• 한국식품영양과학회지
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• 제42권9호
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• pp.1452-1460
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• 2013

마늘은 일반적으로 $0{\sim}-4^{\circ}C$의 저온에서 저장하는 방법이 널리 이용되고 있으며, 저온저장 후 상온보관 시 마늘은 휴면이 일직 타파되고 생육이 촉진되어 품질이 떨어지게 된다. 그리고 저장온도가 낮고 상온과의 온도 차이로 마늘의 표면에 결로가 생기며, 이 결로로 인해 발생된 수분이 마늘의 미생물 생장을 촉진시켜 부패율 증가에 큰 원인이 되고 있다. 그러나 이러한 문제점에도 불구하고 저온저장 후 상온유통 시 후처리에 대한 연구가 매우 미진한 상태이다. 따라서 본 연구에서는 마늘의 저온저장 후 건조처리 방법에 따라 상온 보관성 향상 및 품질에 미치는 영향을 분석하고, 적정저장 및 2차 건조조건을 확립 제시하였다. 연구 결과를 요약하면 다음과 같다. 마늘의 중량감소율은 2차 건조조건에 따라 $40^{\circ}C$ 2일 건조조건에서 2.5~4.1%로 가장 크게 나타났다. 그러나 2차 건조 후 상온보관에 따른 마늘의 중량감소율은 $40^{\circ}C$ 2일 건조조건에서 5% 낮은 것으로 나타났다. 2차 건조 후 상온보관 기간에 따른 마늘의 맹아율은 상온보관 15일까지 20% 급속히 증가하는 것으로 나타났으며, 30일 이후부터는 소폭 증가하는 것으로 나타났다. 2차 건조조건에 따른 마늘의 맹아율은 건조하지 않은 조건에서 그 증가폭이 10% 정도 큰 것으로 나타났으며, 2차 건조조건 중 $35^{\circ}C$ 3일과 $40^{\circ}C$ 2일 건조조건에서의 맹아 생장이 가장 작은 것으로 나타났다. 저온저장 후 2차 건조조건에 따른 마늘의 부패율 변화는 저온저장 후 2차 건조하지 않은 조건에서 부패율이 5~10% 높았으며, $40^{\circ}C$ 2일 건조조건에서의 부패율이 가장 낮은 것으로 나타났다. 저온저장 후 상온보관에 따른 마늘의 경도변화는 저온저장 후 2차 건조를 수행하지 않은 조건에서 그 변화 폭이 20~50 gf 크게 나타났고, 2차 건조 후 상온보관에 따른 마늘의 경도 감소는 $35^{\circ}C$ 2일과 $40^{\circ}C$ 2일 건조조건에서 작은 것으로 나타났다. 따라서 마늘의 저온저장 후 상온보관 시 적정조건은 저온저장 직후 2차 건조를 하며, 2차 건조조건 중 $40^{\circ}C$ 2일 동안 건조하는 것이 마늘의 고품질 유지를 위해 바람직한 것으로 판단된다.

• 대한화학회지
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• 제50권1호
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• pp.65-78
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• 2006

연구에서는 언 빨래가 마르는 현상을 승화라고 생각하는지, 그리고 이를 상평형 그림으로 표현할 수 있는지에 대한 중등학교 화학 교사들의 인식을 알아보았다. 53명의 교사들을 선정하여 이 연구에서 개발한 설문 및 면담을 실시하였다. 또한 사범대학 물리화학 전공 교수 2인과 분석화학 전공 교수 1인에게도 면담을 실시하여 교사 교육을 담당하는 교수의 승화에 대한 생각을 알아보았다. 연구 결과, 설문 응답한 53명의 교사 중 41명이 승화 현상이라고 답하였다. 승화라고 생각하는 교사들은 대부분 고체에서 기체로 상태변화가 일어나기 때문이라고 응답하였으며, 승화가 아니라고 생각한 교사들은 상평형 그림에서 외부압이 1기압일 때 승화가 일어날 수 없는 조건이라고 응답하였다. 17명의 교사는 언 빨래가 마르는 현상을 상평형 그림에 표현할 수 있다고 생각하였으며, 34명이 나타낼 수 없다고 응답하였다. 그러나 대부분 상평형 그림에 언 빨래가 마르는 현상을 과학적으로 설명하는 것에 대해 혼란스러워하였으며, 학생들을 가르치면서도 어려움을 겪는다고 응답하였다.

