• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1140-1147
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• 2001

Experimental schemes that enable characterization of phase-change phenomena in the microscale regime are essential for understanding the phase-change kinetics. Particularly, monitoring rapid vaporization on a submicron length scale is an important yet challenging task in a variety of laser-processing application, including steam laser cleaning and liquid-assisted material ablation. This paper introduces a novel technique based on Michelson interferometry for probing the liquid-vaporization process on a solid surface heated by a KrF excimer laser pulse(λ=248nm, FWHM=24ns) in water. The effective thickness of a microbubble layer has been measured with nanosecond time resolution. The maximum bubble size and growth rate are estimated to be of the order of 0.1㎛ and 1m/s, respectively. The results show that the acoustic enhancement in the laser induced vaporization process is caused by bubble expansion in the initial growth stage, not by bubble collapse. This work demonstrates that the interference method is effective for detecting bubble nucleation and microscale vaporization kinetics.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.38-44
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• 2000

In general liquid rocket nozzles are protected from hot combustion gas by regenerative cooling techniques. But due to the complexity of the cooling system, it causes increase of system cost and frequently source of the system malfunction. Recently, instead of regenerative cooing, ablative material are used to protect combustion chamber wall and nozzle. To determine the nozzle material erosion rate and erosion shape, more than 500 hot fire test were performed by using 100 lb thrust experimental liquid rocket. Test variable were propellant feed sequence, injector, position of igniter and liquid oxygen supply temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.528-531
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• 2000

Deposition of PZT with UV laser ablatio was applied for realization of thin film sensors and actuators. Deposition rate of more than 20nm/min was attained by pulsed KrF excimer laser deposition, which is fairly better than those obtained by the other methods. Perovskite phase was obtained at room temperature deposition with Fast Atom Beam(FAB) treatment and annealing. Smart MEMS(Micro electro-mechanical system) is now a suject of interest in the field of micro optical devices, micro pumps, AFM cantilever devices etc. It can be fabricated by deposition of PZT thin films and micromachining. PZT films of more than 1 micron thickness is difficult to obtain by conventional methods. This is the reason why we applied excimer laser ablation for thin film deposition. The remanent polarization Pr of 700nm PZT thin film was measured, and the relative dielectric constant was determined to about 900 and the dielectric loss tangent was also measured to be about 0.04. XRD analysis shows that, after annealing at 650 degrees C in 1 hour, the perovskite structure would be formed with some amount of pyrochlore phase, as is the case of the annealing at 750 degrees C in 1 hour.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.100-100
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• 2000

Aluminium oxide (Al2O3) films have been investigated for many applications such as insulating materials, hard coatings, and diffusion barriers due to their attractive electrical and mechanical properties. In recent years, application of Al2O3 films for dielectric materials in integrated circuits as gates and capacitors has attracted much attention. Various deposition techniques such as sol-gel, metalorganic decomposition (MOD), sputtering, evaporation, metalorganic chemical vapor deposition (MOCVD), and pulsed laser ablation have been used to fabricate Al2O3 thin films. Among these techniques, reactive sputtering has been widely used due to its high deposition rate and easy control of film composition. It has been also reported that the sputtered Al2O3 films exhibit superior chemical stability and mechanical strength compared to the films fabricated by other processes. In this study, Al2O3 thin films were deposited on Pt/Ti/SiO/Si2 and Si substrates by DC reactive sputtering at room temperature with variation of the Ar/O2 ratio in sputtering ambient. Crystalline phase of the reactively sputtered films was characterized using X-ray diffractometry and the surface morphology of the films was observed with Scanning election microscopy. Effects of Th Ar/O2 ratio characteristics of Al2O3 films were investigated with emphasis on the thickness dependence of the dielectric properties. Correlation between the dielectric properties and the microstructure was also studied

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.5
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• pp.388-393
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• 2021

