• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.147-151
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• 2007

An improvement for the efficiency of the $Sr_{2}SiO_{4}:Eu$ yellow phosphor under the $450{\sim}470\;nm$ excitation range have been achieved by adding the co-doping element ($Mg^{2+}\;and\;Ba^{2+}$) in the host. White LEDs were fabricated through an integration of an blue (InGaN) chip (${\lambda}_{cm}=450\;nm$) and a blend of two phosphors ($Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor) in a single package. The InGaN-based two phosphor blends ($Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor) LEDs showed three bands at 450 nm, 550 nm and 640 nm, respectively. The 450 nm emission band was due to a radiative recombination from an InGaN active layer. This 450 nm emission was used as an optical transition of the $Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor. As a consequence of a preparation of white LEDs using the $Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor yellow phosphor and CaS:Eu red phosphor, the highest luminescence efficiency was obtained at the 0.03 mol $Ba^{2+}$ concentration. At this time, the white LEDs showed the CCT (5300 K), CRI (89.9) and luminous efficacy (17.34 lm/W).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.313-319
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• 2019

The A-KRS (Advanced Korean Reference Disposal System) is the disposal concept for pyroprocessed waste, which has been developed by the Korea Atomic Energy Research Institute. In this disposal concept, the amount of high-level radioactive waste is minimized using pyrochemical process, called pyroprocessing. The produced pyroprocessed waste is then solidified in the form of monazite ceramic. The final product of ceramic wastes will be disposed of in a deep geological repository. By the way, the decay heat is generated due to the radioactive decay of fission products and raises the temperature of buffer materials in the near field of radioactive waste repository. However, the buffer temperature must be kept below $100^{\circ}C$ according to the safety regulation. Usually, the temperature can be controlled by variation of the canister interdistance. However, KAERI has modelled thermal analysis under the boundary condition, where the waste canisters are in direct contact with each other. Therefore, a reliable temperature analysis in the disposal system may fail because of unknown thermal resistence values caused by the spatial gap between waste canisters. In the present work, we have performed thermal analyses considering the gap between heating elements and canisters at the beginning of canister loading into the radioactive waste repository. All thermal analyses were performed using the COMSOL software package.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.10-18
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• 2011

In order to develop highly-integrated RGBY(Red, Green, Blue, Yellow) LED light, a high thermal radiation ceramic package was manufactured, and the encapsulation process was applied with a vacuum printing encapsulation system(VPES). After the completion of vacuum printing, the shape of the encapsulation layer could be controlled by heat treatment during the curing process, and the optical power became highly increased as the encapsulation layer approached a dome shape. The optical characteristics involved in a Correlated Color Temperature(CCT), a Color Rendering Index (CRI), and the efficiency of RGBY LED light were able to be identified by the experimental designing method. Regarding the characteristics of the white light of RGBY LED light, which were measured on the basis of the aforementioned optical characteristics, CRI posted 88, CCT recorded 5,720[$^{\circ}K$], and efficiency exhibited 52[lm/W]. The chip temperature of RGBY LEDs was below 55[$^{\circ}C$] when the consumption power of LED chips was 0.1[W] for the red, 0.3[W] for the green, 0.08[W] for the blue, and 0.24[W] for the yellow. Also, the thermal resistance of the highly-integrated RGBY LED light measured by T3Ster was 2.3[K/W].

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.229-237
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• 2011

In this paper, a 60 GHz LTCC SiP with low-power CMOS OOK modulator and demodulator is presented. The 60 GHz modulator is designed in a 90-nm CMOS process. The modulator uses a current reuse technique and only consumes 14.4-mW of DC power in the on-state. The measured data rate is up to 2 Gb/s. The 60 GHz OOK demodulator is designed in a 130nm CMOS process. The demodulator consists of a gain boosting detector and a baseband amplifier, and it recovers up to 5 Gb/s while consuming low DC power of 14.7 mW. The fabricated 60 GHz modulator and demodulator are fully integrated in an LTCC SiP with 1 by 2 patch antenna. With the LTCC SiP, 648 Mb/s wireless video transmission was successfully demonstrated at wireless distance of 20-cm.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1079-1085
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• 2003

Modified atmosphere packaging was applied to oyster mushrooms (Pleurotus ostreatus) to study the effect of storage temperatures and packaging materialso. Whole mushrooms (200g) were package with polyethylene film $(PE,\;60{\mu}m\;thickness)$, ethylene vinyl acetate (EVA), or ceramic film (containing 5% zeolite) and stored at 0, 5, 10 and $20^{\circ}C$. Weight loss, color, firmness, gas composition $(O_2,\;CO_2)$ inside the film package and ethanol content in the tissue of MA packaged mushrooms were examined. Mushroom that were packed unwrapped in a conventional hardboard box (2 kg) lost marketability at a very early stage of storage due to weight loss, shrinkage, browning, and spore formation. During storage, film packaging prevented or retarded the deterioration of the mushrooms in the aspects of appearance, texture, and discoloration. Firmness slightly decreased with storage time. Total color difference was much higher in the control than in the film-packaged mushroom and rapidly increased at the early of storage. Correlation analysis showed a high correlation between total color difference and b values. These results were characterized by the reduced respiration rate resulting from elevated carbon dioxide and reduced oxygen levels in the package. At all storage temperatures, ethanol content in the tissue increased slightly at the early part of storage and rose considerably towards the end of the storage period. Ethanol content in the oyster mushrooms was higher in the stipe than in pileus tissues. The shelf life of the oyster mushrooms was about $8{\sim}11$ days at $0^{\circ}C$, about $4{\sim}6$ day at $5^{\circ}C$, about $2{\sim}3$ days at $10^{\circ}C$, and about $1{\sim}2$ days at $20^{\circ}C$.

