• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.395-400
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• 2006

Polylactic acids polymer (PLA) was applied as an additive to improve the strength properties of handsheets prepared from three unbleached southern pine kraft pulps with different kappa number and an aspen bleached chemithermomechanical pulp (BCTMP). The results showed that PLA could greatly improve the tensile and burst strength of the pulp handsheets. Heat pressing effect was also important to enhance the strength properties. For unbleached kraft pulps, it was found that an appropriate amount of residual lignin in pulps had a positive effect on the handsheets strength improvement when adding PLA. The thickness of the handsheet did not change the PLA strengthening effect. In general, PLA effect on tear strength improvement could be neglected. However, it had a significant effect on the improvement of tear strength for the aspen BCTMP handsheets not containing sufficient amount of fines.

• 펄프종이기술
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• 제45권1호
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• pp.59-66
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• 2013

Fillers have been used for printing paper to improve printability, sheet formation and optical properties and to reduce production costs by replacing expensive wood pulps. However, an increased filler content will decrease paper strength because filler particles interfere with fiber-fiber bonding. In order to increase filler content without sacrificing too much paper strength in high filler content papers, the surface of precipitated calcium carbonate (PCC) has been modified by adsorbing anionic polyacrylamide and cationic starch in series. The adsorbed polymer layers would enhance interactions between the filler surface and the fiber surface, improving internal bonding. It was found that the modified PCC increased paper strength at a given filler content compared to the coventional method. Negligible differences in optical properties and formation of paper, filler and fines retention and drainage on the wire section were observed between the modified and the conventional PCC. However, the decreased bulk of paper was observed when the modified PCC was used.

• 펄프종이기술
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• 제38권4호
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• pp.61-67
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• 2006

The effect of several inorganic flame-retardants such as ammonium phosphate, ammonium sulfate, aluminum hydroxide and antimony trioxide on the flame-retardant property and tensile strength of paper has been investigated. Flame-retardants were used preferably as a dry powdered mixture and added to the furnish. Both dipping and coating treatments were employed to apply flame-retardants to paper Flame-retardant paper was manufactured by treatment of $5{\sim}30%$ flame-retardants by weight of the paper on a dry weight. Paper's flame-retardant property and tensile strength were examined by comparison of char length and tensile index. As dosages of flame-retardant chemicals increased, flame-retardant property was improved but tensile index was decreased.

• 펄프종이기술
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• 제32권1호
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• pp.1-9
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• 2000

This study was carried out to improve the opacity of printing paper. Conventional filler loading enhanced the opacity of paper, but subsequently caused reduction of paper strength of paper. We try to seek a new filler loading method so-called beater loading that enhances opacity of paper as well as sustained desire strength. In our experiment, comparing to direct loading method, the beater loading method enhanced 0.8% of opacity and 0.2% of brightness. This also decreased the rates of strength reduction of paper. Therefore, the results obtained in this study indicated that beater loading was a very effective method to improve the opacity of paper while not to decreased so much of paper strength.

• 한국포장학회지
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• 제11권1호
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• pp.1-10
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• 2005

Paper angle, environment friendly packaging material, has been mainly used as an edge protector. But, we have perceived its application to package design of heavy product such as strength reinforcement or unit load system (ULS) in the future. Above all, understanding of buckling behavior for angle itself and compression strength and quality standard have to be accomplished for the paper angle to be used for this purpose. The purpose of this study was to elucidate the buckling behavior through theoretical and finite element analysis, and to develop compression strength model by compression test for symetric and asymetric paper angle. Based on the result of theoretical and finite element analysis, increasing rate of buckling of asymmetric paper angle was higher as applied load level was bigger and/or the length of angle was longer than that of symmetric paper angle. Decreasing rate of minimum principal moment of inertia was remarkably increased as the extent of asymmetric angle is bigger, and buckling orientation of angle was open direction near the small web. Increasing rate of maximum compression strength (MCS) for thickness of angle was smaller as the web size was bigger in symmetric angle. MCS of asymmetric angle of $43{\times}57$ and $33{\times}67$ was decreased $15{\sim}18%$ and $65{\sim}78%$, and change of buckling was increased $12{\sim}13%$ and $62{\sim}66%$, respectively.

