• 한국재료학회지
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• 제15권10호
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• pp.626-631
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• 2005

GaN-related compound semiconductors were grown on the corrugated interface substrate using a metalorganic chemical vapor deposition system to increase the optical power of white LEDs. The patterning of substrate for enhancing the extraction efficiency was processed using an inductively coupled plasma reactive ion etching system and the surface morphology of the etched sapphire wafer and that of the non-etched surface were investigated using an atomic force microscope. The structural and optical properties of GaN grown on the corrugated interface substrate were characterized by a high-resolution x-ray diffraction, transmission electron microscopy, atomic force microscope and photoluminescence. The roughness of the etched sapphire wafer was higher than that of the non-etched one. The surface of III-nitride films grown on the hemispherically patterned wafer showed the nano-sized pin-holes that were not grown partially. In this case, the leakage current of the LED chip at the reverse bias was abruptly increased. The reason is that the hemispherically patterned region doesn't have (0001) plane that is favor for GaN growth. The lateral growth of the GaN layer grown on (0001) plane located in between the patterns was enhanced by raising the growth temperature ana lowering the reactor pressure resulting in the smooth surface over the patterned region. The crystal quality of GaN on the patterned substrate was also similar with that of GaN on the conventional substrate and no defect was detected in the interface. The optical power of the LED on the patterned substrate was $14\%$ higher than that on the conventional substrate due to the increased extraction efficiency.

• 한국세라믹학회지
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• 제50권1호
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• pp.18-24
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• 2013

This study was conducted to recycle fly ash containing an abundance of CaO generated from combustion in a circulating layer as a carbon storage medium. The study utilized XRD, TG-DTA and XRF analyses during the hydration of fly ash and identified calcium substances within fly ash that could be used in a carbonation process. $Ca^{2+}$ ions in the calcium substances were easily converted to hydrates. A carbonation experiment was done, which used the method of $CO_2$ gas injection to produce suspensions by mixing fly ash with distilled water. The results were analyzed using TG-DTA, XRD, and pH meter measurements. The study was able to verify that the reaction was completed at a $CO_2$ flow rate of 300cc/min approximately 30 minutes after an injection into a solution with a solid-liquid ratio of 1 : 10 of fly ash and distilled water. Moreover, the stirring time of the suspensions did not influence the reaction, and the reaction time was found to diminish as the portion of the fly ash became smaller. Thus, this study produced carbon storage fly ash having a $CO_2$ storage rate of about 71% through the utilization of the CaO content contained within fly ash.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.557-565
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• 2014

We report the effect of basal-plane stacking faults (BSFs) on X-ray diffraction (XRD) of non-polar (11$\underline{2}$0) a-plane GaN films with different $SiN_x$ interlayers. Complete $SiN_x$ coverage and increased three-dimensional (3D) to two-dimensional (2D) transition stages substantially reduce BSF density. It was revealed that the Si-doping profile in the Si-doped GaN layer was unaffected by the introduction of a $SiN_x$ interlayer. The smallest in-plane anisotropy of the (11$\underline{2}$0) XRD ${\omega}$-scan widths was found in the sample with multiple $SiN_x$ layers, and this finding can be attributed to the relatively isotropic GaN mosaic resulting from the increase in the 3D-2D growth step. Williamson-Hall (WH) analysis of the (h0$\underline{h}$0) series of diffractions was employed to determine the c-axis lateral coherence length (LCL) and to estimate the mosaic tilt. The c-axis LCLs obtained from WH analyses of the present study's representative a-plane GaN samples were well correlated with the BSF-related results from both the off-axis XRD ${\omega}$-scan and transmission electron microscopy (TEM). Based on WH and TEM analyses, the trends in BSF densities were very similar, even though the BSF densities extracted from LCLs indicated that the values were reduced by a factor of about twenty.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.467-468
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• 2009