• Journal of Technologic Dentistry
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• v.36 no.2
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• pp.83-89
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• 2014

Purpose: This study is to evaluate the effect of modeling liquid on the shear-bond strength between zirconia core and veneering ceramic. Methods: Disk-shaped (diameter: 12.0mm; height: 3.0mm) zirconia were randomly divided into six groups according to the surface conditioning method and whether modeling liquid is used or not to be applied (N=60, n=10 per group): group 1-control group with distilled water(ZD); group 2-control group with modeling liquid(ZM); group 3-airborne particle abrasion with $110-{\mu}m$ $Al_2O_3$(AD) with distilled water; group 4-airborne particle abrasion with $110-{\mu}m$ $Al_2O_3$ with modeling liquid(AM); group 5-liner with distilled water(LD); group $6{\pounds}{\neq}liner$ with modeling liquid(LM). Contact angles were determined by the sessile drop method at room temperature using a contact angle measurement apparatus. The specimens were prepared using dentin veneering ceramics, veneered, 3mm high and 2.8mm in diameter, over the cores. The shear bond strength test was performed in a Shear bond test machine. Load was applied at a cross-head speed of 0.50mm/min until failure. The fractured zirconia surfaces were evaluated by using stereomicroscope (${\times}30$). Collected data were analyzed using SPSS(Statistical Package for Social Sciences) Win 12.0 statistics program. Results: ZD showed the highest contact angle($50.6{\pm}5.4^{\circ}$) and LD showed the lowest value($6.7{\pm}1.3^{\circ}$). Control groups and zirconia liner groups were significantly higher contact angle than liner groups(p<0.05). LD was the highest shear bond strength($43.9{\pm}3.8MPa$) and ZD was the lowest shear bond strength($24.8{\pm}4.9MPa$). Shear bond strengths of control groups and contact angle of liner groups were not significantly different((p>0.05). Liner groups presented adhesive failures. The others groups showed cohesive and adhesive failures. Conclusion: Modeling liquid groups showed lower contact angles and lower shear bond strength compared to those of distilled water groups.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.290-298
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• 2018

Herein, an S-band internally-matched power amplifier that shows a power capability of 300 W in a Long Term Evolution(LTE) band 7 is designed and fabricated using a CGHV40320D GaN HEMT from Wolfspeed. Based on the nonlinear model, the optimum source and load impedance are extracted from the source-pull and load-pull simulations at the fundamental and harmonic frequencies, and the harmonic impedance tuning circuits are implemented inside a ceramic package. The internally matched power amplifier, which is fabricated using a thin-film substrate with a high relative permittivity of 40 and an RF35TC PCB substrate, is measured at the pulsed condition with a pulse period of 1 ms and a duty cycle of 10%. The measured results show a maximum output power of 257~323 W, a drain efficiency of 64~71%, and a power gain of 11.5~14.0 dB at 2.62~2.69 GHz. The LTE-based measurement shows a drain efficiency of 42~49% and an ACLR of less than -30 dBc(excluding 2.62 GHz) at an average power of 79 W.

• Journal of Technologic Dentistry
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• v.34 no.3
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• pp.303-314
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• 2012

