• Journal of Powder Materials
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• v.28 no.3
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• pp.239-245
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• 2021

The SnSe single crystal shows an outstanding figure of merit (ZT) of 2.6 at 973 K; thus, it is considered to be a promising thermoelectric material. However, the mass production of SnSe single crystals is difficult, and their mechanical properties are poor. Alternatively, we can use polycrystalline SnSe powder, which has better mechanical properties. In this study, surface modification by atomic layer deposition (ALD) is chosen to increase the ZT value of SnSe polycrystalline powder. SnSe powder is ground by a ball mill. An ALD coating process using a rotary-type reactor is adopted. ZnO thin films are grown by 100 ALD cycles using diethylzinc and H₂O as precursors at 100℃. ALD is performed at rotation speeds of 30, 40, 50, and 60 rpm to examine the effects of rotation speed on the thin film characteristics. The physical and chemical properties of ALD-coated SnSe powders are characterized by scanning and tunneling electron microscopy combined with energy-dispersive spectroscopy. The results reveal that a smooth oxygen-rich ZnO layer is grown on SnSe at a rotation speed of 30 rpm. This result can be applied for the uniform coating of a ZnO layer on various powder materials.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.297-301
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• 2006

In the present work, we investigate the characteristics of new composition material, chalcogenide $Ge_1Se_1Te_2$ material in order to overcome the problems of conventional PRAM devices. The Tc of $Ge_1Se_1Te_2$ bulk was measured $231.503^{\circ}C$ with DSC analysis. For static DC test mode, at low voltage, two different resistances are observed. depending on the crystalline state of the phase-change resistor. In the first sweep, the as-deposited amorphous $Ge_1Se_1Te_2$ showed very high resistance. However when it reached the threshold voltage(about 11.8 V), the electrical resistance of device was drastically reduced through the formation of an electrically conducting path. The phase transition between the low conductive amorphous state and the high conductive crystal]me state was caused by the set and reset pulses respectively which fed through electrical signal. Set pulse has 4.3 V. 200 ns. then sample resistance is $80\sim100{\Omega}$. Reset pulse has 8.6 V 80 ns, then the sample resistance is $50{\sim}100K{\Omega}$. For such high resistance ratio of $R_{reset}/R_{set}$, we can expect high sensing margin reading the recorded data. We have confirmed that phase change properties of $Ge_1Se_1Te_2$ materials are closely related with the structure through the experiment of self-heating layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.229-229
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• 2010

본 실험에서는 $CuInSe_2$, 3원물질을 화학량론적 조성비가 되도록 박막을 제조하기 위해 각 단위원소를 원자비에 맞춰 전자선가열 진공증착기를 사용하여 Cu, In, Se 순으로 증착하였다. $10^{-3}$torr 이상의 진공석영관에서 열처리와 동시에 Selenization을 통해 제작된 $CuInSe_2$박막은 열처리온도 $250^{\circ}C$에서는 $Cu_xSe$, CuSe등의 2차상들이 나타나다가 $450^{\circ}C$이상의 고온에서 $CuInSe_2$ 단일상을 형성하였다. 이로부터 진공중에서 반응을 시켰을 때, 더 낮은 온도에서 반응이 일어나고 열역학적으로 보다 안정한 소수의 화합물들이 쉽게 형성됨을 확인할 수 있었다. 특히 $250^{\circ}C$에서는 Sphalerite 구조를 가지다가 $350^{\circ}C$이상의 온도에서 Selenization하였을 때 Chalcopyrite 구조를 가졌다. 박막이 두꺼워지면서 결정립의 크기가 커지고 응력이 작아지는 특성을 보였다. 에너지 밴드갭은($E_g$)은 Cu/In 성분비율이 클수록 작은값을 보였으며, 결절립크기가 증대되므로 결국 흡수계수가 낮아짐을 알 수 있다. 또한 두께가 증가할수록 전반적으로 흡수계수가 증가하였고 Cu/In의 성분비율이 0.97일 때 기초흡수파장은 1,169nm이고 에너지밴드갭은 1.06eV이었으며, 두께 $1.5{\mu}m$이상일 때 전반적으로 양호한 상태의 p-type $CuInSe_2$ 박막을 제작 하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.2
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• pp.143-149
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• 2024

Segmentation of material phases through image analysis is essential for analyzing the microstructure of materials. Micro-CT images exhibit variations in grayscale values depending on the phases constituting the material. Phase segmentation is generally achieved by comparing the grayscale values in the images. In the case of waste concrete used as a recycled aggregate, it is challenging to distinguish between hydrated cement paste and natural aggregates, as these components exhibit similar grayscale values in micro-CT images. In this study, we propose a method for automatically separating the aggregates in concrete, in micro-CT images. Utilizing the Unet-VGG16 deep-learning network, we introduce a technique for segmenting the 2D aggregate images and stacking them to obtain 3D aggregate images. Image filtering is employed to separate aggregate particles from the selected 3D aggregate images. The performance of aggregate segmentation is validated through accuracy, precision, recall, and F1-score assessments.

