• Korean Journal of Soil Science and Fertilizer
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• v.8 no.3
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• pp.135-152
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• 1975

The following informations are known from physical and chemical characteristics of orchard soils and nutritional diagnosis of orange leaves in Jeju. 1. Most orange orchards are located on terrace and cindercone thus soil moisture and microclimate of an orchard will greatly be affected by its topography. 2. Excessive well drainage, shallow soil depth, high content of gravels, low solid phase ratio and strong wind will give severe problem of soil moisture and wind errosion, thus the exte- nsion of soil depth is necessary for maintain nutrients, water and sufficient root volume. 3. Available soil water was significantly and positively correlated with organic matter content and clay content also contributes to available soil water. Vinyl mulching was greatly helpful for soil water conservation, wind errosion prevention, soil temperature increases during winter. 4. Abundant amphoteric amorphous allophane take a key role to fix phosphorus and also rations and thus it is the major factor to determine fertilizer efficiency. Lime and phosphorus must be applied in deeper soil layer. Release of filed phosphorus must be reevluated for availability. 5. Organic matter such as see weeds will greatly increase fertilizer efficiency and low fertilizer efficiency during spring may be related to available soil water. 6. Nitrogen was in superoptimum and Mg was enough but P and Ca were somewhat deficient according to leaf analysies while K was deficient according to fruit analysis. Phosphorus application increased sugar/acid ratio and potassium decreases rind percentage. 7. Manganese deficiency and toxicity appeared in a few places. Iron and boron were enough. Most places showed tendency of copper excess but some places showed copper deficiency. 8. Soiling after elimination of rock base, application of slow release fertilizer and abundant organic matter, vinyl mulching and drip irrigation will increase fertilizer efficiency greatly and fruit yield drastically.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.3
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• pp.57-62
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• 2017

In the process for preparing Ag-coated Cu flakes by electroless silver plating using hydroquinone reducing agent, Ag coating qualities were compared by changing various process parameters such as type of pretreatment solution, plating temperature, pH of plating solution, type and injection rate of plating solution, and pulp density. Effective pretreatment solution for removing the oxide layer on a Cu flake was preferentially suggested. The conditions of low plating temperature, pH value of 4.34, slow injection rate of Ag plating solution, elimination of deionized water in the Ag plating solution, and high pulp density significantly suppressed the formation of separated tiny Ag particles, and thus the surface coverage of Ag coating on Cu flakes was enhanced.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.25-31
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• 2017

This paper presents a 270/540/750/1500-Mb/s serial-data transmitter realized in a $0.13-{\mu}m$ CMOS technology for the applications of video data transmission. A low-cost RG-58 copper cable(5C-HFBT-RG6T) is exploited as a transmission medium connected to a single BNC connector, which shows cable loss 45 dB in maximum at 1.5 GHz. RLGC modeling provides an equivalent circuit for SPICE simulations of which characteristics are very similar to the measured cable loss. The loss can be compensated by pre-emphasis at transmitter and equalization at receiver if needed. Measurements of the proposed transmitter chip demonstrate the operations of 270-Mb/s, 540-Mb/s, 750-Mb/s and 1.5-Gb/s, and provide the output voltage levels of $370mV_{pp}$ at 1.5 Gb/s even with the pre-emphasis turned-off. The total power consumption is 104 mW from 1.2/3.3-V supplies and the chip occupies the area of $1.65{\times}0.9mm^2$.

• Journal of Nutrition and Health
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• v.39 no.7
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• pp.692-698
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• 2006

