• 한국전산유체공학회지
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• 제16권2호
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• pp.75-80
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• 2011

In this study, three-dimensional transient numerical simulations were carried out for a paint drying system of vehicle. The vehicle on assembly line passes through the drying system consisting of hot and cool air blow region. For the moving motion of the vehicle, moving of inlet boundary condition and MRF technique are used. The transient distribution of temperature and velocity in the drying system were predicted numerically. In order to validate the numerical results, transient distribution of the vehicle surface temperature was compared with experimental data, showing a good agreement. As a result of present study, optimal operating condition of the drying system are to be suggested.

• 한국수산과학회지
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• 제21권1호
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• pp.16-20
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• 1988

다시마의 건조와 수축특성을 알기위한 기초자료를 얻고자 건조중인 다시마의 건조 및 수축특성에 미치는 채취부위, 공기의 온도, 상대습도 및 풍속의 영향에 관하여 실험한 결과를 요약하면 다음과 같다. 1) 다시마의 열풍건조과정은 항률건조 기간이 없이 바로 감률건조기가 나타났으며 이것은 다시 감률건조 1단계 및 2단계로 구분되었다. 2) 두께가 얇은 선단부가 기부보다 수축이 더 많이 되었으며 공기의 온도 $50^{\circ}C$, 상대습도 $30\%$, 유속 0.4m/s의 일정한 건조 조건하에서 다시마의 선단부, 중간부 및 기부를 120분까지 건조하였을 경우 수축율은 각각 $57.5\%,\;54.0\%,\;42.7\%$이었다. 3) 상대습도가 낮은것은 높은것에 비해 건조속도 및 수축속도는 빨랐으나 함수률 $20\%$까지 건조하였을 경우 수축율은 오히려 상대습도가 높은것이 증가하였다.

• Journal of Ginseng Research
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• 제9권2호
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• pp.248-255
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• 1985

In order to investigate the optimal drying condition of white ginseng by using bulk air drier(130 x 62 x 65cm), drying curves, diffusion coefficient at various drying temperature, the energy of activation, variation of color intensity and chemical components during drying of white ginseng were studied. Fick's second low of diffusion for diffusion out of spheres was successfully applied to describe the drying of white ginseng. It was found that the diffusion coefficient of water was 2.2x107, 9.0x107 cm2/sec at drying temperature 4$0^{\circ}C$, 55$^{\circ}C$, respectively. An Arrhenius type temperature dependency of moisture diffusivity was found, the energy of activation being 18.8 Kcal/g mol. Color intensity of white ginseng dried at various drying temperature was increased with an increase in drying temperature. The contents of crude protein, reducing sugar and crude saponin during drying of white ginseng were gradually decreased as increasing of drying time. And with the sensory evaluation by multiple comparison difference analysis, the optimal drying temperature of white ginseng was between 45$^{\circ}C$ and 5$0^{\circ}C$.

• 한국식품저장유통학회지
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• 제18권4호
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• pp.488-496
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• 2011

본 연구는 증절간 고구마 제조를 위하여 냉풍건조 방법을 이용하여 건조조건별 증절간 건조 고구마의 건조특성, 물성 및 관능적 특성을 연구하였다. 건조시 수분함량은 $25^{\circ}C$ 48시간에서 4.98%로 가장 낮은 수치를 보였고, 색차에서 건조온도가 낮을수록, 건조시간이 짧을수록 L값이 높아졌으며 a, b, ${\Delta}E$값은 건조온도가 높을수록 건조시간이 길어짐에 따라 증가하는 경향을 보였다. 가용성 고형분은 건조 조건별로 19~70 $^{\circ}Brix$의 범위를 나타내었고, 환원당은 98.7~194.75 mg/g 범위를 나타내었으며, 불성측정에서 경도는 $25^{\circ}C$, 48시간에서 23.88 $kg_f/cm^2$로 가장 높은 수치를 나타내었으며, 탄성과 응집성은 91.15, 98.36%로 가장 높은 수치를 나타냈다. 관능평가에서 $10^{\circ}C$, 40시간, $25^{\circ}C$, 24시간에서 색, 향미, 맛, 조직감, 전반적인 기호도에서 가장 높은 평가치를 나타내었으며, 반응표면분석을 통한 증절간 고구마의 최적 건조조건을 예측한 결과 $19^{\circ}C$, 건조시간 32hr으로 예측되었다.

