• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.13-22
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• 2007

This study was carried out to scrutinize possibility of manufacturing pitch pine (Pinus rigida) glued laminated timber in order to add values of pitch pine trees. Also, it was investigated to improve bending performance of pitch pine glulam. Pitch pine was imported as one of major plantation species in Korean peninsula. Machine stress rated grades of pitch pine lumber mostly ranged between E7 and E9. which grades were more or less inferior to producing high quality glulam. However, the adhesive properties between pitch pine and pitch pine, and between pitch pine and Japanese larch (Larix kaempferi Carr.), such as shear bond strength, wood failure rate and de-lamination rate of bonded layer submerged in cold and boiling water, were higher than Korean Standard criteria. These properties are essential for manufacturing glulam with single species or multiple species. The modulus of rupture (MOR) of pitch pine glulam exceeded the criterion of Korean Standard for glulam strength grade but modulus of elasticity (MOE) was lower than the criterion. On the other hand, the bending performances (MOR and MOE) were improved 20 percent by mixing with Japanese larch laminar. It is effective to arrange higher quality Japanese larch laminar at the outer layer of glulam for improving bending performances. In conclusion, it is possible to use low quality pitch pine as laminar of structural glulam for adding values of pitch pine.

• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.84-92
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• 2008

Anatomical and physical characteristics of Pinus densiflora woods damaged by forest fire at Yangyang-gun, Kangwon-do were investigated in present study. Even though the bark was severly carbonized, no trace of carbonization in the xylem was found. The amount of resin exudation was different by the degree of fire damage. Green moisture content of sapwood in the damaged wood was lower than that in the sound wood, but vice versa in the heartwood. Green density of heartwood in the damaged wood was higher than that in the sound wood, but there was no significant difference in sapwood. Cambial activities were found stopped in the severely damaged wood but were identified in the lightly damaged wood. In safranine staining process, epithelial and ray parenchyma cell walls in the damaged woods showed darker hue than those in the sound wood. Granular substances were observed in the lumina of ray parenchyma and epithelial cells of the severely damaged wood. Relative crystallinity of the outermost growth ring in the severely damaged wood was slightly higher than that in the sound wood.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.333-336
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• 2006

A new forming method for metal/ other metal two-layer tubes by multi-billet extrusion (MBE) is introduced. The forming possibilities of two-layer tubes CDA 365(inner)/Al 1100(outer) and Al 2014(inner)/Al 1100(outer) by MBE are investigated according to the given frictional condition and die profile. The results show that two-layer tube composed by two types tube as abovementioned can be manufactured by MBE. Some stated variables in the forming process such as effective stress and normalized pressure at welding surface are analyzed by FEM code ($DEFORM^{TM}$-3D)

• Journal of the Korean Wood Science and Technology
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• v.39 no.6
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• pp.521-530
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• 2011

Nowadays, market demand of structural Glulam is growing and diversifying. The durability of Glulam should be significantly considered when they are intended to apply for out-door use such as timber bridge and pergola. This study was aimed to develop the manufacturing process of preservative treated structural Glulam using domestic softwood species. 10 m long structural Glulam were manufactured from domestic pitch pine logs with CuAz-3 preservative treatment. At each manufacturing process, the production yield was evaluated. Finally, bending tests were performed to verify the structural performance of manufactured Glulam. From the results, it was shown that the preservative treatment process hardly influenced on the production yield. But domestic pitch pine was proved to not be suitable for making the preservative treated Glulam due to the large difference of preservative permeability between sapwood and heartwood.

• The monthly packaging world
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• s.236
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• pp.43-47
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• 2012

본 조사의 대상은 화물을 일정한 수량 단위로 하역 운송 보관하기 위하여 사용하는 파렛트이다. 조사 대상 파렛트는 용도에 따라서 재사용 파렛트와 일회용 파렛트로 구분하되, 재사용 파렛트는 다시 구매 보유 물량과 임대 사용 물량으로 구분하였다. 아울러 재질에 따라서 플라스틱, 목재, 금속으로 구분하였다. 조사 대상 업체의 범위는 원칙적으로 우리나라 산업 현장에서 파렛트를 생산하고 있는 모든 업체이다. 조사 대상인 업체의 범위를 기본적으로 통계청에서 제공하는 표준산업분류코드(KSIC)에 근거하여 재질, 규모 및 지역 관점에서 분류하여 처리하였다. 그러나 금속 및 종이 재질 업체에 대한 조사는 다소 미흡한 수준이었으며, 목재 재질 업체에 다소 편중된 조사가 이루어졌다.

