• Journal of the Korean Wood Science and Technology
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• 제19권4호
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• pp.52-61
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• 1991

In this paper, the difference of the property of absorption and desorption for five species in semi-steady state are studied. The species used are listed in Table 1 and the dimension of specimen was $8\times8{\times}T$(Tangential direction)cm and tested in various conditions. A change of average moisture content with time were measured in each cycles. The results obtained are summarized as follows. When the relative humidity in air was maximum or minimum, the distribution of moisture In wood of all specimens were illustrated by exponential curves of decrease or increased from lace 10 center of wood. From the consideration of coefficient of decrease(C), the amount of moisture change of spruce was larger than the others. The pheonomenon was considered no relation to the specific gravity in air dry, but the wood structures. The velocity of the absorption and desorption for species decreased in the order spruce(Picea sitchensis) neodobam(Fagus crenata), solsong(Tsuga heterophylla), meranti(Shorea sp.) and kaesoo(Cercidiphyllum japoicum). In case of constant temperature and water vapor pressure is changed. the amount of absorbed moisture was larger than that of constant water vapor pressure and temperature vaned. In this fact, it is considered that the property of sorption of wood is strongly influenced by vapor pressure gradient than temperature gradient.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.479-482
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• 1999

Cured epoxy resins are extensively used for the electrical insulation in high-voltage equipments. The bisphenol A-based epoxy resins lured with azine show, especially, good thermal properties and mechanical resistances. For the technical and economic reasons, varing amount of inorganic fillers are added to endow the required special properties. In the large generators and motors of power plants, epoxy insulation is disclosed to the harsh conditions like the superheated steam and abrupt temperature variation. Hygrothermal aging at elevated temperatures tends to induce degradation in epoxy resins. To predict the effect of this degradation in DGEBA/MDA/SN/zeolite system, we proceeded the forced moisture absorption experiment using the autoclave. The thermal properties of the untreated and treated specimens were analyzed by DSC and TGA under the nitrogen flowing condition. The moisture absorption results showed a weight increase during hygrothermal aging at 1207. At the initial aging period, the system leaded to more or less postcuring but more prolonged environmental aging leaded the discoloration of specimen and lowering the T$_{g}$./.

• Advances in aircraft and spacecraft science
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• 제6권4호
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• pp.315-331
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• 2019

The stiffness degradation of the cross-ply composite laminates containing a transverse cracking and delamination in $90^{\circ}$ layer is predicted by using a modified shear-lag model by introducing the stress perturbation function. The prediction shows better agreement with the experimental results published by Ogihara and Takeda 1995, especially for laminates with thicker $90^{\circ}$ plies in which extensive delamination occurs. A homogenised analytic model for average transient moisture uptake in composite laminates containing periodically distributed matrix cracks and delamination is presented. It is shown that the model well describes the moisture absorption in a cross-ply composite laminate containing periodically distributed transverse matrix cracks in the $90^{\circ}$ plies. The obtained results represent well the dependence of the stiffness degradation on the crack density, thickness ratio and moisture absorption. The present study has proved to be important to the understanding of the degradation of the material propertiesin the failure process when the laminates in which the delamination grows extensively.

• 한국태양에너지학회 논문집
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• 제23권4호
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• pp.81-88
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• 2003

Earth friendly system is applied widely to industries for maintaining development. The declaration of earth friendly characteristic which is an indication of the total amount of energy in evaluation of earth friendly material is not easy to apply to building materials Therefore, Accurate standards about earth friendly materials are necessary. Earth friendly building materials should be considered in the fields of energy and resource consumption, changes in urban climate and resident health, etc. Among these fields, energy and resource consumption has released toxic pollutants into the air, caused indoor moisture problems and exhausted resources continuously. Especially, moisture problem is an indicator of main factors of earth friendly characteristic. Timber, Soil. Cement Mortar and Charcoal are used to examine the sustainable properties of materials of moisture control. The result shows that wood, charcoal and soil is vivid in changes of moisture absorption and discharge in comparison with that of cement mortar.

