• 한국태양에너지학회 논문집
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• 제34권6호
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• pp.49-56
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• 2014

Research about hybrid solar air-water heater that can make heated air and hot water was conducted as a part of improving efficiency of solar thermal energy. At this experiment, ability of making heating air and hot water was investigated and compared with traditional solar air heater and flat plate solar collector for hot water when air or liquid was heated respectively. Comparing hybrid solar air-water heater that used in this experiment to other solar air heater studied already, it has a lower efficiency at same mass flow rate. Air channel structure, fin's shape and arrangement in the air channel result in these difference then the ability of air heating need to be improved with changing these thing. In case of making hot water, performance was shown as similar with traditional system although the air channels were established beneath absorbing plate. But the heat loss coefficient was shown higher value by installing of air channel. Also the performance of hot water making was shown lower value at same liquid mass flow rate with traditional flat plate solar collector for hot water. So the necessity of performance improvement at lower mass flow rate of each heating medium can be confirmed.

• 수산해양기술연구
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• 제33권3호
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• pp.209-217
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• 1997

The objective of this paper is to improve a discomfort caused by the unequal airflow and vertical temperature difference by buoyancy of the supplied hot air in the conventional hot air heating system. In order to the model experiment we manufactured the hot air heater with two air outlet and a model room. We observed the temperature, velocity and airflow distribution and calculated values of PMV and PPD using mean value of central verticality section's air temperature and velocity. We could improve distribution of vertical temperature and velocity at the central section of the model room owing to correlation of hot air of two air outlet.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.145-147
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• 2009

The benefits of hydroforming technology are known as weight and cost savings through part consolidation and reduced post-forming processes such as welding and piercing. Hydroforming technology has some weaknesses in terms of process cycle times. But, as the hydraulic system and process designs are continuously developed, the cycle time is also reduced to acceptable and competitive levels. Hot air bulging is one of recently developed hydroforming techniques. Hot air bulging in order to further extend the forming degrees of Al lightweight material is investigated. A heated tube is placed in a heated die and sealed at the ends by sealing cylinders. The tube is subsequently expanded against the die cavity wall by internal pressure provided by air medium. The result of this study shows that axial feeding speed and air pressure have an effect on formability of Al air bulging at elevated temperature.

• 한국약용작물학회지
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• 제14권1호
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• pp.8-13
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• 2006

삼백초의 유효성분과 선도유지에 적합한 건조방법을 구명하고자 건조방법을 달리하여 건조시킨 후 건조방법별 유효성분 함량과 선도를 조사한 결과를 요약하면 다음과 같다. 1. 건조방법별 건조시간은 양건에 비해 열풍건조와 동결건조시 $88{\sim}93%$ 단축되었다. 건물수율은 동결건조 > 양건 > 열풍건조 순으로 높았고, 건조후 수분 함량은 양건 > 열풍건조 > 동결건조 순으로 높았다. 2. 총페놀성 화합물과 quercetin 관련물질 함량은 동결건조 > 열풍건조 > 양건 순으로 높았으며, 열풍건조후 볶음 또는 건조전 증자 처리를 함으로써 감소되었다. 항산화 활성은 동결건조에서 가장 높았고, 열풍건조와 양건 간에는 차이가 없었으며, 열풍건조후 볶음 또는 건조전 증자 처리를 함으로써 증가하여 총페놀성 화합물과 quercetin 관련물질 함량과는 다른 경향을 보였다. 3. 적색도 (a)는 동결건조 < 열풍건조 < 양건 순으로 낮았다. 4. 열풍건조시 부위별 총페놀성화합물과 quercetin 관련물질 함량은 꽃 > 잎 > 세절 > 줄기 순으로 높았으며, 항산화 활성도 유사한 결과를 나타내었다. 부위별 적색도는 잎 < 세절 < 꽃 < 줄기 순으로 낮았다. 5. 삼백초의 유효성분과 선도유지에 적합한 건조방법은 세절하여 동결건조하거나 잎과 꽃만을 열풍건조하는 것이 효과적이었다.

• 항공우주기술
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• 제7권1호
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• pp.40-48
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• 2008

공기 혼합시스템은 초음속 지상추진시험설비의 축열식 가열기로부터 공급되는 $1000^{\circ}C$, 3.5MPa의 공기와 고압공기 공급원으로부터 공급되는 상온, 동일 압력의 공기를 혼합시켜서 시험부로 공급하기 위한 설비로 32MPa로 압축되어 있는 고압공기 공급원을 3.5MPa로 감압하는 고압/저온 유동제어부, 축열식 가열기의 고온밸브에서부터 공기 혼합기로 고온의 공기를 공급하기 위한 고온 배관, 축열식 가열기로부터 공급되는 고온 유동과 고압공기 공급원으로부터 공급되는 상온 유동을 혼합하기 위한 공기 혼합기로 구성된다. 공기 혼합 시스템을 통하여 완전히 혼합된 공기의 유량은 25kg/s, 온도는 약 $400^{\circ}C$로 이를 통하여 초음속 지상추진시험설비의 구동 영역을 저 마하수, 저 고도 영역까지 확장할 수 있다.

