• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.383-396
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• 2017

The photothermal therapy is a method of cell ablation using the heat converted from the incident light by photothermal transducers. It offers a selective treatment to desired abnormal cells, in particular, tumor tissues. Among various photothermal agents, gold nanoparticles (Au NPs) have received enormous attention due to their unique physicochemical property over last two decades. In this review, we address research strategies and methods to improve treatment efficacy by organizing recent research works. We mainly focus on research works to enhance light-to-heat conversion via optimizing the morphology of Au NPs and related assemblies as well as the strategies to deliver Au NPs efficiently to specific targets. We also introduce convergence research efforts to combine Au NP-mediated photothermal treatment and other functions such as diagnostic capabilities and other therapeutic methods.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.4 s.193
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• pp.147-152
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• 2007

UV laser ablation of polyimide is a combination of photochemical and photothermal mechanism. Photochemical mechanism is that molecular bonds are broken by photon energy and photothermal is evaporation and melt expulsion. When the laser processing, the etching depth needs to be calculated for prediction of processing result. In this paper, in order to predict the laser etching depth of polyimide by UV laser with the wavelength of 355nm, the theoretical model which includes both the photothermal and the photochemical effect was introduced. The model parameters were obtained by comparing with experimental results. The 3rd harmonic $Nd:YVO_4$ laser system was used in the experiment. From these experimental and theoretical results, the laser ablation of a polyimide was verified to achieve the highest quality microstructure.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.1
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• pp.27-34
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• 2015

Many applications of nanoparticles have been developed since 1970s. Surface plasmon resonance (SPR) effect can be generated at the surface of nanoparticles by illumination. SPR is the resonant oscillation of conduction electrons at the surface material stimulated by incident light. The collisions between excited electrons and metal atoms can cause the production of thermal energy (photothermal effect). Here, we presented the development of thermo-cosmetics using photothermal effect of gold nanoparticles. Gold nanoparticles (GNPs) were chosen for it's low toxicity. We also and investigated the cell biocompatibility and heating effectiveness for photothermal effect of GNPs. Synthesized GNPs were verified by UV-vis spectrophotometer, where GNP has a characteristic absorbance spectrum. Concentration of GNP was measured by atomic absorption analyzer. The cytotoxicity was confirmed by MTT assay and double staining assay. Photothermal effect of GNP was demonstrated by the thermal increasing properties depending on GNP concentration, which was taken by an IR-thermal camera with a xenon lamp as the light source. If the thermal effect of GNP is applied for thermo-cosmetics, it can supply heat to skin by converting solar energy into thermal energy. Thus, cosmetics containing GNPs can provide benefits to people in the cold region or winter season for maintaining skin temperature, which lead to a positive effect on skin health.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.312-319
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• 2021

Photothermal therapy is a treatment that necrotizes selectively the abnormal cells, in particular cancer cells, which are more vulnerable to heat than normal cells, using the heat generated when irradiating light. In this study, we synthesized a reduced graphene oxide with carboxyl groups (CRGO)-gold nanorod (AuNR) nanocomposite for photothermal treatment. Graphene oxide (GO) was selectively reduced and exfoliated at high temperature to synthesize CRGO, and the length of AuNR was adjusted according to the amount of AgNO₃, to synthesize AuNR with a strong absorption peak at 880 nm, as an ideal photothermal agent. It was determined through FT-IR, thermogravimetric and fluorescence analyses that more carboxyl groups were conjugated with CRGO over RGO. In addition, CRGO exhibited excellent stability in aqueous solutions compared to RGO due to the presence of carboxylic acid. The CRGO-AuNR nanocomposites fabricated by electrostatic interaction have an average size of ~317 nm with a narrow size distribution. It was confirmed that under radiation with a near-infrared 880 nm laser which has an excellent tissue transmittance, the photothermal effect of CRGO-AuNR nanocomposites was greater than that of AuNR due to the synergistic effect of the two photothermal agents, CRGO and AuNR. Furthermore, the results of cancer cell toxicity by photothermal effect revealed that CRGO-AuNR nanocomposites showed superb cytotoxic properties. Therefore, the CRGO-AuNR nanocomposites are expected to be applied to the field of anticancer photothermal therapy based on their stable dispersibility and improved photothermal effect.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.117-123
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• 1998

