• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.6
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• pp.467-474
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• 1990

In this paper, the circuit that has characteristics of high speed and low dissipation is described. A 4:1 parallel ADC is constructed by using the designed SCFL(Source Coupled FET Logic). The results of simulation shows that comparators is obtained integrated nonlinearity, $\pm$28mV, compared with limiting value, $\pm$68mV, at 66NHz input signal and 2Gs/s Niquist rates and this paper describes low power dissipation about 0.43W by reducing the elements in a ADC design.

• The Korean Journal of Food And Nutrition
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• v.25 no.3
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• pp.677-684
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• 2012

A bacterium strain GS-2 isolated from the Korean traditional seasoning food, Chungkookjang and was determined to produce large amounts of ${\gamma}$-PGA with high productivity when provided with simple nutrients (L-glutamic acid 2.0%, glucose 1.0%, $NH_4Cl$ 0.5%, $KH_2PO_4$ 0.05%, $MgSO_4{\cdot}7H_2O$ 0.01%, pH 7.0). In this study, the culture medium for this strain was optimized for the production of ${\gamma}$-PGA. The Bacillus subtilis GS-2 required supplementation with L-glutamic acid and other nutrients for maximal production of ${\gamma}$-PGA. The optimal culture conditions for ${\gamma}$-PGA production were a 48 hr culture time, a temperature of $33^{\circ}C$ and initial pH of 6.5 by rotary shaking (220 rpm). A maximum ${\gamma}$-PGA production of 31.0 $g/{\ell}$ was obtained with L-glutamic acid (30 $g/{\ell}$), sucrose (the main carbon source, 30 $g/{\ell}$), $NH_4Cl$ (the main nitrogen source, 2.5 $g/{\ell}$), $KH_2PO_4$ (1.5 $g/{\ell}$) and $MgSO_4{\cdot}7H_2O$ (0.15 $g/{\ell}$) in the culture medium.

• Journal of the Korean Magnetics Society
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• v.7 no.6
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• pp.327-333
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• 1997

We designed and constructed the high frequency magnetic characteristics measurement system to measure core loss, B-H curve, permeability of toroidal ferrite core, amorphous core and various materials for high frequency application. The system consists of universal equipments such as digitizing oscilloscope, signal generator, power amplifier, PC in order to make upgrade easily. The power source is composed of waveform synthesizer and power amplifier ranging from DC to 20 MHz, and output signal H and B from sample core are digitized by oscilloscope with sampling rate 1 GS/ s per channel. Computer controls power source and oscilloscope, reads data from oscilloscope, displays analyzed waveform and saves data with file. The entire procedures finishes within few seconds.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.384-397
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• 2021

Background: With volatile organic compounds (VOCs) containing aromatic and halogenated hydrocarbons such as benzene, toluene, and xylene that can adversely affect the respiratory and cardiovascular systems when a certain concentration is reached, it is important to accurately evaluate the source and the corresponding health risk effects. Objectives: The purpose of this study is to provide scientific evidence for the city of Seoul's VOC reduction measures by confirming the risk of each VOC emission source. Methods: In 2020, 56 VOCs were measured and analyzed at one-hour intervals using an online flame ionization detector system (GC-FID) at two measuring stations in Seoul (Gangseo: GS, Bukhansan: BHS). The dominant emission source was identified using the Positive Matrix Factorization (PMF) model, and health risk assessment was performed on the main components of VOCs related to the emission source. Results: Gasoline vapor and vehicle combustion gas are the main sources of emissions in GS, a residential area in the city center, and the main sources are solvent usage and aged VOCs in BHS, a greenbelt area. The risk index ranged from 0.01 to 0.02, which is lower than the standard of 1 for both GS and BHS, and was an acceptable level of 5.71×10^-7 to 2.58×10^-6 for carcinogenic risk. Conclusions: In order to reduce the level of carcinogenic risk to an acceptable safe level, it is necessary to improve and reduce the emission sources of vehicle combustion and solvent usage, and eco-car policies are judged to contribute to the reduction of combustion gas as well as providing a response to climate change.

• Food Science of Animal Resources
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• v.39 no.2
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• pp.296-308
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• 2019

Although the yellow mealworm (Tenebrio molitor L.) is a promising alternative protein source, the effects of processing conditions on functional properties are unclear. In this study, a protein extract of yellow mealworm larvae (PEYM) was subjected to different heat temperature ($55^{\circ}C$, $75^{\circ}C$, and $95^{\circ}C$) with different time (20, 40, and 60 min) to evaluate the functional properties and protein oxidation. Different heat temperature treatment significantly affected the exposure of surface hydrophobicity of the proteins and protein molecule aggregation, which reached maximum levels at $95^{\circ}C$ for 60 min. Protein oxidation was inversely proportional to the temperature. Both the highest carbonyl value (1.49 nmol/mg protein) and lowest thiol value (22.94 nmol/mg protein) were observed at $95^{\circ}C$ for 60 min. The heating time-temperature interaction affected several functional properties, including solubility, emulsifying potential, and gel strength (GS). Solubility decreased near the isoelectric point (pH 5 to 6). As the temperature and heating time increased, emulsifying properties decreased and GS increased. The oil absorption capacity and foaming properties decreased and the water absorption capacity increased. These results confirmed that PEYM is a suitable source of proteins for processing and applications in the food industry.

