• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.686-693
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• 2001

In this paper, a new carrier complex power series which represents nonlinear transfer function of high power amplifier is derived. Using this transfer function, the nonlinear transfer function of predistortive circuit for linearizing the distortion effect of a HPA(High Power Amplifier) is derived and fabricated. A measured gain and $P_{1dB}$ of the fabricated HPA in IMT-2000 basestation transmitting band are 34.06 dB and 35.4 dBm. The predistortive circuit using inverse carrier complex power series is fabricated and operated with HPA. The predistortive HPA improves C/I(Carrier to Intermodulation) ratio of HPA by 17.01 dB(@Pout=25.43 dBm/tone) with 2-tone at 2.1375 GHz and 2.1425 GHz.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.109-114
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• 2023

In this paper, a 2-channel Image-Reject receiver using a 65-nm CMOS process is presented for Ka-band compact radars. The designed receiver consists of Low-Noise Amplifier (LNA), IQ mixer, and Analog Baseband (ABB). ABB includes a complex filter in order to suppress unwanted images, and the variable gain amplifiers (VGAs) in RF block and ABB have gain tuning range from 4.5-56 dB for wide dynamic range. The gain of the receiver is controlled by on-chip SPI controllers. The receiver has noise figure of <15 dB, OP1dB of >4 dBm, image rejection ratio of >30 dB, and channel isolation of >45 dB at the voltage gain of 36 dB, in the Ka-band target frequency. The receiver consumes 420 mA at 1.2 V supply with die area of 4000×1600 ㎛.

• Advances in aircraft and spacecraft science
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• v.7 no.3
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• pp.203-214
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• 2020

In many applications like the aircraft or the rockets/missiles, the flow from a nozzle needs to be expanded suddenly in an enlarged duct of larger diameter. The enlarged duct is provided after the nozzle to maximize the thrust created by the flow from the nozzle. When the fluid is suddenly expanded in an enlarged duct, the base pressure is generally lower than the atmospheric pressure, which results in base drag. The objective of this research work is to optimize the length to diameter (L/D) ratio of the enlarged duct using the CFD analysis in the flow field from the supersonic nozzle. The flow from the nozzle drained in an enlarged duct, the thrust, and the base pressure are studied. The Mach numbers for the study were 1.5, 2.0 and 2.5. The nozzle pressure ratios (NPR) of the study were 2, 5 and 8. The L/D ratios of the study were 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. Based on the results, it is concluded that the L/D ratio should be increased to an optimum value to reattach the flow to an enlarged duct and to increase the thrust. The supersonic suddenly expanded flow field is wave dominant, and the results cannot be generalized. The optimized L/D ratios for various combinations of flow and geometrical parameters are given in the conclusion section.

• Journal of Nutrition and Health
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• v.49 no.1
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• pp.28-35
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• 2016

Purpose: Vitamin D status is associated with several chronic diseases related to obesity. In this study, we evaluate the nutritional status of vitamin D and its relation to obesity indices in Korean women. Methods: A total of 156 healthy women participated. Vitamin D status (serum $25-OH-vitamin\;D_3$ level) and obesity indices (body mass index, body fat mass, waisthip ratio, and body fat percentage etc.) and serum lipid profiles and serum adipokine (leptin and adiponectin) levels were analyzed. Results: The $25(OH)D_3$ level showed an extremely skewed distribution from 4.1 ng/ml to 24.4 ng/ml and mean $25(OH)D_3$ level was $9.0{\pm}4.0ng/ml$. With cut-off level for vitamin D deficiency (< 12.0 ng/ml), insufficiency (12-19.9 ng/ml) and sufficiency (${\geq}20ng/ml$), 77.6%, 19.2%, and 3.2% of subjects showed vitamin D deficiency, insufficiency, and sufficiency status, respectively. The $25(OH)D_3$ level showed positive correlation with weight (r = 0.2461, p < 0.01), body mass index (r = 0.2913, p < 0.001), body fat contents (r = 0.1691, p < 0.05), fat free mass (r = 0.2330, p < 0.01), and waist hip ratio (r = 0.1749, p < 0.05) after adjusted by age. The $25(OH)D_3$ level showed no significant correlation with serum lipid profiles and adipokine levels. Conclusion: Most subjects (76.6%) in this study, who had a vitamin D deficient status and serum $25(OH)D_3$ level, showed positive correlation with several obesity indices, however further research based on a large Korean population is needed to confirm the relationship.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.332-332
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• 1994