We investigated the effect of mechanical backside damage in Czochralski grown silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductivity decay method, photo-acoustic displacement method, X-ray section topography, and wet oxidation/preferential etching methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the photo-acoustic displacement values increased proportionally, and it was at Grade 1: Grade 2:Grade 3 = 1:19.6:41 that the normalized relative quantization ratio of excess photo-acoustic displacement in damaged wafer was calculated, which are normalized to the excess PAD from sample Grade 1.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.269-275
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• 2004

콘덴싱보일러는 배기가스중의 수증기를 콘덴싱방식이라는 열교환 기술을 통해 2개의 열교환기에서 응축시키면서 생기는 응축잠열을 보일러에 더하여 줌으로써 기존보일러 대비 15 $^{\sim}$ 20% 이상 열효율이 높이는 첨단기술이 사용된 보일러로 콘덴싱보일러의 개발현황, 에너지 절감 효과 그리고 환경친화적 효과를 소개하고자 합니다.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.134-139
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• 2007

Usually nanosecond pulsed laser processing of metal is mainly affected by the thermal ablation. Many studies of the theoretical analysis and modeling to predict the laser ablation of metal are suggested on the basis of the photothermal mechanism at higher laser fluence. In this paper, we investigate the etching depth and laser fluence of laser ablation of copper foils and propose the simplified SSB Model(Srinivasan-Smrtic-Babu model) to study the photothermal effect of nanosecond pulsed laser ablation. The experimental results show that the photothermal ablation of the 355nm DPSS $NdYVO_{4}$ laser is useful to process the copper thin foils.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.574-576
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• 2003

인터넷과 멀티미디어의 눈부신 발전은 교육현장에서도 다양한 교육매체로 활용되어 수업을 돕고 있다. 이러한 교육매체들은 학습자의 생각으로만 이해할 수 있는 것들을 시각적으로 표현하여 보다 직관적이고 구체적으로 이해시킬 수 있다. 이에 본 논문에서는 플래시 액션스크립트를 사용하여 버블, 삽입, 쉘, 퀵, 힙 알고리즘의 수행과정을 그래픽 애니메이션으로 구현함으로 시각적 효과를 통해 다양한 정렬과정을 스스로 학습할 수 있는 학습 시스템을 구현하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.06a
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• pp.66-69
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• 2001

최근 인터넷의 발전으로 방대한 정보가 존재함에 따라 이들 정보들을 통합 관리할 필요성이 증대하고, 웹 검색 시스템의 서비스가 텍스트뿐만 아니라 이미지나 사운드 데이터와 같은 멀티미디어 정보까지 보편화되어 검색의 결과로 서비스를 제공하고 있다. 기존의 검색결과를 보면 멀티미디어 데이터에 대한 검색결과는 부가적 정보로서 서비스를 제공하기 때문에 검색 결과에 대해서도 정확한 결과에 대한 서비스를 제공하지 못하고 있다. 본 논문에서는 XML기반에서 멀티미디어 데이터 소스에 대한 메타데이터를 DTD로 설계하여 내용기반 질의를 효과적으로 분산처리 할 수 있도록 Mediator를 설계한다.

• Journal of Adhesion and Interface
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• v.25 no.2
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• pp.69-74
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• 2024

Soft actuators can be applied to various fields such as the medical industry and manufacturing industry due to the flexibility and smooth movement resulted from their constituent materials. Stimuli-responsive hydrogels are a class of materials that can show large volume changes due to various surrounding stimuli and thus is suitable as a soft actuator material. However, because the change in volume of the stimuli-responsive hydrogel depends on the rate of temperature change and the rate at which the solvent diffuses into the polymer network, in most typical operating conditions, the response time of the actuator is slow due to inefficient heat transfer and diffusion process. In this study, a conjugated polymer was introduced into polydiethylacrylamide, a thermoresponsive hydrogel, to implement a soft actuator driven by light, and the improvement in response time by the photothermal effect of the conjugated polymer was investigated. It was confirmed that the response time was improved by 41% by the introduction of the conjugated polymer, due to the improvement in heat transfer efficiency. Finally, a soft gripper using the hydrogel with improved response time was fabricated and the response time of the gripper was investigated.