• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.185-191
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• 2014

The width of depletion region in a varactor diode can be modulated by varying a reverse bias voltage. Thus, the preferred characteristics of depletion capacitance can obtained by the change in the width of depletion region so that it can select only the desirable frequencies. In this paper, the TV tuner varactor diode fabricated by hyper-abrupt profile control technique is presented. This diode can be operated within 3.3 V of driving voltage with capability of UHF band tuning. To form the hyperabrupt profile, firstly, p+ high concentration shallow junction with $0.2{\mu}m$ of junction depth and $1E+20ions/cm^3$ of surface concentration was formed using $BF_2$ implantation source. Simulation results optimized important factors such as epitaxial thickness and dose quality, diffusion time of n+ layer. To form steep hyper-abrupt profile, Formed n+ profile implanted the $PH_3$ source at Si(100) n-type epitaxial layer that has resistivity of $1.4{\Omega}cm$ and thickness of $2.4{\mu}m$ using p+ high concentration Shallow junction. Aluminum containing to 1% of Si was used as a electrode metal. Area of electrode was $30,200{\mu}m^2$. The C-V and Q-V electric characteristics were investigated by using impedance Analyzer (HP4291B). By controlling of concentration profile by n+ dosage at p+ high concentration shallow junction, the device with maximum $L_F$ at -1.5 V and 21.5~3.47 pF at 0.3~3.3 V was fabricated. We got the appropriate device in driving voltage 3.3 V having hyper-abrupt junction that profile order (m factor) is about -3/2. The deviation of capacitance by hyper-abrupt junction with C0.3 V of initial capacitance is due to the deviation of thermal process, ion implantation and diffusion. The deviation of initial capacitance at 0.3 V can be reduced by control of thermal process tolerance using RTP on wafer.

• Journal of Conservation Science
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• v.27 no.1
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• pp.61-74
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• 2011

The material characteristics of Chos$\breve{o}$n whiteware were investigated by analyzing and comparing the body and glaze compositions of whiteware shards excavated at the Kwangju royal kilns, Ch'unghyodong, and four other local-level kilns. In Korea, the rise of whiteware technology began in the early years of the Chos$\breve{o}$n dynasty, when the indigenous tradition of Kory$\breve{o}$ celadon was strongly influenced by the whiteware aesthetics of the Chinese Ming dynasty. The Kwangju royal kilns eventually made hard-textured whiteware of a quality equivalent to that of the Chinese by using type of porcelain stone that contained slightly less $Fe_2O_3$ and $TiO_2$ and slightly more $K_2O$ than that used for celadon. In contrast, the potters of Ch'unghyodong achieved the same level of quality by finding and using a totally different material: kaolinitic clay. The porcelain stone used at the Kwangju kiln was commonly found in Korea and south China, whereas kaolinitic clay (which has a high aluminum content) was typically found in north China, and was only rarely used in Korea. The flux component of the glaze compositions was mostly limestone, first in burnt form and later in crushed form, and the clay component was often glaze stone, which was a finer-grained porcelain stone with a higher proportion of feldspar. In the future, this comparative analytical study of Korean whiteware components should be extended to the $18^{th}$- and $19^{th}$-century kilns that are currently being excavated at a rapid pace.

• Korean Journal of Food Science and Technology
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• v.52 no.6
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• pp.565-572
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• 2020

The 3-monochloropropane-1,2-diol (3-MCPD) is a contaminant that occurs in foodstuffs in its free form as well as in its bound form. The objective of this study was to evaluate the effects of emulsifier, frying temperature, and the amounts of salt and oil on the formation of bound 3-MCPD in a fried snack model. Emulsifier affected the formation of bound 3-MCPD; furthermore, it was observed that the largest amount of bound 3-MCPD was detected in the fried snack model when glycerin esters of fatty acids were used as emulsifiers. Frying temperature also affected the formation of bound 3-MCPD, which increased significantly as the frying temperature increased from 145 to 190℃. In addition, salt affected the formation of bound 3-MCPD. As the amount of salt increased, the amount of bound 3-MCPD also increased significantly. Moreover, it was observed that the amount of oil did not affect the formation of bound 3-MCPD. These results will aid in the reduction of bound 3-MCPD in fried snacks.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.4
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• pp.228-232
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• 2006

