• Korean Journal of Materials Research
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• v.21 no.5
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• pp.243-249
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• 2011

To reduce manufacturing costs of crystalline silicon solar cells, silicon wafers have become thinner. In relation to this, the properties of the aluminium-back surface field (Al-BSF) are considered an important factor in solar cell performance. Generally, screen-printing and a rapid thermal process (RTP) are utilized together to form the Al-BSF. This study evaluates Al-BSF formation on a (111) textured back surface compared with a (100) flat back surface with variation of ramp up rates from 18 to $89^{\circ}C$/s for the RTP annealing conditions. To make different back surface morphologies, one side texturing using a silicon nitride film and double side texturing were carried out. After aluminium screen-printing, Al-BSF formed according to the RTP annealing conditions. A metal etching process in hydrochloric acid solution was carried out to assess the quality of Al-BSF. Saturation currents were calculated by using quasi-steady-state photoconductance. The surface morphologies observed by scanning electron microscopy and a non-contacting optical profiler. Also, sheet resistances and bulk carrier concentration were measured by a 4-point probe and hall measurement system. From the results, a faster ramp up during Al-BSF formation yielded better quality than a slower ramp up process due to temperature uniformity of silicon and the aluminium surface. Also, in the Al-BSF formation process, the (111) textured back surface is significantly affected by the ramp up rates compared with the (100) flat back surface.

• The Korean Journal of Physiology
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• v.29 no.2
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• pp.269-277
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• 1995

Membrane vesicles were prepared by differential centrifugation from epithelial cells of porcine trachea. Total activity of microsomal ATPases was measured spectrophotometrically by a coupled enzyme assay. The steady-state activity of the enzyme was $329{\pm}10$ nmol/min mg protein. Thapsigargin, a specific antagonist of intracellular $Ca^{2+}-ATPase$, inhibited about 50% of the activity, leaving $178{\pm}18\;nmol/min .mg$ protein (n=6), indicating that the $Ca^{2+}-ATPase$ is one of the major microsomal ATPases. The microsomes used in this study appeared to be tight-sealed vesicles since they showed saturation in $^{45}Ca^{2+}$ uptake experiments. Inositol 1,4,5-trisphosphate $InsP_{3}, 4\;{\mu}M$, an agonist of $InsP_{3}$-sensitive $Ca^{2+}$ release channel ($InsP_{3}$, receptor), and Ca-ionophore A23187 $(10\;{\mu}M)$ induced $^{45}Ca^{2+}$ releases of 20% and 50% of stored $^{45}Ca^{2+}$, respectively. The addition of $(10\;{\mu}M\;InsP_{3}$ also increased the microsomal ATPase activity from $282{\pm}8$ nmol/min mg protein to $334{\pm}21$ nmol/min . mg protein in the intact vesicles. Similar increase in the activity was observed by making microsomes leaky (uncoupling) using the Ca-ionophore A23187. ;$InsP_{3}-induced$ effects were blocked by either thapsigargin or heparin suggesting that: 1) the $InsP_{3}-induced$ increase in ATPase activity is mediated by microsomal $Ca^{2+}-ATPase$, and 2) dissipation of $Ca^{2+}$ gradient across the microsomal membrane is responsible for the $InsP_{3}-induced$ effect. In order to test the dependence of the $Ca^{2+}-ATPase$ activity on the activity of $InsP_{3}-induced$ the activity of ATPases was monitored in various concentrations of free $Ca^{2+}$ using $EGTA-Ca^{2+}$ buffers. The $Ca^{2+}$-dependent biphasic change is the well-known character of $InsP_{3} receptor but not of microsomal $Ca^{2+}-ATPase$ in non-excitable cells; however, the activity of microsomal ATPase appeared biphasic and a maxim진 activity of $397{\pm}36nmol/min\;.mg$ protein was obtained in the solution containing 100 nM free $Ca^{2+}$. Below or above this concentration, the activity of ATPases was lower. These results strongly support a positive correlation of microsomal $Ca^{2+}-ATPase$ to the $InsP_{3}$ receptors in epithelial microsomes.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.2
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• pp.103-108
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• 2005

