• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.379-384
• /
• 2004

A prototype of 750 kW direct-drive wind turbine generator system, KBP-750D is under development in Korea. For the gearless, direct-drive prototype a synchronous generator with permanent magnets has been developed. The upwind 3-blade type machine employs variable speed and pitch control. The operating ranges of wind and rotor speed are 3 to 25 m/s and 9 to 25 rpm, respectively. The tip speed ratio of rotor blade is 7.5, designed for power coefficient 0.47, The blade pitch and torque are controlled with the predefined torque-speed curve according to the conditions of wind and public electric grid. This paper describes the outlines of primary components of KBP-750D.

• Wind and Structures
• /
• v.26 no.5
• /
• pp.331-341
• /
• 2018

A numerical study on the flow over a square cylinder in the vicinity of a wall is conducted for different Couette-Poiseuille-based non-uniform flow with the non-dimensional pressure gradient P varying from 0 to 5. The non-dimensional gap ratio L (=$H^{\ast}/a^{\ast}$) is changed from 0.1 to 2, where $H^{\ast}$ is gap height between the cylinder and wall, and $a^{\ast}$ is the cylinder width. The governing equations are solved numerically through finite volume method based on SIMPLE algorithm on a staggered grid system. Both P and L have a substantial influence on the flow structure, time-mean drag coefficient ${\bar{C}}_D$, fluctuating (rms) lift coefficient ($C_L{^{\prime}}$), and Strouhal number St. The changes in P and L leads to four distinct flow regimes (I, II, III and IV). Following the flow structure change, the ${\bar{C}}_D$, $C_L{^{\prime}}$, and St all vary greatly with the change in L and/or P. The ${\bar{C}}_D$ and $C_L{^{\prime}}$ both grow with increasing P and/or L. The St increases with P for a given L, being less sensitive to L for a smaller P (< 2) and more sensitive to L for a larger P (> 2). A strong relationship is observed between the flow regimes and the values of ${\bar{C}}_D$, $C_L{^{\prime}}$ and St. An increase in P affects the pressure distribution more on the top surface than on bottom surface while an increase in L does the opposite.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.18 no.5
• /
• pp.1-9
• /
• 1981

Experimental results on a 4-bit charge-coupled A/D converter are described. Major operations in the successive approximation algorithm are implemented in a monolithic chip, CCADC, which was fabricated usir p-channel CCD technology, with its die size of 4,200 mil2 Typical operating frequency range has been found out to be from 500Hz to 200kHz. In that frequency range, no missing code has been found in the whole signal range of 2.4 volts for ramp signal slewing at 1 LSB/(sampling time). A discussion is made on several layout techniques to conserve the nominal binary ratio of (8:4:2:1) among the areas of four adjacent potential wells (M wells), whose charge storing capacities correspond to each bit magnitude - 3.6 pC, 1.8 pC, 0.9 pC, and 0.45 pC nominal in the order of MSB to the LSB. The effect of 'dump slot', which is responsible for the excessive nonlinearity (2$\frac{1}{2}$LSB) in the A/D converter, is explained. A novel input scheme called 'slot zero insertion' to circumvent the deleterious effects of the dump slot is described with the experimental results.

• YAKHAK HOEJI
• /
• v.41 no.3
• /
• pp.328-334
• /
• 1997

Pharmacokinetics of DWP401, a recombinant human epidermal growth factor (rhEGF), was studied using radioimmunoassay (RIA) and $^{125}I$-DWP401 in rats. When DWP401 was adm inistered i.v. at doses of 50 and 500 mcg/kg, the plasma DWP401 disappeared biiexponentially with terminal half life of 4.7 and 92.8 min. The $C_{max}$ and $T_{max}$ after s.c. administration of ti at doses of 50 and 500 ${\mu}g$/kg were determined to be 23.6 and 17.5 ng/ml at 50 ${\mu}g$/kg, and 261.4 ng/ml and 36.8 min, respectively. Both the total urinary and biliary recoveries of intact DWP401 2343 very low (<0.4%), probably due to its extensive degradation in the body. the concentration ratio of DWP401 between the organ and plasma decreased especially in the liver and kidney as the dose and time after the dose increased. For example, the liver/plasma and kidney/plasma concentration ratio of DWP401 at 2.5 min after i.v. doses of 50 ${\mu}g$/kg were comparable and much larger than unity. But, the ratio at 2.5 min after i.v. doses of 500${\mu}g$/kg was much larger in the kidney that in than in the liver. These results suggest that the systemic administration of DWP401 might be subject to rapid and extensive clearance from circulation within several hour after main distrbution to liver and kidney.

