• International Journal of Aeronautical and Space Sciences
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• 제11권1호
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• pp.26-30
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• 2010

The present paper studies the thermally-induced vibration phenomenon of the flexible space boom structure. In order to simulate the thermally-induced vibration phenomenon of the flexible thin boom structure of the spacecraft with the attached tip mass in space, the thermally-induced vibration including thermal flutter is experimentally investigated at various thermal environments using a heating lamp in vacuum chamber. In this experimental study, fluctuating characteristics, natural frequency and thermal strains of the thermally-induced vibration are parametrically investigated at various thermal environment conditions. Finally the thermally-induced vibration of the flexible boom structure of the orbiting earth satellite in solar radiation environment from the earth eclipse region including umbra and penumbra is simulated using the power control of the heating lamp in the vacuum chamber.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2001년도 추계학술대회 논문집
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• pp.358-359
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• 2001

PAHs는 불완전연소 과정과 주유소나 타르 생산공장 주변에서 발생하는데 돌연변이와 발암의 잠재력으로 인하여 특별한 관심이 요구되는 것들이고 US-EPA에서도 우선 오염물질로 선정되었다. PAHs를 검출하는 훌륭한 기술들이 존재하나, 이러한 기술들은 연속적인 모니터링이 요구되거나 많은 수의 샘플을 분석해야할 경우에 상당한 양의 비용과 시간이 요구된다. 그러나 분광학 기술을 바탕으로 한 Laser-Induced Fluorescence(LIF) spectroscopy를 이용한 방법은 실시간으로 연속적인 측정을 가능하게 할 뿐 아니라 여러 가지 PAHs, 유류오염물질 등의 물질을 동시에 측정할 수 있다. (중략)

• Carbon letters
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• 제16권1호
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• pp.41-44
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• 2015

We report the preparation of sulfonated reduced graphene oxide (SRGO) by the sulfonation of graphene oxide followed by radiation-induced chemical reduction. Graphene oxide prepared by the well-known modified Hummer's method was sulfonated with the aryl diazonium salt of sulfanilic acid. Sulfonated graphene oxide (SGO) dispersed in ethanol was subsequently reduced by ${\gamma}$-ray irradiation at various absorbed doses to produce SRGO. The results of optical, chemical, and thermal analyses revealed that SRGO was successfully prepared by ${\gamma}$-ray irradiation-induced chemical reduction of the SGO suspension. Moreover, the electrical conductivity of SRGO was increased up to 2.94 S/cm with an increase of the absorbed dose.

• 방사선산업학회지
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• 제5권2호
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• pp.107-112
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• 2011

Electron beam-induced crosslinking of polycaprolactone (PCL) films containing various crosslinking agents (CAs) was investigated in this study. PCL films containing various CAs prepared by a solution casting method were irradiated by electron beams at various absorption doses and the irradiated PCL films were investigated in terms of their crosslinking degree, thermal and mechanical properties, and biodegradability. Based on the results of the crosslinking degree measurement, triallyl isocyanurate was found to be most effective for the electron-beam induced crosslinking of PCL films. The results of the UTM, DMA, and TMA revealed that the thermal and mechanical properties of the crosslinked PCL films were greatly improved in comparison to those of the pure PCL. The results of the enzymatic degradation test revealed that the biodegradability of the crosslinked PCL films was reduced in comparison to that of the pure PCL.

• Wind and Structures
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• 제3권4호
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• pp.267-277
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• 2000

This paper aims to describe the aerodynamic vibrations of various structural elements of bridges, which are particular issues at present. The aerodynamic countermeasures for those vibrations are also discussed considering the generation mechanisms of the aerodynamic instabilities. In this paper, an example of vortex-induced oscillation of bridge deck and its lesson are discussed. Next, the wind-induced cable vibration and its aerodynamic countermeasures are reviewed. Then, the aerodynamic characteristics on two edge girders and their feasibility for application to long span cable-stayed bridges are considered. Furthermore, the bridge decks for future long span bridges are proposed and their aerodynamic characteristics are also discussed.

• 대한한방내과학회지
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• 제34권1호
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• pp.59-70
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• 2013

Objectives : This study was designed to test the effect of a warm environment and Bujaijung-tang on immune and lipid metabolism in rats. Methods : The extract from Bujaijung-tang was made by the pharmacy department of Kyung-Hee oriental medical hospital. The animals were divided into four groups, by room or warm environment and Bujaijung-tang administration. Each group had 8 Sprague-Dawley Rats. We measured body temperature twice a week, body weight three times a week. After 3 weeks of experiment, serum lipid level, WBC, differential count, lymphocyte proliferation and immune cytokine concentration were measured. Results : 1. warm environment induced weight loss in rats. 2. warm environment induced a decrease of total cholesterol and low-density lipoprotein (LDL) cholesterol gain. 3. warm environment and Bujaijung-tang induced an increase of tumor necrosis factor (TNF)-${\alpha}$ concentration. Conclusions : The warm environment had a hyperlipidemia modulating effect. The warm environment and Bujaijung-tang had an immune modulating effect.

• Fibers and Polymers
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• 제2권1호
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• pp.123-130
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• 2001

Photoresponsive side chain copolymer and homopolymer containing an aminonitroazobenzene were synthesized for studying photoisomerization behavior and photo-induced anisotropy. Trans-to-cis photoisomerization was observed under the exposure of a circularly polarized visible light with UV-Vis absorption spectroscopy. Reorientation of polar azobenzene molecules induced optical anisotropy under a linearly polarized light at 532nm. Polarized absorption spectroscopy was employed to investigate the anisotropy of the polymer film during irradiationg of the excitation light. Layers of two photosensitive polymers were used for aligning liquid crystal(LC) molecules instead of one of the rubbed polyimide layers in the conventional twisted nematic cell. For producing homogeneous alignment of a nematic LC molecule, a linearly polarized light was exposed to the films of two polymers. The stability of the LC alignment upon the linearly polarized light exposure was also studied.

• 방사선산업학회지
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• 제4권1호
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• pp.91-94
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• 2010

A number of epidemiological studies as well as biological experiments, showed that genistein, one of the isoflavone, prevents prostate cancer occurrence. In this study, we showed that genistein inhibited the cell proliferation of human promyeoltic leukemia HL-60 cells and induced G2/M phase arrest. In addition, combination of genistein treatment and ${\gamma}$-irradiation displayed synergistic effect in apoptotic cell death of HL-60 cells. This means that the repair of genistein-induced DNA damage was hindered by ${\gamma}$-radiation and thus cell death was increased. In conclusion, genistein is one of the important chemicals that sensitize radiation-induced cell death.

• 해양환경안전학회지
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• 제16권2호
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• pp.185-193
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• 2010

Boussinesq 모형을 이용하여 규칙파 조건(Regular wave condition)에서 파랑변형 및 해빈류의 수치모의를 하였다. 파랑변형의 수치결과는 선행 연구에 의한 수리실험 결과와 비교하여 매우 좋은 일치를 보였으며, 검증한 파랑변형 결과를 바탕으로 충분히 안정한 상태 이후의 해빈류를 계산하여 예측하였다. 모형의 현장 적용성을 위해, 실규모해역에서 관측한 선행 연구의 현장자료와 비교하였으며, 파랑변형의 수치결과는 현장자료와 비교적 양호한 일치를 보였다. 해빈류의 수치결과는 연안사주가 발단된 지역에서 다소 과소평가 되었지만, 전반적으로 해빈류의 공간적 분포에 대하여 정도 있게 예측한 것으로 여겨진다.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2004년도 추계학술대회 논문집
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• pp.310-311
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• 2004