식이습관을 바꾸지 않는 상태에서 4주간의 placebo 투여후 혈청 Total-C치가 240mg/dl 이상인 원발성 고콜레스테 혈증환자 25예씩 두군으로 하여 제1군은 lovastatin 20mg에서 80mg을 1일 1회 저녁에 12주간 투여하였고, 제2군은 pravastatin 5mg을 12주간 아침 저녁으로 2회 경구 투여하였다. Lovastatin과 pravastatin 12주 투여후 혈청 Total-C치는 309$\pm$46mg/d1에서 201$\pm$37mg/d1로, 281$\pm$41mg/d1에서 218$\pm$31mg/d1로, 혈청LDL-C치는 230$\pm$46mg/d1에서 125$\pm$40mg/d1로, 199$\pm$46mg/d1에서 137$\pm$37mg/d1로 각각 유의하게 감소 하였다. (p < 0.005)혈청 Apo B치는 183$\pm$32mg/d1에서 114$\pm$26mg/d1로, 164$\pm$38mg/d1에서 123$\pm$20mg/d1로, 혈청 Apo B / Apo A-1 ratio는 1.6$\pm$0.4에서 1.0$\pm$0.3으로, 1.4$\pm$0.5에서 1.0$\pm$0.3으로 각각 유의하게 감소하였다. (p < 0.005) Lovastatin 및 pravastatin 투여후 임상적으로 의미있는 중상이나 검사상 이상 소견은 관찰되지 않았다.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.178-187
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• 2020

The current emission regulations, US Tier-4 and EU Stage-V, are only able to satisfy the regulations when all currently mass-produced emission reduction technologies such as EGR, DOC, DPF, and SCR are applied. Therefore, in this study, for the application of the Urea-SCR system to non-road diesel engines, the database was established by measuring the NO, NO2 concentration and calculating the NO2/NOx ratio based on the catalyst temperature and exhaust mass flow rate. Also, based on the measured NO2/NOx ratio data, a mathematical model was proposed to predict the NO2/NOx ratio at SCR catalyst, and the suitability of the model was verified through steady-state and transient mode. As a result of comparing the NO2/NOx ratio measured at the DOC outlet under the steady-state condition to two model values separately, the R2 was 0.9811 for the 3D map model and 0.9303 for the mathematical model. And in the case of the NO2/NOx ratio measured at the DPF outlet, the R2 was 0.9797 for the 3D map model and 0.935 for the mathematical model. It was confirmed that the R2 with the model value of the 3D Map of the mathematical model in the transient mode is 0.957, which shows high reliability.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.5
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• pp.683-689
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• 2017

Objective: The experiments were carried out to measure the effect of multivitamin, acidifier and Azolla on growth performance, profitability and lipid profiles of blood of broiler chickens to produce safe and cost effective broilers. Methods: In experiment 1, 240 day-old Cobb-500 broiler chicks were fed diets; $D_1$ (control), $D_2$ ($D_1$ with 1 mL multivitamin/liter water), $D_3$ ($D_1$ with 1 mL acidifier/liter water), $D_4$ ($D_1$ with 1 mL multivitamin and 2 mL acidifier/liter water) having 3 replications in each, and 20 chicks/replication. In experiment 2, 150 day-old Cobb-500 broiler chicks were fed diets; $T_1$ (control), $T_2$ (5% Azolla in the diet), $T_3$ (7% Azolla in the diet) and $T_4$ ($T_1$ with 1 mL multivitamin and 1 mL acidifier/liter water) having 3 replications in each, and 20 chicks/replication in control, and 10 chicks/replication in the remaining dietary treatment groups for 35 days. Results: In experiment 1, the highest live weight was observed in $D_4$ (p<0.05), however, feed intake was statistically similar between diets (p>0.05). The lowest feed conversion ratio (FCR) (p<0.001) and mortality (p<0.05) were observed in $D_2$ followed by $D_4$, $D_1$, and $D_3$, respectively. There were no significant differences between diets for feed cost and net profit (p>0.05). However, evidently but not significantly, the highest net profit was obtained in $D_2$ followed by $D_4$, $D_1$, and $D_3$, respectively. In experiment 2, the highest live weight (p<0.05) and feed intake (p<0.001) were observed in $T_4$. Mortality (p<0.01), FCR (p<0.01), feed cost (p<0.05) and net profit (p<0.05) were significantly different among diets. Considering net profit, $T_2$ was the best performing dietary group followed by $T_3$, $T_1$, and $T_4$, respectively. The lowest lipid profiles were observed in $D_3$ followed by $D_1$, $D_4$, and $D_2$, respectively (p<0.05). In experiment 2, the lowest total cholesterol, TG, and the highest amount of high density lipoprotein were observed in $T_2$, followed by $T_3$, $T_1$, and $T_4$, respectively (p<0.05). Evidently but not significantly, low density lipoprotein was the highest in $T_2$ followed by $T_3$, $T_4$, and $T_1$, respectively (p>0.05). Conclusion: In conclusion, Azolla and acidifier reduced lipid profiles of broiler chickens. Considering net profit and lipid profiles, 5% Azolla may be the suitable dietary group for producing safe and profitable broilers. However, more studies are needed to confirm this study prior to suggesting using Azolla in the poultry industry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1A
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• pp.36-43
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• 2008

