• 벤처창업연구
• /
• 제9권2호
• /
• pp.15-21
• /
• 2014

주식과 선물간의 헤지비율의 시계열 안정성에 대한 연구는 아직 찾아보기 어렵다. 본 연구는 KOSPI200과 S&P500의 주식과 선물 지수를 이용하여 한국과 미국, 두 금융시장의 헤지비율에 대한 시계열 안정성을 연구한다. Coakley, Dollery, and Kellard(2008)는 1995년부터 2005년의 S&P500 현물을 대상으로 시계열 안정성을 확인하였다. 본 연구는 선행연구에서 시계열 안정성이 검증된 기간을 분석기간에 포함하여 두 시장을 분석함으로써 연구결과의 강건성을 얻고자 한다. 한국시장의 분석기간은 주식선물시장이 개설된 1996년부터 2005년이다. S&P500은 1982년부터 2004년을 분석대상으로 하고 있다. 본 연구는 BEKK and diagonal-BEKK을 사용하여 헤지비율을 구하며, 시계열 안정성 검증을 위하여 R/S와 GPH 방법을 사용한다. 분석결과는 시장효율성의 이론적 근거가 되는 랜덤워크가설을 지지하지 않는다. 이 결과는 헤지비율을 이용한 위험관리 방안에 대한 시사점을 제공한다.

• 펄프종이기술
• /
• 제43권3호
• /
• pp.59-65
• /
• 2011

The saw dust of tropical hardwood, Nyatoh(Palaquium Spp.), was used as a raw material for the preparation of the high valued microcrystalline cellulose(MCC). Three pulping methods, soda pulping, Kraft pulping, and acid-sulfite pulping were applied to obtain cellulose from the saw dust. The residual impurities were removed with the additional bleaching processes: (A) $ClO_2{\rightarrow}H_2O_2$; (B) $ClO_2{\rightarrow}O_3$; (C) $O_3$. For the acid treatment for MCC preparation, the $H_2SO_4$, with three concentration, 20%, 40%, 60% were applied and the effects of $H_2SO_4$ concentration on the properties of MCC were evaluated. The results indicated that the MCC obtained by acid-sulfite pulping followed with $O_3$ treatment and 40% $H_2SO_4$ treatment showed less residual lignin, higher brightness and crystallinity than that of Avicel MCC.

• Journal of Forest and Environmental Science
• /
• 제13권1호
• /
• pp.143-152
• /
• 1997

백색부후균인 Fomes pini (Thore) Lloyd에 의해 처리된 chip을 anthraquinone(AQ)을 첨가하여 화학 펄프화를 실시하여 얻은 결과를 미처리재의 것과 비교하였다. 균처리함에 의해 카파값 20에서의 H factor는 소다와 크라프트 증해에서 각각 17%와 15%가 감소되었다. 이러한 결과는 목재를 백색부후균으로 처리함으로 인해 탈리그닌이 용이해졌음을 나타내는 것이다. 비페놀성 ${\beta}$-O-4 화합물인 veratrylglycerol-${\beta}$-guaiacyl ether(I)와 페놀성 ${\beta}$-O-4 화합물인 syringylglycerol-${\beta}$-syringyl ether(III)에 백색부후균을 작용시키면 반응생성물로서 각각 ${\alpha}$-guaiacoxy-${\beta}$-hydroxypropioveratrone(II)과 ${\alpha}$-syringyloxy-${\beta}$-hydroxypropiosyringone(IV)이 생성됨이 밝혀졌다. 따라서 목재에 균처리를 함으로서 카르보닐기가 리그닌의 측쇄 ${\alpha}$ 위에 도입되어 그로 인해 탈리그닌이 용이하게 된 것으로 여겨진다.

