• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.62-62
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• 2000

비접촉식 온도센서는 물체에서 방출하는 적외선 등의 복사신호를 열에너지로 전환하고 이를 다시 전기신호로 2차 에너지 변환하여 온도를 감지하는 센서로 인체 검지를 응용한 다양한 상품 및 교통, 방재, 빌딩 시스템 등의 분야에 널리 응용되고 있다. 비접촉식 적외선 센서는 열에너지를 전기에너지로 변환하는 방법에 따라 양자형과 열형으로 구분되며, 이중 양자형은 광전도나 광기전력 효과 등을 이용하여 감도 및 응답성이 우수하다는 장점을 지니고 있지만, 소자부를 80K 이하 온도로 유지시키는 냉각을 필요로 하므로 대형 제작이 불가피하고 그 용도가 제한적이다. 열형은 냉각이 필요 없고 소형으로 제작가능한 장점을 지니고 있어 써모 파일이나 초전체를 이용한 번용 센서가 보급되고 있다. 그러나 써모파일의 경우 출력되는 전기 신호가 미약하여 감도 및 응답성을 향상하기 위해 구조가 복잡하고, 특히 모터초퍼나 저항을 전압으로 변환시키는 전력기 등이 필요로 하는 단점을 지니고 있다. 따라서 이러한 문제점을 보완하기 위해 열전재료 박막을 이용한 적외선 센서를 개발하려는 노력이 진행중에 있다. 열전박막을 이용한 적외선 센서는 열전재료의 Seebeck 현상을 이용하여 열에너지에서 전기에너지의 변환이 자가발전으로 이루어져 offset과 외부 바이어스를 필요로 하지 않는다. 또한 작은 온도 변화에도 그 감도와 응답성이 높고, 출력신호가 커서 증폭기 등이 불필요한 장점을 지니고 있다. 특히 초전형 센서가 상온에서도 기판에 대한 열 확산을 제어해야 하는 문제점을 갖는 반면, 열전박막형 적외선 센서는 고온에서도 안정된 출력 신호를 얻을 수 있어 그 활용 온도 범위가 크게 확대될 것으로 기대된다. 본 실험에서는 우수한 열전특성을 갖는 (Bi1-xSbx)2Te3 박막을 얻기 위해 열팽창계수가 작고 알칼리 원소가 0.3% 이하로 포함되어 있는 corning glass(# 7059)를 기판으로 사용하였다. 또한 최적의 열전특성을 나타내는 조성을 실험적으로 구하기 위해 (Bi0.2Sbx)2Te3 조성의 합금 타？ 위에 Bi2Te3 및 Sb2Te3 chip을 올려놓고 그 면적을 변화시켜 다양한 조성의 열전박막을 증착하였다. 열전박막의 증착시 산화와 오염에 의한 열전특성 변화를 최소화하기 위해 초기진공도를 1$\times$10-6 Torr로 하였으며, Ar 가스를 흘려주어 2$\times$102 Torr 의 증착진공도를 유지하였다. 열전박막을 증착하기 전에 기판을 10분간 200W의 출력으로 RF 처리하였으며, 30$0^{\circ}C$에서 33 /sec의 속도로 (Bi1-xSbx)2Te3 박막을 증착하였다. 이와 같이 제조된 (Bi1-xSbx)2Te3 박막의 미세구조를 SEM으로 관찰하고 EDS로 조성을 분석하였으며, XRD를 이용하여 결정성을 관찰하였다. 또한 (Bi1-xSbx)2Te3 박막의 Seebeeck 계수 및 전기비저항을 측정하고 증착된 박막조성, 결정상, 미세구조와 열전특성간의 상관관계를 고찰하였다.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.768-771
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• 2005

The deposition of silicon nitride ($SiN_x$) thin films was carried out on $SiO_2/Si$ substrate at room temperature by reactive dc magnetron sputtering. The analysis of deposited $SiN_x$ films using x-ray photoelectron spectroscopy indicated that the composition of $SiN_x$ films was Si-rich. The deposited $SiN_x$ thin films were annealed by varying annealing temperature and time. X-ray diffraction (XRD) analysis was performed in order to examine the crystallization of Si in $SiN_x$ thin films. The optical and electrical properties of $SiN_x$ thin films were measured for the observation of Si nanodot. As a result, we observed the XRD peaks that might be the Si crystals. As the annealing time and annealing temperature increased, the photoluminescence intensity of $SiN_x$ films gradually increased. The capacitance-voltage characteristics of $SiN_x$ film measured before and after annealing indicated that the trap effect of electrons or holes occurred due to the existence Si nanodots in the $SiN_x$ thin films.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.14-19
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• 2014