To study the direct effect of somatostatin (SS) on calcium channel current ($I_{Ba}$) in guinea-pig gastric myocytes, $I_{Ba}$ was recorded by using whole-cell patch clamp technique in single smooth muscle cells. Nicardipine ($1{\mu}M$), a L-type $Ca^{2+}$ channel blocker, inhibited $I_{Ba}$ by $98{\pm}1.9$% (n=5), however $I_{Ba}$ was decreased in a reversible manner by application of SS. The peak $I_{Ba}$ at 0 mV were decreased to $95{\pm}1.5$, $92{\pm}1.9$, $82{\pm}4.0$, $66{\pm}5.8$, $10{\pm}2.9$% at $10^{-10}$, $10^{-9}$, $10^{-8}$, $10^{-7}$, $10^{-5}$ M of SS, respectively (n=3∼6; $mean{\pm}SEM$). The steady-state activation and inactivation curves of $I_{Ba}$ as a function of membrane potentials were well fitted by a Boltzmann equation. Voltage of half-activation ($V_{0.5}$) was $-12{\pm}0.5$ mV in control and $-11{\pm}1.9$ mV in SS treated groups (respectively, n=5). The same values of half-inactivation were $-35{\pm}1.4$ mV and $-35{\pm}1.9$ mV (respectively, n=5). There was no significant difference in activation and inactivation kinetics of $I_{Ba}$ by SS. Inhibitory effect of SS on $I_{Ba}$ was significantly reduced by either dialysis of intracellular solution with $GDP_{\beta}S$, a non-hydrolysable G protein inhibitor, or pretreatment with pertussis toxin (PTX). SS also decreased contraction of guinea-pig gastric antral smooth muscle. In conclusion, SS decreases voltage-dependent L-type calcium channel current ($VDCC_L$) via PTXsensitive signaling pathways in guinea-pig antral circular myocytes.

• Research in Community and Public Health Nursing
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• v.9 no.1
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• pp.181-199
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• 1998

This study was designed to examine Home Nursing Care in Hospital-based and Community-based programs. This study investigates actual conditions of nursing needs and demands of clients and their family and the state of home nursing services. We hope that this study will improve upon the current home nursing care system. In Korea Home-Nursing Care programs are still developing and only now becoming a part of the health care delivery system. The data was collected by a questionaire the clients developed and modified through literature review by this writer and through 10 nurses who are members of 4 hospital and 3 community- based agencies. In this study 173 clients were selected. The study lasted from Oct. 1997 to March of 1998. The results show that the average age was 64.3, years older than most women clients (63.0%), the average age of a caregiver was 50.9 years old and most were female(77%). Two types of agency clients with a significant difference between social conditions [25.7%] used some form of insurance; 54.3% had the spouse pay expenses; pay 58.5% son and daughters of Hospital-based agencies: patients of social workers were 24.0%, the highest in the community agency. The condition of patients was 63.2% of the foley and nelaton catheter insertion at hospital based agencies. The range of nursing services offered is one of the highest among the 34 kinds of servies including nasogastric tube management basic nursing, ROM exercise, bladder irrigation, wound and sore dressing. For an effective care service factors that disturb each program such as a non-cooperatative family as well as patients themselves need to be lessened. Further more, the following must be emphasized, supportive counsel 27.0%, steady care for patient, 13.3%maintain a sense of security(11.7%), dressing sores and nutrition(10.0%). Although there were a large number of home nursing care services in the community, policy changes have gathered momentum. Fortunately, the scope and level at legal support will be increased in the future. The program should intergrate and link the district or community together. A project to develop a community based home nursing system as soon as possible should be developed. In conclusion, home nursing care nurses training curriculum should be strengthened.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.7-13
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• 2012