Purpose: electrophilic $^{18}F(T_{1/2}=110\;min)$ radionuclide in the form of $[^{18}F]F_2$ gas is of great significance for labeling radiopharmaceuticals for positron omission tomography (PET). However, its production In high yield and with high specific radioactivity is still a challenge to overcome several problems on targetry. The aim of the present study was to develop a method suitable for the routine production of $[^{18}F]F_2$ for the electrophilic substitution reaction. Materials and Methods: The target was designed water-cooled aluminum target chamber system with a conical bore shape. Production of the elemental fluorine was carried out via the $^{18}O(p,n)^{18}F$ reaction using a two-step irradiation protocol. In the first irradiation, the target filled with highly enriched $^{18}O_2$ was irradiated with protons for $^{18}F$ production, which were adsorbed on the inner surface of target body. In the second irradiation, the mixed gas ($1%[^{19}F]F_2/Ar$) was leaded into the target chamber, fellowing a short irradiation of proton for isotopic exchange between the carrier-fluorine and the radiofluorine absorbed in the target chamber. Optimization of production was performed as the function of irradiation time, the beam current and $^{18}O_2$ loading pressure. Results: Production runs was performed under the following optimum conditions: The 1st irradiation for the nuclear reaction (15.0 bar of 97% enriched $^{18}O_2$, 13.2 MeV protons, 30 ${\mu}A$, 60-90 min irradiation), the recovery of enriched oxygen via cryogenic pumping; The 2nd irradiation for the recovery of absorbed radiofluorine (12.0 bar of 1% $[^{19}F]fluorine/argon$ gas, 13.2 MeV protons, 30 ${\mu}A$, 20-30 min irradiation) the recovery of $[^{18}F]fluorine$ for synthesis. The yield of $[^{18}F]fluorine$ at EOB (end of bombardment) was achieved around $34{\pm}6.0$ GBq (n>10). Conclusion: The production of $^{18}F$ electrophilic agent via $^{18}O(p,n)^{18}F$ reaction was much under investigation. Especially, an aluminum gas target was very advantageous for routine production of $[^{18}F]fluorine$. These results suggest the possibility to use $[^{18}F]F_2$ gas as a electrophilic substitution agent.

• Clean Technology
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• v.26 no.3
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• pp.221-227
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• 2020

When the waste solid fuel (SRF, Bio-SRF) is burnt in a boiler, a problem occurs in the combustion process involving the alkali components (Na, K) contained in large amounts in the fuel. The alkaline component has a low melting point, which usually forms low melting point salt in the temperature of the furnace, with the resulting low melting point salts attaching to the heat pipe to form a clinker. Various additives are used to suppress clinker generation, and the additive based on the kaolinite has alkali-aluminum-silica to inhibit the clinker. In this study, the reactivity of the additives based on the kaolinite was compared. The additives utilized were R-kaolinite, B-kaolinite, and A-kaolinite. Also silica and MgO were sourced as the comparison group. The experimental group was employed as a laboratory-scale batch horizontal reactor. The additive and alkaline salts were reacted at a weight ratio of 1 : 1, and the reaction temperature was performed at 900 ℃ for 10 hours. The first measurement of HCl occurring during the experiment was performed 30 minutes after the detection tube was used, and the process was repeated every hour after the experiment. After the reaction, solid residues were photographed for characterization analysis by means of an optical microscope. The reaction characteristics of the kaolinite were confirmed based on the analysis results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.802-809
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• 2017

3D printing technology is a manufacturing process for products, in which polymer and metal materials are laminated to form structures. It is advantageous for manufacturing parts requiring a high degree of design freedom and functionality. In addition, it would be a suitable technology for the production of parts for railway vehicles in the future, due to the need to produce parts in small quantities. In order to fully exploit the advantages of 3D printing technology, it is necessary to consider the process characteristics during the design of the product. In this study, the redesign and manufacturing technology of the product considering the performance and process conditions were studied for the heat exchanger in the air compressor of railway vehicles, as a trial application of the 3D printing technique. First of all, the design concept to improve the performance of the heat exchanger was defined, and the design range was specified to satisfy the performance of the present heat exchanger analyzed experimentally. Then, the detailed design was revised considering the characteristics of the metal 3D printing process, such as the manufacturing restrictions and production time. Based on the final design, the product was fabricated by the 3D printing process using aluminum material, and it was confirmed that the dimensional accuracy was satisfied. The weight of the final product was reduced by 41% compared with the existing products. The results of this study will make it possible to develop an efficient product design process for 3D printing technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3442-3447
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• 2014

