• 열처리공학회지
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• 제17권6호
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• pp.356-364
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• 2004

The hydrides in cladding affect the corrosion and tensile properties. In this study corrosion and tensile properties were evaluated with varying the hydrogen concentration. The charged hydrogen contents were ranged from 200 to 1000 ppm. The corrosion rate in water and LiOH solution increases with the hydrogen concentration. The hydride did not affect the corrosion mechanism in the pre-transition region, but in the post-transition region the corrosion rate was accelerated. Cladding E contained higher Niobium content was slowly accelerated compared with other claddings. The yield and ultimate strengths were independent on the hydrogen content. However, the total elongation decreased gradually with increasing the hydrogen content. SEM observation of fracture surface showed that an average of depth of voids decreased with increasing the hydrogen content and small secondary crack are observed.

• 한국표면공학회지
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• 제48권6호
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• pp.275-282
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• 2015

The cost for maintenance (replacement cost) of Ni-superalloy components in plant industry is very expensive because of high unit price of INCONEL 718. A development of repairing technology using kinetic spray process can be very helpful for reducing the maintenance cost. However, it is very difficult to produce well-deposited INCONEL 718 layer showing high interfacial bond strength via kinetic spraying. Thus, INCONEL 718 was deposited on SCM 440 substrate and the interfacial properties were investigated, in order to elucidate the cause of hindrance to the bonding between INCONEL 718 layer and SCM 440 substrate. As a result, it was revealed that the dominant obstacle to the interfacial bonding was excessive compressive residual stress accumulated in the coating layer, resulting from low plastic-deformation susceptibility of INCONEL 718. Nevertheless, the bonding state was enhanced by the post heat-treatment through relieving the residual stress and generating a diffusion/metallurgical bonding between the INCONEL 718 deposit and SCM 440 substrate.

• 한국분말재료학회지
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• 제11권2호
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• pp.124-129
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• 2004

Nanosized WC and WC-Co powders were synthesised by chemical vapor condensation(CVC) process using the pyrolysis of tungsten hexacarbonyl(W(CO)$_6$) and cobalt octacarbonyl(Co$_2$(CO)$_8$). The microstructural changes and phase evolution of the CVC powders during post heat-treatment were studied using the XRD, FE-SEM, TEM, and ICP-MS. CVC powders were consisted of the loosely agglomerated sub-stoichimetric WC$_{1-x}$ and the long-chain Co nanopowders. The sub-stochiometric CVC WC and WC-Co powders were carburized using the mixture gas of CH$_4$-H$_2$ in the temperature range of 730-85$0^{\circ}C$. Carbon content of CVC powder controlled by the gas phase carburization at 85$0^{\circ}C$ was well matched with the theoretical carbon sioichiometry of WC, 6.13 wt％. During the gas phase carburization, the particle size of WC increased from 20 nm to 40 nm and the long chain structure of Co powders disappeared.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.934-937
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• 2003

Glasses in the system $CuO-P_2O_5-V_2O_5$ were prepared by a press-quenching method on the copper plate. The glass-ceramics from these glasses were obtained by post-heat treatment, and the crystallization behavior and DC conductivities were determined. The conductivities of the glasses were range from $10^{-6}s.Cm^{-1}$ at room temperature, but the conductivities of the glass-ceramics were $10^{-3}s.Cm^{-1}$ increased by $10^3$ order. The crystalline product in the glass-ceramics was $CuV_2O_6$. Heat-treatment conditions influenced the crystal growth of $CuV_2O_6$ and conductivity. The linear relationship between in (${\sigma}T$) and $T^{-1}$ suggested that the electrical conduction in the present glass-ceramics would be due to a small polaron hopping(SPH) mechanism.

• 한국재료학회지
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• 제29권8호
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• pp.483-490
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• 2019

Currently, the Korean nuclear industry uses ZIRLO as material for nuclear fuel cladding(zirconium alloy). KEPCO Nuclear Fuel is in the process of developing a HANA alloy to enable domestic production of cladding. Cladding manufacture involves multistage heat treatments and pickling processes, the latter of which is vital for the removal of defects and impurities on the cladding surface. SMUT that forms on the cladding surface during such pickling process is a source of surface defects during heat treatment and post-treatment processes if not removed. This study analyzes ZIRLO, HANA-4, and HANA-6 alloy claddings to extensively study the SEM/EDS, XRD, and particle size characteristics of SMUT, which are second phase particles that are formed on the cladding surface during pickling processes. Using the analysis results, this study observes SMUT formation characteristics according to Nb concentration in Zr alloys during the washing process following the pickling process. In addition, this study observes SMUT removal characteristics on cladding surfaces according to concentrations of nitric acid and hydrofluoric acid in the acid solution.

• Corrosion Science and Technology
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• 제22권2호
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• pp.131-136
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• 2023

The aim of this study was to investigate effects of microstructure control on hydrogen diffusivity, trap activation energy, and cracking behaviors of high-strength steel using a range of experimental techniques. Results of this study showed that susceptibility to hydrogen induced cracking (HIC) was significantly associated with hydrogen diffusivity and trap activation energy, which were primarily influenced by the microstructure. On the other hand, microstructural modifications had no significant impact on electrochemical polarization behavior on the surface at an early corrosion stage. To ensure high resistance to HIC of the steel, it is recommended to increase the cooling rate during normalizing to avoid formation of banded pearlite in the microstructure. However, it is also essential to establish optimal heat treatment conditions to ensure that proportions of bainite, retained austenite (RA), and martensite-austenite (MA) constituents are not too high. Additionally, post-heat treatment at below A₁ temperature is desired to decompose locally distributed RA and MA constituents.

