• Nuclear Engineering and Technology
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• 제56권3호
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• pp.941-948
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• 2024

The effects of radiation on the corrosion of canister materials were investigated for the reliable disposal of high-level radioactive waste. The test specimens were gamma-irradiated at a very low dose rate of approximately 0.1 Gy/h for six and twelve months. The copper and cast iron species were less corroded when irradiated. It is hypothesized that gamma rays suppress the formation of lower-enthalpy species like metal oxides and activate reductive reactions. In contrast, it was difficult to evaluate the effect of radiation on the corrosion of titanium and stainless steel.

• 주물기술
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• 제4권2호
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• pp.1-7
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• 1980

• 월간포장계
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• 통권79호
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• pp.174-181
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• 1999

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.160-164
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• 2007

In the steel industry, there is a need to produce large forged parts for the automobile industries, the flight and shipping industries ad military industries. In the steel-industry application, a cogging technique for cast ingots is required, because the major parts are needed as one large body in order to obtain higher quality. Therefore, cogging process is the primary step in manufacturing of practically large open-die forging. In the cogging process, internal voids have to be eliminated as defects, The present work is concerned with the elimination of the internal voids in large ingots so as obtain sound products. In this study, hot compression tests were carried out to obtain the flow stress of cast microstructure at different temperature and strain rates. The FEM analysis are performed to investigate the overlap defect of cast ingots during cogging stage. The measure flow stress data were used to simulate the cogging process of cast ingot using the practical material properties. Also the analysis of void closure are performed by using the $DEFORM^{TM}$-3D. The calculated results of void closure behavior are compared with the measured results before and after cogging, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the void closure can be investigated by the comparison of practical experiment and numerical analysis.

• 한국주조공학회지
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• 제24권4호
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• pp.209-216
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• 2004

High silicon cast irons(HSCI) with the high acid resistance have been used for the prevention of acid corrosion occurring in various structures under acid conditions. However, the HSCI is only known as one of materials which have high acid resistance, but few work has dealt with this material in domestic. Therefore, in this study, the acid resistance of various cast irons with alloying elements and melting conditions have been examined, and studied the influences of the matrix structures, mechanical properties and morphologies of graphite. The results obtained in this study are as follows : In case of melting temperature, the mechanical properties of specimen manufactured with high temperature of $1650^{\circ}C$ showed higher value because the inclusion and impurity were removed. In case of pouring temperature, the mechanical properties of specimen fabricated below $1350^{\circ}C$ of pouring temperature showed higher value because the amount of gas absorption from atmosphere decreased during the solidification time. The corrosion rate decreased with increase in Si content. On the other hand, Mn addition appeared an opposite trend with Si.

• 한국유기농업학회지
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• 제5권1호
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• pp.125-135
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• 1996

A study was made to investigate the possibility of treating various organic waste of cattle manure, swine manure, goat manure, apple pomace, chinese medicine residue and coffee less by feeding these to earthworms and then by studying the growth and reproductive efficiency of earthworms, and the chemical composition of worm cast and its production. The results are summarized as follows. 1. When the feed for earthworms were in good condition which were cattle manure, swine manure and apple pomace, the reproductive efficiency of earthworms was improved however in worse condition the feed of which were goat manure and chinese medicine residue, the increasing rate(IR) became faster. 2. Despite the high content of organic matter(OM) in coffee lees, the earthworms fed coffee lees showed significantly lower reproductive efficiency and increasing rate(IR) than those fed other organic waste due mainly to its lower pH and lower total nitrogen(TN) content. Therefore, when coffee lees is considered to be fed to earthworms, it is believed necessary to be mixed with addiveves or other organic waste in order to improve the feed condition. 3. pH in swine manure, goat manure, apple pomace, chinese medicine residue and coffee lees became neutralized by being fed by earthworms. 4. Available P2O5 and exchangeable cation(EC) of earthworm cast were a little increased compared to those of feed. The contents of Mn, Fe and Cu in earthworm cast were a little decreased to compared to those of feed. 5. The contents of Mn, Fe and Cu in earthworm cast were a little a decreased to compared to those of feed. 6. Mean fresh weight of earthworm at final time(FW2) was negatively correlated with number of young worms(NY)(P<0.01), but positively with increasing rate(IR) (P<0.001) and C/N ratio(P<0.05) respectively. Number of cocoons (NC) and fresh weight of cocoons(WC) were positively(P<0.01) correlated with fresh weight of young worms (WY) and digested matter(DI) but negatively(P<0.001) correlated with residual matter(WY) and digested matter(DI) but negatively(P<0.001) correlated with residual matter(RW). Number of young worms(NY) and fresh weigh of young worms(WY) were negatively(P<0.001) correlated with increasing rate(IR), however increasing rate(IR) of earthworm was positively(P<0.05) correlatedd with C/N ratio.