• The Korean Journal of Mycology
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• v.1 no.2
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• pp.25-30
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• 1973

The Aspergilli can be isolated from many of damaged domestic fowl's lung which were collected at fowl slaughter house from July to August 1973, during two months at Dapsimri, Dongdaemoon-ku, Seoul city. The survey of incubation condition for carbon source and nitrogen source were summerized as follows: 1. One of the Aspergillius fumigatus group were isolated from damaged domestic fowl's lung. 2. In the preparation of isolation media, adding the 4 gs of silkworm pupa and Meju to Czapek's agar medium is more preferable than Austick's media (2% malt extract agar) 3. In survey of incubation condition, the growth rate and sporulation shown that higher differences according to varieties and amounts of C-source. And in the case of 20% C-source concentration shown that low growth rate than lower concentration of C-source. 4. In N-source, the growth rate indicated that some difference according to varieties of N-source, difference of growth rate demonstrated almost not shown at various amounts differences of mycelium and sporulation was only detected reversely.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1263-1268
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• 2008

In this paper, the low noise power amplifier for GaAs FET ATF-10136 is designed and fabricated with active bias circuit and self bias circuit. To supply most suitable voltage and current, active bias circuit is designed. Active biasing offers the advantage that variations in the pinch-off voltage($V_p$) and saturated drain current($I_{DSS}$) will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets a gate-source voltage($V_{gs}$) for the desired drain voltage and drain current. Using resistive decoupling circuits, a signal at low frequency is dissipated by a resistor. This design method increases the stability of the LNA, suitable for input stage matching and gate source bias. The LNA is fabricated on FR-4 substrate with active and self bias circuit, and integrated in aluminum housing. As a results, the characteristics of the active and self bias circuit LNA implemented more than 13 dB and 14 dB in gain, lower than 1 dB and 1.1 dB in noise figure, 1.7 and 1.8 input VSWR at normalized frequency $1.4{\sim}1.6$, respectively.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.355-358
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• 2004

In this work, N-LDMOSFET(Lateral Double diffused MOSFET) was designed and fabricated on SOI(Silicon-On-Insulator) substrate, for such applications as motor controllers and high voltage switches, fuel injection controller systems in automobile and SSR(Solid State Rexay)etc. The LDMOSFET was designed to overcome the floating body effects that appear in the conventional thick SOI MOS structure by adding p+ region in source region. Also, RESURF(Reduced SURface Field) structure was proposed in this work in order to reduce a large on-resistance of LDMOSFET when operated keeping high break down voltage. Breakdown voltage was 268v in off-state ($V_{GS}$=OV) at room temperature in $22{\mu}m$ drift length LDMOSFET. When 5V of $V_{GS}$ and 30V of $V_{DS}$ applied, the on resistance(Ron), the transcon ductance($G_m$) and the threshold voltage($V_T$) was 1.76k$\Omega$, 79.7uA/V and 1.85V respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1149-1154
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• 2014

To observe the tunneling phenomenon of oxide semiconductor transistor, The Indium-gallum-zinc-oxide thin film transistors deposited on SiOC as a gate insulator was prepared. The interface characteristics between a dielectric and channel were changed in according to the properties of SiOC dielectric materials. The transfer characteristics of a drain-source current ($I_{DS}$) and gate-source voltage ($V_{GS}$) showed the ambipolar or unipolar features according to the Schottky or Ohmic contacts. The ambipolar transfer characteristics was obtained at a transistor with Schottky contact in a range of ${\pm}1V$ bias voltage. However, the unipolar transfer characteristics was shown in a transistor with Ohmic contact by the electron trapping conduction. Moreover, it was improved the on/off switching in a ambipolar transistor by the tunneling phenomenon.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.610-616
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• 2011

Clubroot disease caused by Plasmodiophora brassicae, induces damage to cruciferous vegetables worldwide. For control of the disease, many CR (clubroot resistant) $F_1$ hybrid cultivars of Chinese cabbage have been bred and released in Korea. In this study, we determined the race of 10 field isolates of P. brassicae collected from ten regions in Korea using Williams' differential varieties and investigated the degree of resistance of 25 commercial CR cultivars of Chinese cabbage to the isolates. The clubroot pathogens were assigned into two (HS and YC), two (HN1 and HN2), two (DJ and SS) and four (GS, GN, JS, and PC) isolates for race 2, race 4, race 5, race 9, respectively. All CR cultivars showed similar response, resistant or susceptible, to each isolate and the P. brassicae isolates were divided into two groups. Among them, the DJ, GS, GN, HS, and JS isolates could not infect the CR cultivars. In contrast, the SS, HN1, HN2, PC, and YC isolates caused severe clubroot disease on the CR cultivars like susceptible cultivars. Even though they belong to the same race, the CR cultivars showed a different response to the pathogens. The results suggest that the breakdown of CR in Chinese cabbage has already occurred in cultivation areas of Korea and resistance source introduced in CR cultivars may be very limited. In addition, it is likely that resistance genes of Williams' differential varieties to P. brassicae are different from the gene of CR cultivars of Chinese cabbage used in the study.