• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.111-112
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• 2009

Diamond-like carbon (DLC) is a convenient term to indicate the compositions of the various forms of amorphous carbon (a-C), tetrahedral amorphous carbon (ta-C), hydrogenated amorphous carbon and tetrahedral amorphous carbon (a-C:H and ta-C:H). The a-C film with disordered graphitic ordering, such as soot, chars, glassy carbon, and evaporated a-C, is shown in the lower left hand corner. If the fraction of sp3 bonding reaches a high degree, such an a-C is denoted as tetrahedral amorphous carbon (ta-C), in order to distinguish it from sp2 a-C [2]. Two hydrocarbon polymers, that is, polyethylene (CH2)n and polyacetylene (CH)n, define the limits of the triangle in the right hand corner beyond which interconnecting C-C networks do not form, and only strait-chain molecules are formed. The DLC films, i.e. a-C, ta-C, a-C:H and ta-C:H, have some extreme properties similar to diamond, such as hardness, elastic modulus and chemical inertness. These films are great advantages for many applications. One of the most important applications of the carbon-based films is the coating for magnetic hard disk recording. The second successful application is wear protective and antireflective films for IR windows. The third application is wear protection of bearings and sliding friction parts. The fourth is precision gages for the automotive industry. Recently, exciting ongoing study [1] tries to deposit a carbon-based protective film on engine parts (e.g. engine cylinders and pistons) taking into account not only low friction and wear, but also self lubricating properties. Reduction of the oil consumption is expected. Currently, for an additional application field, the carbon-based films are extensively studied as excellent candidates for biocompatible films on biomedical implants. The carbon-based films consist of carbon, hydrogen and nitrogen, which are biologically harmless as well as the main elements of human body. Some in vitro and limited in vivo studies on the biological effects of carbon-based films have been studied [$2{\sim}5$].The carbon-based films have great potentials in many fields. However, a few technological issues for carbon-based film are still needed to be studied to improve the applicability. Aisenberg and Chabot [3] firstly prepared an amorphous carbon film on substrates remained at room temperature using a beam of carbon ions produced using argon plasma. Spencer et al. [4] had subsequently developed this field. Many deposition techniques for DLC films have been developed to increase the fraction of sp3 bonding in the films. The a-C films have been prepared by a variety of deposition methods such as ion plating, DC or RF sputtering, RF or DC plasma enhanced chemical vapor deposition (PECVD), electron cyclotron resonance chemical vapor deposition (ECR-CVD), ion implantation, ablation, pulsed laser deposition and cathodic arc deposition, from a variety of carbon target or gaseous sources materials [5]. Sputtering is the most common deposition method for a-C film. Deposited films by these plasma methods, such as plasma enhanced chemical vapor deposition (PECVD) [6], are ranged into the interior of the triangle. Application fields of DLC films investigated from papers. Many papers purposed to apply for tribology due to the carbon-based films of low friction and wear resistance. Figure 1 shows the percentage of DLC research interest for application field. The biggest portion is tribology field. It is occupied 57%. Second, biomedical field hold 14%. Nowadays, biomedical field is took notice in many countries and significantly increased the research papers. DLC films actually applied to many industries in 2005 as shown figure 2. The most applied fields are mold and machinery industries. It took over 50%. The automobile industry is more and more increase application parts. In the near future, automobile industry is expected a big market for DLC coating. Figure 1 Research interests of carbon-based filmsFigure 2 Demand ratio of DLC coating for industry in 2005. In this presentation, I will introduce a trend of carbon-based coating research and applications.

• Journal of Chest Surgery
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• v.29 no.6
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• pp.639-645
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• 1996

A 14-year-old male patient with previous surgical repair of tetralogy of Fallot was admitted with hemodynamically significant ventricular tachycardia (VT). On preoperative electrophysiologic study (EPS), the morphology of documented VT was RBBB of vertical axis with 320 msec cycle length. The endocardial mapping during VT delineated the origin of VT at right ventricular outflow tract (RVOT), where the patch was attached. The clinical VT had a clockwise reentry circuit around the patch with the earliest activation at the same site seen during the preoperative EPS. The previously placed right ventricular outflow patch and fibrous tissue were removed. During a postoperative EPS, it was no longer possible to induce the VT. Ventricular tachycardia following repair of tetralogy of Fallot seen in this patient was caused by a macro-reentry around the right ventricular outflow patch. We were able to ablate the VT with the aid of a detailed mapping of its epicardial activation sequence.

