• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.355-360
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• 2013

Diesel-burning air heater (air heater) and infrared heating lamp (infrared heater) were installed as auxiliary heaters in two single water-curtained plastic greenhouses with a set night temperature of $6^{\circ}C$ for cultivation of strawberry 'Seolhyang'. The average night air temperature was $6.6^{\circ}C$ in the infrared heater treatment and $7.1^{\circ}C$ in the air heater treatment. However, when the minimum outside temperature fell below $-10^{\circ}C$, the air heater had less internal temperature fluctuations. In contrast, the infrared heater had some cases of falling below the set temperature. The relative humidity was higher than 98% by the side-effect of water-curtain system regardless of the heating system. There was about $5^{\circ}C$ difference in leaf temperature between the turned-on and -off state of the infrared heater, and the efficacy of the infrared heater on leaf temperature was only limited to about 4 meters from the system. Peduncle length and plant height in the infrared heater tended to be greater than those in the air heater. There was, however, no statistically difference in leaf size and numbers of leaves, flowers on first cluster and branches. There was no difference in soluble solids content, fruit firmness, average fruit weight of the harvested fruits, and the yield. Comparing the heating costs, the air heater system took 622,662 won based on 543 L tax-free diesel, while the infrared heater system took 235,284 won by consuming 5,685 kWh of electricity, and 62.2% heating costs saving was achieved.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.396-407
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• 2020

As fossil fuels are depleted worldwide, alternative resources is required to replace fossil fuels, and biofuels are in the spotlight as alternative resources. Biofuels are produced from biomass, which is a renewable resource to produce biofuels or bio-chemicals. Especially, in order to substitute fossil fuels, the research focusing the biofuel (biodiesel) production based on CO₂ and biomass achieves more attention recently. To produce biomass-based biodiesel, the development of a supply chain network is required considering the amounts of feedstocks (ex, CO₂ and water) required producing biodiesel, potential locations and capacities of bio-refineries, and transportations of biodiesel produced at biorefineries to demand cities. Although many studies of the biomass-based biodiesel supply chain network are performed, there are few types of research handled the uncertainty in CO₂ supply which influences the optimal strategies of microalgae-based biodiesel production. Because CO₂, which is used in the production of microalgae-based biodiesel as one of important resources, is captured from the off-gases emitted in power plants, the uncertainty in CO₂ supply from power plants has big impacts on the optimal configuration of the biodiesel supply chain network. Therefore, in this study, to handle those issues, we develop the two-stage stochastic model to determine the optimal strategies of the biodiesel supply chain network considering the uncertainty in CO₂ supply. The goal of the proposed model is to minimize the expected total cost of the biodiesel supply chain network considering the uncertain CO₂ supply as well as satisfy diesel demands at each city. This model conducted a case study satisfying 10% diesel demand in the Republic of Korea. The overall cost of the stochastic model (US$ 12.9/gallon·y) is slightly higher (23%) than that of the deterministic model (US$ 10.5/gallon·y). Fluctuations in CO₂ supply (stochastic model) had a significant impact on the optimal strategies of the biodiesel supply network.

• Journal of agriculture & life science
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• v.46 no.2
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• pp.179-190
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• 2012