• 한국식품조리과학회지
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• 제31권5호
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• pp.596-604
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• 2015

This study investigated changes in the chemical properties and antioxidant activity of dried shredded radish (Raphanus sativus L.). Shredded radishes with a thickness of either 3.5 mm or 7.0 mm were dried using hot air at $45^{\circ}C$ or were sun dried. The degree of browning for the 3.5 mm sun dried radish, the 7.0 mm sun dried radish, the 3.5 mm hot air dried radish and the 7.0 mm hot air dried radish was 0.12, 0.14, 0.04 and 0.04, respectively. The DPPH radical scavenging activity (EDA%) of the hot air dried radish had a higher value than the sun dried radish. In contrast, the ABTS values of the sun dried radishes were higher than the hot air dried radishes. The total polyphenol content of the 7.0 mm and 3.5 mm hot air dried radishes reached high values of 15.99 and 11.62 mg/g, respectively. The total polyphenol contents of the 7.0 mm and 3.5 mm sun dried radishes were 9.63 and 6.77 mg/g, respectively. In sensory evaluation of the stir-fry dried shredded radishes, the 7.0 mm hot air dried sample scored the highest in terms of smell, color, gloss and overall preference. In conclusion, hot air drying ($45^{\circ}C$) and a thickness of 7.0 mm were found to be the optimal conditions for dried shredded radish and stir-fried dried shredded radish products.

• Journal of Ginseng Research
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• 제33권4호
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• pp.361-366
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• 2009

과열증기 건조처리 후 열풍 건조한 인삼의 건조율이 열풍 건조만으로 건조한 인삼에 비하여 약 40%의 빠른 건조율을 나타내었다. 일반성분의 함량에 있어서 조지방, 조단백질, 조섬유 및 회분 함량의 경우 두처리구간 큰 차이가 없었다. 무기질 및 유리당 함량의 경우에 있어서도 두 처리구간 큰 차이를 나타내지 않았다. 조사포닌 함량의 경우 과열증기 처리 후 열풍건조한 인삼분말의 조사포닌 함량은 5.43% 그리고 열풍건조만 한 인삼분말의 조사포닌 함량은 5.4%로 두시료간 큰 차이가 없었다. 색깔의 경우 적색도를 나타내는 a값에서 과열증기 건조 후 열풍건조 처리한 인삼분말이 열풍건조한 인삼분말에 비하여 약간 높은 결과를 나타내었다. 인삼분말의 미생물 수의 경우 과열증기 건조 후 열풍 건조한 인삼분말이 열풍건조한 인삼분말에 비하여 일반세균 및 효모곰팡이가 약 2 log 정도 감소하였고 대장균군의 경우는 약 1 log 정도 감소한 결과를 나타내었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.222-225
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• 2008

Due to new requirements of the automotive industry, concerning lightweight and non-corroding construction, new production methods, The Hot Air Forming process of aluminum alloys are of special interest. The disadvantage of aluminum alloy is the poorer formability compared to steel. The Hot Air Forming process is one of the forming process receiving recent attention. In the current study, Fabrication of aluminum rear subframe has been attempted using seam and seamless aluminum tubes. On the base of hot workability of the extruded tube and PAM-STAMP simulation results, Optimum condition for fabricating aluminum rear sub(lame parts by Hot Air Forming could be determined.

• Journal of Advanced Marine Engineering and Technology
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• 제26권2호
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• pp.226-232
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• 2002

In tradition, there have been two kinds of drying methods, which are sun drying and artificial drying. The sun drying method which has been adopted traditionally has been replaced by the hot-air drying method which is one of the most general methods of artificial drying, with its simple drying system, low initial cost of drying plant, and easy operating method. But the hot-air drying method has some defects ; (1)much energy loss happens due to the discharge of hot air during the drying process, (2)control of drying rate is not easy on account of changing relative humidity of inlet air for uniform hot air temperature, (3)high temperature of floods in drying process brings about the production of low-grade drying products. Also, the hot-air drying method is inducing environmental and sanitary problems which are resulting from the emission of high temperature and high humidity air, including stick on the drying progress. Vacuum drying technique, whose drying time and 7uantity of exhausting energy is about 1/3 ~1/4 of hot air drying, is very excellent in the drying efficiency. As the results, it took about 20 hours for material to reach about 18% of the final moisture content in order to store products for a long time, from about 470% of the early moisture content at the beginning of drying, and maximum drying rate comes to about $0.35 kg/m^2hr$ at about 350% of the moisture content.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.183-188
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• 2009

RFID method is a non-contact automatic identification technology, which attaches microchips and antennas to an object in a tag form, to send and process information sent to the network using wireless frequency. Drying and curing process is extremely important which minimizes the resistivity of RFID antennas. This research is about the drying characteristic of conductivity ink, and analyzes and compares the hot-air drying process and infrared drying process. Also, the research was done for the improvement in drying performance by using combined process of hot-air and infrared mechanism. The experiment result shows that the hot-air or infrared drying system used alone cannot meet the required performance in drying printing method using conductivity ink. The combined drying system of hot-air and infrared ray showed resistance low enough in short drying and curing time, and this mechanism makes drying and curing process for mass and continuous production possible on-line.