Fundamental aspects of creating passivation layers for corrosion resistance in nuclear engineering applications, specifically the ability to form complete layers versus porous ones, are being explored in this study. Utilizing a laser ablation technique, 1,064 nm fire at 10 Hz with 60 pulses per shot and 0.5 mm between impact points, aluminum samples are treated in an attempt to create a fully formed passivation layer that will be tested in a LiCl-KCl eutectic salt. By placing these samples into an electrochemical environment mimicking a pyroprocessing system, corrosion rates, resistances and material characteristics are tested for one week and then compared between treated and untreated samples. In initial testing, linear sweep voltammetry indicates corrosion current density for the untreated sample at −0.038 mA·cm−2 and treated samples at −0.024 mA·cm−2 and −0.016 mA·cm−2, respectively. This correlates to a control sample corrosion rate of −0.205 mm·yr−1 and treated rates of −0.130 mm·yr−1 and −0.086 mm·yr−1 for samples 1 and 2. In addition, electrochemical impedance spectroscopy circuits show application of a longer-lasting porous passivation layer on the treated metal, compared to the naturally forming layer. However, the current technique fails to create a uniform protection layer across the sample.

Radioactive Oxide is formed on the surface of the coolant pipe of the nuclear power plant. In order to remove the oxide film that is formed on the surfaces of the coolant pipe, chemical and physical decontamination technologies are used. The disadvantage of traditional technologies is that they produce secondary radioactive wastes. Therefore, in this study, the short-pulsed laser eco-friendly technology was used in order to reduce the production of secondary radioactive wastes. It was also used to minimize the damage that was caused to the base material and to remove the contaminated oxide film. The study was carried out using a Stainless steel 304 specimen that was coated with nickel-ferrite particles. Additionally, a transport robot was 3D modeled and manufactured in order to efficiently remove the oxide film from the coolant pipe of the nuclear power plant. The transport robot has a fixed laser head to move inside the horizontal and vertical pipes. The rotating laser head removes the contaminated oxide film on the inner surface of the coolant pipe. In the future, as a condition of the 1064nm short-pulsed laser ablation technique determined by basic analysis, we plan to analyze whether the transport robot is applicable to the radiation contamination site of the nuclear power plant.

In this work, the ablation behavior of monolith ZrB2-30 vol%SiC (Z30S) composites were studied under various oxy-acetylene flame angles. Typical oxidized microstructures (SiO2/SiC-depleted/ZrB2-SiC) were observed when the flame to Z30S was arranged vertically. However, formation of the outmost glassy SiO2 layer was hindered when the Z30S was tilted. The SiC-depleted region was fully exposed to air with reduced thickness when highly tilted. Traces of the ablated and island type SiO2 were observed at intermediate flame angles, which clearly verified the effect of flame angle on the ablation of the SiO2 layer. Furthermore, the observed maximum surface temperature of the Z30S gradually increased up to 2,200 °C proving that surface amorphous silica was continuously removed while monoclinic ZrO2 phase began to be exposed. A proposed ablation mechanism with respect to flame angles is discussed. This observation is expected to contribute to the design of complex-shaped UHTC applications for hypersonic vehicles and re-entry projectiles.

The effect of the laser ablation duration of reduced graphene oxide sheets on their optical properties was studied. After 30 min of ablation, the average lateral size of reduced graphene oxide sheets decreases from 347.4 ± 86.5 nm to 98.8 ± 36.0. The sizes of almost all particles are in the range up to 100 nm, which was confirmed by transmission electron microscopy and dynamic light scattering data. The FTIR spectroscopy data showed that after ablation the intensity of the bands associated with O–H, C–OH and C=O vibrations were noticeably decreased. The optical density and the fluorescence intensity of reduced graphene oxide also depend on the ablation time. After ablation, the reduced graphene oxide fluorescence intensity increased 2–3 times. The fluorescence lifetime decreases both for the first (from 1.36 ns to 0.71 ns) and second (from 6.03 to 3.66 ns) components. A broad band was recorded in the long-lived luminescence spectrum. The long-lived luminescence intensity is higher on 80% for the samples after 30 min of ablation compared to the unablated sample. It was assumed that during laser ablation of reduced graphene oxide a change in the ratio between oxidized and sp2- hybridized carbon occurs. This opens up possibilities for controlling the optical properties of reduced graphene oxide.

Prognosis of unresectable pancreatic cancer is poor with the rate of surviving more than 5 years is less than 10% despite multi-modalities treatment. The American Society of Clinical Oncology suggested that all patients with metastatic pancreatic cancer should be offered information about clinical trials. Endoscopic ultrasound guided radio frequency ablation has been recently used in patients with advanced stage pancreatic cancer in a few studies. This article has reviewed information from published articles using endoscopic ultrasound guided radio frequency ablation for advanced pancreatic cancer.

