• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.313-314
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• 2003

분할형 극세사 직물은 서로 상용성을 가지지 않는 nylon/polyester의 용융고분자물을 복합방사법에 의하여 filament 형태로 방사한 후 이를 제직, 편성의 방법으로 포를 제조하고 알칼리 용액에 처리함으로써 생산되어 진다. 따라서 극세사 직물은 일반적으로 소수성의 합성섬유로 이루어졌음에도 불구하고 알칼리 가수분해에 의하여 분할된 섬유 사이의 수많은 모세관에 의하여 높은 흡수성과 수분전이능력을 갖게 된다. 이러한 이유로 극세사 직물은 일반적인 와이퍼의 용도뿐만이 아니라 food service, medicine, 반도체를 제조하는 clean room등으로 그 응용범위를 넓혀 가고 있다. (중략)

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1492-1499
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• 2001

In order to develop the compact and flexible heat exchangers, we made the helically coiled heat exchangers. They can be manufactured with small diameter copper tubes without the need for fins; inner diameter=1.0 mm, straight tube length=1.5 m. The experiments were carried out with the following conditions; evaporation pressure=0.6 MPa, air velocity=0.7 ∼ 1.7 m/s, and working fluid=R-22. Pressure drop and heat transfer coefficient of heat exchangers were experimented according to the air velocity. The results of heat transfer coefficient show a 35% beneficial increase fur these heat exchangers over the other covered fin-tube heat exchangers. A cooling capacity of about 3 kW was obtained with an air velocity of 1.5 m/s. The distribution header has also been designed fur efficient distribution of refrigerant flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.5
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• pp.699-708
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• 2000

To make compact evaporator, experiments that show characteristics of evaporating heat transfer and pressure drop in the helically coiled small diameter tube were taken in this research. The experiments were performed with HCFC-22 in the helically coiled small diameter tube; inner diameter=1.0(mm), tube length=2.0(m), and curvature diameter=31, 34, 46.2(mm). The experiments were also carried out with the following test conditions; saturation pressure=0.588(MPa), mass velocity=$150{\sim}500(kg/m^2s)$, and heat flux=$1{\sim}5(kW/m^2)$. The experiment results are that the empirical correlation to predict heat transfer coefficient for single phase flow in helically coiled small diameter tube was obtained. It was found that dry-out is occurred at low-quality region for evaporation heat transfer because of breaking of annular liquid film. The friction factor of single phase flow of helically coiled tube was agreed with Prandtl's correlation. Finally, It was proposed for correlation that can precisely predict the friction factor of two phase flow of helically coiled tube.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.4-4
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• 2011

본 연구에서는 해도형 나일론 극세사 제품의 알칼리 용출 및 염색특성에 대한 고찰과 인공피혁, 스웨이드 조직 편물 등의 목적으로 함께 쓰이게 될 폴리우레탄과의 혼방 제품의 염색성 향상에 대한 연구를 진행하였다. 먼저, 해도형 나일론 극세사의 알칼리 용출거동을 확립하기 위해 NaOH 농도 및 온도에 따른 감량 특성을 확인하였으며, Red 색상의 산성염료와 반응성 염료 타입에 따른 염색특성 및 세탁 견뢰도 등을 고찰하였다. 또한, 폴리우레탄의 염착성을 향상시키기 위해 폴리우레탄 합성시 고분자 말단에 아민기를 함유하는 시료에 대한 염색성을 고찰하고, 폴리우레탄 함침 소재로서 쓰이는 인공피혁을 제조하여 염색 특성을 알아보았다. 해당 연구를 통하여 다음과 같은 결과를 얻을 수 있었다. 해도형 초극세사의 알칼리 용출의 경우 $90^{\circ}C$에서 30분 유지시키는 것이 가장 적절한 조건이었으며, pH에 따른 염색성의 경우 레벨링 타입 염료와 반응성 염료의 경우 4~5, 밀링 타입과 함금속 염료의 경우는 5~6정도의 pH에서 우수한 염색성을 나타내었다. 산성염료의 경우 염색온도와 시간이 증가함에 따라 초극세사에 염착된 염료들은 이면의 일반 나일론사로 이동하는 현상이 증가하였지만 반응성 염료의 경우는 이러한 이염 현상이 나타나지 않았다. 한편, 농도가 증가함에 따라 산성염료는 우수한 빌드업성을 나타내는데 반해 반응성 염료는 4% owf이상에서는 염착량이 증가하지 않았으나, 세탁 견뢰도의 경우 반응성 염료로 염색된 시료가 가장 우수한 견뢰도를 나타내었다. 그리고 앞선 모든 염색실험에 있어서 일반 나일론사보다는 초극세사의 염착률이 더 높았고, 겉보기 색농도는 낮게 나타나는 현상을 확인할 수 있었다. 한편, 나일론/폴리우레탄 혼방제품에서 쓰이는 일반적인 폴리우레탄(RPU)과 아민 함량이 높은 폴리우레탄(APU)의 염색성을 알아본 결과 APU의 염색성이 훨씬 우수하였고, RPU에서 나타나는 현상인 염색의 진행에 따른 염료의 탈리가 나타나지 않았으며 견뢰도 또한 우수하였다. 인공피혁의 염색에서는 함침에 사용된 폴리우레탄 수지의 구조에 따라 염색성이 달라지는 현상을 확인하였으며, 특히 반응성 염료를 사용할 경우 인공피혁에서 일반적으로 문제가 되는 견뢰도 저하의 현상이 나타나지 않았다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1573-1576
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• 2003

