• Journal of the Korean Wood Science and Technology
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• v.21 no.3
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• pp.45-52
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• 1993

Surveyed results on the slope of grain and the twist of sawn lumber of Pinus koraiensis, Larix leptolepis, and Pinus densiflora were summarized as follows: 1. The slope of grain of Pinus koraiensis has a Z-grain in the stem axis. The slope of grain was found to be the lowest at near to the pith and then constantly increased. At the height of 0.2m from the base of stem. a cross section of 35 annual rings was found to have a repeatedly increasing and decreasing slope of grain and then constantly decreased. At the height of 1.2m to 7.2m from the base of stem, the slope of grain increased conspicuously until the 10th annual ring, after which it increased near to the bark with repeatedly increasing and decreasing trends. 2. Pinus densiflora has a S-grain in the stem axis. The lowest slope of grain was found at near to the pith, and the highest in the 10 to 35 annual rings from the pith. 3. Larix leptolepis has a S-grain. At the height of 3.2m from the base of stem, the big fluctuation of the slope of grain was found without any particular trend. 4. The slope of grain and the twist between natural and reforested timber of Pinus koraiensis were found to be almost the same trend in viewpoint of the annual ring. The maximum slope of grain of imported Siberian timber of Pinus koraiensis was found at the 10 annual rings, which was quite similar to that of native species in Korea, but the big difference of the twist was found at 140 annual rings. 5. The twist was little at the mature wood of reforested Pinus koraiensis and Siberians and the duplicated part of mature and juvenile woods of those. On the contrary, the twist was great at the duplicated part of mature and juvenile woods of Pinus koraiensis. 6. The twist of Larix leptolepis showed the S-direction which coincided with that of slope of grain. The twist was greatest at the part of juvenile wood and little at the duplicated part of mature and juvenile woods, and little difference of twist was found between mature and juvenile woods. 7. Siberian larix having a minimum slope of grain showed the lowest twist, and the twist at the duplicated part of mature and juvenile woods showed a middle level of both mature and juvenile woods' portions.

• The Research Journal of the Costume Culture
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• v.21 no.1
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• pp.1-16
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• 2013

This study analyzed the characteristics of Korean traditional plain weave excavated from Sang-go period to Joseon Dynasty. To do this, this study classified the Korean traditional plain weave into fiber types(cotton, hemp & ramie, plain weaved silk), analyzed and compared the thickness, twist type of yarns and density by times. First, in characteristics of cotton, the average and maximum density of Joseon Dynasty were higher than those of Goryeo, twist type was mainly s-twist and the density of warp was higher than that of weft. Second, the maximum density of hemp & ramie was found in era of Three Kingdoms of Korea. In common characteristics of hemp & ramie, twist type was mainly s-twist(sometimes non-twist) to the Three Kingdoms of Korea and was changed into non-twist from the Goryeo. The density of warp was higher than that of weft in common. Generally, the average density of ramie was higher than that of hemp. Third, in the characteristics of plain weaved silk, twist type was mainly non-twist(sometimes s and z-twist) from Sang-go period to Joseon Dynasty. Warp-faced ribbed tabby was excavated in Goryeo, the average density of warp-faced ribbed tabby was higher than that of other fiber types plain weave. Generally, in all fiber types, the density of warp was higher than that of weft.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.166-171
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• 1999

An overhead crane system consists of trolley, girder, rope, object, trolley motor, girder motor, and hoist motor. An analytic model which derived from the modelling of the overhead crane system is nonlinear model which includes the swing and the twist angle of the object. this model consists of the equation of motion for motors and object. If the swing angle and the acceleration of Z for the object are small, this model becomes a simple nonlinear model which doesn't include the swing and the twist angle of the object. From the results of computer simulation, the characteristics of an actual overhead crane system could be predicted by the simple nonlinear model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.349-355
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• 2017

Bending work using press dies involves bending a flat blank to a desired angle. The bending produces a flange (the bent part) and a web (the unbent part). The bending line will have a bending angle, and there is an inner and outer bending radius. The minimum inner radius size is determined by the material used. When the inner radius size is too small, there will be excess metal welding, which will cause a crack in the outer radius part. The outer bending radius size cannot be controlled by a bending punch and die block. Types of bending include V-bending, U-bending, O-bending, edge bending, twist bending, and crimping. Z-bending involves two bending lines, which are set on the upper side and under surface of the blank, respectively, and upward or downward bending is used. Z-bending is also called crank bending. Z-bending using this type of die structure will produce a standard inner bending radius. The standard size is the minimum bending radius that represents the angle radius of the bending punch. In industry, there is a need for a sharp edge shape with a very small size (R=0.2mm), but that is not possible when using bending punch and die block. The purpose of this research is to meet the need by development.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.299-304
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• 2003

