• 한국가축번식학회지
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• 제20권3호
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• pp.343-351
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• 1996

본 연구의 목적은 돼지난자의 체외성숙, 수정 및 단위발생시 일어나는 표층과립의 분포를 살펴보고, 그것들의 역할을 규명해 보고자 실시하였다. 난자의 표층과립은 형광염색을 실시한 후 laser scanning confocal microscope를 이용하여 관찰하거나 transmission electron microscope를 사용하여 관찰하였다. Germinal vesicle 단계의 돼지난자에서는 표층과립은 난자피질에 비교적 두꺼운 형태로 발견되었는데, germinal vesicle breakdown이 일어난 직후 피질 부근으로 표층과립의 움직임이 관찰되었다. Microfilaments의 중합화를 방해하는 cytochalasin B를 처리하였을 때 표층과립의 움직임은 관찰되지 않았다. 무 처리군의 수정 및 단위발생을 유도한 난자에서는 표층과립 내용물들이 위란강내에 균질하게 관찰되었으나, cytochalasin B를 처리한 난자에서는 비정상적인 cortical granule의 움직임을 관장하고 이러한 움직임이 수정시 다정자 침입을 막고 표층과립 반응에 영향을 미치는 것으로 사료된다.

• Journal of the Optical Society of Korea
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• 제17권6호
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• pp.548-558
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• 2013

In this work, laser induced breakdown spectroscopy (LIBS) is used to investigate soil samples collected from different desert areas of Riyadh city in Saudi Arabia. Both qualitative analysis and plasma parameters are studied via the observed LIBS spectra. These experiments have been done using a Spectrolaser-7000 system with 50 mJ fundamental wavelength of Nd:YAG laser and detection delay time of 1 microsecond. Many spectral lines are highly resolved for many elements like Al, Fe, Mg, Si, Mn, Na, Ca and K. The electron temperatures Te and electron densities Ne, for the constituent of generated LIBS plasma, are determined for all the collected samples. It is found that both Te and Ne vary from one desert area to other. This variation is due to the change of the elemental concentration in different desert areas that affects the sample's matrices. Time dependent measurements have also been performed on the soil samples. While the signal-to-base ratio (SBR) reached its optimal value at 1 microsecond, the plasma parameters Ne and Te reach values of $4{\times}10^{17}cm^{-3}$ and 9235 K, respectively, at 2.5 microsecond. The later indicate that the plasma cooling processes are slow in comparison to the previously observed results for metallic samples. The observed results show also that in the future it is possible to enhance the exploitation of LIBS in the remote on-line environmental monitoring application, by following up only the values of Ne and Te for one element of the soil desert sample using an optical fiber probe.

• 한국분무공학회지
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• 제27권2호
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• pp.84-93
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• 2022

To implement carbon-neutrality in transportation sectors until 2050, hydrogen is considered a promising fuel for internal combustion engines because hydrogen does not contain carbon itself. Although hydrogen does not emit CO₂ emission from its combustion process, the low energy density in a volume unit hinders the adoption of hydrogen. Therefore, the understanding of hydrogen jet behavior and measurement of equivalence ratio must be conducted to completely implement the high-pressure hydrogen direct injection. The main objective of this research is feasibility test of hydrogen local equivalence ratio measurement by laser-induced breakdown spectroscopy (LIBs). To visualize the macroscopic structure of hydrogen jet, high-speed schlieren imaging was conducted. Moreover, LIBs has been adopted to validate the feasibility of hydrogen local equivalence ratio measurement. The hydrogen injection pressure was varied from 4 MPa to 8 MPa and injected in a constant volume chamber where the ambient pressure was 0.5 MPa. The increased injection pressure extends the vertical penetration of hydrogen jet. Due to the higher momentum supply when the injection pressure is high, the hydrogen has easily diffused in all directions. As the laser trigger timing has delayed, the low hydrogen atomic emission was detected due to the longer mixture formation time. Based on equivalence ratio measurement results, LIBs could be applied as a methodology for hydrogen local equivalence ratio measurement.

• 전기학회논문지
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• 제67권4호
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• pp.569-577
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• 2018

In this paper, with the aid of information which is included within data, preprocessing algorithm-based black plastic classifier is designed. The slope and area of spectrum obtained by using laser induced breakdown spectroscopy(LIBS) are analyzed for each material and its ensuing information is applied as the input data of the proposed classifier. The slope is represented by the rate of change of wavelength and intensity. Also, the area is calculated by the wavelength of the spectrum peak where the material property of chemical elements such as carbon and hydrogen appears. Using informations such as slope and area, input data of the proposed classifier is constructed. In the preprocessing part of the classifier, Principal Component Analysis(PCA) and fuzzy transform are used for dimensional reduction from high dimensional input variables to low dimensional input variables. Characteristic analysis of the materials as well as the processing speed of the classifier is improved. In the condition part, FCM clustering is applied and linear function is used as connection weight in the conclusion part. By means of Particle Swarm Optimization(PSO), parameters such as the number of clusters, fuzzification coefficient and the number of input variables are optimized. To demonstrate the superiority of classification performance, classification rate is compared by using WEKA 3.8 data mining software which contains various classifiers such as Naivebayes, SVM and Multilayer perceptron.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.305-308
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• 2004

