• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.5
• /
• pp.469-473
• /
• 2009

We present high-voltage liquid-electrolyte microbatteries, inspired from the high-voltage generation mechanism of electric eels using serially connected multiple-cell arrays. In the microbatteries, we purge air into the electrolyte filled in a channel layer to isolate serially connected multiple cell arrays using three surface-tension valves (cell-front, outlet, and cell-end valves). Compared to the previous multi-cell stack or interconnection, present microbatteries provide a reduced multi-cell charging time. We have designed and characterized four different prototypes C1, C10, C20, and C40 having 1, 10, 20, and 40 cells, respectively. In the experimental study, the threshold pressures of cell-front, outlet, and cell-end valves were measured as $460{\pm}47$, $1,000{\pm}53$, and $2,800{\pm}170$ Pa, respectively. The average charging time for C40 was measured as $26.8{\pm}4.9$ seconds where the electrolyte and air flow-rates are 100 and $10{\mu}l/min$, respectively. Microbatteries showed the maximum voltage of 12 V (C40), the maximum power density of $110{\mu}W/cm^2$ (C40), and the maximum power capacity of $2.1{\mu}Ah/cm^2$ (C40). We also proposed a tapered-channel to remove the reaction gas from the cell chamber using a surface tension effect. The present microbatteries are applicable to high-voltage portable power devices.

• Preventive Nutrition and Food Science
• /
• v.4 no.1
• /
• pp.62-69
• /
• 1999

The present study was aimed at investigating whether there are sex-related differences in serum levels of lipids, retinol , $\alpha$-tocopherol and ascorbic acid in Korean adults. Serum levels of antioxidant vitamins and lipids were determined algon with anthropometric measurements in 53 healthy male subjects with mean age 42.7$\pm$12.2 years and 44 female subjects with mean age 46.7$\pm$10.3 years. from Taegu in Korea. BMI and W/H ration of the men were 22.66$\pm$2.47, 0.88$\pm$0.04 and those fo thewomen were 23.36$\pm$3.44, 0.84$\pm$0.05 respectively. Systolic and diastolic blood pressures were 121.67$\pm$14.8, 79.3$\pm$12.4 in the men and 123.1 $\pm$17.5 , 78.8$\pm$10.9 in the women respectively. Average serum levels of total cholesterol, LDL-and HDL-cholesterol and triglyceride were 165.8$\pm$36.4, 102.6$\pm$31.2, 41.1$\pm$10.5 and 110.2$\pm$57.8mg/dl in the and 169.1$\pm$39.1, 113.7$\pm$36.2, 38.1 $\pm$8.6, and 85.2$\pm$37.7mg/dl in the women respectively. Thirteen percent of menans thirtyeight percent of women had LDL-cholesterol over 130mg/dl. Serum levels of retinol, $\alpha$tocopherol, ad ascorbic acid were 43.25 $\pm$15.51, 17.93$\pm$7.07, 115.24$\pm$63.25ug/dl in the men and 31.80$\pm$15.39, 17.41$\pm$6.12, an d144.99$\pm$89.87ug/dl in the women respectively. Serum vitamin E showed positive correlations with total cholesterol and LDL-cholesterol and triglyceride.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.16 no.1
• /
• pp.103-110
• /
• 1998

This study deals with the effective management system on the underground facilities by Geographic In-formation System (GIS). For this purpose,"Management System on the Water Supply Network by GIS in Kwangju" was analylized. Following results were obtained in this study. This system could be practically used for the inquiry of water supply and distribution pipes, check valves, pipe equipments and parcel identification numbers. Inquiry of addresses using the parcel identification numbers were effective for the database management system of the water supply facilities. The poits at issue for the performance of this study were the security and education of experts, the security of revenue source, the discord between GIS companies concerned. Establishments of GIS software technologies and database systems, and the settlement between GIS companies were required for the solution of these poits. Development of computer management systems on the water sup-ply network by GIS enabled the replacement of outworn pipes and the leakage inquiry techniques in pipes. in pipes.