This study was performed to obtain a heat saving effect and enhance the efficiency of a greenhouse by using a hot water piping in order to minimize the operating costs of a greenhouse as oil prices continue to rise. This method also reduces the likelihood of accidents caused by snowdrifts in regions with heavy snowfall. In general, the experimental plot was $2.0{\sim}6.0^{\circ}C$ higher than the control plot. When the skylight felt was opened, the minimum temperature was in the range of $3.0{\sim}12.0^{\circ}C$. Therefore, we judged that damage caused by snowdrifts may be prevented partly by active heating. The temperature difference inside of the greenhouse by height was insignificant. The maximum heating load of the greenhouse according to crop was respectively about $37,000kcal{\cdot}h^{-1}$ and $41,700kcal{\cdot}h^{-1}$. During the experiment, the heat value of each designed temperature in the range of the minimum ambient temperature $-11.9{\sim}4.0^{\circ}C$ was about 95,000~322,000 kcal and it was in the range of $6,050{\sim}20,900kcal{\cdot}h^{-1}$. If it is compared with the maximum heating load, it can be shown that about 15~56% of the heating energy can be supplied. The total heat value and the amount of power consumption were 2,629,025 kcal and 677.3 kWh respectively during the experiment. If it is heated with diesel, a fossil fuel, the consumption during the experiment was 291 L and the cost was 331,700won. Total cost of using electric power was about 24,400 won and it is shown that it is about 7.5% of the cost of diesel consumption. Also, if the total amount of power consumption is converted into energy, it is approximately 582,200 kcal and the energy was just about 22% of the total heat value.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.249.2-249.2
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• 2010

최근의 고유가와 환경오염에 대한 대응 수단으로 수송용 바이오연료의 보급에 대한 관심이 세계적으로 높아지고 있다. 이 중 바이오디젤은 동식물성 기름으로부터 메탄올과의 전이에스테르화 반응에 의해 생산되는 경유대체 연료로서 환경 친화성과 지속가능성이 인정됨에 따라 그 생산량이 급격히 증가하고 있다. 바이오디젤의 생산량이 증가함에 따라 대두유, 유채유, 팜유 등의 원료유 가격 상승 및 수급 불안정 문제가 대두되고 있으며 식량자원과의 충돌 문제도 발생되고 있다. 이를 해결하기 위한 방안으로 유리지방산 함량이 높은 저가유지 자원(폐식용유, 폐돈지, 폐우지, soapstock, trapped grease)을 이용한 공정 개발 연구가 활발히 진행되고 있다. 본 연구에서는 비활용되고 있는 해외 열대작물 열매씨앗에서 착유한 식물성 오일의 바이오디젤 원료유로서의 사용 가능성을 검토하였다. 열대작물 오일의 물성 분석 결과 고형물, 수분, 인, 유리지방산 함량이 대두원유보다 매우 높게 나타났다. 오일 중의 인지질은 바이오디젤 제조 반응후 에스테르와 글리세린의 층분리를 방해하여 공정 효율을 감소시키고 유리지방산은 염기촉매와 결합하여 지방산염을 생성해 생산수율을 감소시키는 문제를 일으킨다. 고형물과 수분은 여과와 감압증발에 의해 쉽게 제거가 가능하였다. 15~20%의 유리지방산 함유 열대작물 오일의 전처리를 위해 균질계 산촉매와 비균질 고체 산촉매를 이용해 에스테르화 반응 효율을 조사한 결과 황산이 가장 높은 효율을 보였다. 반응표면분석법(Response Surface Method, RSM)을 적용해 메탄올과 촉매량의 2변수 에스테르화반응 최적화를 수행한 결과 메탄올 26%, 촉매 0.98%로 최적 조건이 도출되었으며 초기 산가 33mgKOH/g에서 0.98mgKOH/g으로 감소됨을 확인하였다. 전처리 정제한 오일의 물성분석 결과 고형물 0.1%, 수분 0.10%, 산가 1.0mgKOH/g, 인함량 20ppm 이하로 바람직한 원료유가 생산됨을 알 수 있었다. 제조된 원료유를 이용해 전이에스테르화 반응 최적화 실험을 RSM에 근거하여 진행한 결과 KOH 0.8%, 메탄올:오일 몰비 6.2:1, 반응온도 $60^{\circ}C$, 교반속도 200rpm, 반응시간 30분으로 나타났으며 증류 정제전 97.3%, 증류후 100.0%의 바이오디젤을 생산 할 수 있었다. 열대작물 오일의 전처리 공정은 메탄올을 과잉양으로 사용함으로 효과적인 알콜 회수 공정이 중요하다. 전처리 후 층분리를 통해 회수되는 메탄올 중의 수분함량은 2%~7%로서 이를 전처리 반응에 재사용하기 위해서는 0.3%이하의 수분함량으로 정제가 필요하다. 본 연구에서는 고가의 증류탑 형태가 아닌 단증류방식으로 2단계 내지 3단계로 0.3% 수분의 메탄올 회수 조건을 도출하였으며 파일롯 공정 설계를 진행하고 있다. 이로서 본 연구의 열대작물 오일은 저가로 충분한 물량의 확보가 가능하다면 바이오디젤 원료 자원으로서 큰 활용가치가 있는 것으로 판단된다.

