• Journal of the Korean Wood Science and Technology
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• v.10 no.3
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• pp.88-95
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• 1982

In order to investigate the physical properties of pine wood (Pinus desiflora S. et Z.) grown in Gangweondo this study has been carried out. The properties studied are percentage of latewood portion occupied in each cross section, specific gravity, crushing strength and relationships between them, respectively. The results summarized are as follows: As far as percentage of latewood portion and specific gravity are concerned, no differences between heartwood and sapwood have been seen, however, the crushing strength of the sapwood has shown larger value than that of the heartwood. 2. Width of annual ring have a defined effect on percentage of latewood and crushing strength, but specific gravity is not influenced significantly by width of annual ring. Percentage of latewood and crushing strength increased with decreasing width of annual ring (Tables 2 & 3). 3. Linear relationships between specific gravity and percentage of latewood, crushing strength and percentage of latewood, crushing strength and specific gravity for both heartwood and sapwood of pine have respectively been seen. Furthermore heartwood and sapwood have shown different patterns of variation as the following equations and Figures 1,2 and 3.

• Fire Science and Engineering
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• v.31 no.6
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• pp.74-82
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• 2017

Fires in buildings built using sandwich panels are difficult to extinguish, and the damage caused by the fire spreading through the inner core material is extensive. Sandwich panels consist of a nonflammable material on both sides of an insulation material. The types of insulation material include organic and inorganic insulation materials, but the former are used in more than 80% of the case. Organic insulation is economically advantageous compared to inorganic insulation, but it is vulnerable to fire. Therefore, the damage caused by sandwich panel fires is higher than that for general fires. In the case of the noxious gas analyzer test, the panel is tested with three round holes having a diameter of 25 mm, in order to determine the risk of the core material, but the cone calorimeter test is carried out using a sandwich panel. In this study, the cone calorimeter test was conducted to examine the fire risk of the composite material when heated on a nonflammable surface, exposed to the core material through a hole, and heated directly the core material. The type of organic insulation employed was flame retardant EPS (Expanded Polystyrene), and the test specimens were tested in three types of sandwich panel, a perforated sandwich panel and single core material. The purpose of this study is to propose a method of measuring the fire risk of the core materials of composite materials using the cone calorimeter test.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.501-507
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• 2011

To develop environmental-friendly insulating composite materials, natural cellulose and porous ceramic balls were used as core materials and activated Hwangtoh was used as a binder. Various specimens were prepared with different water/binder ratios and core material/binder ratios. The physical properties of these specimens were then investigated through compressive strengths, flexural strengths, absorption test, hot water resistance test, pore analysis, thermal conductivity, and observation of micro-structures using scanning electron microscope. Results showed that the maximum compressive strength varied appreciably with the water/binder ratios and core material/binder ratios, but the flexural strength increased with the core material/binder ratios regardless of water/binder ratios. The compressive strength and the flexural strength measured after the hot water resistance test decreased remarkably compared to those measured before test. The pore analysis measured after the hot water resistance test showed that total pore volume, porosity and average pore diameter decreased, while bulk density increased by the acceleration of hydration reaction of binder in the hot water. The thermal conductivity decreased gradually with an increase of core material/binder ratios. It can be evaluated that the composite insulation materials having good insulating properties and mechanical strengths can be used in the field.

• Journal of the Korea Furniture Society
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• v.10 no.2
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• pp.63-71
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• 1999

본 연구는 목재중의 수분량이 변화하는 비정상태하에 있어서의 액체투과성을 평가하기 위한 새로운 방법으로써 원심법에 의한 액체투과성을 평가하기 위한 새로운 방법으로써 원심법에 의한 액체투과성의 평가법을 확립해 보고자 실시하였다. 이 방법은 원심력장에 있어서의 액체투과성과 원심처리부로부터 액체투과성을 평가하는 것이다. 실험결과, 삼나무(Cryptomeria japonica)와 미송 (Pseudotsuga menziesii)은 서로 다른 탈수경과를 나타내었다. 삼나무는 미송보다 더 많은 탈수량을 보였고 재내의 태수량의 변이가 심하였다. 한편 변재와 심재의 탈수거동에 있어서 삼나무는 기체투과성에 의해 평가된 값과 상반된 결과를 나타내었다. 즉, 2200∼3300rpm의 범위에서 편재는 심재보다 탈수량이 적었다.

• Journal of Digital Convergence
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• v.11 no.8
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• pp.349-358
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• 2013

This thesis is a study on Zhuang-zi's theory of self-cultivation. "Mind" is an important concept in Zhuang-zi's philosophy. According to Zhuang-zi "mind" has dual character and its basic state includes the mind which is in keeping with Tao and the mind which is not. They separately refer to mind's natural state(靈府靈臺 之心) and unnatural state(成心). The former is compatible and harmonious while the latter is contradictory. The accomplishment of mind eventually means transcending unnatural mind and attaining mind's natural state. To realize natural mind, Zhuang-zi propose xinzhai(心齋)and zuowang(坐忘).