In order to improve the thermal shock and ablation resistance of high thermal conductivity carbon/carbon composites, carbon nanotubes (CNTs) were introduced by electrophoretic deposition. After modification, the flexural strength of the composites increases by 53.0% due to the greatly strengthened interfaces. During thermal shock between 1100 °C and room temperature for 30 times, the strength continues to increase, attributed to the weakened interfaces in favor of fiber and CNT pull-out. By introducing CNTs at interfaces, thermal conductivity of the composites along the fiber axial direction decreases and that along the fiber radial direction increases. As the thermal shock process prolongs, since the carbon structure integrity of CNT and matrix in the modified composites is improved, the conductivity increases whatever the orientation is, until the thermal stress causes too many defects. As for the anti-ablation performance, the mass ablation rates of the CNT-modified composites with fibers parallel to and vertical to the flame decrease by 69.6% and 43.9% respectively, and the difference in the mass ablation rate related with fiber orientations becomes much less. Such performance improvement could be ascribed to the reduced oxidative damage and the enhanced interfaces.

진단 및 치료의 발전에도 불구하고 췌장담도 악성 종양은 여전히 증가하고 있다. 수술적 절제는 유일한 완치를 기대할 수 있는 치료법이지만 대부분의 환자들은 초진단 시 국소 진행 또는 전이성 종양으로 확인되기 때문에 수술이 불가능한 경우가 많다. ERCP 또는 EUS 유도하 RFA와 광역학치료 등은 직접적으로 암 조직을 소작할 수 있는 국소 치료법으로 예후가 불량한 췌장담도암 환자에서 효과적인 치료법으로 기대를 모으고 있다. 아직 충분한 연구가 진행되지는 못하였지만 ERCP 유도하 ID-RFA는 악성 담도 협착에서 안정성과 유용성이 확인되었고, 추가적인 연구를 통해 장기 효과에 대한 검증이 진행되고 있다.

In this paper, we investigated the effect of the passivation stack with Al2O3, hydrogenated silicon nitride (SiNx:H) stack and Al2O3, silicon oxynitride (SiONx) stack in the n type bifacial solar cell on monocrystalline silicon. SiNx:H and SiONx films were deposited by plasma enhanced chemical vapor deposition on the Al2O3 thin film deposited by thermal atomic layer deposition. We focus on passivation properties of the two stack structure after laser ablation process in order to improve bifaciality of the cell. Our results showed SiNx:H with Al2O3 stack is 10 mV higher in implied open circuit voltage and 60 μs higher in minority carrier lifetime than SiONx with Al2O3 stack at Ni silicide formation temperature for 1.8% open area ratio. This can be explained by hydrogen passivation at the Al2O3/Si interface and Al2O3 layer of laser damaged area during annealing.

목적 : 각막굴절교정수술 후 저평가되는 안압을 다양한 각막 절삭량에 따라 경도, 중등도, 고도 근시 군을 나누어 조사하고, 각 군별로 가장 적합한 수술 후의 안압 보정방법을 제시하고자 하였다. 방법 : 각막굴절교정수술을 받은 평균 연령 26.89±5.18세의 남녀 501명 1,002안(남자 237명, 여자 264명)을 대상으로 하였다. 안압은 비접촉식 안압계를 이용하여 측정하였고, 수술 후 저평가된 안압을 보정하기 위해 Ehlers, Shah, Dresden, Orssengo/Pye의 보정방법을 이용하였다. 다양한 각막 절삭량에서의 안압 차이를 비교하기 위해 세 그룹으로 나누어 분석하였다. 결과 : 비접촉식 안압계로 측정한 수술 전 안압은 15.67±2.39 mmHg이었고, 수술 후 안압은 10.12±2.11 mmHg로 평균 5.55±2.09 mmHg 만큼 유의하게 낮게 측정되었다. Ehlers의 보정방법으로 산출된 수술 후의 안압은 14.53±2.47 mmHg로 수술 전 안압과 평균 1.14±2.83 mmHg 차이를 보여 네 가지 보정방법 중에서 수술 전 안압 측정치와 가장 비슷한 수치를 보였다. 또한 각막 절삭량에 따라 나눈 경도, 중등도, 고도근시 각 군 모두에서 Ehlers 식으로 보정된 안압이 수술 전 안압과 차이가 가장 적게 나타났다. 결론 : 굴절교정수술 후 고도근시를 포함한 다양한 근시군 모두에서 4가지 보정방법 중 Ehlers 보정법이 가장 유용한 것으로 판단된다. 이 결과는 각막굴절교정수술 후 저평가되는 안압의 실제 값을 산출하여 녹내장에 대한 조기진단 및 치료시기가 늦어지는 것을 막는 데에 활용할 수 있을 것이라 생각된다.

