• Journal of the Korean Wood Science and Technology
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• v.29 no.2
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• pp.69-75
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• 2001

This study was carried out to investigate the properties of woodceramics made from thinned logs of Cryptomeria japonica. In order to find the effect of steam injection time on the woodceramics fabricated with boards, boards were made with the non-steamed treatment and steamed treatment 1, 5, 10 min. at $250^{\circ}C$. The percentage of weight loss was proportional to the increased density of board The reducing rate of length and thickness, however, decreased with increasing density of board. The rate of weight loss, length and thickness reduction in non-steamed board were slightly higher than those of steamed board. When the resin impregnation rate increased, the bending strength and compressive strength of woodceramics had a tendency to increase. The bending strength and compressive strength of woodceramics in non-steamed board was higher than those of steamed board. But there was little difference between dimensional and strength properties of woodceramics and steam injection time of board.

• Korean Journal of Agricultural Science
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• v.31 no.2
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• pp.105-114
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• 2004

This study was performed to examine the physical and mechanical properties of eco-concrete using soil, natural coarse aggregate, soil compound and polypropylen fiber. The mass loss ratio was decreased with increasing the content of coarse aggregate and soil compound. The compressive strength, flexural strength, ultrasonic pulse velocity and dynamic modulus of elasticity were increased with increasing the content of coarse aggregate, soil compound and polypropylene fiber. The compressive and flexural strengths were showed in 8.07 MPa and 2.641 MPa at the curing age 28 days, respectively. The coefficient of permeability was decreased with increasing the content of coarse aggregate and soil compound, but it was increased with increasing the content of polypropylene fiber. The lowest coefficent of permeability was showed in $5.066{\times}10^{-9}cm/s$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1715-1719
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• 2004

In order to help the preservation of the unshiu orange and pear, antimicrobial paper incorporating grapefruit seed extract and zeolite was applied to pack fruits. Unshiu orange was packed in a box (24${\times}$24${\times}$22 cm) attached with antimicrobial paper and then stored respectively at l$0^{\circ}C$. Pears were wrapped individually before storage at l$0^{\circ}C$. During the storage, weight loss, pH, total acidity, soluble solid content, microbial load and decay were measured as quality indices. Steady pH increase in unshiu orange was observed to slightly decrease total acidity during the storage with little difference between the packaging treatments. The microbial loads of total aerobic bacteria, and yeast/mold counts were suppressed during storage by the antimicrobial paper packaging, which also contributed to reducing the decayed unshiu orange. Limited reduction of total aerobic bacteria and yeast/mold counts was observed only for initial storage period for the pears wrapped with 9 and 12% antimicrobial agent-added papers. Antimicrobial paper was useful for the reduction of microbial load in unshiu orange and pear without other quality deterioration.

• Journal of Korean Society of Forest Science
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• v.110 no.2
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• pp.244-253
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• 2021

This study aimed to investigate quality characteristics of hot-air dried persimmon during the drying period in 'Bansi' and 'Godongsi'. These cultivars were classified into four grades: 2L, L, M, and S based on the fruit weight. Weight loss, firmness, soluble solid content (SSC), and moisture contents were measured during the hot-air drying period. The weight loss significantly increased during the drying period (p<0.05), while there was no difference between cultivars. In the initial drying period, the firmness decreased due to softening during the ripening stage and increased significantly due to hardening during the water loss stage. Regardless of the cultivars, the SSC increased from 19.6% in the initial period to 55.3% at 12 days after drying. Moisture content statistically decreased in both cultivars over the whole drying period. It took 4 days and 8~10 days to produce semi-dried persimmon (45~55% moisture content) and dried persimmon (25~35% moisture content) in both cultivars. These results could be effectively used as basic data for producing high-quality semi-dried and dried persimmons using the hot-air drying method in 'Bansi' and 'Godongsi'.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.11a
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• pp.53-53
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• 2001