At present, in Korea, due to developments in medicine and technology and an increasing mean lifespan, the expected lifetime for elderly people is increasing (at 70 years, the expected additional lifespan is 14.8 years for males and 18.3 years for females). However, among all causes of death, malignant neoplasm is ranked first for all ages. Further, the incidence rate of oral cancer tends to increase with age. Thus, oral and maxillofacial surgeons have increased opportunity to experience the 'oldest old' patients with oral cancer. Elderly patients commonly have several comorbidities, poor general condition, limited socioeconomic support, fear of various postoperative complications, and perception of short for the rest of their life. In this situation, the patient, caregiver, and surgeon often choose undergraded treatment rather than standard treatment for oral squamous cell carcinoma owing to patient age. In elderly patients with oral cancer, ablation of tumor or reconstructive surgery is challenging for surgeons. Oral and maxillofacial surgeons must evaluate carefully the patient's medical condition and make a decision regarding treatment plans after sufficient discussion with patient and caregivers. We review the literature to consider the factors involved for deciding on a treatment plan regarding surgery in elderly patients with oral cancer.

• Anatomy and Cell Biology
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• v.56 no.4
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• pp.428-434
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• 2023

Pulmonary veins (PVs) and their myocardial sleeves play an important role in the development of atrial fibrillation. Hence, detailed knowledge of PV anatomy is required to improve the procedural success rate and prevent complications during cardiac procedures. The aim of this study was to evaluate the PV anatomy along with anatomical variations in the Indian population. Total 100 formalin fixed cadaveric hearts were examined. The number and pattern of the PVs were observed along with the measurement of their horizontal and vertical diameters. The ovality index for each PV was calculated. Classical PV pattern was observed in 62% cases. Variant pattern like additional right middle PV pattern and left common PV pattern were found in 20% and 10% cases respectively. A separate pattern with presence of both right middle PV and left common PV was observed in 6% cases. In the classical pattern right superior PV was the largest followed by right inferior, left superior and left inferior PV. The additional right middle PV had the smallest diameter whereas the left common PV had the largest diameter. Almost all the veins had greater vertical diameters in comparison to horizontal diameters. The variant PVs were oval and had greater ovality index compared to the normal PVs. In classical pattern 54.8% hearts whereas in variant pattern 79% hearts had one or more oval PV. The given data can help clinicians for planning and execution of various interventional and electrophysiological procedures involving PVs.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.102-107
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• 2015

Purpose Serum Thyroglobulin measurement is a major tool for the follow-up of differentiated thyroid cancer (DTC) patients. Thyroglobulin is Normal thyroid tissue, or thyroid cancer tissue produced only. Thyroid hormone to a halt without Tg differentiation of thyroid cancer recurrence just by measuring how to decide whether there was increasing expectations if I can do it instead. Therefore, in excellent sensitivity Tg new inspection of the functional sensitivity by measuring the looked to evaluate the usefulness of reagents. Thyroidectomy is measuring the numbers Tg (total thyroidectomy) remaining thyroid ablation and radioactive iodine (radioactive iodine remnant ablation, RRA) DTC in patients being diagnosed with or help predict the remaining early detection of thyroid cancer recurrence. Materials and Methods Agent that I'm currently using Tg of the measurements of low clinical specimen for a second drainage of the three (0.08 0.17, 0.98, ng/mL) within the scope of the dilute magnification (2, 4, 8, 16, 32 times) by dilute Intraassy (n=10) and Interassay (n=10) out in no time. Concentration value according to the coefficient of variation and the mean and standard deviation of each measurement (Coefficient of variation, CV) the absolute value of the measured values that corresponds to 20 percent target a coefficient of variation of CV Find the value of the concentration of the functional sensitivity measurement did. Also, analytical sensitivity with recovery rates, Dilution test inspections, and interrelationship, compared. Results Sensitivity is an excellent analytical sensitivity within the prosecutor kit Tg 0.006 ng/mL, and core analytical sensitivity, conducted by the 0.006 ng/mL to same conclusion. Be rather high to 142 percent recovery rate was 60 to measurement and functional sensitivity, 0.01766 ng/mL(Intraassay n=10) was measured at. CBC is relatively good correlation as ($R^2=0.949$) the correlation. Conclusion Recently ultrasensitive thyroglobulin this clinically important indicators of the previous kit and demands are lower than sensitivity to the measurement results. Therefore, ultrasensitive thyroglobulin test is correlated that there would be useful in value in nuclear medicine the thyroid gland.

