• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.8-13
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• 2010

Hydrogen is expected to become a new, clean source of energy for the next generation. Therefore, many studies have investigated the characteristics of the hydrogen flame. However, because the hydrogen flame has high temperature, the flame does not emit visible light, and the flame propagates at a high velocity, investigating its characteristics is difficult. In the present study, in order to simultaneously examine the flame temperature and flame propagation velocity of hydrogen/air mixtures, ultra fine thermocouples with diameters of 12.7, 25.4, and 50.8 ${\mu}m$ are utilized. The results show that it is possible to detect the arrival time of the flame. Due to the temperature compensation with the time constants of thermocouples, it is also possible to estimate the flame temperature.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.895-897
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• 1998

The optical spectra of microwave plasma by four kinds of gases($N_2$, $N_2-CH_4$, $H_{2}-CH_{4}$ and Air-$CH_4$) have been measured for investigating 388.4[nm] peak which has the same intensity as $H_{\alpha}$(656.4[nm]) peak. A 388.4[nm] peak by $N_2$ plasma, $N_{2}-CH_{4}$ plasma and Air-$CH_4$ plasma may be CN peak because it is with 337.1, 357.8 and 316.0[nm] peaks by $N_2$. And a 388.4[nm] peak by $H_{2}-CH_{4}$ plasma without by $N_2$ 337.1, 357.8 and 316.0[nm] peaks may be CH peak. In the investigation results for optical spectra by $H_{2}-CH_{4}$ plasma and $H_{2}-CH_{4}-O_{2}$ plasma, the density of hydrogen atom was increased because oxygen decompose hydrogen molecules in $H_{2}-CH_{4}$ plasma with oxygen. These hydrogen atom decompose $CH_4$ and increase CH radical. And the crystalline of deposited diamond was good and the growth rate increased.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.129-133
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• 1998

The phtocount distributions of a quasi-thermal light source were measured by using the photoelectric counting method. The source was fabricated from the ground glass plate of 9${\mu}{\textrm}{m}$ roughness illuminated by linearly polarized He-Ne laser beam. The coherence time of the quasi-thermal light changed from 31.4$mutextrm{s}$ to 2.48$mutextrm{s}$ according to the grain velocity of the ground glass plate. The photocount distribution showed the Bose-Einstein statistics for a long coherence time compared to the counting time interval, while the distribution approaches the Poisson distribution when the coherence time much shorter than the counting time.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.853-858
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• 2001

The knowledge of flame structure is essential for control of combustion instability phenomena. Some results of an experimental study on mechanism of naturally occurring combustion oscillations with a single dominant frequency are presented. Tests were conducted in a laboratory-scale dump combustor at atmospheric pressure. Sound level meter was used to track the pressure wave inside the combustor. The observed instability was a longitudinal mode with a frequency of $\sim341.8Hz$. Instability map was obtained at the condition of inlet temperature of $360^{\circ}C$, mean velocities of $8.5\sim10.8m/s$ and well premixed mixture. It showed that combustion instability was susceptible to occur in the lean conditions. In this study, unstable flame was observed from stoichiometric to 0.7 in overall equivalence ratio. At selected unstable conditions, phase-resolved OH chemiluminescence images were captured to investigate flame structure with various mean velocities. As mean velocity is increased, the flame grows and global heat release was changed. Due to these effects, combustion instability can be maintained at more lean air-fuel ratio. Also, these results give an insight to the controlling mechanism for an increasing heat release at maximum pressure.

• Journal of the Korean Ceramic Society
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• v.38 no.2
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• pp.107-111
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• 2001

Sr$_{(1-x)}$Ca$_{x}$TiO$_3$: Pr$^{3+}$ , Ga$^{3+}$ (0$\leq$x$\leq$1) 형광체의 여기 및 발광 스펙트럼과 분광 반사율을 조사하여 발광 메커니즘을 규명하고자 하였다. 발광 스펙트럼에서는 611~614nm 사이에서 peak을 가지는 하나의 적색 발광 밴드가 관찰되었으며, 조성에 따라 발광밴드의 모양이 달랐다. 이는 조성에 따른 모체의 결정 구조 변화 때문으로 생각된다. 여기 스펙트럼 끝단과 분광 반사율 스펙트럼의 흡수단은 서로 일치하였으며, 이 결과로부터 모체에 흡수된 에너지가 Pr$^{3+}$ 에 전달되어 적색광을 방출하는 것이 주된 메커니즘으로 생각된다. 한편 120$0^{\circ}C$에서 4시간동안 열처리하여 합성한 Sr$_{0.4}$Ca$_{0.6}$TiO$_3$:(0.1 mol%)Pr$^{3+}$ , (0.2 mol%)Ga$^{3+}$ 는 우수한 색순도와 휘도를 나타내었다.다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.261.2-261.2
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• 2014