• 유기물자원화
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• 제17권4호
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• pp.103-111
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• 2009

본 연구에서는 퇴비화에서 첨가제로 주로 사용하고 있는 톱밥을 대상으로 수분 혼합방식으로서의 습윤과정과 건조과정에서의 수분함량별 톱밥의 물리적 성상의 변화로 인한 공기투과성의 차이점을 파악하고자 하였다. 수분증가에 따라 겉보기밀도는 증가하며, 공기공극은 감소하였다. 그러나 습윤 및 건조과정에서 동일한 수분함량일지라도 습윤과정의 공기공극이 건조과정에 비하여 높게 나타나고 있어 습윤과정이 퇴비화 매체 내에서의 공기이동에 유리한 물리적 성상을 보이고 있다. 또한 수분이 증가함에 따라 톱밥 입자크기가 커지며, 수분함량 40%부터 60% 구간에서 습윤과정이 건조과정에 비하여 큰 입자를 형성하였다. 또한, 습윤과정에서는 수분이 증가함에 따라 공기공극이 작아짐에도 불구하고 수분함량 60% 정도에서 차감압력이 가장 낮아지고 이후 수분 포화상태에 도달하면 급격히 증가하고 있다. 건조과정에서는 습윤과정과는 다르게 포화상태에서부터 수분이 감소함에 따라 차감압력이 지속적으로 감소하는 경향을 보이고 있다. 퇴비화에서 주로 활용되는 건조기준 수분함량 0.67(습량기준 40%) 이상의 수분함량 구간에서 유입 공기유량이 동일할 경우 습윤과정이 건조과정에 비하여 차감압력이 낮아 공기투과성이 개선되어 있음을 알 수 있다. 또한 동일한 수분함량에서의 차감압력은 유입 공기유량에 비례하여 증가하고 있는 것으로 나타났다. 이러한 실험결과로서, 퇴비화공정에서 매체내의 공기이동성을 원활하게 하기 위하여는 습윤과정이 적절하며 수분함량 60% 정도가 최적의 운영조건이라 판단된다.

• Preventive Nutrition and Food Science
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• 제15권3호
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• pp.244-247
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• 2010

This study was performed to evaluate the effect of drying methods on the polyphenol contents and antioxidant activities of Hizikia fusiformis. The seaweed was dried using four different conditions: vacuum drying (VD) at $20^{\circ}C$ and $30^{\circ}C$ and hot-air drying (HD) at $40^{\circ}C$ and $60^{\circ}C$. After drying, the total phenol content, DPPH and nitrite scavenging activities of the water extracts were determined. The total phenol contents were significantly (p<0.05) higher in the vacuum dried samples than the hot-air dried samples. DPPH radical was scavenged 82.67% and 83.45% by VD-20 and VD-30, and 70.44% and 71.23% by HD-40 and HD-60, respectively. At pH 1.2, Hizikia fusiformis scavenged 87.43%, 88.45%, 72.14% and 73.45% of nitrite by the treatment VD-20, VD-30, HD-40 and HD-60, respectively. Interestingly, the nitrite scavenging activity was much more reduced at pH 3.0 than at pH 1.2. Through these experiments, we were able to show that the drying conditions affect the total phenol contents and antioxidant capacities of Hizikia fusiformis.

• 한국농공학회지
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• 제16권4호
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• pp.3600-3610
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• 1974

Experimental work of batch-type dryer was conducted to develop its optimurm operating conditions by analyzing the major factors which affect the drying performance. A laboratory batch-type dryer was constructed and tested for various levels of heated-air rates, and depths of grain deposit. Tong-il rice variety having the initial moisture content of approximaely 23 per cent in wet basis was used for the experiment. The criteria selected for establishing the optimum operating condition were the drying performance rate, the thermal efficiency, and the operational cost of the dryer. The results of the study are summarized as follows: 1. The performance rate of dryer for a specific operating condition was defined as total amount of material dried per hour when the moisture content of grains in the upperlayer reaches to 16 per cent in wet basis. The optimum operating conditions as viewed in the rate of drying performance could be justified by functional realtionship between the depth of grain deposit and air flow rate. In other words, there was a definite depth of grain deposit for a given air-rate which make the dryer performance maximum. The optimum grain depth for the batch-type dryer with 3.3㎡ loading area and with the attached axial fan was about 35cm. 2. The thermal efficiency for the dryer was evaluated by the ratio of the latent heat required to evaporate the grain moisture to the heat input required to raise the ambient air-temperature to 40 degree centigrade. The optimum operating condition as viewed in term of thermal efficiency analyzed was that grater depth and lower air flow-rate may be desirable. This condition is contracted with the optimum condition as viewed by the dryer performance rate. 3. The annual operating cost of batch-type dryer was analyzed for different annual hour of use and for different operation condition. The optimum condition as viewed in terms of operating cost was almost identical to one as viewed in terms of dryer performance rate. Therefore, the most economical use of batch-type dryer for the same annual operating hours can be obtained when the dryer operated in the condition of maximum dryer performance rate. Increasing the annual operating hour may be desirable to cut down the dryer operation cost, since the annual hour of dryer use is much sensitive to the operating cost than any peractical conditions of dryer operation. 4. The most desirable operational condition as justified by combining all the criteria, dryer performance rate, thermal efficiency and annual operating cost, could be concluded to operate the dryer in the condition of maximum performance rate. The condition in general is identical to the lowest operation cost for a given annual operating hour.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.27-30
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• 2003

