• 한국결정성장학회지
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• 제16권3호
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• pp.127-131
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• 2006

세라믹소지에 발생하는 온도별 백화생성기구를 백화를 형성하는 양이온과 음이온을 분석하여 규명하였다. 백화가 발생된 세라믹 소지의 표면을 SEM과 EDS 분석을 하여 백화의 주 성분은 Ca와 S임을 확인하였다. 세라믹소지를 pH 7과 pH 10에서 각기 습식혼합 하였으며, 이때 여과된 액을 ICP와 IC 분석을 하여, 양이온 및 음이온 농도분석을 하였다. pH 7에서 제조된 세라믹 소지의 Ca 이온농도는 pH 10에서 제조된 세라믹소지의 Ca 이온농도의 8배 값을 보였으며, pH 10에서 제조된 세라믹소지는 $1100^{\circ}C$ 이상으로 소결된 소지에서도 백화가 발견되지 않았다.

• Macromolecular Research
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• 제13권1호
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• pp.54-61
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• 2005

We prepared temperature-sensitive liposomes (TS-liposomes) modified with a thermo sensitive polymer, such as poly(N-isopropylacrylamide) (PNIPAAm), to increase the degree of drug release from liposomes at the hyperthermic temperature. A PNIPAAm hydrogel containing TS-Iiposomes was also prepared to obtain a hydrogel complex at body temperature. In addition, a depot system for local drug delivery using the polymer hydrogel was developed to enhance therapeutic efficacy and prevent severe side effects in the whole body. The PNIPAAm-mod­ified TS-liposome was fixed into the PNIPAAm hydrogel having a high temperature-sensitivity. The release behavior of calcein, a model drug, from TS-liposomes in the PNIPAAm hydrogel was then initiated by external hyperthermia; the results indicated that sustained release as a function of temperature and time was caused by the thermosensitivity of the liposome surface and diffusion of the drug into the PNIPAAm hydrogel. Our results indicated that TS-liposomes in a PNIPAAm hydrogel represented a plausible system for local drug delivery.

• Corrosion Science and Technology
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• 제22권4호
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• pp.257-264
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• 2023

Ti-6Al-4V alloys are mainly used as dental materials due to their excellent biocompatibility, corrosion resistance, and chemical stability. However, they have a low bioactivity with bioinertness in the body. Therefore, they could not directly bond with human bone. To improve their applications, their bone bonding ability and bone formation capacity should be improved. Thus, the objective of this study was to improve the bioinert surface of titanium alloy substrate to show bioactive characteristics by performing surface modification using wollastonite powder. Commercial bioactive wollastonite powder was successfully deposited onto Ti-6Al-4V alloy using a room temperature spray process. It was found that wollastonite-coated layer showed homogeneous microstructure and uniform thickness. Corrosion resistance of Ti-6Al-4V alloy was also improved by plasma electrolytic oxidation treatment. Its wettability and bioactivity were also greatly increased by wollastonite coating. Results of this study indicate that both plasma electrolytic oxidation treatment and wollastonite coating by room temperature spray process could be used to improve surface bioactivity of Ti-6Al-4V alloy substrate.

• 한국안전학회지
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• 제22권4호
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• pp.13-19
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• 2007

An numerical method to estimate thermal diffusivity has been developed for one-dimensional unsteady heat conduction problem, when the temperatures are know at two positions in a semi-infinite body. Using the closed form solution which has already derived an explicit solution for the inverse problem for one-dimensional transient heat conduction using Laplace transform technique, we first estimate the surface temperature. The thermal diffusivity can be estimated by using the estimated surface temperature and measured temperatures, which include some uncertainties. The estimated surface heat flux and thermal diffusivity are found to be in good agreement with those of the experimented conditions. This method will be extended to the simultaneous measurement of thermal diffusivity and thermal conductivity.

• 한국전산유체공학회지
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• 제18권3호
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• pp.87-93
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• 2013

A computational study has been performed to examine the effects of catalytic walls on the stagnation region heat transfer. The boundary conditions for none, finite, and fully catalytic walls have been incorporated into a multi-block compressible Navier-Stokes solver. In the present study, both chemical and thermal non-equilibrium effects were included. The flows over a blunt body model were simulated by varying surface catalytic recombination rates. A full range of catalycities was explored in the context of a constant wall temperature assumption. Detailed information on species concentrations, temperature, and surface heat flux are presented. Comparison with available flight data of surface heat flux is also made.

• 항공우주시스템공학회지
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• 제16권6호
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• pp.90-98
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• 2022

EO/IR 위성에 탑재된 적외선 센서(IR Sensor)는 궤도환경에서 임무기간 동안 복사 에너지에 대한 센서 출력의 변화가 발생한다. 고품질 영상을 획득하기 위해 출력을 교정할 수 있는 주기적인 교정이 필요하며, 센서의 주기적이고 정밀한 교정을 위해 탑재체 내부에 흑체 시스템이 적용하였다. 우주 환경에서 사용되는 모든 시스템은 궤도환경에서의 목표 성능을 검증하기 위해 지상에서의 성능시험이 요구되고 있다. 흑체 시스템은 운용환경에서 목표 온도 범위에서 대표추정온도 오차와 흑체 표면온도균일도 성능의 시험적 검증이 요구되고 있다. 본 연구에서는, 궤도환경으로 우주배경복사 냉각이 모사된 열진공 시험을 통해 제안된 흑체 시스템의 대표추정온도 오차 교정 및 성능 검증을 진행하였다.

