• Transactions of the Korean Society of Mechanical Engineers
• /
• v.13 no.4
• /
• pp.636-642
• /
• 1989

In this paper, 3-dimensional fracture phenomena in the local area near the notch tip between the surface and the center of a composite bar which is consisted of two different materials were investigated by using embedded dyeing grids with the pitch of 50.8.mu. It was confirmed that the maximum strain near the notch tip occurred not at the notch front but at the curvature beginning point of the notch which is in the interior of z/W = 0.3 - 0.35 from the surface and a notch was initiated from that point. And that the strain near the notch front between the center and z/W = 0.65 - 0.7 toward the surface was in a state of compression.

• Journal of the Korean Wood Science and Technology
• /
• v.41 no.2
• /
• pp.111-122
• /
• 2013

The steam explosion-chemical pretreatment is a more effective wood pretreatment technique than the conventional physical pretreatment by accelerating reactions during the pretreatment process. In this paper, two-stage pretreatment processes of hardwood were investigated for its enzymatic hydrolysis and the succinic acid yield from the pretreated solid. The first stage pretreatment was performed under conditions of low severity to optimize the amount of solid recovery. In the second stage pretreatment washed solid material from the first stage pretreatment step was impregnated again with chemical (alkaline or chlorine-based chemicals) to remove a portion of the lignin, and to make the cellulose more accessible to enzymatic attack. The effects of pretreatment were assessed by enzymatic hydrolysis and fermentation, after the two stage pretreatments. Maximum succinic acid yield (16.1 g $L^{-1}$ and 77.5%) was obtained when the two stage pretreatments were performed at steam explosion -3% KOH.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.42 no.1
• /
• pp.7-12
• /
• 2010

Morphological characteristics of hemp fiber were investigated using a light microscope in order to provide fundamental data for the use of hemp as a papermaking law material. Phloem of hemp is composed of cortical parenchyma cells and bast fiber with thick walls while xylem is composed of vessel, wood fiber and ray parenchyma cells. Also there are solitary pore and radial pore multiple which exist in diffuse porous pattern. Ray cells consist of uniseriate rays and thin walled ray parenchyma cells. Wood fibers are composed of three types: a large diameter fiber with longer length; a large diameter fiber with shorter length; a small diameter fiber with medium length. Vessel elements are composed of: a medium length one; a longer length one; the one whose both end walls have ligules or tails. Parenchyma cells in xylem and pit parenchyma cells have completely different size and shape. For bast fiber, the average length is about 4.4 mm and the width is about $30.5\;{\mu}m$; for vessel element, $600.0\;{\mu}m$ in length and $493.6\;{\mu}m$ in width; for wood fiber, $1000\;{\mu}m$ and $38.9\;{\mu}m$; for parenchyma cell, $50\;{\mu}m$ and $26.4\;{\mu}m$.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.25 no.4
• /
• pp.293-300
• /
• 2012

In this study, the delamination analysis has been implemented to investigate the initiation and propagation of crack in composite laminates composed of orthotropic materials. A simple modeling was achieved by moving nodal technique without re-meshing work when crack propagation occurred. This paper aims at achieving two specific objectives. The first is to suggest a very simple modeling scheme compared with those applied to conventional h-FEM based models. To verify the performance of the proposed model, analysis of double cantilever beams with composite materials was implemented and then the results were compared with reference values in literatures. The second one is to investigate the behavior of interior delamination problems using the proposed model. To complete these objectives, the full-discrete-layer model based on Lobatto shape functions was considered and energy release rates were calculated using three-dimensional VCCT(virtual crack closure technique) based on linear elastic fracture mechanics.

• Journal of Korea Multimedia Society
• /
• v.12 no.8
• /
• pp.1164-1171
• /
• 2009

This paper proposes an efficient implementation way of traditional wooden building using Parametric modeling method which uses the relations of numerical value ratio between building materials. Building structures and order of construction for Geunjungjeon of Kyuungbok Palace is digitally implemented proving the efficiency of the suggested proposal. Although the existing digital modeling methods for traditional wooden building emphasize the exterior modeling of the building, our modeling method constructed numerous wooden materials and arranged those pieces orderly so that people can see the interior structures of the building which usually is beyond one's vision. The suggested Parametric modeling method, Multi-Object Texture Mapping, Physical Camera Restoration, and GI Renderer for implementing Geunjungjeon of Kyuungbok Palace can be practically used for digital implementation for other traditional wooden buildings.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.43-44
• /
• 2023

Fire doors installed to prevent the spread of fire in buildings are made of paper honeycomb, glass wool, and other materials. Due to their high water absorption rate, they absorb ambient moisture and degrade, and their increased weight causes them to sag internally, creating voids that can warp in the event of a fire and allow flames to pass through. To overcome these issues, research is being conducted on the physical performance of lightweight aerated concrete. However, there is a lack of research on how to ensure fire resistance. Therefore, in this study, the backside temperature of lightweight aerated concrete formulations was measured and compared and analyzied with the physical performance. Since it is difficult to achieve low density by saturation alone, aerated concrete with EPS was produced, which resulted in a density reduction of 24'26%, but the strength increase per unit cement increase was 5'25%, which tended to be lower than the formulation without EPS. The results showed that the lightweight aerated concrete with EPS was 130~140℃ lower than the lightweight aerated concrete with EPS, which is believed to be due to the melting point of EPS delayed the heat diffusion. In the future, wo plan to conduct research to identify the optimal formulation for fire door core materials by varying the amount of EPS added and using industrial by-products to increase long-term strength.

