• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.263-272
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• 2003

Various types of geosynthetics have been manufactured and their applications are rapidly extended disregarding unreliable lifetime, chemical and biological persistence and puncture resistance. Puncture resistance of geosynthetics in earth structures and liner systems has been a critical issue to be improved. In this paper, comparative studies were made on a puncture resistance of various geosynthetics that were used to a liner system. Two types of puncture tools and rubles and gravels were used to generate punctures on geosynthetics. From the results it is shown that types of puncture tools affect puncture resistance of materials significantly and puncture forces were irregular depending upon puncture tools and materials.

• Composites Research
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• v.21 no.5
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• pp.23-30
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• 2008

Stab threats using sharp edged or pointed Instruments could be easily encountered by police officers or soldiers. In this study, the shear thickening fluids (STF) was impregnated into Kevlar fabrics to improve the stab protection and the resistance of STF impregnated Kevlar fabrics was experimentally investigated. The puncture and cut resistance were tested using a drop test machine withspike and knife indenters fabricated based on the National Institute of Justice (NIJ) standard. The STF was filled with spherical $SiO_2$ particles having an average diameter of 100nm, 300nm, and 500nm. The effect of particle size on puncture and cut resistance of STF impregnated Kevlar fabrics was also investigated. The measured impact load histories showed that STF impregnation into fabric leads to withstand higher peak loads than that of neat fabrics under spike test. The test results showed that Kevlar impregnated with STF exhibit remarkable improvements in puncture resistance while it is slightly influential on the cut resistance. Specifically, particle size is the one of the dominant factors controlling fabric resistance to puncture under spike impact test.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.11-17
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• 2004

This study focused on the protection effects of geosynthetics installed on HDPE to resist against puncture loads. The study was conducted by a model test with various types of puncture loads created by different shapes of tools. The puncture resistance of geosynthetics installed as a protective material on HDPE is varied depending on the sizes of geosynthetics and types of puncture loads. In this study, it was found that the protection effect far all kinds of geosynthetics when a truncated cylindrical shape of puncture tool is used is lower than others. Also, geocomposite has the most excellent protection effect against all types of puncture loads.

• The Korean Journal of Pain
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• v.1 no.2
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• pp.203-206
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• 1988

Evaluation of inadvertent dural puncture occuring among 308 epidural blocks done for the relief of pain from various conditions was performed. Dural puncture was suspected in 5 out of 308 epidural bloks. (1.6%) Aspiration of CSF was negative in 3 cases in which dural puncture was suspected only after developing spinal anesthesia. Of the 3 negative CSF aspirations, one case had a history of laminectomy. Adhesions of the adjacent tissues might result in the loss of flexibility and a decrease in potential epidural space which might cause dural tearing during injection and subarachoid injection of the local anesthetic followed by high spinal anesthesia. In another case, the needle tip was obstructed by tissue which led to negative aspiration of CSF and failure to feel loss of resistance. The second injection at the same site may cause subarachnoid injection of the local anesthetic through the previously perforated dura mater and in turn, lead to spinal anesthesia. In the last case, there was no reason to suspect dural puncture since the loss of resistance plus air rebound were definite and aspiration of CSF was negative, but dural puncture was suspected after the patient developed spinal anesthesia.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.43-47
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• 2004

We have been using Moisture Barrier Bags for dry packing of semiconductor packages to prevent moisture from absorbing during shipping. Moisture barrier bag material is required to be waterproof, vapor proof and offer superior ESD (Electro-static discharge) and EMI shielding. Also, the bag should be formed easily to the shape of products for vacuum packing while providing excellent puncture resistance and offer very low gas ＆ moisture permeation. There are some problems like pinholes and punctured bags after sealing and before the surface mount process. This failure may easily result in package pop corn crack during board mounting. The bags should be developed to meet the requirements of excellent electrical and physical properties by means of optimization of their raw material composition and their thickness. This study investigates the performance of moisture barrier bags by characterization of their mechanical endurance, tensile strength and through thermal analysis. By this study, we arrived at a robust material composition (polyester/Aluminate) for better packing.