• Journal of Biosystems Engineering
• /
• v.29 no.6 s.107
• /
• pp.521-530
• /
• 2004

The solar powered water pump is very ideal equipment because solar power is more intensive when the water is more needed in summer and it is very helpful in the rural area, in which electrical power is not available. The average solar radiation power is $3.488\;kWh/(m^2{\cdot}day)$ in Korea. In this study, the experimental system of the water pump driven by the radiation energy were designed, assembled, tested and analyzed fur realizing the solar powered water pump. Energy conversion ken radiation energy to mechanical energy by using n-pentane as operating material was done and the water pumping cycles were able to be continued. The quantity of the water pumped per cycle ranged from 2 L to 10 L depending on the level of the valve open area far the vapour supply. The average quantity was about 4,366 cc. The thermal efficiency was about $0.018\%$. The pressure level of the n-pentane vapour in flash tank was about $110\~150\;kPa$ and that in the water tank was $93\~130\;kPa$. The pressure in the condenser during cycles was maintained as about 70 kPa. The condensation of the n-pentane vapour in the water tank was increased with the cycles even though the internal and external insulation were done. Air tank performance was better with increasing of the water piston displacement and the water could be pumped with the water piston displacement becoming higher than 6,500 cc.

• Journal of the Korean institute of surface engineering
• /
• v.44 no.4
• /
• pp.131-136
• /
• 2011

A kinetic study has been made for the growth of nanocrystalline diamond (NCD) particles to a continuous thin film on silicon substrate in a microwave plasma chemical vapor deposition reactor. Parameters of deposition have been microwave power of 1.2 kW, the chamber pressure of 110 Torr, and the Ar/$CH_4$ ratio of 200/2 sccm. The deposition has been carried out at temperatures in the range of $400\sim700^{\circ}C$ for the times of 0.5~16 h. It has been revealed that a continuous diamond film evolves from the growth and coalescence of diamond crystallites (or particles), which have been heterogeneously nucleated at the previously scratched sites. The diamond particles grow following an $h^2$ = k't relationship, where h is the height of particles, k' is the particle growth rate constant, and t is the deposition time. The k' values at the different deposition temperatures satisfy an Arrhenius equation with the apparent activation energy of 4.37 kcal/mol or 0.19 eV/ atom. The rate limiting step should be the diffusion of carbon species over the Si substrate surface. The growth of diamond film thickness (H) shows an H = kt relationship with deposition time, t. The film growth rate constant, k, values at the different deposition temperatures show another Arrhenius-type expression with the apparent activation energy of 3.89 kcal/mol or 0.17 eV/atom. In this case, the rate limiting step might be the incorporation reaction of carbon species from the plasma on the film surface.

• Journal of Korea Society of Industrial Information Systems
• /
• v.21 no.4
• /
• pp.95-110
• /
• 2016

The purpose of this study is to design a service encounter of a duty free shop using a blueprinting method. This case study analyzed differences between city-based and airport-based duty free shop and proposed a flow chart based on administration blueprinting of the duty free shop in South Korea. The paper presented process criteria based on administrative procedures of customers in city-based and airport-based duty free shop. The results of the study provided the cause of failure with waiting point of customer and customer service and suggested management plan to solve failure. Also, the study addressed more customer-oriented service delivery processes to improve service quality and customer satisfaction through waiting and failure points.

• Journal of the Korean institute of surface engineering
• /
• v.46 no.1
• /
• pp.29-35
• /
• 2013

The effect of DC bias on the growth of nanocrystalline diamond films on silicon substrate by microwave plasma chemical vapor deposition has been studied varying the substrate temperature (400, 500, 600, and $700^{\circ}C$), deposition time (0.5, 1, and 2h), and bias voltage (-50, -100, -150, and -200 V) at the microwave power of 1.2 kW, working pressure of 110 torr, and gas ratio of Ar/1%$CH_4$. In the case of low negative bias voltages (-50 and -100 V), the diamond particles were observed to grow to thin film slower than the case without bias. Applying the moderate DC bias is believed to induce the bombardment of energetic carbon and argon ions on the substrate to result in etching the surfaces of growing diamond particles or film. In the case of higher negative voltages (-150 and -200 V), the growth rate of diamond film increased with the increasing DC bias. Applying the higher DC bias increased the number of nucleation sites, and, subsequently, enhanced the film growth rate. Under the -150 V bias, the height (h) of diamond films exhibited an $h=k{\sqrt{t}}$ relationship with deposition time (t), where the growth rate constant (k) showed an Arrhenius relationship with the activation energy of 7.19 kcal/mol. The rate determining step is believed to be the surface diffusion of activated carbon species, but the more subtle theoretical treatment is required for the more precise interpretation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.11
• /
• pp.831-835
• /
• 2013