• The Korean Journal of Nuclear Medicine
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• v.31 no.3
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• pp.346-355
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• 1997

To evaluate the utility of I-131, T1-201 scintigraphy, and serum thyroglobulin(Tg) in the follow-up of differentiated thyroid cancer, we compared retrospectively the data from 33 patients who underwent total or subtotal thyroidectomy. I-131 scintigraphy was performed after optimal endogenous TSH stimulation ($TSH>50{\mu}U/ml$). Total 41 cases of I-131 and T1-201 scintigraphy pairs were examined. Concomitant serum thyroglobulin levels were measured for 41 pairs of scan. Tg-off levels(that measured after discontinuation of the thyroid hormone) higher than 40ng/m1 were considered positive, and Tg-on levels(that measured during the thyroid hormone replacement) higher than 5ng/ml were considered positive. The concordance rates between I-131 therapeutic scintigraphy and T1-201 scintigraphy was 48% in the 38 case of total scan pairs(59% in the 17 cases of postoperative preablation group, and 38% in the 21 cases of postoperative postablation group). Of 17 studies before the I-131 ablation therapy(preablation group), 7 showed positive I-131 therapeutic scintigraphy despite of negative T1-201 scintigraphy. Among patients with negative I-131 therapeutic scintigraphy, no patients had abnormal T1-201 uptake. However, of 21 studies which were done after radioiodine therapy(postablation group) 6 had abnormal uptake on T1-201 scintigraphy which were not seen on I-131 therapeutic scintigraphy, and Tg-off levels also elevated in this 4 of 6 cases. As a result, I-131 therapeutic scintigraphy showed highest positive rate at postoperative preablation follow-up study in differentiated thyroid cancer patients. T1-201 scintigraphy may be useful in postablation studies, and the use of the combined modalities(T1-201 and Tg levels) provides a higher diagnostic yield.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.429-435
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• 2009

Purpose: The purpose of this study was to assess the prognostic value of preoperative FDG-PET in colorectal cancer (CRC) patients with hepatic metastasis (HM). Materials and Methods: 24 CRC patients (M:F=14:10; age, $63{\pm}10$ yrs) with HM who had undergone preoperative FDG PET were included. Cure-intent surgery was performed in all the patients and HMs were controlled using resection (n=13), radio-frequency ablation (RFA) (n=7), and resection plus RFA (n=4). Potential prognostic markers tested were maxSUV of primary tumor, maxSUV of HM, maxSUV ratio of HM over primary tumor (M/P ratio), histologic grade, CEA level, venous/lymphatic/nerve invasion, T stage, N stage, no. of HM, no. of lymph node metastasis, and treatment modality of HM. Results: 14 CRC patients developed a recurrence with a median follow-up duration of 244 days, whereas 10 patients did not develop recurrence with a median follow-up duration of 504 days. M/P ratios but other potential prognostic markers were significantly higher in the recurrent patients ($0.72{\pm}0.14$) than recurrence-free patients ($0.54{\pm}0.23$) (p=0.038). M/P ratio only was found to predict recurrence by Cox multivariate analysis (hazard ratio 37.7, 95% confidence interval 2.01-706.1, p=0.016). The 11 patients with lower M/P ratio of <0.61 had significantly better disease-free survival rate than the 13 patients with higher M/P ratio (${\geq}0.61$) (p=0.026). Conclusion: maxSUV ratio of HM over primary tumor (M/P ratio) may be useful for prognosis prediction of CRC patients with HM. Higher FDG uptake of HM than that of primary tumor may indicate a more advanced status in stage IV CRC.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.411-420
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• 2009

Purpose: The aim of this study was to investigate the usefulness of $^{18}F$-FDG PET/CT with neck ultrasonography (neck US) in patients with recurrent, papillary thyroid cancer. Material and methods: This retrospective study (December 2006 to April 2008) enrolled sixty-one patients (ninety-one lesions) who underwent high-dose $^{131}I$-ablation therapy after total thyroidectomy, and evaluated recurred papillary thyroid cancer. All lesions were confirmed by histopathology and compared histopathologic findings to PET, PET/CT, and neck US findings. Results: In sixty-one patients (57 women, 4 men; age range, 24-81 years, mean 49 years; 61 papillary carcinomas), the sensitivity, specificity, accuracy of $^{18}F$-FDG PET/CT was 87.2%, 64.0%, 78.1% on a patient basis and 92.3%, 66.7%, 80.9% on a lesion basis, respectively. The sensitivity, specificity, accuracy of $^{18}F$-FDG PET was 71.8% (p=0.03), 59.0% (p=1.00), 67.2% (p=0.03) on a patient basis and 78.8% (p<0.01), 64.1% (p=1.00), 72.5% (p=0.02) on a lesion basis, respectively. The sensitivity, specificity, accuracy of neck US was 71.1% (p=0.07), 52.2% (p=0.75), 63.9% (p=0.05) on a patient basis and 71.2% (p<0.01), 61.5% (p=1.00), 67.0% (p=0.06) on a lesion basis, respectively. Combined $^{18}F$-FDG PET/CT with neck US improved the sensitivity, specificity, accuracy to 94.7% (p=0.50), 82.6% (p=0.13), 90.2% (p=0.03) on a patient basis and 96.2% (p=0.50), 89.7% (p<0.01), 93.4% (p<0.01) on a lesion basis, respectively. Conclusion: $^{18}F$-FDG PET/CT demonstrated significantly higher sensitivity than neck US for the detection of recurred papillary thyroid cancer lesions. Furthermore, combined $^{18}F$-FDG PET/CT with neck US showed more improved sensitivity, specificity, accuracy for diagnosis of recurrent papillary thyroid cancer.

