• 대한의용생체공학회:의공학회지
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• 제30권1호
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• pp.18-22
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• 2009

Laser has been widely used in various fields of medicine. Recently, noninvasive low-level laser therapeutic medical devices have been introduced in market. However, low-level laser cannot deliver enough photon density to expect positive therapeutic results in deep tissue layer due to the light scattering property in tissue. In order to overcome the limitation, this study was aimed to develop a negative pressure applied low-level laser probe to optimize laser transmission pattern and therefore, to improve photon density in soft tissue. In order to evaluate the possibility of clinical application of the developed laser probe, ex-vivo experiments were performed with porcine skin samples and laser transmissions were quantitatively measured as a function of tissue compression. The laser probe has an air suction hole to apply negative pressure to skin, a transparent plastic body to observe variations of tissue, and a small metallic optical fiber guide to support the optical fiber when negative pressure was applied. By applying negative pressure to the laser probe, the porcine skin under the metallic optical fiber guide is compressed down and, at the same time, low-level laser is emitted into the skin. Finally, the diffusion images of laser in the sample were acquired by a CCD camera and analyzed. Compared to the peak intensity without the compression, the peak intensity of laser increased about $2{\sim}2.5$ times and FWHM decreased about $1.67{\sim}2.85$ times. In addition, the laser peak intensity was positively and linearly increased as a function of compression. In conclusion, we verified that the developed low-level laser probe can control the photon density in tissue by applying compression, and therefore, its potential for clinical applications.

• 한국분무공학회지
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• 제6권1호
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• pp.18-24
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• 2001

Liquid fossil fuel contaminated by water can cause trouble in the combustion processes and affect the endurance of a combustion system. Using an optical sensor to monitor the water content instantaneously in a fuel pipeline is an effective means of controlling the fuel quality in a combustion system. In two component liquid flows of oil and water, the flow pattern and characteristics of water droplets are changed with various flow conditions. Additionally, the light scattering of the optical sensor measuring the water content is also dependent on the flow patterns and droplet characteristics. Therefore, it is important to investigate the detailed behavior of water droplets in the pipeline of the fuel transportation system. In this study, the flow patterns and characteristics of water droplets in the turbulent pipe flow of two component liquids of gasoline and water were investigated using optical measurements. The dispersion of water droplets in the gasoline flow was visualized, and the size and velocity distributions of water droplets were simultaneously measured by the phase Doppler technique. The Reynolds number of the gasoline pipe flow varied in the range of $4{\times}10^{4}\;to\;1{\times}10^{3}$, and the water content varied in the range of 50 ppm to 300 ppm. The water droplets were spherical and dispersed homogeneously in all variables of this experiment. The velocity of water droplets was not dependent on the droplet size and the mean velocity of droplets was equal to that of the gasoline flow. The mean diameter of water droplets decreased and the number density increased with the Reynolds number of the gasoline flow.

• Journal of Pharmaceutical Investigation
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• 제40권6호
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• pp.353-356
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• 2010

Although liposomes have been applied as drug delivery systems in various fields, the usage was limited due to the low encapsulation efficiency compared to other carrier systems. Here, cationic liposomes were prepared by mixing 1,2-dioleoyl-3-trimethylammoniopropane (DOTAP) as a cationic lipid, 1,2-dioleoyl-sn-glycerol-phosphoethanolamine (DOPE) and cholesterol (CH), and the liposomes were hydrated by varying the aqueous phases such as phosphate-buffered saline (PBS), 5% dextrose, and 10% sucrose in order to improve the encapsulation efficiency of bovine serum albumin (BSA). The particle size and zeta potential were determined by dynamic light scattering method and in vitro release patterns were investigated by spectrophotometry. Particle size and zeta potential of liposomes were varied depending on the ratio of DOTAP/DOPE/CH in range of 270-350 nm and 0.8-9.7 mV, respectively. Moreover, the addition of polyethylene glycol (PEG) improved the encapsulation efficiency from 37% to 43% as well as reduced particle sizes of liposomes while the liposomes were hydrated in PBS. When the liposomes were hydrated with 10% sucrose, the encapsulation efficiency of BSA was higher than any other groups. Whereas PBS was used as hydration solution, lower encapsulation efficiency was obtained compared with other groups. More than 60% of BSA was released from the liposomes hydrated with 10% sucrose; thereafter another 20% of BSA was released. Therefore, release pattern of BSA from cationic liposomes was extended release in this study. From the results, cationic liposomes dispersed in 10% sucrose would be potential carrier with high encapsulation efficiency.

