• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1846-1854
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• 2022

The sophistication and diversification of mission equipment for surveillance and reconnaissance is leading to a demand for large-capacity public data links. Overseas, a T4 class(274Mbps) common data link was applied to the Global hwak, a high-altitude unmanned aerial vehicle, and various research and development are being conducted in Korea. In this paper, we propose a structure in which pilot is additionally applied to improve SNR performance while minimizing data transmission rate loss in the DVB-S2 frame structure, which is a european satellite broadcasting standard, for high-capacity transmission of T4 class or higher in the common data link. For the performance evaluation of the proposed structure, the performance of the DVB-S2 was compared and analyzed by simulating the UAV data link channel environment. As a result of simulation, 0.15% of transmission rate loss occurred at T4 class transmission rate compared to DVB-S2 in the proposed structure, but improved SNR reception performance of 0.2~0.3dB was confirmed in the UAV channel environment.

• Korean Journal of Microbiology
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• v.9 no.3
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• pp.103-120
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• 1971

We have been studied on brewing sweet starch. We obtained the results as follows ; 1) 5 strains, T-T-2, T-T-4, T-K-2, T-T-18, T-T-1, were the most available in view of fermentative power by capacity of $CO_2$. 2) 5 strains, T-T-4, T-T-2, T-T-1, T-T-3, T-K-2, produced capacity of alcohol more than 5.78%. 3) 6 strains, T-T-2, T-K-2, T-T-4, T-S-2, T-I-3, T-I-1, are available not only taste and flavour, but productive power of alcohol in sweet potato starch. 4) The form of 6 strains are long oval and round and most of them are similar to the other yeast in size. 5) In giant colony the color was cream color and cream buff, and T-K-2 was formed by $15{\times}12mm$ on diameter and by 3.5mm on high. 6) Optimum temperature of most of all strains is 25~ $300^{\circ}C$but T-K-4 is 28-30.deg.C. 7) Optimum pH is 3.4-4.6. 8) T-S-2 was died off at 65.deg.C, the other strains died $60^{\circ}C$. 9( Making Bun-kok with non-heated wheat bran .alpha.-amylase was more increased by 4.5-13.5 mg of glucose in reaction solution and .betha.-amylase more 1.6-3.4ml of N/10-$KMnO_4$ Solution than Bun-kok with heated wheat bran. 10) It seems that mycellium grows better than original in substance containing 0.4 ~ 1.2% of HCl. 11) Making Bun-kok to add 0.8% HCl, .alpha.-amylase was increased 9.93-20.7mg of glucose and .betha.-amylase ws increased 2.6~4.3ml of N/10-$KMnO_4$ solution to reaction solution. 12) 1.2%-HCl, or higher concentration, acts as inhibitor, in the meanwhile the concentration between 0.4~0.8% of HCl acts as activator. 13) We must make Bun-kok for 42 hours, at 28~$30^{\circ}C$) After we made Bun-kok using S-O-II and R-J-I one by one, Bun-kok which mix each other in equal quantity is increased more than original on enzyme acrivity. 15) Oxidation is the best way of refining sweet potato starch in N/10-phosphate buffer solution (pH 7.5). 16) When we prepared sweet potato starch, first pH was 3.0.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.499-506
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• 2016

This study was conducted to estimate carbon stock and uptake for Larix kaempferi Lamb., the single species, which is the most widely distributed one following Pinus densiflora, using data from 6th national forest inventory and forest type map of 1:5,000. Overall distribution area of Larix kaempferi in South Korea was shown as 272,800ha, in detail, Gangwon-do was the most widely distributed region with 39.6% (108,141 ha) of the whole forest area, and Gyeongsangbuk-do was 18.6%(50,839 ha), Chungcheongbuk-do was 15.1%(41,205ha) in order. As the results of analysis in carbon stock and uptake for each province, the values were high with Gyeonggi-do 109.0 tC/ha, $10.3tCO_2/ha/yr$, Gangwon-do 349.1 tC/ha, $9.7tCO_2/ha/yr$ in order, and Jeollabuk-do was the lowest with 78.3 tC/ha, $7.6tCO_2/ha/yr$. Also, the results of estimation in total carbon stocks and uptakes by year (1989~2015) were turned out that total carbon stocks and uptakes were 24,891 thousand tC, $2,428thousand\;tCO_2$ in 2015, increasing about 4.8 times and 3.8 times each compared with 5,238 thousand C/ha, $640thousand\;CO_2$ in 1989. Although forest area was decreased 26.6% with 371,884 ha in 1989 to 272,800 ha in 2015, carbon stocks and uptakes were increased in 2015 in that forest stock was increased 126% compared to 1989.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.8
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• pp.637-640
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• 2009

In this work, we demonstrate 800 V 4H-SiC power DMOSFETs with several structural alterations to obtain a low threshold voltage ($V_{TH}$) and a high figure of merit ($V_B\;^2/R_{SP,ON}$), To optimize the device performance, we consider four design parameters; (a) the doping concentration ($N_{CSL}$) of current spreading layer (CSL) beneath the p-base region, (b) the thickness of p-base ($t_{BASE}$), (c) the doping concentration ($N_J$) and width ($W_J$) of a JFET region, (d) the doping concentration ($N_{EPI}$) and thickness ($t_{EPI}$) of epi-layer. These parameters are optimized using 2D numerical simulation and the 4H-SiC DMOSFET structure results in a threshold voltage ($V_{TH}$) below $^{\sim}$3.8 V, and high figure of merit ($V_B\;^2/R_{SP,ON}$>$^{\sim}$200 $MW/cm^2$) for a power MOSFET in $V_B\;^{\sim}$800 V range.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.189-195
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• 2011