In this study, we fabricated a micro $Pb(Zr,Ti)O_3$ (PZT) film piezoelectric cantilever with a Si proof mass and dual beams through MEMS process. The size of the beam and the integrated Si proof mass were about $4,320{\mu}m{\times}290{\mu}m{\times}12{\mu}m$ and $1,380{\mu}m{\times}880{\mu}m{\times}450{\mu}m$ each. To reduce the air damping and have the larger displacement of dual beams was used for design. After mounting micro PZT film piezoelectric cantilever on shaker, we measured the resonance frequency and a output voltage while making resonant frequency changed. The resonant frequency and the highest average power of the cantilever device were 110.2 Hz and 0.36 ${\mu}W$ each, at 0.8 g acceleration and 23.7 $k{\Omega}$ load resistance, respectively.

• Computers and Concrete
• /
• v.9 no.4
• /
• pp.257-273
• /
• 2012

Based on the heterogeneous characterization of concrete at mesoscopic level, Realistic Failure Process Analysis ($RFPA^{3D}$) code is used to simulate the failure process of concrete-filled tubular (CFT) stub columns. The results obtained from the numerical simulations are firstly verified against the existing experimental results. An extensive parametric study is conducted to investigate the effects of different concrete strength on the behaviour and load-bearing capacity of the CFT stub columns. The strength of concrete considered in this study ranges from 30 to 110 MPa. Both the load-bearing capacity and load-displacement curves of CFT columns are evaluated. In particular, the crack propagation during the deformation and failure processes of the columns is predicted and the associated mechanisms related to the increased load-bearing capacity of the columns are clarified. The numerical results indicate that there are two mechanisms controlling the failure of the CFT columns. For the CFT columns with the lower concrete strength, they damage when the steel tube yields at first. By contrast, for the columns with high concrete strength it is the damage of concrete that controls the overall loading capacity of the CFT columns. The simulation results also demonstrate that $RFPA^{3D}$ is not only a useful and effective tool to simulate the concrete-filled steel tubular columns, but also a valuable reference for the practice of engineering design.

• Journal of Fisheries and Marine Sciences Education
• /
• v.22 no.2
• /
• pp.218-230
• /
• 2010

This study was conducted to determine the effect of the noise level on the boarding environment in a stern trawl ship, KAYA(GT: 1,737 tons, Pukyong National University). We measured the noise level at a working, an accommodation and a teaching area, and an engine space on January 9, 2010 while the KAYA was sailing on a liner sea route. At the working area, the ranges of the noise rating number(NRN) and the NRN determination frequency(FNRN) were from 44 to 73 and from 1000 to 2000Hz, respectively. The results were generally satisfied the criteria of the International Maritime Organization(IMO). The noise level at the area, except the radio room(w2), was exceeded the criteria(50dB(A)) for the efficient studying and working. The noise level at the engine control room and the machine workshop was respectively exceeded 1.2dB and 9.5dB than the criteria caused the conversation disturbance (70dB(A)). At the accommodation, NRN and FNRN were from 49 to 54 and from 1000 to 4000Hz, respectively. The noise level was below the criteria of IMO, but above 40dB(A) caused the sleep disturbance. At the teaching area, NRN and FNRN were from 44 to 63 and from 500 to 2000Hz, respectively. The noise level was exceeded than the criteria(50dB(A)) for the efficient studying. At the engine space, NRN and FNRN were from 95 to 100 and from 2000 to 4000Hz, respectively. The noise level was above the criteria of IMO(90dB(A)) for the residence, while it was not exceeded 110dB(A) for the transient.