• Journal of Biosystems Engineering
• /
• v.23 no.5
• /
• pp.457-464
• /
• 1998

A drying speed control system using fuzzy logic was developed in order to minimize the damage of rice quality for a large capacity continuous dryer. The performance of the system was tested at two object moisture content of 17% and 25% on a wet basis. For object moisture content of 17% on a wet basis, the final output moisture contents from 20.46%, 20.96%, 18.98% on a wet basis were 17.99%, 17.6% and 17.23% on a wet basis, respectively. For object moisture content of 25% on a wet basis, the final output moisture contents from 28.85%, 26.95%, 28.11%, 27.8% on a wet basis were 25.24%, 24.9%, 25.23% and 25.09% on a wet basis, respectively.

• Applied Chemistry for Engineering
• /
• v.28 no.3
• /
• pp.313-317
• /
• 2017

With the continuous increase of energy demand, low-grade coal is regarded as one of new energy sources. However, due to the high water content, the utilization efficiency of low-grade coal is not good to be used in recent conversion plants. Therefore, it requires a drying process to lower the water content in low-grade coals. Although a variety of drying experiments were conducted, drying characteristics in accordance with the pressure change has not been progressed. In this study, the flash drying characteristics of low grade coal with high moisture content (21.5 wt%) were determined in a pressurized micro-riser. The effect of operation conditions such as pressure (1-40 bar), dryer temperature ($200-600^{\circ}C$), and tube length (2-6 m) on drying ratios were investigated.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.388-395
• /
• 2000

This study was performed to examine the effects of infrared (IR)/heated-air combination drying on some quality attributes of Korean white ginsengs. Ginseng roots were dried in a dryer where both the far infrared ray and heated-air are available as drying energy sources. Diametral shrinkage, external color, total saponin content, and ginsenosides and free sugar composition of the IR/heated-air combination dried ginsengs were measured and compared with those of commercial white ginseng products. The external color became lower in lightness and higher in saturation as the IR radiating plate temperature increased. IR/heated-air combination dried white ginsengs at IR plate temperature of 100$^{\circ}C$ was comparable to the commercial white ginseng products in color characteristics. Diametral shrinkage ratios ranged from 20 to 36% and appeared to be independent on the different drying methods. No definite evidence could be found whether the IR/heated-air combination drying and the conventional. hot-air drying practice resulted in white ginsengs having different ginsenoside contents and compositions. No conclusion could be made on whether the various drying treatments used in the study had effects on the free sugar contents and compositions of white ginsengs.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1999.07a
• /
• pp.199-204
• /
• 1999

고려인삼(Panax Ginseng C. A. Meyer)은 오갈피나무과(Araliaceae) 인삼속(Panax)에 속하며 4-6년 동안 그늘진 곳에서 재배되는 다년생 초본식물이다. 인삼은 현재 우리나라뿐만 아니라 중국, 일본, 미국, 캐나다, 소련 등지에서 재배되고 있으나 우리나라 인삼은 "고려인삼"이라는 별칭으로 유통되고 있다. 이것은 고려인삼이 다른 인삼보다 월등히 품질이 우수하기 때문으로 판단하고 있다(고 등,1994). 인삼제품중 원형을 유지하는 건조제품으로는 홍삼, 백삼, 태극삼 등이 있으며 그동안 홍삼류는 국가 전매사업 대상으로서 한국담배인삼공사에서 조제, 가공 판매를 하였으나 1998년부터는 일반인도 취급이 가능하게 되었다. 홍삼은 원료수삼을 약 9$0^{\circ}C$ 이상의 증기로 증삼하기 때문에 이 과정에서 매우 유용한 약용 물질이 생성되는 것으로 알려져 있어 백삼보다 가공비는 높으나 가격이 매우 높기 때문에 일반 인삼가공업자들이 홍삼제조를 선호하고 있다 또한 동남아나 중국 등지에서 고려 홍삼을 선호하기 때문에 더욱 그러한 경향이 나타나고 있다. (중략)고 있다. (중략)

• Current Research on Agriculture and Life Sciences
• /
• v.14
• /
• pp.37-47
• /
• 1996

The main objectives of this studies are to present the most desirable rice processing complex model system in a given our situations by comparision and analyzing the major factors and, also recommend the future prospect of the rice processing complex in Korea. There are 3 different rice processing complex models in Korea. Those are concrete bin, flat type steel bin and square bin. These systems have a lot of differences and have their own characteristics such as capital requirement, efficiency, storage capacity and quality controls. The major problems of the existing rice processing centers in Korea are high fixed cost and the unbalnced systems. Following is summary to solve this problems: 1. Development of the large scale harvester and high speed continuous dryer. 2. Quality inspective system of bulk grain and large scale temporary storage facilities. 3. Large size readjustment of arable land. 4. Select the convenient location of rice processing center and formulation of well equipment facilities.