BACKGROUND: Wastewaters were collected from 25 sites of two industrial areas of Mymensingh and Gazipur in Bangladesh to assess metallic toxicity of wastewater for irrigation usage. METHODS AND RESULTS: The analyzed wastewaters were slightly alkaline to alkaline in nature and were problematic for irrigation except 3 samples. As per TDS values, 9 samples were rated as fresh water and the rest 16 were classified as brackish water. EC and SAR reflected that all samples were medium salinity (C2), high salinity (C3), very high salinity (C4) and low alkalinity (S1) hazard classes expressed as C2S1, C3S1 and C4S1. Wastewaters of different industries were graded as excellent, good, permissible and doubtful for irrigation purpose as per SSP. According to hardness ($H_T$), wastewater were under moderately hard, hard and very hard classes. Cd, Cr and Cu ions were treated as toxicant for irrigating soils and crops. Zn was problematic for long-term irrigation. The concentrations of Pb, Fe and Na were far below the toxic levels. Synergistic relationships were observed between pH-EC, pH-TDS, EC-TDS, SAR-SSP and SSP-hardness. CONCLUSION(s): If wastewater is applied for irrigation due to the fresh water shortage, it can contaminate soil due to some toxic metal ions.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.9-12
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• 2004

We report a successful fabrication of high-$J_C$ $NdBa_2Cu_3O_{7-{\delta}}$ (NdBCO) films on (100) $SrTiO_3$ substrates by pulsed laser deposition (PLD) in high oxygen pressures ranging from 400 to 800 mTorr. Fabricated NdBCO films exhibited only c-axis orientation, good out-of-plane and in-plane textures, and also excellent superconducting properties, including critical temperature ($T_C$) and critical current density ($J_C$) of above 90 K and the highest of $3.1MA/cm^2$ at 77 K in self-field, implying that NdBCO is a perspective alternative to YBCO for coated conductor. In low oxygen pressures ranging from 100 to 200 mTorr, however, the films showed a-, c-mixed orientation and degraded $T_{C,zero}$ values due to the formation of $Nd_{1+x}Ba_{2-x}Cu_3O_{7-{\delta}}$-type solid solutions with an excessive substitution of $Nd^{3+}$ ions for the $Ba^{2+}$ sites.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.16-16
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• 1992

We have studied the effect of platinum addition on the supercon ducting properties of YB $a_2$C $u_3$$O_{7-x}$ (123) compound and elucidated the mechanism of fine dispersion of $Y_2$BaCu $O_{5}$(211) particles in YB $a_2$C $u_3$$O_{7-x}$ superconductor prepared by melting method from the metallurgical point of view. In this study, BaCu $O_2$ and CuO-rich phase unreacted during the peritecitc reaction markedly decreased by the 211 powder addition. The 211 particle of Pt-fee sintered samples exhibited 8~10$\mu$m in size, but in 1wt%Pt-added sample, 211 particles were finely dispersed in 123 matrix and the size of 211 particle was about 1~2$\mu$m. And, the critical temperature( $T_{c. zero}$) of Pt doped samples was 91.5K and the transport critical current density ( $J_{c}$) of Pt-doped samples was much more than 10$^4$A/$\textrm{cm}^2$. The high $J_{c}$ and fine dispersion of 211 particles of Pt doped YB $a_2$C $u_3$$O_{7-x}$ superconductor are attributed to $Ba_4$CuP $t_2$ $O_{8}$ compounds formed during the partial melting, which were considered als nucleation sites of 211 particles, rather than Pt inself.han Pt inself.

• The Journal of the Acoustical Society of Korea
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• v.21 no.7
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• pp.648-655
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• 2002

This paper describes implementation of a multi-channel G.723.1 Annex A (G.723.1A) focused on code optimization using a high performance general purpose Digital Signal Processor (DSP), To implement a multi-channel G.723.1A functional complexities of the ITU-T G.723.1A fixed-point C-code are measures an analyzed. Then we sort and optimize C functions in complexity order. In parallel with optimization, we verify the bit-exactness of the optimized code using the ITU-T test vectors. Using only internal memory, the optimized code can perform full-duplex 17 channel processing. In addition, we further increase the number of available channels per DSP into 22 using fast codebook search algorithms, referred to as bit -compatible optimization.

• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.15-21
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• 1991

The magnetic properties of the $Y_{1}Ba_{2}Cu_{3-x}Sn_{x}O_{7-y}$ superconductor were studied as a function of Sn concentration by utilizing both the vibrating sample magnetometer (VSM) and torque magnetometer. Unlike the cases where Fe and Co were substituted for Cu, the superconducting transition temperature was maintained above 90 K until x reached the value of 0.36. The lower critical field $H_{c1}(T)$ and upper critical field $H_{c2}(T)$ are measured as a function of temperature and external magnetic field, respectively. By aid of these results, $H_{c1}(0)$.($H_{c2}(0)$), the coherence length ${\varepsilon}_{0}$, the penetration depth ${\lambda}_{0}$, and the Ginzburg-Landau parameter k were oqtained. Flux pinning was also observed in the sample.

• 한국초전도학회:학술대회논문집
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• v.11
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• pp.12-12
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• 2001