• Journal of the Korean Institute of Telematics and Electronics
• /
• v.18 no.3
• /
• pp.42-51
• /
• 1981

Boron was predeposited into p (100) Si wafer at 94$0^{\circ}C$ for 60minutes to make the back surface field. High tempreature diffusion process at 1145$^{\circ}C$ for 3 hours was immediately followed without removing boron glass to obtain high surface concentration Back boron was annealed at 110$0^{\circ}C$ for 40minutes after boron glass was removed. N+ layer was formed by predepositing with POCI3 source at 90$0^{\circ}C$ for 7~15 minutes and annealed at 80$0^{\circ}C$ for 60min1es under dry Of ambient. The triple metal layers were made by evaporating Ti, Pd, Ag in that order onto front and back of diffused wafer to form the front grid and back electrode respectively. Silver was electroplated on front and back to increase the metal thickness form 1~2$\mu$m to 3~4$\mu$m and the metal electrodes are alloyed in N2 /H2 ambient at 55$0^{\circ}C$ and followed by silicon nitride antireflection film deposition process. Under artificial illumination of 100mW/$\textrm{cm}^2$ fabricated N+PP+ cells showed typically the open circuit voltage of 0.59V and short circuit current of 103 mA with fill factor of 0.80 from the whole cell area of 3.36$\textrm{cm}^2$. These numbers can be used to get the actual total area(active area) conversion efficiency of 14.4%(16.2%) which has been improved from the provious N+P cell with 11% total area efficiency by adding P+ back.

• Applied Chemistry for Engineering
• /
• v.25 no.5
• /
• pp.455-462
• /
• 2014

This work investigated the hydrophobic coating of silicate yellow phosphor powder in the form of divalent europium-activated strontium orthosilicate ($Sr_2SiO_4:Eu^{2+}$) by using an atmospheric pressure dielectric barrier discharge (DBD) plasma with argon as a carrier and hexamethyldisiloxane (HMDSO), toluene and n-hexane as precursors. After the plasma treatment of the phosphor powder, the lattice structure of orthosilicate was not altered, as confirmed by an X-ray diffractometer. The coated phosphor powder was characterized by scanning electron microscopy, fluorescence spectrophotometry and contact angle analysis (CAA). The CAA of the phosphor powder coated with the HMDSO precursor revealed that the water contact angle increased from $21.3^{\circ}$ to $139.5^{\circ}$ (max. $148.7^{\circ}$) and the glycerol contact angle from $55^{\circ}$ to $143.5^{\circ}$ (max. $145.3^{\circ}$) as a result of the hydrophobic coating, which indicated that hydrophobic layers were successfully formed on the phosphor powder surfaces. Further surface characterizations were performed by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry, which also evidenced the formation of hydrophobic coating layers. The phosphor coated with HMDSO exhibited a photoluminescence (PL) enhancement, but the use of toluene or n-hexane somewhat decreased the PL intensity. The results of this work suggest that the DBD plasma may be a viable method for the preparation of hydrophobic coating layer on phosphor powder.

• Journal of IKEEE
• /
• v.11 no.4
• /
• pp.158-164
• /
• 2007

In this study, three types of a novel Trench IGBTs(Insulated Gate Bipolar Transistor) are proposed. The first structure has P-collector which is isolated by $SiO_2$ layer to enhance anode-injection-efficiency and enable the device to have a low on-state voltage drop(Von). And the second structure has convex P-base region between both gates. This structure may be effective to distributes electric-field crowded to gate edge. So this structure can have higher breakdown voltage(BV) than conventional trench-type IGBT(TIGBT). The process and device simulation results show improved on-state, breakdown and switching characteristics in each structure. The first one was presented lower on state voltage drop(2.1V) than that of conventional one(2.4V). Also, second structurehas higher breakdown voltage(1220V) and faster turn off time(9ns) than that of conventional structure. Finally, the last one of the proposed structure has combined the two structure (the first one and second one). This structure has superior electric characteristics than conventional structure about forward voltage drop and blocking capability, turnoff characteristics.