종이의 전기적 성질 가운데 유전율은 전기장에 대한 종이의 물리화학적인 반응으로 일반적으로 종이의 밀도와 종이를 구성하는 성분의 쌍극자 모멘트에 비례하며 온도에 따라서도 변화한다. 일반적으로 온도가 상승하면 열에너지를 얻게된 쌍극자가 전기장에 배열됨으로써 유전율이 상승하지만 온도가 유리전이점 이상으로 높아질 경우에는 열적 교란에 의해서 분극능력이 감소하게 되어 유전완화 현상이 나타난다. 전기절연지로 사 용될 종이의 절연특성을 이해하기 위해서는 사용환경에 따른 유전적 특성 및 tan 0에 관한 연구가 필요하며 필름형성능력이 우수한 polyvinyl a1cohoHPV A)와 acrylonitrile을 이용하여 시아노에틸화한 PYA의 표면처리에 의해 종이의 유전적 특성이 향상되었음을 기존의 연구를 통하여 확인할 수 있었다. 본 연구에서는 전기절연지가 사용되는 환경조건에서 PYA를 기본물질로하는 유전필름 의 열적 안정성을 평가하였으며, 아울러 표면사이징 공정에서의 적용성 검토를 위하여 용액의 유동특성을 분석하였다. 유전특성 향상을 위해서는 표면 사이즈제의 유도체화 과정에서 쌍극자 모벤트의 밀도 증가를 통한 유전율 향상이 요청되며 이와 동시에 네트원 구조를 통하여 전기장에 대 한 물리적 특성이 유지되어야 한다. 본 연구에서는 W AXD( wide angle x-ray diffraction)를 이용하여 시아노에틸화 반응 과 고온에서의 열화에 의한 필름의 결정화도를 평가하였으며 온도 상승에 따른 흡열 피크의 변화를 통하여 온도 변화에 따른 PYA 분자구조의 변화와 유리전이온도의 추이 를 분석하였다. 또 열화과정에서 수반되는 필름의 중량감소율을 평가함으로써 열안정성 을 평가하였다. 그 결과 시아노에틸화한 PYA가 안정된 분자구조를 유지하고 있음을 확인할 수 있었다. 시아노에틸화한 PYA용액의 점탄성 평가를 위하여 storage modulus와 loss modulus 를 분석하였다. 일반적 유변특성 평가 결과 PYA용액은 shear-thinning, pseudoplastic 한 특성을 나타내어 표면사이즈 공정에서의 적용 가능성을 확인할 수 있었다.

• Journal of Sericultural and Entomological Science
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• v.35 no.1
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• pp.7-10
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• 1993

Mulberry grafting season in normally a one month period starting at the end of March. Such a short period creates a shortage of qualified grafters and inflates wages. Pine tree sawdust was tested as a medium in which to preserve graftages. Sawdust was moistened to two ratios of water to dry weight of sawdust (1.5 and 2.0). Scions were either grafted the same day they were collected or first incubated for 10days at 15$^{\circ}C$. Grafting period could be extended to the middle of February under 1.5 times moisture content and fresh scions. Preservation of scions increased water content, T-N, P2O5, CaO and inositol, whereas decreased total C, glucose and fructose. With no preservation total C decreased, inositol increased slightly early March followed sharp decrease, and sucrose increased with time.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.428-434
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• 2022

This study intends to develop an eco-friendly concrete panel mixed with biochars. Experiments about mechanical and thermal properties were conducted on porous biochar concrete, which has insulation and carbon-capture performance. The concrete has a mixing ratio of 0, 5, 10, and 15 % for biochar and a water-binder ratio of 0.35. The unit weight, porosity, and permeability were measured to evaluate the mechanical characteristics. From the results, as the biochar mixing rate increased, the porosity and the permeability increased, but the unit weight decreased. Even though a decreased trend was observed in the compressive strength results, they satisfied the design standard. Since the thermal conductivity was decreased during the increase of contents, biochar could be considered an excellent material for insulation performance. In addition, regression analyses were conducted regarding the relationship of unit weight with porosity, compressive strength with thermal conductivity, and porous with thermal conductivity. From the regression, significant variables for expanding the scope of the application of biochar were presented.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1066-1072
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• 1999