The performance of blind equalization algorithm ISCA was compared with MSCA that is used for the minimization of the inter symbol interference which occurs in the time dispersive communication channel for digital transmission. Because of the non-linearities of a magnitude and phase transfer characteristics of a communication channel, the transmitting signal will be received that band limited and time dispersived. Therefore the distortion was compensated by using the self adaptive equalizer at the receiving side, then passing through the detector for the decision of "1" or "0". At this time the Constellation Dependent Constant is played an important role in the adaptive equalizer used on the receiver. In order to calculation of this constant, the ISCA and MSCA was used the second order statistics. The ISCA and MSCA which are possible to compensation of mensioned transfer function simulataneously, are improved the performance of original SCA algorithm and then was compared the performance by computer simulation. For this, the recovered constellation, residual isi and MSE was used, and a result of performance comparison, the ISCA algorithm has better than the MSCA in every performance index. But on the steady state of equalizer, the variation of performance due to the CME terms in the MSCA equalization algorithm was less than the ISCA, so MSCA has better stability.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.69-76
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• 2007

The accumulation curves of phenol in the flesh of apples were measured at $5^{\circ}C$, $25^{\circ}C$ and $40^{\circ}C$ when they were exposed to phenol vapor, The effective diffusivities of phenol at the rind and flesh were determined by comparing its experimentally obtained accumulation curves with simulated ones. The simulation was carried out by the non-steady state diffusion rate equation. The diffusion model assumed the consecutive diffusion of phenol at the rind and flesh of apples. The detection time of phenol in the flesh of apples was shortened with increasing temperature, and it accumulated amount also increased rapidly. The estimated effective diffusivity of phenol at the rind of apples increased with temperature as like $1.1{\times}10^{-13}\;m^2/s$ at $5^{\circ}C$, $1.4{\times}10^{-13}\;m^2/s$ at $25^{\circ}C$ and $2.2{\times}10^{-13}\;m^2/s$ at $40^{\circ}C$, but those at the flesh of apples were invariant as $1.5{\times}10^{-10}\;m^2/s$ at this temperature range. The effect of temperature on the diffusivity of phenol was small, but the increase of the vapor pressure of phenol with temperature accelerated the penetration of phenol at the rind, resulting in the rapid accumulation at the flesh of apple.

• Journal of the Korean institute of surface engineering
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• v.53 no.2
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• pp.59-66
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• 2020

Effects of Na₂SiO₃ concentration added into 0.1 M NaOH + 0.05 M NaF solution on the formation behavior and properties of PEO films on AZ91 Mg alloy were investigated under 1200 Hz of alternating current (AC) by voltage-time curves, in-situ observation of arc generation behavior and measurements of film thickness, surface roughness and micro vickers hardness. In the absence of Na₂SiO₃ in the 0.1 M NaOH + 0.05 M NaF solution, about 4 ㎛ thick PEO film was formed within 1 min and then PEO film did not grow but white spots were formed by local burning. Addition of Na₂SiO₃ up to 0.2 M caused more increased formation voltage and growth of PEO film with uniform generation of arcs. Addition of Na₂SiO₃ from 0.2 M to 0.4 M showed nearly the same voltage-time behavior and uniform arc generation. Addition of Na₂SiO₃ more than 0.5 M resulted in a decrease of formation voltage and non-uniform arc generation due to local burning. PEO film growth rate increased with increasing added Na₂SiO₃ concentration but maximum PEO film thickness was limited by local burning if added Na₂SiO₃ concentration is higher than 0.5 M. Surface roughness of PEO film increased with increasing added Na₂SiO₃ concentration and appeared to be proportional to the PEO film thickness. PEO film hardness increased with increasing added Na₂SiO₃ concentration and reached a steady-state value of about 930 H_V at more than 0.5 M of added Na₂SiO₃ concentration.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.3
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• pp.18-27
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• 2002