The quality of bundles is closely related with the apparent thickness. Especially the variation of apparent thickness of bundle determines the qualify of the plane structure made or the bundle such as surface evenness, pore size, and the shape of air-gap, etc.,. This study is dealing with the development of a new measuring system of the thickness of bundle or cross-section by determining the size of the shadow of the object covered by a laser slit beam. Also the measured signal is characterized in terms of the correlogram, the irregularity in wavelength. The correlogram for the irregularity of several sample types could be represented by a sinusoidal function with exponentially decaying amplitude. Moreover, influence of the measuring speed on the signal and the characteristic differences according to the different types of bundle are investigated.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.1
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• pp.112-118
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• 2004

Cowden syndrome is very rare clinical condition with characteristic mucocutaneous lesions associated with abnormalities of the breast, thyroid, and gastrointestinal tract. Here, the case of a 16-year-old girl with diverse gastrointestinal polyposis with breast and thyroid lesions is reported as a definite case of Cowden syndrome. During follow up for 4 years, changes in the characteristic lesions were observed; Esophageal acanthosis and oropharyngeal polyps were newly developed. Gastric, duodenal, rectal and ileal polyps were noted at the first visit when she was 12 years of age and revealed histologically hyperplastic polyps. Mucocutaneous lesions, the pathognomonic finding of Cowden syndrome, were not noted at the first visit or during the follow up period. Breast and thyroid masses were noted at the first visit. Breast aspiration showed highly cellular ductal epithelial fragments and fibroblastic stromal cell fragments, and a thyroid biopsy shows proliferation of irregular sized follicles, with variable colloid contents. Macrocephaly was also noted at the first visit. The characteristic lesions of Cowden syndrome change with the patient's age, and the long-term follow up is recommended in cases suspected with this syndrome.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.2
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• pp.177-181
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• 1988

To get the basic information about ginseng seedling production, yield of ginseng seedling and soil physico-chemical components of Ban-Yang-Jik (semimodified soil) nursery in 29 farmer's field were investigated. The number of available seedling per Kan (Kan means $180{\times}90cm$ area) is $362{\pm}226$. Root weight per seedling was negatively correlated with ammount of fine and extremely fine sand. Positive correlations were shown between pH and OM, K, Ca and Mg, and also between EC and Ca, Mg and ammonium and nitrate nitrogen in soil of nursery. There were significant linear relations between root weight and OM, K, Ca and Mg in soil of nursery. On the other hand, quadratic relation was held between the root weight and $P_2O_5$, but the root weight has no correlation with nitrogen. The nitrogen contents of soil might not influence on the growth of ginseng seedling as greatly as those of $P_2O_5$, K and Ca. The contents of $P_2O_5$, K and Ca in root were increased with increase of the contents of $P_2O_5$, K and Ca in soil of nusery, respectively. It showed the linear correlation between the root weight and $P_2O_5$ and Ca, otherwise quadratic correlation between the root weight and K in root.