• 한국재료학회지
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• 제28권5호
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• pp.279-285
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• 2018

Graphene is an interesting material because it has remarkable properties, such as high intrinsic carrier mobility, good thermal conductivity, large specific surface area, high transparency, and high Young's modulus values. It is produced by mechanical and chemical exfoliation, chemical vapor deposition (CVD), and epitaxial growth. In particular, large-area and uniform single- and few-layer growth of graphene is possible using transition metals via a thermal CVD process. In this study, we utilize polystyrene and boron oxide, which are a carbon precursor and a doping source, respectively, for synthesis of pristine graphene and boron doped graphene. We confirm the graphene grown by the polystyrene and the boron oxide by the optical microscope and the Raman spectra. Raman spectra of boron doped graphene is shifted to the right compared with pristine graphene and the crystal quality of boron doped graphene is recovered when the synthesis time is 15 min. Sheet resistance decreases from approximately $2000{\Omega}/sq$ to $300{\Omega}/sq$ with an increasing synthesis time for the boron doped graphene.

• 대한안전경영과학회지
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• 제4권4호
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• pp.137-146
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• 2002

In order to investigate the effect of irradiation by $^{60}Co-\gamma$rays as well as the e thermal treatment on the dielectric deterioration in ethylene propylene rubber, insulating material for electric cables used in atomic power plants, charging discharging current, residual built- up voltage and dielectric properties are measu discussed in this study. Variance in the characteristic of relative dielectric constant as a function of tem was observed in relatively high dose of irradiation. Since glass transition tem appeared at tens of degree Celsius below zero, the characteristic is attributed orientation polarization. Dielectric loss is generally increased, with increasing d irradiation in the characteristic of dielectric loss as a function of temperature, No d loss by thermal treatment was observed. Dielectric resistance decreases with increa of irradiation in the characteristic of charging current as a function of temperature be considered that dielectric resistance seems to be recovered by thermal treatm characteristic of discharging current as a function of time in the specimen less ir become similar to that of the unirradiated, when thermal treated. A peak is shown residual built- up voltage as a function of time, and the corresponding time of the shorten as increasing dose of irradiation. It is also observed that the corresponding the peak is lengthened by thermal treatment.

• International Journal of Internet, Broadcasting and Communication
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• 제10권3호
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• pp.11-25
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• 2018

While being believed that decrypting any RSA ciphertext is as hard as factorizing the RSA modulus, it was also shown that, if additional information is available, breaking the RSA cryptosystem may be much easier than factoring. For example, Coppersmith showed that, given the 1/2 fraction of the least or the most significant bits of one of two RSA primes, one can factorize the RSA modulus very efficiently, using the lattice-based technique. More recently, introducing the so called cold boot attack, Halderman et al. showed that one can recover cryptographic keys from a decayed DRAM image. And, following up this result, Heninger and Shacham presented a polynomial-time attack which, given 0.27-fraction of the RSA private key of the form (p, q, d, $d_p$, $d_q$), can recover the whole key, provided that the given bits are uniformly distributed. And, based on the work of Heninger and Shacham, this paper presents a different approach for recovering RSA private key bits from decayed key information, under the assumption that some random portion of the private key bits is known. More precisely, we present the algorithm of recovering RSA private key bits from erased key material and elaborate the formula of describing the number of partially-recovered RSA private key candidates in terms of the given erasure rate. Then, the result is justified by some extensive experiments.

• 대한기관식도과학회지
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• 제6권1호
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• pp.21-28
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• 2000

Background:Subacute necrotizing lymphadenitis or Kikuchi's disease is unknown ethiology and self-limiting process. This disease predominantly affects young women age but rarely affects pediatrics, and usually manifests as lymphadenopathy and fever. Even though this disease is self-limited, benign process, many cases are misidentified as malignant lymphoma. The purpose of this study is to report the clinicopathologic finding, radiological finding and many labolatory test and to compare with characteristics of adult patients in this disease. Meterial and Methods:We reviewed 27 pediarics patients with subacute necrotizing lymphadenitis by excision biopsy or fineneedle aspiration cytology.Result:The most common symptomes were palpation of cervical lymh node(88.9%) and fever(66.7%). The common site of the involvement was cervical lymph node. The multiple involvement was 93% and bilateral involvement was 59%. Leukopenia(52%) and elevated erythrocyte sedimentation rates(93%) appeared in abnormal laboratory data. Microscopically, the characteristic finding was the wide area of florid nuclear dusts engulfed by histiocytes and well-circumscrbed area with eosinophilic fibrinoid material. There was a striking degree ofkaryorrhexis and an absence of granulocyte with paucity of plasma cell. All patients recovered with the conservative treatment and there was no specific complication and recurrence. Conclusion : We reviewed pediatric patients with this disease. Characteristics of this disease inpediatric patients were similar to adult patients.

• 한국분말재료학회지
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• 제15권2호
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• pp.101-106
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• 2008

The objective of the present study is to investigate the increase in the functional characteristics of a substrate by the formation of a thin coating layer. Thin coating layers of $Ti_5Si_3$ have high potential because $Ti_5Si_3$ exhibits high hardness. Shock induced reaction synthesis is an attractive fabrication technique to synthesize uniform coating layer by controlling the shock wave. Ti and Si powders to form $Ti_5Si_3$ using shock induced reaction synthesis, were mixed using high-energy ball mill into small scale. The positive effect of this technique is highly functional coating layer on the substrate due to ultra fine substructure, which improves the bonding strength. These materials are in great demand as heat resisting, structural and corrosion resistant materials. Thin $Ti_5Si_3$ coating layer was successfully recovered and showed high Vickers' hardness (Hv=1183). Characterization studies on microstructure revealed a fairly uniform distribution of powders with good interfacial integrity between the powders and the substrate.