• The Korean Journal of Pain
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• v.22 no.2
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• pp.163-166
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• 2009

The superiority of air versus saline for identifying the epidural space remains unestablished. Epidural anesthesia using a loss of resistance technique (LORT) with air is associated with increasing complications of dural puncture-induced headaches and neurological and hemodynamic changes. Here, we described a case of pneumocephalus with a large amount of air that was accompanied by severe headache and nuchal and chest pain occurring after epidural block using LORT with air for combined spinal-epidural anesthesia.

• The Korean Journal of Pain
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• v.22 no.2
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• pp.158-162
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• 2009

Background: The loss of resistance (LOR) method is most commonly used to identify the epidural space. This method is thought to rely on the penetration of the ligamentum flavum. Unfortunately the exact morphology of the ligamentum flavum is variable at different vertebral levels. Especially, it has been pointed out that the lower cervical ligamentum flavum may be discontinuous in the midline in up to 50% of patients. Thus, the LOR method may be inaccurate to confirm the cervical epidural space. The aim of this study is to determine which method is the safest and most exact for confirming the cervical epidural space. Methods: 100 adult, chronic renal failure patients who were undergoing an arteriovenous bridge graft for hemodialysis at the upper arm under cervical epidural anesthesia were recruited for this study. During the cervical epidural puncture, we identified the cervical epidural space by subjectively feeling the resistance with using a finger just through the ligamentum flavum, and we also used the drip infusion method, the loss of resistance method using air, and the hanging drop method. By using 5 grades, we classified the extent of whether or not the techniques were effective. Results: Using the drip infusion method, we identify the epidural space in all the patients as ＋/＋＋ grade. The catheter insertion method was also successful in identifying those epidural spaces over a ${\pm}$ grade. The pseudo LOR was over ${\pm}$ grade in 47 patients. Conclusions: The combined LOR/hanging drop with drip infusion method is useful for confirming the cervical epidural space.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.142-143
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• 2006

Combinatorial methods are being used increasingly to develop the next generation of polymers, coatings and adhesive formulations. Allied to this approach, a new genre of measurement and characterization methods are emerging. These characterization techniques are required to handle and take measurements from small samples. This has led to a number of uses for this technology which usefully fall between convention test specimen and micro- or nano-scale test methods. A versatile measurement platform will be presented which can offer useful indentation, puncture, compression, adhesion and scratch resistance data for a wide variety of material types and that continues to develop and evolve in capability.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.7-11
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• 1986

Nine Korean local cultivars and 34 PI lines of pepper were tested for resistance to anthracnose (Colletotrichum dematium). Red ripe fruits were harvested, punctured and inoculated by spraying and dropping a conidial suspension of Colletotrichum dematium. Resistance was evaluated by measuring the diameter of ripe rot lesions developed on and around the puncture. The results obtained are as follows : 1. PI 201232, PI 224451, PI 257044, PI 257119, PI 257099, PI 224433, PI 244668, PI 257102, PI 173877, Namji, Cheongryong, and Seodong were the least diseased and considered to be resistant. 2. PI 241670, PI 244670, and PI 224423 were the most diseased and considered to be susceptible. 3. Others were in between the two extremes and considered to be intermediate.

• The Korean Journal of Pain
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• v.10 no.1
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• pp.73-76
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• 1997

Background : Epidural anesthesia is now accepted as a popular technique for pain relief and anesthesia. However, accidental dural puncture may occur during placement of the epidural needle. This study was undertaken to evaluate difference of the epidural depth between parturients and non-parturients. Method : Eighty non-parturients receiving epidural anesthesia were assigned to group I, and eighty parturients whose body weight had not yet increased over 15 kg from pregnancy were assigned to group II. With patients in lateral decubitus position, 18 guage Tuohy needle was punctured by approaching at $L_{3-4}$ interspace. Epidural space was identified using loss-of-resistance to air technique. Result : Epidural depth was 4.18 cm and 4.25 cm in group I and group II respectively. There was no significant statistical difference in body mass index(BMI) and ponderal index(PI) (p<0.05), nor in epidural depth between the two groups. Conclusion : Epidural needle need not be placed deeper in parturients than in nonparturients.