• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.111-115
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• 2005

Recently, natural fibers draw much interests in composite industry due to low cost, light weight, and environment-friendly characteristics compared with glass fibers. In this study, mechanical properties were evaluated for two extreme cases of jute fiber orientations, i.e. the unidirectional yarn composites and the felt fabric composites. Samples of jute fiber composites were fabricated by RTM process using epoxy resin, and tensile, compression, and shear tests were conducted. As can be expected, unidirectional fiber specimens in longitudinal direction showed the highest strength and modulus. Compared with glass/epoxy composites of the similar fabric architecture and fiber volume fraction, the tensile strength and modulus of jute felt/epoxy composites reached only 40% and 50% levels. However, the specific tensile strength and modulus increased to 80% and 90% of the glass/epoxy composites. The main reason for the poor mechanical properties of jute composites is associated with the weak interfacial bonding between fiber and matrix. The effect of surface treatment of jute fibers on the interfacial bonding will be examined in the future work.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.7 s.262
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• pp.792-799
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• 2007

A newly developed cellular metal based on kagome lattice is an ideal candidate for multifunctional materials achieving various optimal properties. Intensive efforts have been devoted to develop efficient techniques for mass production due to its wide potential applications. Since a variety of imperfections would be inevitably included in the realistic fabrication processes, it is highly important to examine the correlation between the imperfections and material strengths. Previous performance tests were mostly done by numerical simulations such as finite element method (FEM), but only for perfect structures without any imperfection. In this paper, we developed an efficient numerical framework using nonlinear random network analysis (RNA) to verify how the statistical imperfections (geometrical and material property) contribute to the performance of general truss structures. The numerical results for kagome truss structures are compared with experimental measurements on 3-layerd WBK (wire-woven bulk kagome). The mechanical strength of the kagome structures is shown relatively stable with the Gaussian types of imperfections.

• Journal of the Korea Furniture Society
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• v.26 no.1
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• pp.1-11
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• 2015

This study shows how the plastic furniture design has developed in general and by contemporary auteurist designers. Plastic furniture design began with Mies van der Rohe's chairs produced with compression moldings, and was later successfully commercialized by Knoll and Herman Miller. Plastic undoubtedly played a significant role in giving modern furniture design its current status with its suitability for efficient mass-production. However, the expectations consumers have for designers have extended by the widespread internet accessibility along with the higher standards of the well-developed design industry, and now mass-production is no more the only key to appealing to those in need. Based on the information gathered from the process above, analyses were done on the works of various design artists in the current industry, which leads to certain suggestions that would help bring the plastic furniture design to the next level as a whole.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.10
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• pp.1467-1477
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• 2002

This study was investigated physical properties of stretch fabrics by KES-FB system to show suitable basic data to making skirts of excellent capacity and develop more organized basic skirt pattern by fitness evaluation. 1. The results of T. H. V.(Total Hand Value) were as followa: In the kind of blending fiber, cotton/spandex was more excellent than nylon/spandex and polyester/spandex, in the direction of stretch, one-way(weft inserted polyurethan yarn) polyester/spandex and cotton/spandex were higher than two-way(warp and wet inserted polyurethan yarn) polyester/spandes and cotton/spandex, two-way nylon/spandex was higher than one-way nylon/spandex. 2. The results of calculating the variance between sample stretch fabrics and Japanese s/s women's suit fabrics after standardizing were as follows: Stretch fabrics has 2 range of tensile, bending, shearing, compression, surface, thickness and weight as compared with Jpanese s/s women's suit fabrics. In the tensile property, one-way stretch fabrics were almost the same with Japanese s/s women's suit fabrics, only two-way polyester/spandex had+1～+2 range. In the bending, shear property, there was no difference between sample fabrics and Japanese s/s women's suit fabrics 3. In the total fitness of the skirt, nylon/spandex is the best in the fabrics and one-way stretch fabric is better than two-way strethch fabric.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.151-158
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• 2007

The static and dynamic behaviour of VGT and EGR systems has a significant impact on overall engine performance, fuel economy and exhaust emissions. This is because they define the state and composition of the air charge entering the engine. This work focused on the effect of the aperture ratio of VGT and EGR on the emission and flow characteristics under partial loads conditions. The investigation carried out using 2 liter PCCI 4 cylinder diesel engine with VGT and EGR. The result of this study shows that smoke increases with increasing EGR rate and NOx decreases with increasing EGR rate. It was also found that the residual gas contents greatly impact on soot emission under partial load condition. Finally, it can be concluded that VGT and EGR aperture ratio can greatly impact not only on soot and NOx but also air charging.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.1 no.1
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• pp.75-83
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• 1995