• 한국임상수의학회지
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• 제12권1호
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• pp.897-904
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• 1995

Two giant pandas, which come from China have been roared in Yong-in Farmland zoo since 1994. One of them, which is female and 2 years old showed anorexia, mucous diarrhea and severe abdominal pain. It revealed neutrophilia and hypokalemia which suggested inflammation and loss of electrolytes by diarrhea. The mucous material contained intestinal mucoid epithelim which was infected Gram negative bacilli and infiltrated with neutrophils. The antibacterial therapy with nafcillin and ampicillin was not successful. Yersinia entrocolitica was implicated as a causative organism in the occurrence of bacterial enteritis. This organism had resistance to ampicillin, chlorampenicol, cefalothin, tetracycline, trimetoprim-sul-famethoxazole, erythromycin, gentamicin, kanamycin, carbanicillin and danofloxacin. It responded to the simultaneous administration of cefopherazone, flunixin-meglumine, physiological saline, Lactate Rainger's solution, sodium bicarbonate, KCL and vitamins and recovered after a period of 30days.

• 대한두경부종양학회지
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• 제21권1호
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• pp.10-14
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• 2005

Objectives: Various techniques of endoscopic thyroidectomy have been developed in thyroid resection since 1998 in the aspect of excellent cosmetic viewpoint. Of them, we evaluated our experiences and advantages of gasless axillary approach technique for resection of dominant thyroid nodules. Material and Methods: Twenty-nine cases of thyroid nodules were operated by the technique of gasless axillary approach during one year from December 2003 to December 2004. Twenty four patients underwent total lobectomy and five patients were partial lobectomy. Results: The operation time of first case took 300 minutes, however it became gradually shortened with case experiences down to 100-120 minutes. Pathologically, nodular hyperplasia was twenty cases, follicular adenoma five cases, papillary carcinoma three patients, and Hashimoto's thyroiditis one patient. There was no case of conversion to open thyroidectomy. Three cases of postoperative hoarseness were recovered spontaneously in 3 months. Hospital stay was four days for most patients. The cosmetic result was excellent without visible scar in anterior neck and chest. Conclusion: Endoscopic thyroidectomy via gasless axillary approach shows excellent result in cosmetic view point with hidden incision scar at axilla, and shorter hospitalization. However a question of longer operation time for dissection of the long plane over pectoral muscle is still remained.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제25권3호
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• pp.7-14
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• 2019

Purpose: The purpose of this research is to find out week and strong aspects in LEED categories based on achieved scores earned by LEED-HC(Healthcare) v.2009. Methods: The LEED-HC scorecards of 88 healthcare projects are analyzed. The analysis are focused on relationship between achieved scores, LEED categories and achieved levels. This relationship was presented by graphs and charts. Results: 1) Compare to LEED-NC, in LEED-HC, sub-categories related to public health are added. The scores are added in Energy Atmosphere and Indoor Environmental Quality. 2) Achieve scores in Sustainable Site are high and one in Energy Atmosphere and Indoor Environmental Quality are low at all levels. 3) Scores which was lost in Energy Atmosphere are recovered in Material Resource and Sustainable Site in order to keep its level. 4) Since most of scores in Energy Atmosphere are under EAc1 Optimize energy performance sub-categories, it is important to achieve more score in Optimize Energy Performance Sub-Categories to gain a higher level. Even if LEED-HC has more score in Energy Atmosphere, this is a hard to achieve scores in that categories. It is important to review Energy Atmosphere categories and its points for improvement. Implications: This study will provide basic database in order to establish Korean green building rating system for hospital.

• Smart Structures and Systems
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• 제24권2호
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• pp.157-171
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• 2019

This study investigated the effects of the geometric parameters of superelastic shape memory alloy (SE SMA) fibers on the pullout displacement recovering and self-healing capacity of reinforced cementitious composites. Three diameters of 0.5, 0.7 and 1.0 mm and two different crimped lengths of 5.0 and 10.0 mm were considered. To provide best anchoring action and high bond between fiber and cement mortar, the fibers were crimped at the end to create spear-head shape. The single fiber cement-based specimens were manufactured with the cement mortar of a compressive strength of 84 MPa with the square shape at the top and a dog-bone shape at the bottom. The embedded length of each fiber was 15 mm. The pullout test was performed with displacement control to obtain monotonic or hysteretic behaviors. The results showed that pullout displacements were recovered after fibers slipped and stuck in the specimen. The specimens with fiber of larger diameter showed better displacement recovering capacity. The flag-shaped behavior was observed for all specimens, and those with fiber of 1.0 mm diameter showed the clearest one. It was observed that the length of fiber anchorage did not have a significant effect on the displacement recovery, pullout resistance and self-healing capacity.

• 방사성폐기물학회지
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• 제21권1호
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• pp.9-22
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• 2023

Spin-off pyroprocessing technology and inert anode materials to replace the conventional carbon-based smelting process for critical materials were introduced. Efforts to select inert anode materials through numerical analysis and selected experimental results were devised for the high-throughput reduction of oxide feedstocks. The electrochemical properties of the inert anode material were evaluated, and stable electrolysis behavior and CaCu generation were observed during molten salt recycling. Thereafter, CuTi was prepared by reacting rutile (TiO₂) with CaCu in a Ti crucible. The formation of CuTi was confirmed when the concentration of CaO in the molten salt was controlled at 7.5mol%. A laboratory-scale electrorefining study was conducted using CuTi(Zr, Hf) alloys as the anodes, with a Ti electrodeposit conforming to the ASTM B299 standard recovered using a pilot-scale electrorefining device.