A simple method to evaluate the hygroscopic characteristics of polymer of microelectronic plastic package is suggested. To evaluate the characteristics, specimens were prepared, and the internally absorbed moisture masses were measured as a function of the absorbing time and calculated numerically. The hygroscopic pressure ratio was calculated by heat transfer analysis supported by commercial FEM code because the hygroscopic diffusion equation has the same form as the heat transfer equation. The moisture masses were then summed by the self developed code. The nonconductive polymers had quite different characteristics for the different lots, even though they were the same products. The absorbed moisture mass variations were calculated for several different characteristics, and the optimal curve of the mass variation close to experimental data was selected, whose solubility and diffusivity were affected by the hygroscopic characteristics of the material. The method can be useful in the industrial fields to quickly characterize the polymer material of the semiconductor package because the fast correspondence is normally required in industry. The weight changes in the aluminum-nonconductive-polymer joint due to moisture absorption were measured. The deformed system was also measured using the Moire Interferometry system and compared with the results of finite element analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.334-341
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• 2016

In this paper, the study of a waveguide aperture-coupled feed-structured antenna has been conducted for the purpose of applying it to a wireless back-haul system sufficient for high-capacity gigabits-per-second data rates. For this study, a $32{\times}32$ waveguide slot sub-array antenna with a corporate-feed structure was designed and produced. Also, this antenna is used at 57 GHz to 66 GHz in the V-band. The construction of the antenna is a laminated form with radiating parts (outer groove and slot, cavity), a coupled aperture, and feeds in each. The antenna was designed with HFSS, which is based on 3D-FEM, produced with aluminum processed by a precision-controlled milling machine, and assembled after a silver-plating process. The measurement result from analysis of the characteristics of the antenna shows that return loss is less than -12 dB, VSWR < 2.0, and a wide bandwidth ranges up to 16%. An overall first side lobe level is less than -12.3 dB, and a 3 dB beam width is narrow at about $1.85^{\circ}$. Also, antenna gain is 38.5 dBi, offering high efficiency exceeding 90%.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.3
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• pp.254-263
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• 2006

Manganese has a role as both toxic and essential in humans. Manganese is also an essential component in the welding because it increases the hardness and strength, prevents steel from cracking of welding part and acts as a deoxidizing agent to form a stable weld. In this study, manganese generation rate and its content was determined in flux cored arc welding on stainless steel. Domestic two products and foreign four products of flux cored wires were tested in the well designed fume generation chamber as a function of input power. Welding fume was measured by gravimetric method and metal manganese was determined by inductively coupled plasma-atomic emission spectrophotometer. The outer shell of the flux cored wire tube and inner flux were analyzed by scanning electron microscopy to determine their metal compositions. Manganese generation rate($FGR_{mn}$) was increased as the input power increased. It was 16.3 mg/min at the low input power, 38.1 mg/min at the optimal input power, and up to 55.4 mg/min at the high input power. This means that $FGR_{mn}$ is increased at the work place if welder raise the current and/or voltage for the high productivity. The slope coefficient of $FGR_{mn}$ was smaller than that of the generation rate of total fume(FGR). Also, the correlation coefficient of $FGR_{mn}$ was 0.65 whereas that of FGR is 0.91. $FGR_{mn}$ was equal or higher in the domestic products than that of the foreign products although FGR was similar. From the electron microscopic analytical data, we concluded that outer shell of the wire was composed mainly of iron, chromium, nickel and less than 1.2 % of manganese. There are many metal ingredients such as iron, silica, manganese, zirconium, titanium, nickel, potassium, and aluminum in the inner flux but they were not homogeneous. It was found that both $FGR_{mn}$ and content of manganese was higher and more varied in domestic flux cored wires than those of foreign products. To reduce worker exposure to fumes and hazardous component at the source, further research is needed to develop new welding filler materials that improve the quality of flux cored wire in respect to these points. Welder should keep in mind that the FGR, $FGR_{mn}$ and probably the generation rate of other hazardous metals were increased as the input power increase for the high productivity.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.1
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• pp.31-37
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• 2007

A $^{192}Ir$ small-focal source has been developed by using the HANARO reactor and the radioisotope production facility at the Korea Atomic Energy Research Institute (KAERI). The small-focal source with the dimension of 0.5 mm in diameter and 0.5 mm in length was fabricated as an aluminum-encapsulated form by a specially designed pressing equipment. For the estimation of the radioactivity, neutron self-shielding and ${\gamma}-ray$ self-absorption effects on the measured activity was considered. From this estimation, it is realized that $^{192}Ir$ small-focal sources over 3 Ci activities can be produced from the HANARO. Field performance tests were performed by using a conventional source and the developed source to take images of a computer CPU and a piece of a carbon steel. The small-focal source showed better penetration sensitivity and geometrical sharpness than the conventional source does. It is concluded from the tests that the focal dimension of this source is small enough to maximize geometrical sharpness in the image taking for the close proximity shots, pipeline crawler applications and contact radiography.