Nanocomposites based on poly(methyl methacrylate) (PMMA)/poly(vinylidene fluoride) (PVDF) and poly(ethylene terephthalate) (PET)/(PVDF) blended with carbon fibers (CF) and carbon nanotube (CNT) were prepared by melt mixing in the twin screw extruder. Morphologies of the PMMA/PVDF/CF/CNT and PET/PVDF/CF/CNT nanocomposites were investigated using SEM. The aggregation of CNT was observed in PMMA/PVDF/CF/CNT nanocomposites while the good dispersion of CNT was shown in PET/PVDF/CF/CNT nanocomposites. In SEM image of PET/PVDF/CF/CNT nanocomposite, the CNT were mainly located at the PET domain of phase-separated PET/PVDF blend due to the ${\pi}-{\pi}$ interaction between the phenyl ring of PET and graphite sheet of the CNT's surface. In addition, a fairly good compatibility between PET/PVDF matrix and CF was shown in the SEM image. In the case of PET/PVDF nanocomposites blended with the co-addition of CF and CNT, the volume electrical resistivity decreased while no change was observed in PMMA/PVDF/CF/CNT composites. The degree of CNT dispersion in morphology results was consistent with the electrical conductivity results. From the DSC results, the crystallization temperature (Tc) of PET/PVDF/CF/CNT nanocomposites increased due to the co-addition of CF and CNTs acting as a nucleating agent. Flexural modulus of PET/PVDF/CF/CNT were sharply enhanced due to increasing the interaction between PET and CF.

• Korean Journal of Food Science and Technology
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• v.4 no.2
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• pp.77-83
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• 1972

In order to study the processing adaptability of naked barley, SEDOHADAKA variety produced in Cheolanam-do(1971) was milled after polishing and examined with respect to its proximate principles, amino acid composition, viscosity, raising power, and amylose content, alkali number, blue value and X-ray diffraction pattern of its starch. The results are summarized as fllows: 1) Crude fiber content of naked barley which was milled at 81.6% (A), 79.2% (B) and 74.1% (C) was $2.48{\sim}2.36%$, indicating higher level than wheat flour. 2) Whereas the initial gelatinization temperature of naked barley flour was similar to that of wheat flour, the value of naked barley starch was $89.5^{\circ}C$, higher than that of wheat starch, Amylose content of naked barley starch was 28.5%, similar to wheat starch. 3) Raising power of naked barley starch was generally lower than that common cereal starches. 4) According to the X-ray diffraction pattern diagram, the degree of crystallization was lower in naked barley starch than in non-glutinous rice starch.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.27-33
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• 2016

Phenolic resin has excellent heat resistance and good mechanical properties as a thermosetting resin. However, its thermosetting characteristics cause it to produce a non-recyclable waste in the form of sprue and runner which is discarded and represents up to 15~20% of the overall products. Forty thousand tons of phenolic resin sprue and runner are disposed of (annually). The (annual) cost of such domestic waste disposal is calculated to be 20 billion won. In this study, discarded phenol resin scraps were pulverized and treated by silanes to improve their interfacial adhesion with HDPE. The sizes of the pulverized pulverulent bodies and fine particles were (100um~1000um) and (1~100um), respectively. The pulverized phenol resin was treated with 3-(methacryloyloxy) propyltrimethoxysilane and vinyltrimethoxy silane and the changes in its characteristics were evaluated. The thermal properties were evaluated by DSC and HDT. The mechanical properties were assessed by a notched Izod impact strength tester. When the silane treated phenol resin was added, the heat distortion temperature of HDPE increased from $77^{\circ}C$ to $96^{\circ}C$ and its crystallinity and crystallization temperature also increased. Finally, its impact strength and tensile strength increased by 20% and 50%, respectively, in comparison with the non-treated phenol resin.