• Journal of the Korean Wood Science and Technology
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• v.40 no.3
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• pp.177-185
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• 2012

The interest to develop adhesives from renewable resources is growing to substitute petroleum-based adhesive resins in the manufacture of wood based panels. In our study, rapeseed flour (RSF), which is the by-product of bio-diesel produced from rapeseed, were hydrolyzed with acid and alkali. As a crosslinking agents of the RSF hydrolyzates, phenol-formaldehyde prepolymers (PF) were prepared. The RSF hydrolyzates and PF were mixed to complete the formulation of RSF-based adhesive resins, and the resins were applied to make the medium density fiberboard (MDF). The physical and mechanical properties of the MDF were measured to examine whether RSF can be used as raw materials of adhesive resins for the manufacture of MDF or not. The average moisture content and density of the MDF made with RSF-based adhesive resins satisfied the minimum requirement of KS standard, but the thickness swelling was not. The bending strengths of the MDF made with RSF-based adhesive resins were lower than that of the MDF made with commercial UF resins, but the internal bonding strengths of tested MDF in some make-up conditions of RSF-based adhesive resins were higher than that of MDF made with commercial UF resins. These results showed the potential of RSF as a raw material of adhesives for the production of MDF. Future works on the optimal manufacturing process conditions of MDF made with RSF-based adhesive resins are required to improve the performance of MDF made with RSF-based resins.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.533-537
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• 2015

Micro-algae Chlorella vulgaris (C. vulgaris) is an important source for bio-diesel because of the high content of neutral lipids. In this study, we intended to induce mutants of C. vulgaris by UV-B irradiation. C. vulgaris was first exposed to UV-B for 1, 2, 3, 4, 5 min. As the UV-B exposure time increased, the cell viability and pigment content were decreased. Mutants of C. vulgaris were also induced through ultraviolet irradiation and two strains were selected with respect to lipid contents, where were named as 'UM10', 'UM15'. They were then cultivated in the same way as to the wild type. After 21 days of cultivation, the cell growth, dry cell weight, pigment contents, and lipid contents were measured for investigating characteristics of mutants. As a result, the cell growth and dry cell weight of both mutants increased about 1.4 and 1.5 times, respectively compared with those of wild type. In addition, chlorophyll and carotenoid contents were measured in order to investigate pigment contents in micro-algae through photosynthesis. It was shown that chlorophyll and carotenoid contents of both mutants decreased about 10% compared to those of wild type. Lipid contents in UM10 and UM15 increased about 1.2 and 1.5 times, respectively compared to that of wild type.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.1
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• pp.110-118
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• 2010