The voluntary addition of vitamins and minerals to the appropriate foods may help reduce the risks associated with low intakes of these micronutrients, yet the potential of excessive intake, particularly for persons consuming very large amount of foods needs to be addressed. Using the Flynn's model to estimate the level of each vitamins and minerals that can be added safely to foods, maximum levels of fortification to conventional foods per 100 kcal portion were estimated. Critical factors in the Flynn's model included tolerable upper intake level (UL), each micronutrient intake at the $95^{th}$ percentile, the proportion of fortified foods in the diets of individuals, the proportion of foods to which micronutrients could be practically added, and a range of estimates for fractions of foods which might be actually fortified in each nutrient. Food vehicles included all foods except for fresh foods and alcoholic beverages, in general. With fortification of 50% of all potentially fortifiable foods, micrornutrients could be added safely to foods at levels per 100 kcal 1) > 100% Recommended Intake (RI) for vitamin $B_12$, 2) 1,200% RI for vitamin $B_1$ and niacin, 3) 1,000% $B_1$ for vitamins $B_2$ and $B_6$, 4) 400% RI for vitamin E, 5) 30% RI for calcium, 6) 20% RI for folic acid, iron and zinc, 7) 10% RI for manganese, 8) no fortification for magnesium, phosphorous and vitamin A, and 8) further consideration of vitamin D, copper and selenium due to insufficient evidence. Results of this study suggests a wide range of vitamins and minerals that can be added safely to foods in current diets of Koreans.

• Journal of the Korean Chemical Society
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• v.39 no.3
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• pp.186-190
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• 1995

A simple procedure, readily available at low cost with a sensitivity sufficient to determine trace levels of iron in seawater is proposed, which utilizes adsorptive accumulation of the iron/catechol complex on the mercury drop electrode in a borate medium of pH 8.0. Optimal conditions include a solution concentration of 2 mM catechol, 2.5 mM borate and a pH of 8.0, an accumulation potential of - 0.25 V is applied for 1∼3 min, and the potential scan is in the differential pulse mode. The limit of detection is 1.5 nM Fe using a preconcentration time of 3 min. The interference from copper can be eliminated and baseline slope is greatly improved, because its peak is well separated from that of iron in the proposed medium.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.57-62
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• 2014

Using flexible bismaleimide-triazine co-polymer as a substrate, inkjet-printed Cu films were also investigated for low-cost and process feasibility of flexible electronics. After annealing at $200^{\circ}C$ for 1 h under various reducing ambient, surface color was changed to red and electrical resistivity was decreased to the level of conductor under formic acid ambient. However, its resistivity was much higher than conventional copper films due to surface crack. In order to reduce the residual film stress after annealing, additional isothermal treatment was inserted before anneal hiring the stress relaxation applied in processes of amorphous materials. As a result, no surface crack was observed and electrical resistivity of $3.4{\mu}{\Omega}cm$ was measured after annealing at $230^{\circ}C$ with stress relaxation while electrical resistivity of $7.4{\mu}{\Omega}cm$ was observed after normal annealing without relaxation. The effect of stress relaxation was also confirmed by observing surface crack after decreasing the relaxation time to 0 min.

• Journal of Energy Engineering
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• v.19 no.4
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• pp.234-239
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• 2010

Heat transfer characteristics were experimentally investigated for ice slurry which was made from 6.5% ethylene glycol-water solution flowing in the circular pipe. The test section was made of a copper tube of 13.84 mm inner diameter and 1,500 mm length. The ice slurry was heated by passing hot water through an annulus surrounding the test section. The ice packing factor(IPF) and the mass flux of the experiments were varied from 0 to 25% and from 1,000 to 3,000 kg/$m^2s$ respectively at a fixed hot water temperature and flow rate. The measured heat transfer rates increase with the mass flow rate and IPF; however the effect of IPF appears to be minor at high mass flow rate. At the low mass flow rate condition, a sharp increases in the heat transfer coefficient was observed when the IPF was above 15 ~ 20%. And finally the measured heat transfer coefficients were compared with those calculated from the correlations.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.431-445
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• 1993