• Korean Chemical Engineering Research
• /
• v.53 no.5
• /
• pp.557-564
• /
• 2015

The previous etching, rinsing and drying processes of wafers for MEMS (microelectromechanical system) using SC-$CO_2$ (supercritical-$CO_2$) consists of two steps. Firstly, MEMS-wafers are etched by organic solvent in a separate etching equipment from the high pressure dryer and then moved to the high pressure dryer to rinse and dry them using SC-$CO_2$. We found that the previous two step process could be applied to etch and dry wafers for MEMS but could not confirm the reproducibility through several experiments. We thought the cause of that was the stiction of structures occurring due to vaporization of the etching solvent during moving MEMS wafer to high pressure dryer after etching it outside. In order to improve the structure stiction problem, we designed a continuous process for etching, rinsing and drying MEMS-wafers using SC-$CO_2$ without moving them. And we also wanted to know relations of states of carbon dioxide (gas, liquid, supercritical fluid) to the structure stiction problem. In the case of using gas carbon dioxide (3 MPa, $25^{\circ}C$) as an etching solvent, we could obtain well-treated MEMS-wafers without stiction and confirm the reproducibility of experimental results. The quantity of rinsing solvent used could be also reduced compared with the previous technology. In the case of using liquid carbon dioxide (3 MPa, $5^{\circ}C$, we could not obtain well-treated MEMS-wafers without stiction due to the phase separation of between liquid carbon dioxide and etching co-solvent(acetone). In the case of using SC-$CO_2$ (7.5 Mpa, $40^{\circ}C$), we had as good results as those of the case using gas-$CO_2$. Besides the processing time was shortened compared with that of the case of using gas-$CO_2$.

• Resources Recycling
• /
• v.24 no.6
• /
• pp.54-60
• /
• 2015

The objective of this study is to develop a belt-type dryer with a capacity of 1 ton/day, thereby improving drying efficiency by more than 70% and reducing the size of dryers by more than 50%, and thus making dryers smaller and lighter to reduce the installation and operation costs by more than 20%. We identified structural improvements by analyzing existing dryers employing indirect heating and verified the superior drying performance of the proposed method through some basic experiments. Furthermore, we verified the improvements in the heat transfer and drying characteristics as we conducted the experiments at reduced pressure.

• Journal of Biosystems Engineering
• /
• v.29 no.4
• /
• pp.307-316
• /
• 2004

This study was conducted to develop a coating system for producing clean enriched rice. The nutritional components of such as brown rice, white rice, clean white rice, enriched rice of US, black rice of China, and rice with perfume of China, were analyzed and compared. Total protein lipid md minerals in brown rice were higher than those in the other rices. A nutrition premix with lysine, thiamine, niacine, calcium lactate, ferrous lactate, and rice starch was made for enriching white rice. A coating device consisted of a tumbler, two spraying nozzles, a rice mixer, etc was developed with the capacity of 1 ton/h. And far-infrared dryers of batch and continuous types were developed to dry hygienically the wet enriched rice. The percentages of lysine, thiamine, amino acid nitride, and Ca and Fe of the enriched rice samples produced in this study were, respectively, 4, 3, 3. 2, and 10 times higher than those of white rice, respectively.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.16 no.2
• /
• pp.47-56
• /
• 2008

The objective of this research is to evaluate the optimum recycling methods for the sewage sludge cakes at different microwave power-settings and for different periods of time. The dehydrated sewage sludge cakes used in this study was obtained from N wastewater treatment plan in the P City. The beginning drying processes were carried out in a microwave oven with 2,450 MHz frequency and power ranges of 1kW to 4 kW. The continuous conveyer drying system was also operated with 2,450 MHz frequency and power setting, ranging from of 1 kW to 6 kW. Initial moisture content of the sewage cake is 78~80%, and the moisture content decreased rapidly up to 0.2~2(wt%) within short periods due to breaking the cell walls. This study is also conducted to evaluate the characteristics of sewage sludge cakes with respect to important physical parameters effect on the thermal kinetics for evaporation water in the sludge which are operation times, moisture contents, drying rates, input amounts, flow rates and calorific values. It takes 60 minutes and 120 minutes to reach the critical moisture contents with power setting of 4 kW for 3kg/min and 6kg/min of the flow rates respectively. It takes 120 minutes and 110 minutes to reach the critical moisture contents with flow rates of 2.5 cm/min and sludge input of 6kg/min for the power settings of 4 kW and 6 kW respectively. The most effective value of the power for drying the sludge is 4 kW. Operation with 6kg/min and 4kW on 2cm of the sludge thickness can be effectively and inexpensively to reach the critical moisture contents, when you compare 2cm of the sludge thickness with 1cm and 3cm of the sludge thickness.

• Particle and aerosol research
• /
• v.18 no.3
• /
• pp.79-86
• /
• 2022

Many commercial air purifiers currently have deployed granular activated carbon (GAC) filters for removing volatile organic compounds in the indoor air. GACs are generally used to remove gaseous contaminants in the air through adsorption by the inner surfaces of pores. In addition, airborne particles can be also filtered by the surface adsorption of the GACs, which can improve the life-time of the particulate filters. In this study, the filtration efficiency of GACs to ultrafine particles through surface adsorption was investigated at different volume flow rates by deploying a continuous particle filtration system. The polydisperse sodium chloride (NaCl) particles were generated by a set of an atomizer and a diffusion dryer, and then mixed with particle-free air at different volume flow rates. The penetration of ultrafine particles and pressure drop for each experimental condition were measured to figure out the effect of the volume flow rate on the surface adsoprtion of the GACs to particles, ~ 2 mm. The particle filtration efficiency of the GACs decreased as the volume flow rate increased from 4 to 14 lpm. However, the 5 times thicker GAC filter layer decreased the penetration of ultraparticles than a preious study. The filtration efficiency of the single granule was also higher than the previous result in the literature with smaller granule filter materials.