cd-O(3) = 2.18(2) $\AA$ and O(3)-Cd-O(3) = $115.7(4)^{\circ}.$ Upon treating it with 0.1 torr of Cs vapor at $250^{\circ}C$, all 6 $Cd^{2+}$ ions in dehydrated $Cd_{6-}A$ are reduced by Cs vapor and Cs species are found at 4 crystallographic sites : 3.0 $Cs^+$ ions lie at the centers of the 8-rings at sites of $D_{4h}$ symmetry; ca. 9.0 Cs+ ions lie on the threefold axes of unit cell, ca. 7 in the large cavity and ca. 2 in the sodalite cavity; ca. 0.5 $Cs^+$ ion is found near a 4-ring. In this structure, ca. 12.5 Cs species are found per unit cell, more than the twelve $Cs^+$ ions needed to balance the anionic charge of zeolite framework, indicating that sorption of Cs0 has occurred. The occupancies observed are simply explained by two unit cell arrangements, $Cs_{12}-A$ and $Cs_{13}-A$. About 50% of unit cells may have two $Cs^+$ ions in sodalite unit near opposite 6-rings, six in the large cavity near 6-ring and one in the large cavity near a 4-ring. The remaining 50% of unit cells may have two Cs species in the sodalite unit which are closely associated with two out of 8 $Cs^+$ ions in the large cavity to form linear $(Cs_4)^{3+}$ clusters. These clusters lie on threefold axes and extend through the centers of sodalite units. In all unit cells, three $Cs^+$ ions fill equipoints of symmetry $D_{4h}$ at the centers of 8-rings.

• Journal of the Korean Magnetics Society
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• v.14 no.2
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• pp.76-82
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• 2004

Crystallographic and magnetic properties for Brownmillerite-type oxides $Ca_{1-x}$Sr$_{x}$FeO$_{2.5}$ (x = 0, 0.3, 0.5, 0.7, 1.0) were investigated using x-ray diffraction (XRD) and Mossbauer spectroscopy. Polycrystalline samples were prepared by conventional solid-state reaction method. Information on exact crystalline structures, lattice parameters, bond lengths and bond angles were obtained by refining their XRD profiles using a Rietveld method. The crystal structures were found to be all orthorhombic with space group Icmm (x = 0, 0.3) and Icmm (x = 0.5, 0.7, 1.0) The lattice parameters increased monotonically with increasing Sr concentration. Both the tetrahedral and the octahedral sites were considerably distorted and elongated along b-axis. While bond lengths and bond angles O-Fe-O tend to increase minutely with the increase of Sr content, bond angles Fe-O-Fe decreased accordingly. The Mossbauer spectra showed two sets of sharp sextets originating from ferric ions occupying the tetrahedral and the octahedral sites under the magnetic transition temperature T$_{N}$. Regardless of the compositions x, the electric quadrupole splittings were -0.3 mm/s and 0.4 mm/s for the octahedral and the tetrahedral site, respectively. Above T$_{N}$, the Mossbauer spectra showed the paramagnetic doublets whose electric quadrupole splittings were about 1.6 mm/s, irrespective of compositions x. T$_{N}$ was found to decrease monotonically with the increase of Sr concentration. Ratios of absorption area for the two sites were almost 1:1 up to as high as 0.95 T$_{N}$ for all x. The result of the Debye temperature indicated that the inter-atomic binding force for the Fe atoms in the tetrahedral site was stronger than that for the octahedral site.hedral site.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.710-715
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• 2010