• Journal of Korea Fair Competition Federation
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• no.60
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• pp.22-28
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• 2000

• 수목보호
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• s.3
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• pp.33-38
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• 1997

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.69-69
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• 2012

지구상에는 약 40만 종의 식물이 존재하는 것으로 알려져 있으며 이 중에 는 질병의 치료를 위한 약재로 이용되거나 나무는 대부분 목재 등으로 이용된다. 향나무(Juniperus chinenesis L.)는 항균성 및 방충성이 뛰어난 상록수로서 목재는 조각재나 가구재로 사용되고 민간 및 한의학에서 다양한 증상의 약재로 쓰이고 있으며 부패한 냄새를 제거할 목적이나 향재 및 향료로도 쓰이고 있다. 열매의 정유성분은 화장품, 술, 캔디 등에 사용되며 cedrol은 향료보류제, 유분은 훈향료, 목부는 고혈압, 곽란, 심복통, 통기파혈에 쓰인다. 향나무는 폴레페놀 성분이 함유되어 있고 피톤치드가 많이 나오는 것으로 알려져 있으며 심재의 폴리페놀 화합물은 항암, 항균, 항알러지, 노화방지 및 심장질환 등을 예방하거나 지연시키는 등 광범위한 약리학적 활성을 나타내어 식품, 의약품, 화장품, 향료등 다양한 분야에 활용되고 있다. 향나무 추출물에 관한 연구로는 성분분석과 생리활성 등에 관한 의약학 분야의 다양한 연구와 항산화, 항균활성 등 약리작용에 연구가 최근 다양하게 이루어지고 있는 것을 볼 수 있다. 측백나무속에 속하는 나무들은 대부분 정유 성분을 함유하고 있는 특성으로 항균성 등 바이오 기능성 소재 개발을 위한 연구가 활발히 진행되고 있으나, 향나무 추출물의 염색성에 관한 연구는 찾아보기 어려운 실정이다. 이에 본 연구에서는 다양한 용매를 이용하여 향나무의 잎, 열매, 수피, 심재 각 부위 추출물을 이용하여 견직물에 대한 염색성을 살펴봄으로써 향나무 추출물을 활용한 천연염색과 염재로서의 가능성을 확인하고자 하였다. 실험 결과 증류수를 염액 용매로 염색한 결과 모든 추출물의 잎, 열매 염색포의 색상은 대부분 옅은 Y계열로 나타났으며 향나무의 수피와 심재 염색포는 대부분 적색기미가 강한 YR계열로 나타났다. 에탄올 혼합액을 염액 용매로 하여 염색한 결과 향나무의 잎과 열매의 색상은 대부분 Y계열의 색상을 나타냈고 유기용매 추출염색포에서 정유성분으로 추정되는 물질 때문에 균염이 어려웠으며 수피와 심재 염색포에서 대부분 R계열의 색상이 뚜렷이 나타났다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.557-560
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• 2008

This was done by analyzing the sandwich panels that are now widely used in construction work. Sandwich panels are used for diverse purposes in construction work worldwide. In Korea, polystyrene panels that have organic materials as their core material are used. These panels are thus very vulnerable to fire, with risks of core melting, sheet deformation, and hazardous gases. Accordingly, sandwich panels' fire-resistant or non-flammable properties must be secured. To solve these problems, the optimal mixing proportion of lightweight foamed concrete for the sandwich panel core was determined. A new method of doing this was introduced that is completely different from the existing method, wherein a foaming agent is added to realize lightweight concrete. For lightweight concrete, the foaming mechanisms via diverse chemical reactions were identified, H$_2$O$_2$ was added for heating in the reaction, and the concrete foaming was maximized. Through diverse experiments to determine the optimal mixing proportion of lightweight foamed concrete and to examine the filling characteristic of lightweight foamed concrete for sandwich panel cores using waste materials, the physical and mechanical properties of lightweight foamed concrete were examined.

• Composites Research
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• v.28 no.2
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• pp.58-64
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• 2015

The purpose of this paper is to suggest the effective equivalent finite element model for the impact limiter of a nuclear spent fuel shipping cask made of sandwich composite panels. The sandwich composite panels were composed of a metallic facesheet and a core material made of urethane foam, balsa wood and red wood, respectively. The effective equivalent finite element model for the impact limiter was proposed by comparing the results of low-velocity impact test of sandwich panels. An explicit finite element analysis based on LS-DYNA 3D was done in this study. The results showed that the solid elements were recommended to model the facesheet and core of sandwich panels for impact limiter compared to combination modeling method, in which the layered shell element for facesheet and solid element for core material are used. In particular, the solid element for balsa and red wood core materials should be modeled by the element elimination approach.