• 한국재료학회지
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• 제29권2호
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• pp.116-120
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• 2019

We prepared $Y_3Al_5O_{12};Ce^{3+},Pr3^{+}$ transparent ceramic phosphor using a solid state reaction method. By XRD pattern analysis and SEM measurement, our phosphors reveal an Ia-3d(230) space group of cubic structure, and the transparent ceramic phosphor has a polycrystal state with some internal cracks and pores. In the Raman scattering measurement with an increasing temperature, lattice vibrations of the transparent ceramic phosphor decrease due to its more perfect crystal structure and symmetry. Thus, low phonon generation is possible at high temperature. Optical properties of the transparent ceramic phosphor have broader excitation spectra due to a large internal reflection. There is a wide emission band from the green to yellow region, and the red color emission between 610 nm and 640 nm is also observed. The red-yellow phosphor optical characteristics enable a high Color Rendering Index (CRI) in combination with blue emitting LED or LD. Due to its good thermal properties of low phonon generation at high temperature and a wide emission range for high CRI characteristics, the transparent ceramic phosphor is shown to be a good candidate for high power solid state white lighting.

• 센서학회지
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• 제10권1호
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• pp.62-70
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• 2001

CBD방법으로 성장하여 $450^{\circ}C$로 열처리한 ZnSe 박막은 회전 무늬로부터 외삽법으로 구한 격자상수 $a_0$가 $5.6678\;{\AA}$인 zinc blend임을 알았다. Van der Pauw 방법으로 측정한 Hall 데이터에 의한 이동도는 10 K에서 150 K 까지는 불순물 산란 (impurity scatterimg)에 의하여, 150 K에서 293 K까지는 격자산란 (lattice scattering)에 의하여 감소하는 경향을 나타냈다. 또한 운반자 농도의 ln n대 1/T에서 구한 활성화 에너지($E_a$)는 0.27 eV였다. 투과 곡선의 투과단으로 본 띠 간격은 293 k에서 $2,700{\underline{5}}\;eV$이었던 것이 10K에서는 $2.873{\underline{9}}\;eV$로 변하였다. 광전류 봉우리 위치를 투과단과 비교할 때 293 K에서 30 K까지 관측된 한 개의 봉우리는 가전자대 ${\Gamma}_8$에서 전도대 ${\Gamma}_6$로 전이에 의한 광전류 봉우리이고, 10K에서 관측된 단파장대 417.3 nm($2.971{\underline{4}}\;eV$)의 봉우리는 가전자대 ${\Gamma}_7$에서 전도대 ${\Gamma}_6$로, 431.5 nm($2.873{\underline{3}}\;eV$)의 봉우리는 가전자대 ${\Gamma}_8$에서 전도대 ${\Gamma}_6$로 전이에 의한 광전류 봉우리가 관측된 것으로 판단된다. 광전류 봉우리의 10K에서 단파장대의 가전자대 갈라짐(splitting)에 의해서 측정된 ${\Delta}so$(spin orbit coupling)는 $0.098{\underline{1}}\;eV$ 였다. 10 K에서 광발광 봉우리의 440.7 nm($2.812{\underline{7}}\;eV$)는 자유 엑시톤(free exciton : $E_x$), 443.5 nm ($2.795{\underline{5}}\;eV$)는 주개-얽매인 엑시톤(donor-bound exciton) 인 $I_2(D^0,\;X)$와 445.7 nm ($2.781{\underline{8}}\;eV$)는 반개-얽매인 엑시톤(acceptor-bound exciton) 인 $I_1(A^0,X)$이고, 460.5 nm ($2.692{\underline{3}}\;eV$)는 주개-받개쌍(donor-acceptor pair:DAP) 발광, 580 nm ($2.137{\underline{6}}\;eV$)는 self activated(A)에 기인하는 광발광 봉우리로 분석된다.

