• 펄프종이기술
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• 제38권1호통권113호
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• pp.27-33
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• 2006

Newsprint is quantitatively the most important printing paper. The demands for its printability are continuously increasing. It is well known that the relationship between the physically tested paper properties and newspaper printability is unsatisfactory. In order to improve the printing quality of Korean newsprint, the printability coefficients such as maximum ink requirement(Ymax), print through were investigated. Kinds of newspapers and black printing ink were tested by IGT printability tester. Experiment condition of IGT printability tester was 14 steps between $0.2{\sim}2.8g/m^2$ of ink requirement, printing pressure was 200 N and printing velocity was 1 m/sec. The properties of newspaper samples (basis weight, bulk density, roughness, smoothness, porosity, i. e.) were examined in accordance with KS and TAPPI standard testing methods. The result of this study are respected for usefulness printing quality management of Korean newsprint.

• 대한전자공학회논문지TC
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• 제42권8호
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• pp.1-10
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• 2005

본 논문에서는 대수 이론과 관련된 일반화된 치환 행렬로부터 저밀도 부호의 명시적 구성을 고찰하였으며, 순환공식과 치환행렬에 관한 재킷 역 블록 행렬을 설계하였다. 설계 결과로부터 제안 기법은 저밀도 부호를 얻기 위한 간단하며, 고속화된 기법임을 알 수 있다. 또한, $\pi$-회전 LDPC(low density parity check) 부호와 같은 구조화 LDPC 부호 역시 저밀도 재킷 역 블록 행렬임을 증명하였다.

• 펄프종이기술
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• 제37권2호
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• pp.11-20
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• 2005

This study was carried out to investigate the influence of paper stock type and heat treatment on sizing effect. Various types of pulps were used to make handsheets sized internally with AKD(alkyl ketene dimer) and externally with CMC(carboxyl methyl cellulose). Most of the handsheets were treated with heat by dry oven $(100^{\circ}C,\;30min)$ to evaluate the effect of heat treatment on sizing development. Internal sizing development of newsprint was very bad, but the effect of heat treatment was much higher than those of NBKP, BCTMP. In case of surface sizing, newsprint was more effective compared to the other pulps. Considering above mentioned results, it seems that internal sizing slows down water into paper by molecular diffusion much more than capillary penetration, but surface sizing slows down capillary penetration. With regard to density, a higher thickness sheets showed high heat treatment effect on sizing, therefore it assumed that heat treatment effect on sizing had very close relationship with sheet density.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.164-165
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• 2015

Recently, the reason of using foamed concrete is for core of panel, filler of construction material to give lightness. However, cement causes environmental problem. The cement generates CO₂ but we normally use cement during manufacturing foamed concrete. Accordingly, this study focuses on dynamic properties of matrix according to the addition ratio of paper ash to make lightweight matrix with blast furnace slag and paper ash which are industrial by-product. The experiment progessed in order to select th optimum mixing ratio of the blast furnace slag and paper ash. There are totally 7 levels such as B100:P0, B95:P5, B90:P10, B85:P15, B80:P20, B75:P25, B70:P30 in this study. As a result of the test, B95:P5 matrix has the best density and compressive strength.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.197-198
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• 2006

The high pressure compaction without internal lubricant and the high green density even with the pore free density were achieved by the newly developed die wall lubricant for warm compaction. This developed die wall lubricated warm compaction followed by high temperature sintering resulted in not only the superior mechanical property but also the low dimensional change. In this paper, the effects of increasing the green density on the sintered density, the dimensional change and the mechanical property are mainly discussed

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2002년도 추계학술발표논문집
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• pp.36-46
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• 2002

The accurate characterization of paper structure may provide critical information for ideal selection of raw materials and papermaking processes as well as for predicting the behavior and the quality of final paper products. In this study, local paper structure and the relationship among the structural parameters, thickness, grammage, apparent density and surface roughness of various handsheet and commercial paper samples were evaluated by using recently developed methods. A new concept of surface roughness was also introduced. The results demonstrate that there is significant overestimation in the measured thickness when using the conventional caliper method that originates from the surface roughness and poor paper formation. A novel non-contact thickness tester, referred to as the twin laser profilometer(TLP), provided results that were not subject to these artifacts and thus provided the local intrinsic thickness and consequently the local intrinsic apparent density.