• 설비공학논문집
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• 제27권12호
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• pp.645-651
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• 2015

This paper presents an experimental study on the freeze drying process for poly ${\gamma}$ glutamic acid. The physical properties of poly ${\gamma}$ glutamic acid are measured during the freeze-drying process. The moisture contents of poly ${\gamma}$ glutamic acid according to the glass transient temperature are obtained by DSC (Differential Scanning Calorimetry) analysis. The end point of primary drying for the poly ${\gamma}$ glutamic acid with a thickness of 3 mm is obtained by measuring the thickness of the dried layer, the amount of moisture evaporation, the moisture content, and the pressure in the drying vacuum chamber during the freeze-drying process. By considering the variation in the glass transient temperature with respect to the moisture content of the material, a control schedule for the heating plate temperature is suggested during the secondary drying process.

• 한국세라믹학회지
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• 제33권9호
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• pp.1057-1063
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• 1996

Y2O3-CeO2-ZrO2 powders were prepared from water-soluble salts using a coprecipitation method. The forming process of oxide and the characteristics of the calcined powders treated in different drying conditions were investigated. The oxidation was occurred at the temperature of around 40$0^{\circ}C$ and the main crystallization of ZrO2 around $600^{\circ}C$. On calcination at $600^{\circ}C$ heating lamp-dried powders consisted of agglomerates of globular morphology with average agglomerate size of 2.27${\mu}{\textrm}{m}$ and specific surface area of 68.3m2/g and spray dried powders contained dense spheric particles with average agglomerate size of 1.35${\mu}{\textrm}{m}$ and specific surface area of 11.0m2/g which exhibited low agglomeration tendency. Removal of the water by a freeze-drying technique produced calcined powders containing flake-like secondary particle structures with wide agglomerate size distri-bution of 0.1-60${\mu}{\textrm}{m}$ and specific surface area of 24.5${\mu}{\textrm}{m}$. The 20 MPa-pressed density (36.8-41.4% T,D) of calcined powders did not nealy depend on drying methods whilst compaction ratio of calcined powders derived from freeze-drying was the highest ( 6.24) among three drying methods. On continuous heating up to 150$0^{\circ}C$ the sinterability of calcined powders derived from heating lamp-drying was superior to those derived from spray-and freeze-drying. The final sintered density of calcined powders was the highest (96% T,D at 150$0^{\circ}C$) in case of heating lamp-drying.

• 전기화학회지
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• 제8권1호
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• pp.42-46
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• 2005

It has been known that the synthesis of the cathode materials for the lithium rechargeable batteries by the sol-gel process has many advantages over the conventional solid-state method. It has been, however, a continuing issue that new additional steps should be introduced to commercialize this process. In this work, spray drying was introduced to the existing sol-gel process as a continuous mass production method of the pre-heat treatment precursor materials. The precursors of $LiCoO_2$ and $LiNi_{0.8}Co_{0.2}O_2$ were continuously produced through spray drying from the solution containing stoichiometric amount of lithium, cobalt, and nickel sources as well as a chelating agent. The process variables, such as pH of the starting solution, spray drying conditions, and calcination conditions were optimized. The XRD pattern for the synthesized material indicated a good crystallinity with a layered structure.

