• The Korean Journal of Ecology
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• v.18 no.2
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• pp.255-263
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• 1995

Two poplar clones, I-214 (Populus euramericana) and Peace (P. Koreana × P. trichocarpa), were grown for 21 days in growth chambers at different CO₂concentrations (350, 700 and 2,000 μL·L-1). I-214 has stomata responding to environmental conditions in normal ways and Peace has unresponsive stomata to environmental factors including light, ABA, water stress and CO₂. In both plants, elevated CO₂ stmulated the growth of plant parts, especially leaf dry weight. And a CO₂ enrichment of 700 μL·L-1 CO₂ caused increment of net assimilation rate (NAR). The growth responses of these plants to CO₂ enrichment were different especially at high CO₂ condition (2,000 μL·L-1 CO₂). The total dry weight in Peace increased up to 2,000 μL·L-1 CO₂ but not in I-214. A CO₂ enrichment of 2,000 2,000 μL·L-1 CO₂ had little effect on NAR of I-214 but enhanced NAR of Peace. Although it is uncertain whether the different responses to CO₂ enrichment between I-214 and Peace resulted from the different properties of stomatal responses to long-term CO₂ treatment, the decrease in NAR is probably due in part to CO₂-induced stomatal closure in I-214 but not in Peace.

• Journal of Marine Bioscience and Biotechnology
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• v.11 no.2
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• pp.81-88
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• 2019

In this study, effects of nitrogen (N) and phosphorus (P) starvation on the cell growth and fatty acid (FA) production of newly isolated freshwater microalgae were investigated. The microalgae were identified as Chlorella sp. and Parachlorella sp. through 18S rRNA sequencing. Optimal culture temperature and light intensity were investigated using a high-throughput photobioreator, and the result was validated in 0.5 L bubble column photobioreactors using BG-11 without NaNO₃ and/or K₂HPO₄. Under nutrient starvation conditions, total FA contents of the microalgae were significantly changed rather than FA composition. Starvation of both N and P was most effective for increasing FA contents in Parachlorella sp (24.4±0.1%) whereas highest FA contents (42.6±1.8%) was achieved when only P was starved in Chlorella sp. among tested conditions. These results suggest an effective strategy for increasing FA production from microalgae using appropriate nutrient starvation.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.250-253
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• 2007

An evaporated Ti/Pd/Ag contact system is most widely used to make high-efficiency silicon solar cells, however, the system is not cost effective due to expensive materials and vacuum techniques. Commercial solar cells with screen-printed contacts formed by using Ag paste suffer from a low fill factor and a high shading loss because of high contact resistance and low aspect ratio. Low-cost Ni and Cu metal contacts have been formed by using electroless plating and electroplating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Ni/Cu alloy is plated on a silicon substrate by electro-deposition of the alloy from an acetate electrolyte solution, and nickel-silicide formation at the interface between the silicon and the nickel enhances stability and reduces the contact resistance. It was, therefore, found that nickel-silicide was suitable for high-efficiency solar cell applications. The Ni contact was formed on the front grid pattern by electroless plating followed by anneal ing at $380{\sim}400^{\circ}C$ for $15{\sim}30$ min at $N_{2}$ gas to allow formation of a nickel-silicide in a tube furnace or a rapid thermal processing(RTP) chamber because nickel is transformed to NiSi at $380{\sim}400^{\circ}C$. The Ni plating solution is composed of a mixture of $NiCl_{2}$ as a main nickel source. Cu was electroplated on the Ni layer by using a light induced plating method. The Cu electroplating solution was made up of a commercially available acid sulfate bath and additives to reduce the stress of the copper layer. The Ni/Cu contact was found to be well suited for high-efficiency solar cells and was successfully formed by using electroless plating and electroplating, which are more cost effective than vacuum evaporation. In this paper, we investigated low-cost Ni/Cu contact formation by electroless and electroplating for crystalline silicon solar cells.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.672-680
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• 2017

A solar photovoltaic system is composed of a module mounting structure, supporting trunk, and a control unit that supplies generated electrical power to an external power grid or a load. The efficiency of the system depends on the incident solar light, so the mounting structure is installed to face the sun. However, because the sun always moves, systems that track the sun have better efficiency than fixed systems. The structure experiences wind pressure, snow load, seismic load, and structure weight. The wind pressure has the most serious effect on the structure. The pressure was obtained using finite element method for various gaps between modules and angles between the panel and the ground. The wind pressure is lowest when the gap is zero, and it increases with the inclination angle. Based on the results, a mounting structure module was designed.

• Journal of the Korean Ceramic Society
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• v.42 no.8 s.279
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• pp.554-560
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• 2005

The engineering ceramic needs the properties of high strength, hardness, corrosion-resistance and heat-resistance in order to withstand thermal shock or applied nonuniform stresses without failure. The densely coated porous ceramics can be used for machine component, electromagnetic component, bio-system component and energy-system component by their high-performances from superior coating properties and light-weight characteristics due to the structure including pore by itself. In this study we controlled the porosity of silica and alumina, $8.2\~25.4\%$ and $23.4\~36.0\%$, respectively, by the control of sintering temperature and starting powder size. We made bilayer structures, consisting of a transparent glass coating layer bonded to a thick substrate of different porous ceramics by a thin layer of epoxy adhesive, facilitated observations of crack initiation and propagation. The elastic modulus mismatch could be controlled using different porous ceramics as the substrate layer. Then we applied 150 N force using WC sphere with a radius of 3.18 mm by Hertzian indentation. As a result, the crack initiation in the coating layer was delayed at lower porosity in the substrate layer, and the damage in the coating layer was relatively smaller at the bilayer structure coated on higher elastic substrate.