• 펄프종이기술
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• 제33권2호
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• pp.24-31
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• 2001

As a novel method to improve strength properties of recycled test liner, Condebelt press drying system was introduced and adopted into Korea. New press drying treatment could enhance the surface and strength properties in accordance with the increase of sheet density. However, Condebelt drying can not increase the density of repeatedly recycled test liner as much as that of virgin UKP and at the same density condition, the strength of Condebelt press dried UKP is greater than that of press dried test liner. In order to increase the strength of test liner, two attempts were tried in this study. First, addition of polyelectrolytes, dry strength agent was investigated with a view to promote the fiber bonding potential of reclaimed corrugated container pulp. Second, blending effect of fines were analyzed in an aims of increasing density and strength of test liner. The results were as follows; Even in the case of test liner densified by Condebelt press dryer, addition of amphoteric PAM as a dry strength agent was effective in increasing strength properties and so the effect of dry strength agent on improving bonding potential of recycled OCC fiber could be confirmed. As an appropriate addition level of amphoteric PAM, below 1% based on dry pulp weight was suggested. Different from virgin UKP, density of recycled test liner can be increased by the blending of OCC fines and strength properties also can be improved. However, excessive blending of OCC fines could result in decreasing of density and serious weakening of test liner. The best blending ration of fines in test liner can be determined as about 30%. Taking into account the fines content in general OCC pulp as 50%, excessive 20% of fines were supposed to be fractionated and removed in order to achieve the best strength of Condebelt press dried test liner.

• 펄프종이기술
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• 제34권1호
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• pp.7-11
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• 2002

The print quality of a ink jet printer is generally affected by three major components of the printing process: printer, ink formulation, and paper. The result of this study indicated that the surface sized paper with oxidized starch and cationic starch differed ink jet print quality in terms of ink spread and black optical density of the print image. Paper properties, like air permeability and siting degree, which may influence the ink jet printing were also measured. It was found that black print quality was controlled by starch level and ionic charge on the paper surface. Cationic surface sizing starch improved black ink jet print quality.

• 한국환경과학회지
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• 제27권9호
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• pp.797-802
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• 2018

Information about the density of fish eggs is important to understand the vertical distribution of eggs and survival in early stage, in particular change in egg density is one of major issue in fisheries. This paper describes a practical application of an experimental system for measurement of the fish egg density under laboratory conditions. The device can control the temperature range in each water column, and make different densities at each layer. The density of olive flounder (Paralichthys olivaceus) eggs have ranged from 1,018.49 to $1,020.93kg/m^3$ and were aggregated around the density of $1,020kg/m^3$. The results show that the device is applicable for measuring the fish egg density under laboratory conditions.

• 한국정밀공학회지
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• 제18권12호
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• pp.73-81
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• 2001

The MIAB welding uses a rotating arc as its heat source and is known as an efficient method fur pipe butt welding. The arc is rotated around the weld line by the electro-magnetic force resulting from the interaction of arc current and magnetic field. The electro-magnetic force is affected by magnetic flux density, arc current, and arc length. Especially, the magnetic flux density is an important factor on arc rotation and weld quality. This paper presents a 2D finite element model for the analysis of magnetic flux density in the actual welding conditions. The magnetic flux density is mainly dependent on gap between two pipes, the position of coil from gap center, exciting current, and relative permeability. Thus, the relations between magnetic flux density and main factors were investigated through experiment and analysis. Experiments were performed for the steel pipes(48.1mm O.D and 2.0mm thickness). The analysis results of magnetic flux density reveal that it increases with increasing exciting current, increasing relative permeability, decreasing distance from gap center to coil, and decreasing gap size. It is considered that the results of this study can be used as important data on the design of coil system and MIAB welding system.