• International Journal of Automotive Technology
• /
• v.6 no.1
• /
• pp.1-8
• /
• 2005

Recently, the HSDI (High Speed Direct Injection) diesel engine has been spotlighted as a next generation engine because it has a good potential for high thermal efficiency and fuel economy. This study was carried out to investigate the in-cylinder flow characteristics generated in a HSDI diesel engine with a 4-valve type cylinder head. The four kinds of cylinder head were manufactured to elucidate the effect of intake port geometry on the in-cylinder flow characteristics. The steady flow characteristics such as coefficient of flow rate $(C_{f})$, swirl ratio (Rs), and mass flow rate (m,) were measured by the steady flow test rig and the unsteady flow velocity within a cylinder was measured by PIV. In addition, the in-cylinder flow patterns were visualized by the visualization experiment and these results were compared with simulation results calculated by the commercial CFD code. The steady flow test results indicated that the mass flow rate of the cylinder head with a short distance between the two intake ports is $13\%$ more than that of the other head. However, the non-dimensional swirl ratio is decreased by approximately $15\%$. As a result of in-cylinder flow characteristics obtained by PIV and CFD calculation, we found that the swirl center was eccentric from the cylinder center and the position of swirl center was changed with crank angle. As the piston moves to near the TDC, the swirl center corresponded to the cylinder center and the velocity distribution became uniform. In addition, the results of the calculation are in good agreement with the experimental results.

• Journal of Microbiology and Biotechnology
• /
• v.1 no.2
• /
• pp.121-125
• /
• 1991

The culture conditions and nutritional requirements for enhanced mycelial growth of the ectomycorrhizal fungus P. tinctorius SMF were determined in flask scale experiments. Optimum culture conditions for growth of P. tinctorius SMF in a further modified Melin-Norkrans broth were as follows; temperature 25~$27^{\circ}C$, agitation 120 rpm, and pH 4.0. P. tinctorius SMF utilized various carbon sources including monosaccharides, disaccharides, and polysaccharides. D-Glucose and mannitol were respectively the first and second most suitable carbon sources for mycelial growth. With D-Glucose as the principal carbon source, supplementation of modified Melin-Norkrans (MMN) broth with Lysine (800 mg/l), Glutamic Acid (500 mg/l), or Proline (50 mg/l) enhanced mycelial yields 63%, 34%, and 22% respectively as compared to growth in medium lacking amino acids. ThiaminㆍHCl＋biotin＋pyridoxine supplementation also enhanced growth. As compared to mycelial growth in the MMN medium, growth of P. tinctorius SMF was enhanced 120% in MMN broth when the carbon/nitrogen ratio was 25/1 in citrate buffer at pH 4.5, and growth was 50% greater in MMN broth of carbon/nitrogen ratio with a 10/1~20/1 without using the buffer. Standard conditions established for growth of P. tinctorius SMF in MMN broth were 25~$27^{\circ}C$, agitation 120 rpm, buffered to pH 4.0 with citrate, in MMN medium containing 10 g/l D-glucose supplemented with 800 mg/l lysine. In this medium the carbon/nitrogen ratio was 20/1~25/1, and the maximal mycelial yield ($Y_{x/s}$ ) was 0.472 (4.72 mg/ml) after 7 days of incubation, as compared to 0.214 (2.14 mg/ml), when the fungus was grown in standard MMN broth.

