• Carbon letters
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• v.6 no.4
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• pp.248-254
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• 2005

Silver impregnated activated carbon fibers were post-modified using hydrochloric acid. Adsorption behaviors, SEM morphologies, and functional groups for the silver impregnated ACFs were compared with those of post-modified ACFs. Adsorption isotherms were used to characterize $S_{BET}$, the pore structure and volume of silver-activated carbon fibers (ACFs) before and after acid post-treatment. In order to the reveal the causes of the differences surface states after the samples were washed with hydrochloric acid, outer surface and pore structure were investigated by SEM. And the type and quality of various functional groups were studied from FT-IR spectra and Boehm titration method. Finally, the quantitative properties in silver contents were also examined by EDX spectra.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.401-406
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• 1988

Various types and huge volume of information such as process instructions, work-in process and parametric data are created in a wafer fabrication process and should be provided to personnels inside or outside the facility. This article describes design criteria and functional description on the information system for small-scale wafer fabrication process to accomplish paperless fab and to support efficient fab management.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.311-312
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• 2023

In this study, porous concrete with improved functionality was developed by using superabsorbent polymer (SAP) to provide rooting space for plants. The depth of settlement and mass change according to the substitution and addition rate of SAP were determined by investigating the functional performance of SAP and the volume change upon saturation. Test results indicated the depth of penetration settlement increased as the substitution rate of SAP increased, but the mass change could not be confirmed as the addition rate of SAP increased. The instability of the specimens due to the excessive volume change of SAP, as well as the osmotic pressure phenomenon according to the pH concentration, were identified as the cause. Therefore, future studies are needed to investigate the appropriate substitution and addition rate of SAP, as well as to reduce the osmotic pressure phenomenon according to the pH concentration, which would contribute to the improvement of the functional performance of vegetation concrete.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.34-43
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• 1994

It is well known that the adsorption character of activated carbon is dependent on the specific surface area and pore volume, but the relationship between the surface-chemical structure and the adsorption character has not been studied very often. The purpose of this study is to investigate the effect of the acidic surface functional groups of activated carbon and the adsorption characteristics of low concentration phenol. So three types of activated carbons and four different treatments were introduced to this isotherm experiment. These treatments were nontreatment, 1N $HNO_3$ treatment, 6N $HNO_3$ treatment, $H_2O_2$ treatment. The conclusions of this study are as followings. If the initial concentration of phenol is high as 5mg/l, the adsorption is dependent on the specific surface area. If the initial concentration of phenol is low as $100{\mu}g/l$, the adsorption is dependent on the average pore volume. The acidic surface functional groups prevent the adsorption of phenol molecules to activated carbon. And the adsorbed amount decreases more for $HNO_3$ treatment than for $H_2O_2$ treatment and more for concentrated $HNO_3$ treatment than for dilute $HNO_3$ treatment.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.11-21
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• 2013

PURPOSES: As pavement generally provides service shorter than an expected life cycle, maintenance cost increases gradually. In order to help extending the service life and reduce maintenance cost, a new multi-functional composite pavement system is being developed in Korea. METHODS: This study is a part to develop the multi-functional composite pavement and is to investigate the mechanical performances of fiber-reinforced lean concrete for pavement subbase. The inherent problem of fiber reinforced concrete is dispersion of fibers in concrete mix. This study additionally evaluated fiber dispersion characteristics with respect to different fiber types. RESULTS: From the test results, the compressive strengths of the concretes satisfied the required limit of 5MPa at 7days. The standard deviation of the measured number of fibers were lower in the order of nylon, steel fiber and polypropylene. CONCLUSIONS: Reject ash was shown to be satisfactory as a replacement material to Portland cement in lean concrete base. The fiber volume fraction is suggested to be 0.4% even though the fracture toughness did not vary significantly with respect to fiber types. However, fracture energy absorbed up to complete failure increased with the increased fiber volume fraction increment.

• The Korean Journal of Nuclear Medicine
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• v.37 no.4
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• pp.207-218
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• 2003

Myocardial perfusion imaging has been increasingly used to provide prognostic data and guidance on the choice of appropriate management of patients with known or suspected coronary artery disease. The electrocardiogram gated myocardial SPECT program is corning into wide use with an advent of $^{99m}Tc-labeled$ tracers and an improvement of SPECT machines. The gated technique permits measurement of important cardiac prognostic indicators without any further discomforts or radiation burden in patients underwent standard myocardial perfusion SPECT. In addition, gated study significantly improves diagnostic yield by reducing the number of borderline interpretations and could find myocardial stunning and viable myocardium. Gated single photon emission computed tomography (SPECT) imaging allows the automated calculation of end-diastolic volume, end-systolic volume, ejection fraction, myocardial mass and the assessment of regional wall motion and thickening, and it have dramatically improved assessment of coronary artery disease in routine nuclear practice. This allows the simultaneous assessment of both perfusion and function within the same acquisition, and serves as a cost-effective technique for providing more diagnostic data with fewer diagnostic tests. Because the diagnostic and prognostic power derived from knowledge of left ventricular function can be added to that provided by assessing myocardial perfusion, gated SPECT imaging has rapidly gained widespread acceptance and is now used on a routine clinical basis in a growing number of laboratories, including South Korea. The gated SPECT technique for measurement of left ventricular parameters has been validated against a variety of well established techniques. In this work, overview of gated myocardial perfusion SPECT focus on functional parameters is presented.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.219.2-219.2
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• 2011