• 한국산업보건학회지
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• 제17권1호
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• pp.13-20
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• 2007

This study was performed to investigate the concentrations of PM($PM_{10}$, $PM_{2.5}$, $PM_{1}$) and it's affecting factors in the subway from line 1 to line 8 in Seoul metropolitan area, from Sep. 1 to 30, 2005. PM concentrations were measured at the entrances and centers in subway passenger cabins by a light scattering equipment. And the affecting factors to PM were estimated based on the number of passenger, door open and close and running area etc. The geometric means of $PM_{10}$, $PM_{2.5}$ and $PM_{1}$ concentration in Seoul subway passenger cabins were $214{\mu}g/m^3$, $86.6{\mu}g/m^3$ and $27.0{\mu}g/m^3$, respectively. These mean concentrations in subway carriage were higher when it ran on an underground track than on a ground track. And running time(7AM-9AM, 11AM-13PM, 6PM-8PM) significantly influenced to the concentrations of $PM_{10}$, $PM_{2.5}$ and $PM_{1}$. Daily profile of $PM_{10}$ and $PM_{2.5}$, $PM_{1}$ expressed as an 10 minutes average, showed similar variation pattern over day period. In correlation analysis, significant relations among $PM_{10}$, $PM_{2.5}$ and $PM_{1}$ were detected(p〈0.01). In particular, correlation coefficient between $PM_{10}$and $PM_{1}$ was highly significant(r=0.94). Further study is needed to identity the sources of PM in subway cabins and to compare pollutants concentration among subway lines.

• 한국정보통신학회논문지
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• 제17권2호
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• pp.423-430
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• 2013

최근 손등이나 손바닥, 손가락의 정맥 혈관 패턴정보를 이용하여 개인을 인증하는 기술은 훼손, 복제 및 위조가 불가능하다는 장점으로 인해 연구가 활발하게 진행 중이다. 정맥영상은 피부층과 내부 골격등에 의한 빛의 산란 및 불균일한 내부 조직 때문에 정맥 영역이 뚜렷하게 나타나지 않아, 영상처리 방법을 통해 정맥 영역을 정확하게 분리하는 것이 어렵다. 특히 한 장의 영상에서도 밝기가 균일하지 않아서 지역 영역 단위로 다른 이진 임계치를 사용함으로 인해 처리시간이 오래 걸리고 혈관의 불연속면이 발생한다는 문제가 있다. 이를 해결하기 위해 본 논문에서는 조명 정규화 기반의 고속 정맥 영역 추출 방법을 제안한다. 본 연구는 기존의 방법에 비해 다음과 같은 장점을 가지고 있다. 첫째, 정맥영상의 불균일한 조명을 제거하기 위해 저역통과필터를 통해 조명 성분을 취득하고 이를 통해 조명성분이 균일한 영상을 얻었다. 둘째, 조명 정규화 영상으로부터 단일 임계치를 통해 얻어진 이진 영상의 처리를 통해 혈관 경로를 추출함으로써, 처리시간을 단축하였다. 실험을 통해 기존 방법들에 비해 혈관 영역 추출 정확도가 상승하고, 처리속도가 단축된 결과를 얻을 수 있었다.