• 한국수산과학회지
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• 제52권3호
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• pp.232-240
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• 2019

Approximately 80% of the world's sea cucumbers Apostichopus japonicas are processed into dried sea cucumbers. The hot air-drying method is currently used in industry, but it has many problems, such as a short drying time, severe browning, high nutrition loss, and low recovery. In this study, the moisture absorption rate, dry recovery rate, and lipid nutrient composition of sea cucumber dried by heat pump decompression and with a hybrid dryer were investigated. The moisture absorption rates for hybrid-dried sea cucumbers at 24, 48, 72, 96, and 120 h were 241.3%, 427.7%, 652.0%, 721.0%, and 742.2%, respectively. The moisture absorption rates for hot air-dried sea cucumbers were 155.8%, 240.0%, 390.3%, 655.5%, and 667.4%, respectively. Thus, moisture absorption was faster and greater with hybrid drying than with hot air drying. The dry recovery rate at 24 h was greater for hybrid-dried sea cucumber (70.7%) than for hot air-dried sea cucumber (59.8%). Saturated fatty acid contents of the hybrid- and hot air-dried sea cucumbers were 30.0% and 37.5%, respectively. Moreover, greater ${\Sigma}n-3$ polyunsaturated fatty acid content was found in hybrid-dried sea cucumber (15.8%) than in hot air-dried sea cucumber (11.7%).

• 한국농촌건축학회논문집
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• 제21권1호
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• pp.37-44
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• 2019

Recently, various tourist products using hanok have increased rapidly. In the meantime, there is a steady demand for Hanok architecture. However, there are many negative perceptions about wood deformation and biodeterioration. Wood deformation and biodeterioration are related to moisture content. And the cracks occur in the process of removing water from the wood. Therefore, this study investigates the moisture content and cracks of dried hanok made of wood according to the drying method of wood. Drying methods include natural seasoning and artificial seasoning. There was a difference in moisture removal depending on drying period and method of natural seasoning. Drying time should be about 3 years for natural seasoning, so the moisture content of the wood is stable. In addition, the moisture absorption rate was low even in a humid environment where the voids were removed. However, natural seasoning is time consuming. Artificial seasoning, on the other hand, can quickly remove moisture from the wood and reduce porosity, but it is costly. Cracks that occur during the drying of wood may become problematic in appearance and stability due to wider spacing over time. As a result, the difference in the moisture content of the timber depending on the drying method and drying period of the wood was maintained even after the formation. These gaps appeared to be differences in moisture absorption in a wet environment.

• 한국해양공학회지
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• 제11권2호
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• pp.48-56
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• 1997

This work has been investigated in order to study the influence of the moisture absorption on the mechanical pf the glass fiber/epoxy resein composites and the carbon fiber/epoxy resein composites. The types of glass fiber used in the glass fiber/epoxy resein composites were randomly oriented fiber and plain fabric fiber. And carbon fiber.epoxy resein composites was laminated with fabric prepreg which was formed with carbon fiber and epoxy resein. Both composites were immersed up to 100 days in distilled water at $80^{\circ}C$, and then dried up to 3 days in an oven at 80$80^{\circ}C$. Both composites were measured for the weight gain of water(wt.%) and tensile strength through immersion and dry time. Consequently, it was found that the tensile strength of thw glass fiber/epoxy resein composites and the carbon fiber/epoxy resein composites were reduced proportionally to the moisture absortion rate. Also, the tensile strength of glass fiber composites was decreased more than that of the carbon fiber composites. Additionally, it was found that the tensile strength of all composites which decreased by moisture absorption were partly recovered by drying in an oven at 80$80^{\circ}C$.