The physical properties of polymer concrete were investigated for development of high-performance construction materials. Various specimens of polymer concrete were prepared using unsaturated polyester resin as the polymer-binder with the various dosage of calcium carbonate as microfiller (5~20 wt %) and fine aggregate(10~50 wt %). For the evaluation of the physical properties of polymer concretes, tests such as compressive strength, flexural strength, water absorption test, hot water immersion test, acid resistance test and pore size distribution analysis were conducted. As a result, it is concluded that compressive and flexural strengths of polymer concretes increased up to 4 times than those of conventional cement concrete. Whereas the compressive and flexural strengths of polymer concretes tested after hot water immersion, compared with those of polymer concretes tested before hot water immersion, decreased about 67%, 47%, respectively. By hot water immersion, total pore volume and porosity(%) of polymer concretes were remarkable increased due to decomposition of polymer binder. And also, it is showed that water absorption(%) and weight loss(%) of polymer concrete specimens by acid immersion, compared with those of ordinary portland cement concrete, decreased about 1/100, 1/27, respectively.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.584-589
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• 2000

In order to inhibit rot of soybean sprouts, presoaking treatments of soybeans with various solutions were studied. Optimal soaking time was 20min and citric acid, chitosan, GFSE(Grapefruit seed extract) were more effective. Most of presoaking treatments decreased the rot ratio of soybeans considerably, and didn't decrease germination ratio of them compared to control. Particularly GFSE, chitosan and phosphate buffer were effective. Presoaking treatments besides ethanol showed increased weight and yield of soybean sprouts compared to control, and particularly chitosan treatment increased yield of 67%, weight of 6.9% and length of 9.5% of soybean sprouts compared to control. Presoaking treatments decreased total microbial count of soybeans and rot of soybean sprouts during cultivation.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.56-56
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• 2022

벌개미취(Aster koraiensis Nakai)는 국화과에 속하는 우리나라 자생종으로 어린잎은 식용하고, 항비만 및 고지혈증 예방 등의 연구 결과가 보고되어 이용 가치가 높다고 알려져 있다. 또한 주로 조경소재로 이용되고 있으며, 생태복원을 위한 소재식물로 벌개미취를 이용하려는 시도가 이루어지고 있다. DMZ 남방한계선 철책 주변에는 군의 경계작전을 위해 반복적으로 식생을 제거한 지역(불모지)이 형성되어 있어 이를 복원할 필요가 있다. 생태복원에 있어 가장 기본적인 종 선정 방법은 자생종 또는 인접 지역종을 이용하는 것이다. 벌개미취는 DMZ 일원에 자생할 뿐만 아니라, 건조한 환경은 물론 습윤한 지역에서도 생육한다. 본 연구에서는 토성에 따른 벌개미취의 발아 특성과 광조건에 따른 광합성 반응을 조사하여 DMZ 불모지와 유사한 환경에서의 생육이 건전한지 살펴보고자 하였다. 이를 위해 벌개미취의 기내발아 검정(15℃, 12/12h)과 토성(마사토, 상토, 혼합토)에 따른 종자 발아율을 비교하였고, 차광(0, 50, 75 및 95%)처리에 따른 엽면적당 건중량, 엽록소 함량, 광-광합성 반응을 조사하였다. 벌개미취의 발아율은 기내(79%), 마사토(74%), 상토(82%) 그리고 혼합토(77%)로 나타나 각 처리구간 유의한 차이가 나타나지 않았다. 벌개미취의 엽면적당 건중량은 차광수준이 높을수록 감소하였고, 엽록소 a와 b 함량은 차광수준이 높을수록 감소하였으나 a/b는 통계적으로 차이가 없었다. 광-광합성 반응을 통해 산출한 벌개미취의 광포화점과 광합성 최대속도는 차광수준이 높을수록 감소하는 경향이 나타났고, 순양자수율은 증가하는 경향이 나타났다. 벌개미취는 전천광보다 낮은 광도에서 생장 시 광합성 능력이 감소하는 것으로 보이며, 광이 제한되지 않는 불모지 환경에서 생육이 유리할 것으로 생각한다.