• Advances in Energy Research
• /
• v.8 no.4
• /
• pp.223-231
• /
• 2022

An ex-situ gravitational fixed bed pyrolysis reactor was used over Al₂O₃ supported Ni₂P based catalyst with various Ni/P molar ratios (0.5-2.0) and constant nickel loading of 5.37 mmol/g Al₂O₃ to determine the hydrodeoxygenation of rubberwood sawdust (RWS) at atmospheric pressure. The 3D catalysts formed were characterized structurally as well as acidic properties were determined by hydrogen-temperature programmed reduction (TPR). The Ni₂P phase formed completely on Al₂O₃ for 1.5 Ni/P ratio, although lesser crystallite sizes of Ni₂P were seen at Ni/P ratios less than 1.5. Additionally, it was shown that when nickel loading level increased, acidity increased and specific surface area dropped, probably because nickel phosphate is not easily converted to Ni₂P. When Ni/P ratio was 1.5, Ni₂P phase fully formed on Al₂O₃. The catalytic activity was explained in terms of impacts of reaction temperature and Ni/P molar ratio. At relatively high temperature of 450℃, the high-value deoxygenated produce was predominantly composed of n-alkanes. Based on the findings, it was suggested that hydrogenolysis, hydrodeoxygenation, dehydration, decarbonylation, and hydrogenation are all part of mechanism underlying hydrotreatment of RWS. In conclusion, the synthesized Ni₂P/ Al₂O₃ catalyst was capable of deoxygenating RWS with ease at atmospheric pressure, primarily resulting in long chained (C₉-C₂₄) hydrocarbons and acetic acid.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.2
• /
• pp.197-205
• /
• 2000

The back-off input power level method is generally used for design of high linear mixer. In this paper, the predistortive mixer design method which attaches the predistortor in front of mixer is proposed to compensate the nonlinear characteristics of mixer and the predistortor has inverse nonlinear characteristics of mixer. The proposed method improves C/I ratio of mixer by 22 dB (@Po=-20 dBm/tone), 21.7 dB(@Po=-17 dBm/tone) with two tones of RF at 1852.5MHz, 1857.5MHz and LO at 2015MHz, respectively.

• The Korean Journal of Mycology
• /
• v.31 no.3
• /
• pp.141-147
• /
• 2003

The pileus of Pleurotus cystidiosus was attached at the side and was spatular-shape. It grew to the size of $7.6{\sim}9.8\;cm$ with dark brown color. The length of stem was $1.4{\sim}2.9\;cm$. The individual weight of fruiting-body was 25.4 g in average. This study was conducted to Investigate the physiological characteristics and to develop the artificial cultivation technique of P. cystidiosus. To find out the optimum condition of mycelial growth of P. cystidiosus, physiological conditions such as media, temperature, pH carbon sources and nitrogen sources were investigated. Various cultural media were used for the cultivation of P. cystidiosus and compost dextrose agar was favorable for mycelial growth. The optimal growing temperature and pH were in range of 25 to $30^{\circ}C$, pH $7{\sim}9$, respectively. When different carbon sources were compared, glucose was found to be best. However nitrogen sources were different with each strains. When different C/N ratio were compared, 20:1 of C/N ratio was found to be best.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.4
• /
• pp.345-353
• /
• 2000

In this study, the performance of five ejectors has been investigated with working fluids of water and water vapor. The diameters of nozzle and mixing tube of five ejectors were 1 and 1.5(ejector A), 1 and 2(ejector B), 1 and 2.5(ejector C), 1 and 3(ejector D), 2 and 4(ejector E) in millimeters. The length of the mixing tube was 8-10 times of its diameter. For each ejector, the ratio of mass flow rate of ejected water to that of entrained water vapor, $\mu$, was evaluated in terms of evaporator pressure, mass flow rate of ejected water, and water temperature. It was found that the performance of an ejector was not stable when the ratio of diameters was too small or too large(ejector A and D) and $\mu$ was almost the same for two ejectors with the same diameter ratio(ejector B and E). It was also found that $\mu$ increased almost linearly with an increase of evaporator pressure and the ratio $\mu$ increased as water temperature decreased. As expected, $\mu$ converged to zero as the water temperature approached the evaporator temperature. Finally, a non-dimensional correlation has been developed to predict$\mu$ terms of evaporator pressure and saturation pressure of ejected water.