• Journal of the Korean Wood Science and Technology
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• v.31 no.4
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• pp.1-7
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• 2003

Anatomical and physical characteristics of damaged wood by forest fire and sound wood of Pinus densiflora were examined. Granular substances were found in resin canals, epithelial cells and ray parenchyma cells of damaged wood, but the other distinctive marks of wood structure in damaged wood were not observed. Damaged wood showed slightly higher relative crystallinity in outermost growth ring than sound wood. Green moisture content and water absorptions both in tangential and radial sections of damaged wood were lower than those of sound wood. There were no significant differences in shrinkage, swelling and basic density between damaged and sound woods.

• Journal of Korean Society of Forest Science
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• v.7 no.1
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• pp.45-49
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• 1968

This experiment was carried out to study moisture contents including in the woody parts of standing Pitch Pine trees. The moisture measuring samples were made from the parts of root, branch, top, sapwood and heartwood of test trees. The test trees and average moisture contents measured from the parts of trees are as table (1) and (2). According to the results this study may be concluded as followings. 1) In the winter felled Pitch Pine trees highest moisture contents are shown in the top wood but lowest in the heartwood among the parts of tree. 2) In comparing moisture contents showing between two parts of tree, significant differences are show between top or heartwood and other parts but between branch or sapwood and root are not shown. 3) As general there is no significant variation in moisture contents of root, sapwood and heartwood among the test trees but branch wood is shown considerable variation.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.90-95
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• 2004

Pitch pine (Pinus rigida) has been planted in Korean forests for several decades, primarily for erosion control and use as a fuel supply. To enhance its value, and especially potential use as lamina for structural glued laminated timber (glulam), log quality and lumber yield of pitch pine were evaluated in this study. Trees from pure pitch pine stands with an average diameter at breast height of 32 cm were felled and bucked into 3.6m long 15 cm minimum butt-end diameter logs. Over 80% of the logs were classified to No.2 or No.3 visual grade group. Upon sawing total lumber yield was 55.2%, 39.9% for structural glulam lamina, 7.2% for louver, and 8.1% for miscellaneous use. The final lumber yield for manufacturing structural glulam, after cross-cutting to eliminate knots and finger jointing, was only 15.3%. To enhance this manufacturing yield requires that the rate of knot-included lumber used as lamina be raised. However arrangement of the knot-included lamina, whose mechanical properties need to be accurately evaluated, must be optimized to minimize any reduction to the structural glulam strength. The log quality and lumber yield of pitch pine evaluated in this study are expected to facilitate proper planning for wood product manufacture in the Korean lumbering and glulam industrial field, which has not previously dealt with this species.

• Survey Research
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• v.9 no.1
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• pp.1-22
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• 2008

Telephone directories ille still being used as the sampling frame in almost all fixed-line telephone surveys in Korea, causing potentially serious coverage error. RDD (random digit dialing) sampling is an obvious alternative to solve the problem. The aim of this paper is twofold: 1) proposal of RDD methodology suitable to the telephone system of Korea and 2) the identification of socio-demographic and socio-psychological differences between listed-number and unlisted-number respondents. Major findings of RDD telephone survey conducted experimental]y are as follows. 1) Population coverage by telephone directories is 60% or less. 2) Unlisted-number households have statistically larger income compared to listed-number households. 3) Unlisted-number households have smaller family size compared to listed-number households. 4) Unlisted-number respondents are more sensitive about confidentiality, leaks, 5) Unlisted-number respondents are more liberal compared to unlisted-number respondents. These facts suggest that directory-based telephone surveys tend to be biased in socio-economic aspects.

• The tire
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• s.84
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• pp.7-9
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• 1979

본고는 일본고무보지신문사에서, 장래의 원료고무에 대한 문제점을 조사한 것으로, 첫째, 원료고무에 대해서 현재 어떠한 문제점이 있는가, 앞으로 어떠한 다소재의 대체연구를 할 것인가. 둘째, 앞으로는 어떠한 특성의 원료고무를 희망하고 있는가의 두 가지 문제에 대해서 설문한 각종문제점을 종합한 것이다.<편집자주>