• 한국압력기기공학회 논문집
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• 제4권2호
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• pp.46-49
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• 2008

NDE(Nondestructive examination) detects a flaw or discontinuity in materials. Flaws detected by the pre-service or in-service examinations shall be sized for the purpose of analysis and repair. A flaw that is initiated from the surface is difficult to determine its depth by NDE. The depth of the surface flaw can be measured using an ultrasonic diffracted wave. To find the optimum standard for ultrasonic parameter(For example, frequency & size of transducer), a mock-up test and simulation were established and studied. This inspection technology may show the depth sizing possibility of the flaw down to nearly two(2) mm.

• 한국압력기기공학회 논문집
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• 제5권2호
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• pp.7-12
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• 2009

The flaws detected by the non-destructive surface test methods shall be sized by means of the volumetric test such as an UT(ultrasonic test) or an ECT(eddy current test) for the purpose of analyzing and repairing them. It is generally known that the ECT is a comparatively effective technique for the small size cracks which are located shallowly from the surface. On this study, the ECT technique was tried to size the depth of the crack-like EDM notches, and it is identified that the ECT is an appropriate depth sizing technique for the shallow cracks less than 3mm in the Martensitic CA6NM material.

• 펄프종이기술
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• 제35권3호
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• pp.43-52
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• 2003

The new principle to measure a sizing degree by a contact angle was developed using an automatic determination of the 3-end point coordinates of the water droplet on a sheet, which could diminish the operator's bias during measurement. A constant amount of water was first placed on a sample sheet by a water dispenser, and then an image of the liquid droplet was captured by a digital camera and then transmitted to a computer. The program measuring for contact angle extracted a liquid contour by Gaussian function combined with a 8-direction chain code. The Euclidean equation was applied to the binary image of the liquid contour in order to measure the diameter of the contour. Finally, the contact angle of the liquid was calculated by using the diameter and the top coordinates. In addition, a surface free energy of the sample sheet and an elapsed time taken up to the complete absorption into the sheet were simultaneously measured with the contact angle.

• 대한기계학회논문집
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• 제19권2호
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• pp.382-390
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• 1995

Failure of connecting rod in automotive engine may cause catastrophic situation. The corner radius at small end has an effect on stress raising. To investigate the stress distribution in connecting rod during operation, the finite element analysis was used by giving possible maximum tension and compression. Excessive sizing after forging connecting rod may result in the tensile residual stress which lower the fatigue life and cause premature failures. It was shown that when the sizing amount is too large, the location of high tensile residual stress coincide with that of high stress amplitude during operation through the elastic-plastic finite element analysis. The endurance limit moves down due to the surface finish and decarburization, which combines with the movement of resultant stress points to dangerous range. It was concluded that the precise control of sizing and enough corner radius are necessary to a reliability of connecting rod.

• 펄프종이기술
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• 제48권2호
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• pp.56-60
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• 2016

Neutral or alkaline papermaking provides many advantages in paper strength and processing conditions. It also provides the opportunity of using calcium carbonate fillers in papermaking. These diverse advantages have made almost all paper machines of printing and writing papers run under neutral and alkaline conditions. On the other hand, linerboard machines, which use recycled papers as a raw material, are running under acid conditions using a rosin sizing system. Because the recycled raw materials used by the linerboard industry contain significant amounts of alkaline papers, the linerboard industry has an interest in the possibility of using the neutral or alkaline papermaking opportunity. In this study, the compatibility of the recycled linerboards under neutral or alkaline papermaking conditions was examined by recycling them under various pH conditions. The sizing degree of the papers recycled under neutral or alkaline was significantly lower than that of acid formed papers indicating that during the neutral or alkaline recycling process the rosin sized papers lost their sizing efficiency. Recycling of acid formed linerboards under neutral or alkaline conditions increased the amount of foam, and the foam contained substantial amount of solid materials derived from the acid sizing systems. Use of cationic polyelectrolytes including PEI and poly-DADMAC improved the sizing degree of the recycled papers under neutral and alkaline conditions. PEI decreased the foam generation as well while poly-DADMAC did not show any reducing effect of the foam. These results suggest that PEI forms coordinate bonds with rosin acid and precipitate them onto the surface of recycled fibers, while the reaction products between poly-DADMAC and rosin acid ions still remain water soluble under neutral or alkaline conditions.