This study is investigated the various properties and drying shrinkage of concrete according to water content under the condition proper fluidity is adjusted, in order to suggest the method for reduction of crack by drying shrinkage. According to the results, though water content varies, slump and air content are satisfied to the planed values, but shear slump and separation happen at water content of 120 and 140kg/$m^3$ due to the overuse of superplasticizer(SP). As water content is diminished, setting time is retarded by an increase of the using amount of SP, and compressive and tensile strength increase in the range of 160-180kg/㎥ of water content, but decrease significantly at 120 and 140kg/$m^3$. Length change by drying shrinkage decrease with a decrease of water content. Therefore, considering not only drying shrinkage but also fluidity, setting time and strength, it proves that the most appropriate water content of concrete is 160kg/$m^3$ in the condition of this experiment.

• 한국식품과학회지
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• 제31권3호
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• pp.575-580
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• 1999

복령은 온도와 풍속, 온도와 방사거리를 변화시켜 열풍건조와 원적외선건조방법으로 건조함으로써 건조조건에 따른 색도, 갈변도, 총페놀함량, 전자공여능 등의 품질변화에 미치는 영향을 조사하였다. 색도는 열풍건조시료에서 건조온도와 풍속이 증가할수록, 원적외선건조시료에서 건조온도는 증가하고 방사거리가 짧아질수록 ${\Delta}L$, ${\Delta}a$, ${\Delta}E\;value$는 증가하였고, ${\Delta}b\;value$는 감소하였으며 그 변화폭도 커졌다. 그리고, 갈변된 정도를 알 수 있는 추출물의 흡광도는 색도 변화와 같은 양상을 보였다. 복령의 총페놀함량은 원적외선 시료가 열풍건조시료보다 낮은 함량을 나타냈지만 전체적으로 시판품의 함량보다는 높은 함량을 보였다. 전자공여능은 온도, 풍속과 방사거리에 따른 각 구간별 차이는 거의 없었다. 따라서 원적외선건조보다는 열풍건조로, $50^{\circ}C$의 낮은 건조온도와 0.5 m/s의 느린 풍속으로 건조할 때 품질에 영향을 주는 색도변화와 화학성분함량의 손실을 최소화할 수 있는 것으로 사료되며, 원적외선 열원을 고온, 장시간 사용할 경우 품질손실은 매우 크게 나타났다.

• 한국염색가공학회지
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• 제21권4호
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• pp.23-32
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• 2009

The objective of this study is to investigate the efficacy of leaf powder colorants as substitutes for traditional indigo dyeing. Leaf powder colorants were prepared by hot air($50^{\circ}C$) and room temperanrre($25^{\circ}C$) drying methods from fresh leaves. The presence of indigo in the leaf powder colorants was confirmed by UV/Visible absorption spectra. All the powder colorants showed broad absorption at 602 nm as same as synthetic indigo. Dyeing was done by reduction method with sodium hydrosulfite and sodium hydroxide. Leaf powder colorants produced blue color on silk fabrics, showing similar color to the one dyed traditionally with fresh juice extract. The powder colorants prepared at room temperature drying were more stable for long term storage than that prepared by hot air drying. Thus, the powder colorants prepared by room temperature drying was reduced and dyed in one-step process without sodium hydroxide in the dyebath for further investigate dyeing properties. K/S value of the fabric dyed without sodium hydroxide was much higher than one dyed with sodium hydroxide. Regardless of the addition of sodium hydroxide, rubbing fastness was fairly good showing above 4 rating. Fastness to dry cleaning and light of the fabrics dyed without sodium hydroxide were mote higher than that dyed in alkaline condition.