• 한국주조공학회지
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• 제29권2호
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• pp.64-69
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• 2009

In the present study the effect of cooling rate during solidification on the microstructural characteristics of Al-xAg (x = 31, 33, 35 at.%) in-situ binary eutectic composites has been investigated. To provide a wide range of cooling rate three different casting techniques, i.e. conventional casting, injection casting, and melt spinning have been used. The observed microstructure is very much dependent on the cooling rate. The fcc ${\alpha}$-Al and hcp $Ag_2Al$ phases exhibits an orientation of (111)Al//(0001)$Ag_2Al$, [1-10]Al//[11- 20]$Ag_2Al$. The microstructure of the melt-spun samples contains Widmanstatten structure resulting from solid-state transformation and nano scale two-phase structure resulting from solid-state phase separation. The microstructure of injection-cast samples contains eutectic structure and solid state phase-separated structure. On the other hand, conventional-cast samples exhibit a microstructure consisted of plate-type eutectic structure.

• Journal of Korean Neurosurgical Society
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• 제29권10호
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• pp.1309-1315
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• 2000

Objectives : We performed an in vivo experiment to investigate the effect of $^{166}Holmium$ and $^{166}Holmium$-chitosan complex($^{166}Ho$-CHICO) on the normal brain of rats and to determine the sublethal dose of $^{166}Ho$-CHICO. Materials and Methods : $^{166}Ho$ is a beta and gamma ray emitter. $^{166}Ho$-CHICO is a novel radio-pharmaceutical complex with chitosan to facilitate the transport of $^{166}Ho$ obtained from Korea Atomic Energy Research Center(Taejon, Korea). It is in acidic form and becomes gel state at alkaline pH. One hundred and seventy consecutive rats were divided into four groups : $^{166}Ho$ treated(n＝50), $^{166}Ho$-CHICO treated(n＝57), saline treated(n＝5) and chitosan treated(n＝5) groups. $^{166}Ho$ and $^{166}Ho$-CHICO were injected into the rat brain stereotactically with various doses of 0.1mCi/$20{\mu}l$, 0.2mCi/$20{\mu}l$, 0.3mCi/$20{\mu}l$, and 0.4mCi/$20{\mu}l$ using an automated microinjector. Nuclear imaging, histopathological and hematological studies were performed in 10 rats in each group at 1 day, 3days, 7 days, 1 month and 3 months after the injections. Results : An infiltration of inflammatory cells and necrotic changes were noted in $^{166}Ho$ treated group at 1 week after the injection. A wedge-shaped tissue defect due to necrosis, lined with infiltrated glial cells in $^{166}Ho$ treated group and a cystic defect lined with reactive astroglial cells in $^{166}Holmium$-CHICO treated group at 3 months after the injection were observed. $^{166}Ho$ alone without chitosan leaked out and caused necrotic lesion on the cerebral surface but $^{166}Holmium$-CHICO treated group did not show this feature. As the dose of $^{166}Ho$ increased, the mortality rates were also increased. The mortality rate of the $^{166}Holmium$-CHICO group was higher than the $^{166}Ho$ treated group at a dose of 0.4mCi/$20{\mu}l$/300g. There was no detectable radioactivity due to the leakage or extravasation from the injected site of the brain on the scintigraphy performed at 1 hour, 24 hours and 48 hours after the injection. There was also no detectable activity of $^{166}Holmium$-CHICO in other organs including spleen, liver and kidney. Conclusions : $^{166}Ho$-CHICO did not leak out to the critical cortical surface of the brain from the injection site and induced radiation changes of the parenchyma around the injection site without cortical damage. The sublethal dose of $^{166}Ho$-CHICO for the normal brain in rats was determined to be 0.2mCi/$20{\mu}l$/300g.

