• Journal of the Korean Wood Science and Technology
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• 제47권2호
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• pp.189-199
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• 2019

This study addresses the biorefinery feedstock from Pinus densiflora. This raw material is a major tree species in the Republic of Korea; it is renewable, has cost-effective, and is readily available. In this study, steam explosion of P. densiflora was performed in a reactor at $225^{\circ}C$ and with 1 to 13 min reaction times with or without previous water impregnation. The combined severity factor (Ro), which is an expression relating the reaction temperature and reaction time used in the steam explosion treatment, ranged from 3.68 to 4.79. The influence of both impregnation and steam explosion conditions were investigated by examining color variations, chemical composition, and mass balance on the pretreated solids. The results showed that steam-exploded P. densiflora that was not impregnated with water exhibited significantly darker color (chroma 28.8-41.4) than water-impregnated and steam-exploded P. densiflora (chroma 18.8-37.3). The increased ${\alpha}$-cellulose and lignin contents were detected as the severity factor increased. Furthermore, the ${\alpha}$-cellulose and lignin contents in the non-impregnated/steam-exploded P. densiflora were higher than those in the water-impregnated/steam-exploded P. densiflora. However, the decreased holocellulose content was detected as the severity factor increased. In mass balance, the holocellulose yield from water-impregnated/steam-exploded P. densiflora was higher than that from the non-impregnated P. densiflora.

• Journal of the Korean Wood Science and Technology
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• 제46권4호
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• pp.380-392
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• 2018

The importance of polysaccharides is increasing globally due to their role as a significant source of dietary prebiotics in the human diet. In the present study, in order to maximize the yield of crude polysaccharides from Pinus densiflora, response surface methodology (RSM) was used to optimize a two-stage extraction process consisting of steam explosion and water extraction. Three independent main variables, namely, the severity factor (Ro) for the steam explosion process, the water extraction temperature ($^{\circ}C$), and the ratio of water to raw material (v/w), were studied with respect to prebiotic sugar content. A Box-Behnken design was created on the basis of the results of these single-factor tests. The experimental data were fitted to a second-order polynomial equation for multiple regression analysis and examined using the appropriate statistical methods. The data showed that both the severity factor (Ro) and the ratio of water to material (v/w) had significant effects on the prebiotic sugar content. The optimal conditions for the two-stage process were as follows: a severity factor (Ro) of 3.86, a water extraction temperature of $89.66^{\circ}C$, and a ratio of water to material (v/w) of 39.20. Under these conditions, the prebiotic sugar content in the extract was 332.45 mg/g.

• Korean Chemical Engineering Research
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• 제55권1호
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• pp.40-47
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• 2017

가연성 분진이 제조 취급되는 공정에서의 분진폭발 위험성은 항상 존재한다. 그러나 산업현장에서 취급되는 분진에 대한 분진폭발 특성 정보는 아주 미흡한 실정으로 사업장에서는 화학사고 예방대책 수립에 어려움을 겪고 있다. 본 연구에서는 입도분포가 다른 두 종류의 다중벽 탄소나노튜브(MWCNT)에 대한 분진폭발 특성을 실험적으로 조사하였으며, NFPA 499 Code를 적용하여 MWCNT 제조 취급 공정의 분진폭발 위험장소 구분을 검토하였다. 그 결과 평균입도가 $124.2{\mu}m$인 MWCNT 1의 $P_{max}$, $K_{st}$, LEL, MIE, 및 MIT는 각각 6.3 bar, $56bar{\cdot}m/s$, $125g/m^3$, 1000 mJ 초과 및 $650^{\circ}C$ 초과로 나타났다. 평균입도가 $293.5{\mu}m$인 MWCNT 2의 $P_{max}$, $K_{st}$, LEL, MIE, MIT는 각각 6.2 bar, $42bar{\cdot}m/s$, $100g/m^3$, 1000 mJ 초과 및 $650^{\circ}C$ 초과로 나타났다. NFPA 499 Code에 따른 MWCNT 1, 2의 폭발강도와 점화감도는 각각 0.35와 0.01 미만으로 나타났기 때문에 MWCNT는 NFPA 499 Code에서 제시된 분진폭발 위험장소로 구분하여야 하는 가연성 분진으로 분류되지 않았다.

• 한국가스학회지
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• 제27권4호
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• pp.62-69
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• 2023

화력발전소용 석탄에 대한 연소기술의 발전과 원가절감을 위해 저급탄의 사용량이 지속적으로 증가하고 있다. 연소 시 수분에 의한 증발잠열 손실이 크고 탄을 저장하고 미분화하는 과정에서 자연발화와 분진의 폭발위험이 있다. 본 연구는 국내 D 발전사에서 채취한 석탄분진(coal powder)으로 Coal dust-fine, Coal dust-coarse, Wood pallet+organic dust 및 Wood chip 4종에 대한 최소폭발농도와 폭발강도를 비교 평가하였다. 석탄 분진의 최소폭발농도는 JIS Z 8818:2002에 따라 측정하였으며, 폭발강도는 Siwek 20 L Chamber Apparatus를 이용하여 ASTM E1226에 따라 실험을 실시하였다. 최소폭발농도 시험결과 coal dust-fine가 분진폭발 위험이 있는 것으로 나타났으며, wood chip의 분진농도 130 g/m³에서 폭발이 일어나므로 가장 낮은 분진농도에서 폭발의 위험이 있는 것을 알 수 있었다. 분진폭발 등급 기준에 따르면 Kst가 200 bar m/s 이하로 모든 시료가 폭발등급 St 1등급에 해당되며, 폭발의 위험성이 약한 분진으로 평가되었다.