In order to improve the accuracy of the solution near the boundary in an analysis of viscous flow around an arbitrary boundary which move and be deformed using an Eulerian concept, a level-set based grid deformation method is introduced to concentrate grid points near the boundary. This paper presents a new monitor function which can easily control the level of the concentration of grid points along the boundary. Computations for steady flow around a semi-circular cylinder mounted on the bottom of the flow domain were carried out to check the improvement of the solution using the adaptive grid system with an immersed boundary method. The present numerical results show a good agreement with the solutions obtained by a body fitted grid system and more accurate solutions than those computed with non-adaptive grid system. For the validation of mechanical usefulness of the present method, an expanded analysis of flow around multi-body fixed in the flow domain was carried out. Finally, the present moving adaptive grid method was applied to a two-dimensional bubble rise problem. The computed results show well adapted grid points around the boundary of the bubble at every time and a good agreement with the result calculated by fixed grid system.

• Korean Journal of Social Welfare
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• v.56 no.4
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• pp.57-78
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• 2004

The economic crisis in $1997{\sim}1998$ caused massive unemployment and unprecedentedly increased the number of the poor in Korea. As many unemployed families fell into poverty, the poverty rate skyrocketed to higher than 10 percent. Not later than 2000, unemployment late got back to normal and real average income among urban households approached to the income level prior to the economic crisis. Although the economic crisis has been passed through, poverty was not decreased to the low level prior to the crisis by 2000. Why does it remain high? This study attempts to provide an answer to this question by analysing the poverty trend over the 1990s. Data come from the National Survey of Household Income and Expenditures 1991, 1996, and 20001. Results show that poverty was rapidly reduced in the first half period of the 1990s. This reduction in poverty is largely explained by steady and rapid economic growth. Modest improvement in income inequality also contributed. In contrast, the poverty rate considerably increased in the latter half of the 1990s. Average income was not fully recovered to its prior level, which reflected the economic crisis and the subsequent economic stagnation. Worsened income inequality led to higher poverty rate too. In addition, demographic changes increased the share of economically vulnerable types of families, such as families headed by single parents and the elderly. The most significant factor in explaining the higher poverty rate was extended income differential among non-elderly adults, while the next was the increased number of the elderly families. Yet, findings a little differ depending on which concepts of poverty to adopt. In the analyses based on the concept of absolute poverty, economic growth the most significantly affected the poverty trends in the 1999s. Changes in income inequality played the most important role in explaining the trend in relative poverty. Adopting the concepts of quasi-absolute poverty, which is preferred in this study, results show that rapid economic growth significantly reduced poverty in the first half of the 1990s and both worsened income inequality and stagnated economic growth increased poverty in the latter 1990s.

• Journal of Korean Society of Forest Science
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• v.88 no.1
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• pp.38-46
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• 1999

Canopy structure conductances of a Norway spruce forest in the Solling Hills(Central Germany) and Central Forest Biosphere Reserve(320km to the north-west from Moscow) were derived from LE(latent heat flux) and H(sensible heat flux) fluxes measured(by Eddy correlation technique and energy balance method) and modelled(by one dimensional non-steady-state) SVAT(soil-vegetation-atmosphere-transfer) model(SLODSVAT) using a rearranged Penman-Monteith equation("Big-leaf" approximation) during June 1996. They were compared with canopy stomatal conductances estimated by consecutive intergrating the stomatal conductance of individual needles over the whole canopy("bottom-up" approach) using SLODSVAT model. The result indicate a significant difference between the canopy surface conductances derived from measured and modelled fluxes("top-down" approach) and the stomatal conductances modelled by the SLODSVAT("bottom-up" approach). This difference was influenced by some nonphysiological factors within the forest canopy(e.g. aerodynamic and boundary layer resistances, radiation budget, evapotranspiration from the forest understorey). In general, canopy surface conductances derived from measured and modelled fluxes exceeded canopy stomatal conductance during the whole modelled period, The contribution of the understorey's evapotranspiration to the total forest evapotranspiration was small (up to 5-9% of the total LE flux) and was not depended on total radiation balance of forest canopy. Ignoring contribution of the understorey's evapotranspiration resulted in an overestimation of the canopy surface conductance for a spruce forest up to 2mm/s(about 10-15%).