Purpose: This study aimed to find overseas workplace and improve global competence through the preference survey on overseas employment by dental technology students. Methods: The survey sample consisted of 250 randomly selected dental technology students. Survey was conducted from March 1 to May 1 in 2012. Total of 245(98.0%) replies and analyzed 236 questionnaires excluding 9 incomplete questionnaires. The questionnaires used in this study consisted of 7 items for general information, overseas employment characteristics of 10 items, 7 items for overseas employment activation plane and job competency development of 7 items. Collected data were analyzed using SPSS(Statistical Package for Social Sciences) Win 19.0 statistics program. Results: Regarding general characteristics of the subjects, there were 131 third graders(55.5%), 63 first graders(26.7%) and 42 second graders(17.8%) among 130 males(55.1%) and 106 females(44.9%). 221(93.6%) of the subjects had no experience in language training. Students who had clinical training for 1-5 months were 123(52.1%), and 24(10.2%) students had more than six months. 89(37.7%) of the subjects had no clinical training. 155(65.7%) of the subjects hope to work with korean owner, and 81(34.3%) chose foreign owner. Favored working countries were Australia(41.5%), the United States(29.2%), Canada(18.2%) and other(11.0%). The field of dental ceramic was indicated to be the highest proportion of 104(44.1%). Period of training were 3 hours(40.3%) and 6 hours(35.2%). The most important training were language-centered education(54.2%), Job-oriented education(24.2%), local culture education(16.1%), other(3.0%) and Leadership Training(2.5%). The subjects chose overseas worker(44.9%), working-level practitioner (28.8%), successfully employed dental technology graduate(19.5%a) and professor(3.4%) as an instructor. The subjects get education and training information from professor(40.3%), other(28.0%), senior(14.4%), job site(8.9%) and acquaintance(8.5%). A credit exchange(2.46 points), a joint degree program(2.46 points), and a foreign professor(2.33 points) were needed to activate the overseas employment. A kind of dental prosthesis(3.58 points), carving tooth morphology(3.38 points), and majors of dental technology(3.30 points) were indicated to develop job competency for overseas employment. Age, year, clinical training experience and company owner were statistically meaningful data among the general characteristics affecting job competency development. Conclusion: The college needs to offer variety programs such as foreign language-centered education and a local job competency development program to graduates to be connected with international workplace and employment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.695-700
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• 2018

This paper presents the development of compact and lightweight broadband power amplifier module using HMIC (Hybrid Microwave Integrated Circuit) technology that could be high-density integration for many non-packaged microwave components into the small area of a high dielectric constant printed circuit board, such as a ceramic substrate, also using the special design and fabrication schemes for the structure of minimized electromagnetic interference to obtain the homogeneous electrical performance at the wideband frequency. The results confirmed that the small signal gain has a gain flatness of ${\pm}1.5dB$ within the range of 32 to 36 dB. In addition, the output power satisfied more than 30 dBm. The noise figure was measured within 7 dB, and OIP3 (Output Third Order Intercept Point) was more than 39 dBm. The fabricated broadband power amplifier satisfied the target specification required to electrically drive the high power amplifiers of jamming generators for electronic warfare, so the actual applicability to the system was verified. Future studies will be aimed at designing other similar microwave power amplifiers in the future.

• Journal of Bio-Environment Control
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• v.20 no.3
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• pp.227-232
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• 2011

The processing techniques are need to use the non-marketable paprika fruit because paprika that is difficult crop for cultivation and produced easily non-marketable fruits, such as physiological disorder fruit, malformed fruit, and small size fruit. This study was carried out to investigate the proper active modified atmosphere packaging (MAP) condition for enhancing the storability of fresh-cut paprika fruit. The fresh-cut paprika (cv 'Score', seminis) put into $7cm{\times}0.7cm$ size and packed them in 20 g bags. The active MAP and vacuum treated paprika fruits were packaged with LLDPE/Nylon, EVOH, Tie film, and injected partial pressures of $CO_2$ and $O_2$, and $N_2$ in the packages immediately after sealing to treat active MAP. The ratio of $CO_2$, $O_2$, and $N_2$ of active MAP conditions were 0 : 20 : 80 (air), 5 : 5 : 90, 30 : 10 : 60, 10 : 70 : 20 and vacuum treatment did not contain any gas. The passive packaging treated paprika packaged with $40{\mu}m$ ceramic film. After 7 days of storage at $9^{\circ}C$, the fresh weight decreased less than 2% in all treatments, and showed lower in 5 : 5 : 90 ($CO_2:O_2:N_2$) active-MAP treatment and higher in vacuum treatment than other treatments. The $CO_2$ and $O_2$ concentration in packages did not change remarkably in active-MA treatments except 30 : 10 : 60 active-MAP treatment that showed sharply decreased $O_2$, concentration and increased $CO_2$ concentration at $1^{st}$ day of storage at $9^{\circ}C$. The ethylene concentration in package was the highest in 30 : 10 : 60 active-MAP treatment and the lowest in the passive MAP treatment that packaged with gas permeable film during $9^{\circ}C$ storage for 7 days. The 30 : 10 : 60 active-MAP treatments were not proper condition to storage fresh-cut paprika. The visual quality was maintained higher in 0 : 20 : 80 (air), 5 : 5 : 90, and 10 : 70 : 20 active MAP treatments and passive MAP treatment than others and the firmness, off-odor, and electrolyte leakage was investigated at 7th day of storage at $9^{\circ}C$. The 5 : 5 : 90 and 10 : 70 : 20 active-MAP treatment showed higher firmness and lower off-odor than other treatments after $7^{th}$ day of storage at $9^{\circ}C$. In addition, the electrolyte leakage was reduced less than 20% at 0 : 20 : 80 (air), 5 : 5 : 90, 10 : 70 : 20, and passive MA treatments. Therefore, 10 : 70 : 20 ($CO_2:O_2:N_2$) and 0 : 20 : 80 (air) might be recommended for proper active MAP conditions.