• Applied Microscopy
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• v.25 no.3
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• pp.82-89
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• 1995

High resolution transmission electron microscopic observations on quaternary $Zn_{1-x}Mg_{x}S_y$ $S_{1-y}$(x=0.13, y=0.16) on (001) GaAs substrate grown up to $1.2{\mu}m$ with 20nm ZnSe buffer layer at $300^{\circ}C$ by RIBER MBE system which has a single growth chamber were investigated by HRTEM working at 300kV with point resolution of 0.18nm. The ZnSe buffer layer maintains the coherency with the GaAs substrate. The stacking faults had begun at ZnSe buffer/$Zn_{1-x}Mg_{x}S_{y}S_{1-y}$ interface, whose length and spacing became larger than 60nm and wider than 40nm, respectively. The inverse triangular stacking fault was bounded by stacking faults which were formed on {111} planes with different variants. There exists rare stacking faults inside the triangular defect. The epilayer surrounded by the straight stacking faults, which had formed in the same direction, became the columnar structure.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.2
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• pp.49-53
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• 2017

We study on the change of electrical properties of two-dimensional (2D) $SnSe_2$ materials with respect to Cl doping as $SnSe_{1.994}Cl_{0.006}$ under a high temperature condition. (300~450 K) By the simple solid-state reaction method, non-and Cl-doped 2D $SnSe_2$ materials are successfully synthesized with negligible impurities as confirmed by X-ray diffraction. From the temperature dependence of resistivity, it is observed that the conduction mechanism is changed from hopping to degenerate conduction with Cl doping. By Hall effect measurement, an increase on electron carrier concentration from ${\sim}7{\times}10^{16}$ to ${\sim}3{\times}10^{18}cm^{-3}$ with Cl doping verifies that Cl is an effective electron donor which results in the encouraged carrier concentration. Detailed analysis for temperature dependent Hall mobility reveals that the electrical transports in high temperature regime are governed by the grain boundary-controlled mechanism for non-doped $SnSe_2$, which is effectively suppressed by Cl-doping as entering metallic transport regime.

• Restorative Dentistry and Endodontics
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• v.30 no.3
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• pp.204-214
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• 2005

This study compared the microtensile bond strength (${\mu}$TBS) and microscopic change of two 2-step and two 1-step self-etching adhesives to dentin according to storage times in distilled water. Occlusal dentin was exposed in 48 human molars. They were divided to four groups by different adhesives: SE Bond group (Clearfil SE Bond), AdheSE group (AdheSE). Adper group (Adper Prompt L-Pop), and Xeno group (Xeno III) . Each group was stored in 37$^{\circ}C$ distilled water for 1, 15, and 30 days. Resin-bonded specimens were sectioned into beams and subjected to ${\mu}$TBS testing with a crosshead speed of 1 mm/minute. For SEM observation, one specimen was selected and sectioned in each group after each stroage time. Resin-dentin interface was observed under FE-SEM. In all storage times, mean ${\mu}$TBS of SE group was significantly higher than those of other groups (p < 0.05). There was no significant difference between mean ${\mu}$TBS of SE group and AdheSE group among all storage times, but significant difference between 1- and 30-day storage in mean y${\mu}$TBS of Adper group and Xeno group (p > 0.05). For 1-and 15-day storage, all groups showed the close adaptation between resin-dentin interfaces. For 30-day storage, resin-dentin interfaces showed wide gap in Adper group and separate pattern in Xeno III group.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.2
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• pp.88-100
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• 1998