• 한국전산유체공학회지
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• 제20권3호
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• pp.70-78
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• 2015

Turbulent flow and heat transfer characteristics of textile machine are numerically investigated. To examine the influence of flow structures on the drying performance of fabrics, the nozzle shape of high temperature chamber is changed. For several nozzles, flow and heat transfer characteristics are discussed. The results show that the drying performance is improved by controlling the angle and arrangement of nozzles corresponding to different drying conditions. This feature is strongly related to the enhancement of turbulent fluctuations and secondary flows.

• 한국기계가공학회지
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• 제18권12호
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• pp.45-51
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• 2019

As the separator becomes thinner, the role of thermal stability becomes more important in ensuring the high capacity of medium- and large-sized lithium-ion secondary batteries. In this study, we researched coating technology to improve the separator's thermal stability. We minimized the coating time by optimizing the design of a vertical two-stage coater that was thin, uniform, and capable of coating on both sides at the same time with a maximum 2㎛ thickness coating layer of fluorinated polymer (PVdF-HFP) on the bare polyethylene (PE) separator, which increased the thermal stability. In addition, during the coating process, a dual-jacket-roll method of drying was developed that increased the drying effectiveness without thermal damage to the separator. We also investigated the thermal stability of the separator manufactured from a coating machine, and studied the battery-applied performance by making a lithium-ion pouch battery.

• International Journal of Industrial Entomology and Biomaterials
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• 제35권1호
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• pp.45-50
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• 2017

Using the relatively low-cost, far-infrared dryer inhibiting the destruction of a variety of physiologically active components of the mulberry fruit, we have studied to make semidry mulberry fruit that can be kept at room temperature for a long time. By adjusting the temperature of the far-infrared dryer step-by-step, we developed a semi-dry method of maintaining the shape of the mulberry fruit. In addition, by drying the coating of honey after removing the juice generated by the mulberry fruit thawing process improved the acceptability of the taste of fruit. We conducted heat treatment mulberry fruit into a $95^{\circ}C$ infrared dryer 5 hours to thaw the frozen mulberry fruit. After 10 to 20% of honey coating, the primary drying ($95^{\circ}C$, 5 hours) was implemented. then, the secondary drying was conducted after controlling the temperature of the far infrared dryer $60^{\circ}C$, for 10 hours. These manufacture process was able to obtain semi-dried mulberry fruit. Dry weight ratio and moisture content were around 25%, and around 16% level respectively. It was to enable long-term storage at room temperature. Therefore, it is suggested that the method of using the far-infrared drying machine to manufacture semi-dried mulberry fruit can be a way to improve the farm income if applied to the farm.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.107-112
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• 2001

The IPC(Incremental Prestressed Concrete) which is gradually introducing the tensile force by tendons has been recently developed for reducing the effective depth of PSC bridges. As well known, concrete experiences long-term deformation such as creep and drying shrinkage, and the prediction of the long-term behavior of concrete bridges is essential for both safety and serviceability aspects. This paper was analysed the long-term behavior of a continuous 2-span IPC girder bridge taking into consideration of creep, drying shrinkage and the time of tensile force introduction. As results, the shrinkage of slab concrete increases the negative moment at interior support, and the The difference of concrete ages between slab and girder increases the camber. The effect of initial tensile force is larger than the effect of secondary tensile force in the tendons.

• 약학회지
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• 제15권1호
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• pp.32-40
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• 1971

Optimum reactons for the preparation of extra-light magnesium carbonate from magnesium chloride and sodium carbonate solutions were found by observing the difference of crystalline shapes under an electromicroscope. Reaction temperature the and washing temperature were main factors affecting the crystalline shapes, and drying temperature was found to be of secondary importance. Optimum temperatures for reaction and washing ranged from $20^{\circ}C$ to $30^{\circ}C$ and the temperature over $40^{\circ}C$ should be avoided for the reaction and washing. It was found that the higher the drying temperature, the lighter the crsytal of the produced magnesium carbonate. Reaction time, molar ratio (Mg$^{2+}/CO_{3}^{2-}$ ) and the concentrations of magnesium chloride and sodium carbonate solutions have only a slight effect on the form of the product.