• 한국터널지하공간학회 논문집
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• 제23권6호
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• pp.503-516
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• 2021

자율형 초동소화 체계는 복합적 감지 기술 및 화재 위치별 정확한 타격을 위한 분사/제어 기술등에 대한 고도의 기술이 필요하다. 또한, 상황에 따라 유류화재에 대한 대응을 위해 폼(foam) 분사 기능이 포함하여야 한다. 다만, 단일 분사 모니터를 공용으로 사용할 시 청수와 폼(foam) 분사 특성이 상이하므로 정확한 화재 진압을 위해서는 분사궤적 및 거리에 대한 연구가 필요하다. 본 연구에서는 자율형 소화체계 구축을 위해 개발된 분사 모니터를 통한 폼 분사 특성 분석을 위해 실험적 연구와 수치해석적 연구를 복합적으로 수행하였다. 폼 분사에 대한 유동해석을 위해 OpenFOAM 해석 소프트웨어를 사용하여 모델링을 하였으며, 폼 특성은 일반적인으로 사용되고 있는 포소화약제 수성막포를 적용하였다. 폼 형태에 따라 분사압, 분사각에 따른 분사 거리 해석을 수행하였으며, 동시에 분사 실험을 통해 결과에 대한 검증 및 결과를 제시하였다.

• 분석과학
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• 제29권5호
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• pp.242-247
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• 2016

본 연구는 물휴지 중 메탄올 정량법을 확립 및 밸리데이션을 수행하고, 확립된 시험법을 인체세정용 물휴지에 적용하여 검증하는 것을 목적으로 하였다. 물휴지 중 메탄올 정량시험은 헤드스페이스/가스크로마토그래피/불꽃이온화검출기법(HS/GC/FID)을 사용하였고, ‘의약품 등 시험방법 밸리데이션에 대한 가이드라인’에 따라 밸리데이션을 수행하였다. 확립된 시험법에서 메탄올의 정량범위는 3~40 μg/mL로 나타났으며, 상관계수(R²) 0.999 이상의 직선성과 우수한 선택성을 나타내었고, 검출한계와 정량한계는 각각 0.36와 1.17 μg/mL로 나타났다. 검출범위 내 농도별 회수율을 시험한 결과는 100.67~110.17%를 나타났다. 정밀성시험 결과 메탄올 검출량의 상대표준편차(RSD %)는 1.83%로 2 % 이내의 결과를 나타났다. 물휴지 중 메탄올 시험법을 유통 중인 물휴지 20개 제품에 적용하여 검출량을 분석한 결과 20개 제품에서 0.00017 %~ 0.00156%로 나타나 검출허용한도 기준 내 적합한 것을 확인하였다.

• 한국응용과학기술학회지
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• 제38권2호
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• pp.368-377
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• 2021

본 연구는 방사선 형질전환 차조기와 백출복합물(차조기 복합물)이 퇴행성관절염 관련 매개체에 미치는 영향을 확인하고자 MIA(monosodium iodoacetate)로 퇴행성관절염을 유도한 랫드로 평가하였다. 차조기 복합추출물을 2주 동안 25, 50, 100 mg/kg/day의 용량으로 경구 투여하고 랫드의 우측관절 내 공간에 MIA를 주입한 후 동일 용량을 4주 동안 지속 투여하였다. 이후, 혈청 바이오마커와 무릎 관절 분석의 형태학 및 조직병리학적 분석에 기초한 치료 효과를 평가하였다. 대조군 랫드와 비교하였을 때 차조기 복합추출물은 혈청 내 염증 및 골 대사 마커(TNF-α, MMP-3, COX-2, PGE₂, COMP, Aggrecan)의 생성량을 유의하게 감소시켰다. 이와는 반대로 연골 흡수 매개체인 CTX-2 생성을 증가시켰으며, 방사선 형질전환 차조기는 무릎 연골과 활막을 효과적으로 보존하였다. 그 결과, 차조기 복합물은 퇴행성관절염 증상을 개선하였다. 따라서, 차조기 복합물은 퇴행성관절염 관리를 위한 식품소재로 사용될 수 있다.