• Geosciences Journal
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• v.23 no.1
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• pp.1-20
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• 2019

We present data from the Mesozoic Keumkang, Palbong, and Baekhwa granites in Garorim Bay, in the southwestern part of the Gyeonggi massif, South Korea. Using major and trace element concentrations, Sr-Nd-Pb isotopic compositions, and sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb ages, we aim to constrain the petrogenesis of the granites and explain their origin within a broader regional geological context. SHRIMP U-Pb zircon ages of $232.8{\pm}3.2$, $175.9{\pm}1.2$, and $176.8{\pm}9.8$ Ma were obtained from the Keumkang, Palbong and Baekhwa granites, respectively. The Late Triassic Keumkang granites belong to the shoshonite series and show an overall enrichment in large ion lithophile elements (LILE), a depletion in high field strength elements (HFSE) relative to primitive mantle, compared with neighboring elements in the primitive mantle-normalized incompatible trace element diagram with notable high Ba and Sr contents, and negligible Eu anomalies. The Keumkang granites are typified by highly radiogenic Sr and unradiogenic Nd and Pb isotopic compositions: $(^{87}Sr/^{86}Sr)_i=0.70931-0.70959$, $(^{143}Nd/^{144}Nd)_i=0.511472-0.511484$ [$({\varepsilon}_{Nd})_i=-17.0$ to -16.7], and $(^{206}Pb/^{204}Pb)=17.26-17.27$. The Middle Jurassic Palbong and Baekhwa granites belong to the medium- to high-K calc-alkaline series, and show LILE enrichment and HFSE depletion similar to the Keumkang granites, but exhibit significant negative anomalies in Ba, Sr, and Eu. Furthermore, they have elevated Y and Yb contents at any given $SiO_2$ content compared with other Jurassic granitoids from the Gyeonggi massif. The Palbong and Baekhwa granites have slightly less radiogenic Sr and more radiogenic Nd and Pb isotopic compositions [$(^{87}Sr/^{86}Sr)_i=0.70396-0.70908$, $(^{143}Nd/^{144}Nd)_i=0.511622-0.511660$, $({\varepsilon}_{Nd})_i=-15.4$ to -14.7, $(^{206}Pb/^{204}Pb)=17.56-17.76$] relative to the Keumkang granites. The Keumkang granites are considered to have formed in a post-collisional environment following the Permo-Triassic Songrim orogeny that records continent-continent collision between the North and South China blocks, and may have formed by fractional crystallization of metasomatized lithospheric mantle-derived mafic melts. The Palbong and Baekhwa granites may have been produced from a gabbroic assemblage at pressures of less than ~15 kbar, associated with subduction of the paleo-Pacific (Izanagi) plate at the Eurasian continental margin. Elevated ${\varepsilon}_{Nd}(t)$ values in the granitoids from the southwestern part of the Gyeonggi massif relative to those of the central and northern parts, together with the comparatively shallow depth of origin, imply the presence of an exotic block in the Korean lithosphere.

• Bulletin of the Korean Chemical Society
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• v.21 no.11
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• pp.1125-1132
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• 2000

The pH effect of the precursor solution on the preparation of $LiCoO_2$ by a solution phase reaction containing malonic acid was carried out. Layered $LiCoO_2$ powders were obtained with the precursors prepared at the different pHs (4, 7, and 9) and heat-treated at $700^{\circ}C(LiCoO_2-700)$ or $850^{\circ}C(LiCoO_2-850)$ in air. pHs of the media for precursor synthesis affects the charge/discharge and electrochemical properties of the $LiCoO_2electrodes.$ Upon irrespective of pH of the precursor media, X-ray diffraction spectra recorded for $LiCoO_2-850$ powder showed higher peak intensity ratio of I(003)/I(104) than that of $LiCoO_2-700$, since the better crystallization of the former crystallized better. However, $LiCoO_2$ synthesized at pH 4 displayed an abnormal higher intensity ratio of I(003)/I(104) than those synthesized at pH 7 and 9. The surface morphology of the $LiCoO_2-850$ powders was rougher and more irregular than that of $LiCoO_2-700$ made from the precursor synthesized at pH 7 and 9. The $LiCoO_2electrodes$ prepared with the precursors synthesized at pH 7 and 9 showed a better electrochemical and charge/discharge characteristics. From the AC impedance spectroscopic experiments for the electrode made from the precursor prepared in pH 7, the chemical diffusivity of Li ions (DLi+) in $Li0.58CoO_2determined$ was 2.7 ${\times}$10-8 $cm^2s-1$. A cell composed of the $LiCoO_2-700$ cathode prepared in pH 7 with Lithium metal anode reveals an initial discharge specific capacity of 119.8 mAhg-1 at a current density of 10.0 mAg-1 between 3.5 V and 4.3 V. The full-cell composed with $LiCoO_2-700$ cathode prepared in pH 7 and the Mesocarbon Pitch-based Carbon Fiber (MPCF) anode separated by a Cellgard 2400 membrane showed a good cycleability. In addition, it was operated over 100 charge/discharge cycles and displayed an average reversible capacity of nearly 130 mAhg-1.