• Journal of Yeungnam Medical Science
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• v.15 no.2
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• pp.297-305
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• 1998

Recently, several alternatives have been attempted in the management of benign prostatic hyperplasia (BPH) to reduce morbidity of traditional transurethral resection of the prostate (TURP). Among new modalities, transurethral electrovaporization (TEVP) is considered as a promising alternative. To evaluate the safety and initial efficacy of JEVP using the roller loop electrode (ProSurg Inc. USA) on BPH patients, we compared the results of TEVP with those of TURP and visual laser ablation of the prostate (VLAP). In this study, a total of 115 patients with symptomatic BPH were underwent TEVP (n=17), TURP (n=59) or VLAP (n=39) since 1995. Before treatment, patients were evaluated with an International Prostate Symptom Score (IPSS) and the measurement of maximal uroflow rate (MFR) and postvoid residual urine (PVR). After treatment, the operative and hospital records were reviewed. The uroflowmetry and IPSS were re-evaluated 3-10 months after treatment. In clinical outcome of re-evaluation compared to the preoperative parameters, there was a clinically significant improvement in three procedures. TEVP resulted in 62% reduction in IPSS (TURP, 73% : VLAP, 69%), 84% improvement in MFR (TURP, 113% : VLAP, 91%), and 74% reduction in PVR (TURP, 88% : VLAP, 78%). TEVP had shorter duration of hospitalization and catheterization than the others. TEVP was associated with lower rates of treatment-related complication than TURP. In conclusions, TEVP is considered as a useful procedure to treat symptomatic BPH. And, the advantages of TEVP over TURP include excellent intraoperative hemostasis, lower morbidity, shorter hospital stay and simple technique. In addition the advantages over VLAP include lower cost, shorter duration of catheterization and early symptom improvement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1301-1307
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• 2011

Electrosurgical knee wand (EKW) is a high-frequency thermocautery instrument and is often used for coagulation, ablation, excision, and extirpation of knee ligaments and tissues. In order to maximize the success rate, ease, and safety of knee surgery using EKW and radiofrequency ablation, it is necessary to ensure that the EKW selectively approaches the lesion with utmost accuracy and safety. The key feature of this instrument is its excellent maneuverability. Hence, the authors constructed a tensile spring model based on a shape memory alloy (SMA), which exhibits the shape memory effect. This model can be used in knee surgery as it is considered the most biocompatible femorotibial surgical actuator. The changes in external temperature with current and the thermoelectric characteristics of the SMA were investigated. The relationship between the restoring force and the typical stroke (TS) in response to the conditions in the SMA tensile spring design were evaluated. In conclusion, as the diameter of the SMA tensile spring decreased, the maximum temperature increased. The strain in the actuator caused a stable and proportional increase in the force and induced current for up to 15s, but this increase became very unstable after 30s. Moreover, the relationship between the current and the TS was more stable than that between the current and the restoring force.

• Journal of Digestive Cancer Research
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• v.2 no.2
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• pp.75-77
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• 2014

Ampulla of Vater (AOV) cancer is rare malignant tumor which arises within the vicinity of the AOV. Metastatic AOV adenocarcinoma has poor prognosis, with an overall survival rate at 2 years ranging from 5 to 10%. The Surveillance, Epidemiology and End Results Program of the National Cancer Institute indicated that lymph node metastasis was present in as many as half of patients which were associated with poor prognosis and liver was the second most common site of distant metastasis in AOV cancer. In this case report, we describe a case of complete resolution of AOV cancer, which was already spread to retroperitoneal lymph node and liver. The patient underwent gemcitabine plus cisplatin chemotherapy for palliative aim. After 12 month of chemotherapy, image study showed partial remission, so intraoperative radiofrequency ablation therapy and pylorus preserving pancreaticoduodenectomy was done. AOV cancer was completely resected and the patient was followed up without recurrence for 7 months.