• 자원환경지질
• /
• 제26권3호
• /
• pp.337-347
• /
• 1993

Mineralogical and geochemical studies on some pyrophyllite deposits in Milyang area, Kyeongnam Province (Milyang and Sungjin mine) were carried out in order to investigate dispersion patterns of chemical elements in altered volcanic wallrocks, and to interpret genetic environments of the pyrophyllite deposits. Cretaceous andesitic and tuffaceous rocks, and pyrophyllite ore specimens were collected from the dumps and drilling cores. Andesitic wallrocks were grouped as unaltered and altered rocks in the order of pyrophyllitization. Vertical dispersion patterns and relative mobilities of chemical elements in volcanic wallrocks were discussed. Geochemical environment in the Milyang area is characterized by the occurrence of boron minerals such as dumortierite coexisting with pyrophyllite ores, and tourmaline in granitic rocks. Unaltered andesitic rocks are mainly composed of plagioclase, pyroxene and hornblende, and were propylitized and saussuritized. Altered andesitic rocks are bleached and consist of quartz, sericite, pyrophyllite, kaolinite, chlorite and disseminated pyrite. Pyrophyllite ores are mainly composed of quartz, pyrophyllite, dumortierite, dissemianted pyrite and some diaspore. Enrichment of $SiO_2$, $Al_2O_3$, LOI (loss on ignition), As and Cr, and depletion of $K_2O$, $Na_2O$, CaO, MgO and total Fe are characteristic during alteration process. The REE patterns show that the pyrophyllite deposits could be originated from the continental margin volcanics. The $(La/Lu)_{cn}$ ratios of the pyrophyllite ores increase from 4.2~23.2 to 2.67~128.8 owing to strong acidic hydrothermal alteration. Vertical dispersion patterns of $Al_2O_3$, $K_2O$, $Na_2O$, CaO, MgO, $Fe_2O_3$ (total Fe), As, Au, Sb, Cr and Sr in the wallrocks show the location of orebodies. Particularly dispersion patterns of $Al_2O_3$ and Cr indicate the extension of orebodies. Anomalous distribution of Au, As and Sb in wallrocks shows potential for gold occurrence below the pyrophyllite deposits. Judging from the relative mobilities of elements in wallrocks, $Al_2O_3$ could be added from hydrothermal solution, and the silicified rone be formed from the excess of $SiO_2$.

• 대한소아치과학회지
• /
• 제38권1호
• /
• pp.62-67
• /
• 2011

치아의 맹출은 일반적으로 치근의 1/2~2/3이 완성(Nolla stage 7)되었을 때 임상적으로 출은(emergence)하여 치근 형성이 완성되기 전에 교합평면에 도달한다. 조기 맹출이란 맹출이 가속화되어 정상 맹출 시기 보다 이른 시기에 맹출하는 것으로, 일반적으로 정상 범주를 벗어나는 영구치의 조기 맹출은 매우 드물며 유치의 만성 치근단 주위염 등의 국소적 원인으로 인한 계승 영구치의 상방 치조골이 광범위하게 파괴되었을 때 치아의 치관이나 치근의 형성이 거의 이루어지지 않은 채 계승 영구치가 조기 맹출하는 것을 관찰할 수 있다. 또한 영구치의 조기 맹출에 영향을 미칠 수 있는 여러 전신 질환이 있는 경우에도 영구치의 조기 맹출이 가능하다. 조기맹출 치아의 임상 소견으로는 심한 동요도와 저작 시 동통, 법랑질의 저석회화, 치아의 편향과 변위, 회전 등이 있으며, 방사선학적 소견으로는 미발육된 치근과 골지지의 부족 등이 있다. 조기 맹출 영구치의 발생 가능한 합병증으로는 만성적인 외상과 동통 및 부종이 있을 수 있고, 맹출 순서의 변경과 인접치의 이동으로 인한 소구치 매복율의 증가, 치아의 변위와 회전이 야기될 수 있으며, 영구치의 탈락도 있을 수 있다. 따라서 증상이 있는 조기 맹출 영구치의 경우 공간 유지 및 영구치 고정과 주위 조직의 회복, 치근 발육의 유도를 위해 적절한 처치가 필요하다. 전신 질환이 없는 만7세 여환이 상악 양쪽 제 1소구치의 심한 동요도와 동통을 주소로 치과 의원에서 의뢰되었다. 임상 및 방사선 검사상 치근 형성이 거의 없이 양측 상악 제 1소구치들이 조기 맹출되어 심한 동요도와 부종 및 저작 시동통을 나타내어 상악 제 2유구치에 교정용 band와 spur를 이용한 구내 고정식 장치를 제작하여 14개월 간 장착하여 조기 맹출한 치아들을 안정화시키고 성공적으로 치근 형성을 도모하였기에 이를 보고하는 바이다.

