• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.480.1-480.1
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• 2014

In this study, we suggest the new emitter formation applied solid phase epitaxy (SPE) growth process using rapid thermal process (RTP). Preferentially, we describe the SPE growth of intrinsic a-Si thin film through RTP heat treatment by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Phase transition of intrinsic a-Si thin films were taken place under $600^{\circ}C$ for 5 min annealing condition measured by spectroscopic ellipsometer (SE) applied to effective medium approximation (EMA). We confirmed the SPE growth using high resolution transmission electron microscope (HR-TEM) analysis. Similarly, phase transition of P doped a-Si thin films were arisen $700^{\circ}C$ for 1 min, however, crystallinity is lower than intrinsic a-Si thin films. It is referable to the interference of the dopant. Based on this, we fabricated 16.7% solar cell to apply emitter layer formed SPE growth of P doped a-Si thin films using RTP. We considered that is a relative short process time compare to make the phosphorus emitter such as diffusion using furnace. Also, it is causing process simplification that can be omitted phosphorus silicate glass (PSG) removal and edge isolation process.

• 한국균학회지
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• 제26권4호통권87호
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• pp.525-530
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• 1998

Cinnamaldehyde 유도체의 항진균활성을 조사한 결과 ${\alpha}-chlorocinnamadehyde$가 가장 항균활성이 우수한 것으로 평가되었다. ${\alpha}-Chlorocinnamaldehyde$는 피부진균증의 원인균주인 Tricophyton mentagrophytes, Microsporium gypseum, Epidermophyton floccosum, Cryptococcus neoformans, Aspergillus niger, Candida albicans와 Penicillium avellaneum에 대해 $9.8{\sim}19.5\;{\mu}g/ml$의 최소저지농도를 보였으나 시판중인 항진균제 clotrimzole보다는 역가가 낮은 것으로 나타났다. ${\alpha}-Chlorocinnamaldehyde$를 제외한 나머지 관련 유도체를 비교한 결과 phenyl기 주위의 유도체 화합물에서는 우수한 항균활성이 관찰되지 않았으며, acrolein기가 항균활성에 중요한 관능기로 작용하는 것으로 나타났다.

• 한국재료학회지
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• 제30권10호
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• pp.515-521
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• 2020

Organic-inorganic hybrid perovskite nanocrystals have attracted a lot of attention owing to their excellent optical properties such as high absorption coefficient, high diffusion length, and photoluminescence quantum yield in optoelectronic applications. Despite the many advantages of optoelectronic materials, understanding on how these materials interact with their environments is still lacking. In this study, the fluorescence properties of methylammonium lead bromide (CH₃NH₃PbBr₃, MAPbBr₃) nanoparticles are investigated for the detection of volatile organic compounds (VOCs) and aliphatic amines (monoethylamine, diethylamine, and trimethylamine). In particular, colloidal MAPbBr₃ nanoparticles demonstrate a high selectivity in response to diethylamine, in which a significant photoluminescence (PL) quenching (~ 100 %) is observed at a concentration of 100 ppm. This selectivity to the aliphatic amines may originate from the relative size of the amine molecules that must be accommodated in the perovskite crystals structure with a narrow range of tolerance factor. Sensitive PL response of MAPbBr₃ nanocrystals suggests a simple and effective strategy for colorimetric and fluorescence sensing of aliphatic amines in organic solution phase.

• Parasites, Hosts and Diseases
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• 제47권4호
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• pp.377-380
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• 2009

Growing patterns of pediculocidal drug resistance towards head louse laid the foundation for research in exploring novel anti-lice agents from medicinal plants. In the present study, various extracts of Pongamia pinnata leaves were tested against the head louse Pediculus humanus capitis. A filter paper diffusion method was conducted for determining the potential pediculocidal and ovicidal activity of chloroform, petroleum ether, methanol, and water extracts of P. pinnata leaves. The findings revealed that petroleum ether extracts possess excellent anti-lice activity with values ranging between 50.3% and 100% where as chloroform and methanol extracts showed moderate pediculocidal effects. The chloroform and methanol extracts were also successful in inhibiting nymph emergence and the petroleum ether extract was the most effective with a complete inhibition of emergence. Water extract was devoid of both pediculocidal and ovicidal activities. All the results were well comparable with benzoyl benzoate (25% w/v). These results showed the prospect of using P. pinnata leave extracts against P. humanus capitis in difficult situations of emergence of resistance to synthetic anti-lice agents.

• 한국통신학회논문지
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• 제19권9호
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• pp.1782-1792
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• 1994

$Ti:LiNbO_3$채널형 광도파로와 Asymmetric Coplanar Strip(ACPS) 전극구조를 이용해서, $1.3{\mu}m$에서 동작하는 진형파형 위상 광변조기를 설계, 제작한 다음 변조특성을 관찰하였다. 위상정합이 개선되도록 ACPS 진행파형 전극을 설계하기 위해서 전극과 완충박막의 두께를 포함하여, 전극제원의 해석적 함수로 특성저항, 변조파의 유효굴절률 및 전극손실 등을 고려하였다. Ti 확산방법으로 저손실 채널형 광도파로 제작하였으며, double-spin image reversal 공정을 이용해서 $2.5{\mu}m$ 두께의 전극을 형성하였다. 9GHz 부근에서의 전극구조 공진형상 때문에 변조특성이 제한 되었지만, 2.5GHz 까지는 큰 왜곡없이 변조특성이 관찰되었다.