Supercritical treatment of liquefaction technology for rice hull was investigated the biomass conversion rate and evaluated its crude oil in respect to feasibility of burner in order to heat the green house. The reaction was carried out in a 5,000 mL liquefaction system with dispenser and external electrical furnace. Raw materials (160 g) of rice hull and 3,000 mL of different solvents were fed into the reactor. It was observed that the maximum crude oil yield was about 84.4 % with 1-butanol. The calorific value of crude oil from ethanol solvent were 7,752 kcal/kg. Furthermore, in case study of co-solvent with ethanol and bulk-glycerol, it observed that more than 80 % of rice hull was decomposed and liquefied in its solvent at $315{\sim}326^{\circ}C$ for 30 min. For the development of applicable bio-fuel from rice hull, it was considered that its feasibility is necessary to be carried out for co-solvent soluble portions. Regarding to utilize the crude oil into burner as fuel, it was observed that its calorific value was lower at approximately 24 % than the diesel. Also, flame length from crude oil at lower temperature was decreasing due to incomplete incineration. The temperature of warm wind on the burner was maintained between 63 and $65^{\circ}C$, and the temperature of emission line was appeared at $350{\sim}380^{\circ}C$.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.39-48
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• 2009

Biodiesel is estimated to be the best recycling energy source as an alternative fuel for transportation vehicles which represents the biggest share of greenhouse effect gas exhausts. Thus, in order to widely expand use of biodiesel and to enhancement its reliability, studies on quality improvement of biodiesel is needed. In this study, we have produced biodiesel(BD100, BD20) through esterification reaction using raw material of waste frying oil and analyzed compatibility with 24 items of quality criteria. As waste frying oil has high contents of unsaturated fatty acid such as Oleic acid, Linoleic acid and Linolenic acid, it is confirmed that there is no problem in using the same as a raw material of biodiesel. The result of analyzing the quality criteria items of biodiesel showed that it satisfied all the quality criteria except the oxidation stability of BD100, which was 2 hours, fatty acid methyl ester of BD20, which was 18.6w% and the filter plugging point, which was $-5^{\circ}C$. We believe that it will contribute to improved utilization of waste resources as alternative energy if studies on technology to improve quality of some items are provided.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.310-314
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• 2016

The search for natural antioxidants as alternatives to synthetic products is growing. Microalgae have emerged as a source of natural antioxidants with significant and diverse health-promoting properties. In this study, the effects of hot-water extraction conditions on total polyphenol compounds (TPC) production were investigated for lipid extracted microalgae (LEA). In order to enhance the polyphenol productivity, the extraction variables including solvents, temperature, time and ethanol concentration were optimized. The results showed hot-water extraction provided a higher extraction efficiency than the organic solvents and extraction at high temperatures showed a better extraction efficiency. While hot-water extract showed a higher extraction efficiency compared to 98% ethanol extraction, the mixture of water and ethanol (40:60 v/v) showed the highest production of polyphenols. The maximum polyphenols of 3.35 mg GAE (gallic acid equivalent)/g DM were obtained at the optimized extraction time of 10 min, $100^{\circ}C$ and 40% ethanol, respectively. Although Tetraselmis KCTC 12236BP was preprocessed by hexane to remove lipid for bio-diesel production, the results showed LEA contains relatively high level of polyphenols compared to untreated microalgae which can be used in the production of value-added materials. The predictions obtained from the developed Peleg's model were compared with the experimental data under the same operating conditions. The predicted and experimental data were consistent, indicating the reliability of the model.

• Korean Journal of Medicinal Crop Science
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• v.16 no.5
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• pp.301-305
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• 2008

Forty Ricinus communis collections were obtained from RDA National Agrobiodiversity Center for knowing the possibility of the use as a bio-diesel possibility crop. These are analysis results about crude fat and fatty acid. Gas chromatogram of seed collections analysis showed 6 peaks and retention time of ricinoleic acid was about 17.1 minute. Average oil content of collections were ranged from 44.6 to 49.4% and the difference was between maximum 52.5% and minimum 41.4%. Fatty acid composition was almost unsaturated fatty acid of 97.6% and saturated fatty acid showed low content of 2.4%. Ricinoleic acid was 87.3% and the content of oleic acid and linoleic acid in fatty acid was 4.6%, and 5.2%, respectively. The content of palmitic acid and stearic acid was about 1% and the difference was insignificant. The content of linolenic acid was extremely low as 0.6%.