• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.205-211
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• 2007

In this paper, foam-composite sandwich structures for EDM machine tool components such as column and column block designed by controlling stacking sequences and cross-sectional dimensions of the composite structures. The original column block is a box-shaped structure made of aluminum connecting a column and a Z-stage of the system. This research was focused on the design of efficient column block structure using a foam-composite sandwich structure which have good bending stiffness and damping characteristics to reduce the mass and increase damping ratio of the system. Vibration tests for getting damping ratio with respect to the stacking angle and thickness of the composites were carried out. Finite element analyses for static defection and vibration behaviour were also carried out to find out the appropriate stacking conditions; that is, stacking sequence and rib configuration. From the test and analysis results it was found that composite-foam sandwich structures for the microfactory system can be successful alternatives for high precision machining.

• Journal of Fashion Business
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• v.18 no.2
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• pp.148-165
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• 2014

The purpose of this study is to establish a theory about the necessary structure for knitwear design, and to propose it with the practical data through the actual development of a high value added knit structure. For this study, the market was conducted along with literature reviews on the existing studies and the relevant books about knit structures. The market research aimed at the products released in the spring/summer and fall/winter seasons of 2012-2013, focusing on brand for middle aged women. The utilization of the structure by item and the characteristics of knit design were studied. The research was conducted on S/S products in May and July, and F/W products in October and December. As a result of the market research, it was shown that the lightweight structures with permeability such as plain, lace, links and links, this is repeated and rib structure were frequently utilized during the S/S season, while double structures with good shape stability were greatly utilized during the F/W season. Also, during the F/W season, a cable structure and tubular jacquard that emphasized the volume or cubic effect were frequently used, and there were many jacquard structures where a change of color sense and motive were added. Concerning the knit structures development, the researcher designed the knit structure at the actual production site of the knit fashion. A total of 5 pieces of knit structures were developed by asking a professional for programming and knitting. To the developed structures, the study added a multi-gauged effect, herringbone transformation effect, 3-dimensional surface effect, color effects, geometric patterns, lace penetration effect, and soft surface effect in a water-drop shape. In addition, the structures had differences in the added values by mixing various structures and diversely expressing color sense on the knitting line. This study proposes the direction for 21st century knitwear product design, through the development of a high value added knit structure.

• Composites Research
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• v.35 no.2
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• pp.106-114
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• 2022

Carbon fiber-reinforced plastic, well known high specific strength and high specific stiffness, have been widely used in the aircraft industry. Mostly the CFRP structure is fabricated by lamination of carbon fiber or carbon prepreg, which has major disadvantage called delamination. Delamination is usually produced due to absence of the through-thickness direction fiber. In this study, three-dimensional carbon preform woven in three directions is used for fabrication of aircraft wing unit structure, a part of repeated structure in aircraft wing. The unit structure include skin, stringer and rib were prepared by resin transfer molding method. After, the 3D structure was compared with laminate structure through compression test. The results show that 3D structure is not only effective to prevent delamination but improved the mechanical strength. Therefore, the 3d preform structure is expected to be used in various fields requiring delamination prevention, especially in the aircraft industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.134-141
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• 2019

This paper is a study on design improvement of rotorcraft horizontal stabilizer. The rotorcraft horizontal stabilizer stabilizes the behavior of the pitch, yaw, etc. from the aircraft. Because of this role, horizontal stabilizers are a major component (Flight Safety Part) that affects flight safety on rotorcraft. However, when the rotorcraft was operated in domestic, cracks were found in the inner structure of the horizontal stabilizer and design improvement was needed. In this paper, we identified the two causes of the horizontal stabilizer crack defects through fracture analysis and structural analysis. The first is the tightening torque when the bolt is tightened, and the second is the lead-lag behavior of aircraft. In order to improve these two causes, bolt fastening method, flange structure and thickness were changed and composite ring was applied. In order to verify the design improvement, the structural analysis was performed and the structural strength was improved. Also Fatigue analysis of the internal structure (Rib 1) was performed and it was confirmed that the requirements were satisfied.

• Korean Journal of Social Welfare Studies
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• v.41 no.1
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• pp.85-118
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• 2010

This study aims to suggest an analysis method for the research on the transformation of welfare states. To this end, 'restucturization' and 'change inside the structure' were differentiated. The 'restucturization' indicates a fundamental change of the structure itself, while the 'change inside the structure' means the modification of elements inside the structure. If 'abolition', 'substitution'/'entrust' and 'introduction' occurred, the changes are considered the 'restucturization'. Then it is examined, how the competence of the public organizations for social security systems is changed after the 'restucturization'. On the basis of this evaluation measure, the changes of 'restucturization' are defined as 'public-oriented restucturization', 'private-oriented restucturization' or 'status quo'. For analyzing the 'change inside the structure', coverage, entitlement, the level and length of benefit, finance and delivery system were compared within each country. The current study applied this analysis method to the research on the transformations of social security systems of Great Britain, Sweden and Germany.