• 펄프종이기술
• /
• 제44권4호
• /
• pp.32-42
• /
• 2012

Wood biomass including forest residues, waste wood, and construction residuals has been widely generated in Korea, but forest biomass from the National Forest Management Operation Project plays a big role in generating wood biomass. Unfortunately the promotion policy of woody energy organized by the Forest Service in Korea concentrates more on demand creation rather than on supply expansion. Therefore, in order to utilize insufficient wood resources effectively, it is greatly required to develop uses for maximizing their added value. In particular, more attention to the use of the second generation biomass has been paid in foreign countries because there is a threshold that the first generation biomass cannot produce enough biofuel without threatening food supplies and biodiversity. In Korea, wood pellets are regarded as the alternative clean fuels to oils and coals that emit green house gases into the atmosphere. However, using wood as pellet raw materials can not be an economic way because the value of wood disappears right after burning in the boiler in spite of its contribution to the decrease of carbon emission. Differently from wood pellets, kraft pulping process using woody biomass produces black liquor as a by-product which can be used to generate electricity, bioenergy and biochemicals through gasification. Thus, it can be more economical to make a torrefaction of lignocellulosic biomass such as low-quality wood and agricultural leftovers as raw materials of pellets.

• Geomechanics and Engineering
• /
• 제37권4호
• /
• pp.341-358
• /
• 2024

This paper reports several plane-strain trapdoor tests conducted to investigate the effects of reinforcement on soil arching development under localized surface loading with a loading plate width three times the trapdoor width. An analogical soil composed of aluminum rods with three different diameters was used as the backfill and Kraft paper with two different stiffness values was used as the reinforcement material. Four reinforcement arrangements were investigated: (1) no reinforcement, (2) one low stiffness reinforcement R1, (3) one high stiffness reinforcement R2, and (4) two low stiffness reinforcements R1 with a backfill layer in between. The stiffness of R2 was approximately twice that of R1; therefore, two R1 had approximately the same total stiffness as one R2. Test results indicate that the use of reinforcement minimized soil arching degradation under localized surface loading. Soil arching with reinforcement degraded more at unloading stages as compared to that at loading stages. The use of stiffer reinforcement had the advantages of more effectively minimizing soil arching degradation. As compared to one high stiffness reinforcement layer, two low stiffness reinforcement layers with a backfill layer of certain thickness in between promoted soil arching under localized surface loading. Due to different states of soil arching development with and without reinforcement, an analytical multi-stage soil arching model available in the literature was selected in this study to calculate the average vertical pressures acting on the trapdoor or on the deflected reinforcement section under both the backfill self-weight and localized surface loading.

• 펄프종이기술
• /
• 제30권3호
• /
• pp.38-45
• /
• 1998

Soil and water contamination caused by the abundant use of agricultural chemicals including herbicides and fertilizers draws public concerns since these chemicals may pollute the agricultural lands as well as the food products grown on these lands. As a method to reduce the use of agricultural chemicals mulching with thin plastic film has been commonly practised for many years. Although use of the plastic film for mulching is very effective in preventing the growth of weed, it is almost impossible to remove all of the plastic film from the agricultural land and the remaining film eventually contaminates the soils. Therefore, it is very imperative to develop a mulching material that decomposes completely to prevent soil pollution problems and to enhance the competitive edge of domestic agriculture. Mulch papers are believed to have many positive characteristics in preventing problems caused by the plastic mulch film since it decomposes completely after use. However, the basis weight of mulch papers needs to be reduced to improve its handling properties and to reduce the raw material costs of pulps. In this paper the possibilities of using domestic old corrugated containers in producing mulch papers were examined. Also use of unbleached softwood kraft pulps and dry strength additives were exploited along with two-layered sheet forming technology in decreasing the basis weight of the mulch paper. Results showed that reduction of 20g/$m^2$ of basis weight of mulch paper was possible by the appropriate raw material selection and application of strength resin. To use the mulch papers in paddy fields, however, further research to improve its durability should be pursued.

• 한국식품과학회지
• /
• 제20권1호
• /
• pp.1-5
• /
• 1988

건멸치 크기가 저장 안정성에 미치는 영향을 밝히기 위하여 KP/PE 포장한 건멸치를 $5^{\circ}C$에서 6개월간 저장하면서 주요 품질 지표성분의 변화를 조사하였다. 대멸의 TBA값, 지질산화에 의한 갈변 및 육 색깔의 변화는 중멸이나 소멸보다 켰다. 관능적인 기호도를 보통정도 수준인 3.0점을 기준으로 하여 저장기간을 설정하면 모두 6개월이상 저장 가능하였으나 소멸의 품질이 가장 우수하였고 다음이 중멸이었으며 대멸의 품질이 가장 나빴다. 대멸의 저장기간은 중멸이나 소멸의 약 절반에 상당하였다. 저장중 품질변화를 지질산화에 의한 갈변만 측정하여 관능검사와 같은 결과를 얻을 수 있는 회귀 방정식을 도출하였다.