저온에서 작동하는 대기압 플라즈마 젯은 생체 조직에의 플라즈마 처리를 가능하게 한다. 이에 이온과 전자, 활성 종, 전기장, UV 등을 발생시키는 플라즈마를 암세포에 처리하여 그에 따른 변화를 관찰하였다. 모세관 타입의 젯에 산소를 반응기체로 흘려주어 헬륨 내 산소 함유량에 따른 활성 산소종의 생성을 확인하였다. 대기압 플라즈마에 의해 생성되는 활성 산소 종(OH, O, electronically excited O (1D), O2 ($1{\Delta}g$) 등)이 세포에 산화 스트레스를 유발할 것이라 예상되어 인체의 폐암 세포[Human lung cancer cell, A549]에 펄스파의 헬륨-산소 플라즈마를 처리한 후, 세포 내 활성 산소 종의 증가량을 비교하였다. 그 결과 적은 양의 산소를 추가하였을 때 세포 내 활성 산소 종의 농도가 증가되었다. 이때 플라즈마에서 발생되는 활성 산소 종(Reactive Oxygen Species, ROS)들은 광 방출 스펙트럼(Optical Emission Spectroscopy)로 확인하였고, 세포내 활성 산소 종은 DCF-DA 염색을 통하여 분석하였다. 이러한 헬륨-산소 플라즈마가 세포 성장의 어떠한 시기에 영향을 미치는지를 알아보기 위하여 세포주기 변화를 분석한 결과, 플라즈마 처리 9시간 후부터 G2/M 주기에 머물러 있음을 확인하였다.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.157-161
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• 1999

A Ti:Sapphire laser pumped by the HCP has been designed and fabricated to study the optimal pumping conditions for lasing. The fluorescence energy converter LD-490 has been used. The result showed that the threshold energy of Ti:Sapphire laser is 1.39 KJ and the best efficiency is $7.13{\times}10^{-3}$% at the concentration $1.0{times}10^{-3}$ Mol/l of LD-490 dye. However, the efficiencies were decreased with the decrease of dye concentrations. The maximum output energy was obtained at 50 Torr Ar pressure, when the input voltage was 15 kV. As a convert dye, BBQ, was added to LD-490 with the rate of 1:1, the output energy was increased, whereas the thereshold energy was decreased as 1.17 kJ.

• Polymer(Korea)
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• v.39 no.2
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• pp.256-260
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• 2015

The addition of montmorillonite (MMT) in the UV curable polyurethane diacrylate based resins was investigated to fabricate nanocomposites with improved mechanical properties and water sorption behavior using different photoinitiator systems. As a result, it was observed that 1 wt% of clay loading fairly improved tensile resistance and water uptake behavior. It can be also confirmed that dual photoinitiator system consisted of benzyldimethyl ketal and bisacyl phosphine oxide exhibited enhanced energy absorption band 340~450 nm even with 3 wt% of MMT concentration, which may affect the curing behavior of nanocomposite especially in our UV lamp system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.715-717
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• 2016

Conventional drug carriers such as liposomes, nanoparticles, polymer micelles, polymeric conjugate and lipid microemulsion for cancer chemotherapy shield normal tissues from toxic drugs to treat cancer cells in tumors. However, inaccurate tumor targeting uncontrolled drug release from the carriers and unwanted accumulation in healthy sites can limit treatment efficacy with current conventional drug carriers with insufficient concentrations of drugs in the tumors and unexpected side effects as a result. In this research, we examined the use of sickle red blood cells as a new drug carrier with novel tumor targeting and controlled release properties. Sickle red blood cells show natural tumor preferential accumulation without any manipulation and controlled drug release is possible using a hemolysis method with photosensitizers.

• Korean Journal of Crystallography
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• v.9 no.2
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• pp.96-106
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• 1998

수평 전기로에서 AgInS2 다결정을 합성하여 HWE 방법으로 AgInS2 단결정 박막을 반절연성 GaAs(100) 위에 성장하였다. AgInS2 단결정 박막은 증발원과 기판의 온도를 각각 680℃, 410℃로 성장하였다. 이때 단결정 박막의 결정성이 10 K에서 측정한 광발광 스펙트럼은 597.8 nm(2.0741 eV) 근처에서 엑시톤 방출 스펙트럼이 가장 강하게 나타났으며, 또한 이중결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)도 121 arcsec로 가장 작게 측정되어 최적 성장 조건임을 알 수 있었다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293 K에서 각각 9.35×1023개/㎥, 2.94×10-2㎡/V·s였다. AgInS2 단결정 박막의 광전류 단파장대 봉우리들로부터 10 K에서 측정된 ΔCr(crystal field splitting)은 0.15eV, ΔSo(spin orbit coupling)는 0.0089 eV였다. 광전도 셀로서 응용성을 알아보기 위해 감도(γ), pc/dc(photocurrent/darkcurrent), 최대허용소비전력(maximum allowable power dissipation: MAPD), 응답시간(response time)등을 측정한 결과, S 증기 분위기에 열처리한 광전도 셀의 경우 γ=0.98, pc/dc=1.02×106, MAPD=312 mW, 오름시간(rise time)=10.4 ms, 내림시간(decay time)=10.8 ms로 가장 좋은 특성을 얻었다.