• 펄프종이기술
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• 제47권3호
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• pp.40-46
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• 2015

For some Korean newsprint mill, addition level of aluminum sulfate has been reduced because sulfur from aluminum sulfate has detrimental effect on the efficiency of anaerobic water treatment. At this moment, an unexpected decrease in sizing degree of TMP mixed newspaper was occurred. The phenomena means that hydrophobic substance usually originated from TMP cannot be fixed on the paper. This study focused on effect of alum and PAC on sizing of paper and contamination. Also, substitutability of PAC was discussed as a possible alternatives of aluminum sulfate under anaerobic condition of water treatment. Evaluation of sizing degree and pitch deposit potential were performed at the varied addition level of PAC and aluminum sulfate. Hydrophobic substance mainly derived from TMP could be fixed on the surface of fiber by PAC. Fines retention was not changed by replacing aluminum sulfate with PAC. Additionally, fixing of hydrophobic substance without excessive agglomeration can be enhanced by PAC with low molecular weight. Consequently, sizing degree of newspaper and contamination of recycling process of ONP can be controlled by low molecular weighted PAC.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Proceedings of Pre-symposium of the 10th ISWPC
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• pp.50-55
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• 1999

Sizing development of AKD-sized paper by beta-ketoester formation has been debated until recent years because of absence of its obvious and direct spectroscopic evidence. In this study, reaction between AKD and cellulose was investigated to disclose the possibility of beta-ketoester formation between two components under no catalyzed neutral condition. In absence of water, AKD reacted with cellulose to form beta-ketoester linkage under no catalyzed neutral condition, while, in presence of water, most of AKD was hydrolyzed to a dialkyl ketone or beta-ketoacid. Therefore, the main mechanism of AKD sizing would not be the formation of beta-ketoester between AKD and cellulose in the papermaking process. It could be suggested that the sizing development of AKD-sized paper is obtained by next two mechanisms: 1) formation of a thin-layer of AKD on the fiber surface through melting and spreading of AKD emulsion particles by heat, and 2) the formation of ketone by the hydrolysis of AKD during drying and storage of AKD-sized papers.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2007년도 추계학술발표논문집
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• pp.155-164
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• 2007

• 폴리머
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• 제38권5호
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• pp.620-625
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• 2014

Polyvinyl alcohol/polyamide-epichlorohydrin(PVA/PAE) 복합 지력증강제 처리에 따른 종이의 건조 및 습윤인장강도와 표면특성 변화를 살펴보았다. PVA/PAE 복합 지력증강제를 사용하는 경우, PVA와 PAE를 각각 첨가제로 사용하는 것에 비하여 건조 및 습윤 인장강도 증가와 함께 치수안정성이 우수해 짐을 알 수 있었으며 이는 PVA와 PAE의 물리적인 가교에 의한 결과로 해석할 수 있었다. PVA/PAE의 복합화는 PAE 지력증강제 처리에 의하여 발생하는 종이의 표면 거칠기의 증가를 최소화하며 동시에 사이징도 증가시켜 종이 인쇄 시 색농도 증가에 기여함을 알 수 있다.

• 소성∙가공
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• 제23권4호
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• pp.211-220
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• 2014

The outer race of a constant velocity (CV) joint having six inner ball grooves has traditionally been manufactured by multi-stage warm forging, which includes forward extrusion, upsetting, backward extrusions, necking, ironing and sizing, and machining. In the current study, a multi-stage cold forging process is examined and an assessment for replacing and modifying the conventional multi-stage warm forging is made. The proposed procedure is simplified to the backward extrusion of the conventional process, and the sizing and necking are combined into a single sizing-necking step. Thus, the forging surface of the six ball grooves can be obtained without additional machining. To verify the suitability of the proposed process, a 3-dimensional numerical simulation on each operation was performed. The forging loads were also predicted. In addition, a structural integrity evaluation for the tools was carried out. Based on the results, it is shown that the dimensional requirements of the outer race can be well met.