• Journal of Microbiology and Biotechnology
• /
• 제16권6호
• /
• pp.921-926
• /
• 2006

The production and location of xylanolytic enzymes in alkaliphilic Bacillus sp. K-1, isolated from the wastewater treatment plant of the pulp and paper industry, was studied. When grown in alkaline xylan medium, the bacteria produced xylanolytic enzymes such as xylanase, $\beta$-xylosidase, arabinofuranosidase, and acetyl esterase. Two types of xylanases (23 and 45 kDa) were found to be extracellular, but another type of xylanase (35 and/or 40 kDa) was detected as pellet-bound that was eluted with 2% triethylamine from the residual xylan of the culture. The xylanases were different in their molecular weight and xylan-binding ability. Arabinofuranosidase and $\beta$-xylosidase were found to be intracellular and extracellular, respectively, and acetyl esterase was found to be extracellular. The extracellular xylanolytic enzymes effectively hydrolyzed insoluble xylan, lignocellulosic materials, and xylans in kraft pulps.

• Journal of the Korean Wood Science and Technology
• /
• 제48권5호
• /
• pp.651-665
• /
• 2020

Hydrolysis of biomass for the production of fermentable sugar can be improved by the addition of surfactants. In pulp and paper mills, lignin, which is a by-product of the pulping process, can be utilized as a fine chemical. In the hydrolysis process, lignin is one of the major inhibitors of the enzymatic breakdown cellulose into sugar monomer. Therefore, the conversion of lignin into a biosurfactant offers the opportunity to solve the waste problem and improve hydrolysis efficiency. In this study, lignin derivatives, a biosurfactant, was applied to enzymatic hydrolysis of various lignocellulosic biomass. This Biosurfactant can be prepared by reacting lignin with a hydrophilic polymer such as polyethylene glycol diglycidylethers (PEDGE). In this study, the effect of biosurfactants on the enzymatic hydrolysis of pretreated sweet sorghum bagasse (SSB), oil palm empty fruit bunch, and sugarcane trash with different lignin contents was investigated. The results show that lignin derivatives improve the enzymatic hydrolysis of the pretreated biomass with low lignin content, however, it has less influence on the enzymatic hydrolysis of other pretreated biomass with lignin content higher than 10% (w/w). The use of biosurfactant on SSB kraft pulp can increase the sugar yield from 45.57% to 81.49%.

• 한국작물학회지
• /
• 제36권3호
• /
• pp.266-270
• /
• 1991

미곡의 장기보관에서 보관면적과 소요비용을 절약하려면 정조보관보다 현미 또는 백미로 보관하는 것이 용이하다. 그러나 미곡의 고미화와 식미 악화가 우려되어 본 연구에서는 20개월간 정부창고에서 보관된 벼품종들을 정조, 현미, 백미로 가공하고 각각 지대, PP대, PE대에 포장하여 수확 후 32개월째에 발아력, 지방산도, 식미를 검정하였다. 1. 발아율은 장기 보관함에 따라 감소하였고 밀양 2003보다 추청의 감소가 심하였다. 가공상태에 따라 현미로 제현하여 보관하면 발아율 감소가 현저하였고 포장재질에 따른 차이는 없었다. TTC검정도 유사한 경향을 보여 발아력의 간접검정법으로 이용될 수 있었다. 2. 지방산도는 정조<백미<현미 순으로 높아졌고 포장재료에 따라서는 PP대<지대<PE대 순으로 증가되었다. 특히 현미 보관은 지방산도가 KOH 30mg 이상에 달하여 고미화 특성을 보였고 이를 방지하려면 정조를 지대 또는 PP대에 보관하거나 백미는 지대, PP대, PE대에 보관하여 도 무난하였다. 3. 저장미곡의 식미는 도정보관에 따라 악화되었고 특히 현미보관에서 백미보관 보다 불량하였는데 호분층에 포함된 지방의 산패 때문이었다. 또 품종별로 지방산도가 증가함에 따라 식미는 불량하여 졌다.