Static mixer consists of a straight pipe of circular cross section into which individual elements are inserted to cut, fold, twist and re-combine the mixing fluid. The number of elements and their shape required in any application depend on the complexity of the mixing process. The objectives of this study are to develop a new static mixer and to perform the experimental investigation of pressure drop in order to evaluate the performance of the new one. The mixing fluid used is Glycerin. The pressure drop is measured using a hydraulic manometer and the correlation of Z-factor is suggested as a function of Re. The Z-factors of SSC and YNU mixer are about 40% lower than and 4% higher than that of the Sulzer one.

• Fashion & Textile Research Journal
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• v.5 no.3
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• pp.299-303
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• 2003

Some of historical textiles were analyzed to identify the imprinted textures on the metal remains of Haengyeup(a horse strap pendant) and Doja (a knife), which were excavated in the ruins of Hwangsung-dong, Kyungju city in the fifth century and textiles imprinted on the human bones that were excavated in the Pungnae 4th Area, Namyangju county in the sixteenth century. The results analyzed arc as follows ; It was confirmed that the imprinted textures of Haengyeup and Doja are white ramie since the structural characteristics of cellulosic bast fibers, partially projected long oval cross sections with large lumens and the imprinted textures of human bones are silk fabrics since the triangular cross sections of fibroin is showed. All of the textiles were designed in plain weaves. In the case of weaving yarns, the warp threads were thicker than the weft threads, that is, the imprinted textures of Haengyeup were measured by 1.35 mm for warp and 1.21 mm for weft, and the Doja by 1.16mm for warp and 1.11 mm for weft. In connection with the direction of the yarn twist, the Z-twist were observed in the imprinted textures of human bones, whereas it presented the S-twist in the case of Haengyeup and Doja. The warp yarns were mostly harder twisted than the weft yarns on the amounts of twist, that is, it was observed that the case of Haengyeup were amounted to 0.33 twists per centimeter for warp yarns and 0.25 twists per centimeter for weft yarns. Also it was showed 0.32 twists per centimeter for warp yarns and 0.26 twists per centimeter in the case of the textures of human bones. On the fabric counts, it was showed that the finer the yarns the higher the densities since it were $4.3{\times}5.1$ threads per sqaure centimeters and $7.6{\times}7.1$ threads per sqaure centimeters each in the case of Haengyeup and Doja, whereas it was $18.2{\times}33.7$ threads per sqaure centimeters in the case of the textures of human bones.

• Journal of the Korean Society of Costume
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• v.51 no.7
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• pp.35-47
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• 2001

This is a research about the fabrics attached to the remains of the Okjeon old tomb which was built around the early 5th century to the mid of the 6th century. Most of the remains have one kind of fabric attached to them, but there are cases where different sorts of fabrics are attached, where one kind is attached in layers, and there are also cases where the layer is made of different types of fabrics. Although they are made of warps and wefts with no twists, there can be an S twist on the weft or on both the warp and weft, and only one Z twist can be seen. There are 81 fabrics of plain weaved, one of transformed plain weaved and five 4-end complex gauze in these remains. The sparsest plain weaved fabric has the density of 7.4 strands/cm, while the most dense fabric has the density of 148.2$\times$129.1 strands/cm and 0.046$\times$0.061/mm thickness in thread. All the fabrics observed by SEM are hemp except one silk.

• Journal of the Korean Society of Costume
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• v.58 no.5
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• pp.153-165
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• 2008

The methods used in determining the weaving period of the textiles comprises not only radiocarbon dating but also discrimination of the motif and the textile structure. This study surveys the variation of the structure and the characteristics of the patterned textile of the Joseon dynasty to determine the weaving period. The number of twill gradually decreased in the Joseon dynasty while satin weave became more popular and the non-patterned twill almost vanished after 1600 A.D. The patterned plain weave was started to weave from the beginning of the Joseon dynasty but this has been shifted to twill, satin weave, floated weave, or the textiles with combined techniques more than 2 kinds after 1800 A.D. For the twist of threads, the number of the fabrics with Z-twisted thread in the warp and the non-twisted thread in the weft showed peak in 1600 A.D. and gradually decreased afterward. After 1600 A.D., the textile without twist became general trend.The satin weave started to appear with the 5-end satin in the beginning of the Joseon dynasty but the 8-end satin started to appear from the middle of 17th century and got more popularity with time. At the same period, the patterned textile on the ground of the satin weaved with the different techniques from the earlier period started to appear. The twist of the satin in the 1600 A.D. showed similar trends as twill, this general trend resulted from the fact that the non-twisted thread in the weaving became more popular with the time at that period.