• 한국임상수의학회지
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• 제24권4호
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• pp.658-662
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• 2007

The simple and easy treatment with cast or splint has been applied to stabilize long bone fractures in farm animals. Applying cast or splint is relatively easier than surgical fixation and may temporarily stabilize fracture site. However, the internal fixation provides strong stabilization and early recovery of limb function. In this report, we describe six cases of limb fractures in calves repaired by internal fixation. Fracture sites are various and affected ages are between 1 day and several months old. In some cases, patients were treated with cast or splint before admitting to Veterinary Medical Center. In these patients, regardless of initial treatment fractures were not immobilized. Consequently we decided to treat these patients with open reduction and internal fixation. The fracture repair with implants(bone plate, screw, cerclage wire, and intramedullary pin) were effective and satisfactory in calves which had been failed by application of cast. Although the cost of orthopedic treatment in farm animal is one of the most important considerations from the practical point of view, internal fixation has many benefits in newborn and young calves. And simplicity of postoperative management is also practically significant benefit expected from infernal fixation In conclusion, we suggest that internal fixation will produce better result than external coaptation in calve.

• 한국항공우주학회지
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• 제45권10호
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• pp.892-897
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• 2017

무기체계 SW 개발 전반에 대한 규정인 방위사업청의 무기체계 SW 개발 및 관리 매뉴얼이 개정될 때마다 SW 신뢰성 및 품질향상을 위해 SW 신뢰성 시험의 수준과 범위를 상향하는 방향으로 변경됨에 따라 SW 신뢰성 시험은 SW 개발자에게 큰 부담이 되고 있다. 특히 동적시험은 무기체계 SW를 구현하는데 필요한 일정과 인력에 육박할 정도의 비용이 소요되고 있으며, 1회성으로 그치지 않고 소스코드 형상이 변경될 때마다 수행해야 한다. 본 논문에서는 동적시험 도구인 VectorCast를 이용하여 동적시험을 최초 1회 수행한 후 소스코드 형상변경으로 인한 동적시험 회귀시험 시 사람의 개입을 최소화하여 자동으로 회귀시험을 수행하고 결과 보고서를 생성해주는 회귀시험 자동화 프로그램인 VectorCast Environment Manager 개발에 대해서 기술한다.

• The Journal of Advanced Prosthodontics
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• 제9권3호
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• pp.170-175
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• 2017

PURPOSE. The aim of the present study was to evaluate the fracture resistances of zirconia, cast nickel-chromium alloy (Ni-Cr), and fiber-composite post systems under all-ceramic crowns in endodontically treated mandibular first premolars. MATERIALS AND METHODS. A total of 36 extracted human mandibular premolars were selected, subjected to standard endodontic treatment, and divided into three groups (n=12) as follows: cast Ni-Cr post-and-core, one-piece custom-milled zirconia post-and-core, and prefabricated fiber-glass post with composite resin core. Each specimen had an all-ceramic crown with zirconia coping and was then loaded to failure using a universal testing machine at a cross-head speed of 0.5 mm/min, at an angle of 45 degrees to the long axis of the roots. Fracture resistance and modes of failure were analyzed. The significance of the results was assessed using analysis of variance (ANOVA) and Tukey honest significance difference (HSD) tests (${\alpha}=.05$). RESULTS. Fiber-glass posts with composite cores showed the highest fracture resistance values ($915.70{\pm}323N$), and the zirconia post system showed the lowest resistance ($435.34{\pm}220N$). The corresponding mean value for the Ni-Cr casting post and cores was reported as $780.59{\pm}270N$. The differences among the groups were statistically significant (P<.05) for the zirconia group, as tested by ANOVA and Tukey HSD tests. CONCLUSION. The fracture resistance of zirconia post-and-core systems was found to be significantly lower than those of fiber-glass and cast Ni-Cr post systems. Moreover, catastrophic and non-restorable fractures were more prevalent in teeth restored by zirconia posts.

• The Journal of Advanced Prosthodontics
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• 제9권2호
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• pp.124-129
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• 2017

PURPOSE. This study evaluated the effect of span length on the adaptation of implant-supported cobalt chromium frameworks fabricated by three techniques. MATERIALS AND METHODS. Models with two solid abutment analogs at different inter-abutment distances were digitized using a laboratory scanner. Frameworks of two-, three-, and four-unit fixed prostheses were designed by a computer. Six dots with a diameter of 0.2 mm were preset on the surface of each framework. A total of 54 implant-supported cobalt chromium frameworks were fabricated by milling, selective laser melting (SLM), and cast techniques. The frameworks were scanned and exported as Stereolithography files. Distances between two dots in X, Y, and Z coordinates were measured in both the designed and fabricated frameworks. Marginal gaps between the framework and the abutments were also evaluated by impression replica method. RESULTS. In terms of distance measurement, significant differences were found between three- and four-unit frameworks, as well as between two- and four-unit frameworks prepared by milling technique (P<.05). Significant differences were also noted between two- and three-unit frameworks, as well as between two- and four-unit frameworks prepared by cast technique (P<.05). The milling technique presented smaller differences than the SLM technique, and the SLM technique showed smaller differences than the cast technique at any unit prostheses (P<.05). Evaluation with the impression replica method indicated significant differences among the span lengths for any fabrication method (P<.05), as well as among the fabrication methods at any unit prostheses (P<.05). CONCLUSION. The adaptation of implant-supported cobalt chromium frameworks was affected by the span length and fabrication method.