• Resources Recycling
• /
• v.20 no.6
• /
• pp.50-55
• /
• 2011

Using ultrasonic irradiation, the separation and recovery of PV cell, made of silicon wafer, from PV module was carried out through selective decomposition of EVA used as an interlaminated binder. The ultrasonic cleaner of bath-type (Output: 130 W, Frequency: 40 kHz) was used as an ultrasonic apparatus in this research. With the fixed distance of 2 cm, from ultrasonic generator to PV cell, the experiment of EVA decomposition was performed in various organic solvents such as Toluene, Trichloroethylene, O-dichlorobenzene, Benzene. And also their concentrations and temperature was changed to survey the optimum conditions. However EVA can be decomposed perfectly at $55^{\circ}C$ within 160 min in 5 M of all kinds of solvent, PV cell may be recovered with being damaged or broken severely. This damage may be resulted from the swelling of EVA in the process of decomposition. Whereas, at the condition of 5 M at $65^{\circ}C$, PV cell can be recovered with the state of minor damage or crack. This implies that the decomposition rate of EVA increases with an increase of temperature, thereby EVA can be decomposed before the swelling of EVA layer. Conclusively, it is possible for PV cell to be recovered within 40 min, at $65^{\circ}C$ in 5 M, with less damage.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.9
• /
• pp.1245-1250
• /
• 2006

This study was carried out to develop the method of preparing lecithin-fortified ginseng extract. Firstly, soybean lecithin was mixed with soybean oil (LCS) in varying ratio (2.5%, 5%, 10% and 20%). Then, one part volume of LCS was mixed with three parts volume of ginseng extract with 10% solid matter content and the mixture was vortexed vigorously. Finally, the mixture was spinned at the speed of 3,000 rpm for 30 minutes to separate oil and aqueous ginseng extract layer (AG). AG was then subjected to qualitative and quantitative analysis of phospholipids and ginsenosides. Fatty acid composition and crude fat content before and after LCS was determined. Stability of lecithin in ginseng extract was determined by analyzing phospholipid content in the one third upper and lower layer of the concentrated AG in Falcon tubes while storing the LCS treated concentrated AG in 4, 25 and 40oC for 6 months. Ratio of lecithin transferred to AG increased with the increase in lecithin content of soybean oil. There was no significant change in fatty acid composition and crude fat content, and ginsenoside content in the ginseng extract before and after LCS treatment. TLC and HPLC pattern of saponin fraction before and after treating the ginseng extract with LCS demonstrated no observable difference. There was no change in lecithin content in the upper and lower one third layer of ginseng extract in the tubes after storing the concentrated AG in 4, 25 and $40^{\circ}C$ for 6 months. Ginsenosides HPLC pattern was not changed when stored the LCS-treated ginseng extract in those conditions for six months, indicating satisfiable stability of the LCS-treated concentrated ginseng extract. From these results, it can be concluded that treatment of the ginseng extract with lecithin containing soybean oil is a labor effective method with satisfiable stability to fortify lecithins to ginseng extract.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.34 no.4
• /
• pp.269-274
• /
• 2008

In this study we successfully altered the structural characteristics of the mica surface and were able to control oil-absorption by using the microwave enhanced etching (MEE) technique, which has originally been used in semiconductor industry. When microwave energy is applied to the mica, the surface of the mica is etched in a few minutes. As the result of etching, oil-absorption of the mica was enhanced and surface whiteness was improved by modifying the silicon dioxide layer. Additionally, the high whiteness was maintained even though the etched mica absorbed the sebum or sweat. The surface modification of mica was performed by microwave irradiation after the treatment of hydrofluoric acid. The degree of etching was regulated by acid concentration, irradiation time, the amount of energy and slurry concentration. The surface morphology of the etched mica appears to be the shape of the 'Moon'. The characteristics of surface area and roughness were examined by Brunauer-Emmett-Teller (BET) surface area analysis, atomic force microscopy (AFM), scanning electron microscopy (SEM), spectrophotometer and goniophotometer.