Traction is the treatment of choice for a small nuclear protrusion. The nucleus is soft and can be influenced by suction. Traction provides a method of improving on recumbency-the only effective treatment before traction was devised. The intention is to achieve rapid reduction by distraction the joint surfaces mechanically-a positive purpose-instead of merely avoiding the compression of the upright posture by putting the patient to bed and leaving him there. Recumbency, usually successful in the end, wastes an endless amount of the patient's time and money. Traction carries the further advantage of enabling the patient to be up and about, attending to his bussiness, during treatment. Traction brings the joint surfaces much farther apart than just lying in bed, a greater centripetal force acts on the protruded part of the nucleus. Traction has three beneficial effects; 1. Suction : a sub-atmospheric pressure induces a centripetal effect on the contents. 2. Distraction : increases the distance between the articular edges. X -rays have shown an increase in width of the joint of 2.5 mm. 3. Ligamentous tightening : the posterior longitudinal ligament tightens which then exerts centipetal force on a central protrusion.

• Journal of Korean Neurosurgical Society
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• v.30 no.5
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• pp.657-661
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• 2001

Intracranial giant aneurysms have been known to cause clinical signs and symptoms, either by rupture, compression of surrounding structures, repeated minor leakage, or cerebral ischemia due to thromboembolism. A giant aneurysm which manifests only a seizure disorder comprises relatively few contributions. The authors present a case of a giant, unruptured aneurysm solely presenting with generalized tonic-clonic type seizure in a 43-year-old man. Brain computed tomogram(CT) and 3-D CT angiogram demonstrated a huge calcified aneurysm at the bifurcation of right middle cerebral artery. Complete neck clipping and aneurysmectomy followed by uneventful neurologic recovery.

• Journal of Korean Neurosurgical Society
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• v.56 no.2
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• pp.141-145
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• 2014

Vertebral artery (VA) injuries usually accompany cervical trauma. Although these injuries are commonly asymptomatic, some result in vertebrobasilar infarction. The symptoms of VA occlusion have been reported to usually manifest within 24 hours after trauma. The symptoms of bilateral VA occlusions seem to be more severe and seem to occur with shorter latencies than those of unilateral occlusions. A 48-year-old man had a C3-4 fracture-dislocation with spinal cord compression that resulted from a traffic accident. After surgery, his initial quadriparesis gradually improved. However, he complained of sudden headache and dizziness on the 5th postoperative day. His motor weakness was abruptly aggravated. Radiologic evaluation revealed an infarction in the occipital lobe and cerebellum. Cerebral angiography revealed complete bilateral VA occlusion. We administered anticoagulation therapy. After 6 months, his weakness had only partially improved. This case demonstrates that delayed infarction due to bilateral VA occlusion can occur at latencies as long as 5 days. Thus, we recommend that patients with cervical traumas that may be accompanied by bilateral VA occlusion should be closely observed for longer than 5 days.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.78-83
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• 2007

A newly developed cellular metal based on kagome lattice is an ideal candidate for multifunctional materials achieving various optimal properties. Intensive efforts have been devoted to develop efficient techniques for mass production due to its wide potential applications. Since a variety of imperfections would be inevitably included in the realistic fabrication processes, it is highly important to examine the correlation between the imperfections and material strengths. Previous performance tests were mostly done by numerical simulations such as finite element method (FEM), but only for perfect structures without any imperfection. In this paper, we developed an efficient numerical framework using nonlinear random network analysis (RNA) to verify how the statistical imperfections (geometrical and material property) contribute to the performance of general truss structures. The numerical results for kagome truss structures are compared with experimental measurements on 3-layerd WBK (wire-woven bulk kagome). The mechanical strength of the kagome structures is shown relatively stable with the Gaussian types of imperfections.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.97-102
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• 2005

The procedure of semi-solid forming is composed of heating a billet, forming, compression holding and ejecting step. There are several methods to heat a billet during semi-solid forming process such as electric heating and induction heating. Usually in semi-solid forming process, induction heating has been adopted to achieve more uniform temperature of semi-solid material. Although induction heating is better method than any others, however, there is still difference of temperature between internal part and surface part of semi-solid material. Worse yet, in case of high liquid fraction of semi-solid material, liquid of the billet will flow down though solid of the billet still remains, which is very difficult to handle. In the present study, induction heating of semi-solid material with compulsive surface cooling has been performed to obtain uniform distribution of temperature. Distribution of temperature of the billets was measured and compared with that of conventional distribution of temperature. By this new induction heating method, not only temperature over the whole billet become uniform, but also control of temperature is possible.