• Korean Journal of Heritage: History & Science
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• v.51 no.4
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• pp.84-107
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• 2018

Cheommojik is a pile cloth, a type of textile whose surface is covered with short piles. The term chaedam was used during the late Joseon dynasty to refer to pile cloth rugs, while the terms yoongjeon, dantong and yangtanja were used in the early twentieth century. Various documents, newspaper articles and photographs confirm that pile cloth rugs were used by the general public as well as the royal family from the late Joseon dynasty onward, and that there were domestic manufacturers of such rugs at that time. This study investigated six pile cloth rugs that were produced after the late Joseon dynasty, five of which feature Persian knots made of cut pile, the other being made with the loop pile method. The cut pile rugs are rectangular in shape and measure between 72-98cm by 150-156cm; and they are decorated in the middle with patterns of butterfly, deer, and tiger or the ten longevity symbols, and along the edges with patterns composed of 卍 symbols. The ground warp of all six rugs are made from cotton yarn, while the ground weft is made of cotton yarn on three pieces, wool on one piece and cotton and viscose rayon. The ground weft yarn from four pieces are Z-twist yarn made with two or more S-twist cotton yarn. Four to six colors were used for the pile weft, all being natural colors except for red. Two or more S- or Z-twist yarn were twisted together in the opposite twist for the pile weft, with the thickness determining the number of threads used. Six or more weft threads were used to make the start and end points of the rug; and the ground warp ends were arranged by tying every four of them together. For the left and right edges, three or more threads were wrapped together into a round stick-like form, and the second and third inner ground warps from the edges were stitched on to the wrapped edge. For the loop pile, loops were made in the direction of the warp; the ground warp and the ground weft may have been made with cotton, the pile warp with wool yarn. An analysis of the components of three rugs was conducted to determine which types of animal hair were used for the pile weft. Despite some inconclusive results, it was revealed that goat hair and fat-tailed sheep hair were used, raising the possibility that various kinds of animal fur were used in the production of pile cloth rugs. The six rugs examined in this study are estimated to have been made between the late 1800s and the early 1900s. Although the manufacturer of the rugs cannot be confirmed, we concluded that the rugs were produced in Korea after referring to the documentation of the domestic production of pile cloth rugs during the aforementioned period and the form and placements of the patterns on the rugs.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.159-177
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• 2002

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle and the angular velocity of the air born phase and understand the control mechanism of the high-bar movement, the somersault, the double somersault, the double somersault with full twist. For this study seven well trained university gymnastic volunteered, Zatsiorky and Seluyanov(1983, 1985)'s sixteen segment system anatomical model was used for this study. For the movement analysis three dimensional cinematographical method(Arial Performance Analysis System : APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 5.1 graphical profromming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and angular velocity were defined. As a result of this study 1. As the rotation of the body increased in the air born phase the projection angle of the CM of the total increased, this resulted the increased of the max hight of the CM. 2. In three dimensional angular velocity the Z axis(vertical direction) projection angular velocity increased as the rotation of the body increased in the airborn phase, but the Y axis and the X axis projection angular velocity did not show significant differences. 3. As the rotation of the body increased in the air born phase the angular movement of the shoulder and the hip showed significant change. These movement act as the starter in the preparation phase. 4. The somersault angle, the twist angle, the tilt angle of the upper body related to the global reference frame in the releas phase the average somersault angle of the three types of high-bar movement was $57.7^{\circ}$, $38.8^{\circ}$, $39.7^{\circ}$, the average tilt angle was $-1.5^{\circ}$, $-5.4^{\circ}$, $-8.4^{\circ}$, the average twist angle was $13.4^{\circ}$, $10.6^{\circ}$, $23.3^{\circ}$. This result showed that the somersault with full twist had the largest movement.