• 대한수의학회지
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• 제18권2호
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• pp.87-95
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• 1978

Election microscopic investigation were conducted on the mature mouse (B.W. about 25g) liver which was treated with Ginseng water extract during three, six and nine days respectivelly after carbon tetracholride injection into abdominal cavity. The results obtained were as follows: The liver cells of control group treated with carbon tetrachloride alone were restored slowly. The liver cells of experimental group treated with Ginseng water extract after carbon tetrachloride injection, however, were shown the appearance of well-developed ${\gamma}-ER$ and Golgi complex, marked aggregation of glycogen particles, and a number of large lipid droplets which are attached markedly with glycogen particles as compared to the control group. As these findings, it could be suggested that Ginseng gives an activation to restore the damaged liver cells.

• Archives of Plastic Surgery
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• 제44권3호
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• pp.234-237
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• 2017

Paraffinoma is a destructive complication of paraffin oil injection, usually associated with massive tissue destruction, thus requiring radical surgery and subsequent complex reconstruction. Although breast and penile paraffinomas have been widely described and their management is quite standardized, paraffinomas of the knee are still rare and only few case reports or small case series are available in the current literature. We describe the case of a 77-year-old man with a large paraffinoma of the right knee that occurred after self-injection of paraffin oil, 58 years before. He underwent wide surgical resection of the soft tissues overlying the knee and subsequent two-stage reconstruction by using acellular dermal matrix and, after 20 days, split-thickness skin grafts. Follow-up after 16 months showed no signs of skin ulcerations or inflammation, with an overall improvement in function. Even though conventional flap reconstructions may be still useful, the authors believe that acellular dermal matrices represent a safe, reliable, and less invasive alternative for challenging soft tissue reconstructions even in elderly patients with multiple medical problems.

• 한국분말재료학회지
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• 제16권5호
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• pp.342-350
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• 2009

Development of nanoparticulate materials technology is essential to processing of highly functional nanoparticulate materials and components with small and complex shape. In this paper, the effect of particle size on surface roughness and shrinkage of sintered Fe-8 wt%Ni nanopowder components fabricated by PIM were investigated. The Fe-8 wt%Ni nanopowder was prepared by hydrogen reduction of ball-milled Fe$_2$O$_3$-NiO powder. Feedstock of nanopowder prepared with the wet-milled powder was injection molded into double gear shaped part at 120$^{\circ}C$. After sintering, the sintered part showed near full densified microstructure having apparently no porosity (98%T.D.). Surface roughness of sintered bulk using nanopowder was less than 815 nm and it was about seven times lower than 7 $\mu$m that is typically obtainable from a sintered part produced from PIM.

• 오토저널
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• 제25권4호
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• pp.74-82
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• 2003

Future emission legislation requirements especially the need for CO$_2$ reduction lead to more complex powertrain concepts with an increasing number of independent parameters to be calibrated. For gasoline engines concepts with variable valve timing, direct injection or variable charge motion are in development or already on production. Diesel engines with common rail systems offer a wide range of new injection strategies, the application of new exhaust aftertreatment systems leads to additional complexity. Furthermore a clear trend to highly sophisticated transmission concepts requires a perfect interaction of all powertrain components. While the higher complexity requires increasing test and development effort, the development duration is reduced significantly. Consequently, the potential of such systems cannot be fully utilised by traditional development and calibration approaches within the given timeframe. By introduction of intelligent methodologies f3r the calibration of modem powertrains the development becomes more efficient, faster and better in quality. However, even with standardised and automated calibration methods a differentiated brand-specific powertrain character has to be maintained comparable to a "handmade" calibration performed by highly experienced experts.

• 한국정밀공학회지
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• 제19권6호
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• pp.43-50
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• 2002

In the design of structure, the forces acting on tai structure are key parameter fur noise and vibration control. However, in the complex structure, the forces at the injection point on the structure cannot be measured directly. So, it is necessary to find out Indirect force evaluation method. In this paper, forces have been measured with In-situ vibration responses and system information. And, three existing techniques of indirect force measurement, vita. direct inverse. principal component analysis and regularization have been compared. This paper shows that multi-vibration responses are essential for talc precise estimation of the forces. To check these conditions, rotary compressor is adopted as test sample, because it is very difficult to measure the injection forces from internal excitation to shell. It alas also been obtained that relatively higher force is transmitted through three welding paths to the compressor shell. It shows a good agreement between direct and indirect force evaluation with curvature shell and plate.