• 열처리공학회지
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• 제36권4호
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• pp.215-222
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• 2023

3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals, 3Y-TZP) ceramics are emerging as dental implant materials due to their superior optical and mechanical properties as well as excellent biophysical properties, in spite of low bioactivity. In this study, we investigated to sintered properties and microstructural defects of dental zirconia implants fabricated by ceramic injection molding and post-HIP (Hot isostatic pressing) processing and analyzed the processing parameters related with the obtainment of its high sinterd density. Sintered and microstructural parameters, i.e, apparent density, grain size and phase composition of zirconia implants fabricated by injection molding were dependent on the fixtute size and implant type. Maximum sintered density of 99.2% and minimum grain size of 0.3-0.4 ㎛ were obtained from large-scaled 2-body sample. In 1-body ceramic implant, high sintered density of 99.5% was obtained, but it had a little monoclinic phase and wide grain size distribution.

• 대한수의학회지
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• 제62권2호
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• pp.1.1-1.8
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• 2022

Rehabilitation treatments after orthopedic surgery promote postoperative healing in humans. In veterinary medicine, there is increased interest in rehabilitation treatments because they are potentially beneficial to animals in the post-operation period. This study examined the effectiveness of rehabilitation treatment in dogs that underwent orthopedic surgeries, including femoral head & neck ostectomy (FHNO) and medial patellar luxation treatment (MPLT). The group that received the rehabilitation treatment after FHNO (1.88 weeks) showed a significantly shorter recovery length of 6.62 weeks compared to those that did not receive the treatment (8.50 weeks). The other group that received the rehabilitation treatment after MPLT (4.38 weeks) showed a significantly shorter recovery length of 5.01 weeks compared to those that did not receive the treatment (9.39 weeks). For the qualitative evaluation, the types and frequencies of rehabilitation treatments were monitored. The rehabilitation programs used frequently were heat therapy, laser therapy, passive range of motion, exercise therapy, and aquatic therapy. A standard rehabilitation program after hindlimb surgery was suggested based on the quantitative and qualitative investigation. The results add additional evidence that showed the beneficial effects of rehabilitation treatments in dogs.

• 한국균학회지
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• 제28권1호
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• pp.49-54
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• 2000

1. 저장 중 Penicillium에 이병된 사과, 배, 귤, 포도를 TLC 및 HPLC로 주요독소들을 검정한 결과 patulin만 검출되었고, citrinin은 검출되지 않았다. patulin 독소는 사과에서 $5.68\;{\mu}46.81\;{\mu}g/g$, 배에서 $3.48{\sim}84.71\;{\mu}g/g$, 귤에서 $0.16{\sim}0.27\;{\mu}g/g$검출되었으나 포도에서는 전혀 검출되지 않았다. 2. 과실류 Penicillium 저장 중 억제효과를 검정한 결과 사과, 배, 귤에 대하여 sodium hypochloride gas처리나 열처리$(37^{\circ}C)$에 의하여 방제효과가 켰으며 특히 열처리$(37^{\circ}C)$는 100%의 방제효과를 나타냈다. 처리에 의한 장해를 보면 열처리$(37^{\circ}C)$에서는 장해가 발생하지 많았으며 sodium hypochloride gas 처리에는 배, 귤에서 장해가 나타났으나 사과에서는 발생하지 않았다.

• 한국응용곤충학회지
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• 제51권2호
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• pp.131-140
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• 2012

벚나무응애(Tetranychus viennensis)는 사과 해충으로 수출시 일부 국가에서 주요 검역 대상 해충으로 알려져 있다. 환경조절열처리(controlled atmosphere temperature treatment system: CATTS)는 메틸브로마이드 훈증 처리의 대체 기술로서 과실류를 가해하는 다양한 곤충 및 기타 절지동물 해충류를 소독하는 기술로서 개발되었다. 본 연구는 복숭아심식나방(Carposina sasakii)을 방제하기 위해 개발된 CATTS 조건을 벚나무응애에 적용하였다. 먼저, 매실나무에서 벚나무응애를 채집하였고, 이를 형태적 특징으로 동정하였다. Cytochrome oxidase I (COI)과 internal transcribed spacer (ITS) 영역들의 염기서열은 형태적 동정 결과를 뒷받침하였다. 둘째로, 벚나무응애의 열처리에 대해 가장 높은 내성을 보이는 발육시기를 결정했다. 알, 약충과 성충을 $46^{\circ}C$에서 열처리를 하였을 때 성충에서 가장 높은 내성을 보였다. 셋째, 고온과 변경된 공기조건(1% 산소와 15%의 이산화탄소)을 결합하여 처리하였을 때 응애의 고온에 대한 감수성이 현격하게 증가하였다. 끝으로 CATTS 조건인 $46^{\circ}C$에서 15%의 이산화탄소 농도와 1%의 산소 농도에서 30분 처리는 벚나무응애의 모든 발육태에서 100%의 살비 효과를 나타냈다. 이러한 결과는 수확된 사과에 존재하는 벚나무응애를 사멸하는 데 CATTS 소독 처리 기술을 적용할 수 있다는 것을 제시하였다.