For the manufacture of the $CuGaS_2$, Cu, Ga and S were vapor-deposited in the named order. Among them, Cu and Ga were vapor-deposited by using the Evaporation method in consideration of their adhesive force to the substrate so that the composition of Cu and Ga might be 1 : 1, while the surface temperature having an effect on the quality of the thin film was changed from R.T.[$^{\circ}C$] to $150[^{\circ}C$] at intervals of 50[$^{\circ}C$]. As a result, at 300[$^{\circ}C$]of the Annealing temperature, their chemical composition was measured in the proportion of 1 : 1 : 2. It could be known from this experimental result that it is the optimum condition to conduct Annealing on the $CuGaS_2$ thin film under a vacuum when the $CuGaS_2$ thin film as an optical absorption layer material for a solar cell is manufactured.

• Toxicological Research
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• 제32권2호
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• pp.103-108
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• 2016

The purpose of this study was to determine the hair growth effects of lavender oil (LO) in female C57BL/6 mice. The experimental animals were divided into a normal group (N: saline), a vehicle control group (VC: jojoba oil), a positive control group (PC: 3% minoxidil), experimental group 1 (E1: 3% LO), and experimental group 2 (E2: 5% LO). Test compound solutions were topically applied to the backs of the mice ($100{\mu}L$ per application), once per day, 5 times a week, for 4 weeks. The changes in hair follicle number, dermal thickness, and hair follicle depth were observed in skin tissues stained with hematoxylin and eosin, and the number of mast cells was measured in the dermal and hypodermal layers stained with toluidine blue. PC, E1, and E2 groups showed a significantly increased number of hair follicles, deepened hair follicle depth, and thickened dermal layer, along with a significantly decreased number of mast cells compared to the N group. These results indicated that LO has a marked hair growth-promoting effect, as observed morphologically and histologically. There was no significant difference in the weight of the thymus among the groups. However, both absolute and relative weights of the spleen were significantly higher in the PC group than in the N, VC, E1, or E2 group at week 4. Thus, LO could be practically applied as a hair growth-promoting agent.

• 한국재료학회지
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• 제26권12호
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• pp.681-687
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• 2016

Zirconium(Zr) nuclear fuel cladding tubes are made using a three-time pilgering and annealing process. In order to remove the oxidized layer and impurities on the surface of the tube, a pickling process is required. Zr is dissolved in HF and $HNO_3$ mixed acid during the process and pickling waste acid, including dissolved Zr, is totally discarded after being neutralized. In this study, the waste acid was recycled by adding $BaF_2$, which reacted with the Zr ion involved in the waste acid; $Ba_2ZrF_8$ was subsequently precipitated due to its low solubility in water. It is very difficult to extract zirconium from the as-recovered $Ba_2ZrF_8$ because its melting temperature is $1031^{\circ}C$. Hence, we tried to recover Zr using an electrowinning process with a low temperature molten salt compound that was fabricated by adding $ZrF_4$ to $Ba_2ZrF_8$ to decrease the melting point. Change of the Zr redox potential was observed using cyclic voltammetry; the voltage change of the cell was observed by polarization and chronopotentiometry. The structure of the electrodeposited Zr was analyzed and the electrodeposition characteristics were also evaluated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.32-32
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• 2009

Silicon carbide (SiC) is a wide-bandgap semiconductor that has materials properties necessary for the high-power, high-frequency, high-temperature, and radiation-hard condition applications, where silicon devices cannot perform. SiC is also the only compound semiconductor material. on which a silicon oxide layer can be thermally grown, and therefore may fabrication processes used in Si-based technology can be adapted to SiC. So far, atomic force microscopy (AFM) has been extensively used to study the surface charges, dielectric constants and electrical potential distribution as well as topography in silicon-based device structures, whereas it has rarely been applied to SiC-based structures. In this work, we investigated that the local oxide growth on SiC under various conditions and demonstrated that an increased (up to ~100 nN) tip loading force (LF) on highly-doped SiC can lead a direct oxide growth (up to few tens of nm) on 4H-SiC. In addition, the surface potential and topography distributions of nano-scale patterned structures on SiC were measured at a nanometer-scale resolution using a scanning kelvin probe force microscopy (SKPM) with a non-contact mode AFM. The measured results were calibrated using a Pt-coated tip. It is assumed that the atomically resolved surface potential difference does not originate from the intrinsic work function of the materials but reflects the local electron density on the surface. It was found that the work function of the nano-scale patterned on SiC was higher than that of original SiC surface. The results confirm the concept of the work function and the barrier heights of oxide structures/SiC structures.