Background: Video-assisted thoracic surgery (VATS) became common in the treatment of spontaneous pneumothorax (SP). Therefor we've reviewed the recurrence rate after VATS and analysed the factors affecting recurrent pneumothorax after VATS on this study. Material and Method: This retrospective analysis was performed on 321 patients of SP who had undergone VATS from Jan. 2001 to Dec. 2008. The two groups were divided as follow: group A, non-recurrent group (298 patients: 93%); and group B, recurrent group (26 patients: 7%); the two groups were analysed retrospectively. Result: The average age of the study groups were $20.9{\pm}4.3$ years old in recurrent group vs. $25.9{\pm}11.7$ years old in non-recurrent group with statistical significance (p < 0.05). There were no statistical significance in male to female ratio, height/weight ratio, location of pneumothorax, smoking history, operative time, duration of drain, hospital stay, indication of opertion and incidence rate. Average length of duration in recurrence was 12.9 months. There was 22 (95.7%) recurrent patients after VATS within 4 year period among recurrent group. Treatment methods in 23 of recurrent patients were, 8 (VATS), 2 (Axillary thoracotomy) with 15% or more in amount of pneumothorax and 7 (7 Fr. chest tube), 6 (nasal 02) with 15% or less in amount of pneumothorax. Among 10 cases of reoperation, there were 3 cases of over looking type and 7 cases of new growing type. There was no additional recurrence after these procedures were given. Conclusion: There was higher recurrence rate in younger age after VATS thus for those under 20 yrs old, detailed and possible preoperative warning for recurrence is warranted. Most recurrence occured within 4 year period, thus for this reason, regular interval based follow up with chest x-ray study is suggested during this period.

• The korean journal of orthodontics
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• v.36 no.1 s.114
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• pp.74-83
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• 2006

Analysis of lateral cephalometric radiograph (cephalogram) has been used routinely to evaluate skeletal and dental relationships, but analysis of the lateral facial photograph has not been used frequently for evaluation of skeletal relationships. As concerns about harm of X-ray irradiation increases, this study was planned to evaluate the possibility of substituting analysis of the lateral cephalogram with analysis of the lateral facial photograph by comparing these two analyses. According to the ANB values from cephalometric analysis, subjects were divided into three groups: Class I malocclusion group (n=32). Class II malocclusion group (n=32), and Class III malocclusion group (n=31). After measurements of angles indicating horizontal and vertical relationships of the maxilla and mandible on the lateral cephalograms and photographs, differences between Class I, II and III groups were evaluated. To evaluate the similarity between two similar values in the cephalograms and photographs, t-test using standardized variable Z and correlation analysis were performed in the Class I malocclusion group. The results showed that 1) SnN'Pg' on the photograph can be used to evaluate the antero-posterior relationship of the maxilla and mandible (ANB), 2) N'-Sn/Sn-Pg' on the photograph can be used to evaluate facial convexity (NA/APg), 3) Sn-Tra-Me' on the photograph can be used as a measurement similar to FMA. In conclusion, partly substituting lateral cephalogram analysis with lateral facial photograph analysis was possible in the evaluation of the maxilla and mandible.

• The korean journal of orthodontics
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• v.33 no.2 s.97
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• pp.121-130
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• 2003

The purpose of this study was to evaluate the possibile clinical application of electroplating to increase diameter of an orthodontic wire, through examining the change of physical properties. The diameter of stainless steel orthodontic wire was increased from 0.016 inch to 0.018 inch by electroplating in a bath of nickel sulfate 100g/L, nickel chloride 60g/L, boric acid 30g/L, and sodium chloride 50g/L, under the conditions of 1.7V, $25\~29^{\circ}C\;and\;3.1\~3.3pH$. During the electroplating, the rate of diameter increase was measured every minute. To investigate uniformity, the diameter was measured at three different locations of each wire specimen aster electroplating. An X-ray diffraction test was performed to analyze the nature of the electroplated metal. Following heat treatment to improve adhesion between the wire and electroplated metal, a three-point bending test was conducted to compare stiffness, field strength, and ultimate strength among four wire groups; 0.016 inch, electroplated 016, electroplated and heat-treated 016, and 0.018 inch wires. Through the comparison of each wire group, following results were obtained. 1. In the load-deflection graph, the curve of the electroplated group was Placed between that of the 0.016 inch group and the 0.018 inch group, and the owe was closer to the 0.018 inch group by heat treatment. 2. In the electroplated and heat-treated 016 wire group, the values of stiffness, yield strength and ultimate strength showed higher tendency than in the original 0.016 Inch group. Stiffness and ultimate strength showed statistically significant differences between two groups. 3. Stiffness, yield strength, and ultimate strength of electroplated wire presented lower values than those of 0.018 inch wire group. 4. Stiffness, yield strength, and ultimate strength of electroplated and heat-treated wire showed higher tendency than those of electroplated wire group, and ultimate strength showed statistically significant difference between two groups. 5. After electroplating, the difference in diameter between the three locations was within $0.1\~0.3\%$ variation, and showed no statistical significance.