• Journal of the Korea Fashion and Costume Design Association
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• v.12 no.2
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• pp.131-138
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• 2010

The purposes of this study are for current manufacturing status of the formal knit slacks for the middle aged women. As for the methodology, five manufacturers specializing in formal knitwear brands were subjected to the study, to examine the current manufacturing status of the knit slacks for the middle aged women, by conducting interviews and questionnaire with patterner and designer. The questionnaire items are 20 ones including general questions on manufacturing of the knit slacks, questions on materials used in manufacturing, and on sewing. The results are as followings : First, as for the manufacturing structure of the knit slacks manufacturer, all manufacturers directly manufactured knit slacks in their own factory, and the manufacturing was comprised of 10% in woven slacks and 90% in knit slacks. Second, as for the type of yarn mostly used in fabric knitting for the knit slacks, wool was used mostly for F/W, and acrylic or Saint yarn for S/S. As for the types of knit, Milano rib stitch and Half Milano rib stitch were used for wool and acrylic knitting, and plain stitch was used for Saint yarn. As for the gauge, 12G and 14G were used, whereas 7G, 12G was used for Saint yarn. Repair requests of the knit slacks were mostly on the length of the pants, such as shortening hip circumference and crotch length, or widening waist and hip area. The study shows that the size of knit slacks did not fit the body type of customers.

• The Korean Journal of Pain
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• v.13 no.1
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• pp.97-100
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• 2000

Thoracic outlet syndrome (TOS) is a combination of signs and symptoms caused by the compression of the vital neurovascular structure at the thoracic outlet region. It may stem from a number of abnormalities, including degenerative or bony disorders, trauma to cervical spine, fibromuscular bands, vascular abnormalities and spasm of the anterior scalene muscle. CPT (current perception threshold) is defined as the minimum amount of current applied transcutaneously that an individual consciously perceives. It enables quantification of the hyperesthesia that precedes progressive nerve impairment, as well as hypoesthetic conditions. We experienced a case of thoracic outlet syndrome caused by fibrosis of anterior scalene muscle. The patient was a 30 years old woman with a 3 years history of numbness on the ulnar side, progressive weakness and coldness of both hand, tiredness in the left arm, nocturnal pain in the left forearm, and pain in the left elbow, shoulder and neck. Conservative treatment, stellate ganglion block, cervical epidural block, anterior scalene block and previous operation, including both carpal tunnel release, provided no remarkable relief to the patient. A left scalenectomy and first rib resection were performed by transaxillary approach and left cervical root neurolysis was done. After surgery, we measured CPT using neurometer and found conditions worsening in the opposite arm. We performed the same procedure on right side, and followed by CPT measurement. This case suggests that CPT is a useful measurement of recovery and progression of TOS.

• Composites Research
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• v.29 no.5
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• pp.315-320
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• 2016

Conventionally, composite aircraft structures are fabricated within autoclave at high pressure. However, autoclave process has several disadvantages including high curing costs and limitation of part size. Recently, out-of-autoclave (OoA) processes have been investigated in many studies to replace conventional autoclave process. A newly developed OoA prepreg, using conventional ovens, can significantly reduce the curing costs and produce autoclave-quality parts. Nevertheless, manufacture of void-free complex shape structure using OoA process presents significant challenges because of the low consolidation pressure. In this study, integrated skin-spar-rib composite part was fabricated using OoA prepreg. And cross-sectional macro- and micro-graphs of the part were examined in order to assess the possibility of replacing conventional autoclave process.

• The Research Journal of the Costume Culture
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• v.18 no.1
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• pp.109-117
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• 2010

Knit fabrics are created on diverse machines with diverse knit loops and conditions to make different patterns and fabric types. Dimensional modifications of knit fabrics can also be achieved by numerous methods such as different knit-loop structures, different types of yarns, or different finishing processes including heat setting, steaming, chemical treatment et cetera. This research develops and explores sophisticated three-dimensional knit fabrics by combining the several different knit stitches including rib and purl. This study focuses on 3D knit models created on modern electronic weft (flat V-bed) knitting machines which have capability of individual needle selection. Several samples of the 3D knitted fabrics are also examined in this research. This research furthermore suggests new types of knitted fashion garment made by using the interesting physical effects.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.41-51
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• 2018

In case of evaluating the bond stress of a void deck plate using a wire steel, there is no standard formula considering both the influence on the void and the type of the reinforcing bar. Therefore we proposed a model equation considered the bond characteristics of the void deck plate. A total of 46 specimens was carried out a direct pull-out test and the test variables were the presence of a void body, type of reinforcing bar, the inner cover thickness according to the location of reinforcing bars and bond region. As a result of the comparison between the steel bar and steel wire, the bond stress of the steel wire with the relative rib area of 0.071 is 4.5 ~ 28.58% lower than that of the steel bar with 0.092 and the bond stress reduction rate increases when the inner cover thickness is insufficient. In the case of the inner cover thickness of $1.7d_b$ and $2.7d_b$, the bond stress was reduced to 48.7 ~ 68.4%. In the inner cover thickness was $4.9d_b$ and $5.2d_b$, the bond stresses were equivalent to those of the solid specimens. It was confirmed that the average bond stress and strain were affected by the inner cover thickness. Therefore the predicted model for one module of the void deck plate is proposed and verified by considering the bond characteristics of the void deck plate.