• 공업화학
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• 제10권3호
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• pp.382-387
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• 1999

졸-겔법을 이용하여 무정형의 $V_2O_5$ 겔을 제조한 후, 스핀코우팅에 의하여 균일한 박막의 $V_2O_5$, xerogel 전극을 개발하여 전극의 임피던스 특성을 연구하였다. $V_2O_5$겔이 xerogel로 전환되는 과정에서 스핀코우팅 방법이 $V_2O_5$의 비등방성을 감소시킬 뿐만 아니라 우수한 전기화학적 특성을 갖게 하였다. $V_2O_5$ xerogel의 리튜이온 확산계수 및 전하이동저항은 xerogel내에 존재하는 리튬이온의 물분율이 변함에 따라 증감하였으며 가역성이 우수하였다.

• 생약학회지
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• 제42권2호
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• pp.155-160
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• 2011

In this study, we investigated on antioxidative activity, antibacterial activity against pathogens of acne and tyrosinase inhibitory activity in 75% EtOH extract and its fractions from bark of Prunus sargen tii. The total polyphenol and flavonoidcontent of the EtOAc fraction were found to be 378.0 mg/g and 67.5 mg/g as the highest content. In the measurement of DPPH radical scavenging ability, EtOAc and BuOH fraction were exhibited stronger scavenging ability than the other fractions and 75% EtOH extract. In antibacterial activity by disc diffusion assay against pathogen of acne, antibacterial activity of the EtOAc fraction and 75% EtOH extract was stronger than the other fractions. Especially, the EtOAc fraction was the highest effective fraction in the antibacterial activity. Moreover, tyrosinase inhibitory activity of EtOAc fraction, BuOH fraction and 75% EtOH extract was higher than the other fractions. In particular, tyrosinase inhibitory activity of the EtOAc fraction showed higher activity than ascorbic acid used as positive control.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.125-134
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• 2004

The improvement of artificial respiration method has brought about the decrease in mortality of pulmonary diseases patients. Various respiratory curative methods, inclusive of HFOV (High Frequency Oscillatory Ventilation), have been developed for more effectual and less harmful management of acute respiratory failure. However, the mechanism of gas transfer and diffusion in a bronchiole has not yet been clarified in detail. As a first approach to the problem, we measured oscillatory flows in a Y-shaped micro-channels as bronchiole model by micro Particle Image Velocimetry(micro PIV). In order to establish the fundamental technique of PIV measurements on oscillatory air flow in a micro-channel, we used about 500-nm-diameter incense smoke particles, a diode laser, a high speed camera including an objective lens, and a HFOV, which is effective technique for medical care of pulmonary disease patients, especially, infants. The bronchiole model size is that parent tube is $500\{mu}m$ width and $500\{mu}m$ depth, and daughter tubes are $450\{mu}m$ width and $500\{mu}m$ depth. From this study made on the phenomenon of fluid in micro size bronchus branch of a lung, we succeeded to get time series velocity distribution in a micro scale bronchial mode. The experimental results of velocity distribution changing with time obtained by micro PIV can give fundamental knowledge on oscillatory airflow in micro-channel.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.85.1-85.1
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• 2011

In this study, Grafoil$^{TM}$ which has comparable electric resistance and chemical stability but is flexible, fragile, and cheap material was adopted as bipolar plates for proton exchange membrane fuel cell(PEMFC) having only one straight line flow channel. Because of its flexibility, pressurizations of cell with various pressures showed different operating characteristics compared to ordinary graphite-used PEMFC. While performances of both cells decreased as these were pressurized, investigation of ohmic and faradaic resistance by electrochemical impedance measurement indicated different tendency of change. Ohmic resistance of graphite-used cell increased with increasing pressure, which is reversed in Grafoil$^{TM}$-used cell. It is speculated that effective chemical reaction area is decreased with increasing pressure in case of graphite-used one, but because of flexible property of Grafoil$^{TM}$, gas diffusion layer in Grafoil$^{TM}$-used cell was well-activated. Different rate of change of faradaic resistances in both cells support this supposition. However, although optimum point of pressurization is found, it is required to investigate other operating conditions because of low performance compared to graphite-used cell.

• 공학교육연구
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• 제23권3호
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• pp.13-19
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• 2020

The purpose of this study is to develop and apply a make-a-thon program based on engineering problem solving for science high school students and to analyze the changes of participating students. Through the consultation of teachers and experts, a team-based and student-driven engineering problem-solving-oriented make-a-thon program was developed. And, the program operated using KAIST's human and material resources for 51 students. Students composed of 12 teams studied 12 topics through an engineering problem-solving process, and the overall program satisfaction was very high, on average 4.62. Through this program, students' creative leader competency have been positively changed, especially in cognitive characteristics (diffusion thinking, problem solving ability) and social characteristics (pursuit of social values). Attitudes toward engineering also changed positively, especially in terms of difficulty of engineering, interest in engineering, gender role in engineering, and engineering and occupational factors. In conclusion, it was confirmed that this program is very effective for science high school students with high demand for engineering education.