• Applied Biological Chemistry
• /
• v.6
• /
• pp.61-77
• /
• 1965

In this experiment, Akiochi was studied especially on plant growth on the degraded soils. Besides, such soils were carefully examined on its character and plant body was analysed to know the difference in various mineral contents. For this purpose, paddy cultivation was done with the variety Pal Dal at Suwon, Sosa and Pyungtak. Three plots were chosen at each location as the normal and 2 levels of akiochi, a-the stronger and b-the weaker. Harvests from these 9 plots were measured agronomically and also chemically analysised. As for soil, after an observation on vertical section of soil, samples from each layer were also studied both physically and chemically. The results are summarized as follows. 1. Outer changes in rice plant and changes in yield components. 1) Rice from Akiochi soil showed remarkably shortened culm length, head length, protrusoion length, blade length of boot leaf, and coleoptile length, compared with that from the normal paddy field. 2) There was a tendency for Akiochi rice to have more heads per plant. 3) Akiochi rice showed poorer intercalary growth of upper 3 internodes. The ratio of this upper internode length to total culm length was also smaller in this case. Consquently the ratio of lower internode length to total culm length became larger than that from normal peddy field. 4) Akiochi rice showed significantly fewer first spikelets and attached grains of head at main stem. 5) Maturing rate of both this main seem of whole plant body was remarkably lower than that of normal rice. 6) Akiochi rice showed lower head weight of main stem, total hulled rice weight, total grain yield, 1000-grain weight, straw weight and straw-hulled rice ratio. 2. Physical and chemical study on soil. 1) Akiochi soil showed thinner upper layer and total thickness of upper and lower parts was smaller than that of normal. 2) Akiochi soil of Suwon was mainly composed of sand, while that of Sosa and Pyungtak was composed of heavy clay. 3) Chemical analysis indicated that content of $SiO_2$ in upper layer is always lower than that of normal. But no other common tendencies were found. 4) This analysis further lillustrates lower content of Fe, & Mn at Suwon ; of Mn at Sosa and higher content of Fe at Sosa and organic matters at Pyungtak. 5) Some differences in the content of N in each plot could be marked though irregular. 3. Chemical Composition of plant body. 1) Chemical analysis on grain, boot leaf and straw did not suggest any remarkable differences between normal and Akiochi rice, except that the latter contains less Si in boot leaf and less Mn in straw. 2) Contents of each chemical element were measured in grain and straw to calculate the percentage of element content in grain to that of whole plant body including both grain and straw. Here, Akiochi rice always showed lower value in N, K and Mn. 4. Relationship between chemical composition of plant body and that of soil. Akiochi soil at Sosa marked lower content of Mn. This caused another lower content of this element in grain, boot leaf and straw. But except that, no remarkable relationship could be found in this study.

• Korean Journal of Materials Research
• /
• v.6 no.7
• /
• pp.700-708
• /
• 1996

Electroless plating technique was utilized to flip chip bonding to improve surface mount characteristics. Each step of plating procedure was studied in terms pf pH, plating temperature and plating time. Al patterned 4 inch Si wafers were used as substrstes and zincate was used as an activation solution. Heat treatment was carried out for all the specimens in the temperature range from room temperature to $400^{\circ}C$ for $30^{\circ}C$ minutes in a vacuum furnace. Homogeneous distribution of Zn particles of size was obtained by the zincate treatment with pH 13 ~ 13.5, solution concentration of 15 ~ 25% at room temperature. The plating rates for both Ni-P and Au electroless plating steps increased with increasing the plating temperature and pH. The main crystallization planes of the plated Au were found to be (111) a pH 7 and (200) and (111) at pH 9 independent of the annealing temperature.

• Nuclear Medicine and Molecular Imaging
• /
• v.42 no.6
• /
• pp.469-477
• /
• 2008

Purpose: The goal of this paper is to present the design and performance of a position encoding circuit for $16{\times}16$ array of position sensitive multi-anode photomultiplier tube for small animal PET scanners. This circuit which reduces the number of readout channels from 256 to 4 channels is based on a charge division method utilizing a resistor array. Materials and Methods: The position encoding circuit was simulated with PSpice before fabrication. The position encoding circuit reads out the signals from H9500 flat panel PMTs (Hamamatsu Photonics K.K., Japan) on which $1.5{\times}1.5{\times}7.0\;mm^3$ $L_{0.9}GSO$ ($Lu_{1.8}Gd_{0.2}SiO_{5}:Ce$) crystals were mounted. For coincidence detection, two different PET modules were used. One PET module consisted of a $29{\times}29\;L_{0.9}GSO$ crystal layer, and the other PET module two $28{\times}28$ and $29{\times}29\;L_{0.9}GSO$ crystal layers which have relative offsets by half a crystal pitch in x- and y-directions. The crystal mapping algorithm was also developed to identify crystals. Results: Each crystal was clearly visible in flood images. The crystal identification capability was enhanced further by changing the values of resistors near the edge of the resistor array. Energy resolutions of individual crystal were about 11.6%(SD 1.6). The flood images were segmented well with the proposed crystal mapping algorithm. Conclusion: The position encoding circuit resulted in a clear separation of crystals and sufficient energy resolutions with H9500 flat-panel PMT and $L_{0.9}GSO$ crystals. This circuit is good enough for use in small animal PET scanners.