The purpose of this study was to observe corrosion characteristics of six dental amalgams and was to analyse corrosion products electrochemically. After each amalgam alloy and Hg was triturated as the direction of the manufacturer by using mechanical amalgamator, the triturated mass was inserted into the cylinderical metal mold ($12{\times}10mm$) and was condensed with 160kg/$cm^2$ by using the hydrolic press. The specimen was removed from the mold and was stored at room temperature for 1 week, and was polished with amalgam polishing kit. The anodic and cathodic polarization curve was obtained by using cyclic voltammetric method with 3-electrode potentiostat in saline for each amalgam and Ag, Sn, Cu plate specimen at $37{\pm}0.5^{\circ}C$. The potential sweep range was -1.7V~0. 4V(vs SCE) in working electrode and scan rate was 50mV/s and the exposed surface area of each specimen to the electrolytic solution was $0.79cm^2$. The results were as follows. 1. In anodic-cathodic polarization curve of amalgam specimens, two anodic current rising areas and two cathodic current peaks were obtained at the low Cu amalgam(CF, CS) specimen and three anodic current rising areas and three cathodic current peaks were obtained at the high Cu amalgam (TY, DS, HV) specimen. 2. As this compared with the anodic and cathodic current peak potentials of Sn, Cu and Ag specimen, the first cathodic current peak I c was caused by the reduction of divalent tin salt, second cathodic current peak IIIc results from the reduction of quadravalent tin salt, and third cathodic current peak me results from the reduction of copper salt. 3. As reverse potential sweeping was done repeatedly, anodic current was decreased slightly in all amalgam specimens.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.90-97
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• 2018

As the result(also after it's been carried out the damping force test with 800ea lateral dampers of 50ea trainset from entering heavy maintenance workshop to implement heavy maintenance inspection cycle, there were 86.25%(650ea) which were out of $350kg{\pm}15%$ of the standard value of damping force compared to the reference value. After the implementation of heavy maintenance inspection cycle, it's been examined damping force test with total samples 32ea(samples 8ea per a trainset) from actual running EMU 4ea trainset. As the result, percent defective was 84.4%(27ea), which was a very high level. System. The lateral damper's the failure cause of damping force defective was oil leakage caused by tearing crack of oil seal and foreign material in oil iron 473 ~ 1932 times higher than that of new oil, copper 36 ~ 98 times higher than that of new oil reduced oil amount cycling damping valve. It resulted from the change cause of damping force. In the static analysis on the shape of lateral damper oil seal's the existing and improved product, the stress of the improved product was smaller than that of the existing product. In the fatigue analysis, the existing product showed a low life in the upper area. However, in case of the improved product, it could be confirmed that the destruction did not occur up to the specified 1.0e + 006 cycles and the lifetime was further improved in most areas.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.222-222
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• 2012

Metal oxide gas sensors based on semiconductor type have attracted a great deal of attention due to their low cost, flexible production and simple usability. However, most works have been focused on n-type oxides, while the characteristics of p-type oxide gas sensors have been barely studied. An investigation on p-type oxides is very important in that the use of them makes possible the novel sensors such as p-n diode and tandem devices. Monoclinic cupric oxide (CuO) is p-type semiconductor with narrow band gap (~1.2 eV). This is composed of abundant, nontoxic elements on earth, and thus low-cost, environment-friendly devices can be realized. However, gas sensing properties of neat CuO were rarely explored and the mechanism still remains unclear. In this work, the neat CuO layers with highly ordered mesoporous structures were prepared by a template-free, one-pot solution-based method using novel ink solutions, formulated with copper formate tetrahydrate, hexylamine and ethyl cellulose. The shear viscosity of the formulated solutions was 5.79 Pa s at a shear rate of 1 s-1. The solutions were coated on SiO2/Si substrates by spin-coating (ink) and calcined for 1 h at the temperature of $200{\sim}600^{\circ}C$ in air. The surface and cross-sectional morphologies of the formed CuO layers were observed by a focused ion beam scanning electron microscopy (FIB-SEM) and porosity was determined by image analysis using simple computer-programming. XRD analysis showed phase evolutions of the layers, depending on the calcination temperature, and thermal decompositions of the neat precursor and the formulated ink were investigated by TGA and DSC. As a result, the formation of the porous structures was attributed to the vaporization of ethyl cellulose contained in the solutions. Mesoporous CuO, formed with the ink solution, consisted of grains and pores with nano-meter size. All of them were strongly dependent on calcination temperature. Sensing properties toward H2 and C2H5OH gases were examined as a function of operating temperature. High and fast responses toward H2 and C2H5OH gases were discussed in terms of crystallinity, nonstoichiometry and morphological factors such as porosity, grain size and surface-to-volume ratio. To our knowledge, the responses toward H2 and C2H5OH gases of these CuO gas sensors are comparable to previously reported values.