• Economic and Environmental Geology
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• v.51 no.4
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• pp.323-343
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• 2018

This study defines the mineralogical, micro-textural and geochemical characteristics for the carbonate rocks and discusses the fluids that have affected the depositional environment of the Lower Makgol Formation in Seokgaejae section. Based on analysis of X-ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-ray Spectrometry (SEM-EDS), Electron Probe Micro Analyzer-Wavelength Dispersive X-ray Spectrometry (EPMA-WDS) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS), carbonate miorofacies in the basal and the lower members of the Makgol Formation are distinguished and classified into four types. Type 1 dolomite (xenotopic interlocking texture) and Type 2 dolomite (idiotopic interlocking texture) have relatively high Mg/Ca ratio, flat REE pattern, low Fe and Mn. Extensively interlocking textures in these dolomites indicate constant supply of Mg ion from hypersaline brine. Type 3 and Type 4 dolomite (scattered and loosely-aggregated texture) have relatively moderate Mg/Ca ratio, MREE enriched pattern, low to high Fe and Mn. These partial dolomitization indicate limited supply of Mg ion under the influx of meteoric water with seawater. Also, the evidence of Fe-bearing minerals, recrystallization and relatively high Fe and Mn in Type 4 indicates the influence of secondary diagenetic fluids under suboxic conditions. Integrating geochemical data with mineralogical and micro-textural evidence, the discrepancy between the basal and the lower members of the Makgol Formation indicates different sedimentary environment. It suggest that hypersaline brine have an influence on the basal member, while mixing meteoric water with seawater have an effect on the lower member of the Makgol Formation.

• Journal of Oral Medicine and Pain
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• v.30 no.2
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• pp.269-276
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• 2005

This in vitro study evaluated the influence of a flowable composite resin on the tensile bond strength of resin to enamel and dentin treated with Er:YAG laser and diamond bur. 96 Buccal enamel and mid-coronal dentin were laser-irradiated using an Er:YAG laser and treated with diamond bur. Each groups(48) were divided two small groups depends on acid-etching procedure. Light-cure flowable resin(Metafil Flo) and self-cure resin(Clearfil FII New Bond) were used in this study. After surface etching with 37% phosphoric acid and the application of an adhesive system, specimens were prepared with a hybrid composite resin. After 24hours storage in distilled water at 37$^{\circ}C$, all samples were submitted to the tensile bond strength evaluation, using a universal testing machine(Z020, Zwick, Germany). The obtained results were as follows: 1. TBS of acid-etching group were higher than those of non-etching group in both enamel and dentin treated with Er:YAG laser and diamond bur. Laser 'conditioning' was clearly less effective than acid-etching. Moreover, acid etching lased enamel and dentin significantly improved the microTBS of M-Flo. 2. In enamel, TBS of laser-irradiated group were lower than those of bur-prepared group. However, in flowable resin subgroup, there were not differed those between two groups in dentin. 3. In laser-treated group, TBS of flowable composite resin were higher than those of self-curing resin in dentin, however, there was no difference in enamel. From this study, we can conclude that the self- and light-cure composite resin bonded significantly less effective to lased than to bur-cut enamel and dentin, and that acid-etch procedure remains mandatory even after laser ablation. We suggest that Er:YAG laser was useful for preparing dentin cavity with flowable resin filling.