In this paper, we propose an optimal relay selection scheme for decode-and-forward relaying systems. The optimal relay selection minimizes the number of time slots used to relay source's signal and maximizes an end-to-end signal-to-noise ratio. However, decode-and-forward relaying systems require additional overhead for the optimal relay selection. Assuming independent and identically distributed Rayleigh fading channels, we provide exact and closed-form expressions for the outage probability of capacity and the bit error rate for decode-and-forward relaying systems with the optimal relay selection. It is shown that the analytic results are perfectly matched with the simulated ones. When the numbers of relay nodes are 2, 4, and 8, and the numbers of time slots for overhead are 1, 2, and 4, respectively, the proposed system achieves 1 dB, 2 dB, and 3 dB gains at 1% bit error rate, respectively, and 0.5 dB, 4 dB, and 12 dB gains at 1% outage probability for 1 bps/Hz, respectively, over the conventional decode-and-forward relaying system.

• Journal of Plant Biotechnology
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• v.33 no.2
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• pp.105-110
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• 2006

This study was carried out to investigate the effects of plant growth regulators, medium salt strength and nitrogen ratio on cell culture of Gymnema sylvestre. Cell growth was inhibited by 2,4-D higher than 1.0 mg L$^{-1}$, but not by kinetin lower than 0.5 mg L$^{-1}$. Maximal cell growth was obtained at 1.0 mg L$^{-1}$ 2,4-D and 0.1 mg L$^{-1}$ kinetin. Cell growth was greatest at 1x MS medium but high strength of MS medium inhibited cell growth due to low water potential in the medium. In $NH_4^+:NO_3^-$ ratio of 0:60 (i.e. 0.0 mM $^NH_4^+$ and 60.0 mM $NO_3^-$), cells growth was highest but cells were smaller and whiter compared with those in other $NH_4^+:NO_3^-$ ratio. Reduced cell growth was observed with continuous culture. These results suggested that optimal cell culture of G. sylvestre could be achieved with 1x MS medium with 20:40 ratio of $NH_4^+:NO_3^-$ supplemented with 1.0 mg L$^{-1}$ 2,4-D and 0.1 mg L$^{-1}$ kinetin.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.113-115
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• 2004

Six generations (P$_1$, P$_2$, F$_1$, BC$_1$, BC$_2$ and F$_2$) of four bivoltine silkworm crosses (SKAU-R-1 ${\times}$ Yakwei, SKAU-R-6 ${\times}$ Yakwei, CSR$_2$ ${\times}$ CSR$_4$ and SH$_{6}$${\times}$ NB$_4$D$_2$) were evaluated in a completely randomized block design with 5 replications for each treatment. The generation mean 2 in respect of 3 metric traits (single cocoon weight, single shell weight, and shell ratio ％), were subjected to Cavallis joint scaling test. Additive dominance model was found to be adequate in CSR$_2$${\times}$CSR$_4$ and SH$_{6}$${\times}$ NB$_4$D$_2$ for single cocoon weight and shell weight and SKAU-R-6 ${\times}$ Yakwei for shell ratio(％). Whereas, in rest of the crosses epistasis was evident in the traits under investigation. Magnitude of additive gene effect (d) was greater than dominance(h) in SH$_{6}$${\times}$NB$_4$D$_2$ and SKUA-R-6${\times}$Yakwei for shell ratio (％) and in CSR$_2$${\times}$ CSR$_4$ for shell weight. Thus selection for these traits in early segregating generations of these crosses would be effective for obtaining considerable genetic gain. gain.