• 대한전자공학회논문지
• /
• 제5권1호
• /
• pp.1-5
• /
• 1968

GaAs의 단결정은 Ga의 용액으로부터 epitaxial 방법으로 성장시키는데 300°K에서는 carrier concentration 10 /㎤에서 electron-mobility 7,500∼9,300㎠/V-sec. 정도의 것이 얻어지며 77°K에서는 electron-mobility 50,000∼95,000㎠/V-sec.의 것이 얻어진다. mobility-온도 관계곡선의 이론적인 것과 실험적인 것을 비교해 보면 77°K에서 430°K의 온도범위내에서 ion화한 불순물과 phonon이 주요한 scattering mechanism이라는 것을 나타낸다. 이것은 epitaxial층이 mobility를 제한하는 다른 결함을 별로 내포하지 않는다는 것을 의미한다. epitaxial층의 photoluminescence spectra는 심부에 존재하는 결함의 준위에 의한 방출을 나타내지 않는다.

• 한국결정성장학회지
• /
• 제9권2호
• /
• pp.207-211
• /
• 1999

가스원 분자선 에피택시(GS-MBE)로 성장시킨 $Si/Si_{1-x}Ge_x$ MODFET의 미세조직을 투과식 전자현미경과 간섭광학현미경을 이용하여 관찰하였다. 증착온도변화에 따른 불일치전위의 분포에 큰 변화는 없었지만, 증착온도가 높을수록 표면조도가 거칠어졌고 표면 결함이 나타났다. Si 전기활성층 근처에서는 조성경사기능층보다 전위밀도가 상당히 낮았다. 결정성장 온도를 낮춤에 따라 전기이동도는 증가하였다.

• 한국결정성장학회지
• /
• 제1권1호
• /
• pp.17-25
• /
• 1991

The construction details of VGF apparatus with a DM(direct monitoring) furnace for the growth of low defect crystal and characteristics of GaAs crystal grown by this apparatus are described. The average dislocation densities and EL2 concentration of as-grown undoped GaAs along the different solidified fractions exhibit $4{\times}10^{2}-7{\times}10^{3}cm^{-2}$ and $6{\times}10^{14}-4{\times}10^{15}cm^{-3}$, which are less than those observed for liquid encapsulated Czochralski(LEC) or high-pressure vertical gradient freeze(VGF) crystals. These remarkable reduction of the dislocation densities and EL2 concentrations were explained by the lower temperature gradient ($dT/dx-10^{\circ}/cm$) and slower rates of post - growth cooling ($20^{\circ}C/hr:1240-1000^{\circ}C,\;30^{\circ}C/hr:1000-700^{\circ}C$). Also, The Hall mobilities, carrier concentrations show uniform distribution throughtout 80% of the ingot length.