• The Journal of the Petrological Society of Korea
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• v.3 no.1
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• pp.76-93
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• 1994

The Precambrian Hongjesa granite is lithologically zoned from biotite granite in central part to biotite-muscovite granite towards the margin. The X_{Fe}$ (=Fe/(Fe+Mg)) value and the aluminum saturation index of biotite systematically vary as a function of mineral assemblage, and are positively related with those of bulk rock. This relationship as well as the lithological zoning are attributed to the fractional crystallization of the Hongjesa granitic magma. The trace element data corroborate that biotite-muscovite granite is more fractionated than biotite granite. The evolution of the Hongjesa granite is elucidated by using the AFM liquidus topology, where A=$Al_2O_3-CaO-Na_2O-K_2O$; F=FeO+MnO; and M=MgO. At an early magmatic stage where biotite is the only ferromagnesian mineral to crystallize, the X_{Fe}$ value and the alumina content of granitic magma continuously increase.. Muscovite subsequently crystallizes with biotite along the biotitemuscovite cotectic curve where biotite-muscovite granite forms. Local enrichments in Mn and B further crystallize garnet and tourmaline, respectively. The unique zonal pattern characterized by the occurrence of the evolved biotite-muscovite granite at the margin may be accounted for by the passive stoping during the emplacement of the Hongjesa granite. This emplacement may have occurred in continental collision environment, according to the tectonic discrimination diagram using major element chemistry.

• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.76-81
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• 2012

Silk protein has been explored to be used for biomedical applications for several decades. However, it has not been used in this field cause to their irreversible crystallization after dissolving in water. The existing methods of silk protein hydrolysis using silkworm cocoon were used with harmful solvents and through a very complicated process. Therefore, we have developed novel methods for the production of water-soluble hydrolysate using silkworm gland. We manufactured two types of silkworm gland-derived hydrolysate (water-soluble SGH, SSGH; total SGH, TSGH) and compared the characteristics with commercial cocoon-derived sericin hydrolysate (CSH). The molecular weight of SGH ranged from 7 to 50 kDa (SSGH) and 5 to 15 kDa (TSGH) within glycine, alanine, and aspartic acid as a main amino acid composition. In contrast, CSH ranged from 15 to 50 kDa within serine and aspartic acid. The results of FTIR implied that SGH was more soluble form than CSH, as shown by the decrease in the ${\beta}$-sheet structure at $1630cm^{-1}$ on amide I peak. In comparison with 10% fetal bovine serum, 0.1% (1 mg/ml) SSGH had equivalent effect on the proliferation of human dermal fibroblasts and mesenchymal stem cells. All results of the SSGH made by novel manufacturing process indicate the SSGH is more preferable as a culture medium supplement than cocoon-derived sericin.

• Clean Technology
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• v.25 no.1
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• pp.33-39
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• 2019

A.C (activated carbon) is mainly used to remove VOCs (volatile organic compounds), however, it has many problems such as fire risk due to increasing of adsorbent surface temperature during VOCs ad/desorption, increased cost by frequent replacement cycles requirement and performance degradation when containing moisture. In order to solve these problems, many researches, hydrophobic zeolite adsorbents, have been reported. In this study, $NH_4{^+}Y$-zeolite was synthesized with Y-zeolite through steam treatment and acid treatment, which is one of the hydrophobic modification methods, to secure high surface area, thermal stability and humidity resistance. The Y, Y-550-HN, Y-600-HN and Y-650-HN had adsorption capacities of $23mg\;g^{-1}$, $38mg\;g^{-1}$, $77mg\;g^{-1}$, $61mg\;g^{-1}$. The change of Si/Al ratio, which is an index to confirm the degree of modification, was confirmed by XRF (X-ray fluorescence spectrometer) analysis. As a result, the adsorbtion performance was improved when Y-zeolite modified, and the Si/Al ratio of Y, Y-550-HN, Y-600-HN, Y-650-HN were increased to 3.1765, 6.6706, 7.3079, and 7.4635, respectively. Whereas it was confirmed that structural crystallization due to high heat treatment temperature affected performance degradation. Therefore, there is an optimal heat treatment temperature of Y-zeolite, optimum modification condition study could be a substitute for activated carbon as a condition for producing an adsorbent having high durability and stability.