We present a novel process for the ultra low temperature (<150$^{\circ}C$) polycrystalline silicon (ULTPS) TFT for the flexible display applications on the plastic substrate. The sequential lateral solidification (SLS) was used for the crystallization of the amorphous silicon film deposited by rf magnetron sputtering, resulting in high mobility polycrystalline silicon (poly-Si) film. The gate dielectric was composed of thin $SiO_2$ formed by plasma oxidation and $Al_2O_3$ deposited by plasma enhanced atomic layer deposition. The breakdown field of gate dielectric on poly-Si film showed above 6.3 MV/cm. Laser activation reduced the source/drain resistance below 200 ${\Omega}$/ㅁ for n layer and 400 ${\Omega}$/ㅁ for p layer. The fabricated ULTPS TFT shows excellent performance with mobilities of 114 $cm^2$/Vs (nMOS) and 42 $cm^2$/Vs (pMOS), on/off current ratios of 4.20${\times}10^6$ (nMOS) and 5.7${\times}10^5$ (PMOS).

• 한국전기전자재료학회논문지
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• 제29권10호
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• pp.620-624
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• 2016

Ferroelectric $Pb(Zr_{0.52}Ti_{0.48})O_3$ (PZT) films were deposited on SrTiO3(100) substrate by using conductive $SrRuO_3$ films as underlayer and their structural and ferroelectric properties were investigated. PZT films were grown in (00l) orientation on well lattice-matched pseudo-cubic $SrRuO_3$ films. Thickness dependence of ferroelectric and electrical properties of PZT films was investigated. PZT film with 400 nm thickness showed a remanent polarization ($P_r$) of $29.0{\mu}C/cm^2$ and coercive field ($E_c$) of 83 kV/cm, and $P_r$ decreased and $E_c$ increased with thickness reduction. The dielectric constant for PZT films showed gradual decrease with thickness reduction. Breakdown field of PZT films did not show the thickness dependence and displayed as high value as 1 MV/cm.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1857-1862
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• 2008

Resonant frequency tuning of micro devices is essential to achieve performance uniformity and high sensitivity. Previously reported frequency tuning methods using electrostatic force or mass deposition are not directly applicable to non-conducting polymer devices and have limitations such as dielectric breakdown or low tunable bandwidth. In this paper, thermally frequency-tunable microactuators with poly-dimethylsiloxane membranes are proposed. Permanent and/or nonpermanent frequency tunings are possible using a simple temperature control of the device. Resonant frequency and Q-factor variations of devices according to temperature change were studied using a micro heater and laser Doppler vibrometer. The initial resonant frequencies determined by polymer curing and hardening temperatures are reversibly tuned by thermal cycles. The measured resonant frequency of 9.7 kHz was tuned up by ${\sim}25%$ and Q-factor was increased from 14.5 to 27 as the micro heater voltage increased from 0 to 70 V.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.785-789
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• 2005

Low temperature deposition of silicon and silicon nitride films by catalytic CVD technique was studied for application to thin film transistors on plastic substrates for flexible AMOLEDs. The substrate temperature initially held at room temperature, and was controlled successfully below $150^{\circ}C$ during the entire deposition process. Amorphous silicon films having good adhesion, good surface morphology and sufficiently low content of atomic hydrogen were obtained and could be successfully crystallized using excimer laser without a prior dehydrogenation step. $SiN_x$ films showed a good refractive index, a high deposition rate, a moderate breakdown field and a dielectric constant. The Cat-CVD silicon and silicon nitride films can be good candidates for fabricating thin films transistors on plastic substrates to drive active-matrix organic light emitting display.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.149-152
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• 2005

We present the characterization of poly-Si TFT fabricated below on Plastic Substrate below $170^{\circ}C$ on plastic substrate using excimer laser crystallization of Xe sputtered Si films. Gate insulator with a breakdown field exceeding 8 MV/cm was deposited by using inductively coupled plasma CVD. Finally, we successfully fabricate TFT with a electron field-effect mobility value greater than $290\;cm^2/Vsec$.

• 대한기계학회논문집B
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• 제23권7호
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• pp.918-927
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• 1999

In the fully developed internal flow fields, there are complex transition flows caused by interaction of the cross flow and jet when jet is Injected Into the flow. These interactions are studied by means of the flow visualization methods. An instantaneous laser tomographic method is used to reveal the physical mechanism and the structure of vortices formation in the branch pipe flow. The velocity range of cross flow of the pipe is 0.7m/s and the corresponding Reynolds number $R_{cf}$, based on the duct height is $5.6{\times}10^3$, diameter/height ratios(d/H) 0.14 and velocity ratios 3.0. Oil mist with the size of $10{\mu}m$ diameter is used for the scattering particle. The instantaneous topological features of the vortex ring roll-up of the jet shear layer and characteristics of this flow are studied in detail by performing flow visualization in rectangular duct flow. It is found that the formation and roll-up of ring vortices is a periodic phenomenon. The detailed topology of the vortices in the near field of a cross -flow jet and the mechanism associated with them give enforced hints of vortex breakdown within the vortex system due to the interaction of the jet and the cross-flow.