• Journal of the Korean Wood Science and Technology
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• 제50권1호
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• pp.59-67
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• 2022

Dietary fiber is considered a feed ingredient with high nutritional value in the broiler feed industry. Pine chips contain a large amount of dietary fiber and require some modification for use as broiler feed. In this study, pine chips were subjected to steam explosion under different severity factor (Ro) conditions to improve the chemical and physical properties of dietary fiber. The highest water-holding capacity, oil-holding capacity, and swelling capacity were found for Ro 4.0, followed by Ro4.5 and 3.5. The optimal condition for the steam explosion was determined to be Ro 4.0 (reaction temperature of 210℃, and reaction time of 6.0 min). Under these conditions, the water-holding capacity, oil-holding capacity, and swelling capacity of steam-exploded pine chips were 8.3 g/g, 6.5 g/g, and 5.0 mL/g, respectively. This study may contribute to the application of lignocellulose and related products in the broiler feed industry.

• 한국가스학회지
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• 제15권4호
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• pp.7-14
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• 2011

20 L 구형 폭발시험장치와 시차주사열량계(DSC)를 사용하여 반응성 유기물 분진의 폭발 및 열분해 특성을 실험적으로 조사하였다. 그 결과 97 % Benzoyl peroxide(BPO), Phthalic anhydride(PA), 1-Hydroxybenzotri azol(HBT)의 폭발하한은 매우 낮은 농도인 10~15 g/$m^3$의 범위로 측정되어 착화위험성이 높은 것으로 나타났다. HBT, PA 및 97 % BPO의 폭발지수는 각각 251, 146, 80 [bar m/s]로서, HBT는 폭발등급 2에 해당한다. 또한 밀폐계 분진폭발의 화염전파 특성을 추정하기 위하여 용기면에의 화염도달시간과 폭발압력을 고려하여 화염전파속도를 예측하였다. 97 % BPO 및 HBT의 열분해 개시온도와 발열량은 각각 $107^{\circ}C$(1025 J/g), $214^{\circ}C$(1666 J/g)로 나타났는데, 이와같이 낮은 열분해 온도와 큰 발열량이 폭발특성에 영향을 주는 것으로 판단된다.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.111-122
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• 2013

The steam explosion-chemical pretreatment is a more effective wood pretreatment technique than the conventional physical pretreatment by accelerating reactions during the pretreatment process. In this paper, two-stage pretreatment processes of hardwood were investigated for its enzymatic hydrolysis and the succinic acid yield from the pretreated solid. The first stage pretreatment was performed under conditions of low severity to optimize the amount of solid recovery. In the second stage pretreatment washed solid material from the first stage pretreatment step was impregnated again with chemical (alkaline or chlorine-based chemicals) to remove a portion of the lignin, and to make the cellulose more accessible to enzymatic attack. The effects of pretreatment were assessed by enzymatic hydrolysis and fermentation, after the two stage pretreatments. Maximum succinic acid yield (16.1 g $L^{-1}$ and 77.5%) was obtained when the two stage pretreatments were performed at steam explosion -3% KOH.

• 한국안전학회지
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• 제14권4호
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• pp.120-125
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• 1999

This study evaluated the effect of the accidents caused by fire, explosion, and toxic gas release by using SuperChems, quantitative hazardous material release modeling software, which estimates the potential area of damage. According to the loss severity, the appropriate risk management principles can be applied. Risk management is divided into the two methods which are risk control and risk financing. Risk control includes risk avoidance, risk spreading and diversification, and risk reduction. Risk financing includes risk retention and risk transfer. The results of this study can help the related company determine the appropriate reserve fund and the amount to be insured against the third party losses according to the estimated loss severity.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.182-194
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• 2017

The optimum alkali pretreatment parameters (reaction time, reaction temperature and potassium hydroxide concentration) for facilitate the conversion into fermentable sugar (glucose) from steam exploded (severity log Ro 2.45) barley husk were determined using Response Surface Methodology (RSM) based on a factorial Central Composite Design (CCD). The prediction of the response was carried out by a second-order polynomial model and regression analysis revealed that more than 88% of the variation can be explained by the models. The optimum conditions for maximum cellulose content were determined to be 201 min reaction time, $124^{\circ}C$ reaction temperature and 0.9% potassium hydroxide concentration. This data shows that the actual value obtained was similar to the predicted value calculated from the model. The pretreated barley husk using acid hydrolysis resulted in a glucose conversion of 94.6%. This research of steam explosion and alkali pretreatment was a promising method to improve cellulose-rich residue for lignocellulosic biomass.

• 한국직업건강간호학회지
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• 제25권2호
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• pp.85-95
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• 2016

Purpose: The purpose of this study was to examine the burn characteristics of female patients hospitalized in a burn center. Methods: This is a retrospective descriptive study. The subjects were 222 female patients aged over 19 years old having burn injuries from work sites between January 1, 2012 and December 31, 2014. Data were collected using electronic medical records about the burn-related characteristics. The data were analyzed descriptively. Results: Many of the subjects were in their forties and fifties. Most subjects showed burns with an area of less than 10% of the body surface with a severity of second degree. Scalding burns were the most frequent. Contact burns were usually of third-degree severity and occurred on hands and wrists. Flame burns affected the largest body surface area and frequently occurred on the face and mainly caused by explosion of a stove or kitchen gas. Chemical burns frequently occurred on the lower limbs. Conclusion: Female workers are exposed to the hazards of burn injuries in industrial accidents. Types of burn differ depending on the workplace conditions. Therefore, preventative measures for burn injuries should be established in accordance with the characteristics of each industry to which female workers belong.