• International Journal of Human Ecology
• /
• v.8 no.1
• /
• pp.67-78
• /
• 2007

The aim of this paper was to compare differences and similarities of farmhouses between Denmark and Korea as a cross-cultural study. Farmhouses built during the 18th and 19th centuries in Denmark, and ones from Chosun Dynasty (AD. 1392-1910) in Korea were targets of this study. Literature study and field trips to districts and open-air museums in both countries were used. Field trips were carried out during summer of 2005 in Denmark, and fall of 2005 in Korea. Detailed comparisons focused on farmhouse plans, the use of rooms and furnishing, and building materials. As a conclusion, some differences were found between the two countries. In terms of farmhouse plans, square types with four wings, and parallel types were the most frequent forms in Denmark, while a few types, such as the "I", "L", "U" shapes and square types, were more frequently found in Korea. In Denmark, the most important room was the dwelling-room, in which daily family life took place. Every member of the family slept, ate, and worked here, and kept geese and young animals during the winter season. Therefore, this room was laid out in the center of the house. However, Anbang, the most important room in Korea, was not situated in the best part of the house. Instead, the Daechung-maru occupied the center and the best place because the daechung-maru, in which the ancestral ceremony was held, was thought of as more important than a place for live people. Also the use of rooms and furnishing was quite different between the two countries, reflecting each life style. Danish furnishings represented practical daily life, while Korean furnishings reflected more conceptual aspects. It might have resulted from Confucianism in the Chosun Dynasty, which ruled daily life and even influenced use of rooms and furnishings. In other word, philosophy influenced common peoples' daily life and living environment. With reference to building materials, there was rarely a difference between the two countries. Major materials for farmhouse were quite common, such as half-timbering wood and clay, but the difference was in bricks and roof coverings. Bricks were rarely used in Korean farmhouses, while rice-straw was rare for the roof of a Danish farmhouse. Of course, the choice of materials was strongly affected by the local surroundings and overall environment. This result can give some clues for design ideas when architects and interior designers plan housing that is adapted for local peoples. This kind of cross-cultural study can also contribute to one's understanding of foreign culture, especially in housing and culture. And, it can broaden one's insight of design ideas for designers who have to compete frequently with designers in foreign countries.

• Journal of the Korean Home Economics Association
• /
• v.11 no.4
• /
• pp.424-435
• /
• 1973

This paper attempts to find out the development of designs of chairs in interiors. It will discussed by dividing into two periods; the pre-world war I, and the post-world war I up to date. In the first part it will concentrate on four types of design materjals; plywood, metal, solid wood, and plastic chairs. In the second part it will deal with only two materials; Metal and solid wood. Under each material one designer and manufacturer, the country where the designer worked, and related dates. It will discuss how the design materiai was exploited by each designer within its potentials including how chair was made, what design elements could do, whether he used the potentials, and the potentials were fully exploited. And it discusses the success of the chair design material as shown in the interiors or failure of the chair design material. Fainally under each material one picture of chairs, one or two pictures for the chairs in the interiors, of the chairs will be provided. A bibliography will be attached to the end of the paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.38 no.3 s.116
• /
• pp.29-37
• /
• 2006

To use bamboo in the pulp industry, the anatomical characteristics of 60-day-old, 1-year-old, 2-year-old, and 3-year-old moso bamboo (Phyllostachys pubescens Mazel), and the characteristics of fiber and sheet of alkali pulp made of moso bamboo were investigated. Moso bamboo is composed of metaxylens and parenchyma cells in the inner part of the wall, and thick-walled small bundle sheathes near the outer walls. Moso bamboo showed the heterogeneity in anatomical structure. The longest fibers were shown in the middle part, and the widest width in the inner part. The lignin contents were 14.4% in 60-day-old bamboo, which was not lignified yet. The lignin contents in bamboo above 1 year were approximately 35%. The yields of alkali pulp of moso bamboo were in the range between 41 and 47%, and the yields tend to decrease with the increase of ages. The lignin contents of 60-day-old bamboo were 2.1% and those of bamboo above 1 year showed approximately 4% to 5% increment. The length, width, and curl index of fiber in alkali pulp appeared to be similar in all ages. However, coarseness increased slightly with the increase of bamboo ages. The distribution of long fiber was shown much in 60-year-old bamboo. The optical and mechanical properties of moso bamboo tended to decrease with the increase of bamboo age.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.43 no.3
• /
• pp.43-51
• /
• 2011

Chemical composition and contents of carbohydrates, lignin, and extractives in Moso(Phyllostachys pubescens Mazel), Henon(Phyllostachys nigra var. henonis Stapf ex. Rendle), and Timber bamboo(Phyllostachys bambusoides Sieb. et Zucc.) known as economically valuable bamboo species in Korea were analyzed as a function of ages. All of tested bamboo species were composed of fucose, arabinose, rhamnose, galactose, glucose, xylose, and mannose. Glucose was the sugar which showed the highest content followed by xylose. The contents of others were below 3%. Sugar contents of bamboo shoots showed the lowest among the tested bamboo samples, and the constant rates were shown after 50 days of growth. Lignin content increased by the growth of one year, and the increasing rates tended to be constant after the growth of three years. Bamboo shoots have the highest contents of acid-soluble lignin, which turned into insoluble lignin after the growth of 50 days. Bamboo shoots showed the highest content of extractives and tend to be decreased by the growth of 50 days and then the content increased slowly in proportion to the period of bamboo growth. No relationship was found between species and chemical composition of bamboo. However, there were significant difference in chemical composition between bamboo shoots and 50-day old bamboo.