• Journal of Families and Better Life
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• v.31 no.5
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• pp.47-63
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• 2013

This study deals with a counseling case in which a mother requested counseling due to the problems of her daughter, who suffers from multiple tic disorder. The participants of this study included five family members (grandmother, father, mother and two female children) and a total of 23 sessions were held from September 2006 to December 2007. Additional counseling ($24^{th}$ counseling session) was conducted on April 1st, 2009. The data was based on recorded transcripts and notes from 24 family therapy sessions. The study used a constant comparative analysis, which uses matrix and network display as an analysis method suggested by Miles&Huberman(1994). The characteristics of the family of origin and the indifference of the husband had caused the wife stress. The couple had frequent conflicts due to dysfunctional communication methods, a clash of values, sexual dissatisfaction, and a lack of communication. This marital conflict became the primary factor of the daughter's multiple tic disorder. Intervention of the family therapist resulted in the setting of treatment goals based on MRI's communication theory and Bowen's family systems theory in order to solve the problem of the daughter's multiple tic disorder. Also, the therapist's intervention techniques included exploring experiences with the family of origin, shedding light on the multigenerational transmission process, exploring dysfunctional attempts at solutions, the therapist's self-disclosure, providing similar cases, dealing with resistance, and suggesting a new communication method. To solve the problem, the therapist helped the family separate the daughter spatially from her parents. Therefore, the therapist's intervention helped reduce the daughter's tics and improve relationships among the family.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.414-414
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• 2008

Vertically well-aligned Ga-doped ZnO nanorods with different Ga contents were grown by thermal evaporation on a ZnO template. The Ga-doped ZnO nanorods synthesized with 50 wt % Ga with respect to the Zn content showed maximum compressive stress relative to the ZnO template, which led to a rapid growth rate along the c-axis due to the rapid release of stored strain energy. A further increase in the Ga content improved the conductivity of the nanorods due to the substitutional incorporation of Ga atoms in the Zn sites based on a decrease in lattice spacing. The p-n diode structure with Ga-doped ZnO nanorods, as a n-type, displayed a distinct white light luminescence from the side-view of the device, showing weak ultraviolet and various deep-level emissions.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.384-391
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• 2020

Due to its characteristics of light weight, high energy density, good safety, long service life, no memory effect, and environmental friendliness, lithium-ion batteries (LIBs) are widely used in various portable electronic products. The capacity and performance of LIBs largely depend on the performance of electrode materials. Therefore, the development of better positive and negative materials is the focus of current research. The application of metal organic framework materials (MOFs) derivatives in energy storage has attracted much attention and research. Using MOFs as precursors, porous metal oxides and porous carbon materials with controllable structure can be obtained. In this paper, rod-shaped Co-MOF-74 was grown on Ni Foam (NF) by hydrothermal method, and then Co-MOF-74/NF precursor was heat-treated to obtain rodshaped Co₃O₄/NF. Ni Foam was skeleton structured, which effectively relieved. The change of internal stress changes and destroys the structural volume of the electrode material and reduces the capacity attenuation. Co₃O₄/NF composite material has a specific discharge capacity of up to 1858 mA h/g for the first time, and a reversible capacity of up to 902.4 mA h/g at a current density of 200 mA/g, and has excellent rate and impedance performance. The synthesis strategy reported in this article opens the way to design high-performance electrodes for energy storage and electrochemical catalysis.

• Journal of the Korean Home Economics Association
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• v.18 no.4
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• pp.65-73
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• 1980

The purpose of this study is ti find out a desirable way to stability and improvement of household economy by studying the changes of consumption level and consumption pattern of urban salary and wage earners' households during the years from 1970 to 1978. For this study, "Annual Report on the Family Income and Expenditure survey" (Published by the Bureau of Statistics, Economics Planning Board) has been used as basic material, and the methods of analysis used here are the time series analysis. We have gained the results as follows: 1) From 1970 to 198, the total income level increased at the rate of 416.2% in nominal price, but only 74.4% in reql price, while the total expenditure level showed 338.5% increase in nominal price, but its real increased proved only 418.2% in consideration of inflation. APC decreased from 95.1%(in 1970) to 80.7%(in 1978). 2) As for the expenditure pattern for the above mentioned nine years, the rate of food expenditure increased until 1975 under the price influence, but it trended to decease there after on . The rate of housing expenditure showed a gradual increase while that of fuel and light expenditure was on the decrease. The rate of clothing expenditure had been on the decease until 1974 but it began to increase gradually thereafter on. The trend of miscellaneous expenditures was irregularly up and down, educational expences being the first rank among them, Non-living expenditure had been constant until 1974 but it decreased a little after that. From the results it was found that the consumption level of the salary and wage earners' household in all cities from 1970 to 1978 was not practically improved because of rise in prices, nor was the Engel's coefficient and the rate of miscellaneous expenditure changed distinctively. However, as the successive decrease of APC suggests the possibility of economic development, we must try to put stress on economy in consumption and on encouraging. This will help run our household economy in safety and stability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.7
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• pp.549-555
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• 2015

A measurement technique of interfacial velocity in air-water separated flow by particle tracking velocimetry using an infrared camera (IR-PTV) was developed. As infrared light with wavelength in the range of 3-5 um could hardly penetrate water, IR-PTV can selectively visualize only the tracer particles existing in depths less than 20 um underneath the air-water interface. To validate the measurement accuracy of the IR-PTV technique, a measurement of the interfacial velocity of the air-water separated flow using Styrofoam particles floating in water was conducted. The interfacial velocity values obtained with the two different measurement techniques showed good agreement with errors less than 5%. It was found from the experimental results obtained using the developed technique that with increasing air velocity, the interfacial velocity proportionally increases, likely because of the increased interfacial stress.