• 한국광학회지
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• 제11권4호
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• pp.271-278
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• 2000

광가입자용 광원으로서 유망한 모드변환기가 집적된 1.3$\mu\textrm{m}$ SSC-FP-LD를 저압 MOVPE결정성장법을 사용해 제작하고 이의 특성을 분석하였다. SSC-LD의 활성영역과 SSC영역은 BJB방법으로 접합하였으며 taper형 도파로 구조를 선택성장법으로 성장하였다. 제작한 SSC-LD의 특성을 측정한 결과 SSC 단면으로 부터의 미분효율 0.23~0.32 mW/mA, FFP의 FWHM값은 9.5$^{\circ}$~12.3$^{\circ}$, 단일모드 광섬유와의 광결합 시 추가광결합손실 -1dB 범위내에서 수평방향으로 $\pm$2.5$\mu\textrm{m}$ 및 수직방향으로 $\pm$2.3$\mu\textrm{m}$의 정렬오차 허용도 등과 같은 양호한 특성을 얻었다. SSC-LD의 문제점들을 이해하고 SSC-LD의 성능향상에 대한 지침을 얻고자 방사모드를 고려한 SSC-LD특성 해석을 행하였다. 해석결과 SSC-LD에서의 비대칭 광출력특성, FFP과 SSC영역단면 근처의 도파로 구조와 비상관성, 온도특성열화 등은 BJB 및 SSC영역내의 불균일한 도파로 구조에 의해 발생되는 방사모드와 두 영역 사이의 좋지 못한 광결합 효율에 의해 발생되는 SHB현상에 기인함을 처음으로 지적하였다.

• 자원환경지질
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• 제20권2호
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• pp.85-95
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• 1987

The host rocks of titaniferous magnetite deposits in Gonamsan are alkaline gabbros, which are typical of undersaturated alkaline rocks in terms of the lack of normative quartz. According to field occurrences and petrographic features, these alkaline gabbros are divided into 3 rock types: coarse-grained and pegmatitic rock, medium-grained rock with equigranular texture, and layered cumulate rock. All these rocks mainly contain clinopyroxene(salite), plagioclase(An 43-66), pargasite, and ilmenite. The accessory minerals are apatite, sphene, quartz, and sometimes titaniferous magnetite. Pargasite, sphene, and quartz are considered to be secondary minerals formed by the reaction among clinopyroxene, plagioclase and Fe-Ti oxide at deuteric stage. Fe-Ti oxides generally occur as ilmenite in the alkaline rocks, and titaniferous magnetite in the ore deposits. Layered cumulate rocks are characterized by a recurrence of discontinuous thin mesolayer of clinopyroxene-pargasite within leucolayer mainly composed of plagioclase. Clinopyroxene is cumulus mineral whereas plagioclase, ilmenite and apatite occur as intercumulus minerals. According to the variation diagrams of oxide and trace element contents against the differentiation index, incompatible elements, such as Na, Ba and Sr, show positive correlations whereas compatible elements, such as Mg and Cr, show negative correlations. However some compatible elements, such as Co, Ni and V show irregular variations, reflecting relative cumulate status of cumulus and intercumulus minerals. On the de la Roche multicationic diagram, these alkaline gabbros are distributed along the differentiation curve of undersaturated alkaline series from alkaline basaltic composition through basanitic composition to tephritic composition. Layered cumulate rocks, which are distributed between basanitic composition and tephritic composition, reflect their cumulate character, slightly scattering away from the curve. The medium-grained rock shows higher contents in Ba, Sr and light rare earch elements than the coarse-grained and pegmatitic rock. The former shows two times higher contents of total rare earth elements than the latter, $while(La/Lu)_{cn}$ ratios maintain fairly constant values of 5.08~5.06 in these two rocks. This means that coarse-grained and pegmatitic rock, as compared with the medium-grained rock, was formed by the earlier differentiated magma but rare-earth element distribution pattern remained almost parallel during differentiation. From the data the above mentioned, these alkaline gabbros are considered to be comagmatic and to be formed by intrusions of differentiated magmas in its reservoir.