Since fractures may serve as major conduits of groundwater flow in crystalline rocks, characterization of conductive fractures is especially important for interpretation of flow system. In this study, characterization of fractures to investigate hydraulically conductive fractures in gneisses at an abandoned mine area was performed. The orientation, width, length, movement sense, infilling materials, spacing, aperture, roughness of both joints and faults and intersection and connectivity to other joints were measured on outcrops. In addition, characteristics of subsurface fractures were examined by core logging in five boreholes, of which the orientations were acquired by acoustic televiewer logging from three boreholes. The dominant fracture sets were grouped from outcrops; GSet 1: N50-82$^{\circ}$E/55-90$^{\circ}$SE, GSet 2: N2-8$^{\circ}$E/56-86$^{\circ}$SE, GSet 3: N46-72$^{\circ}$W/60-85$^{\circ}$NE, GSet 4:Nl2-38$^{\circ}$W/15-40$^{\circ}$SW and from subsurface; HSet 1: N50-90$^{\circ}$E/55-90$^{\circ}$SE, HSet 2: N10-30$^{\circ}$E/50-70$^{\circ}$SE, HSet 3: N20-60$^{\circ}$W/50-80$^{\circ}$NE, HSet 4: N10-50$^{\circ}$E/$\leq$40$^{\circ}$NW. Among them, GSet 1, GSet 3 and HSet 1, HSet 3 are the most intensely developed fracture sets in the study area. The mean fracture spacings of HSet 1 are 30-47cm and code 1 fractures, such as faults and open fractures, comprise 21.0-42.9 percent of the whole fractures in each borehole. HSet 3 shows the mean fracture spacings of 55-57cm and the ratio of code 1 fractures is 15.4-26.9 percent. In spite of the mean fracture spacing of 239cm, code 1 fractures of HSet 4 have the highest ratio of 54.5 percent. From the fact that faults or open fractures have high hydraulic conductivity, it can be inferred that the three fracture sets of N55-85$^{\circ}$E/50-80$^{\circ}$SE, N20-60$^{\circ}$W/50-75$^{\circ}$NE and N10-30$^{\circ}$E/$\leq$30$^{\circ}$NW from a fracture system of relatively high conductivity. It is indirectly verified with geophysical loggings and constant injection tests performed in the boreholes.

• Current Photovoltaic Research
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• v.4 no.1
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• pp.21-24
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• 2016

Chalcopyrite based (CIGS) thin films have considered to be a promising candidates for industrial applications. The growth of quality CIGS thin films without secondary phases is very important for further efficiency improvements. But, the identification of complex secondary phases present in the entire film is crucial issue due to the lack of powerful characterization tools. Even though X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and normal Raman spectroscopy provide the information about the secondary phases, they provide insufficient information because of their resolution problem and complexity in analyzation. Among the above tools, a normal Raman spectroscopy is better for analysis of secondary phases. However, Raman signal provide the information in 300 nm depth of film even the thickness of film is > $1{\mu}m$. For this reason, the information from Raman spectroscopy can't represent the properties of whole film. In this regard, the authors introduce a new way for identification of secondary phases in CIGS film using depth Raman analysis. The CIGS thin films were prepared using DC-sputtering followed by selenization process in 10 min time under $1{\times}10^{-3}torr$ pressure. As-prepared films were polished using a dimple grinder which expanded the $2{\mu}m$ thick films into about 1mm that is more than enough to resolve the depth distribution. Raman analysis indicated that the CIGS film showed different secondary phases such as, $CuIn_3Se_5$, $CuInSe_2$, InSe and CuSe, presented in different depths of the film whereas XPS gave complex information about the phases. Therefore, the present work emphasized that the Raman depth profile tool is more efficient for identification of secondary phases in CIGS thin film.

• Food Science of Animal Resources
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• v.26 no.2
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• pp.197-203
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• 2006

This study was conducted to investigate the effect of seleium (Se) and vitamin E supplementation on meat quality and shelf-life in finishing pigs. A total of eighty ($Landrace{\times}Yorkshire{\times}Duroc$) pigs (74.74 initial BW) were randomly allocated into five treatments with four replications and fed for six weeks. Dietary treatments included 1) CON (basal diet), 2) ISE2 (basal diet+0.2 ppm inorganic Se+100 ppm vitamin E), 3) ISE4 (basal diet+0.4 ppm inorganic Se+100 ppm vitamin E), 4) OSE2 (basal diet+0.2 ppm organic Se+100 ppm vitamin E) and 5) OSE4 (basal diet+0.4 ppm organic Se+100 ppm vitamin E). Cooking loss was decreased in treatment of ISE4 as compared with treatment of CON (p<0.05). Crude fat (%) of OSE2 was higher than those of others (p<0.05). Redness ($a^*$- value) of M. longissimus dorsi was increased in treatment of OSE2 as compared with other treatments after 100 of storage (p<0.05). Thiobarbituric acid reactive substances (TBARS) was decreased in treatment of OSE4 compared with treatments of CON and ISE2 after 10d of storage (p<0.05). In conclusion, Se and vitamin E combination did not significantly affect cooking loss,$a^*$- value and TBARS except for cases.