• 한국의류학회지
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• 제41권1호
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• pp.28-42
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• 2017

Moisture transfer characteristics of high emotional garments are important to evaluate wear comfort. Wicking and drying measurement methods are also critical for perspiration absorption and quick dry fabric made of high functional fibers. In this study, the wicking and drying properties of high emotional fabrics made from hybrid composite yarns using CoolMax, Tencel, Bamboo staple fibers and PP. PET CoolMax filaments were also measured and analyzed according to various measuring methods. The wicking property of hybrid composite yarn fabrics by Bireck method was mostly influenced by the structure of hybrid yarns than the absorption rate of constituent fibers; however, both the hygroscopicity of fibers and the composite yarn structure affected the wicking property of the fabrics in the drop method. Concerning drying properties, the KSK 0815B method measuring distilled moisture weight was more relevant to explain the drying characteristics of hybrid yarn fabrics than the KSK 0815A method measuring the time to drying. This study revealed that the drying properties of hybrid yarn fabrics were influenced by the hygroscopicity of constituent fibers, wicking properties of constituent yarns and structure of composite yarns.

• Journal of the Korean Wood Science and Technology
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• 제46권6호
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• pp.637-644
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• 2018

The air permeability of yellow poplar log cross section before and after organosolv pretreatment was investigated, and the moisture absorption of control and organosolv pretreated rectangular parallelepiped specimens was investigated in this study. It was revealed that the diameters of through pores were enlarged and the number of bigger pore was increased by the organosolv pretreatment. The air permeabilities of the cross sections of yellow poplar log were changed from 1.61 darcy to 23.30 darcy, but their weights were reduced by 5 percent. The equilibrium moisture content of control wood specimen at the exposed relative humidity were 5.9 % at 32 %, 9.7 % at 58 %, 14.8 % at 80.5 %, 19.7 % at 90 %, 25.7 % at 95 % and 29.9 % at 100%. The equilibrium moisture content of the specimens pretreated with the parameter of sulfuric acid catalyst of 0.5 % (w/w) were 19.5 % at 32 %, 29.3 % at 58 %, 39.6 % at 80.5 %, 59 % at 90 %, 111.3 % at 95 % and 111.3 % at 100 %, while those pretreated with the parameter of sulfuric acid catalyst of 1.0 % (w/w) were 17.4 % at 32 %, 23.9 % at 58 %, 27.7 % at 80.5 %, 40.6 % at 90 %, 68.8 % at 95 % and 110.0 % at 100 %. The moisture absorption of organosolv pretreated rectangular parallelepiped specimens was higher than that of control specimen.

• 마이크로전자및패키징학회지
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• 제29권3호
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• pp.37-42
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• 2022

최근 반도체 패키지 구조는 점점 더 얇아지고 복잡해지고 있다. 두께가 얇아짐에 이종 계면에서 물성차이에 의한 박리는 심화될 수 있으며 따라서 계면의 신뢰성이 패키징 설계에 중요한 요소라 할 수 있다. 특히, 반도체 패키징에 많이 사용되는 폴리머는 온도와 수분에 영향을 크게 받기 때문에 환경에 따른 물성 변화 고려가 필수적이다. 따라서, 본 연구에서는 다양한 온도조건에서 수분의 흡습과 탈습을 모두 고려한 패키지 구조의 계면 박리 예측을 유한 요소 해석을 통해 수행하였다. 확산계수와 포화 수분 함량과 같은 재료의 물성은 흡습 실험을 통해 확보하였으며, 흡습 이후 TMA 와 TGA 를 통하여 각 재료의 수분 팽창 계수를 확보하였다. 각 계면의 접합 강도 평가를 위해 수분의 영향을 고려하여 다양한 온도 조건에서 마이크로 전단 실험을 수행하였다. 이러한 물성을 바탕으로 온도와 수분에 의해 발생하는 변형을 모두 고려한 패키지 박리 예측 해석을 수행하였으며, 결과적으로 리플로우 공정 동안의 실시간 수분 탈습 거동을 고려한 계면 박리 예측을 성공적으로 수행하였다.