목적: 각막굴절교정수술 후 각막절삭량에 따른 안압변화와 수술 전 굴절이상도에 따른 수술 후 안압 변화에 대하여 알아보고자 하였다. 방법: 라식 각막굴절교정수술을 받은 평균연령 37.34±7.42세, 성인 남녀 108명(남자 48명, 여자60명)을 대상으로 선정하였다. 자동굴절검사기, 비접촉형안압계, 엑시머레이저를 이용하여 굴절이상도, 안압, 각막 절삭량을 측정하였으며, p<0.05일 때 통계적으로 유의하다고 판단하였다. 결과: 각막굴절교정수술 전 안압은 남자가 15.08±2.60mmHg, 여자가 14.16±2.67mmHg로 남자가 여자보다 높게 나타났으며, 각막굴절교정수술 후 안압 감소량은 남자가 4.22mmHg, 여자가 3.61mmHg로 나타났다. 등가구면 굴절력은 각막굴절교정 수술 전 남자 –3.89±2.17D, 여자 –4.45± 2.92D에서, 각막굴절교정 수술 후 남자 -0.10±0.46D, 여자 –0.04±0.46D로 나타났다. 각막굴절교정수술 후 각막절삭량은 남자 53.95㎛, 여자 61.26㎛로 통계적으로 유의한 차이가 있었으며, 각막절삭량과 안압의 감소량에는 유의한 상관성(r=0.2299, p<0.001)을 보였다. 성별로는 남자의 각막절삭량이 많아질수록 안압의 감소량은 유의하게 증가하는 것으로 나타났다. 굴절이상도가 증가할수록 안압의 감소량도 커져 경도의 굴절이상도에서는 3.04±2.18mmHg, 중등도의 굴절이상에서는 4.10±2.16mmHg, 고도의 굴절이상도에서는 4.65 ±3.29mmHg가 감소하는 것으로 나타났다. 결론: 각막굴절교정수술 후 비접촉식 안압계로 측정한 안압은 감소하는 것을 알 수 있었으며, 안압측정은 녹내장 판단에 영향을 줄 수 있으므로 안압 측정시 각막굴절교정수술 여부에 대한 사전설문이 필요할 것으로 생각된다.

Stainless steel is being used in various industries such as automobile and aerospace for its cheap manufacturing cost and excellent mechanical properties. However, stainless steel failed to stably protect a specimen with a Cr2O3 protective layer at temperatures above 1000 ℃. Thus, improving the high temperature flame resistance of the specimen through additional surface coating was needed. In this study, multilayer coatings of YSZ and Al2O3 were performed on SUS 304 specimens using pack cementation coatings and thermal plasma spray. The multilayer coated specimen showed enhanced thermal properties due to the coated layers. The microstructures and phase stability are discussed together with flame conditions at 1350 ℃.

Ablative material in a rocket nozzle is exposed to high temperature combustion gas, thus undergoes complicated thermal/chemical change in terms of chemical destruction of surface and thermal decomposition of inner material. Therefore, method for conjugate analysis of thermal response inside carbon/phenolic material including rocket nozzle flow, surface chemical reaction and thermal decomposition is developed in this research. CFD is used to simulate flow field inside nozzle and conduction in the ablative material. A change in material density and a heat absorption caused by the thermal decomposition is considered in solid energy equation. And algebraic equation under boundary layer assumption is used to deduce reaction rate on the surface and resulting destruction of the surface. In order to test the developed method, small rocket nozzle is solved numerically. Although the ablation of nozzle throat is deduced to be higher than the experiment, shape change and temperature distribution inside material is well predicted. Error in temperature with experimental results in rapid heating region is found to be within 100 K.

수술이 불가능한 담관암에서 담관 내 고주파 열치료는 악성 담관 폐쇄를 호전시키는 실용적인 치료로 보고되고 있으나, 내시경적 역행성 담췌관조영술을 이용한 고주파 열치료는 투시조영을 통해 열을 적용하는 방법으로, 병변을 직접 시각화하지 못하는 단점이 있다. 반면에, 직접 경구 담관 내시경하 담관 내 고주파 열치료는 담관 내 병변을 시각화함으 로써 카테터의 삽입 등에 용이하며 시술로 인한 합병증을 감 소시킬 수 있을 것으로 기대되고 있다. 본 증례에서는 총담 관십이지장문합술을 시행 받은 담관암 환자에서 직접 경구 담관 내시경하 담관 내 고주파 열치료를 적용하여서 스텐트 시술 없이 담관 개존을 보존한 첫 번째 사례로서 직접 경구 담관 내시경하 담관 내 고주파 열치료의 효용성을 문헌 고찰과 함께 보고하는 바이다.