The oxyfluorination effects of electrospun carbon nanofibers (OFACFs) were investigated for $CO_2$ storage. Carbon nanofibers were prepared form poly acrylonitrile / N,N-dimethylformamide solution through electrospinning method and heat treatment. Chemical activation of carbon nanofibers were carried out in order to improve the pore structure. And the surface modification of activated carbon nanofibers was conducted by oxyfluorination to improve the $CO_2$ storage on effect of introduced functional groups. The samples were labeled CF (electrospun carbon nanofiber), ACF (activated carbon nanofibers), OFACF-1 ($F_2:O_2$ = 3:7), OFACF-2 ($F_2:O_2$ = 5:5) and OFACF-3 ($F_2:O_2$ = 7:3). The functional group of OFACFs was investigated by x-ray photoelectron spectroscopy analysis. The specific surface area, pore volume and pore size of OFACFs were calculated and pore shape was estimated by the BET equation. Through the adsorption isotherm, the specific surface area and pore volume significantly decreased by oxyfluorination.

• Transactions on Electrical and Electronic Materials
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• v.3 no.1
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• pp.9-13
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• 2002

In this work, the surface of inorganic fillers were modified with some functional groups such as stearic acid, aliphatic long chain, vinylsilane and aminosilane to control the interaction between inorganic fillers and polymer matrix. Ethylene-vinyl acetate copolymers (EVA) with various amount of vinyl-acetate and copolyether-ester elastomer were used as polymer matrix. The addition of inorganic fillers increases flame retardancy, but results in steep drop of electrical and mechanical properties, which may be caused by the defects in the interface between organic/inorganic hybrid composites. The hybrid composites are found to show better mechanical properties and higher volume resistivities as inorganic fillers are well dispersed and have good adhesion with polymer matrix. Also, the most effective type of functional group coated on fillers depends on the chemical structure of polymer.

• Journal of Korean Neurosurgical Society
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• v.52 no.5
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• pp.435-440
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• 2012

Objective : The purpose of this study is to find the optimal stiffness and volume of bone cement and their biomechanical effects on the adjacent vertebrae to determine a better strategy for conducting vertebroplasty. Methods : A three-dimensional finite-element model of a functional spinal unit was developed using computed tomography scans of a normal motion segment, comprising the T11, T12 and L1 vertebrae. Volumes of bone cement, with appropriate mechanical properties, were inserted into the trabecular core of the T12 vertebra. Parametric studies were done by varying the volume and stiffness of the bone cement. Results : When the bone cement filling volume reached 30% of the volume of a vertebral body, the level of stiffness was restored to that of normal bone, and when higher bone cement exceeded 30% of the volume, the result was stiffness in excess of that of normal bone. When the bone cement volume was varied, local stress in the bony structures (cortical shell, trabecular bone and endplate) of each vertebra monotonically increased. Low-modulus bone cement has the effect of reducing strain in the augmented body, but only in cases of relatively high volumes of bone cement (>50%). Furthermore, varying the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies. Conclusion : The volume of cement was considered to be the most important determinant in endplate fracture. Changing the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies.

• Archives of Plastic Surgery
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• v.50 no.4
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• pp.422-431
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• 2023

Background Posttraumatic lymphedema (PTL) is sparsely described in the literature. The aim of this study is to propose a comprehensive approach for prevention and treatment of PTL using lymphovenous anastomosis (LVA) and lymphatic vessels free flap, reporting our experience in the management of early-stage lymphedema. Methods A retrospective observational study was performed between October 2017 and July 2022. Functional assessment with magnetic resonance lymphangiography and indocyanine green lymphography was performed. Patients with lymphedema and functional lymphatic channels were included. Cases with limited soft tissue damage were proposed for LVA, and those with acute or prior soft tissue damage needing skin reconstruction were proposed for superficial circumflex iliac artery perforator lymphatic vessels free flap (SCIP-LV) to treat or prevent lymphedema. Primary and secondary outcomes were limb volume reduction and quality of life (QoL) improvement, respectively. Follow-up was at least 1 year. Results Twenty-eight patients were operated using this approach during the study period. LVA were performed in 12 patients; mean reduction of excess volume (REV) was 58.82% and the improvement in QoL was 49.25%. SCIP-LV was performed in seven patients with no flap failure; mean REV was 58.77% and the improvement QoL was 50.9%. Nine patients with acute injury in lymphatic critical areas were reconstructed with SCIP-LV as a preventive approach and no lymphedema was detected. Conclusion Our comprehensive approach provides an organized way to treat patients with PTL, or at risk of developing it, to have satisfactory results and improve their QoL.