• 한국식품영양과학회지
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• 제26권2호
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• pp.193-197
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• 1997

볶은 들깨박에 존재하는 항암효소계 유도물질을 분리하기 위해 용매분획과 preparative TLC를 실시하여 이들에 대한 암예방지표효소인 quinone reductase와 AHH 유도활성을 조사하였다. 볶은 들깨박의 메탄올 추출물을 용매분획하여 QR을 측정한 결과 chloroform층에서 가장 높은 활성이 나타났다. 들깨박 메탄올 추출물을 TLC로 분리한 분획가운데 QR과 AHH유도활성은 F1$(R_{f}=0.8)$에서 가장 높았으며, 항산화능은 F1$(R_{f}=0.8)$과 F2$(R_{f}=0.7)$에서 가장 강한 것으로 나타나 QR유도성분과 항산화성분이 동일성분일 가능성이 높은 것으로 사료 된다.

• 한국수산과학회지
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• 제34권5호
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• pp.556-562
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• 2001

본 연구에서는 비교적 성장이 빠르고 배양이 용이한 황갈편조 식물문 중 규조강에 속하는 P. tricornutum으로부터 선정하여 항 산화성 물질을 분리$\cdot$정제하여 물질의 구조를 밝혔다. P. tricornutum의 각 유기용매 추출물의 항산화성은 chloroform획분이 가장 좋았으며, 이 획분을 시료로 하여 silica gel column chromatography, PTLC 및 HPLC를 사용하여 항산화성 물질을 분리$\cdot$정제하였다. Silica gel column을 사용하여 분리된 획분의 항산화성은 dichloromethane: methanol (5: 1)로 용출시킨 획분에서 가장 높았으며, 이 획분의 PTLC 획분은 항산화성이 $20\%$ 증가하였다. 최종 정제된 물질의 $IC_50$값은 $8.3{\mu}g/mL$으로 화학적으로 합성된 항산화제인 BHT 및 BHA보다는 낮았지만 천연 항산화제인 $\alpha-tocopherol$보다는 다소 높게 나타났으며, 이 물질의 화학적 구조는 carotenoid류인 zeaxanthin으로 동정되었다.

• 복식
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• 제59권3호
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• pp.82-95
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• 2009

The kind and the use of the fabrics for crown manufacture in the Baekje period has been studied by characterizing the imprinted fabrics on the crowns and the diadem ornaments from the old tomb. The contact region with the skin inside of the crown and the region between the bark of white birch and the gilt bronze openwork plates contained fabrics. The fabrics used in the gilt-bronze crown were all plain weave silk except that of Yongwonri tomb where loosely woven thin tabby was used. There have been 4-types of iron framed diadem of the Baekje, which comprise the inverted triangle-shaped diadem only with iron frame, the diadem with gold plate ornament in the iron frame, the diadem decorated with mica plate and gold plate, and the diadem with silver ornament in the iron frame. The fabrics used in the triangle shaped iron frame diadem include plain weave silk, irregular plain woven silk, thin tabby, complex silk gauze, twill weave on plain ground, and warp-faced compound weave. The iron frames were wrapped with the fabrics from one layer up to three layers, and the iron diadem was covered with one later of loosely woven textile such as irregular plain woven silk, thin tabby, and complex silk gauze. But in case of decorating the iron diadem with gold Plate ornaments, multiple layers of fabric were used to sustain the weight of the ornaments. The fabrics in the iron diadem frame were sewed with running stitch, overedge stitch or hemming stitch, diagonal hemming stitch, half back stitch), and overcast stitch.