• Investigative Magnetic Resonance Imaging
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• v.17 no.3
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• pp.192-199
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• 2013

Purpose : To retrospectively evaluate the diagnostic performance of dynamic contrast-enhanced MR imaging (DCE-MRI) in detecting recurrent prostate cancer after HIFU of clinically localized cancer, as compared with T2-weighted imaging (T2WI). Materials and Methods: Twenty-six patients with increased prostate-specific antigen levels after HIFU were included in this study. All MR examinations were performed using T2WI and DCE-MRI, followed by transrectal ultrasound-guided biopsy. MRI and biopsy results were correlated in six prostate sectors. Residual or recurrent cancer after HIFU was defined as local tumor progression if biopsy results showed any cancer foci. Two independent readers interpreted the MR images. Results: Of 156 prostate sectors, 51 (33%) were positive for cancer in 17 patients. For detecting local tumor progression, the sensitivity of DCE-MRI and T2WI was 80% and 57% for reader 1 (P < 0.001) versus 84% and 61% for reader 2 (P < 0.001), respectively. The specificity and overall accuracy between DCE-MRI and T2WI showed no statistical difference in both readers (P > 0.05). Interobserver agreement of DCE-MRI and T2WI was moderate and fair, respectively. Conclusion: For detecting local tumor progression of prostate cancer after HIFU, DCE-MRI was more sensitive than T2WI, with less interobserver variability.

• The Korean Journal of Physiology
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• v.1 no.2
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• pp.169-175
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• 1967

An experiment was designed to see if the hippocampus exerts any influence upon the aggressive behavior of male rats. Fighting between rats was observed for the estimation of aggressiveness. Seventeen rats in which the hippocampus was almost totally removed through a small hole with a diameter around 3 mm made in the neocortex at the boundary between the parietal and occipital lobes (hippocampal group), 8 rats with similar neocortical damage alone (operated control group), and 17 normal control rats (normal group) were prepared and subjected to the experiment 3 months after the operation. Applying electric shock of short duration to the feet in a box with grid floor, a fight was provoked between an animal belonging to the hippocampal group and one belonging to the nor-mal group, between a rat of the hippocampal group and one of the operated control group, and also between a rat of the operated control group and one of the normal group. Three observers judged the performance of each animal independently and described it as winning, defeated, tied, or non-fighting. Fifteen shocked trials were administered to each pair of animals with around 2 minutes' interval between each trial. An animal received a 'judging score' of 3 when it won more frequently than was defeated, a judging score of 2 when it won as frequently as was defeated, when all fights were tied, or when no fighting occurred, while it received a judging score of 1 when it won less frequently than was defeated. Group differences in performances were analyzed in terms of judging score using Kolmogorov-Smirnov test for one sample. The results obtained were as follows: 1. In the fights between the hippocampal and the normal groups, the hippocampal animals made significantly better judging scores than the normal animals did (Table 1). 2. There was no significant difference between the hippocampal and the operated control group as to the judging scores they made in the course of fights between the two groups. However, the hippocampal animals tended to dominate over the operated control group as judged by comparing the total 'winning' of the former (30) to that of the latter (14) (Table 2). 3. The total judging score made by the operated control group in the course of the fights against the normal group was not significantly superior to that made by the normal group (Table 3). It was inferred from the above results that, though inconspicuous, the hippocampus tended to exert an inhibitory influence upon the aggressive behavior of male rats.

• The Korean Journal of Nuclear Medicine
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• v.34 no.4
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• pp.285-293
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• 2000

Purpose: A prospective comparison was made between imaging with Tc-99m pertechnetate (Tc-99m) and Ioine-131 (I-131) for the detection of residual and metastatic tissue after total thyroidectomy in patients with well-differentiated thyroid carcinoma. Materials and Methods: Initially our patients had imaging with Tc-99m, followed by I-131 within 3 days. The study included 21 patients who had ablation with high dose of I-131 ranging from 100 mCi to 150 mCi. Planar and pinhole images were acquired for both Tc-99m and I-131. Diagnostic images of Tc-99m and I-131 were compared with post-therapy images. Degree of uptake on Tc-99m and I-131 images was scored by four point scale and compared. Results: The results of the Tc-99m study were: 16 of 19 studies (84%) were positive on simple planar images, but 19 of 20 studies (95%) were positive on pinhole images. Conventional I-131 diagnostic imaging on the other hand showed that all studies (100%) were positive on both planar and pinhole images. There was a significant difference in degree of uptake between Tc-99m and I-131 planar images (p<0.05). Only one case of Tc-99m scintigraphy was negative on both planar and pinhole studies (false negative). There was no distant metastasis on the therapeutic I-131 images. Conclusion: Tc-99m scan using pinhole in certain clinical situations is an alternative to the I-131 scan in detecting thyroid or lymph node metastasis prior to the first ablative treatment after thyroidectomy for well-differentiated thyroid carcinoma.