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

• 한국환경성돌연변이발암원학회지
• /
• 제18권2호
• /
• pp.83-88
• /
• 1998

To detect the mutation in a given sequence, there are variety of methods developed by use of the gel electrophoresis. One of the methods, TGGE (Temperature Gradient Gel Electrophoresis), is a popular technique because it can detect mutations in DNA fragment with ease and at low cost. This study used 200 bp BamHI-digested DNA fragment containing the human $\varepsilon$-globin promoter which was mutated[$\varepsilon$ F1*(-141), GATA- I*(-163), and GATA-1* & $\varepsilon$F1]. This BamHI-digested DNA fragment was directly used to detect the mutated DNA fragment on 50% denaturant gel with temperature gradient of 45$^{\circ}C$ through $53^{\circ}C$. In agreement with the theoretical result of MELTSCAN program (Brossette and Wallet, 1994) the mobilities of mutated DNA fragments were shown to be nearly distinguished on the temperature gradient gel. In contrast to the above result the heteroduplex analysis under the temperature gradient condition was shown to detect the mutated DNA fragments through the heteroduplex formation between strands of mutated DNA and wild-type DNA.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.93-94
• /
• 2009

The influences of $O_2$ partial pressure on electrical properties of transparent semiconducting indium zinc tin oxide thin films deposited at room temperature by magnetron sputtering have been investigated. The experimental results show that by varying the $O_2$ partial pressure during deposition, electron mobilities of IZTO thin film can be controlled between 7 and $25\;cm^2/Vs$. For conducting films, the carrier concentration and resistivity are ${\sim}\;10^{21}\;cm^{-3}$ and ${\sim}\;10^{-4}\;{\Omega}\;cm$, respectively. Concerning semiconducting films, under 12% $O_2$ partial fraction, the electron concentration is $10^{18}\;cm^{-3}$, showing the promising candidate for the application of transparent thin film transistors.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.199-200
• /
• 2009

This paper describes the electrical properties of polycrystalline (poly) 3C-SiC thin films with different nitrogen doping concentrations. The in-situ-doped poly 3C-SiC thin films were deposited by using atmospheric-pressure chemical vapor deposition (APCVD) at $1200^{\circ}C$ with hexamethyldisilane (HMDS: $Si_2$ $(CH_3)_6)$ as a single precursor and 0 ~ 100 sccm of $N_2$ as the dopant source gas. The peaks of the SiC (111) and the Si-C bonding were observed for the poly 3C-SiC thin films grown on $SiO_2/Si$ substrates by using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analyses, respectively. The resistivity of the poly 3C-SiC thin films decreased from $8.35\;{\Omega}{\cdot}cm$ for $N_2$ of 0 sccm to $0.014\;{\Omega}{\cdot}cm$ with $N_2$ of 100 sccm. The carrier concentration of the poly 3C-SiC films increased with doping from $3.0819\;{\times}\;10^{17}$ to $2.2994\;{\times}\;10^{19}\;cm^{-3}$, and their electronic mobilities increased from 2.433 to $29.299\;cm^2/V{\cdot}S$.

• 한국전기전자재료학회논문지
• /
• 제11권11호
• /
• pp.1007-1013
• /
• 1998

In this paper, the dielectric properties of fabricated Polyvinylidene fluoride(PVDF, $PVF_2$) thin film with substrate temperature from 30 to at vapor deposition. The dielectric properties of PVDF thin film had been studied in the frequency range from 10Hz to 4MHz at measuring temperature between 20 and $100^{/circ}C$. The anomalous increasing in dielectric constant and dielectric loss at low frequencies and high temperature was described for PVDF thin film containing ion impurities. In particularly, ion mobility of fabricated PVDF thin film at substrate temperature at $30^{/circ}C$ decrease from $2\times10^{-5}\;to\;3.07$\times10^{-7}cm^2/V.s$ On the other hand, ion density increase abruptly from 1.49\times$$10^{13}$ to $1.5\times$10^{16}$cm^{-3}$ In spite of decreasing of ion mobility, dielectric constants and dielectric loss for PVDF thin film increase rapidly with decreasing frequency and high temperature. It was concluded that the dielectric constants and dielectric loss was related to ion density than to ion mobility at low frequency and high temperatures.