• Journal of Chest Surgery
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• 제2권1호
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• pp.105-114
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• 1969

This experiment was carried out to study the responses of cellular component of blood and bone marrow to cold and also the changes of coagulation during cooling. Forty-two mongrel dogs were subjected to hypothermia by ice-water surface cooling technique. Lowest body temperature ranged from 21-23 degree. Dogs were divided into 3 groups,Group I, 12 dogs: pentothal anesthesia for 3 hours, Group II, 20 dogs;hypothermic group and Group III,10 dogs;postsplenectomy hypothermic group. Results were summarized as follows: 1. Hemoglobin, hematocrit and red blood cell count significantly increased when animals were cooled, and increase was noted in similar magnitude among the animals of Group I. 2. White blood cell count extremely decreased after cooling and effect of splenectomy on white blood cell count was not apparent. No significant changes were seen among Group I. 3. Differential count of white blood cell when cooled showed relative increase of polymorphonuclear neutrophil and decrease of lymphocyte. 4. There was marked decrease of platelets when body temperature reached to 21-23degree and essentially. no changes was noted in Group I. 5. Clotting time, bleeding time, plasma prothrombin time, recalcification time, and fibrinolysis showed no significant changes when dogs were cooled. Clot retration and prothrombin consumption during hypothermia appeared to be poor. In Group II, bleeding time decreased after splenctomy and when body temperature was lowered, plasma prothrombin time, clot retraction, and prothrombin consumption decreased. Decreased bleeding time and poor clot retraction were noted in Group I. 6. It was found that megacaryocyte count decreased even though platelet count of peripheral blood markedly diminsished when animals were cooled. There was some tendency of erythroid hyperplasia noted during hypothermia.

• 한국산학기술학회논문지
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• 제15권2호
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• pp.603-608
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• 2014

항공기와 자동차 부품과 관련된 많은 제조업에서, 낮은 비중과 높은 강도에서 뛰어난 알루미늄 합금(Al2024)은 효과적으로 사용되었다. 가공소재의 표면거칠기 품위를 위한 정면밀링 가공기술은 이들 분야에서 적용되어 왔다. 챔퍼된 드로우 어웨이 타입의 인서트를 갖는 정면밀링 가공은 단지 이론적으로 완전한 평면을 생산할 수 있다. 그러나 그것은 절삭온도, 소성변형, 동적효과 등으로 인하여 불가능하다. 본 논문에서 실험적 연구는 검증된 고속가공이 가능한 정면밀링커터 바디를 사용하여 Al2024의 고속가공 후 표면거칠기를 개선하기 위하여 수행되었다.

• 대한환경공학회지
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• 제28권4호
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• pp.447-452
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• 2006

대형 수체의 수질 모델 검증 효과를 향상시키기 위하여 원격탐사 기술이 적용되었다. 인공위성 영상은 대형 수체의 넓은 표면을 한꺼번에 파악할 수 있으므로 모델의 보정 및 검증에 사용되는 관측 자료의 부족함을 보완할 수 있다. 이 논문은 2000년 4월 29일과 9월 4일에 촬영된 Landsat FTM+영상을 분석하여 팔당호 표층 수온 검증 연구를 제시하고 있다. 영상으로부터 계산된 수온과 모델의 표층 수온의 자료를 획득하여 3가지 방법으로 영상에 의한 수온과 모델의 결과를 비교하였다. 4월 29일 영상의 경우 모델 결과를 기준으로 오차율이 0.13이며 9월 4일에는 오차율이 0.04로 모델의 표층 수온이 영상으로부터 계산된 수온과 잘 일치함을 알 수 있다. 그러나 영상촬영 시점의 대기의 간섭을 고려하지 못한 것이 4월 29일 결과의 오차를 발생시킨 주요 원인으로 사료된다. 그러므로 정확한 수질자료를 얻기 위해서는 영상촬영 시점의 대기의 효과를 고려한 대기보정이 필요할 것이라 사료된다.

• 에너지공학
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• 제4권2호
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• pp.297-302
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• 1995

Ignition of a reactive solid in a shape of square corner by a hot surface is studied theoretically. Ignition time and the location of ignition point are determined as a function of dimensionless parameters, with the use of the homogeneous model of ignition. The effect of geometry on the ignition of solid fuel results in the local characteristics: the reaction is initiated in a hot point in depth of the substance. It is shown that ignition time is proportional to the dimensionless initial temperature, whereas for the ignition of the semiinfinite body this dependence was quadratic.