• 한국지반신소재학회논문집
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• 제18권4호
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• pp.253-262
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• 2019

본 연구에서는 하수관 손상을 예방할 수 있는 CLSM을 개발하기 위하여, 산업폐기물인 제지애쉬를 이용한 CLSM의 일축압축강도 특성을 평가하였다. 이를 위해, 각각의 CLSM 배합조건에 따른 유동성시험 및 일축압축강도시험을 수행하였다. 먼저, 유동성시험 결과, 배합조건에 따라 유동성 기준을 만족하는 함수비의 범위는 24%~32%인 것으로 나타났다. 일축압축강도시험 결과, 강도는 재령일 1일에서 7일 사이에 높은 강도증가율을 보였으며, 이때 강도의 크기는 재령일 28일을 기준으로 발현된 전체 강도의 약 50% 이상인 것으로 확인되었다. 그리고 CLSM의 강도 증가는 플라이애쉬의 영향을 크게 받는 것으로 나타났지만, 개발하고자 하는 CLSM의 기준강도를 고려하면 제지애쉬의 배합이 요구되는 것으로 분석되었다. 또한 높은 시멘트 비율을 적용한 경우의 강도가 낮은 경우에 비하여 크게 발현되었지만, 기준강도를 고려하면 시멘트의 비율을 5%로 적용하는 것이 합리적인 배합조건이라고 판단되었다.

• Journal of the Korean Wood Science and Technology
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• 제30권2호
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• pp.134-143
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• 2002

본 시험은 외발뜨기 한지와 쌍발뜨기 한지의 물리적 특성과 도침이 지질에 어떠한 영향을 미치고 있는지를 구명하고자 검증된 토착한지와 오늘날 전통식으로 제조한 한지, 그리고 개량 한지를 대상으로 했다. 외발뜨기 한지는 치우치지 않는 강도적 특성 때문에 실제 사용할 때, 강하고 질기며 잘 해어지지 않는 종이임을 알 수 있었다. 이처럼 질기다고 느껴지는 것은 좋은 원료와 토착식 제법으로 여러 장 겹쳐서 절대적인 강도를 향상 시켰기 때문이었다. 그러나 상대적 강도인 지수비교에서는 기타 한지와 큰 차이가 없었다. 도침은 내절도를 두드러지게 향상시키며 열단장과 파열지수를 높이는 역할을 했다. 특히 열단장(인장강도)의 향상을 가져왔다. 섬유 배향성을 고려하지 않고 초지한 외발뜨기 한지를 쌍발뜨기 한지와 비교해 보면 가로·세로의 강도 차이가 약간 적다는 것 외에 특별히 뛰어난 점이 없다는 것을 알 수 있었다.

• 한국국방경영분석학회지
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• 제24권1호
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• pp.58-67
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• 1998

This paper studies on physical strength measurement utilized for selecting military sportsmen. In order to estimate physical potential capability of a volunteer for a sportsmen, scores of physical strength factors are used and a regression model is developed. And then the results of this model and current physical strength measurement are compared. This paper shows that the model developed here is more effective than current measurement, since measurable physical strength factors are reduced and physical strength factors are quantified by comparing each other.

• 국제초고층학회논문집
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• 제7권4호
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• pp.287-298
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• 2018

High strength steels have been widely applied in recent years due to high strength and good working performance. When subjected to fire conditions, the strength and elastic modulus of high strength steels deteriorate significantly and hence the load bearing capacity of structures reduces at elevated temperatures. The reduction factors of mechanical properties of high strength steels are quite different from mild steels. Therefore, the fire design methods deduced from mild steel structures are not applicable to high strength steel structures. In recent ten years, the first author of this paper has carried out a lot of fundamental research on fire behavior of high strength steels and structures. Summary of these research is presented in this paper, including mechanical properties of high strength steels at elevated temperature and after fire exposure, creep response of high strength steels at elevated temperature, residual stresses of welded high strength steel member after fire exposure, fire resistance of high strength steel columns, fire resistance of high strength steel beams, local buckling of high strength steel members, and residual strength of high strength steel columns after fire exposure. The results show that the mechanical properties of high strength steel in fire condition and the corresponding fire resistance of high strength steel structures are different from those of mild steel and structures, and the fire design methods recommended in current design codes are not applicable to high strength steel structures.

• 펄프종이기술
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• 제48권1호
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• pp.111-118
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• 2016

The effects of pulp beating degree and bulky promotor concentration on the properties of handsheet including a bulk and strength have been investigated during manufacturing of low density paper (high bulk paper) with cationic fatty acid bulky promotor. It was found that paper bulk increased with increasing cationic fatty acid bulky agent concentration, while tensile strength decreased. On the other hand the opacity of handseets also increased with increasing cationic fatty acid bulky agent concentration, while brightness decreased slightly. With increasing pulp beating degree, paper bulk as well as tensile strength increased, while opacity decreased. Brightness did not show a significant difference with increasing pulp beating degree. The highest bulk and strength values were observed when 1.5% (SwBKP) and 2% (HwBKP) of bulky promotor was treated into the 450 mL CSF pulp slurry.